Selective destruction of cultured tumor cells with uncontrolled nuclear division by cytochalasin B and cytosine arabinoside. Cultures of normal human and hamster and malignant human and hamster cells respond to cytochalasin B (CB) differently. The neoplastic cells become highly multinucleated with continuous nuclear division, while cytoplasmic division is prevented. These cells exhibit uncontrolled nuclear division. The normal cells show control of nuclear division, since CB treatment results in only binucleation, although cytoplasmic division is prevented. The CB-treated normal cells also show reduced incorporation of [3H]thymidine. When rapidly growing normal or neoplastic cells of either species are treated with cytosine arabinoside (ara-C), all cells are killed within 10 to 20 days. If the normal cells are treated with ara-C in the presence of CB, the cells survive for at least 35 to 40 days, suggesting that CB can protect normal cells from the destructive effects of ara-C. However, if malignant cells are treated with ara-C in the presence of CB, all cells are destroyed in 25 days. Although CB affords some protection to tumor cells, it is relatively small and appears only to effect a delay in ultimate cell death. Treatment of any of the cell lines with CB alone results in some loss of viability, but the drug is reversible although less so for the malignant cells, In additional experiments, are-C plus CB-treated normal and neoplastic cells were reversed from the drugs and propagated in normal medium at various periods after the initiation of ara-C treatment. ara-C plus CB-treated normal cells could be freely reversed at any time after the start of ara-C treatment up to at least 35 days. After reversal, cell growth resumed, and the total number of cells returned to that present prior to drug treatment. The tumor cells could not be freely reversed from ara-C plus CB, even when the ara-C was present for only 5 days. In this case the cells seemed to be destroyed at the same rate as in cultures where both drugs were kept in the medium. These results suggest that CB can protect normal but not malignant cells from the toxic effects of ara-C and offer a method to specifically destroy tumor cells.


The effect of dead cells on the activity of actinomycin D against mouse sarcoma 180 ascites. It has been demonstrated that cells killed by heat or irradiation have four times greater affinity for actinomycin D (AMD) than do viable tumor cells. By using a double labeling technique, we were able to show that, with increasing amounts of AMD bound in cells, the incorporation of RNA precursors is proportionally decreased. However, in the presence of nonviable cells or of native DNA, the AMD-induced inhibition of [3H]uridine incorporation is markedly reduced. This reduction does not occur if DNase is added to the system. The accumulation of dead cells in the tumor vicinity during the natural course of tumor growth or therapy must be taken into consideration in planning therapeutic regimens. We suggest that, in combined chemo- and radiotherapy, increased effectiveness of AMD may be obtained by its use prior to irradiation, thereby assuring its direct access to the tumor cells. The addition of DNase could eliminate or greatly diminish the dead cell competition for the drug.


Decrease of epidermal histidase activity by tumor-promoting phorbol esters. The potent skin tumor promoter (12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulates epidermal macromolecular synthesis as well as proliferation, but little is known of specific functional aberrations produced by TPA. This report presents results of a study on the effects of TPA on epidermal histidase (L-histidine ammonia lyase), an enzyme found in normal epidermis but not in dermis or in mouse squamous cell carcinomas. Histidase activity was assayed on postmitochondrial supernatants obtained from hairless mouse epidermis after removal by keratotome. Topical TPA treatment at doses active in tumor promotion (1.7 to 17.0 nmoles/application) produced dose-dependent decreases in epidermal histidase specific activity at 19 hr posttreatment. The onset of the decrease occurred at 12 hr with recovery to control level specific activity by 5 days, showing kinetics similar to those obtained for stimulation of DNA synthesis. This decrease in histidase could not be attributed to a general inhibition of soluble protein synthesis or to the appearance of an inhibitor of histidase activity. The strong promoter TPA produced a greater histidase decrease than did the moderate promoter and mitogen 12,13-didecanoyl phorbol at equimolar dose, while phorbol, a nonpromoter and nonmitogen, produced no effects on histidase. The relationship of this histidase depression to tumor promotion and not initiation is further indicated by the finding that (a) Tween 60, a structurally unrelated tumor promotor, also produced a decrease in histidase; and (b) the tumor initiator urethan and an initiating dose of 9,10-dimethybenz(a)anthracene showed no effects on histadase activity.


Isolation of cis- and trans-4-methylcyclophosphamide and antitumor evaluation in vivo. 4-Methylcyclophosphamide was synthesized and separated into cis and trans isomers by column chromatography. Isolation of these isomers permitted individual evaluation against murine leukemia L1210 in vivo and assessment of possible differences in antileukemic activity. Results indicate no appreciable difference in activity of the isomers, suggesting essentially equal facility for activation by mouse liver microsomes in vivo.


Carcinogenicity of N-nitroso-3,4-dichloro- and n-nitroso-3,4-dibromopiperidine in rats. The carcinogenic potencies of 3,4-dichloro- and 3,4-dibromonitrosopiperdine were compared with that of nitrosopiperidine by feeding to groups of 15 male rats in drinking water. A treatment of 15 weeks with a total of 0.5 mmole of the dichloro compound led to death of all animals before 24 weeks with tumors of the tongue, pharynx, esophagus, nonglandular stomach, nasal turbinates, trachea, bronchi, and bronchioles. Treatment of 27 weeks with the dibromo compound, a total of 1.0 mmole, caused death of all the animals by 41 weeks, with the same types of tumors. One-half of the rats treated with an almost 3-fold higher daily dose of nitrosopiperidine, 3.9 mmoles total, were alive at 40 weeks, and all were not dead until 55 weeks. Most of these animals died with tumors of the tongue, pharynx, esophagus, and nonglandular stomach and with squamous cell tumors and olfactory carcinomas of the nasal cavity, but there were no tumors of the respiratory tree. Substitution of chlorine or bromine in nitrosopiperidine greatly increased the carcinogenicity of the compound.


Synthesis of p-nitrobenzyl and p-nitrophenyl 1-thioglycopyranosides. Reaction of 2,3,4-trio-O-acetyl-alpha-L-fucopyranosyl bromide (1) with thiourea (2), followed by reductive cleavage of the product, gave 2,3,4-tri-O-acetyl-1-thio-beta-L-fucopyranose (4). Reaction of 4 with p-nitrobenzyl bromide followed by O-deacylation yielded p-nitrobenzyl 1-thio-beta-L-fucopyranoside (6). Similar reaction conditions were used for the synthesis of p-nitrobenzyl 1-thio-beta-D-fucopyranoside (11) and 1-thio-alpha-D-mannopyranoside (16). A facile preparation of O-acylated p-nitrophenyl 1-thioglycopyranosides was achieved by condensing the appropriate glycosyl halide with sodium p-nitrobenzenethioxide in N,N-dimethylformamide.


The galactan sulphate of the red alga Polysiphonia lanosa. The structure of the galactan sulphate of P. lanosa has been established by a combination of methylation, treatment with alkali, and partial methanolysis of the alkali-treated polysaccharide to give derivatives of agarobiose. The polysaccharide belongs to the agar class, in which 3-linked derivatives of beta-D-galactose alternate with 4-linked derivatives of alpha-L-galactose in a repeating sequence. In addition to D-galactose itself, the 3-linked units include 6-O-methyl-D-galactose, D-galactose 6-sulphate, and a hitherto unreported unit, 6-O-methyl-D-galactose 4-sulphate. The 4-linked units include L-galactose 6-sulphate, 2-O-methyl-L-galactose 6-sulphate, and 3,6-anhydro-L-galactose.


Fragmentation analysis of extracellular acid polysaccharides from seven Rhizobium strains. Part I. D-glucuronic acid-containing oligosaccharides. The extracellular, bacterial polysaccharides from seven Rhizobium strains have been submitted to partial hydrolysis with acid. Several neutral oligosaccharides, some containing pyruvic acid, were isolated together with D-glucuronic acid-containing oligosaccharides. The polysaccharide from Rh. meliloti did not contain glucuronic acid. For the other six strains, the following components were characterized: 4-O-(beta-D-glucopyranosyluronic acid)-D-glucuronic acid, 4-O-(beta-D-glucopyranosyluronic acid)-D-glucose, and O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-O-(beta-D-glucopyranosyluronic acid)-(1leads to4)-D-glucose. These results indicate the presence of chains containing two beta-(1leads to4)-linked D-glucuronic acid residues, beta-linked to D-glucose at position 4.


Studies on synthesis of 1,2-cis-D-galactosides with partially benzylated intermediates. The 1-bromides of p-nitrobenzoylated 2-O-benzyl- (1) and 2,3- (8) and 2,6-di-O-benzyl-D-galactose (14) and 2-O-benzyl-D-glucose (20) were treated under Koenigs-Knorr conditions with 6-(trifluoroacetamido)-1-hexanol. Examination of the products by p.m.r. spectroscopy, g.l.c., and mass spectrometry revealed that, whereas the major product derived from 14 was the pyranoside (19), the glycosides derived from both 1 and 8 were mainly furanosides. The corresponding glycoside from 20 was entirely the pyranoside (23).


Comparison of clinical and hemodynamic assessment of cardiac disability. Clinical versus hemodynamic assessment of cardiac disability was compared in 187 patients with either coronary artery or valvular disease classified using the New York Heart Association classification (excluding class IV). The following variables were analyzed during rest and exercise: arteriovenous oxygen content difference (CavO2), cardiac index (CI), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), pulmonary arteriolar resistance index (PARI) and heart rate (HR). 180 comparisons of variables were made. Hemodynamic evaluation paralleled clinical evaluation only 19 times during rest and 12 during exercise. There were 5 instances of clinical and hemodynamic distinction between class I and II, 14 between class I and III and 12 between class II and III. Correlation was best in mitral stenosis. The most useful variable was CI followed by PAP and CavO2. HR was not helpful. This study emphasizes that subjective clinical disability may not correlate with physiologic derangement in certain patients.


Cardiac effects of sodium selenite.

Cardiac effects of sodium selenite. The classical idea that selenium is toxic to the heart at levels higher than available in a balanced diet is not supported by experimental work. In mice, treatment with sodium selenite increased the LD50 of ouabain and 2,4-dinitrophenol, and increased the tolerance to nitrogen inhalation. Although sodium selenite had no effect on the dog heart with circulation intact, there was a reduction in coronary vascular resistance in the heart-lung preparation. In the isolated ventricular segment perfused with blood, the administration of sodium selenite caused a positive inotropic effect which appeared even after blockade of beta-adrenergic receptors and in segments perfused with a Krebs-bicarbonate solution that was deficient in oxygen. These results cannot be explained merely as the correction of a selenium deficiency but rather as a positive influence of sodium selenite on the heart that has been acutely stressed by oxygen lack, ouabain, or 2,4-dinitrophenol.


