High skeletal muscle adenylate cyclase in malignant hyperthermia.

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Abstract

Malignant hyperthermia occurs in humans with several congenital myopathies, usually in response to general anesthesia. Commonly, individuals who develop this syndrome lack symptoms of muscle disease, and their muscle lacks specific pathological changes. A biochemical marker for this myopathy has not previously been available; we found activity of adenylate cyclase and content of cyclic AMP to be abnormally high in skeletal muscle. Secondary modification of protein phosphorylation could explain observed abnormalities of phosphorylase activation and sarcoplasmic reticulum function.

Authors

J H Willner, C G Cerri, D S Wood

Human Neutrophil Heterogeneity Identified Using Flow Microfluorometry to Monitor Membrane Potential

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Abstract

Previous studies of neutrophil nitroblue tetrazolium dye reduction in response to endotoxin and rosetting of IgG-coated erythryocytes have suggested functional heterogeneity of peripheral blood neutrophils. In the following study we utilized flow microfluorometry and the membrane potential-sensitive fluorescent dye 3-3′-dipentyloxacarbocyanine to assess the heterogeneity of neutrophils upon activation by a variety of stimuli. Unstimulated neutrophils from normal subjects exhibited a unimodal distribution of fluorescence, suggesting that all the cells possessed the same resting membrane potential. As neutrophils aged (>5 h), some cells lost fluorescence producing a bimodal distribution. In studies with fresh cells, the secretagogue phorbol myristate acetate (20 ng/ml) stimulated a uniform loss of fluorescence (apparent depolarization). The chemoattractant N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) (0.1 μM) caused the neutrophils to assume and maintain (for > 30 min) a bimodal fluorescence distribution in which 65±5% of the neutrophils first decreased and then increased fluorescence (apparent depolarization/partial repolarization), and 35±5% of the cells exhibited either an increase in fluorescence (apparent hyperpolarization) or no change. Treatment of neutrophils with cytochalasin B before stimulation caused the cells to respond homogeneously to f-Met-Leu-Phe. Additional studies using neutrophils from patients with chronic granulomatous disease, which exhibit abnormal membrane potential responses, indicated that this defect affected all such neutrophils uniformly. These observations demonstrate the need to investigate the physiological significance of the heterogeneity of neutrophil function and indicate that the f-Met-Leu-Phe-induced changes in membrane potential observed in bulk population cell studies are the summation of two different responses.

Authors

Bruce Seligmann, Thomas M. Chused, John I. Gallin

A model of decreased functional alpha-1-proteinase inhibitor. Pulmonary pathology of dogs exposed to chloramine T.

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Abstract

The objective of this study was to develop an animal model representative of chronic human alpha-1-proteinase inhibitor deficiency. Eight dogs were treated with a mild oxidizing agent, chloramine T, with varying regimens for 3--27 wk. The capacity of the serum to inhibit both trypsin and elastase was examined and found to respond differently. Although immunologically determined levels of protease inhibitor did not change, the ability of serum to inhibit elastase in an in vitro assay decreased in direct response to chloramine T treatment. The trypsin inhibitory capacity was less affected. Emphysemalike alterations in lung morphology were observable when histologic sections were evaluated both subjectively and objectively by mean linear intercept measurements. The data suggest that this model parallels the emphysema associated with the genetic alpha-1-proteinase inhibitor deficiency in man.

Authors

W R Abrams, A B Cohen, V V Damiano, A Eliraz, P Kimbel, D R Meranze, G Weinbaum

Active Immunization with Lipopolysaccharide Pseudomonas Antigen for Chronic Pseudomonas Bronchopneumonia in Guinea Pigs

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Abstract

Chronic respiratory infection with Pseudomonas aeruginosa is a leading clinical problem among patients with cystic fibrosis. Because antimicrobial agents are usually ineffective in eradicating these infections, additional therapeutic or prophylactic measures should be considered. In this study, an experimental guinea pig model of chronic Pseudomonas aeruginosa bronchopneumonia was utilized to determine whether active immunization with lipopolysaccharide (LPS) P. aeruginosa antigen may favorably influence the course of this infection. Experimental pneumonia was established by tracheobronchial instillation of suspensions of microscopic agar beads, which were impregnated with viable P. aeruginosa. After 4 wk of infection, the geometric mean (reciprocal) passive hemagglutinating Pseudomonas antibody titer was 185±1.3, and lungs contained 16.8±4 × 103 colony-forming units Pseudomonas/ml of lung homogenate. Pseudomonas immunization, given prior to a 4-wk infection, resulted in significantly higher passive hemagglutinating titers (474±1.4; P < 0.05), lower numbers of viable Pseudomonas in lung tissues (2.4±0.6 × 103; P < 0.01), and reduced histopathology in lungs. In contrast, providing Pseudomonas immunization to animals 2 wk after pulmonary infection was established, offered no apparent benefit. Likewise, no protection was afforded by prophylactic immunization with a non-Pseudomonas LPS antigen (Escherichia coli J5 vaccine). Using a Raji cell assay, modified to detect circulating immune complexes in vaccinated and infected guinea pig sera, there was no evidence that active immunization increased the frequency of circulating immune complexes in infected guinea pigs.It is concluded that prophylactic immunization with Pseudomonas LPS antigen may confer protection from subsequent Pseudomonas bronchopneumonia, but that immunization during established infection is not beneficial.

Authors

James E. Pennington, William F. Hickey, Linda L. Blackwood, M. Amin Arnaut

Hepatic and renal metabolism of somatostatin-like immunoreactivity. Simultaneous assessment in the dog.

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Abstract

The hepatic and renal metabolism of somatostatin-like immunoreactivity (SLI) was assessed simultaneously in an in vivo dog model. The hepatic extraction of this peptide was 29.4 +/- 2.3% and was similar for endogenous and infused exogenous SLI. The renal extraction was 62.3 +/- 5%. The renal clearance of SLI was significantly greater than that of inulin indicating that the peptide is handled by peritubular uptake from postglomerular blood in addition to glomerular filtration. In both organs SLI extraction was not saturable even at arterial concentrations in excess of 100 times physiological range. The overall metabolic clearance rate of SLI was 19.7 +/- 1.6 ml/kg per minute of which 32.7 +/- 4.6% was contributed by hepatic and 37 +/- 4.9% by renal uptake mechanisms. The plasma half disappearance time of exogenously infused SLI was 1.9 +/- 0.3 min. The studies indicate that in the dog, the liver and kidney are both major sites of SLI metabolism, together accounting for 70.0 +/- 8.7% of the metabolic clearance of the peptide.

Authors

K S Polonsky, J B Jaspan, M Berelowitz, D S Emmanouel, J Dhorajiwala

Replacement therapy of alpha 1-antitrypsin deficiency. Reversal of protease-antiprotease imbalance within the alveolar structures of PiZ subjects.

