Translational Control of Hemoglobin Synthesis in Thalassemic Bone Marrow

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Abstract

Previous studies of β-thalassemic reticulocytes have implied a decreased amount of functional β-mRNA but unimpaired translation of the β-mRNA present. However, the β/α synthetic ratios in β-thalassemic marrow are higher than those observed in reticulocytes of the same patients. This could imply that marrow cells contain an abnormally functioning β-mRNA no longer active in reticulocytes. To test the function of mRNA found in marrow, intact cells were incubated with [35S]methionine and the relative amounts of nascent α- and β-chains on polysomes of different sizes were measured by tryptic digestion and determination of the specific activities of the respective peptides. Results showed that in normal and β-thalassemic marrow, as well as in reticulocytes, β-chain production, though deficient, occurs predominantly on larger polysomes than the production of α-chains. In one patient with severe thalassemia and very little production of β-chains in marrow or reticulocytes, δ-chain synthesis was found predominantly on larger polysomes than α-chain synthesis. These results indicate that in β-thalassemic as well as in nonthalassemic marrow and reticulocytes, each β- and δ-mRNA initiates protein synthesis at a rate faster than does each α-mRNA, and suggest that the β-mRNA in contact with polyribosomes is normally functioning but quantitatively deficient in β-thalassemic marrow as well as in reticulocytes. No translational defect was detected in a similar study performed in reticulocytes of a patient with hemoglobin H disease, suggesting a normally functioning mRNA in contact with polyribosomes in this condition as well. In both thalassemias, unbalanced synthesis of α- and β-chains was more pronounced on polysomes than in completed chains. This difference possibly reflects a compensatory delay in translation of the nonthalassemic chain, which is present in excess.

Authors

Gabriel Cividalli, David G. Nathan, Harvey F. Lodish

The Mechanism of Bicarbonate Secretion in Rabbit Ileum Exposed to Choleragen

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Bicarbonate may be secreted into the intestinal lumen in cholera because: HCO3− ions are transported, or because OH− ions accumulate and react with dissolved CO2 to form HCO3−. If HCO3− ions are transported into the lumen from the interstitial fluid, lumenal PCO2 should increase (HCO3− ⇌ OH− + CO2); if OH− accumulates, PCO2 should diminish. Net movement of H2O, and HCO3−, and changes in pH and PCO2 in lumenal fluid were studied in adjacent segments of rabbit ileum in vivo, one of which was exposed to choleragen. 4 h after exposure, segments were drained and infused with gassed Krebs-Henseleit solution whose PCO2 exceeded arterial PCO2. After 45 min, fluid was collected anaerobically from control and cholera segments. Among 13 cholera segments, lumenal PCO2 diminished by a mean of 8.4 torr and was less than femoral arterial blood in six instances. In the paired control segments, mean PCO2 increased by 4.4 torr, and was always greater than arterial PCO2. Dilution could not account for the low PCO2 in cholera segments because in hypertonic solutions that caused water to move into the lumen, the PCO2 did not differ from control values obtained with isotonic solutions. The results suggest that OH− accumulation (by addition of OH− or removal of H+) causes HCO3− secretion in cholera. This does not result from secretion of some other base (e.g., HPO4−), because HCO3− accounts for most of the base in the lumenal fluid. The PCO2 changes suggest that OH− reacts with CO2 at the cell-lumen interface, but reaction at the cell-interstitial fluid interface cannot be excluded.

Authors

Kenneth A. Hubel

Superficial and Juxtamedullary Nephron Function during Saline Loading in the Dog

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A modification of the microdissection technique of Hanssen was utilized in dogs to measure superficial (SNGFR) and juxtamedullary nephron filtration rate (JMGFR) in control and saline-expanded dogs. During control studies SNGFR was 60±4 and JMGFR was 72±5 nl/min. During saline loading SNGFR was 74±8 and JMGFR was 65±6 nl/min. The ratio SNGFR: JMGFR significantly increased from 0.84±0.03 to 1.15±0.08. Glomerular perfusion rate (GPR) was measured with the microsphere method during control and saline loading. Superficial GPR did not change significantly but juxtamedullary GPR increased from 225±42 to 323±39 nl/min. Calculated superficial nephron filtration fraction was unchanged after saline expansion but juxtamedullary filtration fraction decreased from 0.34±0.07 to 0.24±0.07. The data demonstrate a tendency for filtration to shift toward the superficial part and plasma flow toward the deep part of the kidney cortex. GFR in juxtamedullary nephrons appears to be less plasma flow-dependent than in superficial nephrons. The fall in filtration fraction in the deep cortex may affect sodium excretion by juxtamedullary nephrons.

