Comparison of impedance to insulin-mediated glucose uptake in normal subjects and in subjects with latent diabetes

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Abstract

A technique was devised for a more accurate measurement than has been heretofore possible of one of the factors responsible for hyperglycemia in the complex syndrome of diabetes. This factor is termed impedance and represents the tissues' insensitivity or resistance to insulin-mediated glucose uptake. It was measured by use of steady-state exogenous insulin and glucose infusions during a period of pharmacological suppression of endogenous insulin secretion. Endogenous new glucose production was also inhibited. Impedance as calculated is a direct function of steady-state glucose concentrations, since exogenous insulin concentrations were similar in all studies. Two groups of normal weight subjects were studied. One had maturity onset latent diabetes, and the other (matched for age, weight, and per cent adiposity) was normal. Impedance was closely reproducible in the same individual and remained relatively constant during prolonged infusions. The diabetics had average infusion glucose concentrations (and thus impedance) 68% higher than the normal group, and it is of note that their previously measured glucose intolerance differed by a similar degree; that is, the diabetic's intolerance (as defined by mean weighted plasma glucose response after oral glucose) was 52% greater than that of the normal individuals.

Authors

Shiao-Wei Shen, Gerald M. Reaven, John W. Farquhar

Capillary basement membrane structure: a comparative study of diabetics and sexual ateliotic dwarfs

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Abstract

A group of 32 sexual ateliotic dwarfs with an isolated deficiency of human growth hormone (HGH) were shown previously to resemble subjects with genetic diabetes mellitus in terms of hyperlipemia, carbohydrate intolerance, and patterns of insulin secretion. 11 of these dwarfs had needle biopsies of the quadriceps femoris carried out and tissue fixed for electron microscopy. Capillary basement membrane thickness was measured and compared with measurements previously obtained in diabetics and normal controls. Measurements were similar in controls and dwarfs (1080 ±27 A and 1086 ±90 A, respectively) and significantly less than in diabetics (2403 ±119 A). Placed in juxtaposition with the absence of retinopathy in dwarfs and the high incidence in the diabetic group (41%), the data support the thesis that these anatomical abnormalities are largely independent of serum lipid and carbohydrate abnormalities. The data are consistent with a supportive, if not causative role of growth hormone in the pathogenesis of these lesions.

Authors

Thomas J. Merimee, Marvin D. Siperstein, Judith D. Hall, S. Edwin Fineberg

Receptors for human γG Globulin on human neutrophils

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Abstract

Cell surface receptors for human γG antibodies directed against bacterial antigens were demonstrated on human neutrophils using an in vitro bacteriocidal-phagocytic assay. These results were confirmed by adherence of sensitized erythrocytes to monolayers of neutrophils or monocytes. Erythrocytes sensitized indirectly with antibacterial γG antibodies after passive sensitization with bacterial antigens adhered to both neutrophils and monocytes. Erythrocytes sensitized directly with conventional anti-D γG antibodies adhered only to monocytes, while those sensitized with the hyperimmune anti-CD γG antibody Ripley adhered to both monocytes and neutrophils. Adherence of anti-Rh or antibacterial γG antibodies to monocytes and neutrophils could be inhibited by whole γG, myeloma globulins of the γ1 or γ3 subclasses, or Fc fragments, but not by Fab fragment.

Authors

R. P. Messner, J. Jelinek

Evidence for the chylomicron origin of lipids accumulating in diabetic eruptive xanthomas: a correlative lipid biochemical, histochemical, and electron microscopic study