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Abstract

The emphysema associated with the inherited serum deficiency of alpha 1-antitrypsin appears to result from an imbalance between neutrophil elastase and its major inhibitor within the alveolar structures. In the present study we assessed the feasibility of reversing this biochemical defect within the lung via parenteral replacement therapy with an alpha 1-antitrypsin concentrate of normal plasma. A 20--40% polyethylene glycol precipitate of pooled human donor plasma was used to obtain an enriched alpha 1-antitrypsin concentrate devoid of hepatitis B antigen and immunoglobulins. Using this material, five individuals with severe serum alpha 1-antitrypsin deficiency (PiZ phenotype) and advanced emphysema received 4 g of alpha 1-antitrypsin intravenously at weekly intervals for four doses. During this period of weekly replacement therapy alpha 1-antitrypsin serum levels were maintained at greater than or equal to 70 mg/dl, the level likely required for effective antielastase protection of the lung. In addition, assessment of lower respiratory tract antielastase activity by bronchoalveolar lavage demonstrated that parenteral replacement of alpha 1-antitrypsin resulted in establishment of effective antielastase activity within the alveolar structures. There were no untoward side effects consequent to this approach to the replacement therapy of alpha 1-antitrypsin. These results demonstrate that the parenteral replacement of alpha 1-antitrypsin provides a means of obtaining elastase-antielastase balance within the lung of individuals with this serum protease inhibitor deficiency.

Authors

J E Gadek, H G Klein, P V Holland, R G Crystal

Elevated cholesterol and bile acid synthesis in an adult patient with homozygous familial hypercholesterolemia. Reduction by a high glucose diet.

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Abstract

Elevated levels of cholesterol synthesis are reported for several young children with homozygous familial hypercholesterolemia (HFH) and are considered to contribute directly to their hypercholesterolemia. In contrast, increased cholesterol production has not previously been found in adult patients with HFH. Using the fecal steroid balance technique, we studied rates of cholesterol and bile acid synthesis in a 24-yr-old man who had severe hypercholesterolemia typical of HFH and who lacked skin fibroblast low density lipoprotein (LDL) receptor activity. On an average diet (45% carbohydrate, 40% fat, 15% protein) mean +/- SEM cholesterol (24.8 +/- 1.4 mg/kg per d) and bile acid (11.1 +/- 1.6 mg/kg per d) excretion were approximately threefold higher than normal. When an isocaloric high carbohydrate, low fat diet (90.5% glucose oligosaccharides, 1.3% safflower oil, 8.2% crystalline amino acids was substituted, mean cholesterol (13.0 +/- 0.5 mg/kg per d) and bile acid (8.6 +/- 0.4 mg/kg per d) fell markedly. The decline in fecal steroid excretion was accompanied by modest reductions in plasma total and LDL cholesterol concentrations and by a softening of cutaneous xanthomata. Although the patient phenotypically and biochemically resembled the HFH state, his family pedigree was not noteable for hypercholesterolemia. While the patient's father had premature cardiovascular disease, his mother had no evidence of heart disease, had normal plasma total and LDL cholesterol levels, and had normal fibroblast LDL receptor activity. Likewise, the plasma cholesterol levels of three other members of the patient's family were normal. Despite the unusual genotypic background of this individual, however, the fecal balance data shows that elevated cholesterol and bile acid synthesis may occur in adult, as well as juvenile, patients with HFH and may be responsive to dietary control.

Authors

P W Stacpoole, S M Grundy, L L Swift, H L Greene, A E Slonim, I M Burr

Virus-induced alterations in insulin release in hamster islets of Langerhans.

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Abstract

After the inoculation of Golden Syrian hamsters with the TC-83 vaccine strain of Venezuelan encephalitis (VE) virus, a sustained diminution in glucose-stimulated insulin release and glucose intolerance of shorter duration develops. To understand better the mechanism of this defect in insulin release, we examined insulin secretion in response to several test agents in isolated perifused islets from control and 24-d post-VE virus-infected hamsters. 50 islets were used in all perifusion experiments, and data were expressed as total insulin released as well as peak response for each test agent during a 30-min perifusion period from control and VE-infected islets. After perifusion with 20 mM glucose, a 45% diminution of insulin release was noted in VE-infected islets in comparison with control islets, which in turn was similar to in vivo findings. However, following 1-mM tolbutamide stimulation, insulin release was similar in control and VE-infected islets. In separate studies, 1 mM tolbutamide, 10 mM theophilline, 1 mM dibutyryl cyclic (c)AMP, and 1 mM 8-bromo-cAMP resulted in statistically similar insulin-release curves in control and VE-infected islets. Additional experiments assessing [5-3H]glucose use in control and infected islets after 20 min of perifusion with 20 mM glucose revealed virtually identical values (239 +/- 30-control; and 222 +/- 27-VE-infected islets). Morphological and morphometric evaluation of VE-infected islets (21 d following virus inoculation) showed no changes in islet volume density, beta cell density, and beta cell granulation. Thus, VE virus induces a defect in glucose-stimulated insulin release from hamster beta cells that can be corrected by cAMP analogues and does not alter islet glucose use.

Authors

E J Rayfield, Y Seto, S Walsh, R C McEvoy

Selective Effects of Glucocerebroside (Gaucher's Storage Material) on Macrophage Cultures

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Abstract

Although the enzymatic lesion in Gaucher's disease is well established, little is known concerning the pathogenic mechanisms involved in the clinical manifestations of the disease. In order to obtain insight into this unexplored aspect of Gaucher's disease, we examined the effects of glucocerebroside (GL1) at the cellular level in monolayers of cultured murine macrophages. The addition of GL1 to these cultures stimulated the macrophages to release increased amounts of lymphocyte-activating factor (LAF) and lysosomal enzymes into the medium. These responses were proportional to the amount of GL1 added to the culture. At higher levels of GL1 (≥20 μg/ml), lactic dehydrogenase, a cytoplasmic enzyme was also released indicating cellular damage at these doses. Intracellular LAF also increased in macrophages incubated with the high doses of GL1, demonstrating an increase in total LAF production by these cells. Lipopolysaccharide acted synergistically with GL1 and stimulated the release of exceedingly high levels of LAF which had a molecular weight profile similar to that of LAF released by exposure to lipopolysaccharide alone. Unlike GL1, galactocerebroside, sphingomyelin, and ceramidetrihexoside, exerted little or no effect on the release of macrophage products. The effect of GL1 was selective for macrophages since addition of this material to mouse lens epithelial cells had no detectable cytotoxic effect and it was only slightly toxic to lymphocytes or P815 cells in concentrations at which macrophages were clearly affected. A direct relationship was observed between the cytotoxicity of the sphingolipids and their accumulation in various cells. Macrophages accumulated large amounts of GL1 but not sphingomyelin, whereas the other cells examined in this investigation did not accumulate either of these lipids. Human monocytes, like murine macrophages, also release increased amounts of LAF when incubated with GL1. The effect of GL1 was dose-responsive and synergy was found with lipopolysaccharide. The relevance of these findings to the pathogenesis of Gaucher's disease is considered.

