Studies of substrate regulation in fasting: II. Effect of infusion of glucose into the carotid artery upon fasting lipolysis in the baboon

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Abstract

The effect of glucose infusion on rates of lipolysis were studied in a group of chair-trained papio baboons that had been prepared for chronic intravenous and intracarotid infusion. All studies were carried out after a 24 hr period of fasting and when the animals were fully awake. After a control interval of 1 hr, a glucose infusion was begun either intravenously or intra-arterially. The infusion was continued at a constant rate for 2 hr and then changed directly to the alternate route and continued an additional 2 hr. Blood samples were collected at 30-min intervals for glucose, free fatty acid (FFA), glycerol, insulin, and in some studies, growth hormone (GH) determination. When glucose doses less than 0.5 mg/kg per min were used, no change in the products of lipolysis was noted during either venous or carotid administration, and glucose and insulin levels remained stable or fell gradually. With doses of glucose between 0.5 and 0.6 mg/kg per min, a greater fall in both FFA and glycerol was noted during carotid administration. No definite changes in plasma glucose or insulin levels were noted during either infusion period. These changes in lipolysis were noted regardless of the sequence of infusion, and a similar differential suppression of FFA was noted during a 24 hr period of carotid glucose administration. When doses of glucose larger than 0.6 mg/kg per min were used, inhibition of lipolysis was noted during both phases of infusion. No definite change in GH levels was noted during the periods of fasting, and the levels of the hormone did not appear to be related to changes in glucose, insulin, or FFA levels.

Authors

Martin J. Conway, Charles J. Goodner, Jon H. Werrbach, Charles C. Gale

Cholesterol balance and fecal neutral steroid and bile acid excretion in normal men fed dietary fats of different fatty acid composition

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Abstract

Six normal men were fed formula diets containing either highly saturated fat (cocoa butter, iodine value 32) or polyunsaturated fat (corn oil, iodine value 125). The sterol balance technique was used to compare the changes in serum cholesterol concentration with the excretion of fecal steroids. The method used for the analysis of fecal steroids was chemical, with a final identification and quantification by gas-liquid chromatography. It was confirmed that the chemical method for fecal steroid analysis was accurate and reproducible.

Authors

William E. Connor, Donald T. Witiak, Daniel B. Stone, Mark L. Armstrong

Erythrocytosis associated with hemoglobin Rainier: oxygen equilibria and marrow regulation

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Abstract

Hemoglobin Rainier (β145 tyrosine→histidine) is an abnormal hemoglobin associated with increased oxygen affinity, decreased heme-heme interaction, presence of a Bohr effect, and erythrocytosis, but without obvious clinical sequelae.

Authors

John W. Adamson, Julian T. Parer, George Stamatoyannopoulos, S. Heinenberg

Radioimmunoassay of beta lipoprotein—protein of rat serum

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Abstract

A double antibody radioimmunoassay for rat serum beta lipoprotein-protein (beta Lp-protein) is described. The protein was purified by ultracentrifugation, selective heparin-manganous precipitation, and gel filtration on Sephadex G-200. Antiserum was prepared in rabbits by biweekly immunization and absorbed with nonbeta lipoprotein containing rat serum. Iodination with 125I and purification by gel filtration provided a radiolabeled protein which was > 98% displaced by purified beta lipoprotein in the immunoassay. The radioimmunoassay was sensitive to beta Lp-protein concentrations from 0.1 to 1.5 μg. Specificity of the immunoassay for beta Lp-protein was established by comparison of the displacement curves obtained with serum very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and density (d) > 1.21 fractions and with the beta and alpha migrating lipoproteins eluted from paper electrophoretograms. Suitability of the assay for measuring beta Lp-protein in serum was established by demonstrating 100% recovery of beta lipoprotein added to whole serum and by the absence of immunoreactive beta Lp-protein in serum of orotic acid-treated rats. Examination of sera from six other vertebrates species revealed partial cross-reactivity. Normal rat serum was found to contain 0.25±0.01 mg/ml of beta Lp-protein and hepatic production by an isolated perfused rat liver system was determined as 0.145 mg/hr.