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Abstract

Plasma lipoprotein alterations in nine insulin-dependent diabetics with hyperlipemia have been related to the lipid accumulating in eruptive xanthomas evolving in these patients. Histochemical and electron microscopic examination of xanthomas have been correlated with the lipid analyses in order to obtain additional evidence regarding the lipoprotein origin of lipids accumulating in the lesions. Both analytical and morphologic evidence suggested that circulating chylomicrons significantly contribute to the xanthoma lipids. All the patients had large quantities of circulating triglyceriderich chylomicrons which carried approximately 70% of the triglyceride found in the plasma. The fatty acid pattern of chylomicron and xanthoma triglycerides were similar. Triglyceride constituted the major lipid found in the xanthomas when they were sampled during their eruption. These findings, take in conjunction with histochemical and electron microscopic evidence of chylomicron particles in the dermal capillary walls, support the theory that blood lipoproteins, and particularly chylomicrons, permeated the vascular walls and the triglycerides carried by these lipoproteins apparently accumulated in tissue macrophages and perithelial cells which evolved into foam cells. Initiation of appropriate therapy resulted in clearance of the chylomicronemia and a concomitant resolution of the xanthomas as reflected by a decrease in total xanthoma lipid. Sequential studies of resolving xanthomas in five patients revealed that xanthoma triglyceride was mobilized more rapidly than cholesterol, resulting in a redistribution of the xanthoma lipids, so that the resolving lesions were cholesterol rich. Consistent with this change in lipid composition, correlative electron microscopy revealed loss of amorphous material from many of the foam cell vacuoles.

Authors

Frank Parker, John D. Bagdade, George F. Odland, Edwin L. Bierman

Evidence for a role of proteinpolysaccharides in regulation of mineral phase separation in calcifying cartilage

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Abstract

Our previous studies have indicated the presence of a macromolecular inhibitor of in vitro mineral growth, as well as a mineral nucleational agent in extracellular matrix fluid aspirated by micropuncture methods from epiphyseal hypertrophic cell cartilage. In this report, new miniaturized methods were used to extract proteinpolysaccharide complexes (PPC) from cartilage, to isolate a light fraction (PPL-C), and further, to separate it into R1, R2, and SR2 subfractions. These methods were applied to PPL-C complexes separated from microdissected epiphyseal cartilages and to cetylpyridinium chloride (CPC) precipitates of extracellular matrix fluid aspirated from similar cartilages. Most of all of the inhibitory action on an in vitro system of mineral growth shown by whole cartilage PPL-C and by cartilage fluid PPC obtained from noncalcifying sites was contained in the R2 fraction which represented ¼-[unk] of the total hexuronate.

Authors

Julio C. Pita, Leon A. Cuervo, Juan E. Madruga, Francisco J. Muller, David S. Howell

Augmentation of albumin but not fibrinogen synthesis by corticosteroids in patients with hepatocellular disease

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Abstract

Simultaneous studies of albumin and fibrinogen metabolism have been conducted using the carbonate-14C method before and after a 13 day course of prednisolone in eight patients with hepatocellular disease. Initially six patients were hypoalbuminemic. The mean plasma albumin and fibrinogen concentrations and albumin and fibrinogen synthetic rates were all lower than the corresponding values in a group of control subjects. Prednisolone therapy was associated with significant increases in the plasma concentration and synthetic rate of albumin but changes in the intravascular albumin pools were not significant. It is inferred that a low synthetic rate of albumin in a patient with liver disease does not necessarily represent the maximum capacity of the diseased liver to synthesize this protein. Changes in the plasma concentration, intravascular pool, and synthetic rate of fibrinogen were small and inconsistent. The data are compatible with a selective action of corticosteroids on hepatic protein metabolism and with the existence of different mechanisms for the control of albumin and fibrinogen synthesis.

Authors

G. D. Cain, G. Mayer, E. A. Jones

Effect of retransfusion after hemorrhagic hypotension on intrarenal distribution of blood flow in dogs

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Abstract

Hemorrhagic hypotension in anesthetized dogs produces a marked decrease of the cortical blood flow, whereas the medullary blood flow is well preserved. These animals were maintained at blood pressures of 50 mm Hg during a 3 hr period after which their blood pressures were restored by the reinfusion of blood or dextran, or both. In the first group of animals, the reinfusion of blood reestablished the blood pressure to control values, but the cortical blood flow was still nonuniformly decreased whereas the medullary blood flow appeared to be increased. In the second group of animals, phenoxybenzamine failed to protect the kidney completely since after blood reinfusion, the same anomalies described for the preceding group were found in 7 out of 10 dogs. The animals of the third group were reinfused with 50% of the shed blood and 10 ml/kg of a 10 g/100 ml solution of low molecular weight dextran. The modifications of the intrarenal distribution of the blood flow were less marked in this group although the blood flow rate of the inner cortex and the outer medulla was always elevated under these conditions. The reinfusion of low molecular weight dextran alone (20 ml/kg of a 10 g/100 ml solution) restored the blood pressure to levels slightly lower than those observed under control conditions but reestablished a normal pattern of intrarenal blood flow. The reinfusion of high molecular weight dextran was inefficient in correcting completely the anomalies of the renal blood flow. Mechanisms such as the increased sympathetic tone, the liberation of angiotensin, and the intravascular cellular aggregation could possibly account for the persisting anomalies of the renal circulation after reinfusion and are discussed.

