Biomedical subjects

D Tan

Publications and source records attributed to D Tan.

At least 73 records · Page 4Linked to original sources

PubMed1998

Role of vascular endothelial growth factor on erythropoietin-related endothelial cell proliferation.

The vascular actions of recombinant human erythropoietin (rhEPO) are of particular relevance for fully understanding rhEPO effects. This study examines the mechanisms of action of rhEPO on endothelial cells from bovine aorta (BAEC). First, the studies demonstrated that rhEPO acts on BAEC proliferation as a comitogenic growth factor in the presence of fetal calf serum (FCS). The main experimental findings disclosed that an interaction between rhEPO and vascular endothelial growth factor (VEGF) is instrumental for the growth-promoting action of rhEPO, as shown by the blockade (92.8+/-2.2% inhibition, P < 0.01) of the rhEPO-induced BAEC proliferation by a specific anti-VEGF antibody and by the capability of VEGF for substituting FCS in the induction of rhEPO-related BAEC proliferation (increase in BAEC number in the absence of FCS: 20 U/ml rhEPO alone, 0.3+/-2.8%; 5 x 10(-11) M VEGF alone, 52.9+/-3.1%; 20 U/ml rhEPO + 5 X 10(-11) M VEGF, 117.8+/-6.9%, P < 0.01 between the two agents combined with respect to each agent alone). The existence of a positive interaction between rhEPO and VEGF was further demonstrated by observing an increased cytosolic Ca2+ ([Ca2+]i) mobilization response to VEGF (10(-11)M) in BAEC pretreated or not with 20 U/ml rhEPO (delta[Ca2+]i = 704+/-111 versus 246+/-36 nM, respectively, P < 0.01). To further examine the mechanism of the potentiation of VEGF effect by rhEPO, we analyzed the mRNA expression of the VEGF receptors KDR/flk-1 and flt-1. The results disclosed that BAEC pretreatment with rhEPO upregulated the expression of both KDR/flk-1 and flt-1, therefore providing a structural basis for the aforementioned positive interactions between VEGF and rhEPO. Furthermore, inhibition by genistein suggests that tyrosine phosphorylation was involved in the VEGF receptor upregulation. The mechanisms identified in the present study disclose an interaction at the level of mRNA expression and functional effects between a hormone with predominantly hemopoietic effects, namely, erythropoietin, and an angiogenic factor, namely, VEGF. This relationship between rhEPO and VEGF might be of particular importance in neovascularization processes and in patients receiving rhEPO as a treatment.

Animals↗

PubMed1998

Effects of angiotensin II on endothelial cell growth: role of AT-1 and AT-2 receptors.

Angiotensin II (AngII) is a main mediator in the regulation of vascular tone. Although its effects on vascular smooth muscle cells are well known, data on its role on endothelial biology are still insufficient. The present study examined the effect of endogenous and exogenous AngII on bovine aortic endothelial cells possessing both AT-1 and AT-2 receptors. A DNA synthesis-promoting effect of AT-2 blockade by PD123319 (10(-9) to 10(-7) M) was demonstrated. This effect was transduced through an AT-1-mediated pathway, as shown by using the AT-1 antagonist, losartan. In addition, an AT-1-mediated effect of AngII was demonstrated on bovine aortic endothelial cell proliferation, which occurred despite the absence of AngII-induced Ca2+ transients. In summary, the present study disclosed relevant characteristics of the effect of AngII on endothelial cell growth that have potential pathophysiologic projections, particularly for the use of selective AngII blocking agents.

Angiotensin II↗

PubMed1998

[Genotype distribution of hepatitis C virus in hepatocellular carcinoma tissue in Hunan province].

Genotypes of hepatitis C virus(HCV) were detected by PCR using type-specific primer in 50 patients' hepatocellular carcinoma(HCC) tissue. The results showed that in the 50 HCC specimens, 30(60%) and 3(6%) were infected with the HCV type II and III, 5(10%) and 8(16%) with type II + III and type II + IV, 2(4%) with type II + I + III in combination, respectively. 2 cases were negative for HCV. These data suggest that HCV type II may be a predominant genotype related to hepatocarcinogenesis in Hunan Province, some cases of HCC may result from coinfection of HCV type II and other genotypes, and only few HCC be separately caused by infection of HCV type III.

