Postnatal Fetal and Adult Hemoglobin Synthesis in Early Preterm Newborn Infants

• Text
• PDF

Abstract

Studies were carried out during the postnatal period in infants born at or before the 32nd wk of gestation to determine the proportion of fetal hemoglobin (Hb F) and adult hemoglobin (Hb A) being synthesized, and to compare these studies to those previously reported on at birth from normal newborn infants 25-43 wk gestation. When the pretern infants reached the postconceptional age corresponding to term, their Hb A and Hb F synthesis was compared to a group of newborn infants at term. 53 blood samples from 25 preterm and 11 full-term infants were incubated in an amino acid mixture containing [14C]leucine, and column-chromatographed on DEAE-Sephadex for separation of Hb F and Hb A fractions. The completeness of the DEAE-Sephadex separation of Hb F and Hb A was confirmed by globin chain chromatography with the use of carboxymethylcellulose. The rate of transition from Hb F to Hb A synthesis postnatally in the preterm infants resembled that reflecting the in utero transition. At the postconceptional age corresponding to term, there was no difference in the relative amounts of Hb F and Hb A being synthesized by the preterm infants and by the term infants. The birth process did not alter the rate of transition from Hb F to Hb A.

Authors

Harry Bard

Metabolism of L-Thyroxine by Phagocytosing Human Leukocytes

• Text
• PDF

Abstract

Intact normal human leukocytes deiodinated L-thyroxine (T4) with the generation of inorganic iodide, chromatographically immobile origin material, and small quantities of L-triiodothyronine (T3). When phagocytosis was induced in the leukocytes through the addition of zymosan particles that had been opsonized by coating with plasma, T4-deiodination was greatly stimulated. In addition to the stimulation of T4-deiodination, the accumulation by the leukocytes of undegraded T4 was increased. Anoxia, which has previously been shown not to interfere with phagocytosis, did not prevent the increased cellular accumulation of T4 that phagocytosis induced, but virtually abolished T4-deiodination. On the other hand, calcium, which has previously been shown to be required for optimal phagocytosis, was required for the increase in both the cellular accumulation and deiodination of T4 that phagocytosis induced. Phospholipase-C, which has previously been shown to induce a metabolic burst that mimics that induced by phagocytosis, did not increase the cellular accumulation or deiodination of T4. On the other hand, colchicine, which has previously been shown to depress the metabolic burst that accompanies phagocytosis, did not prevent the increase in either the cellular accumulation or deiodination of T4 that phagocytosis induced. Thus, increased accumulation of T4 by the leukocytes during phagocytosis appears to be the primary factor responsible for the stimulation of deiodination that phagocytosis induces. The increased accumulation of T4 did not appear to be owing to engulfment of suspending medium surrounding the particles or to binding of T4 to the particles themselves. In addition to the enhanced cellular accumulation, other factors related to the metabolic burst that accompanies phagocytosis might also be involved in the stimulation of T4-deiodination. In leukocytes from two patients with chronic granulomatous disease, a disorder in which phagocytosis appears to occur normally but in which the metabolic burst and attendant increase in hydrogen peroxide generation do not occur, stimulation of T4-deiodination was either greatly diminished or totally lacking. In myeloperoxidase-deficient leukocytes, on the other hand, stimulation of T4-deiodination was at least as great as that in normal cells. Thus, we conclude that the primary factor responsible for the increased deiodination of T4 that phagocytosis induces is the enhanced cellular uptake of hormone. The increased generation of hydrogen peroxide that accompanies phagocytosis may be necessary for the enhanced deiodination of the accumulated T4, but the latter reaction does not require the mediation of myeloperoxidase.

Authors

Kenneth A. Woeber, Sidney H. Ingbar

Threshold Methotrexate Concentration for In Vivo Inhibition of DNA Synthesis in Normal and Tumorous Target Tissues

• Text
• PDF

Abstract

The suppression of DNA synthesis in host and tumor tissues by methotrexate has been monitored in mice by determining the in vivo incorporation of tritium-labeled deoxyuridine ([3H]UdR) into DNA. The duration of inhibition of [3H]UdR incorporation in normal tissues was related to the dose of methotrexate and was a direct function of plasma drug concentration. [3H]UdR incorporation recovered to 50% of pretreatment levels in bone marrow when plasma methotrexate concentration was 10-8 M or less, irrespective of the dose administered, while 50% recovery of DNA synthesis in intestinal epithelium was not observed until plasma methotrexate levels were 5 × 10-9 M or less. Ascitic L1210 leukemia cells did not fully return to pretreatment levels of [3H]UdR incorporation at any time, although a partial recovery of incorporation was noted at methotrexate ascitic fluid concentrations of approximately 10-8 M.

Authors

Bruce A. Chabner, Robert C. Young

Attenuation of the Ventilatory and Heart Rate Responses to Hypoxia and Hypercapnia with Aging in Normal Men

• Text
• PDF

Abstract

The response of ventilation and of heart rate to hypoxia and hypercapnia was determined in eight young normal men age 22-30 yr and eight elderly men age 64-73. The elderly men were selected and carefully screened to eliminate the possibility of cardiopulmonary disease. All the subjects were born at low altitude and had no significant prior exposure to hypoxia. The ventilatory response to hypoxia was measured as the exponential slope constant. k, of regression lines relating the logarithm of incremental ventilation to PAo2 during isocapnic progressive hypoxia. The heart rate response to hypoxia was measured as the percentage change in heart rate between PAo2 = 100 and PAo2 = 40 mm Hg. The ventilatory response to hypercapnia was measured as the slope of regression lines relating ventilation to PAco2 during rebreathing with PAo2 > 200 mm Hg. The heart rate response to hypercapnia was measured as the percentage change in heart rate between control values at the start of the rebreathing test and PACO2 = 55 mm Hg.