Authors

Serge Carriere, Bernard Daigneault

Diminished synthesis of an alpha chain mutant, hemoglobin I (α^{16 lys → glu})

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In patients heterozygous for abnormal hemoglobins there is usually less than 50% of the mutant hemoglobin present in peripheral blood. The synthetic rates of α-chain mutants compared to αA have not been reported to date. In this study the production of αA- and αI-chains has been measured in peripheral blood and bone marrow of two patients with approximately 30% hemoglobin I, an α-chain abnormality (α16 lys → glu). The results suggest that the decreased amount of αI compared to αA is due solely to diminished biosynthesis of the αI-chains. The relative rates of synthesis of αI- and αA-chains are similar in both nucleated red cells and reticulocytes indicating that no change occurs during erythroid cell maturation which preferentially affects either αI or αA production.

Authors

G. J. Folayan Esan, F. J. Morgan, J. V. O'Donnell, S. Ford, A. Bank

Kinetic parameters and renal clearances of plasma adenosine 3′,5′-monophosphate and guanosine 3′,5′-monophosphate in man

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Abstract

Kinetic parameters and the renal clearances of plasma adenosine 3′,5′-monophosphate (cyclic AMP) and guanosine 3′,5′-monophosphate (cyclic GMP) were evaluated in normal subjects using tritium-labeled cyclic nucleotides. Each tracer was administered both by single, rapid intravenous injection and by constant intravenous infusion, and the specific activities of the cyclic nucleotides in plasma and urine were determined.

Authors

Arthur E. Broadus, Neil I. Kaminsky, Joel G. Hardman, Earl W. Sutherland, Grant W. Liddle

Effects of glucagon on adenosine 3′,5′-monophosphate and guanosine 3′,5′-monophosphate in human plasma and urine

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Glucagon, infused intravenously into fasting, well-hydrated, normal men in doses of 25-200 ng/kg per min, induced up to 30-fold increases in both plasma and urinary cyclic AMP. Cyclic GMP levels were unaffected by glucagon. Simultaneous cyclic AMP and inulin clearance studies demonstrated that the glucagon-induced increase in urinary cyclic AMP was entirely due to glomerular filtration of the elevated plasma levels of the nucleotide.

Authors

Arthur E. Broadus, Neil I. Kaminsky, Robert C. Northcutt, Joel G. Hardman, Earl W. Sutherland, Grant W. Liddle

The relationship between the free pool of proline and collagen content in human liver cirrhosis

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The free proline, free glutamic acid, and total collagen contents of the livers of cirrhotic and noncirrhotic patients were determined. The amounts of free proline in the sera of the patients were also determined. The results indicated that certain metabolic changes occurred in cirrhotic livers of humans that were similar to the metabolic changes observed previously in CCl4-induced cirrhosis in the rat. The amount of free proline was coordinate with the increase in total collagen, and both were inversely related to the amount of free glutamic acid. The average proline concentration in sera of cirrhotic patients was not higher than that of non cirrhotic patients, suggesting that the metabolic alteration noted above is a local event in the liver related to fibrogenesis. These and other results suggest that the pool size of free proline may play a prime role in regulation of collagen biosynthesis in liver cirrhosis.

Authors

David Kershenobich, Francisco J. Fierro, Marcos Rojkind

Release of vitamin B₁₂—binding protein by human leukocytes in vitro

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Abstract

Human granulocytes (G) contain a vitamin B12-binding protein (B12BP). There is evidence that chronic myelogenous leukemia leukocytes (CMLL) may synthesize B12BP. Our prior studies suggested that intact, living intravascular G synthesize and release such protein into extracellular compartments in vivo.

