Browse publications by year: 2004

  1. Asi AM, Rahman NA, Merican AF
    J Mol Graph Model, 2004 Mar;22(4):249-62.
    PMID: 15177077
    Protein-ligand binding free energy values of wild-type and mutant C-terminal domain of Escherichia coli arginine repressor (ArgRc) protein systems bound to L-arginine or L-citrulline molecules were calculated using the linear interaction energy (LIE) method by molecular dynamics (MD) simulation. The binding behaviour predicted by the dissociation constant (K(d)) calculations from the binding free energy values showed preferences for binding of L-arginine to the wild-type ArgRc but not to the mutant ArgRc(D128N). On the other hand, L-citrulline do not favour binding to wild-type ArgRc but prefer binding to mutant ArgRc(D128N). The dissociation constant for the wild-type ArgRc-L-arginine complex obtained in this study is in agreement with reported experimental results. Our results also support the experimental data for the binding of L-citrulline to the mutant ArgRc(D128N). These showed that LIE method for protein-ligand binding free energy calculation could be applied to the wild-type and the mutant E. coli ArgRc-L-arginine and ArgRc-L-citrulline protein-ligand complexes and possibly to other transcriptional repressor-co-repressor systems as well.
    MeSH terms: Arginine/metabolism*; Arginine/chemistry; Bacterial Proteins*; Citrulline/metabolism*; Citrulline/chemistry; Computer Simulation*; Escherichia coli/genetics; Escherichia coli/metabolism; Models, Molecular; Protein Binding; Protein Conformation; Repressor Proteins/genetics; Repressor Proteins/metabolism*; Thermodynamics; Molecular Structure; Protein Structure, Tertiary; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism*
  2. Mustafa MR, Dharmani M, Kunheen NK, Sim MK
    Regul. Pept., 2004 Aug 15;120(1-3):15-22.
    PMID: 15177916
    An earlier study showed that des-aspartate-angiotensin I (DAA-I) attenuated the pressor action of angiotensin III in aortic rings of the spontaneously hypertensive rat (SHR) but not the normotensive Wistar Kyoto (WKY) rat. The present study investigated similar properties of DAA-I in isolated perfused kidneys and mesenteric beds of WKY and SHR. In the renal vasculature, angiotensin III induced a dose-dependent pressor response, which was more marked in the SHR than WKY in terms of significant greater magnitude of response and lower threshold. DAA-I attenuated the pressor action of angiotensin III in both the WKY and SHR. The attenuation in SHR was much more marked, occurring at doses as low as 10(-15) M DAA-I, while effective attenuation was only seen with 10(-9) M in WKY. The effects of DAA-I was not inhibited by PD123319 and indomethacin, indicating that its action was not mediated by angiotensin AT2 receptors and prostaglandins. However, the direct pressor action of angiotensin III in the SHR but not the WKY was attenuated by indomethacin suggesting that this notable difference could be due to known decreased response of renal vasculature to vasodilator prostaglandins in the SHR. Pressor responses to angiotensin III in the mesenteric vascular bed was also dose dependent, but smaller in magnitude compared to the renal response. The responses in the SHR, though generally smaller, were not significantly different from those of the WKY. This trend is in line with the similar observations with angiotensin III and II by other investigators. In terms of the effect of DAA-I, indomethacin and PD123319 on angiotensin III action, similar patterns to those of the renal vasculature were observed. This reaffirms that in the perfused kidney and mesenteric bed, where the majority of the vessels are contractile, femtomolar concentrations of DAA-I attenuates the pressor action of angiotensin III. The attenuation is not indomethacin sensitive and does not involve the angiotensin AT2 receptor. The findings suggest that DAA-I possesses protective vascular actions and is involved in the pathophysiology of hypertension.
