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Biomedical subjects

C C Pao

Publications and source records attributed to C C Pao.

At least 55 records · Page 3Linked to original sources
PubMed1992

Amplification of viral RNA for the detection of dengue types 1 and 2 virus.

In vitro DNA amplification by means of the polymerase chain reaction (PCR) was used to amplify dengue types 1 and 2 viral genomes in cultured cells and in the serum of persons infected with dengue virus. Results of the present investigation suggest that the PCR method is type-specific in detecting dengue virus and has a detection sensitivity of less than 100 plaque-forming units (pfu) for both serotypes of the virus. The PCR method may be useful for detecting and typing dengue virus in clinical and epidemiological specimens.

Base Sequence↗
PubMed1992

Prenatal transmission of hepatitis B virus to neonates born to serum hepatitis B virus DNA-positive mothers.

Hepatitis B virus (HBV) DNA was detected by in vitro enzymatic DNA amplification techniques in 66.7% (six of nine) of hepatitis B virus surface antigen (HBsAg)-positive and in 21.1% (7 of 33) of HBsAg-negative pregnant women. Five of the HBV DNA and HBsAg-positive women and one HBV DNA-positive but HBsAg-negative woman gave birth to infants positive for serum HBV DNA at time of birth. These results suggest that HBsAg-negative pregnant women are potentially capable of transmitting HBV DNA to their infants.

Blotting, Southern↗
PubMed1992

Hepatitis C virus in peripheral blood mononuclear cells.

RNA extracted from plasma and peripheral blood mononuclear cells of patients with chronic hepatitis C were used as the template for reverse transcription followed by double in vitro enzymatic amplification with nested primers. Hepatitis C virus was detected in 14 of 15 (93.3%) plasma specimens and in 8 of 15 (53.3%) peripheral blood mononuclear cell specimens obtained from patients with chronic hepatitis C and abnormal liver functions. The results suggest that hepatitis C virus could be found frequently in peripheral blood mononuclear cells of patients with chronic hepatitis C. Whether the presence of hepatitis C virus in peripheral blood mononuclear cells plays any role in the pathogenesis of diseases associated with hepatitis C virus infection remains to be determined.

Base Sequence↗
PubMed1992

Role of hepatitis C virus infection in spontaneous hepatitis B surface antigen clearance during chronic hepatitis B virus infection.

To examine the role of hepatitis C virus (HCV) infection in spontaneous hepatitis B surface antigen (HBsAg) clearance during the course of chronic hepatitis B virus (HBV) infection, serum specimens from 32 asymptomatic HBsAg carriers and 22 patients with chronic hepatitis type B who underwent spontaneous HBsAg clearance were studied for antibody to HCV (anti-HCV) using commercial EIAs. The results were compared with those of control groups matched for age, sex, hepatitis B e antigen, antibody to hepatitis delta virus, and cirrhosis. Eight (25%) of the asymptomatic carriers and 9 (41%) of the patients with chronic hepatitis were seropositive for anti-HCV in contrast to 1.6% and 9.1% of their respective control groups (P less than .01). Serum alanine aminotransferase level was persistently abnormal after HBsAg clearance in one asymptomatic carrier and in four patients with chronic hepatitis. These patients were seropositive for anti-HCV and at least one of them was negative for HBV-DNA by polymerase chain reaction. The data suggest that HCV superinfection may not only suppress HBV or terminate the HBsAg carrier state but may also assume the role of HBV as the cause of persistent hepatitis or transaminase elevation.

Adult↗
PubMed1992

Human papillomavirus in benign and malignant ovarian and endometrial tissues.

Ovarian and endometrial cancer tissues were examined for the presence of human papillomavirus (HPV) and the results were compared with the findings in normal tissues by polymerase chain reaction. Putative DNA of HPV types 16 and 18 that target DNA sequences from paraffin-embedded tissues were amplified with paired oligonucleotide primers that encode the E6 gene of HPV. The amplified DNA sequences were then detected with Southern blot hybridization analysis. The HPV DNA sequences were detected in both benign (50% ovarian, 70% endometrial) and malignant ovarian (27.2%) and endometrial (37.5%) tissue samples. Interestingly, eight hepatoma samples were also analyzed as tissue controls. The results were negative in seven, but positive in one with repeated tests. The results suggest that the spread of HPV in the upper genital tract may not be uncommon. The explanation of a positive liver tissue study result will have to await further study.

Adenocarcinoma↗
PubMed1991

Intraamniotic detection of Chlamydia trachomatis deoxyribonucleic acid sequences by polymerase chain reaction.

The presence of Chlamydia trachomatis in cervicovaginal cells and amniotic fluid of pregnant women was examined by culture and by polymerase chain reaction deoxyribonucleic acid amplification methods. Chlamydial deoxyribonucleic acid sequences were found in nine of 31 (29.0%) cervicovaginal cell specimens, five of which also were positive by culture method. Amniotic fluid specimens from two of the nine (22.2%) cervicovaginal chlamydial deoxyribonucleic acid-positive women and none from the remaining 22 cervicovaginal chlamydial deoxyribonucleic acid-negative women were found to contain chlamydial deoxyribonucleic acid. The results underscore the significance and frequency of intraamniotic chlamydial infection in women with urogenital chlamydial infections.

