Issue published June 1, 1987

T he possibility that corticosteroid cytotoxicity could be mediated by activation of poly(ADP-ribose) polymerase and consequent depletion of NAD and ATP was evaluated in steroid-sensitive S49.1 and steroid-resistant S49.143R mouse lymphoma cells and in lymphocytes from a patient with chronic lymphocytic leukemia. All cell types were shown to have the enzyme poly(ADP-ribose) polymerase and to increase activity in response to DNA strand breaks. Incubation of susceptible cells with 1 microM dexamethasone resulted in DNA strand breaks. Susceptible cells also showed a dose-dependent decrease in NAD and ATP that preceded loss of cell viability. These studies suggest that steroid-induced cytotoxicity in susceptible lymphocytes is due to the presence of DNA strand breaks that activate poly(ADP-ribose) polymerase to a sufficient degree to consume cellular pools of NAD with a consequent depletion of ATP and loss of cell viability.

I n response to global ischemia, tissue xanthine dehydrogenase was converted to xanthine oxidase in all tissues with half-times of conversion at 37 degrees C of approximately 3.6, 6, 7, and 14 h for the liver, kidney, heart, and lung, respectively. The time course of enzyme conversion at 4 degrees C was greatly extended with half-conversion times of 6, 5, 5, and 6 d for the respective tissues. Increases in xanthine oxidase activity were accompanied by the appearance of a distinct new protein species with greater electrophoretic mobility. The oxidase from ischemic rat liver was purified 781-fold and found to migrate with a higher mobility on native gels than the purified native dehydrogenase. Sodium dodecyl sulfate profiles revealed the presence of a single major band of 137 kD for the native dehydrogenase, whereas the oxidase had been partially cleaved generating polypeptides of 127, 91, and 57 kD. Polypeptide patterns for the oxidase resemble those seen following limited in vitro proteolysis of the native dehydrogenase supporting a proteolytic mechanism for the conversion of xanthine dehydrogenase to oxidase in ischemic rat liver.

T o examine the pattern and mechanisms of enhanced intestinal nutrient absorption in diabetes, we measured intestinal transport of 3-O-methylglucose (3OMG), l-alanine (ALA), and SO4 in male Lewis rats made diabetic with streptozocin. Diabetes enhanced 3OMG absorption fivefold in ileum and threefold in jejunum; ALA absorption increased twofold in ileum but not at all in jejunum; ileal SO4 transport was unaffected. Increases in 3OMG and ALA transport were due solely to increases in maximum velocity. The enhancement of ileal glucose absorption was half-maximal in 40-45 d, could be reversed by 10 d of treatment with insulin and did not result from adrenergic denervation. The density of glucose carriers per milligram brush border protein (measured as [3H]phlorizin binding sites) was not altered but there was a sixfold increase in the number of glucose-inhibitable [3H]phlorizin-binding sites in the intact epithelium. Generalized mucosal hypertrophy accounted for less than 30% of this increase. We conclude that the intestine adapts to streptozocin-induced diabetes through recruitment of additional brush border carriers for sugar, probably in the midvillus-to-crypt region.

I ncreased alveolar surface tension due to surfactant deficiency is thought to result in a negative pressure surrounding pulmonary capillaries and to promote fluid filtration. To test this hypothesis, alveolar liquid pressure (Pliquid) was measured by micropuncture in isolated lungs of mature and immature fetal rabbits (with and without surfactant replacement) at different air inflation pressures (Pairway). Lung maturity was assessed by air pressure-volume (P-V) curves. Pliquid was correlated with surfactant content in the lungs and with alveolar size. Pliquid was lower in immature (2.3 +/- 0.7 cmH2O) than in mature (8.4 +/- 1.0 cmH2O) lungs at comparable Pairway (25 cmH2O) (P less than 0.01). The mean linear intercept, a measure of airspace dimensions was similar in all lungs (42.1 +/- 2.0 micron), but alveolar wash phospholipid/g wet lung was lower in immature than in mature lungs (0.05 +/- 0.01 vs. 0.49 +/- 0.30 mg) (P less than 0.01). Surfactant replacement in immature lungs resulted in P-V curves and Pliquid similar to those of mature lungs. If pericapillary interstitial liquid pressure approximates Pliquid, surfactant deficiency will predispose preterm infants to pulmonary edema.

W e previously identified a 210,000-mol-wt platelet glycoprotein (GP 210) that is missing from Bernard-Soulier platelets, and found that an antibody against GP 210 inhibits ristocetin-induced platelet agglutination. We now show by immunoblotting that GP 210 binds heat-aggregated rabbit and human IgG, as well as keyhole limpet hemocyanin (KLH)-anti-KLH and ovalbumin (OA)-anti-OA immune complexes. Immune complex binding to GP 210 was preserved on chymotrypsin-treated platelets that lacked glycoprotein Ib (GP Ib). In contrast, ristocetin-induced platelet agglutination resulted in disappearance of immunologically detectable GP 210 and loss of immune complex binding, even though GP Ib remained intact. Purified Fc fragments inhibited binding of anti-GP 210 antibody to intact platelets and to GP 210 on immunoblots. The Fc fragments also blocked immune complex binding to GP 210. Conversely, anti-GP 210 antiserum and F(ab)2 fragments inhibited binding of fluorescein-labeled Fc fragments to intact platelets. We conclude that GP 210 functions as a platelet Fc receptor.

