Enterotoxigenic Escherichia coli are associated with noninflammatory diarrhea and stimulate adenylate cyclase activity of mammalian cells, thereby increasing intracellular cyclic adenosine 3′,5′-monophosphate (cyclic AMP). Increased concentrations of cyclic AMP in polymorphonuclear neutrophils (PMN) inhibit phagocytosis, candidacidal activity, granule discharge, and chemotactic responsiveness. We examined the effect of enterotoxin on the interaction of human PMN with E. coli. Enterotoxigenic and nonenterotoxigenic strains, including serotypes of E. coli identical except for the presence or absence of the plasmid coding for enterotoxin production, were utilized. Enterotoxigenic and nonenterotoxigenic E. coli, tumbled with PMN, were phagocytized and killed (>97%) equally well, and these strains stimulated PMN hexose monophosphate shunt activity equivalently.
Mark J. Bergman, Richard L. Guerrant, Ferid Murad, Stephen H. Richardson, David Weaver, Gerald L. Mandell
In order to investigate the magnitude and kinetics of the C-reactive protein (CRP) response after differing degrees of tissue injury, we studied changes in serum concentration of this acute phase protein in 19 patients after mild or extensive acute myocardial infarction. An increase in serum CRP concentration was seen in all patients. The rate of increase in concentration was found to be exponential, with a mean hourly rate constant for the entire group of patients of 0.085 (doubling time, 8.2 h). Patients with extensive infarction attained mean serum CRP levels about 4 times as great as did patients with mild infarction. No difference could be shown in the mean rate constant between these groups, the greater CRP response in the former group resulting principally from a more protracted period of rise in serum CRP concentration. A lag period before serum CRP levels began to rise was noted in only 4 of the 13 patients in whom this could be assessed. 7 of 10 patients with presumed unstable angina (coronary insufficiency) showed no rise in CRP concentration, while a small increase as noted in 3 patients. The data suggest that acute tissue injury, such as myocardial infarction, rapidly leads to acceleration in synthesis of CRP, and that the duration of this period of acceleration is related to the extent of tissue injury.
Irving Kushner, Martin L. Broder, David Karp
Cell-mediated and humoral immune responses of mutant diabetic db+/db+ mice were evaluated using in vivo and in vitro immunological assays. When compared to lean, nondiabetic db+/m+ or m+/m+ mice, db+/db+ mice demonstrated markedly altered in vivo immune responses characterized by a significantly diminished ability to reject allogeneic skin grafts, a markedly diminished capacity to generate cytotoxic cells after sensitization with allogeneic EL-4 lymphoma cells and a significantly enhanced plaque-forming cell response to sheep erythrocytes. In contrast, spleen cells from db+/db+ mice demonstrated only minimal alterations in in vitro responses to mitogens and allogeneic cells and no alteration in their capacity to generate an in vitro plaque-forming cell response. The spleens and thymuses of db+/db+ mice weighed significantly less than organs from db+/db+ mice. In addition, thymuses from db+/db+ mice demonstrated a marked deficiency in in vivo [125I]UdR uptake. These data suggest that the altered metabolic status of the diabetic host influences immune function in vivo possibly due to abnormal function of lymphocyte subpopulations.
G Fernandes, B S Handwerger, E J Yunis, D M Brown
The membrane organization of the erythrocytes from patients with Duchenne muscular dystrophy was studied by means of electron spin resonance. The fluidity of the membrane near the polar region of Duchenne muscular dystrophy erythrocytes was similar to that of normal erythrocytes. The membrane environment in the nonpolar region, however, was quite different from that of normal erythrocytes, judged by the spectra with 2-(14-carboxytetradecyl) - 2 - ethyl - 4,4 - dimethyl - 3 - oxazolidinyloxyl as probe. The temperature dependence of the ratio of the line height of central field to that at the low field showed two inflection points in normal erythrocytes at pH 7.4 (13.5°-16.5° and 37.5°-40.5°C, respectively) but the inflection point in the lower temperature range was not detected in Duchenne muscular dystrophy erythrocytes. When pH was varied, an abrupt decrease in the ratio was observed at pH 5.9-5.6 in normal erythrocytes whereas there was a gradual decrease over the range of pH from 6.6 to 5.0 in Duchenne muscular dystrophy erythrocytes.
Bunzo Sato, Koichi Nishikida, Leo T. Samuels, Frank H. Tyler
The beige mouse, C57BL/6 (bg/bg), is an animal model for the Chediak-Higashi syndrome in man, a disease characterized morphologically by giant lysosomes in most cell types. Half-lives for the turnover of [14C]bicarbonate-labeled total soluble liver protein were determined in normal and beige mice. No significant differences were observed between the normal and mutant strain for both rapidly and slowly turning-over classes of proteins. Glucagon treatment during the time-course of protein degradation had similar effects on both normal and mutant strains and led to the conclusion that the rate of turnover of endogenous intracellular protein in the beige mouse liver does not differ from normal.
