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Biomedical subjects

L K Tan

Publications and source records attributed to L K Tan.

At least 109 records · Page 6Linked to original sources
PubMed1981

Coronary artery-left ventricular fistula.

Coronary artery-left ventricular fistulae are exceedingly rare and to date only 19 cases have been reported in the literature. We describe another four cases which we encountered recently. The first patient was a 10-year-old asymptomatic Indian male who was referred because of a to-and-fro murmur. Haemodynamic and angiographic studies revealed an aneurysmally enlarged right coronary draining into the left ventricle. The fistula was ligated and the patient has remained well over a 21/2-year follow-up period. The second patient was a 13-year-old asymptomatic Chinese female referred also because of a to-and-fro murmur. Haemodynamic and angiographic studies showed a grossly enlarged right coronary artery draining into the left ventricle. This patient refused operation and has remained well over a 2-year follow-up period. The third patient was a 43-year-old Chinese male who presented with a 3-year history of angina pectoris and was admitted to hospital because of crescendo angina. The resting electrocardiogram showed marked ischaemic changes and the treadmill exercise stress test was also positive. Selective coronary angiography showed markedly dilated right and left coronary arteries. Multiple fistulae from the three major coronary arteries were seen to communicate with the left ventricle. It was elected to treat this patient medically with propranolol. He has remained well over a 6-month follow-up period. The fourth patient was a 5-year-old asymptomatic Chinese girl. Cardiac catheterization and selective coronary angiography revealed marked dilatation of the branches of the left coronary artery which communicated via a maize of fine vessels into the left ventricle. This patient has remained well over a 5-year follow-up period. The clinical presentation, investigations and treatment of coronary artery-left ventricular fistula are discussed and the literature regarding this subject is reviewed.

Adolescent↗
PubMed1981

Malignant tumours of the undescended testis: a report of three cases.

Three cases of testicular malignancies arising in undescended testes were treated in the Department of Surgery, Singapore General Hospital. The patients were all adult Chinese male who presented with tumours arising in unilateral, intra-abdominal undescended testes. Two of the tumours were seminomas while the third was a choriocarcinoma. In all 3 cases, the tumours were large and at an advanced stage at the time of presentation. The treatment in these cases was surgical excision of the primary lesion followed by radiotherapy or chemotherapy. The patient with choriocarcinoma died soon after chemotherapy was initiated while the other two cases are alive, one for over 6 years with no recurrence.

Adult↗
PubMed1981

Renal cell carcinoma - a local experience.

A review of 23 cases of renal cell carcinoma was undertaken. The sex distribution was 3.6 males to 1 female, the male preponderance being higher than in most reported series. The tumour was most common in the 6th and 7th decades of life. Haematuria was the commonest presenting symptom (52.2%); however, all the features of the classical triad of haematuria, loin pain and swelling were not present in any of our patients; 26% of patients presented with non-urological symptoms. At the time of diagnosis, four patients (17.3%) had evidence of metastasis. Another four developed secondaries after nephrectomy. Our approach to renal cell carcinoma has been aggressive and all 23 patients including those with metastasis were treated by nephrectomy.

Adenocarcinoma↗
PubMed1980

Adriamycin in the treatment of resectible and irresectible primary hepatocellular carcinoma.

The treatment of 205 patients with primary hepatocellular carcinoma in Singapore from 1975 to 1980 is reviewed. Adriamycin given at a dose of 40 mg/m(2) intravenously every 4 weeks for irresectible tumours achieved a response rate of 32% alone and has significantly prolonged the median survival time to 4 1/2 months (135 days) in these individuals. Despite this response only 1/34 (3%) patient showed complete remission and is alive at 2 1/2 years. Use of other combinations with Adriamycin e.g. 5 Fluorouracil and Vincristine produced a significant response in the first 16 weeks (p < 0.005) but not thereafter, when completed with the historical group. To improve the response and to consolidate this response, split doses of total hepatic irradiation (to a maximum of 3,150 rads) and alternate day administration of intravenous Adriamycin 10 mg (to a maximum of 90 mg) were given. 12/23 patients (50%) responded. This was followed by a four weekly Adriamycin, 5 F.U. and Vincristine. Median survival time was 5 1/2 months (165 days). Relapse occurred in all patients. Similarly in 5 patients who had resections, early recurrences occurred in 3/5 (60%) within 3 months, inspite of postoperative chemotherapy with Adriamycin, 5 F.U., Vincristine and Cyclophosphamide given every four weeks. In view of the high recurrence rate following effective treatment, further studies on the biological behaviour of these abnormal livers is required.

Antineoplastic Agents↗
PubMed1979

The pathology of cartilage in chondrodysplasias.