Myocardial contractility in primary nonobstructive myocardiopathy. Left ventricular myocardial function was studied in 13 patients with primary nonobstructive myocardiopathy and compared to the values determined in two control groups. Peak rate of rise of ventricular pressure (max dp/dt) and rate of the proportional rise of ventricular pressure at max dp/dt [(max dp/dt)p-1] were significantly decreased and interval t-max dp/dt was significantly prolonged in primary myocardiopathy, indicating that decreased contractility is characteristic of this disease. Left ventricular pre-ejection period (PEP) was significantly prolonged and PEP/LVET (left ventricular ejection time) ratio was significantly higher in patients with primary myocardiopathy. Increased end diastolic volume (EDV) and end diastolic pressure (EDP) were not characteristic of this diease. Best correlations were found between (max dp/dt)p-1 and t-max dp/dt (r = 0.71). Good correlations between PEP/LVET and internal indices of myocardial contractility qualify this ratio as a simple and useful index of myocardial contractility in various heart diseases.


Left ventricular end-diastolic volume in advanced ischemic heart disease; comparison between healthy subjects and patients with mitral stenosis. The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV) and systolic ejection fraction (SV/EDV) were determined in 6 healthy subjects, 21 patients with ischemic heart disease and 8 patients with mitral stenosis by the left ventricular 133Xe washout technique. Cardiac and stroke indexes as well as left ventricular work and stroke work indexes do not differ in all three groups. A significantly higher EDV and ESV together with a low SV/EDV suggested impaired left ventricular function in patients with ischemic heart disease.


Studies on the hemodynamic changes induced by electrical stimulation of the vagosympathetic trunks in the dog. The effects of electrostimulation of the cephalic endings of the vago-sympathetic trunks on the systemic and perfusion pressure of the hind limb of the dog depend upon frequency, intensity and duration of the stimulus. The electrostimulation performed with stimuli of high frequency, low intensity and moderately long duration (rectangular waves of 1.5 V, 0.7 msec, 100 Hz) consistently elicited systemic hypertension and vasoconstriction. This response was completely abolished by pretreatment with guanethidine or hexamethonium. On the other hand, electrostimulation with stimuli of low frequency, high intensity and long duration (5 V, 1 msec, 10 Hz) produced systemic hypotension and vasodilatation in the perfused hind limb. These effects were completely blocked by atropine or hexamethonium, while guanethidine was unable to induce any modification. These findings suggest that electrostimulation of vagosympathetic trunks can evoke different hemodynamic responses depending upon the characteristics of the stimulus. The occurrence of a  vasodilatation specifically blocked by atropine demonstrates that a purely cholinergic mechanism underlies such a reflex response.


Systolic pressure--diameter relations in the normal conscious dog. Pressure--diameter loops were generated in normal, conscious dogs during left ventricular contraction by means of endocardial ultrasonic gauges and micromanometers. Studies were made in the control state, during volume and pressure loading, and during enhancement of contractility. The diameter at the end of ejection was linearly related to systolic pressure, and the pressure--diameter relation at end-ejection was not affected by changes in preload. However, this relation was substantially displaced by changes in inotropic state, suggesting that the instantaneous pressure--length plane produced by pressure loading is unique to a given level of contractility.


The fractional rate of change of ventricular power during isovolumic contraction. Derivation of haemodynamic terms and studies in dogs. Power and the rate of change of power generated by the ventricle during isovolumic contraction can be calculated on the basis of the energy expended upon compression of the blood within the ventricle during this phase of systole. The ratio of the instantaneous rate of change of power, normalized to instantaneous power, appears to be an expression of particular physiological significance and practical value. This ratio, termed the isovolumic fractional rate of change of ventricular power, describes the capability of the ventricle to sustain an acceleration of energy production relative to instantaneous rates of energy production during isovolumic contraction. In dogs, the fractional rate of change of power changed insignificantly with changes of the preload and afterload; yet its magnitude varied prominently with drug-induced alterations of the contractile state. Although the isovolumic fractional rate of change of power takes a form that in some ways is similar to some previously derived indices of performance, it is independent of assumptions of ventricular geometry, fibre orientation, symmetry of contraction, or elasticity of muscle fibres. The isovolumic fractional rate of change of power is both meaningful and theoretically valid. For these reasons, it appears preferable to empirically-derived indices of performance or indices based upon assumptions which are approximations.


Ventricular fibrillation threshold in acute myocardial infarction and its relation to myocardial infarct size. The effect of myocardial infarct size on ventricular fibrillation threshold (VFT) was evaluated by determining changes in VFT during acute myocardial infarction and relating those changes to infarct size. Infarct size was estimated from gross measurement and from serial changes in serum CPK activity in 25 dogs. VFT reduction correlated well  with gross infarct size (r=0.92). This suggests that the severity of electrical instability during AMI is related to the size of the developing infarct, and that appropriate therapeutic interventions to reduce infarct size during this time may also render the heart more electrically stable.


The fractional disappearance rate of the separate isoenzymes of creatine phosphokinase in the dog. Separation of creatine phosphokinase (CPK) isoenzymes from canine tissue was accomplished successfully with column chromatography. Intravenous injection of each isoenzyme into six dogs resulted in a mono-exponential loss with differing fractional disappearance rates with averaged 0.65%, 0.86%, and 1.68%/min for the MM, MB, and BB isoenzymes, respectively. The distribution volume also varied: MM averaged 6.7%/body weight, MB 7.8%, and BB 10.4%.


Uptake of 125I albumin by the endothelial surface of the isolated dog common carotid artery: effect of certain physical factors and metabolic inhibitors. A study has been made, under transient conditions, of the uptake of 125I albumin by the endothelial surface of isolated dog carotid arteries. Effective rate constants were determined and the apparent activation energy was calculated to be about 13 kcal/mol in the range 25-37 degrees C. Label uptake was not significantly altered by the presence of 1 mmol/1 potassium cyanide or 10 mmol/1 iodoacetate in the incubating medium, or by the absence of substrate from it, consistent with the process being primarily passive. It appeared that the label entered the wall mainly by other routes than the endothelial inter-cell clefts.


Inhibitory action of acetylcholine on potassium uptake of the sinus node. The effect of endogenously released and exogenously administered acetylcholine on potassium uptake was studied in the sinus node of the guinea pig under different conditions. The results suggest the following conclusions: (1) acetylcholine is released in small amounts in the sinus node perfused in vitro and more so during electrical stimulation; (2) when the muscarinic receptors are blocked, an inhibitory action of endogenously-released acetylcholine on potassium uptake is revealed; (3) the inhibition requires small concentrations of acetylcholine, for 10(-5) mol/i eserine, by preventing acetylcholine hydrolysis, turns the inhibition into a stimulation of potassium uptake; and (4) the inhibitory action of acetylcholine on potassium uptake can be reproduced by administering small amounts of exogenous acetylcholine.


Analysis of sino-atrial conduction in man using premature atrial stimulation. Sino-atrial conduction was investigated using premature atrial depolarization in 25 patients seven of whom had sino-atrial block. The results obtained in this investigation were evaluated plotting the test cycle (expressed as difference between the basic sinus cycle and the test cycle as a percentage of the basic sinus cycle) as a function of the return cycle (expressed as difference between the return cycle and the basic cycle as a percentage of the basic sinus cycle). In normal subjects, premature atrial depolarizations elicited in the last 10-20% of the spontaneous sinus cycle, produced a progressive prolongation of the return cycle and the points correlating the return cycle index to the test cycle index fell above the diagonal of the plotting system. After earlier premature atrial depolarizations, the return cycle remained of the same length, and the points correlating the return cycle index to the test cycle index fell along a line parallel to the y-axis ('plateau'). The mean value of the returning cycles (as expressed above) corresponding to the test cycles (as evaluated above) included in the first 5% of the 'plateau' can be defined as 'the sino-atrial conduction index'. This index, the sum of conduction into and out of the sinus node, was found to range from 79 to 185 ms. By assuming similar anterograde and retrograde conduction, the sino-atrial conduction time ranged from 39.5 to 97.5 ms (mean value=70 ms). In the patients with sino-atrial block, fully compensatory pauses were observed for atrial premature depolarizations elicited up to the last 25-35% of the atrial cycle, and a slow and progressive divergence from the diagonal of the plotting system was seen instead of the 'plateau'. In these patients the sino-atrial conduction index ranged from 151 to 297 ms (mean 253 ms). By assuming similar antegrade and retrograde conduction, the sino-atrial conduction time ranged from 75.5 to 148.5 ms (mean value=126.5 ms) with a statistically significant difference with respect to normal subjects (P=0.001).


Mechanical effects of heart contraction on coronary flow. The mechanical effects of heart contraction on coronary flow were studied in the dog heart by implanting vessels in the subendocardial and subepicardial layers of the left ventricular wall and perfusing them independetly of the aortic pressure. At a perfusion pressure of 4 kPa (30 mm Hg), with spontaneous aortic pressure and heart rate, subendocardial flow was 40% less than subepicardial flow. Increasing the aortic pressure or the heart rate produced a comparatively larger decrease of the subendocardial flow. The results suggest that these changes are due to variations of the period of systolic time during which the vessels remain close.


Direct effect of thyroid hormone on intracardiac conduction in acute and chronic hyperthyroid animals. Studies of intracardiac conduction utilizing His bundle electrograms demonstrate direct thyroid hormone action on the conduction system in both acute and chronic hyperthyroid animals.


Inhibition of pacing-induced coronary dilation by aminophylline. In closed-chest anaesthetized dogs, aminophylline was infused into the left circumflex coronary artery at a rate of 250 mug/min. When the heart rate was lower than 100 beats/min, infusion did not modify the left circumflex coronary blood flow and resistance. When the heart rate was elevated to an average of 153 +/- 6 beats/min by right atrial pacing, infusion inhibited the increase in left circumflex coronary blood flow and decrease in coronary resistance. The pacing-induced increment in coronary blood flow was reduced by an average of 64% and the flow deficit was associated with a lowering of the coronary sinus blood oxygen tension. Since aminophylline is known to inhibit the coronary dilator action of exogenous adenosine, the results support the concept that adenosine resulting from the breakdown of adenine nucleotides is a mediator of the metabolic regulation of coronary blood flow.


