MyMedR

Estimates of general combining ability in Hevea breeding at the Rubber Research Institute of Malaysia : I. Phases II and III A

Tan H

Theor Appl Genet, 1977 Jan;50(1):29-34.

PMID: 24407495 DOI: 10.1007/BF00273794

Estimates of general combining ability of parents for yield and girth obtained separately from seedlings and their corresponding clonal families in Phases II and IIIA of the RRIM breeding programme are compared. A highly significant positive correlation (r = 0.71***) is found between GCA estimates from seedling and clonal families for yield in Phase IIIA, but not in Phase II (r = -0.03(NS)) nor for girth (r= -0.27(NS)) in Phase IIIA. The correlations for Phase II yield and Phase IIIA girth, however, improve when the GCA estimates based on small sample size or reversed rankings are excluded.When the best selections (based on present clonal and seedling information) are compared, all five of the parents top-ranking for yield are common in Phase IIIA but only two parents are common for yield and girth in Phases II and IIIA respectively. However, only one parent for yield in Phase II and two parents for girth in Phase IIIA would, if selected on clonal performance, have been omitted from the top ranking selections made by previous workers using seedling information.These findings, therefore, justify the choice of parents based on GCA estimates for yield obtained from seedling performance. Similar justification cannot be offered for girth, for which analysis is confounded by uninterpretable site and seasonal effects.

Controversy of proton pump inhibitor and clopidogrel interaction: a review

Tan HJ

J Dig Dis, 2010 Dec;11(6):334-42.

PMID: 21091895 DOI: 10.1111/j.1751-2980.2010.00466.x

A proton pump inhibitor (PPI) is often co-prescribed with clopidogrel to reduce the gastrointestinal risk of bleeding ulcers in patients following acute coronary syndrome or a stent implant. However, the safety issue of such practice has been scrutinized after some studies reporting an increased incidence of cardiovascular events and mortality, although there have also been contrary research reports. This has lead to a warning statement from the US Food and Drug Administration cautioning the concomitant use of PPI and clopidogrel. This review examines the evidence of PPI as gastroprotective agent, histamine H(2) antagonists as an alternative therapy, the influence of PPI on the antiplatelet effect of clopidogrel, and the controversies of various studies.

New therapies for erectile dysfunction

Tan HM

Int. J. Androl., 2000;23 Suppl 2:87-8.

PMID: 10849506

The quest for improving and maintaining sexual function has been going on since time immemorial. The advent of an effective oral drug, sildenafil, has brought about unprecedented open discussion on male erectile dysfunction, and gas accelerated the pace of development of new therapies for erectile dysfunction. New knowledge in the physiology of sexual function has enabled researchers to target drug treatment at the whole network of the central nervous system and the numerous cascadic enzymatic reactions leading to relaxation of the corporal smooth muscle. One of the brightest potential applications of future molecular technology in the study of erectile dysfuction is in the utilization of gene therapy.

Penile prosthesis implantation in a transsexual neophallus

Tan HM

Asian J Androl, 2000 Dec;2(4):304-6.

PMID: 11202422

Reconstruction surgery for a female to male transsexual usually involves mastectomy, hysterectomy and creating an aesthetically appealing neophallus. We have successfully inserted an inflatable prosthesis using the AMS CX prosthesis in a 45 year old transsexual, who had a large bulky neophallus constructed from the anterior abdominal subcutaneous fat, about 9 years ago. The single cylinder CX prosthesis was well anchored to the symphysis pubis using a dacron windsock tubing, the activation pump was placed in the dependent pouch of the right labium and the reservior in the usual perivesical space. The patient subsequently had debulking procedure using liposuction to create a more aesthetic and functional phallus. To date, the inflatable neophallus prosthesis is functioning well.

An unusual rash and end-stage renal failure

Tan HJ, Eadington D

Hosp Med, 2001 Mar;62(3):176-7.

PMID: 11291470

Is HIV Screening in the General Population Cost Effective?

Tan H, Koh K

Malays Fam Physician, 2008;3(2):96-7.

PMID: 25606125 MyJurnal

The introduction, origin and life-history attributes of the non-native cichlid Etroplus suratensis in the coastal waters of Singapore

Ng TH, Tan HH

J Fish Biol, 2010 Jun;76(9):2238-60.

PMID: 20557661 DOI: 10.1111/j.1095-8649.2010.02642.x

Etroplus suratensis, a southern Asian cichlid, has established populations in Singapore. The fish, which was first collected in 1995, was probably introduced via the aquarium trade or through the Johor River in Malaysia. The growth, feeding and reproductive characteristics were found to follow its ecology in its native range in southern Asia, and its establishment in Singapore could be due to the similarity in environment and availability of food. Changes in intestinal length indicated diet shifts from a predominantly herbivorous to an omnivorous one as it matured. Stomach contents did not provide comparable evidence. Diet similarity to two other introduced cichlids may imply that interspecies resource competition exists. Closer monitoring is needed to determine its effects on the local environment.

