Biomedical subjects

Z Sun

Publications and source records attributed to Z Sun.

At least 181 records · Page 10Linked to original sources

PubMed1998

[An analysis of bacterial resistance to antimicrobial agents in a burn centre].

OBJECTIVE: To investigate bacterial resistance to antimicrobial agents in the background of extensive employment of third-generation cephalosporins in the treatment of burn infection. METHODS: Bacterial susceptibility testing was carried out using Kirby-Bauer method. RESULTS: Out of 259 Gram negative bacilli isolates, 31% of these strains were all resistant to cefotaxime, ceftriaxone, cefoperazone and ceftazidime. In vitro test, susceptibility of 52% third-generation cephlosporins resistant strains were restored by cefoperazone/sulbactum. 23.8% of P. aeruginosa were resistant to imipenem, 51.2% to ciprofloxacin. 28.6% of A. anitratum were resistant to imipenem, 21.4% to ciprofloxacin. 9.9% of enterobacteriaceae were resistant to imipenem, 20.4% to ciprofloxacin. 26.9% of MRSA were resistant to imipenem, 73% to ciprofloxacin. No norvancomycin resistance was detected. 2.7% of E. faecalis were resistant to norvancomycin. CONCLUSION: It is likely that the observed resistance to third-generation cephalosporins may be partially due to chromosome-mediated type-1 beta- lactamase.

Burns↗

PubMed1998

[Study on the preventive effect of tea on DNA damage of the buccal mucosa cells in oral leukoplakias induce by cigarette smoking].

In order to study the preventive effect of tea on DNA damage induced by cigarette smoking and to provide further evidence on the protective effects of tea in human cancer, a 6-month, double-blind and randomized placebo-controlled intervention trial was carried out. The effect of tea on micronuclei frequency in exfoliated oral buccal mucosa cells in 36 oral leukoplakias of smokers was investigated. A kind of mixed tea given in an oral dose of 3 g/day and a concentration of 0.1% smeared on mucosa lession three times a day for 3 months and 6 months, significantly decreased the micronuclei formation in exfoliated oral buccal mucosa cells in subjects with oral leukoplakias. In contrast, there was no change in the micronuclei frequency after 6 months in the placebo group. The results indicate that mixed tea may reduce the oral cancer risk by preventing DNA damage in oral leukopiakias induced by cigarette smoking.

Adult↗

PubMed1998

[Mutation analysis of the p15 gene exon 2 in human primary hepatocarcinoma].

To investigate the role p15 gene plays in the pathogenesis of human primary hepatocarcinoma, 35 human hepatocarcinomas, 35 cases of adjacent non-cancerous liver cirrhosis and the blood cells of 10 normal human were analyzed for somatic mutation in p15 gene with PCR-SSCP. One case of adjacent non-cancerous liver cirrhosis showed abnormal migration single strand. In the hepatocarcinomas and in the other cases of adjacent non-cancerous liver cirrhosis, no mutation was found. Cloning and sequencing of the amplified abnormal migration single strand DNA revealed that it contained a wild type exon 2 of p15 gene in 345 bp length. The results indicate that the inaction of p15 gene by point mutation is a very uncommon event in human hepatocarcinoma.

Carcinoma, Hepatocellular↗

PubMed1998

[Slot blot analysis of metastasis suppression gene nm23 expression in human lung cancer].

To investigate the role of metastasis suppression gene (nm23) in the development and progression of human lung cancer, the mRNA expressions of nm23-H1 and nm23-H2 genes in a series of pulmonary tissues collected at various sites and with different properties were studied with slot blot hybridization. According to the observations on the normal pulmonary tissues, benign lesions, para- and non-cancer tissues, primary cancer and metastatic lymph nodes, there was a tendency of mRNA expression reduction of nm23-H1 and nm23-H2 genes. Among them, nm23-H2 mRNA expressions in lung cancer tissues were significantly decreased when compared with normal pulmonary tissues (P < 0.05), and nm23-H1 and nm23-H2 gene expressions in metastatic lymph nodes were both reduced, compared with those in normal pulmonary tissues (P < 0.05). There was no significant correlation between nm23 gene expression and lymph node metastasis in lung cancer. The results implied that reduction of nm23 gene expression might be associated with the development of lung cancer, but no evidence of metastasis suppression by nm23 gene was revealed in this study.

