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Biomedical subjects

J H Ho

Publications and source records attributed to J H Ho.

At least 73 records · Page 4Linked to original sources
PubMed1980

Establishment of a cell line (NPC/HK1) from a differentiated squamous carcinoma of the nasopharynx.

A long-term cell culture epithelioid cell line was established from a recurrent squamous carcinoma of the nasopharynx of a Chinese male 17 1/2 years after radiation therapy. The cell line, designated NPC/HK1, has been passed 72 times over a period 1 year. The cells have been shown by light and electron microscopies to be of the squamous epithelial type. When they were transplanted subcutaneously into the back of athymic nude BALB/c (nu/nu) mice, tumors developed at the sites of inoculation, which on histological examination were shown to be well-differentiated squamous carcinomas, similar in morphology to the recurrent human tumor from which they were derived. Karyotypic analysis of cells from the cell line demonstrates an aneuploid human type with a modal chromosome number of 74 with both numerical and structural aberrations. Viral particles or Epstein-Barr viral nuclear antigen (EBNA) has not been demonstrated in the cells from the primary culture or several of the subcultures tested. The presence of EBNA in touch smears prepared from the biopsy tissue was inconclusive. Infection of the subcultured cells with EBV from P3HR1 and B95-8 cells was unsuccessful.

Adult↗
PubMed1979

Preserved foods as possible cancer hazards: WA rats fed salted fish have mutagenic urine.

Six batches of food traditionally and commonly consumed by southern Chinese, including two samples of dried shrimps and four samples of different species of salted fish, were tested for mutagenic properties using Salmonella typhimurium TA98 and TA1000. Mutagenic activities toward both tester strains were found in all preparations. In most cases, these activities were enhanced by liver microsomal activation. Urine collected from experimental rats regularly fed salted fish also showed mutagenic activity. The level of this activity decreased markedly when the experimental rats were transferred from a salted fish diet to Purina rat chow. Our data suggested the presence of mutagenic/carcinogenic substances in some local preserved foods and at least one of them, salted fish, has been suspected on epidemiological and experimental evidence to be a possible co-carcinogenic factor in the development of nasopharyngeal carcinoma in southern Chinese. Our finding is compatible with this hypothesis.

Animal Feed↗
PubMed1979

Bronchial cancer in Hong Kong, 1976-77: a preliminary report.

A case-control study of the relationship of bronchial cancer to smoking was conducted during 1976-77 in Hong Kong, in which we took particular note of the histologic type of the tumor. A total of 132 male and 111 female patients were interviewed. The association with smoking was more evident in males than it was in females, and squamous and small-cell type carcinomas, as a group, appeared to be more closely associated with smoking than did adenocarcinomas and large cell tumors. Of the women with bronchial carcinoma, 44% were nonsmokers; 79% of their tumors were adenocarcinomas or large cell carcinomas. For the women in this group, no association could be detected with place of residence, occupation, or use of kerosene for cooking.

Adenocarcinoma↗
PubMed1979

Some epidemiologic observations on cancer in Hong Kong.

The average incidence by age-group per 100,000 for both sexes and the age-standardized incidence rates for the 10 most common cancers in Hong Kong for 1974 were determined. A comparison between the incidence and death rates for these 10 cancers indicated that a good coverage of the actual incidence has been achieved by the Cancer Registry for cancers of the nasopharynx, bronchus, esophagus, colon, rectum, breast, cervix, and bladder, but it was incomplete for cancers of the liver and stomach. A study of their age-specific incidence curves showed a sharp rise in the curve after age 20-24 in cancers of the nasopharynx and liver (males), after age 25-29 in cancers of the cervix and breast (females), and after age 35-39 for the remaining tumors studied; thus a difference in the period of life at which carcinogenesis was initiated was indicated. Epidemiologic observations on nasopharyngeal, esophageal, hepatocellular, and uterine cervical carcinoma were compared, and it is believed that epidemiology is the key to the solution of the cancer problem in Hong Kong.

Adolescent↗
PubMed1978

Delayed hypersensitivity reactions of cancer patients to antigens on lymphoid cell lines.

