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Biomedical subjects

E Bohn

Publications and source records attributed to E Bohn.

At least 37 records · Page 2Linked to original sources
PubMed1988

Inhibition of liver lysosomal acid phospholipase A1 by blood serum proteins.

Pathophysiological conditions may lead to a release of lysosomal acid phospholipase A1 like that of other lysosomal enzymes into the blood stream. As shown here, various serum protein fractions, obtained by dye-ligand affinity chromatography, inhibit phosphoglyceride hydrolysis by lysosomal acid phospholipase A1 in vitro. Their inhibitory potencies vary considerably, and the degree of inhibition depends on the substrate concentration. A delayed phospholipid flotation rate in sucrose gradients in the presence of one of the more potent inhibitory serum proteins, serum albumin, suggests that the inhibition is due to inhibitor-substrate interactions. Although lysosomal phospholipase A1 activity at blood pH is extremely low, serum proteins may contribute to protect biomembranes which are exposed to the vascular lumen against uncontrolled destruction by this enzyme.

Animals↗
PubMed1987

[The action of benzydamine on phospholipase activation].

The effects of the antiinflammatory drug benzydamine (Tantum) on phospholipase activities were determined in vitro, employing various enzyme preparations (rat liver plasma membranes, endoplasmic reticulum, lysosomes; human seminal plasma) and stereospecifically radiolabeled phosphatidylethanolamines as substrates. Fatty acid release from the sn-2 position was inhibited at drug concentrations above 10(-5) mol/l. Concerning the mode of inhibition, a mixed type was found for the soluble phospholipase A2. Impaired fatty acid release from the sn-2 position might contribute to the mechanism of antiinflammatory action of benzydamine by rendering less free precursor acid available for the synthesis of eicosanoids. Fatty acid release from the sn-1 position was inhibited at benzydamine concentrations from 10(-6)-10(-2) mol/l only in lysosomes, whereas in plasma membranes and endoplasmic reticulum it was stimulated, maximally (at 10(-3) mol/l) about 25% and 50%, respectively.

Animals↗
PubMed1986

The relationship between estrogen levels and diets of Caucasian American and Oriental immigrant women.

The relationship between diet and estrogens was studied in two groups of women with different dietary habits and breast cancer risks. Plasma estrogens and androgens and 24-h urinary and fecal excretion of estrogens were measured in premenopausal and postmenopausal Caucasians and recent Oriental immigrants from Southeast Asia to Hawaii. Premenopausal Caucasians had 30-75% higher plasma estrone and estradiol levels than their age-matched cohorts in Hawaii, and the postmenopausal Caucasians had 3-fold higher plasma levels of estradiol. The Oriental women excreted more than twice the amount of estrogen in their feces but they excreted significantly less in their urine. Thus, the ratio of urinary-to-fecal excretion was approximately 3-5 times higher in young Caucasian women. Analysis of dietary components and plasma estrogens in premenopausal women showed a positive correlation between daily intake of total fat and saturated fat and plasma estrone and estradiol concentrations.

Adolescent↗
PubMed1985

Effects of antimalarial drugs on phospholipase A and lysophospholipase activities in plasma membrane, mitochondrial, microsomal and cytosolic subcellular fractions of rat liver.

Activities of membrane-associated phospholipases A1 and A2, and membrane-associated as well as soluble lysophospholipases were measured in different subcellular fractions of rat liver, using suspensions of stereospecifically labelled radioactive phospholipids as substrates. Plasma membranes and endoplasmic reticulum were shown to contain phospholipase A1 and lysophospholipase activities, both of which could be stimulated by Ca2+, mitochondria Ca2+-dependent phospholipase A2 and cytosol Ca2+-independent lysophospholipase activities. Each of these lipolytic enzymes could be inhibited by antimalarial drugs (chloroquine, mepacrine, primaquine) at concentrations above 1 x 10(-4) M. Inhibition of the alkaline cytosolic lysophospholipase by these drugs was noncompetitive with respect to the substrate, and the inhibitory potency increased, when the pH was raised.

Animals↗
PubMed1983

Effects of the serine protease inhibitors FOY and FOY 305 on phospholipase A1 (EC 3.1.1.32) activity in rat - liver lysosomes.

