[Lysine resorption in rats fed on heated casein]. Male Wistar rats six month old were fed on a diet containing 10% casein heated for 4 h at 140 degrees C; control rats got untreated casein. The content of available lysine (as determined according to RAO et al.) was 5.8 g/16g N in heated and 8.5 g/16 gN in untreated casein. The contents of free and total lysine and of epsilon-DNP-lysine were estimated in deproteinized portal blood plasma and in urine. In the former the contents of the remaining amino acids before and after acid hydrolysis were also determined. Deproteinized portal blood plasma of rats fed on untreated or heated casein contained, respectively, un mumoles per 10 ml: total lysine 9.0 and 9.9; free lysine 3.7 and 2.8; bound lysine (total lysine -free lysine) 5.3 and 7.1; peptide-bound lysine (determined as epsilon-DNP-lysine) 4.9 and 4.6; and epsilon-bound lysine (bound lysine - peptide-bound lysine) 0.5 and 2.6. The data indicate that lysine with blocked epsilon-amino group was released in the course of digestion of the heated casein and absorbed. This is additionally substantiated by the presence of this form of lysine in the urine of rats given heated casein.


[Studies on the 14C-15N-acetamide turnover in sheep. 1. Studies on the 14C turnover]. 4 male sheep (average weight: 53.5 kgs) were fed a semisynthetic diet containing acetamide as sole source of nitrogen. At the beginning of the trial twin-labelled 15N-14C-acetamide was administered by way of a ruminal fistula. The curve pattern of 14C activity in the TCE-soluble fraction of the ruminal fluid showed a synchronous behaviour in all animals beginning at 3 hours after the beginning of the trial. A half-life of 2 1/2 hours for the rate of absorption of 14C acetamide and deaminated 14C acetate was established from the decline in 14C activity observed in the TCE-soluble fraction of the ruminal fluid. The peak level of 14C labelling in ruminal proteins was reached after 6 hrs. The specific 14CO2 activity in respiratory  air reached its maximum level after 4 hrs, and was then found to decline continuously. 56% of the administered amount of 14C was excreted over a period of up to 50 hrs after beginning of the trial. The very fact that the peak level of 14C activity was observed to appear in the TCE-soluble fraction of the blood plasma as early as after 1 hr seems to indicate that acetamide is also absorbed through the ruminal wall. The half-life of decline in the 14C activity of this fraction was 5.7 hrs. Analysis by thin layer chromatography showed that 75% of this amount of activity is present in 14C acetamide. The rate of 14C incorporation into blood plasma proteins reached a plateau region after 21 hrs, which was also maintained on the 2nd day of the experiment. 6.5% of the administered amount of 14C activity was excreted in the urine until the 7th day of experiment. 76.6% of the amount of urinary 14C activity excreted within a period of 48 hrs were voided as 14C acetamide. 3.8% of the administered amount of 14C activity was excreted with the faeces within the first 6 days of experiment.


[Studies on the protein and amino acid metabolism of laying hens using 15N labeled casein. 4. Fecal excretion of nitrogen and amino acids, digestibility of crude protein and absorption of basic amino acids]. Generally, the faeces of laying hens fed 15N casein rations were found to contain equal proportions of TCE-precipitable and TCE-soluble nitrogen. Considerable variations were observed to occur between the 64 samples investigated (27%-75%) and no explanation was found to account for this fact. The content of basic amino acids in faecal proteins was found to differ considerably from that of the proteins in the intestinal contents. A high lysine content was found after the feeding of wheat. The present trial substantiated this result, provided the casein contained a certain proportion of non-available lysine. The apparent and true digestibility of dietary N was 88% or 91%, that of 15N (2nd and 6th day of experiment) and 92%. During the feeding of labelled casein a higher level of N labelling was found in the TCE-soluble portion of the faeces, whereas on the 8th to 12th day a higher level of labelling was observed in the TCE-precipitable portion of the faeces. The peak of 15N excretion occurred on the 3rd day of experiment. When 15N administration terminated the atom% 15N in the faeces and in urine was found to decrease rapidly approximating the initial level of labelling asymptotically.


[Determination of feeding value based on simple food characteristics. 1. Determination of the digestibility of green foods and their preservation products]. Regression techniques may be used to establish close relations between the crude fibre content and digestibility data of organic materials (total digestibility). It was shown from regression equations calculated for a number of feedingstuffs that the total digestibility of a feedstuff may be calculated, with a sufficient degree of accuracy, from the crude fibre content of the material. The range of variations from most of the digestibility data obtained for various feedstuffs, was clearly below the limit given (2.5%). When regression equations are used the variation limits should always be indicated for which they had been established. Differences within the different groups of feedstuffs are so small that in many instances, the same equation may generally be used for feedstuffs of the same group. Similarly, equations for calculating digestibility values may be derived on the basis of the lignin content of a material, although the range of variations will, in this case, be wider when compared with the crude fibre content. The reason for this must be seen in the greater uncertainty of the lignin method. Analogous regression equations may be found for the different conserving products of green feeds, in which certain alterations have to be made corresponding to the different methods of conserving used. On the one hand, these are accounted for by changes in the crude fibre content brought about by biochemical reactions during the conserving process on the other hand a special influence of conserving form can be observed. The content of digestible crude protein in green feeds can be established, with a high degree of accuracy, from the crude protein content of the material. The content of digestible organic matter can be calculated from the digestibility of organic matter and from the ash content of the material. The content of digestible organic matter is, in turn, closely related to the content of energetic feed units in a particular material.


[Studies on the 14C-15N-acetamide turnover in sheep. 2. Studies on 15N turnover and comparative studies on the 14C turnover]. Three fistula sheep with average weights of 52.2 kgs were given 37.9 g of 15N and 14C labelled acetamide (= 1.09 mg 15N' and 0,95 mCi14C) which were administered directly through the fistula. The half-life period of 15N retention in the ruminal fluid (TCE soluble portion) was found to be 4 hrs. 18 hrs after 15N administration increasing amounts of 15N were carried back to the rumen by way of the rumino-hepatic circulation. The 15N concentration in the blood (TCE soluble portion) rapidly increased up to a peak value and, from 3 hrs after isotope administration, the 15N concentration was found to decline continuously, with a slight discontinuation at about the 10th hr of experiment. The rate of 15N incorporation into the protein fraction (TEC soluble portion) of the blood was delayed by 4 hrs, relative to the rate of 15N incorporation into ruminal proteins. An average of 43.1% of the administered amount of 15N was excreted in the urine within 7 days. Up to the 4th day of experiment the half-life period of urinary 15N excretion was 19 hrs. An average of 15% of the administered total amount of 15N was excreted in the faeces. In this process, the peak values in both TCE fractions were observed to occur on the 2nd day of experiment. The proportion of isotope in the TCE soluble fraction was found to increase continuously compared with the total amount of the isotope excreted in the faeces. Isotope concentrations between 0.03 and 0.13 atom% of surplus 15N were found in organ and muscle tissues of a sheep that had been slaughtered 7 days after administration of the isotope. The results obtained are discussed on the basis of comparisons made with the analogous behaviour of 14C activity.


[Studies of the influence of nutritional factors on the ruminal mucosa. 1. Structure and functional state of the ruminal mucosa after feeding of extreme rations and abrupt change in nutrition]. Different rations were used in successive experimental periods (Dried green feeds (I), fresh green feed from sugar beet tops (II), concentrates (III, IV), and maize silage (V), to test the effect they have on the structure and oxidative functions of the ruminal mucosa in cattle. Rations I, II, IV, and V were both energy and protein equivalent. Biopsy specimens from ruminal papillae were taken on the day when rations were suddenly changed and on the 21st and 22nd day of the feeding period; they were then investigated histologically and manometrically. It was found that some characteristics, (viz. the type and thickness of the stratum corneum, the thickness of epithelia, the size of cell nuclei in the stratum basale of the epitheliumas well as the state of the lamina propria and the oxygen uptake were subject to alterations depending on nutrition. Nutrition with energy-equivalent, but otherwise extremely different diets representing particular types of rations led to the development of different and quite specific functional states of the ruminal mucosa. All these functional states of the mucosa were found to be within the limits of normality but seemed to have a definitely more favourable functional effect in the case of rations I and IV than in the case of rations II and V. The feeding of concentrates (III, V) increased the energy intake to an amount of 6.6 kEFr, i.e. double that of the other rations, and brought about changes in quantitative parameters. These, in turn, indicated that proliferative and oxidative processes had been stimulated. Changes of this kind were accompanied by increases in the concentration of volatile fatty acids in the ruminal fluid which rose from a maximum of 9 mMol per 100 ml (ration IV) to 12.5 mMol per 100 ml (ration III). Immediately after any change in nutrition brought about by a change of rations, processes of adaptation occurred in the ruminal mucosa. A balanced state of the mucosa was again achieved after a period of not more than 3 weeks.


[Trace element supply to ruminants in the German Democratic Republic. 2. Supply of copper]. The supply of copper to ruminants as influenced by and depending on the geological origin of soils was investigated in different parts of the GDR by using the hair test. Red clovers (meadow clover and field clover) were used as indicator plants. The following results were obtained: Data on the Cu content of clovers grown on soils of the same geological origin were found to correlate with r = 0,81. After eliminating the effects of Cu antagonists resulting from industrial pollution it was possible to establish numerical relations (B = 0.39 and B = 0.89) between the relative values (specific for the particular location) for the Cu content of the indicator plants and the percentage of cows suffering from Cu deficiencies (6.0 and 5.0 ppm Cu in hair). The lowest percentages of Cu supply to the ruminants (established on the basis of the Cu content of red clovers) were found on diluvial sandy soils, glacial loams and peat and bog soils whereas the highest percentages of Cu were found on weathered soils (of phyllite, gneiss, shell limestone, red marl soils and porphyry). Secondary Cu deficiencies in ruminants may arise, independent of the geological origin of the soil material, in places exposed to the main direction of the winds from major industrial areas (emission of SO2, Cd and Mo). Due to primary and/or secondary deficiencies the supply of Cu to ruminants in various locations (syenite, granite, red sandstone, gneiss, loess; peat soils, diluvial sandy soils) may be insufficient. A detailed description is given of areas where Cu deficiency is likely to occur and recommendations are given on how to use mineral mixtures containing a high proportion of Cu (1.00 g Cu per kg).


