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Biomedical subjects

J H Ho

Publications and source records attributed to J H Ho.

At least 55 records · Page 3Linked to original sources
PubMed1987

Measurements of passive smoking and estimates of lung cancer risk among non-smoking Chinese females.

Lifetime exposures to environmental tobacco smoke from the home or workplace for 88 "never-smoked" female lung cancer patients and 137 "never-smoked" district controls were estimated in Hong Kong to assess the possible causal relationship of passive smoking to lung cancer risk. Relative risks based on the husband's smoking habits, or lifetime estimates of total years, total hours, mean hours/day, or total cigarettes/day smoked by each household smoker did not show dose-response results. Similarly, when such categories as mean hours/day, or earlier age of initial exposure, were combined with years of exposure, there were no apparent increases in relative risk. However, when the data were segregated by histological type and location of the primary tumor, it was seen that peripheral tumors in the middle or lower lobes, or, less strongly, squamous or small-cell tumors in the middle or lower lobes, had increasing relative risks that might indicate some association with passive smoking exposure.

China↗
PubMed1987

Symptomatic hypothalamic-pituitary dysfunction in nasopharyngeal carcinoma patients following radiation therapy: a retrospective study.

Endocrine assessment was performed in 32 relapse-free southern Chinese patients (21 males and 11 females, aged 27-50 years at the time of assessment) 5-17 years following radiation therapy (RT) alone for early nasopharyngeal carcinoma (NPC). Initial screening was done using questionnaires emphasizing on impaired sexual function and menstrual disturbance plus measurement of serum levels of thyroxine, free thyroxine index, thyrotropic hormone, prolactin, and additionally testosterone for males only. Those showing abnormalities were subjected to detailed pituitary function tests. Hypothalamic-pituitary dysfunction was found in 7 female patients and only 1 male patient. A delayed TSH response to thyrotropin releasing hormone suggesting a hypothalamic disorder was seen in 6 of the affected female patients, and hyperprolactinaemia in also 6. None of the patients had evidence of diabetes insipidus. Hypopituitarism became symptomatic 2-5 years after RT with a mean latent interval of 3.8 years. A practical protocol for regular endocrine assessment for NPC patients after RT has been proposed. Multiple linear regression analysis of the radiotherapeutic data from the 11 female patients indicates that the likelihood of late occurrence of symptomatic hypothalamic-pituitary dysfunction following RT is dependent on the TDF of the target dose to the nasopharyngeal region and the height of the upper margin of the opposed lateral facial fields above the diaphragma sellae (coefficient of multiple correlation = 0.9025). Except when the sphenoid sinus or the middle cranial fossa is involved, it is advisable to set the height of the upper margin of the lateral facial field at a level no higher than the diaphragma sellae. The hypothalamus and possibly the pituitary stalk as well may sustain permanent damage by doses of radiation within the conventional radiotherapeutic range for carcinomas.

Adult↗
PubMed1987

Adjunctive chemotherapy to radical radiation therapy in the treatment of advanced nasopharyngeal carcinoma.

Sixty-eight consecutive patients with previously untreated nasopharyngeal carcinoma (NPC) with advanced cervical lymph nodal metastases were studied retrospectively for the effectiveness of combining chemotherapy with radical radiation therapy (RT). In 1981 and 1982, 36 patients were treated with radical radiation therapy alone (arm 1). In 1983, 13 patients were given 2 courses of VBMF prior to RT (arm 2). In 1984, 19 patients were given radical RT sandwiched between 2 courses of PVBMF before and 2 after (arm 3). The three arms were comparable in patient characteristics with similar stages of the disease, sex, age distribution, and rates of completion of the prescribed treatments. There was no significant difference in actuarial or disease-free survival between arm 1 and 3 or arm 2 and 3, but arm 1 compared favorably with arm 2 in actuarial survival (X2 = 9.533, p = 0.002). The distant relapses in arms 2 and 3 occurred at significantly shorter times after diagnosis than those in arm 1 (t = 4.1083, p = 0.0001). Postponement of radiation therapy by chemotherapy might have accounted for the earlier distant relapses in arm 2 and 3. Radiation therapy alone given in radical dose had been demonstrated to achieve significantly more complete responses in cervical nodal metastases than either forms of chemotherapy (VBMF or PVBMF) given just two courses prior to radiation therapy (p less than 0.00003). More controlled clinical trials must be completed before acceptance of chemotherapy as part of a standard radical treatment for advanced nasopharyngeal carcinoma with advanced cervical lymph nodal metastases. In all future trials, closer integration in time sequence between the two treatment modalities is indicated. Meanwhile cervical nodal status (CR vs, PR plus NR) at the end of any treatment was shown to be of paramount prognostic significance.

