Displaying publications 1 - 20 of 33 in total

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  1. Balraj P, Khoo AS, Volpi L, Tan JA, Nair S, Abdullah H
    Singapore Med J, 2002 Apr;43(4):194-7.
    PMID: 12188064
    Thirty patients with early onset breast cancer or familial breast cancer from Malaysia were analysed for germline mutation in the early onset breast cancer I gene (BRCA1). Direct sequencing of the entire coding region of BRCA1 identified a frameshift mutation, c.5447-5448insC (insC5447) (codon 1776 of exon 21) in a patient aged 32 of the Malay ethnic origin, who had no family history of breast and/or ovarian cancer. Eight polymorphisms (2201C > T, 2430T > C, P871L, E1038G, K1183R, 4427T > C, S1613G and IVS8-57delT) were identified in the samples tested.
  2. Nair S, Schreiber E, Thong KL, Pang T, Altwegg M
    J Microbiol Methods, 2000 Jun;41(1):35-43.
    PMID: 10856775
    Amplified fragment length polymorphism (AFLP) is a recently developed, PCR-based high resolution fingerprinting method that is able to generate complex banding patterns which can be used to delineate intraspecific genetic relationships among bacteria. In the present study, AFLP was evaluated for its usefulness in the molecular typing of Salmonella typhi in comparison to ribotyping and pulsed-field gel electrophoresis (PFGE). Six S. typhi isolates from diverse geographic areas (Malaysia, Indonesia, India, Chile, Papua New Guinea and Switzerland) gave unique, heterogeneous profiles when typed by AFLP, a result which was consistent with ribotyping and PFGE analysis. In a further study of selected S. typhi isolates from Papua New Guinea which caused fatal and non-fatal disease previously shown to be clonally related by PFGE, AFLP discriminated between these isolates but did not indicate a linkage between genotype with virulence. We conclude that AFLP (discriminatory index=0.88) has a higher discriminatory power for strain differentiation among S. typhi than ribotyping (DI=0.63) and PFGE (DI=0.74).
  3. Nair S, Lin TK, Pang T, Altwegg M
    J Clin Microbiol, 2002 Jul;40(7):2346-51.
    PMID: 12089246
    PCR-restriction fragment length polymorphism (PCR-RFLP) and PCR-single-strand conformation polymorphism (PCR-SSCP) analyses were carried out on the 1.6-kb groEL gene from 41 strains of 10 different Salmonella serovars. Three HaeIII RFLP profiles were recognized, but no discrimination between the serovars could be achieved by this technique. However, PCR-SSCP analysis of the groEL genes of various Salmonella serovars produced 14 SSCP profiles, indicating the potential of this technique to differentiate different Salmonella serovars (interserovar differentiation). Moreover, PCR-SSCP could differentiate strains within a subset of serovars (intraserovar discrimination), as three SSCP profiles were produced for the 11 Salmonella enterica serovar Enteritidis strains, and two SSCP profiles were generated for the 7 S. enterica serovar Infantis and five S. enterica serovar Newport strains. PCR-SSCP has the potential to complement classical typing methods such as serotyping and phage typing for the typing of Salmonella serovars due to its rapidity, simplicity, and typeability.
  4. Nair SV, Madhulaxmi, Thomas G, Ankathil R
    J Maxillofac Oral Surg, 2021 Sep;20(3):340-344.
    PMID: 34408360 DOI: 10.1007/s12663-020-01462-4
    Objective: In this article, we provide a gestalt idea about NGS technologies and their applications in cancer research and molecular diagnosis.

    Background: Next-generation sequencing (NGS) advancements like DNA sequencing and RNA sequencing allow uncovering of genomic, transcriptomic, and epigenomic scenes of individual malignant growths. An assortment of genomic abnormalities can be screened at the same time, for example common and uncommon variations, auxiliary variations like insertions and deletions, copy-number variation, and fusion transcripts.

    Conclusion: NGS innovations together with bioinformatics investigation, which extend our insight, are progressively used to analyze multiple genes in a cost-effective way and have been applied in examining clinical cancer samples and offering NGS-based molecular diagnosis.

    Application: NGS is progressively significant as a device for the diagnosis of cancers.

