葡萄糖转运载体4、葡萄糖转运载体2在罗非鱼不同组织中的表达及其对注射葡萄糖的响应

本试验旨在研究葡萄糖转运载体(GLUT)4、CLUT2在罗非鱼不同组织中的表达及其对注射葡萄糖的响应。利用实时荧光PCR的方法从罗非鱼肌肉中克隆得到GLUT4的c DNA片段,其Gen Bank登录号为JN900493,大小为603 bp,编码200个氨基酸。通过实时荧光半定量PCR检测,比较G LUT4和G LUT2在肌肉、心脏和肝脏中的表达差异,结果显示G LUT4在肌肉和心脏中的表达量较高,而在肝脏中GLUT4的表达量则较低;GLUT2在肝脏中的表达量最高,而在肌肉和心脏中则表现出极低的表达量。选取体重约为80 g的罗非鱼150尾,随机分2个组,每组3个重复,每个重复25尾。试验组腹腔注射葡萄糖(每100 g体重30 mg),对照组以相同剂量腹腔注射0.7%的无菌生理盐水。在注射前(0 h)和注射后的1、3、6和12 h分别进行采样测定。结果显示:1)试验组血浆葡萄糖含量在注射葡萄糖后1 h时达到最高,并显著高于对照组(P<0.05),而后开始下降,3 h后恢复到正常水平;试验组血浆胰岛素含量在葡萄糖注射后3 h时达到最高,并显著高于对照组(P<0.05),而后开始下降,12 h后恢复到正常水平。2)试验组肌肉中GLUT4 mRNA的相对表达量在注射葡萄糖后3 h开始升高,在12 h时达到最高,此时显著高于对照组(P<0.05);试验组心脏中GLUT4 mRNA的相对表达量在注射葡萄糖后1 h即较对照组显著升高(P<0.05),而后随着时间的推移逐渐降低,在6 h时恢复到正常水平;注射葡萄糖后,肝脏中GLUT2 mRNA的相对表达量没有显著变化(P>0.05)。结果表明,注射葡萄糖后瞬时升高了罗非鱼的血浆葡萄糖含量,相对于血浆葡萄糖含量的升高,血浆胰岛素含量的升高相对延迟,而肌肉中GLUT4 mRNA相对表达量的提高又延迟于胰岛素含量的升高,从而加重了罗非鱼对葡萄糖的代谢负担。     

非反刍动物小肠内葡萄糖的吸收与调控

营养性碳水化合物被非反刍动物摄入后，在消化道内逐渐降解成葡萄糖等单糖以及少量的双糖。小部分葡萄糖在门静脉回流组织(PDV)中进行供能代谢，大部分被小肠绒毛吸收而进入门静脉。葡萄糖吸收是由小肠黏膜上的Na^ 依赖型葡萄糖协同转运1(SGLT1)、Na ／K ATP酶、葡萄糖转运子2(GLUT2)以及与吸收有关的调控因子共同完成。     

Blood-to-saliva glucose time lag in sedated healthy dogs

The management of diabetes mellitus mandates measurement of blood glucose. Saliva offers an alternative to blood sampling, but measurement of the salivary glucose concentration is difficult, and the blood-to-saliva glucose time lag is uncertain. We aimed to determine the serum–saliva glucose time lag in the saliva of healthy dogs. The combined duct of the mandibular and sublingual salivary glands of 6 dogs was cannulated to collect saliva and prevent glucose degradation by oral bacteria. Following a 0.25 g/kg IV bolus of dextrose, paired serum–saliva samples were collected at baseline and in twelve 5-min blocks over 60 min. Serum and salivary glucose levels were analyzed with a linear mixed model for repeated measures with a compound symmetry error structure. Mean (±SD) saliva production was 10.3 ± 2.9 µL/kg/min, and the area under the curve (AUC_glucose)_saliva/serum ratio was 0.006, which highlights the magnitude of the large difference in glucose concentration between the 2 compartments. The serum–saliva glucose time lag was 30–40 min.     

