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Biomedical subjects

Lian Zhang

Publications and source records attributed to Lian Zhang.

51 records · Page 3Linked to original sources
PubMed2003

Clinical and histological characteristics of chronic hepatitis B with negative hepatitis B e-antigen.

OBJECTIVE: To study the clinical and histological features of chronic hepatitis B (CHB) with negative hepatitis B e-antigen (HBeAg). METHODS: A total of 743 in-patients with chronic hepatitis B were recruited into the study and divided into two groups according to the HBeAg status. The correlation among alanine transaminase (ALT) levels, hepatitis B virus (HBV) DNA semiquantification, and the liver histopathological data were detected. RESULTS: Of the 743 successive in-patients, 267 (35.9%) were HBeAg-negative. The HBDAG-negative group had significantly lower serologic HBV DNA levels (63.0% of < 100 pg/ml) vs HBeAg-positive (42.6%, P < 0.001), while more sever inflammation (58.1% of inflammatory scores of histological activity index (HAIinf > or = 9) vs HBeAg-positive group (46.0%, P < 0.001) and severe fibrosis (45.3% of fibrosis scores of histological activity index (HAIfib > or = 3) vs HBeAg-positive group (27.9%, P < 0.001) of liver histology. In HBeAg-positive patients, increasing ALI levels were significantly associated with high inflammation and fibrosis scores and low HBV DNA levels. However, it was not the case in the HBeAg-negative cases. In HBeAg-positive patients, 91.3% of them had HAIinf > or = 9 and 65.7% had HAIfib > or = 3 with HBV DNA > 100 pg/ml, while 8.2% of them had HAIinf > or = 9 and 12.3% had HAIfib > or = 3 with HBV DNA < 20 pg/ml, indicating an obverse correlation between HBV DNA levels and histology scores. CONCLUSIONS: As regards clinical and histological background, the chronic HBeAg-negative hepatitis B is a different subpopulation from the HBeAg-positive counterpart.

DNA, Viral↗
PubMed2003

[Relation between single nucleotide polymorphism in estrogen-metabolizing genes COMT, CYP17 and breast cancer risk among Chinese women].

OBJECTIVE: To test the hypothesis whether polymorphism in estrogen-metabolizing genes, COMT and CYP17, impacts on the risk of breast cancer among Chinese women. METHODS: COMT (Val158Met) and CYP17 (T1931C) polymorphisms were detected by PCR-based restriction fragment length polymorphism analysis in 250 breast cancer patients and 250 frequency-matched normal controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression. RESULTS: COMT Met/Met genotype was found in 10.4% of breast cancer patients, which was significantly higher (P = 0.03) than that in controls (5.2%). Women with Met/Met genotype showed 2-fold increased risk for breast cancer (adjusted OR 2.1, 95% CI 1.1 - 4.5) compared with those with Val/Val or Val/Met genotypes. Stratified analysis showed that the elevated risk of breast cancer, associating with the COMT Met/Met genotype, was evident only among premenopausal women (adjusted OR 4.1, 95% CI 1.2 - 17.3) but not among postmenopausal women (adjusted OR 1.3, 95% CI 0.5 - 3.5). There was no significant difference in the distribution of CYP17 genotypes between breast cancer patients and the control subjects (P = 0.83). CONCLUSION: The allele encoding for low activity COMT, but not CYP17, may be a genetic risk factor for breast cancer among Chinese women.

Adult↗
PubMed2002

Correlation between a single nucleotide polymorphism in the matrix metalloproteinase-2 promoter and risk of lung cancer.

Matrix metalloproteinases (MMPs) play an important role in several steps of cancer development. A single nucleotide polymorphism (-1306C-->T) in the MMP2 promoter sequence disrupts an Sp1 site and thus results in strikingly lower promoter activity. We examined the relationship between this polymorphism and risk for lung cancer in 781 cases and 852 age- and sex-matched controls in a Chinese population. We found that the allele frequency of MMP2-1306C was significantly higher among cases than among controls (0.91 versus 0.83). Subjects with the CC genotype had an overall 2-fold increased risk for developing lung cancer [adjusted odds ratio (OR) 2.18; 95% confidence interval (CI), 1.70-2.79] compared with those with the CT or TT genotype. The elevated risk was observed evenly among different subtypes of this cancer. Stratified analysis indicated an additive interaction between the CC genotype and smoking on the elevated risk. The ORs of lung cancer for the CC genotype, smoking, and both factors combined were 2.38 (95% CI 1.64-3.45), 4.26 (95% CI 2.57-8.44), and 7.64 (95% CI 4.74-12.33), respectively. Furthermore, when the data were stratified by the pack-years smoked, this joint effect was more evident and stronger in heavy smokers (OR 10.25, 95% CI 5.80-18.09) than in light smokers (OR 5.55, 95% CI 3.34-9.22). These results demonstrate a significant association between the MMP2 -1306C/T polymorphism and risk of developing lung cancer solely or in a manner of interaction with carcinogen exposure.

