Effect of triiodothyronine augmentation on rat lung surfactant phospholipids during sepsis.

Surfactant functional effectiveness is dependent on phospholipid compositional integrity; sepsis decreases this through an undefined mechanism. Sepsis-induced hypothyroidism is commensurate and may be related. This study examines the effect of 3,3',5-triiodo-L-thyronine (T3) supplementation on surfactant composition and function during sepsis. Male Sprague-Dawley rats underwent sham laparotomy (Sham) or cecal ligation and puncture (CLP) with or without T3 supplementation [CLP/T3 (3 ng/h)]. After 6, 12, or 24 h, surfactant was obtained by lavage. Function was assessed by a pulsating bubble surfactometer and in vivo compliance studies. Sepsis produced a decrease in surfactant phosphatidylglycerol and phosphatidic acid, with an increase in lesser surface-active lipids phosphatidylserine and phosphatidylinositol. Phosphatidylcholine content was not significantly changed. Sepsis caused an alteration in the fatty acid composition and an increase in saturation in most phospholipids. Hormonal replacement attenuated these changes. Lung compliance and surfactant adsorption were reduced by sepsis and maintained by T3 treatment. Thyroid hormone may have an active role in lung functional preservation through maintenance of surfactant homeostasis during sepsis.

Triiodothyronine (T3) supplementation maintains surfactant biochemical integrity during sepsis.

Surfactant functional effectiveness is dependent on phospholipid compositional integrity: sepsis decreases this through an undefined mechanism. Sepsis-induced hypothyroidism is commensurate and may be related. This study examines the effect of triiodothyronine (T3) supplementation on surfactant function, metabolism, and composition during sepsis. Male Sprague-Dawley rats (n = 75) underwent sham laparotomy or cecal ligation and puncture (CLP) with or without T3 supplementation (CLP/T3; 3 ng/hr). Twenty-four hours later, surfactant was obtained by lavage. Total phospholipids were determined by chromatography. Choline phosphate cytidyltransferase (CT) activity was determined by the formation of cytidine diphosphate (CDP)-choline. In vivo lung compliance was determined by lung inflation; surfactant hysteresis plots were determined on a pulsating bubble surfactometer. Lung compliance and surfactant hysteresis plots were significantly affected by sepsis; T3 modulated this (dynamic compliance: sham = 0.66 +/- 0.02, CLP = 0.47 +/- 0.06, CLP/T3 = 0.56 +/- 0.02 mm Hg/mL; p < 0.05). Sepsis produced a decrease in phosphatidylglycerol, and phosphatidic acid, with an increase in lesser surface active lipids phosphatidylserine and phosphatidylinositol. Hormonal replacement prevented these alterations. Lung CT activity was increased by sepsis independent of T3 treatment. Thyroid hormone may have an active role in lung functional preservation during sepsis caused by maintenance of surfactant biophysical and compositional homeostasis.

Protein-lipid interactions of the proteolipid c subunit of the Escherichia coli proton-translocating adenosinetriphosphatase.

Interactions between Escherichia coli membrane phospholipids and the hydrophobic c subunit of the F1F0 proton-translocating ATPase were characterized. Extraction of E. coli membranes with a neutral mixture of chloroform and methanol and subsequent separation steps produced several protein-containing fractions. The protein-containing fraction most soluble in organic solvents contained subunit c and a lipid fraction enriched in phosphatidylglycerol compared to total E. coli membrane phospholipids. Other ATPase subunits and some additional proteins extracted from the membranes by this procedure could be separated from the c subunit by subsequent extraction. The purified and delipidated c subunit contained fatty acids which were released upon treatment with boron trifluoride methanol. Furthermore, deleting and restoring the genes for the F0 subunits changed the composition of extractable membrane phospholipid and fatty acids, indicating that the F0 plays a significant structural role in the membrane.

[The mechanism of in vivo arylamine acetyltransferase activation]. / Mekhanizm aktivatsii in vivo arilamin-atsetiltransferazy.

A kinetic analysis of arylamine acetyltransferase activation by prodigiozane, a stimulator of organism unspecific resistance, has been carried out. The change of enzyme activity is associated not with a change of its tissue content, but is due to the appearance of a new isoenzyme with altered rate of product dissociation from the catalytic site under condition when k-1 much greater than kKaT. The effect observed is suggested to be defined by a genetically determined adaptative mobility of organism rather than by genetically determined enzyme synthesis. A search strategy for arylamine acetyltransferase activity regulators is proposed.

[The nature of peptides firmly associated with the protein part of membrane lipoproteins in chloroplast biogenesis]. / O prirode peptidov, prochno assotsiirovannykh a belkovoi chast'iu lipoproteidov membran pri biogeneze khloroplastov.

The biosynthesis of membrane lipoproteins in maize plastids at different stages of differentiation of the chloroplast lamellar system was studied. Prolamellar and lamellar system preparations were isolated from maize plastids and been or kidney bean chloroplasts, disintegrated by osmotic shock. Chloroplast lipoproteins are membraneous proteins of chloroplast lamellar systems. Peptids, lipids and carbohydrates "firmly" associated with the protein part of membrane lipoproteins were found at all stages of chloroplast ultrastructure formation. Incorporation of C14 amino acid increased with the time of incubation in "firmly" lipoprotein--bound peptids and in the polypeptid part of lipoproteins. Puromycin but not actidion D inhibited amino acid incorporation into the peptids and polypeptids of chloroplasts in vitro experiments. The maximal level of C14-peptids "firmly" associated with the protein part of membrane lipoproteins was observed in the membrane fraction of proplastids in vivo. It is pointed out that biogenesis process leads to the decrease of content of "firmly" lipoprotein--bound peptids in the chloroplast lamellae fraction.