Allyl-containing sulfides in garlic increase uncoupling protein content in brown adipose tissue, and noradrenaline and adrenaline secretion in rats.
The effects of garlic supplementation on triglyceride metabolism were investigated by measurements of the degree of thermogenesis in interscapular brown adipose tissue (IBAT), and noradrenaline and adrenaline secretion in rats fed two types of dietary fat. In Experiment 1, rats were given isoenergetic high-fat diets containing either shortening or lard with or without garlic powder supplementation (8 g/kg of diet). After 28 d feeding, body weight, plasma triglyceride levels and the weights of perirenal adipose tissue and epididymal fat pad were significantly lower in rats fed diets supplemented with garlic powder than in those fed diets without garlic powder. The content of mitochondrial protein and uncoupling protein (UCP) in IBAT, and urinary noradrenaline and adrenaline excretion were significantly greater in rats fed a lard diet with garlic powder than in those fed the same diet without garlic. Other than adrenaline secretion, differences due to garlic were significant in rats fed shortening, also. In Experiment 2, the effects of various allyl-containing sulfides present in garlic on noradrenaline and adrenaline secretion were evaluated. Administration of diallyldisulfide, diallyltrisulfide and alliin, organosulfur compounds present in garlic, significantly increased plasma noradrenaline and adrenaline concentrations, whereas the administration of disulfides without allyl residues, diallylmonosulfide and S-allyl-L-cysteine did not increase adrenaline secretion. These results suggest that in rats, allyl-containing sulfides in garlic enhance thermogenesis by increasing UCP content in IBAT, and noradrenaline and adrenaline secretion. (+info)
Nitrate removal in closed-system aquaculture by columnar denitrification.
The columnar denitrification method of nitrate-nitrogen removal from high-density, closed system, salmonid aquaculture was investigated and found to be feasible. However, adequate chemical monitoring was found to be necessary for the optimization and quality control of this method. When methanol-carbon was not balanced with inlet nitrate-nitrogen, the column effluent became unsatisfactory for closed-system fish culture due to the presence of excess amounts of nitrite, ammonia, sulfide, and dissolved organic carbon. Sulfide production was also influenced by column maturity and residence time. Methane-carbon was found to be unsatisfactory as an exogenous carbon source. Endogenous carbon could not support high removal efficiencies. Freshwater columns adpated readily to an artificial seawater with a salinity of 18% without observable inhibition. Scanning electron microscopy revealed that the bacterial flora was mainly rod forms with the Peritricha (protozoa) dominating as the primary consumers. Denitrifying bacteria isolated from freshwater columns were tentatively identified as species of Pseudomonas and Alcaligenes. A pilot plant column was found to behave in a manner similar to the laboratory columns except that nitrite production was never observed. (+info)
Dense populations of a giant sulfur bacterium in Namibian shelf sediments.
A previously unknown giant sulfur bacterium is abundant in sediments underlying the oxygen minimum zone of the Benguela Current upwelling system. The bacterium has a spherical cell that exceeds by up to 100-fold the biovolume of the largest known prokaryotes. On the basis of 16S ribosomal DNA sequence data, these bacteria are closely related to the marine filamentous sulfur bacteria Thioploca, abundant in the upwelling area off Chile and Peru. Similar to Thioploca, the giant bacteria oxidize sulfide with nitrate that is accumulated to +info)
Tetradecylthioacetic acid (a 3-thia fatty acid) impairs secretion of oleic acid-induced triacylglycerol-rich lipoproteins in CaCo-2 cells.
The fatty acid analogue tetradecylthioacetic acid (TTA) has previously been shown to decrease triacylglycerol secretion in CaCo-2 cells (Gedde-Dahl et al., J. Lipid Res. 36 (1995) 535-543). The present study was designed to further elucidate the effect of TTA on lipoprotein production in CaCo-2 cells. TTA did not affect oleic acid-induced triacylglycerol synthesis, but it significantly decreased secretion of newly synthesized triacylglycerol when compared to cells incubated with oleic acid alone or oleic acid in combination with palmitic acid. In contrast, pulse-chase experiments showed no difference in the amount of labeled triacylglycerol secreted from cells exposed to either fatty acid combination during the chase period, indicating that TTA did not affect the secretory process in general. Cells incubated with TTA alone secreted triacylglycerol present at 1.025+info)
Thiolated recombinant human tumor necrosis factor-alpha protects against Plasmodium berghei K173-induced experimental cerebral malaria in mice.
