Promotion of human adipocyte precursor replication by 17beta-estradiol in culture.

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Abstract

The influence of 17beta-estradiol and 17alpha-estradiol on adult human omental adipocyte precursors grown in a propagating culture system was studied. Cells were grown in subculture in the presence or absence of hormone. 17beta-estradiol resulted in significant promotion of adipocyte precursor replication, as determined by cell counting and incorporation of radioactive thymidine into DNA. The hormone stimulated cell multiplication in the concentration range 0.5--500 ng/ml growth medium. The highest level tested was 500 ng/ml. The maximal effects were obtained at 50 ng/ml (P less than 0.001 by paired t test, 48 h after hormone addition). All 10 cell strains (five were derived from men and five from women) that were tested responded similarly to the hormone. 17beta-estradiol did not affect cell size. 17alpha-estradiol did not promote the replication of adipocyte precursors, nor did it influence cell size. Thus, 17beta-estradiol, which is the active isomer in known target tissues, stimulates the multiplication of human adipocyte precursors in culture.

Authors

D A Roncari, R L Van

Pancreatic and Gastric Somatostatin Release in Response to Intragastric and Intraduodenal Nutrients and HCl in the Dog

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Abstract

The effects of the instillation of glucose, fat, casein hydrolysate, and HCl into the gastrointestinal tract upon plasma levels of somatostatin-like immunoreactivity (SLI) in the venous effluent of the pancreas, fundus and antrum of the stomach, and in the inferior vena cava (IVC) were determined in normal laparotomized dogs. Fasting SLI levels in the effluent plasma from these sites were significantly greater than IVC levels. The intragastric administration of glucose elicited a prompt and significant rise in SLI levels in pancreatic, fundic and antral venous plasma, and in IVC plasma; intraduodenal glucose elicited smaller increments. After intragastric fat, a smaller, more gradual increase in the pancreatic and fundic effluents was observed, whereas the rise in antral SLI was minute, and IVC SLI did not rise significantly. Intraduodenal fat elicited a prompt increase in the pancreatic and antral vein SLI levels, and a small but significant increase in fundic and IVC plasma which suggests faster release of enteric factors that influence SLI secretion in the pancreas and antrum. Intragastric casein hydrolysate elicited a prompt increase in SLI in both the pancreatic and fundic veins, the latter being marked, but the antral SLI response was small; IVC SLI rose significantly within 15 min. Intragastric HCl provoked a prompt and marked rise in pancreaticoduodenal and antral vein SLI but no increase in fundic vein SLI; IVC SLI levels rose significantly within 20 min. Intraduodenal HCl elicited an even more prompt and marked pancreatic SLI response, and SLI rose significantly in both the fundic and antral venous effluents; IVC SLI also rose more promptly. In dogs with a gastric fistula that prevented intraduodenal entry of HCl, intragastric HCl elicited only a very small and transient rise in pancreaticoduodenal vein SLI, markedly stimulated the antral SLI response, but completely suppressed fundic venous SLI levels.

Authors

Volker Schusdziarra, Virginia Harris, J. Michael Conlon, Akira Arimura, Roger Unger

The in vivo transfer of antigen-induced airway reactions by bronchial lumen cells.

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Abstract

Rhesus monkeys with airway responses to aerosol challenge with Ascaris antigen constitute a primate model of inhalant asthma. Previous studies have shown that bronchial lavage cells from airway-reactive animals will release histamine or a slow-reactive substance of anaphylaxis after challenge with antigen. Because these bronchial lumen cells are the first cells in contact with inhaled antigen, they may play a role in induction of antigen-induced airway responses. To evaluate this possibility, bronchial lumen lavage cells from animals with airway reactivity were transferred to the bronchial lumens of animals with negative airway responses to antigen challenge. The transfer of the bronchial lumen cells resulted in transient airway reactivity of the recipients to aerosol antigen challenge. It is suggested that the mast cells which constitute a component of the bronchial lumen cells may be the active cell alone, or in combination with other cells, which results in this primate immunoglobulin E-mediated airway response and its transfer to nonreactivie recipients.

Authors

R Patterson, I M Suszko, K E Harris

Glucose-Stimulated ⁴⁵Calcium Efflux from Isolated Rat Pancreatic Islets

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Abstract

Kinetics of 45Ca efflux and insulin release were studied in collagenase-isolated rat islets during 2-h perifusions with calcium-depleted (0.05 mM) bicarbonate-phosphate buffer containing 2.2 mM glucose. Addition of glucose (16.7 mM) suppressed 45Ca efflux by 30%. Removal of glucose caused an “off response” of insulin release. The perifusion of a normal concentration of Ca (2.3 mM) greatly stimulated 45Ca efflux, indicating Ca ↔ 45Ca exchange. When Ca and glucose were superimposed, the effects on 45Ca efflux and insulin release depended upon the order of presentation of the stimuli: when Ca was added to an ongoing 16.7-mM glucose perifusion, biphasic patterns of 45Ca and insulin release were seen; when glucose was superimposed on a Ca perifusion, an inhibition of the Ca-stimulated 45Ca efflux occurred, and a reduced but clearly biphasic insulin response was seen. The subsequent insulin off response after with-drawal of the glucose was also reduced.

