The Monoglyceride Pathway of Fat Absorption in Man

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Abstract

The absorption of fat was studied in five male subjects with cannulation of the thoracic duct in the neck by the administration of doubly labeled monoglycerides, or triglyceride as well as labeled free glycerol or labeled free oleic acid, by gastric or duodenal intubation.

Authors

Herbert J. Kayden, John R. Senior, Fred H. Mattson

Effects of Adrenergic Receptor Activation and Blockade on the Systolic Preejection Period, Heart Rate, and Arterial Pressure in Man

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Abstract

We have investigated the possibility that alterations in the duration of the systolic preejection period can be used to estimate adrenergic influences on the human left ventricle. The preejection period was determined from high speed, simultaneous recordings of the phonocardiogram, carotid pulse tracing, and electrocardiogram. The preejection period was shortened by isoproterenol, epinephrine, and moderate doses of norepinephrine—all of which activate beta adrenergic receptors—and by cedilanid-D. It was unaltered by changes in heart rate induced by atropine and right atrial electrical pacing. Beta adrenergic receptor blockade by propranolol abolished the shortening effects of the three catecholamines but did not inhibit that due to cedilanid-D. Vasoconstriction, both alpha adrenergic (epinephrine and norepinephrine after propranolol) and nonadrenergic (angiotensin), prolonged the preejection period. Most of the shortening of the preejection period by beta adrenergic receptor activating agents and cedilanid-D and all of the prolongation accompanying pharmacologic vasoconstriction occurred after the onset of the first heart sound, thereby excluding changes in electrical-mechanical delay as a major factor in the observed preejection period responses. Shortening of the preejection period by beta adrenergic activity induced with isoproterenol was dose-related. Increasing doses of propranolol produced parallel shifts to the right in the isoproterenol dose-response curve.

Authors

Willard S. Harris, Clyde D. Schoenfeld, Arnold M. Weissler

Studies of Paroxysmal Nocturnal Hemoglobinuria Erythrocytes: Increased Lysis and Lipid Peroxide Formation by Hydrogen Peroxide

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Abstract

When paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes were exposed to H2O2 they lysed excessively and formed greater than normal quantities of lipid peroxides when compared to red cells of normal subjects and patients with most types of hematologic disease. It was also shown that lytic sensitivity to acidified serum was related to the enhanced lytic sensitivity to H2O2. If the lipid of PNH cells was first extracted then exposed to ultraviolet radiation more lipid peroxides were formed than in extracts of normal red blood cells. The possible explanations for these findings and their relationship to the PNH hemolytic mechanism are discussed.

Authors

Charles E. Mengel, Herbert E. Kann Jr., Wilhelm D. Meriwether

A Possible Role for the Adenylcyclase System in Insulin Secretion

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Abstract

A possible role for adenylcyclase in insulin secretion was investigated. Isoproterenol, a predominantly β-adrenergic agent, when mixed with an α-adrenergic blocking agent (phenoxybenzamine), stimulated insulin secretion from pieces of the rat's pancreas in vitro. Theophylline, caffeine, 3′5′-cyclic AMP, glucagon, adrenocorticotropin (ACTH), and thyrotropin (TSH), all of which are thought to act through the adenylcyclase systems in the liver and adipose tissue, also stimulated insulin secretion in vitro; oxytocin and vasopressin, which do not stimulate lipolysis in adipose tissue, were inactive. In all cases, stimulation of insulin secretion could not be detected when glucose was absent or present in only low concentrations (less than 100 mg/100 ml) and was maximal at high levels of glucose (300 mg/100 ml). When pancreatic tissue was obtained from normoglycemic rats and contained no detectable glycogen in the Islets, the stimulant effects of glucose and of theophylline were reduced or abolished by mannoheptulose and 2-deoxyglucose. When tissue was derived from rats infused for 8-10 hr with glucose and contained glycogen, theophylline, even in the absence of glucose, stimulated secretion and this effect was reduced by 2-deoxyglucose but not by mannoheptulose. It is suggested that the β-cell contains an adenylcyclase system through which phosphorylase and possibly phosphofructokinase could be activated; and that insulin secretion could depend upon and be regulated by hormones and other substances which influence the rate at which glycolysis proceeds within the β-cell.