Rat-liver lysosomal phospholipase A1 activity is unspecifically inhibited in a pH dependent and competitive manner by the cationic amphiphilic protease inhibitors FOY (ethyl 4-6(6-guanidinohexanoyloxy) benzoate methanesulfonate) and FOY 305 (N,N-dimethylcarbamoylmethyl 4-(4-guanidinobenzoyloxy)-phenylacetate methanesulfonate) in concentrations above 10(-4)M. This inhibition may contribute to anti-inflammatory effects of these drugs in that they reduce the release by lysosomal enzymes of fatty acids from membrane phospholipids and consequently decrease the biosynthesis of bioactive oxygenated arachidonate metabolites, among them inflammatory mediators.

Animals↗
PubMed1983

Effects of the anti-inflammatory serine esterase inhibitor, FOY, on phospholipase A2 (EC 3.1.1.4) activity in rabbit polymorphonuclear leukocytes.

Phospholipase A2 activity of polymorphonuclear leukocytes (PMNLs) towards radioactively labelled phosphatidylethanolamine is inhibited by FOY (ethyl 4-(6-guanidinohexanoyloxy)-benzoate methanesulfonate) in concentrations above 10(-4)M. The inhibition is noncompetitive with respect to the substrate employed and depends on the pH. Impairment of PMNL phospholipase A2 activity could play a role in the anti-inflammatory effect of FOY: the release of fatty acids from membrane phospholipids is reduced and consequently also the biosynthesis of bioactive oxygenated arachidonate metabolites, among them inflammatory mediators.

Animals↗
PubMed1983

Computerized dietary analysis systems: a comparative view.

The computerized dietary analysis system that was in use at Tufts University/Frances Stern Nutrition Center and two commercially available systems were compared in a study examining differences between systems. Content, software, data base maintenance, and cost were among the characteristics in which they differed. Calculations on three-day food records provided by five omnivore and five vegetarian women differed from one system to the next. Significant differences were noted for total kilocalories, total fat, saturated fatty acids, polyunsaturated fatty acids, cholesterol, and phosphorus. Unfortunately, it was not possible to describe the degree to which each of the many possible causes of variability may have contributed to the differences in nutrient calculations. However, coding activity did not appear to influence nutrient calculations within one system in a significant manner when skilled coders were employed. We conclude that differences observed in dietary studies using different computerized dietary analysis systems may be due in part not to real differences in subjects but rather to the system employed. Valid reference standards against which each nutrient value can be compared to ascertain exactly what these errors are do not exist. All the information consumers need to make useful comparisons among the various computerized dietary analysis systems is not yet available in a standardized format and is eagerly awaited by this and other groups.

Adult↗
PubMed1982

Effects of antimalarial drugs on several rat-liver lysosomal enzymes involved in phosphatidylethanolamine catabolism.

The effects of three cationic amphiphilic antimalarial drugs (chloroquine, mepacrine and primaquine) on the intralysosomal catabolism of phosphatidylethanolamine and several of its metabolites were studied with rat-liver lysosomes which had been isolated from animals previously treated with Triton WR-1339. The activities of each of the various enzymes involved in the main pathways of intralysosomal phosphatidylethanolamine degradation (Kunze, H., Hesse, B. and Bohn, E. (1982) Biochim. Biophys. Acta 711, 10-18) exhibited almost identical inhibitory sensitivities towards mepacrine and primaquine. In contrast, chloroquine inhibited the activities of the various enzymes to different extents, lysophospholipid acylhydrolase (EC 3.1.1.5) being the most sensitive enzyme, followed by phospholipase A1 (EC 3.1.1.32) and monoacylglycerol lipase, and eventually lysophospholipid monoacylglycerol hydrolase as the least sensitive enzyme. The relative inhibitory potencies towards phospholipase A1 activity of chloroquine were increased with increasing pH, and the mode of inhibition was competitive. In contrast, the inhibitory potencies towards monoacylglycerol lipase activity of chloroquine increased only up to pH 5 but decreased above this value, and the mode of inhibition was noncompetitive.

Animals↗
PubMed1982

Hydrolytic degradation of phosphatidylethanolamine and phosphatidylcholine by isolated rat-liver lysosomes.

