Selected ion monitoring was used to detect tuberculostearic acid (10-methyloctadecanoic acid) in sputum from patients with pulmonary tuberculosis. The specimens were autoclaved, lyophilized, extracted, and methanolysed before being subjected to thin-layer chromatography and injected into the gas chromatograph/mass spectrometer. Tuberculostearic acid could be detected in five of six tuberculous sputum specimens containing acid-fast rods detectable by light microscopy of Ziehl-Neelsen stained smears. After the sputum specimens had been cultured for five days on Löwenstein-Jensen medium, when still no colonies could be observed visually, the presence of tuberculostearic acid was demonstrated in all six cases of tuberculosis. In corresponding analyses of sputum from eight patients with non-tuberculous pneumonia, tuberculostearic acid was not found. This fatty acid, the presence of which was also demonstrated in cultures of various mycobacterial and nocardial species, is characteristic of organisms of the order Actinomycetales. The demonstration of tuberculostearic acid in sputum specimens may constitute a rapid and sensitive way of diagnosing pulmonary tuberculosis.
Glucogon immunoreactivity (IRG) was measured in plasma of duodenopancreatectomized subjects with a nonspecific (K-4023) and a specific (30-K) glucagon antiserum. After an overnight fast, plasma IRG (K-4023) was significantly (P < 0.05) higher in the subjects without pancreas, averaging 782±79 (SEM) pgeq/ml, than in the controls (482±80 pgeq/ml). IRG (30-K) of 162±68 pg/ml did not change during an infusion of arginine (450 mg/kg per 40 min). Insulin deprivation during 3 d in one patient did not restore the IRG response to arginine as reported in depancreatized dogs.
We examined the vaginal washings from patients with nonspecific vaginitis (NSV) to seek biochemical markers and possible explanations for the signs and symptoms of this syndrome. Seven amines were identified including methylamine, isobutylamine, putrescine, cadaverine, histamine, tyramine, and phenethylamine. These amines may contribute to the symptoms of NSV and may contribute to the elevated pH of the vaginal discharge. They may also be partly responsible for the "fishy" odor that is characteristic of vaginal discharges from these patients. Among the seven amines, putrescine and cadaverine were the most abundant and were present in all vaginal discharges from each of ten patients before treatment. These amines are produced in vitro during growth of mixed vaginal bacteria in chemically defined medium, presumably by decarboxylation of the corresponding amino acids. We hypothesize the anaerobic vaginal organisms, previously shown to be quantitatively increased in NSV, are responsible for the amine production, because metronidazole inhibited the production of amines by vaginal bacteria in vitro, and Haemophilus vaginalis did not produce amines. H. vaginalis did release high concentrations of pyruvic acid and of amino acids during growth in peptone-starch-dextrose medium, whereas, other vaginal flora consumed both pyruvic acid and amino acids in the same medium during growth. These findings suggest that a symbiotic relationship may exist between H. vaginalis and other vaginal flora in patients with NSV.
A noncovalent complex of meningococcal group B polysaccharide and type 2 outer membrane protein has been characterized and its potential as a vaccine against group B meningococcal disease investigated. The polysaccharide component was found to have a partition coefficient, Kd, of 0.34 on Sepharose CL-4B in the presence of sodium deoxycholate. The protein consisted of four to five major proteins including the principal outer membrane protein. Hydrophobic binding between the protein and polysaccharide was demonstrated by gel filtration and isopycnic CsCl density gradient centrifugation and found to involve all of the proteins. After demonstrating safety and immunogenicity in animals, two lots of vaccine were tested in a total of eight volunteers. Two 120-μg doses were given subcutaneously at 0 and 5 wk. Mild local reactions occurred in all eight volunteers, but no systemic reactions were observed. 2 wk after the first dose, six of the volunteers had increased levels of bactericidal antibodies against both the group B polysaccharide and the outer membrane proteins. Antibody rises to the group B polysaccharide (mean 6-fold) were confirmed by passive hemagglutination assays and rises to the proteins (mean 10-fold) by a solid phase radioimmunoassay. The second dose resulted in little or no increase in antibody titers. Antibody titers declined over a period of 14 wk but mostly remained above preimmunization levels. Bactericidal antibodies with specificity for the group B polysaccharide were mostly of the immunoglobulin (Ig)M class, and were directed against a determinant associated only with high molecular weight polysaccharides. We conclude that both the group B polysaccharide and the outer membrane protein are immunogenic in man when presented as a complex and that the complex warrants further testing and development as a vaccine against group B meningococcal disease.
The effects of continuous infusions of insulin in physiologic doses on glucose kinetics and circulating counterregulatory hormones (epinephrine, norepinephrine, glucagon, cortisol, and growth hormone) were determined in normal subjects and diabetics. The normals received insulin at two dose levels (0.4 and 0.25 mU/kg per min) and the diabetics received the higher dose (0.4 mU/kg per min) only.