Robert T. Lyons, Henry C. Pitot
Adult rats show evidence of severe lung damage after 72h of continuous exposure to hyperoxia (96-98% O2). Treatment of adult rats with a solution of Plasmanate, inadvertently contaminated with endotoxin-producing organisms, or with purified endotoxin itself markedly altered the lung toxicity associated with hyperoxic exposure (survival in treated animals = 110/113 [97%] versus survival in untreated animals = 56/172 [33%]). After 72h of hyperoxic exposure, the endotoxin-treated rats demonstrated significant increases in lung superoxide dismutase, catalase, and glutathione peroxidase activity, a protectant enzyme response not seen in untreated adult rats. The basis for endotoxin's protective effect from hyperoxic lung damage is believed to be related to the stimulated increase in activity of the pulmonary antioxidant enzyme defense system. Some previously known actions of endotoxin are speculated to also serve a protective function by opposing some of the usual detrimental effects of high concentrations of O2 on the lung.
L Frank, J Yam, R J Roberts
Adult female (NZB + NZW)F1 mice were treated with cortisone, cortisone with tolerogen (isologous NZB IgG-nucleosides conjugates) or cortisone with isologous IgG free of nucleosides. Other treatments also included tolerogen or isologous IgG alone, and cortisone together with denatured DNA. All untreated mice died by 10 mo of age. Cortisone prolonged the survival rate. This effect was further improved by combined treatment of cortisone and tolerogen. Prolonged survival was accompanied by a decrease in proteinuria. Other treatments failed to influence either survival or proteinuria. Although cortisone did not prevent the appearance of antibody to denatured DNA, cortisone and tolerogen suppressed them in most of the animals. Preexisting antibody to denatured DNA was reduced by cortisone and cortisone and tolerogen, but not by cortisone and IgG. In contrast, antibody to native DNA bore no relationship to therapy. Animals living beyond 1 yr of age, regardless of the treatment, fall into three histopathological categories: (a) severe nephritis, as in untreated animals, (b) moderate nephritis (with absence of severe alteration of the glomerular basement membrane, i.e. the histological counterpart of prolonged survival), (c) minimal nephritis. In a small number of animals treated with cortisone or cortisone and IgG and in 6/20 animals treated with cortisone and tolerogen, minimal lesions as judged by light, fluorescent, and electron microscopy were found. These last mice were in good health at 15-16 mo of age, twice the life-span of untreated mice. In conclusion, these data suggest that tolerance to nucleic acid antigens facilitated by cortisone offers a promising new approach to treat established murine lupus nephritis.
Y Borel, R M Lewis, J André-Schwartz, B D Stollar, E Diener
As an ancillary part of a typhoid fever vaccine study, 10 healthy adult male volunteers (nonimmunized controls) were serially bled 6 days before to 30 days after ingesting 105Salmonella typhi organisms. Five persons developed typhoid fever 6-10 days after challenge, while five remained well. During the febrile illness, significant changes (P < 0.05) in the following hematological parameters were measured: a rise in α1-antitrypsin antigen concentration and high molecular weight kininogen clotting activity; a progressive decrease of platelet count (to 60% of the predisease state), functional prekallikrein (55%) and kallikrein inhibitor (47%) with a nadir reached on day 5 of the fever and a subsequent overshoot during convalescence. Despite the drop in functional prekallikrein and kallikrein inhibitor, there was no change in factor XII clotting activity or antigenic concentrations of prekallikrein and the kallikrein inhibitors, C1 esterase inhibitor (C1̄-INH) and α2-macroglobulin. Plasma from febrile patients subjected to immunoelectrophoresis and crossed immunoelectrophoresis contained a new complex displaying antigenic characteristics of both prekallikrein and C1̄-INH; the α2-macroglobulin, antithrombin III, and α1-antitrypsin immunoprecipitates were unchanged. Plasma drawn from infected-well subjects showed no significant change in these components of the kinin generating system. The finding of a reduction in functional prekallikrein and kallikrein inhibitor (C1̄-INH) and the formation of a kallikrein C1̄-INH complex is consistent with prekallikrein activation in typhoid fever. The correlation of these changes with the drop in platelet count suggests that a common mechanism may be responsible.
Robert W. Colman, Robert Edelman, Cheryl F. Scott, Robert H. Gilman
Previous studies showed that in rats with obstruction of the bile ducts draining the median and left hepatic lobes, and in rats with normal bile ducts in which the bile acid pool size and secretion were augmented by 48-h intraduodenal infusion of taurocholate, bile acid flux through secreting hepatocytes was increased. Under these conditions, taurocholate transport maximum exhibited a time-dependent adaptation to increased secretory load.
F-J. Wannagat, R. D. Adler, R. K. Ockner
Amino acids and peptides release gastrin and stimulate gastric acid secretion. However, the relation between gastrin release and acid secretory response is unclear. An isotonic mixed amino acid solution (casein hydrolysate) was continuously infused into the stomach of eight healthy human subjects. Acid secretion, measured by in vivo intragastric titration, increased 12.8 meq/h over the response to intragastric infusion of isotonic saline. Plasma gastrin heptadecapeptide (G-17) concentration, measured by specific radioimmunoassay, increased 13 pmol/liter during intragastric amino acid infusion.