Adult↗

PubMed1998

[A study on HBV DNA pre C region A83 mutation in patients with hepatitis B].

Mismatched polymerase chain reaction (MPCR) and restriction fragment length polymorphism assay(RFLP) were performed to detect the HBV DNA pre core A83 mutation in 97 patients with chronic HBV infection in Hunan. HBV DNA pre core A83 mutation were detected in 37 out of 97 patients (37/97,38.1%). It was found that the prevalence of HBV DNA pre core A83 mutation of the patients with severe hepatitis and with CAH(chronic active hepatitis) were significantly higher than those with CPH(chronic persistent hepatitis) and carriers of HBV, and the patients with elevated transaminase (ALT > 70U) or positive HBeAb were significantly higher than those with normal transaminase (ALT < 70U) and with positive HBeAg, respectively. The results suggest that the HBV DNA pre core A83 mutation is associated with active and severe liver tissue in patients with hepatitis B.

Adolescent↗

PubMed1998

[Serum HBV DNA detected by polymerase chain reaction with dUTP/uracil-DNA glycosylase].

The ability of PCR reagent containing dUTP/uracil-DNA glycosylase for controlling carry-over contamination of PCR products was explored. All of 204 sera taken from hepatitis patients were used for HBV DNA detection by PCR with PCR-dUTP/UDG reagent in comparison with that without dUTP/UDG. The results showed that its efficiency of controlling contamination was excellent. At least, contamination of 100 ng PCR products was got rid of. The corresponding rate of HBV DNA detection by PCR-dUTP/UDG in combination with dot hybridization using digoxin-labeled HBV probe was as high as 89.32%, higher than that (81.45%) of PCR without dUTP/UDG plus dot hybridization(P < 0.05). It suggests that PCR-dUTP/UDG method could prevent PCR products from contaminating and increase accuracy and specificity of PCR amplification.

DNA Glycosylases↗

PubMed1998

[Four-year follow-up and molecular epidemiologic investigation of intrafamilial transmission of HCV infection].

OBJECTIVE: To study the intrafamilial transmission of HCV infection. METHODS: Four-year follow-up and molecular epidemiologic investigation of HCV infection in a village was carried out. The diversity of HCV core region was analysed by reverse transcription nested polymerase chain reaction, Okamoto genotyping method, and single strand conformation polymorphism analysis (SSCP). RESULTS: The incidence of positivity of anti-HCV and -HCVRNA raised from 21.30% (75/352) to 43.18% (152/352). There were 42 families with two or more members serological positive for anti-HCV and/or -HCVRNA. There were a 3.46-fold increase of intrafamilial propagation of HCV infection in the past 4 years. HCV genotyping by Okamoto method showed that 90.67% (136/150) belonged to Type 1b/II, two cases (1.33%) belong to type 2a/III and three cases (2.00%) were co-infection of both types. Comparison of SSCP patterns revealed that the SSCP of HCV cDNA was identical among members of the same family, but the single strand conformation of HCV cDNA exhibited polymorphism patterns in different families. CONCLUSION: The results indicate that the cause of marked increase of HCV infection rate in this village in a 4-year period is mainly because of intrafamilial propagation. SSCP is more feasible for molecular epidemiologic investigation of HCV infection than genotyping.

Adolescent↗

PubMed1998

[Changes of serum myocardial enzymes in patients with malignant hematologic diseases].

Myocardial enzymes including aspartate aminotransferase (AST), lactate dehydrogenase (LDH), HBD (LDH1 and LDH2), and creatine kinase (CK) and its isoenzyme were monitored in 106 cases of malignant hematologic diseases. The findings were that average values of LDH and HBD increased. There were 82.4% myocardial enzyme levels of 51 patients with leukemia, lymphoma, and myelodysplastic syndrome (MDS) returning to normal or making an obvious reduction after chemotherapy associated with drugs of heart toxicity, while there were increases of the myocardial enzyme levels before chemotherapy. Patients with the increasing of enzyme levels were only 3.9% after chemotherapy. After several courses of chemotherapy, the positive rates of the increasings of CK and CK-MB were higher than that of pretreatment. The results suggest that the injuries of myocardium are possible.

