The quantitative relationship of urinary peptide hydroxyproline excretion to collagen degradation

• Text
• PDF

Abstract

To determine the quantitative relationship of urinary hydroxyproline peptide excretion to collagen breakdown, known quantities of radioactive hydroxyproline peptides were administered to unlabeled animals and excertion of radioactivity in respiratory carbon dioxide, urine, and feces was measured. The major routes of excretion of collagen peptide metabolites were respiratory carbon dioxide (75%) and urine, as hydroxyproline-containing peptides (25%).

Authors

Phillip H. Weiss, LeRoy Klein

Studies on the prekallikrein (kallikreinogen)-kallikrein enzyme system of human plasma: I. Isolation and purification of plasma kallikreins

• Text
• PDF

Abstract

By measurement of its arginine esterase activity, plasma kallikrein was purified from fresh frozen ACD plasma. The steps involved alcohol fractionation, isoelectric precipitation, and carboxymethyl (CM) Sephadex and DEAE cellulose chromatography. Three enzymatically active fractions were finally isolated and termed plasma kallikreins I, II, and III; they represented purifications of 970,320- and 590-fold, respectively. All three kallikreins were active biologically; they increased vascular permeability in the guinea pig and released a kinin from human plasma, as measured in the rat uterus bioassay. Bradykinin and/or closely related kinins were identified in the kallikrein I plasma digest by radioimmunoassay.

Authors

Robert W. Colman, Lawrence Mattler, Sol Sherry

Studies on the prekallikrein (kallikreinogen)—kallikrein enzyme system of human plasma: II. Evidence relating the kaolin-activated arginine esterase to plasma kallikrein

• Text
• PDF

Abstract

Evidence is presented in this paper that the kaolin-activated arginine esterase of plasma is related to plasma kallikrein activity. Such a relationship is based on studies that (1) establish a constant ratio of esterase activity on various synthetic substrates for the kaolin-activated arginine esterase, purified kallikrein(s), and preparations obtained during the fractionation procedure; (2) exclude other known plasma and tissue arginine esterases; (3) confirm the requirement for factor XII in the activation of the enzyme precursor; and (4) show similarities in behavior between the plasma esterase and purified kallikrein(s) toward a variety of inhibitors.

Authors

Robert W. Colman, Lawrence Mattler, Sol Sherry

Influence of hemoglobin precipitation on erythrocyte metabolism in alpha and beta thalassemia

• Text
• PDF

Abstract

Certain aspects of the metabolism of centrifuged young and old erythrocytes in hemoglobin H disease have been examined and compared with similar studies of beta thalassemia and normal cells. Glycolysis, hexose monophosphate shunt activity (HMPS), potassium flux, and glutathione (GSH) content were measured. The distributions of hemoglobins H and F, as well as the activities of erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and glutamic oxalacetic transaminase (GOT), were utilized for estimations of the relative ages of the cell samples. The young erythrocytes in hemoglobin H disease differed in several respects from older hemoglobin H cells. They contained more soluble hemoglobin H and GSH and, after splenectomy, fewer inclusions. HMPS activity was subnormal in hemoglobin H young cells and rose to normal activity in old cells. Potassium flux tended to increase in old cells when inclusions were present.

Authors

David G. Nathan, Thomas B. Stossel, Robert B. Gunn, Harold S. Zarkowsky, Mitsuko T. Laforet

Effect of sodium phenobarbital on bilirubin metabolism in an infant with congenital, nonhemolytic, unconjugated hyperbilirubinemia, and kernicterus

• Text
• PDF

Abstract

Sodium phenobarbital and various hormones, compounds capable of hepatic enzyme induction, were given to an infant boy with congenital, nonhemolytic, unconjugated, hyperbilirubinemia and severe kernicterus for prolonged periods between the ages of 2 and 25 months to determine their effect on serum bilirubin concentrations. Phenobarbital, 5 mg/day orally, on two occasions decreased serum bilirubin concentrations approximately threefold over a period of 30 days. Withdrawal of phenobarbital after the first study resulted in a gradual (30 days) return of serum bilirubin to pretreatment levels. The lower serum bilirubin concentrations observed when phenobarbital therapy was reinstituted were maintained for 61 days on 2.5 mg/kg per day of the drug. Orally administered L-triiodothyronine, 0.05-0.1 mg/day for 71 days, intramuscular human growth hormone, 1 mg/day for 21 days, and testosterone propionate, 0.1 mg/day for 9 days, did not decrease serum bilirubin levels below lowest control values of 18 mg/100 ml.

