Immunological Studies of the Human Placenta CHARACTERIZATION OF IMMUNOGLOBULINS ON TROPHOBLASTIC BASEMENT MEMBRANES

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Abstract

Immunohistological and elution studies of the human placenta revealed the presence of IgG on the trophoblastic basement membrane (TBM) which demonstrated specificity for placental but not lung, thyroid, or kidney basement membranes, suggesting the presence of a placenta-specific antigen in TBM. IgG comprised the bulk of immunoglobulin in eluates, and small amounts of IgA, trace amounts of IgM, but no IgE or IgD were identified in eluates. The distribution of IgG subclasses in eluate was not unusual as compared to maternal and neonatal sera, and Gm and Inv typing of eluates indicated that it was of maternal origin. Small amounts of eluate-IgG effectively inhibited the blastogenic response of unrelated lymphocytes to old tuberculin, phytohemagglutinin, and in one- or two-way mixed lymphocyte culture reactions. The inhibition was distinct from nonspecific inhibitors, and dose-response analysis indicated that eluate was very much more potent as an inhibitor than were the nonspecific inhibitors. Inhibition was shown to not be due to anti-HL-A activity, and was probably not due to aggregated IgG or immune complexes. Binding of eluate to lymphocytes was very loose as shown by washing experiments, and no binding could be shown by immunofluorescence. The capacity of eluate IgG to inhibit MLC was retained after pepsin digestion to F(ab′)2, suggesting that the inhibition reactions were immunological. It is suggested that eluate-IgG is maternal blocking antibody to a hitherto uncharacterized trophoblast antigen, and it is speculated that either abnormal antigen or aberrant responses to antigen could result in fetal wastage.

Authors

W. Page Faulk, M. Jeannet, W. D. Creighton, A. Carbonara

The Interactions of Proinsulin with Insulin Receptors on the Plasma Membrane of the Liver

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Abstract

The interactions of proinsulin with the insulin-specific receptors were investigated in purified rat liver plasma membranes. These studies were designed to characterize the binding of proinsulin to the insulin receptors, to search for proinsulin-specific receptor sites, and to examine the possibility of proinsulin conversion at the insulin receptor site. Proinsulin was only 3-5% as potent as insulin in binding to insulin receptors. Proinsulin reacted with all of the insulin-specific receptors, and direct binding studies of [125I]porcine proinsulin and [125I]rat proinsulin did not reveal proinsulin-specific receptor sites other than the insulin receptors in rat liver membranes.

Authors

Pierre Freychet

The Role of Platelet Membrane Phospholipids in the Platelet Release Reaction

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Abstract

The structure and function of the platelet surface was probed by phospholipase C (Clostridium perfringens) which hydrolyzes membrane phospholipids, particularly phosphatidylcholine. Platelet phospholipids were susceptible to phospholipase C, and extent of hydrolysis was dependent on concentration of phospholipase C and Ca++. Phospholipase C (0.15 U/ml) with Ca++ (0.55 mM) hydrolyzed 15.6% phospholipids during 5 min. Phospholipase C released platelet serotonin (5HT), ADP, and platelet factor 4. Hydrolysis of 5% phospholipids resulted in release of 70% 5HT. Platelet 5HT release was rapid, occurring within 2 min. Phospholipase C (0.2 U/ml) with Ca++ (0.55 mM) also released 10.35 nmol sotrage pool ADP/109 platelets and 63% platelet factor 4 during 3 min. Phospholipase C did not cause leakage of cytoplasmic metabolic pool ADP, since only 6.6% [3H]ADP was released. Ultrastructural analysis of phospholipase C-modified platelets showed that platelets were intact. After 2% phospholipid hydrolysis, centralization of granules and contraction of microtubules were evident. After 18% phospholipid hydrolysis, there were morphological indications of degranulation. Phospholipase C-induced phospholipid hydrolysis caused the release of ADP and 5HT since: (a) Phospholipase C purified by heating was shown to be free of protease and neuraminidase activity and capable of inducing the platelet release reaction. (b) Antitoxin (Cl. perfringens) neutralized phospholipase C-induced 5HT release which rules out a contaminant. (c) Phosphorylcholine, the hydrolysis product, did not induce platelet 5HT release. This study demonstrates that minimal hydrolysis of platelet phospholipids triggers the release reaction. Our hypothesis is that phospholipids, presumably phosphatidylcholine, are situated at or near active site or “receptor” on the platelet surface and function as the modulator for the release reaction.