    MeSH terms: Angiotensin I/analogs & derivatives*; Angiotensin I/pharmacology*; Angiotensin III/pharmacology*; Animals; Blood Pressure/drug effects; Blood Vessels/drug effects; Blood Vessels/innervation*; Cardiovascular Agents/pharmacology; Hypertension/physiopathology*; Imidazoles/pharmacology; Indomethacin/pharmacology; Kidney/drug effects*; Male; Prostaglandins/metabolism; Pyridines/pharmacology; Rats, Inbred SHR; Rats, Inbred WKY; Vasoconstrictor Agents/pharmacology; Mesenteric Artery, Superior/drug effects; Receptor, Angiotensin, Type 2/metabolism; Rats; Angiotensin II Type 2 Receptor Blockers
  3. Mohamed AS, McCulloch TM
    Laryngoscope, 2004 Jun;114(6):1128-9.
    PMID: 15179226
    MeSH terms: Cadaver; Equipment Design; Humans; Larynx/surgery*; General Surgery/education*; Teaching Materials*
  4. Peet M, Shah S, Selvam K, Ramchand CN
    World J Biol Psychiatry, 2004 Apr;5(2):92-9.
    PMID: 15179668
    There are several reports of reduced levels of polyunsaturated fatty acids (PUFA), particularly arachidonic acid (AA) and docosahexaenoic acid (DHA), in membrane phospholipid from various tissues including red blood cells (RBC) taken from schizophrenic patients. However, reports have not been entirely consistent and most studies have been confounded by the potential effects of environmental factors including antipsychotic medication and diet. We measured PUFA levels in RBC from two separate groups of unmedicated patients and control subjects from India and Malaysia, populations which have substantial differences in diet. We found no significant difference in levels of AA between patients and control subjects in either population. Levels of adrenic acid were significantly reduced, and levels of DHA significantly increased in both clinical populations. However, diet-related differences in DHA between the populations from India and Malaysia were much greater than differences between schizophrenic patients and controls. It is concluded that reduced RBC membrane levels of AA and DHA are not pathognomic of schizophrenia but that variations in cell membrane fatty acid levels are an epiphenomenon which may reflect underlying abnormalities of phospholipid and fatty acid metabolism and their interaction with environmental factors including medication and diet.
    MeSH terms: Chromatography, Thin Layer; Chronic Disease; Erythrocyte Membrane/metabolism*; Fatty Acids, Unsaturated/blood*; Humans; India; Malaysia; Schizophrenia/blood*; Schizophrenia/ethnology; Arachidonic Acid/blood
  5. Imran Y, Vishvanathan T
    Singapore Med J, 2004 Jun;45(6):280-2.
    PMID: 15181523
    Open fracture of the tibia is very common among motorcyclists. The morbidity associated with this injury is well-documented as treatment of severe open fractures is very difficult. There is currently no study done in the literature to see the relationship between fracture severity and the side of the injury.
    MeSH terms: Accidents, Traffic*; Adolescent; Adult; Aged; Aged, 80 and over; Child; Child, Preschool; Female; Fractures, Open/epidemiology*; Humans; Malaysia/epidemiology; Male; Middle Aged; Motorcycles*; Retrospective Studies; Severity of Illness Index; Tibial Fractures/epidemiology*; Incidence
  6. Abdullah JM, Rahman ZA, Ariff AR, Jaafar H, Phang KS
    Singapore Med J, 2004 Jun;45(6):286-8.
    PMID: 15181525
    Rhabdoid tumour is a rare childhood tumour with poor prognosis. We report a 13-month-old Malay girl suffering from this tumour that was located at the left fronto-temporo-parietal region of the brain. Computed tomography showed a large irregular enhancing mass that caused obstructive hydrocephalus. The tumour did not reduce in size after three operations and finally the patient succumbed to the disease four months after diagnosis.
    MeSH terms: Brain Neoplasms/diagnosis*; Brain Neoplasms/surgery; Craniotomy; Female; Humans; Infant; Reoperation; Tomography, X-Ray Computed; Fatal Outcome; Rhabdoid Tumor/diagnosis*; Rhabdoid Tumor/surgery
  7. Sudaryanto A, Takahashi S, Iwata H, Tanabe S, Ismail A
    Environ Pollut, 2004 Aug;130(3):347-58.