Authors

R. Philip Eaton, David M. Kipnis

Effect of dl-ethionine on the intestinal absorption and transport of palmitic acid-1-¹⁴C and tripalmitin-¹⁴C. Role of intramucosal factors in the uptake of luminal lipids

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Abstract

The effect of DL-ethionine on the uptake and transport of lipid by the rat small intestine was investigated. A cottonseed oil emulsion containing 14C-labeled tripalmitin or palmitic acid was administered intragastrically to rats pretreated with DL-ethionine, DL-ethionine plus methionine, or saline, and the rats were sacrificed 2, 4, and 6 hr later. Lipids from the plasma, the stomach, the colon, the luminal contents of the small intestine, and the wall of the small intestine were extracted, fractionated, and their radioactivity assayed.

Authors

Jacques I. Kessler, S. Mishkin, J. Stein

Effect of adenosine 3′,5′-monophosphate on production of glucose and ammonia by renal cortex

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Abstract

In studies employing rat renal cortical slices, the addition of adenosine 3′,5′-monophosphate (cyclic AMP) to the incubation medium caused an increase in production of glucose from glutamine, glutamate, α-ketoglutarate, fumarate, malate, and oxalacetate, but not from glycerol and fructose. These observations suggest that cyclic AMP accelerates a rate-limiting gluconeogenic reaction between oxalacetate and the triose phosphates. The addition to the medium of parathyroid hormone, which is known to increase renal cortical cyclic AMP, also stimulated glucose production from glutamine.

Authors

Anthony S. Pagliara, A. David Goodman

Effect of diet and triiodothyronine on the activity of sn-glycerol-3-phosphate dehydrogenase and on the metabolism of glucose and pyruvate by adipose tissue of obese patients

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Abstract

Lipogenesis and the metabolism of sn-glycerol-3-phosphate were studied in 23 fat biopsies from eight grossly obese patients. The first biopsy was obtained after a minimum of 12 days on a 3500 cal diet, the second biopsy after 2 wk on a 900 cal diet, and the third biopsy after an additional 2 wk on 900 cal supplemented with thiiodothyronine, 250 μg/day.

Authors

G. A. Bray, Stella Mothon, Andrea Cohen

Organ culture of mucosal biopsies of human small intestine

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Abstract

In vitro experiments of small intestinal mucosal function and metabolism utilizing excised tissue have been limited to a few hours by rapid epithelial cell necrosis which occurs with current incubation methods. We describe a method for culturing human mucosal biopsies for up to 24 hr employing organ culture methodology and demonstrate its potential application to studies of mucosal function. Peroral biopsies were placed in organ culture plates and maintained with modified Trowell's medium in 95% O2-5% CO2 at 37°C for 6-24 hr. To study cell proliferation, 2 μc of thymidine-3H was added per ml of medium. To study fat absorption, biopsies were exposed to micellar solutions of linolenic acid, monoolein, and taurodeoxycholate in Krebs-Ringer buffer for 15 min after culture in vitro for 24 hr. After 24 hr of culture, villi were shorter and wider. Cells in the lamina were reduced in number. Light and electron microscopic morphology of epithelial cells compared favorably to those of control biopsies except in occasional areas of partial necrosis. Some absorptive cells were more cuboidal and contained more lysosomes; many appeared entirely normal. Most crypt cells appeared normal; some contained increased glycogen and lysosomes. Mitoses were present, and labeled cells were abundant in crypts of biopsies after 6 hr of incubation with thymidine-3H-containing medium. By 24 hr. labeled cells migrated to the base of the villi. When biopsies cultured in vitro were subsequently exposed to micellar lipid, numerous lipid droplets were identified in the cytoplasm of absorptive cells. Thus, after 24 hr in vitro under these culture conditions, many human small intestinal epithelial cells maintain near normal morphology, epithelial cell proliferation proceeds, and fat absorption occurs.

