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Biomedical subjects

Viroj Wiwanitkit

Publications and source records attributed to Viroj Wiwanitkit.

At least 55 records · Page 3Linked to original sources
PubMed2006

An observation on correlation between rainfall and the prevalence of clinical cases of dengue in Thailand.

BACKGROUND AND OBJECTIVES: An investigation was carried out in Thailand to study the correlation between rainfall and prevalence of dengue infection during 2002-03, which can be used for prevention and control of the disease. METHODS: Rainfall data (2002-03) collected from Ministry of Public Health were utilised for transformation of the infection and the rainfall data were derived from Royal Irrigation Department, Thailand. The correlation between the rainfall and the prevalence of dengue was assessed by regression analysis. RESULTS: The least square equation plot prevalence (y) versus rainfall (x) is y = 3.0x + 4.6 (r = 0.78, p < 0.05) (r = 0.68, p < 0.05). INTERPRETATION AND CONCLUSION: The study indicated that the prevalence of dengue infection in Thailand may depend on rainfall. Therefore, the surveillance and control of mosquito should be intensified during the period with high rainfall is recommended. However, the other confounding factors like ambient temperature and humidity which also determine the transmission of dengue should be looked into, before concluding that the increased prevalence is a result of rainfall alone. Further, similar studies to assess the correlation between the rainfall and prevalence of infection in the other countries are required to confirm these observations.

Dengue↗
PubMed2006

High sister chromatid exchange among a sample of traffic policemen in Bangkok, Thailand.

There are several volatile substances from the traffic, including benzene, toluene, carbon monoxide, lead and formaldehyde. Most of these substances are considered carcinogens. Police are at occupational risk for toxic fume exposure. This study compared sister chromatid exchange (SCE), a marker for genotoxicity, among a sample of Thai traffic policemen in Bangkok with healthy control subjects. Thirty police officers (all male) and 20 controls were included in this study. The average (mean+/-SD) SCE for policemen and controls were 4.40+/-0.93/cell and 0.24+/-0.12/cell, respectively. A significantly higher SCE among the policemen was observed. Concern for and prevention of toxic substance exposure in traffic police officers should be made a national goal.

Case-Control Studies↗
PubMed2006

Detection of Cryptococcus neoformans in bird excreta.

We evaluated 14 samples of bird excreta from pigeons, parrots, open billed storks and crows obtained from thirteen places in Bangkok and nearby areas between April and July 2004. These bird excreta were examined for Cryptococcus neoformans by direct plating method to inspect their ability to grow at 37 degrees C. Capsule production was examined by Indian ink preparation. They were also tested for urease and phenoloxidase enzymes. Cryptococcus neoformans var neoformans was recovered from pigeon excreta in 9.09%. This implies those having impaired immunity may get this fungus from the environment.

Animals↗
PubMed2006

Secondary and tertiary structure aberration of alpha globin chain in haemoglobin Q-India disorder.

Hemoglobinopathies are important inherited disorders with considerable high prevalence in Asia. Hemoglobin Q-India is a hemoglobinopathy that was first identified in India. Hb Q-India is caused by the mutation GAC --> CAC at codon 64 of the alpha-1 globin gene. The correlation between this hemoglobinopathy and thalassemia was reported. Although primary structure of disorder Hb Q-India is well documented, the secondary and tertiary structures, which can help explain the pathogenesis of the Hb Q-India disorder is not known. In this study, amino acid sequence of human alpha globin was searched using ExPASY and used for further mutation to Hb Q-India disorder. The derived sequences, alpha globin chains in both normal and Hb Q-India disorder, were used for further investigation for secondary and tertiary structures. Modeling of these proteins for secondary and tertiary structures was done using the NNPREDICT server and CPHmodels 2.0 Server, respectively. In this study, the secondary and tertiary structures of human alpha globin chains of normal and hemoglobin Q-India disorder are calculated and presented. Based on this information, the main difference between the predicted alpha globin secondary structures of normal and Hb Q-India is an extra helix in the Hb Q-India. The predicted tertiary structure also supports this finding. The results from this study can be good data for further study on Hb Q-India disorder, which can bring to the further understanding on this hemoglobinopathy.

Amino Acid Sequence↗
PubMed2006

Ethics of clinical pathologist.

