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Biomedical subjects

L Chow

Publications and source records attributed to L Chow.

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

Detection and differentiation of dengue-1 from Japanese encephalitis virus infections by ABC MAC-ELISA.

An IgM antibody capture enzyme linked immunosorbent assay using avidin biotin complex system (ABC MAC-ELISA) was established for the detection and differentiation of dengue-1 and Japanese encephalitis virus infections. The cut-off value of MAC-ELISA was based on the mean value of optical density at 490 nm of seven negative human sera carried along in each assay multiplied by 2.1. The specificity of MAC-ELISA tested on 200 healthy enrolled male serum was 99.5% and 98.0% for dengue-1 and Japanese encephalitis IgM, respectively. Two hundred and sixty-six acute or followed-up dengue serum specimens which were identified to possess dengue-1 virus by virus isolation technique using C6/36 cell line and monoclonal antibody immunofluorescent assay (IFA) were tested by MAC-ELISA for IgM antibodies to dengue-1 and Japanese encephalitis virus infection. The positivity of IgM antibody for serum collected from day 1 to day 7 after onset of the disease was 0.0%, 0.0%, 7.6% 14.2%, 25.0%, and 77.7% by each consecutive day, correspondingly, for those collected from day 8 to two month was 96.7% overall. By comparison the P/N value of dengue-1 IgM to JE IgM, 98.5% and 96.8% of the dengue-1 and Japanese encephalitis suspected serum specimens could be distinguished from each other, respectively. MAC-ELISA is a convenient, rapid, sensitive and specific method for the detection and differentiation of dengue-1 from Japanese encephalitis virus infections.

Antibodies, Viral↗
PubMed1990

Transoesophageal echocardiography in the longitudinal axis: correlation between anatomy and images and its clinical implications.

Transoesophageal echocardiographic imaging in the longitudinal axis is a recent addition to the non-invasive evaluation of congenital and acquired heart disease. The technique provides unique images of intracardiac anatomy but their interpretation remains difficult. A heart specimen was therefore cut according to the echocardiographic imaging planes to elucidate the morphological details. The results suggested that longitudinal transoesophageal imaging complements the transverse axis approach. It gave new imaging information on the right ventricular outflow tract and the pulmonary trunk, the atrioventricular valves, the interventricular septum, the cardiac apex, and the thoracic aorta. In particular, it showed the entire length of the right ventricular outflow tract. When longitudinal imaging was used in combination with transverse imaging almost all the thoracic aorta could be examined. Imaging in the longitudinal axis may also allow better assessment of the mechanisms of atrioventricular valve regurgitation.

Aorta, Thoracic↗
PubMed1989

Infected atrial myxoma.

A patient is reported in whom a left atrial myxoma was found to be infected with Staphylococcus aureus. The clinical presentation, diagnosis and treatment are described and discussed.

Echocardiography↗
PubMed1989

[MAC-ELISA for the detection of IgM antibodies to dengue type I virus (rapid diagnosis of dengue type I virus infection)].

The commercial rapid diagnostic reagents for Dengue virus infection is still not available at present. An ABC MAC-ELISA (Avidin Biotin Complex IgM Antibody Capture Enzyme Linked Immunosorbent Assay) for the detection of Dengue type I virus infection has been described. IgG purified from high titer (HI = 2560) human anti-flavivirus serum is labelled with biotin for the rapid diagnosis of Dengue type I virus infection. 389 serum specimens of suspected Dengue Fever patients including 226 HI(+) paired sera and 163 HI(-) paired sera which were collected from 1 to 150 days after onset of the disease in 1988 have been assayed for IgM antibodies to Dengue type I virus. Cut off value is based on the mean of OD490 of 162 Dengue negative serum specimens plus 4 SD. The positivity of IgM antibody increased as the viremia disappeared and IgM antibody for Dengue-1 serum specimens collected 9 days after onset of the disease is 100% detectable.

Antibodies, Viral↗
PubMed1989

Genetic homogeneity at the Friedreich ataxia locus on chromosome 9.