Adenocarcinoma↗

PubMed1998

[Universal presence of HBVx gene and its close association with hotspot mutation of p53 gene in hepatocellular carcinoma of prevalent area in China].

OBJECTIVE: Hepatitis B virus (HBV) is a major etiological agent of hepatocellular carcinoma (HCC). The x gene of HBV genome (HBVx) is considered as its oncogene. In order to assess the extent of its involvement in hepatocarcinogenesis, both HBsAg sero-positive and mainly sero-negative HCC were searched for the presence, expression and mutation status of the x gene of HBV, as well as its association with 249 codon hot spot mutation of p53 gene. METHODS: Using PCR, RT-PCR, PCR-RFLP and DNA sequencing, studies were more focused on 25 HBsAg sero-negative, pathologically diagnosed HCC patients operated during 1991 to 1996 mainly in Qidong and also in Beijing. RESULTS: The x gene sequence of HBV was found by PCR without exception in all 25 seronegative HCC DNA (100% 25/25) and also in all 19 seropositive counterparts. The RNA messages of HBVx gene were found in all 8 HCC patients randomly selected from the seronegative group. Sequence analysis of the HBVx gene showed the presence of missense mutation in the 130 and 131 codon in 4 of 6 samples studied. Using PCR-RFLP, missense mutation of the 249 codon was identified in 57% (12/21) of all HBsAg negative cases from Qidong. No such mutations were found in the 4 Beijing counterparts. CONCLUSION: HBVx gene sequence was universally present in HBsAg negative HCC samples of Qidog studied, indicating the important role of HBVx gene in hepatocarcinogenesis of the high incidence area. The close association of the hotspot mutation of p53 gene in Qidong HCC with the presence of HBVx gene sequence suggests that such mutation is the molecular footprint of the combined effect of aflatoxin B1 exposure and HBVx gene product.

Adult↗

PubMed1998

[Comparison of pharmacological effects between cultispecies Sichuan Fritillary bulb (F. wabueasis, F. mellea) and wild Sichuan Fritillary bulb (F. unibracteata)].

The ethanol extracts from the cultured Sichuan Fritillary bulb have been proved similar to those from the wild one in treating coughing in mice, expectoration in rats, asthma in guinea pigs, bronchodilation of isolated lungs in mice, and cyclic nucleotide(cAMP, cGMP) in the plasma and lungs of mice. The acute toxicity of the cultured and wild species is also similar to each other. However, in terms of asthma relieving and cAMP level increment in the lungs, the cultured species F. wabueasis is significantly superior to the wild species of Fritillary bulb.

Animals↗

PubMed1998

[Repeat operations for recurrent trigeminal neuralgia after microvascular decompression].

For the study of cause and treatment of recurrent trigeminal neuralgia, repeat operations were performed in 12 patients with recurrent trigeminal neuralgia after microvascular decompression. Among repeat operations, there was vascular loop recompression at trigeminal root in 10 patients, negative exploration in 2 patients. The pain relief was achieved after neurovascular redecompression or neurolysis in all patients. The patients had no recurrent pain during a follow-up from 6 months to 4 years. The causes of recurrent trigeminal neuralgia after microvascular decompression and the questions related to repeat operations were discussed.

Adult↗

PubMed1998

[Recurrent pheochromocytoma].

OBJECTIVE: To improve the diagnosis of recurrent pheochromocytoma. METHODS: To study 11 cases of recurrent pheochromocytoma treated from 1970 to 1996. RESULTS: The recurrence was due to the metastasis of malignant tumor and the multifocal occurrence of benign one. Extraadrenal pheochromocytomas tended to occur at several sites or metastasize. The metastatic places usually no show pheochromatic tissues, and the recurrent benign tumors were liable to grow at extraadrenal regions. The nature of recurrent tumors should be judged according to variant factors. CONCLUSION: The recurrent pheochromocytomas are not malignant in nature, but they have considerable malignant tendency and should undergo intensive survelliance and regular examinations especially for the primary or recurrent extraadrenal pheochromocytomas.

Adolescent↗

PubMed1998

[Human interleukin-13 cDNA cloning and expression].