Authors

Paul K. Schick, Byung P. Yu

A Microperfusion Study of Phsophate Reabsorption by the Rat Proximal Renal Tubule EFFECT OF PARATHYROID HORMONE

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Abstract

To study the mechanism of phsophate reabsorption by the proximal tubule and the effect of parathyroid hormone (PTH), microperfusion experiments were carried out in rats. Segments of proximal tubule isolated by oil blocks were perfused in vivo with one of three solutions, each containing 152 meq/liter Na+ and 2 mmol/liter phosphate, but otherwise differing in composition. The pH of solution 1 was 6.05-6.63, indicating that 60-85% of the phosphate was in the form of H2PO4-. The pH of solution 2 was 7.56-7.85, and 85-92% of the phosphate was in the form of HPO4=. Solution 3 contained HCO3- and glucose and had a pH of 7.50-7.65. When the proximal tubules were perfused with solution 1, the 32P concentration in the collected perfusate was found to be consistently lower than in the initial perfusion solution. In sharp contrast, when the tubules were perfused with solutions 2 or 3, 32P concentration usually rose above that in the initial solution. Water (and persumably Na+) reabsorption, as measured with [3H]inulin, was the same with the acid and alkaline solutions. Administration of partially purified PTH clearly prevented the fall in phosphate concentration with the acid solution, but had a less discernible effect on phosphate reabsorption with the two alkaline solutions. Measurements of pH within the perfused segments with antimony microelectrodes demonstrated that PTH enhanced alkalinization of the acid perfusion solution. The findings are consistent with the view that H2PO4- is reabsorbed preferentially over HPO4=. This can be attributed to either an active transport mechanism for H2PO4- or selective membrane permeability to this anion. PTH appears to either inhibit an active transport process for H2PO4-, or to interfere with passive diffusion of phosphate by alkalinizing the tubular lumen.

Authors

Norman Bank, Hagop S. Aynedjian, Stephen W. Weinstein

Pathogenic Role of Cyclic AMP in the Impairment of Urinary Concentrating Ability in Acute Hypercalcemia

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Abstract

A possible association between the impairment of urinary concentrating ability and an impairment of the vasopressin-dependent cyclic AMP system in hypercalcemia was investigated in rat kidneys both in vivo and in vitro. The increases of urinary osmolality and negative free water clearance and the increase of urinary cyclic AMP excretion by vasopressin injection were significantly less in the hypercalcemic rats than in the control rats. The increase of cyclic AMP concentration by vasopressin in renal medullary tissue was significantly less in the slices obtained from the hypercalcem'c rats than in those obtained from the control rats. The activation of adenylate cyclase by vasopressin was significantly less in the group with an increased concentration of calcium in media than the control group, but phosphodiesterase activity was not affected by calcium concentration in the media. These data suggest that the impaired urinary concentrating ability in hypercalcemic kidneys is due at least in part to the direct inhibitory effect of calcium on the vasopressin-dependent cyclic AMP system at the level of adenylate cyclase in renal medulla.

Authors

Nama Beck, Harbans Singh, Sarah W. Reed, H. V. Murdaugh, Bernard B. Davis

Sulfate Metabolism in Human Chondrocyte Cultures

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The depletion of articular cartilage in the afflicted joints is a primary clinical feature of osteoarthritis. This disorder has been linked to a disturbance in the metabolism of the extracellular matrix components of this tissue. The mechanisms involved in the regulation of sulfated proteoglycan metabolism in articular cartilage were therefore studied by measuring the biosynthesis and distribution of 35S-labeled glycosaminoglycans in chondrocyte cultures derived from normal and osteoarthritic tissue. Incorporation experiments were carried out at pH 7.0 with [35S]Na2SO4 in the presence of fetal calf serum, human serum from normal or arthritic individuals, or a combination of these.