  5. George S, Ajikumaran Nair S, Johnson AJ, Venkataraman R, Baby S
    J Ethnopharmacol, 2015 Jun 20;168:158-63.
    PMID: 25858510 DOI: 10.1016/j.jep.2015.03.060
    Melicope lunu-ankenda leaves are used to treat diabetes in folklore medicinal practices in India and Malaysia. Here we report the isolation of an O-prenylated flavonoid (3,5,4'-trihydroxy-8,3'-dimethoxy-7-(3-methylbut-2-enoxy)flavone; OPF) from the leaves of M. lunu-ankenda and its antidiabetes activity against type-2 diabetes mellitus (T2DM).
  6. Hystad P, Larkin A, Rangarajan S, AlHabib KF, Avezum Á, Calik KBT, et al.
    Lancet Planet Health, 2020 06;4(6):e235-e245.
    PMID: 32559440 DOI: 10.1016/S2542-5196(20)30103-0
    BACKGROUND: Most studies of long-term exposure to outdoor fine particulate matter (PM2·5) and cardiovascular disease are from high-income countries with relatively low PM2·5 concentrations. It is unclear whether risks are similar in low-income and middle-income countries (LMICs) and how outdoor PM2·5 contributes to the global burden of cardiovascular disease. In our analysis of the Prospective Urban and Rural Epidemiology (PURE) study, we aimed to investigate the association between long-term exposure to PM2·5 concentrations and cardiovascular disease in a large cohort of adults from 21 high-income, middle-income, and low-income countries.

    METHODS: In this multinational, prospective cohort study, we studied 157 436 adults aged 35-70 years who were enrolled in the PURE study in countries with ambient PM2·5 estimates, for whom follow-up data were available. Cox proportional hazard frailty models were used to estimate the associations between long-term mean community outdoor PM2·5 concentrations and cardiovascular disease events (fatal and non-fatal), cardiovascular disease mortality, and other non-accidental mortality.

    FINDINGS: Between Jan 1, 2003, and July 14, 2018, 157 436 adults from 747 communities in 21 high-income, middle-income, and low-income countries were enrolled and followed up, of whom 140 020 participants resided in LMICs. During a median follow-up period of 9·3 years (IQR 7·8-10·8; corresponding to 1·4 million person-years), we documented 9996 non-accidental deaths, of which 3219 were attributed to cardiovascular disease. 9152 (5·8%) of 157 436 participants had cardiovascular disease events (fatal and non-fatal incident cardiovascular disease), including 4083 myocardial infarctions and 4139 strokes. Mean 3-year PM2·5 at cohort baseline was 47·5 μg/m3 (range 6-140). In models adjusted for individual, household, and geographical factors, a 10 μg/m3 increase in PM2·5 was associated with increased risk for cardiovascular disease events (hazard ratio 1·05 [95% CI 1·03-1·07]), myocardial infarction (1·03 [1·00-1·05]), stroke (1·07 [1·04-1·10]), and cardiovascular disease mortality (1·03 [1·00-1·05]). Results were similar for LMICs and communities with high PM2·5 concentrations (>35 μg/m3). The population attributable fraction for PM2·5 in the PURE cohort was 13·9% (95% CI 8·8-18·6) for cardiovascular disease events, 8·4% (0·0-15·4) for myocardial infarction, 19·6% (13·0-25·8) for stroke, and 8·3% (0·0-15·2) for cardiovascular disease mortality. We identified no consistent associations between PM2·5 and risk for non-cardiovascular disease deaths.

    INTERPRETATION: Long-term outdoor PM2·5 concentrations were associated with increased risks of cardiovascular disease in adults aged 35-70 years. Air pollution is an important global risk factor for cardiovascular disease and a need exists to reduce air pollution concentrations, especially in LMICs, where air pollution levels are highest.

    FUNDING: Full funding sources are listed at the end of the paper (see Acknowledgments).

