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Articles by L. Zhang
Total Records ( 22 ) for L. Zhang
  K Chang , D Xiao , X Huang , L. D Longo and L. Zhang
 

Chronic hypoxia during pregnancy has profound effects on uterine artery (UA) contractility and attenuates uterine blood flow. The present study tested the hypothesis that chronic hypoxia inhibits the pregnancy-induced reduction in pressure-dependent myogenic tone of resistance-sized UAs. UAs were isolated from nonpregnant ewes (NPUAs) and near-term pregnant ewes (PUAs) that had been maintained at sea level (~300 m) or at high altitude (3,801 m) for 110 days. In normoxic animals, the pressure-dependent myogenic response was significantly attenuated in PUAs compared with NPUAs. Hypoxia significantly increased myogenic tone in PUAs and abolished its difference between PUAs and NPUAs. Consistently, there was a significant increase in PKC-mediated baseline Ca2+ sensitivity of PUAs in hypoxic animals. Hypoxia significantly increased phorbol 12,13-dibutyrate (PDBu)-induced contractions in PUAs but not in NPUAs. Whereas the inhibition of ERK1/2 by PD-98059 potentiated PDBu-mediated contractions of PUAs in normoxic animals, it failed to do so in hypoxic animals. Hypoxia decreased ERK1/2 expression in PUAs. PDBu induced membrane translocation of PKC- and PKC-. Whereas there were no significant differences in PKC- translocation among all groups, the translocation of PKC- was significantly enhanced in NPUAs compared with PUAs in normoxic animals, and hypoxia significantly increased PKC- translocation in PUAs. In the presence of PD-98059, there were no significant differences in PDBu-induced PKC- translocation among all groups. Treatment of PUAs isolated from normoxic animals with 10.5% O2 for 48 h ex vivo significantly increased PDBu-induced contractions and eliminated its difference between PUAs and NPUAs. The results suggest that hypoxia upregulates pressure-dependent myogenic tone through its direct effect in suppressing ERK1/2 activity and increasing the PKC signal pathway, leading to an increase in the Ca2+ sensitivity of the myogenic mechanism in the UA during pregnancy.