Authors

Frank J. Bruns, Edward A. Alexander, Arthur L. Riley, Norman G. Levinsky

Augmentation of the Peripheral Metabolism of l-Triiodothyronine and l-Thyroxine after Acclimation to Cold: MULTIFOCAL STIMULATION OF THE BINDING OF IODOTHYRONINES BY TISSUES

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Increased metabolism of thyroid hormones was observed in rats adapted to an ambient temperature of 4°C. The increased hormonal degradation was manifested in enhanced metabolic, urinary deiodinative, biliary, and fecal clearances of iodothyronines. Increased metabolic clearances were due to stimulation of cellular hormonal disposition, evidenced by elevated intrinsic cellular clearances. After adaptation, the concentration of protein-bound iodine in plasma was decreased, and the binding of the hormones by plasma proteins was increased. The enhanced rate of metabolism of iodothyronines was associated with stimulation of the binding of these hormones by diverse tissues, suggesting the participation of extrahepatic degradative foci in the increased hormonal deiodination observed in vivo. Increased hepatocellular binding and a significantly enlarged hepatic distribution space of thyroxine were noted. Hepatocellular binding of triiodothyronine was similarly augmented, and a smaller but significant increase in the hepatic space of this iodothyronine was detected. Analysis of the hepatic subcellular partition of iodothyronines 35 min after the intravenous administration of isotopically labeled thyroid hormones disclosed increased hormonal binding by the microsomal fraction in cold-adapted animals and an attendant increase in the microsomal protein concentration. Partial microsomal subfractionation in a discontinuous sucrose gradient indicated that the observed stimulation of microsomal hormonal binding was associated with proliferation of the smooth endoplasmic reticulum.

Authors

Alan Balsam, Lynn E. Leppo

A Specific Role for Saline or the Sodium Ion in the Regulation of Renin and Aldosterone Secretion

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It is well established that in normal man the renin-angiotensin-aldosterone system is responsive to changes in volume. The present study was performed to determine whether sodium has an action apart from volume in the regulation of the secretion of renin and aldosterone. Acute volume expansion was induced either by saline, dextran, or glucose infusion in supine, normal subjects in balance on a 10 meq sodium/100 meq potassium diet. Plasma renin activity (PRA), angiotensin II (A II), aldosterone (PA), cortisol, serum sodium, and potassium were measured every 10 min for the first 30 min and then at 1, 2, 4, 6, and 8 h.

Authors

Michael L. Tuck, Robert G. Dluhy, Gordon H. Williams

Hyperactivity of Neutrophil Leukotactic Responses during Active Bacterial Infection

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To determine if changes in neutrophil leukocyte function occur during active bacterial infection, the neutrophils of 25 patients with active bacterial infection and 25 age-matched controls were compared for leukotactic activity, random mobility, and nitroblue tetrazolium reduction. The neutrophil leukocytes of patients with bacterial infection were hyperactive in unidirectional movement toward a chemotactic stimulus as measured in the leukotactic assay and usually had increased nitroblue tetrazolium reduction. The mean leukotactic index was 165±56 in patients with bacterial infection and 70±11 in controls (P < 0.001). After 7-10 days of appropriate therapy with clinical and bacteriological response, leukotactic activity returned to normal values. A hyperactive leukotactic response continued, however, in patients with persisting bacterial infection. The hyperactive leukotactic response of circulating neutrophils appears to be an early and sensitive event in the inflammatory cycle stimulated by bacterial infection and may aid in the localization of invading bacteria.

