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Biomedical subjects

C W Lim

Publications and source records attributed to C W Lim.

At least 19 recordsLinked to original sources
PubMed2005

An intelligent tutoring system for trauma management (Trauma-Teach): a preliminary report.

Trauma-Teach is an interactive software for tutoring surgical trainees on medical trauma management procedures. Users of the system interact with a virtual patient suffering from trauma injuries. The task of the user is to stabilise the virtual patient, discover the underlying injuries and decide on an appropriate management plan. Artificial intelligence techniques are used to simulate the patient's pulmonary and cardiovascular systems in real time, determine the responses and results of treatments and diagnostics accordingly, model the patient deterioration if wrong actions are taken, and give a measure of reality to the system by selecting actual trauma cases from the hospital's database.

Artificial Intelligence↗
PubMed2003

Self-organized superlattice formation during crystal growth from continuous beam fluxes.

Alloy superlattice structures consisting of alternating Si-rich and C-rich layers form spontaneously during gas-source molecular beam epitaxy of Si(1-y)C(y) on Si(001) from constant Si2H6 and CH3SiH3 precursor fluxes at T(s)=725-750 degrees C. The self-organized patterning is due to a complex interaction among competing surface reactions. During growth of the initial Si-rich layer, strain-driven C segregation to the subsurface results in charge transfer from surface Si atom dangling bonds to C backbonds. This decreases the Si2H6 sticking probability, and, hence, the instantaneous deposition rate, thereby enhancing C segregation. The Si-rich layer continues until a critical C coverage is reached allowing nucleation of a C-rich layer which grows until the excess subsurface C is depleted. The process then repeats with periods tunable through the choice of T(s) and y(avg).

Journal Article↗
PubMed2003

Characterization of the protective response against a homologous challenge infection with Strongyloides venezuelensis in rats.

The protective response in rats against a homologous challenge infection with Strongyloides venezuelensis was characterized. In an initial infection with 1000 filariform larvae and migrating larvae (L(3)) of S. venezuelensis, the population of L(3) in the lungs on day 3 postinfection (PI), and that of adult worms in the small intestine on day 7 PI, were 180.8+/-14.5 and 336.8+/-70.7, respectively. The latter were gradually expelled towards day 42 PI. After the initial infection, the rats developed strong immunity against a homologous challenge infection as manifested by a marked reduction in worm populations, stunted body length and width, damage to reproductive organs, impaired egg production and rapid expulsion of the worms by day 14 after challenge. Expulsion of the worms was preceded by a significantly elevated (P<0.05) peripheral blood eosinophil (PBE) count, both in the initial (200.0+/-26.5 x 10(3)ml) and the challenge infection (400.9+/-165.4 x 10(3)ml). These findings suggest that rats acquire strong homologous immunity following initial exposure to S. venezuelensis. It is suggested that PBEs are involved in worm expulsion. A major target of these effector mechanisms is the reproductive system of S. venezuelensis.

Animals↗
PubMed2003

Brucella abortus infection in indigenous Korean dogs.

Three dogs reared on a dairy farm with a high incidence for Brucella abortus were serologically positive for B. abortus and no other Brucella spp. The identity of the organism was confirmed to be B. abortus by AMOS (abortus melitensis ovis suis)-polymerase chain reaction with specific primers for B. canis. One hundred percent homology of the canine isolate and the bovine pathogen isolated from the farm was demonstrated. The only possible source of infection was infected cattle on the same farm. It is suggested that dogs be routinely included in brucellosis surveillance and eradication programs.

Animals↗
PubMed2000

The prevalence and pattern of contact lens use in a Singapore community.