OBJECTIVE: To construct an efficient expression system for HIL-13 in prokaryotic cells. METHODS: After Amplified by RT-PCR, The cDNA fragment encoding HIL-13 was inserted into pGEX-2T plasmid and expressed under induced condition. RESULTS: HIL-13 cDNA was obtained. Recombinant plasmid pGEX-2T HIL-13 was constructed and sequenced, the inserted fragment of the recombinant plasmid was confirmed to be HIL-13 cDNA. HIL-13 was expressed as a fusion protein with glutathione-s-transferase (GST-HIL-13, MW = 39,000). CONCLUSIONS: (1) HIL-13 cDNA has been obtained from T lymphocytes. (2) The rate of expression of HIL-13 in prokaryotic cells is about 37%.

Amino Acid Sequence↗

PubMed1998

[Bacterial distribution and antimicrobial resistance monitoring of surgical infection].

OBJECTIVE: To study the antimicrobial resistance of surgical isolates in Wuhan area. METHOD: The diameters of the inhibition zones of surgical isolates around antibiotic susceptibility test discs at 13 hospitals in Wuhan were computerfiled and analysed by the software of "WHONET-3" according to NCCLS published in 1993. RESULT: A total of 957 surgical isolates were collected in 1996. S. aureus, P. aeruginosa, E. coli and CNS were the main microorganisms. 12.4% of S. aureus was resistant to oxacillin and to other antimicrobials as well. Most strains of Enterobacteriaceae were resistant to ampicillin, with a resistant rate of more than 75%, but 93% for klebsiella sp. Imipenem, ceftazidime, amikacin and ciprofloxacin were most active agents against Gram (-) bacilli including Enterobacteriaceae and glucose nonfermenters. CONCLUSION: Antimicrobial resistance should be seriously considered during surgical therapy and prophylaxis with antimicrobial agents. The tendency to antimicrobial resistance of clinical isolates should be followed up continuously.

Anti-Bacterial Agents↗

PubMed1998

[Effects of hairy root huangqi on hemopoietic function].

The effects of hairy root Huangqi on hemopoietic system were studied in this paper. The oral administration of 5-20 g/kg hairy root Huangqi per day for 5-12 days could increase the count of RBC and reticulocytes in mice with hemorrhagic anemia, raise the hemoglobin, RBC and hematocrit in mice with hemolytic anemia, enhance the number of WBC and nucleared cells in bone marrow of mice treated with cyclophosphamidum or x-rays. The experiments showed that hairy root Huangqi promoted the hemopoietic function. The effects were similer to those of natural Huangqi.

Anemia, Hemolytic↗

PubMed1998

[The relation of diabetic retinopathy with blood-fat and lipid peroxidation].

PURPOSE: To observe and inquire into the relation of diabetic retinopathy with lipid metabolism, and lipid peroxidation. METHODS: The contents of triglyceride (TG), total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), superoxide dismutase (SOD) and lipid peroxide (LPO) of serum were examined and determined both in thirty patients with diabetes in early stage suffering from retinopathy and twenty four healthy people. RESULTS: TG, TC, LDL-C and LPO in patients group were obviously higher than those in the control group, while HDL-C and SOD were lower than those in healthy control group. CONCLUSION: The disorder of lipid metabolism and the growing intensity of lipid peroxidation caused by diabetes may be one of the dangerous factors to bring about the retinopathy.

Aged↗

PubMed1997

Frequent abnormalities of TSG101 transcripts in human prostate cancer.

TSG101 has been identified as a candidate tumor suppressor gene and abnormal transcripts have been identified in a substantial fraction of breast cancers. To determine whether TSG101 expression is commonly altered in other tumors, a series of 15 primary and metastatic prostate cancers were analysed by reverse transcriptase-PCR amplification. Abnormal transcripts with extensive deletions in the coding region were found in nine of these tumors, while only the normal transcript was found in control and benign prostatic hypertrophy tissues. More than one abnormal transcript was found in four of these nine cases and distinct abnormal TSG101 transcripts were found in separate biopsies taken from one tumor. Importantly, the normal TSG101 transcript was undetectable in two metastatic prostate cancers, indicating the absence of TSG101 protein. Sequence analysis demonstrated that there were at least six distinct deletions, with four of these deletions found in more than one tumor sample. The most commonly identified deletion, from bp 153 to 1055, was identical to a deletion reported previously in breast cancer. These results demonstrate that TSG101 transcripts are frequently abnormal in prostate cancer and suggest that loss of TSG101 protein contributes to disease development or progression.

