Biomedical subjects

Guangwei Li

Publications and source records attributed to Guangwei Li.

7 recordsLinked to original sources

PubMed2006

Efficient finite-element, Green's function approach for critical-dimension metrology of three-dimensional gratings on multilayer films.

We present an efficient method for calculating the reflectivity of three-dimensional gratings on multilayer films based on a finite-element, Green's function approach. Our method scales as NlogN, where N is the number of plane waves used in the expansion. Therefore, it is much more efficient than the commonly adopted rigorous-coupled-wave analysis (RCWA), which scales as N3. We demonstrate the effectiveness of this method by applying it to a two-dimensional periodic array of contact holes on a multilayer film. We find that our Green's function approach is about one order of magnitude faster than the RCWA approach when applied to typical contact holes considered in industry. For most cases, this method is efficient enough for application as a realtime, critical-dimension metrology tool.

Journal Article↗

PubMed2005

Predictors for erectile dysfunction among diabetics.

This study aims to examine the predictors related to erectile dysfunction (ED) among Chinese diabetics. From 1995 to 1999, 327 men with diabetes mellitus (DM) were enrolled into this study. They completed face to face interview, professional psychogenic assessment, measurements of penile hemodynamic parameters and measurements of hormone levels. Complications of diabetes were obtained from hospital medical records. One hundred and twenty nine diabetics were diagnosed as ED. The associations between individual predictor and ED were accessed using both univariate and multivariate logistic regression models. We found that the risk of ED was significantly associated with age (adjusted odd ratios (OR) = 1.16, 95% confident intervals (CI): 1.10-1.38), duration of DM (adjusted OR = 1.30, 95% CI: 1.28-1.87), lower physical activity (adjusted OR = 1.67, 95% CI: 1.15-3.03), retinopathy (adjusted OR = 1.15, 95% CI: 1.01-1.89), neuropathy (adjusted OR = 2.07, 95% CI: 1.54-3.06) and depression (adjusted OR = 1.46, 95% CI 1.32-2.56). The study shows that diabetics with ED suffer more serious complications than those patients with non-ED. ED may act as a sentinel event for underlying complications among male diabetics.

Adult↗

PubMed2004

[Present situation in the study of antisperm antibodies].

Immune factors account for 5%-15% of male infertility. Because of the diversity in molecular weight, structure and location, sperm antigens play different roles in immune infertility. Antisperm antibodies (AsAb) influence sperm function not only by direct action, but also by changing the local microenvironment indirectly. This paper reviews the progress in the studies of the implication of human sperm antigens, the function, mechanisms, categories and titer of AsAb in male infertility.

Antibodies↗

PubMed2002

[Impact of islet alpha cell loss on insulin secretion].

OBJECTIVE: To investigate the impact of islet alpha cell loss on insulin secretion. METHODS: Human pancreatic tissues underwent over-digestion of collagenase. Digestion was terminated in half of the tissue suspension, and half of the suspension was put into solution of collagenase to undergo over-digestion so as to cause loss of islet alpha cells. The tissues of digested human pancreas and over-digested human pancreas were fixed and immunohistochemical staining was made to observe the loss of islet alpha cells. The contents of insulin and glucagon in solutions of normal human pancreas, human islet of pancreas with normal enzyme secretion, and over-digested human islet were measured by radioimmunoassay. The ratios of insulin/glucagon in these three solutions were calculated so as to analyze the loss of alpha cells. Different human pancreatic tissues were inoculated in 24-well plate. Glucose solutions of different concentrations were added into the suspensions. The concentration of insulin in the supernatant was measured after incubation. C57/BL Normal human pancreas and human pancreas with islet alpha cell loss were transplanted into the renal capsules of two groups of 5 C57/BL mice with experimental diabetes mellitus respectively. The blood insulin was measured for two days. On the 3(rd) day, the left kidneys of the mice were taken to undergo insulin/glucagon immunohistochemical staining to observe the loss of alpha cells. Human islets with alpha cell loss were transplanted into the renal capsules of another 10 mice. Then 5 of them received injection of normal saline and the other 5 received glucagon for 7 days, then glucagon was injected into the mice of normal saline group, and vise versa. The blood sugar was measured every day. RESULTS: Glucagon immunohistochemistry showed alpha cell loss from islet periphery in over-digested human pancreas. The insulin/glucagons ratios were 100:2.34 and 100:2.05 in the normal pancreas and isolated normal islets respectively, and was 100:0.314 in the over-digested islets, showing a loss of > 80% of alpha cells. As compared with normal islets, glucose-induced insulin secretion was significantly decreased. The insulin concentration was 222.7 micro U/ml +/- 32.1 micro U/ml in the suspension of cultured normal pancreatic cells and was 124.6 micro U/ml +/- 12.6 micro U/ml in the supernatant of suspension of pancreatic islets with alpha cell loss (P < 0.01). The average blood sugar was 8.9 micro U/ml +/- 1.98 micro U/ml in mice grafted with normal islets and was 21.3 micro U/ml +/- 2.2 micro U/ml in mice grafted with alpha cell deficient islets (P < 0.01). However, insulin secretion in islets with alpha cell loss was significantly improved by exogenous glucagon in vitro and in vivo. CONCLUSION: The function of insulin secretion in islets with alpha cell loss is significantly decreased. Insulin secretion of islets with alpha cell loss can be improved by exogenous glucagon.

