The mechanism of the hypolipidemic effect of garlic oil extract in rats fed on high sucrose and alcohol diets

The effect of feeding garlic oil to white albino rats maintained on high sucrose and alcohol diets was studied. It is proposed that the mechanism of the hypolipidemic effect of the oil involves the active principle, diallyl disulphide, inactivating enzymes and substrates containing thiol groups in an exchange reaction; increased hydrolysis of triacylglycerols as increased lipase activity is induced by the oil; and the reduction in the biosynthesis of triacylglycerols as NADPH is made unavailable for the process by the metabolism of the oil.     

Human skin chymotrypsin-like proteinase chymase. Subcellular localization to mast cell granules and interaction with heparin and other glycosaminoglycans

The subcellular localization of human skin chymase to mast cell granules was established by immunoelectron microscopy, and binding of chymase to the area of the dermo-epidermal junction, a basement membrane, was demonstrated immunocytochemically in cryosections incubated with purified proteinase prior to immunolabeling. Because heparin and heparan sulfate proteoglycans are major constituents of mast cell granules and basement membranes, respectively, the ability of chymase to bind to glycosaminoglycans (GAG) was investigated. Among a variety of GAGs, only binding of chymase to heparin and heparan sulfate appears physiologically significant. Binding was ionic strength-dependent, involved amino groups on the proteinase, and correlated with increasing GAG sulfate content, indicating a predominantly electrostatic association. Interaction with heparin was observed in solutions containing up to 0.5 M NaCl, and interaction with heparan sulfate was observed in solutions containing up to 0.3 M NaCl. Binding of heparin did not detectably affect catalysis of peptide substrates, but may reduce accessibility of proteinase to protein substrates. Measurements among a series of serine class proteinases indicated that heparin binding was a more common property of mast cell proteinases than proteinases stored in other secretory granules. Binding of chymase to heparin is likely to have a storage as well as a structural role within the mast cell granule, whereas binding of chymase to heparan sulfate may have physiological significance after degranulation.     

Parathyroid hormone stimulates adenylate cyclase in rat cerebral microvessels

We have studied the effect of parathyroid hormone (PTH) on adenylate cyclase of microvessels isolated from rat cerebral cortex. Native bovine (b) PTH-(1–84), the synthetic amino-terminal fragment bPTH-(1–34) and the synthetic analog [Nle⁸, Nle¹⁸, Tyr³⁴]-bPTH- (1–34) amide stimulated adenylate cyclase in a dose-dependent manner with apparent ED₅₀ values of 16 nM, 6.3 nM and 15 nM respectively. The stimulation by bPTH was greatly enhanced by guanosine triphosphate. The PTH antagonist, [Nle⁸, Nle¹⁸, Tyr³⁴]-bPTH-(3–34) amide inhibited the action of bPTH-(1–84) and bPTH-(1–34). In summary, PTH stimulated adenylate cyclase in rat cerebral microvessels in a very similar manner to its stimulation in the renal cortex.     

Changes of beta-endorphin and somatostatin concentrations in different hypothalamic areas of female rats after chronic starvation

To study the effect of starvation on hypothalamic beta-endorphin and somatostatin (SRIF) concentrations in relation to starvation induced anestrus, groups of 8 rats were fed 50% of their normal daily chow consumption. Rats were sacrificed after 4, 8, 12, and 16 days during diestrus or anestrus. beta-endorphin concentrations decreased in the preoptic suprachiasmatic area (0.52 +/- 0.13 vs 0.21 +/- 0.05 ng/mg tissue wet weight) and increased in the posterior hypothalamus (0.31 +/- 0.06 vs 0.57 +/- 0.11 ng/mg) after 4 days of starvation. No significant change occurred in the arcuate nucleus or in the median eminence. On day 8 and 12 of starvation, beta-endorphin was unaltered in all areas compared to controls. Vaginal smears showed constant diestrus in a significant number of rats (5 out of 8) after 12 days. beta-endorphin concentrations in the arcuate nuclei of these rats were significantly reduced on day 16 (1.00 +/- 0.33 vs 0.30 +/- 0.11 ng/mg). The SRIF levels changed only in the median eminence with increased concentrations on day 12 (45.2 +/- 8.4 vs 79.5 +/- 14.8 ng/mg). At this time serum levels of luteinizing hormone (LH), prolactin (PRL), and growth hormone (GH) were significantly reduced. The results indicate that changes in hypothalamic beta-endorphin accompany the events leading to starvation induced anestrus.     

Effects of Autogamy In Paramecium Tetraurelia On Catalase Activity and On Radiosensitivity to Natural Ionizing Radiations

SYNOPSIS Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity to natural ionizing radiations—the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. the role of the catalase in the mechanism of natural irradiation effect is discussed.     

Biological and structural properties of MIP-1 alpha expressed in yeast.

The murine macrophage inflammatory proteins-1 alpha (MIP-1 alpha) and MIP-1 beta are distinct but closely related cytokines. Partially purified mixtures of the two proteins affect neutrophil function and cause local inflammation and fever. The particular properties of MIP-1 alpha have not been well studied, although it has been identified as being identical to an inhibitor of haemopoietic stem cell growth. We have expressed MIP-1 alpha in yeast cells and purified it to sequence homogeneity. Structural analysis of this biologically active material by circular dichroism and fluorescence spectroscopy confirms that MIP-1 alpha has a very similar secondary and tertiary structure to platelet factor 4 and interleukin 8 with which it shares limited sequence homology. The in-vitro stem cell inhibitory properties have been confirmed using a range of murine progenitor cells including purified bone marrow progenitor cells (FACS-1), the FDCP-mix A4 cell line, and spleen colony forming unit (CFU-S) populations. Plateau levels of inhibition of stem cell growth were achieved using concentrations of 0.15 micrograms/ml MIP-1 alpha. We have also demonstrated that MIP-1 alpha is active in vivo: 5 micrograms of MIP-1 alpha per mouse given as a bolus injection, protects stem cells from subsequent in-vitro killing by tritiated thymidine. MIP-1 alpha was also shown to enhance the proliferation of more committed progenitor granulocyte macrophage-colony forming cells (GM-CFC) in response to granulocyte macrophage-colony stimulating factor (GM-CSF).