Changes in flow and pressure due to rotation of a saphenous vein segment. The effect of axial rotation on flow through and pressure gradient across saphenous vein segments was studied using 15 cadaver long saphenous veins. A significant reduction in flow occurred at a mean rotation of 25 degrees/cm and a significant increase in head loss across the segments occurred at a mean rotation of 23 degrees/cm. Collapse of the vein segments occurred at a mean rotation of 27 degrees/cm.


Optimal length of a saphenous vein segment when used as an arterial substitute. An in-vitro experiment using 12 cadaver long saphenous veins was performed to determine the optimal length of a saphenous vein segment intended for use as an arterial substitute. This length was found to be 8% greater than the body length, as judged by maximal flow through the veins and 6% greater than body length judged by minimal pressure loss across the vein segments. Extreme extension of the veins resulted in incomplete transverse rupture of the inner layers of three of the veins tested.


Ultrasonic measurement of prosthetic heart valve action. An in-vitro study has been made of the echo patterns obtained during ultrasonic Time-Motion (T-M) scanning of commonly used prosthetic heart valves. Studies have been undertaken of Starr-Edwards, Beal, and Björk-Shilley valves. From the recorded traces information has been obtained regarding the orientations of the ultrasound beam to the central axes of the valves for which accurate measurements can be made. The orientations have been determined for which the opening and closing times of the valves can be measured to within 20 ms. Characteristics of the T-M trances have been noted which allow the angle between the direction of an ultrasound beam and a central valve axis to be reduced to less than 20 degrees. This makes the error due to angular misalignment of the beam less than --6% when the range of movement of a ball, disc, or flap is being measured. Finally a number of artefacts are considered which can arise when prosthetic valves are examined with ultrasound.


Effects of prindolol on isoproterenol-induced subendocardial ischaemia in dogs with multiple chronic coronary artery occlusion. Multiple chronic coronary artery occlusions were produced in dogs by implantation of ameroid rings on the circumflex branches of the left and right coronary artery. Sixty-five per cent of the animals survived. Seventy-seven per cent of the remaining animals had no detectable myocardial infarction. Myocardial blood flow distribution was studied 4 weeks after operation using the tracer microsphere technique. During control conditions myocardial blood flow was homogeneously distributed within the left ventricle. In one group of dogs, regional dilatory capacity was tested by intravenous infusion of dipyridamole. Four compartments of myocardial blood flow were found. The collateral dependent subendocardium with 114 ml/min-100 g-1 was the lowest perfusion rate. In another group of dogs myocardial blood flow distribution was examined during isoproterenol infusion and after beta-blockade with prindolol during continuous isoproterenol infusion. During isoproterenol infusion, a nonhomogeneous blood flow pattern was found when the heart rate increased to 200/min together with a slight fall in diastolic perfusion pressure. Under these conditions, the flow to the collateral dependent subendocardium was severely diminished, while the flow to the areas perfused by normal coronary arteries increased, reflecting compensatory vasodilation. After beta-blockade with prindolol 0.1 mg/kg, the myocardial blood flow distribution was also nonhomogeneous but in the opposite direction: the collateral dependent subendocardium was now the best perfused compartment. The flow to the areas perfused by normal coronary arteries decreased due to the reduced oxygen requirements, while the collateral dependent subendocardium remained maximally dilated. This phenomenon was explained as a postischaemic reactive hyperaemic response to the isoproterenol-induced ischaemia in the collateral dependent subendocardium.


Effects of verapamil on infarct size following experimental coronary occlusion. Open-chest anaesthetized dogs were given verapamil after left anterior descending artery occlusion, and ST-segment alterations and haemodynamic variables were monitored. Verapamil produced a highly significant reduction in ST-segment elevation in the epicardial electrocardiogram and prevented the haemodynamic deterioration seen in the control animals in which ST-segment elevation persisted. The apparent protective effect of verapamil in myocardial ischaemia is discussed in relation to its ability to inhibit selectively the transmembrane fluxes of calcium ions in excitable tissues.


Presynaptic dendrite cells and two other classes of neurons in the superficial layers of the superior colliculus of the chimpanzee. In the superior colliculus of chimpanzee, three classes of neurons can be identified by ultrastructural criteria. They are 1) marginal cells located in the stratum zonale, 2) collicular relay cells in the stratum griseum superficiale and 3) presynaptic dendrite (PSD) cells, i.e., neurons with presynaptic specializations in soma and/or dendrites. PSD cells are the smallest neurons in the stratum griseum superficiale; they have a relatively large, deeply infolded nucleus and a small rim of cytoplasm rich in free ribosomes. PSD cells are sufficiently different from the two other classes of neurons to be reliably identified at the ultrastructural level. They closely resemble presynaptic neurons as described in the lateral geniculate nucleus of other mammalian species. Presynaptic dendrites in continuity with PSD cells are rich in organelles, especially ribosomal cluster, and establish en passage contact with other dendrites. Another type of presynaptic dendrite, poor in organelles, except for bundles of microtubules, could not be traced back to its parent neuron. Homo- or heterogeneity of PSD cells is discussed. No amxon was traced from a PSD cell.


Immunoelectron microscopic evidence of contractile proteins in the cellular and acellular components of mouse kidney glomeruli. Actin and/or actin-like protein have been localized in the cellular and acellular components of the glomerular walls of mouse kidney by means of immunoelectron microscopy, employing human antibodies to smooth muscle (SMA). Contractile antigens have been confirmed to be present in the cytoplasm of podocytes and mesangial cells in association with fine filaments which are considered of importance in the control of blood flow, intravascular pressure, and filtration rate within the glomerulus. The extracellular presence of contractile proteins in the mesangial matrix and glomerular basement membrane can be related to cell movement in a frictional environment. This latter phenomenon, which is strictly interdependent with cell adhesion and aggregation, is most evident in the mesangial cells in a form of luminar pseudopodia, cytoplasmic projections, and phagocytosis.


Troponin bound calcium in electron micrographs of myocardial cells as demonstrated by the potassium-antimonate technique. Following the K-antimonate reaction in atrial myocardial tissue, a pattern of evenly spaced cross striations of antimonate precipitates is demonstrated along the myofilaments. This spacing, found in both turtle and mouse atria, has a periodicity of about 400 A. In order to test the shifts of the antimonate reaction product in the tissue, a comparison is made between the localization of the antimonate precipitate as seen in viz. thin plastic sections and in cryo-ultra sections being dry-cut at -90 degree C from N2 frozen tissue. Preliminary results suggest only minor distributional differences in the sarcomeric pattern. On the basis of these tests, and, on the basis of previous studies by means of X-ray microanalysis, it is suggested that the periodic pattern of evenly spaced precipitates, reflects the localization of troponin bound calcium along the thin filaments during contraction.


Role of the "thrombocytoids" in capsule formation in the dipteran Calliphora erythrocephala. Of the three hemocyte types present in the blood of Calliphora, only one participates in capsule formation around implanted cellophane. This hemocyte, the thrombocytoid, shows in the blood a tendency to dissociate into numerous small cytoplasmic fragments, comparable to the mammalian megakaryocyte. This tendency is dramatically increased during the process of encapsulation. Most of the intact thrombocytoids and the numerous fragments participating in capsule formation do not show any particular modifications in their cytoplasm during this process, which corresponds to a mere sequestration of the implant. Dense material, resulting from necrotic cell debris and hemolymph lipoproteins, is often observed between the cellophane and encapsulating thrombocytoids, which apparently participate in the resorption of this material.


Observations on peroxisomes in interrenal (adrenocortical) cells of Triturus cristatus and Salamandra salamandra (Urodele Amphibians). Intracellular organelles (average diameter: 0.3 mu) similar to peroxisomes were observed in the interrenal cells of Triturus cristatus and Salamandra salamandra. Their peroxisomal nature was demonstrated by incubating tissue sections in alkaline 3,3-diaminobenzidine. Oxidation of diaminobenzidine, a characteristic feature of peroxisomes, was observed. These organelles are devoid of a central nucleoid and are surrounded to various degrees by profiles of the smooth endoplasmic reticulum. The matrix of these organelles is sometimes in direct communication with the inside of the smooth tubules. These relationships suggest a possible origin of the peroxisomes from the smooth endoplasmic reticulum.


Cytochemical and electron-microscopic study of the paraoesophageal bodies and related nerves in Schizophyllum sabulosum (L.), Diplopoda Julidae. The ultrastructural study of the paraoesophageal bodies of Schizophyllum sabulosum reveals the occurrence of two axonal types (ax 1 and ax 2) near secretory cells. Two possibilities exist for the functional role of the nerves related to these paraoesophageal bodies. The results of treatment with proteases (pronase, pepsin, trypsin) and the identification of glycogen in both the paraoesophageal bodies and the nerves that link them to the brain and Gabe organs, suggest transport of at least part of the secretions from the paraoesophageal bodies to the Gabe organs.


Surface fine structure of the globiferous pedicellariae of the regular echinoid, Psammechinus miliaris Gmelin. The globiferous pedicellariae of Psammechinus miliaris are described. Two fixation methods giving minimal distortion and rapid tissue hardening were adapted for soft tissue preparation for scanning electron microscopy. The pedicellarial valves are covered by a microvillous epithelium. The outer valve epithelial microvilli overlying red spherulocytes in the epidermis are characterized by a filament matrix radiating out from each microvillus. These microvilli may function in epidermal absorption of organic solutes. The inner valve microvilli are more densely packed and the filament matrix is absent. Ciliation is confined to the inner valve surface where the cilia are concentrated to form a distal sensory pad and sensory hillock. Behavioural evidence suggests a chemo- and mechanosensory role for the inner valve surface.