  7. Kato Y, Liew BS, Sufianov AA, Rasulic L, Arnautovic KI, Dong VH, et al.
    PMID: 32922948 DOI: 10.1186/s41016-020-00194-1
    Globally, the discipline of neurosurgery has evolved remarkably fast. Despite being one of the latest medical specialties, which appeared only around hundred years ago, it has witnessed innovations in the aspects of diagnostics methods, macro and micro surgical techniques, and treatment modalities. Unfortunately, this development is not evenly distributed between developed and developing countries. The same is the case with neurosurgical education and training, which developed from only traditional apprentice programs in the past to more structured, competence-based programs with various teaching methods being utilized, in recent times. A similar gap can be observed between developed and developing counties when it comes to neurosurgical education. Fortunately, most of the scholars working in this field do understand the coherent relationship between neurosurgical education and neurosurgical practice. In context to this understanding, a symposium was organized during the World Federation of Neurological Surgeons (WFNS) Special World Congress Beijing 2019. This symposium was the brain child of Prof. Yoko Kato-one of the eminent leaders in neurosurgery and an inspiration for female neurosurgeons. Invited speakers from different continents presented the stages of development of neurosurgical education in their respective countries. This paper summarizes the outcome of these presentations, with particular emphasis on and the challenges faced by developing countries in terms of neurosurgical education and strategies to cope with these challenges.
  8. Kato Y, Liew BS, Sufianov AA, Rasulic L, Arnautovic KI, Dong VH, et al.
    PMID: 32925985 DOI: 10.1186/s41016-020-00209-x
    [This corrects the article DOI: 10.1186/s41016-020-00194-1.].
  9. Ross IN, Nair S, Jayakumar CR
    Singapore Med J, 1985 Jun;26(3):271-8.
    PMID: 4048988
    The results of 2449 investigations of the upper gastrointestinal tract were analysed to determine the incidence of disease. Abnormalities were detected in 53% of patients who had endoscopy, but were found in only 24% of patients who had barium studies (p <= 0.001). Altogether 916 patients had abnormal findings. Duodenal ulcer accounted for 42% of cases, gastric ulcer 16% and gastric cancer 9%. The prevalence of perforated ulcer was 13%. The annual incidence/1000 in males and females (>14 years) were respectively, for duodenal ulcer 1.66 and 0.42, for gastric ulcer 0.57 and 0.25, for perforated ulcer 0.36 and 0.05, and for gastric cancer 0.29 and 0.14. Most types of gastro-duodenal disease were less common in Malays than expected (p = <0.001). However oesophageal cancer and varices were more common in Indians compared to Malays and Chinese (p = <0.001). This study showed that the pallern of perforating ulcers was not the same as that of non-peforating ulcers, suggesting a differing pathogenesis. Identification of the factors causing a different prevalence of disease between the three ethnic groups would help in the understanding of the causes of upper gastrointestinal disease.
  10. Naidu R, Yadav M, Nair S, Kutty KK
    Anticancer Res, 1998 Jan-Feb;18(1A):65-70.
    PMID: 9568057
    Expression of p53 protein was investigated by immunohistochemical techniques in archival cases of 134 primary breast carcinomas comprising 13 comedo ductal carcinoma in situ (DCIS), 105 invasive ductal carcinomas, 7 contained the comedo DCIS component adjacent to the invasive ductal component, 5 invasive lobular carcinomas, three colloid carcinomas and one medullary carcinoma. Overexpression of p53 gene product was studied to determine the association with clinico-pathological parameters and also its relationship to c-erbB2. Overexpression of p53 protein was observed in 31% (4/13) of comedo DCIS, 37% (39/105) of invasive ductal carcinomas, 57% (4/7) of carcinomas containing both the in situ and invasive lesions and all medullary carcinomas. A significant relationship (p < 0.05) was observed between strong immunoreactivity of p53 protein and absence of estrogen receptor, histological grade and c-erbB2 but not with lymph node metastases or age of patient. These observations suggest that overexpression of p53 protein may play an important role in tumor progression from noninvasive to invasive in some breast carcinomas and may have potential as an indicator for poorer prognosis.
  11. Naidu R, Yadav M, Nair S, Kutty MK
    Br. J. Cancer, 1998 Nov;78(10):1385-90.
    PMID: 9823984
    Expression of c-erbB3 protein was investigated in 104 primary breast carcinomas comprising nine comedo ductal carcinoma in situ (DCIS), 91 invasive ductal carcinomas and four invasive lobular carcinomas using two monoclonal antibodies, RTJ1 and RTJ2. Of the 91 invasive ductal carcinomas, seven contained the comedo DCIS component adjacent to the invasive component. An immunohistochemical technique was used to evaluate the association between expression of c-erbB3 and clinical parameters and tumour markers such as epidermal growth factor receptor (EGFR), c-erbB2, cathepsin-D and p53 in archival formalin-fixed paraffin-embedded tumour tissues. Our results indicated that RTJ1 and RTJ2 gave identical staining patterns and concordant results. It was found that the overexpression of c-erbB3 protein was observed in 67% (6/9) of comedo DCIS, 52% (44/84) of