Authors

Harry R. Hill, Jonathan M. Gerrard, Nancy A. Hogan, Paul G. Quie

Uptake and Utilization of Exogenous Cystine by Cystinotic and Normal Fibroblasts

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The uptake of l-[35S]cystine was studied in six cystinotic and six normal fibroblast lines grown for five days either on cover slips or in 32-oz plastic flasks. Cystinotics showed greater uptake than normals. The apparent Kt for cystine entry in both types of cells was 0.043 mM but cystinotic cells showed a higher maximum velocity of entry. A comparison of the fate of l-[35S]cystine incubated for 20 min with monolayers of cells showed 30% and 15% of the intracellular 35S to be l-cystine in cystinotic and normal cells, respectively. The 35S effluxed more slowly from cystinotic than from normal cells after a 20-min preloading with l-[35S]cystine. Identification of 35S compounds in efflux media after 3 min showed 75% of the total 35S was l-cystine with the remainder in cysteine and acidic sulfur metabolites of cystine with no essential difference between cystinotics and normals. In paired experiments, the specific activity of the effluxed l-[35S]cystine after both efflux periods was the same as that entering the cell, thus indicating that the free l-[35S]cystine had not exchanged with the pre-existing pool in the cystinotic cells. During 3 min efflux, the l-cystine pool in normal cells was depleted mainly by loss of free cystine. In cystinotic cells, a new steady state was attained after 21 min of efflux and the intracellular l-[35S]cystine had the same percentage of total radioactivity seen after the initial 20-min uptake. After the rapid efflux of l-[35S]cystine from normals, [35S]cysteine and other labeled cystine metabolites appeared in the efflux media. By the end of a 3-min efflux, cystinotic cells had incorporated more label into reduced glutathione than had normal cells. However, when the new steady state was attained in cystinotics, the amounts of 35S in glutathione were not markedly different in the two types of cells. Approximately 95% of the total label could be accounted for in free sulfur compounds.

Authors

Beatrice States, Dorothy Harris, Stanton Segal

The Effect of Insulin on the Alpha-Cell Response to Hyperglycemia in Long-Standing Alloxan Diabetes

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In acute experimental diabetes in animals, alpha-cell unresponsiveness to hyperglycemia can be promptly corrected by insulin, but in human diabetes, even massive doses of insulin have little effect. To determine if this inability of insulin to correct the alpha-cell abnormality in man is merely the consequence of the long duration of the diabetic state (rather than of a difference in mechanism), the effect of insulin was studied in alloxan diabetes of long duration. Alloxan-diabetic dogs were maintained for 7-18 mo and treated daily with insulin. When glucose was infused without insulin, glucagon did not decline but rose paradoxically. However, when insulin was infused at a rate of 9 mU/kg/min together with glucose, a prompt decline in glucagon from a base-line average of 171 pg/ml SEM±34 to a nadir of 41 pg/ml SEM±9 was observed. This decline indicated that alpha-cell responsiveness to hyperglycemia is completely restored by large quantities of insulin. To determine if small amounts of insulin would similarly restore alpha-cell responsiveness in long-standing experimental diabetes, 1.4 mU/kg/min was infused. By the time the mean insulin level had risen 43 μU/ml, glucagon had declined significantly and ultimately fell to a nadir of 44 pg/ml. It is concluded from these studies that alpha-cell responsiveness to hyperglycemia can be fully restored in long-standing alloxandiabetic dogs as readily as in acutely diabetic dogs. Its ineffectiveness in restoring alpha-cell responsiveness to hyperglycemia in human diabetes may not, therefore, be related to duration of the diabetic state, and may reflect a primary alpha-cell defect.

Authors

Jan T. Braaten, Gerald R. Faloona, Roger H. Unger

Ectopic ACTH Production in Carcinoma of the Lung

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Immunoreactive ACTH was found in almost all tissue extracts of lung carcinoma from patients without clinical evidence of Cushing's syndrome; i.e. 14 of 15 primary tumors, nine of nine metastatic lymph nodes, and four of four metastatic liver nodules contained immunoreactive ACTH. The incidence of ACTH in extracts of other tumor types was much lower. Comparable normal tissues contained no detectable ACTH. Immunoreactive growth hormone, parathyroid hormone, or gastrin was not found in the same carcinoma tissue. The predominant form of ACTH in the tumor extracts was big ACTH. In pituitary extracts little ACTH predominated.

Authors

George Gewirtz, Rosalyn S. Yalow

β-Sitosterolemia and Xanthomatosis: A NEWLY DESCRIBED LIPID STORAGE DISEASE IN TWO SISTERS

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Although the usual diet may contain 150-250 mg of plant sterols, chiefly β-sitosterol, only trace amounts of these sterols have heretofore been found in human or animal blood and tissues. We now report elevated plant sterol levels in the blood and tissues of two sisters with extensive tendon xanthomas but normal plasma cholesterol levels. Besides β-sitosterolemia and xanthomatosis, no other physical, mental, or biochemical abnormalities were detected.