Actuarial Analysis↗
PubMed1987

Early effects of cranial irradiation on hypothalamic-pituitary function.

Hypothalamic-pituitary function was studied in 31 patients before and after cranial irradiation for nasopharyngeal carcinoma. The estimated radiotherapy (RT) doses to the hypothalamus and pituitary were 3979 +/- 78 (+/- SD) and 6167 +/- 122 centiGrays, respectively. All patients had normal pituitary function before RT. One year after RT, there was a significant decrease in the integrated serum GH response to insulin-induced hypoglycemia. In the male patients, basal serum FSH significantly increased, while basal serum LH and testosterone did not change. Moreover, in response to LHRH, the integrated FSH response was increased while that of LH was decreased. Such discordant changes in FSH and LH may be explained by a defect in LHRH pulsatile release involving predominantly a decrease in pulse frequency. The peak serum TSH response to TRH became delayed in 28 patients, suggesting a defect in TRH release. Twenty-one patients were reassessed 2 yr after RT. Their mean basal serum T4 and plasma cortisol levels had significantly decreased. Hyperprolactinemia associated with oligomenorrhoea was found in 3 women. Further impairment in the secretion of GH, FSH, LH, TSH, and ACTH had occurred, and 4 patients had hypopituitarism. Thus, progressive impairment in hypothalamic-pituitary function occurs after cranial irradiation and can be demonstrated as early as 1 yr after RT.

Adult↗
PubMed1986

Malignant lymphoepithelial lesion of the salivary gland.

Eight cases of malignant lymphoepithelial lesion (MLEL) of major salivary glands, seven of which occurred in Southern Chinese patients, are reported. All but two of the patients were older than 40 years of age; there were five male and three female patients. The parotid and submandibular glands were the sites of origin in equal numbers of cases. Six patients had elevated titers of serum IgA against Epstein-Barr virus capsid antigen. Seven remained well after surgery and local radiation therapy, and one died of miliary tuberculosis without evidence of residual neoplasm. Histologically, MLELs were characterized by syncytial clumps of large cells with vesicular nuclei and prominent nucleoli, admixed with abundant small lymphocytes and plasma cells. Two features not emphasized previously in the literature were the presence of reactive histiocytes in some epithelial islands, producing a starry sky pattern, and perineural invasion, which was identified in four cases. The tumor cells showed strong immunostaining for cytokeratin. The literature concerning this rare tumor is reviewed, and the differential diagnosis between MLEL and benign lymphoepithelial lesion, metastatic undifferentiated carcinoma, and malignant lymphoma is discussed.

Adolescent↗
PubMed1986

Hypothalamic hypopituitarism following cranial irradiation for nasopharyngeal carcinoma.

Eight patients, one male and seven females, with no pre-existing hypothalamic-pituitary disease, who developed symptoms of hypopituitarism following cranial irradiation for nasopharyngeal carcinoma were studied 5 years or more after radiotherapy. All were GH deficient. Four of the patients with no GH response during insulin tolerance tests (ITT) showed increased GH in response to synthetic human growth hormone releasing factor (GRF-44). Four patients had impaired cortisol responses to ITT, and gradual but diminished cortisol responses to ovine corticotrophin releasing factor (CRF-41). There was no significant difference between mean peak increments in response to ITT and those in response to CRF-41. TSH responses to TRH were delayed in five and absent in two patients; four of these had low free T4 index. Prolactin was raised in all seven women and increased further in response to TRH. Two patients had impaired gonadotrophin responses to LHRH. None of the patients had clinical or biochemical evidence of diabetes insipidus. These data suggest that post-irradiation hypopituitarism in these patients results from radiation damage to the hypothalamus leading to varying degrees of deficiency of the hypothalamic releasing or inhibitory factors.