Mark Feldman, John H. Walsh, Helen C. Wong, Charles T. Richardson
Aspirin inhibits platelet function by permanently acetylating the cyclooxygenase that forms prostaglandins. We determined the sensitivity of platelets to aspirin in normal subjects by measuring [3H-acetyl]aspirin-susceptible cyclooxygenase in washed platelets obtained at various times after aspirin ingestion. A single 325-mg aspirin dose inactivated 89% of platelet cyclooxygenase. The inhibition persisted for 2 days suggesting that oral aspirin also inactivated megakaryocyte cyclooxygenase. Thereafter, active enzyme returned with a time-course reflecting platelet turnover (life-span 8.2+/-2 days). Single doses of 20-650 mg aspirin resulted in 34- greater than 95% inhibition after 24 h. Daily doses of 20-325 mg aspirin for brief periods produced 61- greater than 95% inactivation when measured 24 h after cessation of the drug. Platelet cyclooxygenase is more sensitive to inactivation by aspirin than enzyme in sheep seminal vesicles.
J W Burch, N Stanford, P W Majerus
Very low density lipoproteins (VLDL) and low density lipoproteins (LDL) from human normolipemic plasma, and the VLDL, the intermediate density lipoprotein (IDL), and LDL from patients with Type III hyperlipoproteinemic plasma were tested for their abilities to suppress the activity of 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase in cultured human fibroblasts from normal subjects and a Type III patient. Regulation of cholesterol synthesis in the fibroblasts of a patient with Type III hyperlipoproteinemia appears to be normal. VLDL from normal subjects, isolated by angle head ultracentrifugation (d < 1.006) or by gel filtration on BioGel A-5m, were about 5 times less effective than LDL in suppressing HMG-CoA reductase activity, based on protein content, in agreement with previous reports with normal fibroblasts. Zonal centrifugation of normal VLDL isolated by both methods showed that the VLDL contained IDL. Normal VLDL from the angle head rotor, refractionated by the zonal method, had little, if any, ability to suppress the HMG-CoA reductase activity in either normal or Type III fibroblasts. VLDL, IDL, and LDL fractionated by zonal ultracentrifugation from Type III plasma gave half-maximum inhibition at 0.2-0.5 μg of protein/ml, indistinguishable from the suppression caused by normal LDL. Type III VLDL did not suppress HMG-CoA reductase in mutant LDL receptor-negative fibroblasts. Zonally isolated VLDL obtained from one Type IV and one Type V patient gave half-maximal suppression at 5 and 0.5 μg of protein/ml, respectively. Molecular diameters and apoprotein compositions of the zonally isolated normal and Type III VLDL were similar; the major difference in composition was that Type III VLDL contained more cholesteryl esters and less triglyceride than did normal VLDL. The compositions and diameters of the Type IV and Type V VLDL were similar to normal VLDL. These findings show that the basic defect in Type III hyperlipoproteinemia is qualitatively different from the cellular defect found in familial hypercholesterolemia, since the regulation of HMG-CoA reductase activity is normal in Type III fibroblasts. The metabolic defect in hypertriglyceridemia is related to the triglyceriderich lipoproteins which, free of other lipoproteins, have an enhanced ability to interact with cultured fibroblasts to regulate HMG-CoA reductase activity. These studies suggest that, in hypertriglyceridemia, there is a mechanism for direct cellular catabolism of VLDL which is not functional for normal VLDL.
Sandra H. Gianturco, Antonio M. Gotto Jr., Richard L. Jackson, Josef R. Patsch, Harley D. Sybers, O. David Taunton, Daniel L. Yeshurun, Louis C. Smith
Fasting leads to an increase in the ability of adipocytes to bind insulin, and this was accounted for by an increase in the affinity of the receptors for insulin without any change in the number of receptors per cell. Binding affinity can increase because of a decrease in the dissociation rate constant (kd), an increase in the association rate constant (ka), or both. Kinetic studies demonstrated that fasting leads to a striking decrease in the rate at which insulin dissociates from its receptor, and the near two-fold prolongation of the time at which 50% of the bound 125I-insulin dissociates (28±4 vs. 50±5 min) correlated quite well with the two-fold increase in binding affinity. On the other hand, the rate at which insulin associates with its receptor was essentially unchanged. Negatively cooperative interactions between receptors were readily demonstrated in cells from control and fasting animals, and the magnitude and sensitivity of this effect was the same in both groups of cells. It seemed likely that during fasting a change in the concentration of some substrate or hormone could lead to these effects on insulin binding. However, in vitro attempts to recreate the substrate and hormonal changes which occur in fasting produced no evidence to support this idea. In conclusion: (a) fasting leads to an increase in the ability of adipocytes to bind insulin because of an increase in binding affinity; (b) this increase in the affinity of the receptor for insulin was primarily accounted for by a decrease in the rate at which insulin dissociates from its receptors; and (c) fasting did not appreciably alter the negatively cooperative interactions displayed by adipocyte insulin receptors.