[Substitution of protein feed through lysine-supplemented high-protein wheat during the breeding and laying period of hens. 1. Problems, analytical methods used and results obtained in the chick period]. Different parameters were investigated in a trial carried out for the 8-week chick period with an experimental group receiving a protein feed in which 7% of the feed, relative to that of the control group, was replaced by protein-rich wheat. Values for consumption were higher in the controls than in the experimental chicks because of the lower energy content of the ration. Statistically well-established data were obtained indicating that the amounts of crude protein, lysine and sulfur-containing amino acids consumed per unit of weight gain were lower in the experimental group than in the control group. Total body analyses showed that the bodies of the control birds contained more crude protein (alpha less than 0.05) and less fat (alpha less than 0.001). The rate of mortality during the 8-week chick period was 1.1% in the control group and 0.5% in the experimental group.


[Studies on reducing the crude protein content of feeds fed to chicks and young hens (laying stock)]. 2 rearing trials were carried out on a total of 8550 hybrid chicks (White Leghorn) to investigate in which way food mixtures containing reduced levels of crude protein (supplemented or unsupplemented with amino acids) might influence the growth of chicks and young hens. Decreases from 21.5% to 16.5% in the crude protein content of chicken feed and from 15% to 13% in feeds feed to young hens (greater than 8 weeks of life) did not reduce the live weight of birds at the end of the rearing period to any appreciable extent. No clearly defined differences were found to exist between the different types of feed tested concerning the amount of food and energy consumed per unit of weight gain and the mortality rate among the birds; it was shown, however, that the demand for crude protein per unit of weight gain was clearly reduced in birds reared at the lower crude protein level. For young hens receiving the diet poorer in protein the date when the birds began laying was slightly delayed. Otherwise, no statistically significant differences were found to exist between the young birds fed varying levels of crude protein, concerning the age at 50% laying performance and other parameters that are characteristic of the entire laying period (laying performance, weight of individual eggs, food consumption, mortality, fertilization of hatching eggs, hatchability of eggs). It appears that the feeding of a reduced protein diet to chicks and young hens (laying stock) did not have any detrimental effect on the growth and later laying performance of the birds. Apart from the fact that the demand for protein feeds is considerably reduced during the rearing period the costs of feeding per bird can also be cut down.


[Determination of feeding value on simple food characteristics. 2. Determination of food energy value of green feeds]. Regression analyses had been made to find interrelationships between the crude fibre content and the EFr content of green feeds. Regression equations were obtained from these analyses which were used to calculate the EFr values, with a sufficient degree of accuracy, from data on the crude fibre content. In these equations the b values were found to be by far more clearly differentiated than in the equations used for calculating digestibility values. These are apparently influenced by the composition of the feeds. The range of variations appears to be only slightly affected when we compare the data with those obtained in calculations made to established the total digestibility values. This is a fact that applies to both the green feeds and their conservation products. Studies investigating the relationships between the content of digestible organic matter (VOS) and EFr (as expressed by the conversion factor (see article) showed that the EFr data could be established, with a fair degree of accuracy, from the VOS values. The f values of the different feeds that were classified into particular groups of feeding-stuffs, were shown to agree fairly well; moreover, they were found to be largely independent of exogenic factors (such as vegetation and N fertilizing). Characteristic differences between the f values of the different conservation products and those of the green feeds were observed although these differences remained within narrow limits (1-3%), so that calculations can be made using only a few factors. When starch equivalents were taken into account it was found that the f values used in calculations for starch equivalents were clearly influenced by feed composition, which, in turn, was influenced by the particular effect of crude values in SE calculations. It is at this point that differences between the two systems of Food Evaluation become particularly apparent. The close relations existing between VOS and EFr values apply, first and foremost, to green feeds and their conservation products. Much wider differences in the f values of different feeds may be observed in the case of foodstuffs having a much more extreme composition. The f values of feedingstuffs with high protein content (e.g. blood meal) may be decreased down to a value of 0.7 while those of foodstuffs rich in fat (e.g. oil cakes or foodstuffs of animal origin containing a high percentage of fat) may be increased up to and over 1.4. In these cases, special circumstances have to be taken into consideration.


[Resorption and incorporation of radioactive labeled amino acids during administration of various protein carriers in rats. 1. Resorption of 14C leucine and 3H glycine after intragastric administration]. Male Albino rats (90-100 g) were fed ad libitum (with limited periods of feeding) for 14 days. The diets were adjusted to a crude protein content of 10%. Powdered whole egg, fish meal, yeast and gelatine were used as protein sources. Additionally, one group of rats was fed a protein-free diet. On the 15th day of experiment the rats were fed a test diet at a level of 2 g per 100 g of body weight. 2 hrs after that the rats received 25 muCi of 3H glycine and 5 muCi of 14C-L-Leucine per 100 g of body weight administered by way of intragastric infusion. It was found that a large proportion of the radioactive amino acids were absorbed as early as after 0.5 hr. The highest rate of absorption was observed in animals fed dietary proteins of poor quality or a protein free diet, so that in animals receiving a gelatine diet or a protein-free diet only 68.4% or 56.4% of the administered amount of 14C activity were detected inside the gastro intestinal tract after 0.5 hr. Analogous data for the 3H activity were 52.4% and 25.3%. Maximum absorption occurred after 3-7 hrs. Following this the level of radioactivity in the intestinal contents again increased reaching a peak value after 14-24 hrs; in the case of 14C activity this peak value amounted to 25.4% of the administered dose in animals fed the gelatine diet and 32.8% in the group receiving the protein-free diet. It was established that the major proportion of the resecreted amount of 14C activity was present in leucine. Until 72 hrs after the intake of 14C activity the level of radioactivity was again found to decline, a processes which was induced by processes occurring in the large intestines. Moreover, evidence was obtained in confirmation of previous findings, indicating that the composition of faecal amino acids was constant and unaffected by dietary proteins.


[Determination of the true digestibility of amino acids in variously prepared potatoes in growing pigs. 1. Freshly steamed potatoes and silage made from steamed potatoes]. Freshly Steamed Potatoes of 6 varieties were investigated. With 3 varieties the true N and amino acid digestibilities were found to be in good agreement, while great variations were found in potatoes of the other 3 varities so that it appears to be a matter of some doubt whether the true amino acid digestibility could, in the case of potatoes, be reliably derived from data on the true N digestibility. Differences in the true amino acid digestibility data were found between the varities of potatoes grown in different years. A positive trend was found to exist in the relationship between the absolute amino acid content and true digestibility. The true lysine digestibility of freshly steamed potatoes varies between 76-90%, the average percentage being about 80%. The true methionine digestibility was found to vary within still wider limits, although the average percentages was also about 80%. Values established for the true cystine digestibility ranged from 80% to 90%. The true amino acid digestibility data did not provide a sufficiently reliable basis for making conclusions as to the existence of a limiting amino acid. Both the lowest value for true digestibility and the greatest variations were found in the case of the amino acids alanine, tyrosine, and methionine. It was observed that silage made from steamed potatoes had a lower true digestibility of N than steamed fresh potatoes although the value for true amino acid digestibility were the same, with the exception of methionine and cystine.


[Studies on growing pigs to determine the true digestibility of variously prepared potatoes. 2. Technically dried potatoes]. There are two kinds of damage to potato proteins that may arise in the process of beat drying. Decreases in the gross lysine content are accompanied by a still much more pronounced depression of digestibility. If, for example, the gross lysine content of dried potatoes was only 50% of that of steamed potatoes then the average value for the true lysine digestibility was 15%; in some cases the content of truly digestible lysine was 0% when compared to that of steamed potatoes. Similarly, it was found that some types of dried potatoes with a dry matter content of about 88% had already lost about 43% of the truly digestible lysine contained in steamed potatoes.


[Influence of mechanical and thermal treatment of animal feed on the true digestibility of amino acids. 2. True digestibility of amino acids in treated horse beans]. Trials were performed to investigate in which way mechanical and/or thermal treatment of horse beans would have an effect on the harmful components that were shown to be present in horse beans. In the course of these trials amino acids from heat-treated horse beans (variety Fribo) were analyzed for their true digestibility. Apart from heat-treated horse beans the investigation included undecorticated and decorticated beans and a mixture of horse beans with spring barley.


[Supply of trace elements to ruminants in the German Democratic Republic. 3. Supply of zinc]. The supply of zinc to ruminants as influenced by and depending upon the geological origin of soils was investigated using the hair test and the technique of indicator plants. A total of 1276 samples of red meadow clover and 3022 samples of red field clover and 4184 hair specimens from cows were analyzed. The following statistically well-established results were obtained which appear to be generalizable: Red meadow clover contained significantly more Zn than red field clover (48 ppm/38 ppm). Red meadow clover and field clover grown on loamy soils (59%), weathered soils of less (59%), red sandstone (57%) basalt (53%), shell limestone (47%) and Keuper (41%) contained only 59%-41% of the amount of Zn found in indicator plants that were grown in locations were the highest Zn level (weathered soils of porphyry). Zn concentrations in red meadow and field clover grown on soils of the same geological origin correlated with r = 0.87. A positive correlation (B = 0.53) was found to exit between the relative proportions of Zn contained in indicator plants grown on a particular soil and the proportions of Zn contained in hair specimens from Zn-deficient cows (less than 100 ppm of Zn). The largest number of hair specimens containing less than 100 ppm of Zn were found in cows from areas with soils of basalt (17%), and loess (18%), areas with loamy soils (24%), and sandy diluvial soils (25%), or with alluvial pastures (23%), or with soils of Keuper (27%), shell limestone (22%) or red sandstone (29%). Ruminants in these areas are liable to suffer from Zn deficiencies.