Authors

Ashim K. Bhattacharyya, William E. Connor

Neutral Proteases and Cathepsin D in Human Articular Cartilage

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Proteolytic enzymes have been studied in extracts of human articular cartilage by the use of micromethods. The digestion of hemoglobin at pH 3.2 and of cartilage proteoglycan at pH 5 was shown to be due chiefly to cathepsin D. Cathepsin D was purified 900-fold from human patellar cartilage. Its identity was established by its specific cleavage of the B chain of insulin. At least six multiple forms of cathepsin D are present in cartilage; these corresponded to bovine forms 4-9. Cathepsin D had no action on proteins at pH 7.4. However, cartilage extracts digested proteoglycan, casein, and histone at this pH. The proteolytic activities against these three substrates were purified about 170-, 160-, and 70-fold, respectively. Each activity appeared in multiple forms on DEAE-Sephadex chromatography. The three activities appear to be different since cysteine inhibited casein digestion, aurothiomalate inhibited histone digestion, and neither inhibited proteoglycan digestion. Tests with a wide range of inhibitors and activators suggest that these three activities differ from other neutral proteases described in the literature.

Authors

Asher I. Sapolsky, David S. Howell, J. Frederick Woessner Jr.

A Serum Component Related to Nonimmunoglobulin Amyloid Protein AS, a Possible Precursor of the Fibrils

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A nonimmunoglobulin protein with the molecular weight of 9,145 (protein AS) has been shown to be a principal component of the amyloid fibrils in different clinical types of amyloidosis. A protein component, antigenically closely related to protein AS, was detected in human sera. The protein AS-related component (protein ASC) was found in the sera of many groups of patients, including 48 out of 55 patients with various clinical types of amyloidosis. No structural relationship of protein ASC to the plasma component of amyloid was found. Protein ASC was also present with high frequency in the serum of diseases known to be frequently complicated by amyloidosis. In some cases, ASC was found in the sera of patients 2-3 yr before the diagnosis of amyloidosis was established. Protein ASC was also frequently found in hypogammaglobulinemia. Among normal individuals, protein ASC was seldom detected in the serum by our techniques, but there was a noticeable increase with age and during pregnancy. Moreover, a more sensitive technique, immunoelectro-osmophoresis, revealed protein ASC in a higher number of sera from both patients and normal controls. Thus protein ASC was suggested to be a normal serum constituent, usually present only in minor quantities. Under certain conditions, protein ASC increases considerably in serum, and may in such instances act as a precursor for the deposition of amyloid fibrils in the tissues.

Authors

G. Husby, J. B. Natvig

The Intestinal Absorption of Dietary Cholesterol by Hypercholesterolemic (Type II) and Normocholesterolemic Humans

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The incomplete absorption of dietary cholesterol may represent an adaptive intestinal barrier that prevents hypercholesterolemia. To explore this mechanism, we compared cholesterol absorption in 15 normocholesterolemic and 6 hypercholesterolemic (type II) subjects fed background cholesterol-free formula diets with 40% of calories as fat. Each test meal consisted of a breakfast into which was incorporated scrambled egg yolk containing 300-500 mg of cholesterol and [4-14C]cholesterol (3-22 μCi), either naturally incorporated into the yolk cholesterol by previous isotope injection into the laying hen or added in peanut oil to the yolk of the test breakfast. In some instances [1α-3H]cholesterol was the radioactive marker.

Authors

William E. Connor, Don S. Lin

Disturbance of Serum Viscosity in Diabetes Mellitus

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The serum viscosity of diabetic patients has been found to be increased. The elevation averaged 8% above healthy subjects and 6% above nondiabetic patients. The serum viscosity elevation was greater when diabetic sequelae associated with microangiopathy were present. No relation of serum viscosity to age, sex, obesity, duration of disease, or type of treatment was demonstrated. Serum total protein and glucose levels were found to be correlated with serum viscosity, and increases in their serum concentrations were observed in diabetes. Analysis demonstrated that their elevation did not explain either the viscosity increase or the difference in viscosity between diabetics with and without sequelae.

Authors

Donald E. McMillan

Substrate Turnover during Prolonged Exercise in Man: SPLANCHNIC AND LEG METABOLISM OF GLUCOSE, FREE FATTY ACIDS, AND AMINO ACIDS

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Arterial concentrations and substrate exchange across the leg and splanchnic vascular beds were determined for glucose, lactate, pyruvate, glycerol, individual acidic and neutral amino acids, and free fatty acids (FFA) in six subjects at rest and during 4 h of exercise at approximately 30% of maximal oxygen uptake. FFA turnover and regional exchange were evaluated using 14C-labeled oleic acid.

