中国3个民族群体Y染色体上17个双等位基因位点的遗传分析

目的研究中国不同民族群体Y染色体的遗传多样性.方法采用PCR和等位基因特定PCR(ASPCR)的方法,对山东汉族、白族和土族共计76份男性DNA样本进行Y染色体上17个双等位基因位点的基因分型,确定每一个体的单倍型,统计3个群体各单倍型的频率分布,与国内其他群体的结果进行对比分析,并进行这些群体的主成分分析.结果有6个位点在3个群体中没有发现多态变异,YAP 在土族、白族和山东汉族中的分布分别为23.8%、6.7%和4%;3个群体共发现11种单倍型,山东汉族7种,土族8种,白族9种,主要单倍型频率集中在H1、H3、H5、H6、H8和H11.主成分分析结果显示白族与北方汉族相近,山东汉族与南方汉族等南方群体聚在一起,土族与彝族、回族和满族相近.结论山东汉族可能与一些南方群体有过基因交流,白族基因池中融入汉族基因流.中亚人群的基因流可能对东亚人群的遗传结构有过影响.     

Charcot-Marie-Tooth disease type 1A: a clinical, electrophysiological, pathological, and genetic study

Various clinical manifestations, electrophysiological findings, and sural nerve biopsies are reported in a Taiwanese family with type 1A Charcot-Marie-Tooth disease (CMT-1A). In addition, molecular genetic studies for duplication of the peripheral myelin protein 22 (PMP22) gene were also performed. There were 3 patients (2 men and 1 woman) with ages at onset ranging from 37 to 44 years. The onset of symptoms was insidious, and the neurological manifestations included distal muscle weakness and wasting, mild sensory loss, and hyporeflexia or areflexia. The severity of clinical manifestations varied from mild to severe, although with very prominent demyelinating polyneuropathy in electrophysiological studies. The sural nerve biopsy study revealed demyelination and an onion-bulb appearance. The molecular genetic studies confirmed duplication of the PMP22 gene in chromosome 17p11.2-12. We conclude that the clinical presentations, electrophysiological studies, and pathological studies as well as the molecular genetic analysis remain important in the clinical diagnosis of CMT-1A.     

Small bowel obstruction following low anterior resection: the impact of diversion ileostomy

Background The incidence of small bowel obstruction following rectal cancer surgery has not been well documented in the era of sphincter-preserving surgery. This report aimed to study the incidence, aetiologies and outcomes of small bowel obstruction in patients after low anterior resection for rectal cancer. The factors that might affect the incidences of small bowel obstruction were analysed.Methods Consecutive patients who had undergone low anterior resection for rectal cancer from August 1993 to March 1999 were studied. Patients with unplanned admissions, with the diagnosis of small bowel obstruction, were reviewed. The aetiologies and outcome of small bowel obstruction were documented.Results Two hundred and fourteen patients were included, with a median follow-up time of 39 months; 22 patients presented with 30 episodes of small bowel obstruction, and operations were necessary in nine patients (40.9%). Malignant obstruction occurred in two patients (10.3%). Obstruction within 6 weeks of surgery (including closure of stoma) occurred in 13 patients (6.1%). Early obstruction occurred at a higher incidence in those patients who had had an ileostomy than in those who did not (9.1% vs 2.9%, P=0.048).Conclusion Small bowel obstruction following rectal cancer surgery occurred in 10.3% of patients. The majority of the obstruction was benign in nature. The presence of diversion ileostomy was associated with an increased incidence of early obstruction, and the use of loop ileostomy for proximal diversion should be further assessed.     