  X. SHI , P. ZHUANG , L. ZHANG , L. CHEN , B. XU , G. FENG and X. HUANG
  This study tested the hypothesis that different starvation time for fish before blood sampling can influence the result of plasma biochemical analysis. Glucose (GLU), total cholesterol (CHOL), triglyceride (TGL) and total protein (TP) in the plasma of juvenile Amur sturgeon (Acipenser schrenckii) were measured after different starvation duration (0, 0.5, 1, 2 and 3 days). Starvation time had a significant influence on plasma GLU, CHOL, TGL and TP concentrations (P < 0.05). Plasma GLU and TP concentrations were unpredictably variable with duration of starvation. Plasma TGL and CHOL concentrations after 3 days starvation were significantly higher than that in fish starved for 0, 0.5, or 1 day, and no significant difference was found among fish starved for 0, 0.5, or 1 day. In order to get baseline value for these blood parameters, juvenile Amur sturgeon should be starved for 1 day.
  R. Zang , J. Bai , H. Xu , L. Zhang , J. Yang , L. Yang , J. Lu and J. Wu
  Real-time quantitative PCR (qPCR) is the most accurate method of quantifying gene expression, provided that suitable endogenous controls are used to normalize the data. To date, no reference genes have been validated for development in Lanzhou fat-tailed sheep (Ovis aries). We have determined the expression profiles of 7 housekeeping genes as candidate reference genes (Actb, Ywhaz, Sdha, Gapdh, Tubb2, Pgk1 and 18S rRNA) in 7 developmental stages (1, 3, 5, 7, 9, 11 and 13 months of age) and 6 tissues (omental fat, liver, tail fat, thigh muscle, subcutaneous fat (backfat above 12th and 13th rib) and perirenal fat) in Lanzhou fat-tailed sheep. The software packages geNorm, NormFinder and BestKeeper were used to evaluate the stability of potential reference genes; each produced comparable results. Initial results showed several of the candidate genes exhibited stable expression throughout development while Actb was identified as the least stable gene. Further analysis with geNorm, NormFinder and BestKeeper identified Gapdh, Tubb2, Sdha and Ywhaz as acceptably stable in gene expression. Comparison of diacylglycerol O-acyltransferase 1 (Dgat1) expression data normalized with geometric averages obtained from combinations of either Gapdh, Sdha, Ywhaz or Tubb2, Sdha, Ywhaz showed no significant differences, indicating that these two combinations are similar. The data provided in this paper may also be useful in guiding researchers performing gene expression in other species of sheep.
  W. G. Gao , Y. H. Dong , Z. C. Pang , H. R. Nan , L. Zhang , S. J. Wang , J. Ren , F. Ning and Q. Qiao
  Aims: To determine the secular trend of prevalence of Type 2 diabetes and pre-diabetes in a Chinese population from 2001 to 2006.
Methods: Two consecutive population-based surveys for diabetes were conducted in a randomly selected population aged 35–74 years and living in Qingdao, China in 2001–2002 (n = 10854) and 2006 (n = 4416). All participants underwent standardized 2-h 75-g oral glucose tolerance tests (OGTTs), along with fasting capillary plasma glucose (FCG) tests in 2006. One urban community underwent OGTTs directly in 2002 (n = 1815), while a two-step screening strategy using FCG as a first-line screening test followed by OGTTs was used in 9039 individuals in 2001. Diabetes and pre-diabetes was defined according to the 2006 World Health Organization/International Diabetes Federation criteria.
Results: Based on the results of direct OGTTs, the age-standardized prevalence of diabetes and pre-diabetes in urban areas was 12.2 and 15.4% in 2002, whereas the prevalences were 18.8 and 28.7% in urban areas and 14.1 and 20.2% in rural areas in 2006 (P < 0.001, in urban areas). Using the two-step screening strategy, the prevalence of diabetes in 2001 was 10.1% in urban and 7.7% in rural areas and 13.8% in urban and 12.2% in rural areas in 2006 (P < 0.001). Based on the data of the 2006 survey, the two-step screening strategy missed 30.2% of diabetes cases when compared with the number defined by the direct OGTT approach.
Conclusions: Qingdao has experienced a marked increase in the prevalence of diabetes and pre-diabetes in the past 5 years. Intervention to prevent a further increase in the prevalence of diabetes is urgently required.
  F. Ning , Z. C. Pang , Y. H. Dong , W. G. Gao , H. R. Nan , S. J. Wang , L. Zhang , J. Ren , J. Tuomilehto , N. Hammar , K. Malmberg , S. W. Andersson and Q. Qiao
  Objective  To investigate the major risk factors and their association with the dramatic increase in the prevalence of diabetes from 2001-2002 to 2006 in Qingdao, China.

Methods  Population-based cross-sectional studies on diabetes were performed in 4598 men and 7026 women aged 35-74 years. The 2006 World Health Organization diagnostic criteria for diabetes were used.

Results  The crude prevalence of diabetes was 11.3% in both men and women in urban areas and 5.3% and 8.9% in rural areas in 2001-2002. This increased to 19.2% and 16.1% in urban areas and 14.2% and 13.8% in rural areas in 2006 for men and women, respectively. The increase in diabetes prevalence from 2001-2002 to 2006 was paralleled by an increased body mass index in rural areas but not in urban areas. The major risk factors associated with diabetes were age, family history of diabetes, obesity, hypertension and high triglycerides. The multivariate adjusted odds ratio and 95% confidence interval for diabetes corresponding to a one standard deviation increase in waist circumference was 1.81 (1.47, 2.23) in urban men, 1.64 (1.26, 2.13) in rural men, 1.98 (1.66, 2.37) in urban women and 2.02 (1.63, 2.51) in rural women. Low socio-economic classes had a higher risk for diabetes in urban areas but a lower risk in rural areas, both associated with increased waist circumference.

Conclusion  Established risk factors are of great importance for the prevalence of diabetes in the urban and rural Chinese populations and changes in these factors could explain the recent dramatic increase in diabetes prevalence, particularly in rural areas. Considering the high prevalence of obesity and physical inactivity, intervention is urgently required in China.

  W. G. Gao , Y. H. Dong , Z. C. Pang , H. R. Nan , S. J. Wang , J. Ren , L. Zhang , J. Tuomilehto and Q. Qiao
  Aims  A diabetes risk score for screening undiagnosed diabetes was constructed and validated in Chinese adults.