Authors

Igal Gery, J. Samuel Zigler Jr., Roscoe O. Brady, John A. Barranger

Sulfation of Lithocholate as a Possible Modifier of Chenodeoxycholic Acid-induced Elevations of Serum Transaminase in Patients with Gallstones

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Abstract

Chenodeoxycholic acid (CDC), through its metabolite, lithocholic acid (LC), is hepatotoxic in certain species. The cause of elevations of serum transaminase in 25% of humans ingesting CDC, however, is unknown, but also may be due to LC. Because efficient hepatic sulfation of LC may protect against hepatic injury, the aim of this study was to determine if sulfation of LC might modify CDC-induced elevations of transaminase. Pretreatment sulfation fraction (SF) was estimated in 63 randomly selected patients with gallstones in a double-blind randomized trial of CDC, 750 mg/d, 375 mg/d, or placebo; in 27 of these, SF was repeated at 1 or 2 yr. In four other patients, the SF was measured at 2 yr only. Serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase were determined monthly for 3 mo and then every 3 or 4 mo; an elevation of transaminase was defined as > 150% of the normal upper limit in asymptomatic patients. 10 μCi of 3H-glyco-LC (sp act 84 mCi/mol) was ingested 10-12 h before fasting duodenal biliary drainage. Bile acids in bile were separated by thin-layer chromatography. The SF was estimated as a percentage of total radioactivity (scintillation counting) in sulfated glyco-LC. The standard deviation for replicate SF determinations (n = 311) was 2.1% The pretreatment SF (mean 60.7±1.7 SEM) correlated inversely with age (r = 0.336, P < 0.005) and directly with the obesity index (r = 0.495, P > 0.001), but was independent of sex. The SF, remeasured at 1 or 2 yr, did not change significantly with time or CDC. Among CDC-treated patients, elevations of transaminase occurred in 75% of patients with a SF < 45% vs. 11% with a SF > 45% (P < 0.001). In conclusion, a SF < 45% occurred in patients with gallstones who had a high probability of developing elevated serum transaminase when treated with CDC. Thus, sulfation of lithocholate may modify CDC-induced elevations of serum transaminase.

Authors

J. W. Marks, S. O. Sue, B. J. Pearlman, G. G. Bonorris, P. Varady, J. M. Lachin, L. J. Schoenfield

Two independent lipoprotein receptors on hepatic membranes of dog, swine, and man. Apo-B,E and apo-E receptors.

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Abstract

We have reported previously that canine livers possess two distinct lipoprotein receptors, an apoprotein (apo)-B,E receptor capable of binding the apo-B-containing low density lipoproteins (LDL) and the apo-E-containing cholesterol-induced high density lipoproteins (HDLc), and an apo-E receptor capable of binding apo-E HDLc but not LDL. Both the apo-B,E and apo-E receptors were found on the liver membranes obtained from immature growing dogs, but only the apo-E receptors were detected on th hepatic membranes of adult dogs. In this study, the expression of the apo-B,E receptors, as determined by canine LDL binding to the hepatic membranes, was found to be highly dependent on the age of the dog and decreased linearly with increasing age. Approximately 30 ng of LDL protein per milligram of membrane protein were bound via the apo-B,E receptors to the hepatic membranes of 7- to 8-wk-old immature dogs as compared with no detectable LDL binding in the hepatic membranes of adult dogs (greater than 1--1.5 yr of age). Results obtained by in vivo turnover studies of canine 125I-LDL correlated with the in vitro findings. In addition to a decrease in the expression of the hepatic apo-B,E receptors with age, these receptors were regulated, i.e., cholesterol feeding suppressed these receptors in immature dogs and prolonged fasting induced their expression in adult dogs. Previously, it was shown that the apo-B,E receptors were induced in adult livers following treatment with the hypocholesterolemic drug cholestyramine. In striking contrast, the apo-E receptors, as determined by apo-E HDLc binding, remained relatively constant for all ages of dogs studied (10--12 ng/mg). Moreover, the expression of the apo-E receptors was not strictly regulated by the metabolic perturbations that regulated the apo-B,E receptors. Similar results concerning the presence of apo-B,E and apo-E receptors were obtained in swine and in man. The hepatic membranes of adult swine bound only apo-E HDLc (apo-E receptors), whereas the membranes from fetal swine livers bound both LDL and apo-E HDLc (apo B,E and apo-E receptors). Furthermore, the membranes from adult human liver revealed the presence of the apo-E receptors as evidenced by the binding of 12--14 ng of HDLc protein per milligram of membrane protein and less than 1 ng of LDL protein per milligram. The membranes from the human liver also bound human chylomicron remnants and a subfraction of human HDL containing apo-E. These data suggest the importance of the E apoprotein and the apo-E receptors in mediating lipoprotein clearance, including chylomicron remnants, by the liver of adult dogs, swine, and man.

Authors

R W Mahley, D Y Hui, T L Innerarity, K H Weisgraber

Stimulation of Monovalent Cation Active Transport by Low Concentrations of Cardiac Glycosides: ROLE OF CATECHOLAMINES

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Abstract

The stimulatory effect of low concentrations of ouabain on the Na-K pump in isolated guinea pig left atria was studied in vitro by assessing active transport of the K+ analog Rb+. Active transport of Rb+ was stimulated 20±8% (SEM, P < 0.05) above control values by 3 nM ouabain, but was inhibited by concentrations >10 nM. Preincubation with the β-adrenergic antagonist propranolol (1 μM) completely blocked stimulation of active transport of Rb+ by 3 nM ouabain. Norepinephrine, 10 nM, increased Rb+ active transport 29±10% (P < 0.02) above control values. The β-adrenergic agonist l-isoproterenol, 10 nM, increased active transport of Rb+ by 33±10% (P < 0.01) above control levels. This stimulatory effect was abolished if tissues were first exposed to propranolol. Tyramine (0.1 μM), a stimulator of endogenous catecholamine release, increased active transport of Rb+ 26±12% (P < 0.05) above control values. Rb+ active transport was not significantly changed when left atrial tissues were incubated with α-adrenergic agonists or antagonists. Ouabain stimulation of Rb+ active transport was prevented by in vivo depletion of myocardial endogenous catecholamines by either reserpine or 6-hydroxydopamine. These findings indicated that in myocardial tissue, Na-K pump stimulation by low concentrations of ouabain is mediated at least in part through β-adrenergic effects of endogenous catecholamines.

