Effect of fructose on the hexosamine turnover in the rat crystalline lens

Rats were given isocaloric rations containing starch (control) and varying amounts of fructose as carbohydrates. Hexosamines were isolated from the lens, glycoproteins--from the blood serum, and their turnover was studied. A drastic deceleration of hexosamine turnover in the lens was observed at high-fructose diets (20 and 40% of fuel value), while glycoprotein turnover in the blood plasma was not changed as compared to the control, glucose-6-phosphate dehydrogenase in red blood cells was decreased, insulin level was lowered, and glucose level in the blood serum rose insignificantly. It has been suggested that fructose may be cataractogenic in animals.     

Mechanism for maintaining blood protein composition with various protein regimens

The study of the blood plasma protein content, turnover constant and half-life of albumin, fibrinogen and the total fraction of IgG + transferrin, was conducted in 70 male Wistar rats which received rations containing 4, 8, 12, 18 and 36% protein (casein), during a month. The total serum protein content and the proteins assayed in the blood plasma were not reliably changed in relation to the protein level in the animals' ration. It was found that the half-life of the proteins studied increased with the lowering of the protein content in the ration. It is suggested that the increase of the blood plasma protein half-life is one of the mechanisms of maintaining stable blood plasma protein composition in case of insufficient protein content in the food ration.     

Effect of diets with different caloric levels on blood protein turnover

The content of albumin, fibrinogen, the summary fraction of IgG + transferrin and summary serum proteins in the blood plasma, their turnover constant and half-life were investigated in 122 Wistar male rats that during a month received rations with reduced calorific value at the expense of carbohydrates or due to gradual diminution of protein, fat and carbohydrates in the ration. It has been shown that the permissible level of the ration calorific value reduction depends not only on the energy deficiency level, but also on the ration components at the expense of which the reduction is achieved. The reduction of the animals' nutrition calorific value influences the general development of growing rats and the blood protein turnover rate, the specific action on the mechanisms of the blood protein half-life regulation being of a greater importance than the energy deficiency.     

Glutathione-related enzymic activities in rats receiving high cholesterol or standard diets supplemented with two forms of selenium

Selenium deficiency was produced in rats fed a high cholesterol diet for 57 days (Group 1). It was characterized by an increase in malondialdehyde (MDA) an end product of lipid peroxidation and by the dramatic collapse of selenium-dependent glutathione peroxidase activity (GSHPx) in plasma, erythrocytes and in homogenate supernatant fraction of liver, kidney and heart compared with rats fed a standard diet containing sodium selenite (Group 3). A compensatory rise in the activity of liver glutathione S-transferase (GST) activity and also in glutathione reductase (GSSGR) activity was accompanied by an increase in NADPH-generating enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Adequate dietary selenium supplementation by Se-rich Spirulina corrected all the selenium deficiency effects (Group 2), then, GSHPx and NADPH-consuming enzymes activities were of the same magnitude as those exhibited by rats fed a standard diet containing adequate selenium in the form of sodium selenite. Based on this study, it is concluded that Se-enriched Spirulina behave as an excellent selenium carrier.     

A toxicological hygiene study of a dye made from abattoir blood for sausage products

Toxicologic and hygienic study of a pigment from abattoir blood--carboxyn (based on carboxyhemoglobin) was conducted on noninbred white rats in subacute (3 months) and chronic (12 months) experiments. The condition of the animals, their bw growth, blood morphology, erythrocyte sedimentation rate, the content of hemoglobin, protein and iron in the blood serum were evaluated. Activity of the following enzymes was studied: catalase and sorbitol dehydrogenase--in the blood serum; glucose 6-phosphate dehydrogenase, lactate dehydrogenase and cytochrome P-450 content--in the liver. Internal organs of the rats were subjected to histological investigation. The data obtained have evidenced the absence of some signs of biotransformation of the red complex of carboxyhemoglobin, or its toxic effect on the experimental animals. It has been concluded that carboxyn can be used as a coloring component in the production of sausage (in the amount of up to 2% of the sausage meat mass).     