Authors

Barbara J. Frankel, Walter T. Imagawa, Michael D. L. O'Connor, Ingmar Lundquist, John A. Kromhout, Rudolph E. Fanska, Gerold M. Grodsky

Relationship between the Rate of H⁺ Transport and Pathways of Glucose Metabolism by Turtle Urinary Bladder

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Abstract

The urinary bladder of the fresh-water turtle acidifies its contents by actively transporting H+ ions across the luminal membrane. It is known that the H+ transport system is dependent upon oxidative metabolism and the substrate glucose; however, the specific biochemical events resulting in H+ translocation have not been identified.

Authors

L. H. Norby, John H. Schwartz

Biosynthesis of Chenodeoxycholic Acid in Man: STEREOSPECIFIC SIDE-CHAIN HYDROXYLATIONS OF 5β-CHOLESTANE-3α, 7α-DIOL

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Abstract

Stereospecific side-chain hydroxylations of 5β-cholestane-3α, 7α-diol were studied in mitochondrial and microsomal fractions of human liver. Incubation of 5β-cholestane-3α, 7α-diol resulted in hydroxylations at C-12, C-24, C-25, and C-26. Hydroxylations at C-24 and C-26 were accompanied by the introduction of additional asymmetric carbon atoms at C-24 and C-25 respectively, that led to the formation of two distinct pairs of diastereoisomers, namely 5β-cholestane-3α, 7α,24-triols (24R and 24S) and 5β-cholestane-3α, 7α,26-triols (25R and 25S). A sensitive and reproducible radioactive assay to measure the formation of the different biosynthetic 5β-cholestanetriols was developed. Optimal assay conditions for human mitochondrial and microsomal systems were tentatively established.

Authors

S. Shefer, F. W. Cheng, A. K. Batta, B. Dayal, G. S. Tint, G. Salen

Accumulation of lysophosphoglycerides with arrhythmogenic properties in ischemic myocardium.

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Abstract

Lysophosphoglycerides, products of membrane phospholipid catabolism known to influence membrane function in several systems, appeared in the effluents of anoxic isolated rabbit hearts perfused at low flow and accumulated in perfused hearts and myocardium rendered ischemic in situ. Comparable concentrations of lysophosphoglycerides bound to albumin markedly and reversibly altered action potentials of isolated canine Purkinje fibers in vitro. Changes induced included diminution of the maximum diastolic potential, peak dV/dt of phase zero, amplitude, and action potential duration--alterations resembling those seen in ischemic myocardium in vivo. These electrophysiological alterations are compatible with changes implicated in predisposing to dysrhythmia dependent on reentry, a phenomenon potentiated by the presence of zones of decreased conduction. Thus, accumulation of lysophosphoglycerides induced by ischemia may contribute to the genesis of malignant dysrhythmia early after its onset.

Authors

B E Sobel, P B Corr, A K Robison, R A Goldstein, F X Witkowski, M S Klein

Propranolol Antagonizes the Anti-Inflammatory Effect of Alcohol and Improves Survival of Infected Intoxicated Rabbits

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Abstract

We studied the effects of alcohol and propranolol on the course of peritonitis in rabbits. Induction of sterile peritonitis with normal saline led to a 50% augmentation of granulocyte adherence in normal rabbits, and a mean cumulative granulocyte count of 27,000/mm3 in peritoneal exudate by 8 h. Rabbits intoxicated with alcohol at the time of peritonitis induction maintained a granulocyte adherence below pretreatment values, and only delivered a cumulative mean of 12,000 granulocytes/mm3 into the peritoneal fluid. When intoxicated rabbits received propranolol intravenously at the time of intoxication, adherence increased above preperitonitis levels, and stayed significantly above values for animals given alcohol alone. In addition, the defect in granulocyte delivery was prevented by propranolol, resulting in a mean cumulative granulocyte count in peritoneal fluid of 24,000/mm3.