PURPOSE: We conducted a cross-sectional survey to determine the prevalence, socio-demographic patterns, and characteristics of contact lens use in an electoral community in Singapore. METHODS: One thousand eight hundred fifteen persons aged between 12-55 years from 768 households were surveyed using a standardized pre-tested questionnaire. RESULTS: The percentage of contact lens wearers in the survey populations was 9.0%. Forty-two percent of surveyed individuals were myopes, 21.8% of whom wore contact lenses. Contact lens wearers tended to be young Chinese females with higher level education and incomes. Most wore monthly disposable or daily wear soft contact lenses. Convenience and cosmesis were the main reasons cited for contact lens wear. Optometrists, who prescribed the bulk of contact lenses, were also the most influential in determining consumers' choice of lenses. CONCLUSION: Information gathered in this population-based survey may be used to facilitate national eye-care planning and provide a baseline for comparison with rates of lens wear found in other countries and in future surveys.

Adolescent↗
PubMed1999

Theoretical analysis of the effect of cutaneous metabolism on skin permeation of parabens based on a two-layer skin diffusion/metabolism model.

The effect of cutaneous metabolism on the skin penetration of drugs was analyzed based on a two-layer skin diffusion/metabolism model. In vitro permeation studies of propylparaben and butylparaben with or without an esterase inhibitor, diisopropyl fluorophosphate (DFP), were performed. Pretreatment of the skin with DFP prolonged the lag time for the penetration of intact parabens. Additionally, DFP significantly decreased the total flux of butylparaben, but not that of propylparaben. Model analysis of the penetration profiles revealed that DFP inhibits the cutaneous metabolism without affecting any other processes. To comprehensively understand the relationships among lipophilicity, metabolic rate, and skin permeation of drugs, simulation studies were performed with newly derived equations concerning the permeability coefficient and the lag time for the penetration of both intact and metabolite forms. The analysis revealed that the lag time for the penetration of both intact and metabolite forms becomes shorter with increasing metabolic rate. As the metabolic rate of the drug increases, skin penetration of the intact form decreases whereas that of the metabolite increases. The total flux of intact and metabolite forms increases with increasing metabolic rate, being more obvious for highly lipophilic drugs. This indicates that the permeation of lipophilic compounds such as butylparaben is more highly affected by cutaneous metabolism in the viable layer because these compounds easily penetrate the stratum corneum layer. Consequently, the balance between the permeability of drug across the stratum corneum and the dermis has been implicated to impose a significant influence on the percutaneous absorption of drugs subjected to cutaneous metabolism.

Animals↗
PubMed1996

Intravenous fumonisin B1 induces cell proliferation and apoptosis in the rat.

In the rat, the target organs of fumonisin B1, a mycotoxin produced by Fusarium moniliforme, are the kidney and liver. Fumonisin B1 is also hepatocarcinogenic in the rat and is associated epidemiologically with esophageal cancer in humans. We investigated the effect of a single intravenous dose of fumonisin B1 on cell proliferation, lesion development, and glutathione status in the major target organs of the rat. Male Sprague-Dawley rats were injected intravenously with fumonisin B1 at 0 or 1.25 mg/kg and were euthanized at 12 hr or, 1,2,3, or 5 days. An intraperitoneal injection of 5-bromo-2'-deoxyuridine at 100 mg/kg was given 90 min prior to euthanasia. In fumonisin B1 treated rats, serum cholesterol and serum urea nitrogen were elevated; however, the activity of hepatic enzymes was unaffected. Hepatic and renal glutathione concentrations were depressed at 12 and 24 hr, respectively, with subsequent recovery. Histologic changes were most prominent in the outer medulla of the kidney, with cell proliferation and apoptosis followed by nephrosis. Cell proliferation also occurred in the liver and esophagus, but in the absence of tissue injury. The labeling index peaked on day 1 for the liver and on day 3 for the esophagus. These results confirm that the primary target organ of fumonisin B1 in the rat is the kidney and support the concept that fumonisin B1-induced mitogenesis may be the mechanism of carcinogenesis.

Animals↗
PubMed1995

A method for the separation of delta bilirubin using Cibacron Blue affinity chromatography.

