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Biomedical subjects

V Ng

Publications and source records attributed to V Ng.

At least 19 recordsLinked to original sources
PubMed2006

Rapid onset of ulcerative typhlocolitis in B6.129P2-IL10tm1Cgn (IL-10-/-) mice infected with Helicobacter trogontum is associated with decreased colonization by altered Schaedler's flora.

Infection with Helicobacter trogontum, a urease-positive helicobacter isolated from subclinically infected rats, was evaluated in B6.129P2-IL10(tm1Cgn) (interleukin-10(-/-) [IL-10(-/-)]) and C57BL/6 (B6) mice. In a first experiment, IL-10(-/-) mice naturally infected with Helicobacter rodentium had subclinical typhlocolitis but developed severe diarrhea and loss of body condition with erosive to ulcerative typhlocolitis within 1 to 3 weeks of experimental infection with H. trogontum. A second experiment demonstrated that helicobacter-free IL-10(-/-) mice dosed with H. trogontum also developed severe clinical signs and typhlocolitis within 2 to 4 weeks, whereas B6 mice colonized with H. trogontum were resistant to disease. In a third experiment, using helicobacter-free IL-10(-/-) mice, dosing with H. trogontum resulted in acute morbidity and typhlocolitis within 8 days. Acute typhlocolitis was accompanied by signs of sepsis supported by degenerative hemograms and recovery of Escherichia coli and Proteus spp. from the livers of infected mice. Quantitative PCR data revealed that H. rodentium and H. trogontum may compete for colonization of the lower bowel, as H. trogontum established higher colonization levels in the absence of H. rodentium (P < 0.003). H. trogontum-induced typhlocolitis was also associated with a significant decrease in the levels of colonization by five of eight anaerobes that comprise altered Schaedler's flora (P < 0.002). These results demonstrate for the first time that H. rodentium infection in IL-10(-/-) mice causes subclinical typhlocolitis and that infection with H. trogontum (with or without H. rodentium) induces a rapid-onset, erosive to ulcerative typhlocolitis which impacts the normal anaerobic flora of the colon and increases the risk of sepsis.

Animals↗
PubMed2006

Comparison of forced-air warming and electric heating pad for maintenance of body temperature during total knee replacement.

We conducted a randomised controlled trial to compare the efficacy of forced-air warming (Bair Hugger(trade mark), Augustine Medical model 500/OR, Prairie, MN) with that of an electric heating pad (Operatherm 202, KanMed, Sweden) for maintenance of intra-operative body temperature in 60 patients undergoing total knee replacement under combined spinal-epidural anaesthesia. Intra-operative tympanic and rectal temperatures and verbal analogue score for thermal comfort were recorded. There were no differences in any measurements between the two groups, with mean (SD) final rectal temperatures of 36.8 (0.4) degrees C with forced-air warming and 36.9 (0.4) degrees C with the electric pad. The heating pad is as effective as forced-air warming for maintenance of intra-operative body temperature.

Aged↗
PubMed2005

A study of natural rubber latex allergens in gloves used by healthcare workers in Singapore.

BACKGROUND: Allergy to natural rubber latex (NRL) proteins is a well-recognized health problem among subjects using protective gloves and products made of NRL. There is currently no information on NRL allergen levels in gloves used in Singapore. OBJECTIVES: This study aims to quantify the amount of specific allergens (Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02) found in rubber gloves used in Singapore. It also aims to determine if these levels are above thresholds that may cause NRL allergy. It also compares the levels of these specific allergens in gloves used for different purposes, namely gloves used for examination purposes or for surgical procedures. METHODS: Forty-nine rubber gloves were obtained from major hospitals and healthcare departments in Singapore and were analysed for their NRL allergen levels. FITkit, based on the enzyme immunometric assay technique, was used to determine the specific allergen levels of Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02 in the gloves. RESULTS: Examination gloves had higher NRL allergen content compared with surgical gloves, and powdered gloves had higher allergen content compared with nonpowdered gloves. Among the various allergens, Hev b 5 and Hev b 6.02 were present in larger quantities than Hev b 1 and Hev b 3. Only two of 19 (11%) surgical gloves had the sum of the four allergens (Hev b 1, Hev b 3, Hev b 5, Hev b 6.02) in excess of 1 microg g(-1), which is believed to be a clinically relevant threshold. Among the examination gloves, 25 of 30 (83%) exceeded this level. CONCLUSIONS: This study shows that NRL allergen levels are present in the majority of examination gloves used by healthcare workers in Singapore at levels high enough to cause NRL allergy among sensitized persons. The information can serve as evidence for a possible requirement for manufacturers to produce gloves with low NRL allergen levels and to state the allergen level in gloves in the product information.

