Biomedical subjects

Yi Zhao

Publications and source records attributed to Yi Zhao.

95 records · Page 6Linked to original sources

PubMed2002

Novel sustained-release implant of herb extract using chitosan.

Chitosan (CS), a naturally occurring high-molecule polymer, which is stable in vivo, has proved to be a useful biomaterial. The extract of danshen (Radix Salviae miltiorrhizae), a medicinal herbal, was developed with CS-gelatin as an implant for the promotion of anastomosing and healing on muscles and tissues at the organic incision site in abdominal cavities. Measurements were made of the sustained release of tanshinone IIa, a marker component, from the material in vitro. The dissolution medium was assayed with an high-performance liquid chromatography method. Biodegradation studies of the material were also conducted both in vitro and in vivo. The film made of this material exhibited a sustained release effect. The release profile confirms to the Higuchi equation. At most about 20% of the incorporated drug were released over 15 days in a CS-gelatin (1:2) matrix. Drug release was found to be effectively controlled by the drug-amount loaded in the matrix. The improved film (CS/gelatin ratio: 1:16) can be hydrolyzed by lysozymes in vitro in 4 days. This film of 0.5 cm2 was implanted and degraded completely in rats over 28 days and the animals' wounds of abdominal incision healed well.

Abietanes↗

PubMed2002

Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody.

AIMS: This study aims to examine the genomic variants of the 'a' epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). METHODS: Eighteen HBV carriers were studied. Hepatitis B virus (HBV) DNA was extracted and the 'a' epitope region was amplified and sequenced. RESULTS: Eighteen Chinese asymptomatic HBV carriers were studied. There were 13 patients who were positive for both HBsAg and anti-HBs. Of these, one patient had only wild-type HBV, three had a viral mixture, and five had only 'a' epitope variant HBV. Of the three patients with a viral mixture, all had variants in the less conserved region (123-137). Of the five patients with pure HBsAg mutants, three had variants in the less conserved region while two had variants in the highly conserved region. In this study with a limited number of patients, the serum alanine aminotransferase (ALT) levels were higher in patients with wild-type HBV, compared with those with either 'a' epitope variants or a viral mixture consisting of wild type and variants. CONCLUSION: Eight of the nine (89%) patients positive for both HBsAg and anti-HBs harbored an 'a' epitope variant. The lower ALT levels seen in patients who had either pure 'a' epitope variant or a mixture of wild type and mutants suggest that a closer monitoring of these 'a' epitope variants should be required, as patients carrying these infectious viral strains may remain asymptomatic.

Adult↗

PubMed2002

Helicobacter pylori infection is unlikely to be transmitted between partners: evidence from genotypic study in partners of infected patients.

INTRODUCTION: We postulated that the oro-oral route of transmission between spouses could be an important route of transmission of Helicobacter pylori. AIMS: To estimate the prevalence of different genotypes of H. pylori as distinguished by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in our local population, and to compare the genotypes of H. pylori isolated from patients and their spouses. METHODS: Gastric biopsies were obtained from 183 dyspeptic patients during endoscopy. PCR for H. pylori was carried out using the uceC gene for amplification, and PCR products were digested further for RFLP analysis using the enzyme MboI. Spouses of H. pylori-positive index cases were screened for the infection using serological testing; if found to be positive serologically, endoscopy and gastric biopsies were performed for genotypic study of the micro-organism. For couples with indistinguishable H. pylori strain on RFLP with restriction endonuclease MboI, the process of RFLP was repeated with digestion of the PCR products using restriction endonuclease HhaI. RESULTS: We established our PCR technique to be 89.5% sensitive and 95.5% specific. Eighty-nine subjects were found to be H. pylori positive by PCR, and eight different genotypic strains were found according to our RFLP analysis. Two genotypes accounted for 80.8% of the cases. Sixteen of 31 spouses tested serologically for H. pylori were positive. All 13 spouses who agreed to undergo endoscopy were PCR positive for H. pylori. Five couples shared indistinguishable H. pylori genotypes, but this strain was also the commonest genotype in our local population, as based on RFLP with restriction endonuclease MboI. Further RFLP on the PCR products on these five couples using restriction endonucleases HhaI showed that the H. pylori isolated from these five couples were of different strains. CONCLUSION: The oro-oral route of transmission between spouses is unlikely to be an important mode for H. pylori infection.

Adult↗

PubMed2002

[Expression and clinical significance of MAGE-4 gene in human hepatocellular carcinoma].

OBJECTIVE: To explore the possibility of MAGE-4 gene encoding protein used as a target for immunotherapy in HCC patients. METHODS: The expression of MAGE-4 gene in tumor tissues and tumor adjacent non-HCC liver tissues was examined by the RT-PCR method. The relationship between positive expression rate of MAGE-4 gene and other clinical and lab data including AFP, AFU, anti-HCV, HBsAg, AFP mRNA, and the diameter of the tumors in HCC patients was also determined. RESULTS: The positive expression rate of MAGE-4 gene was significantly higher in the tumor than in tumor surrounding tissues (38.7% vs 0%, P<0.01), while the positive expression rate of MAGE-4 gene had no relationship with the clinical and lab data (P>0.05). CONCLUSIONS: The high frequency of MAGE-4 gene expression in HCC suggests the possibility of MAGE-4 gene encoding protein as a target for immunotherapy in HCC patients, but the expression has no relationship with the tumor metastasis and the recurrence of HCC.

Antigens, Neoplasm↗

PubMed2002

[The anticancer effect of artesunate and its mechanism].

AIM: To study the anticancer effect of artesunate and its mechanism. METHODS: To observe the effect of artesunate on the growth of solid tumor and the expression of PCNA, Bcl-2 and Bax genes in mice bearing H22 solid hepatic carcinoma. RESULTS: After administration of artesunate (ig, 300 mg.kg-1.d-1 x 7 d), growth of solid tumor was obviously inhibited, the tumor inhibitory rates were 49.1%, 48.7% and 46.6% and 46.6% in 3 experiments. The apoptosis of liver cancer cells were increased. Immunohistochemical staining showed that the number of Bcl-2 protein positive cells were decreased, but the number of Bax protein positive cells were increased. The PCNA positive cells were significantly lower than those in the control group. CONCLUSION: Artesunate showed obvious anticancer activity on H22 hepatic carcinoma bearing mice and undergo apoptosis of liver cancer cells. The mechanism of anticancer effect of artesunate may be related to down-regulation of the expression of PCNA and Bcl-2 genes and up-regulation of the expression of Bax gene.

Animals↗