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Biomedical subjects

K T Tan

Publications and source records attributed to K T Tan.

At least 19 recordsLinked to original sources
PubMed2006

Microalbuminuria prevalence study in hypertensive patients with type 2 diabetes mellitus in Singapore.

INTRODUCTION: Microalbuminuria is a marker of increased cardiovascular morbidity and mortality. It represents the earliest clinical evidence of diabetic nephropathy. Its early detection allows for implementation of individually-tailored cardiovascular risk reduction management programmes. Despite this, information on the prevalence of microalbuminuria in hypertensive patients with type 2 diabetes mellitus in Singapore is limited. METHODS: The Microalbuminuria Prevalence Study (MAPS) assessed the prevalence of macroalbuminuria and microalbuminuria in consecutively-screened hypertensive adult patients with type 2 diabetes mellitus in ten Asian countries. This paper presents the results of a sub-analysis of data from patients in Singapore. RESULTS: Singapore contributed seven percent of the overall enrolment into MAPS; a total of 499 patients were enrolled and 388 constituted the per-protocol population (patients with bacteriuria and haematuria were excluded). Overall, the prevalence of diabetic kidney disease was high. In our study population, 23.5 percent of patients had macroalbuminuria (95 percent confidence interval [CI] 21.3-25.6), and 48.5 percent of patients had microalbuminuria (95 percent CI 45.9-51.0). Only 28.1 percent (95 percent CI 25.8-30.4) of patients were normoalbuminuric. Associated factors were poor glycaemic control and poor blood pressure control. CONCLUSION: The high prevalence (72 percent) of microalbuminuria and macroalbuminuria found in hypertensive patients with type 2 diabetes mellitus in Singapore is a cause for concern. These findings highlight the need to screen for microalbuminuria and better manage hypertensive patients with type 2 diabetes mellitus, if we are to avoid a major increase in end-stage renal disease.

Albuminuria↗
PubMed2006

Massive pre-placental and subchorionic haematoma.

We report an unusual case of massive pre-placental and subchorionic haematoma occurring in a 26-year-old woman who presented with antepartum haemorrhage at 24 weeks gestation. Ultrasonography showed a subchorionic haematoma in the lower posterior uterine wall measuring 5.0 cm in largest diameter. There was also a separate irregular multiloculated structure measuring 4.3 cm in largest diameter on the surface of the placenta, due to a pre-placental haematoma. The subchorionic haematoma diminished in size over time, while the pre-placental haematoma continued to grow, measuring 9.0 cm at 28 weeks, and 9.3 cm at 32 weeks. At 32 weeks, the patient presented with premature rupture of membranes and four days later, an emergency caesarean section was performed when the patient had another episode of severe antepartum haemorrhage. Both mother and child recovered well. The current literature on such haematomas is reviewed.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed2005

The benefits of combined anti-platelet treatment in carotid artery stenting.

OBJECTIVE: To assess the benefits of a combined anti-platelet regime of aspirin and clopidogrel in carotid artery stenting. METHODS: A randomised controlled trial was performed comparing aspirin and 24-h heparin with aspirin and clopidogrel for patients undergoing carotid artery stenting. Outcome measures included 30-day bleeding and neurological complications and 30-day stenosis rates. RESULTS: Bleeding complications (groin haematoma or excessive bleeding at the groin site) occurred in 17% of the heparin and 9% of the clopidogrel group (p=0.35; n.s). The neurological complication rate in the 24-h heparin group was 25% compared to 0% in the clopidogrel group (p=0.02). The 30-day 50-100% stenosis rates were 26% in the heparin group and 5% in the clopidogrel group (p=0.10; n.s). CONCLUSIONS: The dual anti-platelet regime has a significant impact on reducing adverse neurological outcomes without an additional increase in bleeding complications. This study was terminated prematurely due to an unacceptable level of complications in the heparin arm of the trial.

Aged↗
PubMed2005

Abnormal circulating levels of metalloprotease 9 and its tissue inhibitor 1 in angiographically proven peripheral arterial disease: relationship to disease severity.