Comparison between the effects of propofol and etomidate on motor and electroencephalogram seizure duration during electroconvulsive therapy

Tan HL, Lee CY

Anaesth Intensive Care, 2009 Sep;37(5):807-14.

PMID: 19775046

An ideal anaesthetic for electroconvulsive therapy (ECT) should have rapid onset and offset with no effect on seizure duration, and provide cardiovascular stability during the procedure. Propofol is commonly used, even though it has been shown to shorten seizure duration which might affect the efficacy of ECT Etomidate has been advocated as an alternative. This prospective, randomised, single-blind, crossover study was conducted to compare the effects of etomidate (Etomidate-Lipuro, B. Braun Ltd, Melsungen, Germany) and propofol (Diprivan, AstraZeneca, UK) on seizure duration as well as haemodynamic parameters in patients undergoing ECT Twenty patients aged between 18 and 70 years were recruited. Group I received etomidate 0.3 mg/kg for the first course of ECT (Group IA) and propofol 1.5 mg/kg for the second ECT (Group IB), while Group II received propofol for the first ECT (Group IIA) and etomidate for the second ECT (Group IIB). There was a washout period of two to three days in between procedures. Parameters recorded included motor seizure duration, electroencephalogram seizure duration, blood pressure and heart rate. Analysis demonstrated neither period effect nor treatment period interaction. Etomidate was associated with a significantly longer motor and electroencephalogram seizure duration compared with propofol (P < 0.01). Neither drug demonstrated consistent effects in suppressing the rise in heart rate or blood pressure during ECT Myoclonus and pain on injection were the most common adverse effects in etomidate group and propofol group respectively. Etomidate is a useful anaesthetic agent for ECT and should be considered in patients with inadequate seizure duration with propofol.

Fulltext Infective endocarditis in pregnancy complicated by septic embolization to the cerebellum

Tan HJ, Rabani R, Noorfaizan S

Med J Malaysia, 2007 Aug;62(3):249-50.

PMID: 18246919 MyJurnal

This report describes a pregnant lady in early trimester that was admitted with fever and left loin pain and was initially treated as presumed pyelonephritis. Subsequently she was found to have infective endocarditis with vegetation on the mitral valve. The course of her illness was complicated by acute pulmonary edema and septic embolization to the cerebellum. A decompressive craniectomy and resection of the lateral lobe of cerebellum was performed. Although the presenting features and risk factors are well described, the atypical presentations of infective endocarditis in pregnancy remain a diagnostic challenge for the treating physician. This report highlights the importance of rapid detection of endocarditis in pregnancy and the treatment of systemic complications.

Fulltext High-flux haemodialysis treatment as treatment for carbamazepine intoxication

Koh KH, Tan HH

Med J Malaysia, 2006 Mar;61(1):109-11.

PMID: 16708747 MyJurnal

Acute severe intoxication with carbamazepine is associated with seizures, coma and respiratory depression. Traditionally, charcoal haemoperfusion is used to remove the drug. We present a case of carbamazepine intoxication, successfully treated with three hours of high-flux haemodialysis. Thus, haemodialysis using high-flux membranes is a feasible and effective therapeutic option for carbamazepine intoxication.

Sexually transmitted infections in Singapore teenagers

Chan RK, Tan HH

Ann Acad Med Singap, 2003 Jan;32(1):25-8.

PMID: 12625094

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.

Clinical efficacy of sulfadoxine-pyrimethamine in the treatment of falciparum malaria in Sabah, Malaysia

Tan HS, Tan PE

Ann Acad Med Singap, 1984 Apr;13(2):170-4.

PMID: 6388486

One hundred and ten consecutive patients with falciparum malaria were treated with Fansidar and primaquine. Of the 61 patients who were followed up at one week, 4 (6.6%) failed to clear their parasitaemia (1 R III and 3 R II treatment failures). Of the subsequent 40 patients who were seen again at one month, another 3 (7.5%) had recrudesced (R I treatment failure). A total of 7 patients thus experienced some form of treatment failure in the cohort of 40 who completed the one month follow up. Only 1 of these 7 patients (with R III treatment failure) failed to respond to repeat Fansidar treatment, and may be the only one with true Fansidar resistance. The overall treatment failure rate of 17.5% (95% confidence interval: 6-29%) in the cohort who completed the study is consistent with the known clinical efficacy of Fansidar. These results suggest no significant Fansidar resistance in falciparum malaria found in Sabah.