invasive ductal carcinomas, 71% (5/7) of carcinomas containing both the in situ and invasive lesions and 25% (1/4) of invasive lobular carcinomas. A significant relationship (P < 0.05) was observed between strong immunoreactivity of c-erbB3 protein and histological grade, EGFR and cathepsin-D, but not with expression of c-erbB2, p53, oestrogen receptor status, lymph node metastases or age of patient. However, we noted that a high percentage of oestrogen receptor-negative tumours (59%), lymph node-positive tumours (63%) and c-erbB2 (63%) were strongly positive for c-erbB3 protein. We have also documented that a high percentage of EGFR (67%), c-erbB2 (67%), p53 (75%) and cathepsin-D-positive DCIS (60%) were strongly positive for c-erbB3. These observations suggest that overexpression of c-erbB3 protein could play an important role in tumour progression from non-invasive to invasive and, also, that it may have the potential to be used as a marker for poor prognosis of breast cancer.
  12. Ramli N, Nair SR, Ramli NM, Lim SY
    Clin Radiol, 2015 May;70(5):555-64.
    PMID: 25752581 DOI: 10.1016/j.crad.2015.01.005
    The purpose of this review is to illustrate the differentiating features of multiple-system atrophy from Parkinson's disease at MRI. The various MRI sequences helpful in the differentiation will be discussed, including newer methods, such as diffusion tensor imaging, MR spectroscopy, and nuclear imaging.
  13. Ooi EH, J Y Chia N, Ooi ET, Foo JJ, Liao IY, R Nair S, et al.
    Int J Hyperthermia, 2018 12;34(8):1142-1156.
    PMID: 29490513 DOI: 10.1080/02656736.2018.1437282
    A recent study by Ooi and Ooi (EH Ooi, ET Ooi, Mass transport in biological tissues: Comparisons between single- and dual-porosity models in the context of saline-infused radiofrequency ablation, Applied Mathematical Modelling, 2017, 41, 271-284) has shown that single-porosity (SP) models for describing fluid transport in biological tissues significantly underestimate the fluid penetration depth when compared to dual-porosity (DP) models. This has raised some concerns on whether the SP model, when coupled with models of radiofrequency ablation (RFA) to simulate saline-infused RFA, could lead to an underestimation of the coagulation size. This paper compares the coagulation volumes obtained following saline-infused RFA predicted based on the SP and DP models for fluid transport. Results showed that the SP model predicted coagulation zones that are consistently 0.5 to 0.9 times smaller than that of DP model. This may be explained by the low permeability value of the tissue interstitial space, which causes the majority of the saline to flow through the vasculature. The absence of fluid flow tracking in the vasculature in the SP model meant that any flow of saline into the vasculature is treated as losses and do not contribute to the saline penetration depth of the tissue. Comparisons with experimental results from the literature revealed that the DP models predicted coagulation zone sizes that are closer to the experimental values than the SP models. This supports the hypothesis that the SP model is a poor choice for simulating the outcome of saline-infused RFA.
  14. Nair RS, Nair S
    Curr Drug Deliv, 2015;12(5):517-23.
    PMID: 25675336
    Mortality rate due to heart diseases increases dramatically with age. Captopril is an angiotensin converting enzyme inhibitor (ACE) used effectively for the management of hypertension. Due to short elimination half-life of captopril the oral dose is very high. Captopril is prone to oxidation and it has been reported that the oxidation rate of captopril in skin tissues is considerably low when compared to intestinal tissues. All these factors make captopril an ideal drug candidate for transdermal delivery. In this research work an effort was made to formulate transdermal films of captopril by utilizing polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) as film formers and polyethylene glycol 400 (PEG400) as a plasticizer. Dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) were used as permeation enhancers. Physicochemical parameters of the films such as appearance, thickness, weight variation and drug content were evaluated. The invitro permeation studies were carried out through excised human cadaver skin using Franz diffusion cells. The in-vitro permeation studies demonstrated that the film (P4) having the polymer ratio (PVP:PVA = 80:20) with DMSO (10%) resulted a promising drug release of 79.58% at 24 hours with a flux of 70.0 µg/cm(2)/hr. No signs of erythema or oedema were observed on the rabbit skin as a result of skin irritation study by Draize test. Based on the stability report it was confirmed that the films were physically and chemically stable, hence the prepared films are very well suited for transdermal application.
  15. Karanth L, Barua A, Kanagasabai S, Nair S
    PMID: 26350784 DOI: 10.1002/14651858.CD009824.pub3
    BACKGROUND: Congenital bleeding disorders can cause obstetric haemorrhage during pregnancy, labour and following delivery. Desmopressin acetate is found to be an effective drug which can reduce the risk of haemorrhage and can also stop bleeding in certain congenital bleeding disorders. Its use in pregnancy has been controversial. Hence beneficial and adverse effects of desmopressin acetate in these groups of pregnant women should be evaluated.This is an update of a Cochrane review first published in 2013.