Methods  Two consecutive population-based diabetes surveys among Chinese adults aged 20-74 years were conducted in 2002 (n = 1986) and 2006 (n = 4336). Demographic and anthropometric measures were collected following similar procedures. Standard 2-h 75-g oral glucose tolerance tests (OGTTs) were performed to diagnose diabetes in both surveys. Fasting capillary plasma glucose (FCG) and glycated haemoglobin (HbA1c) were also measured together with the OGTTs on the same day of the 2006 survey. Beta coefficients estimated using logistic regression analysis derived from data of the 2002 survey were used to develop the risk assessment algorithm. The performance of the algorithm was validated in the study population of the 2006 survey.

Results  Of all the variables tested, waist circumference, age and family history of diabetes were significant predictors of diabetes and were used to construct the risk assessment score. The score, ranging from 3 to 32, performed well when applied to the study population of the 2006 survey. The area under the receiver operating characteristic curve was 67.3% (95% CI, 64.9-69.7%) for the score, while it was 76.3% (73.5-79.0%) for FCG alone and 67.8% (64.9-70.8%) for HbA1c alone. At a cut-off point of 14, the sensitivity and specificity of the risk score were 84.2% (81.0-87.5%) and 39.8% (38.2-41.3%).

Conclusions  The risk score based on age, waist circumference and family history of diabetes is efficient as a layperson-oriented diabetes screening tool for health promotion and for population-based screening programmes.

  L. Y. Qie , J. P. Sun , F. Ning , Z. C. Pang , W. G. Gao , J. Ren , H. R. Nan , L. Zhang and Q. Qiao
 

Aims

To study the cardiovascular disease risk profiles in newly diagnosed diabetes diagnosed by either glucose or/and HbA1c criteria in Chinese adults.

Methods

Two population-based cross-sectional studies were conducted in 2006 and 2009, respectively. Data from 1987 men and 2815 women aged 35-74 years were analysed. Newly diagnosed diabetes was defined according to either glucose (fasting and/or 2-h glucose), HbA1c or both criteria.

Results

Ageing, positive family history of diabetes, elevated levels of waist circumference, systolic blood pressure, total cholesterol, triglycerides and γ-glutamyl transferase were independently associated with newly diagnosed diabetes defined by glucose criterion alone, but not for diabetes defined by HbA1c criterion alone. Only waist circumference, total cholesterol and smoking were significantly associated with the presence of diabetes defined by HbA1c criterion alone.

Conclusions

Cardiovascular disease risk profiles were different in patients with newly diagnosed diabetes defined by the two diagnostic criteria for diabetes. This may have certain clinical implications on diabetes management and research.