Authors

José Corcino, Stephen Krauss, Samuel Waxman, Victor Herbert

Glucagon levels and metabolic effects in fasting man

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Abstract

The role of glucagon in the metabolic adaptation to prolonged fasting in man has been examined. Plasma immunoreactive glucagon was determined during 6-wk fasts and during infusion of exogenous glucagon using an assay which minimized nonpancreatic immunoreactivity.

Authors

Errol B. Marliss, Thomas T. Aoki, Roger H. Unger, J. Stuart Soeldner, George F. Cahill Jr.

Mixed leukocyte reactivity and leukemia: study of identical siblings

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Abstract

This report describes a search for tumor-specific transplantation antigens in man by testing four sets of identical siblings using the mixed leukocyte transformation reaction. In each case, one member of the set had acute leukemia in relapse. In no instance did the leukemic cells of the patient stimulate the cells of the normal twin, nor did cells from the normal twin stimulate cells from the leukemic patient. Possible explanations for the failure to detect a leukemia-associated antigen in these studies are discussed.

Authors

Robert H. Rudolph, Eric Mickelson, E. Donnall Thomas

Uniphasic insulin responses to secretin stimulation in man

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Abstract

Secretin-stimulated insulin release was studied in normal subjects. In response to rapid intravenous injections (pulses) of secretin, insulin levels reached a peak between 2 and 5 min and returned to basal levels with 15 min. In contrast to large glucose pulses, increasing secretin pulses did not elicit sustained or prolonged insulin responses. In addition, insulin responses to a pulse and infusion were essentially identical with that of a pulse alone. Increasing secretin pulses given in 1 day were associated with decreasing insulin responses but not when the same pulses of secretin were given over a 2 day period. When time was the sole variable, insulin responses progressively decreased after identical 15-U secretin pulses given every 30 min, but were unchanged when the interval was 105 min. These observations indicate that secretin in contrast to glucose stimulates insulin release which is uniphasic. They suggest that release occurs only from a stored, readily available pool. This insulin pool appears to be relatively small and can be discharged faster than it refills.

Authors

Roger L. Lerner, Daniel Porte Jr.

Very low density lipoprotein triglyceride transport in type IV hyperlipoproteinemia and the effects of carbohydrate-rich diets

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Abstract

Transport of plasma-free fatty acids (FFA) and of fatty acids in triglycerides of plasma very low density lipoproteins (VLDL-TGFA) was studied in two normal subjects, five patients with type IV hyperlipoproteinemia, and two patients with type I hyperlipoproteinemia. After intravenous pulse-labeling with albumin-bound 1-palmitate-14C, specific radioactivity of plasma FFA and VLDL-TGFA were determined at intervals up to 24 hr. The results were analyzed using several different multicompartmental models each compatible with the experimental data. Fractional transport of VLDL-TGFA was distinctly lower (no overlap) in the type IV patients than in the control subjects, both on a usual balanced diet (40% of calories from carbohydrate) and on a high-carbohydrate diet (80% of calories). However, net or total transport of VLDL-TGFA in the type IV patients was not clearly distinguishable from that in the control subjects, there being considerable overlap on either diet. The results suggest that in this group of type IV patients the underlying defect leading to the increased pool size of VLDL-TGFA is not overproduction but a relative defect in mechanisms for removal of VLDL-TGFA. Since some of these type IV patients had only a moderate degree of hypertriglyceridemia at the time they were studied, and since it is not established that patients with the type IV phenotype constitute a biochemically homogeneous population, the present results should not be generalized.