[Determination of metabolism-oriented methionine requirements using 35 S methionine]. Experimental rats (weighing 50-100 gm) received semisynthetic diets containing 8%, 10%, or 12% of crude protein (Soya protein). These were supplemented with graded amounts of L- or DL methionine. After a 5-day feeding period the rats were injected 35S methionine. Subsequently, the levels of urinary 35S excretion were determined over a period of 4 days after methionine injection. The level of urinary 35S excretion was found to be clearly increased if methionine supplementation exceeded the methionine requirements of the animals. Supplementation with 0.15% methionine was just enough for diets containing 8-10% crude protein. 0.2% methionine had to be supplemented to meet the methionine requirements of the animals if the diet contained 12% crude protein. Requirements for the content of sulfur-containing amino acids in the protein were shown to be independent of the protein content of the diet, and were found to vary between 4.4% and 4.7% of the crude protein. The needs for methionine supplementation were independent of the fact whether L methionine or DL methionine was added. It is definite advantage of the present method that methionine demands are determined in close correlation with metabolic processes, including the maintenance metabolism.


[Resorption and incorporation of radioactive-labeled amino acids during the administration of various protein carriers in rats. 2. Uptake of radioactivity by tissues of the gastrointestinal tract after intragastric administration of 14C-L-U-leucine and 3H-glycine]. Male Albino rats (weighing 90-100 gms) were fed ad libitum for 14 days with limited periods of access to food. Powdered whole egg (V), fish meal (F), yeats (H), and gelatine (10% protein in dry matter) used as protein sources. Additionally, one group of rats received a protein-free (e). Radioactive tracers were administered by intragastric infusion of 25 mu Ci 3H glycine and 5 mu Ci 14C L-leucine per 100 gm of body weight 2 hrs after the feeding of 2 gm of the experimental diet per 100 gms of body weight. The level of uptake of radioactive tracers from the different sections of the gastro-intestinal tract was measurels of 3H and 14C labelling in intestinal tissues were observed 3 hrs and 7 hrs after infusion. The level of 14C labelling was found to be negatively correlated and the level of 3H labelling was positively correlated with the biological value of the diet. Intestinal tissues are capable of storing considerable amounts of 14C radioactivity. So, 72 hrs after infusion, the following levels of 14C radioactivity (expressed as percentage of the total dose of radioactivity) were found in tissues of the gastro-intestinal tract: whole egg: 8.4%, fish meal: 9.6%, yeast: 13.1%, gelatine: 14.9%; protein-free diet; 14.2%. The quotients correlating the levels of radioactivity from the intestinal contents with that found in the intestinal wall suggest that the walls of the small intestine possess a high capacity for absorption. At all times of radioactive measurements the walls of the small intestine were found to contain higher levels of both 14C and 3H radioactivity than the contents of small intestine.


[Resorption and incorporation of radioactive-labeled amino acids during administration of various protein carriers in rats. 3. Uptake of radioactivity by blood plasma, liver and muscular tissue and incorporation into tissue proteins after intragastric administration of 14C-leucine and 3H-glycine]. Growing male rats received diets of varying biological value (protein sources: powdered whole egg (V); fish meal (F); yeast (H); gelatine (G); protein-free diet (e)) for a 14-day feeding period. Subsequently, 14C leucine and 3H glycine were administered intragastrically. The level of uptake of 14C and 3H radioactivity into blood plasma, liver and muscular tissue and the rate of incorporation of the radioactive tracers into the proteins of these tissues was examined. A negative correlation was found to exist between the incorporation of radioactivity into liver proteins and the biological value of dietary proteins, the former being mainly dependent on the level of incorporation into the liver. For muscular proteins the rate of incorporation decreases with the decreasing biological value of the dietary proteins. This may be attributed to the fact that with poor protein nutrition the rate of protein synthesis in the skeletal muscles is also reduced. Comparative studies on the specific 14C radioactivity from free leucine made in the group on the protein-free diet and in the group receiving the whole egg diet showed that the leucine pool of the skeletal muscles was markedly redueced in animals fed a protein-deficient diet while the leucine pool in the liver remained comparatively constant.


[Relationship between the quality of dietary proteins and the functional status of the adrenal cortex. Variations in the content of transcortion, free corticosterone and total corticosterone in the blood plasma of rats fed with proteins of various quality]. Growing male Wistar rats were used to test in which way variations in the quality of dietary proteins (10% absorbable crude protein; casein supplemented with 4% methionine (K); casein/gelatine (1 : 3); maize gluten supplemented with 4 amino acids; and maize gluten) influenced the binding capacity of blood plasma for corticosterone, and the concentration of corticosteroid-binding globulin ("CBG"), total corticosterone, free corticosterone and albumin-bound corticosterone in blood plasma. The binding capacity of the blood plasma for corticosterone and the total concentration of corticosterone, CBG, free corticosterone and albumin-bound corticosterone were found to rise with the improving quality of the dietary proteins (r = 0.830). A close correlation was found to exist between the concentration of total corticosterone in the blood plasma and CBG. Increases in the total concentration of corticosterone in blood plasma are, in 84% of all cases, brought about by increases in CBG concentrations. In conclusion, reference is made to the significance which such results may have for the control of regulatory processes.


[Relationship between the quality of dietary proteins and the functional status of the adrenal cortex. 5. Content of corticosterone and cortisol in the liver and in the mucosa of the small intestine of rats fed with proteins of various quality (estimation of binding capacity for corticosteroids)]. Relationships between the Quality of Dietary Proteins and the Functional State of the Adrenal Cortex. (5) Content of Corticosterone and Cortisol in the Liver and in the Mucosa of the Small Intestine of Rats Fed Proteins of Varying Quality (Estimation of the Binding Capacity for Corticosteroids). Growing male Wistar rats were used to investigate in which way the quality of dietary proteins (maize gluten and maize gluten supplemented with amino acids) influenced the content of corticosteroids in the liver and in the mucosa of the small intestine of untreated rats (N), adrenalectomized animals (AE) and animals treated with corticosteroids (N + S). In AE animals the content of corticosteroids in the tissues was very low. In N + S animals of both dietary groups the mucosa of the small intestine contained more corticosteroids than the liver; the content of corticosteroids in the mucosa, however, was also found to vary in dependence upon the diet fed. The mucosa of N + S animals receiving dietary proteins of high quality contained more corticosteroids; this indicates a higher binding capacity of the mucosa for corticosteroids.


[Effect of changing fat and protein levels on various fundamental characteristics of lipid and protein metabolism in the blood serum and on the body composition of growing rats]. A total of 263 young rats received 6 different diets containing varying levels of lipids and proteins. After a feeding period of not less than 3 weeks the animals were killed in a fasted state or after feeding and the blood serum was investigated for total lipids, free fatty acids, cholesterol, urea, creatinine and insulin. The bodies of the animals were analyzed for crude fat und crude protein. The body proteins seemed to be hardly influenced whereas considerable variations were noticed in the values for body fat, although these were not found to be clearly related to the intake of dietary fat. Values for the content of total lipids, free fatty acids and cholesterol in blood serum were shown to be clearly dependent on the amount of fat ingested. In addition, it was observed that these processes were partly influenced by dietary proteins. The values for urea, creatinine and insulin were only slightly affected by dietary fat, but were markedly changed by dietary proteins. Differences in total lipids and cholesterol as discussed above were blurred or disappeared altogether when the animals were analyzed after food intake; on the other hand, it was shown, that dietary proteins had a statistically well-established effect on the values for urea and a marked influence on insulin values.


[Effect of zinc deficiency on glucose tolerance]. 18 male rats (Sprague Dawley) were divided into 3 groups each receiving the following amounts of dietary zinc: 2 mg/kg in the depletion group and 100 mg/kg in both the ad libitum-fed control group and in the pair-fed control group. After 34 days of experiment the rats were fasted for 12 hrs and then received 50 mg of glucose per 60 g of body weight injected into the femoral muscle. With equal intial glucose concentrations Zn-depleted rats exhibited a significantly reduce glucose tolerance compared with that of the ad libitum-fed control animals. The reduced glucose tolerance in the Zn-deficient animals does, in this case, not arise as a result of the reduced food intake and the resulting weakened condition of the animals. This was shown by results obtained with the pair-fed animals exhibiting a significantly more stable glucose tolerance than the Zn-depleted rats, which was even more rigid than that of the ad libitum-fed controls.


[Studies on the modification of methionine imbalance in rats through the supplementation of threonine, serine, glycine or glutamic acid]. Experimental rats were fed a basal diet containing about 10% of crude protein from casein which was supplemented with 5 g DL methionine per 100 g of food. Simultaneously, either threonine, serine, glycine or glutamic acid were added in amounts of 5 gms. After a 7-day feeding period the experimental animals were injected 35S-methionine. The animals were killed after an incorporation period of 24 hrs and the 35S activity measured in different organs and in the excreta. The pattern of body weight gains, and the values for 35S activity showed that glycine had reduced the toxic action of methionine. Threonine was shown to have a similar effect while, under the prevailing conditions, serine augmented the symptoms of toxocity. Definitely higher levels of 35S activity found in the residual carcasses after methionine or serine supplementation seem to suggest an increase in cystein formation in intermediary metabolism. This, in turn, delays the elimination of SH groups from the body so that as a result of this, a higher toxocity is observed.


[Studies on the influence of various vitamin-B6 uptake in the hen on the nutrient content of liver, pectoral muscle, total body and egg]. The present study included 2 trials which were performed to investigate in which way graded vitamin B6 supplies or vitamin B6 deficiency would influence the chemical composition of the whole body, the liver, pectoral muscle or the eggs of hens and in which way it might change the pattern of amino acid composition in the proteins of the pectoral muscle. The following results were obtained: No direct changes in the protein and fat content of the birds (total body, liver, pectoral muscle) were noted in trial 1 when graded amounts of vitamin B6 were supplied, whereas in trial 2 signifikant increases in the fat content of the body and decrases in the protein levels were observed when vitamin B6 supplements were added to a vitamin-deficient diet (pair-fed group) or fed to animals receiving increased amounts of food (controls). Variations in dietary vitamin B6 concentrations did not produce statistically significant changes in the protein and fat content of eggs, and in the pattern of amino acid composition of proteins in the pectoral muscle. However, with increasing vitamin B6 uptake, the serine to glycine ratio was narrowed.


