Metformin promotes irisin release from murine skeletal muscle independently of AMP-activated protein kinase activation.

AIM: Irisin, a novel myocyte-secreted hormone mediating beneficial effects of exercise on metabolism, is supposed to be an ideal therapeutic target for metabolic disorders such as obesity and diabetes. Here, we investigated the potential effects of metformin and glibenclamide, two antidiabetic medicines, on irisin release in mouse. METHODS: Wild-type and diabetic obese db/db mice were administrated with metformin and glibenclamide for 2 weeks, and cultured C2C12 myotubes were treated by metformin. Expression of irisin precursor FNDC5 was measured and blood irisin concentration was detected. AMP-activated protein kinase (AMPK) was blocked by chemical inhibitor compound C or knocking down with specific siRNA. RESULTS: The mRNA and protein expression of FNDC5 in skeletal muscle and blood irisin concentrations were lower in diabetic db/db mice than those in wild-type mice. Metformin and glibenclamide decreased blood glucose in db/db mice. Metformin, but not glibenclamide, increased intramuscular FNDC5 mRNA/protein expression and blood irisin levels. Additionally, the reductions of blood glucose and body weight in metformin-treated db/db mice were positively associated with blood irisin concentrations. In C2C12 myotubes, metformin upregulated intracellular FDNC5 mRNA/protein expression and promoted irisin release. Although metformin activated AMPK signalling in skeletal muscle cells, disrupting of AMPK signalling by chemical inhibitor or siRNA-mediated knockdown did not abolish the promoting effect of metformin on irisin release. CONCLUSION: Metformin promotes irisin release from murine skeletal muscle into blood, independently of AMPK pathway activation. Our results suggest that stimulation of irisin may be a novel molecular mechanism of metformin which is widely used for treatment of metabolic disorders.

Geographic variation in viral load among hepatitis B carriers with differing risks of hepatocellular carcinoma.

The risk of hepatocellular carcinoma (HCC) varies significantly among hepatitis B virus (HBV) carriers from different geographic regions. We compared serological markers of HBV infection in adult male carriers from Haimen City, China and Senegal, West Africa, where the prevalence of chronic infection is similar. HCC mortality among HBV carriers is much higher in Haimen City than it is in Senegal (age-standardized rate, 878 versus 68 per l0(5) person-years). A dramatic difference was observed when HBV DNA levels in serum were assessed among carriers by Southern blot. In the Senegalese group (n = 289), 14.5% were HBV DNA positive by Southern blot in their 20s, and this percentage declined in each subsequent decade of age to 3.3, 2.9, and 0% thereafter. In the Chinese group (n = 285), a higher prevalence of HBV DNA positivity and a less consistent reduction were seen; 29.4% were positive in their 20s, and 30.2, 23.6, and 20.6%, respectively, were positive in each subsequent decade of age. Among 102 male Asian-American HBV carriers, the prevalence of HBV DNA positivity was intermediate between the Chinese and Senegalese populations (36.8, 10.7, 3.0, and 4.6% in each subsequent decade of age). Viral titers were similar among those who were HBV DNA positive in all three populations [median value, 10(7) virions/ml (range, 10(6)-10(9) virions/ml)]. The presence of HBV DNA in serum was positively associated with serum glutathione S-transferase, a marker of liver damage. These findings suggest that the more prolonged maintenance of productive virus infection in the Chinese carriers compared with the Senegalese carriers may explain their higher risk of HCC. This profound difference in the natural history of chronic infection may be due to earlier age of infection in China or to as yet unknown environmental or genetic factors.

Threshold distributions of phenylthiocarbamide (PTC) in the Chinese population.

The ability to taste phenylthiocarbamide (PTC) is a well-documented Mendelian trait. Mapping and cloning the gene(s) responsible for the PTC tasting ability would help to delineate the molecular basis for the variations in PTC tasting ability in humans and to shed new light on taste chemosensory functions. In view of the spectacular successes in genome science, the positional cloning strategy seems to be a feasible approach to the isolation of the gene(s) underlying the PTC tasting ability. As a first step toward mapping the gene(s), we collected PTC taste threshold data on 106 individuals, most of them being university students, in Shanghai, China. Using various parametric and nonparametric statistical methods, we have found that the data set is best described by a bimodal distribution. The frequency of PTC nontasters is estimated to be 10%. This is consistent with the view that the PTC nontasting ability follows a recessive mode of inheritance. Several authors had previously reported PTC data on Chinese living outside China. Our data are, to our knowledge, the first ever collected from the Chinese population within China.