Authors

W. J. Malaisse, F. Malaisse-Lagae, D. Mayhew

Cortisol Metabolism in Cirrhosis

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The production and peripheral metabolism of cortisol have been studied in 10 cirrhotics and 11 controls after i.v. tracers of cortisol-14C. The findings were as follows: (a) Total urinary excretion of radioactivity was normal (81% of the dose) but a decreased fraction was present as glucosiduronates: 18-47% of the dose (average 34%) compared to a normal average of 54%. (b) There was a distinctively abnormal pattern of cortisol metabolites, not previously observed in other illnesses: tetrahydrocortisone was decreased to 14% of the enzyme hydrolysate (normal 26%); cortolones were increased to 34% (normal 19%), owing entirely to an increase in cortolone (20α) formation, since β-cortolone (20β) was not significantly increased; Reichstein's substances U and epi-U were increased, averaging 2.6% for the former and 4.7% for the latter; tetrahydrocortisol, allotetrahydrocortisol and cortols were normal. This pattern was independent of the degree of decreased glucosiduronate formation and also independent of the presence or absence of a portacaval shunt. (c) Cortisol production, determined by isotope dilution, was normal in each of six cirrhotic patients. From these data, taken in conjunction with our previously reported findings concerning the influence of norethandrolone on cortisol metabolism, the following conclusions were drawn: (a) Cirrhotic patients have decreased A-ring reduction of cortisone to tetrahydrocortisone and correspondingly increased 20-ketone reduction of cortisone to Reichstein's substances U and epi-U and then to the cortolones. (b) Intrahepatic cholestasis, a regular pathophysiological feature of cirrhosis, may be responsible for the observed abnormal cortisol metabolite pattern in this disease. (c) The slowed metabolic turnover rate of cortisol in cirrhosis may be due to decreased transport and/or binding of cortisol to its intracellular metabolic sites rather than to abnormalities of any specific metabolizing enzymes.

Authors

Barnett Zumoff, H. Leon Bradlow, T. F. Gallagher, Leon Hellman

Mechanism of Pulsus Paradoxus in Clinical Shock

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Abstract

An inspiratory fall in systolic arterial pressure of more than 10 mm Hg (pulsus paradoxus) was noted in 30 of 61 patients with shock. Inspiratory right atrial pressures and total blood volumes were significantly lower in patients with pulsus paradoxus. Rapid infusion of dextran in 22 patients usually was effective in reversing the exaggerated inspiratory fall in systolic pressure. Total peripheral vascular resistance tended to be higher in the patients with pulsus paradoxus and administration of vasoconsrictor drugs often accentuated the respirator pressure variation.

Authors

Jay N. Cohn, Alan L. Pinkerson, Felix E. Tristani

Role of Insulin in Endogenous Hypertriglyceridemia

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Abstract

Dietary carbohydrate accentuation of endogenous triglyceride production has been studied in 33 patients. A broad and relatively continuous spectrum of steady-state plasma triglyceride concentrations was produced in 31 of the 33 subjects during 3 wk of a high carbohydrate (fat-free) liquid formula diet. Two patients developed plasma triglyceride concentrations in excess of 2000 mg/100 ml, and these were the only patients we have studied in which carbohydrate induction of hypertriglyceridemia seemed to be associated with a defect in endogenous plasma triglyceride removal mechanisms. In the remaining 31 patients the degree of hypertriglyceridemia was highly correlated with the insulin response elicited by the ingestion of the high carbohydrate formula (P < 0.005). No significant correlation existed between fasting plasma triglyceride concentration and either plasma glucose or free fatty acid concentrations after the high carbohydrate diet, nor was the degree of hypertriglyceridemia related to degree of obesity. It is suggested that hypertriglyceridemia in most subjects results from an increase in hepatic triglyceride secretion rate secondary to exaggerated postprandial increases in plasma insulin concentration.

Authors

Gerald M. Reaven, Roger L. Lerner, Michael P. Stern, John W. Farquhar

The Effects of Estradiol and Estriol on Plasma Levels of Cortisol and Thyroid Hormone-Binding Globulins and on Aldosterone and Cortisol Secretion Rates in Man

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Abstract

The effects of estriol and estradiol on the plasma levels of cortisol- and thyroxine-binding globulin activity, and on the secretion rates of aldosterone and cortisol were studied in man. The metabolite estriol had no consistent or significant influence on plasma levels of the hormone-binding globulin activities; the hormone estradiol increased these binding capacities significantly, as expected. Cortisol secretion rate rose slightly after estriol but was unchanged after estradiol. Both compounds induced substantial increases in the aldosterone secretion rate of most treated subjects. The mechanism of this apparently paradoxical effect of estrogens is not clear; it is suggested that the “salt-retaining” action of estrogens is mediated in part by the rapid enhancement of aldosterone output which follows their administration in man. Balance experiments in four subjects suggest that both estradiol and estriol may induce a transient early natriuresis in man; but other mechanisms for estrogen stimulation of aldosterone secretion may be operative as well.

