奶制品葡萄糖含量的酶法分析

本文介绍了利用葡萄糖氧化酶测定奶制品中葡萄糖含量的方法，并讨论了测量条件。该方法灵敏准确，操作简便，测定范围0－150mg/L，用于实际样品的测定，结果满意。     

高碳水化合物配方早餐对健康者餐后血糖影响

目的:研究高碳水化合物配方早餐(HCD)对健康志愿者餐后血糖的影响。方法 :10名健康志愿者为研究对象,先后摄人A、B、C、D、E套早餐,测量空腹、餐后0.5h、1h、2h的血糖值,计算血糖曲线下面积;问卷调查患者有无饥饿感。结果 :B餐血糖曲线下面积(SAUC)(19.72±1.66)明显高于A餐(16.03±1.25)(P<0.01)与C餐(16.81±2.23)(P<0.01),没有饥饿感的人数明显多于B餐和C餐。结论:合理配制的高碳水化合物配方早餐对健康志愿者餐后血糖调控有效。     

Human pancreatic glucokinase (GlkB) complements the glucose signalling defect of Saccharomyces cerevisiae hxk2 mutants

Human pancreatic glucokinase (GlkB, hexokinase IV) has been expressed in Saccharomyces cerevisiae. The recombinant protein showed similar enzyme kinetics to those described for the original enzyme. When expressed in hxk2 yeast mutants, GlkB complemented both the glucose induction and the glucose repression defects present in the mutant. It was also functional in regulating the activity of the Snf1 kinase complex in response to glucose, participating in the regulation of the Reg1/Glc7 phosphatase complex, as its yeast counterpart.     

用葡萄糖氧化酶法降低马铃薯颗粒全粉还原糖

观察了葡萄糖氧化酶 (GOD)对降低马铃薯颗粒全粉中葡萄糖及还原糖的作用。结果表明 ,当控制马铃薯颗粒全粉的水分在 5 0 %～ 60 % ,酸度为 3 5 ,温度为 3 9℃时 ,GOD的酶解降糖速度最快。在此条件下用GOD(5 0 0U/kg产品 )反应 1 80min ,可以使原料中的葡萄糖减少 80 %～ 90 % ,还原糖减低 3 0 %以上。     

Glucose metabolism in lactating cows in response to isoenergetic infusions of propionic acid or duodenal glucose

A bibliographical study showed that increasing supplies of glucogenic nutrients lead to a curvilinear increase in milk and protein yield. Increased post-hepatic glucose availability may be involved in the increase in milk yield. In the present experiment, 5 dairy cows were arranged in a 5 x 5 Latin square design to compare the respective effects of 2 amounts of either duodenal glucose or ruminal propionic acid (C3) on glucose metabolism. Treatment consisted of a grass silage-based diet supplemented with glucogenic nutrients infused into the rumen as a mixture of volatile fatty acids (control) or C3 (6.5 and 13 mol/d) or as glucose (3.4 and 6.9 mol/d) infused into the duodenum. Treatments were isoenergetic and isonitrogenous and contained 100 and 115% of energy and protein requirements, respectively, according to the Institut National de la Recherche Agronomique. Glucose appearance rate (Ra) tended to increase with the level of infusions of both glucogenic materials and with the high dose of duodenal glucose. Plasma insulin-like growth factor-I (IGF-I) concentration increased with the infusion of glucogenic materials compared with the control and was significantly higher with glucose than with C3 treatments. This experiment did not indicate whether the increased Ra was the key mechanism to increased milk yield because milk yield only tended to increase and the standard error for Ra was high. With the high dose of glucose infused into the duodenum, the Ra increase was greater than the increased lactose production in milk. Because of that connection, IGF-I may also be involved by favoring the glucose utilization by the mammary gland.     

