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Biomedical subjects

F Zilliken

Publications and source records attributed to F Zilliken.

At least 19 recordsLinked to original sources
PubMed1985

Inhibition of in vitro microsomal lipid peroxidation by isoflavonoids.

In a comparative study the inhibition of microsomal lipid peroxidation induced by an Fe2+-ADP-complex and NADPH by naturally occurring isoflavones and their reduced derivatives (isoflavanones and isoflavans) has been examined. It is found that the isoflavanones are more active than the parent isoflavones and the isoflavans are by far the most potent inhibitors. In our in vitro test system 6,7,4'-trihydroxy- and 6,7-dihydroxy-4'-methoxyisoflavans (IC50 values 1.3 X 10(-6) and 1.1 X 10(-6) mol/l respectively) surpass the inhibitory effect of alpha-tocopherol, (+)-cyanidanol-3 and BHA (butylated hydroxyanisole). In order to establish a structure-activity relationship, a few more isoflavans have been included in the investigation.

Animals↗
PubMed1984

Inhibitors of hydrogen peroxide-induced haemolysis of bovine erythrocytes.

The optimal conditions for the haemolysis of bovine erythrocytes by H2O2 have been established. The parameters were concentration of erythrocytes, H2O2 concentration, time, and influence of the solvent in which the substances tested were dissolved. Some inhibitors of this oxidative haemolysis have been employed to serve as model substances for further antihaemolytic investigations with natural products.

Acetates↗
PubMed1984

6,7,4'-Trihydroxyisoflavan: a potent and selective inhibitor of 5-lipoxygenase in human and porcine peripheral blood leukocytes.

The effect of 6,7,4'-trihydroxyisoflavan on human platelet 12-lipoxygenase and human and porcine PMNL 5-lipoxygenase activities has been studied. 6,7,4'-Trihydroxyisoflavan was found to inhibit 5-lipoxygenase more strongly than 12-lipoxygenase; its concentration for 50% inhibition (IC50) was 1.6 microM for human and porcine 5-lipoxygenase and 22 microM for human platelet 12-lipoxygenase. Inhibition of microsomal cyclooxygenase from ram seminal vesicles is exhibited at much higher concentrations of 6,7,4'-trihydroxyisoflavan (IC50 = 200 microM).

Animals↗
PubMed1984

A newly discovered sialidase from Gardnerella vaginalis.

A sialidase (neuraminidase, acylneuraminosyl hydrolase, EC 3.2.1.18) has been discovered and isolated from Gardnerella vaginalis (ex. Haemophilus vaginalis), a possibly pathogenic inhabitant of the female genital tract. Bacteria were grown in peptone-yeast-extract medium with 2.0 mM N-acetylmannosamine as enzyme inductor under CO2 atmosphere. Sialidase activity was found in the bacterial sediment and in the culture medium. The enzyme was liberated from the cells by ultrasonic treatment. Purification was performed by 60-80% ammonium sulfate precipitation and by column chromatography on Sepharose CL-6B and Sephadex G 200. The enzyme revealed a molecular weight in the range of Mr 75 000 and a pH optimum at 5.5. Among the different types of NeuAc-containing glycoconjugates, the enzyme exhibits its highest activities towards the globular glycoproteins alpha 1-acid glycoprotein and fetuin. Taking their cleavage rate as 100, it is around 55 for II3NeuAc-Lac, 45 for bovine submaxillary mucin, 35 for II6NeuAc-Lac and IV3, III6NeuAc2-LcOse4. The rates for III8,II3NeuAc2-Lac, gangliosides and colominic acid are below 20. Due to its specificity pattern, the enzyme may play a role in the pathogenic process of G. vaginalis infections.

Chromatography, Gel↗
PubMed1980

Lipid metabolism of developing central nervous tissues in organotypic cultures. III. Ganglionic control of glycerolipids and fatty acids in cortex grey matter.

Lipid changes in rat brain grey matter were observed in a coculture system of innervating and target explants. The de novo biosynthesis of individual glycerolipids and the metabolism of fatty acids were investigated. Innervating grey matter cultures exhibited a substantial increase in neutral glycerolipid formation. Only slight modifications were observed in the fatty acid fraction. Target cells responded to innervation by a marked increase in phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine formation. In addition, the biosynthesis of arachidonate and docosahexaenoate was drastically enhanced. It is shown that neuritic bridges connecting the explants, rather than soluble factors, account for the effects observed. Putative mechanisms involved in changes of lipid metabolism are discussed.

Animals↗
PubMed1980

Isolation, purification, and properties of neuraminidase from Propionibacterium acnes.