Authors

Thomas H. Browning, Jerry S. Trier

Development of γG, γA, γM, β_1C/β_1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, plasminogen, α₁-antitrypsin, orosomucoid, β-lipoprotein, α₂-macroglobulin, and prealbumin in the human conceptus

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Abstract

The synthesis of γG, γA, γM, β1C/β1A, C′1 esterase inhibitor, ceruloplasmin, transferrin, hemopexin, haptoglobin, fibrinogen, α1-antitrypsin, orosomucoid, β-lipoprotein, α2-macroglobulin, and prealbumin was studied in 15 normal human embryos and fetuses of 29 days to 18 wk gestation and in the yolk sacs of four embryos from 5.5 to 11.5 wk gestation using tissue culture in 14C-labeled amino acids followed by radioimmunoelectrophoresis. The human embryo as early as 29 day gestation synthesized β1C/β1A, C′1 esterase inhibitor, transferrin, hemopexin, α1-antitrypsin, β-lipoprotein, α2-macroglobulin, and prealbumin in culture. At 32 days gestation ceruloplasmin and orosomucoid were also synthesized, but synthesis of fibrinogen was not observed before 5.5 wk. Synthesis of γM occurred as early as 10.5 wk gestation, and γG synthesis was found in cultures as early as 12 wk gestation; γA synthesis was not detected in any of the tissue cultures. With the exception of the γ-globulins, each of the proteins studied was synthesized by the liver, but additional sites of synthesis for some of these proteins were also found. Synthesis of γG and γM occurred primarily in the spleen, but other sites of synthesis were noted as well.

Authors

David Gitlin, Anita Biasucci

Familial hyperlysinemia with lysine-ketoglutarate reductase insufficiency

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Fibroblasts grown in tissue culture from the skin of normal subjects have lysine-ketoglutarate reductase activity (lysine: α-ketoglutarate: triphosphopyridine nucleotide (TPNH) oxidoreductase (ε-N-[L-glutaryl-2]-L-lysine forming)). The activity of the enzyme is considerably reduced in the skin fibroblasts grown from three siblings with hyperlysinemia. The high concentrations of lysine in the blood of these patients, the previous demonstration in the intact subject of a reduction in the ability to degrade lysine, and the present demonstration of diminished lysine-ketoglutarate reductase activity, accurately define the metabolic defect and establish the saccharopine (ε-N-[L-glutaryl-2]-L-lysine) pathway as the major degradative pathway for lysine in the human.

Authors

Joseph Dancis, Joel Hutzler, Rody P. Cox, Norman C. Woody

The gastrointestinal stimulus to insulin release: I. Secretin

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The gastrointestinal stimulus to the release of insulin has been investigated in man by the use of a radioimmunoassay for secretin. Serum secretin levels rose rapidly after the oral ingestion of glucose or protein and preceded the elevation of serum insulin. An intravenous infusion of highly purified secretin caused a release of insulin when the serum secretin levels were within the physiological range.

Authors

D. J. Chisholm, J. D. Young, L. Lazarus

Derivation of a three compartment model describing disappearance of plasma insulin-¹³¹I in man