Ultrastructure of the larval corpus allatum of hyphantria cunea Drury (Insecta, Lepidoptera). The corpora allata of the three last larval instars were studied in newly molted animals, at the beginning, middle, and end of the feeding period, and during the molt period. They were found to consist of uniform gland cells, whose ultrastructure changes in the course of the instars. In glands cells considered to be resting, the outer and inner nuclear membranes run in parallel without forming a dilated perinuclear space. Mitochondria are small, polymorphic, with an electron-dense matrix. The smooth endoplasmic reticulum (SER) appears as stacks of parallel cisternae near the nuclear envelope and in the rest of the cytoplasm, and as accumulations of twisted profiles. Occasionally, the SER takes the form of paracrystalline bodies. There are few small smooth-surfaced vesicles in the cytoplasm. In cells considered as active, a dilated perinuclear space occurs. The peripheral ends of profiles forming the SER are swollen, and numerous vesicles and vacuoles bud off from them to fill the cytoplasm. Mitochondria are large, with a more transparent matrix. The plasma membrane of gland cells located just beneath the connective tissue sheath forms numerous small invaginations. The corpora allata consist of resting cells during the molt periods. At the beginning of each instar, few active gland cells appear. In the middle of the second to last and the third to last instars, the bulk of the gland cells is active. At the end of these instars, there are both active and inactive cells. In the middle of the last instar, the gland cells are inactive or subactive, and at its end, all gland cells are completely inactive.


The fine structure of the hypothalamic secretory neurons of the white-crowned sparrow, Zonotrichia leucophrys gambelii (Passeriformes: Fringillidae). I. Parvocellular tuberal nuclei. The fine structure of the parvocellular tuberal nuclei and that of the ependyma bordering the third ventricle in the basal hypothalamus of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, have been investigated. Photoperiodically stimulated birds have been compared with birds held on short days. The perikarya of the neurons of the basal infundibular (tuberal) nucleus, and in part, of the more dorsal layers, contain dense-cored granules (1000-1500 A). The granules in the anterior part of the nucleus are somewhat larger than those of the posterior part. The synapses and the synaptic relationships of these cells are described. The single-layered ependyma of the third ventricle in the basal hypothalamus may be divided into the dorsal typical ependyma, the ventrolateral "glandular" ependyma, and the ventral "glandular" ependyma. Cells of the ventral ependyma lack apical cilia but bear a few microvillous processes. They have well-developed Golgi apparatus, conspicuous polysomes, and frequently dense, irregularly-shaped granules. Basal cytoplasmic processes extend ventrally to the outer surface of the median eminence. Photoperiodic stimulation appears to increase the numbers of apical protrusions of the cells in the ventral glandular ependyma and to cause an increase in size of the nerve cells of the basal infundibular nucleus.


Larval and adult eye of the western rock lobster (Panulirus longipes). A number of differences exists between the compound eyes of larval and adult rock lobsters, Panulirus longipes. The larval eye more closely resembles the apposition type of compound eye, in which retinula cells and rhabdom lie immediately below the cone cells. The adult eye, on the other hand, is a typical clear-zone photoreceptor in which cones and retinula cell layers are separated by a wide transparent region. The rhabdom of the larval eye, if cut longitudinally, exhibits a "banded" structure over its entire length; in the adult the banded part is confined to the distal end, and the rhabdom is tiered. Both eyes have in common an eighth, distally-located retinula cell, which possesses orthogonally-oriented microvilli, and a peculiar lens-shaped "crystal", which appears to focus light onto the narrow column of the distal rhabdom. Migration of screening pigment on dark-light adaptation is accompanied by changes in sensitivity and resolution of the eye. Retinula cells belonging to one ommatidium do not arrange into one single bundle of axons, but interweave with axons of four neighbouring facets in an extraordinarily regular fashion.


The general ultrastructure of the carotid body of the domestic fowl. Electron microscopic studies of the carotid body of the domestic fowl (Gallus gallus domesticus) have shown Type I and Type II cells combined with axons into compact groups. The many Type I cells in the depths of the organ had a body, containing the nucleus, and an elongated, flared process. Some of the Type I cells in the superficial regions tended to be spindle-shaped. Type I cells were characterised by membrane-bound, dense-cored vesicles about 120 nm in diameter. Type II cells invested the Type I cells and had axons embedded in them as in Schwann cells. The fine structure of the carotid body in the domestic fowl resembles that of the Lovebird (Uroloncha domestica) and of various amphibia and mammals. The possibility is discussed that the Type I cells may have a chemoreceptor or a general secretory function, or even both of these axons leading to or from Type I cells. The main role of the Type II cells seems to be to provide a pathway for functions together.


Immunocytochemical identification of neurophysin-secreting neurons in the hypothalamo-neurohypophysial system of some non-mammalian vertebrates. Antiserum raised against a mammalian neurophysin, porcine neurophysin-II, was used in conjugation with the immunoperoxidase histochemical technique to detect neurophysin in the hypothalamus of the chickens, frog and goldfish. In the chickens, the paraventricular and supraoptic nuceli as well as the internal and external zones of the median eminence stained for neurophysin. Material in the perikarya of the frog and goldfish preoptic nucleus also cross-reacted immunologically against anti-porcine neurophysin-II serum. Serial dilutions of the anti-mammalian neurophysins serum were carried out in order to ascertain at which point the 3-layer immunocytochemical reaction ceased to localize neurophysin. In the chicken, frog and goldfish as well as in the rat, neurosecretory structures became difficult to visualize between 12800 and 25400 fold dilution of antiserum. The results demonstrate that the immunological cross-reactivity previously observed between an anti-mammalian neurophysin serum and the neurophysin isolated from mammals of varying phylogeny also extends to certain non-mammalian vertebrates and is suggestive of a structural homology of neurophysin from different species.


Ultrastructure of the adrenal medulla of normal and insulin-treated hamsters. Fine structural characteristics of the chromaffin cells both in normal and insulin-administered hamster adrenal gland were studied. Exocytosis occurs in 5 per cent of nonstimulated cells especially on the apical cell surfaces. At the same time the occurrence of a great number of closely attached secretory granules was conspicuous on the lateral plasma membrane in the untreated hamster adrenal medulla. Following insulin treatment (10 IU/100 g/body weight), characteristic was the development of large intercellular vacuoles between the lateral plasma membrane, in which electron-dense secretory material was frequently present. On the basis of this observation it is suggested that in the case of insulin-induced hormone secretion, exocytosis preferentially occurs on the lateral plasma membrane, and may play an important role in the discharge of secretory materials from the cells.


Indoleamines and the eccentric cells of the limulus lateral eye. The lateral eye of the horseshoe crab, Limulus polyphemus, was studied by fluorescence microscopy according to Falck and Hillarp and microspectrofluorometry for identifying neuronal monoamines. After the formaldehyde treatment, the eccentric cells and their axons have a yellowish, rapidly fading fluorescence, such as is seen with 5-hydroxytryptamine. The microspectrofluorometric analysis was compatible with the fluorescence being caused by an indole, which could not be definitely identified, however. The eccentric cells have the ability to accumulate indoleamines such as 5-hydroxytryptamine, 6-hydroxytryptamine and 5,6-dihydroxytryptamine. Their axons were best demonstrated after being loaded with 6-hydroxytryptamine. Characteristic varicose terminals were seen in the neuropil, often arranged in clusters. Other terminals, possibly originating from the eccentric cells, were also seen among the pigment cells in the basal part of the ommatidia.


In vitro culture of the proximal tubule of the bovine nephron: transmission and scanning electron microscopy. By means of a previously described method, viable pure tubules of the nephron were isolated in high yield from the outer cortex of the near-term foetal bovine kidney. The tubular suspension obtained was constituted almost exclusively of proximal segments (about 95%), whose cells were dispersed and grown as confluent primary cultures. The cultured proximal cells were shown to maintain in vitro, on glass or plastic surfaces, the same orientation as on the tubular basement membrane in vivo, with interdigitations extending from the base of the cells and along their full height. Numerous mitochondria and the typical cytoplasmic bodies of the proximal cell were retained in cells grown in vitro. A flagellum was seen in every cultured cell and was shown to be present in the proximal cell in vivo. There is a progressive change, in vitro, of the microvilli of the brush border, from a close-packed to a sparse distribution and to a decrease in height and a reduction in number. This in vitro regression to an earlier embryonic state was correlated with the ability of the proximal cells to synthesize in vitro an alpha-fetoprotein and with the loss in vitro of histiospecific antigen synthesis, confined in vivo to the brush border area. The confluent proximal cells became filled with microfilaments and microtubules, the significance of which is discussed.


A scanning electron microscopic study of rabbit spermatozoa in the female reproductive tract following coitus. The surface morphology of rabbit spermatozoa, fixed in situ (female reproductive tract) and prepared for scanning electron microscopy by critical point drying, was studied for as many as 36 hours post coitum. The findings demonstrate that 1) spermatozoa in the reproductive tract following coitus exist as a heterogenous, morphological population and 2) with time, shifts within this population from one predominant morphology to another take place. In the fresh ejaculate, most spermatozoa have intact surfaces free of membranous disruptions.  With time, a process of labilization (denudation) of the membranes covering the acrosomal region occurs in a progressively larger proportion of spermatozoa. The labilization originates by a process of vesiculation and/or vacuolation and leads to the appearance of a series of small fenestrations of perforations of the surface membranes. The perforations coalesce, and gradually larger areas of the surface membranes are eroded such that by 15 hours post coitum, the outer acrosomal membrane, as well as other acrosomal areas, are to varying degrees, directly exposed to the uterine milieu. Secretory granules, picked up by cilia and transferred to the spermatozoa become localized over the acrosomal region shortly after coitus. The possible significance of these time-dependent morphological events with the phenomena of capacitation and the "true" and "false" acrosome reactions are discussed.


The retina-lamina projection in the visual system of the bee, Apis mellifera. Single Golgi impregnated visual cells and their axons were treated from the retina to the first synaptic layer (lamina) in serial electron microscopic sections. This analysis of the retina-lamina projection was undertaken in the upper dorso-median eye region which is known to be involved in the perception of polarized light. For identification of individual visual cells and their fibres a numbering system was used which relates the number of each of the nine visual cells within one retinula to the transverse axis of the rhabdom (TRA) (Fig. 1). Because of the twist of the retinula along its course to the basement membrane (Fig. 6), individual visual cells change their position relative to any eye-constant co-ordinate system. Each axon bundle originating from one 9-celled retinula performs a 180 degrees-rotation before entering the lamina (Fig. 2). The direction of rotation (clockwise or counter-clockwise), which may differ even between adjacent bundles, is related to the two mirror-image types of rhabdoms in the corresponding retinulae and is opposite to the direction of rhabdom twist. Thus, even in small groups of the in total 5500 ommatidia in the eye of the bee, two types of retinulae exist which can be characterized by the geometry of the rhabdoms as well as by the direction of rotation of the retinulae and the axon bundles (Fig. 1). Visual cell numbers 1, 2, and 9, the microvilli of which are oriented in the direction of TRA, form three long visual fibres terminating in the second synaptic layer (medulla). In cross sections of laminar pseudocartridges they appear as the smallest fibre profiles arranged in a symmetrical line of the pseudocartridge bundle (=the transverse axis of the pseudocartridge; TPA) (Fig. 4). The remaining six fibres (cell numbers 3-8) only project to the lamina (short visual fibres; svf's). Two of them (cell numbers 5 and 6), which are the largest cells in the proximal retinula and have their microvilli perpendicularly arranged to TRA (Fig. 1), give rise to the two thickest axons of the underlaying pseudocartridge. In cross sections, t he connecting line of these two axons is orthogonally oriented to TPA (Fig. 5). A model was developed, in which all long visual fibres originate from ultraviolet receptors and in which the polarization sensitivity of the basal ninth cell is enhanced by the twist of the rhabdom. Finally, this model is discussed in light of behavioral experiments revealing the ultraviolet receptors as the only cells involved in the detection of polarized light.