Anthracyclines↗

PubMed1998

[Investigation of hepatitis B virus infection in blood donors].

To investigate the status of HBV-M and HBV DNA in blood donors, 583 serum samples were detected by ELISA technique and polymerase chain reaction. The results were that hepatitis B virus marker(HBV-M) positive rate was 55.9%(326/583), HBV DNA 9.78%(57/583). The data indicate that there is high incidence of HBV infection in blood donors. The donors should be strictly tested for HBV in the future.

Adolescent↗

PubMed1998

[Study on gene of YRRM in azoospermia].

OBJECTIVE: To detect the abnormal YRRM gene in azoospermia and to explore the pattern of YRRM gene in Chinese men. METHODS: With the special primer for YRRM, the YRRM gene was analyzed using the PCR method. Extracting the testis total RNA, we performed the RT-PCR. The part of YRRM gene was sequenced. RESULTS: No amplification band of YRRM gene was noted in 4 of 74 Chinese men with azoospermia (5.4%). The YRRM gene was obviously expressed in the testis of man and showed a 500 bp cDNA fragment. The cDNA and genomic DNA were different because the intron. We found that Chinese people only have YRRM1 pattern of gene, and the sequence of YRRM gene of Chinese men shows that the composition of the nucleotide is same as YRRM1 gene. CONCLUSION: These cases of abnormal YRRM gene may result in male infertility, YRRM gene and azoospermia is the YRRM1 gene is polymouphase of racial.

Adult↗

PubMed1998

[Polymerase chain reaction applied for detection of Toxoplasma gondii in lymph nodes].

In order to investigate the morbidity of toxoplasmic lymphadenitis, polymerase chain reaction (PCR) was used to detect DNA of Toxoplasma gondii within lymph nodes in 3 groups of 120 patients with different diseases. After extracting the DNA of each sample, PCR was employed to amplify toxoplasma DNA. The results showed that the amplification product of 210 bp was confirmed in 7 patients: 3 cases of Hodgkin's disease (HD), 2 cases of non-Hodgkin's lymphoma (NHL) and 2 cases of chronic lymphadenitis (CL). Each PCR product was then subjected to Southern blot hybridization. Besides the 7 cases proved by PCR, 1 case of CL was found positive. The positive percentages of HD, NHL and CL were 9.38% (3/32), 4.88% (2/41), and 6.38% (3/47), respectively. The total positive rate was 6.67% (8/120).

Animals↗

PubMed1998

[A prospective investigation on interferon treatment of chronic hepatitis B].

Mismatched polymerase chain reaction and restriction fragment length polymorphism assay together with neutralization bioassay were performed in order to elucidate the influence of pre core mutation of HBV genome and neutralizing anti-INF on the therapeutic efficacy of IFN-2b. In 29 patients treated with IFN alpha-2b, HBV DNA pre core mutation were detected in 15 patients (15/29, 51.7%), HBV DNA in 7 of these 15 patients (7/15, 46.6%) turned to negative, all of whom were recurrent one year follow up. In the other 14 patients without pre core mutation, 7 patients (7/14, 50%) became serum HBV DNA negative, none of whom were recurrent. HBV DNA was undetectable in 4 of the 15 patients (4/15, 26.7%) with neutralizing antibody. In contrast, HBV DNA became undetectable in 10 of the 12 patients (10/12, 83.3%) without neutralizing antibody (P < 0.05).

Adult↗

PubMed1998

[A clinical observation on the leukopenia treated with shengbaikuai decoction].

OBJECTIVE: To study the effective orally taken medicine in treating the leukopenia. METHODS: Ninety cases of leukopenia induced by chemotherapy were divided into 3 groups. They were test group treated with Shengbaikuai Decoction (SBK), control group and blank group. Their efficacies were compared with each other, 25 cases with nonchemotherapy were also observed. RESULTS: WBC count and absolute neutrophil count (ANC) in test group were higher than those of other groups immediately after treatment and 2 weeks later (P < 0.01). The marked effective rate and total effective rate of test group after 2 weeks were 60.0% and 80.0% (P < 0.001) respectively, which were significantly higher than those of other groups. WBC and ANC count after treatment and 3 weeks later were higher than those before treatment in nonchemotherapy group (P < 0.001). The marked effective rate and total effective rate 3 weeks later were 64.0% and 80.0% respectively. CONCLUSIONS: SBK could increase WBC count rapidly and definitely without apparent side effect.