Jerrold M. Olefsky, Masashi Kobayashi
12 patients with pemphigus foliaceus, a form of pemphigus with lesions that arise in the intercellular substance in the superficial layers of the epidermis, and 7 patients with pemphigus vulgaris, where lesions are in the deep layers, were studied by immunofluorescence. Circulating antibodies to intercellular antigens (IC antibodies) were found in 11 pemphigus foliaceus and 5 pemphigus vulgaris patients. On direct immunofluorescence of skin lesions 75% (9 of 12), pemphigus foliaceus patients had intercellular deposits of IgG localized solely or predominantly in the superficial epidermal layers, whereas this was not the case in any of the patients with pemphigus vulgaris. Over 70% of the pemphigus foliaceus patients with predominantly superficial IgG deposits lacked in their lesions normal intercellular antigens usually expressed in the deep layers of the epidermis. This was shown by the inability of IC antibodies in autologous or allogeneic sera to bind to intercellular antigens in the lower epidermis of patient's skin, even though the same sera could bind to intercellular antigens in all layers of normal allogeneic skin. Lack of normal intercellular antigens deep in the epidermis may result in circulating IC antibodies binding to the superficial layers, a site which corresponds to, and thus in some patients may account for, the anatomical location of lesions in pemphigus foliaceus.
Jean-Claude Bystryn, Jose Rodriguez
Large forms of Candida are characteristically present in invasive lesions and are often cleared by host defenses. Therefore, an in vitro system was developed to study interactions between leukocytes and pseudohyphae. By light, phase contrast, and electron microscopic observations, in the absence of serum, neutrophils attached to and spread over the surfaces of partially ingested pseudohyphae, which then appeared damaged. Using a new assay which measured neutrophil-induced inhibition of uptake of [14C]cytosine by Candida, damage to Candida in the absence of serum was 53.04±2.96% by neutrophils from 27 normal subjects. With serum, damage to Candida increased because of opsonization by low levels of anti-Candida immunoglobulin G in normal sera. Damage to Candida was inhibited by colchicine, cytochalasin B, and 2-deoxyglucose, which interfered with spreading of neutrophils over the surfaces of Candida. Dibutyryl cyclic AMP, theophylline, and isoproterenol also inhibited damage to Candida. Hydrocortisone was inhibitory in levels (10 μM) achievable with pharmacologic doses in man. Light, fluorescence, and electron microscopy indicated that neutrophils degranulated after contact with Candida. Quantitative studies revealed only a minimal increase in specific release of lysosomal enzymes from azurophil granules, but much greater release of lysozyme from specific granules. Candida activated neutrophil oxidative microbicidal mechanisms, as shown by iodination of Candida by neutrophils, and chemiluminescence from neutrophils interacting with Candida. Unlike live Candida, killed Candida did not induce chemiluminescence, were not iodinated, and did not attach to neutrophils by microscopy. Like Candida pseudohyphae, contact between neutrophils and hyphal forms of Aspergillus and Rhizopus occurred in the absence of serum. This did not occur with Cryptococcus neoformans, an encapsulated yeast, and was low with Candida yeasts. These findings indicate that neutrophils can recognize and attach to Candida pseudohyphae, then damage the Candida. This may represent a general reaction between neutrophils and large forms of fungi. Though the size of the organisms precludes complete ingestion, neutrophil oxidative microbicidal mechanisms are activated, and preferential release of contents of specific granules appears to occur.
Richard D. Diamond, Raymond Krzesicki, Wellington Jao
Mechanisms were studied that might explain the attachment and damage to Candida albicans pseudohyphae by neutrophils in the absence of serum. Attachment of neutrophils to pseudo hyphae was inhibited by Candida mannans (1-10 mg/ml), but not by mannose, dextran, chitin, conconavalin A, or highly charged polyamino acids. Contact was also inhibited by pretreatment of Candida before incubation with neutrophils with chymotrypsin, but not trypsin or several inhibitors of proteases. Similar results were obtained with pretreatment of neutrophils, except that trypsin was inhibitory. When pseudohyphae were killed with ultraviolet light, proteinpolysaccharide complexes of mol wt <10,000 were released which appeared to bind to the surfaces of neutrophils and inhibit contact between neutrophils and Candida, as well as other fungi.
Richard D. Diamond, Raymond Krzesicki
The action of histamine, carbamylcholine, and gastrin on oxygen uptake by cells isolated from canine fundic mucosa was studied in vitro. Viable mucosal cells were prepared by exposure of separated mucosa sequentially to collagenase and EDTA. Oxygen consumption, determined by polarography, was chosen as an index of physiological response of mucosal cells to secretagogues.
