功劳木的化学成分及其体外对P-糖蛋白转运的影响

目的研究功劳木的化学成分,评价其体外对P-糖蛋白转运的影响。方法功劳木用体积分数为70%乙醇提取,得到的浸膏经硅胶干柱色谱分成8份,其中第3～5份和第8份经反复硅胶柱色谱分离得到3个化合物,利用理化性质和波谱数据鉴定了它们的化学结构,并检测3个化合物对耐药细胞株K562/ADM细胞内罗丹明（rhodamine123,Rh123）蓄积的影响。结果显示3个化合物分别为：1-O-（β-D-glucopyranosyl）-（2S,3S,4R,8E）-2-[（2’R）-2’-hydroxytetra cosenoilamino]-8-octadec-ene-1,3,4-triol（1）、erthro-syringoyl glycerol 4-O-β-D-glucoside（2）、葡萄糖（3）。结论化合物1～3为首次从本属植物中分离得到,化合物1和2明显增加耐药细胞株K562/ADM细胞内罗丹明（rhodamine123,Rh123）蓄积量,表现出抑制P-糖蛋白转运功能的活性。

P-糖蛋白与药物的结合体在体内的转化过程探讨

目的ATP结合盒转运载体蛋白作为影响药物体内过程的重要因素已被广泛研究,P-糖蛋白(P-gp)是其中最主要的一种转运子。P-gp的结构、特点及组织分布决定了其在药物的吸收、分布、代谢、排泄方面的重要作用。了解P-gp的这些作用有助于增加临床用药的合理性。经过近三十年的发展,虽然研究P-gp的方法已经较为成熟;但是,目前对转运子的研究仍有许多争议存在,还有很多问题需要解决。本文主要阐述P-gp的特性及其对药物体内过程的影响。

The Effect of Thoracic Operation on Glucose Transporter-4 mRNA Expression by Preoperative Infusion of Glucose

Objective: To investigate the changes in glucose transporter-4(Glut-4) mRNA expression in skeletal muscle before and after the thoracic operation and to observe the changes in Glut-4 mRNA expression by preoperative infusion of glucose. Methods: Twelve cases of elective thoracic operation were randomly divided into two groups, namely ordinary group Ⅰ and glucose infusion group Ⅱ. One gram of intercostal muscle was taken while thorax being opened and closed from patients under general anesthesia. Total RNA of the muscle cells was extracted by TRIzol one-step assay. Reverse transcription-competitive polymerase chain reaction (RT-PCR) was used to determine the Glut-4 mRNA amplification products with β-actin mRNA as an internal control. The Glut-4 mRNA expression was expressed by targeted gene /β-actin ×100%. The plasma glucose and insulin levels were determined at the same time.Results: Glut-4 mRNA expression was significantly reduced(P<0.05) and plasma glucose level increased (P<0.05), while thorax was being closed as compared with those while being opened. However, Glut-4 mRNA expression in glucose infusion group Ⅱ was significantly higher than ordinary group Ⅰ (P<0.01) and plasma glucose level in group Ⅱ was lower than group Ⅰ(P<0.05) when thorax was being closed. Conclusion: The results indicate that the synthesis of Glut-4 is suppressed by the surgical stress of thoracic operation under general anesthesia. We found that preoperative infusion glucose can increase Glut-4 mRNA expression at the same surgical stress and relieve postoperative insulin resistance.

Glut-4 is translocated to both caveolae and non-caveolar lipid rafts, but is partially internalized through caveolae in insulin-stimulated adipocytes

Caveolae and non-caveolar lipid rafts are two types of membrane lipid microdomains that play important roles in insulin-stimulated glucose uptake in adipocytes. In order to ascertain their specific functions in this process, caveolae were ablated by caveolin-1 RNA interference. In Cav-1 RNAi adipocytes, neither insulin-stimulated glucose uptake nor Glut-4 （glucose transporter 4） translocation to membrane lipid microdomains was affected by the ablation of caveolae. With a modified sucrose density gradient, caveolae and non-caveolar lipid rafts could be separated. In the wild-type 3T3- L l adipocytes, Glut-4 was found to be translocated into both caveolae and non-caveolar lipid rafts. However, in Cav1 RNAi adipocytes, Glut-4 was localized predominantly in non-caveolar lipid rafts. After the removal of insulin, caveolaelocalized Glut-4 was internalized faster than non-caveolar lipid raft-associated Glut-4. The internalization of Glut-4 from plasma membrane was significantly decreased in Cav-1 RNAi adipocytes. These results suggest that insulin-stimulated Glut-4 translocation and glucose uptake are caveolae-independent events. Caveolae play a role in the internalization of Glut-4 from plasma membrane after the removal of insulin.