Neuraminidase activity was discovered in 32 of 38 strains of Propionibacterium acnes. Enzyme production was studied in yeast extract bouillon of different pH containing various amounts of human milk as neuraminidase inductor. Enzyme activity was found in the bacterial sediments as well as in the culture filtrates. Since neither ultrasonic treatment nor lysozyme incubation of bacterial sediments did release reasonable amounts of enzyme, culture filtrates were used for enzyme preparation. Neuraminidase was isolated by 40% ammonium sulfate precipitation, dialysis, concentration and repeated gel chromatography on Sephadex G-100. The enzyme posesses a molecular weight of about 33 000 and a pH-optimum around 5.0. The Michaelis constants are 1.8 x 10(-3) M for alpha 2 leads to 3 linked N-acetylneuraminic acid (NeuAc) in II3NeuAc-Lac, 3.7 x 10(-3) M for the alpha 2 leads to 6 linkage in II6NeuAc-Lac, and 2.1 x 10(-3) M for the alpha 2 leads to 8 linkage of II3 (comes from 2 alpha NeuAc8)2-Lac, respectively. Among the different groups of naturally occurring NeuAc-containing substrates, i.e. oligosaccharides, glycolipids and glycoproteins, the enzyme exhibits its highest activity towards low molecular weight oligosaccharides. Activity is considerably lower on glycoproteins. Glycolipids (gangliosides) are only little attacked under conditions used in the test. However, there is no remarkable specificity towards one of the different linkage types of N-acetylneuraminic acid. In general, the enzyme reveals a specificity pattern similar to that found in other bacteria of low pathogenicity towards man.

Acne Vulgaris↗
PubMed1979

Uptake and distribution of orally applied N-acetyl-(14C)neuraminosyl-lactose and N-acetyl-(14C)neuraminic acid in the organs of newborn rats.

N-acetyl-(14C)neuraminosyl-(alpha,2 leads to 3)lactose enzymatically prepared of CMP-NeuNAc and lactose by a particulate enzyme fraction from lactating rat mammary gland was applied orally to newborn rats and examined for uptake and distribution in relation to those of free N-acetyl-(14C)neuraminic acid. The neonates were allowed to stay with their mother before and during the incubation time up to 6 h. Within this time 70% of the given dose was excreted while 30% was retained in the body. (14C)NeuNAc-lactose activity appeared 1.5 h after application in blood, urine, and tissues and attained maximum values after 3 and 6 h, respectively. The highest uptake occurred in liver, spleen, and brain. The absorption of the trisaccharide was delayed by 30 min compared with free (14C)NeuNAc. The time courses of the curves show a slower but higher accumulation in the tissues suggesting a better utilization of the (14C)NeuNAc from (14C)NeuNAc-lactose or pecularities in the absorption of the trisaccharide by the organs.

Administration, Oral↗
PubMed1979

Properties and substrate specificities of two neuraminidases from Trichomonas fetus.

Trichomonas fetus, a protozoon belonging to the class of flagellates causes vaginal infections in cows, leading to sterility or abortion in early stage of pregnancy. Two neuraminidases were isolated from the culture medium and purified by various procedures of gel chromatography, ion exchange chromatography, and by affinity chromatography on N-(4-nitrophenyl)-oxamic acid-Sepharose 4B. The molecular weights of the two neuraminidases were determined as 320 000 (enzyme I) and 38 000 (enzyme II) respectively. However, enzyme I seems to consist of two isoenzymes containing four subunits of almost equal molecular weight. The pH optima of both enzymes depend on the substrates and range from pH 4.7 to 5.5. Due to the type of substrate, the Michaelis constants (Km) vary between 5.0 x 10(-2)M and 6.6 x 10(-3)M for enzyme I and between 1.4 x 10(-2)M and 4.9 x 10(-3)M for enzyme II. Among the different groups of NeuAc-containing substrates, i.e. glycoproteins, glycolipids, oligosaccharides and synthetic ketosides, enzyme I preferably cleaves high molecular weight glycoprotein type substrates whereas enzyme II shows higher affinities to low-molecular weight oligosaccharides. The ganglioside II3NeuAcGgOse4Cer is susceptible to both enzymes only after removal of the lipophilic ceramide residue. Both enzymes show differences in the specificity towards alpha 2 leads 3 to 3, alpha 2 leads to 6, and alpha 2 leads to 8 glycosidic linkages of NeuAc. Taking the rate of cleavage of the alpha 2 leads to linkage in II3NeuAc-Lac as 100, enzyme I reveals 65 for the alpha 2 leads to 6 linkage in II6NeuAc-Lac, and 15 for the alpha 2 leads to 8 linkage in II3(comes from 2 alpha NeuAc8)2-Lac, whereas enzyme II exhibits values around 50 for both the alpha 2 leads to 6- and the alpha 2 leads to 8-linked substrates. The activity of neuraminidase I and II is not influenced by Ca2 but is inhibited by Cu2, Hg2, ann 4-hydroxymercurisulfonic acid. The inhibition by Hg2 and by the latter is reversible with enzyme I by addition of dithioerythritol.