Case-Control Studies↗
PubMed2002

[Detection and analysis of Helicobacter pylori in oral cavity and stomach from chronic gastritis patients].

OBJECTIVE: To investigate the prevalence of Helicobacter pylori (Hp) in the oral cavity of gastritis patients and analyze the genotype similarity of Hp in the oral cavity with that in the stomach. METHODS: A total of 384 plaque samples were collected from 32 patients with chronic gastritis and chronic periodontitis, one supragingival plaque sample and one subgingival plaque sample from one tooth, totally 6 teeth having been examined for one patient. Gastric biopsy specimens were collected by gastroscopy, four pieces of specimen for one patient, to undergo rapid urease test, histopathology, and Warthin-Starry silver staining. PCR assay was conducted on each specimen with primers based on the sequences of urease C gene and cag A gene specific to Hp to amplify the 294-bp and 400-bp DNA fragments. The identity of amplified products was confirmed by restriction endonuclease digestion. Two PCR positive products (Hp urease C gene 294 bp fragments) from the dental plaque samples and one gastric biopsy specimen from one of the four patients in the same family, totalling 12 specimens, were further examined by single-strand conformation polymorphism (SSCP). RESULTS: Twenty-seven patients (84.4 %) had at least one Hp positive dental plaque sample. In total, 113 (29.4%) of the 384 tested samples were urease C gene positive and 9 (2.3%) were positive for both urease C gene and cag A gene. The Hp positive rate was significantly higher in subgingival plaque (71/192, 37%) than in supragingival plaque (42/192, 21.9 %) (P < 0.01). The Hp positive rate in dental plaque was 57.1% (48/84) at the gingiva with the probing depth (PD) >/= 4 mm, significantly higher than that at the gingiva with the PD < 4 mm (34.3%, 37/108,P < 0.05). The Hp positive rate in the specimens of gastric mucosa was 96.7% (31/32). The Hp in the 12 dental plaque specimens and gastric biopsy specimens from the 4 patients in the same family had 3 banding patterns all together. One of the patients had at least one identical banding pattern in both the plaque specimens and gastric biopsy specimens. One specific banding pattern was found in the Hp from the dental plaques of all 4 patients. In one patient, the SSCP banding pattern in the Hp from dental plaque was inconsistent with that from gastric biopsy specimens. CONCLUSION: Hp exists in the oral cavity of gastritis patients. Oral Hp infection may be an important source of gastric Hp infection. Familial clustering and oral-oral transmission of Hp infection exist.

Adult↗
PubMed2002

Partition coefficients for the trihalomethanes among blood, urine, water, milk and air.

Chloroform, bromodichloromethane, chlorodibromomethane, and bromoform comprise the trihalomethanes, a group of widespread and mildly lipophilic compounds that result from water chlorination and other sources. Many animal studies show the chronic toxicity and carcinogenicity of these compounds, and recent work has demonstrated the importance of both ingestion and inhalation exposure pathways. This study presents partition coefficients describing the equilibrium among biological compartments (air, water, blood, milk, urine) for the four THMs based on results of headspace gas chromatographic analyses performed under equilibrium conditions and at 37 degrees C. The calculated partition coefficients ranged from 2.92 to 4.14 for blood/water, 1.54-2.85 for milk/blood, and 3.41-4.93 for blood/urine, with the lowest being chloroform and the highest being bromoform. Both human and cow milk were tested, with similar results. The available samples of human milk may not fully account for differences in lipid content and possibly other factors that affect estimates of partition coefficients. Simultaneous measurements of milk and blood in exposed individuals are suggested to confirm laboratory results. Partition coefficients are predicted using the octanol-air partition coefficient, also measured in this study, and the octanol-water partition coefficient. Results are similar to literature estimates for liquid/air partitioning of chloroform and chlorodibromomethane, but they differ from predictions based on hydrophobicity and lipid content. High correlations between the derived partitioned coefficients and the molecular structure (number of Br atoms) and physical properties (molecular weight and boiling point) are found for these analogous chemicals. In humans, THMs are both stored and metabolized with relatively rapid clearance rates. The derived partition coefficients can help to interpret results of biological monitoring and predict the potential for the accumulation and transfer of chemicals, specifically by the application of physiologically-based pharmacokinetic models. THM exposures to potentially susceptible populations, e.g. nursing infants, can be predicted using either such models.