^(18)F-fluoro-2-deoxyglucose uptake on PET CT and glucose transporter 1 expression in colorectal adenocarcinoma

AIM:To evaluate the correlation between the level of 18 F-fluoro-2-deoxyglucose (18 F-FDG) uptake and glucose transporter 1 (GLUT1) expression in colorectal adenocarcinoma (CRA).METHODS:Forty four patients with resected CRA and preoperative 18 F-FDG positron emission tomography computed tomography data were investigated in this study.Comparison of maximum standardized uptake value (SUVmax) of the lesion was made with GLUT1 expression by immunohistochemistry and various clinicopathologic factors including tumor volume,invasion depth,gross finding,and lymph node metastasis.RESULTS:SUVmax was 14.45 ± 7.0 in negative GLUT1 expression cases,15.51 ± 5.7 in weak GLUT1 expression cases,and 16.52 ± 6.8 in strong GLUT1 expression cases,and there was no correlation between between GLUT1 expression and SUVmax.SUVmax was significantly correlated with tumor volume (P < 0.001).However,there was no significant differences in SUVmax and GLUT1 expression among other clinicopathologic factors.CONCLUSION:GLUT1 expression does not correlates significantly with 18 F-FDG uptake in CRA.18 F-FDG uptake was increased with tumor volume,which is statistically significant.

Clinicopathologic significance of GLUT1 expression and its correlation with Apaf-1 in colorectal adenocarcinomas

AIM:To investigate the role of glucose transporter 1 (GLUT1) expression in colorectal carcinogenesis and evaluate the correlation with clinicopathological parameters and apoptosis-activating factor-1 (Apaf-1) expression in colorectal adenocarcinomas. METHODS:We used tissue microarrays consisting of 26 normal mucosa,50 adenomas,515 adenocarcinomas,and 127 metastatic lesions. Medical records were reviewed and clinicopathological analysis was performed. RESULTS:GLUT1 expression was absent in normal mucosa and low or moderately apparent in 19 cases (38.0%) of 50 adenomas. However,GLUT1 expression was detected in 423 (82.1%) of 515 adenocarcinomas and in 96 (75.6%) of 127 metastatic lesions. GLUT1 expression was significantly correlated with female gender (P = 0.009),non-mucinous tumor type (P = 0.045),poorer differentiation (P = 0.001),lymph node metastasis (P < 0.001),higher AJCC and Dukes stage (P < 0.001 and P < 0.001,respectively). There was a significant inverse correlation between GLUT1 expression and Apaf-1 expression (P = 0.001). In univariate survival analysis,patients with GLUT1 expression demonstrated poor overall survival and disease-free survival (P = 0.047 and P = 0.021,respectively,log-rank test). CONCLUSION:GLUT1 expression was frequently increased in adenocarcinomas and metastatic lesions. GLUT1 expression was significantly correlated with poorer clinicopathologic phenotypes and survival of patients with colorectal adenocarcinomas.

Olive oil consumption and non-alcoholic fatty liver disease

The clinical implications of non-alcoholic fatty liver diseases(NAFLD)derive from their potential to progress to fibrosis and cirrhosis.Inappropriate dietary fat intake,excessive intake of soft drinks,insulin resistance and increased oxidative stress results in increased free fatty acid delivery to the liver and increased hepatic triglyceride(TG)accumulation.An olive oil-rich diet decreases accumulation of TGs in the liver,improves postprandial TGs,glucose and glucagonlike peptide-1 responses in insulin-resistant subjects, and upregulates glucose transporter-2 expression in the liver.The principal mechanisms include:decreased nuclear factor-kappaB activation,decreased lowdensity lipoprotein oxidation,and improved insulin resistance by reduced production of inflammatory cytokines(tumor necrosis factor,interleukin-6)and improvement of jun N-terminal kinase-mediated phosphorylation of insulin receptor substrate-1.The beneficial effect of the Mediterranean diet is derived from monounsaturated fatty acids,mainly from olive oil.In this review,we describe the dietary sources of the monounsaturated fatty acids,the composition of olive oil,dietary fats and their relationship to insulin resistance and postprandial lipid and glucose responses in non-alcoholic steatohepatitis,clinical and experimental studies that assess the relationship between olive oil and NAFLD,and the mechanism by which olive oil ameliorates fatty liver,and we discuss future perspectives.

