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Biomedical subjects

H H Tan

Publications and source records attributed to H H Tan.

At least 19 recordsLinked to original sources
PubMed2006

Oxidative burden in prediabetic and diabetic individuals: evidence from plasma coenzyme Q(10).

AIM: Individuals with diabetes and prediabetes are at risk of vascular injury. However, the exact mechanisms are unclear. The mitochondria mobile electron carrier coenzyme Q(10) (CoQ(10)) is a potent lipophilic antioxidant. We hypothesize that oxidative stress, detectable as changes in plasma CoQ(10) concentrations and composition, plays an important role in vascular disease in diabetes. METHODS: We measured plasma CoQ(10) concentrations (including reduced ubiquinol and oxidized ubiquinone subfractions) in 60 subjects with normal glucose tolerance [NGT; fasting plasma glucose (FPG) < 5.5 mmol/l], 63 with impaired fasting glucose (IFG; FPG 5.6-6.9 mmol/l) and 69 with Type 2 diabetes (DM; FPG > 6.9 mmol/l). RESULTS: In men and women, the total CoQ(10)/total cholesterol ratio was reduced in DM (mean +/-sd) [male (M) 0.09 +/- 0.04; female (F) 0.07 +/- 0.04] compared with NGT (0.29 +/- 0.08; 0.21 +/- 0.07) and IFG (0.27 +/- 0.07; 0.23 +/- 0.07) (DM vs. NGT and IFG P = 0.001). A stepwise reduction in the plasma ubiquinol fraction (ubiquinol/total CoQ10) was observed from NGT (M 0.93 +/- 0.06; F 0.95 +/- 0.06) compared with IFG (0.43 +/- 0.25; 0.41 +/- 0.15) and DM (0.24 +/- 0.11; F 0.29 +/- 0.16) (DM vs. IFG vs. NGT P = 0.001). In contrast, the plasma ubiquinone/ubiquinol ratio increased from NGT (M 0.08 +/- 0.07, F 0.06 +/- 0.08) to IFG (2.14 +/- 1.84, 1.75 +/- 1.04) to DM (4.77 +/- 4.88, 3.81 +/- 3.71) (DM vs. IFG vs. NGT P = 0.001). These differences remained after adjusting for age, body mass index and FPG. CONCLUSIONS: The change in CoQ(10) with increasing FPG concentration suggests an increase in oxidative burden, already evident in the prediabetic IFG individuals. This increase in oxidative stress might contribute to the increased risk of vascular disease.

Adult↗
PubMed2006

Seroprevalence of HSV-1 and 2 among sex workers attending a sexually transmitted infection clinic in Singapore.

We studied the seroprevalence of herpes simplex virus (HSV)-1 and 2 in sex workers attending a sexually transmitted infection clinic in Singapore and examined their knowledge and attitudes towards HSV infection. A total of 300 participants were recruited. Questionnaires were administered and blood was taken and analysed, using the HerpeSelect 1 and 2 Elisa IgG assays (type-specific serological test). HSV-1 serology was positive in 230 (76.7%), negative in 67 (22.3%) sex workers and indeterminate in three (1.0%) sex workers. HSV-2 serology was positive in 237 (79.0%) and negative in 63 (21.0%) sex workers. On univariate analysis, there was significant association between HSV-2 seropositivity and increasing age, nationality (locals) (P<0.001) and marital status (P<0.01). Adjusting for age, marital status and condom use, HSV-2 prevalence increased significantly with duration of years of practice of sex work. Most of the respondents (86.0%) were aware that HSV could be spread through sex without a condom and about two-thirds of them were aware that HSV could be spread in the absence of symptoms. In conclusion, HSV-2 is a common infection among sex workers in Singapore with the risk increasing with years of practice.

Adult↗
PubMed2006

An epidemiological and knowledge, attitudes, beliefs and practices study of sexually transmitted infections in older men.