Authors

Gunvor Ahlborg, Philip Felig, Lars Hagenfeldt, Rosa Hendler, John Wahren

Ventilatory Acclimatization to Moderate Hypoxemia in Man: THE ROLE OF SPINAL FLUID [H⁺]

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This study has assessed the regulation of arterial blood and cerebrospinal fluid (CSF) pH and thereby their contribution to the control of breathing in normal man during various stages of ventilatory acclimatization to 3,100 m altitude. CSF acid-base status was determined: (a) from measurements of lumbar spinal fluid during steady-state conditions of chronic normoxia (250 m altitude) and at + 8 h and + 3-4 wk of hypobaric hypoxia; and (b) from changes in cerebral venous PCO2 at + 1 h hypoxic exposure. After 3-4 wk at 3,100 m, CSF [H+] remained significantly alkaline to values obtained in either chronic normoxia or with 1 h hypoxic exposure and was compensated to the same extent (∼66%) as was arterial blood [H+]. Ventilatory acclimatization to 3,100 m bore no positive relationship to accompanying changes in arterial PO2 and pH and CSF pH: (a) CSF pH either increased or remained constant at 8 h and at 3-4 wk hypoxic exposure, respectively, coincident with significant, progressive reductions in PaCO2; (b) arterial PO2 and pH increased progressively with time of exposure; and (c) in the steady-state of acclimatization to 3,100 m the combination of chemical stimuli present, i.e. PaO2 = 60 mm Hg, pHa and pHCSF = + 0.03-0.04 > control, was insufficient to produce the observed hyperventilation (PaCO2 = 32 mm Hg). It was postulated that ventilatory acclimatization to 3,100 m altitude was mediated by factors other than CSF [H+] and that the combination of chronic hypoxemia and hypocapnia of moderate degrees provided no mechanisms for the specific regulation of CSF [HCO3−] and hence for homeostasis of CSF [H+].

Authors

J. A. Dempsey, H. V. Forster, G. A. Dopico

Increased Clearance of Antipyrine and d-Propranolol after Phenobarbital Treatment in the Monkey: RELATIVE CONTRIBUTIONS OF ENZYME INDUCTION AND INCREASED HEPATIC BLOOD FLOW

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The effects of phenobarbital treatment for 12 days on the regional distribution of blood flow and on the disposition of two model drugs, antipyrine and d-propranolol, have been determined in six unanesthetized rhesus monkeys. Phenobarbital significantly increased total hepatic blood flow from 179±15 to 239±27 ml/min. Liver weight was increased to a similar degree (34%) in phenobarbital-treated animals as compared to control monkeys. The clearance of both antipyrine and d-propranolol was increased and the half-life decreased significantly by phenobarbital. Analysis of the data by a perfusion-limited pharmacokinetic model showed that the changes in antipyrine clearance were due almost entirely to enzyme induction. On the other hand, with d-propranolol, the increase in liver blood flow contributed as much to the enhanced clearance as did the stimulation of drug metabolism. The mechanism by which phenobarbital produces the frequently observed increase in drug clearance, therefore, depends upon the initial clearance value of the drug. For low clearance drugs like antipyrine, clearance changes occur largely as a result of enzyme induction. With higher clearance drugs, the effects of increased hepatic blood flow become progressively more important the greater the initial clearance value.

Authors

Robert A. Branch, David G. Shand, Grant R. Wilkinson, Alan S. Nies

Enhancement of Human Lymphocyte Transformation by Aggregated Human Gamma Globulin

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The effect of heat-aggregated human gamma globulin (aggFII) on the induction of in vitro lymphocyte transformation, measured by the uptake of tritiated thymidine into newly synthesized DNA, was studied with peripheral blood lymphocytes derived from 12 patients with rheumatoid arthritis (RA), six with ankylosing spondylitis (AS), two with systemic lupus erythematosus (SLE), and seven normal subjects. It was found that 200 μg aggFII induced significant transformation of the lymphocytes of eight patients with RA, five with AS, one with SLE, and one normal subject. Neither deaggregated FII nor heat-aggregated human serum albumin induced significant transformation of the lymphocytes of any subject tested. A source of complement appeared necessary to support aggFII-induced blastogenesis, since enhanced transformation occurred only in the presence of fresh plasma. Heat-inactivated plasma and fetal calf serum (FCS), and FCS devoid of hemolytic complement, failed to support enhanced blastogenesis in the presence of aggFII. Since substrates similar to those employed in these studies are present in vivo in the rheumatoid joint, it is suggested that aggFII may enhance intra-articular lymphocyte transformation in subjects with RA.