Andrew H. Soll
Using oxygen uptake as an index of the physiological response of isolated parietal cells, the interactions between histamine and gastrin and between histamine and carbamylcholine and the effects of atropine and metiamide on these interactions have been studied. Parietal cells were isolated from canine fundic mucosa by sequential exposure of separated mucosa to collagenase and EDTA. In previous studies carbamylcholine, isobutyl methyl xanthine, gastrin, and histamine have each been shown to increase oxygen uptake by these cells. Isobutyl methyl xanthine greatly enhanced the histamine effect. Carbamylcholine was inhibited by atropine but not by metiamide, histamine was inhibited by metiamide but not by atropine, and gastrin was inhibited by neither, suggesting that each of these agents has a direct action on the parietal cell. In the present studies, potentiating interactions between histamine and carbamylcholine and between histamine and gastrin have been demonstrated. Against a histamine (0.1 and 1 μM) plus isobutyl methyl xanthine (0.1 mM) background, the dose for 50% response for gastrin was approximately 1 nM, and the maximal response was obtained at 0.1 μM. When added to these combinations of stimulants, metiamide and atropine retained their respective specificities against stimulation by histamine and carbamylcholine, in that responses were inhibited to the level that was seen when the component of the pair that was not inhibited was given alone.
Andrew H. Soll
Secondary amyloidosis is a complication of diseases characterized by recurrent acute inflammation. In this study, a standardized stimulus which induced fever and inflammation was given to six normal subjects (19-24 yr old) to follow the fluctuation in concentration of serum amyloid A (SAA), the precursor of the secondary amyloid fibril protein. After a single intramuscular injection of etiocholanolone (0.3 mg/kg), blood samples were drawn twice a day for 12 days for determination of SAA by solid phase radioimmunoassay. From a base line of <100 μg/ml, the SAA concentration began rising within 12 h to a maximum value at about 48 h of 1,350-1,800 μg/ml in three males and 380-900 μg/ml in three females and returned to base line by 4-5 days. The SAA response showed a similar time response to C-reactive protein (CRP), a well-documented acute phase protein which was assayed semiquantitatively by capillary tube precipitin reaction. CRP, but not SAA, showed a quantitative correlation with the amount of fever induced by etiocholanolone. One subject exhibited a second rise in SAA and CRP concentrations after acute over-indulgence with alcohol, suggesting that acute liver damage may have caused an acute phase reaction. Thus, a controlled episode of fever and inflammation produced a prompt and prolonged elevation of SAA and CRP concentrations. Unlike SAA, CRP has not been implicated in the pathogenesis of amyloidosis, although its relationship to the P component of amyloid has recently been established.
Keith P. W. J. McAdam
Binding of [3H]dihydroergocryptine to platelet lysates appears to have all the characteristics of binding to α-adrenergic receptors. At 25°C binding reaches equilibrium within 20 min and is reversible upon addition of excess phentolamine. Binding is saturable with 183±22 fmol of [3H]dihydroergocryptine bound per mg of protein at saturation, corresponding to 220±26 sites per platelet. Kinetic and equilibrium studies indicate the dissociation constant of [3H]dihydroergocryptine for the receptors is 1-3 nM. The specificity of the binding sites is typical of an α-adrenergic receptor. Catecholamine agonists compete for occupancy of the [3H]dihydroergocryptine binding sites with an order of potency (−)epinephrine> (−)norepinephrine≫ (−)isoproterenol. Stereospecificity was demonstrated inasmuch as the (+)isomers of epinephrine and norepinephrine were 10-20-fold less potent than the (−)isomers. The potent α-adrenergic antagonists phentolamine, phenoxybenzamine, and yohimbine competed potently for the sites, whereas β-antagonists such as propranolol and dichlorisoproterenol were quite weak. Dopamine and serotonin competed only at high concentrations (0.1 mM).
Kurt D. Newman, Lewis T. Williams, N. Hahr Bishopric, Robert J. Lefkowitz
In order to evaluate the importance of suppuration, persistent infection, and scar formation in the evolution of Escherichia coli chronic pyelonephritis, we treated rats with different antibiotic regimens at different stages of the disease. The results show that (a) if acute suppurative pyelonephritis is aborted with early antibiotic therapy, chronic pyelonephritis is prevented; (b) chronic pyelonephritis can develop even after eradication of infection if acute suppuration persists beyond 3 days; (c) persistent infection does not lead to chronic pyelonephritis, if the acute suppuration is suppressed; and (d) residual infection, antigen-load, antibody, and(or) cell-dependent autoimmune processes did not play a significant role. We interpret these results as evidence that the pathologic entity recognized as chronic pyelonephritis results from kidney damage, scarring and shrinkage secondary to acute suppuration.