Authors

Steven H. Quarfordt, Arthur Frank, David M. Shames, Mones Berman, Daniel Steinberg

Transport of plasma free fatty acids and triglycerides in man: a theoretical analysis

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Abstract

Three different multicompartmental models of free fatty acid (FFA) and very low density lipoprotein triglyceride fatty acid (VLDL-TGFA) transport in man are formulated from plasma FFA and VLDL-TGFA tracee and tracer data collected over a 24 hr interval after the injection of palmitate-14C. All modeling and data fitting were performed on a digital computer using the SAAM program. Structural differences in the three models relate to the position of the slowly turning over compartment required to generate the late portion of the plasma VLDL-TGFA tracer data. The positions of this slow compartment are along the hepatic pathway from FFA to VLDL-TGFA (model A) or in the distribution system of VLDL-TGFA (model B) or in the distribution system of FFA (model C). Although all three models are equally consistent with our experimental data and are supported by observations of others, each reveals inconsistency with some data obtained from the literature. Consequently, a combination model of FFA-TGFA transport, incorporating properties of models A, B, and C would be more consistent with all available data. Experiments that would help to determine the quantitative significance of each of the slow compartments in the combination model are suggested.

Authors

David M. Shames, Arthur Frank, Daniel Steinberg, Mones Berman

Increased ureteral back pressure enhances renal tubular sodium reabsorption

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Abstract

Moderate increases of ureteral back pressure usually cause decreases of glomerular filtration rate and even greater decreases of sodium excretion. It has been assumed previously that increased ureteral back pressure does not enhance renal tubular sodium reabsorption directly and that the decreases of sodium excretion are caused by the decreases of glomerular filtration rate. In the experiments reported here, the effect of increased ureteral back pressure on urinary sodium excretion was studied in dogs in which changes of filtration rate were minimized by infusing saline while ureteral back-pressure was increased.

Authors

Milford Fulop, Paul Brazeau

Metabolism of arterial plasma estrogens by the splanchnic organs of the dog in vivo

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Abstract

In order to study the splanchnic metabolism of blood-borne estrogens, a constant infusion of estrone-6,7-3H was made in a series of dogs, and arteriovenous (A-V) differences at equilibrium were determined for estrone-6,7-3H and for its products estradiol-17β, estrone sulfate, estrone glucosiduronate, and estradiol-17β glucosiduronate across the splanchnic bed (artery-hepatic vein), the small intestine (artery-superior mesenteric vein), and the spleen (artery-splenic vein). Per cent extractions (100 - [V/A] 100) were calculated. The plasma metabolic clearance rate (MCR) for estrone was measured. Principal findings were as follows: mean MCR was 731 liters/day per m2, SEM 50. By comparison with estimated hepatic plasma flow and using the observed splanchnic extraction of estrone, 45-71% of estrone metabolism was calculated to be extrasplanchnic. The significant mean per cent extractions were as follows (SEM in parentheses): splanchnic bedestrone 85.9 (1.92), estradiol-17β 88.11 (3.36), estrone sulfate 27.9 (5.22), estrone glucosiduronate -48.5 (9.33), estradiol-17β glucosiduronate -33.3 (80.3); small intestine—estrone 45.3 (2.60), estradiol-17β 46.1 (12.9), estrone glucosiduronate - 30.8 (7.9); spleen—estrone 35 (3.8), estrone glucosiduronate 12 (3.7). These results lead to the following conclusions. Both estrone and estradiol-17β are nearly completely extracted in one passage through the splanchnic bed. There is net uptake of estrone sulfate and net production of estrone glucosiduronate and of estradiol-17β glucosiduronate by the splanchnic bed. There is net uptake of estrone and of estradiol-17β by the intestine, associated with substantial net production of estrone glucosiduronate. There is net uptake of estrone by the spleen and a small but significant net uptake of estrone glucosiduronate.

Authors

Delwood C. Collins, Hugh D. Robinson, Carolyn M. Howard, John R. K. Preedy

Effects of increased sodium delivery on distal tubular sodium reabsorption with and without volume expansion in man

