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Biomedical subjects

S H Chan

Publications and source records attributed to S H Chan.

At least 325 records · Page 18Linked to original sources
PubMed1981

HLA and psoriasis in the Chinese.

The HLA locus A, B and C antigen frequency of 70 unrelated Chinese patients with psoriasis were compared to that of 330 normal subjects. The frequency of 1, Aw30 and B13 were significantly elevated among patients compared to normals, even after correction for the number of antigens typed for. The joint occurrence of Aw30, B13 was observed in 20/70 (37.1%) patients compared to 8/330 /2.4%) normals (chi 2 = 60.7, RR = 16.1). Aw30 and B13 were found to be in significant linkage disequilibrium in patients as well as normals.

China↗
PubMed1981

Inhibition of lymphocyte proliferation by sera from patients with hepatocellular carcinoma: lack of correlation with serum alpha-fetoprotein levels.

Sera from 23 hepatocellular carcinoma (HCC) patients were studied for their effects on lymphocyte proliferation during polyclonal mitogen stimulation and one-way mixed lymphocyte culture (MLC). The effect of 25% HCC serum on tritiated thymidine uptake of cultures varied from slight augmentation to 95% inhibition; however, no relationship was found between the potency of inhibition and serum alpha-fetoprotein (AFP) concentration. Purified AFP from the ascitic fluid of an HCC patient had no effect on MLC or cultures containing pokeweed mitogen; but at a concentration of 200 micro g/ml, AFP inhibited up to 30% of the proliferative responses in cultures containing phytohemagglutinin or concanavalin A. Results strongly suggest that the AFP in HCC sera is not inhibitory in itself.

Blood↗
PubMed1980

Glycine enhancement of caudate neuronal activities: relationship with the dopaminergic nigrostriatal pathway.

Glycine microinjection into the substantia nigra zona compacta (SNC) in lightly anesthetized rats produced a marked and rapid decrease in spontaneous discharges of SNC neurons and a simultaneous enhancement of caudate nucleus (CN) activities. In animals pretreated with the dopamine receptor blocker, haloperidol, intranigral microinjection of glycine produced a dissociation of the nigral inhibition and caudate excitation. The SNC neurons were similarly suppressed while the CN neurons exhibited no discernible change in firing frequency. A possible role was suggested for glycine as an inhibitory neurotransmitter acting on the cells of origin of the nigrostriatal pathway.

Animals↗
PubMed1980

Clonidine suppression of bradycardia induced by gigantocellular reticular nucleus in the cat.

In chloralose-urethane-anesthetized cats, intravertebral injection of clonidine (0.5--4.0 micrograms/kg) elicited a drastic suppression of the bradycardia induced by stimulating the gigantocellular reticular nucleus (GRN). The degree of blockage of GRN-induced cardioinhibtion was related to the time course of the inherent cardiovascular effects of clonidine. It was also dependent upon the dose of the imidazoline compound and the intensity/train pulse frequency of reticular stimulation. It was suggested that the two mechanisms may interact with one another in the brainstem and possible modes of interaction were discussed.

Animals↗
PubMed1980

Comparison of various assays for detection of AFP in differentiating patients with primary hepatocellular carcinoma from controls.

Four assays for the detection of alphafetoprotein (AFP) in the diagnosis of primary hepatocellular carcinoma (HCC) were evaluated. The frequency of AFP detection was compared in 89 HCC patients and in 71 patients with chronic active hepatitis/cirrhosis. Of the four assays, immunodiffusion, counterimmunoelectrophoresis (CIE), supplement CIE, and radioimmunoassay, the best for differentiating patients with HCC from those with chronic active hepatitis and cirrhosis was CIE.

Carcinoma, Hepatocellular↗
PubMed1980

HLA antigen in Chinese patients with hepatocellular carcinomas.