BACKGROUND: Peripheral arterial disease (PAD) is associated with adaptive changes in the vascular and muscle extracellular matrix (ECM) in response to reduced blood flow. Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), are key modulators of ECM turnover. We hypothesized that patients with intermittent claudication (with low ankle-brachial blood pressure index, <0.8), and critical ischaemia would have raised circulating levels of MMP-9, TIMP-1 and TIMP-2 compared with healthy controls, reflecting an increase in proteolytic activity which may be related to ECM turnover in PAD. METHODS: We studied 36 patients (23 males; 65 +/- 9 years) with intermittent claudication and 43 (25 males; 68 +/- 12) patients with critical ischaemia. All patients had angiographic evidence confirming significant PAD. RESULTS: Circulating levels of MMP-9 and TIMP-1 were higher (both P < 0.0001) in the PAD patient groups compared with the controls. Patients with critical ischaemia had MMP-9 and TIMP-1 levels that were significantly higher than those with intermittent claudication. There were no differences in circulating TIMP-2 levels between patients and controls. There was a modest positive correlation between the white cell count (WCC) and MMP-9, both patients with intermittent claudication (Spearman, r = 0.398, P = 0.016) and critical ischaemia (r = 0.378, P = 0.014). CONCLUSION: We demonstrate higher levels of circulating MMP-9 and TIMP-1 in patients with intermittent claudication and critical ischaemia. Circulating concentrations of both markers can be related to disease severity, being higher in critical ischaemia compared with levels in intermittent claudication.

Aged↗
PubMed2005

Clinically apparent atherosclerotic disease in diabetes is associated with an increase in platelet microparticle levels.

BACKGROUND: The commonest cause of mortality in patients with Type 2 diabetes is atherothrombosis, which can be related to abnormalities in the coagulation and fibrinolytic pathways, as well as in platelet function. Platelet microparticles (PMPs) may contribute to the prothrombotic state and may promote the progression of atherosclerosis. We hypothesized that PMPs are elevated in Type 2 diabetes and that patients with Type 2 diabetes and clinically apparent atherosclerosis would have the highest levels. Similarly, we hypothesized that soluble plasma P-selectin (sPsel) and CD40L (both molecules which are released by activated platelets), as well as %CD62P (P-selectin) and %CD63 positivity on platelets quantified by flow cytometry, would be highest in patients with Type 2 diabetes and clinically apparent atherosclerotic disease, and might be correlated to PMP levels. METHODS: Venous blood was obtained from 21 Type 2 diabetic patients without atherosclerotic complications, 18 diabetic patients with clinically apparent atherosclerotic disease and 21 non-diabetic control subjects. PMPs, as well as %CD62P and %CD63 positivity on platelets, were quantified by flow cytometry. sPsel and CD40L were measured using ELISA. RESULTS: Patients with Type 2 diabetes and clinically apparent atherosclerotic disease had the highest PMP (P=0.045) and sPsel (P=0.046) levels, compared with patients without complications (who had intermediate PMP levels) and control subjects. Control subjects had the lowest CD40L levels (P<0.001) when compared with patients with Type 2 diabetes, with no difference in sCD40L levels between the two diabetic subgroups. %CD62P and %CD63 positivity did not differ between the groups. PMP levels correlated with %CD62P positivity (P=0.026) but not to %CD63 positivity (P=0.089), sCD40L (P=0.407) or sP-sel (P=0.163); sCD40L levels did not correlate with any other marker of platelet activation. CONCLUSION: PMPs are elevated in Type 2 diabetes. In addition, patients with clinically apparent atherosclerosis had the highest levels of PMPs and sPsel. Thus, PMPs may be a marker of symptomatic atherosclerotic vascular disease in Type 2 diabetes, and may both represent a useful risk stratification tool as well as a novel therapeutic target for anti-thrombotic drugs.

Aged↗
PubMed2004

The endothelium and platelets in cardiovascular disease: potential targets for therapeutic intervention.

The interaction between platelets and endothelium has been implicated in many disease processes. It is now known that platelets may be involved in the initiation of atheroma, modulate various inflammatory responses, and contribute to endothelial dysfunction, in addition to their classical role in thombosis. Indeed, various drugs targeting platelets and endothelium have been shown to be of benefit in disease states. The last few years has seen an exponential increase in our knowledge of platelet and endothelial biology. As a result of this, many new drugs, for example the ADP-antagonists and the GpIIbIIIa antagonists, have been developed for use in the clinical setting. There is also renewed interest in the use of older drugs (for example, the statins) in modulating platelet-endothelial interactions. This review focuses on the recent advances in our understanding of the interaction(s) between platelets and endothelium and how this knowledge could be manipulated for therapeutic gain.

Adenosine Triphosphatases↗
PubMed2002

Magnetic resonance angiography for the diagnosis of renal artery stenosis: a meta-analysis.