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Abstract

The separate effects of volume expansion and of increased delivery of sodium on sodium reabsorption in the diluting segment of the distal nephron were studied in man. In six normal subjects during a sustained water diuresis, sodium delivery to the distal nephron was increased without volume expansion by the administration of acetazolamide. In these subjects, free water clearance rose linearly as a function of urine flow. In five patients with complete, central diabetes insipidus, distal sodium delivery was increased by the infusion of hypertonic saline during a sustained water diuresis. In four of these five patients, changes in free water clearance were also observed during hypertonic saline diuresis in the presence of distal blockade of sodium reabsorption with chlorothiazide. At high rates of distal delivery the following observations were made: (a) free water clearance was lower and fractional sodium excretion higher during saline diuresis compared to acetazolamide diuresis; (b) although free water clearance was moderately reduced by chlorothiazide at low rates of urine flow, there was no difference in free water clearance between saline loading alone and saline plus chlorothiazide at high rates of urine flow; and (c) during saline loading free water clearance rose without evidence of a limit when increased distal delivery was accompanied by spontaneous increases in glomerular filtration rate, but tended toward a limit when glomerular filtration rate remained constant.

Authors

Vardaman M. Buckalew Jr., Barry R. Walker, Jules B. Puschett, Martin Goldberg

Metabolic clearance rate of radioiodinated human calcitonin in man

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Abstract

The characteristics of the disappearance of radioiodinated synthetic human calcitonin from plasma have been studied in man. After single injection the disappearance curve was multiexponential. The number of exponentials of the theoretical curve fitting the best with the experimental data varied individually. Metabolic clearance rate was determined both from single injection and constant infusion studies, and fast initial distribution volume from the former. Metabolic clearance rate values in normal man calculated from constant infusion studies were 82.3 ±3.4 ml/min per m2. Values derived from single injection studies were similar, 77.0 ±4.7 ml/min per m2. These results were compared to those obtained in end stage, renal failure patients. Metabolic clearance rate was considerably lower and volume of fast initial distribution slightly larger in that group. This fact emphasizes the important role of kidneys in the utilization and/or the degradation of human calcitonin.

Authors

Raymond Ardaillou, Pierre Sizonenko, Alain Meyrier, Gabriel Vallée, Christian Beaugas

Calcification of collagen by urine in vitro: dependence on the degree of saturation of urine with respect to brushite

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Abstract

A state of supersaturation of urine with respect to brushite is considered to be important in the formation of renal stones composed of calcium phosphate. 56 supersaturated urine specimens and 44 undersaturated specimens were incubated with collagen (Sigma collagen). Most of the supersaturated specimens calcified the collagen, whereas none of the undersaturated ones did so. Among samples which calcified the collagen, whereas none of the undersaturated ones did so. Among samples which calcified the collagen, the activity product of Ca++ and HPO4= after incubation with collagen was essentially the same as that after incubation of the same specimen with brushite; it usually differed from that obtained after incubation with octacalcium phosphate or hydroxyapatite. The molar calcium-to-phosphorus ratio of the solid phase in collagen was approximately 1. These results suggested that the solid phase formed in collagen is brushite. This conclusion was confirmed by the direct identification of brushite in collagen by X-ray diffraction.

Authors

Charles Y. C. Pak, Belle Ruskin

Cerebrovascular response to acute hypocapnic and eucapnic hypoxia in normal man

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Abstract

Alterations in human cerebral blood flow and related blood constituents were studied during exposure to acute hypoxia. Observations were made during serial inhalation of decreasing O2 concentrations with and without maintenance of normocarbia, during 8 min inhalation of 10% O2, and after hyperventilation at an arterial PO2 of about 40 mm Hg. In the range of hypoxemia studied, from normal down to arterial PO2 of about 40 mm Hg, the magnitude of the cerebral vasodilator response to hypoxia appeared to be largely dependent upon the coexisting arterial CO2 tension. The mean slope of the increase in cerebral blood flow with decreasing arterial O2 tension rose more quickly (P < 0.05) when eucapnia was maintained when compared with the slope derived under similar hypoxic conditions without maintenance of eucapnia. When 12 subjects inhaled 10% oxygen, cerebral blood flow rose to more than 135% of control in four whose mean decrease in arterial CO2 tension was - 2.0 mm Hg. The remaining eight had flows ranging from 97 to 120% of control, and their mean decrease in CO2 tension was - 5.1 mm Hg. When mean arterial PO2 was 37 mm Hg, hyperventilation was carried out in 10 subjects. Arterial PO2 increased insignificantly, arterial PCO2 declined from 34 to 27 mm Hg (P < 0.05), and cerebral blood flow which had been 143% of control decreased to 109%, a figure not significantly different from control.