This report describes the effects of pharmacologic doses (3 g/d) of nicotinic acid on the plasma distribution and chemical composition of the high density lipoprotein (HDL) subfractions HDL2 and HDL3 and examines the influence of the drug on the metabolism of the major HDL apoproteins, apolipoproteins A-I (ApoA-I) and A-II (Apo-II).
A plaque assay that detects human mononuclear blood cells producing immunoglobulin (Ig)M antibody to sheep erythrocytes was investigated for its usefulness in studying B-cell activation and regulation in 24 patients with humoral immunodeficiency. Cells from 3 of 15 patients with common variable agammaglobulinemia produced some plaques (range 40--160/10(6) cells; normal range 80--1240/10(6)), but those from the other 12, from all 7 with x-linked agammaglobulinemia and from the 2 with x-linked immunodeficiency with hyper-IgM failed to produce any detectable plaques. In co-cultures of patient and normal cells a very good correlation was seen between results of the plaque assay and an IgM biosynthesis assay in detecting excessive suppressor cell activity. Cells from 7 of 15 common variable agammaglobulinemics, from 3 of 7 x-linked agammaglobulinemics, and from both patients with hyper-IgM caused significant suppression of IgM biosynthesis and(or) plaque formation by normal cells. The observations in the last two groups and discordance for excess suppressor activity in identical twins with common variable agammaglobulinemia suggest that the activity develops secondarily to whatever their primary defects may be. Culturing non-T cells from common variable agammaglobulinemics exhibiting excessive suppressor cell activity with normal T cells resulted in plaque formation in four of five patients so studied; in all five the suppressor activity was found in the T-cell population. The availability of a plaque assay for the study of blood cells from immunodeficient patients provides a new probe to examine the cellular nature of such defects.
α2-Plasmin inhibitor (α2PI) is a recently characterized, fast-reacting plasmin inhibitor in human plasma that appears to play an important role in regulation of in vivo fibrinolysis. We report here a case of complete deficiency of α2PI in man. The patient, a 25-yr-old Japanese man, had a life-long severe bleeding tendency (hemarthrosis and excessive bleeding after trauma). The following tests were within normal limits: platelet count, bleeding time, thrombin time, prothrombin time, partial thromboplastin time, titers of known clotting factors, platelet glass bead retention, Factor VIII-related antigen, platelet aggregation by ADP, collagen and ristocetin, and clot retraction. Routine liver function tests were also normal. The only abnormal finding was that whole blood clot lysis was extemely rapid and was complete in 4-8 h. The concentration of plasma protease inhibitors, including α2-macro-globulin, antithrombin III, α1-antitrypsin, and C1̄INH, were all normal. The concentration of α2-PI in the patient's plasma, assayed by immunological methods, was <0.1 mg/100 ml (normal concentration, 6.1±0.88 mg/100 ml [mean±SE]) and functional assays showed a complete deficiency of α2PI. Addition of purified α2PI to the patient's whole blood completely corrected the accelerated fibrinolysis. The patient's parents, four siblings, and four other members of this family were asymptomatic, but the titers of α2PI in their plasmas were ≅50% of normal pooled plasma. There were three consanguineous marriages in this family, and the α2PI deficiency appears to have been inherited as an autosomal recessive trait. We speculate that α2PI deficiency in this patient has led to uninhibited in vivo fibrinolysis that probably causes the severe hemorrhagic tendency. Thus, this study indicates the important role of α2PI in hemostasis.
Peripheral blood mononuclear cells from 46 systemic lupus erythematosus (SLE) patients showed reduced ability to proliferate in vitro in response to the soluble antigen, tetanus toxoid, as compared with 96 normal controls. Special studies of 27 untreated SLE patients also revealed significantly decreased blastogenic responses to tetanus toxoid. In both the total and untreated SLE populations, decreased mean tetanus antibody titers also were found as compared with the control population. However, the reduction in antibody titer and blastogenic response was not strictly parallel. A limited immunization program was initiated in low-responding volunteers from the SLE and normal populations. Three out of four SLE patients did not develop a significant blastogenic response despite increases in anti-tetanus titers after immunization, whereas all normals showed significant increases in both blastogenic and antibody responses. The accumulated evidence indicated that the unresponsiveness was the result of a defect in T-cell function. Monocyte reactivity was demonstrated to be normal, and no evidence was found for the presence of suppressor cells, inhibition by immune complexes, or increased prostaglandins to explain the defect.