INTRODUCTION: This study was conducted to determine the disease patterns of sexually transmitted infections (STI) in older men, as well as to gather information on their knowledge, attitudes, beliefs and sexual practices. METHODS: A prospective study was carried out from January to June 2005 in men aged 50 years or older who attended the Department of STI Control clinic. RESULTS: There were 104 men enrolled. The majority (92.3 percent) were Chinese, and 62.5 percent were aged between 50 and 59 years, 25.9 percent between 60 and 69 years, and 11.5 percent aged 70 years or older. The patients were predominantly heterosexual, and had fairly low levels of education--85.6 percent of the patients had received primary or secondary school level of education. Majority (79.8 percent) of the men had been sexually active in the preceding six months, and 37.3 percent had paid sex during that time. 29.8 percent of men reported having taken drugs such as sildenafil (Viagra, Pfizer, New York, NY, USA) or similar drugs such as vardenafil (Levitra, Bayer, Wuppertal, Germany) or tadalafil (Cialis, Eli Lilly, Indianapolis, IN, USA). 56.7 percent of the men had active infections, with non-gonococcal urethritis (15.4 percent), genital warts (12.5 percent) and gonorrhoea (10.6 percent) being the commonest. Generally, condom usage was accepted as an effective way to prevent transmission of STI. However, many of the men surveyed felt that condom usage reduced their sexual pleasure, and 38.5 percent felt that condoms were inconvenient. There were also areas of human immunodeficiency virus (HIV) knowledge that were lacking. Most patients listed the media as their main source of knowledge about STI and HIV. CONCLUSION: Older males attending the clinic remain at significant risk of STI and targeted educational efforts are warranted.

Age Factors↗
PubMed2005

A case of tuberculosis verrucosa cutis--undiagnosed for 44 years and resulting in fixed-flexion deformity of the arm.

Tuberculosis verrucosa cutis (TBVC) is a paucibacillary form of cutaneous tuberculosis caused by exogenous re-infection in previously sensitized individuals. Here, we report an unusual case of TBVC in a 53-year-old Chinese woman that had been present for 44 years and resulted in fixed-flexion deformity of her arm and functional disability. The diagnosis was made by a positive culture for Mycobacterium tuberculosis and she responded well to antituberculous therapy. To our knowledge, this is the first such case of TBVC reported in the English literature with sequelae of functional impairment of the arm.

Arm↗
PubMed2005

Use of polymerase chain reaction on pooled cervical swabs to detect Chlamydia trachomatis infections in female sex workers in Singapore.

INTRODUCTION: Infections caused by Chlamydia trachomatis (C. trachomatis) is one of the commonest sexually transmitted infections (STI). As there is currently no laboratory in Singapore that offers the chlamydia culture tests, alternative laboratory methods were developed and antigen detection methods such as enzyme immunoassays (EIA) proved to be even less sensitive than cell culture. This study was done to assess the accuracy and sensitivity of pooling five endocervical swabs collected for C. trachomatis testing by polymerase chain reaction (PCR) technology, as compared to the currently used EIA on individual swabs, in female sex workers who were seen at a STI clinic in Singapore. METHODS: A total of 1,182 endocervical swab specimens were analysed by EIA as well as in pools of five specimens using PCR. Any pool with a positive PCR result for C. trachomatis infections was subjected to repeat PCR testing of the five individual specimens in the pool. RESULTS: There were a total of 48 confirmed cases of C. trachomatis infection. EIA detected 19 positive samples for C. trachomatis, yielding a prevalence of 1.6 percent among the sex workers tested. Pooled PCR testing showed a higher prevalence rate of 4.1 percent, with 48 PCR positive samples. All cases that were EIA positive were also PCR positive. Individual runs on 200 random samples as well as on 220 individual samples from positive pooled results showed PCR inhibition rates ranging from 1.5 percent to 2.3 percent. However, the PCR inhibition rate was 0 percent with the use of pooling. Sensitivity of EIA was 39.6 percent, with 100 percent specificity. EIA tests had a false negative rate of 60.4 percent. PCR was found to be 100 percent sensitive and specific. CONCLUSION: C. trachomatis infections among female sex workers attending the clinic were found to be higher using PCR technology. Less sensitive methods such as EIA result in undertreatment of otherwise undetected cases. The pooling strategy using pool sizes of five specimens, with a disease prevalence of 4.1 percent is reliable and cost-effective, and has since been introduced in the current medical surveillance scheme for sex workers in the clinic.

Cervix Uteri↗
PubMed2005

Autosomal dominant familial chronic mucocutaneous candidiasis associated with acne rosacea.