Four-hundred and fifty nine cancer patients were skin tested with extracts from five lymphoid cell lines. More than 50% of patients with lymphoma had positive skin tests with the extracts prepared from the cell line derived from Burkitt's lymphoma (BL) and more than 50% of nasopharyngeal carcinoma (NPC) patients reacted to the NPC-derived cell line extracts. Although the significant association between patient diagnosis and orgin of cell lines suggested that tumor-associated antigens were responsible for the pattern of delayed hypersensitivity, problems in standardization of antigen potency and non-specificity need to be resolved before this in vivo assay achieves its full potential.

Antigens, Neoplasm↗
PubMed1978

Morphological transformation of nasopharyngeal epithelial cells in vitro by Epstein-Barr virus from B95-8 cells.

Tissue fragments of fresh biopsy specimens from the non-neoplastic NP mucosa of 20 subjects, from the tumours of 10 NPC patients, from the mucosa of freshly removed tonsils from nine subjects and from the primary lesions of seven patients with malignancies of the upper respiratory or alimentary tract other than NPC were infected with EBV derived from B95-8 cells. A significantly higher frequency of growth stimulation and a greater mean growth ratio between infected and uninfected fragments from the same source were observed in the non-neoplastic NP mucosa specimens than in the others. In addition, the growth characteristics and the morphology of the cells in the infected non-neoplastic NP mucosal explants resembled those of transformed cells; but whether they possess malignant potential is being investigated.

Carcinoma↗
PubMed1978

In vivo cell-mediated immunity in Chinese patients with nasopharyngeal carcinoma.

Delayed hypersensitivity to antigens derived from four EBV-related (KHLY 28, Raji, F265 and NC37) and one EBV-unrelated (Molt) T-lymphoid cell lines and to standard antigens (Trichophyton, Candida albicans and streptokinase/streptodornase) was measured in 104 NPC patients and 24 patients with other cancers. Of the NPC patients with non-disseminated disease, 55/86 (63.2%) had a positive skin reaction to HKLY 28 extract, compared with only 1/18 (5.6%) OC patients with non-disseminated disease. The frequencies of these NPC patients with positive skin reactions to the other cell-line extracts were significantly lower (1.7-5.4%). From the preliminary results of a longitudinal study, skin testing with this particular crude membrane extract from HKLY 28 cells appears to be of little practical value in monitoring the clinical evolution of NPC, although a significant association between clinical evolution and certain patterns of skin reactivity response to the extract was found in about two-thirds of the cases analysed.

Antigens↗
PubMed1978

Stage classification of nasopharyngeal carcinoma: a review.

Various stage classifications of NPC have been described and discussed. Treatment results have been reported for the various stages for only four of these classifications; the correlation between stage and treatment results was best in the classification of the author.

Carcinoma↗
PubMed1978

Analysis for volatile nitrosamines in salt-preserved foodstuffs traditionally consumed by southern Chinese.

Six types of salted fish and 10 other sorts of salted food products traditionally consumed by southern Chinese were analysed by GC-MS for the presence of volatile nitrosamines. The detection limit in the original raw food was 1 microg/kg for each nitrosamine. Only NDMA, in the range of 1-35 microg/kg, could be detected, in four of the six types of salted fish samples examined; and no nitrosamines were found in the other salted food products.

Animals↗
PubMed1978

Nasopharyngeal carcinoma and histocompatibility antigens.

New data are presented concerning the relationship between NPC and HLA antigens among Chinese. When attention is confined to newly diagnosed cases, it can be shown that, apart from the increased risk associated with the joint occurrence of A2 and B-Sin 2, there is also an increased risk associated with BW17 and a decrease in risk associated with A11. Among long-term survivors, however, BW17 is appreciably decreased, whereas A2 in the absence of B-Sin 2 or BW17 is increased. Among Malays, a non-Chinese group, there is an excess among NPC patients of a locus A blank, a blank which is probably associated with the AW19 complex.

Carcinoma↗
PubMed1978

Carcinoma of the nasal and paranasal regions in rats fed Cantonese salted marine fish.