Fulltext Experience with 395 extracorporeal shockwave lithotripsy in the treatment of renal and ureteric calculi

Tan HM, Cheung HS

Med J Malaysia, 1990 Jun;45(2):113-7.

PMID: 2152014

Three hundred and ninety five cases in 358 consecutive patients (male-232, female-126) with renal and ureteric stones were treated with extracorporeal shockwave lithotripsy (ESWL) from March to November 1988. They either had ESWL alone, or in combination with stone manipulation or debulking percutaneous nephrolithotripsy (PCNL). Seventy five percent of the stones were found in the pelvicalyceal system and 25% in the ureter. Seventy-six percent of the stones were less than 25mm size. Two hundred and ninety (79%) cases were followed up to three months. Two hundred and forty nine (85.9%) cases were stone free and 36 (12.4%) had residual sand less than 3mm size. Five (1.7%) cases failed to fragment with ESWL monotherapy and were salvaged by either percutaneous or ureteroscopic intervention. None of the cases required any open surgery intervention.

Fulltext Percutaneous renal surgery for urolithiasis

Tan HM, Cheung HS

Med J Malaysia, 1990 Jun;45(2):118-22.

PMID: 2152015

Sixty eight consecutive cases of percutaneous renal surgery, percutaneous nephrolithotripsy (PCNL), were performed on 64 patients (male-41, female-23) at the Subang Jaya Medical Centre from April 1988 to July 1989. All the cases were done as a one stage procedure. Fifty eight stones were large renal or staghorn and ten were ureteric. Thirty cases (41%) were stone free after PCNL alone. Thirty eight cases had residual fragments needing extracorporeal shockwave lithotripsy (ESWL). Mean operating time was 109.6 +/- 36.0 minutes. Mean hospital stay was 4.5 +/- 1.8 days. At three months follow-up, 86% of the cases were stone free. The remaining had residual sand (less than 3mm). Minor complications occurred in six patients. None required major surgical intervention post PCNL.

Estimates of genetic parameters of certain characters in Hevea brasiliensis

Tan H, Mukherjee TK, Subramaniam S

Theor Appl Genet, 1975 Jan;46(4):181-90.

PMID: 24419927 DOI: 10.1007/BF00281668

Heritability estimates of five quantitative characters, namely, yield, girth, girth increment, virgin bark and renewed bark thickness, of the breeding Phase III Hevea families have been obtained by variance component analyses. In general, the combined heritability estimates for various characters were low to moderate. The heritabilities of these characters based on female variance components, however, were high, suggesting that considerable improvement of each of the characters could be achieved in properly designed experiments.Estimates of heritability for average yields (Range: 0.11-0.34) over different years showed that the first three years' yield was adequate for predicting estimates of genetic variance for the average of five years' yield.Correlation studies on yield with other characters indicated considerable influence of environment, with genetic correlations accounting for about 0.07 to 0.36 in the characters studied.Expected direct response to selection in yield and correlated response in yield to selection for girth at opening and virgin bark thickness have been calculated using three arbitrary values of selection intensity. The efficiency of the correlated response was found to be approximately half that of the direct response. However, the indirect selection for yield using virgin bark thickness appeared to be more favourable than that using the girth at opening favoured by earlier workers.

Fulltext Preparation of theranostic 153 Samarium-labelled polystyrene microspheres for hepatic radioembolization

Tan, H. Y., Wong, Y. H., Kasbollah A., Md. Shah M. N., Abdullah B. J. J., Yeong, Chai Hong

Malaysian Journal of Medicine and Health Sciences, 2019;15(102):21-21.

MyJurnal

Introduction: Hepatic radioembolization is a minimally invasive procedure involving intrarterial administration of radioembolic microspheres for the treatment of liver tumours. In this study, a biocompatible polystyrene (PS) microspheres formulation containing radioactive Samarium-153 (153Sm) was synthesized and tested. The 153Sm emits both diagnostic gamma energy and therapeutic beta radiation, renders the synthesized microspheres an ideal theranostic radioembolic agent for hepatic radioembolization. Methods: First, the 152Sm2O3 (20 – 50%, w/v) was encapsulated in PS microspheres using solid-in-oil-in-water solvent evaporation method. The 152Sm-labelled PS microspheres were then activated to 153Sm (Eβmax = 807.6 keV, half-life = 46.3 hours) via 152Sm (n,γ) 153Sm reaction in a nuclear reactor with a neutron flux of 2.0 x 1012 n.cm-2.s-1. Physicochemical characterization, gamma spectroscopy and in-vitro radiolabeling studies were carried out to study the properties and stability of the microspheres before and after neutron activation. Results: The 153Sm -labelled PS microspheres achieved a nominal activity of 4.0 GBq.g-1 after 6 hours of neutron activation. Scanning electron microscope (SEM) and particle size analysis show that the microspheres remained spherical with diameters within 15 – 60 μm after neutron activation. No long half-life radioimpurities were found in the samples as revealed by the gamma spectroscopy results. The 153Sm-labelled PS microspheres achieved radiolabeling efficiency of more than 95% in saline and blood plasma over 480 hours. Conclusion: A biocompatible 153Sm-radiolabelled PS microspheres formulation has been successfully developed. The formulation achieved desirable properties for theranostic treatment of liver tumours. The formulation is relatively cheaper, easier to be produced and more readily available.