Allergens↗
PubMed2005

Appropriate use of personal protective equipment among healthcare workers in public sector hospitals and primary healthcare polyclinics during the SARS outbreak in Singapore.

BACKGROUND: Singapore was affected by an outbreak of severe acute respiratory syndrome (SARS) from 25 February to 31 May 2003, with 238 probable cases and 33 deaths. AIMS: To study usage of personal protective equipment (PPE) among three groups of healthcare workers (HCWs: doctors, nurses, and administrative staff), to determine if the appropriate PPE were used by the different groups and to examine the factors that may determine inappropriate use. METHODS: A self-administered questionnaire survey of 14,554 HCWs in nine healthcare settings, which included tertiary care hospitals, community hospitals, and polyclinics, was carried out in May-July 2003. Only doctors, nurses, and clerical staff were selected for subsequent analysis. RESULTS: A total of 10 236 valid questionnaires were returned (70.3% response); 873 doctors, 4404 nurses, and 921 clerical staff were studied. A total of 32.5% of doctors, 48.7% of nurses, and 77.1% of the administrative staff agreed that paper and/or surgical masks were "useful in protecting from contracting SARS". Among this group, 23.6% of doctors and 42.3% of nurses reported working with SARS patients. The view that a paper and/or surgical mask was adequate protection against SARS was held by 33.3% of doctors and 55.9% of nurses working at the A&E unit, 30.5% of doctors and 49.4% of nurses from medical wards, and 27.5% of doctors and 37.1% of nurses from intensive care units. Factors which predicted for agreement that paper and/or surgical masks were protective against SARS, included HCW's job title, reported contact with SARS patients, area of work, and Impact Events Scale scores. CONCLUSION: A variety of factors determine appropriate use of personal protective equipment by HCWs in the face of a major SARS outbreak.

Administrative Personnel↗
PubMed2005

Latex sensitisation in healthcare workers in Singapore.

INTRODUCTION: Epidemiological data on latex sensitisation among Asian healthcare workers is lacking. The aim of the study is to determine the rate of latex sensitisation in our healthcare workers. MATERIALS AND METHODS: We recruited 313 healthcare workers, of which 46.6% were operating theatre staff and 53.4% were non-operating theatre staff. Seventy-one administrative staff served as controls. All participants answered a self-administered questionnaire relating to latex exposure and glove-related symptoms. Latex sensitisation was determined by skin prick testing to latex and latex-specific IgE detection. RESULTS: The prevalence of latex sensitisation among healthcare workers was 9.6%, with no difference between operating theatre and nonoperating theatre staff. Glove-related symptoms were reported in 13.7% of all healthcare workers, of which 22.9% were sensitised to latex. Only 26.7% of latex-sensitised healthcare workers had glove-related symptoms while the rest were asymptomatic. The most common symptoms were itch and hand eczema but the most important discriminating symptom was contact urticaria. Personal history of atopy was more common in sensitised healthcare workers (40.0%) compared to non-sensitised workers (31.8%). Only 1 out of 9 (11.2%) symptomatic latex-sensitised subjects had sought previous medical attention for the problem. CONCLUSIONS: Latex sensitisation among healthcare workers in Singapore should be considered a significant occupational health risk, as it is in the West. Increased screening and awareness of this problem is essential to identify those at risk.