This report correlates the survival time of 93 intrafamilial skin allografts performed under conditions of main histocompatibility complex (HLA) haploidentity with donor-recipient compatibility for products of the HLA-A, -B, -C, and -DR, as well as C3 proactivator, Glyoxalase I, and P loci located on the human 6th chromosome. Incompatibilities for HLA-A and -B (and to a lesser extent for HLA-C) and(or) for HLA-DR products exerted a strong influence upon the fate of skin allografts. When HLA-A and -B were considered alone, the most compatible group of grafts had a mean survival time of 15.8 d, as compared with 11.3 d for the most incompatible transplants. HLA-DR compatibility alone was associated with a mean survival time of 15.3 d, whereas HLA-DR-incompatible grafts had a mean survival time of 11.5 d. Incompatibilities for C3 proactivator, Glyoxalase I, and P did not have a significant effect upon graft survival.
Female NZB/NZW F1 mice were treated as adults with 5-alpha-dihydrotestosterone powder packed into subcutaneous implants. Two treatment protocols were followed: (a) 3-mo-old mice received 6 mg of androgen, and (b) 6-mo-old mice were castrated and given 12 mg of androgen. Sham females received empty implants. Mice were followed monthly for surival, for antibodies to DNA and polyadenylic acid, and for renal histopathology. The percent survival at 11 mo was 74% for mice treated at 3 mo, compared to 11% for the sham controls, and 100% for mice treated at 6 mo, compared to 20% for their sham controls. Androgen-treated mice had less immune complex glomerulonephritis as determined by immunofluorescent and electron microscopy. Surprisingly, treated mice had no significant sustained reduction in antibodies to DNA although they had reduced antibodies to polyadenylic acid. These results suggest that androgens can still prolong survival and reduce immune complex deposition even when treatment is delayed to an age when disease is relatively established. After delayed androgen treatment, mice survive despite the presence of high levels of IgG antibodies to DNA.
The serum bactericidal activity (SBA) of cirrhotic patients was compared with that of normal individuals using the release of 51Cr from radiolabeled Escherichia coli as the assay method. 80% (22/27) of patients were found to have deficient SBA against at least one of three smooth, serum-sensitive test strains of E. coli. Cirrhotic patients were found to have normal levels of serum lysozyme. Although some patients were mildly hypocomplementemic, this abnormality did not correlate with the presence of a bactericidal defect. Bactericidal antibody in normal and cirrhotics' sera was limited to the immunoglobulin (Ig)M class. Purified IgM from patients with deficient SBA against E. coli 0111 had lower concentrations of bactericidal antibody for that E. coli than did IgM from normal sera; the calculated bactericidal activity of total serum IgM was also lower. The bactericidal defect in cirrhotic serum could be completely corrected by either human antiserum to the homologous strain of E. coli or by purified, normal human IgM. However, because higher concentrations of IgM were required to restore normal SBA to a cirrhotic's serum than to agammaglobulinemic serum, there may be an inhibitor of bactericidal antibody in addition to a deficiency of bactericidal IgM antibody to E. coli in the serum of patients with cirrhosis. The bactericidal activity of the alternative complement pathway was also assessed. Sera from cirrhotic patients had no deficit in SBA attributable to the alternative complement pathway. In fact, in some, the activity of the alternative complement pathway was supernormal, compensating in part for the deficit in IgM-mediated SBA.
Hemoglobin (Hb) Indianapolis is an extremely labile beta-chain variant, present in such small amounts that it was undetectable by usual techniques. Clinically, it produces the phenotype of severe beta-thalassemia. Biosynthetic studies showed a beta:alpha ratio of 0.5 in reticulocytes and about 1.0 in marrow after a 1-h incubation. These results, similar to those seen in typical heterozygous beta-thalassemia, suggested that betaIndianapolis was destroyed so rapidly that its net synthesis was essentially zero. To examine the kinetics of globin synthesis, reticulocyte incubations of 1.25--20 min were performed with [3H]leucine. The betaIndianapolis:beta A ratio at 1.25 min was 0.80 suggesting that beta Indianapolis was synthesized at a near normal rate. At 20 min, this ratio was 0.46 reflecting rapid turnover of beta Indianapolis. The erythrocyte ghosts from these incubations contained only betaIndianapolis and alpha-chains, and the proportion of betaIndianapolis decreased with time, indicating loss of betaIndianapolis. Pulse-chase studies showed little change in beta A:alpha ratio and decreasing betaIndianapolis:alpha and betaIndianapolis:beta A with time. The half-life of betaIndianapolis in the soluble hemoglobin was approximately equal to 7 min. There was also rapid loss of beta Indianapolis from the erythrocyte membrane. From these results, it may be inferred that betaIndianapolis is rapidly precipitated from the soluble cell phase to the membrane, where it is catabolized. Heterozygotes for beta 0-thalassemia usually have minimal hematologic abnormalities, whereas heterozygotes with betaIndianapolis, having a similar net content of beta-chain, have severe disease. The extremely rapid precipitation and catabolism of betaIndianapolis and the resulting excess of alpha-chains, both causing membrane damage, may be responsible for the severe clinical manifestations associated with this variant. It seems likely that other, similar disturbances in the primary sequence of globin polypeptide chains may produce clinical findings similar to those seen with hemoglobin Indianapolis and thus produce the phenotype of severe beta-thalassemia.
