Combined Drug Treatment of Obesity

Pharmacological treatment of obesity has been neglected as a viable therapeutic option for many years. Recent long term studies with combinations of obesity drugs gives promise that drugs may play a role in weight maintenance, which classically has been the most difficult aspect of treating obesity. Currently available obesity drugs include centrally acting adrenergic agents and serotonin agonists. Drugs still in development include a lipase inhibitor that produces fat malabsorption, a combined adrenergic-serotonergic reuptake inhibitor, various gut-central nervous system peptides, and a number of beta-3 agonists. Any of these obesity drugs given alone produces modest weight loss, and for most, weight loss continues for as long as medication is given. The most successful drug regimens to date are combinations of phentermine and fenfluramine or of ephedrine, caffeine, and/or aspirin. The former combination produces reduction in body weight and complications of obesity for 2 to almost 4 years in clinical trials to date. More research is needed to document long term efficacy and particularly the long term safety of these and other combinations.     

Induction of paternal genome loss by the paternal-sex-ratio chromosome and cytoplasmic incompatibility bacteria (Wolbachia): A comparative study of early embryonic events

Paternal genome loss (PGL) during early embryogenesis is caused by two different genetic elements in the parasitoid wasp, Nasonia vitripennis. Paternal sex ratio (PSR) is a paternally inherited supernumerary chromosome that disrupts condensation of the paternal chromosomes by the first mitotic division of fertilized eggs. Bacteria belonging to the genus Wolbachia are present in Nasonia eggs and also disrupt paternal chromosome condensation in crosses between cytoplasmically incompatible strains. Cytoplasmic incompatibility Wolbachia are widespread in insects, whereas PSR is specific to this wasp. PGL results in production of male progeny in Nasonia due to haplodiploid sex determination. The cytological events associated with PGL induced by the PSR chromosome and by Wolbachia were compared by fluorescent light microscopy using the fluorochrome Hoescht 33258. Cytological examination of eggs fertilized with PSR-bearing sperm revealed that a dense paternal chromatin mass forms prior to the first metaphase. Quantification of chromatin by epifluorescence indicates that this mass does undergo replication along with the maternal chromatin prior to the first mitotic division but does not replicate during later mitotic cycles. Contrary to previous reports using other staining methods, the paternal chromatin mass remains condensed during interphase and persists over subsequent mitotic cycles, at least until formation of the syncytial blastoderm and cellularization, at which time it remains near the center of the egg with the yolk nuclei. Wolbachia-induced PGL shows several marked differences. Most notable is that the paternal chromatin mass is more diffuse and tends to be fragmented during the first mitotic division, with portions becoming associated with the daughter nuclei. Nuclei containing portions of the paternal chromatin mass appear to be delayed in subsequent mitotic divisions relative to nuclei free of paternal chromatin. Crosses combining incompatibility with PSR were cytologically similar to Wolbachia-induced PGL, although shearing of the paternal chromatin mass was reduced. Wolbachia may, therefore, block an earlier stage of paternal chromatin processing in the fertilized eggs than does PSR. © 1995 Wiley-Liss, Inc.     

The influence of polyalcohols and carbohydrates on the thermostability of alpha-amylase

The influence of polyhydric alcohols and carbohydrates on the thermostability, i.e., the heat inactivation kinetics, of Bacillus licheniformis alpha-amylase was studied in the temperature range 96 degrees to 130 degrees C. High concentrations (from 9 to 60 weight percent) of glycerol, sorbitol, mannitol, sucrose, or starch can markedly decrease the inactivation rate constant, k, and in the studied cases, this stabilizing effect grows stronger with increasing additive concentration. Statements about stabilization should, however, be specified carefully with respect to temperature, because E(A) is mostly altered likewise. For dissolved enzyme E(A) was almost always decreased in the presence of polyol or carbohydrate, whereas for immobilized enzyme it was augmented in each studied instance. The inactivation of dissolved enzyme can, in all the studied cases, be adequately described as a first-order process. Immobilized enzyme, however, shows biphasic then first-order inactivation kinetics, depending on the additive concentration and temperature.     