Authors

Edith R. Schwartz, P. Roger Kirkpatrick, Roby C. Thompson

Studies on “Big” Growth Hormone from Human Plasma and Pituitary

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Abstract

Most of the immunoreactive growth hormone (IRGH) in human plasma elutes from Sephadex G-75 as “little” GH (LGH), mol wt 22,000, but 14-39% elutes earlier (“big” GH, BGH). In saline extracts of human pituitary, 11-17% of IRGH eluted as BGH. On gel filtration of pituitary and plasma BGH in 8 M urea, 59-81% ran as LGH, but when the remaining BGH was refiltered in urea, all ran as BGH. Thus there is a “urea-stable” and a “urea-labile” form of BGH. SImilarly, freezing and thawing converted over half of pituitary and plasma BGH to LGH, but when the “freeze-stable” BGH was again frozen, thawed, and refiltered, almost all ran as BGH. Urea-stable BGH was not dissociated by freezing, and most of the freeze-stable BGH was stable in urea, so the two forms are very similar or identical. Since 8 M urea and freezing dissociate peptides linked by noncovalent bonds, probably the BGH that is dissociated by urea and freezing consists of LGH bound noncovalently to another moiety, while in stable BGH the LGH is bound to another molecule by covalent or unusually strong noncovalent linkage. On centrifugation, the sedimentation of urea-stable BGH was consistent with a mol wt about twice that of LGH. Trypsinization of urea-stable BGH converted 36-59% to LGH, suggesting that some BGH may be a “prohormone” of LGH. On retrypsinization of the BGH that was not converted to LGH, only 13-24% converted, suggesting that there may be two forms of urea-stable BGH which vary in their response to trypsin.

Authors

Donald R. Wright, A. David Goodman, Kathleen D. Trimble

Effect of Age and Magnesium Depletion on Bone Magnesium Pools in Rats

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In vivo and in vitro studies were carried out to characterize the exchangeable bone magnesium pool and determine what effect age and magnesium depletion has on bone magnesium. A highly significant correlation was found between the size of the in vitro elutable and in vivo exchangeable bone magnesium (r=0.97). To show that the exchangeable bone magnesium was the surface-limited bone magnesium, elution studies were performed 4 h after the in vivo administration of radiomagnesium. Specific activity in the eluant was 85% of that found in the serum at time of death, suggesting that the elutable and exchangeable bone magnesium pools were largely the same pool.

Authors

Allen C. Alfrey, Nancy L. Miller, Richard Trow

Analyses of Lymphocytes from Patients with Rheumatoid Arthritis and Systemic Lupus Erythematosus OCCURRENCE OF INTERFERING COLD-REACTIVE ANTILYMPHOCYTE ANTIBODIES

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Abstract

Large percentages of the lymphocytes from some patients with rheumatoid arthritis and systemic lupus erythematosus were densely covered with Ig demonstrable by immunofluorescence, which was occasionally present in the form of caps. The amount and character of the Ig staining depended largely on the procedures used in the isolation and washing of the lymphocytes. Cold-reactive antilymphocyte antibodies present in many sera wre primarily responsible for these variations. Overnight culture of the lymphocytes proved to be an efficient procedure for the removal of adsorbed antibody. Some evidence was also obtained for the presence of circulating immune complexes and exogenous rheumatoid factor molecules on the lymphocyte surface. Thus on freshly isolated cells the demonstration of surface Ig proved to an unreliable marker of bone marrow-derived (B) cells in these disease: the actual percent of B cells with intrinsic surface Ig was often markedly decreased. In patients with systemic lupus erythematosus, this reduction was in agreement with the low numbers of cells that had a receptor for aggregated IgG. The mean percentage of thymus-derived (T) cells in both diseases was slightly greater than the normal level.