T he present study was designed to determine whether somatostatin is released into the circulation in sufficient amounts to regulate exocrine and endocrine pancreatic function and to evaluate the possible role of somatostatin as a hormonal regulator of the pancreas. Mean plasma somatostatin levels (SLI) increased from 11 +/- 2 pmol liter-1 to peak concentrations of 18 +/- 2 in six healthy male volunteers after a steak meal (P less than 0.05). Infusion of somatostatin inhibited hormone-induced exocrine pancreatic secretion and suppressed cerulein-stimulated pancreatic polypeptide (PP) secretion, but did not significantly change arginine-stimulated insulin and glucagon release at mean plasma somatostatin concentrations within the range seen after a meal. The amount of somatostatin released after a meal thus was of sufficient magnitude to inhibit exocrine pancreatic function and PP release. On the other hand, basal and arginine-stimulated glucagon and insulin secretions were not significantly affected by these plasma concentrations of intravenous somatostatin suggesting that the exocrine pancreas might be more sensitive to somatostatin than the islet cells. We conclude that somatostatin in concentrations within the range seen after a meal is a potent inhibitor of stimulated acinar cell function in man. The findings support the hypothesis that somatostatin acts as a true hormonal regulator.

T o test the hypothesis that prostacyclin (PGI2) is formed via a biochemical interaction between platelets and lymphocytes, we measured eicosanoids by high performance liquid chromatography (HPLC) and radioimmunoassay (RIA). A distinct 6-keto-prostaglandin F1 alpha (6KPGF1 alpha) peak was noted when [14C]arachidonic acid ([14C]AA) was added to the mixed cell preparations which was increased by pretreating platelets with 1-benzylimidazole (1-BI). Lymphocytes prelabeled with [14C]AA failed to form 6KPGF1 alpha when stimulated with phytohemagglutinin (PHA) or ionophore A23187. When the prelabeled platelets were suspended together with aspirin-treated lymphocytes and stimulated with ionophore, thrombin, or collagen, a 6KPGF1 alpha peak was detected and enhanced by 1-BI. These results were supported by quantifying the 6KPGF1 alpha content in the HPLC-purified fraction by RIA. Adding prostaglandin H2 (PGH2) directly to lymphocytes led to 6KPGF1 alpha production. Platelet aggregation and release were inhibited by lymphocytes in a dose-related manner. We conclude that lymphocytes possess PGI2 synthase activity which is capable of converting platelet-derived PGH2 into PGI2. PGI2 formed is sufficient to inhibit platelet function.

W e have found a human serum, E27, obtained from a multiply transfused patient with systemic lupus erythematosus, which immunoprecipitates the lymphocyte function associated antigen-1 (LFA-1). The immunoprecipitated molecules were identified as the LFA-1 alpha and beta chains by their comigration on SDS-PAGE, two-dimensional SDS-PAGE, and by sequential clearance experiments. Serum E27 did not immunoprecipitate LFA-1 from autologous cells, though LFA-1 molecules were present. In contrast, serum E27 immunoprecipitated LFA-1 from most but not all normal donor lymphocytes. Thus, serum E27 defines two serological phenotypes of LFA-1. 95% of normal individuals tested exhibited the LFA-1 phenotype precipitated by serum E27. Serum E27 appears to be directed at determinants of the LFA-1 alpha-chain and not the beta-chain since it immunoprecipitated LFA-1 molecules but not the Mac-1 molecules. Additional evidence for the alpha chain specificity was provided by immunoprecipitation of mouse-human heterohybridoma cells. LFA-1 was immunoprecipitated by serum E27 from mouse-human heterohybridoma cells expressing the human alpha-chain, not from a hybrid cell line expressing the human beta-chain. Together these findings demonstrate an antigenic polymorphism of the human LFA-1 alpha-chain molecule.

W e calculated gastric HCO3- and H+ secretion, as well as nonparietal and parietal volume secretion, in 15 duodenal ulcer patients who had previously undergone successful proximal gastric vagotomy, 15 unoperated duodenal ulcer patients, and 15 normal control subjects. Basal HCO3- secretion was not significantly altered after vagotomy, while basal H+ secretion, parietal volume and nonparietal volume secretion were reduced significantly. Intravenous gastrin-17 infusion reduced gastric HCO3- secretion by approximately 50% in both unoperated ulcer patients and normal subjects (P less than 0.05). Gastrin-17 infusion did not inhibit gastric HCO3- secretion after vagotomy. In fact, mean gastric HCO3- secretion increased to a nearly significant extent in response to gastrin (P = 0.06). These findings indicate that gastrin inhibits gastric HCO3- secretion in humans and that the gastrin-induced reduction in gastric HCO3- secretion is dependent upon intact vagal innervation to the oxyntic mucosa.

W e studied the role of the sodium-potassium pump in erythrocytes of 12 patients with sickle cell anemia (SS). Ouabain-binding sites per cell and pump-mediated Rb/K uptake were significantly higher in SS patients than in white or black controls. Ouabain-resistant Rb/K influx was also greater than in normal controls or patients with sickle cell trait. Deoxygenation of SS erythrocytes increased ouabain-sensitive Rb/K influx without altering ouabain binding, presumably as the consequence of an increase in the passive influx of sodium. Deoxygenation increased mean corpuscular hemoglobin concentration (MCHC) by 5.5%, and studies of the density distribution of SS cells indicated an increase in highly dense fractions known to contain sickled erythrocytes. Ouabain prevented the rise in MCHC and reduced the percentage of dense cells. These findings indicate a magnified role for the sodium-potassium pump in the pathophysiology of SS erythrocytes and suggest that its inhibition might prove useful in therapy.

4 4 small cell lung cancer cell lines established from 227 patients were studied for myc family DNA amplification (c-myc, N-myc, and L-myc). Two of 19 lines (11%) established from untreated patients' tumors had DNA amplification (one N-myc and one L-myc), compared with 11 of 25 (5 c-myc, 3 N-myc, and 3 L-myc) cell lines (44%) established from relapsed patients' tumors (P = 0.04). The 19 patients who had tumor cell lines established before chemotherapy treatment survived a median of 14 wk compared with 48 wk for the 123 extensive stage patients who did not have cell lines established (P less than 0.001). Relapsed patients whose cell lines had c-myc DNA amplification survived a shorter period (median of 33 wk) than patients whose cell lines did not have c-myc amplification (median of 53 wk; P = 0.04). We conclude that myc family DNA amplification is more common in tumor cell lines established from treated than untreated patients' tumors, and c-myc amplification in treated patients' tumor cell lines is associated with shortened survival.