Base Sequence↗

PubMed1997

Identification of a flexible loop region (297-313) of urokinase-type plasminogen activator, which helps determine its catalytic activity.

Pro-urokinase has a much higher intrinsic catalytic activity than other zymogens of the serine protease family. Lys300(c143) in an apparent "flexible loop" region (297-313) was previously shown to be an important determinant of this intrinsic catalytic activity. This was related to the loop allowing the positive charge of Lys300(c143) to transiently interact with Asp355(c194), thereby inducing an active conformation of the protease domain (Liu, J. N., Tang, W., Sun, Z., Kung, W., Pannell, R., Sarmientos, P., and Gurewich, V. (1996) Biochemistry 35, 14070-14076). To further test this hypothesis, the charge at position 300(c143) and the flexibility of the loop were altered using site-directed mutagenesis designed according to a computer model to affect the interaction between Lys300(c143) and Asp355(c194). When the charge at Lys300(c143) but not Lys313(c156) was reduced, a significant reduction in the intrinsic catalytic activity occurred. Similarly, when the flexibility (wobbliness) of the loop was enhanced reducing the size of side chain, the intrinsic catalytic activity was also reduced. By contrast, when the loop was made less flexible, the intrinsic catalytic activity was increased. These findings were consistent with the hypothesis. The effects of these mutations on two-chain activity were less and often discordant with the intrinsic catalytic activity, indicating that they can be modulated independently. This structure-function disparity can be exploited to create a more zymogenic pro-urokinase (lower intrinsic catalytic activity) with a high catalytic activity, as exemplified by two of the mutants. The changes in intrinsic catalytic activity and two-chain activity induced by the mutations were due to changes in kcat rather than Km. Some significant structure-function differences between pro-urokinase and its highly homologous counterpart, tissue plasminogen activator, were also found.

Catalysis↗

PubMed1997

Androgen receptor-associated protein complex binds upstream of the androgen-responsive elements in the promoters of human prostate-specific antigen and kallikrein 2 genes.

An increasing number of proteins which bind to hormone-dependent nuclear receptors and mediate their effects on gene expression are being identified. The human prostate-specific antigen (PSA) and kallikrein 2 (KLK2) genes are regulated by the androgen receptor (AR). Using electrophoresis mobility shift assays (EMSA), a common nuclear protein(s) which binds upstream of the androgen-responsive elements (AREs) in the PSA and KLK2 promoters was identified. Binding occurred between bp -539 and -399 and bp -349 and -224 in the PSA and KLK2 promoters respectively, which were shown previously to be necessary for AR-mediated transactivation. Glutathione S-transferase (GST)-AR fusion proteins were constructed to determine whether the AR interacted directly with this protein or protein complex. Specific interactions were observed with AR fusion proteins containing the DNA binding domain. EMSA supershift experiments and GST-AR pull-down experiments followed by Western blotting identified a Fos-related protein(s) of approximately 40 kDa as part of this complex. Competition experiments with a double-stranded oligonucleotide containing an AP-1 binding site demonstrated that DNA binding was not mediated by AP-1. These results indicate that a Fos-containing protein complex distinct from AP-1 binds upstream of the AREs in the PSA and KLK2 promoters, interacts with the AR and may participate in regulation of these two androgen-responsive genes.

Amino Acid Sequence↗

PubMed1997

BAC and PAC contigs covering 3.5 Mb of the Down syndrome congenital heart disease region between D21S55 and MX1 on chromosome 21.

Chromosome 21 is a model for the study of human chromosomal aneuploidy, and the construction of its physical and transcriptional maps is a necessary step in understanding the molecular basis of aneuploidy-dependent phenotypes. To identify the gene(s) responsible for Down syndrome congenital heart disease (DS-CHD), we constructed a physical map of the D21S55 to MX1 region. A bacterial artificial chromosome (BAC) library was screened using several YACs spanning the interval, and a P1-derived artificial chromosome (PAC) library was screened using radiolabeled STS PCR products and whole BACs in gap-filling initiatives. FISH confirmed the location of all BAC and PAC clones to 21q22.2-q22.3. Overlaps were established using clone-to-clone Southerns and 24 new STSs, generated from the direct sequencing of BAC and PAC ends, along with 35 preexisting STSs. Approximately 3.5 Mb of the 4- to 5-Mb D21S55 to MX1 interval is covered in 85 BACs and 24 PACs, representing fourfold coverage within the contigs. These BAC and PAC contigs are valuable reagents for isolating the genes for DS-CHD.