预处理和贮藏条件对脱水甘蓝表面返霜的影响

添加葡萄糖的脱水甘蓝在贮藏过程中葡萄糖极易从甘蓝内部迁移到表面．实验结果表明，渗糖处理时添加一定量的乳糖和高麦芽糖浆代替葡萄糖，对延长脱水甘蓝的返霜期有良好的效果，高麦芽糖浆对延长脱水甘蓝返霜的效果明显好于乳糖．实验还研究了热烫时间、贮藏环境的相对湿度对葡萄糖迁移影响的规律．热烫90s、贮藏在较低的环境湿度下均有利于延长脱水甘蓝的返霜天数．     

红枣多糖对小鼠血糖及血清胰岛素水平影响的初步研究

研究红枣多糖对正常小鼠血糖及糖耐量的影响,结果表明红枣多糖对正常小鼠血糖没有影响,对正常小鼠糖耐量有改善作用。为研究红枣多糖对四氧嘧啶、肾上腺素诱导的糖尿病小鼠血糖及血清胰岛素水平的影响,以200mg/kg剂量腹腔注射四氧嘧啶建立四氧嘧啶糖尿病动物模型,以0.03mg/kg剂量腹腔注射肾上腺素建立肾上腺素高血糖动物模型。对造模成功的小鼠随机分为模型对照组、红枣多糖大(0.8g/kg)、中(0.4g/kg)、小(0.2g/kg)剂量组和阳性药物组,以灌胃给药。对两种类型小鼠的处理均设立正常对照组,给予等体积的水。灌胃14d后测定小鼠空腹的血糖、胰岛素,结果表明红枣多糖对肾上腺素引起的急性血糖升高无明显作用,对四氧嘧啶诱导的糖尿病小鼠其大剂量显示出一定的降糖作用,并使得血清胰岛素水平有所升高。     

高纯度低聚果糖生产技术的探讨

低聚果糖是一种功能性低聚糖，用于特殊目的的低聚果糖必须具有很高的纯度。本文探讨了高纯度低聚果糖的生产技术     

Duodenal glucose increases glucose fluxes and lactose synthesis in grass silage-fed dairy cows

The effect of intestinal glucose supply on whole body rate of glucose appearance (WBGRa) and mammary utilization of glucose was studied in four lactating dairy cows. Glucose (0, 443, 963 and 2398 g/d) was continuously infused in the duodenum over 14-d periods using a Latin square design. A grass silage-based diet was formulated so that treatments were isoenergetic and isonitrogenous and contained 100 and 110% of energy and protein requirements according to INRA (1989). The WBGRa was measured by the [6,6-(2)H2]glucose dilution technique, and mammary glucose balance by arteriovenous differences and blood flow measurements. Duodenal glucose infusion increased arterial glucose concentrations linearly, whereas arterial concentrations of insulin, growth hormone, and glucagon were not changed. The WBGRa increased linearly with increasing glucose loads. The increase represented 42% of the intestinal glucose supplement. Mammary blood flow dramatically increased (up to 45%) and was associated with a significant increase of arterial insulin-like growth factor-1 concentrations. Mammary gland rate of glucose disappearance ([6,6-(2)H2]glucose measurement) increased linearly, whereas net mammary balance of glucose, lactose, and milk yields increased quadratically. Net mammary balance of glucose accounted for 60% of WBGRa, except for the greatest dose (47.6%). The decrease in milk yield with 2398 g/d of glucose may be explained by an imbalance in intracellular intermediate concentrations. The milk ratio of glucose-1-phosphate to glucose-6-phosphate decreased significantly at the greatest infusion of glucose. In conclusion, exogenous glucose supply to a grass silage-based diet increased WBGRa, mammary utilization of glucose and milk synthesis.     

盐酸精氨酸葡萄糖注射液中葡萄糖含量的测定

目的建立测定盐酸精氨酸葡萄糖注射液中葡萄糖含量的方法。方法选择适宜的pH值,然后通过考察该pH值下溶液旋光度与盐酸精氨酸和葡萄糖浓度的线性关系并测定盐酸精氨酸的比旋度,建立旋光法测定葡萄糖含量的计算公式。结果测定pH值为4.2。在此pH值下,盐酸精氨酸和葡萄糖混合溶液的旋光度与盐酸精氨酸浓度和葡萄糖浓度的复相关系数为0.9999,线性范围分别为2.3～3.0g/100ml和1.8～3.2g/100ml;测得盐酸精氨酸的比旋度为11.54。结论盐酸精氨酸和葡萄糖的旋光度具有加和性,从测得的旋光度中扣除盐酸精氨酸的旋光度,即是葡萄糖的旋光度,葡萄糖的含量可按公式c=2.0852(α-0.1154c1)计算。     