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Abstract

Insulin-131I was administered intravenously to normal subjects, to patients with maturity-onset diabetes and normal renal function, and to nondiabetic patients with renal failure. The ensuing plasma disappearance curves of immunoprecipitable radioactive insulin were determined, and these data were analyzed in a variety of ways. Firstly, fractional irreversible loss rates of insulin from plasma were calculated and found to be greatly diminished in patients with renal failure (t½ = 39 min), as compared with normal (t½ = 15 min) and diabetic subjects (t½ = 12 min). Secondly, plasma insulin-131I disappearance curves were resolved into sums of three exponentials by the method of “peeling,” and values for the resultant three slopes and half-lives were determined. Patients with normal renal function had similar values for all parameters, while those patients with renal failure were differentiated on the basis of the slope of the last component, with a prolongation of its half-life to 275 min (approximately twice normal). Finally, a three pool model was formulated to describe the kinetics of plasma insulin disappearance in man, representing plasma (pool 1), interstitial fluid (pool 2), and all tissues in which insulin is utilized and degraded (pool 3). The proposed model adequately describing the disappearance curves of insulin-131I observed in all patients indicated that volumes (per cent body weight) of pool 1 (4.04) and pool 2 (10.11), calculated on the basis of the model and the experimental data, corresponded closely to estimates of plasma and interstitial fluid volumes obtained by independent means. It also demonstrated that patients with renal failure were characterized by a decreased removal rate of insulin from pool 3 and an increased recycling rate of insulin from pool 3 to pool 2. It is concluded that the proposed model represents a reasonable description of the kinetics of insulin distribution and degradation, and that its use provides quantitative insights into the physiology of insulin metabolism.

Authors

Abraham Silvers, Robert S. Swenson, John W. Farquhar, Gerald M. Reaven

Micropuncture studies of the sweat formation in cystic fibrosis patients

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Abstract

In order to determine whether the precursor solution of sweat is abnormal in cystic fibrosis, osmolality and concentrations of sodium and chloride were measured in fluid obtained by micropuncture from the sweat gland coil of the nail fold of patients with this disease. Osmolality was 323±4.8 SE (mOsm/kg of water), sodium concentration was 151±1.1 SE (mEq/liter), and chloride concentration was 124±6.0 SE (mEq/liter). The sweat:plasma ratio for osmolality averaged 1.1±0.015 SE. These values are not significantly different from the corresponding ones obtained previously in normal individuals. It is concluded therefore that the disturbance of sweat gland function as far as electrolytes are concerned is restricted to the excretory ducts.

Authors

Irene J. Schulz

Leukocyte myeloperoxidase deficiency and disseminated candidiasis: the role of myeloperoxidase in resistance to Candida infection

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Abstract

The neutrophils and monocytes of a patient with disseminated candidiasis were found to lack detectable levels of the lysosomal enzyme myeloperoxidase (MPO), although they had normal levels of other granule-associated enzymes. Leukocytes from one of the patient's sisters also lacked detectable MPO; leukocytes from his four sons contained approximately one-third of mean normal peroxidase levels. Neither the patient nor his affected relatives had experienced frequent or unusual bacterial infections.

Authors

Robert I. Lehrer, Martin J. Cline

An enzymatic basis for Lewis blood Types in man

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Abstract

Milk from women with blood type Le(a+) or Le(b+) contains a specific fucosyltransferase not found in the milk of women with blood type Le(a- b-). The enzyme, a guanosine diphosphate L-fucose: N-acetyl-β-D-glucosaminylsaccharide α-4-L-fucosyltransferase is apparently required for the synthesis of the structural determinants of Lea and Leb specificity, both of which contain fucose in an α-1,4 linkage to N-acetylglucosamine. The same enzyme is also involved in the synthesis of milk oligosaccharides, as two oligosaccharides which contain this linkage are absent from the milk of women with Le(a- b-) blood type.

Authors

Evelyn F. Grollman, Akira Kobata, Victor Ginsburg

Complement metabolism in man: hypercatabolism of the fourth (C4) and third (C3) components in patients with renal allograft rejection and hereditary angioedema (HAE)