Authors

Richard S. Kronenberg, Charles W. Drage

Effects of Digoxin-Specific Antibodies on Accumulation and Binding of Digoxin by Human Erythrocytes

• Text
• PDF

Abstract

The present studies indicate that accumulation of digoxin by intact human erythrocytes is the result of two processes: binding of digoxin to the erythrocyte membrane and uptake of digoxin across the membrane into the cell. In contrast, accumulation of ouabain by human erythrocytes is entirely attributable to binding of this glycoside to the plasma membrane. Digoxin binding to the erythrocyte membrane involves a single class of binding sites, is a saturable function of the extracellular digoxin concentration, reversible, temperature-sensitive, dependent on the cation composition of the incubation medium, inhibited by other cardioactive steroids, and correlates with the inhibition of erythrocyte potassium influx. Digoxin uptake across the membrane into the cell is also temperature-sensitive and reversible but is a linear function of the extracellular digoxin concentration, not altered by changes in the cation composition of the incubation medium, not inhibited by other cardioactive steroids, and does not correlate with inhibition of erythrocyte potassium influx. Digoxinspecific antibodies can both prevent and reverse effects of digoxin on potassium influx in human erythrocytes by virtue of the capacity of the antibodies to decrease the amount of digoxin that is bound to the erythrocyte membrane. These antibodies also reduce uptake of digoxin across the plasma membrane into the erythrocyte; however, this portion of cellular digoxin is not responsible for the observed inhibition of potassium influx. In the presence of digoxin-specific antibodies, the changes in digoxin binding to the erythrocyte membrane and in digoxin uptake across the membrane into the cell reflect the ability of the antibodies to form complexes with “free” digoxin molecules in the incubation medium and thereby decrease the effective concentration of digoxin.

Authors

Jerry D. Gardner, Diane R. Kiino, Timothy J. Swartz, Vincent P. Butler Jr.

Histamine Release Induced by Human Leukocyte Lysates REABSORPTION OF PREVIOUSLY RELEASED HISTAMINE AFTER EXPOSURE TO CYCLIC AMP-ACTIVE AGENTS

• Text
• PDF

Abstract

The role of cyclic AMP in histamine release induced by human leukocyte lysates was investigated. Leukocytes were incubated with leukocyte lysates prepared by ultrasonic disruption, and histamine was determined fluorimetrically. Several cyclic AMP-active agents had a marked inhibitory effect on histamine release. Theophylline and isoproterenol produced 50% inhibition at concentrations of less than 10-5 M. Prostaglandin E1 and dibutyryl cyclic AMP inhibited release by 50% at 7 × 10-8 M and 6 × 10-5 M concentrations, respectively. Histamine, which has recently been shown to increase leukocyte cyclic AMP, had a pronounced inhibitory effect on lysate-induced histamine release, producing 50% inhibition at a concentration of only 2.5 × 10-12 M.

Authors

Michael T. Kelly, Arthur White

Neural Control of Counter-Regulatory Events during Glucopenia in Man

• Text
• PDF

Abstract

The effect of autonomic denervation on the metabolic and hormonal responses during intracellular glucopenia in man was investigated. 2-Deoxy-d-glucose (2 DG), a competitive inhibitor of glucose metabolism, was administered intravenously to nine normal volunteers and to five patients, three with complete cervical cord transection (C-6) and two with idiopathic orthostatic hypotension. Before, during, and after a 20 min infusion of 2 DG (50 mg/kg) plasma concentrations of glucose, lactate, FFA, total catecholamines, immunoreactive insulin (IRI), human growth hormone (HGH), and cortisol were determined for periods up to 150 min. In control subjects, the initial elevation of FFA, glucose. HGH, and cortisol corresponded with the rise in total catecholamines, with maximal levels attained at 60 min, lactate rose at a slower rate, reaching peak levels at 150 min: although no change in IRI was noted. In contrast, 2 DG-induced glucopenic stress in the autonomic denervated subjects was characterized by no detectable catecholamine release or significant rise in glucose, FFA, lactate, or IRI. However, HGH and cortisol responses in four of the five patients were of a similar or greater magnitude than controls.

Authors

Robert G. Brodows, F. Xavier Pi-Sunyer, Robert G. Campbell

Ouabain Binding and Cation Transport in Human Erythrocytes

• Text
• PDF

Abstract

In the present studies we have explored the relation between ouabain binding and the inhibition of potassium influx in intact human erythrocytes. The rate at which bound ouabain molecules dissociate from the erythrocyte membrane is not altered by complete replacement of choline with sodium or by partial replacement with potassium. These findings indicate that the effects of these cations on ouabain binding reflect alterations in the rate of association of ouabain molecules with the erythrocyte membrane. Variations in the cation composition of the incubation solution did not alter the relation between the fraction of the glycosidebinding sites occupied by ouabain or the fraction of ouabain-sensitive potassium influx which was inhibited. That is, irrespective of the affinity of the erythrocyte membrane for ouabain molecules and irrespective of the magnitude of glycoside-sensitive potassium influx, occupation of a given fraction of the glycoside-binding sites by ouabain results in the inhibition of an equal fraction of the ouabain-sensitive potassium transport sites.