卷须链霉菌木聚糖酶水解玉米芯汽爆液及酵母发酵精制低聚木糖

研究了卷须链霉菌 (Streptomycescirratus)D 1 0木聚糖酶水解玉米芯汽爆液的酶用量和水解时间 ,结果得到 80U/ 1 0 0mL酶用量和水解 6h是合适的加酶量和水解时间 ;筛选出 1株能够精制低聚木糖的Candiasp .酵母 ,该酵母能消耗木糖、阿拉伯糖而不消耗木二糖 ;利用此酵母精制酶解液 ,在接菌量为 1 0 %,48h时酶解液中木糖、阿拉伯糖完全被消耗 ,木二糖以上的低聚木糖含量变化不明显 ,因此利用该酵母能达到精制低聚木糖的效果     

Investigation of limiting metabolic steps in the utilization of xylose by recombinant Saccharomyces cerevisiae using metabolic engineering

A Saccharomyces cerevisiae screening strain was designed by combining multiple genetic modifications known to improve xylose utilization with the primary objective of enhancing xylose growth and fermentation in xylose isomerase (XI)-expressing strains. Strain TMB 3045 was obtained by expressing the XI gene from Thermus thermophilus in a strain in which the GRE3 gene coding for aldose reductase was deleted, and the genes encoding xylulokinase (XK) and the enzymes of the non-oxidative pentose phosphate pathway (PPP) [transaldolase (TAL), transketolase (TKL), ribose 5-phosphate ketol-isomerase (RKI) and ribulose 5-phosphate epimerase (RPE)] were overexpressed. A xylose-growing and fermenting strain (TMB 3050) was derived from TMB 3045 by repeated cultivation on xylose medium. Despite its low XI activity, TMB 3050 was capable of aerobic xylose growth and anaerobic ethanol production at 30 degrees C. The aerobic xylose growth rate reached 0.17 l/h when XI was replaced with xylose reductase (XR) and xylitol dehydrogenase (XDH) genes expressed from a multicopy plasmid, demonstrating that the screening system was functional. Xylose growth had not previously been detected in strains in which the PPP genes were not overexpressed or when overexpressing the PPP genes but having XR and XDH genes chromosomally integrated. This demonstrates the necessity to simultaneously increase the conversion of xylose to xylulose and the metabolic steps downstream of xylulose for efficient xylose utilization in S. cerevisiae.     

Effect of a carbohydrate-free diet on changes in lipid and proteins levels in rat tissues

The influence of carbohydrate-free and high-fatty (82% calorific value) ration on the content and turnover of proteins and lipids in the liver and perirenal fatty tissue was studied in experiments in vivo, in male Wistar rats (n = 23) with initial body weight (bw) 200 +/- 10 g. One month after the feeding with the ration studied bw of rats given carbohydrate-free diets did not differ from that of the control animals. The protein content was decreased and its turnover slowed down in hepatocytes of rats given carbohydrate-free ration. No significant changes were detected in the lipid content and turnover in hepatocytes. No changes were recorded in the protein content and turnover in the rat fatty tissue; however, significant changes were observed in the lipid turnover. They were manifest in an increased use of ramified aminoacid metabolites in lipid synthesis, and in speeding up the lipid turnover.     

Proteins,isoleucine, lysine and methionine content of bovine,porcine and poultry blood and their fractions

Studies carried out in bovine blood proteins pointed out that they are excellent sources of lysine (Lys), but deficient in isoleucine (Ile) and methionine (Met). The purpose of this investigation was to determine and compare the content of proteins, Lys, Ile and Met in whole blood, red cells and plasma of bovine, porcine and poultry species. Blood from the different species were centrifuged for their separation in plasma and red cells. Proteins, Lys, Ile and Met content in blood and their fractions were determined. Results showed that protein content in bovine and porcine blood and plasma were significantly higher than those for poultry. Red cells and plasma proteins from poultry posses superior levels of Ile than bovine and porcine red cells and plasma. Lys content was high for all blood and fraction species. Met was low in all the species under study.     

木糖添加量对面团流变学特性与面包品质的影响

添加木糖代替面包配方中的蔗糖,采用直接发酵法制作木糖面包。采用粉质仪法、拉伸仪法测定添加木糖前后面团的流变学特性,研究木糖添加量对面团流变学特性和面包品质的影响。结果表明:木糖添加量越高,面团的粉质指数越低,稳定和断裂时间越短,软化度和公差指数越高;添加木糖可使面团的吸水量减少,对形成时间无影响。随木糖添加量的增加,面团的拉伸能量、拉伸阻力和拉伸比降低,而延伸度增加;但是随醒发时间的增加,木糖添加量与拉伸特性各指标间相关系数降低,木糖对面团拉伸特性的影响效果减弱。配方中添加1.5%的蔗糖即可满足面包酵母生长需求。添加木糖对面包的规则度影响较小,但可使面包的体积和比容变小,感官品质变差;木糖添加量3.0%时面包硬度最小,超过3.0%时面包体积、比容和感官得分明显降低。添加木糖可提高面包的水分保持能力和抗氧化能力,对酸度和酸价无影响。     

Effect of soy protein on intestinal absorptive ability of calves by the xylose absorption test