One hundred and fourteen Chinese patients with hepatocellular carcinomas (HCC) were studied for alpha-fetoprotein (AFP), hepatitis B surface antigen (HBsAg), anti-HBsAg, and HLA markers. Younger patients with HCC (less than 60 yr old) were more significantly associated with elevated serum AFP (P less than 0.0001) and serum HBsAg (P less than 0.0001) than were older (greater than or equal to 60 yr old) patients. A strong correlation existed between serum AFP and HBsAg among the patients (P less than 0.0001). Of 27 AFP-negative patients, 15 (55.6%) had HLA-B15 compared to 53 of 238 (22.3%) healthy controls (corrected P less than 0.003, relative risk = 4.4). The frequency of HLA-B15 was even higher in the AFP-negative plus HBsAg-negative subgroup (61%). AFP-negative patients also had a significant lack of blood group A.

ABO Blood-Group System↗
PubMed1980

A pilot study on the screening of primary hepatocellular carcinoma in selected high risk groups in the population using multiple tumour markers.

A prospective one year study on groups of 377 high risk individuals was done using alphafoetoprotein (AFP), alpha 1antitrypsin (A1AT), alpha 1-acidglycoprotein 1 (A1GP), gammaglutamyltraspeptidase (GGT) and isocitrate dehydrogenase (ICD) to detect hepatocellular carcinoma (HCC). The high risk groups screened were: cirrhosis, unexplanable hepatomegalies, chronic hepatitis B surface antigen (HBsAg) carrier, family members of afflicted HCC cases, individuals on hormonal therapy and males over the age of 30 years. 58/377 (15%) were found to have HCC. This consisted of 16/43 (37%) clinical cirrhosis, 40/71 (56%) unexplanable hepatomegalies, 1/33 (3%) chronic HBsAg, 1/156 (0.6%) family members. AFP remained the most useful test but the others such as A1AT, A1Gp, GGT and ICD recognised both malignant and asymptomatic nonmalignant diseases. Only 4 (7%) patients had resectible tumours detected and 1 patient was found to have liver dysplasia. HBsAg positivity and persistently raised AFP. The significance of HBsAg amongst family members and other group is discussed in terms of genetic susceptibility, environmental oncogenic vulnerability and ultimate screening.

Adult↗
PubMed1980

Primary hepatocellular carcinoma developing in a female patient on long term oral contraceptives--a case report.

The association between hepatic tumours and oestrogen and progestogen therapy is well established. The risk of developing primary hepatocellular carcinoma (PHC) is small. In Africa and Asia where hepatitis B virus (HBV) infections are common, the development of PHC is also high. The presence of Hepatitis B core antibody indicates previous exposure to HBV and carries a risk of developing PHC by more than 34 times of non-infected normal. A Chinese female 29 years who had been on oral oestrogen and progestogen contraceptives continuously for 8 years developed PHC. She had no known illness due to HBV but was found to have concomitantly positive Hepatitis B core antibody in her sera. The presence of this HB core antibody and the long term consumption of oestrogen/progesterone derivatives may have been responsible for the early presentation of PHC in this patient. It is the first report in this country of PHC developing in a pill consumer since the introduction of oral contraceptives a decade ago In view of the prevalence of Hepatitis B in the region, this case finding warrants further study to determine whether (a) there is a higher frequency in pill consumers (b) an earlier age of presentation of hepatic malignancy. Meanwhile, it may be prudent to recommend alternative methods of birth control in individuals known to have been previously exposed to HBV infection, clinically or otherwise.

Adult↗
PubMed1980

Immunogenetics of nasopharyngeal carcinoma--position in 1980.

The HLA profile of 313 newly diagnosed Chinese NPC patients was compared to that of 330 normal Chinese subjects. A2 Bw46 and Aw19/B B17 were associated with increase risks of developing NPC whereas A11 was associated with a decreased risk. A2 Bw46 was confined to older onset patients whereas Aw19/B B17 was associated with NPC patients of all ages but particularly with younger patients. The Aw19/B B17 haplotypes was also associated with poor survival. A DR blank was strongly associated with NPC giving a relative risk of 26.5. In Malay NPC the HLA associations were Aw19/B B17 and A9 B18 and in Kadazan NPC, the association was with A9. Possible mechanisms of the HLA association were discussed.

Adult↗