We developed and evaluated a method for the separation of delta bilirubin (B delta) by micro-column affinity chromatography based on Cibacron Blue 3G-A-Agarose. Untreated serum was applied to affinity columns and free non-protein bound bilirubins were eluted with phosphate buffer containing 20 g/l Triton X-100. Retained albumin was eluted using caffeine-benzoate reagent and bilirubin associated with this fraction (B delta) quantitated by the method of Jendrassik and Gróf modified by Doumas et al (Clin Chem 1985;31:1779-1789); results correlated well with the high performance liquid chromatography (HPLC) method (n = 35, y (affinity) = 1.009x (HPLC)-5.49; r = 0.959) described by Lauff et al. (J Chromatography 1981;226:391-402). Two controls analyzed with each batch gave between-batch imprecision less than 4.0% (n = 10; Control 1, mean = 20.05 mumol/l; Control 2, mean = 74.82 mumol/l). Within-batch imprecision was less than 3.3% for both levels. Specimens collected from 25 neonates less than 20 days of age showed a B delta concentration of 1.7 +/- 0.7 mumol/l (mean +/- 1 S.D.) and percent B delta of 2.2 +/- 1.9 (mean total bilirubin +/- 1 S.D. = 118 +/- 79 mumol/l). Although time consuming, this simple and precise method allows the measurement of B delta in laboratories without the need for specialized instruments.

Adult↗
PubMed1994

The prognostic significance of urinary albumin in Polynesians with non-insulin-dependent diabetes.

Polynesian (59 Maori and 30 Pacific Island) patients were identified from two diabetes clinic registers and followed for a mean of 4.8 years, in order to determine the prognostic significance of urinary albumin excretion. Events were defined as death or entry onto a renal replacement programme. Fourteen events occurred during the period of follow-up. Urinary albumin/creatinine ratio was treated as a continuous variable in a proportional hazards analysis. A 10-fold increase in albumin/creatinine ratio was associated with a 5-fold increase in the risk of an event (95% C.I. = 2.05-12.09). In conclusion, elevated urinary albumin/creatinine predicted mortality and renal morbidity in Maori and Pacific Island patients with non-insulin-dependent diabetes.

Albuminuria↗
PubMed1992

Salami publication.

Explore the source record for details and available documents.

Duplicate Publications as Topic↗
PubMed1991

Bradyarrhythmias in acute myocardial infarction: should thrombolysis lower the decision threshold for temporary pacing?

Both acute myocardial infarction and reperfusion therapy with thrombolytic agents may be associated with bradyarrhythmias, and there may be a case for 'prophylactic' insertion of a temporary pacing wire in selected patients. We describe 4 patients in whom clinical decisions had to be made concerning the appropriateness and timing of temporary pacing, and discuss the implications for modern guidelines on the indications for pacing in such a setting.

Bradycardia↗
PubMed1990

Clinical and ethnic characteristics associated with urinary albumin excretion in noninsulin dependent diabetic subjects attending the Wellington Hospital diabetes clinic.

In noninsulin dependent diabetes, elevation of urinary albumin excretion above the normal range is thought to predict increased mortality. A random urinary albumin/creatinine ratio and the following clinical characteristics were recorded on 405 patients with noninsulin dependent diabetes attending the Wellington Hospital diabetes clinic; (1) ethnic origin, (2) age, (3) sex, (4) age at diagnosis, (5) duration since diagnosis of diabetes, (6) body mass index, (7) systolic blood pressure, (8) diastolic blood pressure, (9) retinopathy, (10) insulin therapy, (11) antihypertensive therapy, and (12) the presence or absence of treated cardiovascular disease. The overall prevalence of elevated urinary albumin/creatinine ratio (greater than 2.2 mg/mmol) was 45%. Stepwise regression analysis showed that 12% of the variability of urinary albumin/creatinine ratio in our clinic population could be accounted for by ethnic origin of patients, with noncaucasians (the Maori, Pacific Islanders and Asians) having a higher urinary albumin excretion than caucasians (p less than 0.001). Systolic blood pressure, retinopathy and cardiovascular disease predicted a further 8% of this variability. The cause of this ethnic difference in urinary albumin excretion and its possible relationship to excess mortality in noncaucasians is not yet known.

