MyMedR

[Clostridium bifermentans serovar malaysia, a new anaerobic bacterium pathogen to mosquito and blackfly larvae]

de Barjac H, Sebald M, Charles JF, Cheong WH, Lee HL

C. R. Acad. Sci. III, Sci. Vie, 1990;310(9):383-7.

PMID: 1972899

A strain of Clostridium bifermentans individualized as serovar malaysia (C.b.m.) according to its specific H antigen is toxic to mosquito and blackfly larvae when given orally. The toxicity occurs in sporulated cells which contain, in addition to spores, proteinic parasporal inclusion bodies and feather-like appendages; the amino acid content of the inclusion bodies is similar to that of Bacillus thuringiensis serovar israelensis (B.t.i.) and B. sphaericus crystals. The toxicity to Anopheles stephensi is as high as that of B.t.i. and the best strains of B. sphaericus. Culex pipiens is somewhat less susceptible, and Aedes aegypti much less. Pure parasporal inclusion bodies, isolated by ultracentrifugation on sucrose gradients, are highly toxic to mosquito larvae. The larvicidal power is destroyed by heating at 80 degrees C or by treatment with 50 mM NaOH. It is preserved by freeze-drying. The innocuity to mice of the sporulated cells is shown by different routes of administration: force-feeding, percutaneous, subcutaneous, intraperitoneal or intravenous injections. The potential for the biological control of mosquito and blackfly larvae is suggested.

Fermentation of a Malaysian Bacillus thuringiensis serotype H-14 isolate, a mosquito microbial control agent utilizing local wastes

Lee HL, Seleena P

Southeast Asian J. Trop. Med. Public Health, 1991 Mar;22(1):108-12.

PMID: 1948250

A screening program searching for indigenous microbial control agents of mosquitos in Malaysia is initiated since 1987 and to date at least 20 isolates of mosquitocidal Bacillus thuringiensis serotypes have been obtained. Preliminary field evaluation of several isolates indicated that they are highly effective in the control of medically important mosquito species. For operational purposes, there is an urgent need to produce this agent utilizing cheap and locally available wastes through fermentation biotechnology. Fermentation studies in shake-flasks containing standard nutrient broth and soya bean waste, respectively, indicate that it takes about 37 hours for a Malaysian isolate of B. thuringiensis serotype H-14 to mature. In the grated coconut waste, fishmeal and rice bran, the bacteria took 28 hours, 26 hours and 126 hours respectively to mature. The endotoxin was harvested from the standard nutrient broth at 55 hours and at 50 hours from soybean, grated coconut waste and fishmeal. The endotoxin could only be harvested 150 hours after inoculation from rice bran medium. However, no bacterial growth was detected in palm oil effluent. In terms of endotoxin and biomass production, fishmeal appears to be a suitable medium. Variations in the pH of the fermenting media were also noted.

Fulltext Human aural myiasis

Lee HL, Yong YK

Southeast Asian J. Trop. Med. Public Health, 1991 Jun;22(2):274-5.

PMID: 1948291

Fulltext Determination of insecticide susceptibility in Culex quinquefasciatus Say adults by rapid enzyme microassays

Lee HL, Abimbola O, Singh KI

Southeast Asian J. Trop. Med. Public Health, 1992 Sep;23(3):458-63.

PMID: 1488701

Rapid enzyme microassays for the detection of resistance due to organophosphate and carbamate in individual field-collected strains of Culex quinquefasciatus adults were conducted. These tests allowed accurate differentiation by eye, on the basis of color changes of susceptible and resistant individuals. Two separate tests were conducted for the biochemical assays. In the insensitive acetylcholinesterase (AChE) test, acetylthiocholine iodide (ACTH) and 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) were used as substrate and coupling agent respectively. The resulting yellow chromophore indicated AChE activity. Test results showed that the color intensity decreased as increasing concentrations of propoxur were added, thereby confirming the susceptibility of the enzyme to inhibitor. Assay of non-specific esterase however, indicated elevated levels which were correlated with degree of malathion resistance. Electrophoretic data revealed the presence of 2 esterase bands in all strains. It was concluded that such a pattern was not contributory to malathion resistance in adults.

Fulltext Bionomics of important mosquito vectors in Malaysia

Vythilingam I, Chiang GL, Lee HL, Singh KI

Southeast Asian J. Trop. Med. Public Health, 1992 Dec;23(4):587-603.

PMID: 1363679

Fulltext Acute appendicitis--the University Hospital experience

Lee HY, Jayalakshmi P, Noori SH

Med J Malaysia, 1993 Mar;48(1):17-27.