[An analysis of effects of fetal order and parental age on retinoblastoma].

78 cases of retinoblastoma (Rb) diagnosed at the Eye ENT Hospital, Shanghai from 1953 to 1985 were studied. The results of multiple Logistic regression analysis and conditional probability model showed that high fetal order had a moderate risk (OR = 1.28, P less than 0.05) of developing unilateral Rb. Both unilateral and bilateral cases were independent of parental ages, and no interaction could be found between fetal order and paternal or maternal age; also, the effect of fetal order was not confounded by paternal ages.

[Genetic epidemiology and a matched case-control study of bilateral breast cancer in Shanghai].

A matched case-control study on breast cancer was conducted in Shanghai from September 1990 to April 1992. Forty-six cases of bilateral breast cancer and 67 unilateral cases were studied. Results indicated that family history of breast cancer, personal history of benign breast diseases, high-level education, earlier menarche, and heavier body weight were the risk factors for breast cancer with conditional logistic regression analysis. Transmission of bilateral and unilateral breast cancer maybe conformed to Medellian recessive heredity model in simple segregation analysis, and all bilateral breast cancer, asynchronous bilateral breast cancer and asynchronous premenopausal bilateral breast cancer conformed to Medellian dominant heredity, and all unilateral breast cancer conformed to Medellian co-dominant heredity in complex segregation analysis.

The effect of adenosine on blood pressure variability in sinoaortic denervated rats is mediated by adenosine A2a-Receptor.

It is known that adenosine decreases blood pressure (BP) level as well as blood pressure variability (BPV). However, there is little information about the effect of adenosine on BPV. With a computerized analytic system for BP and heart rate (HR) that could sample the data continuously in conscious, freely moving rats, we studied the effects of different agonists and antagonists of adenosine receptors on BPV in sinoaortic denervated (SAD) rats. It was found that both adenosine and 5'-N-cyclopropyl-carboxamidoadenosine (CPCA, a selective adenosine A,-receptor agonist) decreased BPV. whereas N6-cyclopentyladenosine (CPA, a selective adenosine A1-receptor agonist) had no significant effect on BPV. When the rats were pretreated with theophylline (the nonselective adenosine-receptor antagonist), the inhibitory effects of adenosine as well as CPCA on BPV were abolished. Furthermore, it was found that 8-(3-chlorostyryl)caffeine (CSC, a selective adenosine A2a-receptor antagonist), also could prevent such an effect on BPV of CPCA. By itself, however, neither theophylline nor CSC had any influence on BPV. These results suggest that the effect of adenosine on BPV is mediated by adenosine A2a-receptor.

Blood pressure variability is increased in genetic hypertension and L-NAME -induced hypertension.

AIM: To examine whether the blood pressure variability (BPV) is increased in spontaneously hypertensive rats (SHR) and L-NAME-induced hypertensive rats (NHR). METHODS: BPV was recorded with continuous hemodynamic monitoring in conscious un restrained rats. Time course of L-NAME-induced hypertension was measured by the tail-cuff method. Plasma NO concentration was determined by the method of nitric acid reductase. RESULTS: In both SHR and NHR, systolic and diastolic BPV were significantly increased when compared with their respective controls. In S HR, in crease in diastolic BPV was predominant, whereas in NHR, increase in systolic BP V was predominant. Moreover, increase in systolic BPV in NHR (102 %) was obviously higher than that in SHR (28 %). Chronic administration of L-NAME 1 g/L in drink ing water caused a progressive increase in arterial blood pressure in rats. All rats were hypertensive at 4 weeks after treatment. Plasma NO level was decreased in NHR. CONCLUSION: Increased BPV is a general phenomenon in hypertension. NO is involved in the regulation of BPV.

[Anti-inflammatory effect of cyproheptadine].