H ypoalbuminemia in inflammatory disorders is not an infrequent finding. However, little is known about albumin synthesis in these patients. In the present study we have measured the albumin synthesis in four patients with inflammatory diseases using the [14C]carbonate technique. Because inflammation causes a decreased albumin synthesis and this decreased synthesis could not be related to a reduced amino acid supply, we have also examined the possible molecular mechanisms of reduced albumin synthesis during inflammation using in vivo and in vitro experiments in rats. In rats with turpentine-induced inflammation, serum albumin concentration and liver albumin mRNa level were markedly decreased. These changes could not be reproduced by administration of fibrinogen-, or fibrin-degradation products, or several hormones, such as corticosteroids, growth hormone, and adrenaline. However, monocytic products, especially interleukin 1, postulated to be important mediators of the inflammatory response, reduced albumin synthesis and liver albumin messenger RNA content but not total protein synthesis in rats in vivo and in primary cultures of rat hepatocytes. These findings suggest that monocytic products play an important role in reduced albumin synthesis during inflammation.

W e have determined the extent of fragment X formation during thrombolytic therapy by integration over time of the plasma fibrinopeptide B beta 1-42 concentration. This peptide is quantitatively released when fragment X is formed by plasmin action on fibrinogen or fibrin I. In response to streptokinase (SK) and rt-PA, 264 +/- 54 and 95 +/- 12 mg/dl respectively of fibrinogen was converted to fragment X. By immunoblotting, fragment X was demonstrated as early as 5 min after SK and 30 min after rt-PA, and was still evident 24 h after treatment. Patients treated with SK showed extensive further plasmin degradation of fragment X to fragments Y and D. Thus fragment X concentrations tend to be more similar in the two groups than would be expected from the extent of fibrinogen breakdown. Fragment X forms clots, but these have lower tensile strength and are more susceptible to further plasmin lysis than clots of fibrin. Thus the similar bleeding observed in the two treatment groups might be a reflection of their similar plasma fragment X concentrations.

R ecombinant murine granulocyte macrophage colony-stimulating factor (rGM-CSF) has been produced in Escherichia coli and purified to homogeneity. GM-CSF has an established role as an in vitro regulator of granulocyte and macrophage colony formation. We have determined that rGM-CSF also has intrinsic activity as a megakaryocyte colony-stimulating factor and that rGM-CSF augments the effect of interleukin 3 (IL-3) on megakaryocyte colony formation. The dose-response curve for megakaryocyte colony induction with rGM-CSF showed plateau megakaryocyte stimulation at 9 ng/ml. When IL-3 (at a plateau dose for megakaryocyte colony induction) was added to rGM-CSF over a 0-22-ng/ml dose range, the resultant megakaryocyte colony stimulation approximated the sum of the levels of stimulation produced by either factor alone. These results establish GM-CSF as a multilineage growth factor with definite megakaryocyte colony-stimulating activity and indicate that both GM-CSF and IL-3 are important in the regulation of megakaryocytopoiesis.

W e compared the blood (PBDHT) and urine (PUDHT) production rate of dihydrotestosterone (DHT) in normal men and women to determine whether peripheral formation was totally reflected in blood. PBDHT was similar when measured at both sites in men (674 +/- 79 vs. 788 +/- 207 SE micrograms/d); however, PUDHT was greater than PBDHT in women (174 +/- 55 vs. 55 +/- 8 micrograms/d, P less than 0.02). Excretion rates of DHT and 3 alpha-androstanediol (3 alpha diol) were similar in both sexes despite major differences in blood levels. However, between sexes large differences were present in 3 alpha diol glucuronide (3 alpha diolG) in both plasma and urine. These observations indicate that peripheral (renal) formation of DHT and probably 3 alpha diol were not accurately determined by measurement of these steroids in blood. The large difference between blood and urine production rates in women suggests an important role of non-testosterone precursors of 5 alpha-reduced steroids. Measurements of 3 alpha diolG may provide more insight into these peripheral events.

T he steroid hormone, 1 alpha,25-dihydroxyvitamin D3 (calcitriol), has been shown to inhibit T cell proliferation, primarily through inhibition of interleukin 2 (IL-2) production. In these experiments, we show that calcitriol also markedly inhibited production of the lymphokine, gamma interferon (IFN-gamma), by activated human T lymphocytes. Regulation of both IL-2 and IFN-gamma production as well as transferrin receptor (TfR) expression by calcitriol was apparent at the messenger RNA (mRNA) level as determined by Northern blotting. The decrease in IL-2 and IFN-gamma mRNA that occurred with calcitriol treatment was coordinate and not apparent up to 12 h after phytohemagglutinin stimulation, whereas decreased accumulation of TfR mRNA was not present before 24-36 h. Furthermore, the effects of calcitriol on IL-2, IFN-gamma, and TfR mRNA accumulation were specific; actin mRNA accumulation was comparable between control and treated cells. These data indicate that calcitriol regulated proteins associated with T cell activation at the transcriptional level and that these effects were mediated in a specific, coordinate fashion.