Authors

Jerry D. Gardner, Diane R. Kiino

Use of Inert Gases to Study the Interaction of Blood Flow and Diffusion during Passive Absorption from the Gastrointestinal Tract of the Rat

• Text
• PDF

Abstract

Measurement of the relative absorption rates of inert gases (H2, He, CH4, SF6, and 133Xe) was used to investigate the interaction between diffusion and blood flow during passive absorption from the stomach, small bowel, and colon of the rat. If uptake is blood flow limited, the gases should be absorbed in proportion to their solubilities in blood, but if diffusion limited, uptake should be proportional to the diffusion rate of the gases in mucosal tissues.

Authors

Michael D. Levitt, David G. Levitt

Measurement of Inorganic Pyrophosphate in Biological Fluids, ELEVATED LEVELS IN SOME PATIENTS WITH OSTEOARTHRITIS, PSEUDOGOUT, ACROMEGALY, AND UREMIA

• Text
• PDF

Abstract

A rapid and relatively simple method for measurement of inorganic pyrophosphate (PPi) in biological samples has been described. The mean ±SEM of plasma samples from 94 normal subjects was 1.8±0.06 μM, giving a normal range (99% confidence limits) of 0.16 - 3.40 μmol/liter. Analysis of 17 plasma samples in duplicate showed a standard deviation of 0.18, giving a 99% probability that a single determination of plasma PPi would be ±0.68 μM of the true value.

Authors

Donald C. Silcox, Daniel J. McCarty

Systemic Lupus Erythematosus. STUDIES OF THE ANTIBODIES BOUND TO SKIN

• Text
• PDF

Abstract

Systemic lupus erythematosus is characterized by antibodies demonstrable by immunofluorescence on the renal glomeruli and at the basement membrane area of both normal and involved skin. Acid eluates from glomeruli and from normal-appearing skin of three patients with systemic lupus erythematosus contained an antinuclear antibody. This antibody fixes complement and produces a mixed immunofluorescent pattern. Anti-deoxyribonucleic acid or antiextractable nuclear antigen antibodies may be present. This antibody is concentrated on the skin and glomerular basement membrane in proportion to the total serum IgG concentration. In two cases the skin eluate contains, in addition to the antinuclear antibody, a basement membrane antibody that fixes complement, gives a linear immunofluorescent pattern, and appears to be similar (although not identical) to the pemphigoid antibody.

Authors

Madeleine Landry, W. Mitchell Sams Jr.

Induction of Aryl Hydrocarbon Hydroxylase in Human Pulmonary Alveolar Macrophages by Cigarette Smoking

• Text
• PDF

Abstract

Pulmonary alveolar macrophages were obtained from healthy volunteers by saline pulmonary lavage, and aryl hydrocarbon hydroxylase was measured in the cells. Enzyme activity was low in cells from five nonsmokers with a mean of 0.008±0.004 U/106 cells. Cells obtained from nine cigarette smokers contained higher enzyme levels, with a mean of 0.095±0.024 U/106 cells. A former cigarette smoker was lavaged on five occasions. Enzyme activity during two lavages 4 mo apart were 0.010 and 0.009 U/106 cells, respectively. 1 wk after smoking was resumed, the enzyme activity rose slightly to 0.013, and reached 0.041 U/106 cells by 1 mo. Upon cessation of smoking, the enzyme activity returned to control levels by the next lavage, 2 mo later. These data indicate that aryl hydrocarbon hydroxylase may be induced in pulmonary alveolar macrophages of subjects chronically exposed to cigarette smoke.

Authors

E. T. Cantrell, G. A. Warr, D. L. Busbee, R. R. Martin

Protective Study with a Group A Streptococcal M Protein Vaccine. INFECTIVITY CHALLENGE OF HUMAN VOLUNTEERS

• Text
• PDF

Abstract

Healthy adult male volunteers were immunized with purified M protein from Group A streptococci. Type 1. The vaccine was administered subcutaneously as an aluminum hydroxide-precipitated antigen in three montly doses. Control subjects received a placebo of the aluminum hydroxide adjuvant. To test the efficacy of the immunization, vaccinees and controls were challenged with a virulent strain of Type 1 streptococci applied to the pharynx. The immunization and challenge of the vaccinated and control subjects (19 men in each group) were carried out as a double blind experiment. All subjects were carefully screened by physical and laboratory examinations before and after the immunization and infectivity schedules. 30-50 days after the last injection, the vaccinees and control subjects were infected with the streptococci. Careful surveillance was maintained to evaluate the extent of acquired streptococcal infection. Throat cultures, leukocytes counts, temperatures, and physical signs and symptoms were monitored daily. All subjects received 1.2 million U of penicillin intramuscularly no later than 6 days after inoculation with the culture. Illness was judged by the appearance of exudative pharyngitis and cervical adenopathy accompanied by a positive throat culture. By these criteria, 9 of the 19 placebo controls, and 1 of 19 vaccinees were ill. No residual illness or clinical complications was observed after the penicillin treatment. It is concluded that the alum-precipitated M protein vaccine afforded protection against an upper respiratory Type 1 streptococcal infection.