Classical Friedreich ataxia, a progressive, neurodegenerative disorder involving both the central and peripheral nervous systems, has been subclassified according to the observed clinical heterogeneity. The variations in the age at onset and in the spectrum and severity of symptoms have previously been interpreted as evidence of genetic heterogeneity. We have studied the linkage between the disorder and closely linked DNA markers in families of distinct ethnic origins, including the "typical" French-Canadians and the Acadian population of Louisiana. The disease in these two populations, both of continental French origin, has a very similar initial clinical picture. However, a marked difference in the rate of progression of the obligatory symptoms after 10 years of apparent disease is observed. A total of 553 individuals from 80 families with 202 affected members have been typed with the chromosome 9 marker MCT112, which we have previously shown to be closely linked to the disease locus. Evidence for linkage was observed in all families with the generation of a combined total lod score of 25.09 at a recombination fraction of theta = .00, providing strong evidence for genetic homogeneity at this locus for the classical form of this disease.

Canada↗
PubMed1988

Peritoneal eosinophilia in patients on continuous ambulatory peritoneal dialysis: a prospective study.

A prospective study on peritoneal eosinophilia was conducted in 23 continuous ambulatory peritoneal dialysis (CAPD) patients for a mean period of 7.9 months. Peritoneal eosinophilia as defined by peritoneal eosinophil count exceeding 100/mm3 was found in 60.8% of patients. Most developed peritoneal eosinophilia within 3 months of the initiation of dialysis, although the phenomenon could occur as early as one day or as late as 6 months after dialysis. Fifty-seven percent of those with peritoneal eosinophilia also had peripheral blood eosinophilia. Although most peritoneal eosinophilic episodes subsided in a month, in one patient the process grumbled on for 150 days. The number of peritonitis episodes was not significantly different between patients with peritoneal eosinophilia and those without. The only distinction between the two groups of patients was that those who developed peritoneal eosinophilia had a significantly (P = .002) higher serum IgE concentration initially as well as throughout the period of observation.

Adolescent↗
PubMed1987

Genetic relationship among human papillomaviruses associated with benign and malignant tumours of patients with epidermodysplasia verruciformis.

Human papillomaviruses (HPVs) 5, 8, 19 and 25 induce macular skin lesions in patients with epidermodysplasia verruciformis. HPVs 5 and 8 are known to prevail in skin carcinomas, which develop in about one-third of these patients. We compared the viral DNAs by heteroduplex analysis and on the basis of partial nucleotide sequences. The colinear genomes were closely related and showed nucleotide sequence homology in the range of 40% to 90%. Homology values between 70% and 80% were observed throughout roughly 4 kb of the heteroduplex molecules as estimated after 'calibration' by partial sequencing. Heteroduplex analysis did not support the hypothesis that the different HPV types arise by recombination and allowed no grouping to correlate with the association with malignant tumours. The upstream regulatory sequences of HPVs 8, 19 and 25 appeared highly conserved but differed from those of previously sequenced papillomaviruses in length, in the TATA motif, in the copy numbers and positions of the ACCGN4CGGT palindrome and of a YGCCAA direct repeat, and in two strictly conserved blocks of 33 and 29 nucleotides.

Base Sequence↗
PubMed1986

The gene for the alpha 1(IV) chain of human type IV procollagen: the exon structures do not coincide with the two structural subdomains in the globular carboxy-terminus of the protein.

Previous studies on the coding sequences of DNAs for the alpha 1(IV) chain of basement membrane collagen demonstrated a striking homology between the first 115 and the second 114 amino acids of the globular (NC1) domain of the protein. Also, alignment of the 12 cysteine residues indicated that the homology was particularly strong around three paired clusters of amino acids around cysteine residues. Here we have isolated a cosmid clone containing the 3'-end of the gene. Analysis of the clone and previously isolated lambda clones demonstrated that the intron--exon patterns of the gene does not reflect the homology in the protein. Therefore the homology cannot have arisen in any simple manner from gene duplications.

