Displaying publications 1 - 20 of 373 in total

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  1. Lee HB, Ho AS, Teo SH
    Cancer Chemother Pharmacol, 2006 Jul;58(1):91-8.
    PMID: 16211395
    Given that p53 is a tumor suppressor that plays a central role in the cellular response to DNA damage and that more than 50% of all cancers have mutated p53, the wider utility of photodynamic therapy (PDT) in the treatment of cancer will depend on an understanding of whether p53 status modulates response to PDT. In this study, we investigated the photosensitivity of isogenic cell lines that differ only in their p53 status to PDT using hypericin as the photosensitizer.
  2. 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.
  3. Yap KL, Kalpana M, Lee HL
    Trop Biomed, 2008 Apr;25(1):1-8.
    PMID: 18600198
    The importance of house fly (Musca domestica L) wings in mechanical transmission of bacteria was studied. A droplet of phosphate-buffered saline containing Vibrio cholerae was rolled along one wing of each house fly. None adhered to the wings but small proportions of the bacterium were isolated from about half the wings. Vibrio cholerae was spread onto the ventral wing surfaces of each unconscious house fly which then was placed inside a bottle. When it regained consciousness, the types of activity it performed over five minutes were noted before the house fly was killed and the bacteria on its wings numerated. Control were house flies killed before inoculation. The proportion of house flies with bacteria on their wings and the mean number of bacteria remaining were significantly less on live house flies than killed controls. Among the live house flies, bacteria were detected on fewer house flies which flew (25%) than those which did not fly (81%). In addition, the mean number of bacteria on the former was significantly less than the latter (5 against 780 colonies). However, both these parameters were not significantly different between the group which performed and the group which did not perform wing grooming; takeoff and alighting over short distances, and somersaulting. Wings of unconscious house flies tethered by their thoraxes were inoculated with V. cholerae. After regaining consciousness, the house flies were allowed to move their wings in flight motions for up to 30 seconds. Small proportions of bacteria remained on all the house flies. House flies were placed in a chamber containing a liquid bait spiked with V. cholerae. After two hours, 10 were removed sequentially and cultured for V. cholerae. The bacterium was isolated from four house flies: two from the legs, and two others from their bodies minus legs and wings. In conclusion, house fly wings do not play an important role in mechanical transmission of bacteria suspended in a non-adhering liquid medium because of the low transfer rate of the bacteria to the wings and poor retention of bacteria on the wings during normal house fly activities.
  4. Chen CD, Nazni WA, Lee HL, Sofian-Azirun M
    Trop Biomed, 2005 Dec;22(2):195-206.
    PMID: 16883288 MyJurnal
    Larvae of Aedes aegypti and Aedes albopictus obtained from 6 consecutive ovitrap surveillance (OS) in Taman Samudera and Kg. Banjar were evaluated for their susceptibility to temephos. Larval bioassays were carried out in accordance with WHO standard methods, with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos respectively. Aedes aegypti and Ae. albopictus obtained from six OS in Taman Samudera showed resistance to diagnostic dosage of temephos with percentage mortality between 5.3 to 72.0 and 9.3 to 56.0, respectively, while Ae. aegypti and Ae. albopictus obtained from Kg. Banjar showed resistance to temephos with percentage mortality between 16.0 to 72.0 and 0 to 50.6, respectively. Only two strains of Ae. aegypti from Kg. Banjar were susceptible to temephos with 93.3% (OS 2) and 100% (OS 3) mortality. The 50% mortality at lethal time (LT50) for all strains of Ae. aegypti and Ae. albopictus tested against operational dosage of temephos showed range between 36.07 to 75.69 minutes and 58.65 to 112.50 minutes, respectively, and complete mortality was achieved after 24 hours. Our results indicated that there is weekly variations of the resistance status for Ae. aegypti and Ae. albopictus. Aedes susceptibility to temephos is changing from time to time in these two study sites. It is essential to continue monitoring the resistance of this vector to insecticides in order to ensure the efficiency of program aimed at vector control and protection of human health.