Handbook of the Mammals of the World

Frugivores feed on fruits and nectars that contain different types of sugars in different proportions, which provide these animals with energy. Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) has a high glucose intake irrespective of sugar concentration of nectar. It is not known how these bats regulate their blood plasma glucose concentrations in order to avoid the negative effects associated with hyperglycemia. Fruit bats have a high amount of sugar intake in a short period of time which could cause a glucose challenge and it is therefore necessary to determine whether these bats are able to regulate their blood plasma glucose concentrations within normal concentrations. This study investigated the diel variations in blood plasma glucose concentrations of E. wahlbergi. Epomophorus wahlbergi‘s blood plasma glucose concentration was lower (5.24 ± 0.38 mmol/l) at 18:00 before feeding and increased during/after feeding (8.19 ± 1.24 mmol/l) but bats appeared to regulate it within limits. Their range in concentrations was higher than the normal mammalian blood plasma glucose concentrations range. Consequently these bats appear to regulate their blood plasma glucose concentration, although at a range higher than normal mammalian levels, and thus reduce the negative consequences associated with hyperglycemia.     

蜂胶对正常小鼠血糖的影响

将90只ICR小鼠随机分为模型组、蜂胶水提液低剂量组(WSPI)、蜂胶水提液高剂量组(WSP2)、蜂胶醇提液低剂量组(EEP1)、蜂胶醇提液高剂量组(EEP2)和阳性对照组(拜糖苹)，首先测空腹血糖，然后给予不同的受试药物，1周后，所有小鼠禁食测空腹血糖，然后给予饲料，2h后测餐后血糖。结果发现，蜂胶对正常小鼠的空腹血糖和餐后血糖影响不显著，表明蜂胶对正常小鼠的血糖没有影响。     

Basal glucosuria in cats

Objective of this study was to demonstrate the ubiquitous presence of glucose in urine of euglycemic cats by a highly sensitive glucose assay. The local electronic database was searched for results of quantitative urine glucose measurements in cats. A total of 325 feline urine glucose measurements were identified, of which 303 (93%) had been submitted by one of the co‐authors working in a near‐by small animal practice. After the exclusion of patients with kidney disease (n = 60), hyperthyroidism (n = 15), diabetes mellitus (n = 11), multiple diseases (n = 9) or steroid treatment (n = 3), as well as serial measurements (n = 87) and outliers (n = 8), the final study population consisted of 132 cats. Urine creatinine concentration was unavailable in five patients. Whereas all but one cat had glucose concentrations above the detection limit of the assay (0.11 mmol/L, Gluco‐quant Enzyme Kit/Roche Diagnostics), no positive glucose dipstick test result (Combur 9‐Test, Roche Diagnostics) was observed. The median (range) of urinary glucose concentration and the glucose‐to‐creatinine ratio (UGCR) was 0.389 (<0.11–1.665) mmol/L and 0.0258 (0.007–0.517) respectively. The UGCR was not affected by age, gender, breed or leukocyturia, whereas cats with hematuria had slightly higher values. Data show that so‐called “basal glucosuria” is present in the majority of cats and by no means diagnostic for diabetes mellitus or renal glucosuria. This has to be considered when using bio‐analytical methods with a low limit of quantification.     

Glycemic Status and Predictors of Relapse for Diabetic Cats in Remission

Background

It is unknown if diabetic cats in remission have persistent abnormalities of glucose metabolism and should be considered prediabetic, or have normal glucose tolerance.

Objective

To characterize glycemic status of diabetic cats in remission and to determine predictors of relapse.

Animals

A total of 21 cats in diabetic remission and 28 healthy control cats.

Methods

At a median of 107 days after remission, screening blood glucose concentration was measured on entry to the clinic. After a 24‐hour fast in hospital, fasting blood glucose, fructosamine and feline pancreatic lipase concentrations were measured, and 3 hours later, a simplified IV glucose tolerance test (1 g glucose/kg) performed. Twenty cats were monitored for relapse for at least 9 months.

Results

Of the 21 cats in remission, 19% (4/21) had impaired fasting glucose concentration and 76% (16/21) had impaired glucose tolerance. Of cats followed up for 9 months after testing, 30% (6/20) had relapsed and required insulin treatment. Fasting blood glucose concentration ≥7.5 mmol/L (≥135 mg/dL) (odds ratio [OR] = 12.8) and severely impaired glucose tolerance (≥5 hours to return to <6.5 mmol/L or <117 mg/dL; OR = 15.2) were significantly associated with relapse. Blood glucose concentration >14 mmol/L; 252 mg/dL at 3 hours was significantly associated with relapse (OR = 10.1).

Conclusion and Clinical Importance

Most cats in diabetic remission have impaired glucose tolerance and a minority have impaired fasting glucose concentration and should be considered prediabetic. More severe glucose intolerance and impaired fasting glucose concentration are predictors of relapse. Ongoing glucose monitoring of diabetic cats in remission is recommended.     