Production and fates of unique organelles (transosomes) in ovarian follicles of Gallus domesticus under various conditions. II. Production and fates of transosomes (sacs of ribosomes made in the follicular cells of an ovarian follicle and subsequently passed to the cytoplasms of the oocyte) have been studied by electron microscopy in ovaries of young chicks, a testosterone-treated hen, aged hens which had ceased laying eggs and a "non-layer" mutant. Study was also made of "primitive yolk" (vacuoles present in both follicular cells and ooplasms of small follicles of normally laying hens). It was found that both transosomes and vacuoles of primitive yolk were present in small oocytes of young chicks, and "non-layer" mutants. However, the transosomes deep within the ooplasms were present within lysosomal vesicles in both of these instances and the vacuoles containing primitive yolk were patently abnormal in the "non-layer" mutant. Very few transosomes or primitive yolk vacuoles were present within the ooplasms of follicles from a testosterone-treated hen or from those of aged hens which were no longer laying. In both of these latter cases such bodies were present in the follicular cells. However, many transosomes were seen to be in the process of being lysed within the cytoplasms of these follicular cells.


The surface fine structure of the bovine subcommissural organ. The bovine subcommissural organ was studied by using scanning electron microscopy. The most prominent findings was the existence of protruded and dilated endings of the ependymal cells. The majority of these cells were ciliated with two or more cilia; only a few unciliated cells were seen. Some pore-like structures were also seen on the surface. From the functional point of view, the most interesting finding was an amorphous heterogeneous material on the subcommissural ependyma. Especially in the caudal part of the organ this material accumulated in abundance. No real filamentous structures such as Reissner's fibre could be seen, however, it was assumed that the heterogeneous material corresponds to this formation. No supraependymal neurones were demonstrated.


Ultrastructural observations on human cerebral capillaries in organ culture. The use of an organotypic-in the strictly literal meaning of the word, nervous tissue culture device has allowed the identification and ultrastructural study of various types of developing capillaries in human cerebellum and olfactory bulb in vitro. Most capillaries were similar to those already described by other authors or by us, in human or animal embryos and fetuses. Large Type I Capillaries. Their luminal diameters were greater than 8 microns. The basement membranes were thin and discontinous. Numerous interendothelial junctions were either plate-like attachments or contained pentalaminar zones. Type II Capillaries. Their lumina were between 2 and 8 microns in diameter. The basement membranes were wider than those of type I capillaries and were sometimes continuous. The interendothelial junctional complexes of type II capillaries included pentalaminar portions. Many simple or complex vascular sprouts (type IV and V capillaries) had small or non-patent lumina. Their basement membranes were absent or very thin and discontinuous. Their interendothelial junctions were similar to those of type I capillaries. Some of the less frequently encountered capillary types seen in developing human nervous tissue were absent in culture. Some pathological features were seen-especially in long-term cultures-in type I and II capillaries containing degenerating blood cells or processes sometimes obviously related to histiocytic cells. They consisted mainly of an accumulation of microfilaments and modifications of the rough endoplasmic reticulum in the endothelial cells. These pathological changes did not modify the main characteristics of the capillaries. The origin of the vascular sprouts, the exact nature of the interendothelial junctions and the significance of the pathological changes are discussed. This model may prove useful for the study of cerebral vasculogenesis, the development of the blood-brain barrier and the physiological or pathological properties of the human brain capillaries in tissue culture.


Fenestrated blood capillaries and lymphatic capillaries in rat skeletal muscle. Capillary fenestrae occur in one of about 60 cross-sectioned blood capillaries in normal adult rat skeletal muscles. The fenestrae occur singly or in groups. Fenestrated capillaries are found close to muscle fibers as well as in the perimysial and perineurial connective tissue. Small numbers of lymphatic capillaries are also present, mostly in the perimysial connective tissue.


The membrane systems of the cardiac muscle cell of Cirolana borealis Lilljeborg (Crustacea, Isopoda). The membrane systems of the cardiac muscle cell of the isopod Cirolana borealis Lilljeborg are described. The sarcolemma invaginates at the level of the Z band, forming transverse tubules. Narrow tubules branch off in a longitudinal direction from these transverse and radially arranged Tz-tubules forming a transverse collar at each A-I level, where dyadic and triadic junctions are formed with the sarcoplasmic reticulum. Two different orientations of the coupling discs have been detected in the supercontracted sarcomere, and this observation has been discussed. Adjacent myofibrils are separated by a double layer of sarcoplasmic reticulum.


Ultrastructure of muscle cells in Siboglinum fiordicum (Pogonophora). Two different muscle types are found in the body of Siboglinum fiordicum: body wall muscle and blood vessel muscle. Both are of a myomesothelial type. The myofibrils of the body wall muscle are non-striated and consist of thick and thin myofilaments. Scattered dense bodies and attachment plaques are described. The sarcoplasmic reticulum forms a three-dimensional network in the myofibrils and only peripheral couplings are observed. The thick filaments are of a paramyosin type and have a diameter ranging from 400-1500 A. The blood vessels muscle is non-striated, but sometimes a sarcomere-like organization has been observed. Both thick and thin filaments are present. The thick filaments have a diameter of 250-400 A and lack transverse striations. Dense bodies and attachment of plaques are few. The sparse sarcoplasmic reticulum is restricted to the myofibril periphery where it makes peripheral couplings with sarcolemma. The luminal surface of the vessels is lined by a basal lamina with collagen-like inclusions. No endothelium is found. The body wall muscle and the blood vessel muscle are compared with other muscle types described in invertebrates.


Hypertrophy of intestinal smooth muscle. Proximal to an experimental stenosis of the small intestine of rats and guinea-pigs a remarkable hypertrophy of the muscle coat develops 3-5 weeks after the operation. There is no increase in the length of the intestine but an overall increase in volume of the muscularis externa up to 10 times. This increase is accounted for by an increase in size and in number (by mitosis) of smooth muscle cells of both the longitudinal and circular layers. Bundles of newly-formed smooth cells appear in the serosa and are circularly arranged. In the hypertrophic smooth muscle cells of the circular layer the ratio of surface to volume is 0.80 (0.80 mum2 of cell surface for every mum3 of cell volume) as against 1.4 in the control muscle. The hypertrophic muscle cells have a highly developed sarcoplasmic reticulum and show a large number of nexuses. The density of innervation (number of axons per given number of smooth muscle cells) is smaller than in controls. Few collagen fibrils are visible in the extracellular space.


The composition and protein metabolism in the immature rabbit intervertebral disc. The nucleus pulposus (NP) and annulus fibrosus (AF) of immature rabbit intervertebral discs (IVD) have been subjected to the dissociative extraction procedure of Sajdera and Hascall (1969). The soluble, insoluble and unextracted fractions so obtained were analysed for total nitrogen, collagen, tyrosine, uronic acid, hexosamine and sialic acid content. A high proportion of non-collagenous protein, hexose and sialic acid in the NP insoluble fraction suggests the presence of glycopeptides associated with collagen and/or proteoglycans. The levels of proteoglycan in the soluble NP and AF fraction are similar. Immature (soluble) collagen, however, resides largely in the AF region. The metabolism of rabbit IVD protein components was also investigated both chemically and by autoradiography. L-Tyrosine-3,5-H3 was administered intraperitoneally (3 mc/kg) to 4 week-old rabbits. Animals were sacrificed at various time intervals and the harvested tissues extracted as before and lumbar discs collected. The levels of L-Tyrosine-3,5-H3 in the NP and AF insoluble and soluble fractions were determined using a tritium scintillation counting procedure and localisation by autoradiography. Pronounced extracellular activity of proteoglycan and glycoprotein is not evident before 24 hours. Soluble collagen, however, is synthesized and dispersed within 4 hours of isotope administration.


Selection and characterization of eight phenotypically distinct lines of lectin-resistant Chinese hamster ovary cell. Clones resistant to the lectins phytohemagglutinin (PHA), wheat germ agglutinin (WGA), the agglutinin(s) from Lens culinaris (LCA), and ricin (RIC) have been selected from parental auxotrophic Chinese hamster ovary (CHO) cells. The sensitivity to other lectins of these cells and of CHO cells resistant to concanavalin A (ConA) has been determined, and their activity of UDP-N-acetyl-glucosamine glycoprotein N-acetyl-glucosaminyltransferase (GlcNAc-T) has been measured. At least 8 different phenotypes have been identified on the basis of this analysis, and complementation between 2 of them demonstrated.


Alteration in cellular RNAs during the in vitro lifespan of cultured human diploid fibroblasts. An abrupt concommitant increase in total cellular RNA and protein was observed as cultured human diploid fibroblasts entered the senescent phase of their in vitro lifespan. DNA content remained stable from early to final passages. Fractionation of cellular RNAs by polyacrylamide gel electrophoresis demonstrated an increase in both 28S and 18S ribosomal and 4S transfer RNAs in these senescent cells. Separation of poly(A) RNA (mRNA) by oligo(dT)-cellulose chromatography suggests an increase in this group of RNAs. However, the ratios of 28S to 18S rRNAs, tRNA to rRNA, and mRNA to total cellular RNA were not significantly different in cells before and after senescence, indicating that the overall increases in total cellular RNA was not due to an accumulation of a single RNA class.