Adolescent↗

PubMed1998

[Detection of Toxoplasma gondii DNA in human lymph node tissue by in situ hybridization].

AIM: To detect the presence of Toxoplasma gondii in lymph node tissue in patients with Toxoplasma infection. METHODS: T. gondii (RH strain) specific DNA fragment clones were obtained by using PCR and gene recombination technique. The DNA fragments used as hybridization probes were labelled with digoxigenin by random primer method. The technique of in situ hybridization (ISH) was used to detect T. g DNA in the lymph node sections. RESULTS: Four out of 120 samples T. g DNA were found positive, one with Hodgkin's disease (HD) (1/32), one with non-Hodgkin's lymphoma (NHL) (1/41) and 2 with chronic lymphadenitis (CL) (2/47). The total positive rate was 3.3%. It was demonstrated that this highly specific probe could detect 10 pg of the total RH strain T. g DNA. CONCLUSION: ISH was applicable in detecting pathogens in the lymph node tissues of individuals with Toxoplasma infection.

Animals↗

PubMed1997

A comparison of two pertussis epidemics in Auckland.

AIM: To determine if the addition of the 6 week dose of pertussis vaccine in 1984 was associated with any change in the hospitalisation rate for children with pertussis and the higher hospitalisation rates for Maori and Pacific Islander children with pertussis. METHODS DESIGN: Population based study of pertussis hospitalisations using a retrospective chart review of hospitalisation data for children during the 1991 epidemic, which was compared to previously published data from the 1982 epidemic. SETTING: Princess Mary and Middlemore hospitals, Auckland. SUBJECTS: Children aged 0-14 years resident in metropolitan Auckland and hospitalised in Auckland during 1982 or 1991 with pertussis. MEASUREMENTS: Hospitalisation rates were calculated as number of children with a discharge diagnosis of pertussis per 1000 children aged 0-14 years based on 1981 and 1991 census data. 1982 data were converted to person-years as published report was for an 8 month period. Hospitalisation rates were compared as a relative risk (RR) of hospitalisation in 1991 versus 1982. RESULTS: There were 84 cases during 8 months in 1982 and 66 cases in 1991. Rates of hospitalisation by ethnic group; in 1982 were 0.24 Other/European (OE), 1.98 Maori (M), 1.37 Pacific Islander (PI); and in 1991 were 0.22 OE, 0.51 M, 0.40 PI. Compared to 1982 the relative risk of hospitalisation in 1991 adjusted for ethnicity was 0.43 (CI 0.33, 0.58, p < 0.0001). Compared to 1982 there was a significant reduction in the hospitalisation rate in 1991 for M (RR = 0.26, CI 0.16, 0.43, p < 0.0001); and PI children (RR = 0.29, CI 0.16, 0.54, p < 0.0001); but not for OE children (RR = 0.91, 95% CI 0.57, 1.46, p = 0.70). CONCLUSIONS: There was a significant reduction in the rate of hospitalisation for pertussis in 1991 compared to 1982. This reduction in hospitalisation rate was due to a reduction in rates for Maori and Pacific Islander children.

Adolescent↗

PubMed1997

Hepatitis C in asymptomatic blood donors.

Among 248 asymptomatic blood donors positive for antibody to hepatitis C virus (anti-HCV) enrolled in a long-term prospective study, 86% had chronic HCV infection and 14% appeared to have recovered as assessed by serial determinations of serum alanine aminotransferase (ALT) levels and HCV RNA by polymerase chain reaction. Established parenteral risk factors for HCV transmission were identified in 75% of donors. In addition, there was a strong independent association between HCV positivity and cocaine snorting, suggesting that shared snorting devices may be a covert route of parenteral transmission. Ear piercing in males was also significantly associated with transmission. There was no evidence for sexual spread. Although the majority of HCV carriers had both biochemical and histological evidence of chronic viral hepatitis, the extent of liver injury was generally mild. Among a larger population of 280 HCV RNA-positive donors, 17% had repeatedly normal ALT levels, 45% had levels that did not exceed twice, and only 22% had levels that exceeded five times the upper limit of the normal range. Among 81 patients who underwent liver biopsy, only 13% had evidence of severe hepatitis (8%) or cirrhosis (5%), despite a duration of infection that generally exceeded 15 years. No severe histological lesions were observed in blood donors with chronic HCV infection who had repeatedly normal ALT levels. In both donors and blood recipients, the frequency of severe morbidity or mortality related to HCV infection was less than 10% during the first two decades of infection. Further long-term studies are required to see if the progression to severe outcomes continues to accrue at this slow pace or whether it accelerates during subsequent decades.