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Abstract

Highly purified and radioiodinated human C4 and (or) C3 were administered to patients with renal allografts in rejection, with hereditary angioedema (HAE), with chronic glomerulonephritis, and to control subjects. The latter group included normal individuals, anephric patients before transplantation, and stable renal allograft recipients. The catabolic rates of these complement proteins were determined by analysis of the disappearance of plasma protein-bound radioactivity (km), and by direct measurement of urinary excretion of radioactivity (ku). The correlation coefficient between these two methods was 0.96. The mean ±2 SD for catabolic rates in the control subjects was 0.9-2.7% plasma pool/hr for C4 and 0.9-2.0% plasma pool/hr for C3. Patients experiencing renal allograft rejection had unstable levels of C4 and C3, and exhibited moderate hypercatabolism of both proteins. One patient with chronic glomerulonephritis had hypercatabolism of C4 and C3 in the presence of stable normal serum levels. In patients with HAE who had extremely low levels of C4, catabolic rates for C4 were markedly elevated (3.7, 5.8, 7.0 and 8.8%/hr). Analysis of plasma curves in HAE revealed a three component disappearance curve instead of the two component curve in control subjects receiving the same preparation. Even though C3 levels were normal, moderate hypercatabolism of C3 was also present in HAE (2.6, 2.8, 2.8, and 3.2% of pool/hr). The marked hypercatabolism of C4 in HAE constitutes the first direct evidence for the in vivo destruction by uninhibited C1 esterase of its natural substrate C4. The moderate hypercatabolism of C3 is consistent with the in vivo formation of C3-convertase.

Authors

Charles B. Carpenter, Shaun Ruddy, Isam H. Shehadeh, Hans J. Müller-Eberhard, John P. Merrill, K. Frank Austen

Studies on the role of angiotensin in experimental renovascular hypertension: an immunologic approach

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Abstract

The role of angiotensin in three forms of experimental hypertension was assessed in rats. First, the acute blood pressure response to injected angiotensin amide and angiotensin acid was determined. Rats made hypertensive with deoxycorticosterone and saline showed exaggerated responses; rats made hypertensive by clipping one renal artery showed depressed responses; and rats made hypertensive by clipping one renal artery and contralateral nephrectomy showed normal responsivity to angiotensin amide but depressed responsivity to angiotensin acid. These findings suggested that different mechanisms may be involved in the three types of hypertension studied.

Authors

A. R. Christlieb, T. U. L. Biber, R. B. Hickler

The relationship between peritubular capillary protein concentration and fluid reabsorption by the renal proximal tubule

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Abstract

The relationship between peritubular capillary protein concentration and rate of sodium reabsorption by the rat proximal tubule was examined using free-flow recollection micropuncture techniques. Tubule fluid-to-plasma inulin ratios were measured before, during, and at successive intervals after brief (15-25 sec) intra-aortic injections (at the level of the renal artery) of colloid-free, isoncotic, and hyperoncotic solutions. Arterial hematocrit and protein concentrations were measured simultaneously in these rats. In other rats, total protein concentration of peritubular capillary blood plasma was determined before, during, and after these same infusions with a newly described submicroliter fiber-optic colorimeter.

Authors

Barry M. Brenner, Kenneth H. Falchuk, Robert I. Keimowitz, Robert W. Berliner

Breakdown products of C′3 in human synovial fluids

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Abstract

Activation of the complement sequence results in conversion of the third component of complement (C′3) to an inactive product (C′3i) and the elaboration of additional fragments of smaller molecular weights and faster electrophoretic mobilities. Immunoelectrophoretic analysis of fresh synovial fluids with an anti-human C′3 antiserum disclosed in some a variable degree of conversion of C′3 to C′3i, but a more striking finding was an additional line in the α-globulin region. This faster migrating protein gave a reaction of partial identity with C′3/C′3i. With this antiserum a similar pattern developed when fresh human serum was incubated with immune complexes, or aggregated γ-globulin. The same breakdown product of C′3 was obtained by treatment of fresh human serum with Zymosan, ammonium, hydrazine, agar, or dextran. Heating serum at 56°C for 1 hr destroys the breakdown product; aging of serum produces it.

