Biomedical subjects

X Zeng

Publications and source records attributed to X Zeng.

At least 109 records · Page 6Linked to original sources

PubMed1999

MDM2 oncogene as a target for cancer therapy: An antisense approach.

The MDM2 oncogene is amplified or overexpressed in human cancers. It has also been suggested that MDM2 levels are associated with poor prognosis of several human cancers. The MDM2 oncoprotein binds to the p53 tumor suppressor protein and serves as a negative regulator of p53. The p53 tumor suppressor also has an important role in cancer therapy, with p53-mediated apoptosis being a major mechanism of action for many clinically used cancer chemotherapeutic agents and radiation therapy. Therefore, the negative regulation of p53 by MDM2 may limit the magnitude of p53 activation by DNA damaging agents, thereby limiting their therapeutic effectiveness. The investigators hypothesize that, by inhibiting MDM2 expression, the MDM2 oncoprotein level will be reduced and the MDM2 negative feedback inhibition of p53 will be diminished, resulting in a significant increase of functional p53 levels that will modulate p53-mediated therapeutic effects. The overall objective of the present study was to investigate the functions of MDM2 oncogene in tumor growth and the potential value of MDM2 as a drug target for cancer therapy. The role of MDM2 in tumor growth is determined by inhibiting MDM2 expression in in vivo models of human cancers. The in vivo synergistically therapeutic effects of MDM2 inhibition and DNA damaging agents were also evaluated. Significant in vitro antitumor activities were found in cell lines, human osteosarcoma SJSA and choriocarcinoma JAR, in a time-, concentration-, and sequence-dependent manner. Following i.p. administration of anti-MDM2 antisense oligonucleotides, in vivo antitumor activity was observed in nude mice bearing SJSA and JAR xenografts in a dose-dependent manner. Moreover, in vivo synergistically therapeutic effects of MDM2 inhibition and DNA damaging agents adriamycin and 10-hydroxycamptothecin were observed. This study should provide the basis for future development of anti-MDM2 antisense oligonucleotides as cancer therapeutic agents used alone or in combination with conventional chemotherapeutics.

Animals↗

PubMed1999

Discernment of the sensitized inner ear by peripheral immunocompetent lymphocytes.

OBJECTIVE: To investigate the role of peripheral immunocompetent lymphocytes during the immune response in the inner ear. METHODS: Sensitized lymphocytes from peripheral blood, neck lymph nodes and spleen of three groups of donor animals, i.e., group A immunized intradermally with keyhole limpet hemocyanine (KLH) and both inner ears challenged with KLH, group B received only KLH intradermally without inner ear challenge, and group C used as control, were isolated and labelled with 51Cr. The labelled lymphocytes were injected intravenously into the recipients. They were immunized intradermally with right inner ears challenged with KLH. Twenty to 24 h later, the radioactivities in the temporal bones of the recipients were assayed to detect the infiltration of labelled cells. RESULTS: In groups A and B, the radioactivity in the right temporal bones was higher than that in the left temporal bones (P < 0.05). The highest labelling radioactivity was detected in the right temporal bones of group A. The lowest migration of 51Cr-labelled cells to the inner ear was found in group C. The ratio of radioactivity between right (challenged) and left (unchallenged) inner ears was higher in group A than in groups B and C, with the difference being significant (P < 0.05). CONCLUSION: The immune reaction in response to antigenic stimulation in the inner ear is immunologically modulated by the peripheral systemic circulation.

Adjuvants, Immunologic↗

PubMed1999

[Magnetic resonance imaging in dental appliance treatment of obstructive sleep apnea syndrome].

OBJECTIVE: To investigate the upper airway changes after wearing dental appliance in obstructive sleep apnea syndrome(OSAS). METHODS: The research included 11 aged OSAS patients and 11 matched controls. Through dental appliance therapy the OSAS was proved by polysomnography to have ideal treatment results (AHI had decreased from 44.6 +/- 22.5 per hour to 7.53 +/- 6.44 per hour). Magnetic resonance imaging (MRI) had been performed before and after wearing dental appliance. The MRI images of upper airway after wearing dental appliance were compared with those of without wearing, and even with those of the controls. RESULTS: After wearing dental appliance the size of upper airway increased greatly, from 12.27 ml +/- 4.13 ml to 13.93 ml +/- 4.58 ml(P < 0.01), While the size of oropharynx was increased from 5.55 ml +/- 2.10 ml to 6.88 ml +/- 2.26 ml (P < 0.001). There was still remained significant difference at nasopharynx, soft palate and tongue compared with the matched controls. CONCLUSION: Dental appliance worked with the effect of enlarging upper airway. The abnormal airway morphology can not be changed completely by dental appliance treatment. MRI technique, especially the 3-D reconstruction model of upper airway, is an effective and special method in OSAS research.