Lysosomal catabolism of radioactively labelled phosphatidylethanolamine, phosphatidylcholine and several potential metabolites of these diacylphospholipids was studied using rat-liver lysosomes which had been isolated from Triton WR-1339-treated animals. Hydrolysis of these lipids seems to be restricted to the soluble lysosomal compartment. The initial intralysosomal degradation is predominantly catalysed by phospholipase A1 (EC 3.1.1.32) followed by lysophospholipase (EC 3.1.1.5). The end products of this pathway are free fatty acids and glycerophosphorylethanolamine or glycerophosphorylcholine. These phosphodiesters are not hydrolysed further in lysosomes, as has been shown previously (Fowler, S. and De Duve, C. (1969) J. Biol. Chem. 144, 471-481). The intermediary lysophospholipids, however, are also hydrolysed by an alternative pathway, i.e. by a lysophospholipase which catalyses the hydrolysis of the glycerophosphate ester bond, followed by a monoacylglycerol lipase and a phosphomonoesterase (EC 3.1.3.2), respectively. Besides these two catabolic routes of intralysosomal hydrolysis of phosphatidylethanolamine and phosphatidylcholine, additional pathways are possible, which seem, however, to be of minor importance, at least in the substrate concentration ranges employed in these studies. These additional reactions include attack by a phospholipase A2 (EC 3.1.1.4) and--as discovered recently (Matsuzawa, Y. and Hostetler, K.Y. (1980) J. Biol. Chem. 255, 646-652)--by a phospholipase C (EC 3.1.4.3). Cations such as Mg2+, Ca2+, K+ and Na+ inhibit preferentially deacylation reactions.

Animals↗
PubMed1982

Effects of forced convection of heated air on insensible water loss and heat loss in preterm infants in incubators.

To assess the effect of forced convection of heated air exchange in preterm infants in conventional incubators, we measured insensible water loss and total heat loss in preterm infants in a conventional forced convection incubator (air velocity 15 to 25 cm/second) and in a specially constructed still-air incubator (air velocity 0 to 2 cm/second) at equal operative temperature and humidity. Under the forced conditions, insensible water loss in the preterm infants increased by a mean 52% from 1.04 +/- 0.24 (mean +/- SD) to 1.58 +/- 0.51 ml/kg/hour (P less than 0.001). The ensuing increase in evaporative heat loss was partly reflected in the small but significant increase in total heat loss from 1.65 +/- 0.47 to 1.80 +/- 0.44 kcal/kg/hour (P less than 0.02). In the forced convection incubator, the increased evaporative heat loss in preterm infants was apparently partly compensated by a decreased nonevaporative heat loss. If reduction of insensible water loss is required, preterm infants should not be subjected to forced convection in incubators.

Air↗
PubMed1981

Serum insulin and glucose in hyperinsulinemic subjects fed three different levels of sucrose.

Twenty-four adult men and women, classified as carbohydrate-sensitive on the basis of an exaggerated insulin response to a sucrose load, consumed diets containing 5, 18, and 33% of calories as sucrose for 6 wk each in a cross-over design. The diets contained identical natural and processed foods except for a patty containing 2, 15, or 30% of the calories as sucrose at the expense of wheat starch. Carbohydrate, fat, and protein provided 44, 42, and 14% of the calories, respectively. Of total calories, 25% were consumed at breakfast and 75% at dinner. Initial body weights of the subjects were essentially maintained. Fasting serum insulin levels increased with the sucrose content of the diet and were significantly higher in men than in women. Mean fasting glucose was significantly higher on either 18 or 33% sucrose than on 5% sucrose. The sucrose content of the diet did not affect fasting serum glucagon. When compared to the insulin response to a sucrose load (2 g/kg body weight) after consuming the 5% sucrose diet, serum insulin was significantly higher at 1 h after the 18% sucrose diet and at 0.5, 1, 2, and 3 h after the 33% sucrose diet. Except after 2 h, the glucose response was significantly greater after the 18 and 33% sucrose diets than after the 5% sucrose diet. These results indicate that sucrose intake by carbohydrate-sensitive individuals, even at levels approximating the average United States intake, can produce undesirable changes in several parameters associated with glucose tolerance.