Ribosome binding to reovirus mRNA in protein synthesis requires 5' terminal 7-methylguanosine. Purified reovirus synthesizes in vitro a mixture of mRNA molecules that contain 5' terminal structures of the type ppG..., GpppG..., and m7GpppGm, the relative amount of each depending upon the presence of S-adenosylmethionine (SAM) or S-adenosylhomocysteine (SAH) in the transcription incubation mixture. Reovirus mRNAs containing 5' termini of the type ppG... and GpppG... can be specifically modified by wheat germ extracts in the presence of SAM to yield the structure m7GpppG...(Muthukrishnan et al., 1975). The mRNA methylase activity is ribosome-independent and is recovered almost entirely in the high speed supernatant fraction of wheat germ extracts. Its activity is inhibited by aurintricarboxylic acid. Ribosome binding experiments with reovirus mRNA and wheat germ extract indicate that only those mRNA molecules containing 5' terminal m7G are capable of participating in the initiation of protein synthesis and subsequent polysome formation. mRNA with unmethylated 5' termini do not form a complex with 40S ribosomal subunits. Discrimination between unmethylated and methylated reovirus mRNA, active in protein synthesis, apparently occurs at or before the formation of 40S-mRNA complexes. T1 or pancreatic RNAase digestion of methylated mRNA bound to 80S ribosomes yields 5' terminal fragments of apparent chain lengths about 32 and 36 nucleotides, respectively. A portion of the T1 RNAase-resistant fragments rebinds to ribosomes to form a nuclease-resistant complex. In contrast, the shorter 5' terminal oligonucleotide m7GpppGmpCpUp(Np)3Gp derived by RNAase T1 digestion of purified reovirus mRNA does not bind to ribosomes. The results suggest that 5' terminal m7G may function as the primary recognition signal for ribosome binding and that wheat germ ribosomes bind very close to the 5' termini of some of the species of methylated reovirus mRNAs.


The messenger RNA sequences in growing and resting mouse fibroblasts. The sequences present in messenger RNA in resting and growing 3T6 cells have been examined. First, the abundance and complexity classes of mRNA in growing 3T6 were compared to those in other established cell lines. The overall complexities measured for mRNA from HeLa cells and the three mouse fibroblast lines, 3T6, SV-PY-3T3, and L, are qualitatively similar and correspond to approximately 10,000 sequences. The relative amount of the two major abundance classes and their complexities appear identical in the three mouse fibroblast lines despite their different histories. HeLa cell mRNA is significantly different both in the amount and the complexity of the two major classes. The complexity of the two mRNA classes appears the same in resting and growing 3T6, although there is a small difference in relative amounts. Cross hybridizing cDNA and mRNA from resting and growing cells shows that the majority of mRNA sequences are the same in the two states. However, cross hybridization after the common sequences are removed shows that about 3% of the mRNA in resting cells is not present in the growing state, while the opposite cross shows 3% of the mRNA in growing cells is not present in resting cells. These differences may result from alterations in gene expression which are related to the growth state of the cell.


Initiation sites for translation of sindbis virus 42S and 26S messenger RNAs. Sindbis virus 26S RNA is the principal species of virus-specific RNA found in the infected cell; it is derived from a one third segment of virion 42S RNA. When translated in cell-free extracts from mouse ascites cells or rabbit reticulocytes, 26S RNA directed the synthesis primarily of the 33,000 dalton virus capsid protein, and the protein products were in the form of free peptides rather than peptidyl-tRNA. In contrast, the polypeptides synthesized in either extract in response to Sindbis virus 42S RNA were heterogeneous, ranging in molecular weight from 33,000 to 190,000, and were largely in the form of peptidyl-tRNA. The number of independent initiation sites on the 26S and 42S RNAs was determined by analyzing a tryptic digest of reaction products labeled with yeast N-formyl-35S-methionyl-tRNAFmet. The 26S RNA appeared to contain a single initiation site, and this site could also be found in varying amounts in different preparations of 42S RNA. However, a second initiation site, distinct from that of 26S RNA, was the major site in 42S virion RNA. These results suggest that 42S virion RNA contains two potential sites for initiation of protein synthesis. Only one of these may be active, however, and it is postulated that the second site functions primarily, if not exclusively, in the subgenomic 26S RNA species. In this regard, Sindbis virus 42S RNA may represent a novel form of a eucaryotic messenger RNA.


Genes for VA-RNA in adenovirus 2.

Genes for VA-RNA in adenovirus 2. VA-RNA from adenovirus 2 (Ad2) infected cells is shown to consist of two species. The gene coding for the major species maps at position 30 on the viral DNA, where it spans a site cleaved by the restriction enzyme Bam Hl. The minor species, constituting a few percent of the total VA-RNA, is distantly related in oligonucleotide composition to the major species. Its template maps within 700 base pairs to the right of the gene for the major species. The direction of transcription is from left to right on the conventional Ad2 map. These results, gained with a novel method for blotting (E. M. Southern, manuscript in preparation), have also led to the identification of the Bam Hl recognition sequence.


Fibrinolytic activity in a human fibrosarcoma cell line and evidence for the induction of plasminogen activator secretion during tumor formation. Seven clones were isolated from the HT1080 human fibrosarcoma cell line using a fibrinagarose overlay technique. Three of these clones induced lysis of the fibrin overlay, whereas four did not. The extracellular and intracellular levels of protease were then measured using 125I-fibrin plates incubated with acid-treated human serum. The extracellular protease can be directly assayed in the medium from cells incubated with 10% fetal calf serum. Although there were large differences in the amounts of protease secreted by these two sets of clones, the intracellular levels of protease were similar. No significant differences were found between the abilities of the cells to grow in soft agar or as tumors in immunosuppressed hamsters. However, cells grown from tumors derived from all the low secretors of protease showed an increase in the amount of protease secreted. It appeared, therefore, that the secretion of protease might be selected for or induced during tumor growth. Further detailed studies with one of the low secreting clones (clone E) suggested an inductive rather than a selective mechanism for this increase in extracellular plasminogen activator.


The effects of topoinhibition and cytochalasin B on metabolic cooperation. Metabolic cooperation was used to investigate the ability of 3T3 cells to form intercellular junctions under conditions of topoinhibition and topostimulation, respectively. A transformed BHK cell lacking hypoxanthine guanosine phosphoribosyl tranferase, which was used an an indicator, was found to incorporate 3H-hypoxanthine when in prolonged (20 hr) or brief (1 hr) contact with donor 3T3 cells, whether the latter were in a quiescent layer of in the region of stimulation at the edge of a wound. Cytochalasin B (1 mug/ml) prevented the development of metabolic cooperation and abolished most preexisting cooperation between donor 3T3 cells and recipient BHK cells. Cooperation was reestablished by removal of the drug. Cytochalasin B inhibited cooperation by the donor 3T3 cells in both the layer and wound edges, irrespective of topoinhibition and topostimulation. This provides further evidence that alteration in capacity to form stable intercellular junctions is not a necessary feature of the topoinhibition phenomenon.


Ultrastructural aspects of histolytic processes in the salivary gland cells during metamorphic stages in Rhynchosciara hollaenderi (Diptera, Sciaridae). The cytoplasm of Rhynchosciara hollaenderi late larval, prepupal and pupal salivary gland cells was studied at the ultrastructural level. In the second half of the 4th instar, evidence of an intensive secretory activity is visible in the form of numerous secretory granules in the apical area of the cells. At the same stage, the endoplasmic reticulum cisternae adjacent to Golgi groups are active in the transfer of vesicular elements. At later stages this activity rapidly diminishes. Before the appearance of the DNA puffs, i.e. at the end of the 4th instar, mitochondria begin to show a granular deposit and normal mitochondria decrease in number. These with the granular deposit form clusters and initiate formation of single autophagic vacuoles before the appearance of the DNA puffs. Later, at the time, when the 2B puff opens, the autophagic vacuoles appear in great number. Simultaneously with the formation of the autophagic vacuoles the presence of acid phosphatase in the Golgi vesicles and in autophagic vacuoles was shown. In the last stages investigated (late pupae) acid phosphatase is present free in the cytoplasm and at the same time disappearance of free ribosomes, pycnosis of polytene chromosomes and breakage of nuclear membranes occur. It is concluded that the histolysis of the salivary gland cells begins before the large DNA puffs appear, then it becomes very intensive and continues after these puffs undergo regression.


Histone synthesis in Rhynchosciara salivary glands. I. Site and timing of synthesis. The site of histone synthesis was studied in polytene cells of the salivary glands of the Rhynchosciara americana (Diptera). It was found that, as is the case in non-polytene systems, these proteins are synthesized in the cytoplasm in a class of light polysomes which contain 3-4 ribosomes. This class of polyribosomes is most active at about 5 days before pupation when the nuclei are most active in DNA synthesis and the chromosomes of the gland show many open 'DNA puffs'.


Investigation of lipid + water systems. Part 6. Proton magnetic resonance in ordered lyotropic mesophases. P.m.r. measurements have been made on macroscopically ordered samples of the smectic mesophase in two 1-monoglyceride + water systems and the 1-amino-octane + water system. Three doublets have been observed, one from hydroxyl protons, and the remaining two from methylene protons in two sections of the alkyl chain undergoing different types of molecular motion. The protons of the glyceryl residue also contribute to one of the alkyl chain doublets. The magnitudes of the doublet splittings have been measured at a number of different temperatures and compositions in each system. Some correlations have been made between the splittings obtained and the type of head group and the length and conformation of the alkyl chain. The effects of temperature change have been interpreted in terms of the increasing occurrence of gauche configurations in segments of the alkyl chain. Correlations have been made between degrees of order obtained from p.m.r. and d.m.r. spectra.


Raman studies of some diunsaturated olefinic and acetylenic fatty acids and their derivatives. The Raman spectra of CCl4 solutions of the 6,12; 7,12; 8,12; 9,12; and 10,12 isomers of octadecadiynoic acid and of the octadecadienoic acid methyl esters of both the cis,cis and trans,trans series are reported. Provided that there are two or more methylene groups between the unsaturated groups, the double and triple bond vibrational wavenumber values are close to those found in monounsaturated derivatives. An attempt has been made to obtain a correlation between the relative intensities of the nu(CequalsC) and delta(CH2) bands and the ratio of the number of double bonds to methylene groups in the molecule.