Tissue sensitive to insulin and insulin binding to monocytes were evaluated in 15 nonobese maturity-onset diabetics and in 16 healthy controls. Insulin sensitivity was determined by the insulin clamp technique in which the plasma insulin is acutely raised and maintained 100 μU/ml above the fasting level and plasma glucose is held constant at fasting levels by a variable glucose infusion. The amount of glucose infused is a measure of overall tissue sensitivity to insulin.
Chronically instrumented awake dogs were used to study the effects of nitroglycerin and propranolol on the transmural distribution of myocardial blood flow during transient ischemia. Studies were carried out 7-14 d after implantation of an electromagnetic flowmeter probe and balloon occluder on the left circumflex coronary artery, placement of epicardial minor axis sonar crystals, and implantation of left atrial, left ventricular, and aortic catheters. The occluder was inflated to completely interrupt flow for 10 s followed by partial release to reestablish flow at 60% of the preocclusion level. During this partial release, which served as the control for the study, regional myocardial blood flow was measured with 7- to 10-μm radioactive microspheres. After control measurements, seven dogs were given nitroglycerin (0.4 mg i.v.) and eight dogs propranolol (0.2 mg/kg i.v.). 5 min later the occlusion and partial release sequence was repeated, and regional myocardial blood flow was measured when heart rate, aortic and left ventricular end-diastolic pressure, and minor axis diameter were unchanged from control values.
Endothelial cells in tissue culture degrade bradykinin and convert angiotensin I to angiotensin II. These are both functions of a single dipeptidyl hydrolase, angiotensin converting enzyme. Monolayer cultures were prepared from human, rabbit, pig, and calf vessels. Angiotensin converting enzyme activity was assessed by adding either bradykinin or angiotensin I to the cells in culture flasks, and measuring residual peptide over time by radioimmunoassay. Peptide degradation was inhibited by the specific converting enzyme inhibitor, SQ 20881. The flasks were equilibrated with varying hypoxic gas mixtures: hypoxia rapidly (less than 2 min) decreased enzyme activity and room air restored it as rapidly. The extent to which activity was reduced was a direct function of PO2 (r = 0.93, P less than 0.001), and there was no enzyme activity below a PO2 of 30 mm Hg. Four preparations were studied with respect to decrease in enzyme activity by hypoxia: (a) intact cells in monolayer, (b) sonicated cells, (c) sonicated cells from which converting enzyme was partially dissolved by a detergent, and (d) purified converting enzyme. Hypoxia had progressively less of an inhibiting effect on the enzyme activity of the preparations as the degree of cell integrity decreased. Hypoxia inhibits angiotensin converting enzyme activity in cultured endothelial cells, but the effect of hypoxia is not on the enzyme per se, but appears to be a unique characteristic of the endothelial cell.
Human macrophages, derived from peripheral blood monocytes, acquire enhanced cytotoxicity for human target cells after incubation in mediator-rich supernates from antigen-stimulated lymphocytes. Maximum cytotoxicity was observed after 24-h incubation in mediators. In comparison to normal macrophages, mediator-activated macrophages were cytotoxic to five of the six malignant cell lines tested but had no effect on five nonmalignant cell lines. In 20 experiments with one target (SK-BR-3), mean cytotoxicity was 23 +/- 2.7% and with another target (MA-160), was 29 +/- 3.4%. Macrophages became cytotoxic after 8-h incubation with mediators and the enhanced cytotoxicity persisted for at least 40 h after the lymphocyte mediators were removed. These findings are consistent with the hypothesis that macrophages, activated by antigen-induced lymphocyte mediators, can contribute to the host resistance to tumor growth in man.
Acid infusion studies were performed in nephrectomized rats and dogs with either intact parathyroid glands (intact) or after thyroparathyroidectomy (thyroparathyroidectomized [TPTX]) to determine the role of parathyroid hormone (PTH) in extrarenal disposal and buffering of acutely administered acid. 29 intact rats given 5 mM/kg HCl and 6 intact dogs given 7 mM/kg HCl developed severe metabolic acidosis but all survived. However, each of 12 TPTX rats and 4 TPTX dogs given the same acid loads died. Intact rats and dogs buffered 39 and 50% of administered acid extracellularly, respectively, whereas extracellular buffering of administered acid was 97 and 78% in TPTX rats and dogs, respectively. 17 TPTX rats and 6 TPTX dogs given synthetic PTH 2 h before acid infusion survived. The blood bicarbonate and extracellular buffering in these animals, measured 2 h after acid infusion, was similar to intact animals. Changes in liver, heart, and skeletal muscle pH determined from [14C]5,5-dimethyl-2,4 oxazolidinedione distribution seemed insufficient to account for the increased cell buffering of PTH-replaced animals. Indeed, muscle pH in TPTX dogs given PTH and acid was only 0.06 pH units lower than in control dogs given no acid, suggesting that another tissue, presumably bone, was the target for PTH-mediated increased cell buffering. This conclusion was supported by the observation that PTH did not alter the pH of intact rat diaphragms in vitro. These results indicate that PTH is necessary for the optimal buffering of large, acute acid loads presumably by increasing bone buffering.