Hpyerglycemic Effect of a Mixture of Sea Cucumber and Cordyceps Sinensis in StreptozotocinInduced Diabetic Rat

Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber （Apostichopusjaponicas） and cordyceps sinensis （Cor-dyceps militaris） （SCC） in diabetic rat and explore the mechanism underlining such an effect. The diabetic model rat was induced with intraperitoneal injection of streptozotocin （STZ）. The diabetic model rats were randomly divided into control group （0.9% NaC1）, low dose group （300 mg SCC.（kg body weight）-1） and high dose group （1200 mg SCC （kg body weight）-l）. Sodium chloride and SCC were intragastrically administered once a day for 35 d. Changes in fasting serum glucose and serum insulin content, oral glucose tolerance and liver and muscle glycogen content were routinely evaluated. Pancreas tissue and β-cells of islets were observed under both optical and transmission electronic microscope, respectively. The abundance of glucose metabolism-relating genes in gastrocnemius and epididymal adipose tissue was determined with either reverse transcription PCR （RT-PCR） or western blotting. Results showed that SCC significantly decreased fasting serum glucose content, improved glucose tolerance and increased serum insulin and glycogen content; repaired STZ-injured β-cells of diabetic rat, and increased the expression of phosphatidylinositol 3 kinase （PI（3）K）, protein kinase B （PKB） and glucose transporter 4 （Glut4） encoding protein in both gastroenemius and adipose tissue, and Glut4 encoding gene in peripheral tissue. Our findings demonstrated that SCC exerted an anti-hyperglycemic effect by repairing β-cells and promoting insulin-mediated signal transduction pathway in insulin-sensitive gastrocnemius and adipose tissue.

Hepatic expression and cellular distribution of the glucose transporter family

Glucose and other carbohydrates are transported into cells using members of a family of integral membrane glucose transporter (GLUT) molecules. To date 14 members of this family, also called the solute carrier 2A proteins have been identified which are divided on the basis of transport characteristics and sequence similarities into several families (Classes 1 to 3). The expression of these different receptor subtypes varies between different species, tissues and cellular subtypes and each has differential sensitivities to stimuli such as insulin. The liver is a contributor to metabolic carbohydrate homeostasis and is a major site for synthesis, storage and redistribution of carbohydrates. Situations in which the balance of glucose homeostasis is upset such as diabetes or the metabolic syndrome can lead metabolic disturbances that drive chronic organ damage and failure, confirming the importance of understanding the molecular regulation of hepatic glucose homeostasis. There is a considerable literature describing the expression and function of receptors that regulate glucose uptake and release by hepatocytes, the most import cells in glucose regulation and glycogen storage. However there is less appreciation of the roles of GLUTs expressed by non parenchymal cell types within the liver, all of which require carbohydrate to function. A better understanding of the detailed cellular distribution of GLUTs in human liver tissue may shed light on mechanisms underlying disease pathogenesis. This review summarises the available literature on hepatocellular expression of GLUTs in health and disease and highlights areas where further investigation is required.

Pluronic L-81 ameliorates diabetic symptoms in db/db mice through transcriptional regulation of microsomal triglyceride transfer protein

AIM: To test whether oral L-81 treatment could im-prove the condition of mice with diabetes and to investigate how L-81 regulates microsomal triglyceride transfer protein (MTP) activity in the liver. METHODS: Genetically diabetic (db/db) mice were fed on chow supplemented with or without L-81 for 4 wk. The body weight, plasma glucose level, plasma lipid profile, and adipocyte volume of the db/db mice were assessed after treatment. Toxicity of L-81 was also evaluated. To understand the molecular mecha-nism, HepG2 cells were treated with L-81 and the effects on apolipoprotein B (apoB) secretion and mRNA level of the MTP gene were assessed.RESULTS: Treatment of db/db mice with L-81 sig-nificantly reduced and nearly normalized their body weight, hyperphagia and polydipsia. L-81 also markedly decreased the fasting plasma glucose level, improved glucose tolerance, and attenuated the elevated levels of plasma cholesterol and triglyceride. At the effective dosage, little toxicity was observed. Treatment of HepG2 cells with L-81 not only inhibited apoB secretion, but also signif icantly decreased the mRNA level of the MTP gene. Similar to the action of insulin, L-81 exerted its effect on the MTP promoter. CONCLUSION: L-81 represents a promising candidate in the development of a selective insulin-mimetic mol-ecule and an anti-diabetic agent.