    PMID: 15182968
    Concentration of butyltin compounds (BTs), including tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) and total tin (SigmaSn) were determined in green mussel (Perna viridis), 10 species of muscle fish and sediment from coastal waters of Malaysia. BTs were detected in all these samples ranging from 3.6 to 900 ng/g wet wt., 3.6 to 210 ng/g wet wt., and 18 to 1400 ng/g dry wt. for mussels, fish and sediments, respectively. The concentrations of BTs in several locations of this study were comparable with the reported values from some developed countries and highest among Asian developing nations. Considerable concentration of BTs in several locations might have ecotoxicological consequences and may cause concern to human health. The parent compound TBT was found to be highest than those of its degradation compounds, DBT and MBT, suggesting recent input of TBT to the Malaysian marine environment. Significant positive correlation (Spearman rank correlation: r2=0.82, P<0.0001) was found between BTs and SigmaSn, implying considerable anthropogenic input of butyltin compounds to total tin contamination levels. Enormous boating activities may be a major source of BTs in this country, although aquaculture activities may not be ignored.
    MeSH terms: Animals; Environmental Monitoring/methods; Malaysia; Organotin Compounds/analysis*; Seawater/chemistry; Species Specificity; Trialkyltin Compounds/analysis; Water Pollutants, Chemical/analysis*; Geologic Sediments/chemistry; Bivalvia/metabolism*
  8. Khor TO, Gul YA, Ithnin H, Seow HF
    Cancer Lett, 2004 Jul 16;210(2):139-50.
    PMID: 15183529
    The enhancement of cell proliferation and promotion of cell survival via the inhibition of apoptosis is thought to be the key to the initiation and progression of cancers. The phosphatidylinositol-3 kinase (PI3K)/Akt is an important survival signal pathway that has been shown to be crucial in the regulation of balance between pro-apoptotic and survival (anti-apoptotic) signal. In this study, the expression of phosphorylated Akt at Thr308 and Ser473, BCL-2-antagonist of cell death (BAD) at Ser136 and glycogen synthase kinase-3beta (GSK-3beta) at Ser9 in 47 paraffin-embedded human colorectal carcinoma (CRC) tissues were determined by immunohistochemical staining in order to dissect the alterations in the signal transduction pathways in CRC. Our results showed that there was a significant increase in the expression of these biomolecules in CRC tissues compared to the apparently normal adjacent tissues. The frequency of increased expression in tumor colonic mucosa were as follows: p-Akt1/2/3 (Thr308) = 16/47 (34%); p-Akt1 (Ser473) = 21/47 (44.7%); phospho-BAD (p-BAD) Ser136 = 27/47 (57.4%) and phospho-GSK-3beta (p-GSK-3beta) = 21/47 (44.7%). Analysis of the total p-Akt1 (Ser473), p-Akt1/2/3 (Thr308), p-GSK-3beta (Ser9) and p-BAD (Ser136) score found that there was a statistically significant relationship with each other. A statistically significant positive linear relationship was found between total p-Akt (Ser473) score and total p-GSK-3beta (Ser9) score as well as with total p-BAD (Ser136) score. On the other hand, total p-Akt1/2/3 (Thr308) scores had a statistically significant positive linear relationship with p-GSK-3beta (Ser9) only. The Akt targets, p-GSK-3beta (Ser9) and p-BAD (Ser136) were positively correlated to each other. There was no significant correlation between clinico-pathological data with total p-Akt1 (Ser473), p-Akt1/2/3 (Thr308), p-GSK-3beta (Ser9) and p-BAD (Ser136) score except for age. The total scores of p-GSK-3beta were found to be higher in patients in the age group of greater than 60. This is the first report of p-Akt1/2/3 (Thr308) and p-BAD (Ser136) expression in primary colorectal tumor tissue. Our data further supports the role of PI3K/Akt signaling pathways in the pathogenesis of CRC and contributes to the identification of target molecules in the signal transduction pathway for cancer therapy.