L ung inflammatory cells of patients with idiopathic pulmonary fibrosis (IPF) were evaluated for their ability to injure 51Cr-labeled AKD alveolar epithelial cells in the presence and absence of IPF alveolar epithelial lining fluid (ELF). The IPF cells were spontaneously releasing exaggerated amounts of superoxide (O.2) and hydrogen peroxide (H2O2) compared with normal (P less than 0.02). Cytotoxicity of the AKD cells was markedly increased when the IPF inflammatory cells were incubated with autologous ELF (P less than 0.02). The majority of IPF patients had ELF myeloperoxidase levels above normal (P less than 0.002). Incubation of IPF ELF with AKD cells in the presence of H2O2 caused increased cellular injury (P less than 0.01 compared with control), which was suppressed by methionine, a myeloperoxidase system scavenger. IPF patients with high concentrations of ELF myeloperoxidase deteriorated more rapidly than those with low ELF myeloperoxidase (P less than 0.05). Thus, IPF is characterized by an increased spontaneous production of oxidants by lung inflammatory cells, the presence of high concentrations of myeloperoxidase in the ELF of the lower respiratory tract, and a synergistic cytotoxic effect of alveolar inflammatory cells and ELF on lung epithelial cells, suggesting oxidants may play a role in causing the epithelial cell injury of this disorder.

D uring phototherapy for neonatal jaundice, bilirubin is converted into a variety of photoproducts. Determination of the relative importance of these photoproducts to the elimination of bilirubin requires knowledge of their rates of excretion. We have measured the rate at which the structural isomer of bilirubin, lumirubin, disappeared from the serum of nine jaundiced premature infants after the cessation of phototherapy. In all patients studied, the decline in serum lumirubin could be approximated by a first-order rate equation with a half-life of 80 to 158 min. This rate of disappearance is much faster than that previously determined for the other major bilirubin photoproducts. In samples of bile aspirated from the duodenum of infants undergoing phototherapy, lumirubin was the principal bilirubin photoproduct found. These results indicate that formation and excretion of lumirubin is an important route for bilirubin elimination during phototherapy.

T he microvascular endothelium has been postulated to be a critical target in the rejection of vascularized allografts. This study was undertaken to examine the ability of human sheep erythrocyte rosette forming lymphocytes (E-RFC) to form stable conjugates with microvascular endothelial cells (EC), and to assess whether a receptor-ligand interaction mediates this event. Human foreskin microvascular EC monolayers were used as targets of chromium-51-labeled E-RFC in a quantitative adherence assay. Binding was saturable, displaceable by unlabeled E-RFC, augmented by recombinant interleukin 1 (rIL-1) and inhibited by anti-LFA1 antibody. The Leu-11+ lymphocyte subset, known to be enriched for natural killer (NK) cells, bound preferentially. Only the EC-adherent lymphocyte fraction contained NK effectors, which lysed EC and classical NK targets. Thus, NK cells adhere to microvascular EC via a specific receptor-ligand interaction. The possibility exists that such binding occurs in recipients of vascularized allografts, representing the initial stage of graft rejection.

T he molecular basis of clinical diversity in glycogenosis type II (Pompe's disease) was investigated by comparing the nature of acid alpha-glucosidase deficiency in cultured fibroblasts from 30 patients. Biosynthetic forms of acid alpha-glucosidase with different molecular mass were separated electrophoretically and identified by immunoblotting. Immuno-electron microscopy was employed to determine the intracellular localization of mutant enzyme. Our studies illustrate that maturation of acid alpha-glucosidase is associated with transport to the lysosomes. Deficiency of catalytically active mature enzyme in lysosomes is common to all clinical phenotypes but, in the majority of cases, is more profound in early onset than in late onset forms of the disease. Thus, the results suggest that the clinical course of glycogenosis type II is primarily determined by the amount of functional acid alpha-glucosidase. The role of secondary factors can, however, not be excluded because three adult patients were identified with very low activity and little enzyme in the lysosomes.

W e show that 1,25-dihydroxyvitamin D3 (1,25[OH]2D3), the most hormonally active metabolite of vitamin D3, modulates sensitively and specifically both the protein and messenger RNA accumulation of the multilineage growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF). The regulation of GM-CSF expression is seen in both normal human mitogen-activated T lymphocytes and T lymphocytes from a line (S-LB1) transformed with human T cell lymphotropic virus 1 (HTLV-1). In contrast, cells from a HTLV-1 transformed T lymphocyte line (Ab-VDR) established from a patient with vitamin D-resistant rickets type II with undetectable 1,25(OH)2D3 cellular receptors are resistant to the action of 1,25(OH)2D3. Inhibition of GM-CSF expression by 1,25(OH)2D3 can occur independently of interleukin 2 regulation and is probably mediated through cellular 1,25(OH)2D3 receptors. We conclude that 1,25(OH)2D3 may be important in the physiology of hematopoiesis.

W e have previously identified a receptor for 1,25-dihydroxyvitamin D3 in myocardial cells (Simpson, R.U. 1983. Circulation. 68:239.). To establish the relevance of this observation, we evaluated the role of the prohormone vitamin D3 in regulating cardiovascular function. In rats maintained on a vitamin D3-deficient diet for nine weeks, increases in systolic blood pressure (BP) and serum creatine phosphokinase (CPK) were observed. These increases coincided with a reduction of serum calcium from 10.3 to 5.6 mg/dl. However, while serum calcium remained depressed throughout the study, increases in BP and serum CPK were transient. After nine weeks of vitamin D3-depletion, but not after six weeks, ventricular and vascular muscle contractile function were also markedly enhanced. The increase in ventricular contractile function could not be prevented by maintaining serum calcium at 9.0 mg/dl during the period of D3-depletion. These observations suggest a primary role for the vitamin D3-endocrine system in regulating cardiovascular function.