Authors

Eugene N. Fox, Robert H. Waldman, Masako K. Wittner, Arthur A. Mauceri, Albert Dorfman

Canine Systemic Lupus Erythematosus. TRANSMISSION OF SEROLOGIC ABNORMALITIES BY CELL-FREE FILTRATES

• Text
• PDF

Abstract

The presence of viruses was sought in a colony of dogs bred from parents with systemic lupus crythematosus (SLE). Cell-free filtrates prepared from the spleens of these animals were injected into newborn dogs, mice, and rats. The canine recipients developed antinuclear antibody (ANA) and positive lupus erythematosus (LE) cell tests: ANA and, in some cases, antinative DNA antibodies were produced by the murine recipients: no abnormalities were detected in the rats. Serial passage of spleen cells or cell-free filtrates of spleen tissue in syngeneic mice reduced the time required for appearance of ANA from 9 to 4 mo. Some murine recipients of the canine filtrate developed malignant lymphomas. Murine leukemia viruses were identified in these tumors by electron microscopic, virologic, and serologic technics. These neoplasms, but not other tumors known to contain murine leukemia viruses, were associated with the production of ANA. Puppies inoculated with the canine filtrate-induced mouse lymphoma developed ANA and positive LE cell tests within 4 mo.

Authors

Robert M. Lewis, Janine Andre-Schwartz, Gerald S. Harbis, Martin S. Hirsch, Paul H. Black, Robert S. Schwartz

Impaired Lymphocyte Transformation in Hodgkin's Disease. EVIDENCE FOR DEPLETION OF CIRCULATING T-LYMPHOCYTES

• Text
• PDF

Abstract

The kinetics of lymphocyte transformation induced by phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were studied daily, with blood lymphocytes from normal individuals and from untreated patients in all stages of Hodgkin's disease (HD). In addition, spleen lymphocytes and lymph node lymphocytes were studied with similar techniques.

Authors

Kenneth M. Matchett, Andrew T. Huang, William B. Kremer

Simulation of Tissue Properties in Irreversible Diffuse Obstructive Pulmonary Syndromes. ENZYME DIGESTION

• Text
• PDF

Abstract

The length-tension properties of alveolar wall from normal cats were studied before and after exposure to enzymes naturally found in mammals (elastase, trypsin, collagenase, hyaluronidase). Hyaluronidase effected little change while all the proteolytic enzymes altered the mechanical properties of lung tissue. Collagenase removed the “mechanical stop” and the alveolar walls fractured at low forces. The properties of wall exposed to trypsin resembled those of elastase-treated tissue. Elastase increased the extension necessary to reach a given force and increased the maximum length (Lmax) and resting length (Lo). Maximum extensibility (λmax), the ratio of Lmax to Lo, fell with both elastase and trypsin digestion. A reduction in λmax simulates the changes in alveolar wall properties seen in the lungs of the aged and in those with an irreversible diffuse obstructive pulmonary syndrome (DOPSI). Unlike these states, however, the energy loss in stretching alveolar wall increased with elastolysis. Furthermore, the changes in Lo necessary to effect a change in λmax of alveolar wall comparable to that seen in DOPSI were excessive. The altered tissue properties that occur in man with obstructive pulmonary syndromes could not be produced with these proteolytic enzymes or with hyaluronidase.

Authors

C. J. Martin, T. Sugihara

Lymphocyte Transformation during Dinitrochlorobenzene Contact Sensitization. AN IN VITRO AND IN VIVO EVALUATION OF THE PRIMARY IMMUNE RESPONSE IN MAN

• Text
• PDF

Abstract

An evaluation of cell-mediated immunity in man is described that combines the advantages of an in vitro technique, lymphocyte transformation, with the use of contact sensitization to a primary immunogen, dinitrochlorobenzene (DNCB). DNCB, when coupled to autologous or allogeneic peripheral blood leukocytes, forms a complex, DNCB-antigen, that induces lymphocyte transformation specifically in leukocyte cultures from subjects sensitized to DNCB. Sequential studies of lymphocyte transformation to DNCB-antigen show that specifically reactive lymphocytes are first detected at about 10 days after in vivo application of a sensitizing dose of DNCB and reach a peak at about 14-21 days.

Authors

A. Edgar Miller, William R. Levis

Abnormalities in the Distribution of Serum Immunoglobulin Concentrations in Juvenile Rheumatoid Arthritis

• Text
• PDF

Abstract

Concentrations of serum IgG. IgA, and IgM were determined in 200 patients with juvenile rheumatoid arthritis. The relative frequency distribution of IgG and IgM approached that of a log-normal curve; however, there was marked skewing of the distribution of the serum concentrations of IgA. The prevalence of selective IgA deficiency was 4%. In order to permit further intragroup comparisons, the serum immunoglobulin concentrations were standardized by comparison to a sex-age matched control group. By this process it was found that there was concordance of the serum levels of IgG with IgA, and IgG with IgM. The standardized concentrations of IgA and IgM were less in females than males. The aberration in distribution of serum IgA concentrations found in this study, and the relative inability of females to respond to their disease by increasing specific serum immunoglobulin levels, add further data supporting the concept of immunodeficiency in the pathogenesis of juvenile rheumatoid arthritis.

Authors

James T. Cassidy, Ross E. Petty, Donita B. Sullivan

Estimation of Cholesterol and Bile Acid Turnover in Man by Kinetic Analysis

• Text
• PDF

Abstract

The kinetics of cholesterol and bile acid turnover were determined from an analysis of the biliary lipids after a single intravenous injection of labeled cholesterol. A compartmental model was designed for the system, and the fractional metabolic rates and fluxes were determined in one lean and two obese normal humans. Each of the normals converted about 3% per day of their rapidly miscible cholesterol pool to cholic acid and 1% per day or less to chenodeoxycholate. Cholate was catabolized at about twice the rate of the dihydroxy bile acids in these normals. Two of the normals were fed corn oil with little change in their kinetic parameters from the control state. The other normal received cholestyramine and dramatically increased the bile acid flux with little change in neutral sterol catabolism. A cirrhotic patient was also studied by this technique and noted to have kinetic parameters quite different from the normals.