Authors

Thomas J. Hougen, Nancy Spicer, Thomas W. Smith

Effect of cetiedil, an in vitro antisickling agent, on erythrocyte membrane cation permeability.

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Abstract

Cetiedil has been reported to relieve painful crises in sickle cell anemia and to have antisickling properties in vitro. The drug alters neither oxygen affinity nor the solubility of deoxyhemoglobin S. Because the viscosity of the erythrocyte interior and the kinetics of gelation are dependent on the concentration of hemoglobin, we postulated that cetiedil might inhibit sickling by modifying erythrocyte sodium or potassium movements in a manner that would increase cell water content and thus dilute the cell hemoglobin. The drug has two such effects: it inhibits the specific increase in potassium permeability that follows a rise in cytoplasmic calcium concentration and it causes a rise in passive sodium movements. These effects are further evidence that cell ion and water movements may be important in the process of sickling and suggest a mechanism for the results reported with cetiedil.

Authors

L R Berkowitz, E P Orringer

Generation of fibrinolytic activity by infusion of activated protein C into dogs.

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Abstract

Bovine-activated protein C, administered intravenously to dogs, increases the rate of lysis of whole blood clots. Protein C, bovine prothrombin, and diisopropylfluorophosphate-inactivated protein Ca do not increase the rate of lysis. Repeated infusions of protein Ca sustain rapid blood clot lysis, but neither elevate circulating fibrin-split products nor decrease circulating plasminogen levels. The administration of protein Ca results in the elevation of the levels of lysine-adsorbable plasminogen activator activity in the plasma. When partially purified concentrates of this activator are added to normal dog blood at the levels seen following protein Ca injection, the rate of clot lysis is similar to that seen after protein Ca injection. The addition of protein Ca to citrated whole blood in vitro, with the subsequent neutralization of protein Ca with antibodies, results in increased rates of lysis when plasma made from the treated blood is reinjected into the animal. The generation of fibrinolytic activity is dependent on both cellular and plasma components of blood. A model of protein Ca fibrinolytic activity has a minimum of two components: a secondary messenger formed by protein Ca action on blood cells and plasma, and the subsequent appearance of plasminogen activator in the animal in response to that messenger.

Authors

P C Comp, C T Esmon

Biliary lipids, bile acids, and gallbladder function in the human female. Effects of pregnancy and the ovulatory cycle.

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Abstract

To study the events that might lead to an increased risk of cholesterol gallstones, we examined biliary lipid composition and secretion and bile acid composition and kinetics at different stages of pregnancy or ovulation in young, nonobese, healthy women. Lipid composition and bile acid distribution were determined in duodenal fluid obtained in the fasting state and after stimulation of the gallbladder. Biliary lipid secretion was measured by the marker-perfusion technique. Bile acid kinetics were determined with cholic and chenodeoxycholic acids labeled with carbon13, by measuring the relative abundance of 13C in duodenal bile acids for 4--5 d. In a subset of patients we measured gallbladder storage and emptying during the kinetic study. The phase of the ovulatory cycle had no effects, but there were significant changes during pregnancy. The lithogenic or cholesterol saturation index of fasting hepatic and gallbladder bile increased during the second and third trimesters. The mean secretion rate of biliary lipids was not altered, but in the last two-thirds of pregnancy, cholesterol secretion increased in relation to bile acid and phospholipid secretion. There was a progressive decrease in the percentage of chenodeoxycholic acid and a similar increase in the percentage of cholic acid. The pool size of each major bile acid increased in the first trimester. Chenodeoxycholic acid and deoxycholic acid pools, but not cholic acid pools, subsequently decreased. The fractional turnover rate of both primary bile acids was slower during pregnancy. The synthesis rate of chenodeoxycholic but not cholic acid decreased in a linear manner during the first 20 wk of pregnancy. The rate of enterohepatic cycling of the bile acid pool was reduced throughout pregnancy. The volume of the fasting gallbladder and the residual volume after a physiologically stimulated contraction were directly correlated with bile acid pool size. The residual volume was also directly related to total bile acid synthesis.

Authors

F Kern Jr, G T Everson, B DeMark, C McKinley, R Showalter, W Erfling, D Z Braverman, P Szczepanik-van Leeuwen, P D Klein

Hydrogen peroxide metabolism in human monocytes during differentiation in vitro.

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Abstract

The capacity of human blood monocytes to secrete hydrogen peroxide (H2O2) and superoxide (O2-) was measured as the cells differentiated during 4 wk of culture. Morphologic transformation of monocytes into macrophages, epithelioid cells, and multinucleated giant cells accompanied a steady increase in the content of protein per cell, from 0.77 mg/10(7) cells on days 0 to 11.77 mg/10(7) cells on days 20 to 29. In contrast, secretion of H2O2 by adherent monocytes was 859 +/- 73 nmol/60 min per mg protein (mean +/- SEM, n = 18) on day 0, rose 40% on day 3, and then fell rapidly, remaining below 6% of the initial values after day 10. The decline in capacity to secrete reactive oxygen intermediates was observed whether H2O2 or O2- were measured, whether the cells were challenged with phorbol myristate acetate or with opsonized zymosan, and whether the results were expressed per milligram cell protein or per cell. Superoxide dismutase activity tripled in adherent monocytes from day 0 to day 3, and thereafter remained elevated through at least day 16. In contrast, the activity of myeloperoxidase declined rapidly, catalase and glutathione peroxidase declined more gradually, and glutathione reductase and glutathione remained constant through the period of observation. Thus, the decline in capacity to secrete H2O2 could not be attributed to increases in cellular levels of these antioxidants. On the first day of culture, H2O2 release was enhanced up to fourfold by inclusion of sodium azide or potassium cyanide in the assay medium. This enhancement appeared to be due to inhibition of monocyte myeloperoxidase, rather than catalase. This conclusion was based on the kinetics and dose-response relationships for the effects of azide and cyanide on H2O2 release and on the activities of catalase and myeloperoxidase. Thus, the differentiation of human monocytes into macrophages in vitro is accompanied by an apparent reduction in the capacity to produce H2O2 and O2-. In this regard, the human monocyte-derived macrophage comes to resemble the resting tissue macrophage previously characterized in the mouse peritoneal cavity.

Authors

A Nakagawara, C F Nathan, Z A Cohn

Prevention by granulocyte depletion of increased vascular permeability of sheep lung following endotoxemia.