Base Sequence↗

PubMed1997

Correlation of cytomegalovirus DNA levels with response to antiviral therapy in cardiac and renal allograft recipients.

BACKGROUND: Cytomegalovirus (CMV) infection represents a significant morbidity factor for transplant recipients. A rapid, sensitive, specific, and reliable test is desirable for early detection of CMV infection and for monitoring the efficacy of antiviral therapy. METHODS: We examined the incidence of CMV infection in 95 cardiac and 25 renal allograft recipients followed for up to 3 years using qualitative and quantitative polymerase chain reaction (PCR) techniques. Results were subsequently correlated with clinical findings. Of the 236 samples analyzed by the CMV PCR, 84 and 20 were also analyzed by blood buffy coat culture and anti-CMV antibody IgM assays, respectively. RESULTS: The sensitivity of the CMV PCR was found to be superior to that of the other assays, although the specificity of the blood buffy coat culture is as good as that of the CMV PCR, which is higher than that of the anti-CMV antibody IgM assay. CMV infection was detected by the CMV PCR in 17 of 95 cardiac and 9 of 25 renal transplant recipients. Clinical symptoms were observed when > or =500 copies of CMV DNA/1 microg of total DNA were detected by a quantitative CMV PCR assay using an external control CMV plasmid; however, some patients had symptoms when 50-100 copies were present. The levels of CMV DNA detected varied (50-1000 copies) in patients who developed asymptomatic CMV infection. The CMV DNA levels decreased to 50-100 copies 1-2 weeks after antiviral therapy was initiated and correlated well with disappearance of clinical symptoms. CMV DNA levels decreased to < or =5 copies at 4-7 weeks after treatment. This contrasts with patients who were unresponsive to anti-CMV therapy, in whom high levels of CMV DNA (> or =500 copies) persisted for at least 5 weeks and significant levels of CMV DNA (50-100 copies) were detected for several months afterward, despite multiple courses of anti-CMV therapy. Clinical symptoms also did not disappear during this period of observation. CONCLUSIONS: (1) The CMV PCR represents a rapid, sensitive, specific, reliable test for detection of CMV infection, especially for detection of virus replication in an incipient phase. (2) The quantitative CMV PCR is useful for monitoring the efficacy of antiviral therapy to distinguish patients who respond to therapy from those who do not. (3) CMV DNA levels > or =500 copies/1 microg of total DNA analyzed by the quantitative CMV PCR can be used to differentiate CMV infection from other infections and rejection.

Cytomegalovirus↗

PubMed1997

Cold-induced hypertension. A model of mineralocorticoid-induced hypertension.

Hypertension, tachycardia and cardiac hypertrophy develop in rats exposed to mild cold (5 degrees C, 41 degrees F) for 1 to 3 weeks. Elevation of blood pressure (BP) during cold exposure is sodium dependent, although the rats still have an elevation of BP with a minimum of NaCl in their diet. Drugs that interfere with the renin-angiotensin-aldosterone (RAA) system at various levels (propranolol, clonidine, captopril, losartan and spironolactone) are able to prevent the development of cold-induced hypertension (CIH). Plasma renin activity (PRA) increases during the first 3 weeks of exposure to cold and then gradually decreases toward control level. Increased blood pressure and dipsogenic sensitivity to administration of angiotensin II (Ang II) have been demonstrated during the first 3 weeks of exposure to cold suggesting an upregulation of Ang II receptors when PRA is elevated. Additional studies have shown greater Fos-like immunoreactivity in the diencephalon of cold-exposed compared to warm-acclimated rats after 1 hr i.v. infusion of Ang II (333 ng/kg/min). Thus, most characteristics of cold-induced hypertension mimic those of hypertension induced experimentally by chronic administration of large doses of deoxycorticosterone acetate (DOCA) and salt. The results suggest that CIH is a mineralocorticoid-induced hypertension and that various levels of the RAA system contribute.

Acclimatization↗