INTRODUCTION: Autosomal dominant chronic mucocutaneous candidiasis (CMC) without endocrinopathy (OMIM 114580) is a well-described entity. The associations recorded with this disorder to date are intercellular adhesion molecule-1 (ICAM-1) deficiency and hyper-immunoglobulin E syndrome. CLINICAL PICTURE: We report a new association in a family (mother and nonidentical twin sons) where acne rosacea is a prominent feature together with CMC. In addition, antibodies to thyroid microsomal and antiparietal cell were also isolated. The autoantibodies might be associated with a current "latent" endocrinopathy in particular autoimmune thyroiditis. TREATMENT: The patient was treated with intermittent pulses of itraconazole for the candidiasis and doxycycline initially before being substituted with isotretinoin 6 months later for the rosacea. OUTCOME: The patient's candidiasis responded well and has been in remission for 3 months while his rosacea continues to improve.

Adult↗
PubMed2004

Treatment gap in the use of lipid-lowering drug therapy in diabetes: a population-based study.

BACKGROUND: Lowering cholesterol is highly effective in reducing morbidity and mortality in high-risk people with prevalent cardiovascular disease. AIMS: To investigate lipid-lowering therapy use for secondary prevention of coronary heart disease in all diabetic patients in Tayside, Scotland. METHODS: Among the 385,500 Tayside residents on 31 March 2001, the DARTS database identified all people with Types 1 and 2 diabetes with prevalent macrovascular disease, defined as a history of angina or coronary heart disease. The uptake of lipid-lowering drug was ascertained from MEMO's database of prescriptions dispensed at Tayside pharmacies. RESULTS: Among the 1128 Type 1 patients, 11.3% had prevalent macrovascular disease and 7.9% used lipid-lowering therapy with 42.2% for patients with macrovascular disease. Current/former smokers (OR 2.40, 95% CI: 1.15-5.03) and those with a history of coronary heart disease (OR 2.26, 95% CI: 1.04-4.90) were more likely to use lipid-lowering therapy. Among the 8686 Type 2 patients, 38.8% had prevalent macrovascular disease and 18.3% used lipid-lowering therapy, with 26.7% for patients with macrovascular disease. Current/former smokers (OR 1.37; 95% CI 1.17-1.61) and those with a history of coronary heart disease (OR 2.07, 95% CI 1.66-2.59) or angina (OR 1.30, CI 1.03-1.63) were more likely to use lipid-lowering therapy. A duration of 4 years or less from the first macrovascular event was associated with increased use (OR 1.27; 95% CI 1.05-1.54). Age > 70 years reduced the likelihood (OR 0.51, CI 0.44-0.60). CONCLUSION: A clear gap exists between those requiring lipid-lowering drug therapy and those who are actually receiving it in Tayside.

Adult↗
PubMed2004

Cutaneous Mycobacterium haemophilum infections in immunocompromised patients in a dermatology clinic in Singapore.

INTRODUCTION: Mycobacterium haemophilum, a nontuberculous mycobacterium (NTM) that was first described in 1978, is a pathogen that can cause an array of symptoms in immunocompromised patients, predominantly cutaneous. CLINICAL PICTURE: We report our hospital's experience with the first 3 patients diagnosed with this infection from 1994 to 2002. All were women; one had systemic lupus erythematosus (SLE), one had mycosis fungoides and the last had Sjogren's syndrome with recurrent bacterial infections, although the specific nature of her immunocompromised state has not been defined. All were HIV negative. All 3 women presented with cutaneous lesions--the first with recurrent erythematous plaques on the limbs and back, the second with tender nodules and abscesses on the knees, and the third with papular eruptions on the cheek. TREATMENT/OUTCOME: All responded to a combination of antibiotics and are presently still undergoing treatment and follow-up. CONCLUSION: Infections caused by M. haemophilum occur mainly in immunocompromised patients. They can present with a variety of cutaneous manifestations, which require a high index of suspicion and coordination between the treating physician and the laboratory for diagnosis. Combination antibiotic treatment is recommended, and patients should be followed up after treatment to survey for possible relapse.

Adult↗
PubMed2003

Treatment of toxic epidermal necrolysis in AIDS with intravenous immunoglobulins.

Individuals with AIDS are at higher risk of developing severe cutaneous adverse drug reactions. We report two AIDS patients with drug-induced toxic epidermal necrolysis (TEN). The suspected drugs were discontinued. Both patients were treated with intravenous human immunoglobulins at a dose of 1 g/kg body weight per day for two consecutive days and both experienced a good outcome. Intravenous immunoglobulin potentially lowers the morbidity and mortality of TEN and shortens the duration of the patient's hospitalization.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Sexually transmitted infections in Singapore teenagers.