W e reevaluated the concept that the in vivo glucose disposal rate in man is determined by the activity of the glucose transport system. Rates of glucose disposal were determined in whole body and across forearm at four insulin levels (approximately 9, approximately 50, approximately 160, and approximately 1700 microU/ml) and at each insulin level at four glucose levels (approximately 90, approximately 160, approximately 250, and approximately 400 mg/dl). At the lowest insulin level, the Michaelis constants (Ks:s) for glucose disposal in whole body (8.7 +/- 1.1 mM) and across forearm (7.4 +/- 1.4) mM) were compatible with a Ks determined in vitro for the transport system. At higher insulin levels, the apparent Ks increased significantly in whole body (16.2-37.7 mM) and across forearm (20.7-31.2 mM). We interpret the apparent increase of Ks by insulin to reflect a shift in the rate-limiting step from glucose transport to some step beyond transport.

H uman granulocyte-macrophage colony-stimulating factor (GM-CSF) exerts profound effects on the proliferation, differentiation, and effector function of myeloid lineage cells. In contrast to its growth-promoting effects on normal myeloid progenitor cells, we found that GM-CSF unexpectedly inhibited the colony growth of U937 cells in agar culture. Furthermore, medium conditioned by recombinant GM-CSF(rGM-CSF)-treated U937 cells was found to exert an inhibitory effect on subsequent U937 colony growth that was partially due to the presence of tumor necrosis factor (TNF). By Northern blot analysis, rGM-CSF was shown to induce expression of the TNF gene in U937 cells and in T-lymphocyte-depleted, monocyte-enriched peripheral blood mononuclear cells. Furthermore, rGM-CSF was observed to significantly enhance TNF secretion by monocytes stimulated with endotoxin and phorbol myristate acetate (PMA). These data suggest that some of the biological effects of GM-CSF may be amplified through the release of monokines such as TNF.

S tudies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.

R everse triiodothyronine (rT3) is metabolized predominantly by outer ring deiodination to 3,3'-diiodothyronine (3,3'-T2) in the liver. Metabolism of rT3 and 3,3'-T2 by isolated rat hepatocytes was analyzed by Sephadex LH-20 chromatography, high performance liquid chromatography, and radioimmunoassay, with closely agreeing results. Deiodinase activity was inhibited with propylthiouracil (PTU) and sulfotransferase activity by sulfate depletion or addition of salicylamide or dichloronitrophenol. Normally, little 3,3'-T2 production from rT3 was observed, and 125I- was the main product of both 3,[3'-125I]T2 and [3',5'-125I]rT3. PTU inhibited rT3 metabolism but did not affect 3,3'-T2 clearance as explained by accumulation of 3,3'-T2 sulfate. Inhibition of sulfation did not affect rT3 clearance but 3,3'-T2 metabolism was greatly diminished. The decrease in I- formation from rT3 was compensated by an increased recovery of 3,3'-T2 up to 70% of rT3 metabolized. In conclusion, significant production of 3,3'-T2 from rT3 by rat hepatocytes is only observed if further sulfation is inhibited.

W e studied the disaggregation of human platelets by tissue-type plasminogen activator (t-PA). When added to a suspension of human platelets induced to aggregate in plasma with adenosine 5'-diphosphate, t-PA promoted disaggregation of platelets over several minutes. Addition of fresh plasma or purified human fibrinogen to disaggregated platelets facilitated (reversible) aggregation and subsequent disaggregation. Aspirin treatment of platelets markedly potentiated the ability of t-PA to induce disaggregation. Disaggregation was inhibited by alpha-2-antiplasmin. Comparative analysis of the rate of proteolysis of platelet-bound fibrinogen with that of ambient plasma fibrinogen suggested that fibrinogenolysis of cohesive fibrinogen occurred more rapidly than fibrinogenolysis of ambient fibrinogen. These data demonstrate that t-PA facilitates platelet disaggregation in plasma through kinetically selective proteolysis of cohesive fibrinogen by plasmin, and suggest that thrombolytic mechanisms may serve both to remove platelets from platelet-fibrin thrombi and to disperse circulating platelet aggregates.

A dministration in vivo of recombinant interleukin 2 (rIL-2) to mice induces a polyclonal IgM response. When co-administered with a specific antigen, rIL-2 can enhance concentrations of murine IgM antibodies specific for the antigen by fivefold within 7 d of initial treatment. IgM antibodies that are induced after injection of rIL-2 include antibodies specific for J5, a cell wall core lipopolysaccharide (LPS) antigen that is shared by the different members of the Enterobactericeae family. We report here that mice pretreated with rIL-2 or immunized with J5 antigen 7 d before bacterial challenge were protected from septic death that is caused by intraperitoneal challenges with Escherichia coli. Optimal protection was provided by a combined J5 antigen and rIL-2 treatment. Acquisition of the rIL-2 and J5 antigen-induced protection against lethal bacterial infection coincided temporally with maximal serum IgM titers that also contained IgM antibodies specific for the J5 antigen. In passive immunization experiments, the affinity-purified IgM fraction in sera of rIL-2-treated animals was identified as necessary and sufficient for protection. The IgM-depleted serum had no protective effect. The nonspecific augmentation of host-defense mechanisms without the induction of endotoxin manifestations makes rIL-2 a potential candidate to any alternative LPS-containing vaccines for the prevention of bacterial infections by gram-negative organisms since the core LPS antigen is shared among gram-negative bacteria.

T he metabolism of human IgE was studied in normals, severe atopics, and patients with the hyperimmunoglobulin E-recurrent infection (HIE; Job's) syndrome to determine whether IgE metabolism is altered in patients with marked elevation of serum IgE. Purified polyclonal 125I-IgE was administered intravenously and serial plasma and urine samples were obtained. After analysis, the metabolic data support previously published evidence that IgE (at concentrations found in normal individuals) is catabolized at a higher fractional rate than other immunoglobulins and is catabolized by both an intravascular and an extravascular pathway. In addition, the data show that the fractional catabolic rate for IgE is significantly less for the atopic patients (mean +/- SEM = 0.20 +/- 0.01) and for the HIE patients (0.15 +/- 0.02) than for the normal volunteers (0.52 +/- 0.06; P less than 0.01) and is inversely related (r = -0.851; P less than 0.001) to the serum IgE concentration. These findings have specific importance in showing that decreased fractional catabolic rate contributes substantially to elevation of IgE in atopic and HIE patients. In addition, the findings have general significance in that they lead to a unifying hypothesis of immunoglobulin catabolism.