[Results of chewing and ruminant activity of cows fed rations of cereal straw of various physical forms and after chemical treatment with sodium lye]. 3 trials were conducted with adult cows. The animals received different types of coarse fodder (straw, lucerne) which was subjected to chemical treatment (liquid NaOH) and mechanical treatment (pelleting, wafering); then, the chewing and ruminating activity of the cows was measured. Different criteria were used, i.e. movements of the jaws during food intake and rumination and number of regurgitated bits of food. On the average, one movement of jaws lasted 0.94 sec. and swallowing and regurgitation took 5.5 sec. From this, the duration of the rumination process was determined. No differences in ruminating activity were found between lucerne and chopped/chaffed food while the the case of wheat straw about 30% of additional ruminating activity was performed in comparison with pelleted lucerne and chaffed food. This structural effect was even a bit more pro nounced when the straw was first ground and then wafered. Preceding chemical treatment of the straw with liquid NaOH reduced the ruminating activity in the case of chopped food by 53%, with pellets by 40% and with straw pressed into blocks by 62%. The finess of the feed was in no case found to be related to rumination activities, while hardness of the food particles as well as physical and chemical treatment of the food had an importent influence on the rumination activity.


[Studies in male sheep on the feeding value of excreta from young hens and broilers]. 5 digestibility trials were carried out, each with 4 male sheep, to investigate the excreta of young hens and broilers produced as litter in hen batteries for rearing and fattening stock. Data on the digestibility of organic matter and energy of broiler excreta were 76.0% and 76.4%; i.e. these values were only slightly lower than those for the basal ration (barley + dried green lucerne: 76.6% and 76.8%). Digestibility coefficients for organic matter and energy content in the excreta of young hens were 69.4% and 70.4%, respectively. The protein digestibility of excreta of broilers and young hens was 82.3% and 84.3%; that is to say, the investigated dropping contained 330 g and 260 g of digestible crude protein per kg of dry matter. Due to the high ash content of the samples the energy content of the analyzed excreta was only 474 EFr and 421 EFr per kg of dry matter.


[Influence of thermal and mechanical treatment of animal feed on the true digestibility of amino acids. 3. Influence of pelleting coarsely-ground cereals on the true digestibility of amino acids]. It was found that different procedures of heat treatment influenced the true digestibility of nitrogen and of the amino acids in cereals. In view of the fact that under practical feeding conditions pelleting is the most widely used procedure studies were made in trials with young pigs fed coarsely ground barley or maize of pellets of these as sole diet.


[Metabolism of 15N-14C-acetylurea in the sheep]. 3 male sheep (phi 48.3 kg) were fed a semisynthetic diet containing acetyl urea as sole protein source and 15N-14C labelled acetyl urea (urea-C labelled) by intraruminal tube.  A half life period of 4 hrs was established for the removal of labelled acetyl urea from the TCE-soluble portion of the ruminal fluid. The degree of 14C labelling in ruminal proteins was very low whereas the extent of 15N labelled protein synthesis was quite marked reaching a maximum between the 18th and 24th hour of experiment. The steepest rise of 15N incorporation into ruminal proteins was found to occur between 8 to 12 hrs after start of the experiment, i.e. at the time of peak level of 15N returned from 15N urea via the rumino-hepatic circulation. 23.3% of the amount of 14C activity administered (mean of all 3 experimental animals) was excreted through respiration. The curve patterns of both isotopes in the TCE soluble portion of the ruminal fluid were similar to that of the degasified TCE soluble portion of the blood blasma. At the peak time (8 hrs) a concentration of the nitrogen isotope of about 4 atom% excess of 15N was observed. The level of 14C labeling in blood plasma proteins was insignificant when compared with that of 15N labelling. The ratio at the peak time was 1:10; the same ratio was found for ruminal proteins. From this it can be concluded that the process of labelling of blood plasma proteins proceeds mainly through microbial protein synthesis. Sheep I and III excreted an average of 60.6% of 14C activity and 57.0% of the administered excess of 15N in the urine. 6 hrs after the beginning of the experiment 81% of the amount of urinary 14C activity was found to occur as acetyl urea; after 48 hrs this amount had decreased to 50%. All experimental sheep excreted a urinary sediment consisting mainly of acetyl urea. The level of faecal 14C excretion (1.4%-2.9% of the amount administered) was considerably lower than that of 15N excretion (9.1%--15.6% of the administered dose). The TCE soluble fraction of the faeces contained up to 2% of the 14C dose and 3% of the 15N dose. The true digestibility data of 15N from 15N acetyl urea varied between 96.4% and 98.2%. An average of 40.9% was obtained for the 15N balance over the 7-day trial period.


[Qualitative and quantitative studies on the metabolism of fatty acids, in particular on that of linoleic acid in calves]. 24 calves of the breed "Deutsche Schwarzbunte Rasse" were used for qualitative and quantitative investigations on the metabolism of fatty acids, particularly that of linoleic acid. The trial comprised 6 calves in 4 groups. The experimental rations consisted of powdered skim milk, oat meal, milk sugar, coco fat and varying proportions of linoleic acid (1.0%, 1.5%, 2.5%). The control group received the basal ration without supplements of linoleic acid. After a short period of adjustment the metabolic trial was started with 9 periods each lasting 7 days. The composition of fatty acids in the faecal lipids was analysed by gas chromatography. The studies led to the conclusion that the fatty acids contained in the faecal fat were not immediately derived from the dietary fat. The results of the trial also showed that the major proportion of all the fatty acids present in the faecal lipids consisted of only 4 fatty acids, viz. oleic acid, palmitic acid, lauric acid and myristic acid. Changes observed for the content of linoleic acid in faecal lipids were negligible so that the assumption may be made that all of the linoleic acid added was completely digested.


[Effect of different types of rations on various characteristics of ruminal and intermediary metabolism in sheep. 1. Formation of volatile fatty acids]. Studies on Ruminal Physiology were made with 15 growing female Merino sheep to investigate the influence of different types of rations on the fermentation of volatile fatty acids. The rations were constructed of green feed, straw and concentrates (type 1) or chemically treated straw pellets + concentrates (type 2). One ration (type 3) consisted of concentrates only. With regard to the total concentration of acids ration 3 was significantly superior to the 2 other types of rations. Moreover, ration 3 produced a specific fermentation pattern of the volatile fatty acids. This was characterized by a significant reduction in the molar proportion of acetate compared with ration 1 and 2 and a significant increase in the level of propionic and valeric acid relative to ration 1. Differences in the fermentation pattern between rations 1 and 2 were mainly limited to differences in the absolute and molar proportions of propionate where the straw pellet rations in each case produced the significant higher values. The acetate to propionate ratio was narrowed in the order of ration 1-3 (4.1 :1, 3.1:1, 2.6-2.9 :1). Statistically wellestablished negative correlations were found to exist between the concentrations of volatile fatty acids and the pH values which were established simultaneously.


[Substitution of protein feed through lysine-supplemented high-protein wheat during the rearing and laying period of hens. 3. Effect of graded lysine doses on the crude nutrient content of carcasses and on the level of amino acids and GOT activity in the blood of young hens]. A large-scale trial was carried out under commercial conditions to investigate to which extent the feeding of rations with varying lysine content to young hens would influence the crude nutrient content of the body fractions and might change the pattern of amino acid composition and the activity of GOT in the blood. Four rations were fed each containing 14.2% crude protein, 626-633 EFh units/kg and 0.59%, 0.61%, 0.54% and 0.46% lysine. The crude protein and crude fat content of the total body and of body fractions were in no case found to be related to the feeding regime. The proportion of crude ash in the "remainder of non-utilizable parts", in "bones", "intestinal and abdominal fat", "ovaries" and "small intestine" decreased with the decreasing lysine content of the rations. The concentrations of free lysine, histidine, arginine, and phenylalanine in the deproteinized blood plasma of the young hens were significantly (a = 0.01) lower in the birds of the lysine deficient group than in the hens of the other groups. Positive regressions were calculated for the lysine content or the content of aspartic acid in the ration and the pattern of free amino acids in blood plasma. Positive and negative linear relationships were found to exist between the concentrations of free lysine, and those of histidine, arginine or threonine, and serine. A close correlation existed between the total amount of essential amino acids in blood plasma and the lysine concentrations of the plasma. Increasing lysine supplementation produced a decline in the N content of the whole blood and blood corpuscles but a rise in the N content of blood plasma. The activity of GOT in the blood of young hens was not found to be useful as an indicator of the quality of dietary proteins.


[Substitution of protein feed through lysine-supplemented high-protein wheat during the rearing and laying period of hens. 4. Effect of graded lysine doses during the rearing of young hens on the performance characteristics during the laying period]. 1530 laying hybrid hens kept under conditions of large-scale production were used to test whether varying lysine levels given to young hens would later on influence the production of the birds during their laying period. Thus, young hens received isonitrogenous and isocaloric diets with varying lysine content (group 1-4: 0.59%, 0.61%, 0.54%, 0.46%) and varying sources of lysine (group 1: wheat/fish meal; group 2--4: wheat/synthetic L-lysine). The ration used for the controls was prepared on the basis of nationally prescribed formulas.


[Studies on the use of wheat rich in crude protein in the feeding of broilers. 1. Experimental procedure, weight gains, food consumption and food efficiency]. A fattening trial was carried out with 8 groups of broilers each comprising 1225 birds. Within this trial tests were made to replace the protein feeds of newly hatched chicks over a period of up to 56 days of age, by wheat rich in crude protein. If wheat with a high crude protein content is fed supplementation with lysine and methionine will be necessary depending on the kind of protein feed used. No supplementation with amino acids is required if rations of fish meal + extracted soya bean meal are used despite their reduced content of these amino acids. The broilers consumed larger quantities of the wheat + extracted soya bean meal+fish meal ration than of the mixtures containing no fish meal. Food requirements per unit of weight gain were the same for the mixtures containing high-protein wheat and for the standard maize ration. The lowest food consumption per unit of weight gain was computed for the wheat + extracted soya bean meal diet supplemented with amino acids. The same quantities of lysine, thioamino acids and threonine were necessary for broilers receiving the wheat rations as for birds of the standard group. Protein feed may be saved by using high-protein wheat in the fattening of broilers. The rates of weight gain obtained with these rations are the same or even better than those achieved with rations of maize + fish meal+soya bean meal.