    OBJECTIVES: To determine the efficacy of desmopressin acetate in preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders.

    SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant and abstract books of conferences proceedings. We also searched for any randomised controlled trials in a registry of ongoing trials and the reference lists of relevant articles and reviews.Date of most recent search: 18 June 2015.

    SELECTION CRITERIA: Randomised and quasi-randomised controlled trials investigating the efficacy of desmopressin acetate versus tranexamic acid or factor VIII or rFactor VII or fresh frozen plasma in preventing and treating congenital bleeding disorders during pregnancy were eligible.

    DATA COLLECTION AND ANALYSIS: No trials matching the selection criteria were eligible for inclusion.

    MAIN RESULTS: No trials matching the selection criteria were eligible for inclusion.

    AUTHORS' CONCLUSIONS: The review did not identify any randomised controlled trials investigating the relative effectiveness of desmopressin acetate for bleeding during pregnancy in women with congenital bleeding disorders. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials) to decide whether or not to treat women with congenital bleeding disorders with desmopressin acetate.Given the ethical considerations, future randomised controlled trials are unlikely. However, other high quality controlled studies (such as risk allocation designs, sequential design, parallel cohort design) to investigate the risks and benefits of using desmopressin acetate in this population are needed.

  16. Khoo SP, Shanmuhasuntharam P, Mahadzir WM, Tay KK, Latif A, Nair S
    Asia Pac J Public Health, 1998;10(1):49-51.
    PMID: 10050209 DOI: 10.1177/101053959801000111
    The delay in the diagnosis of oral cancer has been variously reported as being contributed by the clinicians, patients or both. The purpose of this study was to evaluate the referral pattern of 65 patients eventually diagnosed as having oral squamous cell carcinoma. The results showed that 50% of the patients delayed seeking professional help for more than 3 months after being aware of the lesion. The majority of the patients consulted medical practitioners as the first source of help. The mean clinicians' and patients' delay were 10.3 weeks and 28.9 weeks respectively. Dental practitioners showed a tendency to refer more advanced lesions compared to the medical practitioners. The findings raise the concern that lack of patients' awareness, misdiagnosis by clinicians and late detection by dental practitioners prevail thus calling for urgent measures towards early detection of the disease.
  17. Naidu R, Wahab NA, Yadav M, Kutty MK, Nair S
    Int J Mol Med, 2001 Aug;8(2):193-8.
    PMID: 11445874
    Amplification of int-2/FGF-3 gene was investigated by differential polymerase chain reaction (dPCR) in 440 archival primary breast carcinoma tissues. Of these, 23 were comedo ductal carcinoma in situ (DCIS), 18 were non-comedo DCIS, 41 were comedo DCIS with adjacent invasive ductal carcinomas, 19 were non-comedo DCIS with adjacent invasive ductal carcinomas, 270 were invasive ductal carcinomas, 33 were invasive lobular carcinomas, 21 were colloid carcinomas and 15 were medullary carcinomas. Int-2 was amplified in 22% (96/440) of the primary breast carcinomas. It was shown that int-2 was amplified in 13% (3/23) of the comedo DCIS, 17% (7/41) of the comedo DCIS and 29% (12/41) of the adjacent invasive ductal carcinomas, 26% (71/270) of the invasive ductal carcinomas, 18% (6/33) of the invasive lobular carcinomas, 10% (2/21) of the colloid carcinomas and 13% (2/15) of the medullary carcinomas. In