Authors

Steven H. Quarfordt, Mary F. Greenfield

Pyrazinoate Excretion in the Chimpanzee. RELATION TO URATE DISPOSITION AND THE ACTIONS OF URICOSURIC DRUGS

• Text
• PDF

Abstract

These experiments were designed to define the renal disposition of pyrazinoic acid in a nonhuman primate that is phylogenetically close to man and to relate this to the effects of pyrazinoate on urate excretion. The renal clearance of pyrazinoate was almost always greater than the simultaneous glomerular filtration rate at plasma concentrations ranging from 1.9 to 960 μg/ml. Some inhibitors of tubular secretion, probenecid, MK-282 (an experimental, potent uricosuric drug), p-aminohippurate, iodopyracet, sulfinpyrazone, and mersalyl, reduced clearances of pyrazinoate to values far below filtration rate. Chlorothiazide, allopurinol, and salicylate did not. The clearance of pyrazinoate was not influenced by changes in urine flow. It is concluded that pyrazinoate is actively secreted and actively reabsorbed.

Authors

George M. Fanelli Jr., I. M. Weiner

Heterogeneity of Parathyroid Hormone. CLINICAL AND PHYSIOLOGIC IMPLICATIONS

• Text
• PDF

Abstract

When immunoreactive human parathyroid hormone (hPTH), extracted by three different solvents (20% acetone in 1% acetic acid, 8 M urea, or normal saline) from parathyroid glandular tissue was subjected to Sephadex G-100 gel filtration and immunoassay using two different antisera (273 and C-329), four distinct fractions were observed. The first (I), a void volume peak, was detected by both antisera with similar immunoreactivity, as was a second (II), which had the elution and sedimentation properties of highly purified bovine parathyroid hormone (bPTH); a third (III) eluted between [125I]growth hormone and [125I]insulin, sedimented with the velocity of a molecule of approximately 6,000 mol wt, and was detected primarily by antiserum 273; a final fraction (IV), detected primarily by C-329, eluted just prior to [125I]insulin. The elution profiles of the acetone-acetic acid and 8 M urea extracts were similar and contained fraction II as their major component. In saline extracts, however, fraction III predominated.

Authors

Robert Silverman, Rosalyn S. Yalow

Stimulation of Human Prolactin Secretion by Intravenous Infusion of L-Tryptophan

• Text
• PDF

Abstract

Previous studies have demonstrated that the secretion of human prolactin is regulated primarily by factors that influence catecholamines of the hypothalamus. In an effort to identify other factors that may regulate prolactin secretion, the amino acid L-tryptophan, a precursor in the synthesis of serotonin, was infused into normal human volunteers. Intravenous infusion of L-tryptophan, 5-10 g over a 20 min period, but not equivalent amounts of 17 other amino acids, induced marked increases in serum prolactin concentrations in eight normal human volunteers. Increases of 20-200 ng/ml above the control level were observed with peak values at 20-45 min after initiation of the infusion. In addition, infusion of L-tryptophan was associated with decreases in serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyrotropin in those subjects in whom the base-line serum hormone concentration was above the lower limits of assay detectability. No consistent change was observed in serum concentrations of growth hormone, cortisol, or glucose. Four subjects with juvenile diabetes demonstrated increases in serum prolactin values comparable with those observed in healthy individuals in response to infusions of L-tryptophan. Serum prolactin values in patients with surgically induced hypopituitarism were undetectable or deficient after infusion of 10 g of L-tryptophan. In this respect, infusion of L-tryptophan was equally effective in these subjects as the standard chlorpromazine stimulation test in identifying patients with hypopituitarism, indicating that the infusion of L-tryptophan may serve as a sensitive and reliable clinical test of prolactin secretory reserve. Further studies relating to the possible mechanism of action of L-tryptophan indicated that infusion of 5-hydroxytryptophan represents a much more potent stimulus for the secretion of prolactin and that premedication with the serotonin antagonist, methysergide maleate, serves to blunt the effect of L-tryptophan on prolactin secretion. These results support the concept that the effect of L-tryptophan on the secretion of human prolactin is mediated through its conversion to serotonin and are consistent with reported experimental observations that serotonin may participate in the reciprocal regulation of prolactin and gonadotropins.

Authors

John H. MacIndoe, Roger W. Turkington

Stimulation of Insulin Secretion by Long-Chain Free Fatty Acids. A DIRECT PANCREATIC EFFECT

• Text
• PDF

Abstract

A continuous-flow centrifuge was used to infuse sodium salts of oleic, linoleic, lauric, or palmitic acid into the pancreatic artery of anesthetized dogs. In these regional perfusion studies there was no increase in FFA levels in the general circulation. Elevation of pancreatic FFA levels produced an immediate increase in pancreatic venous immunoreactive insulin (IRI). After 10 min of FFA infusion. IRI levels declined somewhat from the initial peak response but soon rose again to high levels which were then sustained until the infusion was terminated. All four long-chain FFA tested produced a similar biphasic IRI response. Clearcut increases in IRI were associated with absolute FFA levels (measured in pancreaticoduodenal venous plasma) as low as 0.6-0.8 μeq/ml and with increments over basal levels of as little as 0.4-0.5 μeq/ml. At higher levels of FFA, absolute IRI levels in the pancreatic venous effluent exceeded 1,000 μU/ml in some experiments and 5- to 10-fold increases over basal values were observed.