    MeSH terms: Age Factors; Aged; Female; Humans; Immunohistochemistry; Male; Middle Aged; Phosphorylation; Proto-Oncogene Proteins/biosynthesis*; Proto-Oncogene Proteins/metabolism*; Serine/chemistry; Threonine/chemistry; Tumor Cells, Cultured; Colorectal Neoplasms/genetics; Colorectal Neoplasms/physiopathology*; Signal Transduction; Up-Regulation; Gene Expression Regulation, Neoplastic*; Apoptosis/drug effects*; Protein-Serine-Threonine Kinases/biosynthesis*; Protein-Serine-Threonine Kinases/metabolism*; Proto-Oncogene Proteins c-bcl-2/genetics*; Glycogen Synthase Kinase 3/biosynthesis*; Glycogen Synthase Kinase 3/genetics; Proto-Oncogene Proteins c-akt
  9. Tan LC, Venketasubramanian N, Hong CY, Sahadevan S, Chin JJ, Krishnamoorthy ES, et al.
    Neurology, 2004 Jun 08;62(11):1999-2004.
    PMID: 15184604
    OBJECTIVE: To investigate the prevalence of Parkinson disease (PD) in Singapore and compare the rates between Singaporean Chinese, Malays, and Indians.

    METHODS: A three-phase community-based survey among a disproportionate random sample of 15,000 individuals (9,000 Chinese, 3,000 Malays, 3,000 Indians) aged 50 years and above who live in central Singapore was conducted. In phase 1, trained interviewers conducted a door-to-door survey using a validated 10-question questionnaire. In phase 2, medical specialists examined participants who screened positive to any of the questions. Participants suspected to have PD had their diagnosis confirmed in phase 3 by a movement disorders specialist.

    RESULTS: The participation rate was 67% among 22,279 eligible individuals. Forty-six participants with PD were identified of which 16 were newly diagnosed cases. The prevalence rate of PD for those aged 50 and above in Singapore was 0.30% (95% CI: 0.22 to 0.41), age-adjusted to US 1970 census. The prevalence rates increased significantly with age. The age-adjusted prevalence rates among Chinese (0.33%, 95% CI: 0.22 to 0.48), Malays (0.29%, 95% CI: 0.13 to 0.67), and Indians (0.28%, 95% CI: 0.12 to 0.67) were the same (p = 1.0).

    CONCLUSIONS: The prevalence of PD in Singapore was comparable to that of Western countries. Race-specific rates were also similar to previously reported rates and similar among the three races. Environmental factors may be more important than racially determined genetic factors in the development of PD.

    MeSH terms: Aged; Aged, 80 and over; China/ethnology; Ethnic Groups/genetics*; Female; Health Surveys; Humans; India/ethnology; Malaysia/ethnology; Male; Middle Aged; Parkinson Disease/ethnology*; Parkinson Disease/epidemiology; Surveys and Questionnaires; Research Design; Sampling Studies; Singapore/epidemiology; Prevalence
  10. Ismail BS, Kalithasan K
    J Environ Sci Health B, 2004 May;39(3):419-29.
    PMID: 15186031
    The adsorption, desorption, and mobility of permethrin in six tropical soils was determined under laboratory and greenhouse conditions. The six soils were selected from vegetable growing areas in Malaysia. Soil organic matter (OM) was positively correlated (r2 = 0.97) with the adsorption of permethrin. The two soils, namely, Teringkap 1 and Lating series with the highest OM (3.2 and 2.9%) released 32.5 and 30.8% of the adsorbed permethrin after four consecutive repetitions of the desorption process, respectively, compared to approximately 75.4% of the Gunung Berinchang soil with the lowest OM (1.0%) under the same conditions. The mobility of permethrin down the soil column was inversely correlated to the organic matter content of the soil. Permethrin residue penetrated only to the 10-15 cm zone in the Teringkap 1 soil with 3.2% OM but penetrated to a depth of more than 20 cm in the other soils. The Berinchang series soil with the lowest OM (1.0%) yielded leachate with 14.8% permethrin, the highest level in leachates from all the soils tested. Therefore, the possibility for permethrin to contaminate underground water may be greater in the presence of low organic matter content, which subsequently allows a higher percentage of permethrin to move downwards through the soil column.