AIM: To review the published literature comparing the diagnostic accuracy of magnetic resonance angiography (MRA) with and without gadolinium in diagnosing renal artery stenosis, using catheter angiography as reference. MATERIALS AND METHODS: A meta-analysis was performed of English language articles identified by computer search using PubMed/MEDLINE, followed by extensive bibliography review from 1985 to May 2001. Inclusion criteria were: (1) blinded comparison with catheter angiography; (2)indication for MRA stated; (3) clear descriptions of imaging techniques; and (4) interval between MRA and catheter angiography < 3 months and only the largest of all studies from one centre was selected in the analysis. RESULTS: A total of 39 studies were identified, of which 25 met the inclusion criteria. The number of patients included in the meta-analysis was 998: 499 with non-enhanced MRA and 499 with gadolinium-enhanced MRA. The sensitivity and specificity of non-enhanced MRA were 94% (95% CI: 90-97%) and 85% (95% CI: 82-87%), respectively. For gadolinium-enhanced MRA sensitivity was 97% (95% CI: 93-98%) and specificity was 93% (95% CI: 91-95%). Thus, specificity and positive predictive value were significantly better for gadolinium-enhanced MRA (P < 0.001). Accessory renal arteries were depicted better by gadolinium-enhanced MRA (82%; 95% CI: 75-87%) than non-gadolinium MRA (49%; 95% CI: 42-60%) (P < 0.001). CONCLUSIONS: Gadolinium-enhanced MRA may replace arteriography in most patients with suspected renal artery stenosis, and has major advantages in that it is non-invasive, avoids ionizing radiation and uses a non-nephrotoxic contrast agent.

Contrast Media↗
PubMed2001

Diverse cyclization catalyzed by In(OTf)3 for the convergent assembly of substituted tetrahydrofurans and tetrahydropyrans.

[reaction: see text]. A novel In(OTf)3-catalyzed (3,5) oxonium-ene type cyclization for the facile construction of various multisubstituted tetrahydrofurans and tetrahydropyrans was successfully developed. Further mechanistic investigations unveiled an In(OTf)3-catalyzed skeletal reorganization of the tetrahydrofuran to its thermodynamic isomer under thermal conditions.

Journal Article↗
PubMed2001

A clinical review of granulosa cell tumours of the ovary cases in KKH.

INTRODUCTION: Granulosa cell tumour (GCT) represents the largest group of sex-cord stromal tumours and comprises 1.5-3% of ovarian malignancy. The aim is to determine the incidence of the disease, study the profile of local patients, and assess the use of imaging studies in the diagnosis of the tumour. MATERIAL AND METHODS: Clinical records of 19 patients diagnosed with GCT between October 1988 and July 1997 in Kandang Kerbau Hospital (KKH) were reviewed. RESULTS: GCT accounts for 3.5% of ovarian malignancy (54 out of 1552) in Singapore, of which 94.7% are adult GCT. In our study, patients are mainly peri/postmenopausal women (63.2%) in their 50s who experience post-menopausal bleeding. There is a high incidence of association with endometrial hyperplasia (40%). Ultrasound scans are able to predict the size and involvement of the tumour rather accurately. In our study sample, 13 patients (68.4%) presented with Stage 1 of the disease, none with Stage 2, 1 with Stage 3 (5.3%) and none with Stage 4. The other 5 patients (26.3%) were unstaged. Only one patient required adjuvant chemotherapy. CONCLUSION: The local data with regards to GCT is congruent with those found in foreign literature. However, in our study, there were no patients with recurrence whereas GCTs are known to be late recurring in up to 20% of patients 10-20 years after diagnosis. This is probably attributed to the relatively short period of follow-up in this study. Thus, despite the fact that there is no evidence of recurrence of disease in our current study, we still recommend a vigilant follow-up protocol on all patients as literature has proven that with early detection of recurrences, it is possible to achieve complete cure.

Adult↗
PubMed2001

Sex linked recessive dystonia parkinsonism of Panay, Philippines (XDP).

Sex linked dystonia parkinsonism (XDP), also referred to as "lubag" in American literature, was described in 1975 occurring endemically in Panay, Philippines. It is an adult onset, sex linked, predominantly male, severe, progressive movement disorder with high penetrance and a high frequency of generalisation. The movement disorder is characterised by dystonic movements, usually starting in the 3rd or 4th decade, spreading to generalisation within two to five years. The dystonia coexists or is replaced by parkinsonism usually beyond the 10th year of illness. No treatment has been found to be effective. Neuroimaging shows caudate and putamenal atrophy in patients reaching the parkinsonian stage. Neuropathology reveals pronounced atrophy of the caudate and putamen, mostly in the cases with long standing illness. The sex linked pattern of inheritance has been established. Genetic studies have located the affected gene (DYT3) to Xq13.1, with one group mapping the XDP gene to a < 350 kb locus in the DXS 7117-DXS 559 region.

Adult↗
PubMed1999

HIV and youths in Singapore--knowledge, attitudes and willingness to work with HIV-infected persons.