PMID: 8341168

A 1 year review of 529 cases of acute appendicitis, treated at the University Hospital in 1990, was performed. Perforation rate was 23.7% and delay in diagnosis was found to be significant. Patients above 50 years of age were particularly at risk. Diagnostic error was 19.3% and it was a problem not only in young women but also in children. Temperature and rectal examinations were not found to be helpful in the diagnosis in contrast to leukocytosis. Waiting time for operation was long (median 7 hours), be it for a perforated or a nonperforated appendicitis.

Antagonistic activities of mosquito larvicidal Bacillus sphaericus (Neide) against some pathogenic bacteria

Seleena P, Lee HL

Indian J Med Res, 1993 Mar;97:83-4.

PMID: 8505080

Mosquitocidal strains of B. sphaericus serotype H-5a5b were shown for the first time to exhibit antagonistic activities against several human pathogens especially Salmonella. These strains of B. sphaericus also exhibited high larval toxicity against several mosquitoes.

Clinical evaluation and serum concentration of zuclopenthixol acetate in psychotic Asian patients: a single-dose preliminary study

Tan CH, Low BL, Ng LL, Khoo YM, Lee HS

Ther Drug Monit, 1993 Apr;15(2):108-12.

PMID: 8099240

Nineteen acutely disturbed psychotic Asian patients were treated with a single intramuscular injection of 50 mg of zuclopenthixol acetate in Viscoleo. Patients were assessed clinically before and after treatment using the Brief Psychiatric Rating Scale (BPRS). Serum zuclopenthixol and the inactive geometric isomer trans(E)-clopenthixol were determined by high-performance liquid chromatography after intramuscular injection. All patients improved, with the BPRS being significantly reduced (p < 0.001) at 72 h after injection. Adverse effects were generally few. The mean +/- SEM serum zuclopenthixol concentrations at 24, 48, and 72 h were 19.9 +/- 2.8, 31.5 +/- 4.5, and 17.8 +/- 2.9 micrograms/L, respectively. trans(E)-Clopenthixol concentrations ranged from negligible to 39.5 micrograms/L. This study confirms that a single intramuscular injection of 50 mg is adequate for managing severely disturbed psychotic patients for the first 3 days. The serum zuclopenthixol concentrations attained in the Asian patients were higher than those reported in Caucasian psychiatric patients. In some patients, a considerable amount of zuclopenthixol had been transformed to trans(E)-clopenthixol.

Studies on the effect of translocation of chemical insecticides in Eicchornia host plant on Mansonia mosquitos--a potential control method

Lee HL, Singh KI

Southeast Asian J. Trop. Med. Public Health, 1993;24 Suppl 2:105-9.

PMID: 7526473

A novel method for the control of Mansonia larvae was developed and tested. In this method, foliar absorption and translocation of a chemical insecticide, monocrotophos, a known systemic insecticide was studied in the Eicchornia plant. Acetone solution of the insecticide was painted onto leaves of the plant. At daily intervals, stems were severed and divided into equal sections which were introduced into bowls. Larvae of Aedes aegypti were tested for the presence of monocrotophos. It was found that translocation of the insecticide occurred at different rates in the stems and in some plants the chemical was also released into the surrounding water. Based on these results, 2 insecticides namely, monocrotophos and temephos were painted onto leaves of the host plant and their translocation to the root and water environment was examined by testing with Mansonia and Aedes aegypti larvae. The results again confirmed the translocation process and it was found that the insecticides were secreted into the surrounding water, thereby killing the larvae. However, in leaves painted with permethrin (synthetic pyrethroid) or flufenoxuron (chitin synthesis inhibitor), such a process was not detected. The potential of this new concept in Mansonia larval control is examined.

Prevalence and determinants of cervical cancer screening: a community-based study in Singapore

Seow A, Lee HP

Ann Acad Med Singap, 1994 May;23(3):342-7.

PMID: 7944247

A cross-sectional survey of 568 married women aged 21-65 years in the Pasir Panjang Constituency was conducted to determine the prevalence of cervical cancer screening in the community and the factors affecting acceptance of this screening test. Results show that 309 (54.4%) of the respondents had ever had a Pap smear. The women who reported having had a smear were more likely to be below 45 years of age (prevalence ratio 1.47, 95% confidence interval 1.15 to 1.88), Chinese and of a higher socioeconomic status (1.68, 1.33 to 2.12). They were also more likely to have married at a later age (1.68, 1.21 to 2.31) than women who had not had a smear. Age and socioeconomic status remained independent predictors on multivariate analysis. The findings suggest that an important task of public health practitioners is to increase the uptake of screening among older and socially disadvantaged women who are known to be at the highest risk of cervical cancer. In addition, strategies to encourage younger women to continue regular attendance at screening clinics beyond their childbearing years will be important for the future.