Authors

R. Michael Buckley, Elvira S. Ventura, Rob Roy MacGregor

Antibodies to Histones in Drug-Induced and Idiopathic Lupus Erythematosus

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Abstract

When tissue sections are extracted with 0.1 N HCl, cellular nuclear proteins, including histones, are removed but nuclear DNA is retained. Histones can be reconstituted back to nuclear DNA in acid-extracted tissue sections so that the resulting nuclear substrate is composed only of DNA and histones and does not contain acidic nuclear protein antigens. The resulting DNA-histone tissue substrate can be used in the immunofluorescent method for specific detention of antibodies to histones. Sera from 23 patients with drug-induced lupus erythematosus (procainamide 19, isoniazid 2, nitrofurantoin 2) and 20 patients with idiopathic (not drug-induced) systemic lupus erythematosus (SLE) were studied. All 23 patients with drug-induced lupus erythematosus (LE) lost nuclear staining on acid-extracted sections. In contrast, only 12 of 20 with idiopathic SLE lost nuclear staining on acid-extracted tissues, and in the remaining 8, there was no significant fall in titer. In the drug-induced LE group, loss of nuclear staining was due to the absence of histones on the substrate because with histone-reconstituted sections, 22 of 23 again became positive for nuclear staining at titers equal to or at one doubling dilution below titers on unextracted tissues. In contrast, of the 12 idiopathic SLE sera which lost nuclear staining, only 5 regained nuclear staining on histone-reconstituted tissue sections. In idiopathic SLE, antinuclear antibodies are heterogeneous in specificities and may consist of antibodies to native DNA, histones, or nonhistone proteins. In contrast, antinuclear antibodies in drug-induced LE are less heterogeneous and mainly consist of antibodies to histones.

Authors

M. J. Fritzler, E. M. Tan

Tissue Guanosine-3′,5′-Cyclic Monophosphate Levels and Soluble Guanylate Cyclase Activity: A POSITIVE CORRELATION DURING UNILATERAL CRYPTORCHIDISM IN THE RAT TESTIS

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Abstract

The relationship between the subcellular distribution of guanylate cyclase and tissue guanosine-3′,5′-cyclic monophosphate (cGMP) levels was investigated in rat testes after surgically induced unilateral cryptorchidism. Placement of one of a testis pair in the abdominal cavity results in loss of testicular weight and function in the abdominal testis whereas the remaining scrotal testis appears to be functionally normal. Within 5 days after surgery, tissue cGMP levels were increased by twofold in the abdominal testis. A fourfold elevation was noted from 10 to 30 days after surgery. Whereas the homogenate guanylate cyclase activity was only slightly elevated 10 and 20 days postoperatively, a 200% increase in the soluble guanylate cyclase activity was seen at 5 days. Between 10 and 30 days, the rise in activity was >250% (P < 0.01). An increase in soluble guanylate cyclase activity was noted when the data were expressed as per milligram protein, per milligram DNA or per whole testis. Conversely, particulate guanylate cyclase activity was reduced by 40% in the cryptorchid testis. Kinetic analysis of the soluble enzyme prepared from abdominal and scrotal testes yielded linear Line-weaver-Burke plots for both enzyme preparations with an identical Km for guanosine triphosphate, but a three-fold higher maximal velocity for the abdominal enzyme. When the soluble guanylate cyclases from both testes were mixed and assayed together, the activities were additive rather than exhibiting synergism or inhibition. These experiments indicate that the altered Vmax is not due to a transferable activator or inhibitor.

Authors

W. Austin Spruill, Alton L. Steiner, H. Shelton Earp

l-Triiodothyronine and l-Reverse-Triiodothyronine Generation in the Human Polymorphonuclear Leukocyte

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Abstract

Extrathyroidal monodeiodination of l-thyroxine (T4) is the principal source of l-triiodothyronine (T3) and l-reverse-triiodothyronine (rT3) production. To define some of the cellular factors involved, we examined T3 and rT3 generation from added nonradioactive T4 in human polymorphonuclear leukocytes, using radioimmunoassays to quantify the T3 and rT3 generated. Under optimum incubation conditions which included a pH of 6.5 in sucrose-acetate buffer, the presence of dithiothreitol as a sulfhydryl-group protector, and incubation in an hypoxic atmosphere, significant net generation of T3 and rT3 was observed. Of the several subcellular fractions studied, the particulate fraction obtained by centrifugation at 27,000 g was found to possess the highest T3- and rT3-generating activities per unit quantity of protein. With respect to T3 generation from substrate T4, the Km was 5 μM and the Vmax was 7.2 pmol/min per mg protein. Propylthiouracil, methimazole, and prior induction of phagocytosis inhibited both T3 and rT3 generation, but T3 generation was inhibited to a greater extent. rT3, in a concentration equimolar to that of substrate T4, did not alter T3 generation, but inhibited T3 generation when the molar ratio of rT3 to T4 approached 10:1. Under the incubation conditions employed, particulate fractions of leukocytes obtained from five cord blood samples displayed an essentially normal relationship between T3- and rT3-generating activities, despite the distinctly divergent serum T3 and rT3 concentrations in these samples. From our findings, we draw the following conclusions: (a) the human polymorphonuclear leukocyte possesses the ability to generate T3 and rT3 from substrate T4; (b) the T3- and rT3-generating activities are associated principally with the 27,000 g particulate fraction and display enzymic characteristics with a sulfhydryl-group requirement; (c) T3-generating activity appears to be more susceptible to inhibitory influences than rT3-generating activity; and (d) in cord blood leukocytes, the putative enzymes catalyzing T3 and rT3 generation appear to be functionally intact under the experimental conditions employed.