Authors

Nathan J. Zvaifler

Increased sodium reabsorption in the proximal and distal tubule of caval dogs

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Abstract

The effects of water diuresis, hypotonic NaCl, and hypotonic mannitol diuresis on renal sodium and water excretion were examined in normal dogs and in dogs with chronic constriction of the thoracic inferior vena cava and ascites (caval dogs). During all three diuretic states, the capacity to excrete solute-free water relative to the supply of sodium to the water clearing segment of the nephron was significantly greater in the caval dog. This finding was most evident during hypotonic NaCl diuresis but was also striking during hypotonic mannitol diuresis despite the more unfavorable gradient for sodium reabsorption at the distal tubule produced by this agent in caval dogs. In addition, fractional distal sodium load was significantly smaller in caval dogs during water diuresis and could not be increased as readily as in normal dogs by hypotonic NaCl or mannitol infusion. The data indicate that fractional sodium reabsorption is increased at the water clearing segment and the proximal tubule in caval dogs.

Authors

George J. Kaloyanides, Roy J. Cacciaguida, Nancy C. Pablo, Jerome G. Porush

Cellular transport of l-histidine in Hartnup disease

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Abstract

The urinary excretion, the intestinal absorption, and the elimination of histidine from blood were studied in two patients with Hartnup disease. On standard diet the patients lost a great proportion of the dietary histidine in the urine, whereas the fecal loss was negligible. A high oral dose of L-histidine gave only a slight increase in plasma histidine and no increase in fecal histidine, but a considerable increase in the urinary histidine output. Intravenously administered L-histidine was eliminated more rapidly than in controls. The lack of increase in plasma histidine after the oral loading may be explained by the rapid elimination from the blood. This was mainly due to a rapid cellular uptake of histidine which is supposed to be a normal reaction of histidine-deprived cells. Thus the only obvious defect in the histidine transport in Hartnup disease is the reabsorption defect in the renal tubules. A generally impaired cellular transport of L-histidine is improbable.

Authors

Sverre Halvorsen, Olof Hygstedt, Rudolf Jagenburg, Ottar Sjaastad

Kinetic studies of plasma free fatty acid and triglyceride metabolism in man

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Abstract

Plasma transport of free fatty acids (FFA) and triglyceride fatty acids (TGFA) was studied in seven subjects with normal lipid metabolism, one case of total lipodystrophy, and one case of familial hyperlipemia (Type V). Studies were carried out after intravenous injection of radioactive FFA, of lipoproteins previously labeled in vitro in the triglyceride moiety, or both.

Authors

R. Philip Eaton, Mones Berman, Daniel Steinberg

Normal and abnormal regulation of β-MSH in man

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Abstract

The regulation of plasma β-melanocyte-stimulating hormone (β-MSH) in man has been studied utilizing a radioimmunoassay previously described (1). In normal subjects plasma β-MSH values ranged from 20 to 110 pg/ml. Metyrapone increased and dexamethasone decreased plasma β-MSH levels. Surgical stress stimulated β-MSH secretion. Plasma β-MSH levels were elevated in patients with untreated Addison's disease and untreated congenital adrenal hyperplasia, and these levels fell to normal during glucocorticoid therapy. In patients with Cushing's syndrome due to pituitary adrenocorticotropic hormone (ACTH) excess, plasma β-MSH was slightly elevated before treatment. In those patients who developed pituitary tumors and hyperpigmentation after bilateral adrenalectomy, plasma β-MSH was greatly elevated. In patients with Cushing's syndrome due to adrenal tumor, plasma β-MSH was subnormal. In patients with the ectopic ACTH syndrome, the levels of plasma β-MSH were high. Plasma β-MSH had a diurnal variation in normal subjects, patients with Addison's disease, and patients with congenital adrenal hyperplasia; but the normal diurnal variation was lost in patients with Cushing's disease. In patients with high plasma β-MSH, simultaneous determinations of plasma ACTH showed close correlation between the degree of elevation of ACTH and that of β-MSH. In extracts of tumors from patients with the ectopic ACTH-MSH syndrome the quantities of the two hormones were roughly equivalent. In patients with hyperpigmentation due to a variety of disorders other than pituitary-adrenal abnormalities, plasma β-MSH was normal. It is concluded that the secretion of β-MSH is regulated by the same factors that regulate ACTH.

Authors

Kaoru Abe, Wendell E. Nicholson, Grant W. Liddle, David N. Orth, Donald P. Island