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Abstract

To see whether circulating granulocytes are necessary for the lung vascular reaction to endotoxin, we measured the endotoxin response in chronically instrumented sheep before and after granulocyte depletion with hydroxyurea. Granulocyte depletion did not affect the pulmonary hypertension caused by endotoxin (peak mean pulmonary artery pressures = 38 +/- 2 cm H2O before depletion and 42 +/- 2 after depletion, P = NS). The late phase increase in lung lymph flow after endotoxin was significantly lower in the granulocytopenic animals as reflected by lung lymph flow (mean steady state lymph flow before depletion = 30.6 +/- 2.0 SE ml/h; mean steady state lymph flow after granulocyte depletion = 15.4 +/- 1.0; P less than 0.01) even though late phase pulmonary vascular pressures were similar before and after granulocyte depletion. Lung lymph protein clearance (lymph flow x lymph/plasma protein concentration) was also significantly lower after granulocyte depletion (mean steady state before depletion = 2.14 +/- 1.4 SE ml/h; and after depletion = 10.4 +/- 1.0; P less than 0.01). We conclude that circulating granulocytes are necessary for the development of increased lung vascular permeability to fluid and protein following endotoxin. The pulmonary vasopressor effects of endotoxin in sheep are independent of granulocytes.

Authors

A C Heflin Jr, K L Brigham

Short-term effects of synthetic human parathyroid hormone-(1--34) administration on bone mineral metabolism in osteoporotic patients.

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Abstract

Since studies in animals and humans have shown that parathyroid hormone can stimulate bone formation and increase trabecular bone, and patients with primary and secondary hyperparathyroidism may exhibit osteosclerosis, we evaluated the effect of short-term administration of human parathyroid hormone, hPTH-(1--34), in patients with osteoporosis. Six patients with osteoporosis underwent detailed studies including blood and urinary measurements of calcium, phosphate, and magnesium; 47Ca kinetic studies; and 18-d balance studies before and during the short-term administration (3--4 wk) of a daily subcutaneous injection of hPTH fragment 1--34 given as 450 or 750 U/dose. The mean fasting plasma calcium values rose slightly after hPTH-(1--34) administration, primarily in the high-dose group. There was no difference in the mean fasting plasma inorganic phosphate levels. The mean daily urinary excretion of calcium and phosphate was significantly increased in patients given the higher dose. In patients given 750 U, net intestinal calcium absorption increased, phosphate absorption increased, calcium balance improved, and phosphate balance improved. In patients given 450 U, calcium balance and phosphate balance worsened. 47Ca kinetic studies showed a minimal increase in bone accretion rate, a decrease in the mean transit time of calcium in the exchangeable pools, and a decrease in the exchangeable-pool size. In all six patients there was an increased renal clearance of 47Ca as a result of hPTH-(1--34) administration. These studies indicate that low doses of parathyroid hormone may promote bone formation, whereas higher doses clearly have an adverse effect on the skeleton.

Authors

D M Slovik, R M Neer, J T Potts Jr

Estimated rate of prostacyclin secretion into the circulation of normal man.

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Abstract

The rate of secretion of prostacyclin (PGI2) into the circulation of normal man was estimated by measurement of the 2,3-dinor-6-keto-PGF1 alpha (D) and 15-keto-13,14-dihydro-2,3-dinor-6-keto-PGF1 alpha (KDD) urinary metabolites of PGI2. Subjects received 6-h intravenous infusions of vehicle alone and PGI2 at 0.1, 0.4, and 2.0 ng/kg per min in random order. The fractional elimination of the metabolites was independent of the rate of PGI2 infusion. 6.8 +/- 0.3% of the infused PGI2 appeared as D and 4.1 +/- 0.4% as KDD. The regression of infused PGI2 upon the quantities of the two metabolites excreted in excess of control values permitted estimation of the rate of entry of endogenous PGI2 into the circulation corresponding to a given quantity of metabolite excreted. Using the quantities excreted in the 24 h from commencement of the infusions the estimated rates were 0.08 +/- 0.02 ng/kg per min from D and 0.10 +/- 0.03 from KDD. Studies with exogenous PGI2 suggest that infusion rates 2--4 ng/kg per min are required to achieve the threshold for inhibition of platelet function (ex vivo) in man. Although not precluding a role for PGI2 in local platelet-vessel wall interactions, the much lower estimates obtained in this study suggest that endogenous PGI2 is unlikely to act as a circulating antiplatelet agent in healthy man.

Authors

G A FitzGerald, A R Brash, P Falardeau, J A Oates

Oxidant injury of lung parenchymal cells.

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Abstract

Hyperoxia and paraquat ingestion are two clinical examples of lung injury thought to be mediated by oxidant mechanisms. An in vitro cytotoxicity assay using freshly explanted 51Cr-labeled lung tissue as the target was used to quantify the ability of hyperoxia and paraquat to directly injure lung parenchymal cells in an environment where indirect mechanisms such as recruitment of inflammatory cells were not possible. There are clear species differences in the susceptibility of lung parenchyma to direct injury by hyperoxia (95% O2) and paraquat (10 microM--10 mM) for 18 h at 37 degrees C, with human and rat lung being more sensitive than rabbit lung. Oxygen radical inhibitors, particularly catalase (1,100 U/ml) and alpha-tocopherol (10 micrograms/ml), reduced hyperoxia and paraquat-induced lung injury, although their ability to do so depended on the oxidant and the species. The simultaneous use of hyperoxia and paraquat accelerated the in vitro lung parenchymal cell injury in each species tested. These studies demonstrate that both oxygen and paraquat can directly injure the cells of the lower respiratory tract without enlisting the aid of additional blood-derived inflammatory cells. In addition, the 51Cr-labeled lung explant assay used for these studies allows for the quantitative assessment of direct lung cell injury and thus may prove useful as an in vitro model by which to investigate lung injury of other etiologies.

Authors

W J Martin 2nd, J E Gadek, G W Hunninghake, R G Crystal

Hemostatic Function, Survival, and Membrane Glycoprotein Changes in Young versus Old Rabbit Platelets

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Abstract

Although in vitro studies have demonstrated functional differences between young and old platelets, in vivo differences have not been precisely established. Therefore the in vivo hemostatic function of young and old platelets and the survival time have been examined in rabbits. The hemostatic function was measured by performing serial ear bleeding times in irradiation-induced thrombocytopenic rabbits. After irradiation with 930 rad the platelet count gradually diminished reaching a nadir (∼20 × 103/μl) at 10 d. The platelets present in the circulation, 7-10 d after irradiation, were considered old platelets, and the platelets present after recovery, 11-14 d postirradiation, young platelets. The measurement of platelet size was consistent with the hypothesis that platelets become smaller with age: the mean size was 3.84 μm3 for old platelets and 5.86 μm3 for young platelets. Regression analysis of the relationship between the bleeding time and the platelet count in 18 rabbits showed a significantly different slope for rabbits with predominantly old platelets compared with rabbits with predominantly young platelets (P < 0.001). Young platelets were more effective giving much shorter bleeding times than old platelets at comparable platelet counts. Survival times of young and old platelets were measured using platelets harvested on day 8 postirradiation (old platelets) and day 12 postirradiation (young platelets) that were labeled and then reinjected into normal recipient animals. The mean platelet survival time, calculated by gamma function, of old platelets was 28.8 h; of young platelets, 87.4 h; and of normally circulating heterogeneous platelets, (normal platelets) 53.0 h. Notably, the survival of old platelets was found to be exponential, and of young platelets, linear. Analysis of the membrane glycoproteins in young, old and normal platelets indicated that there was no qualitative difference amongst the young, normal, and old platelets. The relative relationship among all the glycoprotein peaks was equal and the only changes observed were quantitative, with young platelets having significantly more membrane glycoprotein per cell than old platelets and normal platelets. Normal platelets had intermediate concentrations of each glycoprotein. These results demonstrate that young platelets are hemostatically more effective in vivo than old platelets. The data are compatible with the hypothesis that platelets age in the circulation by losing membrane fragments and then after becoming senescent, are removed from the circulation by a random process.