Cyproheptadine, an anti-5-hydroxytryptamine drug, 20 mg/kg ip or 20-40 mg/kg ig markedly inhibited hind paw edema induced by injection of fresh egg white 0.1 ml or 2.5% formaldehyde 0.1 ml in rats. Cyproheptadine 20 mg/kg ip or 40-60 mg/kg ig inhibited hind paw edema produced by local injection of 0.15 ml 1% carrageenin in normal or adrenalectomized rats. It inhibited the proliferation of granuloma induced by cotton pellet after sc 20 mg/kg qd x 7d, the swelling of mouse ear induced by xylene, and the increased vascular permeability induced by 0.7% HAc in mice. Cyproheptadine did not prolong the survival time in adrenalectomized rats and there were no marked effects on adrenal weight or the plasma concentration of cortisol in rats. It decreased the weight of the thymus and the content of prostaglandin E in the inflammatory tissue of rats. These results suggest that the anti-inflammatory activity of cyproheptadine is presumably due to its anti-5-hydroxytryptamine effect and the inhibition of synthesis or release of prostaglandin E.

[Effects of trilobine on platelet aggregation, thromboxane A2, and prostacyclin formation in rats].

Using turbidimetry we found that trilobine inhibited ADP-induced platelet aggregation both in vitro and in vivo. Incubated with TrL 0.5, 0.75, and 1.0 mg.ml-1, platelet aggregation was inhibited by 38.2%, 68.2%, and 94.0% respectively. The inhibitory rates were 47.6% and 84.0% with TrL 20 and 40 mg.kg-1 ip respectively in vivo. The formation of platelet TXB2 was inhibited by 40% with TrL 20 mg.kg-1 ip in vivo, while the formation of carotid artery wall PGI2 was not affected. The production of TXA2-like substance was inhibited by 37%, 53%, and 78% with TrL 0.5, 1.0, and 2.0 mg.ml-1 respectively.

Complex segregation analysis of primary hepatocellular carcinoma in Chinese families: interaction of inherited susceptibility and hepatitis B viral infection.

Primary hepatocellular carcinoma (PHC) is extremely common in eastern China, where it is both associated with chronic infection with hepatitis B virus (HBV) and often familial. Complex segregation analysis of 490 extended families was undertaken with liability classes defined by age, sex, and HBV infection status. The maximum-likelihood model suggests that a recessive allele with population frequency approximately .25 yields lifetime risk of PHC, in the presence of both HBV infection and genetic susceptibility, of .84 for males and .46 for females. The model further predicts that, in the absence of genetic susceptibility, lifetime risk of PHC is .09 for HBV-infected males and .01 for HBV-infected females and that, regardless of genotype, it is virtually zero for uninfected persons. Complex segregation analysis therefore provides evidence for the interaction of genotype, environmental exposure, sex and age in determining the occurrence of PHC in this population.

Aerosol transmission of experimental rotavirus infection.

Several aspects of the epidemiology of rotavirus suggest the possibility that transmission may occur by nonenteral routes. We utilized the mouse model of rotavirus infection to investigate the experimental transmission of rotavirus infection by respiratory droplets. Following exposure to a defined dose of aerosolized rotavirus, the kinetics of viral replication within the lung and gastrointestinal tract was studied using a double antibody enzyme immunoassay and indirect immunofluorescence. These studies documented the efficient transmission of rotavirus infection by means of aerosol in all exposed animals. Rotavirus antigen was detected as early as 12 hours after infection in the pulmonary and gastrointestinal tracts of the infected animals and antigen remained detectable in both sites for at least 8 days following infection. Gastrointestinal illness was clearly demonstrable in the animals while pulmonary pathology was not evident. These studies document that rotavirus infection can be transmitted by aerosol droplets under experimental conditions.

Molecular and genetic epidemiology of hepatocellular carcinoma: studies in China and Senegal.

To identify environmental, viral, and genetic factors that may influence the risk of developing hepatocellular carcinoma (HCC), large prospective studies are being conducted in Haimen City, China and Senegal, and a case-control study of genetic variation in the detoxification of aflatoxin-B1 was carried out in Shanghai, China. Analysis of 78 HCCs that have occurred among 51,020 men enrolled in a large prospective study in Haimen City, China showed a strong association of HCC with chronic hepatitis B virus (HBV) infection. There were also significant associations of HCC risk with occupation (farming), history of a clinical episode of hepatitis in adulthood, and a family history of HCC. Study of 52 HCC cases and 116 controls for genetic polymorphisms and HCC risk showed a significant association with epoxide hydrolase (EPHX) mutant alleles (1/2, 2/2) and a borderline association with homozygous deletion of the glutathione-S-transferase mu (GSTM1) gene. There was a multiplicative interaction of these polymorphisms with chronic HBV infection such that HBsAg-positive persons who were GSTM1 null and were EPHX 1/2 or 2/2 had 135 times the risk of HCC as HBsAg-negative persons with the wild type genotypes for GSTM1 and EPHX. The risk of HCC is not uniform among persons with chronic HBV or HCV infections. Studies of genetic, viral, and environmental interactions may permit identification of those individuals at highest risk within groups at increased risk of HCC. Prevention strategies could then be targeted at those individuals.