contrast, int-2 was not amplified in non-comedo DCIS and invasive ductal carcinomas with adjacent non-comedo DCIS lesions. A significant association was observed between int-2 amplification in the in situ components and adjacent invasive lesion (P<0.05). All tumors with int-2 amplification in the in situ lesions (7/7) also demonstrated same degree of amplification in the adjacent invasive components. However, 9% (5/53) of the tumors with no amplified int-2 gene in the in situ components showed int-2 amplification in the adjacent invasive lesions. A significant relationship was noted between amplification of int-2 and lymph node metastases (P<0.05) and poorly differentiated tumors (P<0.05) but not with estrogen receptor status (P>0.05) and proliferation index (Ki-67 and PCNA) (P>0.05). In Malaysia, majority of the patients belong to younger age group (<50 years old) but a comparison of the age groups showed that the amplification of int-2 was not statistically associated with patient age (P>0.05). These observations indicate that amplification of int-2 tends to strengthen the view that int-2 may have the potential to be an indicator of poor prognosis regardless of the age of the patient. Moreover, the presence of int-2 amplification in preinvasive, preinvasive and adjacent invasive lesions, and invasive carcinomas suggest that int-2 could be a marker of genetic instability occurring in early and late stages of tumor development.
  18. Nair S
    Cureus, 2021 Oct;13(10):e18846.
    PMID: 34804700 DOI: 10.7759/cureus.18846
    COVID-19 infection is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was declared a pandemic in 2020. Dengue fever (DF) is caused by the dengue virus (DENV) from the Flaviviridae family and is transmitted via the bite of the female Aedes aegypti mosquito. COVID-19 pneumonia and dengue fever coinfection is a relatively difficult diagnosis to be established considering the similarities in the clinical manifestation of both diseases. I hereby report an unusual case of dual diagnosis involving COVID-19 pneumonia and dengue fever (DF) on the same day of presentation to the hospital. A 62-year-old male presented to the emergency department with a fever of six days duration associated with chills, rigors, arthralgia, myalgia, and a generalized pinpoint rash over the chest and abdomen. He had contact with a worker who recently tested positive for COVID-19. However, his vital signs were stable with peripheral capillary oxygen saturation (SPO2) of 99% under room air. Laboratory investigations showed polycythemia, increased hematocrit levels, and thrombocytopenia. Liver function tests showed evidence of acute hepatitis. Otherwise, the basic metabolic panel and coagulation profile were normal. Viral screens for hepatitis B, hepatitis C, and human immunodeficiency virus (HIV) were negative. The posterior-anterior chest radiograph of the patient showed ground glass opacity in both middle and lower zones of the lungs, which is mostly peripheral with preservation of lung markings. The diagnosis was confirmed by a positive SARS-CoV-2 polymerase chain reaction (PCR) test with a cycle threshold (CT) value of 19.97 and positive immunoglobulin M (IgM) and immunoglobulin G (IgG) titers on the dengue serology panel on the same day of testing. Predisposing risk factors were chronic medical illnesses (type 2 diabetes mellitus, hypertension, and ischemic heart disease) and exposure to probable COVID-19-infected individuals. The patient fully recovered after treatment with oral paracetamol 1 g four times a day for five days and an intravenous drip of 0.9% sodium chloride for 24 hours.
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