The possibility that surface tension may affect the hydrostatic transmural pressure of pulmonary vessels and the development of pulmonary edema was studied in anesthetized, open-chested dogs. Isogravimetric pressure (the static intravascular pressure at which transmural osmotic and hydrostatic pressures are balanced such that net fluid flux is zero and lung weight is constant) was measured in nine animals under three conditions: (a) control, normal surface tension, at an alveolar pressure of 30 cm H2O with the apenic lung at room temperature; (b) after increasing surface tension by cooling and ventilating at a low functional residual capacity, at an alveolar pressure sufficient to produce the same lung volume present during control measurements; and (c) after restoring surface tension by rewarming while holding the lung at a high inflation volume, again at the control lung volume. Lung volumes were established from external dimensions and confirmed +/- 10% by deflation spirometry. The isogravimetric pressure (relative to alveolar pressure) was significantly less with increased surface tension than during either the initial control condition (P less than 0.01), or when the surface tension has been restored (P less than 0.01). Similar changes occurred in each of three additional studies performed with control alveolar pressures of 10 cm H2O. Thus, increased surface tension favors fluid leakage presumably because it increases the microvascular transmural pressure.
The effect of hydrocortisone on thrombocytopenic bleeding has been studied in rabbits using a jugular vein bleeding-time technique and a microvascular bleeding-time technique. An inverse relationship was found between the bleeding time and platelet count with both techniques in rabbits made thrombocytopenic by either X-irradiation or injection of heterologous platelet antiserum. Hydrocortisone shortened both bleeding times in thrombocytopenic animals when given in single large doses intravenously (25-100 mg/kg), in daily doses (6 mg/kg) intramuscularly, and shortened the jugular bleeding time when applied to the outside of the jugular vein or instilled intraluminally into the vein. This effect was also noted in normal animals. The effect on thrombocytopenic bleeding was dose related. When given daily, the effect was greater when hydrocortisone was given for 10 d than for 5 d. Both indomethacin and tranylcypromine also reduced the jugular vein bleeding time when instilled intraluminally into the jugular vein, whereas exogenously provided arachidonic acid reversed the effect of hydrocortisone but did not reverse the effect of indomethacin or tranylcypromine. Exogenously provided linoleic acid did not have any effect. Perfusion of the vessel segment with prostacyclin (PGI2) reversed the effect of intraluminally administered hydrocortisone, indomethacin, and tranylcypromine. Similarly, hydrocortisone, indomethacin, and tranylcypromine all reduced the rate of loss of fluid from a standard wound in isolated vessels emptied of blood and perfused with saline under constant pressure. PGI2 reversed the action of these three agents, however, arachidonic acid reversed only the effect of hydrocortisone and did not reverse the effect of indomethacin and tranylcypromine. The generation of PGI2-like material and 6-keto-prostaglandinF1 α from jugular vein strips was prevented by prior exposure of the animals or vessel wall to hydrocortisone. These results are compatible with the hypothesis that the vessel wall releases smooth muscle-relaxing prostaglandins when injured and that inhibition of prostaglandin formation by hydrocortisone enhances hemostasis by allowing vasoconstriction to be maintained.
Rapid pull-through pressure profiles of the normal human upper esophageal sphincter (UES) were simultaneously studied with a conventional three-orifice Honeywell solid-state probe, an eight lumen radially perfused (RP) probe, and a circumferentially sensitive (CS) probe designed to measure UES pressure (UESP) without regard to probe orientation. Pressure curves were digitized and analyzed by computer. The Honeywell probe recorded significantly lower peak pressures than the other two methods, and had wide intrasubject pressure variations (average coefficient of variation, 53%). In contrast, UESP measured with the CS probe was constant for each subject (mean peak UESP, 121 mm Hg; average coefficient of variation, 15%). Anteroposterior RP probe UESP were identical to CS probe pressures. Thus, peak perfused anteroposterior UESP correlates with circumferentially measured sphincter squeeze.
