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Biomedical subjects

C K Ho

Publications and source records attributed to C K Ho.

178 records · Page 10Linked to original sources
PubMed1979

Immune mechanisms against canine distemper. I. Identification of K cell against canine distemper virus infected target cells in vitro.

Canine peripheral blood lymphocytes, polymorphonuclear leucocytes (PMN) and monocytes (macrophages) were obtained by various cell separation techniques and were tested for their cytotoxic capacity against antibody-sensitized canine distemper virus (CDV) infected Vero cells by an in vitro chromium release assay. Canine lymphocytes were found to destroy CDV infected target cells effectively, while neither PMN nor monocytes (macrophages) could do so. The active lymphocyte was characterized by various rosetting techniques to be a non-T and a non-B lymphocyte. These cells bear no surface immunoglobulin (SIg-) but possessed both Fc receptors (Fc+) and complement receptors (EAC+) suggesting that these cells are neither classical T nor B cells. The possible roles of this K cell in the resistance against canine distemper are discussed.

Animals↗
PubMed1978

Immune effector cell activity in canines: failure to demonstrate genetic restriction in direct antiviral cytotoxicity.

Experiments were undertaken to establish whether the cytotoxic activity of canine immune effector cells against viral antigens was affected by the genotype of the target cell (genetic restriction). Puppies from three different breeds were infected with vaccinia virus, and the peripheral blood leukocytes were collected at various times for measurement of their cytotoxicity against autologous and heterologous vaccinia virus-infected and uninfected skin fibroblasts. In all cases cytotoxicity only occurred against virus-infected targets, and there was no consistent evidence of preferential killing of autologous targets. Several indirect approaches were used to demonstrate that direct, presumably T cell, cytotoxicity was being measured rather than antibody-dependent cell cytotoxicity. On the basis of the evidence from cross mixed-lymphocyte assays and cell-mediated lympholysis assays, the dogs were shown not be be identical with respect to their histocompatibility antigens. The significance of our findings to the phenomenon of genetic restriction as observed for mouse-derived immune effector cells is briefly discussed.

Animals↗
PubMed1978

Isolation of various canine leucocytes and their characterization by surface marker analysis.

Various techniques were used to separate canine peripheral blood leucocytes into populations enriched in lymphocytes, polymorphonuclear leucocytes, phagocytic mononuclear cells (monocytes) and macrophages. Surface markers on each cell population were determined by rosette formation. Fc receptors for IgG and complement receptors (C3b and C3d) were present on PMN, monocytes, macrophages as well as on a sub-population of lymphocytes. Purification of the lymphocytes into T-and B-cell-enriched populations revealed that these receptors were present only on the B lymphocytes and not on the T lymphocytes. In addition, a third lymphocyte population, which did not possess surface immunoglobulin, and Fc receptor but not the complement receptor. None of the cell populations exhibited C4 complement receptors or Fc receptors for IgM. When different cell populations were tested for their ability to form rosettes directly with human type 'O' red blood cells it was found that most populations could rosette, suggesting that this technique could not be used as a specific marker for canine T lymphocytes.

Animals↗
PubMed1976

Multiple sebaceous adenomas and internal malignant disease: a case report with chromosomal analysis.

A case of multiple sebaceous adenomas associated with internal malignant disease is further documented. Thirteen similar cases reported in the literature are also reviewed. We support the thesis that this association represents a unique syndrome. It can be seen in both sexes and usually is manifested during the fifth and sixth decades. A family history of malignant disease was revealed among seven of the nine cases mentioned. Of the other skin lesions, keratoacanthoma is also frequently seen. The internal malignant tumors most commonly afflict the gastrointestinal tract, especially the large intestine. With proper treatment the internal tumors appear to be of a low degree of malignancy. However, these patients have a propensity to develop muliple visceral tumors and require periodic follow-up. Some patients develop skin tumors prior to the discovery of internal malignant disease, an event that offers some prognostic value. Chromosomal study of the cultured blood lymphocytes by the Giemsa banding technique failed to reveal any abnormality.

Adenocarcinoma↗
PubMed1975

Congenital malformations. Cleft palate, congenital heart disease, absent tibiae, and polydactyly.