Authors

Kenneth A. Woeber, Betty A. Maddux

The Effect of Acetazolamide on Cerebral Blood Flow and Oxygen Utilization in the Rhesus Monkey

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Abstract

The brain is critically dependent for its moment to moment function and survival on an adequate supply of oxygen. The enzyme carbonic anhydrase (EC 4.2.1.1) may play an important role in oxygen delivery to brain tissue by facilitating the hydration of metabolically produced carbon dioxide in erythrocytes in brain capillaries, thus permitting the Bohr effect to occur. We examined the effect of 30 mg/kg i.v. acetazolamide, a potent inhibitor of carbonic anhydrase, upon cerebral blood flow and oxygen consumption in lightly anesthetized, passively ventilated rhesus monkeys. Cerebral blood flow and oxygen consumption were measured with oxygen-15-labeled water and oxygen-15-labeled oxyhemoglobin, respectively, injected into the internal carotid artery and monitored externally. Acetazolamide produced an immediate and significant increase in cerebral blood flow (from a mean of 64.7 to 83.8 ml/100 g per min), an increase in arterial carbon dioxide tension (from a mean of 40.7 to 47.5 torr), and a decrease in cerebral oxygen consumption (from a mean of 4.16 to 2.82 ml/100 g per min). Because the change in cerebral oxygen consumption occurred within minutes of the administration of acetazolamide, we believe that this effect probably was not due to a direct action on brain cells but was achieved by an interference with oxygen unloading in brain capillaries. A resultant tissue hypoxia might well explain part of the observed increase in cerebral blood flow.

Authors

B. E. Laux, M. E. Raichle

Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity.

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Abstract

To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude.

Authors

R P Hebbel, J W Eaton, R S Kronenberg, E D Zanjani, L G Moore, E M Berger

Decreased Pulmonary Transvascular Fluid Filtration in Awake Newborn Lambs after Intravenous Furosemide

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Abstract

We studied the effect of furosemide on pulmonary transvascular filtration of fluid and microvascular permeability to plasma proteins by measuring steady-state lung lymph flow and protein flow, pulmonary arterial and left atrial pressures in nine 1-wk-old unanesthetized lambs before and after rapid intravenous infusion of furosemide, 1 mg/kg in 10 experiments and 8 mg/kg in 5 experiments. With rapid diuresis induced by furosemide (an eightfold increase in urine flow), lung vascular pressures decreased, protein concentrations of lymph and plasma increased, and there was a consistent decrease in lymph flow and lymph protein flow, more pronounced after the larger dose. Five additional lambs received 8 mg/kg of furosemide intravenously in the presence of saline-induced pulmonary edema; in these experiments, the decrease in vascular pressures, increase in transvascular protein gradient, and decrease in lymph flow were greater than in lambs without pulmonary edema. These findings suggest that furosemide decreases transvascular filtration of fluid in the lung by diminishing the transvascular hydraulic pressure gradient and increasing the transvascular gradient for protein osmotic pressure. In five acute experiments on anesthetized lambs with kidneys removed, 8 mg/kg of intravenous furosemide decreased lymph flow one-half as much as it did in the presence of kidneys, with no change in lung vascular pressures or protein concentrations. The results of experiments in lambs without kidneys are consistent with a reduction in the vascular surface area for exchange of fluid and protein in the lung.

Authors

Richard D. Bland, Douglas D. McMillan, Michael A. Bressack

Inactive form of erythrocyte carbonic anhydrase B in patients with primary renal tubular acidosis.

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Abstract

Evidence was found for an inactive form of carbonic anhydrase type B in the erythrocytes of two children with primary renal tubular acidosis. The addition of zinc chloride to hemolysates from these patients resulted in a marked increase in the activity of this enzyme. No such effect was noted with hemolysates of control subjects. No significant differences were observed in the zinc levels of hemolysates of these patients and of normal individuals. However, the level of zinc in the carbonic anhydrase B isolated from one of these patients was low, suggesting a modified form of the enzyme. The restoration of activity upon the addition of zinc was reversed by ethylenediamine tetraacetate, but no such effects were noted for the carbonic anhydrase B of normal individuals. Thus the abnormal carbonic anhydrase B has decreased zinc binding. The ultraviolet difference spectrum of the carbonic anhydrase B of normal individuals and that of a patient showed a peak at 305 nm which decreased upon the addition of zinc. The abnormal form of carbonic anhydrase B was not distinguishable from that of normal individuals by either immunological or electrophoretic criteria.