In vitro effects of insulin on glucose and lipid metabolism in rat embryos

Glucose is utilized for oxidation and synthesis of various lipids in cultured rat embryos. The present experiment examined the effect of insulin on the incorporation of glucose into lipid fractions in rat embryos in vitro . Embryos at the 2-cell, 8-cell and blastocyst stages were incubated for 5 h in hamster embryo culture medium (HECM)-1 containing ¹⁴C-glucose and 170 nmol/L insulin, or in HECM-1 containing only ¹⁴C-glucose, and the oxidation of glucose in these embryos was examined. In addition, the total lipids of blastocysts were separated by thin layer chromatography and the radioactivity of the separated lipid fractions was measured. Oxidation of glucose was significantly increased after insulin treatment compared with that without insulin treatment in 8-cell embryos and blastocysts ( P  < 0.05), but not in 2-cell embryos. Incorporation of glucose into lipids in blastocysts was significantly lowered by insulin treatment compared with that without insulin treatment ( P  < 0.05). Most of the radioactivity was recovered from triacylglycerols of blastocysts and the remaining radioactivity was found in other neutral lipids and phospholipids. We conclude that insulin accelerates the utilization for oxidation of glucose and inhibits the storage of triacylglycerols in rat blastocysts.     

Calcium-stimulation test for the assessment of beta-cell function in cats

To assess the potential of an intravenous calcium-stimulation test (CST) as an indicator of insulin secretion in cats, indices calculated from CST results were compared with indices of insulin secretion derived from an intravenous glucose tolerance test (ivGTT) and hyperglycaemic glucose clamp (HGC) in 11 healthy, normal glucose tolerant, conscious cats. Intravenous administration of 2.5mg/kg Ca(2+) resulted in a significant increase in plasma free Ca(2+) (P<0.001) and plasma insulin (P=0.047) concentrations but did not affect the plasma glucose concentration. The indices of insulin secretion based on the CST did not correlate significantly with corresponding indices based on the ivGTT and HGC. In conclusion, the CST is not a useful test for assessing insulin secretion in cats. Other indices of insulin secretion, such as fasting insulin concentrations and the homeostasis model assessment of beta-cell function (HOMA-B), are easier to obtain and correlate better with indices of insulin secretion derived from the HGC, the gold standard technique for assessing insulin secretion.     

Clinical assessment of blood glucose homeostasis in horses: comparison of a continuous glucose monitoring system with a combined intravenous glucose and insulin test protocol

Background: The combined glucose‐insulin test (CGIT) is helpful for evaluating insulin sensitivity. A continuous glucose monitoring system (CGMS) reports changes in interstitial glucose concentrations as they occur in the blood. Use of the CGMS minimizes animal contact and may be useful when performing a CGIT. Hypothesis: Results obtained using a CGMS are useful for the evaluation of glucose responses during the evaluation of insulin sensitivity in equids. Animals: Seven mature, obese ponies. Methods: Ponies were equipped with CGMS for determination of interstitial glucose concentrations. Glucose (150 mg/kg, IV) and insulin (0.1 U/kg, IV) were administered and blood glucose concentrations determined at (minutes after time zero) 1, 5, 15, 25, 35, 45, 60, 75, 90, 105, and 120 with a hand‐held glucometer. Blood chemistry results were compared with simultaneously obtained results using CGMS. Results: Concordance coefficients determined for comparison of blood glucose concentrations determined by a hand‐held glucometer and those determined by CGMS after the zero time point were 0.623, 0.764, 0.834, 0.854, and 0.818 (for delays of 0, 5, 10, 15, and 20 minutes, respectively). Conclusions and Clinical Importance: Interstitial glucose concentrations obtained by the CGMS compared favorably to blood glucose concentrations. CGMS may be useful for assessment of glucose dynamics in the CGIT.     

葡萄糖氧化酶对鸡蛋品质的影响

在基础日粮中分别添加0、0.1%、0.2%、0.3%、0.4%葡萄糖氧化酶用于饲喂26周龄海兰褐蛋鸡,研究其对鸡蛋品质的影响。试验结果表明:蛋鸡日粮中添加葡萄糖氧化酶对改善鸡蛋品质有一定的作用。蛋鸡日粮中添加0.3%葡萄糖氧化酶显著提高了蛋壳厚度、哈氏单位和蛋比重(P<0.05);添加0.3%～0.4%葡萄糖氧化酶能显著降低蛋黄中胆固醇含量,以0.4%添加组效果最明显(P<0.01);各试验组间蛋形指数、蛋黄颜色、蛋黄相对重和蛋壳相对重差异不显著(P>0.05)。     