Authors

Stephen R. Crespin, William B. Greenough III, Daniel Steinberg

Response of Plasma Histaminase Activity to Small Doses of Heparin in Normal Subjects and Patients with Hyperlipoproteinemia

• Text
• PDF

Abstract

The release of histaminase activity in plasma after small intravenous of heparin was studied in 85 normal subjects and patients. In normal subjects, plasma histaminase activity (basal level, 1.7±0.1 U/ml, mean ±SEM) increased 1.6±0.2 U/ml after 10 U of heparin/kg, 8.5±2.4 U/ml after 20 U/kg, and 33±4.9 U/ml after 75 U/kg. The extent of the increase varied widely among individuals but in a particular individual the response was constant and dose-dependent. Histaminase activity rose to peak levels within 7-15 min and then declined exponentially with a half-life of 40-120 min. This pattern of response was also observed in two patients with the histaminase-producing tumor, medullary carcinoma of the thyroid. A significantly reduced response was observed, however, in 14 patients with type I hyperlipoproteinemia, a disorder in which high plasma triglyceride levels are associated with low postheparin plasma lipolytic activity. After 10 U heparin/kg, plasma histamine activity increased 0.5±0.2 U/ml, and after 75 U heparin/kg, 10.9±5.6 U/ml. In contrast, in 27 patients with other types of hyperlipoproteinemia in whom postheparin lipolytic activity was normal, the increase (2.4±0.6 U/ml) in plasma histaminase activity after 10 U heparin/kg was not significantly different from that of normal subjects. The reduced response of the plasma histaminase activity to heparin in patients with type I hyperlipoproteinemia did not appear to be due to the presence of lipemia or to an inhibitor of the enzyme in plasma. These findings suggest that many patients with type I hyperlipoproteinemia may have deficient release of both lipolytic and histaminase activities into plasma after heparin administration.

Authors

Stephen B. Baylin, Michael A. Beaven, Ronald M. Krauss, Harry R. Keiser

Interrelation between Alterations in Pulmonary Mechanics and hemodynamics in Acute Myocardial Infarction

• Text
• PDF

Abstract

Pulmonary mechanics were evaluated in 30 patients with acute myocardial infarction by measuring forced expiratory flow rates and total pulmonary resistance (RT) with the oscillometric method at the resonant frequency of the chest (6-8) cycle/s). During the first 3 days after infarction, forced expiratory volume (FEV) and forced mid-expiratory flow rate (FEF25-75%) were 69% and 60% of predicted values, respectively. 10 or more wk later these values were 95% and 91%. Initially, RT was 52% greater than predicted, but was only 4% greater 10 or more wk later. In 11 patients RT was measured at both resonant frequency and at 3 cycle/s. Five of these patients had no clinical signs of heart failure, but nine had abnormally high values of pulmonary artery pressure, “wedge” pressure and pulmonary extravascular water volume. All of these patients recovered. Initially, RT at resonance was 50% and RT at 3 cycle/s was 130% greater than predicted values. 2-3 wk later these figures were -3% and +6% of those predicted, respectively. At 10 wk or more, significant frequency dependence of RT had disappeared (RT at 3 cycle/s was 7% greater than RT at resonance). Isoproterenol inhalation in six patients caused no change in flow rates, RT at resonance, or RT at 3 cycle/s. RT at resonance and at 3 cycle/s, FEV, and FEF25-75% correlated significantly with the pulmonary vascular pressures. Patients with more marked arterial hypoxia and larger values for extravascular water volume had greater elevations of RT and depression of FEF25-75%, but linear correlations were not significant. Clinical signs of congestive heart failure significantly correlated with a fall in FEV and FEF25-75%, the development of frequency dependence of RT, and elevation of the pulmonary wedge pressure. The initial elevation of RT and low flow rates indicate a modest degree of airway obstruction in acute myocardial infarction. Lack of response to isoproterenol suggests that bronchial muscular constriction is not a major factor. Frequency dependence of RT accompanied by elevated pulmonary vascular pressures and extravascular water volume indicates that pulmonary congestion causes the development of uneven time constants in the airways. Vascular engorgement and interstitial edema from elevated vascular pressures causing narrowing of the peripheral airways and closure of collateral airways could account for the above findings.

Authors

Benjamin Interiano, Richard W. Hyde, Morrison Hodges, Paul N. Yu

Regulation of Adrenal Ornithine Decarboxylase by Adrenocorticotropic Hormone and Cyclic AMP

• Text
• PDF

Abstract

Adrenal ornithine decarboxylase activity was stimulated in a dose-related manner after administration of ACTH or dibutyryl (6N-2′-O-dibutyryl) cyclic AMP to hypophysectomized rats. Little effect was observed for 2 h, but striking increases in enzyme activity were observed 4 h after administration of these substances. Effects of ACTH and dibutyryl cyclic AMP were not secondary to stimulation of steroidogenesis, since hydrocortisone had no effect on adrenal ornithine decarboxylase although it did stimulate activity of the enzyme in the liver and kidney.