The PMR analysis of non-conjugated alkenoic and alkynoic acids and esters. The 220 MHz PMR spectra of 143 non-conjugated alkenoic and alkynoic acids and esters are correlated so as to provide a method for the structural analysis of such compounds in general. The spectral data are explained in terms of long-range deshielding of the double bonds, triple bonds, acid and ester groups in the molecules, and parameters are derived to quantify the influence of these groups on the chemical shifts of methyl and methylene protons up to six carbon atoms distant along an alkyl chain. It is shown that, by the application of these parameters, 220 MHz PMR spectroscopy can be used to determine both the stereochemistry and position of double bonds, and the position of triple bonds, in the majority of fatty acids and esters. The 2- to 9- and 13- to 17-cis- and trans-isomers of octadecenoic acid may be readily idenfited in this way, whilst for the octadecynoic acids all positional isomers may be characterized. Examples are also given of the structural analysis of several polyenoic compounds, including methyl cis-5, cis-8, cis-11, cis-14, cis-5, cis-8, cis-11, trans-14, and trans-5, cis-8, cis-11, cis-14-eicosatetraenoates, and methyl trans-5, cis-9, cis-12-octadecatrienoate.


Sinoatrial transmission and atrial invasion during normal rhythm in the rabbit heart. Intracellular microelectrodes and small unipolar leads applied to endocardial surface of the right atrium in vitro were used to study the complex extracellular wave patterns recorded from the neighborhood of the cardiac pacemaker during spontaneous activity. Sinus activity propagated slowly toward the site of atrial invasion on the venous border of the crista terminalis. Atrial activation was marked by a primary negative wave that appeared 20-40 msec after pacemaker firing. Two sources of complex multiphasic waves were found. First, potentials from transitional sinus tissue propagated toward the atrium and caused low-voltage waves that preceded and slurred the onset of the atrial initial negativity. Second, bundles and layers of the crista terminalis muscle were excited asynchronously around the invasion region, as if cross-connections were infrequent. Waves originating from this source occurred after the firing of the invasion site. No extracellular wave could be associated with the firing of the true pacemaker cells. The sinoatrial ring bundle (SARB) yielded a discrete biphasic deflection along most of its way toward the coronary sinus. This potential appeared most frequently after that of the adjoining cristal muscle, raising questions about the functional role of the SARB as an internodal preferential pathway.


Influence of cardiopulmonary vagal afferent activity on carotid chemoreceptor and baroreceptor reflexes in the dog. The goal of this study was to determine if physiological levels of cardiopulmonary vagal afferent activity modulate carotid chemoreceptor and baroreceptor reflexes. In anesthetized, ventilated dogs, the aortic nerves and the cervical sympathetic trunks were cut, and atropine was administered so that vagotomy would interrupt only cardiopulmonary afferent impulses. Reflex vascular responses were observed in perfused gracilis muscle and hindpaw. Carotid chemoreceptors were activated with nicotine or hypoxic, hypercapnic blood; carotid baroreceptors were stimulated by changes in carotid pressure. Interruption of vaga afferents augmented reflex vascular responses during changes incarotid pressure from 75 to 125 mm Hg. Interruption of cardiopulmonary vagal afferents potentiated reflex vasoconstrictor (muscle), vasodilator (paw), and vasopressor responses to activation of the carotid chemoreceptors. The potentiation of the chemoreceptor reflex frequently occurred in the absence of increases in base-line vascular resistance. Vagotomy also potentiated ventilatory responses to stimulation of the carotid chemoreceptors in spontaneously breathing dogs. The results indicate that interruption of cardiopulmonary afferents potentiates the vascular and ventilatory responses to activation of the carotid chemoreceptors and augments the gain of the carotid baroreceptor reflex at low carotid pressures. These findings suggest that physiological levels of cardiopulmonary vagal afferent impulses suppress carotid baroreceptor and chemoreceptor reflexes through an interaction in the central nervous system. The suppressive effect on the chemoreceptor reflex may be distinct from tonic restraint of the vasomotor center by vagal afferents, since it involves sympathetic vasodilator as well as vasoconstrictor responses and may occur without suppression of base-line adrenergic constrictor tone.


Inhibition of bradykinin vasodilation and potentiation of norepinephrine and angiotensin vasoconstriction by inhibitors of prostaglandin synthesis in skeletal muscle of the rat. Recent reports have indicated that vascular responsiveness can be altered by exogenously administered or endogenously released prostaglandins. Furthermore, in certain tissues inhibitors of prostaglandin synthesis have been shown to limit the increase in blood flow in response to bradykinin and to enhance the reduction in blood flow in response to angiotensin and norepinephrine. These findings suggest an important local circulatory role for prostaglandins. We attempted to implicate further prostaglandins in local blood flow regulation by examining the effects of indomethacin (IND) and 5,8,11,14-eicosatetraynoic acid (ETA), inhibitors of prostaglandin synthesis, on microvascular arteriolar responses to bradykinin, prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), histamine, norepinephrine, and angiotensin. Male Wistar rats were anesthetized with sodium pentobarbital, and their cremaster muscle was exteriorized and prepared for in vivo microscopic observation of microvessels. Changes in arteriolar luminal diameters in response to topical administration of vasoactive agents were quantified with an image-shearing measuring eyepiece in conjunction with a television microscope and recorder. Local administration of IND or ETA significantly reduced the arteriolar dilation elicited by bradykinin, whereas the responses to PGE1 and PGE2 remained unaltered. Responses to histamine, although somewhat reduced, were not significantly different from control. Vasoconstrictor responses of arterioles elicited by norepinephrine and angiotensin were potentiated by IND or ETA administration. These results indicate that prostaglandins synthetized in skeletal muscle microcirculation in situ (1) mediate, in part, vasodilator responses to bradykinin and (2) modulate vasoconstrictor responses to angiotensin and norepinephrine. Thus, these findings support the hypothesis that prostaglandins are local regulators of microvascular responsiveness.


Transmural gradients in ventricular tissue metabolites produced by stopping coronary blood flow in the dog. To determine whether transmural metabolite gradients develop in the contracting, ischemic left ventricle due to factors other than a nonuniform distribution of myocardial blood flow, right and left coronary artery inflow was completely stopped with vessel occluders in open-chest dogs for 15 or 30 seconds before a transmural myocardial tissue sample was obtained for regional analysis of creatine phosphate, adenosine triphosphate (ATP), and lactate. Heart rate was controlled, and the decline in left ventricular systolic pressure during the period in which coronary blood flow was stopped was attenuated by aortic constriction. Studies were also performed in dogs that were (1) pretreated with propranolol, (2) subjected to ventricular fibrillation, and (3) volume loaded. Control studies revealed no transmural metabolite gradients in the normally perfused ventricle, but creatine phosphate was slightly lower in the inner region than it was in the outer and middle ventricular wall regions. With coronary blood flow stopped for 30 seconds, a significant lactate gradient, increasing from the outer to the inner region, was present. Propranolol-treated dogs with their coronary blood flow stopped for 30 seconds also exhibited a lactate gradient, but dogs with ventricular fibrillation and their coronary blood flow stopped for 30 seconds did not. Volume-loaded dogs with their coronary blood flow stopped for only 15 seconds had a significant lactate gradient. Reciprocal gradients occurred in creatine phosphate but not in ATP. The findings suggest that the contracting ventricle uses energy unevenly and that in myocardial ischemia one of the factors causing greater subendocardial vulnerability is a greater energy need in this region.


Effect of spatial variations in shear on diffusion at the wall of an arterial branch. The effect of spatially varying shear on transport to the wall of a two-dimensional branch was examined, using oxygen as the test solute and the results of earlier fluid mechanical calculations to provide the shear profiles in a region characterizing the aortic bifurcation. The numerical technique employed allowed both blood-phase and mural resistances to solute uptake to be treated simultaneously and self-consistently. The calculated profiles of wall concentration and mural flux were significantly different from those which would have obtained if the shear had been uniform. The calculations suggest that, even when solute is rapidly taken up from the blood, the occasional high-shear and flow-development sites encountered along the arterial tree prevent the diffusion boundary layer adjacent to the wall from thickening to the point at which nutrition is compromised. The indirect effect of arterial geometry on transport, consequent to its direct effect on the magnitude and the distribution of the relevant hemodynamic variables, was illustrated using the branch area ratio as the geometric parameter. The shapes of the flux and interfacial concentration profiles along the branch wall were markedly dependent on the extent to which wall shear affected intimal permeability.


Changes in intramyocardial ST segment voltage and gas tensions with regional myocardial ischemia in the dog. This study was designed to evaluate the sensitivity of changes in myocardial carbon dioxide and oxygen tensions as indicators of regional myocardial ischemia and also to determine to what extent these changes can be related to changes in intramyocardial ST segment voltage. Changes in ST segment voltage recorded in unipolar epicardial electrodes proved to be a less-sensitive indicator of underlying myocardial ischemia than were changes in ST segment voltage recorded in unipolar intramyocardial electrodes. In 9 dogs, regional ischemia was produced by placing a variable constrictor on the left circumflex coronary artery; circumflex flow was monitored. Myocardial carbon dioxide and oxygen tensions were measured using a mass spectrometer. Unipolar electrograms were recorded using a multicontact plunge electrode. With progressive degrees of proximal stenosis, ranging from a critical stenosis, which is associated with a decrease in mean flow of less than 15%, to a severe stenosis associated with and 80% decrease, ST voltage increased 21 mv and carbon dioxide tension increased 84 mm Hg, but oxygen tension decreased only 7 mm Hg. The study suggests that increases in intramyocardial ST segment voltage, an index of myocardial ischemia, are associated with parallel increases in myocardial carbon dioxide tension, each providing a more sensitive quantitative correlate of regional myocardial ischemia than do decreases in oxygen tension. The local accumulation of carbon dioxide may be an important pathophysiological mechanism in myocardial ischemia.


Control of renin secretion in the dog. Effects of furosemide on the vascular and macula densa receptors. Experiments were undertaken to investigate further the effect of furosemide on renin secretion in the anesthetized dog. To separate the effects of the macula densa and the baroreceptor mechanisms, experiments were conducted in kidneys made nonfiltering by combining 2.5 hours of renal ischemia with ureteral ligation. Furosemide, in a dose of 5 mg/kg, increased renin secretion and decreased renal resistance in dogs with a nonfiltering kidney. Prior dilation of the nonfiltering kidney with either acetylcholine or papaverine prevented changes in both resistance and renin secretion. However, following dilation of the intact filtering kidney with acetylcholine, furosemide caused an increase in renin secretion. Infusion of d,l-propranolol decreased renin secretion in both the filtering and the nonfiltering kidneys. Following propranolol treatment, furosemide increased renin secretion in the filtering kidney but had no effect on renal resistance. These experiments indicate that furosemide stimulates renin secretion by both the macula densa and the baroreceptor mechanisms. The data suggest that stimulation of the sympathetic nervous system may alter renin secretion by modulating the renal baroreceptor, but sympathetic innervation does not appear to be involved in the macula densa mechanism.