Authors

John F. Crigler Jr., Norman I. Gold

Extracellular fluid in individual tissues and in whole animals: the distribution of radiosulfate and radiobromide

• Text
• PDF

Abstract

Radiosulfate, 35SO4, and radiobromide, 82Br, were administered simultaneously to rats and dogs. In rats, the apparent volume of distribution of 82Br averaged 30% of body weight and was constant between 0.5 and 35 hr after injection. The apparent volume of distribution of 35SO4, corrected for urinary loss, increased by 6% body weight/hr: the extrapolated volume at zero time was 88% of bromide space. Analysis of individual tissues and carcasses for 82Br and inorganic 35SO4 showed that equilibration of both isotopes in several organs and in the whole carcass was rapidly achieved within 1 to 2 hr: no further increase in measured spaces occurred in 24 hr. The carcass inorganic sulfate space was 92%±2% of the bromide space in intact rats, and showed no increase with time. However, a progressively greater fraction of the injected 35SO4 was not recovered, owing to metabolic alteration. In eviscerated rats, the inorganic sulfate space was a smaller and much more constant fraction (79.8% ±0.4%) of the bromide space, showing that at least 20% of body bromide (and hence chloride) is nonextracellular. The viscera chiefly responsible for the higher ratio of spaces in the intact animal were the liver, small bowel, and kidney. In the last two organs, excess inorganic 35SO4 (beyond the bromide space) was attributable to trapped transcellular fluid in which sulfate had been concentrated more than chloride (or bromide). Excess sulfate in liver and cartilage could not be explained in this manner: the results suggest passive binding of sulfate, but could reflect active cell uptake in these tissues. No excess sulfate was found in skin or tail. The implications of these observations with respect to the distribution of body chloride and the measurement of extracellular space are discussed. The extracellular volume of the rat is estimated to be 24% of body weight.

Authors

T. Martin Barratt, Mackenzie Walser

Dietary perturbation of calcium metabolism in normal man: compartmental analysis

• Text
• PDF

Abstract

The effect of dietary calcium intake on calcium metabolism was studied in eight normal volunteers by multicompartmental analysis of radiocalcium and balance data. In paired studies of six normal subjects on normal and high or low calcium intakes, necessary and sufficient criteria were used to determine changes in calcium metabolic parameters produced by alterations in dietary calcium. These changes involved gastrointestinal calcium absorption rate, renal and endogenous fecal rate constants, and bone resorption rate. Bone accretion rate and compartment sizes need not change between the paired studies. The changes of parameters involving kidney, gut, and bone were in a direction to support calcium homeostasis and were compatible with the pattern of changes produced by parathyroid hormone. However, the source of the stimulus for hormone secretion was not apparent since plasma calcium concentrations showed no significant difference between paired studies. The implications of these findings relative to control of hormone secretion, calcium regulatory mechanisms, and metabolic bone disease are discussed.