[Studies on the use of wheat rich in crude proteins in the feeding of broilers. 2. Carcass yields and carcass composition]. Studies were made to investigate whether the the substitution of maize for high-protein wheat fed in combination with different protein in fattening rations to broilers would influence the carcass yields and chemical carcass composition of broilers. The described dietary regime was not found to have a significant influence on the different criteria of carcass composition (roaster carcass, flesh, abdominal fat, total proportion of utilizable parts) with the exception of the relative proportion of utilizable offals. The chemical composition of the total body and of all the utilizable parts showed little variation with the different types of feeding. The fat content of all the utilizable parts was much more dependent on the carcass weight of the birds at the end of the fattening period than on the composition of the rations (type of cereals used; supplementation of amino acids).


[Effect of various technological processes on the feeding properties of extracted sunflower meal]. The extracted sunflower meal with low cellulose content that was obtained by a new technological procedure exhibited better feeding properties than the sunflower meal produced by the old procedure. This is due to reduced protein denaturation and restricted deterioration of lysine but other biological factors may also be involved in this. The extracted sunflower meal with low cellulose content produced nearly identical results compared with those of extracted soya bean meal, and even a somewhat more efficient rate of gain. This is probably due to the higher methionine content of the meal, a fact which was also pointed out by other authors doing experimental work with extracted meals. It is a matter of great economic importance that the expensive soya bean meal which has to be, for the most part, imported to Bulgaria, can be replaced by this type of extracted sunflower meal. On the basis of the new technological procedure it has become possible to produce an extracted meal with low cellulose content from an ordinary extracted meal by using a fairly simple procedure (removal of seed husks).


[Addition of various types of fat to mixed dry feed as influencing the growth rate and the level of food utilization in rainbow trout (salmo gairdneri)]. Commercially prepared mixtures of dry feed for trout were supplemented with sunflower oil, cod liver oil or emulsions of fish oil in amount of about 5% and were fed to hatchery rainbow trout (Salmo gairdneri) for an experimental period of 112 days at water temperatures ranging from 13 degrees to 20 degrees C. The fish receiving the fatted pellets were clearly superior to the controls in regard of rate of gain, food utilization and protein utilization. The best results were obtained with additions of sunflower oil. In this case, the rate of gain was 382% as compared with 262% (for the controls), food consumption per weight gain of fish was 1.28 compared with 1.98, PER 2.04 compared with 1.26 and PPW (productive protein value) 34.5 relative to 22.4. Additions of fat to the feed increased the fat content of the experimental fish by about 3%, raising it to an average total of 11.5%. The same effect had already been observed in a previous trial as a result of a 10% addition of sunflower oil.


[Studies on the protein and amino acid metabolism of laying hens using 15N labeled casein. 2. 15N incorporation into the N fractions and basic amino acids of the hen stomach and into the contents of the crop and stomach]. 4 colostomated laying hens received 15N labelled casein as sole protein source for a period of 6 days. Two birds each were slaughtered on the 8th and 12th day of experiment. 23.5% of the total N in the glandular stomach and the gizzard were TCE soluble. The amino acid composition of the gastric proteins was broader than that of the proteins of flesh, with the exception of lysine and histidine. The atom % 15N' of the N of the stomach was roughly the same as that of the protein N; the level of labelling in the TCE soluble N fraction was only slightly higher. 2 and 6 days after the final administration of tracer N an appreciable proportion of 15N was found in the N fractions and in the basic amino acids contained in the crop and the stomach. From this is may be concluded that a considerable portion of the N-containing substances previously absorbed were secreted into the lumen of the crop and the stomach.


[Studies on the protein and amino acid metabolism of laying hens using 15N labeled casein. 15N concentration in the intestinal content and intestinal tissue in relation to the time of the last 15N administration]. Four laying hens with anus praeternaturalis were fed 15N casein for a period of 6 experimental days. Each experimental bird thus received a 15N excess (15N') of 154.44 mg. 11.54 mg of 15N' were found in lysine 3.99 mg in histidine and 9.58 mg in arginine. 2 hens were slaughtered 48 hours after the last 15N dose; another 2 were sacrificed after 144 hrs. In this investigation the N content of the intestinal contents and in the proteins of the small and large intestine were determined. The average N content of the small intestine per hen 2.65% that of the large intestine, 2.60% and, correspondingly, the TCE soluble proportion of N was 21.8% and 20.4%. The percentage of amino acids in the contents of the small intestine was found to change relative to that of the dietary proteins, approximating the protein composition of the intestine. In the first two hens the atom % 15N' was found in the different sections of the intestine and in the intestinal contents varied between 0.14 and 0.28. The data obtained from the two hens slaughtered 144 hours after the last 15N' dose were nearly the same ranging from 0.08 to 0.10 atom % 15n'.


[Influence of endogenous factors on the ash, calciu, magnesium, potassium, sodium, phosphorus, zinc, iron, copper and manganese contents in the bristles of pigs. 4. Effect of time of cutting and heredity on the inorganic components in the hair of the pigs (bristles of sows and piglets, newly grown hair)]. Samples of sow bristles were examined every 3 months. The results obtained confirmed the monthly gathered experimental data on the ash content and the Ca, Mg, K, and Na content (P less than 0.05-0.001) of Boar Bristles. Similarly, investigations made every 3 months showed a significant seasonal influence on the concentration of these mineral components in the bristles of the pigs (P less than 0.05-0.001). A comparison was made between newly grown hair and original bristles showing the presence of other yet unknown factors that had a controlling influence on the mineral composition of the hair. The inorganic components in the short newly grown hair were not different from those found in analogous long hair.


[Studies on the suitability of solid materials in porcine feces for use in the fattening of cattle. 1. Procedure and results of fattening trials]. Mixtures of pelleted fool containing 30% or 50% of solid material from pig semi-liquid manure were fed to fattening bulls in a 252-day feeding trial. The controls (comprising 9 animals each) received pelleted straw concentrates. The digestibility of the pellets used in these trials was tested on sheep. The animals accepted these pellets readily after a period of adjustment (consumption of dry matter per animal per day: 7.58 kg and 8.20 kg). The daily weight gains of the experimental animals were 1176.0 g and 1003.5 g. The energy required per kg of weight increase was found to be 3.72 kEFr and 4.02 kEFr. The solid materials obtained from pig semiliquid manure were found to have a lower feeding value than the pig faeces, the feeding value of the solid materials corresponding to that of meadow hay of medium quality. The solids may be used to advantage for fattening cattle when fed in combination with straw, cereals and sugar beet products.


[Influence of crude fibers in the diet of rats on the absorption of amino acids]. Growing rats received either a protein-free experimental diet or a diet containing 15% crude protein (whole egg). The crude fibre content of the diet was adjusted to 5%, 10%, or 20% by adding various proportions of what straw meal. Following a preliminary 7-day period of feeding the animals received L-14C-Leucine administered by stomach tube or by subcutaneous injection. In a 72-hour post-experimental period analyses were made to investigate the urinary and faecal excretion of radioactivity. About 50% of the amount of radioactivity excreted with the feaces were of endogenic origin. In general, higher percentages of straw meal in the diet produced higher levels of faecal 14C excretion. It was only in the animals placed on the whole egg diet that the TCA soluble portion of radioactivity was found to rise with the increasing straw content of the diet. The experimental results substantiate the assumption that native crude fibre influences the process of intestinal sloughing and, additionally, it is capable of abosrbing or adsorbing amino acids, peptides or protein, due to its spatial configuration. Similarly, it affects the digestion and resorption of proteins.


The effect of ageing on plasma pethidine concentration. 1. Plasma pethidine levels have been monitored after the administration of 1.5 mg/kg intramuscularly to a group of young (under 30) and old (over 70) subjects. 2. Plasma levels were consistently higher in the old group, this was most marked for the first three hours but for most of the study there was a more than two-fold difference. 3. Differences in uptake from muscle and in metabolism were small and appeared unimportant. 4. Less pethidine was excreted in the elderly and this contributed to the overall differences in serum levels but was not important in explaining the marked disparity noted over the first three hours. 5. Red cell binding of pethidine by the young was much greater than by the old and if the differences in drug binding also applies to other tissues this would explain the high serum levels in the old and the increased incidence of side effects.


The effect of age on plasma levels of propranolol and practolol in man. 1. Plasma levels of propranolol and practolol were measured in groups of elderly and young subjects, after the oral administration of propranolol (40 mg) and practolol (200 mg) on separate occasions. 2. At all sampling times the mean plasma propranolol level in the group of elderly subjects was substantially greater than the corresponding level in the group of young subjects, there being a significant difference between the two, and a fourfold difference in the mean peak levels. 3. After practolol, there was no significant difference between the mean plasma concentrations of the drug in the two groups for the first 2 hours. Subsequently, the mean plasma levels in the group of elderly subjects were somewhat higher than the corresponding levels in the young group, the differences between the two reaching significance. 4. It is suggested that there is a need to substantially reduce the dose of propranolol given to elderly patients. With practolol, however, no reduction is necessary providing renal function is normal for the patient's age.


Absorption of enteric and non-enteric coated prednisolone tablets. 1. Relative rates of absorption of enteric and non-enteric preparations of prednisolone were measured in five renal transplant recipients. 2. The absorption of the enteric coated preparation is delayed and the peak plasma concentration is much lower than that attained using the same dose of the uncoated material. 3. The therapeutic implications of these observations are discussed.


Measurement of plasma prednisolone in man. 1. A modification of the competitive protein binding assay for prednisolone described by English, Chakraborty & Marks (1974) is presented. 2. Addition of pg quantities of [3H]-prednisolone following oral dosage with prednisone or prednisolone. 3. Mean plasma half-life and peak plasma concentrations in patients with respiratory disease seen following prednisolone administration agree well with previous studies in healthy volunteers performed by other workers using competitive protein binding and radioimmunoassay techniques. 4. A considerable inter-patient variation in bioavailability after a standard dose of prednisolone (20 mg) was noted.