Fulltext Monitoring resistance gene frequencies in Malaysian Culex quinquefasciatus Say adults using rapid non-specific esterase enzyme microassays

Lee HL, Tadano T

Southeast Asian J. Trop. Med. Public Health, 1994 Jun;25(2):371-3.

PMID: 7855659

The ability to identify the occurrence of different resistance genotypes in field populations of mosquito is considered important for the purpose of optimising chemical control operations. The recent development of rapid microassays of enzymes responsible for resistance has provided a means for rapidly assessing the genetic background of target mosquito populations. This concept is the topic of investigation in this study. Non-specific esterase activity, which is responsible for the resistance to organophosphates in Malaysian Culex quinquefasciatus Say adults, was determined in 3 field populations from Kuala Lumpur City using rapid enzyme assay. The optical density results were used to estimate the genotypic frequencies of the populations. Subsequently, time-dependent changes in the various frequencies were determined. Such techniques allowed rapid assessment of resistance genotypes for decision-making and its possible use in insect control merits further investigation.

Fulltext Absence of plasmid in mosquitocidal Clostridium bifermentans serovar malaysia

Seleena P, Lee HL

Southeast Asian J. Trop. Med. Public Health, 1994 Jun;25(2):394-6.

PMID: 7855665

Fulltext Glutathion S-transferase activity and DDT-susceptibility of Malaysian mosquitos

Lee HL, Chong WL

Southeast Asian J. Trop. Med. Public Health, 1995 Mar;26(1):164-7.

PMID: 8525405

Comparative DDT-susceptibility status and glutathion s-transferase (GST) activity of Malaysian Anopheles maculatus, Culex quinquefasciatus and Aedes aegypti was investigated to ascertain the role of this enzyme in DDT resistance. The standardised WHO dose-mortality bioassay tests were used to determine DDT susceptibility in these mosquitos, whilst GST microassay (Brogdon and Barber, 1990) was conducted to measure the activity of this enzyme in mosquito homogenate. It appeared that DDT susceptibility status of Malaysian mosquitos was not correlated with GST activity.

Pharmacokinetics of propofol infusion in Asian patients undergoing coronary artery bypass grafting

Lee HS, Khoo YM, Chua BC, Ng AS, Tan SS, Chew SL

Ther Drug Monit, 1995 Aug;17(4):336-41.

PMID: 7482686

The pharmacokinetics of propofol was studied in 11 Asian patients with fentanyl-isoflurane anaesthesia during cardiopulmonary bypass (CPB) and undergoing elective coronary artery bypass grafting (CABG). Instead of the usual increments of morphine and a benzodiazepine, propofol (4 mg/kg/h) was initiated at the start of CPB and ceased at CPB separation. Whole blood propofol concentrations were determined during and postinfusion using high-performance liquid chromatography with fluorescence detection. Data from four patients seemed to fit a two-compartment model, whereas those from seven patients were significantly (F test, p < 0.05) better fitted to a three-compartment model. The pharmacokinetic parameters were as follows: The mean (SD) of the initial distribution phase t1/2 pi, intermediate distribution phase t1/2 alpha, and elimination phase t1/2 beta were 2.22 (1.04) min, 42.9 (16.4) min, and 370 (138) min, respectively. The mean clearance of 1.31 (0.50) L/min was lower than those reported from other studies, whereas the mean blood concentration of 2.2 (1.0) mg/L at the 1-h infusion period was higher. The mean calculated apparent Css was 3.9 (1.5) mg/L. The low clearance is likely to be due to hemodynamic changes during CPB and CABG, thereby affecting drug distribution and blood flow to the liver.

Isolation and Identification of novel toxins from a new mosquitocidal isolate from Malaysia, Bacillus thuringiensis subsp. jegathesan

Kawalek MD, Benjamin S, Lee HL, Gill SS

Appl Environ Microbiol, 1995 Aug;61(8):2965-9.