Authors

James M. Phang, Mones Berman, Gerald A. Finerman, Robert M. Neer, Leon E. Rosenberg, Theodore J. Hahn

Effects of dietary fats on plasma lipids and lipoproteins: an hypothesis for the lipid-lowering effect of unsaturated fatty acids

• Text
• PDF

Abstract

Several aspects of the effects of dietary fat on plasma lipids and lipoproteins were investigated in 12 subjects during the long-term feeding of formulas containing 40% of their calories as either saturated or unsaturated fats. The changes in fatty acid composition of plasma lipids, shown previously to occur after prolonged feedings of a dietary fat, required 10-14 days to be complete and were synchronous with the effect of the fat on plasma lipid concentrations. The change in lipid concentration occurred in low but not in high density lipoproteins. The effects on lipid levels of the low density lipoproteins were found to occur with little or no effect on the concentration of the protein moiety of these lipoproteins; as a result, cholesterol- and phospholipid to protein ratios in low density lipoproteins fell during unsaturated fat feeding. The effects of dietary fat on plasma phospholipids were studied in detail: the relative amounts of phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and lysophosphatidylcholine were unaffected by the type of dietary fat. However, the molecular species of phosphatidylcholine were markedly affected. More than 90% of the fatty acids at the α-position were saturated during both saturated and unsaturated feedings. In contrast, during unsaturated feedings, linoleate at the β-position outnumbered oleate by approximately 4:1, whereas during saturated feedings these two types of fatty acids were present in nearly equal amounts.

Authors

Norton Spritz, Maurice A. Mishkel

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D₃ into lymph

• Text
• PDF

Abstract

The absorption of endogenous cholesterol, labeled with tracer doses of cholesterol 14C or cholesterol-3H and of near physiological doses of vitamin D3-3H was studied in rats with cannulated intestinal lymphatics. The effects of administering mixed micellar solutions of fatty acid, monoglyceride, and bile salt on the absorption of these labeled sterols was determined. It was observed that the specific activity of free cholesterol and the amounts of vitamin D3 appearing in lymph were significantly increased during the intraduodenal administration of mixed micellar solutions of either linoleic or palmitic acid, in contrast to control rats receiving a micellar solution of taurocholate. These increases were related linearly to the lymph triglyceride level. In addition it was observed that when the linoleic acid solution was administered there was a more marked increase in the ratio of the specific activities of free and esterified cholesterol in lymph than with either the palmitic acid or taurocholate solutions.

Authors

Gilbert R. Thompson, Robert K. Ockner, Kurt J. Isselbacher

Activation of aldosterone secretion in primary aldosteronism

• Text
• PDF

Abstract

Angiotensin infusion evokes marked increases in aldosterone secretion in primary aldosteronism and little change in secondary aldosteronism. The low plasma renin activity of primary aldosteronism and the elevated plasma renin activity of secondary aldosteronism are thought to account for this differential response. The effect of angiotensin on aldosterone and 18-hydroxycorticosterone secretion was studied during adrenal vein catheterization in seven patients with primary aldosteronism (whose plasma renin activity had been elevated following spironolactone therapy), one hypertensive patient with normal plasma renin activity and normal aldosterone secretion, two patients with secondary aldosteronism who had elevated plasma renin activity, and one anephric patient whose plasma renin activity was 0. Adrenal venous aldosterone and 18-hydroxycorticosterone were measured before and after a ten min sub-pressor angiotensin infusion.

Authors

Richard F. Spark, Sidney L. Dale, Paul C. Kahn, James C. Melby

The enzymatic mechanisms for deoxythymidine synthesis in human leukocytes: IV. Comparisons between normal and leukemic leukocytes

• Text
• PDF

Abstract

(1) Synthesis of deoxythymidine by either direct transfer of deoxyribosyl to thymine (pyrimidine deoxyribosyltransferase) or by a coupled deoxynucleoside phosphorylase mechanism is approximately twofold greater with normal leukocyte extracts (55 to 88% granulocytes) than with extracts prepared from leukocytes obtained from patients with chronic myelogenous leukemia. Activities in lymphocytes (normal or leukemic) are one-fifth the activity of normal granulocytes.