Authors

Fred H. Katz, Attallah Kappas

Inhibition of Synthesis of Fetal Hemoglobin by an Isoleucine Analogue

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Abstract

Reticulocytes from newborn infants with Rh isoimmune hemolytic disease actively incorporated radioactive amino acids in vitro into hemoglobins F and A. Approximately 50% of the reticulocytes appeared capable of synthesis of both of these hemoglobins within the same cell, as demonstrated by the selective elution technique of Betke and Kleihauer. An isoleucine analogue, L-O-methylthreonine, inhibited the incorporation of a variety of amino acids into hemoglobin F, without significantly affecting the synthesis of hemoglobin A. The inhibition was prevented upon concomitant addition of L-isoleucine to the medium. These observations suggest that an independent biosynthetic apparatus is present in the cell for the synthesis of each of these two hemoglobins. Because isoleucine is present only in the gamma chains of hemoglobin F, the inhibitory effect of the analogue on the synthesis of this hemoglobin must represent a selective effect on the production of gamma chains.

Authors

George R. Honig

The Relation of Immunoglobulin Class, Pattern of Antinuclear Antibody, and Complement-Fixing Antibodies to DNA in Sera from Patients with Systemic Lupus Erythematosus

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Abstract

Sera from 55 patients with systemic lupus erythematosus were studied to clarify the significance of the patterns of nuclear fluorescence observed. The sera in which the IgG fraction produced a peripheral pattern of nuclear fluorescence were found to contain complement-fixing antibodies to native DNA and to DNA-histone complexes. This correlation did not exist when complement-fixing activity was compared to the IgM nuclear patterns. Sera which contained only complement-fixing antibodies to denatured DNA and which did not react with native DNA or nucleoprotein did not produce the peripheral pattern of nuclear fluorescence. The data suggest that single strands of DNA were not the reactive groups in the nucleus responsible for the peripheral pattern. The results support the conclusion that DNA within a DNA-protein complex may be the nuclear antigen responsible for the peripheral pattern of nuclear fluorescence.

Authors

Naomi F. Rothfield, B. David Stollar

Pathogenesis of Hemolytic Anemia in Homozygous Hemoglobin C Disease

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Abstract

Hemoglobin C is less soluble than hemoglobin A in red cells, in hemolysates, and in dilute phosphate buffer. Its relative insolubility may be explained by electrostatic interactions between positively charged β6-lysyl groups and negatively charged groups on adjacent molecules. Red cells from patients with homozygous hemoglobin C (CC) disease exhibit aberrant physical properties which suggest that the cells are more rigid than normal erythrocytes. They pass through membrane filters less readily than normal red cells do, and their viscosity is higher than that of normal cells. Differences from normal cells are exaggerated if mean corpuscular hemoglobin concentration (MCHC) is increased, by suspension in hypertonic salt solution. Increased rigidity of CC cells, by accelerating their fragmentation, may be responsible for formation of microspherocytes. These small dense cells are exceptionally rigid, and probably are even more susceptible to fragmentation and sequestration. Rigidity of CC cells can be attributed to a “precrystalline” state of intracellular hemoglobin, in which crystallization does not occur, although the MCHC exceeds the solubility of hemoglobin in hemolysates.

Authors

Samuel Charache, C. Lockard Conley, David F. Waugh, Richard J. Ugoretz, J. Richard Spurrell

Role of Autonomic Nervous System and the Cough Reflex in the Increased Responsiveness of Airways in Patients with Obstructive Airway Disease

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Abstract

Inhalation of aerosols of citric acid, histamine phosphate, or carbon dust, or air cooled to - 20°C or rapid respiratory maneuvers (inspiration or expiration) results in an increase in airway resistance in some patients with asthma or bronchitis. It has been shown previously in animals that stimulation of cough receptors results in bronchoconstriction through efferent cholinergic pathways. In the patients studied, the administration of atropine sulfate, which would block such pathways, abolished the bronchoconstrictor effects of all the stimuli except large doses of histamine, which may exert a direct effect on airway smooth muscle. These data suggest that sensitized cough receptors may be involved in triggering reflex airway constriction in such patients.

Authors

B. G. Simonsson, F. M. Jacobs, J. A. Nadel

Cytochrome Oxidase Repair during Treatment of Copper Deficiency: Relation to Mitochondrial Turnover

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Abstract

The repair of cytochrome oxidase depletion during the treatment of copper deficiency was studied in the rat. The purpose of this study was to distinguish the role of new cell production from the possibly more specific role of mitochondrial turnover in determining the rate of this repair.

