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Biomedical subjects

S L Tien

Publications and source records attributed to S L Tien.

15 recordsLinked to original sources
PubMed1999

Activated protein C resistance: a study among 60 thromboembolic patients in the Singapore population.

Resistance to activated protein C (APC-R) is the commonest inherited cause of thrombosis among Caucasians. Few studies have been carried out on its prevalence in Asians. We conducted a prospective study on 60 patients with thromboembolism to determine its prevalence in our local population. The Factor V Leiden (VaQ506) mutation associated with this condition was detected by amplification of the Factor V gene by polymerase chain reaction (PCR) and digestion of the fragment with Mnl I. Three patients were found to be heterozygous for this mutation. None of the 3 patients had other concomitant hypercoagulable states. In addition, we studied the prevalence of this condition in Malays which was found to be 0.5%. Our study suggests that the incidence of APC-R is much lower here compared to the West.

Activated Protein C Resistance↗
PubMed1999

A case report of adult T-cell leukaemia/lymphoma (ATLL).

Adult T-cell leukaemia/lymphoma (ATLL) is a unique disease with distinct manifestations, a characteristic phenotype and a likely retroviral aetiology. It is unusual in Southeast Asia, though more commonly seen in some countries like Japan. We report a case of this disease in a 71-year-old man in Singapore who presented with papular erythematous eruptions for 6 years and subsequently developed generalised lymphadenopathy. He was diagnosed to have ATLL and, despite an initial response, became resistant to combination chemotherapy. We discuss the aetiology, characteristics and management of this interesting disease.

Aged↗
PubMed1998

Highly complex chromosomal rearrangement of chromosome 9 in a case of chronic myeloid leukemia.

A 63-year-old man with chronic myeloid leukemia (CML) was found to have a new complex Philadelphia translocation. All of the bone marrow cells had a rearrangement of a five-way translocation, t(9;22;10;12;1), involving a single chromosome 9. The patient went into blast crisis two years after initial diagnosis and the karyotype remained unchanged. He died in blast crisis 10 months later. We believe this case is a unique 5-way translocation in which four chromosomes were translocated to a single chromosome.

Chromosomes, Human, Pair 1↗
PubMed1995

Haemophagocytosis in bone marrow aspirate--a review of the clinical course of 10 cases.

The clinical course of 10 cases where marrow aspirate showed features of haemophagocytosis was reviewed. Eight of these had a fulminant clinical course characterized by high fever, constitutional symptoms, wasting, hepatosplenomegaly with liver dysfunction, sometimes lymphadenopathy, progressive pancytopenia and coagulopathy, like that described as 'malignant histiocytosis' in the past. The remaining 2 cases did not have this classical clinical syndrome. Among the former 8 cases, 4 of them had high-grade lymphoma, 3 of whom were confirmed to be peripheral T cell lymphoma. Three of the remaining 4 had suspicious lymphomatous infiltrate on marrow trephine. In every case an extensive search for viral etiology by serology was negative. The 2 cases which did not have fulminant clinical feature were found to have lymphoma of the diffuse large cell and Ki-1 anaplastic type, respectively. A review of the literature reveal that most cases with haemophagocytic syndrome have a fulminant clinical course and are peripheral T cell lymphoma, which generally has a poor prognosis. In our study, the 8 cases with the classical haemophagocytic syndrome had a median survival of 24 days and a long-term survival of 37.5% at 28 months. Prompt initiation of chemotherapy is a life-saving measure and the only chance of achieving a long-term survival in patients with haemophagocytic syndrome if the underlying lymphoma can be diagnosed early.

Adolescent↗
PubMed1994

Detection of protein C or protein S deficiency in patients on warfarin therapy--a study of nine patients.

This review studied 9 cases of young or middle-aged patients with protein C or protein S deficiency presenting with thrombotic events in the venous or arterial system. The clinical features were consistent with those described in the literature. Affected family members with similarly low levels were also detected in family studies, some of whom did not have any thrombotic history. Serial measurement of protein C, factor II and factor X at various International Normalization Ratio (INR) levels showed a correlation between suppression of these vitamin K dependent factors and degree of anticoagulation. Furthermore, there was a distinguishable difference in these indices (protein C level, protein C: factor II, protein C: factor X ratio) in warfarinized protein C deficient patients when compared with warfarinized patients who were not protein C deficient. This provides a means in diagnosing protein C deficiency even in warfarinized patients. Such a pattern was not found for protein S deficient patients, which may be due to the assay method used.

Adult↗
PubMed1994

Use of low molecular weight heparin in the treatment of venous thrombosis in a patient with anti-thrombin III deficiency: a case report.

This paper describes the use of a low molecular weight heparin (LMWH) in the treatment of a thrombotic episode in a patient with anti-thrombin III deficiency. Subcutaneous Fraxiparine, a low molecular weight heparin, was successfully used in the initial treatment of a second thrombotic episode in this patient with good results--no clot extension and an almost complete resolution of pulmonary emboli. This case demonstrates the advantages of using LMWH over conventional unfractionated heparin (UFH) which include ease of administration and the rapid achievement of optimal anticoagulation in conjunction with a diminished need for laboratory monitoring.

Adult↗
PubMed1993

Altered immunity in haemophiliacs treated exclusively with cryoprecipitate.