Authors

T Kondo, N Taniguchi, K Taniguchi, I Matsuda, M Murao

Direct evidence of participation of rat lung carbonic anhydrase in CO2 reactions.

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Abstract

Isolated rat lungs were ventilated with air and perfused with a blood-free Krebs-Ringer bicarbonate solution under conditions of net CO2 elimination in the lung. Some of the effluent perfusate was drawn through a stop-flow pH electrode apparatus, arriving at the electrode within 4 s after passing through the pulmonary capillaries. pH and temperature of the fluid in the electrode chamber were continuously monitored both before and after withdrawal was suddenly stopped. Little or no change was observed in the pH of the perfusate after flow was stopped, despite the fact that CO2 was eliminated in the lung, suggesting that the conversion of H2CO3 to CO2 in the blood-free perfusion fluid was markedly accelerated and the rise in pH was complete by the time the perfusate reached the electrode. Because the effluent perfusate was shown to be free of carbonic anhydrase activity, the catalysis must have occurred during transit through the isolated lung. When acetazolamide was added to the perfusate, a rise in the pH of the perfusate after stopping flow was consistently seen. These results suggest that the carbonic anhydrase of isolated lungs accelerates the conversion of H2CO3 to CO2 and enhances COW elimination as perfusate passes through the pulmonary capillaries, and that the enzyme may be present on the capillary endothelial surface.

Authors

E D Crandall, J E O'Brasky

Skeletal Muscle Protein and Amino Acid Metabolism in Experimental Chronic Uremia in the Rat: ACCELERATED ALANINE AND GLUTAMINE FORMATION AND RELEASE

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Abstract

The kinetics and factors regulating alanine and glutamine formation and release were investigated in skeletal muscle preparations from control and experimentally uremic rats. These preparations maintained phosphocreatine and ATP levels in vitro which closely approximated levels found in vivo. Alanine and glutamine release from uremic muscle were increased 45.8 and 36.0%, respectively, but tissue levels were unaltered. The increased release of alanine by uremic muscle was not accounted for by decreased rates of medium alanine reutilization via oxidation to CO2 or incorporation into muscle protein. The maximal capacity of added amino acids such as aspartate, cysteine, leucine, and valine to stimulate net alanine and glutamine formation was the same in uremic and control muscle. Epitrochlearis preparations were partially labeled in vivo with [guanido-14C]-arginine. On incubation, preparations from uremic animals showed a 54.6% increase in the rate of loss of 14C-label in acid precipitable protein. Correspondingly, these same uremic preparations showed a 62.7% increase in 14C-label appearance in the acid-soluble fraction of muscle and in the incubation media. Insulin decreased alanine and glutamine release to an extent threefold greater in uremic than in control preparations, and increased muscle glucose uptake approximately threefold in all preparations. Although basal rates of [4,5-3H]leucine incorporation into protein were decreased 25% in uremic muscles as compared with control muscles, insulin stimulated [3H]leucine incorporation nearly equally in both preparations.

Authors

Alan J. Garber

The Regulation of Skeletal Muscle Alanine and Glutamine Formation and Release in Experimental Chronic Uremia in the Rat: SUBSENSITIVITY OF ADENYLATE CYCLASE AND AMINO ACID RELEASE TO EPINEPHRINE AND SEROTONIN

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Abstract

The mechanism of the increased alanine and glutamine formation and release from skeletal muscle in experimental uremia was investigated using epitrochlearis preparations from control and chronically uremic rats. In uremic muscle, insensitivity to epinephrine or serotonin suppression of alanine and glutamine release was observed. With control muscles, 1 nm or greater, epinephrine inhibited alanine and glutamine release, whereas with uremic muscles, epinephrine concentrations <1 μM did not alter amino acid release. Decreased alanine and glutamine release with 1 nM serotonin was observed in control muscles, but no inhibition was observed with concentrations <1 μM in uremic muscle. Muscle amino acid levels were the same in control and uremic muscles in the presence or absence of epinephrine or serotonin. The reutilization of released alanine by protein synthesis or oxidation to CO2 was not differentially affected by epinephrine in uremic muscles as compared with control muscle. Dibutyryl-cAMP inhibited amino acid release equally in uremic and control muscles. Epinephrine or serotonin increased cAMP levels two- to four-fold or more in control than in uremic muscle. Basal- and fluoride-stimulated adenylate cyclase activities were equal in uremic and control muscle homogenates and in membrane fractions, but 10 μM epinephrine-stimulated adenylate cyclase was reduced 30-60% with uremia. At any concentration of epinephrine (0.001—100 μM), the stimulation of membrane adenylate cyclase activity was one- to twofold greater with control membranes than with uremic muscle membranes. With either control or uremic muscle, peak adenylate cyclase activity was observed at 1 μM epinephrine.