  Y.J. Li , L. Zhang , L.Q. Shang , H.F. Wang , H. Zou , H. Zhang and D.J. Ji
  Using PCR-SSCP method, the relationship between genetic polymorphisms at three reproduction associated loci and litter size were explored in Chinese Haimen goat. The results showed that intron 1 of Prolactin Receptor (PRLR) gene had two genotypes and three genotypes were also found in intron 2 of the same gene while no polymorphism was detected in FSHR gene. The least square analysis and multiple comparisons of the polymorphisms at PRLR gene loci and litter size indicated that variations of PRLR gene intron 2 correlated extremely significantly with litter size in Haimen goat. These findings demonstrated that PRLR gene could be used as a candidate genetic marker for fecundity in goat.
  G.T. Cao , Y.P. Xiao , C.M. Yang , A.G. Chen , T.T. Liu , L. Zhou , L. Zhang and P.R. Ferket
  A total of 600, 1 day old male Lingnan Yellow broiler chickens were used to investigate the effects of Clostridium butyricum (C. butyricum) on growth performance, nitrogen metabolism, intestinal morphology and cecal microflora in broiler chickens. The birds were randomly assigned into 5 treatments (6 replicate pens per treatment with 20 birds per pen) and fed the same antibiotic-free basal diets during a 42 days feeding experiment. The treatments were as follows: no addition (Control), 2.5x107 cfu C. butyricum kg-1 of diet (CB1), 5x107 cfu C. butyricum kg-1 of diet (CB2), 1x108 cfu C. butyricum kg-1 of diet (CB3) and 10 mg colistine sulfate kg-1 of diet (Antibiotic). Compared with the control birds, birds fed either CB1 or CB2 or antibiotic diet had greater (p<0.05) Body Weight (BW) on day 21 and 42 and higher (p<0.05) Average Daily Gain (ADG) from day 1-42. Birds fed C. butyricum or antibiotic diet had lower (p<0.05) Feed-to-Gain ratio (F:G) than the control birds from day 1-42. Dietary C. butyricum decreased (p<0.05) the concentration of serum Uric Acid (UA) compared with the control diet on day 21. Supplementation with CB2 or CB3 decreased (p<0.05) serum ammonia concentration compared with the control diet on day 21 and 42. Birds fed C. butyricum diet had higher (p<0.05) ileal villus height than the control birds on day 21 and 42. Birds fed CB2 or CB3 diet had lower (p<0.05) ileal crypt depth than the control birds on day 21 and 42. Supplementation with CB1 or CB3 decreased (p<0.05) the population of cecal Escherichia coli (E. coli) compared with the control on day 21. Birds fed C. butyricum diet had higher (p<0.05) population of cecal Bifidobacterium on day 21 and birds fed CB2 diet had higher (p<0.05) cecal Bifidobacterium on day 42 compared with the control birds. Supplementation with CB1 or CB2 increased (p<0.05) the number of cecal Lactobacillus on day 21 and supplementation with CB2 increased (p<0.05) Lactobacillus on day 42 compared with the control or antibiotic groups. The results indicate that supplementation with C. butyricum promotes growth performance, modulates nitrogen metabolism improves intestinal morphology and balances cecal microflora in broiler chickens.
  L. Zhang , Y. Luo , J. Hu , J. Wang , X. Liu and H. Pan
  CAPNS1 also known as CAPN4, encodes the small subunit of CAPN1 and CAPN2 which is required to maintain stability and activity of both calpains. But to date polymorphism of yak CAPNS1 has not been reported. In this study, variation in the exon 6-intron 6 region of CAPNS1 was investigated in 1059 yaks and Chinese cattle by Polymerase Chain Reaction-Single Strand Conrmational Polymorphism (PCR-SSCP). Five PCR-SSCP patterns representing five allelic variations and containing four Single Nucleotide Polymorphisms (SNPs) in intron 6 were observed. Allele B was the most common allele with a frequency of 48.12% in yak and 93.29% in Chinese cattle whereas allele A and C were only in yak as well as allele D and E were rare (0.42 and 0.16%, respectively) and only in Chinese cattle. These results indicate that yak and cattle CAPNS1 is polymorphic and suggest further analysis is required to see if the variation detected affects their meat quality.
  X.X. Shi , Q.L. Yu , L. Han , J. CH. Tian , L. Zhang , Y.B. Zhang and Z.H.B. Guo
  An experiment was conducted to investigate the effects of post mortem ageing on the changes of meat quality characteristics and calpains activities of Gannan yak (Bos grunniens) meat. Twelve, 3 years old yaks (body weight, 230±10 kg) were used in this study and Longissimus dorsi muscle was removed from the carcasses immediately after slaughter and cut into chops with an average weight of 50 g, vacuum-packed into pouches, taken to the laboratory under refrigerated conditions. The samples were aged at 4°C for 0, 12, 24, 48, 72, 120, 168 and 192 h, respectively. The results indicated that the pH value of meat fell gradually to the minimum of 5.56 within the first 72 h (p<0.05) and the value did not change in the next 120 h. Water Holding Capacity (WHC) had a decreased trend in the first 72 h (p<0.05) but was s since. Tenderness of yak meat was improved in ageing days evaluated by Shear Force (SF) and Myofibril Fragmentation Index (MFI) (p<0.05). Hardness, springiness and chewiness were significantly decreased by analyzing the texture profile which reflected the progressive softness of the meat (p<0.05). Activity of μ-calpain was decreased continuously in first 72 h and activity of m-calpain was declined slightly only in first 12 h. However, activity of calpastatin was stable in first 72 h and then decreased gradually. The results demonstrated that the meat quality properties of yak meat were improved during ageing after postmortem and μ-calpain might be the main contributor of tenderization.
  B.P. Wang , D. Zhang , Y.Y. Liu , F. Wang , S.Y. Wang , L.D. Han , C.Y. Liu , C.X. Liu , J.P. Liu , J. Pan , W.B. Zhang , Tuo Ya , Zhaori Getu , Daolema , C.H. Huang , J.L. Han , Suya , L.G. Zhang , H.M. Zhou and L. Zhang
  The current study investigated the ovarian response to gonadotropin for establishing a suitable protocol of superovulation in Bactrian camel. Fifteen female camels were randomly divided into 4 groups to compare 4 different superovulation protocols during the natural breeding season. Each camel in 4 groups was injected with FSH at 80, 80, 60, 60, 60, 60, 40 and 40 mg, respectively total dosage of 480 mg, for consecutive 4 days at 12 h intervals. The camels in group 2-4 were naturally mated and subsequently injected 300 IU LH 48 h after the last injection of FSH, the camels in group 1 received the same procedure exception of LH injection. Ovarian follicles and corpora luteas were observed through synchronistic laparotomy 7-9 days after natural mating. The results indicated that there is no significant difference in average ovulation rate (p>0.05) among group 1-3 nor among group 2-4. However, there is considerable difference between group 1 and 4 in average ovulation rate (p<0.05), among which the value is highest (81.38±6.44%) for group 4 but lowest (16.89±7.98%) for group 1. Furthermore, the average number of follicles has yet no obvious difference (p>0.05) among group 1-3 nor among group 2-4 but significant difference (p<0.05) between group 1 and 4. Comparatively the animals in group 1 yielded highest average number of follicles (9.80±1.50). Conclusively, the protocol 4 had a best superovulatory effect with an average corpora lutea 9.33±1.45 and therefore it can be used for superovulation in camels.
  Y Yu , Y Li , L Li , J Lin , C Zheng and L. Zhang
 