Immunohistochemical Study of Hexose Transporters GLUT-2 and GLUT-5 in Birds Gastrointestinal Tract

The hexoses glucose, galactose and fructose serve as important dietary energy sources in animals and glucose plays a central role in energy homeostasis within eucaryotic cells. As relatively little is known about patterns of hexose transporters expression in birds gastrointestinal tract, the aim of the study was to examine glucose transporters 2 （GLUT-2） and glucose transporters 5 （GLUT-5） expression in stomach and duodenal epithelium of two different species--broilers （Gallus gallus domesticus） and ostriches （Struthio camelus var. domesticus） chicken. Materials from the two parts of gastrointestinal tract were collected from six 7-day-old female broilers and six 7-day-old female ostriches. Specimens were fixed with 10% formalin, embedded into paraffin, cut into 7 lain thick slices, followed by immunohistochemical staining with polyclonal primary antibodies rabbit anti-GLUT-2 and rabbit anti-GLUT-5; the staining was carried out according to the manufacturers guidelines （IHC kit, Abcam, UK）. The investigation showed that the staining for both antibodies was more intensive in the epithelial cells of stomach and duodenum of the 7-day-old broilers. In duodenal epithelium, goblet cells and brush border membranes were stained in both species, however the signal was stronger for GLUT-5 than GLUT-2. Staining for GLUT-2 and GLUT-5 occurred in different parts of gastrointestinal tract of 7-day-old ostriches, but was weaker compared to 7-day-old broilers, which showed that the gastrointestinal tract of 7-day-old female broilers was more developed for transportation ofhexoses than 7-day-old female ostriches.

Effect on glycemia in rats with type 2 diabetes induced by streptozotocin: low-frequency electro-pulse needling stimulated Weiwanxiashu(EX-B 3) and Zusanli(ST 36)

OBJECTIVE: To investigate the effect of low frequency electro-pulse acupuncture(EA) on blood glucose in rats with streptozotocin-induced type 2diabetes, and the possible mechanism underlying the action.METHODS: Rat models were established with high fat feeding and intraperitoneal injection of streptozotocin(STZ)(30 mg/kg). Rats with a random blood glucose > 16.7 mmol/L and blood glucose at 2 h-point of oral glucose tolerance test(OGTT) > 11.1 mmol/L were included as diabetic rats, and randomly divided into model group, EA Weiwanxiashu(EX-B 3) group, EA Zusanli(ST 36)group, glimepiride group, and EA non-acupoint group(n = 12). EA(2 Hz continuous wave, 2 m A,20 min/day, 6 days/week, 4 weeks) and intra-gastric administration of glimepiride were applied as interventions. With fasting blood glucose and OGTT tested at the end of the intervention, thestudy observed the patterns of hypoglycemic effects. For mechanism study, it observes hematoxylin and eosin staining and Masson staining of pancreas paraffin sections, protein expression of glucagon-like peptide 1 receptor(GLP-1R) in the pancreas and skeletal muscle, glucose transporter 4(GLUT4) protein expression in skeletal muscle membrane, to detect whether EA controls blood glucose via regulation of GLP-1R.RESULTS: EA Weiwanxiashu(EX-B 3) significantly increased model rats' pancreas GLP-1R, and GLUT4 of skeletal muscle membrane; the therapy significantly decreased model rats' skeletal muscle GLP-1R, restored pancreas morphology, and reduced fasting blood glucose and insulin resistance indices.CONCLUSION: EA Weiwanxiashu(EX-B 3) alone has significant effect on glycemia. EA Weiwanxiashu(EX-B 3) plus glimepiride further strengthen the effect. The regulation of the GLP-1R in pancreas and skeletal muscle might be mechanism underpinning the effect.