Prednisolone levels in the plasma and urine: a study of two preparations in man. 1. A competitive protein binding method was used to measure prednisolone and cortisol in blood and urine of volunteers given prednisolone by mouth (15 mg) in the standard tablet form and a fortnight later a regulated release formulation of prednisolone metasulphobenzoate containing an equivalent amount of prednisolone. 3. Plasma prednisolone levels rose rapidly after the standard tablet and more slowly after the regulated release form. The normal activity of the hypothalamic-pituitary-adrenal axis as measured by the 09.00 h plasma cortisol concentration was present 24 h after ingestion of the regulated release preparation. In contrast, the 09.00 h plasma cortisol level was reduced in subjects 24 h after receiving prednisolone in the standard tablet form.


The plasma half-life of antipyrine in chromic uraemic and normal subjects. 1. Antipyrine was given intravenously in a dose of 18 mg/kg body weight to twelve patients with chronic renal failure (plasma creatinine greater than 4.9 mg/100 ml) who were not taking drugs and twenty normal subjects. 2. Plasma antipyrine levels were measured by a specific method, the plasma half-life of the drug was determined and used as an index of drug oxidation. 3. The mean (+/- s.d) plasma antipyrine half-life in patients with chronic renal failure (7.3 +/- 2.0 h) was significantly shorter than in normal subjects (13.2 +/- 4.3 h: P less than 0.002). There was no difference in the apparent volume of distribution of antipyrine between the two groups (P greater than 0.6). 4. Pretreatment of five patients with chronic renal failure and seven normal subjects with antipyrine or phenobarbitone for weeks significantly shortened the mean plasma antipyrine half-life from 7.4 +/- 2.5 h to 5.0 +/- 1.5 h in uraemics (P less than 0.005) and from 13.2 +/- 4.5 h to 6.9 +/- 1.5 h in normal subjects (P less than 0.0025).5. These results suggest that oxidation of antipyrine by hepatic microsomal enzymes is increased in patients with chronic renal failure, but a state of maximal induction of these enzymes was not observed. The clinical implication of this finding with regard to the association between liver microsomal enzyme induction and vitamin D resistant osteomalacia is discussed.


Pharmacokinetics of a single dose of phenytoin in man measured by radioimmunoassay. 1. Serum concentrations of phenytoin were studied by radioimmunoassay in five normal volunteers following a single oral dose of phenytoin sodium (100 mg). 2. Two distinct peaks were found at 2.5-3.5 and 10-12 h after ingestion. Maximum serum concentrations ranged from 1.56 mug/ml. The mean plasma half-life of the drug under these conditions was 9.81 +/- 0.66 (s.e. mean) hours.


The skeletal muscle response to the repeated administration of suxamethonium and its interaction with edrophonium in anaesthetised man. Tetanic and single twitch contractions of the adductor pollicis muscle in man were recorded during repeated injections of suxamethonium (0.2 mg/kg or 0.1 mg/kg) every 15 minutes. 2 Tachyphylaxis to suxamethonium developed rapidly in every patient studied when single twitch contractions were observed but tetanic contractions later showed an increasingly prolonged recovery with repeated injections. 3 Edrophonium administered at the point of 50% recovery of the tetanic contractions in patients given suxamethonium (0.2 mg/kg) repeatedly first potentiated the blockade but when the tachyphylaxis had developed fully on the single twitch, usually after the third or fourth injection, the blockade of the tetanic contractions was reversed. 4 These findings indicate that the tachyphylaxis and the change in the nature of the blockade produced by suxamethonium in man take place at the same time and might be part of the same phenomenon.


Effect of intravenous injection of salbutamol in asthma. The effect of i.v. salbutamol was compared with aerosol salbutamol in ten asthmatic patients. 2 A cumulative dose of salbutamol (300 mug) given in three separate injections over 45 min resulted in a mean increase in peak expiratory flow rate (PEFR) of 38.3% and FEV1 of 36%. 3 There was no significant difference in degree of bronchodilatation to the same dose of salbutamol administered intravenously or by aerosol. 4 Palpitations, tremor, and postural hypotension were common when the drug was injected intravenously over one minute, but did not occur after aerosol administration. 5 It is suggested that sulbutamol by intravenous injection is a useful addition to the treatment of acute asthma.


Intravenous infusion of salbutamol in the treatment of asthma. The effects of i.v. infusion of increasing rates of salbutamol for up to 4 h were documented in ten convalescent asthmatic patients. 2 The major bronchodilator effect was seen at 4.16 mug/minute. A small further improvement occurred at infusion rates up to 25.0 mug/min but was not significantly better than that seen at the lower infusion rate. 3 Cardiovascular effects were minimal after 60 min at the lower rate and even at 25.0 mug/min mean heart rate rose by only 17.1 beats/minute. All patients tolerated the 4 h infusion well. 4 It is concluded that i.v. infusion of salbutamol may be a useful addition to the treatment of the patient with a severe attack of asthma.


Procainamide absorption studies to test the feasibility of using a sustained-release preparation. Using in vitro techniques it was confirmed that whilst the release of procainamide from the conventional formulation (Pronestyl) was rapid, that from the sustained-release preparation (Cardiorytmin Retard) occurred over a prolonged period. 2 The peak plasma procainamide concentrations after single doses of Cardiorytmin Retard were relatively lower and occurred later than those after single doses of Pronestyl. Furthermore, after reaching a peak, the fall in plasma procainamide concentration was less rapid after the sustained-release preparation. Early urinary recovery of procainamide in patients and in healthy volunteers was greater after Pronestyl than after Cardiorytmin Retard, though overall recovery in urine was similar. These findings indicate that the absorption of the sustained-release preparation is slower, though the overall bioavailabilities of the two preparations are almost the same. 3 These results confirm the feasibility of using a sustained-release procainamide preparation, such as Cardiorytmin Retard, since it would be possible to administer the same amount of drug in fewer daily doses without plasma concentrations becoming ineffective towards the end of each dosing interval.


The distribution of quinidine in human blood. The uptake of quinidine by washed human red blood cells from isotonic buffer solution (pH 7.4) occurred rapidly and was proportional to the concentration of drug in buffer. A constant red cell/buffer partition ratio of 4.16+/-0.15 s.e. mean was found. 2. Uptake from buffer solution was not affected by temperature or ouabain or by gassing with nitrogen or carbon monoxide and there was no evidence of saturability. Drug in red blood cells was associated largely with the cell contents (94.4+/-1.5% s.e. mean) following partition. 3 Plasma reduced the uptake of quinidine so that a red cell/plasma partition ratio of 0.82+/-0.09 s.e. mean was found. 4 Alteration of plasma binding by dilution of plasma with buffer showed that uptake was proportional to free drug concentration. 5 The possibility of red cell uptake of drug should be included in any considerations concerning pharmacokinetic aspects of drug action in the body.


The acute and chronic bronchodilator effects of ephedrine in asthmatic patients. In eight asthmatic patients, there was no change in the bronchodilator response to a single dose of ephedrine (22 mg) given alone or in a compound tablet, after treatment with ephedrine (11 mg three times a day) or one tablet three times a day for 2 weeks. 2 There was no deterioration in lung function during the 2 week treatment period with either ephedrine or the compound tablet. 3 An inter-patient variation was noted in the plasma ephedrine concentraition required for bronchodilatation. 4 The half-life of theophylline did not change after chronic treatment with the tablets, one three times a day for 2 weeks.


Stacking interactions of nucleobases: NMR-investigations. I. Self association of N6, N9-dimethyladenine and N6-dimethyl-N9-ethyladenine. The selfassociation of N6,N9-dimethyladenine and N6-dimethyl-N9-ethyladenine has been studied by means of NMR technique. The thermodynamic quantities have been calculated using an isodesmic NMR model with three NMR parameters (the monomer shift deltaM and two complex shifts delta2 and delta3). The dependence of the thermodynamic quantities on the NMR parameters is discussed. Special attention is given to the determination of deltaM and its temperature dependence. Calculations with delta3 = 2 - delta2 and deltaM taken independently of temperature result in an average entropy deltaS = - 17.9 +/- 1.8 e.u. for N6,N9-dimethyladenine and deltaS = - 16.7 +/- 1.7 e.u. for N6-dimethyl-N9-ethyladenine and in an average enthalpy deltaH = - 7.2 +/- 0.6 kcal - mol-1 for both substances investigated.


Conformation of the common purine (beta) ribosides in solution: further evidence for a correlation between N-S state of the ribose moiety and syn-anti equilibrium. The solution conformations of adenosine, guanosine and inosine in liquid ND3 have been determined by NMR. Comparison of the Karplus analysis of the proton HR spectra of the ribose moiety obtained in this solvent with the data from aqueous solutions of A and I proves that the conformations of the nucleosides are very similar in both liquids. From the analysis of the vicinal coupling constants of the ring protons it has been deduced that the S state C(2')-endo is slightly preferred. The mole fraction in S approximates 0.6 for all three nucleosides. C-13 relaxation measurements have been applied in the determination of the correlation times for rotational diffusion. Only at temperatures below - 40 degrees C is the pseudo-rotation of the furanoside ring slowed down sufficiently for it not to contribute to the measured relaxation rates. From NOE studies and T1 measurements on the individual protons it is derived that the N, C(3')-endo, form of the ribose is correlated with an anti conformation of the base (Y approximately 210 degrees to 220 degrees) and the S, C(2')-endo, form of the ribose with a syn conformation of the base (Y approximately 30 degrees to 50 degrees). The glycosyl torsion angles derived for the two conformations of A, G, and I are equal within the limits of accuracy.


The structure determination of the variable portion of the Bence-Jones protein Au. The structure of a pi-type Bence-Jones protein variable fragment Au has been determined by molecular replacement methods using the known structure of an other Bence-Jones variable fragment Rei (Epp et al., Eur J. Biochem. 45, 513 (1974). The crystallographic R factor is 0.31 for about 4000 significantly measured reflections between 6.8 to 2.5 A. The Au protein forms a dimer across a crystallographic two fold axis. The spatial relationship of the two monomers, the conformation of the backbones and of the internal residues is extremely similar to that found in Rei.