Adult↗
PubMed2004

A study of hippocampal shape anomaly in schizophrenia and in families multiply affected by schizophrenia or bipolar disorder.

Hippocampal shape anomaly (HSA), characterised by a rounded hippocampus, has been documented in congenital malformations and epileptic patients. Subtle structural hippocampal abnormalities have been demonstrated in patients with schizophrenia. We tested the hypothesis that HSA is more frequent in schizophrenia, particularly in patients from families multiply affected by schizophrenia, and that HSA is transmitted within these families. We also aimed to define the anatomical features of the hippocampus and other cerebral structures in the HSA spectrum and to determine the prevalence of HSA in a control group. We reviewed the magnetic resonance imaging of a large number of subjects with schizophrenia and bipolar disorder, many of who came from multiply affected families, relatives of the affected probands, and controls. Quantitative measures of hippocampal shape and position and other qualitative anatomical measures were performed (including depth of dominant sulcus cortical cap, angle of dominant sulcus and hippocampal fissure, bulk of collateral white matter, prominence of temporal horn lateral recess and blurring of internal hippocampal architecture) on subjects with HSA. A spectrum of mild, moderate and severe HSA was defined. The prevalence of HSA was, 7.8% for the controls (n=218), 9.3% for all schizophrenic subjects (n=151) and 12.3% for familial schizophrenic subjects (n=57). There was a greater prevalence of moderate or severe forms of HSA in familial schizophrenics than controls. However, there was no increase in the prevalence of HSA in the unaffected first-degree relatives of schizophrenic patients or in patients with familial bipolar disorder. HSA was rarely transmitted in families. HSA was frequently associated with a deep, vertical collateral/occipito-temporal sulcus and a steep hippocampal fissure. Our data raise the possibility that HSA is linked to disturbances of certain neurodevelopmental genes associated with schizophrenia. However, the lack of any increase in prevalence in the unaffected relatives of patients and the lack of clustering within individual pedigrees argues against this developmental anomaly being commonly associated with genetic predisposition to the illness.

Adult↗
PubMed2004

Biological monitoring of kidney function among workers occupationally exposed to trichloroethylene.

AIMS: To investigate the nephrotoxic potential of trichloroethylene in a currently exposed population using sensitive urinary markers of kidney toxicity. METHODS: Renal dysfunction was monitored in a cross-sectional study of 70 workers currently exposed to trichloroethylene. An age and sex matched control population of 54 individuals was drawn from hospital and administrative staff. RESULTS: The mean exposure to trichloroethylene, estimated from urinary trichloroacetic acid concentrations, was 32 ppm (range 0.5-252 ppm) with an average duration of exposure of 4.1 years (range 1-20 years). Significant differences between the exposed and control populations were found for nephrotoxicity markers N-acetylglucosaminidase (NAG) and albumin, and for the mode of action marker, formic acid. However, neither NAG nor albumin showed a significant correlation with either the magnitude or duration of exposure to trichloroethylene. There was a significant correlation between urinary formic acid and trichloroacetic acid concentrations. Within the exposed population there were dose dependent increases in urinary methylmalonic acid concentrations and urinary glutathione S-transferase alpha activity. Although still within the control range, these changes were clearly dose dependent and consistent with one of the proposed mechanisms of trichloroethylene induced kidney toxicity. CONCLUSION: Although there was no evidence of kidney toxicity within the population studied, the results suggest that kidney damage could occur at exposure concentrations higher (>250 ppm) than those encountered in this study.

Adult↗
PubMed2004

Salivary immunoglobulin A and lysozyme in patients with psoriasis.