Authors

Alan J. Garber

Sympathetic Hyperactivity during Hypothalamic Stimulation in Spontaneously Hypertensive Rats

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Abstract

To determine whether sympathetic hyperactivity of hypothalamic origin contributes to keep blood pressures high in spontaneous hypertension, aortic pressures and sympathetic nerve spike potentials were recorded during electrical stimulation of the posterior hypothalamus in urethane-anesthetized normotensive or hypertensive rats. Basal sympathetic nerve activity was higher in spontaneously hypertensive rats than in either normotensive or deoxycorticosterone acetate-salt hypertensive ones even before stimulation began. Blood pressure elevations produced by hypothalamic stimulation were always preceded by substantial increases in amplitude and rate of neural firing. Changes in amplitude could not be quantified, but rates of neural firing accelerated much more in spontaneous hypertensives than in normotensives during stimulation with 50- and 100-μA currents. Similar differences between deoxycorticosterone acetate-salt hypertensives and either normotensives or spontaneous hypertensives were not statistically significant. Nerve activity invariably became quiescent immediately after hypothalamic stimulation was discontinued, and recovery from this poststimulatory inhibition was faster in spontaneously hypertensive than in normotensive rats. Although spontaneous hypertensives generally also had stronger pressor responses to various sympathomimetic stimuli, responses to hypothalamic stimulation were enhanced to a greater extent than those to either norepinephrine or sympathetic nerve stimulation. Because this selectivity indicates participation of mechanisms other than augmented cardiovascular reactivity, further enhancement of responsiveness to hypothalamic stimuli was attributed to the associated increase in sympathetic nerve firing. These results are in accord with the hypothesis that the blood pressure elevation in rats with established spontaneous hypertension is a result, at least in part, of sympathetic hyperactivity emanating from the posterior hypothalamus.

Authors

Kazuo Takeda, Ruben D. Buñag

Increased Production and Expression of Tissue Thromboplastin-Like Procoagulant Activity In Vitro by Allogeneically Stimulated Human Leukocytes

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Abstract

Intravascular coagulation, thrombosis, and fibrin deposition often produce tissue damage in allogeneic inflammatory reactions such as allograft rejection. The mechanisms which initiate blood clotting in these reactions are poorly understood. We find that allogeneic stimulation of human leukocytes in vitro increases production and expression of tissue thromboplastin-like activity. In our experiments mixed leukocyte cultures (MLC) of cells from allogeneic (unrelated) donors produced and expressed more procoagulant activity than control cultures of cells from each donor alone. After 7 days, allogeneic MLC had 5- to 50-fold more total procoagulant activity than controls, as shown by assaying lysed whole cultures. Additionally, allogeneic MLC had 8- to 240-fold more procoagulant activity expressed on leukocyte surfaces and in culture supernates than controls after 7 days, as shown by assaying intact whole cultures and cell-free supernates. These increases were largely accounted for by gains in the amounts of procoagulant activity produced and expressed per cell in MLC as compared to controls. Controls and MLC produced and expressed considerable amounts of procoagulant activity during the 1st day of culture, and there were no differential effects of allogeneic stimulation on day 1. However, after day 1, the total amount of procoagulant activity produced and the amount expressed declined steadily in controls, nearly reaching preculture levels by day 7. In contrast, the total amount of procoagulant activity in allogeneic MLC remained high, and the amount of activity expressed on cell surfaces and in supernates increased severalfold by day 7. MLC of syngeneic (identical twin) cells produced and expressed the same amount of activity as controls over a 7-day period, whereas MLC of cells from each twin and an allogeneic donor produced and expressed more activity than controls (at least 9- and 35-fold more, respectively). Thus, increases of procoagulant activity production and expression were found only in MLC of genetically dissimilar cells. Therefore, these increases must have resulted from allogeneic stimulation.

Authors

Henry Rothberger, Theodore S. Zimmerman, John H. Vaughan

Renin response to stimulation of cardiopulmonary mechanoreceptors in man.

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Abstract

Plasma renin activity (renin) and hemodynamic response to venous pooling of blood in legs were studied in 24 healthy volunteers and four patients who after bilateral nephrectomy received a functioning renal transplant. Blood pressure cuffs were placed around subjects' thighs and inflated at a pressure 5 mm Hg below the individuals' diastolic pressures. 30 min after thigh cuff inflation, renin significantly increased in all volunteers (mean = 125%). Inflation of cuffs induced a decrease of right atrial pressure, cardiopulmonary blood volume, and cardiac output, but there were no changes in the extra-arterial systolic and diatoloic pressure or in the pressure amplitude. After cuffs were deflated, renin and hemodynamic parameters returned toward normal. In nine volunteers in whom thigh cuff inflation initially elicited renin increases, subsequent intravenous propranolol (0.25 mg/kg) abolished the response to repeated cuff inflation. The renin increase to thigh cuff inflation was absent or suppressed in four patients with a recently transplanted denervated kidney. It is concluded that thigh cuff inflation elicited a reflex-mediated renin increase, and that the reflex stemmed from stimulation of cardiopulmonary mechanoreceptors.