Adult↗
PubMed1986

Enzyme-linked immunosorbent assay of antibodies to Epstein-Barr virus nuclear and early antigens in patients with infectious mononucleosis and nasopharyngeal carcinoma.

A sensitive enzyme-linked immunosorbent assay was used to measure titers of IgG antibodies against bacterially synthesized Epstein-Barr virus nuclear antigen and early antigen in sera from 100 healthy North Americans, 40 North American patients with infectious mononucleosis, and 48 Asian patients with nasopharyngeal carcinoma. All healthy persons previously infected with Epstein-Barr virus had antibodies to nuclear antigen, and 70% had very low but detectable antibody titers to early antigen. In contrast, patients with mononucleosis had nondetectable or very low levels of antibodies to nuclear antigen and high antibody levels to early antigen. High levels of antibody to early antigen also were seen in patients with nasopharyngeal carcinoma, and a decrease in this response during the first 12 months after diagnosis and treatment was a significant prognostic indicator of survival. The probability of survival was 75% for patients whose antibody concentration to early antigen remained constant or decreased, and near 0% for patients with increasing levels of antibody.

Antibodies, Viral↗
PubMed1986

Cantonese-style salted fish as a cause of nasopharyngeal carcinoma: report of a case-control study in Hong Kong.

Two hundred fifty incident cases of nasopharyngeal carcinoma under age 35 years in Hong Kong Chinese and an equal number of age- and sex-matched friend controls were interviewed. Mothers of cases and controls were interviewed also, if available, to obtain information on childhood events concerning the study subjects. Consumption of Cantonese-style salted fish during all time periods was significantly associated with nasopharyngeal carcinoma; the association was especially strong during childhood. The relative risk for having Cantonese-style salted fish as one of the first solid foods during weaning was 7.5 (95% confidence limits, 3.9, 14.8), and the relative risk for consuming the food at least once a week compared to less than once a month at age 10 years was 37.7 (95% confidence limits, 14.1, 100.4). It is estimated that over 90% of young nasopharyngeal carcinoma cases in Hong Kong Chinese can be attributed to consumption of this food during childhood.

Adult↗
PubMed1986

Parotid swelling as the first manifestation of nasopharyngeal carcinoma: a report of two cases.

Nasopharyngeal carcinoma usually presents with enlargement of upper cervical lymph nodes, epistaxis, postnasal discharge, aural symptoms or cranial nerve palsy. Parotid swelling as the first and presenting symptom creates a diagnostic problem to both clinicians and pathologists. The authors report here two such cases to draw attention to this diagnostic problem and discuss the therapeutic implications.

Adult↗
PubMed1985

An analysis of some risk factors for lung cancer in Hong Kong.

Lung cancer has been the major cause of cancer death in Hong Kong for more than a decade. Although it is known that some 95% of male cases can be attributed to smoking, the etiological factors in women remain elusive. Among "never-smoked" female cases, increases in attributable risk from passive smoking were limited to only some of the histological types of lung carcinomas, and an overall analysis of all types did not reveal any significant increase in relative risk from this source. Other environmental factors which encourage bronchial irritation are suspected. Methodological differences may explain the differences in proportional distributions of histological lung tumor types noted between previous reports, and the risk values attributed therein to active and passive smoking.

Adolescent↗
PubMed1985

An analysis of multiple mechanisms of adenosine toxicity in baby hamster kidney cells.