Effect of Yiqihuoxue prescription on myocardial energy metabolism after myocardial infarction via cross talk of liver kinase B1-depen-dent Notch1 and adenosine 5'-monophosphate-activated protein kinase

OBJECTIVE: To investigate the effect of Yiqihuoxue prescription(YQHX) from Traditional Chinese Medicine(TCM) on myocardial glucose and lipid metabolism after myocardial infarction via the cross talk between the liver kinase B1(LKB1)-dependent Notch1 and adenosine 5'-monophosphate(AMP)-activated protein kinase(AMPK). YQHX was prepared with substances with properties that benefit, to activate blood circulation based on the TCM theory.METHODS: Animal models of myocardial infarction were established by ligating Sprague Dawley rats' left anterior descending coronary arteries. The animals were randomly divided into a myocardial infarction(MI) group, a YQHX group, a perindopril group, a γ-secretase inhibitor, Notch signal inhibitor(DAPT) group, a DAPT+YQHX group and a sham group. The related drugs were administered on the second day after operation, and changes in the relevant indexes were examined on weeks 1 and 4.Changes in cardiac structure and function were examined by echocardiography. The glucose and free fatty acids(FFA) were examined by ELISA. The expression of Notch, LKB1 and AMPK m RNA was examined by a real-time fluorescence quantitative method. The expression of glucose transporter 4(GLUT4), and the expression of total acetyl-Co A carboxylase(ACC) and its phosphorylation were examined by western blotting.RESULTS: Compared with the sham group, the expression of Notch, LKB1 and AMPK m RNA in the MI group was lower. Compared with the MI group, the expression of these m RNAs in the YQHX and perindopril groups was higher, and their expression in the DAPT group was lower. At all time points, the protein expression of GLUT4 and p ACC decreased in the MI group. On week 1, the expression of p ACC protein was higher. In the DAPT group, the expression of p ACC protein decreased. Compared with the YQHX group, the expression of p ACC protein in the DAPT + YQHX group was lower. On week 4,compared with the MI group, the expression of GLUT4 protein in the YQHX group and the perindo-pril group was higher. The expression of GLUT4 protein in the DAPT group decreased. Compared with the YQHX group, the expression of GLUT4 protein in the DAPT+YQHX group was lower. There was no significant difference in the expression of ACC protein between the groups.CONCLUSION: YQHX promoted cross talk between the LKB1-dependent Notch1 and AMPK in myocardial tissue after myocardial infarction. Furthermore,it regulated the glucose and lipid metabolism of cardiomyocytes at different time points, thereby ameliorating the cardiac energy metabolism via different mechanisms and protecting the heart.

Canagliflozin,an inhibitor of sodium-glucose co-transporter 2,advances in the treatment of type 2 diabetes

Canagliflozin(CANA)is a sodium-glucose co-transporter 2 inhibitor.One of the important mechanisms of CANA is the inhibitory effect on the glucose uptake in the proximal tubule of the nephron,and the other mechanism can be the reduction of inflammatory cytokine expression monocytes and macrophages.It is proved by FDA for the management of type 2 diabetes.In the present work,we summarized the publication and clinical evidence of the CANA on healthy individuals and those with related metabolic diseases,such as type 1 and 2 diabetes,obesity,or cardiovascular and kidney diseases.This drug has been reported to offer potential advantages in regulating body weight and reducing heart failure,hypoglycemia,and stroke risk in patients with type 2 diabetes.Some in vitro and animal experiments also show that this drug has good effects on cancer treatment.However,some case reports and experiments also show the side effect of CANA,such as amputation,fracture,and pancreatitis,while the mechanism is still unknown.Overall,CANA has a good effect on the management of type 2 diabetes by reducing the risk of kidney failure,cardiovascular diseases,and stroke.However,as a new drug,more clinical trials and experiments of CANA should be carried out in the future.

Identification and function of glucose transporter 1 in human mesangial cells

Objective To evaluate the role of glucose transporter 1 (GLUT1) in the glucose uptake of glomerular mesangial cells.Methods Cultured human glomerular mesangial cells were used. The expressions of glucose transporter 1 mRNA and protein were detected with reverse transcription-polymerase chain reaction (RT-PCR), flow cytometry and immunofluorescence staining. Glucose uptake was determined with 2-deoxy-［3H］-D-glucose uptake assay.Results The expressions of GLUT1 mRNA and proteins were detected in human mesangial cells. Glucose uptake and its kinetics assay showed that GLUT1 is a functional glucose transporter in cultured human mesangial cells, and that its function could be inhibited by the specific inhibitor, Phloretin. Conclusion GLUT1 is the predominant glucose transporter in human mesangial cells, which has the kinetic characteristics of high affinity and low capacity for D-glucose. This suggests that in order for mesangial cells to take up excessive quantities of glucose, as in diabetes, changes in glucose transporter expression, translocation or activity may be required.