Tubulin genes are intimately associated with cell division and cell elongation, which are central to plant secondary cell wall development. However, their roles in pollen tube polar growth remain elusive. Here, a TUA1 gene from Picea wilsonii, which is specifically expressed in pollen, was isolated. Semi-quantitative RT-PCR analysis showed that the amount of PwTUA1 transcript varied at each stage of growth of the pollen tube and was induced by calcium ions and boron. Transient expression analysis in P. wilsonii pollen indicated that PwTUA1 improved pollen germination and pollen tube growth. The pollen of transgenic Arabidopsis overexpressing PwTUA1 also showed a higher percentage of germination and faster growth than wild-type plants not only in optimal germination medium, but also in medium supplemented with elevated levels of exogenous calcium ions or boron. Immunofluorescence and electron microscopy showed -tubulin to be enriched and more vesicles accumulated in the apex region in germinating transgenic Arabidopsis pollen compared with wild-type plants. These results demonstrate that PwTUA1 up-regulated by calcium ions and boron contributes to pollen tube elongation by altering the distribution of -tubulin and regulating the deposition of pollen cell wall components during the process of tube growth. The possible role of PwTUA1 in microtubule dynamics and organization was discussed.

  L. Zhang , A.M. Elwazri , T. Zimmerly and M. Brochu
  The quantitative effects of surface finish on the mechanical behavior of flaw-free bulk nano-Ag samples consolidated by a dynamic process were studied. The results show that the samples possessing a surface roughness of 30 and 12 nm had a converted yield strength of 310 MPa, ultimate tensile strength of 320 MPa and ductility of 15%, while the samples possessing a surface roughness of 267 nm exhibited a brittle behavior and a reduction in strength of 35% in comparison to the smoother surfaces. Dimples were observed for the samples exhibiting plasticity, while an intergranular pattern was identified for the brittle materials.
  J. Cantizani , J. Ortiz , A. S. Ravipati , Lorena Rodriguez , B. Cautain , L. Zhang , N. Reddy , C. E. Nath , F. Vicente , N. de Pedro and S. R. Koyyalamudi
  Background: The aim of this study is screening Chinese medicinal plants for inhibitors of Glycogen synthase kinase-3 (GSK-3). GSK-3 is a proline/serine protein kinase ubiquitously expressed and involved in many cellular signalling pathways. GSK-3 has emerged as one of the most attractive therapeutic targets for the development of selective inhibitors as promising new drugs for numerous pathologies, including neurodegenerative diseases and type II diabetes. Thus, the use of GSK-3 inhibitors is one of the most promising therapeutic strategies for the future treatment of these potentially life threatening diseases. Materials and Methods: In the aim of discovery of potential inhibitors, 42 traditional Chinese medicinal plants were screened against GSK-3β which were selected based on their folklore use. The selected plant materials were extracted with ethanol and water. In vitro assay was carried out to evaluate the inhibition of human GSK-3β. The Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay was conducted with immortalized Hepatocyte cell line (Fa2N4) to evaluate the cytotoxicity of the plant material. Results: Many new ethanol and aqueous extracts showed significant inhibitory activity against GSK-3β with moderate or no cytotoxicity. Water extracts of Prunella vulgaris, Rabdosia rubescens and Sarcandra glabre have exhibited highest inhibition against GSK-3β. This in turn was supported by the fact that a good correlation exists between GSK-3β inhibitory activity and antioxidant content of the extracts. Conclusion: Considering the potent activity of P. vulgaris, R. rubescens and S. glabre, further isolation and characterization of individual bioactive compounds is recommended for the discovery of potent natural inhibitors of GSK-3β.
  Y Ding , L Jiao , W Zhang , L Zhou , X Zhang and L. Zhang
 