Five calves per group were fed whole milk (control) or one of three milk replacers with one-thrid of the total protein provided by a soy product. Soy products were Promocaf (a commercial soy protein concentrate), an experimental soy flour. After a 24-h fast, calves were fed xylose solution. Urine was collected for 5 h. Jugular blood was sampled at 0, .5, 1, 1.5, 2, 2.5, 3, 4, and 5 h after xylose administration. Xylose tests were weekly on each calf through 5 wk of age. Urinary xylose excretion, as a percentage of xylose fed, was higher in the control group during the last 4 wk than in groups fed milk replacers. Mean urinary xylose excretions during 5 wk from calves sampled 5 h after xylose administration were 12.4, 4.2, 4.2, and 4.3% of xylose administered for calves fed milk, soy flour, soy protein concentrate, and Promocaf, respectively. Mean increases in peak of xylose concentration in plasma were 55.7, 44.4, 42.8, and 45.3 mg/100 ml. Peak values for control calves were higher than those for calves fed soy products at wk 4 and 5. Times required to reach peak value did not differ significantly. Neither xylose concentration of plasma nor urinary xylose excretion differed among the groups fed soy products.     

Effects of adrenalectomy and glucocorticoid therapy on enzyme activities in mammary and adipose tissues from lactating rats.

Several mammary and adipose enzymes were measured in normal, adrenal-ectomized, adrenalectomized cortisol-treated, and intake-restricted lactating rats. Acetyl-CoA carboxylase, lipoprotein lipase, and triglyceride synthetase complex activities in mammary tissue were unchanged by intake restriction, decreased by adrenalectomy, and increased by glucocorticoid-replacement therapy. Malic dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and lipoprotein lipase activities in adipose were unchanged after adrenalectomy.     

保健食品中低聚木糖含量测定

目的建立一种含有多糖纤维和低聚木糖的保健食品中低聚木糖含量测定的方法。方法用无水乙醇沉淀多糖纤维,将多糖纤维从试样中分离,用12%稀硫酸溶液将试样中的低聚木糖酸解为木糖,10%氢氧化钠溶液调p H至中性,选择适合的糖柱,以木糖为标样,外标法计算低聚木糖的含量(以木糖通过转换系数计)。结果酸解后试样中木糖浓度在0.0378~0.4536 mg/m L的范围内与峰面积的线性关系良好,相关系数r0.999。在3水平不同浓度木糖标准品添加下,木糖的回收率为97.9%。结论该方法操作简便、重现性好,适用于添加了多糖纤维和低聚木糖的保健食品中低聚木糖的含量测定。     

麦胚球蛋白对亚硝酸盐急性中毒大鼠肝损伤的保护作用研究

研究不同剂量的麦胚球蛋白(wheat-embryo globulin,WEG)对亚硝酸盐急性中毒大鼠肝损伤的保护作用。该实验测定肝脏组织中丙二醛(malondialdehyde,MDA)含量、超氧化物歧化酶(superoxide dismutase,SOD)活性以及谷胱甘肽(gluthione,GSH)含量,同时对血清中谷草转氨酶(aspartate aminotransferase,AST)、乳酸脱氢酶(lactate dehydrogenase,LDH)以及谷丙转氨酶(alanine aminotransferase,ALT)的活性进行检测,并以苏木晴-伊红染色(hematoxylineosin staining,HE)在显微镜下观察大鼠肝组织形态变化。结果表明:在亚硝酸盐急性中毒模型中,不同剂量的麦胚球蛋白均能减少脂质过氧化产物MDA含量(p<0.05),提高肝脏中SOD活性和GSH含量,降低血清中AST、ALT以及LDH水平(p<0.05),肝脏变性和坏死病理程度明显减轻。可见麦胚球蛋白对亚硝酸盐中毒大鼠肝损伤具有明显保护作用。     

The metabolic efficiency of baker's yeast in an atherogenic diet

The effect of bakery compressed yeasts in the amounts of 6 and 12 g/100 g of the ration was studied in rats. It was revealed that 12 g of yeasts per 100 g of the atherogenic ration produced a hypocholesterolemic effect. A negative effect of this amount of the yeasts was manifest in the slow growth of the rats' body mass and in an increased ratio of the kidney/body mass. The yeasts amounts used did not protect the test animals from the kidney infiltration with lipids and cholesterol; 12 g of yeasts per 100 g of the ration promoted elevation of sialic acid content in the blood plasma. Morphologic changes were observed only in the aortal wall, they were characteristic of the prelipid stage of atherosclerosis and did not depend on the yeasts amount.     