INTRODUCTION: We compared the salivary immunoglobulin A (IgA) and lysozyme concentration and secretion rates among mild and severe psoriasis patients and controls in Singapore. MATERIALS AND METHODS: Fifty-one psoriasis patients and 24 controls participated in the study. None of the patients were on immunosuppressive therapy. The Psoriasis Area and Severity Index (PASI) was used to assess the severity of psoriasis. Patients were divided into mild and severe groups by the median PASI score. Each subject contributed a 5-minute unstimulated salivary sample. Enzyme-linked immunosorbent assay method was used to determine the salivary IgA and lysozyme levels. RESULTS: Psoriasis patients had lower concentration and secretion rate of IgA (geometric mean [GM], 97.5 micro g/mL and 32.3 micro g/min) and lysozyme (GM, 127.6 micro g/mL and 42.1 micro g/min) than controls (IgA GM 256.3 micro g/mL, 79.1 micro g/min; lysozyme GM 180.9 micro g/mL, 55.8 micro g/min) [P = 0.000 (IgA concentration), P = 0.000 (IgA secretion rate), P = 0.015 (lysozyme concentration) and P = 0.150 (lysozyme secretion rate)]. However, no significant differences were observed between mild and severe patients for both IgA and lysozyme concentrations and secretion rates. PASI score showed negative, but non-significant, correlations with either log salivary IgA (r = -0.22, P = 0.13) or log lysozyme (r = -0.09, P = 0.53) secretion rates. CONCLUSION: Psoriasis patients had lower concentrations and secretion rates of salivary IgA and lysozyme compared to controls. However, among patients, the salivary IgA and lysozyme levels are variable and not related to severity of psoriasis.

Adult↗
PubMed2004

Neurocysticercosis: a rare cause of seizure.

Neurocysticercosis is endemic in certain parts of the world, is rare in Europe and has never previously been described in the Irish healthcare setting. We report the case of a healthy male, originally from Guatemala, who presented to our hospital with a generalized tonic-clonic seizure presumed secondary to neurocysticercosis.

Adult↗
PubMed2003

Dopaminergic drug effects on physiological connectivity in a human cortico-striato-thalamic system.

Cortico-striato-thalamic (CST) systems are anatomical substrates for many motor and executive functions and are implicated in diverse neuropsychiatric disorders. Electrophysiological studies in rats, monkeys and patients with Parkinson's disease have shown that power and coherence of low frequency oscillations in CST systems can be profoundly modulated by dopaminergic drugs. We combined functional MRI with correlational and path analyses to investigate functional and effective connectivity, respectively, of a prefronto-striato-thalamic system activated by object location learning in healthy elderly human subjects (n = 23; mean age = 72 years). Participants were scanned in a repeated measures, randomized, placebo-controlled design to measure modulation of physiological connectivity between CST regions following treatment with drugs which served both to decrease (sulpiride) and increase (methylphenidate) dopaminergic transmission, as well as non-dopaminergic treatments (diazepam and scopolamine) to examine non-specific effects. Functional connectivity of caudate nucleus was modulated specifically by dopaminergic drugs, with opposing effects of sulpiride and methylphenidate. The more salient effect of sulpiride was to increase functional connectivity between caudate and both thalamus and ventral midbrain. A path diagram based on prior knowledge of unidirectional anatomical projections between CST components was fitted satisfactorily to the observed inter-regional covariance matrix. The effect of sulpiride was defined more specifically in the context of this model as increased strength of effective connection from ventral midbrain to caudate nucleus. In short, we have demonstrated enhanced functional and effective connectivity of human caudate nucleus following sulpiride treatment, which is compatible both with the anatomy of ascending dopaminergic projections and with electrophysiological studies indicating abnormal coherent oscillations of CST neurons in parkinsonian states.

Aged↗
PubMed2003

Cognitive modulation of the cerebral processing of human oesophageal sensation using functional magnetic resonance imaging.