The introduction of reactive thiol groups in recombinant human tumor necrosis factor (TNF) alpha (rhTNF-alpha) by the reagent succinimidyl-S-acetylthioacetate resulted in the formation of a chemically stabilized rhTNF-alpha trimer (rhTNFalpha-AT; as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis). rhTNFalpha-AT showed a substantially enhanced protective efficacy against the development of experimental murine cerebral malaria (ECM) after intravenous injection compared to the protective efficacy of nonmodified rhTNF-alpha. Administration of thiolated rhTNF-alpha with protected thiol groups (rhTNFalpha-ATA; no stabilized trimers in vitro) exhibited the same protective efficacy against ECM, while in vitro bioactivity was reduced. Parasitemia was significantly suppressed in rhTNF-treated mice that were protected against ECM but not in treated mice that developed ECM. Protection against ECM was not related to increased concentrations in plasma of soluble TNF receptor 1 and 2 directly after injection or at the moment of development of ECM in nontreated mice. The results indicate that thiolation of rhTNF-alpha leads to the formation of stable trimers with increased potential in vivo. (+info)
A fission yeast gene for mitochondrial sulfide oxidation.
A cadmium-hypersensitive mutant of the fission yeast Schizosaccharomyces pombe was found to accumulate abnormally high levels of sulfide. The gene required for normal regulation of sulfide levels, hmt2(+), was cloned by complementation of the cadmium-hypersensitive phenotype of the mutant. Cell fractionation and immunocytochemistry indicated that HMT2 protein is localized to mitochondria. Sequence analysis revealed homology between HMT2 and sulfide dehydrogenases from photosynthetic bacteria. HMT2 protein, produced in and purified from Escherichia coli, was soluble, bound FAD, and catalyzed the reduction of quinone (coenzyme Q2) by sulfide. HMT2 activity was also detected in isolated fission yeast mitochondria. We propose that HMT2 functions as a sulfide:quinone oxidoreductase. Homologous enzymes may be widespread in higher organisms, as sulfide-oxidizing activities have been described previously in animal mitochondria, and genes of unknown function, but with similarity to hmt2(+), are present in the genomes of flies, worms, rats, mice, and humans. (+info)
Health aspects of the curing of synthetic rubbers.
A commonly used tread rubber formulation was cured in the laboratory under conditions simulating vulcanization in the Bag-O-Matic press. Volatile emissions were collected on charcoal and analyzed by combined GC-mass spectrometry. The compounds identified were either contaminants present in the raw material or reaction products. Some of these compounds were also identified in charcoal tube samples collected in the atmosphere of the industrial operations. Estimates based on the loss of weight of rubber during curing were used to predict airborne concentrations and compared to the concentrations actually found. The literature of the toxicity of raw materials and effluents was reviewed, and no acute or chronic toxicological effects would be anticipated. Information concerning potential carcinogenicity was not available and could not be evaluated. (+info)
Novel derivatives of phenethyl-5-bromopyridylthiourea and dihydroalkoxybenzyloxopyrimidine are dual-function spermicides with potent anti-human immunodeficiency virus activity.
Sexually active women represent the fastest growing HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) risk group. In an effort to develop a vaginal microbicidal contraceptive potentially capable of preventing HIV transmission as well as providing fertility control, we have synthesized novel non-nucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) and examined them for dual-function anti-HIV and spermicidal activity. Structure-based drug design by use of a computer docking procedure for the NNI binding pocket generated from nine RT-NNI crystal structures led to the synthesis of three novel NNIs: N-[2-(2, 5-dimethoxyphenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (D-PBT); N-[2-(2-fluorophenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (F-PBT); and 5-isopropyl-2-[(methylthiomethyl)thio]-6-(benzyl)-pyrimidin-4-(1H)-on e (S-DABO). The anti-HIV activity of these NNIs was compared with that of trovirdine and virucidal/spermicide, nonoxynol-9 (N-9), by measuring viral RT activity and p24 antigen production as markers of viral replication using HTLVIIIB-infected human peripheral blood mononuclear cells (PBMCs). The effects on sperm motion kinematics and sperm membrane integrity were examined by computer-assisted sperm analysis and by confocal laser scanning microscopy (CLSM), respectively. The growth-inhibitory effects of NNI versus N-9 against normal human ectocervical and endocervical epithelial cells were tested using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. All three NNIs were potent inhibitors of purified recombinant HIV RT and abrogated HIV replication in PBMCs at nanomolar concentrations (IC50 < 1 nM) when compared with N-9 or trovirdine (IC50 values of 2.2 microM and 0.007 microM, respectively). Two NNIs, F-PBT and S-DABO, also exhibited concentration- and time-dependent spermicidal activity. The drug concentration required to inhibit sperm motility by 50% (EC50 values) for the lead compound F-PBT versus N-9 was 147 microM and 81 microM, respectively. Sperm-immobilizing activity induced by F-PBT and S-DABO was rapid (t1/2 = 7-13 min) and irreversible. Unlike that of N-9, spermicidal activity of F-PBT and S-DABO was not accompanied by loss of acrosomal membrane as detected by fluorescent-lectin binding assay and CLSM. Whereas N-9 was cytotoxic to normal human ectocervical and endocervical cells at spermicidal doses, both F-PBT and S-DABO were selectively spermicidal. We conclude that as potent anti-HIV agents with spermicidal activity and reduced cytotoxicity, F-PBT and S-DABO show unique clinical potential to become the active ingredients of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission. (+info)