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Biomedical subjects

S H Tan

Publications and source records attributed to S H Tan.

At least 91 records · Page 5Linked to original sources
PubMed1990

Basal cell carcinoma of the head and neck region--a five-year study (1984-88).

Two hundred and seventy-two patients with 292 lesions of basal cell carcinoma of the head and neck region treated at the Department of Plastic Surgery, Singapore General Hospital over a period of five years, were reviewed. Basal cell carcinoma is common in the face, the lesser pigmented mongoloid race of our population and has a higher incidence in the elderly age group. A large number (63%) of the basal cell carcinoma are of the pigmented variety, a very unusual feature. The commonest site of occurrence is the nose (37%). Of the 292 basal cell carcinoma excised, 27 (9%) had tumour involvement of the margins of excision. However, of these 27 cases, only 4 have presented with recurrent tumour. The place of close observation and immediate re-excision of positive margins is discussed. The 4 cases of recurrent basal cell carcinoma involved the nose and lip area, areas with a known higher incidence of recurrence. The results of treatment (98.7% cure rate) of this group are encouraging and compares well with those of other series and using other modalities of treatment. Longer follow-up is required.

Adult↗
PubMed1989

Ultrastructure of the pineal gland of the monkey, Macaca fascicularis, with special reference to the presence of synaptic junctions on pinealocytes.

The present study described the normal ultrastructure of the monkey pineal gland. The gland was composed of the principal pinealocytes, intramural neurons and glial cells. The nucleus of the pinealocytes was deeply infolded with evenly distributed chromatin materials. The abundant cytoplasm was rich in organelles including the well-developed Golgi apparatuses, multivesicular bodies, dense-cored vesicles and widely scattered free and polyribosomes. A variety of axon terminals was observed and the majority of them contained pleomorphic agranular vesicles with a few large dense-cored vesicles. A few terminals showed flattened vesicles or small dense cored vesicles. Some of the axon terminals formed synaptic contacts with the cell bodies of pinealocytes. These synapses were mainly concentrated in the posterior third of the gland. The occasional intramural neurons observed were postsynaptic to axon terminals containing round agranular vesicles. The sources of the nerve fibres and terminals forming synaptic junctions with pinealocytes and intramural neurons were discussed.

Animals↗
PubMed1989

HLA Bw46 and DR9 associations in Graves' disease of Chinese patients are age- and sex-related.

The HLA-A, -B antigens in 159 Chinese patients with Graves' disease were compared with those of 330 controls. The HLA-DR antigens of the patients were also studied in 100 normals. Analysis of the increased prevalence of Bw46, according to the sex and age of onset of disease of the patients, showed that the strong association of Bw46 resided with male patients (n = 58), Pc = 0.0000052, RR = 4.2. Although the frequency of Bw46 was also increased in female patients (n = 101), it was statistically not significant. For the DR9 antigens, the strong association with male patients was also observed, viz. Pc = 0.019, RR = 3.2. Males also had higher risks of Graves' disease if they had homozygous Bw46 at presentation. Further analysis by age of onset of disease revealed the segregation of significant association with Bw46 for the males at 1-19 yr, Pc = 0.0011, RR = 17.5 HLA associations (Bw46 and DR9) with Graves' disease in Chinese are observed primarily in males, especially those whose known ages of onset of the disease are between 1-19 yr (Bw46).

Adult↗
PubMed1989

Ethnicity and drug use: a critical look.

The present study addresses two limitations of the literature regarding the ethnicity-drug use relationship, namely, the absence of ethnically diverse samples and also the inadequate control of background variables. The data employed consisted of responses from 3,697 students derived from a single-stage probability survey from which eight ethnic groupings were constructed: (1) Eastern European, (2) Western European, (3) British Isles, (4) Black, (5) Oriental, (6) East/West Indian, (7) Jewish, and (8) Mediterranean. The findings reveal that, first, the significant zero-order ethnicity effect for alcohol use did not attenuate after controlling for background variables. Also, this relationship was not conditional upon other independent variables. Second, for other substance use measures, the significant zero-order ethnicity effect was found to be spurious or conditional.

Acculturation↗
PubMed1989

Speech development in children.

Speech is unique to man, as a system of communication in which thoughts are expressed and understood by using acoustic symbols. The range of normality in speech development in children is wide. Development does not occur at a steady rate and language milestones are earlier in girls. There is speech delay if the child is not speaking by 3 1/2 years of age, or speech may be defective in articulation or language. Any speech problems should be detected and treated however as early as possible and hence certain children in high-risk groups should be screened for hearing or speech problems.

Child, Preschool↗
PubMed1988

Congenital hypothyroidism in Singapore: prescreening era.

Early diagnosis and treatment is extremely important in patients with congenital hypothyroidism to prevent mental retardation. Late diagnosis in children with congenital hypothyroidism results in a poor developmental outcome with low IQ and poor educational and occupational abilities. General practitioners and paediatricians should try to diagnose congenital hypothyroidism early, so that treatment can be initiated as soon as possible. The importance of a neonatal screening programme for congenital hypothyroidism is emphasized.