Adult↗

PubMed1999

[Comparison of closing T loop technique and sliding technique using preadjusted appliance].

OBJECTIVE: To compare the difference between closing T loop technique and sliding technique. In anchorage demand and treatment outcome. METHODS: Sixteen first premolar extraction cases were chosen and divided into two groups for prospective paired t-test. They were treated by one author using 0.022" x 0.028" preadjusted appliances. T loops were fabricated using 0.018" x 0.025" s.s. wire. Chinese NiTi coil springs and 0.019" x 0.025" s.s. arch wire were employed in sliding technique group. Treatment materials, steps and appliance design in both groups were standardized. Measurements of dental model and cephalogram were taken. RESULTS: In closing T loop technique group and sliding technique group, the ratio of anterior teeth movement was 0.55 and 0.53 respectively. The difference was not significant (P > 0.05). L1MP angle decreased by 5.7 degrees and 3.1 degrees respectively during treatment (P < 0.05). CONCLUSION: Demand on anchorage was not significantly different between two groups. Sliding technique was more favorable in maintaining anterior teeth inclination.

Adolescent↗

PubMed1999

[Synthetic assessment of health impact of cerebrovascular diseases on potential health days of life lost].

OBJECTIVE: To assess synthetically the impact on population health caused by cerebrovascular diseases. METHODS: Incidence, duration of disease, disabilities and deaths of cerebrovascular diseases were analyzed with potential health days of life lost (PHDLL) as an indicator in urban areas of Changsha, Hunan Province. RESULTS: The PHDLL caused by cerebrovascular disease totaled 2 624.94 days per thousand of population, 33.01% of them attributed to deaths and 53.44% to chronic disability. CONCLUSION: Hemorrhagic cerebrovascular disease mainly lead to death and ischemic one caused chronic disability.

Adolescent↗

PubMed1999

[Studies on immunization strategies for hepatitis B in different endemic areas of China].

OBJECTIVE: To compare the cost-benefit of immunization with hepatitis B (HB) vaccine in different endemic areas of HB and to explore the optimal strategy for it. METHODS: Cost-benefit analysis and comprehensive weighted score analysis (CWSA) were used to screen the optimal immunization strategy for low, medium and heavy endemic areas of HB. RESULTS: Significant economic benefit was obtained in Long-An County, Guangxi Zhuang Autonomous Region, Shanghai and Jinan, Shandong Province from HB immunization programs for infants. The greatest benefit cost ratio (BCR) was provided by the low-dose immunization strategy, which was 49.91, 54.53 and 37.68, respectively for heavy, medium and low endemic areas of HB. The maximal net benefit could be obtained by the high-dose immunization strategy with better immune protective efficacy. CWSA showed that the low-dose immunization strategy was the optimal one for HB immunization. CONCLUSION: It is suggested that the low-dose immunization strategy be implemented in undeveloped areas to obtain a greater BCR, and the high-dose one be implemented in more developed areas to obtain more net benefit and lower prevalence of hepatitis B surface antigen carriage.

China↗

PubMed1999

[Research on quality of life of stroke patients and linear model of its impact factors].

The present study reviewed the investigation of 278 stroke patients of Changsha city population in 1994. The result showed that patients of stroke might have different quality of life during the process of their illness. Multiple regression model indicated that major factors on the chronic stroke patients were type of stroke, age, home nursing time, labor-losing days, occupations. The study provides reference source for prevention of stroke and improvement of quality of life.

Adult↗

PubMed1999

[A study of scavenging action of purslane aquenous extracts on oxygen free radical].

Auto-oxidation in alkalesent solution with the help of pyrogallol can generate O2.-, and the system of 1, 10-phenathroline-Fe(II)/H2O2 can produce .OH. Spectropholometry (wave length 322 nm and 536 nm) was used to observe the effect of fresh purslane aqueous extracts and the purslane aquenous extracts processed by boiling water upon O2.- and .OH. The results showed that fresh purslane aqueous extracts could obviously help generate O2.- and reduce .OH, and the aqueous extracts of purslane processed by boiling water had a scavenging action on O2.- and .OH greatly.

Drugs, Chinese Herbal↗

PubMed1999

[Evaluation of therapeutic efficacy by detection of specific IgG and IgG4 against KLH in schistosomiasis japonica].

The specific IgG and IgG4 antibodies in the sera of patients with Schistosoma japonicum were determined by KLH-ELISA and SEA-ELISA. The results showed that KLH-ELISA was as sensitive and specific as SEA-ELISA. The negative conversion rates of IgG and IgG4 12 months after treatment detected by KLH-ELISA were significantly higher than those by SEA-ELISA. The negative conversion rate of IgG was 92.9%, and that of IgG4 was 97.6% 24 months after treatment. Therefore, it is regarded that detecting specific IgG and IgG4 by KLH has high value in both diagnosing schistosomiasis japonica and assessing its therapeutic efficacy. Particularly the specific IgG4 may be a short-duration antibody which can indicate successful chemotherapy of patients with chronic Schistosoma japonicum infection.