Fulltext Anti-Candida activity and biofilm inhibitory effects of secreted products of tropical environmental yeasts

Tan HW, Tay ST

Trop Biomed, 2011 Apr;28(1):175-80.

PMID: 21602784

This study describes the killer phenotypes of tropical environmental yeasts and the inhibition effects of the culture filtrates on the biofilm of Candida albicans. A total of 26 (10.5%) of 258 yeast isolates obtained from an environmental sampling study demonstrated killer activity to Candida species. The killer yeasts were identified as species belonging to the genus Aureobasidium, Pseudozyma, Ustilago and Candida based on sequence analysis of the ITS1-5.8S-ITS2 region of the yeasts. Pseudozyma showed the broadest killing effects against sensitive strains of Candida. New species of Ustilago and Pseudozyma demonstrating killer phenotypes were identified in this study. Interestingly, more than 50% reduction in the metabolic activity of Candida albicans biofilm was noted after exposure to the culture filtrates of the nine killer yeasts. Purification and characterization of toxin and metabolites are essential for understanding the yeast killing effects.

Fulltext Drug interaction between cyclosporine A and quinine in a renal transplant patient with malaria

Tan HW, Ch'ng SL

Singapore Med J, 1991 Jun;32(3):189-90.

PMID: 1876897

We report a previously undocumented drug interaction between cyclosporine A and quinine. A 39 year old Asian with a recent renal transplant was diagnosed to have a mild cerebral falciparum malaria. He was treated with seven days of oral quinine (600 mg, 8 hourly), followed by a stat dose of pyrimethamine (75 mg)--sulfadoxime (1200mg) because of a strong suspicion of chloroquine resistant falciparum malaria. Using a polyclonal radioimmunoassay method, we measured morning trough cyclosporine A level before, during and after the quinine treatment. Results showed a gradual decrease in the cyclosporine A level from a baseline value of 328 ng/ml to 107 ng/ml after seven days of oral quinine with a subsequent rise to pre-treatment level after discontinuation of quinine. There was no significant change in the dose of cyclosporine A administered during the period of quinine treatment (4.05 to 3.83 mg/kg body weight). Biochemical liver function tests, serum creatinine and hematological parameters were also essentially unchanged during this period. In vitro study showed no significant methodological interference in the cyclosporine assay by quinine dihydrochloride. These findings suggest an in vivo drug interaction between cyclosporine A and quinine. The mechanism of this interaction is not clear. Further studies are required to confirm the significance of this observation. Quinine and its stereoisomer, quinidine should be used with caution until further information is available.

The inhibitory effects of aureobasidin A on Candida planktonic and biofilm cells

Tan HW, Tay ST

Mycoses, 2013 Mar;56(2):150-6.

PMID: 22882276 DOI: 10.1111/j.1439-0507.2012.02225.x

Aureobasidin A (AbA) is a cyclic depsipeptide antifungal compound that inhibits a wide range of pathogenic fungi. In this study, the in vitro susceptibility of 92 clinical isolates of various Candida species against AbA was assessed by determining the planktonic and biofilm MICs of the isolates. The MIC(50) and MIC(90) of the planktonic Candida yeast were 1 and 1 μg ml(-1), respectively, whereas the biofilm MIC(50) and MIC(90) of the isolates were 8 and ≥64 μg ml(-1) respectively. This study demonstrates AbA inhibition on filamentation and biofilm development of C. albicans. The production of short hyphae and a lack of filamentation might have impaired biofilm development of AbA-treated cells. The AbA resistance of mature Candidia biofilms (24 h adherent population) was demonstrated in this study.

Fulltext A cohort study of risk factors and clinical outcome predictors for patients presenting with unstable angina and non ST segment elevation myorardial infraction undergoing coronary intervention

Chong E, Shen L, Tan HC, Poh KK

Med J Malaysia, 2011 Aug;66(3):249-52.

PMID: 22111450

Thrombolysis in Myocardial Infarction (TIMI) score has been used to predict outcomes in patients presenting with unstable angina (UA) and non-ST elevation myocardial infarction (NSTEMI). Our study assessed other clinical predictors for patients with UA/NSTEMI undergoing early percutaneous coronary intervention (PCI).

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