INTRODUCTION: This is a review of sexual knowledge, behaviour and the extent of sexually transmitted infections (STI), including human immunodeficiency virus (HIV) infection, in Singapore adolescents. METHODS: Data were retrieved from relevant studies, reports and statistics concerning STI and HIV in Singapore. RESULTS: For many reasons, adolescents are at a higher risk of acquiring STI and HIV infections. Adolescents in Singapore are still relatively conservative in their sexual attitudes and behaviour. Most of those who had sex never used condoms. Fortunately, the incidence of STI and HIV infections among adolescents is relatively low. However, this may be changing, and there is a proportion of individuals who exhibit higher risk behaviours. CONCLUSIONS: In this age of rapidly changing morals and values, accurate information and skills need to be provided to young people to ensure that they are adequately prepared to protect themselves from acquiring STI/HIV infection.

Adolescent↗
PubMed2003

Prevalence of temporomandibular disorder subtypes, psychologic distress, and psychosocial dysfunction in Asian patients.

AIMS: To use the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to investigate the physical diagnoses, psychologic distress, and psychosocial dysfunction in Asian TMD patients. The RDC/TMD Axis I and II findings were compared to those of Swedish and American TMD patients. METHODS: One hundred ninety-one patients (53 male and 138 female) referred to 2 institutionalized TMD clinics in Singapore were enrolled in the study. The mean age of the predominantly Chinese population (83.2%) was 33.6 +/- 9.3 years. Data from a RDC/TMD history questionnaire and clinical examination were fed directly by patients and clinicians into a computerized diagnostic system (NUS TMDv1.1). Axis I and II findings were generated on-line, based on RDC/TMD rule engines. Data were automatically exported to SPSS for statistical analysis. RESULTS: Group I (muscle) disorders were found in 31.4% of the patients; Group II (disc displacement) disorders were found in 15.1% and 15.7% of the patients in the left and right temporomandibular joints, respectively; and Group III (arthralgia, arthritis, and arthrosis) disorders were found in 12.6% and 13.0% of the patients in the left and right joints, respectively. Axis II assessment of psychologic status showed that 39.8% of patients experienced moderate to severe depression and 47.6% had moderate to severe nonspecific physical symptom scores. Psychosocial dysfunction was observed in only 4.2% of patients based on graded chronic pain scores. CONCLUSION: Axis I and II findings of Asian TMD patients were generally similar to their Swedish and American cohorts. In all 3 populations, women of child-bearing age represented the majority of patients. Muscle disorders were the most prevalent type of TMD. A substantial portion of TMD patients were depressed and experienced moderate to severe somatization.

Adolescent↗
PubMed2003

A case series of sotalol-induced torsade de pointes in patients with atrial fibrillation--a tale with a twist.

INTRODUCTION: Sotalol is a potent antiarrhythmic often used in patients with atrial fibrillation. However, it has been associated with a risk of provoking other potentially dangerous arrhythmias, especially if used in high doses and in patients with uncorrected electrolyte imbalance or impaired renal and cardiac function. CLINICAL PICTURE: We present 4 patients with atrial fibrillation treated with sotalol who developed torsade de pointes due to marked prolongation of the QT interval. While 1 patient had renal failure, all had normal left ventricular function. One patient had been treated with sotalol for more than 10 months before developing torsade de pointes precipitated by hypokalaemia, while another had tolerated sotalol for a 3-month period before the drug was discontinued, and only developed torsade de pointes when the drug was restarted 2 years later. Significantly, the doses used in all patients were relatively low, in contrast to most other reported cases where higher doses were used. CONCLUSION: As with all antiarrhythmic therapy, these cases illustrate the need for close follow-up of patients treated with sotalol, even if relatively low doses are used. In addition, patients who had previously tolerated the drug well are still susceptible to its proarrhythmic effects.

Aged↗
PubMed2003

A case of nonfatal cutaneous melioidosis.

Melioidosis is a tropical infectious disease caused by the gram-negative bacterium Burkholderia pseudomallei. It is endemic in many parts of the world, including Southeast Asia, and has a mortality rate of about 45%. We report a case of localized nonfatal cutaneous melioidosis presenting as a persistent ulcer in an otherwise healthy young woman.

Adult↗
PubMed2003

A case series of gastrointestinal abnormalities in fetuses with echogenic bowel detected during the antenatal period.