L -Triiodothyronine (T3) stimulates DNA synthesis and replication of cultured GC cells, a T3-responsive growth hormone (GH)-secreting cell line. To determine whether T3 stimulates secretion of an autocrine growth factor, we compared the growth-promoting activity of medium conditioned by T3-stimulated and T3-depleted cells to that of unconditioned medium. Addition of polyclonal rabbit anti-T3 serum to T3-containing media decreased cellular T3 content by 50-70%. In unconditioned medium, anti-T3 serum decreased T3-induced cell growth and GH production by 40-70%. In conditioned medium, anti-T3 serum also effected a 45-70% decrease in induction of GH secretion but did not attenuate the growth-promoting activity. Growth-promoting activity was not detected in medium conditioned by T3-depleted cells. Thus, conditioned medium from T3-containing GC cell cultures contains growth-promoting activity that is independent of T3. Further, the induction of GC cel growth by T3 may occur, at least in part, by induction of an autocrine growth factor.

W e have determined that the organic matrix of calcium oxalate kidney stones contains a glycoprotein inhibitor of calcium oxalate crystal growth (nephrocalcin) that resembles nephrocalcin present in the urine of patients with calcium oxalate stones and differs from nephrocalcin from the urine of normal people. Pulverized calcium oxalate renal stones were extracted with 0.05 M EDTA, pH 8.0; nephrocalcin eluted in five peaks using DEAE-cellulose column chromatography, and each peak was further resolved by Sephacryl S-200 column chromatography. Four of the five DEAE peaks corresponded to those usually found in nephrocalcin from urine; the fifth eluted at a lower ionic strength than any found in urine. Amino acid compositions and surface properties of nephrocalcins isolated from kidney stones closely resembled those of nephrocalcins isolated from urine of stone-forming patients: they differed from normal in lacking gamma-carboxyglutamic acid residues, and in forming air-water interfacial films that were less stable than those formed by nephrocalcin from normal urine.

W e reported that aspirin (ASA) abnormally prolongs bleeding time (BT) in uremia. The present study was designed to investigate whether the abnormally prolonged post-ASA BT in uremia is due to different ASA pharmacokinetics and bioavailability that might be a consequence of uremic condition, platelet cyclooxygenase is peculiarly sensitive to ASA in uremia, and ASA affects primary hemostasis in uremia by a mechanism independent of cyclooxygenase inhibition. Our results showed that in patients with uremia, but not in normal subjects, ASA markedly prolongs the BT. This effect is transient and depends on the presence of ASA in the blood. The observed differences in ASA kinetic parameters are not an explanation of the exaggerated effect of ASA on primary hemostasis in uremia. The sensitivity of platelet cyclooxygenase to ASA inhibition is comparable in uremics and in normal subjects. The temporal dissociation between ASA-induced prolongation of BT and the effect on platelet thromboxane A2 generation suggests that ASA inhibits platelet function in uremia by a mechanism distinct from cyclooxygenase blocking. This possibility is strengthened by the observation that ibuprofen at a dose that fully inhibits platelet cyclooxygenase activity does not significantly prolong BT.

T he effects of interaction between endothelial angiotensin converting enzyme (ACE) and goat anti-rabbit ACE (GtARbACE) antibodies were studied in rabbit glomeruli. By immunofluorescence ACE was not detectable in normal glomeruli. However, when kidneys were perfused with GtARbACE antibodies glomerular bound IgG was seven times higher than that of non-immune IgG and granular deposits of goat IgG were found on the endothelium of glomeruli and arteries. Rabbits injected intravenous for 4 d with GtARbACE antibodies showed on day 1 granular deposits of goat IgG on the glomerular endothelium; from day 3 to 24 there was gradual development of subepithelial deposits of goat IgG, rabbit IgG and C3. When GtARbACE antibodies were similarly injected into proteinuric rabbits there was formation of subepithelial granular deposits of goat IgG and ACE. The results document that a glomerular endothelial antigen is redistributed in vivo by a specific ligand, an event associated with formation of immune deposits. Furthermore, if the glomerular permeability is artificially increased, immune complexes shed from nonglomerular endothelia into the circulation can contribute to form subepithelial immune deposits.

C atecholamine-induced lipolysis in isolated human adipocytes during the first year of life was investigated. During this period fat cell size increased markedly. Basal and catecholamine-induced glycerol release were positively correlated with age when lipolysis was expressed per cell. However, when lipolysis was expressed per unit of cell surface area (micrometer squared), this correlation was observed only for noradrenaline. Basal lipolysis and the effect of the pure beta-agonist, isoprenaline, were identical in infants and adults. From 0 to 2 mo of age noradrenaline had very little lipolytic effect. The addition of the alpha-2-adrenoceptor antagonist, yohimbine, to noradrenaline equalized lipolysis per micrometer squared in infants and adults and the alpha-2-adrenoceptor sensitivity was significantly enhanced in infants. In both groups the lipolytic adrenoceptor was of the beta-1 type. In conclusion, adipocytes from infants have a poor lipolytic response to noradrenaline partly because of the small fat cells but mainly because of an enhanced alpha-2-adrenoceptor activity.