Hyperglycaemia in transition dairy cows: Effects of lactational stage and conjugated linoleic acid supplementation on glucose metabolism and turnover

Supplementing conjugated linoleic acid ( CLA ) is supposed to spare glucose due to the milk fat‐depressing effect of the trans ‐10, cis ‐12 CLA isomer, and allows repartitioning nutrients despite an energy deficiency in early lactation. However, there is still a lack of knowledge in terms of the dynamic pattern of the glucose turnover in transition dairy cows. We hypothesized that dairy cows supplemented with CLA have an altered rate of glucose turnover and insulin sensitivity during early lactation. We conducted three consecutive hyperglycaemic clamps (HGC ) in weeks ?2, +2 and +4 relative to parturition in Holstein cows supplemented daily either with 70 g of lipid‐encapsulated CLA (6.8 g trans ‐10, cis ‐12 and 6.6 g of the cis ‐9, trans ‐11 CLA isomer; CLA ; n  = 11) or with 56 g of control fat ( CON ; n  = 11). From week ?3 up to week +4 relative to parturition, milk yield and dry matter intake (DMI ) were recorded daily, while body weight (BW ) and milk composition were obtained once weekly. Blood samples were taken once weekly and every 30 min during the HGC . Plasma was analysed for concentrations of glucose, fatty acids (FFA ), beta‐hydroxybutyrate (BHB ), insulin, triglycerides and cholesterol. The CLA supplementation did not affect performance and metabolic parameters except for BHB and cholesterol. Furthermore, insulin concentrations and insulin sensitivity were affected by treatment. During the HGC in early lactation, insulin response was lower and decrease in FFA and BHB greater compared with the HGC in week ?2 although glucose target concentration achieved during the steady‐state period was similar for all three HGC . Our findings in terms of insulin and cholesterol suggest that body reserves are preserved through CLA feeding without restraining animal's performance. Furthermore, CLA effects on cholesterol and triglyceride concentrations indicated beneficial effects on hepatic lipid export contributing to an improved efficiency of prevailing metabolites in circulation.     

β-CM5对离体大鼠小肠葡萄糖吸收的影响

为了探讨β-酪啡肽-5(β-CM5)对大鼠小肠葡萄糖吸收的影响,利用翻转的离体小肠模型,通过测定60 min内β-CM5不同浓度组肠囊内葡萄糖含量及葡萄糖的转运率;测定离体肠道黏膜α-葡萄糖苷酶、Na+-K+-ATP酶活力,分析大鼠小肠钠依赖性葡萄糖共转运载体(SGLT-1)及葡萄糖转运载体2(GLUT-2)mRNA表达水平,揭示β-CM5对葡萄糖吸收影响及机制。结果:不同浓度β-CM5肠囊内葡萄糖的转运量及转运率均显著低于对照组;β-CM5组小肠黏膜中α-葡萄糖苷酶和Na+-K+-ATP酶活力显著低于对照组;β-CM5组小肠黏膜中SGLT-1、GLUT-2 mRNA表达量与对照组相比均显著性下调。结果表明:β-CM5可以通过抑制葡萄糖吸收的相关酶活性,下调葡萄糖转运载体mRNA的表达,从而抑制肠道葡萄糖的吸收,提示β-CM5可能具有降糖作用。     

Molecular insights into dietary induced colic in the horse

Equine colic, a disorder manifested in abdominal pain, is the most frequent cause of emergency treatment and death in horses. Colic often requires intestinal surgery, subsequent hospitalisation and post operative care, with a strong risk of complications arising from surgery. Therefore strategies that explore approaches for preventing the condition are essential. To this end, a better understanding of the factors and mechanisms that lead to the development of colic and related intestinal diseases in the horse allows the design of preventive procedures. Colic is a multifactorial disorder that appears to be induced by environmental factors and possibly a genetic predisposition. One factor that seems to influence the risk of developing colic is the excessive consumption of diets containing high levels of carbohydrates. Therefore, major efforts have been made by various laboratories and institutions across the world to study the type and digestibility of various feed in order to formulate accurate and safe feed components and proportions. However, relatively little work has been carried out to characterise, in detail, the carbohydrate digestive and absorptive capacity and mechanisms underlying the potential adaptive response of equine gut epithelium to a changing diet. This review focuses on advances made towards understanding the molecular and cellular mechanisms involved in digestion and absorption of dietary carbohydrates in the equine gastrointestinal tract and the implication of these processes for the whole body physiology. It addresses the underlying mechanisms that may govern the adaptive response of equine small intestine to increased dietary hydrolysable carbohydrates. Furthermore, it describes changes that occur in the equine large intestinal microbiology and host tissue biology brought about by alterations in diet and in colic. It is hoped that a better understanding of the molecular and cellular processes that play important roles in the physiology and pathology of the equine gastrointestinal tract will assist the development of effective strategies to prevent equine colic.     