OBJECTIVE: The objective was to evaluate the incidence of gastrointestinal abnormalities amongst those fetuses with antenatally diagnosed echogenic bowel (EB). MATERIALS AND METHODS: A retrospective review of all cases delivered from April 2002 to March 2003 with antenatally diagnosed EB was conducted. This was defined as bowel that appeared as echogenic as (if not greater than) the iliac bone on a real-time image. The postnatal outcomes with regard to gastrointestinal abnormalities, till their discharge, were noted. RESULTS: Of the 13,941 patients delivered, there were 70 cases with antenatally diagnosed EB, giving an incidence of 70/13,941 or 0.50%. Of these, 6 defaulted follow-up and 1 had a mid-trimester termination of pregnancy at 21 weeks' gestation for social reasons. Of the remaining 63 cases with EB, 2 were stillbirths at 31 weeks and 35 weeks of gestation, respectively. Three fetuses (3/63 or 4.76%) were diagnosed with gastrointestinal abnormalities. Meconium plug syndrome was diagnosed postnatally in 2 cases, of which, 1 resolved with conservative management while the other required an emergency laparotomy. Intestinal atresia was diagnosed in the postmortem of one of the stillbirths. There was evidence of intrauterine growth retardation (IUGR) in both the stillbirth and the fetus that had required laparotomy. None of the 3 fetuses exhibited clinical features of aneuploidy. CONCLUSION: As the quoted background risk for gastrointestinal pathology is 0.23%, an increased incidence (4.76%) is observed in those fetuses found to have antenatal EB. It is possible that the presence of IUGR is associated with a worse prognosis. Further prospective studies are needed to verify this association.

Abnormalities, Multiple↗
PubMed2002

Gestational diabetes mellitus: a call for systematic tracing.

INTRODUCTION: Women with history of gestational diabetes mellitus (GDM) have up to 50% lifetime risk of developing frank diabetes mellitus (DM). They are an ideal group of patients to implement early interventional measures to halt the progression to diabetes. The success of any early intervention programme would depend largely on postpartum follow-up. We set out to study the response rate to postpartum oral glucose tolerance test (OGTT) and to profile the non-responders on 105 women who attended our Gestational Diabetes Joint Clinic (GDJC). MATERIALS AND METHODS: We divided these women into 3 groups according to their response to postpartum OGTT and compared their weights, glycaemic parameters and other clinical characteristics during gestation. Group A comprised non-responders or those who did not turn up for postpartum OGTT; group B comprised responders with a normal postpartum OGTT; and group C comprised responders with an abnormal postpartum OGTT defined as 2-hour plasma glucose equal or more than 7.8 mmol/L. RESULTS: The non-respondent rate to postpartum diabetes screening was 37.1%. The non-responders were found to be significantly heavier, with more severe hyperglycaemia during their pregnancy (in terms of glycosylated haemoglobin and results of antepartum OGTT) and had bigger babies compared to the responders with normal postpartum OGTT. Their features instead resembled those who had failed their postpartum OGTT. CONCLUSION: The group of non-responders was probably at similar risk of developing glucose intolerance postpartum as those who were tested abnormal. A more effective call and recall system and education programme is, therefore, needed to ensure postpartum attendance of all patients with GDM.

Adult↗
PubMed2002

Sexually transmitted diseases in the older population in Singapore.

BACKGROUND: Sexually transmitted diseases (STDs) in persons older than 50 years are rarely studied because STDs are more common in young people. AIM: To study the distribution and types of STDs in older persons, defined in our study as individuals aged 50 years or older. METHOD: Retrospective analysis of surveillance data for diseases notified under the Infectious Disease Act, which include syphilis, gonorrhoea, non-gonococcal urethritis (NGU), vaginal discharge and chancroid. Human immunodeficiency virus (HIV) infections were not included. Data from notifications of diseases, such as genital herpes and genital warts, which are not compulsory, were also analysed. Period of study was from January 1996 to December 2000. RESULTS: During the study period, STD notifications for persons aged 50 years and older accounted for 7.6% of all notifications. Among these older persons, males were predominantly affected. The most common disease notified in older persons was gonorrhoea (600 cases), followed by non-infectious syphilis (578 cases) and NGU (339 cases). There were 76 cases of infectious syphilis. The age-specific disease rates for this group of older patients were as follows (number of cases per 100,000 patients per year): gonorrhoea-17.61, non-infectious syphilis-16.96, infectious syphilis-2.23, NGU-20.66, genital warts-6.92 and genital herpes-7.33. CONCLUSION: Although STDs occur mainly in the young, it affects a small but significant proportion of persons aged 50 years and older. A better understanding of the epidemiology of STDs in these population is important for reducing STD morbidity and improving STD care.

Adult↗