T he responsiveness of isolated guinea pig lung parenchymal strips to substance P was enhanced by at least 100-fold in the presence of the endopeptidase inhibitors phosphoramidon (1 microM) or thiorphan (1 microM), but not with the converting enzyme inhibitor, captopril, or an inhibitor of serum carboxypeptidase N (both 1 microM). Responses of guinea pig tracheal rings to substance P were also markedly potentiated by phosphoramidon. The increase in tissue responsiveness by these inhibitors was relatively specific for substance P among several other spasmogenic peptides, including formyl-methionyl-leucyl-phenylalanine and the complement peptides C3a and C5a. The enhanced responses appear to result from a decrease in the rate of substance P degradation in the presence of neutral endopeptidase inhibitors. Specific binding of substance P to its receptor on bronchial membranes was increased by three- to fourfold in the presence of phosphoramidon. These data demonstrate an enhanced potential for substance P to contract lung tissues when degradation by a neutral endopeptidase-like enzyme is blocked.

A utoantibodies in the skin and sera of patients with epidermolysis bullosa acquisita bind to a large matrix molecule within the lamina densa region of skin basement membrane. At the site of these immune complexes, the epidermis separates from the dermis, which creates a subepidermal blister just below the lamina densa. The target molecule for the autoantibodies is in close apposition to fibronectin, a major extracellular matrix molecule that is abundant in the upper dermis of skin. In this report, we show specific affinity between fibronectin and the 290,000-D chain of the epidermolysis bullosa acquisita antigen, and that this affinity is mediated by the gelatin/collagen-binding domain of fibronectin (Mr = 60,000). Since blistering in epidermolysis bullosa acquisita often occurs in the absence of clinical and histological inflammation, a direct interruption in the fibronectin-epidermolysis bullosa acquisita antigen bond may be involved in the pathogenesis of epidermal-dermal disadherence that occurs in this bullous disease.

S teinberg and colleagues have previously described a unique kindred with normotriglyceridemic hypobetalipoproteinemia (1979. J. Clin. Invest. 64:292-301). In a reexamination of this kindred, we found an abnormal apolipoprotein (apo) B species, apo B-37 (203,000 mol wt), in the plasma lipoproteins of multiple members of the kindred. In affected individuals apo B-37 was found in very low density lipoproteins, along with the normal apo B species, apo B-100 and apo B-48. High density lipoproteins (HDL) also contained apo B-37, but no other apo B species. The first 13 amino-terminal amino acids of apo B-37 were identical to those of normal apo B-100. We utilized a panel of 18 different apo B-specific monoclonal antibodies and polyclonal antisera specific for apo B-37 and the thrombin cleavage products of apo B-100 to map apo B-37 in relation to apo B-100, apo B-48, and the thrombin cleavage products of apo B-100. The results of those immunochemical studies indicated that apo B-37 contains only amino-terminal domains of apo B-100. In affected individuals, the majority of apo B-37 in plasma was contained in the HDL density fraction. Within that fraction apo B-37 was found on discrete lipoprotein particles, termed Lp-B37, that had properties distinct from normal HDL particles containing apo A-I. This report documents for the first time the existence of an abnormal apo B species in humans. Further study of apo B-37 and lipoprotein particles containing apo B-37 should lead to an improved understanding of apo B structure and function.

I n 1979 Steinberg and colleagues recognized a unique kindred with normotriglyceridemic hypobetalipoproteinemia (1979. J. Clin. Invest. 64:292-301). We have undertaken an intensive reexamination of this kindred and have studied 41 family members in three generations. In this family we document the presence of two distinct apo B alleles associated with low plasma concentrations of apolipoprotein (apo) B and low density lipoprotein (LDL) cholesterol and we trace the inheritance of these two alleles over three generations. One of the alleles resulted in the production of an abnormal, truncated apo B species, apo B-37. The other apo B allele was associated with reduced plasma concentrations of the normal apo B species, apo B-100. H.J.B., the proband, and two of his siblings had both abnormal apo B alleles and were therefore compound heterozygotes for familial hypobetalipoproteinemia. Their average LDL-cholesterol level was 6 +/- 9 mg/dl. All of the offspring of the three compound heterozygotes had hypobetalipoproteinemia, and each had evidence of only one of the abnormal apo B alleles. In the entire kindred, we identified six heterozygotes for familial hypobetalipoproteinemia who had only the abnormal apo B-37 allele and their average LDL cholesterol was 31 +/- 12 mg/dl. We identified 10 heterozygotes who had only the allele for reduced plasma concentrations of apo B-100 and their LDL cholesterol level was 31 +/- 15 mg/dl. Unaffected family members (n = 22) had LDL cholesterol levels of 110 +/- 27 mg/dl. This report describes the first kindred in which two distinct abnormal apo B alleles have been identified, both of which are associated with familial hypobetalipoproteinemia.

U sing 31P-nuclear magnetic resonance, we studied the relationship between myocardial high-energy phosphate content and flux values for the creatine kinase reaction in the living rat under inotropic states achieved during norepinephrine infusion and halothane anesthesia. Under 2% halothane anesthesia (n = 4), 1% halothane anesthesia (n = 5) and norepinephrine infusion (n = 4), rats developed rate-pressure products of 19.5 +/- 1.6, 32.0 +/- 3.5, and 48.5 +/- 2.0 X 1,000 mmHg/min, respectively. Adenosine triphosphate content was not affected by inotropic state, ranging from 24.3 +/- 1.1 to 25.6 +/- 1.1 mumol/g dry weight, but creatine phosphate content varied inversely and reversibly with cardiac performance from 45.6 +/- 6.0 under 2% halothane to 26.0 +/- 6.5 mumol/g dry weight during norepinephrine infusion. The flux values for the creatine kinase reaction were 15.4 +/- 4.6, 20.5 +/- 2.0, and 30.1 +/- 7.9 mumol/g dry weight per s under 2% halothane, 1% halothane, and 1% halothane with norepinephrine, respectively. These results suggest that the turnover of myocardial high-energy phosphate compounds, not their tissue contents, matches cardiac performance during inotropic stimulation.