  5. Lau KW, Chen CD, Lee HL, Izzul AA, Asri-Isa M, Zulfadli M, et al.
    Trop Biomed, 2013 Mar;30(1):36-45.
    PMID: 23665706 MyJurnal
    The aim of the present study was to determine the vertical distribution and abundance of Aedes mosquitoes in multiple storey buildings in Selangor and Kuala Lumpur, Malaysia. Ovitrap surveillance was conducted for 4 continuous weeks in multiple storey buildings in 4 residential areas located in Selangor [Kg. Baiduri (KB)] and Kuala Lumpur [Student Hostel of University of Malaya (UM), Kg. Kerinchi (KK) and Hang Tuah (HT)]. The results implied that Aedes mosquitoes could be found from ground floor to highest floor of multiple storey buildings and data from different elevation did not show significant difference. Ovitrap index for UM, KB, HT and KK ranged from 0 - 29.17%, 0 - 55.56%, 8.33 - 83.33% and 0 - 91.17% respectively. Aedes aegypti and Aedes albopictus were found breeding in HT, KK and KB; while only Ae. albopictus was obtained from UM. The results indicate that the invasion of Aedes mosquitoes in high-rise apartments could facilitate the transmission of dengue virus and new approaches to vector control in this type of residential area should be developed.
  6. Wan-Norafikah O, Nazni WA, Noramiza S, Shafa'ar-Ko'ohar S, Azirol-Hisham A, Nor-Hafizah R, et al.
    Trop Biomed, 2010 Dec;27(3):662-7.
    PMID: 21399609
    A preliminary study on the vertical dispersal of Aedes populations in high-rise apartments was carried out in Presint 9, Putrajaya, Malaysia. Ovitraps were placed indoors within four blocks of high-rise apartments from the ground floors (0.0 - 3.0 m) until up to the tenth floors (28.1 - 30.0 m). Aedes aegypti was the dominant species found in the ovitraps (87.85%), while Aedes albopictus was found in lower numbers. From total number of larvae collected (650), 40.92% of these larvae were obtained from the fourth block; Block D. The peak density of Aedes sp. was observed at level 6 (16.1 - 18.0 m), while Ae. aegypti was found until the tenth floor (28.1 - 30.0 m). In contrast, Ae. albopictus was found only up to the sixth floor (16.1 - 18.0 m). A poor correlation of the mean number of Aedes larvae collected with the level of high-rise apartments occupied (N=40; ρ=-0.349) was also observed which indicated the possibility of lesser Aedes populations to be found at higher level of high-rise apartments. Therefore, larger scale studies are strongly recommended to examine the vertical dispersal of Aedes mosquitoes.
  7. Lee HS
    Ther Drug Monit, 1984;6(2):182-8.
    PMID: 6740737
    In a study with 113 Asian children in which phenobarbitone was used as the sole antiepileptic drug in 75 children, including Chinese, Malays, and Indians, the mean phenobarbitone dosage required to produce a plasma level of 15 micrograms/ml was 5.2 mg/kg/day. While the mean plasma level/dose ratio varied, the differences between the three ethnic groups were not statistically significant. Also of little difference were the ratios between the male and female groups. For those patients with poor seizure control, however, the mean plasma level/dose ratio was significantly lower than in those whose seizures were controlled. Using additional anticonvulsant drugs concurrently with phenobarbitone in 40 children raised the mean plasma level/dose ratios significantly in each ethnic group. Further, the greater age level in those given additional antiepileptic drugs might have contributed slightly to a higher mean plasma level/dose ratio.
  8. 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.
  9. Gaydos CA, Ngeow YF, Lee HH, Canavaggio M, Welsh LE, Johanson J, et al.
    Sex Transm Dis, 1996 9 1;23(5):402-6.
    PMID: 8885072
    BACKGROUND AND OBJECTIVES: Noninvasive urine screening for Chlamydia trachomatis infections offers a valuable public health tool, which could be of vast importance in chlamydial control programs. The authors evaluated a new DNA amplification method, ligase chain reaction (LCR).

