Inhibition of the development of adjuvant arthritis in rats as affected by vitamin E

The experiments on rats have shown that preliminary oral administration of vitamin E significantly suppressed generalization, but not development of adjuvant-induced arthritis. Oral vitamin E administration beginning one day after the onset of arthritis inhibited the development and generalization of the disease. Vitamin E had no effect on serum lysosomal enzyme activity, but markedly depressed lipid peroxidation.     

Serum vitamin A and vitamin E concentrations after parenteral vitamin A administration in sheep

Twenty primiparous dairy sheep of the Mytilene breed, which were fed with a ration deficient in vitamin A and carotenes, were divided into 2 groups of 10 animals each after a 2-month adaptation period. The animals of group A were administered vitamin A palmitate by intramuscular injection (3500 IU/kg bodyweight), while the animals of group B were used as controls and received only the vehicle of the preparation without vitamin A. Serum vitamin A concentrations increased significantly in the animals of group A compared to the animals of group B (P < 0.01) from the first 24 h post-injection and remained significantly high for 8 days, and at 10 days post-injection they reached the pre-injection levels. The serum vitamin E concentration declined significantly (P < 0.05) in the animals of group A compared to the animals of group B for 8 days, when they reached the pre-injection levels. No changes in serum vitamins A and E levels in the animals of the 2 groups were observed 20 days after the injection of vitamin A.     

Serum lipoproteins as cholesterol donors to mycoplasma membranes.

Mycoplasma hominis andAcholeplasma laidlawii were grown in media in which a fraction of human serum lipoproteins provided the sole source of cholesterol. Increasing levels of very low density lipoproteins had an inhibitory effect on the growth of the organisms. Low and high density lipoproteins in all concentrations proved to be excellent sources of cholesterol. Both organisms were able to limit the amount of cholesterol taken up and to preferentially incorporate free cholesterol despite an excess of esterified cholesterol in the medium. When similar levels of free cholesterol were provided by low density or high density lipoproteins, the organisms incorporated from 20–45% more cholesterol from the former. This preference for cholesterol from low density lipoproteins partially supports the theory that the low density lipoproteins act as a donor while the high density lipoproteins are a scavenger of cholesterol.     

Serum amyloid A promotes cholesterol efflux mediated by scavenger receptor B-I

Serum amyloid A (SAA) is an acute phase protein whose expression is markedly up-regulated during inflammation and infection. The physiological function of SAA is unclear. In this study, we reported that SAA promotes cellular cholesterol efflux mediated by scavenger receptor B-I (SR-BI). In Chinese hamster ovary cells, SAA promoted cellular cholesterol efflux in an SR-BI-dependent manner, whereas apoA-I did not. Similarly, SAA, but not apoA-I, promoted cholesterol efflux from HepG2 cells in an SR-BI-dependent manner as shown by using the SR-BI inhibitor BLT-1. When SAA was overexpressed in HepG2 cells using adenovirus-mediated gene transfer, the endogenously expressed SAA promoted SR-BI-dependent efflux. To assess the effect of SAA on SR-BI-mediated efflux to high density lipoprotein (HDL), we compared normal HDL, acute phase HDL (AP-HDL, prepared from mice injected with lipopolysaccharide), and AdSAA-HDL (HDL prepared from mice overexpressing SAA). Both AP-HDL and AdSAA-HDL promoted 2-fold greater cholesterol efflux than normal HDL. Lipid-free SAA was shown to also stimulate ABCA1-dependent cholesterol efflux in fibroblasts, in line with an earlier report (Stonik, J. A., Remaley, A. T., Demosky, S. J., Neufeld, E. B., Bocharov, A., and Brewer, H. B. (2004) Biochem. Biophys. Res. Commun. 321, 936-941). When added to cells together, SAA and HDL exerted a synergistic effect in promoting ABCA1-dependent efflux, suggesting that SAA may remodel HDL in a manner that releases apoA-I or other efficient ABCA1 ligands from HDL. SAA also facilitated efflux by a process that was independent of SR-BI and ABCA1. We conclude that the acute phase protein SAA plays an important role in HDL cholesterol metabolism by promoting cellular cholesterol efflux through a number of different efflux pathways.     

Growth and bone mineralisation as affected by dietary calcium, phytic acid and vitamin D

1. Rats were fed various diets ranging from the normal chow, pure flour containing large amounts of phytic acid, Ca-enriched flour and mixtures of flour and normal food with various levels of calcium. 2. It was found that the animals eating the pure flour grew less and were smaller. 3. They suffered from hypocalcemia and had low plasma alkaline phosphatase and 25-HCC-vitamin D3 levels. 4. These animals had rib-cage deformities. 5. Additional calcium in the flour improved the animals' growth and calcification. 6. The mixed food did not greatly affect the animals and additional calcium did not improve growth or bone mineralisation. 7. The Bedouin eat large amounts of unleavened bread containing large amounts of phytates. 8. It is concluded that uptake of large amounts of phytates by the Bedouin eating unleavened bread is due to the flour and that the clinical manifestations are a direct result of the flour and not the lack of vitamin D due to covering the skin from sunlight.     