Authors

T. Douglas Kinsella

On the Mechanism of Lithium-Induced Diabetes Insipidus in Man and the Rat

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The mechanism of lithium-induced diabetes insipidus was investigated in 96 patients and in a rat model. Polydipsia was reported by 40% and polyuria (more than 3 liter/day) by 12% of patients receiving lithium. Maximum concentrating ability after dehydration and vasopressin was markedly impaired in 10 polyuric patients and was reduced in 7 of 10 nonpolyuric patients studied before and during lithium therapy. Severe polyuria (more than 6 liter/day) was unresponsive to trials of vasopressin and chlorpropamide, but improved on chlorothiazide. Rats receiving lithium (3-4 meq/kg/day) developed massive polyuria that was resistant to vasopressin, in comparison to rats with comparable polyuria induced by drinking glucose. Analysis of renal tissue in rats with lithium polyuria showed progressive increase in the concentration of lithium from cortex to papilla with a 2.9-fold corticopapillary gradient for lithium. The normal corticopapillary gradient for sodium was not reduced by lithium treatment. The polyuria was not interrupted by brief intravenous doses of vasopressin (5-10 mU/kg) or dibutyryl cyclic AMP (10-15 mg/kg) capable of reversing water diuresis in normal and hypothalamic diabetes insipidus rats (Brattleboro strain). The present studies suggest that nephrogenic diabetes insipidus is a common finding after lithium treatment and results in part from interference with the mediation of vasopressin at a step distal to the formation of 3′,5′ cyclic AMP.

Authors

John N. Forrest Jr., Alan D. Cohen, Jorge Torretti, Jonathan M. Himmelhoch, Franklin H. Epstein

The Mechanism of Activation of Hormone-Sensitive Lipase in Human Adipose Tissue

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A partially purified hormone-sensitive triglyceride lipase of human adipose tissue was found to be activated twofold by the addition of cyclic 3′,5′-AMP, ATP, and magnesium ions. Lipase activities against diolein and monoolein were not affected. Addition of protein kinase inhibitor at zero time completely inhibited activation, and this inhibition was prevented by prior addition of an excess of exogenous protein kinase (from rabbit skeletal muscle). Addition of protein kinase inhibitor during the activation step blocked the activation process without a time lag, suggesting that protein kinase operates directly on hormone-sensitive lipase. Further purification yielded a fraction free of protein kinase, and lipase activation in this fraction depended absolutely on addition of exogenous kinase. Incubation of human fat with epinephrine or isoproterenol stimulated lipolysis and caused conversion of nonactivated hormone-sensitive lipase to its activated form, as indicated by a decrease in the activation subsequently obtainable in fractions prepared from such hormone-treated tissues. These findings strongly suggest that the stimulation of lipolysis by hormonal treatment is the consequence of the activation of hormone-sensitive triglyceride lipase by cyclic 3′,5′-AMP-dependent protein kinase.

Authors

John C. Khoo, Alegria A. Aquino, Daniel Steinberg

Bone Marrow Erythropoiesis in the Anemia of Infection, Inflammation, and Malignancy

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A major factor in the anemia of infection, inflammation, and malignancy is a relative failure of the bone marrow to increase erythropoiesis in response to a shortened red cell survival. The possible causes for this diminished marrow response are: (a) a reduced production of erythropoietin, or, (b) impaired bone marrow response to erythropoietin. In this report studies were performed on 6 normals, 13 patients with anemia from infection or inflammation, and 18 patients with anemia caused by advanced malignancy. Serum erythropoietin activity was measured using the posthypoxic, polycythemic mouse assay. Assessment of bone marrow response to erythropoietin was made by measuring 59Fe-heme synthesis in bone marrow suspensions cultured for 3 days with and without the addition of erythropoietin. The results showed that marrow heme synthesis was increased in erythropoietin-treated cultures as compared with saline control cultures by 66±8% (mean ±SE) in normals, 101±10% in patients with infection or inflammation, and 31±5% in malignancy. Serum erythropoietin levels were consistently diminished relative to expected levels for the degree of anemia in the infection-inflammatory group, but not in malignancy. In these patients, plasma inhibitors to the biological activity of erythropoietin were not detected in vitro. These studies suggest that another factor to consider in the anemia of malignancy is a decreased bone marrow response to erythropoietin. In the anemia of infection-inflammation, marrow response to erythropoietin is normal, but serum levels of erythropoietin are decreased relative to the degree of anemia.