Authors

R. J. Winchester, J. B. Winfield, F. Siegal, P. Wernet, Z. Bentwich, H. G. Kunkel

The Defect in Hemophilic and von Willebrand's Disease Plasmas Studied by a Recombination Technique

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Abstract

Factor VIII in preparations from normal plasma is a large glycoprotein of greater than 2 million molecular weight which elutes in the exclusion volume of 4% agarose gels at an ionic strength of 0.15. Recent studies have demonstrated that the factor VIII in canine and bovine plasma is a macromolecular complex composed of a large inert carrier protein and a noncovalently bound small fragment which contains the procoagulant active site. This complex is dissociable in 0.25 M CaCl2, and conditions for its recombination have been reported. The present study reports the dissociation characteristics of normal human factor VIII preparations in 0.25 M CaCl2 and the ability to achieve quantitative recombination of the dissociated fragments of normal human and bovine factor VIII after the removal of Ca2+. The recombination technique was used to characterize further the defect in hemophilia and von Willebrand's disease. Void volume preparations from human hemophilia A-, canine hemophilia A, and human von Willebrand's plasma, with no factor VIII procoagulant activity, were mixed with the small active fragment prepared from the normal plasma of their respective species. Chromatography of the three mixtures in agarose gel showed that the fractions from the human hemophilic plasmas contained a molecule that bound the small active normal fragment, but neither the fractions from canine hemophilia A plasmas nor the fractions from the human von Willebrand's plasmas demonstrated evidence of such material. These data suggest that there is present in human hemophilia A plasma a normal functional carrier molecule which is absent or nonfunctional in the plasma of hemophilic dogs and humans with von Willebrand's disease.

Authors

Herbert A. Cooper, Robert H. Wagner

Modulation of the Random Migration of Human Platelets

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Abstract

Random migration of human platelets has been recognized as a parameter of platelet function which can be assessed in a reproducible manner by modification of the Boyden micropore filter technique for evaluating this function in other cells (Boyden, S. 1962. J. Exp. Med. 115: 453-466). Because platelets are extremely susceptible to aggregation, the conditions for collecting and isolating platelets and the migration buffer (Ca++ and Mg++-free phosphate buffered saline, pH 6.8, with glucose and gelatin) were selected to minimize such a possibility. The random movement of platelets into the micropore filter was maximal at 30-37°C and was contingent upon the metabolic integrity of the cell; thus, it can be attributed to active spontaneous migration. While the initiating and enhancing effects of epinephrine on the platelet aggregation-release reaction are mediated by an α-adrenergic receptor, the inhibition of random migration involved a β-receptor. Equimolar propranolol but not phentolamine prevented epinephrine inhibition of random migration, and isoproterenol had activity comparable to epinephrine while phenylephrine was inactive. The capacity of the cholinomimetic agent, carbachol, to increase platelet migration is reminiscent of the recent findings in several cell systems in which β-adrenergic and cholinergic stimuli have opposite effects. The prostaglandins E1 and E2 augmented spontaneous migration in contrast to their well established inhibitory action on platelet aggregation at the concentrations employed. The suppression by indomethacin of prostaglandin enhancement and of spontaneous migration implies a requirement for the prostaglandin biosynthetic pathway during the migration process. Thus, the spontaneous migration of human platelets, an additional parameter of platelet function for in vitro investigations, disclosed not only a β-adrenergic receptor for epinephrine, but also a capacity for cholinergic augmentation and an apparent requirement for prostaglandin biosynthesis.

Authors

Frank H. Valone, K. Frank Austen, Edward J. Goetzl

Selective Measurement of Two Lipase Activities in Postheparin Plasma from Normal Subjects and Patients with Hyperlipoproteinemia

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An assay has been developed for specific measurement of two different lipase activities in postheparin plasma. Lipoprotein lipase, derived from extrahepatic sources, is measured as protamine-inactivated lipase activity; hepatic lipase activity is protamine-resistant under the conditions of this assay. In 100 normal subjects, both enzyme activities were noted to be related to age and sex. Protamine-resistant lipase, which comprised 46-95% of the total activity, was highest in men over 18. Protamine-inactivated lipase activity was greatest in younger males and was age-correlated in women, doubling between the second and sixth decades.