Langerhans cells in murine vaginal epithelium affected by oestrogen and topical vitamin A

Langerhans cells vary in their morphology and distribution in the vaginal epithelium of ovariectomized mice stimulated to hyperplasia and keratinization by oestrogen. When the stratum corneum was removed by topical vitamin A application, the shape and distribution of Langerhans cells were unaffected. It was concluded that Langerhans cell morphology and distribution depend on the configuration of the lower strata of the epithelium and not on the presence of a stratum corneum.     

Effect of vitamin E deficiency on the development of cardiac arrhythmias as affected by acute ischemia

Malonic dialdehyde content was increased by 53% in the myocardium of male Wistar rats (250-300 g) devoid of vitamin E for 2 months, as compared to the control rats (animals receiving an optimal amount of vitamin E). Transitory ischemia (10 min) with subsequent reoxygenation (5 min) was induced during open heart surgery under urethan anesthesia. Ischemia was induced by the occlusion of the descending branch of the left coronary artery. In ischemic rats with vitamin E deficiency the incidence of ventricular fibrillation, tachycardia, extrasystoles and the additive duration of arrhythmias were significantly increased as compared to the control.     

Serum albumin acts as a shuttle to enhance cholesterol efflux from cells

An important mechanism contributing to cell cholesterol efflux is aqueous transfer in which cholesterol diffuses from cells into the aqueous phase and becomes incorporated into an acceptor particle. Some compounds can enhance diffusion by acting as shuttles transferring cholesterol to cholesterol acceptors, which act as cholesterol sinks. We have examined whether particles in serum can enhance cholesterol efflux by acting as shuttles. This task was accomplished by incubating radiolabeled J774 cells with increasing concentrations of lipoprotein-depleted sera (LPDS) or components present in serum as shuttles and a constant amount of LDL, small unilamellar vesicles, or red blood cells (RBC) as sinks. Synergistic efflux was measured as the difference in fractional efflux in excess of that predicted by the addition of the individual efflux values of sink and shuttle alone. Synergistic efflux was obtained when LPDS was incubated with cells and LDL. When different components of LPDS were used as shuttles, albumin produced synergistic efflux, while apoA-I did not. A synergistic effect was also obtained when RBC was used as the sink and albumin as shuttle. The previously observed negative association of albumin with coronary artery disease might be linked to reduced cholesterol shuttling that would occur when serum albumin levels are low.     

Metabolism of vitamin A affected by prostaglandin F synthase in contractile interstitial cells of bovine lung

Contractile interstitial cells (CIC), the major component of the alveolar septum of the bovine lung are enriched in prostaglandin (PG) F synthase (Fukui, M., Fujimoto, T., Watanabe, K., Endo, K., and Kuno, K. (1996) J. Histochem. Cytochem. 44, 251-257.). The enzyme catalyzes not only the reduction of PGD(2) and PGH(2) but also that of various carbonyl compounds (Watanabe, K., Yoshida, R., Shimizu, T., and Hayaishi, O. (1985) J. Biol. Chem. 260, 7035-7041). Here, we report that retinal (vitamin A-aldehyde) was reduced to retinol (vitamin A-alcohol) dose- and time-dependently by PGF synthase using NADPH as a cofactor. The Km value of PGF synthase for retinal was about 20 microM, a same order to that for PGH(2). The conversion of retinal to retinol was also observed in cultured CIC, as demonstrated by the greenish fluorescence characteristic of retinol. Thus, retinal might be one of the natural substrates for PGF synthase in vivo, and retinol synthesized from retinal in CIC may play physiological and pathological roles in the lungs.     

Measurements of mitochondrial volumes are affected by the amount of mitochondria used in the determinations.

Mitochondrial water spaces were determined by centrifugal filtration, by using 3H2O and [14C]-sucrose, -mannitol, -inulin and -dextran. The volume (in microliter/mg of mitochondrial protein) of each of the spaces was inversely proportional to the amount of mitochondria (mg of protein) centrifuged. The dextran space (representing extramitochondrial water carried down with the mitochondria) decreased the most, and accounted for most of the changes observed in the other spaces. However, the calculated matrix and intermembrane spaces also decreased when increasing amounts of mitochondria were centrifuged. For each space, the same value was obtained when centrifugal filtration was done at 8000 and at 15,600 g, and when the mitochondria were incubated with the markers for 15 s to 5 min, indicating that sucrose, mannitol and inulin do not penetrate the matrix, nor does dextran penetrate the intermembrane space, under the incubation and centrifugation conditions generally used to measure mitochondrial spaces.