    MeSH terms: Adsorption; Environmental Exposure; Environmental Monitoring; Herbicides/chemistry; Kinetics; Malaysia; Organic Chemicals; Soil*; Soil Pollutants/analysis*; Soil Pollutants/poisoning; Permethrin/chemistry*
  11. Mak KH, Kark JD, Chia KS, Tan C, Foong BH, Chew SK
    Clin Cardiol, 2004 May;27(5):275-80.
    PMID: 15188942
    BACKGROUND: Ethnic differences in coronary mortality have been documented, and South Asians from the Indian subcontinent are particularly vulnerable.

    HYPOTHESIS: This study sought to determine whether there was a difference in the utilization of invasive cardiac procedures and long-term mortality in survivors of myocardial infarction (MI) among Chinese, Malays, and South Asians in Singapore.

    METHODS: All MI events in the country were identified and defined by the Singapore Myocardial Infarction Register, which uses modified procedures of the World Health Organization MONICA Project. Information on utilization of coronary angiography, coronary angioplasty, coronary artery bypass graft, and survival was obtained by data linkage with national billing and death registries. Hazard ratios (HR) were calculated using the Cox proportional hazards model with adjustment for baseline characteristics.

    RESULTS: From 1991 to 1999, there were 10,294 patients who survived > or = 3 days of MI. Of these, 40.6% underwent coronary angiography and 16.5% a revascularization procedure < or = 28 days. Malays received substantially less angiography (34.0%) and revascularization (11.4%) than Chinese (41.9%, 17.9%) and South Asians (40.0%, 16.3%). The ethnic disparity increased during the 1990s, particularly in the performance of coronary angiography (p = 0.038). While fatality declined during the study period for Chinese and South Asians, the rate remained stable for Malays. After a median follow-up period of 4.1 years, survival was lowest among Malays (adjusted HR, 1.28; 95% confidence interval, 1.15-1.42, compared with Chinese).

    CONCLUSION: Ethnic inequalities in invasive cardiac procedures exist in Singapore and were exacerbated in the 1990s. Inequalities in medical care may contribute to the poorer longterm survival among Malays.

    MeSH terms: Adult; Asia/ethnology; China/ethnology; Female; Health Services Accessibility; Humans; Malaysia/ethnology; Male; Middle Aged; Myocardial Infarction/ethnology*; Myocardial Infarction/mortality; Myocardial Infarction/surgery*; Myocardial Revascularization/statistics & numerical data*; Patient Acceptance of Health Care/ethnology; Retrospective Studies; Singapore/epidemiology; Survival Rate; Coronary Angiography/statistics & numerical data*; Asian Continental Ancestry Group*
  12. Ujang Z, Henze M, Curtis T, Schertenleib R, Beal LL
    Water Sci Technol, 2004;49(8):1-10.
    PMID: 15193088
    This paper presents the existing philosophy, approach, criteria and delivery of environmental engineering education (E3) for developing countries. In general, environmental engineering is being taught in almost all major universities in developing countries, mostly under civil engineering degree programmes. There is an urgent need to address specific inputs that are particularly important for developing countries with respect to the reality of urbanisation and industrialisation. The main component of E3 in the near future will remain on basic sanitation in most developing countries, with special emphasis on the consumer-demand approach. In order to substantially overcome environmental problems in developing countries, E3 should include integrated urban water management, sustainable sanitation, appropriate technology, cleaner production, wastewater minimisation and financial framework.
    MeSH terms: Cities; Developing Countries*; Ecology/economics; Ecology/education*; Education, Professional; Engineering/economics; Engineering/education*; Environmental Pollution/prevention & control; Forecasting*; Humans; Industry; Japan; Sanitation; Water Supply; Program Development; Waste Management; History, 20th Century
  13. Singh HJ, Rahman A, Larmie ET, Nila A
    Placenta, 2004 Aug;25(7):631-6.