Instability of Langmuir-Blodgett layers of barium stearate, cadmium arachidate and tripalmitin, studied by means of electron microscopy and infrared spectroscopy. Results of an investigation of the stability of n-layers of barium stearate, cadmium arachidate and tripalmitin by means of electron microscopy and attenuated total reflection infrared spectroscopy are reported. Odd and even numbered barium starate n-layers with n - 1,2,3,4,5 are found to rearrange spontaneously from a regular film into ultrastructures of irregular, flat islands of varying thickness. The kinetics of the phase transformation of the first layer depends on the substrate, that of n-layers appears to be dependent on n, the temperature, and the surrounding medium. The kinetic behaviour of odd and even numbered layers is distinctly different. Similar studies on cadmium arachidate layers reveal much slower kinetics of the rearrangement process. In the case of tripalmitin n-layers it is shown that electron microscopy and infrared spectroscopy yield valuable complementary information about ultrastructure and molecular structure of the layers in correlation with the rearrangement process, which also occurs with this system. Consequences of the results of this paper for work published in various fields are briefly discussed.


The significance of the 2' OH group and the influence of cations on the secondary structure of the RNA backbone. In the IR spectra, the coupling of vibrations leads to band splitting and/or bands shifting in opposite directions which provides information on the mutual orientation of groupings. From such band shifts in the range 1800 to 1500 cm-1 one can draw conclusions on the double helix formation of polynucleotides. These band shifts are caused either by vibrational coupling of stretching vibrations within pairs of base residues or by coupling of stretching vibrations with the bending (scissor) vibration of the -NH2 groups; the latter is indicated by band shifts after deuterium substitution within the amino groups. Couplings of phosphate and 1 ibose vibrations in the range 1300 to 1000 cm-1 provide information on the secondary structure of the backbone. In order to obtain information of the structure of the RNA backbone, the IR spectra of poly(ribonucleotides) were studied in neutral media in which they were single-stranded. The shift due to coupling of the band of the 2'OD bending vibration and that of the antisymmetric stretching vibration of the ether group of the ribose residue proves that ribose residues of the backbone are cross-linked via hydrogen bonds. These are formed between the 2'OD or 2'OH groups, respectively, and the O atoms of the ether group of the neighboring ribose residues. This is the reason for the difference between DNA and RNA as regards the 2'OH group. The structure formation caused by these hydrogen bonds results in a stiffening of the RNA backbone. The tendency to form these hydrogen bonds increases in the order poly (U), poly(C), poly (A). This order of secondary structure stabilization is due to an interplay between the influences of (1) the 2'OH hydrogen bonds and (2) the base residues' stacking. Furthermore, the coupling of the antisymmetric stretching vibration of the greater than PO2- groups with a vibration involving the 2'OH group can result in a doublet structure of the band at about 1240 cm-1 if cations with strong fields are present. This probably shows that these cations can turn the greater than PO2-groups-which are usually turned outward at the backbone, as shown by construction of molecular models- towards the basic residues. Thus they cause stiff monohelices which are right-handed screws.


Interpretation of invertebrate photoreceptor potentials in terms of a quantitative model. It is known from voltage-clamp experiments on visual cells of Limulus and Balanus that the total membrane current can be separated approximately into a dark current JD and a light-induced current JL such that each part has a time-and intensity-independent reversal potential. In addition JL can be represented approximately as a product of a nonlinear, time independent current-voltage characteristics J0L (v) and an "activation factor" xa which depends on light intensity and time. J0L(V) can be described by a simple electro-diffusion membrane model (for JD we use the same model). A set of kinetic equations including amplification, latency and light adaptation leads to a determination of xa for photoisomerization of single rhodospin molecules and for arbitrary light signals. The receptor potentials calculated show many features of the experiments on Limulus, Balanus and Astacus.


Dielectric properties of synaptosomes isolated from rat brain cortex. Dielectric measurements were performed on the suspensions of synaptosomes isolated from rat brain cortex. The synaptosomes in buffered salt media showed typical dielectric dispersions caused by the presence of a thin limiting membrane of sufficiently low conductivity. An analysis of the dielectric data revealed that the electric conductivity of the synaptosome interior was about 37% of the external medium conductivity under isotonic conditions and that the dielectric constant for the interior phase was about 35. The membrane capacitance (0.7 muF cm-2) remained constant irrespective of nature and concentration of the univalents salts examined. Significant reduction in both the conductivity and the dielectric constant of the internal phase can be explained theoretically proveded that some intra-synaptosomal structural (synaptic vesicles and/or small mitochondria) of non-conducting nature occupies about 50% of the particulate volume, the remainder being in equilibrium with the external salt medium.


A method for determining the dielectric constant and the conductivity of membrane-bounded particles of biological relevance. Numerical assessment is made regarding Pauly and Schwan's theory which describes the dielectric behavior of a suspension of "shell spheres" as a model of biological membrane-bounded particles. The results indicate that approximate expressions of the theory may give rise to serious errors when applied to particles smaller than about 1 mum in diameter. With a view to performing analysis according to a general expression of the theory, some of the characteristic responses of dielectric parameters upon changes in phase parameters are examined with particular reference to some numerical ranges of biological interest. On this  basis a simplified and systematic procedure is proposed for estimating the phase parameters of particles whose shell phase can be regarded as non-conductive. As the application of the procedure proposed, a set of dielectric data of a synaptosome suspension is analyzed, so that the following three phase parameters are successfully determined: membrane capacitance (or shell  phase  dielectric constant), interval phase conductivity and internal phase dielectric constant. Some limitations of the procedure are discussed for the cases of conducting shells and small particles.


1/f Membrane noise generated by diffusion processes in unstirred solution layers. A mathematical treatment is given for 1/f noise observed in the ion transport through membranes. It is shown that this noise can be generated by current or voltage fluctuations which occur after step changes of the membrane permeability. Due to diffusion polarization in the unstirred solution layers near the membrane these fluctuations exhibit a 1 square root of t time course which produces noise with a 1/f frequency dependence. The spectral density of 1/f noise is calculated for porous membranes with random switches between a finite and zero pore permeability. A wide frequency range and a magnitude of 1/f noise are obtained which are compatible with experimental data of 1/f noise reported for nerve membranes.


Stacking interactions of nucleobases: NMR-investigations. II. Self-association of purine-and pyrimidine-derivatives. The self-association of various purine- and pyrimidine-derivatives in D2O has been studied by means of NMR technique. The thermodynamic quantities have been calculated using an isodesmic NMR model. Among the nucleobases investigated, the adenine-derivatives were found to be most suitable for quantitative determination. A comparison of methylated adenine-derivatives and the pH-dependence of the self-association lead to the conlcusion, that the stacking associates are stabilized by special van der Waals interactions based, essentially, on the polarizability of the pi-electron-system of the assciated molecules.


Association of sexual hormones with nucleobases in water: NMR-investigations. The mixed association of testosterone-sulfate and estradiol-sulfate with several derivatives of nucleobases in D2O has been investigated by means of nuclear magnetic resonnance spectroscopy. From the differences among the chemical shifts of the hormone-protons it is concluded, that the nucleobases in the complexes are located above the center of the steroid molecule. The beta-side of the steroid which is characterized by the axial methyl-groups is directed towards the bases. The enthalpies of mixed association of the hormones with a certain nucleobase of the same order of magnitude as the enthalpy of selfassociation of this nucleobase (Schimmack et al., to be published). It is suggested that the complexes are stabilized by van-der-Waals forces. This stacking-like interaction is not specific for the male or female sex hormones: no qualitative or quantitative differences have been observed among the complexes of the two hormone-sulfates with the nucleobases.


Carcinogenesis and radiation risk: a biomathematical reconnaissance. The biological effects of radiation are often correlated with the dose of radiation received by the tissue or cells at risk, though other physical factors such as spatial or temporal dose distributions, total number of cells  irradiated, or relative biological effectiveness are also relevant. In attempting an estimate of biological effect, for example carcinogenesis, it is frequently assumed that the risk is simply proportional to the dose received, though biological experiment often reveals a much more complex relation between effect and dose. We have therefore examined in some detail certain of the consequences of taking into account such a complex relationship in assessing "risk" on the basis of "dose". We first examine the effect of size of population of cells at risk. If tumours arise from chance interactions of cells and ionizing particles we might imagine that large animals containing many orders of magnitude more cells might be much more at risk. A survey of literature shows no evidence that this is so, and of course mere mass might be expected to be a poor parameter for defining carcinogenic risk. As between tissues, DNA content combined with metabolic parameters or "proliferative potential" would be better. However, the literature does show that for a single co-ordinated tissue or organ the fraction of that tissue irradiated is significant. There is clearly some correlation with number of cells at risk. We therefore proposed a formula relating the risk of a cell population to a rare event, such as the "transformation" of a cell or group of cells to an overt tumour. We assume a spatial pattern of dose administered to a defined group of cells reacting according to an assumed dose-response relationship. The assumptions are, biologically speaking, very crude, and we discuss some of the ensuing limitations. The formula may, however, be used to attack a number of important problems. First it is necessary to discuss the forms of dose-response relationships derived theoretically and also observed in radiobiology. Several are chosen for detailed study, particularly responses rising more rapidly than dose at low levels, then reaching a maximum and declining with increasing dose. It is pointed out that there are many possible explanations of this decline at high dose, ranging form cell "death" to "sterilization" or to mutual interaction of neighbouring cells. It can also arise from simple statistical consideration of the probability of multiple events necessary for carcinogenesis in the same or neighbouring cells.


Epidural haematoma. A retrospective study of 100 patients. A retrospective study was made of 100 consecutive patients with an epidural haematoma in order to establish which clinically demonstrable factors had influenced the prognosis quoad vitam et sanationem. Operations were performed on 92 of these patients, 29 (32%) of whom died; 8 patients died without operation, and in 2 of these cases the diagnosis was not made during life. A lucid interval was observed in 57 patients; absence of a lucid interval in combination with a lowered sensory level indicated associated intradural lesions (cerebral contusion, acute subdural haematoma), with consequently a less good prognosis. The prognosis was also adversely affected by deeper coma, occurrence of extensor spasms, bilateral stiff pupils, bilateral pyramidal symptoms and an age over 50. Some 33% of the patients treated by operation showed marked symptoms of compression (extensor spasms and/or bilateral stiff pupils); although these symptoms are usually described as indicative of a hopeless prognosis, 40% of the patients in this catagory survived. Contrary to the data in the literature, the interval between accident and operation within the first 24 hours did not influence the mortality, which was 50%. All patients operated on more than 24 hours after the accident, survived. A cranial fracture was absent in 13 patients, 11 of whom were under 30; absence of a cranial fracture was prognostically favourable. A catamnestic study revealed that 7 of the 58 accessible survivors had residual neurological dysfunctions; all these patients were up and about. The residual morbidity after early operation (within 24 hours) was the same as that after later operation. The data obtained were compared with those on a number of series recently published in the literature.