Authors

W Kiowski, S Julius

Effect of glucagon on glucose production during insulin deficiency in the dog.

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Abstract

The aim of the present experiments was to determine the effects of basal glucagon on glucose production after induction of prolonged insulin lack in normal conscious dogs fasted overnight. A selective deficiency of insulin or a combined deficiency of both pancreatic hormones was created by infusing somatostatin alone or in combination with an intraportal replacement infusion of glucagon. Glucose production (GP) was measured by a primed constant infusion of [3H-3]glucose, and gluconeogenesis (GNG) was assessed by determining the conversion rate of circulating [14C]alanine and [14C]lactate into [14C]glucose. When insulin deficiency was induced in the presence of basal glucagon the latter hormone caused GP to double and then to decline so that after 4 h it had returned to the conrol rate. The conversion of alanine and lactate into glucose, on the other hand, increased throughout the period of insulin lack. Withdrawal of glucagon after GP had normalized resulted in a 40% fall in GP, a 37% decrease in GNG, and a marked decrease in the plasma glucose concentration. Induction of insulin deficiency in the absence of basal glucagon resulted in an initial (30%) drop in GP followed by a restoration of normal GP after 2--3 h and moderately enhanced glucose formation from alanine and lactate. It can be concluded that (a) the effect of relative hyperglucagonemia on GP is short-lived; (b) the waning of the effect of glucagon is attributable solely to a diminution of glycogenolysis because GNG remains stimulated; (c) basal glucagon markedly enhances the GNG stimulation apparent after induction of insulin deficiency; and (d) basal glucagon worsens the hyperglycemia pursuant on the induction of insulin deficiency both by triggering an initial overproduction of glucose and by maintaining the basal production rate thereafter.

Authors

A D Cherrington, W W Lacy, J L Chiasson

Cell-Mediated Immunity during Natural Measles Infection

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Abstract

Natural measles causes prolonged depression of cell-mediated immunity yet little is known as to how the infection influences lymphocyte function. Therefore, we studied the properties and function of lymphocytes during and after measles. The number and proportion of circulating thymus-derived lymphocytes was low during the acute stage of measles, and at this time 37% of these cells showed positive immunofluorescent staining for measles virus after stimulation with phytohemagglutinin. 7% of B cells were shown to contain virus but their numbers did not alter during the infection. Acute-phase lymphocytes, when stimulated, yielded infective virus and half were killed on incubation with autologous serum and complement. In acute measles the increase in [3H]-thymidine uptake of lymphocytes when stimulated with an optimal dose of PHA was normal in media with 10% fetal calf serum and low in media containing 10% autologous serum: the mean values were 56.8±34.1 and 23.7±25.9 cpm × 103 per 106 lymphocytes, respectively. Stimulation of acute-phase lymphocytes by Candida antigen was also low in media containing autologous serum averaging 1.2 × 103 cpm per 106 lymphocytes. On recovery 4-6 wk later this rose significantly to 18.9±19.8. The mean migration index of leukocytes to heat-killed candida cells in acute measles was 0.84±SD 0.08, and this fell significantly to 0.75±SD 0.08 4 wk later. Thus, depletion of T cells, an inhibitor of lymphocyte proliferation in the serum and a possible defect in antigen processing, interacts to depress cell-mediated immunity in measles.

Authors

H. C. Whittle, J. Dossetor, A. Oduloju, A. D. M. Bryceson, B. M. Greenwood

Hereditary Male Pseudohermaphroditism Associated with an Unstable Form of 5α-Reductase

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Abstract

The properties of 5α-reductase have been compared in genital skin fibroblasts cultured from five patients from three families (Los Angeles, Dallas, and Dominican Republic) in which hereditary male pseudohermaphroditism has been established to result from deficient conversion of testosterone to dihydrotestosterone.

Authors

Mark Leshin, James E. Griffin, Jean D. Wilson

Adenosine Triphosphatases of Rat Pancreatic Islets: COMPARISON WITH THOSE OF RAT KIDNEY

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Abstract

Electrolyte fluxes are fundamental to normal endocrine pancreatic function. Adenosine triphosphatases (ATPases) are enzyme systems believed to modulate electrolyte movements across membranes in a number of cell types. This study was undertaken to measure cation-dependent ATPases of rat pancreatic islets. In addition, we compared effects of substances which influence endocrine pancreatic function upon ATPases in homogenates of islets and kidney, the latter being a tissue which would not be expected to have a stimulus-secretion response to substances which activate islets.