Animals↗
PubMed1976

Alteration of plasma lipids and intermediates of lipid metabolism in healthy fasting volunteers by ethanol and fructose.

After healthy persons, aged between 20 and 35 years, had consumed either ethanol or ethanol and fructose, triglycerides, free glycerol, FFA, phospholipids and total cholesterol were determined. After a basic dosage of 0.5 g ethanol/kg body weight, each person received a maeintenance dosage of 0.1 g ethanol/kg body weight and hour. Control experiments were carried out on persons receiving only fructose and on fasting persons who consumed no ethanol. After 8 hrs, triglycerides rose in the ethanol group by 107 %, in the ethanol-fructose group by 63 %. FFA exhibited in both ethanol and ethanol-fructose groups an initial decrease, with a secondary increase in the ethanol group. The initial decrease was greater in the ethanol-fructose group. A significant rise in free glycerol by 419 % was observed 30 min after the intake of combined ethanol/fructose. Free glycerol rose under ethanol alone by 144%. The ohospholipids exhibited a slight rise in the ethanol group; no significant changes occured in the cholesterol. The blood ethanol level was lower under ethanol-fructose than under ethanol alone. The addition of fructose diminishes the ethanol-induced hypertriglyceridemia. Our investigations give further proof that, under short-term ethanol load, the fatty acids necessary for the increased triglyceride synthesis in the liver, originate predominantly from a peripheral lipolysis, and that changes in liver metabolism depending on the oxidation of ethanol are not of less importance for the development of the acute ethanol-induced hyperlipidemia.

Adult↗
PubMed1976

[Metabolism of essential and endogenous serum fatty acids in healthy persons, coronary disease and patients with lipid metabolism disorder. Partial aspect of high risk problem patients with age-related lipid and fatty acid concentrations in serum and regulation of long-chain products from essential and endogenous precursors in healthy subjects].

Total lipid, free and esterified cholesterol and triglycerides significantly increase in concentration with increasing age. Palmitic, palmitoleic, oleic and linoleic acid behave in the same way. Free fatty acids, phospholipids and stearic acid show the same concentrations in all groups of age. C20 fatty acids demonstrate a competitive regulatory mechanism of desaturase activity in their age dependant distribution. While the 20:3(n-9), a product of the endogenous (n-9) family, increases, the 20:3(n-6) and 20:4(n-6), both desaturation and chain elongation products of the essential n-6 family, decrease. Such behavior has been demonstrated in many feeding studies (12, 13, 15, 16, 17, 29) and is interpreted as a result of competitive substrate interaction on desaturase activity.

8,11,14-Eicosatrienoic Acid↗
PubMed1975

Lipid metabolism of developing central nervous tissues in organotypic cultures. I. Lipid distribution and fatty acid profiles of the medium for rat brain cortex in vitro.

The distribution and concentration of lipid components of different media used for organotypic cultures of rat brain cortex have been measured quantitatively. Five cholesterol ester species have been fractionated from chicken embryonic extract. Their fatty acid profiles have been determined by combined gas liquid chromatography-mass spectrometry. The depletion characteristics of medium cholesterol esters and some fatty acids during development of brain cortex were not symmetrical. Polyunsaturated fatty acids of the medium were lowered prior to the saturated and monoenoic fatty acids. The phenomenon of depletion may be correlated with enhanced esterase activity mediated by the tissue.

Animals↗
PubMed1975

Lipid metabolism of developing central nervous tissues in organotypic cultures. II. A comparative study of medium and tissue fatty acids in developing rat cerebral cortex and cerebellum.

Organotypic cultures of rat cerebral cortex and cerebellum have been supplemented with different media. Fatty acid analysis in incubated media and in tissue explants revealed a characteristic differentiation of three periods during maturation: a posttraumatic repair phase, a synaptogenic period and a synaptic stage. Medium fatty acids are biphysically depleted from the nutrient. Both tissues differ in the depletion pattern of individual fatty acids. The development of tissue fatty acids is mainly observed during the synaptogenic period. Turnover studies of individual fatty acids indicate a tissue-specific and time-dependent characteristic.

Animals↗