The pathology of four types of chondrodysplasias, viz., type II achondrogenesis, thanatophoric dwarfism, Saldino-Noonan syndrome, and chondrodysplasia punctata were studied. In each of these disorders, cells with features similar to the chief and dark chondrocytes of normal hyaline cartilage were seen to be altered in different ways. There was a total absence of chief cells in type II achondrogenesis. All the chondrocytes present were of one variety at different states of maturation, with the fully matured cell having features of dark chondrocytes. The absence of chief cells was associated with marked diminution of interlacunar matrix and failure of growth plate development. The chief chondrocytes in thanatophoric dwarfism appeared diminished in number. They were probably abnormal functionally as evident by their lack of cytoplasmic vacuolation and the formation of thick, occasionally branched collagen in the matrix. The growth plate was stunted and poorly developed. Striking changes involving the dark cells were noted in Saldino-Noonan syndrome, where unusually elongated dark cells were found in groups within abnormal cystic spaces. The chief cells were large and contained abnormal cytoplasmic filaments. There was no formation of a growth plate. In chondrodysplasia punctata, the chief cells were enlarged and abnormally vacuolated. The matrix showed excessive aggregates of coarse granular material. In addition, there were focal accumulations of highly abnormal chief and dark cells with abnormal matrix which contained increased amount of keratan sulphate and culminated in spotty calcification.

Achondroplasia↗
PubMed1979

Nonsmoking grain handlers in Saskatchewan: airways reactivity and allergic status.

This study was carried out to determine whether respiratory disease in Saskatchewan grainhandlers was or was not due to hypersensitivity to grain dust. Sixty nonsmoking grainhandlers, half of whom had low FEV1/FVC ratios and half of whom had high, were studied. The findings in grainhandlers were compared with those in 30 age-matched, nonsmoking teachers. In the group of grainhandlers with low FEV1/FVC ratios, one had developed asthma associated with exposure to grain dust. The majority were healthy, had FEV1/FVC ratios of 70% or greater, and had less evidence of allergic respiratory disease than had age-matched teachers. The studies suggest that non-atopic, nonsmoking men can work in grain elevators without developing respiratory disability, though they may develop a small but significant increase in nonspecific bronchial reactivity to histamine.

Agricultural Workers' Diseases↗
PubMed1978

Oral cromoglycate in treatment of adverse reactions to foods.

20 subjects with adverse reactions to foods were given oral cromoglycate and placebo separately for seven days each. While on each medication they were given, for four consecutive days, a food to which they were sensitive. Adverse reactions were prevented in 14 subjects. These results suggest that oral cromoglycate is of value in the treatment of some patients with adverse reactions to foods.

Administration, Oral↗
PubMed1978

Non-specific aorto-arteritis in Singapore with special reference to hypertension.

Aorto-arteritis has recently emerged as a distinct disease entity with involvement of aorta and its major branches by a non-specific inflammation of unknown etiology. Though the distribution of this disease is worldwide, it is more prevalent in Japan, India, and South-east Asia. This paper describes a series of 48 cases seen in Singapore and emphasizes the protean nature of this disease. Though modes of clinical presentation were many, hypertension appeared to be the commonest as it occurred in 33 patients, giving an incidence of 69 per cent. This incidence was much higher than the 48 per cent reported among Europeans and 42 per cent reported among South Africans. It would therefore appear that hypertension was a far more common manifestation of aorto-arteritis among Asians. The commonest cause of hypertension in aorto-arteritis in this series was renovascular, with renal artery stenosis or occlusion occurring in 27 cases (85 per cent). The frequency of involvement of the renal artery is much greater than the 34 per cent reported by the Japanese. Therefore renovascular hypertension should be regarded as a predominant feature of aorto-arteritis in Singapore.

Adolescent↗
PubMed1977

Immunoglobulin levels in white and metis communities in Saskatchewan.

Serum-immunoglobulin levels (IgG, IgM, IgA, IgD, IgE) have been studied in white and metis (Cree Indian) communities in Saskatchewan. The levels of IgG, IgA, IgD and IgE were higher in the metis than in the whites. Both IgG and IgM were higher in females than in males. IgG and IgA levels rose progressively with age. IgM levels rose rapidly during the first year to almost adult levels, and then fell gradually after the age of 30. IgE levels also rose rapidly during the first 3 years of life, were higher on average in children than in adults, and fell to adult levels at puberty. Low levels of IgA were associated with high levels of IgG; they were not associated with either high levels of IgE or an increase in the prevalence of asthma.

Adolescent↗
PubMed1975

Ruptured aneurysms of the aortic sinus of Valsalva.

Aneurysms of the aortic sinus of Valsalva (ASV) are uncommon. This study describes eight cases of ruptured aneurysms of the congenital variety observed over a 10-year period in Singapore. Although ASV is classically diagnosed at the time of rupture, only one patient in this series presented with acute chest pain and dyspnea. All eight patients had continuous murmurs. The clinical diagnosis was confirmed by cardiac catheterization and angiography in eight patients and by thoracotomy in six. In six patients, the aneurysm had ruptured into the right ventricle and in two into the right atrium. In the five patients where the site of the aneurysm could be definitely determined, four arose from the right coronary and one from the noncoronary sinus. This marked preponderance of right coronary sinus over noncoronary sinus aneurysm in Singapore is more in accordance with the Japanese rather than the Western experience. A systolic gradient due to the aneurysm pressing on the right ventricular outflow tract was established in four patients during cardiac catheterization and angiography and confirmed in three patients at thoracotomy. Six patients underwent operation and were alive and well from 7 months to 3 years later.

Adult↗