Taurocholate concentrations in fetal and neonatal rats were determined by radioimmunoassay. Total body taurocholate pool size varied from 0.0049 +/- 0.0008 to 203 +/- 8 nmol/g body weight from day 5 of gestation to 5 d after birth. A 50-fold increase in taurocholate pool size was observed between days 15 and 19 of gestation. The distribution of taurocholate between liver, intestine, and the remainder of the carcass was determined for rats of gestational age 19 d to 5 d after birth. The major fraction of total body taurocholate was in the liver and intestine, with less than 15% in the remainder of the carcass. The ratio of taurocholate in intestine to taurocholate in liver, which was 1:17 at 19 d of gestation, had altered substantially to a ratio of 6:1 by 5 d after birth. Treatment of pregnant rats with 60 microgram/d of dexamethasone from gestational day 9 until sacrifice increased fetal taurocholate pool size by 80% at 15 d, 40% at 19 d, and 16% at 1 d after birth. Administration of dexamethasone to the mother also changed the ratio of taurocholate in intestine to taurocholate in liver. At 19 d of gestation, dexamethasone-treated mothers had fetuses with approximately equal amounts of taurocholate in intestine and liver. This suggested that adrenocorticosteroids stimulate the early maturation of factors controlling taurocholate pool size and tissue distribution in the rat fetus.
Five patients with fasting and(or) postprandial hypoglycemia were found to have insulin antibodies in the absence of previously documented immunization. Studies on the equilibrium-binding of insulin to the autoantibodies revealed two classes of binding sites with association constants and binding capacities analogous to those of insulin antibodies from insulin-treated diabetic patients. Similarly, no consistent differences in these parameters were found in both groups of patients with insulins of bovine, porcine, and human origin. Proinsulin (C-segment directed) antibodies capable of binding bovine or porcine proinsulin were present in 10 of 10 and 9 of 10 insulin-treated diabetics serving as controls, respectively, and, when present, provide incontrovertible evidence of exogenous insulin administration. No such antibodies could be detected in the hypoglycemic patients with autoimmune insulin antibodies. The kinetics of dissociation of the insulin-antibody complexes were consistent with the existence of two classes of antibody sites. The corresponding dissociation rate constants were large enough to predict that significant amounts of free hormone may be generated by this mechanism and provide a plausible pathogenesis for the hypoglycemia in these patients.
Recently, evidence has been reported to suggest that human platelets like several other circulating blood cells may bind insulin. To examine whether human platelets contain specific insulin receptors, washed human platelets suspended in Hepes buffer were incubated at 24 degrees C with 125I-insulin in the presence and absence of unlabeled insulin and specific insulin binding was determined. Insulin binding by platelets increased progressively with time of incubation to reach a maximum at 3 h and was proportional to the number of platelets in the incubation mixture. Maximum insulin binding was observed at pH 8. Insulin degradation by platelets as assessed by TCA precipitability and reincubation studies was minimal. Scatchard analysis of the binding data and dissociation studies revealed evidence of negative cooperativity of the platelet insulin receptor. A high affinity dissociation constant of approximately equal to 3 X 10(9) M-1 was determined and the concentration of platelet insulin receptors was estimated as 25 binding sites/micron2 platelet surface area. Binding of 125I-insulin by platelets was inhibited by unlabeled porcine insulin and to a lesser extent by catfish insulin and porcine proinsulin but not by glucagon, prolactin, growth hormone, and thrombin. The findings indicate that human platelets contain specific insulin receptors. The significance of the platelet insulin receptor, particularly with respect to altered platelet function in diabetes mellitus, remains to be determined.
The binding of purified human erythrocyte AMP deaminase to human erythrocyte membranes and the effect of binding on enzyme catalytic activity was investigated. AMP deaminase binds preferentially and specifically to the cytoplasmic surface of the erythrocyte membrane. The binding is saturable, reversible, and responsive to alterations of pH, of ionic strength, and of ATP and AMP concentrations. A limited number (approximately equal to 2.2 X 10(4) per erythrocyte) of apparently homogeneous high affinity (Ka approximately equal to 2.6 X 10(7) M-1) binding sites is present. The stability of purified and endogenously bound AMP deaminase is markedly improved by the interaction with the membrane, whereas the catalytic activity of AMP deaminase is sharply reduced. AMP deaminase displaces membrane bound glyceraldehyde 3-phosphate dehydrogenase in roughly a dose-response manner. No evidence for binding of AMP deaminase to spectrin or band 3 (the G3PD binding protein) was found in sucrose gradients, however. The interaction of AMP deaminase with the erythrocyte membrane may play an important role in the regulation of cellular adenine nucleotide metabolism.
Nonsuppressible insulin-like activity extracted and purified from human serum (NSILA-S) mimics all insulin-like effects in vitro and, after injection, in vivo in the presence of excess insulin antibodies. However, there is no evidence that it exerts acute insulin-like effects in its native form in the circulation, where it is almost completely bound to a specific large molecular weight carrier protein. In this paper we show that partially purified NSILA-S-carrier protein, devoid of endogenous insulin-like activity, inhibits the stimulatory effect of NSILA-S, but not of insulin, on 3-0-methylglucose transport and on lipogenesis from [U-14C]glucose in isolated rat fat cells. Concomitantly, it prevents binding of 125I-labeled NSILA-S to the insulin receptor and to the NSILA-S-binding site.