Blood Donors↗

PubMed1997

Concentrated ascitic fluid reinfusion in cirrhotic patients: a simplified method.

A new method for ascites filtration and reinfusion, which uses a single Cuprophan filter and is performed in the dialysis unit, is reported. Thirty-one procedures were performed in 17 patients with cirrhosis and massive ascites. A mean volume of 8.6 L of ascitic fluid was removed; from this volume, 5 L were ultrafiltered and a concentrated ascitic fluid was reinfused (x = 359.8 mL). The whole procedure was completed in a mean time of 248 minutes. No relevant method-related complications were detected. Moreover, no significant changes in blood urea nitrogen (BUN), creatinine, plasma and urinary electrolytes, or platelet count were found, even in the case of repeated procedures (two to nine times). The reinfused fluid contained a mean value of albumin of 4.7 g/dL and significant amounts of globulins and complement. The overall cost of the materials used in the procedure ($49.46) offered competitive advantages with respect to other types of frequently used methods. In conclusion, we present a safe, effective, and time- and cost-saving technique for ascites reinfusion that represents an advantageous alternative to more complicated and expensive methods or to the currently used medical therapy.

Ascites↗

PubMed1997

Submandibular gland peptide-T (SGP-T) inhibits intestinal anaphylaxis.

A novel peptide, submandibular gland peptide-T (SGP-T), which reduces allergen-induced hypotension, was examined for effects on intestinal anaphylaxis. Hooded-Lister rats were sensitized to egg albumin and prepared for the measurement of in vivo myoelectric activity of the jejunum. The disruption of migrating myoelectric complexes (MMCs) that occurs upon intraluminal, duodenal challenge with antigen of sensitized rats was inhibited by 75% upon intravenous treatment with 100 micrograms/kg of SGP-T. In addition, SGP-T reduced the number of rats experiencing anaphylactic diarrhea and disrupted MMCs, but the peptide did not alter antigen-provoked release of rat mast cell protease II. The mechanism of action of SGP-T remains to be determined, but it apparently does not act directly on mast cells to exert its antianaphylactic action. These results emphasize that modulation of immediate hypersensitivity reactions is only one of several gastrointestinal activities that are affected by growth factors and peptides released from salivary glands.

Anaphylaxis↗

PubMed1997

Evaluation of commercially available and in-house reverse transcription-PCR assays for detection of hepatitis G virus or GB virus C.

Serum samples from 96 Spanish hemodialysis patients, as well as serial dilutions of RNA extracted from a reference strain of hepatitis G virus (HGV), were tested for HGV or GB virus C (GBV-C) RNA. Two different reverse transcription (RT)-PCR-based methods of detection were compared for the ability to detect RNA extracted from the samples: an RT-nested PCR assay with primers derived from the 5' noncoding region (5'NC) or nonstructural region 3 (NS3) sequences and a commercially available RT-PCR assay with primers derived from the 5'NC or NS5A sequences. When RT-nested PCR was performed on 10-fold serial dilutions of RNA from the HGV reference strain, the last positive dilution was 10(-7) to 10(-8). With the commercial RT-PCR assay, the last positive dilution was 10(-6) to 10(-7). When equal amounts of RNA extracted from serum samples from 96 hemodialysis patients were tested for HGV or GBV-C RNA, 25 patients (26%) were positive by the RT-nested PCR. However, only 21 (84%) of these 25 positive patients were positive for HGV or GBV-C by the commercial RT-PCR assay. Analysis of the 5'NC and NS3 sequences amplified by RT-nested PCR demonstrated that all but two positive patients had unique HGV or GBV-C sequences. In summary, RT-nested PCR and a commercially available RT-PCR assay for HGV or GBV-C gave concordant results for 96% of the patients tested.

Base Sequence↗