Authors

William Shapiro, Albert J. Wasserman, James P. Baker, John L. Patterson Jr.

Hemoglobin stability: observations on the denaturation of normal and abnormal hemoglobins by oxidant dyes, heat, and alkali

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Abstract

Several unstable mutant hemoglobins have alterations which affect areas of the molecule involved in the attachment of heme to globin. Loss of heme from globin has been demonstrated during the denaturation of some of these unstable mutants. The importance of heme ligands for the stability of hemoglobin was illustrated in the present experiments on the denaturation of several hemoglobins and hemoglobin derivatives by heat, oxidative dyes, and alkali. Heating of normal hemolysates diluted to 4 g of hemoglobin per 100 ml at 50°C for 20 hr in 0.05 M sodium phosphate, pH 7.4, caused precipitation of 23-54% of the hemoglobin. Dialysis against water or dilution of the sample decreased denaturation to 12-20%. Precipitation was decreased to less than 3.5% by the presence of 0.015 M potassium cyanide. Increasing the ionic strength of the medium increased precipitation. Cyanide prevented the formation of inclusion bodies when red cells containing unstable hemoglobin Philly, β35 tyr → phe, were incubated with the redox dye new methylene blue. Conversion to methemoglobin increased the rate of alkali denaturation of hemoglobin but the presence of potassium cyanide returned the denaturation rate to that of ferrohemoglobin. The ability of cyanide to decrease heat precipitation of hemoglobin may depend on a dimeric or tetrameric state of the hemoglobin molecule. Purified β-chains, which exist as tetramers, were stabilized but purified monomeric α-chains were not rendered more heat resistant by the ligand. Stabilization of hemoglobin by cyanide required binding of the ligand to only one heme of an αβ-dimer. Hemoglobin Gun Hill, an unstable molecule with heme groups present only on the α-chains was quite heat stable in the presence of cyanide. The binding of cyanide to the iron atom in methemoglobin is thought to be associated with increased planarity of the heme group and increased stability of the heme-globin complex. The stabilizing effect of cyanide in the above experiments suggests that Heinz body formation, heat precipitation of hemoglobin, and the increased alkali denaturation of methemoglobin depend on changes of heme-globin binding.

Authors

Ronald F. Rieder

Digoxin intoxication: the relationship of clinical presentation to serum digoxin concentration

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Abstract

A radioimmunoassay for serum digoxin concentration has been used to study the interrelationships of circulating levels of the drug and various factors in the clinical setting in 48 hospitalized patients with cardiac rhythm disturbances due to digoxin intoxication. 131 patients on maintenance doses of digoxin without toxicity and 48 patients with equivocal evidence of digoxin excess were also studied and compared with the toxic group.

Authors

Thomas W. Smith, Edgar Haber

Effects of parathyroid hormone on plasma and urinary adenosine 3′,5′-monophosphate in man

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Abstract

The effects of parathyroid hormone (PTH) on plasma and urinary adenosine 3′,5′-monophosphate (cyclic AMP) levels were studied in normal subjects. Under basal conditions normal adults have plasma concentrations of cyclic AMP ranging from 10 to 25 nmoles/liter and excrete from 1.5 to 5 μmoles of cyclic AMP per g of urinary creatinine. About one-half to two-thirds of the cyclic AMP excreted in the urine is derived from the plasma by glomerular filtration, and the remainder is produced by the kidney. Renal production of cyclic AMP is partly under the control of PTH. It can be suppressed by infusions of calcium and stimulated by infusions of the calcium chelating agent, EDTA. Infusions of PTH in doses up to 10 mU/kg per min were associated with dose-related increases both in urinary cyclic AMP and phosphate. Infusions of PTH in doses ranging from 20 to 80 mU/kg per min did not lead to any further increase in phosphaturia but did lead to further marked increases in urinary cyclic AMP. A modest increase in plasma cyclic AMP was noted when PTH was infused at 40 mU/kg per min. Anephric patients failed to show appreciable increases in plasma cyclic AMP in response to large doses of PTH but did show expected increases in response to glucagon. Surgical removal of parathyroid adenomas from nine patients with primary hyperparathyroidism was invariably followed by a decrease in urinary cyclic AMP, PTH, in large doses, and calcium infusion produced up to 2-fold increases in the other known naturally occurring cyclic nucleotide, guanosine 3′,5′-monophosphate (cyclic GMP).