Authors

Seymour R. Levin, Barry G. Kasson, June F. Driessen

Disulfide Bonds and the Quaternary Structure of Factor VIII/von Willebrand Factor

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Abstract

Human Factor VIII/von Willebrand factor, purified by calcium citrate-cellulose chromatography and 4% agarose gel filtration was subjected to sodium dodecyl sulfate gel electrophoresis on gels containing 2% acrylamide and 0.5% agarose. We find a series of multimers of which the apparent molecular weight of the higher members was ≅5 million. The higher multimers were isolated by 2% agarose gel filtration. Treatment of the high molecular weight multimers with 2-mercaptoethanol at concentrations of 0.005-0.5% in the presence of 1% dodecyl sulfate resulted in a shift to lower molecular weight multimers. Between mercaptoethanol concentrations of 0.01 and 0.5%, the predominant species was the dimer of the basic subunit. Mercaptoethanol concentrations >0.5% were required to reduce the interchain disulfide bonds of the dimer. An artificial multimeric series was prepared by cross-linking von Willebrand factor subunits with dimethylsuberimidate. Comparison of the multimers produced by reduction with the multimers produced by cross-linking, demonstrated the absence of odd-numbered multimers from the reduced series. Thus, the protomeric unit appears to be the dimer. High molecular weight multimers had both ristocetin cofactor activity and Factor VIII procoagulant activity. Reduction of the protein in the absence of denaturing agents, caused a gradual shift to lower molecular weight species and a concomitant loss of von Willebrand factor activity. In contrast, Factor VIII activity was unchanged by reduction. These studies suggest that the moieties having von Willebrand factor activity and those having Factor VIII activities are covalently linked by disulfide bonds.

Authors

Richard B. Counts, Stefan L. Paskell, Susan K. Elgee

Correlation of adenosine deaminase activity with cell surface markers in acute lymphoblastic leukemia.

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Abstract

Adenosine deaminase (ADA) activity has been measured in the lymphoblasts of 23 untreated patients with acute lymphoblastic leukemia and related to the presence or absence of immunologic cell surface markers. The mean ADA activity in the acute lymphoblastic leukemia population as a whole was increased fourfold over that in normal lymphocytes. 9 of the 23 patients were classified as thymus-derived (T-) cell acute lymphoblastic leukemia on the basis of erythrocyte rosette positivity; the remaining 14 patients had null-cell leukemia. The mean ADA activity (ADA U/mg protein) of T-cell lymphoblasts (102 U) was 3 times higher than the mean of null lymphoblasts (30 U). This difference is statistically significant (P less than 0.02). Measurement of ADA activity offers a biochemical method of distinguishing between immunological subtypes of lymphoblasts which may be of prognostic and therapeutic value.

Authors

J F Smyth, D G Poplack, B J Holiman, B G Leventhal, G Yarbro

A serum inhibitor of immune regulation in patients with systemic lupus erythematosus.

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Abstract

Normal mononuclear leukocytes were incubated with serum from patients with active systemic lupus erythematosus (SLE) and healthy subjects and then studied on lymphoproliferative tests. Serum from SLE patients that contained an autoantibody to a subpopulation of thymus-derived (T) lymphocytes inhibited suppressor T-cell activity induced with concanavalin A. These sera did not inhibit lymphoproliferative responses or suppression by monocytoid cells. Mitogen-activated suppressor cells were not inhibited with serum from SLE patients or healthy subjects lacking T-cell autoantibody. This abnormality may contribute to the altered immune response that occurs with SLE.

Authors

J J Twomey, A H Laughter, A D Steinberg

Absence of the platelet receptor for drug-dependent antibodies in the Bernard-Soulier syndrome.

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Abstract

The platelet membrane receptor for quinidine- and quinine-dependent antibodies was studied in three patients with the Bernard-Soulier syndrome (BSS) and in normal subjects with immunologic techniques based on the release of 51Cr from labeled platelets. The receptor could not be detected on BSS platelets but was present on platelets from each of 180 normal subjects. BSS platelets reacted normally with other allo- and autoantibodies. In confirmation of previous reports, BSS platelets were found to be deficient in glycoproteins Ib and Is. However, after apparently total cleavage of these proteins from the membrane of normal platelets by controlled hydrolysis with trypsin or chymotrypsin, 80% of the drug-dependent antibody receptor activity was retained. These observations suggest the existence of an additional, hitherto unrecognized membrane defect in Bernard-Soulier platelets.

Authors

T J Kunicki, M M Johnson, R H Aster