Air↗
PubMed2002

Novel variants related to TT virus distributed widely in China.

TTV is a DNA virus with high genetic heterogeneity. To investigate the novel isolates of the virus, blood samples were collected from subjects who lived in various parts of China and suffered from hepatitis or were asymptomatic carriers. Nested PCR was carried out to amplify a 3.2-kb fragment using primers deduced from the prototype TTV (TA278). The ten entire 3.2-kb nt sequences were aligned with isolate TA278, SANBAN, TUS01, and SENV retrieved from GenBank, and a phylogenetic tree was constructed by Neighbor-Joining method. The analysis indicated that five novel variants of the present study have not been described before, and all TTV-related isolates could be classified into three groups. The isolate TCHN-A, B and TUS01 were included in a group, and the remaining novel isolates together with SANBAN and TA278 clustered into another group, while SEN virus formed a distinct group. The genetic distances of the five novel variants were 0.5507-0.8476 to TA278, 0.4635-0.7877 to SANBAN, 0.6064-0.7834 to TUS01 and 0.6936-0.8236 to SENV. Of these novel variants, the ORF1 consisted of 426-772 aa and ORF2 of 141-156 aa. The nt identities of ORF1 and ORF2 between those variants and TA278, SANBAN, and TUS01 were 46.1-60.8 and 48.7-63.6%, and those of aa sequences were only 27.1-52.4 and 28.9-45.5%, respectively. The first 65 aa of ORF1 were rich in arginine and most conserved with homology of 56.5-70.0%. There was a hypervariable region from aa 286 to 403 with merely 17.7-27.0% of identity. Despite a low aa identity between TA278 and the variants, they have similar hydrophilicity profiles of ORF1. There were 2-10 N-glycosylation motifs found in these variants. In conclusion, despite the high divergence, sequences of all these isolates shared common genome organisation, ORF structure, hydrophilicity patterns, and some potential motifs with TTV prototype. It is suggested that various TTV and TTV-related isolates belong to a very large and complex family, which remains to be studied.

Base Sequence↗
PubMed2002

Helicobacter pylori infection in rural China: demographic, lifestyle and environmental factors.

BACKGROUND: Although Helicobacter pylori is one of the most common human bacterial infections worldwide, its mode of transmission is unclear. METHODS: To investigate possible associations between H. pylori infection and demographic, lifestyle, and environmental factors in a rural Chinese population, a cross-sectional survey was administered to 3288 adults (1994 seropositive, 1019 seronegative, 275 indeterminate) from 13 villages in Linqu County, Shandong Province, China. RESULTS: Helicobacter pylori prevalence was elevated for: infrequent handwashing before meals (OR = 1.7, 95% CI: 1.0-3.0), crowding (i.e. sharing a bed with >2 people [OR = 2.3, 95% CI: 1.3-4.2]), washing/bathing in a pond or ditch (OR = 1.5, 95% CI: 1.0-2.4), and medium (OR = 1.6, 95% CI: 1.3-2.0) and low (OR = 2.3, 95% CI: 1.9-2.9) compared to high village education level, and reduced for never being married or divorced (OR = 0.4, 95% CI: 0.2-1.0). There was also a suggestion that source of drinking water, especially water from a shallow village well might be related to H. pylori seropositivity. There was no evidence of an association between H. pylori prevalence and alcohol or tobacco use, raw fruit and vegetable intake, or individual social class measures. CONCLUSIONS: The results of this study suggest that person-to-person transmission is the most plausible route of H. pylori infection in this rural Chinese population, but waterborne exposures deserve further investigation.

Adult↗
PubMed2002

Cocaine induction of dopamine transporter trafficking to the plasma membrane.