T he administration of platelet-activating factor (PAF) into the airway system of the lung is known to cause profound effects, yet little is known about the metabolism of this active lipid mediator. 3H-Labeled PAF administered into the airway of isolated rat lungs was rapidly and extensively metabolized. The tissue retained 96% of the administered radiolabel while the perfusate contained 4%. Characterization of the tissue retained lipid indicated metabolism into lyso-PAF (3.3%), phosphatidylcholine (82.3%), neutral lipid (1.7%) and intact PAF (10.2%). Analysis of tissue phosphatidylcholine by mass spectrometric techniques revealed metabolism of PAF to 1-0-hexadecyl-2-arachidonoyl-GPC, which represented 20-23% of the administered radiolabeled hexadecyl-PAF. These findings support the hypothesis that a relationship between PAF and arachidonate metabolism exists at the intact organ level. Autoradiographic analysis of the cellular distribution of the radiolabeled PAF metabolites in the lung tissue indicated labeling of two cell types, the alveolar type II cell and the nonciliated bronchiolar epithelial cell (Clara cell).

S ingle, preexposure, parenteral injection with both recombinant tumor necrosis factor/cachectin (TNF/C) and interleukin-1 (IL-1) prolonged the survival of rats (144 +/- 9 h) in continuous hyperoxia (greater than 99% O2 at 1 atm) when compared with rats injected with boiled TNF/C and boiled IL-1 (61 +/- 2 h), TNF/C alone (61 +/- 2 h), IL-1 alone (62 +/- 2 h), or saline (64 +/- 3 h). After exposure to hyperoxia for 52 h, pleural effusion volume, pulmonary artery pressure, total pulmonary resistance, and lung morphologic damage were decreased in those rats given TNF/C and IL-1 as compared with saline-injected rats. In parallel, ratios of reduced (GSH) to oxidized (GSSG) glutathione were greater (P less than 0.05) in lungs of TNF/C + IL-1-injected rats (91 +/- 20) than of saline-injected rats (30 +/- 4) that had been exposed to hyperoxia for 52 h. No differences were found in superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, or catalase activities in lungs of TNF/C + IL-1- or saline-treated, hyperoxia-exposed rats. Our results indicate that pretreatment with TNF/C and IL-1 favorably altered lung glutathione redox status, decreased lung injury, and enhanced survival of rats exposed to hyperoxia.

I nhibition of Factor VIIa-tissue factor activity by a plasma component(s) that requires factor Xa has been described recently. In this communication, we have developed a specific radiometric assay (which utilizes 3H-Factor IX and is sensitive to less than 1% of plasma level) for this inhibitor and have measured its activity in various disease states. Strikingly, the levels of this inhibitor were found to be normal in patients with advanced chronic hepatocellular disease but low in patients with disseminated intravascular coagulation (DIC). When endotoxin was used to induce DIC in rabbits, the levels of this inhibitor fell by 25-90%. Human umbilical vein endothelial cells (HUVE), bovine pulmonary artery endothelial cells, and a human hepatoma cell line (HepG2) all synthesized and secreted this inhibitor, whereas a promyelocytic cell line (HL-60) did not and a monocytic cell line (U937) appears to synthesize only small amounts. When ammonium sulfate-fractionated human plasma and serum-free conditioned media from both HUVE and HepG2 cells were electrophoresed on sodium dodecyl sulfate acrylamide gels, two activity peaks corresponding to Mr approximately 45,000 and Mr approximately 33,000 were eluted in each case. These observations suggest that (a) the inhibitor is consumed in DIC and that (b) endothelial cells (or other cells) synthesize sufficient amounts of this inhibitor in vivo to compensate for any decreased production by liver cells.

T he role of tumor cell membrane gangliosides in tumor formation was probed using a series of cloned murine AKR lymphoma cell lines. Tumor formation was directly related to high expression and shedding of membrane gangliosides. In vivo, as little as 1 pmol of purified total gangliosides of highly tumorigenic cells, injected intradermally with poorly tumorigenic cells (which lacked and did not shed gangliosides), markedly increased the tumorigenicity of these cells in syngeneic normal mice. Thus, gangliosides shed by tumor cells are a previously unrecognized, extremely potent enhancer of tumor formation in vivo.

W e studied the effect of human immunodeficiency virus (HIV) infection on the surface-marker expression of the human promonocytic cell line U937. U937 cells persistently produced HIV as detected by reverse transcriptase activity in culture supernatant. Expression of HLA class II antigens on U937/HIV cells was decreased 2- to 10-fold, depending on the Mab used. Class II expression of U937/HIV cells increased approximately two-fold by treatment with r-interferon-gamma. Whereas noninfected U937 cells expressed moderate amounts of lymphocyte function-associated antigen-1 (LFA-1) (CD11a) and minimal amounts of the C3bi receptor (CD11b) and p150/95 (CD11c), U937/HIV cells expressed moderate amounts of C3bi receptor and p150/95 and showed elevated expression of LFA-1 alpha (CD11a) and -beta (CD18) chains. Expression of these adhesion molecules resulted in strongly enhanced phorbolester-induced aggregation of U937/HIV cells compared with the noninfected U937 cells. In addition, almost all U937/HIV cells, but not noninfected U937 cells, intensely stained for cytoplasmic nonspecific esterase activity. The effects of HIV infection on U937 cells strikingly resemble the effects of differentiation-inducing agents, such as PMA and DMSO, on the U937 phenotype. Our finding suggests that HIV infection, apart from down regulating class II expression, induces differentiation of U937 cells.