Child↗
PubMed1987

Malabsorption of oral antibiotics in humans and rats with giardiasis.

We observed unexplained treatment failures in 13 patients with serious infections and apparent incidental giardiasis. Antibiotic concentrations were assayed in the serum from patients before initiating anti-Giardia therapy and again 2 to 3 weeks after therapy. The peak serum concentrations of antibiotics were higher after treatment for giardiasis. The rat model of giardiasis was used to examine the hypothesis that oral antibiotics are malabsorbed during Giardia lamblia infection. Twenty-eight-day-old Sprague-Dawley rats were fed amoxicillin (50 mg/kg/dose), ampicillin (50 mg/kg/dose), cefaclor (50 mg/kg/dose), cephalexin (50 mg/kg/dose), erythromycin (50 mg/kg/dose), penicillin V (50 mg/kg/dose) or sulfamethoxazole (20 mg/kg/dose) and sera were assayed for antibiotics at 1, 2, 4, 6 and 12 hours after therapy. The same rats were fed 10(5) G. lamblia cysts on 4 consecutive days. On Day 7 of infection the rats were fed the same antibiotic and sera were assayed for antibiotics at 1, 2, 4, 6 and 12 hours after therapy. The mean peak serum concentrations for all drugs except sulfamethoxazole were significantly higher in the rats before infection with G. lamblia. These data suggest that oral antibiotic therapy maybe compromised by decreased absorption in the presence of giardiasis.

Administration, Oral↗
PubMed1987

Relapse markers in childhood thyrotoxicosis.

Childhood thyrotoxicosis is not an uncommon illness, but there is a considerable relapse rate in these patients on medical treatment. An attempt is made in this study to identify those markers that are predictive of a tendency to relapse in childhood thyrotoxicosis. A total of 32 patients with Graves disease were included in the study. Several features were correlated with a tendency to relapse. Of these features, sex, family history, and antibody status were not significantly correlated to relapse. However, of 17 patients with goiter size two times normal or larger, 16 relapsed in comparison with seven relapses of 15 patients with goiter size less than two times normal (p = 0.0039). Of eight patients without ophthalmopathy, only two relapsed, while 21 patients of 24 patients with ophthalmopathy, relapsed (p = 0.002). Of 13 patients with serum thyroxine levels below 20 mcg/dl, six relapsed; of the 19 patients with serum thyroxine levels above 20 mcg/dl, 17 relapsed (p = 0.039). Among 24 patients with a previous relapse, only one achieved a remission with a second course of treatment. The remaining 23 patients had recurrent relapses. Hence it was found that goiter size, presence of ophthalmopathy, total thyroxine levels, and a previous relapse correlated significantly with a further relapse.

Adolescent↗
PubMed1985

Glucose tolerance test and insulin levels in children with transfusion-dependent thalassaemia.

Blood glucose and serum immunoreactive insulin levels were measured following an oral glucose load in 20 unrelated children with multiple transfused thalassaemia. Results suggest that even though overt diabetes and glucose intolerance are uncommon before the age of 13 years, the presence of insulin resistance is evident, especially in those who have been splenectomized.

Adolescent↗
PubMed1985

Microangiopathy in Singapore diabetic children.

Nineteen children with insulin-dependent diabetes mellitus were assessed for microangiopathic complications in the University Department of Paediatrics, Singapore. Of 17 who underwent nerve conduction studies, all showed impaired nerve conduction velocities, with more sensory than motor nerve involvement. The extent of neuropathy was significantly correlated with the duration of disease. Of five children who showed significant proteinuria, two had impaired creatinine clearance, two had cataract formation, and two retinopathy, in one background and in one proliferative. Our study showed a high prevalence of microangiopathic complications in these diabetic children and it is hoped that improved blood glucose control, with the aid of home blood glucose monitoring, may minimize or arrest the microangiopathic complications.

Adolescent↗
PubMed1985

The use of the single radial haemolysis technique in the serological diagnosis of dengue and Japanese encephalitis virus infections.

The single radial haemolysis test for the serological diagnosis of suspected dengue and Japanese encephalitis virus infections uses crude virus antigens with a haemagglutinin titre of 1:320 or 1:640. The results, which may be read 3 hours after the addition of a patient's serum, showed a general agreement between this test and haemagglutination-inhibition tests in the number of case diagnoses that were confirmed. The antibody responses of individual patients shown by the two tests, however, were different, which suggests that the two tests may not be measuring the same antibody. The single radial haemolysis test can distinguish between dengue and Japanese encephalitis viruses using specific mouse hyperimmune sera. Tests on a limited number of sera from Japanese encephalitis patients also showed no cross-reactions with dengue virus antigens in those cases having a low-titred but significant fourfold antibody rise to Japanese encephalitis antigen.

Dengue↗