Several previous human postmortem experiments have detected an increase in striatal [(3)H]WIN 35428 binding to the dopamine transporter (DAT) in chronic cocaine users. However, animal experiments have found considerable variability in DAT radioligand binding levels in brain after cocaine administration, perhaps caused by length and dose of treatment and type of radioligand used. The present experiments tested the hypothesis that [(3)H]WIN 35428 binding and [(3)H]dopamine uptake would be increased by exposure to cocaine through alterations in DAT cellular trafficking, rather than increased protein synthesis. Experiments were conducted in stably hDAT-transfected N2A cells and assessed the dose response and time course of cocaine effects on [(3)H]WIN 35428 binding to the DAT, [(3)H]dopamine uptake, measures of DAT protein and mRNA, as well as DAT subcellular location. Cocaine doses of 10(-6) M caused statistically significant increases in [(3)H]WIN 35428 binding and [(3)H]dopamine uptake after 12 and 3 h, respectively. Despite these increases in DAT function, there was no change in DAT total protein or mRNA. Immunofluorescence and biotinylation experiments indicated that cocaine treatment induced increases in plasma membrane DAT immunoreactivity and intracellular decreases. The present model system may further our understanding of regulatory alterations in DAT radioligand binding and function caused by cocaine exposure.

Animals↗
PubMed2002

Rapid screening mitochondrial DNA mutation by using denaturing high-performance liquid chromatography.

AIM: To optimize conditions of DHPLC and analyze the effectiveness of various DNA polymerases on DHPLC resolution, and evaluate the sensitivity of DHPLC in the mutation screening of mitochondrial DNA (mtDNA). METHODS: Two fragments of 16s gene of mitochondrial DNA (one of them F2 is a mutant fragment) and an A3243G mutated fragment were used to analyze the UV detection limit and determine the minimum percentage of mutant PCR products for DHPLC and evaluate effects of DNA polymerases on resolution of DHPLC. Under the optimal conditions, we analyzed the mtDNA mutations from muscle tissues of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) and screened blindly for variances in D-loop region of mtDNA from human gastric tumor specimen. RESULTS: Ten A3243G variants were detected in 12 cases of MELAS, no alterations were detected in controls and these results were consistent with the results obtained by analysis of RFLP with ApaI. We also identified 26 D-loop variances in 46 cases of human gastric cancer tissues and 38 alterations in 13 gastric cancer cell lines. The mutation of mtDNA at 80 ng PCR products containing a minimum of 5% mutant sequences could be detected by using DHPLC with UV detector. Moreover, Ampli-Taq Gold polymerase was equally as good as the proofreading DNA polymerase (e.g., Pfu) in eliminating the false positive produced by Taq DNA polymerases. CONCLUSION: DHPLC is a powerful, rapid and sensitive mutation screening method for mtDNA. Proofreading DNA polymerase is more suitable for DHPLC analysis than Taq polymerase.

Case-Control Studies↗
PubMed2002

[Diagnostic value of ultrasonic examination in patients with different stages of liver fibrosis].

OBJECTIVE: To discuss the diagnostic value of ultrasonic examination in patients with early liver cirrhosis and the relation with different stages of liver fibrosis. METHODS: In the series, 263 patients with chronic hepatitis B were under taken liver biopsy and ultrasonic examination of type B for determination of liver cirrhosis images, width of the main portal vein and the splenic vein, tumefaction of the spleen. Data were analysed statistically. RESULTS: Sixties of 263 patients were diagnosed as early liver cirrhosis. The diagnostic sensitivity, specificity, misdiagnostic rate, missed diagnostic rate, and Jonden's index of ultrasonic examination for early liver cirrhosis were 52.5%, 88.3%, 11.7%, 47.5%, and 0.508, respectively. The width of the main portal vein with liver fibrosis of S1, S2, S3, and S4 were 10.93 mm +/- 1.25 mm, 11.35 mm +/- 1.06 mm,11.29 mm +/- 1.52 mm, and 11.4 8mm +/- 1.25 mm, respectively with statistic difference between S4 and S1 (P=0.03). The width of the spleen vein of S1, S2, S3, and S4 were 6.518 mm +/- 2.033 mm, 7.190 mm +/- 1.569 mm, 7.444 mm +/- 1.805 mm and 8.406 mm +/- 2.227 mm, respectively with statistic difference between S4 and S2 (P=0.035). The incidence of tumefaction of the spleen was increased with the degree of liver fibrosis. CONCLUSIONS: The diagnostic sensitivity of ultrasonic examination for early liver cirrhosis is low. The width of the main portal vein, the spleen vein and the incidence of tumefaction of the spleen are related with the degree of liver fibrosis. The regeneration node of liver cirrhosis may contribute to the development of portal hypertension.