Authors

Stanley Zucker, Samuel Friedman, Rita M. Lysik

Effects of Dietary Calcium Restriction and Chronic Thyroparathyroidectomy on the Metabolism of [³H]25-Hydroxyvitamin D₃ and the Active Transport of Calcium by Rat Intestine

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Abstract

Previous studies have shown that chronically thyroparathyroidectomized (TPTX) rats, fed a diet with restricted calcium but adequate phosphorus and vitamin D content, have higher levels of intestinal calcium absorption than controls. The results of recent acute experiments have suggested that parathyroid hormone (PTH) may be essential for regulating the renal conversion of 25-hydroxyvitamin D3 (25-OH-D3) to 1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3] in response to dietary calcium deprivation. Since 1,25-(OH)2-D3 is the form of the vitamin thought to be active in the intestine, increases in calcium transport mediated by this metabolite would not be expected to occur in the absence of the parathyroid glands if the preceding model is correct. The present study was undertaken to examine the chronic effects of both dietary calcium restriction and the absence of PTH on the metabolism of [3H]25-OH-D3 and duodenal calcium-active transport in rats given thyroid replacement. These relatively long term studies confirm earlier observations which indicated that the adaptation of calcium absorption to a low calcium intake occurs in both sham-operated and TPTX animals.

Authors

Murray J. Favus, Marlin W. Walling, Daniel V. Kimberg

Sequence of Events Mediating the Effect of Cholera Toxin on Rat Thymocytes

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We have found that in rat thymocytes binding of [125I]choleragen is followed by cellular accumulation of cyclic 3′,5′-AMP which, in turn, is followed by stimulation of amino acid transport. Binding of cholera toxin was complete by 30 min and remained constant for the subsequent 150 min. After stimulation by choleragen, cellular cyclic 3′,5′-AMP became maximal by 30 min, after which it declined steadily so that by 90 min of incubation, cellular cyclic nucleotide levels were only 20% of those seen at 30 min. Stimulation of amino acid transport, although detectable by 15 min, did not become maximal until 120 min (by which time cellular cyclic 3′,5′-AMP had decreased by more than 80%). We have also used this system to delineate the step at which various pharmacologic agents and hormones act to alter the sequence of events mediating the response of rat thymocytes to cholera toxin. The ability of cycloheximide to abolish choleragen-stimulated amino acid influx without reducing [125I]choleragen binding or cellular cyclic 3′,5′-AMP suggests that cyclic nucleotide stimulation of amino acid transport includes a step involving protein synthesis.

Authors

James M. Boyle, Jerry D. Gardner

Spontaneous and Amino Acid-Stimulated Glucagon Secretion in the Immediate Postnatal Period: RELATION TO GLUCOSE AND INSULIN

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The extent and significance of spontaneous glucagon secretion in the immediate postnatal period were investigated in groups of normal infants studied cross-sectionally and longitudinally. Arginine-and alanine-stimulated glucagon secretion was also studied. Plasma glucagon concentrations were correlated with prevailing glucose and insulin concentrations.

Authors

Mark A. Sperling, Paul V. Delamater, Dale Phelps, Robert H. Fiser, William Oh, Delbert A. Fisher

Stimulators and Inhibitors of Hepatic Porphyrin Formation in Human Sera

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Human sera were found to contain factors that stimulate and factors that inhibit porphyrin formation by cultured avian liver cells. The capacity of sera to stimulate or inhibit porphyrin formation varied in different hormonal states and in the porphyrias. Sera from 31 post partum women, eight of whom were not lactating, inhibited porphyrin formation to a mean level 30% below the level in control cultures and also inhibited drug and steroid stimulation of porphyrin formation. In contrast, mean porphyrin formation compared to control cultures was increased between 9 and 21% by sera from 52 normal subjects, 16 women on oral contraceptives, and 11 pregnant women. It was increased 193% by sera from nine subjects with acute intermittent porphyria and 172% by sera from 13 subjects with porphyria cutanea tarda. Heated sera or ethanol extracts of sera from all groups of subjects further increased the mean porphyrin stimulation by sera and, for the post partum subjects, eliminated the inhibitory effect. Ethanol extracts of sera from 28 oral contraceptive-treated women caused significantly greater mean stimulation of porphyrin formation than did extracts of sera from 30 normal women. While sera from 17 out of 22 porphyric subjects contained both stimulatory and inhibitory factors, 5 out of 22 had no evidence of an inhibitory component. There appeared to be heterogeneity in the occurrence of the factors among porphyrics.