Animals↗

PubMed2002

Effects of insulin resistance and insulin secretion on the efficacy of interventions to retard development of type 2 diabetes mellitus: the DA Qing IGT and Diabetes Study.

OBJECTIVE: To investigate the effects of insulin resistance (IR) and insulin secretion (IS) on the development of diabetes mellitus in individuals with impaired glucose tolerance (IGT) who underwent lifestyle interventions. METHODS: 284 out of 577 individuals with IGT identified by population-based screening in Da Qing, China, who were randomized to undergo diet change and/or increased physical activity had baseline fasting and 2 h post-load insulin determinations. They were followed for 6 years for the development of diabetes. IR and IS were assessed using calculated indices based on fasting plasma insulin and glucose. The interactions of IR, IS, obesity and plasma glucose and the effects of the lifestyle interventions were evaluated using Cox Proportional Hazards analysis. RESULTS: Both IR and IS were significantly associated with the development of diabetes. Lifestyle interventions were more effective in those with lower IT and higher IS at baseline. Diet plus exercise interventions resulted in significantly lower incidence of diabetes, even after controlling for IR, IS, BMI and 2hrPG. CONCLUSION: Both IR and beta-cell function were predictors of diabetes in Chinese with IGT. Lifestyle intervention reduced the incidence of DM and these interventions were more effective in those with less IR.

Adult↗

PubMed2002

[Relationship between calpain-10 gene polymorphism, hypertension and plasma glucose].

OBJECTIVE: To detect the association among calpain-10(CAPN-10) gene polymorphism, hypentension and hyperglycemia. METHODS: 378 individuals in the present study were the second generation offsprings of 187 hypentensives and 19 1 nonhypertensives. Fasting plasma glucose (FPG), insulin, triglyceride and fibrinogen were determined. The polymorphism of UCSNP-43 and UCSNP-44 of CAPN 10 gene were analysed with PCR-SSCP method. RESULTS: (1)The frequency of G/G geno type of UCSNP-43 was higher in the second generation offsprings of the hypertensives than that in the nonhypertensive controls(86.6%, 75.4%, P < 0.05). (2) The frequenncy of G/G genotype of UCSNP-43 was higher in the hypertensive parents of the second generation offsprings in the hypertensive groups than that in the normotensive parent of the second generation offsprings of the nonhypertensive control groups (OR = 2.84, P = 0.01). After adjustment of age, sex and body mass index (BMI), the frequency of G/G genotype in the highest FPG-quartiles (FPG 5.42 +/- 0.1mmol/L) was much more than that in the lowest FPG quartiles (FPG 4.09 +/- 0.3 mmol/L) with OR of 3.32. CONCLUSIONS: Polymorphism of UCSNP-43 in CAPN-10 gene might be one of the genetic factors contributing to hypertension and diabetes mellitus in the population in Daqing city. It may be a predictor of type 2 diabetes mellitus (T2DM) in the decendents of hypertensives.

Adult↗

PubMed2002

[The efficacy and safety of pioglitazone hydrochloride in combination with sulphonylureas and metfomin in the treatment of type 2 diabetes mellitus a 12-week randomized multi-centres placebo-controlled parallel study].

OBJECTIVE: To evaluate the efficacy and safety of pioglitazone hydrochloride 30 mg/day with sulphonylureas and metfomin in the treatment of patients with type 2 diabetes mellitus. METHODS: There were 283 patients treated with sulphonylureas and metfomin randomized in this multicenter double-blind placebo-controlled clinical trial. Patients who had 7.0 mmol/L </= fasting plasma glucose(FPG) < 13.0 mmol/L were randomized to receive placebo or pioglitazone 30 mg once daily for 12 weeks. RESULTS: The patients who had been treated with pioglitazone 30 mg showed significant decrease on average from baseline in FPG(1.1 mmol/L versus 0.4 mmol/L, P < 0.001), postprandial plasma glucose(PPG,1.5 mmol/L versus 0.3 mmol/L, P < 0.001), and glycosylated hemoglobin (HbA1c, 0.7% versus 0.4%, P < 0.01). AS for fasting plasma insulin (FIns) levels decreased, significant difference was also observed in the two groups (P < 0.05). HOMA-IR had significant mean decrease in the pioglitazone group as compared with placebo group (P < 0.01). CONCLUSION: Pioglitazone 30 mg/day for 12 weeks might improve the metabolic control and the insulin sensitivity in poorly controlled type 2 diabetes with previous administration of sulphonylureas and metfomin. It provides a safety and tolerance profile for type 2 diabetes mellitus in this trial.

Blood Pressure↗