Enzymic and nonenzymic systems protecting photoreceptor membranes against active forms of oxygen and lipid peroxides

A vertebrate disk membrane is composed of 40 % lipids and 60 % proteins. Its fracture faces have been classed into the plasmic (PF) and exoplasmic faces (EF), complementary with each other, like those of most other types of cell membranes. The hypothesis assuming the PF particles as representing membrane-associated proteins has been challenged by serious questions if they in fact emerge from the crystalline formation or decoration effects during freezing and shadowing processes. This problem seems to be yet unanswered, despite the remarkable case of the purple membrane of Halobacterium, partly because most observations have been made on the replicas from a single face of specimen, and partly because, in the case of photoreceptor membranes, the conformation of a rhodopsin and its relatives remains yet uncertain. The former defect seems to be partially fulfilled with complementary replica methods.

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Effects of Vitamin E Administration on Platelet Function and Serum Lipid Peroxides in DOCA-Salt Hypertensive Rats

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648162 ◽

1991 ◽

Vol 65 (04) ◽

pp. 411-414 ◽

Cited By ~ 2

Author(s):

Keizo Umegaki ◽

Hiromi Saegusa ◽

Masato Kurokawa ◽

Tomio Ichikawa

Keyword(s):

Vitamin E ◽

Platelet Function ◽

Serum Lipid ◽

Lipid Peroxide ◽

Lipid Peroxides ◽

Hypertensive Rats ◽

Serotonin Content ◽

Serum Lipid Peroxide ◽

Salt Hypertension

SummaryEffects of vitamin E on platelet function and serum lipid peroxide levels were investigated in DOCA-salt hypertensive rats. In the hypertensive rats, ADP- and collagen-induced platelet aggregation in whole blood were markedly attenuated and accompanied by a reduction of serotonin content as compared with the normotensive controls. These facts indicated the appearance of exhausted platelets, which have already been activated in vivo, due to the hypertension. Platelet vitamin E levels were decreased by 50%, while serum lipid peroxide levels were increased 3.6-fold in the hypertensive rats. Vitamin E administration (10 times the dietary intake) during the experimental periods did not influence either the aggregability or the serotonin content of platelets from the hypertensive rats. However, vitamin E administration significantly prevented the elevation of serum tipid peroxides due to the hypertension. These results suggest that vitamin E administration has little effect on platelet activation in vivo due to DOCA-salt hypertension.

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Adverse Influence of Cigarette Smoking on the Endothelium

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649654 ◽

1993 ◽

Vol 70 (04) ◽

pp. 707-711 ◽

Cited By ~ 77

Author(s):

Andrew D Blann ◽

Charles N McCollum

Keyword(s):

Endothelial Cells ◽

Von Willebrand Factor ◽

Tobacco Smoke ◽

Lipid Peroxides ◽

Short Exposure ◽

Acute Effects ◽

Adverse Influence ◽

Von Willebrand ◽

Willebrand Factor

SummaryThe effect of smoking on the blood vessel intima was examined by comparing indices of endothelial activity in serum from smokers with that from non-smokers. Serum from smokers contained higher levels of von Willebrand factor (p <0.01), the smoking markers cotinine (p <0.02) and thiocyanate (p <0.01), and was more cytotoxic to endothelial cells in vitro (p <0.02) than serum from non-smokers. The acute effects of smoking two unfiltered medium tar cigarettes was to briefly increase von Willebrand factor (p <0.001) and cytotoxicity of serum to endothelial cells in vitro (p <0.005), but lipid peroxides or thiocyanate were not increased by this short exposure to tobacco smoke. Although there were correlations between von Willebrand factor and smokers consumption of cigarettes (r = 0.28, p <0.02), number of years smoking (r = 0.41, p <0.001) and cotinine (r = 0.45, p <0.01), the tissue culture of endothelial cells with physiological levels of thiocyanate or nicotine suggested that these two smoking markers were not cytotoxic. They are therefore unlikely to be directly responsible for increased von Willebrand factor in the serum of smokers. We suggest that smoking exerts a deleterious influence on the endothelium and that the mechanism is complex.

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The influence of oxidized technical carbon N121 on the properties of butyl-based rubbers

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2018-95-3-123-128 ◽

2019 ◽

pp. 123-128

Author(s):

M. N. Nagornaya ◽

A. V. Myshliavtsev ◽

S. Ya. Khodakova

Keyword(s):

Hydrogen Peroxide ◽

Carbon Black ◽

Gas Permeability ◽

Mechanical Tests ◽

Butyl Rubber ◽

Rubber Mixture ◽

Active Forms Of Oxygen ◽

Technical Carbon ◽

Furnace Black ◽

The Subject

The subject of the study were samples of channel technical carbon K354, furnace technical carbon N121 and experimental – based on TUN121, oxidized with active forms of oxygen. Samples of carbon black were studied in the composition of a rubber mixture based on BK 1675N butyl rubber. The purpose of this study was to determine the possibility of using oxidized technical carbon N121 in fillers of rubber based on butyl rubber, instead of carbon black K354. The physicochemical properties of the samples of technical carbon under study, the results of physical and mechanical tests, and the gas permeability tests of rubber mixtures filled with the samples under study are presented. A conclusion is made about the possibility of replacing channel technical carbon K354 with furnace black carbon N121 oxidized with 30% hydrogen peroxide.

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