Sixty-five patients with haemophilia A from Singapore General Hospital, treated within the last 15 years exclusively with cryoprecipitate, were studied for the effect of the total number of exposures to random blood donors on their immune system. These haemophiliacs were aged 4 to 71 years (median 24 years) and were all apparently healthy with no clinical evidence of viral infection. None of them was a homosexual or intravenous drug user. All of them tested negative for human immuno-deficiency virus antibody and hepatitis B surface antigen. Analysis of the T-lymphocyte subset population showed 20 out of 65 haemophiliacs or 30.8% had reversal of T4/T8 ratio, ie. less than 1.00. There was no significant difference in the mean age of the 20 patients with abnormal T4/T8 ratios compared with the 45 with normal T4/T8 ratios. The mean age of the former group was 23 and the latter was 25. The group with reversal of T4/T8 ratio had exposure to 827.4 +/- 137.3 (mean +/- SEM) random blood donors, which is significantly higher than 402.5 +/- 64.1 in the group with normal T4/T8 ratio (p < 0.05). The reversal of T4/T8 ratio is predominantly due to the suppression of absolute T4 cell counts, with slightly raised absolute T8 cell counts. This abnormality may be transient or permanent. Interestingly, all the six out of 65 haemophiliacs with factor VIII inhibitor did not show any reversal of T4/T8 ratio in this study.

Adolescent↗
PubMed1993

Main causes of pre-donation deferral of prospective blood donors in the Singapore Blood Transfusion Service.

A retrospective study of the main causes of pre-donation deferral of prospective blood donors in the Singapore Blood Transfusion Service was carried out. Computerised records of all pre-donation deferrals from 1 January 1988 to 31 December 1991 were studied. A total of 278,401 pre-donation screening interviews were carried out during this period. Forty thousand one hundred and sixty-three or 14.4% of these transactions resulted in deferral of prospective blood donors either temporarily or permanently. Analysis of the deferrals showed that the top ten defined causes were: recent ingestion of medication; influenza; low haemoglobin level; a raised blood pressure; recent sexual exposure in high-risk activity; being underweight; Hepatitis B carrier status; recent history of measles, chickenpox or other infections; tattoos, ear-piercing or acupuncture in the preceding six months; and presenting for a subsequent donation too soon. To protect blood donors and recipients, stringent donor screening criteria are necessary. Modifying physical criteria could lower deferral rates but must be preceded by studies to ensure that donors do not suffer ill-effects. Increased public education on common causes of donor deferral may also lower deferral rates by allowing prospective donors to "pre-screen" themselves. However, one-to-one medical screening and appropriate counselling are still the best means for accepting or deferring blood donors in the Singapore setting.

Blood Donors↗
PubMed1991

Apparent change of Rhesus blood group typing in a case of ulcerative colitis.

An interesting case of ulcerative colitis with an apparent change of Rhesus blood group typing is described. To our knowledge, this has not been reported before. We postulate that during the initial active phase of ulcerative colitis, an unknown D-like antigen, possibly bacterial in origin, could temporarily give rise to a Rhesus D-positive blood group typing in a patient with Rhesus D-negative blood type. Interestingly, with continuous immunosuppressive therapy for ulcerative colitis, the patient did not develop anti-D antibodies despite multiple transfusions with D-positive blood.

Adult↗
PubMed1991

A preliminary report on ABO incompatible bone marrow transplant.

Between September 1985 and June 1990, five patients with major and six patients with minor ABO blood group incompatibility between donor and recipient underwent allogeneic bone marrow transplantation (BMT) in the Singapore General Hospital. The period to engraftment, rate of recovery of peripheral blood leukocytes, granulocytes, and platelets and the incidence of graft versus host disease (GVHD) was similar to that observed following ABO blood group compatible marrow transplant. Erythroid development and reticulocytosis were, however, significantly delayed in patients receiving major ABO incompatible marrow transplant.

ABO Blood-Group System↗
PubMed1991

Individualised treatment of seven cases of acquired factor VIII inhibitors.

Seven non-haemophilic patients with acquired Factor VIII inhibitors, admitted to Singapore General Hospital from 1986 to 1990, were studied to analyse their characteristic clinical features and therapeutic outcome. They all had low Factor VIIIC activities, ranged from 0 to 7% and their Factor VIII inhibitors ranged from 1.5 to 128 Bethesda units. All were Chinese aged 30 to 66 years, median 49 years. Six were females, with only one male. Five had associated autoimmune diseases and two had no apparent underlying disorder. One out of seven patients died despite treatment. Therapeutic approach is largely individualised. It may be life-threatening and needs prompt and adequate treatment.

Acute Disease↗
PubMed1990

Yields of fibronectin by heparin-cold-precipitation from plasma.

Fibronectin prepared by heparin-cold-precipitation from 10 packs each of 24-hour plasma, stored plasma and 6-hour frozen plasma was assayed by electroimmunodiffusion. Its yield obtained from 24-hour plasma was significantly higher than that from stored plasma (p less than 0.01) indicating a decline with storage. Freezing of plasma within 6 hours retards degradation of fibronectin. Therefore, 24-hour plasma or 6-hour frozen plasma should be used to prepare fibronectin in order to achieve a better yield.

Blood Preservation↗