Authors

R. Richman, C. Dobbins, S. Voina, L. Underwood, D. Mahaffee, H. J. Gitelman, J. Van Wyk, R. L. Ney

Effect of Intraduodenal Glucose Administration on Hepatic Extraction of Insulin in the Anesthetized Dog

• Text
• PDF

Abstract

Extraction of insulin by the liver after administration of glucose in the duodenum has been studied in fourteen anesthetized dogs. Plasma insulin and glucose were measured in the portal vein hepatic vein and hepatic artery. During the control period 40±3% of the approximately 11 mU of insulin presented to the liver/min was removed during a single transhepatic passage. Within 5 min after glucose administration, the amount of insulin reaching the liver increased significantly. In some animals this increase preceded any significant increase in the glucose concentration of the femoral artery. After glucose administration, hepatic extraction of insulin remained unchanged in five animals and rose significantly in nine. In five of the latter animals, the increase may have been more apparent than real due to nonrepresentative sampling of hepatic venous blood. However, for the whole group of animals, comparison of arterial insulin levels with the amount of insulin delivered to the liver suggested a transient increase in insulin extraction between 5 and 50 min after glucose administration. In no animal was there a decrease in the proportion of insulin extracted by the liver after glucose administration. The results indicate that the extraction process is not saturable at physiological insulin levels. Prior to glucose administration, net hepatic glucose output averaged between 30 and 40 mg/min. After glucose administration, the liver began to take up glucose and there was a significant correlation between hepatic glucose uptake and the amount of insulin reaching the liver. However, since the amount of glucose presented to the liver also increased, it is not established that the insulin was responsible for the change in hepatic carbohydrate metabolism.

Authors

Melvin Kaden, Philip Harding, James B. Field

The Mechanics of Esophageal Muscle Contraction. EVIDENCE OF AN INOTROPIC EFFECT OF GASTRIN

• Text
• PDF

Abstract

To compare the mechanical properties of lower esophageal sphincter (LES) and esophageal circular smooth muscle, force-velocity determinations were made under various physiological conditions. Isotonic and isometric recordings of opossum circular muscle were used to obtain the velocity of shortening and force, respectively, during alterations in: (a) initial muscle length (preload), (b) afterload, (c) calcium concentration, and (d) gastrin I. Muscle contraction was elicited to the neurogenic response at the termination of electrical stimulation. A change in preload (muscle length) altered the peak force (Po) developed during an afterloaded contraction, but had only a minor effect on the maximum velocity of shortening (V max). At the length of optimal tension development, Lo, (preload, 1.5 g), the LES muscle had a V max of 6.1±0.2 mm/s and a Po of 17.7±0.7 g. The esophageal muscle at its Lo (preload, 2.0 g) had a V max of 6.3±0.5 mm/s and a Po of 18.1±1.2 g. A decrease in calcium from 2.5 mM to 1.0 mM significantly reduced the V max and Po of all muscle, but an increase in calcium to 5.0 mM increased these parameters only minimally. At a calcium of 1.0 mM, gastrin I increased both V max and Po of all muscle. This inotropic effect of gastrin I occurred at lower concentrations in LES muscle than in muscle from the upper esophagus. The power (force × velocity) and work (force × muscle shortening) of esophageal and LES muscle were calculated from these data. Both the work and power generated during esophageal and LES muscle contraction were determined by: (a) the initial muscle length as produced by the preload, (b) the afterload against which the muscle was contracting, and (c) the contractility of inotropism of the muscle, that is, the force-velocity curve on which the muscle was operating.

Authors

Sidney Cohen, Fe Green

In Vivo Assessment of Pulmonary Vascular Integrity in Experimental Pulmonary Edema

• Text
• PDF

Abstract

During single pass indicator studies across the lungs [14C]urea remains in the vascular compartment, but its molecular size and solubility suggest it might escape abnormally permeable vessels. To test the hypothesis that [14C]urea might be used to distinguish pulmonary edema due to acutely increased intravascular pressure from that due to vascular damage by alloxan, we studied [51Cr]erythrocytes (r), [125I]albumin (a), [14C]urea (u), and tritiated water as dilution indicators in the pulmonary circulation of anesthetized dogs. In addition, the adequacy of albumin as an intravascular indicator was evaluated.

Authors

Kenneth L. Brigham, James D. Snell Jr.

Development of Intestinal Adenyl Cyclase and Its Response to Cholera Enterotoxin

• Text
• PDF

Abstract

Adenyl cyclase activity in intestinal membranes has been studied during development in the rabbit fetus from fetal day 17 to 10 days postnatally and in the human fetus from the 10th to the 17th wk of gestation. In the rabbit, the enzyme was already present by fetal day 17 and showed a fourfold peak rise in specific activity by 22 days. By 28 days, the specific activity had fallen toward adult levels and remained constant throughout gestation and the 1st wk of life. Fluoridestimulated activity showed a similar curve, and was 2.5-5 times the basal values. Activities in jejunum and ileum were comparable at all time points studied. Phosphodiesterase activity did not change during gestation. When fetal intestinal segments were incubated in vitro with purified cholera enterotoxin, adenyl cyclase activity in subsequently prepared membranes was increased two- to threefold. This level was not regularly further elevated by fluoride ion. Lithium ion inhibited both the basal and fluoride-stimulated enzyme activity in membranes prepared from rabbit fetuses at term. Lactase activity (reflecting the development of the microvilli) in either whole intestinal homogenates or in the membrane fractions showed a differnet pattern of development, with a rise beginning on fetal day 24 and a plateau just after birth. In intestinal membranes prepared from human fetuses, the activity of both basal and fluoride-stimulated adenyl cyclase tripled from the 10th to the 17th wk of gestation. The data both in the rabbit and in man show that intestinal adenyl cyclase is capable of responding to cholera enterotoxin quite early in gestation. In the rabbit, this occurs before the time of appearance or ville or of an enzyme marker (lactase) for microville. The results support the concept that adenyl cyclase is present in plasma membrane other than the brush border.