Authors

Ronald M. Krauss, Robert I. Levy, Donald S. Fredrickson

Cell-Mediated Immunity after Bacterial Infection of the Lower Respiratory Tract

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Abstract

Lower respiratory tract and systemic cell-mediated immunity have been studied in rabbits after infection with Listeria monocytogenes or Diplococcus pneumoniae. Respiratory tract cell-mediated immunity was evaluated by direct and indirect assays of migration inhibitory factor (MIF) production. Systemic delayed hypersensitivity was determined by means of intradermal testing with appropriate antigens.

Authors

J. Robert Cantey, W. Lee Hand, Carl G. Hughes, Mary E. Lund, Neva L. King

Effect of Mannitol on Glomerular Ultrafiltration in the Hydropenic Rat

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Abstract

The effect of mannitol upon glomerular ultrafiltration was examined in hydropenic Munich-Wistar rats. Superficial nephron filtration rate (sngfr) rose from 32.0±0.9 nl/min/g kidney wt to 42.0±1.6 (P < 0.001) in eight rats. Hydrostatic pressure gradients acting across the glomerular capillary (ΔP) were measured in glomerular capillaries and Bowman's space with a servo-nulling device, systemic (πA) and efferent arteriolar oncotic pressures (πE) were determined by microprotein analysis. These data were applied to a computer-based mathematical model of glomerular ultrafiltration to determine the profile of effective filtration pressure (EFP = ΔP — π) and total glomerular permeability (LpA) in both states. Filtration equilibrium obtained in hydropenia (LpA ≥ 0.099±0.006 nl/s/g kidney wt/mm Hg) and sngfr rose because EFP increased from a maximum value of 4.2±1.1 to 12.8±0.5 mm Hg after mannitol (P <0.01). This increase was due to both increased nephron plasma flow and decreased πA. Computer analysis of these data revealed that more than half (>58%) of this increase was due to decreased πA, consequent to dilution of protein. Since EFP was disequilibrated after mannitol, LpA could be calculated accurately (0.065 ± 0.003 nl/s/g kidney wt/mm Hg) and was significantly lower than the minimum estimate in hydropenia.

Authors

Roland C. Blantz

The Immunohistopathology of Glomerular Antigens THE GLOMERULAR BASEMENT MEMBRANE, COLLAGEN, AND ACTOMYOSIN ANTIGENS IN NORMAL AND DISEASED KIDNEYS

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The immunofluorescent localization of antisera to human glomerular basement membrane (GBM), collagen, and smooth muscle actomyosin was examined in 15 specimens of normal renal tissue and 98 specimens from patients with renal disease. The anti-GBM and anticollagen antisera normally localize to GBM, while antiactomyosin localizes to the mesangium. Diabetic nephropathy revealed a striking expansion of mesangial material reacting with antiactomyosin. In contrast, the expanded mesangium in membranoproliferative glomerulonephritis did not react with antiactomyosin, and the GBM localization of anti-GBM and anticollagen sera was similarly lost. The thickened GBM in diabetes mellitus and membranous nephropathy reacted with anti-GBM and anticollagen, but with accentuation of staining on the inner aspect of the GBM. In proliferative glomerulonephritis there was a moderate increase in the distribution of actomyosin. Glomerular sclerosis and hyalinization in all diseases studied was accompanied by a loss of immunofluorescent staining for all glomerular antigens, including collagen.

Authors

Jon I. Scheinman, Alfred J. Fish, Alfred F. Michael

Protein Binding by Specific Receptors on Human Placenta, Murine Placenta, and Suckling Murine Intestine in Relation to Protein Transport across These Tissues

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Abstract

Human, rat, and mouse placentas and rat and mouse intestines were homogenized in buffered saline, and fraction consisting primarily of cell membranes was separated from each of the homogenates by differential centrifugation. Human, bovine, and guinea pig IgG, and human IgE, Bence-Jones protein, serum albumin, insulin, and growth hormone were labeled with 131I or 125I, and the binding of these proteins by the cell membrane fractions was investigated. Rat and mouse sucklings were given labeled proteins intragastrically, and the amount of each protein absorbed after a given interval of time was determined. It was found that the degree and specificity of protein binding by the cell membrane fractions from human and murine placentas strikingly paralleled the relative rate and specificity of protein transport from mother to fetus in the respective species at or near term. Similarly, the degree and specificity of protein binding by the cell membrane fractions from suckling rat and mouse intestines tended to parallel the rate and specificity of protein absorption from the gastrointestinal tract in these animals. However, some discordance between protein binding and protein transport was also observed. The data suggest that: (a) the binding of a protein by specific receptors on cell membranes may be a necessary first step in the transcellular transport of the protein; (b) specific protein binding by cell receptors does not ensure the transport of that protein across the tissue barrier; and (c) specific transport mechanisms other than or in addition to specific cell membrane receptors are involved in the active transport of proteins across the human or murine placenta or the suckling murine intestine.