Blood Glucose↗
PubMed1978

Phospholipase A2 and prostaglandins in human seminal plasma.

Lipolytic activity toward phospholipids in human seminal plasma had been ascribed to phospholipase A2 (17). The enzyme is soluble, heat stable at pH 5, requires Ca2+ for optimal activity, inhibited by ionic and nonionic detergents, and catalyzes the hydrolysis of the fatty acids in the 2 position of various sonicated phospholipids. In 12 healthy fertile and 20 subfertile individuals, the total phospholipase A2 activity toward radioactively labeled phosphatidylethanolamine has been compared with the total amounts of prostaglandins E and F, which have been determined by specific radioimmunoassay. There is a statistically significant correlation (p is less than 0.01) between total phospholipase A2 activity and prostaglandin E (and F) contents in the seminal plasma. It is concluded that phospholipase A2 is secreted along with prostaglandins into seminal plasma. This seminal phospholipase A2 possibly reflects the initial step of substrate release for prostaglandin biosynthesis in the human male reproductive system.

Calcium↗
PubMed1976

Phosphatidylethanolamide derivatives of prostaglandins E1 and E2.

Prostaglandins E1 (PGE1) and E2 (PGE2) have been coupled with the amine group of phosphatidylethanolamine (PE) by means of dicyclohexylcarbodiimide. These complexes basically mimic the relaxant and contractile effects of the corresponding free prostaglandins (PGs) on various smooth muscle preparations, but exhibit a delayed onset of action and a lower affinity for the PG receptors. The complexes are comparable with the free, parent PGs, in their intrinsic activities. The same holds true for the effects on blood pressure and on the motility of the uterus in situ. The PGE2-PE complex is hydrolysed to release obviously free PGE2 by cell-free homogenates prepared from various tissues, but not by blood plasma. The PGE2-PE complex is immunologically indistinguishable from the free PGE2.

Animals↗
PubMed1976

Activation of intravascular coagulation by endotoxin: the significance of granulocytes and platelets.

The importance of granulocytes and/or platelets in endotoxin-induced generalized intravascular coagulation was studied as well as thrombocytopenic rabbits. Neutropenia and thrombocytopenia were induced by oral administration of busulphan. Generalized intravascular coagulation, as indicated by renal glomerular microclot formation, was initiated by two intravenous injections of endotoxin. Granulocyte counts before the second injection of endotoxin were most significantly related to activation of intravascular coagulation whereas platelet counts either before the first or second injection of endotoxin were not definitely related to the activation process. Renal glomerular microclots occurred in rabbits after two injections of endotoxin even when the platelet counts were between 500 and 5000/mul. These experiments indicated that granulocytes but not platelets are essential to the activation of endotoxin-induced intravascular coagulation.

Animals↗
PubMed1976

The effect of leukocyte and platelet transfusion on the activation of intravascular coagulation by endotoxin in granulocytopenic and thrombocytopenic rabbits.

The effect of transfusion of peritoneal leukocytes, platelets, or cell suspension medium on the activation of intravascular coagulation and on the generation of capillary microclots was studied in 51 granulocytopenic and thrombocytopenic rabbits. Granulocytopenia and thrombocytopenia induced by feeding the cytoxic drug busulfan prevented the activation of intravascular coagulation and the occurrence of renal glomerular microclots after two injections of endotoxin. The transfusion of platelets into busulfan-pretreated rabbits increased the mean platelet count from 2,400 to 205,000 cells/mul, but platelet-transfused rabbits did not exhibit activation of intravascular coagulation after endotoxin injection. If however, granulocytopenic and thrombocytopenic rabbits were transfused with peritoneal leukocytes (1.0 X 10(9) cells/kg) before the second injection of endotoxin, activation of intravascular coagulation occurred, and microclot formation in renal glomerular capillaries was observed in a high percentage of animals. Positive reactions to endotoxin were obtained in leukocyte-transfused rabbits even with platelet counts of 1,000 cells/mul before the second injection of endotoxin. Thus platelets do not seem to be essentially involved in the activation of intravascular coagulation by endotoxin, whereas the presence of leukocytes is required for triggering endotoxin-induced generalized intravascular coagulation.

Agranulocytosis↗