A girl had cleft palate, micrognathia, Wormian bones, congenital heart disease, dislocated hips, absent tibiae, bowed fibulae, preaxial polydactyly of the feet, and abnormal dermal patterns at birth. She was born after a pregnancy complicated by exposure to multiple medications. This combination of malformations may represent a distinct entity unrelated to the medication or may be a complication of the intrauterine drug exposure.

Abnormalities, Drug-Induced↗
PubMed1975

Ocular colobomata, cardiac defect, and other anomalies: a study of seven cases including two sibs.

An association of ocular colobomata and congenital heart disease was observed in seven patients. Two of these were maternal half sisters whose mother also had ocular colobomata. All the patients had normal karyotypes. There was a high incidence of other associated abnormalities involving the central nervous, skeletal, and urogenital systems. Discovery of an ocular coloboma should alert the clinician to search for other abnormalities.

Abnormalities, Multiple↗
PubMedDate not supplied

Establishment of a work-related diseases surveillance system in Taiwan, Republic of China.

BACKGROUND: The occurrence of occupational illness and injury has been seriously underestimated in Taiwan, which subsequently contributes to difficulties in performing effective control of occupational hazards and implementing intervention programs for protecting workers. METHODS: Based on the successful experience of the nationwide blood lead level surveillance program, the Department of Health, the Executive Yuan, Taiwan, Republic of China, has established a work-related diseases surveillance system. This government-administered system requests practicing physicians to report the suspected cases suffering from six categories of work-related disorders. RESULTS: An occupational illness and injury surveillance program in Taiwan has been in operation since June of 1995. CONCLUSION: Background information of work-related diseases obtained from this surveillance system will be useful for providing better management of available resources for occupational medicine, for preventing hazards, and for enforcing occupational diseases prevention programs. Our experience in establishing this surveillance system will be used in other countries and settings.

Disease Notification↗
PubMedDate not supplied

Assessment of coke oven emissions exposure among coking workers.

Coking workers are regularly exposed to coke oven emissions, which consist primarily of polycyclic aromatic hydrocarbons and volatile organic compounds. This study measured the workers' exposure to the benzene soluble fraction of total particulates (BSF). The study population consisted of 88 coking workers as an exposure group and 59 referents. Personal breathing-zone samples of BSF and total particulates were taken from all study subjects for 3 consecutive days. The highest BSF concentrations were found among the topside oven workers (geometric mean; range) (microgram/m3): lidman (515; 72-18, 181), tar chaser (432; 51-4334), and larry car operator (185; 55-649). The lowest was 7 micrograms/m3 in the referents. Among the samples at the topside oven 84% exceeded the Occupational Safety and Health Administration standard (150 micrograms/m3 BSF). The percentage of BSF in total particulates varied across job classifications, ranging from 0.3% in wharfmen to 24% in tar chasers. Area sampling indicated that the BSF concentration at the topside area was sixtyfold higher than that at the administrative area, which was approximately 2 km from the coke oven plant.

Air Pollutants, Occupational↗
PubMedDate not supplied

Suppression of vincristine-mediated cytotoxic activity by mitoxantrone in human cell lines.

In the present study, we used different cell lines to determine the anticellular effect of a combination of mitoxantrone (MXT) and vincristine (VCR). In all the cell lines tested, most cells (approximately 90%) in cultures with VCR (0.01-1 microM) alone died in the 3 days following exposure, while those with VCR and MXT (0.1-1 microM) invariably survived much longer (6-9 days). Based on the MTT and the 3H-thymidine uptake assays, it was shown that the antagonistic effect of MXT was optimal at 0.1-1 microM and when applied simultaneously. Our results showed that neither modulation of drug accumulation nor inhibition of tubulin assembly could account for the antagonistic effect of MXT. Furthermore, the cytotoxic effects of VCR and/or MXT had no correlation with c-myc gene expression and DNA fragmentation was not observed. Flow cytometry revealed that while most cells (> 90%) exposed to VCR alone for 16-24 h were arrested at the G2/M phase, a fraction of cells were able to escape mitotic arrest when MXT was also present. These results suggest that the use of MXT in conjugation with VCR for the treatment of cancers should be applied with caution.

Antineoplastic Agents↗