Animals↗

PubMed1999

[Schistosoma japonicum: protective immunity induced in mice immunized with SjGST-Sj32].

Schistosoma japonicum glutathione-s-transferase (SjGST), Schistosoma japonicum 32,000 protein (Sj32) and SjGST - Sj32 were expressed and purified to study on protective immunity against Schistosoma japonicum. The result showed that compared with the adjuvant control group, the worm burden was decreased significantly in mice immunized with recombinant SjGST - Sj32, Sj32 and Sj32 + SjGST (P < 0.05). At the same time, the liver egg per gram(EPG) was decreased in mice immunized with SjGST - Sj32, Sj32, Sj32 + SjGST and SjGST. It is concluded that Sj32 significantly induces both protective immunity and anti-fecundity immunity, but SjGST only has an anti-fecundity effect.

Animals↗

PubMed1999

[Study on the removal of arsenic from drinking water by coagulants].

The coagulation method for removing arsenic in drinking water from dispersed water supply was tested. The results showed that the remained arsenic [As(V)] in decanted water could be lower than 0.05 mg/L by directly putting 50 mg/L ferric sulfate into water samples without adjusting pH value (pH 7.82) and settling for 12 hours in room temperature while the original As(V) concentration was 1.0 mg/L. The same removal efficacy could be achieved by putting 30 mg/L ferric sulfate or 40 mg/L aluminum sulfate and filtering after 30-40 min settlement. The removal rates were raised with the increased concentration of coagulants in water. The remained As(V) in filtered water could meet the valid health standard of drinking water (< 0.05 mg/L) when the original concentrations of As(V) were 1.0 mg/L and 0.5 mg/L by using 30 mg/L ferric sulfate and aluminum sulfate respectively. Furthermore, ferric sulfate was more efficient than aluminum sulfate at varied of pH value, water temperature, turbidity and hardness of water, etc. Generally, arsenic in coagulated sludge would not release into water again.

Arsenic↗

PubMed1999

[Changes of simple epithelial cytokeratin during oral carcinogenesis].

OBJECTIVE: To investigate whether the simple epithelial cytokeratin CK18 and CK19 can be used as a marker of oral precancerous lesions. METHODS: Formalin-fixed, paraffin-embedded tissue sections of normal oral mucosa, epithelial hyperplasia, mild epithelial dysplasia, moderate epithelial dysplasia, severe epithelial dysplasia and oral squamous cell carcinomas were stained with a CK18-specific antibody and CK19-specific antibody respectively by LSAB immunohistochemical method. The stained sections were observed under light microscopy. The results were described and analyzed with Rank Sum Test. RESULTS: CK18 was not detected in normal and abnormal oral tissue sections. But in normal nonkeratinized mucosa, CK19 was detected in the basal cell layer dispersively. In epithelial dysplasia, CK19 was detected in the suprabasal cell layer and the number of CK19-positive cell layers was correlated with the dysplasia degree of epithelia. Furthermore, CK19 was detected in oral squamous cell carcinoma, especially in the poor-differentiated cancer cells. CONCLUSION: CK19 expression in suprabasal cell layer of oral mucosa can be used as a candidate marker for diagnosis of oral precancerous lesions and determination of the differentiation level of oral squamous cell carcinoma.

Biomarkers, Tumor↗

PubMed1999

[Immunocytochemical identification of tropomyosin in nucleoli and nucleolar matrix of Physarum polycephalum].

Nucleoli were isolated from physarum polycephalum, and nucleolar matrix was prepared by digesting the nucleoli respectively with DNase 1, 0.25 mol/L (NH4)2SO4 and 2 mol/L NaCl to remove DNA and most proteins. SDS-PAGE analysis indicated that there were about 20 polypeptides in nucleolar matrix component, including the 37 kD polypeptide which was similar to tropomyosin in molecular weight. The result of indirect immunofluorescence treated with anti-tropomyosin antibody and sheep anti-rabbit IgG antibody labelled with FITC showed that bright fluorescence was observed in the nucleoli and nucleolar matrix, but no bright fluorescence in the controls. Indirect Immunoblotting detection further verified that tropomyosin existed in nucleolar matrix. Protein A-colloidal gold immunoelectron microscopic study showed that there were many gold particles in the specimens labelled with tropomyosin antibody, and there were few gold particles found in the controls. Tropomyosin distributed dispersedly in nucleoli.