    GOALS: The goal was to ascertain whether urine testing could be used as screening method to detect C. trachomatis infections in commercial sex workers, patients at sexually transmitted diseases clinic, and asymptomatic patients in Kuala Lumpur, Malaysia.

    METHODS: First-void urine specimens from 300 men and 300 women were tested by LCR, as well as by a commercially available enzyme immunoassay. The LCR assay amplifies specific sequences within the chlamydial plasmid with ligand-labeled probes, and the resultant amplicons are detected by an automated immunoassay. Specimens with discrepant results were confirmed by another LCR of the specimen that targeted the gene for the major outer membrane protein (OMP1).

    RESULTS: There were 31 LCR-positive male urine and 37 LCR-positive female urine specimens. The resolved sensitivity and specificity for the LCR of the male urine specimens were 100% and 99.6%, respectively, whereas for female urine specimens, the sensitivity and specificity were 100% and 98.5%, respectively. After resolution of discrepant test results by OMP1 LCR, the prevalence was 10% for men and 11% for women. The urine enzyme immunoassay was not useful in diagnosing C. trachomatis infections in either men or women, as the resolved sensitivities were 10% and 15.2%, respectively. The specificities were 99.6% for men and 98.9% for women.

    CONCLUSIONS: Testing first-void urine specimens by LCR is a highly sensitive and specific method to diagnose C. trachomatis infections in men and women, providing health care workers and public health officials with a new molecular amplification assay that uses noninvasive urine specimens for population-based screening purposes.

  10. Son HJ, Lee H, Kim JH, Yu IK, Han HY
    Malays J Pathol, 2018 Apr;40(1):73-78.
    PMID: 29704388
    Progressively transformed germinal centers (PTGC) is a benign process characterised by a morphological variant of reactive follicular hyperplasia in lymph nodes. It was recently shown that some cases of PTGC are associated with IgG4-related disease (IgG4-RD) or increased IgG4 plasma cells. Five years ago, a 57-year-old woman presented with enlargement of multiple lymph nodes in the left parotid, submandibular, and neck areas, pathologically diagnosed as PTGC after excisional biopsy. Since then, she has experienced numbness in her extremities, especially the left shoulder and arm, pruritus on the left side of the face and intermittent facial palsy, for which she has been receiving regular symptomatic treatment. Recently the patient developed diabetes mellitus (approximately seven months ago). In routine follow-up scans, a mass was detected in left kidney and magnetic resonance imaging of the abdomen prior to surgery revealed a slightly enhanced bulky mass replacing the pancreatic tail and uncinate process. The mass in left kidney was diagnosed as clear cell renal cell carcinoma, and the pathological features of the pancreatic lesion were those of IgG4-related chronic fibrosing pancreatitis. Retrograde examination of the neck lymph node diagnosed as PTGC showed increased deposition of IgG4-positive plasma cells.
  11. Basivi PK, Ramesh S, Kakani V, Yadav HM, Bathula C, Afsar N, et al.
    Sci Rep, 2021 May 10;11(1):9918.
    PMID: 33972653 DOI: 10.1038/s41598-021-89430-x
    In this study, a novel nanohybrid composite containing nitrogen-doped multiwalled carbon nanotubes/carboxymethylcellulose (N-MWCNT/CMC) was synthesized for supercapacitor applications. The synthesized composite materials were subjected to an ultrasonication-mediated solvothermal hydrothermal reaction. The synthesized nanohybrid composite electrode material was characterized using analytical methods to confirm its structure and morphology. The electrochemical properties of the composite electrode were investigated using cyclic voltammetry (CV), galvanic charge-discharge, and electrochemical impedance spectroscopy (EIS) using a 3 M KOH electrolyte. The fabricated composite material exhibited unique electrochemical properties by delivering a maximum specific capacitance of approximately 274 F g-1 at a current density of 2 A g-1. The composite electrode displayed high cycling stability of 96% after 4000 cycles at 2 A g-1, indicating that it is favorable for supercapacitor applications.
  12. Lee HL, Gregorio ER, Khadri MS, Seleena P
    J Am Mosq Control Assoc, 1996 Dec;12(4):651-5.
    PMID: 9046471
    Evaluation of the effectiveness of Bacillus thuringiensis ssp. israelensis (B.t.i.) against mosquito larvae dispersed by ultralow volume (ULV) spraying was conducted in simulated field trials. Effectiveness was measured using 3 different indicators: larval mortality, colony-forming unit enumeration, and droplet analysis. B.t.i. was dispersed with a ULV generator using 2 different flow rates: 0.3 and 0.5 liter/min on 2 different days. Based on the results of this study, it can be concluded that an output of 0.3 liter/min is effective for controlling Aedes aegypti. although a dosage of 0.5 liter/min can be used when high residual activity is desired. For Culex quinquefasciatus control, both dosages were effective but with low residual activity. For Anopheles maculatus control, only a discharge rate of 0.5 liter/min was effective with low residual activity. B.t.i. application at both dosages penetrated tires well, indicating that B.t.i. ULV application is an effective method for controlling container-inhabiting mosquitoes. Good coverage of target area and penetration were attributed to satisfactory droplet profiles.
  13. CoRe, H. W., Lee, H. L., M. Sofian-Azirun, Nura-Muna, A. H., Chen, C. D., O. Wan-Norafikah
    MyJurnal
    The efficacy of a 2.15% imidacloprid gel bait against laboratory strain Periplaneta americana and Blattella germanica
    was evaluated under laboratory conditions. The susceptibility trend of both species towards imidacloprid was: adult male
    < adult female < nymphs. All stages of both species were dead within 10 days in primary poisoning testing. Periplaneta
    americana adult male (LT50 = 0.47 h; LT95 = 5.24 h) died fastest, while nymphs of B. germanica took the longest time to
    reach 95% mortality (LT95 = 43.84 h). In indirect exposure via secondary poisoning, only adult males of P. americana (LT50
    = 100.63 h) and B. germanica (LT50 = 54.66 h) obtained 50% mortality before the testing ended. No complete mortalities
    were achieved in any stages of both species within 10 days of secondary poisoning testing. Therefore, imidacloprid gel
    bait used in this study was able to cause complete mortalities within less than 2 days of 10-day primary poisoning testing
    but less effective in the 10-day secondary poisoning testing.
  14. Lee KK, Kassim AM, Lee HK
    Water Sci Technol, 2004;50(5):73-7.
    PMID: 15497832
    White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.
  15. Rohani A, Wong YC, Zamre I, Lee HL, Zurainee MN
    PMID: 19842378
    Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes albopictus Skuse cell line and used to infect adult female Aedes aegypti mosquitoes. Each serotype was mixed separately with fresh human erythrocytes and fed to adult female mosquitoes using an artificial membrane feeding technique. Fully engorged mosquitoes were selected and retained at 26 degrees C, 28 degrees C and 30 degrees C to observe dengue virus development in Aedes vectors. Virus detection was carried out by reverse-transcriptase polymerase chain reaction (RT-PCR). The virus was first detected on Day 9 at 26 degrees C and 28 degrees C and on Day 5 at 30 degrees C for both dengue 2 and 4. The study shows the incubation period of the viruses decreased when the extrinsic incubation temperature increases.
  16. Du C, Zan MCH, Cho MJ, Fenton JI, Hsiao PY, Hsiao R, et al.
    Nutrients, 2021 Jan 29;13(2).
    PMID: 33572863 DOI: 10.3390/nu13020442
    BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has increased the already high levels of stress that higher education students experience. Stress influences health behaviors, including those related to dietary behaviors, alcohol, and sleep; yet the effects of stress can be mitigated by resilience. To date, past research studying the connections between dietary behaviors, alcohol misuse, sleep, and resilience commonly investigated singular relationships between two of the constructs. The aim of the current study was to explore the relationships between these constructs in a more holistic manner using mediation and moderation analyses.