Amniotic Fluid↗
PubMed1991

Human papillomaviruses and small cell carcinoma of the uterine cervix.

The in vitro DNA amplification technique of polymerase chain reaction was used to evaluate the possible presence of human papillomavirus (HPV) in small cell carcinoma of the uterine cervix. None of the 12 cases examined contain detectable amounts of either HPV type 16, 18, 31, or 33 DNA. On the other hand, HPV types 16 and 18 DNA were found in 14 (93.3%) and 9 (60.0%) of 25 invasive cervical squamous carcinoma tissues. The results seem to suggest that these types of HPV are not present or are present in extremely small quantities in cervical small cell carcinoma. Such an absence of HPV DNA makes it unlikely that these types of HPV play any etiological role in the pathogenesis of cervical small cell carcinoma.

Adult↗
PubMed1991

Identification of human papillomavirus DNA sequences in peripheral blood mononuclear cells.

Polymerase chain reaction (PCR) was used to amplify and identify the presence of the DNA of human papillomavirus (HPV) types 6, 11, 16, and 18 in peripheral blood mononuclear cells (PBMCs) of women with and without urogenital HPV infections. HPV DNA of various types was found in PBMCs of 13 of 25 (52.0%) patients with urogenital HPV infections and in none of the 19 control subjects who are free of urogenital HPV infections. The presence of HPV DNA in PBMCs may impair the immunologic functions of the lymphocytes and play a role in the epidemiology of HPV infections and the pathogenesis of HPV-induced diseases.

Base Sequence↗
PubMed1991

Serum hepatitis B virus DNA in hepatitis B virus seropositive and seronegative patients with normal liver function.

The presence of hepatitis type B virus (HBV) DNA in serum specimens from 926 apparently healthy people with normal liver functions was determined by polymerase chain reaction; 41.2% of people with positive results for HBV surface antigen (HBsAg) (94 of 228) and 95.2% of people with positive results for HBV e antigen (HBeAg) (60 of 63) were found to have positive results for serum HBV DNA. On the other hand, serum HBV DNA was found in 11.0% (77 of 698) of HBsAg-negative people and in 13% (69 of 530) of those who had positive results for serum antibodies directed against HBsAg. The results seem to suggest that HBV DNA can be found in a significant portion of apparently healthy people with normal liver function who are either seronegative for HBsAg or seropositive for antibodies directed against HBsAg.

Base Sequence↗
PubMed1991

Detection of human herpesvirus 6 DNA in T and B cell lymphomas.

DNA extracted from tissues of 109 patients with lymphoproliferative disorders, including 40 T-cell lymphomas, 40 B-cell lymphomas, 8 Hodgkin's disease, 13 hyperplasia, 5 infectious mononucleosis, 2 histiocytic medullary reticulosis and 1 Kikuchi's disease, and peripheral blood lymphocytes (PBL) from 17 healthy donors were investigated for the presence of human herpesvirus 6 (HHV-6) DNA sequence by polymerase chain reaction (PCR) and Southern hybridization. The procedures for DNA amplification were composed of the first round of PCR using a pair of primers LL and LR, which were contained in the HHV-6 major capsid gene, and the second round of nested PCR using an internal pair of primers LLN and LRN. Results showed that the prevalence of HHV-6 DNA sequence in human tissues was similar in both B and T cell lymphoma patients and normal adults, and viral heterogeneity was detected in the amplified DNA sequence from local strain of Taiwan as compared to that of U1102 strain from Uganda.

DNA, Viral↗
PubMed1991

Incidence, determinants and significance of delayed clearance of serum HBsAg in chronic hepatitis B virus infection: a prospective study.

To investigate the incidence, determinants and significance of delayed clearance of serum HBsAg in chronic hepatitis B virus infection, a prospective follow-up study was conducted in two consecutive groups of patients. Group I consisted of 984 patients (859 men and 125 women) with biopsy-proven chronic type B hepatitis, whereas group II consisted of 1,598 asymptomatic chronic carriers (998 men and 600 women) with normal serum aminotransferase activity. During a mean follow-up period of 4.0 +/- 2.3 yr, 19 patients (1.9%) of group I cleared HBsAg from their serum, whereas 35 patients (2.2%) in group II did so in a mean follow-up period of 2.7 +/- 1.4 yr. The annual incidence of delayed serum HBsAg clearance was 0.5% in group I and 0.8% in group II (p less than 0.02). The cumulative probability of HBsAg clearance was also higher in group II than in group I (p less than 0.007). Antibodies to HBsAg developed in 9 patients (47.4%) with chronic hepatitis and in 11 (31.4%) asymptomatic carriers who cleared serum HBsAg. Those who were HBeAg negative and those older than 40 at entry and those who exhibited cirrhosis during follow-up had a higher incidence of delayed HBsAg clearance. Gender, initial histological changes and hepatitis delta virus infection did not influence the occurrence of HBsAg clearance. Serum HBV DNA was not detectable by slot-blot hybridization but was still detectable by polymerase chain reaction in serum specimens collected within 1 yr of HBsAg clearance. Liver biopsy performed later in 10 patients showed no significant hepatitis activity or tissue HBV DNA, HBsAg or HBcAg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Hepatitis B virus DNA in cervicovaginal cells.