Animals↗

PubMed1999

[Expression of genes aroG and pheA in phenylalanine biosynthesis].

aroG and pheA genes, encoding 3-Deoxy-D-arabinoheptulonate-7-phosphate synthase(DS) and Chorismate mutase (CM)-prephenate dehydratase(PD) in the pathway of phenylalanine biosynthesis respectively, were amplified by polymerase chain reaction(PCR). The genes were assembled on the multicopy vectors and expressed in both Escherichia coli and Brevibacterium. The products of two gene were detected by SDS-PAGE. The activities of relevant enzymes were measured in the crude extract of the host strain. When aroG-pheA genes were introduced into E. coli p2392, the activities of DS, CM and PD were increased by 4.3-fold, 4.4-fold and 2.2-fold respectively. Whereas in the case of Brevibacterium flavum 2732, the activities of DS, CM and PD were increased by 12.3-fold, 2.3-fold and 5.6-fold, respectively. As the results, the overproduction of phenylalanine was brought about by using the genetic engineering strain of B. flavum.

3-Deoxy-7-Phosphoheptulonate Synthase↗

PubMed1999

[Studies on allozyme of Gammatricula].

AIM: To furnish molecular genetic evidences for taxonomy of Gammatricula. METHODS: A total of 24 enzymes of 6 populations of Gammatricula songi and 1 population of Gammatricula chinensis collected from Kaihua County and Chunan County of Zhejiang Province were studied using horizontal starch gel electrophoresis. RESULTS: 29 loci were found. The percentages of polymorphic loci of G. songi populations were 6.9%-13.8%. All loci of G. chinensis were monomorphic. The Nei's distance among G. songi populations did not exceed 0.12. The Nei's distance between G. songi and G. chinensis was 0.73. CONCLUSION: The allozyme variations of inter-G. songi are limited, but the allozyme variation between G. songi and G. chinensis is significant.

Alleles↗

PubMed1999

[Studies on allelic zymogram of periodic Brugia malayi from Zhejiang Province].

AIM: To study the allelic zymogram of periodic B. malayi from Zhejiang Province. METHODS: 180 adult worms(male 60, female 120), 32,000 microfilaria and 1,500 infective larvae of periodic B. malayi were examined for the isoenzymes of 14 enzymes by horizontal starch gel electrophoresis with 14 different isomyme. RESULTS: Twenty-seven allelic loci were found in three developing stages of B. malayi, most of them were homozygotes, however, two of them(MPI,MDH) were heterozygotes(7.4%). 17, 19 and 9 loci were presented in adult worms, microfilariae and infective larvae, respectively. At the same time, the allelic zymogram of B. malayi from Guizhou Province was also examined. CONCLUSION: The allelic zymogram of periodic B. malayi from Zhejiang Province was similar to that of periodic B. malayi from Guizhou Province but passaged in the laboratory.

Animals↗

PubMed1999

[Dexamethasone inhibits IL-5-induced eosinophil survival].

OBJECTIVE: To assess the effect of dexamethasone (Dex) on interleukine-5-induced survival of eosinophils (EOS) in vitro. METHODS: EOS were purified from guinea pigs by Percoll density gradient and incubated for 4 days in the presence of IL-5 with or without Dex. Cell viabilities were determined by staining cells with fluorescein diacetate and propidium iodide. RESULTS: In the absence of Dex, IL-5 enhanced EOS survival was inhibited in a dosedependent manner. Inhibition was time-dependent and required at least 2 days exposure of EOS to Dex. When EOS were incubated with varying concentrations of IL-5 and 1,000 nmol/l Dex, survival inhibition was reduced at higher concentration of IL-5, and completely abolished by IL-5 1,000 pg/ml. CONCLUSIONS: Dex acts directly on mature EOS to decrease their viabilities, implying the Dex may be important in the treatment of allergic and other inflammatory eosinophilic disorders.

Animals↗

PubMed1999

[Nasopharygeal size in obstructive sleep apnea syndrome].

OBJECTIVE: To investigate the impact of upper airway 3-D size on the obstructive sleep apnea syndrome (OSAS). METHODS: There were 20 male and 3 female OSAS patients involved in the research. The measured apnea-hypopnea index (AHI) was 45.72(24.01 episodes per hour of sleep). The items measured from magnetic resonance imageing (MRI) of upper airway size were compared to those from 12 normal controls that were sex and age matched to the OSAS patients. The Pearson correlation and multiple linear regression had done to investigate into the relationship of AHI and MRI data. RESULTS: The OSAS patients had relatively narrow nasopharynges than matched controls in the following items: the sagittal size, transverse size, section area and volume. The measured sagittal size of the nasopharynx was closely related to AHI and Lown SaO2, and the volume of nasopharynx was related to apnea index (AI). CONCLUSION: The nasopharyngeal size is closely associated with OSAS.

Adult↗