Authors

Arleen B. Rifkind, Shigeru Sassa, Irwin R. Merkatz, Robert Winchester, Leonard Harber, Attallah Kappas

Lung Volumes in Diffuse Obstructive Pulmonary Syndromes

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Lung volumes in irreversible diffuse obstructive pulmonary syndromes (DOPSI) have been studied by using an analog of the lung that simulates an 18-breath nitrogen washout. The functional residual capacity (FRC), the dead space volume (Vd), the distribution of ventilation, as well as the pattern of lung emptying have been measured in normal subjects and those with obstructive syndromes. The Vd increased progressively with severity of the obstructive syndrome, as did FRC. For all subjects, both normal and obstructed, the ratio of Vd/FRC remained relatively fixed with the regression line of Vd upon FRC showing a minimal value for Vd of 67 cm3. Vd increased by an average value of 33 cm3 per liter of lung volume above this value. The increase in FRC resulted from the increased volume of the poorly ventilated compartment for the most part. X-ray evidence of emphysema was poorly correlated with the changes in Vd or FRC. A significant increase in anatomical Vd in DOPSI makes up an appreciable portion of the total Vd (physiological).

Authors

A. C. Young, C. J. Martin, S. Tsunoda

Effects of Intraduodenal Administration of HCl and Glucose on Circulating Immunoreactive Secretin and Insulin Concentrations

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Abstract

A new radioimmunoassay for secretin was used to investigate (a) serum secretin responses to intraduodenally infused HCl and glucose, (b) the metabolic half-life and the volume of distribution of exogenous secretin and (c) the effect of endogenously released secretin on insulin secretion in 25 anesthetized dogs. Portal and femoral venous blood samples were taken simultaneously before, during, and after intraduodenal infusion of HCl (21 meq/30 min) and glucose (131 ml/30 min). Control experiments were performed with intraduodenal infusion of saline.

Authors

Guenther Boden, Noorjehan Essa, Oliver E. Owen, Frederick A. Reichle, Walter Saraga

Detection of the Carrier State in Combined Immunodeficiency Disease Associated with Adenosine Deaminase Deficiency

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Abstract

A large pedigree containing a child with severe combined immunodeficiency disease (CID) associated with adenosine deaminase (ADA) deficiency was investigated to ascertain if heterozygotes could be detected by measuring red cell ADA activity. 9 of 17 individuals in three generations who were at risk for being heterozygous had decreased red cell ADA activity. This genetic information establishes one form of CID as an autosomal recessive disorder. The identified heterozygote population had a mean ADA value of 19.2 U/g hemoglobin (0.95 confidence interval; 14.0 to 24.4 U/g hemoglobin), which was approximately one-half the mean, 36.1 U/g hemoglobin, of a randomly selected control population (0.95 confidence interval; 22.5-58.1 U/g hemoglobin). Statistical comparisons of the heterozygotes to the normal population indicates that within a high-risk family heterozygotes may be identified with 90% confidence.

Authors

C. Ronald Scott, Shi-Han Chen, Eloise R. Giblett

Superoxide Dismutase Activity in Leukocytes

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Abstract

Superoxide dismutase activity has been identified in both human neutrophils and rabbit alveolar macrophages by two distinct assay procedures. The enzyme is insensitive to both cyanide and azide and is present in the cytosol of the cell. The identification of this enzyme in phagocytic cells is compatible with the theory that superoxide anion might be involved in the bactericidal activity of the cell. It is proposed that the enzyme functions to protect the cell against superoxide generated during the phagocytic process.

Authors

Lawrence R. Dechatelet, Charles E. McCall, Linda C. McPhail, Richard B. Johnston Jr.

Studies on the Mode of Action of Cholera Toxin: EFFECTS ON SOLUBILIZED ADENYLATE CYCLASE

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Abstract

To gain further insight into the mechanism of action of cholera toxin, solubilized preparations of adenylate cyclase from control and toxin-treated rat livers were studied. Adenylate cyclase activity was measured in both particulate and solubilized form in rat liver under control conditions and after intravenous injection of cholera toxin. Cholera toxin caused a 3.3-fold activation of adenylate cyclase in the particulate preparation and a 5.8-fold increase in the solubilized preparation. Thus, the ability of cholera toxin to stimulate adenylate cyclase is present even when the enzyme membrane environment is disrupted. Furthermore, the solubilized enzyme, after treatment with cholera toxin, retained its ability to respond to catecholamines, but not to glucagon. In contrast, the control enzyme lost its responsiveness to catecholamines and glucagon after solubilization.

Authors

Barbara Beckman, Jorge Flores, Patricia A. Witkum, Geoffrey W. G. Sharp