PMID: 7487029

A new mosquitocidal Bacillus thuringiensis subsp., jegathesan, has recently been isolated from Malaysia. Parasporal crystal inclusions were purified from this strain and bioassayed against fourth-instar larvae of Culex quinquefasciatus, Aedes aegypti, Aedes togoi, Aedes albopictus, Anopheles maculatus, and Mansonia uniformis. The 50% lethal concentration of crystal inclusions for each species was 0.34, 8.08, 0.34, 17.59, 3.91, and 120 ng/ml, respectively. These values show that parasporal inclusions from this new subspecies have mosquitocidal toxicity comparable to that of inclusions isolated from B. thuringiensis subsp. israelensis. Solubilized and chymotrypsin-activated parasporal inclusions possessed low-level hemolytic activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the crystals were composed of polypeptides of 77, 74, 72, 68, 55, 38, 35, 27, and 23 kDa. Analysis by Western blotting (immunoblotting) with polyclonal antisera raised against toxins purified from B. thuringiensis subsp. israelensis reveals that proteins in parasporal inclusions of subsp. jegathesan are distinct, because little cross-reactivity was shown. Analysis of the plasmid content of B. thuringiensis subsp. jegathesan indicates that the genes for toxin production may be located on 105- to 120-kb plasmids. Cry- clones that have been cured of these plasmids are nontoxic. Southern blot analysis of plasmid and chromosomal DNA from subsp. jegathesan showed little or low homology to the genes coding for CryIVA, CryIVB, and CryIVD from B. thuringiensis subsp. israelensis.

How sexually permissive are Singaporeans?

Kok LP, Heng BH, Ong YW, Ho ML, Lee HP

Ann Acad Med Singap, 1995 Sep;24(5):679-84.

PMID: 8579309

This paper presents data on two surveys done in 1989 and 1992 that indicated the attitudes of Singaporeans to sexuality. Both surveys revealed that Singaporeans have sexually conservative attitudes and those who have a lower education, are single, above the age of 40, are Malays/Muslims hold more conservative views.

Fulltext A case of human enteric myiasis due to larvae of Hermetia illucens (Family: Stratiomyiadae): first report in Malaysia

Lee HL, Chandrawathani P, Wong WY, Tharam S, Lim WY

Malays J Pathol, 1995 Dec;17(2):109-11.

PMID: 8935136

A case of true enteric myiasis in a 7-year-old girl is reported. Two larvae were obtained from the vomitus of the patient. After processing and identification, the larvae were found to be those of Hermetia illucens (Soldier Fly). This is the first case of true enteric myiasis due to these larvae in Malaysia.

A new serovar of Bacillus thuringiensis possessing 28a28c flagellar antigenic structure: Bacillus thuringiensis serovar jegathesan, selectively toxic against mosquito larvae

Seleena P, Lee HL, Lecadet MM

J Am Mosq Control Assoc, 1995 Dec;11(4):471-3.

PMID: 8825511

A novel Bacillus thuringiensis strain highly toxic to mosquitoes was isolated from soil samples in Malaysia. This strain was shown to display a new subfraction of the H-28 flagellar antigen determining a new serovar H28a28c, which was designated serovar jegathesan. Bioassays indicated that Culex quinquefasciatus larvae are the most susceptible to this new isolate, whereas toxicity to Anopheles maculatus and Aedes aegypti larvae was 10 times lower. The potency of this new serotype is also comparable to most of the Malaysian B. thuringiensis H-14 isolates.

Breast cancer in Singapore: trends in incidence 1968-1992

Seow A, Duffy SW, McGee MA, Lee J, Lee HP

Int J Epidemiol, 1996 Feb;25(1):40-5.

PMID: 8666502

BACKGROUND: Breast cancer is the most commonly occurring cancer among women in Singapore, a country which has experienced significant changes in lifestyle over the past three decades. The increase in incidence of the disease is a matter of some concern.

METHODS: Data from the population-based Singapore Cancer Registry for 1968-1992 were used to determine time trends, inter-ethnic differences and the contributions of age, period and cohort effects to the incidence of the disease.

RESULTS: Our results revealed an average annual increase of 3.6% over the 25-year period for all women, form 20.2 per 100,000 women in the period 1968-1972 to 38.8 per 100,000 in 1988-1992. There was a statistically significant difference between the three major ethnic groups, the rate of increase being highest in Malays (4.4%) and lowest in Indians (1.4%). The overall increase was attributable to a strong cohort effect that remained significant when adjusted for time period for Chinese women and for all ethnic groups combined. The risk was observed to increase in successive birth cohorts from the 1890s to 1960s.

CONCLUSIONS: Our results suggest that breast cancer incidence rates are likely to continue to increase more sharply in the future as women born after the mid-20th century reach the high-risk age groups. They also suggest the pattern by which important aetiological factors for the disease in our population have exerted their effects, and provide support for the role of demographic and lifestyle changes as possible risk factors.

Fulltext Vacuum delivery at The Maternity Hospital Kuala Lumpur: a comparison of metal and silicone cups

Lee HY, Subramaniam N, Nordin MM

Singapore Med J, 1996 Feb;37(1):55-60.

PMID: 8783915

To compare the advantages and disadvantages of the New Bird metal cups and silicone cups in terms of maternal and foetal outcome. To study the adverse effects and factors associated with failed vacuum deliveries.

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