Authors

Jonathan D. Gitlin, David Gitlin

Mechanisms for Development of Diabetic Hypertriglyceridemia in Streptozotocin-Treated Rats EFFECT OF DIET AND DURATION OF INSULIN DEFICIENCY

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Abstract

A combined ultrastructural and functional approach was employed to define the effects of duration of diabetes and of diet on various aspects of lipid metabolism in rats with severe streptozotocin (SZ)-induced insulin deficiency. Plasma triglyceride (TG) levels rose to a mean of 479 mg/100 ml 24 h after SZ administration in rats eating a fat-free, high carbohydrate diet as compared to a mean of 324 mg/100 ml in rats eating a high fat diet. These changes were associated with a commensurate increase in hepatocyte Golgi very low density lipoprotein (VLDL) content, but only a small increase in estimates of VLDL-TG secretion rate (post-Triton WR 1339 increment in plasma TG level). Although these findings are consistent with the thesis that VLDL-TG synthesis and secretion are increased 24 h after administration of SZ, it seemed unlikely that the observed increase in VLDL-TG secretion could entirely account for the severity of the hypertriglyceridemia. Thus, although lipoprotein removal rate was not measured directly, it was necessary to postulate that a defect in VLDL-TG removal was also present at this stage.

Authors

Eve P. Reaven, Gerald M. Reaven

Rapid Transient Efflux of Phosphate Ions from Pancreatic Islets as an Early Action of Insulin Secretagogues

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Abstract

Anionic fluxes during the membrane realignments of stimulated insulin release have not been characterized previously although cations have been implicated in stimulus-secretion coupling. We have shown that a limited packet pulse of phosphate release (“phosphate flush”) begins at the same time that the first phase of insulin secretion may occur. To demonstrate this phenomenon, we have prelabeled islets, obtained from rat pancreas by collagenase digestions, by incubation with [32P]orthophosphate. When such prelabeled islets are perifused with Krebs-Ringer bicarbonate containing 0.5 mg/ml D-glucose, a basal rate of efflux of radioactivity is established; transfer to perifusates containing 3.0 mg/ml D-glucose elicits an increased 32P efflux within 1-2 min to peak values which are 7- to 21-fold greater than basal. The total duration of this “phosphate flush” approximates 10 min and exceeds the duration of the first phase of stimulated insulin secretion. With lesser concentrations of glucose, the flush exhibits dose-response relationships, and with 3 mg/ml glucose, a second flush can be elicited by restoring basal conditions and stimulating anew with 3 mg/ml glucose. The phenomenon is highly specific and can be reduplicated by other secretagogues (L-leucine) or sugars (D-mannose) which are also known to elicit insulin release but not by sugars which fail to affect insulin secretion (D-galactose, D-fructose, i-inositol, L-glucose). The efflux of radioactivity consists entirely of [32P]orthophosphate. Phosphate flush persists in phosphate-free media, Ca++-free media, and when insulin release is obtunded by adding Ni++ (2 mM) to the perifusates. Thus, efflux of [32P]orthophosphate can be dissociated from insulin extrusion, and from net influx of ionic phosphate or calcium. Membrane stabilization with D2O or 1.0 mM tetracaine reversibly inhibits phosphate flush. Although the mechanism by which this effect occurs has not yet been established, the phosphate flush appears to constitute one of the earliest and hitherto unknown indices of the excitatory state in pancreatic islets.