Analysis of the response of baby hamster kidney cells to adenosine in the presence of the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine has revealed two distinct mechanisms of toxicity. The first is apparent at low concentrations of adenosine (less than 5 microM) and is dependent upon the presence of a functional adenosine kinase. The initial toxicity is abolished by uridine, is unrelated to the inhibition of ribonucleotide reductase, and is accompanied by a decrease in the size of the pyrimidine nucleotide pool. Toxicity at higher concentrations of adenosine is adenosine kinase independent and is potentiated by homocysteine thiolactone. An elevation in the intracellular level of S-adenosylhomocysteine, which was observed following treatment with higher concentrations of adenosine (greater than 10 microM), is believed to mediate toxicity at these levels. Interestingly, BHK cells were resistant to intermediate levels of adenosine. The mechanism of resistance is currently unknown, but appears unrelated to a lack of inhibition of adenosine deaminase. It is proposed that substrate inhibition of adenosine kinase may be a determinant of this property.

Adenine↗
PubMed1985

Prognosis and histology in Stage I nasopharyngeal carcinoma (NPC).

During 1969-1975, 212 new patients with Stage I nasopharyngeal carcinoma (NPC) with a tumor apparently confined to the nasopharynx were treated at Queen Elizabeth Hospital, Kowloon, Hong Kong. The initial histologies of 137 patients were available for review and further studies. The primary tumors were histologically classified into two major types--squamous cell carcinoma (35 patients) and undifferentiated carcinoma (102 patients). The latter was further divided into 4 sub-types: lymphoepithelioma of the Schmincke type, lymphoepithelioma of the Regaud type, spindle cell carcinoma, and undifferentiated carcinoma of the nasopharyngeal type. Such histological typing of the initial tumor was not of value in predicting the clinical outcome, whether in terms of 5-year crude or disease-free survival rate, or the tendency of the tumor to develop recurrence at the primary site, or distant metastases after a standardized course of radiation therapy. There is no significant correlation between the extent of mononuclear infiltration nor fibrosis in the tumor stroma and the survival or tumor control rates.

Carcinoma↗
PubMed1985

Epidemiology of nasopharyngeal carcinoma in Malaysia and Hong Kong.

We conducted 2 case-control studies with Malaysian and Hong Kong Chinese and investigated the association between salted fish intake and nasopharyngeal carcinoma (NPC). Both studies show a highly significant association between salted fish intake, especially during childhood, and NPC. Furthermore, from our results we estimate that the majority of NPC cases occurring in the southern Chinese can be attributed to their consumption of this food early in life.

Adult↗
PubMed1983

Do cooking fuels pose a risk for lung cancer? A case-control study of women in Hong Kong.

Two hundred female lung cancer patients and 200 female district controls in Hong Kong were interviewed about their previous use of various types of cooking fuels to assess whether any association could be found with lung cancer risk. Mixed results were found when the data were analyzed in terms of ever-exposed vs never-exposed duration, and relationship with smoking. Cases were found to have slightly more exposure to kerosene, whereas controls were likely to have used the cleaner, but more expensive, liquid petroleum gas (LPG) type of fuel. Because the evidence was conflicting if evaluated in terms of consistency, strength, specificity, and coherence of the associations, it was concluded that the small differences in exposure levels between the cases and controls probably reflected their socio-economic circumstances rather than risk for lung cancer. No interaction effect was found between kerosene exposure and smoking.

Cooking↗
PubMed1982

Cancer in Hong Kong: some epidemiological observations.

A good coverage by the Hong Kong Cancer Registry of cases of the common cancers diagnosed in Hong Kong during 1974-78 is indicated by an excess of cases over deaths registered, which is according to expectation from survival prospects. The trends during 1961-79 showed a rapid increase in mortality from lung cancer in both sexes, a moderate rise in liver cancer in males, and small increases in esophageal cancer in males and colon cancer in females. Cervical cancer was the only neoplasm that showed a decreasing trend, although this was small in proportion. Some epidemiological observations on cancer arising in the lung, liver, larynx, and nasopharynx are presented.

Adolescent↗