AIM OF STUDY: This study examines the level of knowledge among youths in Singapore regarding HIV transmission and their attitudes towards working with a HIV-infected person at the workplace. METHOD: Respondents consist of 413 youths from three educational institutions in Singapore. The survey was administered to classes which were randomly selected by the liaison persons of these three educational institutions. RESULTS: Findings of this study suggest that youths in Singapore are generally clear that HIV can be transmitted through sexual contact, blood transfusion and from a woman to her unborn child. However, our data also suggest that a sizeable number of respondents still possess a number of misconceptions about how HIV can be transmitted. While available scientific data suggest that HIV cannot be transmitted through casual contact at the workplace, results of this study suggest that some elements of uncertainty and fear still prevail. This is an interesting finding as it suggests that while AIDS education and campaigns may increase knowledge and awareness about HIV transmission, they do not really reduce personal concern about the possibility of infection and the potential stigma associated with working with HIV-infected persons. CONCLUSION: The implications of our findings on AIDS education are discussed.

Adult↗
PubMed1997

Endometrial hyperplasia and the risk of endometrial carcinoma.

OBJECTIVES: To determine the incidence of endometrial carcinoma in endometrial hyperplasia and try to identify those patients at greatest risk. METHODS: We conducted a retrospective study of 116 patients who had simple, complex or mixed (simple with focal complex) endometrial hyperplasia with or without atypia, from January 1991 to December 1994. RESULTS: Twenty-nine patients had endometrial hyperplasia with atypia and 87 without atypia. Incidence of endometrial carcinoma was 27.6% in those with atypia; and 3.4% in those without atypia. All were stage I (A or B) adenocarcinomas. Polycystic Ovary Disease and subfertility were found significantly in the cases with cytological atypia; however, they were not significant in the cases with carcinoma. No significant historical differences that could predict carcinoma were found.

Adenocarcinoma↗
PubMed1997

Computerised analysis of foetal heart rate variation: prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term.

The aim of this study was to determine the value of antenatal numerical assessment of foetal heart rate variation in the prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term. Two hundred and seven patients who underwent prostaglandin cervical ripening after 37 weeks gestation for the indications of pregnancy-induced hypertension, foetal growth retardation or post-dates pregnancy were included in this study. Prior to commencement of cervical ripening, a 30-minute cardiotocography tracing was recorded on the System 8000 machine and the long-term and short-term variations were calculated. Forty-three patients (20.8%) had a long-term variation of less than 30 ms; 9 (4.3%) had a short-term variation of less than 3 ms. The sensitivity and positive predictive values of long-term variation in the prediction of admission to neonatal special care unit were 25.6% and 23.2%, respectively. Corresponding values for short-term variation were 2.6% and 11.1%, respectively. The sensitivity and positive predictive values of long-term variation in the prediction of caesarean section for foetal distress were 33.3% and 9.3%, respectively. Corresponding values for short-term variation were 8.3% and 11.1%, respectively. Long-term and short-term variations appeared to be both poor predictors of adverse perinatal outcome. However, of 4 foetuses with both reduced antenatal heart rate variation and who were subsequently delivered by caesarean section for foetal distress in labour, all 4 were admitted to neonatal special care unit (NSCU). Foetuses with intrapartum evidence of foetal distress were more likely to be admitted to NSCU when antenatal foetal heart rate variation was reduced.

Adult↗
PubMed1996

A modular domain of NifU, a nitrogen fixation cluster protein, is highly conserved in evolution.

hnifU, a gene exhibiting similarity to nifU genes of nitrogen fixation gene clusters, was identified in the course of expressed sequence tag (EST) generation from a human fetal heart cDNA library. Northern blot of human tissues and polymerase chain reaction (PCR) using human genomic DNA verified that the hnifU gene represented a human gene rather than a microbial contaminant of the cDNA library. Conceptual translation of the hnifU cDNA yielded a protein product bearing 77% and 70% amino acid identity to NifU-like hypothetical proteins from Haemophilus influenzae and Saccharomyces cerevisiae, respectively, and 40-44% identity to the N-terminal regions of NifU proteins from several diazatrophs (i.e., nitrogen-fixing organisms). Pairwise determination of amino acid identities between the NifU-like proteins of nondiazatrophs showed that these NifU-like proteins exhibited higher sequence identity to each other (63-77%) than to the diazatrophic NifU proteins (40-48%). Further, the NifU-like proteins of non-nitrogen-fixing organisms were similar only to the N-terminal region of diazatrophic NifU proteins and therefore identified a novel modular domain in these NifU proteins. These findings support the hypothesis that NifU is indeed a modular protein. The high degree of sequence similarity between NifU-like proteins from species as divergent as humans and H. influenzae suggests that these proteins perform some basic cellular function and may be among the most highly conserved proteins.

Amino Acid Sequence↗