Effect of the ratio of polyunsaturated fatty acids of the omega 6 and omega 3 families in the diet of rats on the cholesterol content of the blood plasma and liver

The influence of polyunsaturated fatty acids omega 6 and omega 3 on the cholesterol level in the blood plasma and liver was studied in rats fed with rations containing no fats during 6 weeks. The total cholesterol content in the blood plasma decreased in the animals given ration with eicosapentaenoic acid (EPA), and the ration containing "Iwashi" sardine fat combined with sunflower oil. In the animals receiving the latter ration the level of free cholesterol in the liver lowered, however, the level of total cholesterol and its esters rose that could be explained by the reduction of the ratio of fatty acids 20:4/18:2 in cholesterol esters.     

The vitamin E allowance of rats on different combinations of sunflower and soybean oils in their diets

Soybean oil and its combinations with sunflower oil, as 1:1 and 1:3, were used in the rations intended for rats. As it is evidenced by the data on the content of tocopherol in the tissues, malonic dialdehide in the liver, diene conjugates in the liver and red blood cells, and red blood cell resistance, the fatty products used in the rations sufficiently provided the animals with antioxidants. The role of tocopherol isomers and phosphatides, as synergists of antioxidants in varying combinations of soybean and sunflower oils, formed for simultaneous intake of linoleic and linolenic acids with the ration, has been analyzed.     

The role of niacin in regulating the pentosophosphate pathway and production of NADP-H in fatty tissue

A study was made of the effect of alimentary deficiency of niacin and of exogenous nicotinamide (500 mg/kg) on the activity of the key enzymes of the pentose phosphate pathway and NADP-dependent malate and isocitric dehydrogenase in the epididymal fatty tissue of rats. It is established that vitamin depletion in the animals' body brings about a 3-fold decrease in the content of NADP+ and a 1.7-fold decrease in the content of NADPH, a 43-percent inhibition of the activity of glucose 6-phosphate dehydrogenase and a 39-percent reduction with respect to transketolase. Nicotinamide suppresses the activity of glucose 6-phosphate dehydrogenase by 35% and that of isocitric dehydrogenase by 40% 12 hours after intraperitoneal injection. It is suggested that NADPH production in the fatty tissue of rats undergoes appreciable changes under the effect of niacin.     

Enhancement of xylose uptake in 2-deoxyglucose tolerant mutant of Saccharomyces cerevisiae

Chemical mutation of Saccharomyces cerevisiae using ethyl methane sulfonate was performed to enhance its ability of xylose uptake for ethanol production from lignocellulose under microaerobic condition. Among the appeared mutants, the mutant no. 2 (M2) strain screened using inhibitory effects of 2-deoxyglucose (DOG) showed more than 4-fold high ability in xylose uptake compared with the wild type strain, under the presence of glucose. The catabolite repression by glucose was sufficiently reduced in M2 strain due to its tolerance to the high concentration of DOG (0.5%, wt./vol.). Metabolomic analyses of various sugars in the cell revealed that some of xylose was reduced to xylitol in M2 cell, providing the concentration gradient of xylose and more uptake of xylose. Xylulose-5-phosphate was significantly detected in the crude cell extract from M2 strain, indicating higher metabolic activity in pentose phosphate pathway. This was also confirmed by in vitro analyses of key enzymes involved in glucose and xylose metabolism, such as hexokinase, glucose-6-phosphate dehydrogenase and xylose reductase. Glucose uptake was moderately suppressed in the presence of trehalose-6-phosphate inhibiting the activation of hexokinase, resulting in more uptake of xylose through hexose transport system. To our knowledge, this study is the first report verifying that the mutation technique successfully enhances the xylose uptake by S. cerevisiae, particularly under the presence of glucose.     

Influence of rations with various linoleic acid contents on the fatty acid composition of phospholipids in blood platelets of rats

Gas-liquid chromatography was used to study the fatty-acid composition of phospholipids in platelets of Wistar-Kioto rats which received semisynthetic rations with varying content of linoleic acid, 1 week prenatally and 18 weeks postnatally. In ration I the level of 18:2n6 was lower than 0.1 cal%, ration II contained 9.0 cal%, and ration III -- 16.0 cal%. Ration III, as compared to ration II, induced an increase in the content of linoleic fatty acids, arachidonic fatty acid content being unchanged. Ration I, as compared to ration II induced a decrease in linoleic fatty acid content, and an increase in the content of oleic and linolenic fatty acids attended by the appearance of appreciable amounts of 20:3n9 and 20:5n3. Long-term linoleic acid deficiency induced no changes in the unsaturation degree of fatty acids in platelet phospholipids of rats given ration I. This is an evidence of high reserve possibilities of the mechanisms regulating fatty acid metabolism in the mammals.