Peripheral blood lymphocytes from 38 patients with autoimmune thrombocytopenic purpura (AITP) were tested for HLA-A, -B, and -C alloantigens. Isolated B lymphocytes from 20 of these patients were tested for HLA-DRw (Ia) alloantigens. The profile of HLA alloantigens in the patients with AITP was significantly different from that of a matched control population. The most significant finding was the presence of the HLA-DRw2 alloantigen in 75% of patients as compared with 23% in the control population, P less than 0.001, relative risk 10.0 (A relative risk of 1 would indicate no association between the presence of the antigen and the disease.) The co-occurrence of either A3 and B7 (known to be in linkage disequilibrium with DRw2) or A26 and Bw38 was significantly increased as compared with the control population (P less than 0.001). Of the patients positive for DRw2, 47% had the association A26 and Bw38 as compared with the control population association incidence of 21% (P less than 0.1). Thus, in the patient population, A26-Bw38 appears to be a haplotype that is in linkage disequilibrium with DRw2 (as presumably is the case with A3-B7). These data indicate that a predisposition to AITP is inherited with a DRw2 gene of the major histocompatibility system.
Aspirin treatment of cultured endothelial cells from the umbilical vein increased the adherence of 51Cr-platelets when thrombin was present. If the cyclooxygenase activity of endothelium was inhibited by aspirin, as it is in the platelet, reduction of endogenous prostacyclin (PGI2) production could have been responsible. By correlating thrombin-induced adherence of platelets to endothelial monolayers with PGI2 release (as measured by radioimmunoassay for 6-keto-prostaglandin FI1 alpha [6-keto-PGF1 alpha]), we have demonstrated an inverse relationship between platelet adherence and PGI2 levels. Untreated endothelial monolayers exposed to thrombin and platelets resulted in 4% platelet adherence and 107 nM 6-keto-PGF1 alpha. With 0.1 mM aspirin treatment, which is known to block platelet cyclooxygenase, adherence was 5% and 6-keto-PGF1 alpha decreased to 45 nM. Increasing the aspirin concentration to 1 mM resulted in 44% adherence and less than 3 nM 6-keto-PGF1 alpha. When 25 nM exogenous PGI2 was added to 1 mM aspirin-treated endothelium, adherence returned to 5%. The increase in thrombin-induced platelet adherence to 1 mM aspirin-treated monolayers was reversed 2 h after removal of the aspirin solution. 6-Keto-PGF1 alpha returned to 37% of the untreated monolayer value. Recovery from the aspirin effect did not occur when cycloheximide, an inhibitor of protein synthesis, was present during the 2-h period.
The contribution of reduced purine salvage to the hyperuricemia associated with hypoxanthine-guanine phosphoribosyltransferase deficiency was measured by the intravenous administration of tracer doses of [8-14C]adenine to nine patients with normal enzyme activity, three patients with a partial deficiency of hypoxanthine-guanine phosphoribosyltransferase, and six patients with the Lesch-Nyhan syndrome. The mean cumulative excretion of radioactivity 7 d after the adenine administration is 5.6±2.4, 12.9±0.9, and 22.3±4.7% of infused radioactivity for control subjects, partial hypoxanthine-guanine phosphoribosyltransferase-deficient subjects, and Lesch-Nyhan patients, respectively. To assess relative rates of nucleotide degradation in control and hypoxanthine-guanine phosphoribosyltransferase-deficient patients two separate studies were employed. With [8-14C]inosine administration, three control subjects excreted 3.7-8.5% and two enzyme-deficient patients excreted 26.5-48.0% of the injected radioactivity in 18 h. The capacity of the nucleotide catabolic pathway to accelerate in response to d-fructose was evaluated in control and enzyme-deficient patients. The normal metabolic response to intravenous fructose is a 7.5±4.2-mmol/g creatinine increase in total urinary purines during the 3-h after the infusion. The partial hypoxanthine-guanine phosphoribosyltransferase-deficient subjects and Lesch-Nyhan patients show increases of 18.6±10.8 and 17.3±11.8 mmol/g creatinine, respectively. Of the observed rise in purine exretion in control subjects, 40% occurs from inosine excretion and 32% occurs from oxypurine excretion. The rise in total purine excretion with Lesch-Nyhan syndrome is almost entirely accounted for by an elevated uric acid excretion. Increases in urine radioactivity after fructose infusion are distributed in those purines that are excreted in elevated quantities.
Patients with systemic lupus erythematosus (SLE) produce excessive amounts of autoantibodies. It has also been demonstrated in several systems that such patients have a relative loss of suppressor thymus-derived (T) cells that inhibit the immune response. This loss of suppressor cells has been suggested as one of the causes of the excessive production of antibodies in patients with SLE.