酶促反应合成葡萄糖硬脂酸酯的研究

以Novozym435脂肪酶为催化剂,正己烷为有机溶剂,丙二醇为乳化剂,酶促合成葡萄糖硬脂酸酯.考察了脂肪酶加入量、反应温度、反应时间、底物配比、体系含水量、振荡速率对酶促酯化反应的影响,确定了酶促反应的工艺条件;同时对产物进行了定性、定量分析.研究结果表明:酶加入量为脂肪酸质量的10%,底物酸、糖的摩尔比为1:1,温度为60℃,含水量为有机溶剂的5.3%,反应时间为4.5 h,振荡速率为100r/min时,硬脂酸最大转化率可达93.40%.     

Evaluation of glucose dose on intravenous glucose tolerance test traits in Holstein-Friesian heifers

Glucose metabolism in dairy and beef cattle has received considerable attention because balanced blood glucose is essential for numerous processes, such as milk production and general health. The glucose tolerance test measures the ability of an organism to regulate blood glucose levels. Glucose half-life time (GHLT) has high heritability and could serve as a potential parameter to breed for metabolic resistance. However, studies focusing on identification of an adequate glucose dose have not yet been conducted in cattle. The objective of this study was to analyze the effect of 5 different glucose doses (0.5, 1, 1.5, 2, and 3 g/kg of body weight^0.75) on intravenous glucose tolerance test (ivGTT) traits and insulin responses in nongestating heifers. A total of 150 tests were performed in 30 Holstein-Friesian heifers aged 13 to 15 mo. Blood samples were obtained every 7 min after glucose injection until min 63. Glucose traits and insulin parameters included blood serum glucose and insulin concentration at min 0 (basal concentration), min 7 to 21 (peak glucose and insulin concentration), and min 63 (last sampling) relative to glucose administration, glucose and insulin area under the curve (GAUC and IAUC), and GHLT estimated between min 14 and 42. Serum glucose and insulin concentrations were measured according to the hexokinase colorimetric method and radioimmunoassay, respectively. Generalized linear mixed model was used to test for significant differences in ivGTT traits, insulin responses, and glucose elimination rates (k) over time at different glucose doses. Maximum glucose and insulin concentrations at min 63 increased with higher glucose doses. Significantly lower GHLT were obtained at increasing glucose doses, whereas GAUC and IAUC were significantly higher at increasing doses. The k values were affected by glucose dose and by time interval. Glucose dose greatly affected most ivGTT traits, insulin responses, and glucose elimination rates. Therefore, researchers should standardize their methods to achieve repeatable results and use the same time points for GHLT calculation. Higher glucose doses (≥1.5 g/kg of body weight^0.75) triggered glucose concentrations above the glucose renal threshold during the initial 42 min, whereas the lowest glucose concentration failed to induce a maximum insulin response. Further research is necessary to determine an adequate dose inducing maximum insulin responses with minimum renal glucose losses.     

添加高钙菜、辣木对大米和糙米米粉品质及餐后血糖的影响

研究大米米粉、糙米米粉、高钙菜糙米米粉和辣木糙米米粉的蒸煮特性、体外模拟环境下葡萄糖释放量及小鼠餐后血糖反应的差异。结果表明,相比于大米米粉,配方为100%的糙米粉的米粉,无论是在米粉品质方面还是在血糖控制方面都优于大米米粉,其最终葡萄糖释放量要比大米米粉的葡萄糖释放量减少约40 mg,而添加了辣木、高钙菜等含有功能性成分物质的糙米米粉对小鼠的餐后血糖值也有降低作用,其最终的葡萄糖释放量分别比大米米粉的葡萄糖释放量减少约11、33 mg,且更能维持米粉的结构完整性,说明添加功能性成分对降低餐后血糖也有一定的作用;但是添加2%辣木和4%高钙菜的含量可能较少,与100%糙米米粉相比,其减缓葡萄糖释放的效果略不显著,100%糙米米粉更有利于人体血糖的调控。     

亚甲基蓝为介体的丝网印刷双酶修饰电极测定葡萄糖

以亚甲基蓝作为电子媒介,通过壳聚糖固定葡萄糖氧化酶和辣根过氧化酶在丝网印刷电极上,制备成葡萄糖生物传感器。循环伏安法和恒电位法用于研究修饰电极的电化学特性,在优化的实验条件下,获得传感器对葡萄糖响应的线性范围为8．0×10-5～3．5×10-3mol/L。此方法测定葡萄糖抗干扰能力强、重现性好、准确度高,电极制作简单,使用方便。     