Authors

Richard J. Grand, Frank M. Torti, Stephanie Jaksina

Hemoglobin Brigham (α₂^Aβ₂^{100 Pro→Leu}). HEMOGLOBIN VARIANT ASSOCIATED WITH FAMILIAL ERYTHROCYTOSIS

• Text
• PDF

Abstract

Erythrocytosis associated with the presence of a hemoglobin with increased oxygen affinity has been reported for 10 hemoglobin variants, most of which demonstrate altered electrophoretic mobility. Several members of a family were found to have erythrocytosis, and both the whole blood and the hemoglobin exhibited increased oxygen affinity. Phosphate-free hemoglobin solutions had a normal Bohr effect and reactivity to 2,3-diphosphoglycerate. The electrophoretic properties of the hemoglobin were normal, but on peptide mapping of a tryptic digest of the isolated β-chains, a normal βT11 peptide and an abnormal βT11 with greater Rf were seen. Analysis of the abnormal peptide showed the substitution of leucine for the normal proline at β100 (helical residue G2).

Authors

Jacob J. Lokich, William C. Moloney, H. Franklin Bunn, Sally M. Bruckheimer, Helen M. Ranney

Disparate Enzyme Activity in Erythrocytes and Leukocytes. A VARIANT OF HYPOXANTHINE PHOSPHORIBOSYL-TRANSFERASE DEFICIENCY WITH AN UNSTABLE ENZYME

• Text
• PDF

Abstract

A family is reported in which each of two sisters has a son with no detectable hypoxanthine phosphoribosyltransferase (HPRT) (EC 2. 4. 2. 8) in his erythrocytes, a finding considered pathognomonic of Lesch-Nyhan disease. However, neither has the stigmata of the disease. One boy is neurologically normal, and the other is moderately retarded. There was only a slight increase in urinary uric acid, but the amounts of hypoxanthine and xanthine, and their ratios, were similar to those found in Lesch-Nyhan disease, strongly indicating that excesses of these last two oxypurines are not responsible for the symptomatology in that disease. In contrast to the nondetectable HPRT activity in the red blood cells, leukocyte lysates from the two boys have 10-15% of normal activity, possibly reflecting continuing synthesis of an unstable enzyme. This hypothesis is supported by the demonstration that at 4°C HPRT activity was rapidly lost in the propositus while the activity increased in control subjects. The mother's cells were intermediate between the two. The intact and disrupted leukocytes of the hemizygote, in the absence of added phosphoribosyl converted as much hypoxanthine to inosinate as the normal cell, and appropriate tests indicated that under these circumstances enzyme concentration is not rate limiting whereas the concentration of the cosubstrate, phosphoribosyl pyrophosphate, is. The capacity for normal function in the intact mutant cell is more representative of in vivo conditions than the lysate, which may explain the important modification of clinical symptomatology, the relatively mild hyperuricosuria, and the presence of mosaicism in the circulating blood cells of the heterozygotes. A similar explanation may apply to other genetic diseases in which incomplete but severe enzyme deficiencies are found in clinically normal individuals.

Authors

Joseph Dancis, Lily C. Yip, Rody P. Cox, Sergio Piomelli, M. Earl Balis

Abnormal Lipoprotein Lipase in Familial Exogenous Hypertriglyceridemia

• Text
• PDF

Abstract

A 5-yr old male proband and his sister have had hypertriglyceridemia and hepatosplenomegaly since birth. When studied on a metabolic ward, they demonstrated rapid decreases in serum triglycerides on 3 g fat/day diets. Oral glucose tolerance tests were normal. Postheparin lipolytic activity (PHLA) against chylomicrons was virtually absent in both children whereas the mother and a normolipemic sister had levels approximately 50% normal. However, all four had a normal PHLA against commercial triglyceride emulsion (Intralipid). Two unrelated children from different kindreds of typical type 1 hyperlipoproteinemia and two patients with acquired type V hyperlipoproteinemia had deficient PHLA against both substrates. No inhibitors of PHLA could be demonstrated in the proband's plasma, and his own PHLA could not be enhanced by either normal concentrated plasma or pooled d > 1.063 lipoprotein fraction. The proband's postheparin plasma required almost 20 times the normal chylomicron-triglyceride concentration to reach one-half maximal lipase velocity.

Authors

Paul H. Schreibman, Daniel L. Arons, Christopher D. Saudek, Ronald A. Arky

A Saturable, Vasopressin-Sensitive Carrier for Urea and Acetamide in the Toad Bladder Epithelial Cell

• Text
• PDF

Abstract

The permeability of the toad bladder to a series of isotopically labeled nonelectrolytes was determined in the presence of 150 mM unlabeled acetamide. Under these conditions, overall bladder function was unimpaired, as shown by a normal response to vasopressin of short-circuit current and permeability coefficient of [3H]water,[14C]ethanol, and [14C]propionamide. The permeability of the bladder to isotopic acetamide and urea, however, was significantly depressed by unlabeled acetamide, in both the absence and presence of vasopressin. These experiments indicate a competition between unlabeled and isotopic species for binding sites, and show the existence of a saturable, vasopressin-sensitive carrier for urea and acetamide in the epithelial cell membrane.

Authors

Sherman Levine, Nicholas Franki, Richard M. Hays