Cantonese salted fish is suspected on epidemiological grounds to be an etiological factor in human NPC. To determine whether this food contains a carcinogen which acts on the upper respiratory epithelial lining, WA albino rats and Syrian golden hamsters were given Cantonese salted fish in their diet for one to two years from the age of one month and examined for tumours in that area. Three of 20 treated rats, but no control rats and no treated or control hamsters, developed carcinomas (two adenocarcinomas and one undifferentiated) in the nasal or paranasal sinus cavities after 12 to 24 months' treatment. NDEA was given orally to a similar group of animals as a positive control, and NDMA, the only volatile nitrosamine detected in salted fish, was added to the drinking-water of a third group. Three of 14 NDEA-treated rats developed adenocarcinomas in the nasal cavities, but none of the other animals developed nasal or paranasal tumours. These findings lead us to suspect that salted fish may contain a carcinogen or procarcinogen that can act systematically on the epithelial cells of the nasal and paranasal cavities.

Adenocarcinoma↗
PubMed1977

Unilateral breast-feeding and breast cancer.

Women of fishing villages in Hong Kong by custom breast-feed with only the right breast. The hypothesis that the unsuckled breast may have an altered risk of cancer development was investigated. Records of the radiotherapy divisions in Hong Kong between 1958 and 1975 were searched, and breast-cancer patients were interviewed for a detailed history of lactation. The overall left/right ratio of cancer in the breasts of 2372 women with unilateral breast carcinoma was 0-97, indicating that breast cancer was equally distributed between the two sides. Of 73 patients with a history of exclusively one-sided breast-feeding, 27 of 34 patients aged 55 or over (79-4%) and 19 of 39 patients under age 55 (48-7%) had a carcinoma in the unsuckled breast. Comparisons of patients who had nursed unilaterally with nulliparous patients and with patients who had borne children but had not breast-fed indicated a highly significant increased risk of cancer in the unsuckled breast. No statistically significant differences in laterality of breast cancer were found in 52 patients who had for convenience nursed to a greater extent from one side than the other. This study indicates that in post-menopausal women who have breast-fed unilaterally, the risk of cancer is significantly higher in the unsuckled breast and that breast-feeding may help to protect the suckled breast against cancer.

Adult↗
PubMed1977

Neutralizing EBV-specific IgA in throat washings of nasopharyngeal carcinoma (NPC) patients.

Throat washings from 26 nasopharyngeal carcinoma (NPC) patients from Hong Kong and Tunisia were studied for the presence of transforming EBV. Only six (23%) were found positive which led to the hypothesis of a neutralizing factor in such salivas. The search for EBV-specific antibodies showed that NPC saliva contained neutralizing VCA and EA IgA (54 and 27% respectively) and VCA and EA IgG (73 AND 54% respectively). Both transforming and non-transforming throat washings contained virus particles as visualized by electron microscopy, but in non-transforming salivas (containing IgA and IgG) the particles were found to be clumped. Comparative study of throat washings from patients with Burkitt's lymphoma (BL); infectious mononucleosis (IM), immunodeficiencies, other cancers, and healthy subjects showed that IgA were restricted to NPC cases.

Antibodies, Viral↗
PubMed1977

Cold lymphocytotoxic antibodies in nasopharyngeal carcinoma.

Sera from patients with nasopharyngeal carcinoma (NPC), a disease associated with Epstein-Barr virus (EBV), were found to be cytotoxic at 15% degrees C in the presence of complement for a panel of human lymphocytes, with a higher frequency than those of matched controls. The cold lymphocytotoxic antibodies (LTA) responsible for this activity have the same properties as those described in sera from individuals with acute viral infections. The frequency and geometric mean titres (GMT) of LTA varied with the origin of the patient (Chinese larger than North African larger than Caucasian) and the stage of the disease (Stage IV larger than Stage I). A positive correlation between LTA and anti-EBV titres was found with regard to antibodies to the viral capsid antigen (VCA) and the EBV-specified nuclear antigen (EBNA). The absence of correlation between LTA and anti-early antigen (EA) titres probable reflects the complex relationships existing between viral infection and LTA production, but is compatible with the hypothesis that LTA acts as an immune regulatory mechanism in viral infections.

Antibodies, Viral↗