Amino Acid Sequence↗
PubMed1986

Large introns in the 3' end of the gene for the pro alpha 1 (IV) chain of human basement membrane collagen.

Using a recently characterized cDNA clone (HT-21) coding for the pro alpha 1 (IV) chain of human type IV procollagen, we have isolated three clones from a bacterio-phage lambda Charon 4A library of human genomic DNA. The intron/exon structure of the pro alpha 1 (IV) genomic clones was analyzed by heteroduplex electron microscopy and nucleotide sequencing. The analysis showed that the introns separating exons 2-9 are large and have a total length of over 12,000 base pairs (bp). Six of seven exons at the 3' end of the gene coded for -Gly-Xaa-Yaa-repeats of the collagenous part of the chain. Five of the -Gly-Xaa-Yaa- coding exons (numbers 5-9) varied in size between 72 bp and 134 bp, and none of them were 54 bp or multiples thereof. A sixth exon (exon 4) was a junction exon containing 71 bp coding for -Gly-Xaa-Yaa- sequences and 142 bp coding for the carboxyl-terminal noncollagenous domain (NC-1). The seventh exon (exon 3, 178 bp) coded for sequences of the NC-1 domain. Five of the six -Gly-Xaa-Yaa- coding exons began with the second base coding for glycine, and only one exon began with a complete glycine codon at the 5' end. The results (i) suggest that the gene for the pro alpha 1(IV) chain of human basement membrane collagen is significantly larger than the genes for fibrillar collagens and (ii) show that it lacks the 54-bp exon repeats characteristic of fibrillar collagen genes.

Base Sequence↗
PubMed1986

AIDS in a Hong Kong Chinese.

A young Hong Kong Chinese male patient with fever of unknown origin is presented. The diagnosis of acquired immunodeficiency syndrome was made only 5 months after the onset of his illness. The lack of awareness of the syndrome might account for the delay in the diagnosis. The legal attitude towards homosexuality might have an adverse effect on epidemiological studies of AIDS in Hong Kong.

Acquired Immunodeficiency Syndrome↗
PubMed1985

[Clinical evaluation of a domestically prepared enzyme immunoassay kit for the detection of hepatitis B surface antigen].

National Institute of Preventive Medicine (NIPM) has succeeded in the development of an enzyme immunoassay (EIA) kit for detection of hepatitis B surface antigen. The sandwich principle was used for the test. Guinea pig anti-HBs IgG was used for coating microtiter plates and Horseradish peroxidase was conjugated with goat specific anti-HBs. Its stability is longer than 4 months. The lowest detectable dose is 0.7 ng/ml or better for subtype ad of HBsAg tested with Hepatitis Sensitivity Panel, Bureau of Drug and Food, Department of Health. The regression curve was determined by testing 66 samples with Auszyme II (EIA Kit. Abbott Lab.) and NIPM Kit, while Auszyme II used as a reference kit. The two EIA kits correlated well with a coefficient of determination (r2) of 0.86. Evaluation on 1,157 patients' and officers' serum samples in Tri-Service General Hospital showed that the positive rate was 24.7% (286/1,157) by RIA (Clinical Assays, Travenol Lab., USA) and that of NIPM EIA Kit was 24.4% (282/1,157). There was no statistical significance in terms of positive rate (p greater than 0.05). The positive rates of 534 blood donors are 22.1% (118/534) and 21.9% (117/534) respectively. Another evaluation on 974 serum samples in National Taiwan University Hospital showed that the positive rate was 27.2% (265/974) by Ausria II-125 (RIA. Abbott Lab.) and that of NIPM EIA Kit was 27.4% (267/974). The undetectable rate and false positive rate of NIPM EIA Kit were 0.41% (4/974) and 0.62% (6/974) respectively. In comparison with four other kind of commercial EIA Kits, the results of NIPM EIA Kit were satisfactory also. We have scaled up the reagent preparations for the kit, except the antibody coated microtiter plate preparation. At the end of March 1985 we will supply 850 EIA kits for the Development Center for Biotechnology for their hepatitis B vaccine production program.

Hepatitis B Surface Antigens↗