BACKGROUND: While cortical processing of visceral sensation has been described, the role that cognitive factors play in modulating this processing remains unclear. AIM: To investigate how selective and divided attention modulate the cerebral processing of oesophageal sensation. METHODS: In seven healthy volunteers (six males, mean age 33 years; ranging from 24 to 41 years old) from the general community, phasic visual and oesophageal (non-painful balloon distension) stimuli were presented simultaneously. During the selective attention task, subjects were instructed to press a button either to a change in frequency of oesophageal or visual stimuli. During a divided attention task, subjects received simultaneous visual and oesophageal stimuli and were instructed to press a button in response to a change in frequency of both stimuli. RESULTS: Selectively focussing attention on oesophageal stimuli activated the visceral sensory and cognitive neural networks (primary and secondary sensory cortices and anterior cingulate cortex respectively) while selective attention to visual stimuli primarily activated the visual cortex. When attention was divided between the two sensory modalities, more brain regions in the sensory and cognitive domains were utilised to process oesophageal stimuli in comparison to those employed to process visual stimuli (p=0.003). CONCLUSION: Selective and divided attention to visceral stimuli recruits more neural resources in both the sensory and cognitive domains than attention to visual stimuli. We provide neurobiological evidence that demonstrates the biological importance placed on visceral sensations and demonstrate the influence of cognitive factors such as attention on the cerebral processing of visceral sensation.

Adult↗
PubMed2003

Can salivary lead be used for biological monitoring of lead exposed individuals?

BACKGROUND: Measurement of blood lead (BPb) is the usual method for biomonitoring of persons exposed to inorganic lead. AIM: To explore the use of salivary lead (SPb) as an alternative. METHODS: BPb and SPb levels were measured in a group of 82 lead exposed adults. RESULTS: The mean BPb of the workers was 26.6 microg/dl (SD 8.6, range 10-48) and the mean SPb level 0.77 microg/dl, or 3% of the BPb level. As the SPb distribution was skewed, logarithmic transformation was performed to normalise the distribution. A bivariate scattergram of BPb and logSPb (r = 0.41, p = 0.00) had a line of best fit expressed as BPb = 29.7 + 8.95logSPb. The relation of logSPb and BPb was stronger among non-smokers (r = 0.42) compared to smokers (r = 0.3); and among those without a medical condition (r = 0.44). Multiple linear regression analysis (fitting smoking and medical condition into the model) yielded an R of 0.54, and an adjusted R(2) of 0.26. CONCLUSION: The study findings do not support the use of SPb for biomonitoring at BPb levels ranging from 10 to 50 microg/dl.

Adult↗
PubMed2002

Self perceived work related stress and the relation with salivary IgA and lysozyme among emergency department nurses.

AIMS: To assess and compare the self perceived work related stress among emergency department (ED) and general ward (GW) nurses, and to investigate its relation with salivary IgA and lysozyme. METHODS: One hundred and thirty two of 208 (63.5%) registered female ED and GW nurses participated in the study. A modified mental health professional stress scale (PSS) was used to measure self perceived stress. ELISA methods were used to determine the salivary IgA and lysozyme levels. RESULTS: On PSS, ED nurses had higher scores (mean 1.51) than GW nurses (1.30). The scores of PSS subscales such as organisational structure and processes (OS), lack of resources (RES), and conflict with other professionals (COF) were higher in ED than in GW nurses. ED nurses had lower secretion rates of IgA (geometric mean (GM) 49.1 micro g/min) and lysozyme (GM 20.0 micro g/min) than GW nurses (68.2 micro g/min, 30.5 micro g/min). Significant correlations were observed between PSS and log IgA and lysozyme secretion rates. OS, RES, and COF were correlated with log IgA and lysozyme levels. CONCLUSION: ED nurses, who reported a higher level of professional stress, showed significantly lower secretion rates of salivary IgA and lysozyme compared to GW nurses. Salivary IgA and lysozyme were inversely correlated with self perceived work related stress. As these salivary biomarkers are reflective of the mucosal immunity, results support the inverse relation between stress and mucosal immunity.

Adult↗
PubMed2001

Salivary cortisol levels and work-related stress among emergency department nurses.