A human neutrophil neutral protease which generates a low molecular weight peptide from a plasma protein substrate and cleaves the basic amino acid ester substrates α-N-p-tosyl-l-arginine methyl ester HCl, α-N-benzoyl-l-arginine-methyl ester HCl, and α-N-carbobenzoxy-l-lysine-p-nitrophenyl ester has been purified to homogeneity and distinguished from the known lysosomal neutrophil proteases. The starting activity was obtained from purified human neutrophils by homogenization, sedimentation by low-speed centrifugation, and high salt elution of the insoluble material. Purification was achieved by aprotinin-affinity chromatography, precipitation at low ionic strength, and gel filtration. The overall recovery, relative to the activity in the starting eluate of the neutrophil fraction, was ≅50% with a 200- to 400-fold increase in specific activity. After treatment with diisopropylfluorophosphate to eliminate autodegradation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of reduced and unreduced protein gave a single protein band of 29,000-30,000 mol wt. The isoelectric point determined in sucrose gradients ranged from pH 7.8 to 8.3 with a peak at pH 8.0. This neutrophil protease, like cathepsin G and elastase, is composed of a single polypeptide chain of ≅30,000 mol wt, but differs from cathepsin G and elastase in its less cationic isoelectric point and its failure to cleave synthetic substrates presenting an aromatic amino acid ester linkage and alanyl peptide bonds, respectively.
Because human platelets participate in the contact phase of intrinsic coagulation and contain a Factor XI-like coagulant activity, the nature of the Factor XI-like activity was examined and compared with purified plasma Factor XI. The platelet factor XI-like activity was sedimented with the particulate fraction of a platelet lysate, was inactivated by heat (t1/2 3.5 min, 56°C), was not a nonspecific phospholipid activity, and was destroyed by treatment with Triton X-100. Isolated platelet membranes were four-fold enriched in Factor XI activity and similarly enriched in plasma membrane marker enzymes. The Factor XI-like activity of platelet membranes was detected only when assayed in the presence of kaolin, which suggests that it is present in an unactivated form and can participate in contact activation. Concanavalin A inhibited the Factor XI-like activity of platelet lysates and platelet membranes but not of plasma or purified Factor XI. A platelet membrane-Factor XI complex was isolated after incubation of membranes with purified Factor XI. The Factor XI activity of the platelet membrane-plasma Factor XI complex was inhibited by concanavalin A, whereas unbound plasma Factor XI retained activity. An antibody raised against plasma Factor XI inhibited the in vitro Factor XI activity of plasma and of the platelet membrane-plasma Factor XI complex but had no effect on the endogenous Factor XI-like activity of washed lysed platelets or isolated platelet membranes. Washed platelets and isolated platelet membranes obtained from a Factor XI-deficient donor without a history of excessive bleeding had normal quantities of platelet Factor XI-like activity and normal behavior in the contact phase of coagulation (collagen-induced coagulant activity). These results indicate that platelet membranes contain an endogenous Factor XI-like activity that is functionally distinct from plasma Factor XI.
We have studied the distribution of folate coenzyme forms in cultured human fibroblasts from control lines and from lines derived from nine patients representing all of the published reports of 5,10-CH2-H4PteGlu reductase deficiency. Based on mobility on DEAE-Sephadex and differential microbiological assay the major folate fractions in extracts of human fibroblasts were 5-CH3-H4PteGlu, 10-CHO-H4PteGlu, and 5-CHO-H4PteGlu with smaller fractions, which included 5-CH3-H2PteGlu, 10-CHO-PteGlu, and H4PteGlu. Evidence that the 5-CHO-H4PteGlu may have been derived from 5,10-CH=H4PteGlu during extraction is presented. In most of the mutant fibroblasts the absolute concentration of 5-CH3-H4PteGlu was lower than in control cells but the proportion of intracellular folate which was 5-CH3-H4PteGlu was strikingly lower in mutant cells when determined by chromatography or differential microbiological assay. In both control and mutant cells most of the 5-CH3-H4-PteGlu was polyglutamate. The proportion of intracellular folate which was polyglutamate was similar in control and mutant cells. A direct relationship was observed between the proportion of cellular folate which was 5-CH3-H4PteGlu, and both the clinical severity of this disorder and the residual enzyme activity indicating that the distribution of different folates may be an important control of intracellular folate metabolism. These studies indicate that 5,10-CH2-H4PteGlu reductase is the only significant intracellular pathway for the generation of 5-CH3-H4PteGlu, that the activity of this enzyme regulates the level of this folate in control and mutant cells under conditions of culture used here, that the majority of intracellular folate is in the polyglutamate form, and that the relative distribution of folates may control folate metabolism by interaction in the various folate reactions.
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