Effects of supplementation of chromium histidinate on glucose,lipid metabolism and oxidative stress in cats

In recent years, two meta‐analyses of chromium (Cr) supplementation have shown beneficial effects on glucose metabolism. Chromium histidinate (CrHis) reduces serum glucose levels in rats fed a high‐fat diet but no study has been conducted on cats until now. The aim of this study was to examine the effects of CrHis on glucose and lipid metabolism in cats. To challenge the glucose metabolism, 16 cats were fed a high‐carbohydrate high‐fat diet for three months. One group (n = 8) received 800 ug CrHis per day for two months, while the other group (n = 8) served as control group. An oral glucose tolerance test was conducted, blood samples were taken, and biochemical parameters and oxidative stress were measured. CrHis serum levels were significantly increased (p = 0.027) in the treatment group, while fructosamine levels were significantly lower (p = 0.029) in the control group. In both groups, glucose (p < 0.01), b‐hydroxy‐butyrate (p = 0.024) and 8‐hydroxy‐deoxyguanosine (p = 0.028) levels decreased significantly and cholesterol levels increased significantly (p < 0.01). In conclusion, CrHis did not improve glucose or lipid metabolism and did not affect oxidative stress in healthy cats.     

The intravenous glucose tolerance test in water buffalo

OBJECTIVE: The response to intravenous glucose loading in the buffalo using the intravenous glucose tolerance test (IGTT) was investigated to provide a reference for intravenous glucose injection in buffaloes. METHOD: Twelve healthy, fasted, male swamp buffaloes were divided into three groups. Group I: six buffaloes were given 50% glucose at a dosage of 1 g/kg body weight via the jugular vein. Group II: three buffaloes received normal saline. Group III: three buffaloes were not injected. Blood samples were taken from the opposite vein at 60 and 10 min pre-injection (pre60 and pre10), and at 1, 5, 10, 30, 60, 120, 180, 240, 300, 360 and 420 min post-glucose injection (PGI). Plasma glucose was analyzed by the oxidase method. Insulin and glucagon were soon determined with a human radioimmunoassay kit. The insulin (pmol/l)/glucose (mmol/l) ratios (IGR) were also calculated for each sampling time. RESULTS: Mean plasma glucose, insulin and glucagon concentrations of buffaloes in groups II and III were similar at all the sampling times (p > 0.05) and the curves of the IGR for group II and group III were flat throughout. Group I Buffaloes showed an immediate 20 times increase in the mean plasma glucose concentration PGI, over the pre60 and pre10. The peak plasma insulin concentration occurred at 30 min PGI. The mean plasma glucose and insulin concentrations remained above pre-administration levels until 420 min PGI (p < 0.05). However, the mean plasma glucagon concentrations were different only at 1 and 5 min PGI sampling times. The curve of the IGR for group I showed an initial decrease at 1 min PGI, and fluctuated from 10.18 to 25.55 for the remainder of the sampling period. The correlation analysis showed that the mean plasma glucose concentration was positively correlated with insulin level (r = 0.73, p < 0.005), and significantly negatively correlated with mean plasma glucagon (r = -0.58, p < 0.05). The mean plasma insulin level did not show significant correlation with the glucagon (r = 0.06, p > 0.05). CONCLUSION: The hyperglycemia, high insulin, and protracted glucose and insulin curves, the initial decrease in the insulin/glucose ratio indicates that there was an unexpected glucose tolerance to acute intravenous glucose loading in water buffalo compared with other ruminants. The possibly suggested intravenous glucose load in buffaloes is about 5.09-8.28 mmol/l.     

Evaluation of a Rapid Reagent Strip Test for Blood Glucose Determination in Diarrheic Calves

Sixty-three blood samples from 10 diarrheic calves were tested for glucose concentration by two methods. Plasma glucose concentration was measured by the conventional glucose-6-phosphate dehydrogenase method in the clinical laboratory, and the results compared to those obtained using a rapid reagent strip test for blood glucose concentration measurement. The rapid reagent strip test result could not be used to make an accurate prediction of the actual plasma glucose concentration as determined by the conventional method, due to the wide variability in actual plasma glucose concentrations corresponding to each rapid test result.