M P Glauser, J M Lyons, A I Braude
The present report has presented the first clear evidence in man for the existence of specific hepatic cholesterol precursor sites associated with the formation and secretion of bile acids and biliary cholesterol. These hepatic compartments derive virtually all their cholesterol from newly synthesized and lipoprotein free cholesterol. The model which is presented was formulated on current concepts of cholesterol metabolism in man and is concerned, at this initial stage, with the elucidation of the bile acid and biliary cholesterol compartments. The complexity of cholesterol metabolism in man necessitated an initial approach that would minimize the number of inputs of cholesterol into the system, allow for the sampling of several cholesterol compartments, and permit the simultaneous labeling of newly synthesized cholesterol and preformed cholesterol. To achieve these objectives, we studied the patient with a total bile fistula. Six patients were administered simultaneously pulse injections of labeled mevalonic acid and [14C]cholesterol. The qualitative features of the specific activity time course curves after labeled mevalonic acid revealed no precursor-product relationship between bile acid, biliary cholesterol, and plasma free cholesterol. The peak specific activity of the bile acids was reached in approximately 100 min and was higher than the biliary cholesterol, which was higher than the plasma free cholesterol. The plasma free cholesterol specific activity became higher than the other lipids after 12 h and remained higher throughout the period of study. Similar related observations were made with [14C]cholesterol. The data were then subjected to simulation analysis and modeling using the SAAM-27 computer program. Computer least-square fits of the data were obtained after the model was evolved. During the model development, the least number of compartments and transport pathways were introduced consistent with a good fit of the data. Of particular importance was the constraint that the model fit the data obtained from both [14C]cholesterol and labeled mevalonic acid. The same parameter values were used to fit the data from both tracers. The fluxes arrived at in the model indicate that 31% and 20%, respectively, of the cholesterol input into the bile acid and biliary cholesterol precursor sites were derived directly from the newly synthesized hepatic cholesterol. The remainder had its origin predominantly from lipoprotein free cholesterol. Plasma esterified cholesterol (as free) made a small contribution (11%) to the bile acid compartment. Similarly, 10% of the biliary cholesterol arose from an unknown hepatic site.
Charles C. Schwartz, Mones Berman, Z. R. Vlahcevic, L. Gregg Halloran, Daniel H. Gregory, Leon Swell
Plasma ACTH and corticosteroid concentrations were measured by radioimmunoassay in chronically catheterized fetuses of 32 pregnant sheep. Fetal plasma ACTH levels 38±5 pg/ml (means±SEM) were slightly (P < 0.05) lower than maternal 54±4 pg/ml levels. No general rise in fetal plasma ACTH concentration was noted before 140 days gestation; however, fetal plasma corticoid levels began to increase after about 125 days. This suggested that an increase in fetal adrenal responsiveness to endogenous ACTH occurred during gestation.
James C. Rose, Alastair A. Macdonald, Michael A. Heymann, Abraham M. Rudolph
We examined the degree of airway obstruction that developed in eight asthmatics who exercised while breathing air under four conditions: (a) ambient room temperature and water content; (b) body temperature and ambient water content; (c) ambient room temperature fully saturated; and (d) body temperature fully saturated. These test conditions were performed in random order. Multiple aspects of pulmonary mechanics were measured before and 5 min after exercise. When air at ambient conditions was inhaled, the expected airway obstruction developed after exercise, and all variables changes significantly from their pre-challenge values. Heating the air to body temperature did not influence this response. Increasing the humidity at ambient temperatures significantly blunted the response, and by inhaling body temperature, fully saturated air completely prevented it from occurring. Thus, the water content of inspired air is an important variable in the development of exercise induced asthma.
R H Strauss, E R McFadden Jr, R H Ingram Jr, E C Deal Jr, J J Jaeger
The physiological role of thyrotropin-releasing hormone (TRH) in the regulation of thyrotropin (thyroid-stimulating hormone, TSH) and prolactin (Prl) secretion has been assumed but not proven. Stimulation of their release requires pharmacologic doses of TRH. Lesions of the hypothalamus usually induce an inhibition of TSH secretion and an increase in Prl. To determine whether TRH is essential for TSH and Prl secretion in the rat, 0.1 ml of TRH antiserum (TRH-Ab) or normal rabbit serum was administered to normal, thyroidectomized, cold-exposed, and proestrus rats through indwelling atrial catheter. Serum samples were obtained before and at frequent intervals thereafter. Serum TSH concentrations in normal, thyroidectomized, cold-exposed, and proestrus rats were not depressed in specimens obtained up to 24 h after injection of normal rabbit serum. In contrast, serum TSH was significantly decreased after the administration of TRH-Ab in all normal (basal, 41±8 μU/ml [mean±SE]; 30 min, 6±2; 45 min, 8±3; 75 min, 4±2); thyroidectomized (basal, 642±32 μU/ml; 30 min, 418±32; 60 min, 426±36; 120 min, 516±146); coldstressed (basal, 68±19 μU/ml; 30 min, 4±3; 180 min, 16±8); and proestrus (basal, 11 a.m., 57±10 μU/ml; 1 p.m., 20±3; 3 p.m., 13±4; 5 p.m., 19±3) rats. However, 0.1 ml of TRH-Ab had no effect on basal Prl concentrations in normal or thyroidectomized rats and did not prevent the Prl rise in rats exposed to cold (basal, 68±7 ng/ml; 15 min, 387±121; 30 min, 212±132; 60 min, 154±114), or the Prl surge observed on the afternoon of proestrus (basal 11 a.m., 23±2 ng/ml; 1 p.m., 189±55; 3 p.m., 1,490±260; 5 p.m., 1,570±286). These studies demonstrate that TRH is required for TSH secretion in the normal, cold-exposed and proestrus rat and contributes, at least in part, to TSH secretion in the hypothyroid rat, but is not required for Prl secretion in these states.