Authors

Morris A. Blajchman, Andrew F. Senyi, Jack Hirsh, Edward Genton, James N. George

Abnormal high density lipoproteins in cerebrotendinous xanthomatosis.

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Abstract

The plasma lipoprotein profiles and high density lipoproteins (HDL) were characterized in patients with the genetic disease cerebrotendinous xanthomatosis (CTX). Abnormalities in the HDL may contribute to their increased atherogenesis and excessive deposits of tissue sterols in the presence of low or low-normal concentrations of plasma cholesterol (165 +/- 25 mg/dl) and low density lipoproteins (LDL). The mean HDL-cholesterol concentration in the CTX plasmas was 14.5 +/- 3.2 mg/dl, about one-third the normal value. The low HDL-cholesterol reflects a low concentration and an abnormal lipid composition of the plasma HDL. Relative to normal HDL, the cholesteryl esters are low, free cholesterol and phospholipids essentially normal, and triglycerides increased. The ratio of apoprotein (apo) to total cholesterol in the HDL of CTX was two to three times greater than normal. In the CTX HDL, the ratio of apoAI to apoAII was high, the proportion of apoC low, and a normally minor form of apoAI increased relative to other forms. The HDL in electron micrographs appeared normal morphologically and in particle size. The abnormalities in lipoprotein distribution profile and composition of the plasma HDL result from metabolic defects that are not understood but may be linked to the genetic defect in bile acid synthesis in CTX. As a consequence, it is probable that the normal functions of the HDL, possibly including modulation of LDL-cholesterol uptake and the removal of excess cholesterol from peripheral tissues, are perturbed significantly in this disease.

Authors

V Shore, G Salen, F W Cheng, T Forte, S Shefer, G S Tint, F T Lindgren

Role of Adherence in Cytopathogenic Mechanisms of Entamoeba Histolytica: STUDY WITH MAMMALIAN TISSUE CULTURE CELLS AND HUMAN ERYTHROCYTES

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Abstract

The enteric pathogen, Entamoeba histolytica, appears to cause disease by adhering to and then destroying mucosal barriers. Using an in vitro method of studying the interaction of E. histolytica with target cells (Chinese hamster ovary [CHO] and human erythrocytes [RBC]), we examined the mechanism of amebic adherence and its role in lysis of target cells. Killing and phagocytosis of target cells by amebas ceases at 4°C, allowing observation of adherence. Amebas adhere to CHO cells at 4°C, 78.9% formed rosettes (amebas with ≥3 adherent CHO cells each) at 2 h. At 37°C, cytochalasins B and D inhibit adherence of amebas to CHO cells (P < 0.0005). Amebas adhere to and kill CHO cells in media with <0.1 μM calcium and magnesium plus 10 mM EDTA, indicating that divalent cations are not required in the medium. Adherence of amebas to human RBC was not ABO blood group specific and showed greater adherence to human than bovine or sheep RBC (P < 0.005). Neither Fc nor complement receptors were found on amebas by standard rosette studies. The amebic adherence receptor is not trypsin (0.125%) sensitive nor inhibited by trypan blue (1 mM). N-acetyl-d-galactosamine (GALNAc) inhibited the adherence of amebas to CHO cells and human RBC (0.1 g/100 ml or 4.5 mM GALNAc, P < 0.005) by binding to a receptor on the amebic surface. GALNAc abolishes amebic cytolysis of target CHO cells (determined by 111Indium oxine release from CHO cells, P < 0.001) but not amebic phagocytosis of CHO cells. By suspending ameba-CHO cells rosettes in dextran, we found that GALNAc (1%) reversibly inhibits amebic adherence (P < 0.0005) and that cytochalasins decrease amebic killing of adherent CHO cells (P < 0.025).

Authors

Jonathan I. Ravdin, Richard L. Guerrant

Receptor-mediated regulation of superoxide production in human neutrophils stimulated by phorbol myristate acetate.

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Abstract

Human neutrophils contain receptors for phorbol myristate acetate (PMA), a complex lipid that induces them to generate superoxide (O (2)). Binding of PMA to these receptors displays specificity, reversibility, and high affinity. The receptor's apparent KD was approximately 0.29 nM and multiple copies (approximately 2.1 +/- 0.6 x 10(5)) were present per neutrophil. We found that the timing and magnitude of the neutrophil's respiratory burst were set independently. The onset of O (2) production occurred after a lag that was inversely proportional to the initial concentration of added PMA. The extent (rate) of O (2) production was directly proportional to the fractional occupancy of the receptor by PMA. Dual regulatory controls, such as those we noted when neutrophils were stimulated by PMA, could afford metabolic stability in the face of transient or low intensity stimuli without compromising quick and powerful responses to larger disturbances.

Authors

R I Lehrer, L Cohen

Radioimmunological determination of insulinlike growth factors I and II in normal subjects and in patients with growth disorders and extrapancreatic tumor hypoglycemia.

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Abstract

Serum levels of immunoreactive insulinlike growth factors (IGF) I and II were determined by a modified IGF I and a new IGF II radioimmunoassay in normal children and adults, and in patients with acromegaly, isolated growth hormone deficiency, and extrapancreatic tumor hypoglycemia. Serum samples were gel filtered by a simple routine procedure at acidic pH to dissociate and separate IGF from the IGF carrier protein. Mean immunoreactive IGF I levels (+/- SD; corrected for crossreactivity of IGF II) were 193 +/- 58 ng/ml in normal adult subjects, 712 +/- 245 ng/ml in acromegalic patients and 24 +/- 14 ng/ml in patients with isolated growth hormone deficiency. The lack of growth hormone alone, irrespective of an otherwise normal hormonal status, appears to be responsible for the drastic decrease of IGF I levels. Oversecretion of growth hormone does not increase the levels of immunoreactive IGF II: mean levels (+/- SD; corrected for crossreactivity of IGF I) in normal and acromegalic subjects are virtually identical (647 +/- 126 and 641 +/- 189 ng/ml, respectively). Apparently, normal growth hormone levels stimulate IGF II production already maximally. However in growth hormone deficiency immunoreactive IGF II is significantly decreased (252 +/- 99 ng/ml). Thus, IGF II, like IGF I, is growth hormone dependent. But in contrast to IGF I, the growth hormone dependence of IGF II seems to become apparent only at subnormal growth hormone levels. In normal children IGF I is age dependent: it is low in newborn cord sera (51 +/- 20 ng/ml) and gradually rises into the adult range with increasing age. At the onset of and during puberty mean IGF I levels lie above prepubertal values. In contrast, IGF II levels in normal children are independent of age and pubertal stage beyond the first year of life, whereas newborns have significantly lower IGF II values. Hypoglycemia resulting from extrapancreatic tumors is not associated with increased immunoreactive IGF I or II levels. IGF I is decreased in most of the sera (mean level +/- SD:56 +/- 39 ng/ml) whereas IGF II lies in the normal range (556 +/- 195 ng/ml).