Sucrose is a convenient, common, tissue-equivalent material suitable for electron paramagnetic resonance (EPR) dosimetry of ionising radiation. A number of publications have reported on the dosimetric properties of sucrose and their use in radiation accident dose reconstruction. However, previous studies did not include specially the description of measurement methods of sucrose by EPR. The aim of this work is to introduce particularly the EPR measurement methods of sucrose. In this regard, practical considerations of sample size, microwave power, modulation amplitude, EPR spectrum and signal stability are discussed.

  E. X. N Li , D Livdan and L. Zhang
 

We take a simple q-theory model and ask how well it can explain external financing anomalies, both qualitatively and quantitatively. Our central insight is that optimal investment is an important driving force of these anomalies. The model simultaneously reproduces procyclical equity issuance waves, the negative relation between investment and average returns, long-term underperformance following equity issues, positive long-term drift following cash distributions, the mean-reverting operating performance of issuing and cash-distributing firms, and the failure of the CAPM in explaining the long-term stock-price drifts. However, the model cannot fully capture the magnitude of the positive drift following cash distributions observed in the data.

  W Huang , Q Liu , S. G Rhee and L. Zhang
 

The empirical evidence on the cross-sectional relation between idiosyncratic risk and expected stock returns is mixed. We demonstrate that the omission of the previous month's stock returns can lead to a negatively biased estimate of the relation. The magnitude of the omitted variable bias depends on the approach to estimating the conditional idiosyncratic volatility. Although a negative relation exists when the estimate is based on daily returns, it disappears after return reversals are controlled for. Return reversals can explain both the negative relation between value-weighted portfolio returns and idiosyncratic volatility and the insignificant relation between equal-weighted portfolio returns and idiosyncratic volatility. In contrast, there is a significantly positive relation between the conditional idiosyncratic volatility estimated from monthly data and expected returns. This relation remains robust after controlling for return reversals.

  C. Liu , X. Wang , Z. Chen , L. Zhang , Y. Wu and Y. Zhang
 

Background: The effects of hepatic ischemia-reperfusion (I/R) on insulin signaling remain unclear. We observed changes in insulin secretion and signal protein expression during the early steps in insulin signaling after hepatic I/R in rats.

Materials and Methods: Eighty healthy Wistar rats were randomly divided into an I/R group and a control (C) group. After we exposed the hepatic hilum, ischemia was induced by clamping the hepatic artery and portal vein for 30 minutes and then the liver was reperfused for 2 hours in the I/R group; a show procedure was done in the C group. Blood samples were obtained after exposure of the hepatic hilum (T1) and 2 hours after reperfusion in the I/R group (T2) and 2.5 hours after T1 in the C group (T2). We measured glucose and insulin plasma concentrations. We determined the expressions of insulin signaling proteins, including insulin receptor (IR) β unit (IR β), IR substrate 1 (IRS-1), IRS-2, and P85 in phosphatidylinositol 3-kinase (PI3K) and tyrosine phosphorylation of these proteins in liver and skeletal muscle.

Results: Plasma glucose concentrations increased in both groups at T2 (P < .01) and were higher in the I/R group (P < .01). Insulin concentrations in the I/R group did not change significantly at T2. Insulin concentrations at T2 were higher than those at T1 in the C group (P < .05). Expressions of insulin signal proteins showed no significant difference between the 2 groups; however, tyrosine phosphorylation of IR β, IRS-1, IRS-2, and the interactions between IRS-1 in skeletal muscle or IRS-2 in liver and PI3K were significantly lower in the I/R group than the C group.

Conclusion: Hepatic I/R inhibited insulin secretion and induced insulin resistance via down-regulation during the early steps in insulin signaling in rats.
 
 
 
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