Arthur R. C. Harris, Dana Christianson, M. Susan Smith, Shih-Lieh Fang, Lewis E. Braverman, Apostolos G. Vagenakis
Immunoreactive calcitonin released by a medullary thyroid carcinoma in tissue culture has been found to exhibit heterogeneity when analyzed by gel chromatography and radioimmunoassay, in a pattern analogous to that seen in the circulation of the patient from whom the neoplasm was removed. To examine the cause of the heterogeneity, the immunoreactive material released by the tumor into tissue culture medium was further analyzed by gel electrophoresis in the presence of the protein denaturant 8 M urea, by gel chromatography after reduction and alkylation, by affinity chromatography on concanavalin A-agarose, and by bioassay in a renal adenylyl cyclase system of enhanced sensitivity. The results suggest that the larger immunochemical forms of calcitonin described in the circulation of patients with medullary thyroid carcinoma may be released directly from the neoplasm and need not derive from peripheral metabolism of the monomer. It could be demonstrated that a major proportion of the immunochemical enlargement is dependent upon intermolecular disulfide bridge formation whereas aggregation or non-convalent protein binding account for a smaller component of the heterogeneity. In view of the absence of binding of the immunoreactive material to the lectin agarose, carbohydrate side chains, at least of the α-d glucosyl variety, do not seem to contribute significantly to calcitonin enlargement. Additionally, the studies indicate that, at least by in vitro assay, the larger immunochemical forms of calcitonin, representing the majority of the immunoreactivity released by a medullary thyroid carcinoma, are biologically inactive.
To investigate mechanisms of extrathyroidal thyroid hormone metabolism, conversion of thyroxine (T4) to 3,5,3′-triiodothyronine (T3) and degradation of 3,3′,5′-triiodothyronine (rT3) were studied in rat liver homogenates. Both reactions were enzymatic. For conversion of T4 to T3, the Km of T4 was 7.7 μM, and the Vmax was 0.13 pmol T3/min per mg protein. For rT3 degradation, the Km of rT3 was 7.5 nM, and the Vmax was 0.36 pmol rT3/min per mg protein. Production of rT3 or degradation of T4 or T3 was not detected under the conditions employed. rT3 was a potent competitive inhibitor of T4 to T3 conversion with a Ki of 4.5 nM; 3,3′-diiodothyronine was a less potent inhibitor of this reaction. T4 was a competitive inhibitor of rT3 degradation with a Ki of 10.2 μM. Agents which inhibited both reactions included propylthiouracil, which appeared to be an allosteric inhibitor, 2,4-dinitrophenol, and iopanoic acid. Sodium diatrizoate had a weak inhibitory effect. No inhibition was found with α-methylparatyrosine, Fe+2, Fe+3, reduced glutathione, β-hydroxybutyrate, or oleic acid.
Michael M. Kaplan, Robert D. Utiger
To examine the role of basal insulin and glucagon secretion in potassium and sodium homeostasis, somatostatin, a potent inhibitor of insulin and glucagon secretion, was infused for 5 h into healthy human subjects, maturity-onset diabetes, juvenile-onset diabetics, and normal dogs. Infusion of somatostatin resulted in an increase in serum potassium (0.5-0.6 meq/liter) in normal subjects and maturity-onset diabetics, but not in juvenile-onset diabetics despite equivalent reductions in plasma glucagon in all three groups. A similar rise in serum potassium was observed in normal conscious dogs given somatostatin and was reversed by insulin replacement. Urinary excretion of potassium was unaffected by somatostatin.
Ralph A. Defronzo, Robert S. Sherwin, Mark Dillingham, Rosa Hendler, William V. Tamborlane, Philip Felig
The oxidative metabolism of monocytes and polymorphonuclear leukocytes from human peripheral blood was studied in resting and phagocytosing cells. Monocytes, like neutrophils, showed an increase in oxygen consumption during phagocytosis with a concurrent release of superoxide anions and hydrogen peroxide. Both oxygen products are highly reactive agents with potential bactericidal activity. Neutrophils consumed two and a half times as much oxygen, generated about twice as much superoxide, and released five times as much hydrogen peroxide as monocytes did. Monocytes generated superoxide and hydrogen peroxide at equivalent rates.