Temperature and chemical shocks induce chilling tolerance in germinating Cucumis sativus (cv. Poinsett 76) seeds

Roots of 24-h-old germinated cucumber ( Cucumis sativus cv. Poinsett 76) seeds were subjected to thermal and chemical stresses, equilibrated at 25°C for 2 h and chilled at 2.5°C for 96 h. The germinated seeds were then held at 25°C for 72 h after they were chilled and the elongation of the primary root was used as a measure of chilling tolerance. Control roots elongated from an initial length of 0.2 cm to a final length of 6.3 cm at the end of 72 h. while chilled roots elongated to a final length of only 0.4 to 0.6 cm. Exposure to 0.4 M ethanol for 4 h or to 40°C for 1 h induced substantial chilling tolerance and the roots had a final length of 4.1 and 3.1 cm. respectively. Exposure to 7.5°C for 3 h conferred less chilling tolerance (elongation to 1.4 cm). while exposure to other chemicals (i.e. aqueous solutions of Ca(NO₃)₂, mannitol. methanol and NaCl) produced less, though still significant increases in chilling tolerance. A more severe chilling treatment of 144 h at 2.5°C was required to consistently induce elevated rates of ion leakage. Only the heat and the ethanol shock treatments significantly reduced chilling-induced ion leakage. Inclusion of the protein synthesis inhibitor cycloheximide negated the protective effects of these shock treatments. It appears that de novo protein synthesis is required for induction of chilling tolerance by a variety of chemical and thermal shock treatments.     

Selection for higher yields and heat resistance in Pima cotton has caused genetically determined changes in stomatal conductances

Gas exchange analysis was used to characterize photosynthetic and stomatal responses to key environmental stimuli in five commercial lines of Pima cotton ( Gossypium barbadense L.) which represent a gradient of selection for higher yields and heat resistance, and a primitive, uncultivated G. barbadense. At constant light and vapor pressure deficit, stomatal conductance increased linearly with air temperature in the 23 to 36$C range in all five commercial lines, and conductance at each temperature increased as a function of selection. In contrast, photosynthetic rates had a low sensitivity to temperature in the 23 to 36$C range, particularly in the advanced lines. In a segregating F₂ population from a cross between the advanced line, Pima S-6, and the primitive cotton, B368, the slope of the stomatal response to temperature in each F₂ plant was positively correlated with the stomatal conductance measured at 40$C. An analysis of the frequency distribution of stomatal conductance in F₁ and F₂ progeny of the cross showed that the differences in stomatal conductance between lines were genetically determined. These data indicate that selection for higher yield and heat resistance in Pima cotton has caused genetically determined changes in stomatal properties. Characterization of the relationship between the altered stomatal properties and the attained increases in heat resistance and yields could make it possible to use these physiological traits as selection criteria in future breeding programs.     

Transpiration measurements on apple trees with an improved stem heat balance method

Since the late eighties a handy and user-friendly sap flow meter (Dynagage®) is on the market which can quantify 0205 the sap flow through intact plant stems, based on the stem heat balance method. The documentation about its accuracy and reliability, however, is still too limited to use it as a standard method in field experiments with apple trees. We therefore tested this commercial system on potted apple trees (Malus domestica L.; cv. Red Elstar and Jonagold; on rootstock M9 vf) with stem diameters of 1.8 to 4 cm. The measured sap flow was compared with mass loss measured by an automated balance, supposing the total mass loss of the trees was equal to the water loss by transpiration. The results revealed three major problems:

Inhibition of Bacillus spores by combinations of heat,potassium sorbate,NaCl and pH

Viability of spores of Bacillus cereus was totally inhibited at 85°C over 30 min by adding 0.4% (w/v) potassium sorbate with 6% (w/v) NaCl at pH 4.5. Viability of B. stearothermophilus spores was totally inhibited at 95°C for 45 min in a buffer at pH 4.2 containing 0.8% (w/v) potassium sorbate and 8% (w/v) NaCl. A synergistic inhibitory effect was demonstrated in some of the combinations. The inhibition may be due to interference with the heat-resistance apparatus of the spores.O.B. Oloyede was and J. Scholefield is with the Department of Bioscience & Biotechnology, Food Science Division, University of Strathclyde, Glasgow G1 1SD, UK. O.B. Oloyede is now with the Department of Biochemistry, University of Ilorin, Ilorin, Nigeria.     

大鼠心脏血压超负荷诱导左心室HSP70基因表达

本工作应用热休克蛋白７０（ＨＳＰ７０）核酸分子杂交方法,测定了大鼠腹主动脉缩窄后左心室ＨＳＰ７０ｍＲＮＡ的水平。结果表明：大鼠腹主动脉缩窄后４ｈ,动脉血压已明显升高,并持续在高水平上;大鼠左心室重／体重比在第三天开始增加,然后持续升高,第４周时比对照组增加５９％;左心室ＨＳＰ７０ｍＲＮＡ在腹主动脉缩窄后４ｈ已明显升高,１ｄ,２ｄ,１ｗ均维持在高水平,１ｗ后逐渐消失。实验结果提示：大鼠心肌负荷增加早期,左心室ＨＳＰ７０ｍＲＮＡ表达明显增加。