Authors

Neil I. Kaminsky, Arthur E. Broadus, Joel G. Hardman, Douglas J. Jones Jr., John H. Ball, Earl W. Sutherland, Grant W. Liddle

A lipoprotein characterizing obstructive jaundice. II. Isolation and partial characterization of the protein moieties of low density lipoproteins

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Abstract

The plasma low density lipoproteins (LDL) in biliary obstruction are characterized almost exclusively by the presence of the immunochemically distinct lipoprotein families, lipoprotein B (LP-B) and lipoprotein X (LP-X). It is suggested that LP-X, with its uniquely high content of unesterified cholesterol and phospholipid, is primarily responsible for the unusual lipid composition of LDL and the abnormal plasma lipid composition in obstructive jaundice.

Authors

D. Seidel, P. Alaupovic, R. H. Furman, W. J. McConathy

The role of ceruloplasmin in iron metabolism

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Abstract

The importance of ceruloplasmin in iron metabolism was studied in swine made hypoceruloplasminemic by copper deprivation. When the plasma ceruloplasmin level fell below 1% of normal, cell-to-plasma iron flow became sufficiently impaired to cause hypoferremia, even though total body iron stores were normal. When ceruloplasmin was administered to such animals, plasma iron increased immediately and continued to rise at a rate proportional to the logarithm of the ceruloplasmin dose. The administration of inorganic copper induced increases in plasma iron only after ceruloplasmin appeared in the circulation. Thus, ceruloplasmin appeared to be essential to the normal movement of iron from cells to plasma.

Authors

H. P. Roeser, G. R. Lee, S. Nacht, G. E. Cartwright

Studies on steroid fever II. Pyrogenic and anti-pyrogenic activity in vitro of some endogenous steroids of man

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Abstract

The pyrogenic properties of some C-19 and C-21 steroids were examined by in vitro incubation of human blood leukocytes with serum-buffer solutions of the steroids and injection of the 18-hr supernatants into rabbits. In previous studies this method demonstrated release of leukocyte endogenous pyrogen by etiocholanolone. With two exceptions, steroids known to cause fever in man, such as 11β-OH etiocholanolone and 3α-hydroxy-5β-pregnane-20-one were also pyrogenic in vitro. All steroids tested which are nonpyrogenic in man, such as androsterone, 3β-OH etiocholanolone, and 3α, 17α-dihydroxy-5β-pregnan-20-one were also nonpyrogenic in vitro. Solubility in aqueous solution did not correlate with pyrogenic capacity.

Authors

G. M. Dillard, Phyllis Bodel

Anaphylatoxin inactivator of human plasma: its isolation and characterization as a carboxypeptidase

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Abstract

The failure of human serum to give rise to anaphylatoxin activity could be attributed to the presence of a potent inactivator of anaphylatoxin in human serum. The inactivator was isolated and characterized as an α-globulin with a molecular weight of approximately 310,000. It was found to abolish the activity of both anaphylatoxins, which are derived respectively from the third and the fifth component of complement, and of bradykinin. Inactivation of C3-derived anaphylatoxin and of bradykinin was accompanied by release of C-terminal arginine from these peptides. The anaphylatoxin inactivator was shown to hydrolyze the synthetic substrates hippuryl-L-arginine and hippuryl-L-lysine and to be inhibited by ethylenediaminetetraacetate (EDTA) or phenanthroline. These observations indicate that the anaphylatoxin inactivator constitutes a metal-dependent enzyme resembling in specificity pancreatic carboxypeptidase B.

Authors

Viktor A. Bokisch, Hans J. Müller-Eberhard

Defect in urinary acdification induced in vitro by amphotericin

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Abstract

Authors