Racial/ethnic disparities in preschool immunizations: United States, 1996-2001

OBJECTIVES: We examined current racial/ethnic differences in immunization coverage rates among US preschool children. METHODS: Using National Immunization Survey data from 1996 through 2001, we compared vaccination coverage rates between non-Hispanic White, non-Hispanic Black, Hispanic, and Asian preschool children. RESULTS: During the 6-year study period, the immunization coverage gap between White and Black children widened by an average of 1.1% each year, and the gap between White and Hispanic children widened by an average of 0.5% each year. The gap between White and Asian children narrowed by an average of 0.8% each year. CONCLUSIONS: Racial/ethnic disparities in preschool immunization coverage rates have increased significantly among some groups; critical improvements in identifying, understanding, and addressing race/ethnicity-specific health care differences are needed to achieve the Healthy People 2010 goal of eliminating disparities.     

Effects of beta-carotene on cell viability and antioxidant status of hepatocytes from chronically ethanol-fed rats

The purpose of the present study was to evaluate the effects of beta-carotene on the cell viability and antioxidant status of hepatocytes from chronically ethanol-fed rats. Rats in the ethanol group were given an ethanol-containing liquid diet that provided 36 % of total energy as ethanol, while rats in the control group were fed an isoenergetic diet without ethanol. After 4 weeks, hepatocytes were taken out and cultured for 24 h. Hepatocytes from the rats in the control and ethanol groups were cultured in medium without (HC, HE) or with beta-carotene (HC+B, HE+B). The results showed that lactate dehydrogenase leakage was significantly increased in the HE compared with that in the HC group. However, lactate dehydrogenase leakage of the HE+B group was similar to that of the HC group. When compared with the HC group, activities of glutathione peroxidase and catalase in the HE group were significantly decreased by 54 and 31 %, respectively. Catalase activity in the HE+B group was significantly increased by 61 % compared with that in the HE group. However, activities of glutathione reductase and superoxide dismutase showed no difference among the groups. The level of glutathione in the HC+B and HE+B groups was significantly increased to 155 and 143 % compared with those in the HC and HE groups, respectively. The concentration of lipid peroxides showed no difference among the groups. The present results demonstrate that beta-carotene improved the cell viability of hepatocytes, and increased catalase activities and glutathione levels in hepatocytes from chronically ethanol-fed rats.     

Tetrandrine, a bisbenzylisoquinoline alkaloid from Chinese herb Radix, augmented the hypnotic effect of pentobarbital through serotonergic system

This is the first study of hypnotic activity of tetrandrine (a major component of Stephania tetrandrae) in mice by using synergism with pentobarbital as an index for the hypnotic effect. The results showed that tetrandrine potentiated pentobarbital (45 mg/kg, i.p.)-induced hypnosis significantly by reducing sleep latency and increasing sleeping time in a dose-dependent manner, and this effect was potentiated by 5-hydroxytryptophan (5-HTP). In the subhypnotic dosage of pentobarbital (28 mg/kg, i.p.)-treated mice, tetrandrine (60 and 30 mg/kg, p.o.) significantly increased the rate of sleep onset and also showed synergic effect with 5-HTP. Pretreatment of p-chlorophenylalanine (PCPA, 300 mg/kg, s.c.), an inhibitor of tryptophan hydroxylase, significantly decreased pentobarbital-induced sleeping time and tetrandrine abolished this effect. From these results, it should be presumed that serotonergic system may be involved in the augmentative effect of tetrandrine on pentobarbital-induced sleep.     

A mechanistic study of cigarette smoke and cyclooxygenase-2 on proliferation of gastric cancer cells