Authors

J Zapf, H Walter, E R Froesch

Reactivity of a monoclonal antibody with human ovarian carcinoma.

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Abstract

A murine monoclonal antibody (OC125) has been developed that reacts with each of six epithelial ovarian carcinoma cell lines and with cryopreserved tumor tissue from 12 of 20 ovarian cancer patients. By contrast, the antibody does not bind to a variety of nonmalignant tissues, including adult and fetal ovary. OC125 reacts with only 1 of 14 cell lines derived from nonovarian neoplasms and has failed to react with cryostat sections from 12 nonovarian carcinomas.

Authors

R C Bast Jr, M Feeney, H Lazarus, L M Nadler, R B Colvin, R C Knapp

Reaccumulation of thyroglobulin and colloid in rat and mouse thyroid follicles during intense thyrotropin stimulation. A clue to the pathogenesis of colloid goiters.

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Abstract

Since Marine's observations some 50 years ago, it has been generally accepted that colloid goiters invariably result from colloid repletion of originally hyperplastic goiters after cessation of the goitrogenic stimulus. However, clinical observations suggest that many goiters never go through a stage of hyperplasia, but are colloid-rich from the beginning. We have injected rats and mice with thyrotropin (TSH), three times a day for 4 d, while the animals were kept on an iodine-rich diet (HID). Additional groups of animals were fed an iodine-poor diet (LID) or a diet containing 0.15% propylthiouracil (PTU) or 1% sodium perchlorate (ClO4). At intervals, thyroid weight, DNA, iodine and thyroglobulin content, thyroglobulin iodination, and intracellular droplet formation were measured. Histologic sections were also prepared and stained with periodic acid Schiff. Furthermore, thyroxine concentration was measured in the serum. Thyroglobulin content dropped by approximately 30% in HID animals but by 60% in all other groups 1 d after starting TSH. Thereafter, thyroglobulin reaccumulation occurred and droplet formation correspondingly decreased despite continuous heavy TSH stimulation. The largest amount of thyroglobulin was reaccumulated in HID animals followed by the PTU/LID groups, whereas no reaccumulation was observed in the ClO4 group. Reaccumulation of thyroglobulin only occurred if there was concomitant organification of at least some iodine. The subsequent phases of depletion and reaccumulation of thyroglobulin were mirrored by the morphology of the follicular lumina, the staining properties of the colloid and the serum T4 concentration. These observations suggest that endocytosis gradually becomes refractory to continuous TSH stimulation if a certain minimal amount of iodine is available for organic binding. Thus, primarily colloid-rich goiters may form in the presence of continuously higher than normal thyrotropin levels without a previous stage of follicular hyperplasia. The view should be revised that accumulation of colloid and intense thyrotropin stimulation are mutually exclusive events.

Authors

H Gerber, H Studer, A Conti, H Engler, H Kohler, A Haeberli

Cultured human amniotic fluid cells characterized with antibodies against intermediate filaments in indirect immunofluorescence microscopy.

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Abstract

Cells cultured from second trimester human amniotic fluid were characterized in indirect immunofluorescence (IIF) microscopy using specific antibodies against the subunit proteins of different types of cytoskeletal intermediate filaments. Most of the amniotic fluid cell cultures contained only epithelial cells as indicated by the positive keratin-fluorescence in IIF. Five distinct types of keratin-positive cells could be characterized. A dominating cell type (E-1) in most cultures were rapidly proliferating epithelial cells, previously called amniotic fluid cells (AF-cells). These cells showed a fibrillar cytoplasmic fluorescence both with keratin antibodies and with antibodies against vimentin, the fibroblast type of intermediate filament protein. E-1 cells did not show the typical cell-to-cell arrangement of keratin fibrils between the adjacent cells, a characteristic previously found in most cultured epithelial cells. Most of the cultures also contained large epitheloid cells (E-2), showing a fine fibrillar cytoplasmic organization of both keratin- and vimentin filaments, clearly different from that seen in E-1 cells. Several cultures contained two additional epithelial cells both showing the typical cell-to-cell arrangement of keratin fibrils (E-3 and E-4). These two cell types could be distinguished because of their distinct difference in size. E-4 cells typically grew as small cell islands among other epitheloid cells. Amniotic fluid cell cultures occasionally contained also large multinucleated cells (E-5), which appeared to contain large amount of fibrillar keratin. Fibroblastic cells, identified by their decoration only with antibodies against vimentin, were rarely found in amniotic fluid cell cultures. Interestingly, in such cultures some cells with a fibroblastoid appearance were identified as epithelial cells on the basis of the positive keratin-fluorescence. The results show the suitability of IIF with cytoskeletal antibodies in characterization of heterogenous cell populations and indicate that normal amniotic fluid cell cultures mostly contain epithelial cells.

Authors

I Virtanen, H von Koskull, V P Lehto, T Vartio, P Aula

Receptors for insulinlike growth factor I are defective in fibroblasts cultured from a patient with leprechaunism.

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Abstract

We previously have demonstrated that fibroblasts from a patient with leprechaunism exhibited markedly decreased insulin binding to insulin receptors and that the ability of insulin to stimulate glucose incorporation in the patient's cells was greatly impaired. In addition, the insulinlike growth factor, multiplication-stimulating activity (MSA), also exhibited an impaired ability to stimulate glucose incorporation in the patient's fibroblasts, although in normal fibroblasts this response appears to be mediated by an insulinlike growth factor receptor. The present study examines 125I-labeled insulinlike growth factor I (IGF-I) binding to patient's and control fibroblasts. 125I-labeled IGF-I binds to a specific IGF-I receptor in normal fibroblasts. At steady state, binding was inhibited by unlabeled IGF-I, IGF-II, MSA III-2, MSA II, insulin, and proinsulin, in order of potency, but not by high concentrations of epidermal growth factor and human growth hormone, chemically unrelated polypeptides 125I-labeled IGF-I binding to patient's cells was decreased by approximately 75%, whereas binding of epidermal growth factor to its cell surface receptors was unaffected. Computer curve-fitting of untransformed equilibrium binding data suggests that the decreased binding resulted from a decreased Ka for IGF-I. The ability of the patient's IGF-I receptor to recognize insulin also appears to be altered. Impaired IGF-I binding by the leprechaun patient's fibroblasts may contribute to the abnormal biological response to insulinlike growth factors observed in vitro and to the in utero growth retardation.