Authors

Robert C. Gallo, Seymour Perry

Influence of 2,3-diphosphoglycerate metabolism on sodium-potassium permeability in human red blood cells: studies with bisulfite and other redox agents

• Text
• PDF

Abstract

It is known that bisulfite ions can selectively deplete red blood cells of 2,3-diphosphoglycerate (2,3-DPG). Studies of the effects of bisulfite on sodium-potassium permeability and metabolism were undertaken to clarify the physiologic role of the abundant quantities of 2,3-DPG in human erythrocytes. Treatment of cells with bisulfite results in a reversible increase in the passive permeability to Na and K ions. Metabolism of glucose to lactate is increased, with a rise in the intracellular ratio of fructose diphosphate to hexose monophosphate. Cell 2,3-DPG is quantitatively converted to pyruvate and inorganic phosphate. The permeability effects of bisulfite are countered by ethacrynic acid and by such oxidizing agents as pyruvate and methylene blue. Taken together, the results suggest that the effects on Na-K flux of bisulfite are related more to the reducing potential of this anion than to its capacity to deplete cells of 2,3-DPG.

Authors

John C. Parker

Subunit dissociation of certain abnormal human hemoglobins

• Text
• PDF

Abstract

The extent of dissociation of various hemoglobins into subunits was estimated from their elution volumes (Ve) on G-100 Sephadex. Under the same controlled conditions carboxyhemoglobins A, A3 (A1), F, S, and C all had the same elution volumes. The carboxy and cyanmet derivatives of hemoglobin Kansas (a variant with very low oxygen affinity) had a relatively high Ve, indicating a decreased mean molecular weight and therefore an increased tendency to form dimers and even monomers. Conversely, the liganded derivatives of hemoglobin Chesapeake (a variant with high oxygen affinity) had a relatively low Ve, suggestive of an impaired degree of subunit dissociation. Deoxyhemoglobin Chesapeake had a Ve identical with that of deoxyhemoglobin A. Cat hemoglobin, known to have an unusually low oxygen affinity, was found to have a higher Ve than human, dog, rabbit, rat, or guinea pig hemoglobins.

Authors

H. Franklin Bunn

Plasma and adipose tissue fatty acids of Diabetic Children On long-term corn oil diets

• Text
• PDF

Abstract

A method is described to determine the fatty acid composition of small samples of subcutaneous adipose tissue, and of fasting plasma free fatty acids (FFA) and triglycerides. These analyses were carried out on samples from five normal children, six diabetic children consuming a standard diabetic diet, 17 diabetic children prescribed a diet rich in corn oil since diagnosis 4-7 years ago, and 2 brothers with familial hypercholesterolemia on a corn oil diet for 3 yr. The results obtained showed that: (1) The composition of adipose tissue triglycerides in the diabetic children on a standard diet was similar to that in the normal children. (2) The 17 diabetic children were consuming different quantities of corn oil. (3) There was a highly significant correlation between the percentage of linoleic acid present in adipose tissue and in the fasting plasma FFA fraction. It is therefore concluded that future assessments of the adherence of these diabetic children to their corn oil diet will be possible by examination of the fasting plasma FFA fraction, obviating the need for repeated adipose tissue biopsies. (4) The sum of the concentration of saturated and monounsaturated fatty acids of the same chain length in adipose tissue was similar to that in the fasting plasma FFA fraction, even though the proportions of individual acids were different in the two fractions.

Authors

Eileen C. Albutt, Graham W. Chance

Some determinants of the effects of VAL-5-angiotensin II amide on glomerular filtration rate and sodium excretion in dogs

• Text
• PDF

Abstract

In 12 dogs anesthetized with chloralose, angiotensin (angiotensin II amide) given intravenously increased the glomerular filtration rate (GFR) of an ischemic kidney while simultaneously having little effect on the GFR of the contralateral kidney. In the ischemic kidney, in 14 of 30 observations, increments of GFR greater than 100% of mean control GFR (9 ml/min) occurred in response to angiotensin. The magnitude of the increase in GFR produced by angiotensin was independent of dose (range 0.005-0.050 μg/kg per min), the degree of accompanying pressor response, and alterations in renal blood flow (RBF) (electromagnetic flow-meter). In the ischemic kidney, increments of GFR could be produced by sub-pressor doses of angiotensin.