Michael Reiss, Dirk Roos
To explore the etiology of congenital hypoplastic anemia (CHA) or the Diamond-Blackfan anemia, erythropoietin responsive committed erythroid precursors were enumerated by the plasma clot method. These included blood and marrow erythroid burst-forming units (BFU-E) and marrow erythroid colony-forming units (CFU-E). The peripheral blood nucleated cells of 11 patients and the marrow cells of seven of these patients were examined. Studies were repeated in several patients during relapse and after induction of remission. BFU-E were undetectable in the marrow and blood of all but one relapsed patient, and the numbers of marrow CFU-E were depressed in all relapsed patients. Blood BFU-E remained low in all of the patients in remission. No evidence was obtained for suppression of normal CFU-E or BFU-E by CHA lymphocytes. Erythropoietin dose-response curves performed in two patients revealed a 10-fold increase in erythropoietin requirement for marrow CFU-E colony growth. This marked unresponsiveness to erythropoietin was strikingly improved by steroid therapy in one patient. We suggest that CHA is the result of a qualitative and/or quantitative deficiency of BFU-E. If BFU-E are produced, they must be relatively unresponsive to erythropoietin. The abnormal BFU-E give rise to erythropoietin unresponsive CFU-E and, thence, to proerythroblasts that are, in turn, trapped in that early stage of development because of their poor erythropoietic response. Hence, red cell production is deficient. Steroids appear to improve the erythropoietin response of CHA erythroid precursors.
David G. Nathan, Bryan J. Clarke, Diane G. Hillman, Blanche P. Alter, David E. Housman
A 50% reduction in the activity of uroporphyrinogen-I (URO) synthase in liver, erythrocytes, and cultured skin fibroblasts characterizes all patients with clinically active acute intermittent porphyria (AIP). The same enzyme defect has also been demonstrated in the erythrocytes and skin fibroblasts of completely latent gene carriers of this disorder and presumably exists in the liver as well.
Shigeru Sassa, Gregory L. Zalar, Attallah Kappas
Growth was evaluated in a group of 10 infants and children with familial or idiopathic classic renal tubular acidosis in whom alkali therapy was initiated at ages ranging from 8 days to 9.5 yr and administered at dosage schedules documented to sustain correction of acidosis in at least four prolonged observation periods on the Pediatric Clinical Research Ward. When alkali therapy was begun, six patients (four infants and two children) were stunted (height <2.5 SD below mean). Of the four who were not, two infants were too young (<2 wk of age) to have become stunted, and two children had been documented earlier to be nonacidotic. At the start of alkali therapy, the heights of the patients correlated inversely with the maximal possible duration of prior acidosis.
Elisabeth McSherry, R. Curtis Morris Jr.
High density lipoprotein was isolated from pooled rat serum and mesenteric lymph of lymph fistula rats. In most experiments, 5,5′-dithionitrobenzoic acid, an inhibitor of the enzyme lecithin:cholesterol acyltransferase, was added during the collection of lymph to prevent modification of the lipid composition of newly secreted lipoproteins. Negative staining electron microscopy of lymph high density lipoprotein revealed discoidal particles (190±3 × 55±1 Å) which tended to form rouleaux, smaller spherical particles were also present. Serum high density lipoprotein contained only spherical particles (diameter 93±4 Å). Lipid analysis showed that lymph high density lipoprotein was enriched in phospholipid and deficient in cholesterol esters when compared to serum high density lipoprotein. The phospholipid to cholesterol esters ratio was greatest in basal lymph high density lipoprotein when compared to fatty lymph and serum high density lipoprotein. From analysis of the lipid compositional data and direct particle measurement by electron microscopy, it could be determined that ≅50% of basal lymph high density lipoprotein and 30% of fatty lymph high density lipoprotein was discoid. Basal lymph high density lipoprotein was enriched in apoA-I and deficient in the arginine-rich peptide, and the apoprotein composition of fatty lymph high density lipoprotein more closely resembled serum. These observations demonstrate that intestinal lymph contains two types of high density lipoprotein particles, a discoid nascent particle deficient in cholesterol ester and rich in apoA-I, and spherical high density lipoprotein derived from plasma. A significant amount of lymph high density lipoprotein appears to be secreted by the intestine.
P. H. R. Green, A. R. Tall, R. M. Glickman
To evaluate the possibility that the carbohydrate composition of fibrinogen may be altered in the dysfibrinogenemia associated with liver disease, we studied the sialic acid content of purified fibrinogen from 12 patients with liver disease and its relationship to the prolongation of the thrombin time. Purified fibrinogen showed that Aalpha-, Bbeta-, and gamma-chains when reduced and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and exhibited prolongation of the thrombin time similar to that of the plasma from which it was derived. Sialic acid content of the purified fibrinogen ranged from 12.7 to 71.4% higher in patient fibrinogens when compared to normal controls. A progressive delay in thrombin time was associated with increasing sialic acid content of the patient fibrinogen. Enzymatic removal of sialic acid from four of the abnormal fibrinogens resulted in a shortening of their thrombin times to the range of the desialylated normal control. Periodic acid-Schiff reagent stained only the Bbeta- and gamma-chains of the reduced patient fibrinogens after sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggesting that the excess sialic acid is located on these two chains. These studies demonstrate a biochemical alteration of the functionally abnormal fibrinogen found in some patients with liver disease, and indicate that the excess sialic acid plays an important role in the functional defect of this protein.
J Martinez, J E Palascak, D Kwasniak