Adolescent↗
PubMed2002

Serum antibodies to Helicobacter pylori and the CagA antigen do not explain differences in the prevalence of precancerous gastric lesions in two Chinese populations with contrasting gastric cancer rates.

Incidence and mortality rates for gastric cancer in rural People's Republic of China differ greatly over short distances. In Shandong Province, we studied asymptomatic adult subjects from Bei Duan village (n = 196) in Linqu County (a high-risk area for gastric cancer) and from Shi Huang village (n = 192) in Cangshan County (a low-risk area for gastric cancer). The prevalence of advanced precancerous gastric lesions (APGL) was assessed by microscopic examination of endoscopic stomach biopsies. ELISAs were used to detect serum IgG to Helicobacter pylori whole-cell antigen and to the CagA protein. A logistic regression model was used to quantify the role of the two H. pylori seromarkers in explaining the differences in prevalence of APGL between the two villages after adjusting for age and sex. The prevalence of APGL was much greater in Bei Duan than in Shi Huang. Although H. pylori seroprevalence by the whole-cell ELISA was similar in the two populations, seroprevalence of CagA was significantly greater in Bei Duan. Although age, sex, and both H. pylori seromarkers were associated with APGL in the logistic regression model, the effect of village of residence remained strong after adjustment for all four covariates. Only a relatively small proportion of the difference in prevalence of APGL between these two rural Chinese populations can be explained by differences in H. pylori or CagA seroprevalence.

Antibodies, Bacterial↗
PubMed2002

[Association of immune response to hepatitis B vaccine with HLA-DRB1*02, 07, 09 genes in the population of Han nationality in Guangdong Province].

OBJECTIVE: To study the association between immune response to hepatitis B vaccine and HLA-DRB1*02, 07, 09 genes in the population of Han nationality in Guangdong Province. METHODS: A total of 1 400 healthy college students of Han nationality from Guangdong Province were recruited in this study, who received standard courses of vaccination with recombinant hepatitis B virus vaccine at month 0, 1 and 6. Eight weeks after the final vaccination, the serum levels of anti-HBs antibody was examined with enzyme-linked immunosorbent assay (ELISA). Detection of HLA-DRB1*02, 07, 09 alleles were performed with PCR using sequence-specific primers in 118 individuals who failed to produce or produced insufficient antibodies (nonresponders or weak responders), 100 normal responders and 45 strong responders. RESULTS: The frequency of HLA-DRB1*07 in nonresponders or weak responders was significantly higher than that in normal or strong responders (15.25% vs 3.44%, P<0.05), while the frequency of HLA-DRB1*02 was much lower (5.08% vs 17.9%, P<0.05). The frequency of HLA-DRB1*09 showed no obvious difference between the 2 groups (19.49% vs 17.9%, P>0.05). CONCLUSION: Failure or deficiency in the response to HBV vaccine is associated with the HLA-DRB1*07 gene, while HLA-DRB1*02 gene is related to the normal vaccination process or overreaction. Definite relation of HLA-DRB1*09 to the response to HBV vaccine is not found.

Adult↗
PubMedDate not supplied

N-nitroso compounds and mutagens in Chinese fermented (sour) corn pancakes.

Stomach cancer rates in rural Linqu County, Shandong Province, China, are exceptionally high. A previous case-control study revealed that the risk of stomach cancer was 30% higher among those who consumed sour (fermented) corn pancakes at least daily. A previous study of the sour pancakes reported volatile nitrosamines in most specimens, and almost half reportedly showed mutagenic activity. Few households currently consume sour pancakes, and the duration of fermentation has been shortened. We tested specimens of pancake batter and sour pancakes from Linqu County for mutagenic activity using the Ames test; for N-nitroso compounds (NOC) we used the Nitrolite-thermal energy analysis (TEA) method. Results of the Ames test were inconclusive: only 1 out of 15 cooked pancakes showed a positive mutagenic response, and all 15 batter specimens were negative; however, several batter specimens showed a weakly positive trend of mutagenicity with extract concentration. Our assay for total nitroso compounds was weakly positive in only 1 out of 15 specimens of sour pancake batter. That specimen was also tested by gas chromatography-TEA for nitrosaminoacids and volatile nitrosamines, but none were detected. It seems unlikely that the Chinese sour pancakes are significantly contaminated by NOC or other mutagens.

Animals↗