Authors

Norbert Freinkel, Catherine El Younsi, Jerry Bonnar, Rex M. C. Dawson

Normal Glomerular Permeability and Its Modification by Minimal Change Nephrotic Syndrome

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Abstract

It has been suggested that the glomerular basement membrane restricts the passage of large molecules only, the barrier to filtration of smaller molecules being at the level of the epithelial slit pore. This hypothesis was investigated by measuring glomerular permeability to 125I-labeled polydisperse polyvinyl pyrrolidone (PVP) in 16 children with idiopathic nephrotic syndrome (INS) and in 6 children of comparable age who had no evidence of renal disease. Studies were performed in the patients with INS before, during, and after treatment with steroids. PVP in blood and urine samples was separated according to molecular size by solumn chromatography, to permit the calculation of permeability to inert macromolecules of sizes ranging from 8,000 mol wt. In untreated INS, glomerular permeability to molecules > 40 Å was normal; permeability to smaller molecules was markedly reduced, frequently to 20% or less of normal. There was an average decrease in inulin clearance (Cin) of 24%. Glomerular permeability and Cin returned to normal in INS treated with steroids only when proteinuria disappeared. The results support the concept, derived from studies with ultrastructural tracers, that the final barrier to filtration may be at the level of the epithelial slit pore. Thus fusion of the epithelial foot processed with obliteration of the slit pores was associated with impaired passage of smaller molecules of PVP into the urine. Reversal of the pathologic abnormality resulted in return of permeability to normal. The decreased Cin seen in INS may not reflect true glomerular filtration rate, but may result from restricted passage of inulin molecules (mol wt 5,000) through the epithelial slit pore.

Authors

Alan M. Robson, Joseph Giangiacomo, Randy A. Kienstra, Saiyid T. Naqvi, Julie R. Ingelfinger

Relationship between Frequency Dependence of Lung Compliance and Distribution of Ventilation

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Abstract

The previously demonstrated empirical association between frequency dependence of lung compliance and distribution of ventilation, the latter determined by the N2 washout technique, was confirmed by establishing a mathematical link between the two tests. By assuming a two-compartment system with known compliances and making corrections for Pendelluft and common dead space mixing effects, the ratio of dynamic to static compliance (Cdyn/Cst) for any respiratory frequency can be calculated from the compartmental analysis of the N2 washout at a single respiratory frequency. By using these equations, a good correlation was found between calculated and measured Cdyn/Cst in dogs with artificially induced bronchial obstruction and in young smokers or young nonsmokers after carbachol inhalation. A two-compartment N2 washout was demonstrated in 10 young healthy smokers at one or two respiratory frequencies whereas all 10 normal controls showed a single exponential curve. These findings indicate that the non-invasive N2 washout test is capable of predicting Cdyn/Cst and at the same time gives a direct measure of gas distribution. Further, it appears to be a highly sensitive method for the detection of “small airway disease.”

Authors

Adam Wanner, Stephen Zarzecki, Neal Atkins, Angel Zapata, Marvin A. Sackner

The Effect of Adrenergic Blockade on the Glucagon Responses to Starvation and Hypoglycemia in Man

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In an attempt to ascertain whether the sympathetic nervous system modulates glucagon release in man during starvation and hypoglycemia, the influence of alpha and beta adrenergic blockade on glucagon responses was studied in young, healthy men subjected to fasting and insulin-induced hypoglycemia. Six volunteers fasted for 84 h on three separate occasions. Plasma immunoreactive glucagon (IRG), measured initially at 12 h, climbed gradually from mean levels of 54 pg/ml to a zenith of 124 pg/ml at 48 h, with maintenance of these levels for the duration of the fast. The infusion of propranolol or phentolamine throughout the terminal 24 h of the second and third fasts failed to alter the pattern of IRG release. After an overnight fast, five volunteers received insulin intravenously, which evoked a mean rise in plasma IRG levels from 63 pg/ml to a maximum of 256 pg/ml at 30 min. The concurrent administration of propranolol or phentolamine did not modify the glucagon responses to insulin-induced hypoglycemia. These data suggest that the augmented glucagon release in man during starvation or after hypoglycemia is not significantly regulated by signals from the adrenergic nervous system.