Authors

Peter R. Dallman

Otic Lesions and Congenital Hypothyroidism in the Developing Chick

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Abstract

In an effort to elucidate the relation, if any, between thyroid abnormality and congenital deafness in Pendred's syndrome, an experiment was designed to study the effects of hypothyroidism on middle and inner ear hearing structures, including the auditory nerve and its central projection, in developing chick embryos. Propylthiouracil (PTU), 2 mg, was injected into the albumin of fertile chick eggs on the 10th incubation day. Single doses of L-thyroxine (range 1-100μg) were inoculated in a similar manner, either alone or with PTU. Control inocula included sterile saline or water. After hatching, each chick was examined for obvious malformations. The thyroid glands, middle and inner ear mechanisms, auditory nerve, and brainstem were studied grossly and with different histologic staining techniques. When compared to controls, chicks exposed to PTU on their 10th incubation day exhibited: increased mortality, delayed hatching, reduced size, incomplete yolk sac absorption, and death within 5 days unless exogenous thyroid hormone was provided in the first 24-48 hr after hatching. Specific, consistent, morphologic alterations were observed in their thyroid glands as well as in the sensory hair cells of the acoustic papilla and cells of the spiral ganglion of the cochlea. Our data also indicate that if 50-75 μg of L-thyroxine is given simultaneously with (or as long as 120 hr after) the PTU injection on the 10th incubation day, one cannot detect the gross defects, marked thyroid lesions, or abnormal histology in cells of the cochlea and its ganglion. A relationship between embryonic thyroid gland function and the hearing mechanism of the chick embryo is suggested.

Authors

Gerald J. Bargman, Lytt I. Gardner

Hemoglobin Yakima: I. Clinical and Biochemical Studies

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Abstract

Three members of a family who have erythrocytosis and a new hemoglobin, designated hemoglobin Yakima, are described.

Authors

Richard T. Jones, Edwin E. Osgood, Bernadine Brimhall, Robert D. Koler

Hemoglobin Yakima: II. High Blood Oxygen Affinity Associated with Compensatory Erythrocytosis and Normal Hemodynamics

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Erythrocytosis without clinical illness was noted in a man and his two daughters. Their blood contained approximately 62% hemoglobin A and 38% a new hemoglobin, designated hemoglobin Yakima. The oxygen affinity of whole blood from each subject was greatly increased and heme-heme interactions were impaired. At 37°C and a plasma pH of 7.40, the oxygen pressure required to produce 50% saturation of hemoglobin with oxygen was only 12 mm Hg as compared with a normal of 26 mm Hg. The high oxygen affinity of this blood is attributed to the presence of hemoglobin Yakima; and the increased oxygen affinity was shown to be characteristic of the isolated abnormal hemoglobin. A Bohr effect was present in hemoglobin Yakima.

Authors

Miles J. Novy, Miles J. Edwards, James Metcalfe

Plasma Lipoproteins in Liver Disease: I. Immunologically Distinct Low-Density Lipoproteins in Patients with Biliary Obstruction

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Abstract

Sera from patients with extrahepatic biliary obstruction were found to have an abnormal lipoprotein (obstructive lipoprotein) which failed to react with antibodies to normal lipoproteins of d < 1.063. Preparations of this abnormal lipoprotein made by a combination of immunoprecipitation and multiple polyanion precipitations revealed a high content of free cholesterol (26%) and phospholipids (61%) but only trace amounts of cholesterol esters and triglycerides. Protein content varied from 13% to a corrected low of 5% when ultracentrifugation was also performed. Amino acid analyses of the latter preparations resembled that of lipoproteins of d < 1.006.

Authors

Sam Switzer

Antibodies to Native and Denatured Deoxyribonucleic Acid in Systemic Lupus Erythematosus

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Abstract

The relative reactivities with native and denatured DNA of 35 lupus sera were investigated by quantitative complement fixation and precipitin studies and showed great variations. The use of purified native DNA demonstrated that, in at least 22 of these 35 sera, the anti-DNA antibodies reacted with the native form, independently of denatured contaminants. Systemic lupus sera were shown to contain three main types of DNA antibodies: those reacting only with denatured DNA, those reacting to the same extent with both forms of DNA, and those reacting preferentially with native DNA. In some instances, the latter antibodies fix complement and precipitate only with native DNA but are inhibited by the denatured form. This finding points to the importance of conformation in the antigenic structure of DNA. The simultaneous occurrence of different varieties of DNA antibodies was demonstrated in several sera. Evidence was obtained that some of these human antibodies to DNA can belong to the IgM class. Thus, DNA antibodies from systemic lupus patients differ in many respects from most of the experimentally produced antibodies capable of reacting with DNA.

Authors

Roberto Arana, Maxime Seligmann