Precordial and epicardial surface potentials during Myocardial ischemia in the pig. A theoretical and experimental analysis of the TQ and ST segments. The solid angle theorem was used to analyze the relationships between TQ and ST segment deflections recorded from precordial and epicardial locations and the time course, size, shape, and transmural location of the ischemic process in the ventricular myocardium. Mathematical predictions were compared with experimental data from the intact heart. Precordial electrograms obtained in anesthetized close-chest pigs were compared with epicardial electrograms recorded directly from the heart's surface. Various areas of ischemia were produced by occluding large and small coronary artery branches, and the resultant changes in ischemic shape were delineated with Thioflavin S injections and postmortem ultraviolet photography. Formally derived equations and cumulative experimental data were in close agreement, suggesting that in the ischemic ventricle (1) TQ depression always accompanies ST elevation, (2) TQ and ST segment changes in magnitude and polarity are complex functions of ischemic size, shape, and transmural location; (3) precordial electrocardiogram (ECG) ST segment elevation is directly related to ischemic size; and (4) epicardial ECG ST segment elevation is inversely related to ischemic size. It is thus concluded that precordial and epicardial ECG TQ and ST segment deflections are complex functions of ischemic geometry and that their accurate interpretation with respect to ischemic size and shape and in the presence of pharmacological interventions is often difficult and may be misleading.


Stress, deformation, and atelectasis of the lung. The lung parenchyma as a tissue has a rather unusual stress-strain relationship. A theoretical derivation of this relationship is presented which connects the surface tension and the tissue elastic stress in the alveolar septa with the alveolar geometry. The mathematical expression contains a few meaningful physical constants which can be determined by in vitro and in vivo experiments. With this stress-strain relationship, the general equations of lung mechanics are formulated, and solutions to some simpler problems are presented. First, the equilibrium of a lung subjected to a uniform inflation pressure (definition: alveolar air pressure - intrapleural pressure - pleural tension X mean curvature of pleura) is analyzed, and the stability of the equilibrium states with respect to small perturbations is examined. Second, an exact solution for a lung in a chest under the influence of gravity is presented; the solution is "exact," of course, for only a particular lung, but it can serve as a standard to check numerical procedures being developed in many laboratories. Finally, three types of possible atelectasis-planar, axial, and focal-are analyzed. The planar type can exist in a normally inflated lung, provided the layers of alveoli are forced to collapse toward a plane by some external agent. But axial atelectasis (alveoli collapse into a cylinder) can occur only if the dimension (at which the elastic tension in the alveolar septa vanishes). Similarly, focal atelectasis can occur only if the entire lung is smaller than the resting volume.


Does the surface tension make the lung inherently unstable? Many authors regard the human lung as a collection of 300 million bubbles independently connected by cylindrical tubes. Under surface tension such a model is inherently unstable in the sense that the small alveoli would empty into the large ones so that the lung would consist only of collapses and hyperinflated alveoli. It has been demonstrated that this basic model is wrong. My observation is based on the well-known fact that both sides of each interalveolar septum are exposed to ventilated air. When the topological relationship between the alveolar septa is properly taken into account, it can be shown that each interalveolar septum is a minimal surface and that there is no problem of inherent instability in the sense mentioned earlier. However, the lung structure is flimsy and can become unstable in the same sense that an airplane structure or an Atlas rocket can become unstable. The clarification of lung inflation and atelectasis can proceed in a rational manner when the confusion of an erroneous model is removed.


Static linear and nonlinear elastic properties of normal and arterialized venous tissue in dog and man. Ten normal and four transplanted canine jugular vein segments and four human saphenous vein segments were studied to determine the in vitro static elastic properties of venous tissue and their modification by transplantation into the arterial system. Both the intraluminal pressure and the longitudinal force were varied, and the resulting dimensions were recorded photographically. Venous segments manifested a hysteresis response but showed minimum tendency to creep. The pressure-strain relationships were curvilinear with an initial, highly compliant phase over the physiological venous pressure range followed by a relatively noncompliant phase. This transition occurred at lower pressures for jugular segments than it did for saphenous segments. In contrast, comparable-sized canine carotide artery segments did not show this essentially noncompliant phase over the pressure range studied (0 to 200 cm H2O). At comparable pressures and strains, the jugular vein segments were stiffer than the saphenous vein segments in both the circumferential and the longitudinal directions. At comparable strains, the saphenous vein moduli were similar to those in the carotid artery segments. Jugular segments transplanted into arterial circuits became virtually noncompliant and markedly inhomogeneous, with wall thickening and a histologic picture of intimal proliferation. They showed no tendency to "arterialize," that is, they failed to assume either the elastic or the histologic characteristics of arterial tissue.


Studies on magnesium's mechanism of action in digitalis-induced arrhythmias. The mechanism by which magnesium affects digitalis-induced arrhythmias was studied in dogs with and without beta-receptor blockade. Digoxin was infused at a rate of 2.5mug/kg/min until ventricular tachycardia developed, then half the animals were given MgSO4, the other half saline. In animals given MgSO4, sinus rhythm was immediately re-established; in animals given saline, ventricular tachycardia persisted. In animals with beta-receptor blockade, MgSO4 was as effective in abolishing ventricular tachycardia as in those without beta-receptor blockade. We found no evidence that magnesium re-activated digoxin-inhibited (Na+, K+)-ATPase, altered myocardial or microsomal digoxin binding, or acted via the autonomic nervous system. Magnesium's direct effect on calcium and potassium fluxes across the myocardial cell membrane may be the mechanism of its antiarrhythmic action in digitalis-toxic arrhythmias.


Ventricular arrhythmias in the late hospital phase of acute myocardial infarction. Relation to left ventricular function detected by gated cardiac blood pool scanning. Abnormalities of left ventricular function and extent of myocardial infarction were studied in relation to prevalence of late ventricular premature contractions (VPCs) in 36 patients in the convalescent stage of acute myocardial infarction (MI). Left ventricular ejection fraction (EF) and percent akinesis (%A) were calculated from gated cardiac blood pool scans; myocardial infarct size was estimated from peak CPK values; and VPCs were detected by 24 hour ambulatory ECGs 2-4 weeks following hospitalization for acute MI. Twenty-two patients had either zero (class 0) or less than 30/hour unifocal VPCs (class I). Fourteen patients had greater than 30/hour unifocal (class II), multifocal (class III) or coupled VPCs (class IV), including ventricular tachycardia. Thirteen of 14 class II-IV patients had EF less than 40% compared with only 8 of 22 class 0-I patients. Class II-IV patients had significantly lower mean EF (30.5 +/- 2.3 SE to 49.6 +/- 4.0) P less than 0.01, higher mean %A (28.1 +/- 2.2 to 16.9 +/- 3.7) P less than 0.05, and higher mean peak CPK (1350 +/- 187 to 721 +/- 155) P less than 0.05 than class 0-I patients. These data suggest that VPCs may not be an independent risk factor for sudden cardiac death in the convalescent phase of MI.


Time dependent changes in the functional properties of the atrioventricular conduction system in man. Time dependent changes in the electrophysiological properties of the atrioventricular conducting system (AVCS) were determined at two or more cycle lengths (CL) in 22 patients using bundle of His (H) electrograms, incremental atrial pacing and atrial extrastimulus method. The atrioventricular (A-H interval) and intraventricular (H-V interval) conduction times and refractory periods (RP) of the atrium, the A-V node (AVN) and His-Purkinje system (HPS) were measured during the control period, and repeat measurements were made after a 30 minute interval in eight patients (group A), after a 60 minute interval in nine (group B) and after 30 and 60 minute intervals in five (group C). No statistically significant changes from control values were seen after 30 and 60 minute intervals in any group in sinus rate, A-V nodal conduction time and the onset of A-V nodal Wenckebach block. H-V intervals were identical to the control values in all groups. Insignificant changes from control values occurred in RP of the atrium and HPS. Only the functional refractory period (FRP) of the AVN showed a statistically significant decrease from control values in groups B and C. This decrease could be explained by changes in autonomic tone. These observations in general confirm the reproducibility of electrophysiological properties of AVCS within one hour, and further support the validity of the techniques utilized in this and previously reported studies in the evaluation of cardioactive drugs.


Initial forces of ventricular depolarization in the Wolff-Parkinson-White Syndrome. Analysis based upon localization of the accessory pathway by epicardial mapping. The epicardial activation sequence of 34 patients with the Wolff-Parkinson-White syndrome was determined. Epicardial pre-excitation occurred at a spectrum of sites over either the free wall of the left or right ventricle or in a paraseptal region, always adjacent to the atrioventricular rings. The site of pre-excitation was related to the spatial position of the 10 msec vector of the vectorcardiogram (VCG) in 15 patients and the 20 msec vector of the electrocardiogram (ECG) in 29 patients with a single accessory pathway. All patients whose 20 msec vector (ECG) was directed to the right had accessory pathways which caused epicardial breakthrough over the free wall of the left ventricle. When the 20 msec vector (ECG) was to the left and inferior, epicardial pre-excitation was over either the right ventricular free wall or in the region of the pulmonary outflow tract. Superior location of the initial forces, especially the 10 msec vector (VCG), strongly suggested the presence of a septal bypass tract. The polarity of the delta wave and maximum QRS forces in precordial lead V1 were discordant in a significant number of patients, pointing to probable shortcomings of a classification based upon the latter.


Diagnostic accuracy of ambulatory ECG monitoring in ischemic heart disease. Fifty patients with precordial pain were evaluated by 24 hour ambulatory ECG monitoring during normal everyday activities, and by coronary arteriography. The monitoring was regarded as positive if deviation of the ST segment of 1 mm or more from the resting pattern was observed, or if major T wave inversion occurred. Comparison of the results of the two tests showed a good correlation. Among the 32 patients with positive abnormalities on ECG monitoring, 28 had severe coronary disease (greater than 60% obstruction). Among the 18 patients with negative monitoring, only three had severe coronary disease. All seven patients with major T inversion had significant coronary obstruction. The type of chest pain and the resting ECG were less indicative of coronary pathology. The good correlation demonstrated between the ambulatory ECG monitoring and coronary arteriograms validates the monitoring as a reliable tool for uncovering latent ischemic heart disease (IHD) and for evaluation of patients with established IHD.