    PMID: 15193869
    The aim of the study was to ascertain if there was any difference in the levels of prorenin and active renin between pre-eclamptic and normotensive feto-placental tissues.
    MeSH terms: Adult; Amnion/chemistry; Angiotensin I/analysis; Angiotensin I/metabolism; Angiotensin II/metabolism; Chorion/chemistry; Female; Humans; Placenta/chemistry*; Pre-Eclampsia/metabolism*; Pregnancy; Renin/analysis*
  14. Ismail BS, Ngan CK, Cheah UB, Abdullah WY
    Bull Environ Contam Toxicol, 2004 Apr;72(4):836-43.
    PMID: 15200001 DOI: 10.1007/s00128-004-0320-5
    MeSH terms: Agriculture; Environmental Monitoring; Malaysia; Pesticides/analysis*; Soil Pollutants/analysis*; Solubility; Water Movements; Water Pollutants, Chemical/analysis*; Ecosystem
  15. Salam A
    Med Teach, 2004 May;26(3):279.
    PMID: 15203509
    MeSH terms: Cross-Sectional Studies; Education, Medical, Undergraduate/methods*; Educational Measurement; Humans; Malaysia; Surveys and Questionnaires; Students, Medical/psychology*; Problem-Based Learning*
  16. Omar E, Madhavan M, Othman NH
    Pathology, 2004 Apr;36(2):152-9.
    PMID: 15203751
    To investigate RET and p53 expression in local thyroid lesions, in order to shed light on the pathogenesis of papillary carcinoma and explain the high prevalence of this condition among the nodular hyperplasia (multi-nodular goitre) cases.
    MeSH terms: Adenocarcinoma, Papillary/metabolism*; Adenocarcinoma, Papillary/epidemiology; Adenocarcinoma, Papillary/secondary; Adenoma/metabolism*; Adenoma/epidemiology; Adenoma/pathology; Adolescent; Adult; Aged; Female; Goiter, Nodular/metabolism*; Goiter, Nodular/epidemiology; Goiter, Nodular/pathology; Humans; Immunoenzyme Techniques; Malaysia/epidemiology; Male; Middle Aged; Mutation; Neoplasm Recurrence, Local; Proto-Oncogene Proteins/metabolism*; Thyroid Neoplasms/metabolism*; Thyroid Neoplasms/epidemiology; Thyroid Neoplasms/pathology; Thyroidectomy; Survival Rate; Tumor Suppressor Protein p53/genetics; Tumor Suppressor Protein p53/metabolism*; Receptor Protein-Tyrosine Kinases/metabolism*; Proto-Oncogene Proteins c-ret
  17. Chur-Hansen A
    Med Teach, 2004 Jun;26(4):343-8.
    PMID: 15203848
    International students' medical training often includes an elective placement in their home country to prepare them for practice on graduation. Seven Malaysian students in their final year of medicine were interviewed pre- and post-graduation and asked to reflect on whether they felt adequately prepared for working in Malaysia. These seven international students, who studied medicine in Australia, all returned to Malaysia for six weeks for their elective, and the interviews canvassed their perceptions of this experience, along with their thoughts on how well their training in Australia had prepared them for working in their country of origin. The interview data were qualitatively analysed, and case studies were constructed. Main themes were identified and tabulated. Students voiced similar concerns about how ready they were for working at home. These included a lack of practical skills relative to their Malaysian-trained counterparts, language difficulties, medical communication skill incompatibilities across cultures, expectations to perform complex or unfamiliar tasks with minimal supervision and substantial burdens of responsibility with long working hours. These students did not feel greatly prepared for their return home to practise medicine. The elective placement was not well utilized by the majority of students in this study.
    MeSH terms: Education, Medical/organization & administration*; Foreign Medical Graduates/psychology*; Humans; Interviews as Topic; Longitudinal Studies; Malaysia; South Australia
  18. Chee HY, AbuBakar S
    Biochem Biophys Res Commun, 2004 Jul 16;320(1):11-7.