Microsurgical fronto-temporal approach to pituitary adenomas with extrasellar extension. In the present paper the microsurgical, fronto-temporal technique for the surgical treatment of chromophobe pituitary adenomas with extra-seller extension is described in detail. The complete treatment of expansive chromophobe adenomas includes 4000 rad of external irradiation by the rotation technique and hormonal replacement therapy. The results of this treatment in 36 consecutive patients from 1971 through 1975 are given. There is no mortality nor recurrence of tumor in the follow-up period. The postoperative morbidity is low, especially in the group operated by the microsurgical fronto-temporal approach. The visual acuity improved or normalized in 86%, for the visual fields this percentage was 90%. These results are compared to those of our own series of 65 patients, treated from 1945 through 1959, and to some other data from the literature. Finally, some arguments in favour of the intracranial approach versus the transsphenoidal approach are presented.


Uncommon third ventricle herniation with cyst formation as a possible result of obstructive hydrocephalus. An adult man with an unusual cyst formation, originating from the suprapineal recess is described. The cyst may partly be caused by and may partly have contributed to aqueductstenosis.


Paralytic pontine exotropia in subarachnoid hemorrhage. A clinicopathological correlation. A syndrome of combined right lateral gaze palsy and right internuclear ophthalmoplegia, followed by a left exotropia in a case of subarachnoid hemorrhage is presented. At necropsy a single small pontine end-zone infarction was found, involving the medial part of the right paramedian pontine reticular formation, the tectospinal tract and the ventral part of the right medial longitudinal fasciculus. The fila radicularia of the right abducens nerve passed through the necrotic area. The mechanism of these characteristic ocular motor disturbances in relation to the post mortem findings and the topopathogenesis of the pontine infarction are discussed.


Effect of glycerol treatment on the natural history of acute cerebral infarction. From a population of patients with acute cerebral infarction one hundred were selected and divided into two groups, with comparable neurological deficit and risk factors. To one group of patients glycerol was administered, the other group served as a control. Neurological deficit was scored on the day of admission and in the next 4 weeks. There was no noticeable beneficial effect of glycerol administration in acute cerebral infarction.


A forme fruste of the pterygium syndrome? A case of a girl with popliteal webbing associated with limited extension of the knee, flexion contractures of the third, fourth, and fifth digits, hypothrophia of leg musculature, and absent tendon reflexes in the legs is reported. Between 19 months and 6 years of age, the digital contractures, popliteal webbing, and limitation of knee extension progressively improved. This is the first reported instance of this combination of signs and the first report of regression of some of these physical findings.


Aseptic meningitis as a complication of scinticysternography utilizing 111Indium-dtpa. The intrathecal administration of numerous substances has been known to cause arachnoiditic as well as aseptic meningitic reactions. Pleocytosis and increased protein in the CSF are well known findings following administration of air or myelographic dyes. This has also been observed with antibiotics. Even intrathecal steroids (e.g. depo-medrol) have been implicated in aseptic meningitic reactions. Despite the wide variety of causative agents, only a small percentage of patients develop clinical manifestations of aseptic meningitis. Are these reactions then caused by specific auto-immune type responses, or are they directly related to local irritants in each case, or a combination of both factors?


Changes in lymphocyte recirculation and liberation of the adoptive memory response from cellular regulation in irradiated recipients. Thoracic duct lymphocytes from previously immunized (AS2 x AS)F1 rats ('TDL) were adoptively transferred to syngeneic recipients and triggered by soluble HSA (s-HSA) the following day. The response of 'TDL in an irradiated recipient was almost two orders of magnitude greater than the response in a nonirradiated adult host. The affinity of the antibody in the adult recipients was significantly reduced but increased with time. Nonirradiated young recipients (3 weeks old) also supported an adoptive memory response which was comparable in quantity and quality to that found in irradiated hosts. The response of 'TDL declined progressively when transferred into 2-week-old or 4-week-old radiation chimeras, or was reduced in irradiated hosts when the memory cells were mixed together with nonimmune TDL. The experiments indicate that the differential response between the adult and irradiated recipient is the result of a restrictive control in the former host rather than an enhancing factor in the latter. Lymphocytes in the nonimmune population regulate both the expansion and maturation of the adoptive memory response, the high energy-binding B cells being at a selective disadvantage. Host irradiation effectively liberates the adoptive response from this cellular control mechanism. A comparative study of transferred, [14C]leucine-labeled TDL showed that distribution and homing of lymphocytes to lymph nodes and spleen was not altered by irradiating the recipients. However, adoptively transferred cells almost completely failed to recirculate in irradiated rats, in contrast to normal recipients. But, the injection of large numbers of unlabeled TDL following irradiation forced more labeled cells into the recirculating pool, suggesting that saturation of depleted lymphoid tissue with lymphocytes is an important factor regulating lymphocyte traffic. The relevance of this "saturation effect" in regulating the adoptive memory response is discussed.


The association of H-2 antigens and EAC receptors on the surface of peritoneal cells. The exposure of murine peritoneal cells to anti-H-2 sera results in a diminished expression of H-2 antigen on the cell surface. Concomitant with this "H-2 modulation" the capacity of macrophages to bind sheep red blood cells coated with antibody and complement (EAC) was markedly diminished. In contrast, there was no change in the capacity of modulated macrophages to bind sheep red blood cells coated with antibody alone (EA). Antibodies to K end H-2 specificities were more effective in reducing the binding of EAC than antibodies to D end H-2 specificities. Exposure of peritoneal cells to O or Ly antisera had no effect on the formation of EAC rosettes. Exposure of peritoneal cells to anti-H-2 sera, under conditions which would not allow modulation of H-2 antigens, also prevented the reduction of EAC binding. Thus, the EAC receptors and H-2 antigenic specificities seem to be closely related on the surface of peritoneal cells, but constitute distinct cell surface structures. Preliminary evidence indicates that vinblastine, a microtubule depolymerizing agent, may disrupt the close association of EAC receptors and H-2 antigens. It is suggested that the association of EAC receptors and K end H-2 determinants on the membrane of macrophages may have implications for the regulation of the immune response by H-2-linked Ir genes.


Similar combining sites of IgG1 and IgG2a antibodies in individual mice as judged from affinity and rate constant measurements. Within individual sera, mouse IgG1 and IgG2a subclass antibodies against the antigenic determinant oligo-D-alanine are likely to have similar combining sites. The antibodies are characterized by two methods, by their rate of binding to antigen equipped sheep red blood cells and by the hapten inhibition of antigen binding. The two characteristics are shown to be independent. The subclass antibodies of thirteen different sera differ by a factor of about 10 in their rate constant and by a factor of about 50 in affinity for hapten. In contrast, IgG1 and IgG2a within the same serum have strikingly similar rate constants (factor 1.02-1.33) as well as very similar affinities (factor 1.1-2.7). Since it is highly improbable that correlation in two independent criteria occurs by chance, the IgG1 and IgG2a antibodies are assumed to have similar combining sites.


Similar specificity of IgG1 and IgG2a antibodies in individual mice. In this study the previous finding of similar variable regions in individual IgG1 and IgG2a antibody populations is extended by the demonstration of similar fine specificity of IgG1 and IgG2a combining sites. Antibody populations from individual mice directed against oligo-D-alanine determinants were analyzed in their cross-reactivity towards 5 heterologous dipeptides. This was done by mixing antibody and hapten followed by determination of free antibodies in a kinetic red cells sensitization assay. The comparison of hyperimmune sera from 10 mice showed that genetically identical mice can differ significantly in their cross-reaction pattern. Within each serum the cross-reaction pattern was determined for IgG1 and IgG2a. With a few exceptions the same individual pattern was found in both IgG1 and IgG2a antibody populations. This was taken as evidence that the combining sites of IgG1 and IgG2a anti-oligo-D-alanine antibody populations in an individual mouse are similar.


Chemical analysis and electron microscopy studies of human C1q prepared by different methods. Five differently isolated and purified human C1q preparations were examined by electron microscopy and analyzed by polyacrylamide gel electrophoresis in 0.1% sodium dodecyl sulfate and 0.5 M urea. The amino acid and carbohydrate composition of C1q purified by the DNA method are reported and compared with results obtained on C1q isolated by other procedures. Electron microscopy showed that all C1q preparations had six peripheral subunits connected by fibrillar strands to a central subunit. The presence of small amounts of dimers was also observed. The physico-chemical properties of the molecule are independent of the purification method used. The five C1q preparations labeled with 125I in presence of lactoperoxidase formed two types of noncovalently linked subunits. In each case the smaller (central) subunit contained over thirty times as much radioactivity as the larger (peripheral) subunit supposed to interact with immune complexes. Reduction and alkylation confirmed for each preparation the presence of three polypeptide chains, the smaller of which contained essentially all radioactivity.


"Natural" killer cells in the mouse. I. Cytotoxic cells with specificity for mouse Moloney leukemia cells. Specificity and distribution according to genotype. In the spleens of young, adult mice there exist naturally occurring killer lymphocytes with specificity for mouse Moloney leukemia cells. The lytic activity was directed against syngeneic or allogeneic Moloney leukemia cells to a similar extent, but was primarily expressed when tested against in vitro grown leukemia cells. Two leukemias of non-Moloney origin were resistant and so was the mastocytoma line P815. Although killer activity varied between different strains of mice, the specificity of lysis was the same as indicated by competition experiments using unlabeled Moloney or other tumor cells as inhibitors in the cytotoxic assays. Capacity to compete and sensitivy to lysis by the killer cells were found to be highly positively correlated. Analysis of the kinetics of the cytotoxic assay revealed a rapid induction of lysis within one to four hours, arguing against any conventional in vitro induction of immune response. No evidence was found of soluble factors playing any role in the cytolytic assay.