Reduction of enteric infectious disease in rural China by providing deep-well tap water.

Enteric infectious disease (EID), defined here as bacillary dysentery, viral hepatitis A, El Tor cholera, or acute watery diarrhoea, is an important public health problem in most developing countries. This study assessed the impact on EID of providing deep-well tap water (DWTW) through household taps in rural China. For this purpose, we compared the incidence of EID in six study villages (population, 10,290) in Qidong County that had DWTW with that in six control villages (population 9397) that had only surface water. Both the bacterial counts and chemical properties of the DWTW met established hygiene standards for drinking water. The incidence of EID in the study region was 38.6% lower than in the control region; however, the introduction of DWTW supplies did not significantly affect the incidence of bacillary dysentery. These results indicate that the construction and use of DWTW systems with household taps is associated with decreased incidences of El Tor cholera, viral hepatitis A, and acute watery diarrhoea. Since high construction costs have led many authorities to question the value of DWTW, we carried out a cost-benefit analysis of the programme. The cost of constructing a DWTW system averaged US $36,000 at 1983 prices, or US $10.50 per capita. The combined capital and operating costs of a DWTW system were US $1.46 per capita per annum over its 20-year estimated life. The benefits derived from reductions in cost of illness and savings in time to fetch water were 2.2 times the costs at present values Capital outlays were recouped in a 3.6-year payback period and the provision of DWTW proved highly beneficial in both economic and social terms.

Low frequency of p53 mutations observed in a diverse collection of primary hepatocellular carcinomas.

Recent studies of the p53 tumor suppressor locus (designated TP53) in primary hepatocellular carcinoma (PHC) have identified a high frequency of codon 249 mutations. Due to the geographic location from which the samples were obtained and the substitution observed, the mutation was suggested to be attributable to aflatoxin B1 (AFB1) exposure. To determine the generality of this phenomenon, we have examined PHC tissues from 107 geographically and ethnically diverse sources. The frequency of p53 gene mutations was evaluated by using PCR/restriction-digest methods, GC-clamp (G+C-rich sequence) denaturing gradient gel electrophoresis, and DNA sequencing. The mutation rate observed in tumors from high-AFB1-exposure regions (25%) was more than double the rate observed in low-exposure regions (12%) but lower than the 50% frequency previously reported. Codon 249 mutations occurred at a much lower frequency than previously reported (2 of 107 samples examined). These results suggest that changes in DNA encoding p53 may not represent primary oncogenic effects but instead represent genetic changes related to tumor progression. High AFB1 levels may facilitate the generation of these progressional changes, but not by inducing a specific p53 gene mutation at codon 249 as previously reported.

Human hepatocellular carcinoma is characterized by a highly consistent pattern of genomic imbalances, including frequent loss of 16q23.1-24.1.

Comparative genomic hybridization (CGH) analysis was used to identify chromosomal imbalances in 52 human primary hepatocellular carcinomas (HCCs). The most prominent changes were gains of part or all of chromosome arms 8q (83% of cases) and 1q (73%) and loss of 16q (63%). Other commonly overrepresented sites were 5p, 7q, and Xq. Recurrent sites of DNA sequence amplification included 8q23--24 (five cases) and 11q13--14 (four cases). Other frequently underrepresented sites were 4q, 8p, 16p, and 17p. Taken collectively, these findings and data from other CGH studies of HCCs define a subset of chromosome segments that are consistently over- or underrepresented and highlight sites of putative oncogenes and tumor suppressor genes, respectively, involved in hepatocellular oncogenesis. Loss of heterozygosity analysis with a panel of polymorphic microsatellite markers distributed along 16q defined a minimal region of chromosomal loss at 16q23.1--24.1, suggesting that this region harbors a tumor suppressor gene whose loss/inactivation may contribute to the pathogenesis of many HCCs.