Hepatitis B virus DNA sequences were detected in seven (12.1%) of 58 cervicovaginal cell specimens that were obtained from pregnant women by polymerase DNA amplification assay. The presence of hepatitis B virus DNA in these cells raises the possibility that infected cervicovaginal cells may be a source through which hepatitis B virus can be transmitted from infected mothers to their newborns and between heterosexual partners.

Base Sequence↗
PubMed1990

Detection of human cytomegalovirus in cervicovaginal cells by culture, in situ DNA hybridization and DNA amplification methods.

The presence of human cytomegalovirus (HCMV) was tested in 388 cervicovaginal cells specimens obtained from the same number of pregnant women. HCMV was detected in 5.41%, 11.6% and 13.9% of these specimens by conventional culture, in situ DNA hybridization and polymerase chain reaction (PCR) methods, respectively. The sensitivities of detecting HCMV by in situ hybridization and PCR methods were 76.2% and 90.5% and the specificities were 92.1% and 90.5%, respectively, when compared with conventional culture method. The PCR compared favourably with both conventional culture and in situ hybridization methods and it may become a valuable and useful tool for the early and rapid detection of HCMV in clinical specimens.

Base Sequence↗
PubMed1990

The detection of Gardnerella vaginalis DNA sequences in uncultured clinical specimens with cloned G. vaginalis DNA as probes.

Cloned Gardnerella vaginalis DNA were selected from a plasmid DNA library constructed with partially restriction endonuclease Hind III-digested genomic DNA of G. vaginalis to serve as DNA probe in detecting G. vaginalis. The level of detection was determined to be approximately 10,000 cells by slot-blot DNA hybridization. This probe DNA will not cross-hybridize with DNA of a number of non-Gardnerella micro-organisms commonly found in female genital tract. The DNA probe-based hybridization test may become a useful tool for the identification of G. vaginalis in uncultured clinical specimens.

Blotting, Southern↗
PubMed1990

Detection of human papillomaviruses in cervicovaginal cells using polymerase chain reaction.

The polymerase chain reaction (PCR) was used to identify human papillomavirus (HPV) in cervicovaginal cells in normal individuals and in patients with cervical intraepithelial neoplasia (CIN). By use of a set of primers encoding the E6 region of the HPV genome, the presence of HPV DNA was demonstrated in the cervicovaginal cells of 43 (42.2%) of 102 normal individuals and in all 12 CIN patients. High sensitivity of the PCR method produced an additional 9 positive results on second sampling from 48 individuals who were initially HPV-negative. On the other hand, 26 (24.3%) of 107 HPV-positive individuals were HPV-negative when sampled a second time 5-7 days later. The data suggested that retest probably should be considered for patients clinically suspected of having HPV infection whose initial test results are negative for HPV DNA. Also, single HPV DNA-positive results should be accepted with caution.

Base Sequence↗
PubMed1990

Detection of Epstein-Barr virus DNA sequences in nasopharyngeal carcinoma cells by enzymatic DNA amplification.

The presence of Epstein-Barr virus (EBV) DNA sequences was examined by the polymerase chain reaction in 50 nasopharyngeal carcinoma (NPC) biopsy specimens and in two primary epithelial tumor cell cultures derived from patients with NPC. The detection limit was a single EBV genome equivalent by agarose gel electrophoresis followed by Southern blot analysis of the amplified products. EBV DNA sequences were detected in all 41 undifferentiated NPC cell specimens, in 2 of 4 moderately differentiated NPC cell specimens, and in 3 of 5 keratinized NPC cell specimens. Undifferentiated NPC cells were also found to contain higher copy numbers of EBV than cells of the other two types of NPC. Our data suggest that EBV replication may be closely associated with the differentiation of NPC tumor cells. The results also demonstrated a sensitive and specific method for the detection of EBV DNA sequences in NPC tumor cells.

Base Sequence↗
PubMed1990

Detection and identification of Mycobacterium tuberculosis by DNA amplification.

The polymerase chain reaction (PCR) was used to identify mycobacterial DNA sequences in uncultured clinical specimens. Two oligonucleotide primers derived from the sequence of a gene that codes for the 65-kilodalton antigen of Mycobacterium tuberculosis amplified DNA from all 11 species of mycobacteria tested. Amplified DNAs of nontuberculosis mycobacteria were found to be approximately 20 to 40 bases shorter than those from M. tuberculosis and Mycobacterium bovis BCG. DNA equivalent to that present in as few as 40 M. tuberculosis cells either alone or in the presence of DNA equivalent to that in 10(6) human cells could be detected. Results from analysis of cultured bacteria and clinical specimens showed PCR was sensitive and specific both in detecting mycobacteria and in differentiating M. tuberculosis and BCG from other species of mycobacteria. The PCR method with the primers reported here may become a useful tool in the early and rapid detection of mycobacterial infections in uncultured clinical specimens.

Base Sequence↗