Authors

E E Van Obberghen-Schilling, M M Rechler, J A Romanus, A B Knight, S P Nissley, R E Humbel

Suppression of atherogenesis in cholesterol-fed rabbit treated with nifedipine.

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Abstract

We tested the effects of nifedipine, a calcium antagonist, on atherogenesis in rabbits fed a 2% cholesterol diet. The drug was given orally, 40 mg/dl, and control rabbits received placebo. Nifedipine was well tolerated, and evoked only transient, moderate reductions in arterial pressure. Plasma total cholesterol after 8 wk before killing the rabbits was similar in the placebo and nifedipine-treated groups, averaging 1,903 +/- 138 (n = 13) and 1,848 +/- 121 mg/dl (n = 13; mean +/- SE; P greater than 0.8). In placebo-treated rabbits, aortic lesions stainable with Sudan IV covered 40 +/- 5% of the intimal surface, and the cholesterol concentration in aortic tissue was 47 +/- 5 mg/g protein. Corresponding values for the aortas from nifedipine-treated rabbits were significantly lower and averaged 17 +/- 3% (P less than 0.001) and 29 +/- 2 mg/g protein (P less than 0.001). We conclude that nifedipine suppressed atherogenesis without reducing hypercholesterolemia.

Authors

P D Henry, K I Bentley

Deficiency of protein C in congenital thrombotic disease.

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Abstract

A family with a history of recurring thrombosis was studied to determine if a plasma protein deficiency could account for the observed disease. Protein C levels in plasma were determined immunologically using the Laurell rocket technique. The propositus, his father, and his paternal uncle, who are severely affected, had 38-49% of normal levels of protein C antigen, whereas unaffected family members had normal levels. There was no familial deficiency of antithrombin III and plasminogen. Because activated protein C is a potent in vitro anticoagulant enzyme and an in vivo profibrinolytic agent, it is suggested that the recurrent thrombotic disease in this family is due to an inherited deficiency in protein C.

Authors

J H Griffin, B Evatt, T S Zimmerman, A J Kleiss, C Wideman

Demonstration that circulating 1 alpha, 25-dihydroxyvitamin D is loosely regulated in normal children.

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Abstract

The effects of vitamin D, 2.5 mg (100,000 U)/d for 4 d, on serum calcium, serum 25-hydroxyvitamin D (25-OHD) and serum 1 alpha, 25-dihydroxyvitamin D (1 alpha, 25(OH)2D) were compared in 24 normal adults and 12 normal children. The daily dose of vitamin D was 1,500 U/kg body wt in children weighing less than 45 kg. Vitamin D increased mean serum calcium from 9.5 +/- 0.1 to 9.8 +/- 0.1 mg/dl (P less than 0.05), increased mean serum phosphorus from 4.6 +/- 0.1 to 5.0 +/- 0.1 mg/dl (P less than 0.01), increased mean serum 25-OHD from 25 +/- 3 to 34 +/- 4 ng/ml (P less than 0.001), and increased mean serum 1 alpha, 25(OH)2D from 34 +/- 3 to 42 +/- 4 pg/ml (P less than 0.02) in children. In contrast, vitamin D increased mean serum 25-OHD from 18 +/- 2 to 39 +/- 6 ng/ml (P less than 0.001) and did not change mean serum calcium (9.4 +/- 0.1 vs. 9.5 +/- 0.1 mg/dl), mean serum phosphorus (4.0 +/- 0.1 vs. 4.1 +/- 0.1 mg/dl), or mean serum 1 alpha, 25(OH)2D (31 +/- 2 vs. 29 +/- 3 pg/ml) in adults. Mean serum 1 alpha, 25(OH)2D was significantly higher after vitamin D in children than in adults (P less than 0.02). These results provide evidence that circulating 1 alpha, 25(OH)2D is not as tightly regulated in children as it is in adults. This difference in regulation could account in part for the higher values for serum 1 alpha, 25(OH)2D observed in children.

Authors

P H Stern, A B Taylor, N H Bell, S Epstein

Immunoglobulin allotypes and immune response to meningococcal group B polysaccharide.

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Abstract

Serum samples were collected from 120 healthy adult volunteers (105 Caucasians and 15 Negros) before and after immunization with meningococcal polysaccharide (MPS) group B vaccine. Antibodies to MPS group B were measured and sera were typed for several Gm and Km(1) allotypes. A significant association was found between the Km(1) allotype and immune response to MPS group B in Caucasians.

Authors

J P Pandey, W D Zollinger, H H Fudenberg, C B Loadholt

Bacterial adhesion in the pathogenesis of infective endocarditis. Effect of subinhibitory antibiotic concentrations on streptococcal adhesion in vitro and the development of endocarditis in rabbits.

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Abstract

Bacterial adhesion to the constituents of nonbacterial thrombotic endocarditis (NBTE) is important in the pathogenesis of endocarditis. Subinhibitory concentrations (subMIC) of some antibiotics decrease bacterial adhesion to epithelial cells in vitro. We utilized an in vitro assay system to study the effect of subMIC of various antibiotics on streptococcal adhesion to a fibrin-platelet matrix (simulating NBTE). The results were (a) bacterial adhesion of Streptococcus sanguis and Streptococcus faecalis to NBTE was significantly reduced by vancomycin, penicillin, tetracycline, chloramphenicol and streptomycin (P less than 0.01 vs. controls) but not rifampin or trimethoprimsulfametrole; (b) the effect was dose-dependent and increased with duration of exposure to antibiotic; (c) reduction in bacterial adhesion did not correlate with altered retention by hydrophobic-interaction chromatography. This reduction in adhesion correlated with a diminished capacity of subMIC exposed Streptococcus sanguis (1/4 vancomycin minimum inhibitory concentration (MIC) X 4 h) to produce endocarditis in vivo. After intravenous inoculation of 10(6) colony-forming units of preincubated organisms into rabbits with traumatized aortic valves, 6 of 22 developed endocarditis vs. 17 of 22 controls (P = 0.03). These results may be relevant to prophylaxis of endocarditis since exposure of bacteria to subMIC of various antibiotics may reduce bacterial adherence both, to mucosal surfaces, and to damaged cardiac valves.

Authors

W M Scheld, O Zak, K Vosbeck, M A Sande