Authors

Robert M. Walter, R. James Dudl, Jerry P. Palmer, John W. Ensinck

Kinetics of Salicylate Elimination by Anephric Patients

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Abstract

The objectives of this research were to determine the kinetics of salicylate elimination in anephric patients and particularly to establish if these patients form the major metabolite of salicylic acid, salicyluric acid, at a normal rate. This investigation was initiated because of conflicting reports concerning the contribution of the kidneys to the formation of salicyluric acid in man. Six patients, 20-44 yr old, three of whom were anatomically anephric while the other three were physiologically anephric, received an intravenous injection of 500 mg salicylic acid (as sodium salicylate)/1.73 m2 body surface area on an interdialysis day. Serial blood samples were obtained for 12 or 16 h after injection and the plasma was assayed for salicylic acid, salicyluric acid, total protein, albumin, and creatinine. Detailed pharmacokinetic analysis based on an open, two-compartment linear model revealed no significant differences in apparent volume of distribution and apparent first-order distribution and elimination rate constants between the anephric patients and normal adult subjects. An estimate of salicyluric acid formation rate by the anephric patients, based on the initial rate of increase of salicylurate concentrations in plasma, indicates that the metabolite is formed at a normal rate. These results suggest that the kidneys do not contribute significantly to the formation of salicyluric acid from salicylic acid in man.

Authors

David T. Lowenthal, William A. Briggs, Gerhard Levy

Enhanced Phagocytic Capacity THE BIOLOGIC BASIS FOR THE ELEVATED HISTOCHEMICAL NITROBLUE TETRAZOLIUM REACTION

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Abstract

The biologic basis for the elevated histochemical reduction of nitroblue tetrazolium dye (NBT) in neutrophils from patients with acute bacterial infection or polycythemia vera was studied. A precipitin reaction followed mixing NBT with heparin. NBT was reduced after phagocytosis of this complex (H-NBT) by polymorphonuclear leukocytes (PMNs). Ingestion required divalent cations and was facilitated by the presence of complement. H-NBT incubated with normal but not with C2-deficient human serum converted native C3 to its inactive form.

Authors

Charles E. McCall, Lawrence R. DeChatelet, Robert Butler, David Brown

Rapid Identification of Candida albicans Septicemia in Man by Gas-Liquid Chromatography

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Gas-liquid chromatography (GLC) was used to study normal serum and serum from patients with septicemia caused by a variety of bacteria and by Candida albicans. The gas chromatograms of seven sera from six patients with septicemia due to C. albicans were found to be significantly and reproducibly different from those of normal sera. Chromatograms of serum from 19 bacteremic patients were indistinguishable from normals. The major peaks present in chromatograms of normal sera were identified by GLC and mass spectroscopy as the methyl esters of palmitic, oleic, linoleic, and stearic acids. In addition to these peaks, serum from patients with candidemia contained abnormal peaks that were also present in cultures of C. albicans grown in normal serum and in washed C. albicans harvested from cultures in yeast nitrogen base broth. Chromatograms from 11 cases of mucosal candidates differed little from normal and were easily distinguished from those of fungemia patients. Chromatograms of serum from two of four patients with deep-invasive candidiasis were indistinguishable from those of fungemia and reverted to normal after infections were eradicated.

Authors

Geraldine G. Miller, Michael W. Witwer, Abraham I. Braude, Charles E. Davis

The Effect of 3′,5′-Adenosine Monophosphate on Granulocyte Adhesion

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Abstract

Human granulocyte adhesion to glass capillary tubes was tested in the presence of agents that increase intracellular levels of cyclic 3′,5′-adenosine monophosphate (cAMP). Adhesion was significantly reduced by 10-3-10-4 M dibutyryl cAMP, 10-4-10-6 M prostaglandin E1 (PGE1), 10-4-10-6 M histamine, or 10-3 M theophylline. Adhesion was not suppressed by 10-4 M theophylline unless it was combined with PGE1 or histamine. Eosinophil and basophil adhesion was especially sensitive to suppression by the above agents. These findings suggest that intracellular cAMP may play a role in regulation of adhesiveness of human basophils, eosinophils, and neutrophils.

Authors

Richard E. Bryant, Marilyn C. Sutgliffe