益生菌对2型糖尿病缓解作用的研究进展

糖尿病是由多因素引发的一种慢性代谢性疾病,是21世纪全世界范围内的一种流行病。糖尿病患者的肠道菌群失调,抗氧化能力降低并伴有低度炎症。而有关研究显示,益生菌作为一种活的对肠道有益健康的微生物,它可通过平衡肠道菌群、降低机体的氧化损伤和调节机体的免疫因子,起到缓解糖尿病相关症状的作用。本文梳理了目前常用的以α-葡萄糖苷酶和DPP-IV为靶点来筛选降糖菌株的两种方法,并通过体内实验评价了益生菌的降糖作用。同时从肠道菌群、免疫反应、氧化应激、短链脂肪酸以及肠道屏障等五个方面进一步概括了益生菌缓解2型糖尿病的作用机制,以期为2型糖尿病的相关研究提供一定的参考。     

家蚕丝素粉对糖尿病预防作用的研究

研究了家蚕丝素粉对糖尿病小鼠的预防作用和对正常小鼠血糖及葡萄糖的耐受作用。结果表明,家蚕丝素粉在1000mg/kg和3000mg/kg的剂量下,糖尿病小鼠的空腹血糖值明显低于模型组23.38%和38.22%,达到了显著水平;家蚕丝素粉对正常小鼠血糖无明显降低作用;家蚕丝素粉在1000mg/kg和3000mg/kg的剂量下具有明显增强正常小鼠的葡萄糖耐受作用,而且达到了显著水平。     

Isolation and preliminary characterization of Pichia pinus mutants insensitive to glucose repression

A new method for the isolation of glucose repression-insensitive mutants in the methylotrophic yeast Pichia pinus was developed. The method is based on screening of small suspension samples derived from 2-deoxyglucose-resistant colonies for alcohol oxidase activity. Alcohol oxidase activity was evaluated by determination of formaldehyde excreted by cells. Mutants with glucose non-repressible alcohol oxidase and catalase synthesis were obtained. All mutants grew poorly on D -xylose compared to the wild type, whereas growth on L -arabinose was similar to the wild type. Changes in the glucose transport system were suggested to be responsible for altered growth characteristics and defective glucose repression.     

Metabolomic analysis of significant changes in Lactobacillus casei Zhang during culturing to generation 4,000 under conditions of glucose restriction

Lactic acid bacteria are being consumed more frequently as awareness of their health benefits has increased. The industrial production of lactic acid bacteria requires a comprehensive understanding of their survival stress, especially regarding changes in metabolic substances in a glucose-limited environment. In the present study, a metabolomic approach was applied to investigate Lactobacillus casei Zhang using cultures from a common ancestor that were permitted to evolve under conditions with normal or glucose-restricted media for up to 4,000 generations. Metabolomic analyses of intracellular and extracellular differential metabolites under De Man, Rogosa and Sharpe broth (2% vol/vol glucose; Oxoid Ltd., Basingstoke, UK) and glucose-restricted (0.02% vol/vol glucose in De Man, Rogosa and Sharpe broth) conditions were performed at generations 0, 2,000, and 4,000 and revealed 23 different metabolites. Myristic acid, ergothioneine, Lys-Thr, and palmitamide contents exhibited significant reductions between 0 and 4,000 generations, whereas nicotinate, histidine, palmitic acid, l-lysine, urocanate, thymine, and other substances increased. The dynamics of the pathways involved in AA metabolism, including glycine, serine, and threonine metabolism, histidine metabolism, lysine degradation, and arginine and proline metabolism, were also a focus of the present study. There were also changes in several other metabolic pathways, including vitamin B₆, thiamine, nicotinate, and nicotinamide, according to generation time. Additionally, in the present study we screened for key metabolites involved in the glucose-restricted response and provided a theoretical basis for comprehensively revealing the regulatory mechanisms associated with L. casei Zhang glucose restriction at the metabolic level. These findings also provide novel ideas and methods for analyzing the glucose-restricted stress response at the metabolic level.