Laboratory investigation is a general process in every hospital. Due to the increasing number of laboratory tests, physicians need to have a full awareness to prevent non ethical practice in laboratory process. Every physician should be aware of the medical ethics for clinical pathology. The cores medical ethics for clinical pathology include: 1. Proper laboratory request: Request only necessary tests with indication, not request aimed at service change from the patient and request all required tests without bias on the patients socioeconomic status. 2. Proper specimen collection procedure: "first, do no harm" to the patient, practice gently and bring the least suffering to the patient. 3. Proper keeping of laboratory result: Keep patients' information confidential, and do not change the laboratory results to increase the returns. Explanations and examples on some problems relating to the three topics are presented in Table 1 to help the reader realize the importance of these cores values.

Ethics, Medical↗
PubMed2005

Quantum chemical analysis of alternative pathways for iron activation step for artemisinin, a new antimalarial drug.

Malaria is a mosquito-borne parasitic infection. It can be said that malaria is a very important tropical mosquito-borne infectious disease. The selection of antimalarial drugs depends on the species and the reported resistance pattern in each setting. Artemisinins are a new group of antimalarial drugs against the drug-resistant strains of malarial parasites. The mechanism of action of artemisinin compounds consists of two important steps: (a) activation and (b) alkylation. In the activation step by iron, there are two possible pathways for developing C-4 free radical: (a) 1.5 H-shift and (b) C-C cleavage. Here, the author performs a quantum chemical analysis of the activation reaction of artemisinin by the two alternative pathways. According to this study, the required energy for compound formation in C-C cleavage is more than that for C-O cleavage. It can be noted that the C-C cleavage pathway is less preferable, implying that the 1.5 H-shift should be the more common phenomenon.

Antimalarials↗
PubMed2005

A review of human sparganosis in Thailand.

BACKGROUND: Sparganosis is a zoonosis that occurs occasionally in humans. The infection is reported in many countries but is most common in eastern Asia. In Thailand, a southeast Asian country, the infection is sporadic. DESIGN: In this study the clinical presentations of human sparganosis cases in Thailand were investigated by means of a literature review. RESULTS: Reports of 34 cases of sparganosis were found. The infections were ocular (17 cases), subcutaneous (ten cases), central nervous system (five cases), auricular (one case), pulmonary (one case), intraosseous (one case) and intraperitoneal (one case). Of these 34 cases, 14 had risk behaviour reported, 12 had a history of drinking impure water, five had a history of eating frog or snake meat and two had a history of using frog or snake meat as a poultice. Some cases had more than one risk factor. CONCLUSION: Most cases of sparganosis in Thailand presented with superficial ocular mass lesions. The major risk behaviour in Thailand is drinking water contaminated with the infective organism. Some cases of serious deep visceral sparganosis have also been reported.

Adolescent↗
PubMed2005

Diagnostic value and cost utility analysis for urine Gram stain and urine microscopic examination as screening tests for urinary tract infection.

The aim of this study was to evaluate the diagnostic properties of urine Gram stain and urine microscopic examination for screening for urinary tract infection (UTI), and to perform an additional cost utility analysis. This descriptive study was performed on 95 urine samples sent for urine culture to the Department of Microbiology, Faculty of Medicine, Chulalongkorn University. The first part of the study was to determine the diagnostic properties of two screening tests (urine Gram stain and urine microscopic examination). Urine culture was set as the gold standard and the results from both methods were compared to this. The second part of this study was to perform a cost utility analysis. The sensitivity of urine Gram stain was 96.2%, the specificity 93.0%, the positive predictive value 94.3% and the negative predictive value 95.2%. False positives occurred with a frequency of 7.0% and false negatives 3.8%. For the microscopic examination, the sensitivity was 65.4%, specificity 74.4%, positive predictive value 75.6% and negative predictive value 64.0%. False positives occurred with a frequency of 25.6% and false negatives 34.6%. Combining urine Gram stain and urine microscopic examination, the sensitivity was 98.1%, specificity 74.4%, positive predictive value 82.3% and negative predictive value 97.0%. False positives occurred with a frequency of 25.6% and false negatives 1.9%. However, the cost per utility of the combined method was higher than either urine microscopic examination or urine Gram stain alone. Urine Gram stain provided the lowest cost per utility. Economically, urine Gram stain is the proper screening tool for presumptive diagnosis of UTI.

Costs and Cost Analysis↗