The objective of this study was to assess and compare the self-perceived work-related stress of emergency department (ED) and general ward (GW) nurses and to assess the relationship between self-perceived stress and salivary cortisol levels in these groups of nurses. Seventy-three female ED (n = 23) and GW (n = 50) nurses from a general hospital completed a self-administered questionnaire. A modified mental health professional stress scale (PSS) was used to measure self-perceived work-related stress. Salivary samples were collected at the start and end of morning shiftwork. An enzyme-linked immunosorbent assay method was used to determine the salivary cortisol concentration (nmol/L). ED nurses perceived that nursing was more stressful (mean, 1.58; 95% confidence interval [CI], 1.35 to 1.81) than did GW nurses (mean, 1.30; 95% CI, 1.18 to 1.40). On the PSS subscales, scores of organizational structure and process, lack of resources, and conflict with other professionals were higher in ED nurses (all P < 0.01). The morning cortisol was significantly lower in ED (geometric mean, 9.10; 95% CI, 6.62 to 12.42 nmol/L) than in GW (geometric mean, 15.45; 95% CI, 11.86 to 20.14 nmol/L) nurses. Log morning salivary cortisol was negatively correlated with PSS (r = -0.255), scores of organizational structure and process, and conflict with other professionals (all P < 0.05). The difference between morning and afternoon cortisol concentration in ED nurses (geometric mean, 6.35; 95% CI 4.14 to 9.93 nmol/L) was lower than in GW nurses (geometric mean, 12.42; 95% CI, 9.38 to 16.28 nmol/L). The log value of the difference correlated marginally with PSS (r = -0.21, P = 0.07) and significantly with scores of organizational structure and process, lack of resources, and conflict with other professionals (all P < 0.05). There was no difference between the two groups in afternoon salivary cortisol level. ED nurses perceived more stress compared with GW nurses. Morning salivary cortisol concentration is better correlated with PSS compared with the morning-afternoon salivary cortisol difference. The result raises the possibility of using a single morning salivary cortisol sample to reflect self-perceived stress.

Adult↗
PubMed2001

Structural brain abnormalities associated with deletion at chromosome 22q11: quantitative neuroimaging study of adults with velo-cardio-facial syndrome.

BACKGROUND: Velo-cardio-facial syndrome (VCFS) is associated with deletions in the qll band of chromosome 22, learning disability and psychosis, but the neurobiological basis is poorly understood. AIMS: To investigate brain anatomy in adults with VCFS. METHOD: Magnetic resonance imaging was used to study 10 patients with VCFS and 13 matched controls. We carried out three analyses: qualitative; traced regional brain volume; and measurement of grey and white matter volume. RESULTS: The subjects with VCFS had: a high prevalence of white matter hyperintensities and abnormalities of the septum pellucidum; a significantly smaller volume of cerebellum; and widespread differences in white matter bilaterally and regional specific differences in grey matter in the left cerebellum, insula, and frontal and right temporal lobes. CONCLUSIONS: Deletion at chromosome 22q11 is associated with brain abnormalities that are most likely neurodevelopmental and may partially explain the high prevalence of learning disability and psychiatric disorder in VCFS.

Adult↗
PubMed2001

[Comparison of seminal vitamin B12, folate, reactive oxygen species and various sperm parameters between fertile and infertile males].

Vitamin B12(VB12), folate and reactive oxygen species(ROS) in human semen from both fertile and infertile males, and their relationships with other parameters were observed. Semen samples from 44 infertile and 176 fentile control subjects were collected and measured based on the guidelines issued by WHO. The results showed that no significant differences on semen VB12 and folate were observed between fertile and infertile groups(P > 0.05). However, the levels of ROS in infertile group were significantly higher than those in fertile group(P < 0.01). The morphological defects and low motility of sperm in infertile group was significantly higher than those in fertile group(P < 0.01). A positive relation was observed between the levels of ROS production and the morphological defect of sperm(P < 0.01). There was a significant negative correlation between the levels of VB12, folate and ROS(P < 0.01) in semen. It is interesting to note that the values of ROS also show a significantly positive correlation with sperm motility (P < 0.01). A significant differences of ROS levels between fertile and infertile group with negative white blood cells in sperm was also observed. It is concluded that the increase of ROS on the morphological defect of sperm is one of the most important factors related to poor sperm quality and human infertility.

Adult↗