    METHODS: Higher education students from China, Ireland, Malaysia, South Korea, Taiwan, the Netherlands, and the United States were enrolled in a cross-sectional study from April to May 2020, which was during the beginning of the COVID-19 pandemic for most participants. An online survey, using validated tools, was distributed to assess perceived stress, dietary behaviors, alcohol misuse, sleep quality and duration, and resilience.

    RESULTS: 2254 students completed the study. Results indicated that sleep quality mediated the relationship between perceived stress and dietary behaviors as well as the relationship between perceived stress and alcohol misuse. Further, increased resilience reduced the strength of the relationship between perceived stress and dietary behaviors but not alcohol misuse.

    CONCLUSION: Based on these results, higher education students are likely to benefit from sleep education and resilience training, especially during stressful events.

  17. Nurin-Zulkifli IM, Chen CD, Wan-Norafikah O, Lee HL, Faezah K, Izzul AA, et al.
    PMID: 26867376
    Surveillance of mosquitoes and their distribution in association with rainfall, relative humidity, and temperature were conducted in selected suburban and forested areas, namely, Sungai Penchala (Kuala Lumpur) and Taman Alam (Selangor) for 12 months. Armigeres kesseli was the most abundant species in Sungai Penchala while Aedes butleri was the most dominant species in Taman Alam. A positive correlation between mosquito distribution and rainfall was observed in selected mosquito species in Sungai Penchala (Armigeres kesseli, r = 0.75; Armigeres subalbatus, r = 0.62; and Aedes albopictus, r = 0.65) and Taman Alam (Armigeres sp, r = 0.59; Ae. butleri, r = 0.85; and Ae. albopictus, r = 0.62). However, no significant cor- relation was found either between selected mosquito species in both study areas and relative humidity or temperature. Results obtained suggested that vector control programs to be conducted based on temporal distribution of vectors in order to achieve beneficial outcomes with effective costing.
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