Authors

John C. McGiff, James R. Lynch, Jeffrey A. Leinicke, James C. Strand, Ali Aboosi

Lipid metabolism in human platelets: I. Evidence for a complete fatty acid synthesizing system

• Text
• PDF

Abstract

Extracts from human platelets contain the enzymes of de novo fatty acid biosynthesis. The pattern of incorporation of acetate-1-14C into fatty acids by intact platelets indicates that these enzymes function in platelets. The level of acetyl-coenzyme A (CoA) carboxylase activity in extracts of platelets from normal subjects is 0.036 ±0.01 mμmole of malonyl-CoA formed per min per mg of protein and that of fatty acid synthetase is 0.075 ±0.016 mμmole of malonyl-CoA utilized per min per mg of protein. Thus, platelets are the only formed elements of the blood capable of de novo fatty acid synthesis. The capacity of platelets to synthesize fatty acids is similar to human liver based on enzyme activity per milligram of soluble protein.

Authors

Philip W. Majerus, M. B. Smith, G. H. Clamon

Microfibrils of blood platelets: their relationship to microtubules and the contractile protein

• Text
• PDF

Abstract

Human blood platelets were subjected to osmotic shock, brief sonication, pressure homogenization, or treatment with adenosine diphosphate (ADP). These procedures demonstrated an abundance of cytoplasmic microfibrils. The fibrils resembled those found on electron microscopy of partially purified thrombosthenin, the actomyosin-like protein isolated from platelets, and they also appeared to resemble the myofilaments of smooth muscle. Similar fibrils were not found in leukocytes studied under identical conditions. Treatment with colchicine (2 × 10-5 mole/liter) resulted in the disappearance of microtubules but did not affect the morphology of the microfibrils or interfere with platelet-dependent clot retraction. Thus, microfibrils rather than microtubules may represent the morphologic counterpart of the contractile protein. Brief osmotic shock at low temperature or treatment with 10-4 M ADP caused the marginal band of microtubules to be replaced by a bundle of intertwining microfibrils. The apparent inter-conversion of microtubules and microfibrils under a variety of conditions led to the hypothesis that fibrils and tubules consist of similar subunits whose degree of polymerization might be dependent on local cytoplasmic forces. Furthermore, on the basis of these observations, it is postulated that the contractile properties of the cells may be vested in the microfibrils, whereas the tubules may serve to maintain the highly asymmetric shape characteristic of circulating and irreversibly aggregated platelets.

Authors

Dorothea Zucker-Franklin

Fetal insulin and growth hormone metabolism in the subhuman primate

• Text
• PDF

Abstract

The concentrations of plasma glucose, insulin, growth hormone, and immunoreactive growth hormone-like substance in subhuman primate fetal and maternal plasma were examined after the intravascular administration of glucose, arginine, or tolbutamide to the fetus. Cannulation of interplacental vessels permitted studies on the fetus in utero without disruption of fetal-placental-maternal anatomic integrity. Single glucose injections, glucose infusions, and arginine infusions into the fetus did not alter fetal plasma insulin concentrations. In contrast, tolbutamide injections elicited an immediate 3-4-fold increase in fetal plasma insulin concentrations. A bidirectional placental transfer of insulin was demonstrated with the use of simultaneously injected insulin-125I to the mother and insulin-131I to the fetus.