Cigarette smoke has been shown to cause gastric cancer. Overexpression of cyclooxygenase-2 (COX-2) is a common characteristic in gastric malignancy. The present study aimed to explore the correlation between cigarette smoke and COX-2 in the promotion of tumorigenesis in human gastric cancer cells (AGS). We further studied the action of COX-2 on other proto-oncogenes on gastric tumor growth. Results showed that chloroform extract (CE) and ethanol extract (EE) from cigarette smoke dose-dependently stimulated gastric cancer cell proliferation, which was accompanied with an activation of ornithine decarboxylase (ODC) activity, COX-2, and c-myc expressions. Both antisense of c-myc and alpha-difluoromethylornithine (DFMO, specific ODC inhibitor) inhibited cell proliferation without affecting COX-2 expression in response to cigarette smoke extracts (CSE). However, selective COX-2 inhibitor (SC-236) not only blocked the proliferative activity but also the ODC activity and c-myc protein expression by CSE in gastric cancer cells. Further, supplementation of exogenous prostaglandin (PG) E(2) reversed all the inhibitory actions of SC-236. Our results underline the importance of COX-2 in the cancer-promoting effect of CSE and its modulation on its downstream growth-related genes, such as c-myc and ODC in cancer cell proliferation. These results reveal that CSE-induced gastric carcinogenesis is via the COX-2/c-myc/ODC and PGE(2)-dependent pathway. Hence, selective COX-2 inhibitor could be an effective therapeutic agent for gastric cancer in smokers.     

Constitutional activation of IL-6-mediated JAK/STAT pathway through hypermethylation of SOCS-1 in human gastric cancer cell line

The interleukin-mediated Janus kinase (JAK)/STAT pathway plays a crucial role in carcinogenesis. Recently, increased STAT3 activity was found in hepatocellular carcinoma and multiple myeloma in which there was silencing of SOCS-1 (suppressor of cytokine signalling-1) by gene promoter hypermethylation. We investigated the expression level of interleukin-6 (IL-6) and SOCS-1 in gastric cancer cell lines. Expression of SOCS-1 correlated with IL-6 level in most of the cell lines, except for AGS cells in which SOCS-1 was absent despite a high level of IL-6 production. Methylation analysis by methylation-specific polymerase chain reaction and bisulphite sequencing revealed that CpG island of SOCS-1 was densely methylated in AGS cells. Demethylation treatment by 5'aza-deoxycytidine restored SOCS-1 expression and also suppressed constitutive STAT3 phosphorylation in AGS cells. Moreover, methylation of SOCS-1 was detected in 27.5% (11 of 40) of primary gastric tumours samples, 10% (one of 10) of adjacent noncancer tissues but not in any (zero of nine) normal gastric mucosa. Methylation of SOCS-1 also correlated with the loss of mRNA expression in some primary gastric cancers. In conclusion, this is the first report to demonstrate that hypermethylation of SOCS-1 led to gene silencing in gastric cancer cell line and primary tumour samples. Downregulation of SOCS-1 cooperates with IL-6 in the activation of JAK/STAT pathway in gastric cancer.     

Bacteria-induced intestinal cancer in mice with disrupted Gpx1 and Gpx2 genes

Two glutathione peroxidase (GPX) isozymes, GPX-1 and GPX-2 (GPX-GI), are the major enzymes that reduce hydroperoxides in intestinal epithelium. We have previously demonstrated that targeted disruption of both the Gpx1 and Gpx2 genes (GPX-DKO) results in a high incidence of ileocolitis in mice raised under conventional conditions, which include the harboring of Helicobacter species [non-specific-pathogen-free (non-SPF) conditions]. In this study, we have characterized GPX-DKO mice that have microflora-associated intestinal cancers, which are correlated with increased intestinal pathology/inflammation. We found that GPX-DKO mice raised under germ-free conditions have virtually no pathology or tumors. After colonizing germ-free mice with commensal microflora without any known pathogens (SPF), <9% of GPX-DKO mice develop tumors in the ileum or the colon. However, about one-fourth of GPX-DKO mice raised under non-SPF conditions from birth or transferred from SPF conditions at weaning have predominantly ileal tumors. Nearly 30% of tumors are cancerous; most are invasive adenocarcinomas and a few signet-ring cell carcinomas. On the basis of these results, we conclude that GPX-DKO mice are highly susceptible to bacteria-associated inflammation and cancer. The sensitivity exhibited in these mice suggests that peroxidative stress plays an important role in ileal and colonic pathology and inflammation, which can lead to tumorigenesis.