    PMID: 15207695
    Binding of dengue virus 2 (DENV-2) to C6/36 mosquito cells protein was investigated. A 48 kDa DENV-2-binding C6/36 cells protein (D2BP) was detected in a virus overlay protein-binding assay. The binding occurred only to the C6/36 cells cytosolic protein fraction and it was inhibited by free D2BP. D2BP was shown to bind to DENV-2 E in the far-Western-binding studies and using mass spectrometry (MS) and MS/MS, peptide masses of the D2BP that matched to beta-tubulin and alpha-tubulin chains were identified. These findings suggest that DENV-2 through DENV-2 E binds directly to a 48 kDa tubulin or tubulin-like protein of C6/36 mosquito cells.
    MeSH terms: Amino Acid Sequence; Animals; Binding Sites; Cell Line; Dengue Virus/metabolism*; Molecular Sequence Data; Molecular Weight; Culicidae/metabolism*; Culicidae/virology*; Protein Binding; Tubulin/metabolism; Tubulin/chemistry*; Viral Envelope Proteins/metabolism; Viral Envelope Proteins/chemistry*; Sequence Alignment; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*; Insect Proteins/metabolism; Insect Proteins/chemistry*; Protein Interaction Mapping/methods*
  19. Sosroseno W
    Immunopharmacol Immunotoxicol, 2004 May;26(2):309-13.
    PMID: 15209366
    The aim of this study was to determine the effect of L-arginine on Porphyromonas gingivalis-induced phagocytosis by RAW264.7 cells. The cells were pretreated with L-arginine or D-arginine prior to incubation with either unopsonized or opsonized P. gingivalis. In other experiments, the cells were pretreated with L-arginine and various concentrations of NMLA (N(G)-monomethyl-L-arginine) prior to incubation with the bacteria. The phagocytosis was microscopically assessed and determined by the phagocytic index. The results showed that L-arginine, but not D-arginine enhances the ability of RAW264.7 cells to engulf the bacteria. The upregulatory effect of L-arginine on P. gingivalis-induced phagocytosis was abolished by NMLA. The results of the present study suggest that L-arginine may upregulate the P. gingivalis-induced phagocytic activity of RAW264.7 cells, perhaps, via modulation of nitric oxide synthase.
    MeSH terms: Animals; Arginine/pharmacology*; Cell Line; Macrophages/drug effects*; Macrophages/immunology*; Macrophages/microbiology; Phagocytosis/drug effects*; Porphyromonas gingivalis/immunology*; Porphyromonas gingivalis/pathogenicity*; omega-N-Methylarginine/pharmacology; Mice
  20. Fix AG
    Am J Hum Biol, 2004 Jul-Aug;16(4):387-94.
    PMID: 15214057
    Migration among local populations classically has been seen as the principal process retarding genetic microdifferentiation. However, as Sewall Wright pointed out long ago, migration may also act as a random differentiating force. In fact, when migrants comprise a biological kin group, migration may be considered a component of genetic drift. The causes of kin-structured migration (KSM) lie in the common, if not universal, tendency for kin to associate and cooperate. However, similar to genetic drift, KSM has its greatest effect in smaller populations and is most apparent in low-density fission-fusion societies such as the Yanomamo of South America and the Semai of Malaysia, and less salient in higher density, low-mobility populations such as those of the New Guinea Highlands. The evolutionary consequences of KSM begin with increased genetic variation among populations. Such intergroup variation provides a basis for group selection. The origin of larger-scale geographic differentiation can arise from kin-structured migrant groups colonizing new regions. Waves of colonizing kin-structured founder groups may produce gene frequency clines, mimicking demic diffusion and natural selection. Finally, because kin structuring reduces the effective size of a population, it may be speculated that the extremely small effective size inferred for ancestral populations of Homo sapiens may be an artifact of kin-structured demographically larger populations.
    MeSH terms: Emigration and Immigration*; Biological Evolution; Family*; Hemoglobin E/genetics; Humans; Malaysia; Models, Genetic; Polymorphism, Genetic; Genetic Variation/genetics*; Global Health; Genetic Drift
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