Authors

Daniel H. Mintz, Ronald A. Chez, Edgar O. Horger III

Degranulation of leukocytes in chronic granulomatous disease

• Text
• PDF

Abstract

Quantitative chemical analyses of the subcellular distribution patterns for acid and alkaline phosphatase, beta glucuronidase and peroxidase were obtained for human peripheral blood leukocytes of four patients with chronic granulomatous disease (CGD). Five young adults with acute infections served as controls. The observations were made on fractions obtained by homogenization and centrifugation of leukocytes previously incubated with or without particles for ingestion. Distributions in resting CGD and normal cells were very similar for acid and alkaline phosphatase and peroxidase, but the proportion of beta glucuronidase in the granule fraction of CGD cells was depressed, with an increased proportion in the soluble fraction. Release of granule-bound enzymes during phagocytosis of a variety of particles was the same for CGD and control cells, except that release of beta glucuronidase was less marked in CGD cells. Total enzymatic activity of CGD cells for the hydrolases studied was normal. The data indicated that granular enzymes are released in a normal fashion in phagocytizing CGD cells. Supportive evidence of release of enzymes into the phagocytic vacuole of CGD cells was obtained by an electron microscopic study of myeloperoxidase.

Authors

Robert L. Baehner, Morris J. Karnovsky, Manfred L. Karnovsky

Interaction of the anticoagulant drug warfarin and its metabolites with human plasma albumin

• Text
• PDF

Abstract

The interaction of the anticoagulant drug warfarin and its metabolites with human plasma albumin was studied by equilibrium dialysis. A 20-fold variation of buffer ionic strength (0.017-0.340) caused no significant change in the warfarin association constant. But the binding strength rose significantly as the pH was increased from 6.0 to 9.0 and then declined at pH 10.0. The 6-, 7-, and 8-hydroxywarfarin metabolites showed a 7- to 23-fold reduction in binding strength at pH 10.0. These data indicate that the molecular basis of the interaction is nonelectrostatic and that the introduction of polar hydroxyl groups on the coumarin nucleus by metabolism reduces its hydrophobic binding surface. The interaction was markedly exothermic and showed a positive entropy (increased molecular disorder), which suggests cooperative hydrogen and hydrophobic bonding as the molecular basis for the binding of warfarin to albumin.

Authors

Robert A. O'Reilly

Lipid metabolites of carbon tetrachloride

• Text
• PDF

Abstract

5 min after intravenous injection into rats of 14C- or 36Cl-carbon tetrachloride, liver lipids were found labeled. Most of the radioactivity was found in the phospholipid fraction. The metabolites were shown to comprise a heterogeneous group of branched long-chain chlorinated fatty acids, probably containing the trichloromethyl side chain. Surviving liver slices also formed these metabolites. In a simple chemical system which generates trichloromethyl free radicals, carbon tetrachloride added to methyl oleate to form esters which behaved like the metabolites during counter-current distribution and urea adduction. The evidence strongly suggests the formation of these metabolites by free radical attack on unsaturated lipids. The relation of these observations to current theories of carbon tetrachloride intoxication is discussed.

Authors

Enoch Gordis

Peptide hydrolase activities of the mucosa of human small intestine

• Text
• PDF

Abstract

Few studies have been published on peptide hydrolase activities of human small intestine mucosa. We developed methods to screen tissue extracts for such enzymes and to quantitate hydrolase activities for dipeptides containing the aromatic amino acid L-phenylalanine. The screening procedure indicated glycyl-L-proline hydrolase activity was reduced in biopsy specimens from patients with flattened intestinal mucosa. To explore this further, we established optimal assay conditions for hydrolase activities (a) glycyl-L-proline, (b) L-phenylalanyl-L-proline, (c) L-alanyl-L-phenylalanine, and (d) L-phenylalanylglycine. Biopsy specimens from patients with various intestinal disorders, but without flattened mucosa, and from three patients with flattened mucosa, showed a disproportionate reduction in activities (a) and (b), with the reduction being significantly more marked in the latter patients. We suggest that intestinal imidopeptide hydrolase activities, such as (a) and (b), are sensitive to changes in intestinal disease generally, particularly to the altered physiology associated with flattening of the mucosa, and are secondary to, rather than a cause of, the intestinal pathology.

Authors

William D. Heizer, Leonard Laster

Effects of guanidine derivatives on mitochondrial function. I. Phenethylbiguanide inhibition of respiration in mitochondria from guinea pig and rat tissues

• Text
• PDF

Abstract

Authors