Adolescent↗
PubMed1990

Comparison of urinary albumin excretion between Maoris, Pacific Island Polynesians and Europeans with non-insulin-dependent diabetes.

Elevated urinary albumin excretion is a marker for increased mortality and morbidity in European subjects with non-insulin-dependent diabetes. Urinary albumin excretion was compared in 32 Maoris, 34 Pacific Island Polynesians and 66 subjects of European origin with non-insulin-dependent diabetes attending a diabetes clinic in Wellington, New Zealand. The random urinary albumin to creatinine ratio was used as an estimation of urinary albumin excretion rate. The random urinary albumin to creatinine ratio was significantly higher in Maori and Pacific Island Polynesian subjects, compared to diabetic Europeans (geometric mean urinary albumin to creatinine ratios were 13.13, 12.00 and 2.79 mg/mmol respectively, P less than 0.05). These findings would be consistent with the high mortality and morbidity seen in the Maori and Pacific Island Polynesian diabetic populations. The correlation between hypertension and increased urinary albumin excretion was stronger in the Europeans than in the Maoris and Pacific Island Polynesians studied, suggesting that differences in blood pressure alone are unlikely to account for the observed differences in albumin excretion. Follow-up studies are required to determine whether diabetic Maoris and Pacific Island Polynesians with increased urinary albumin excretion have a similar prognosis to their European counterparts.

Albuminuria↗
PubMed1990

Effects of low and high relative molecular protein mass on four methods for total protein determination in urine.

Four commonly used methods for the determination of total protein in urine were compared. These were two biuret methods using different precipitants, a Ponceau S method and a Coomassie Brilliant Blue method. The protein content of the urines was also evaluated by sodium dodecylsulphate polyacrylamide gel electrophoresis. The biuret method with ethanolic phosphotungstic acid as precipitant correlated best with the Coomassie Brilliant Blue method (r = 0.944; p less than 0.001) but less well with the Ponceau S (r = 0.895; p less than 0.001) or biuret-trichloroacetic acid (r = 0.874; p less than 0.001) methods. For urines with normal electrophoretic protein patterns, the imprecise biuret-trichloroacetic acid method (cv = 18.5%) gave the greatest number of false high results (23 in 36 urines) as assessed by electrophoresis. False low results were common in low relative molecular mass (Mr) proteinuria, especially with the biuret-tricholoroacetic acid and Ponceau S methods. High Mr proteinuria rarely caused false low results. Discrepancies between methods appear to have resulted from incomplete precipitation of low Mr protein by trichloroacetic acid.

Azo Compounds↗
PubMed1988

Effects of sodium dodecylsulphate, dye concentration and paraprotein on coomassie blue dye-binding assays for protein in urine.

Various Coomassie Blue reagents, containing either increased dye concentration or added sodium dodecylsulphate, were compared with a biuret method for the assay of total protein in urine. When immunoglobulin free light chain protein or immunoglobulin paraprotein were present, results from the Coomassie Blue methods were up to 50% lower than with the biuret method; increased dye concentration did not improve comparability substantially, but the addition of sodium dodecylsulphate reduced the bias to about 20%. When neither free light chain protein nor immunoglobulin paraprotein was present, results from the Coomassie Blue methods were only about 30% lower. The addition of sodium dodecylsulphate reduced this bias to 10%. Correlations between the biuret and the Coomassie Blue method were best when the Coomassie Blue reagent contained 40 mg/L sodium dodecylsulphate (r better than 0.98 in all groups; p less than 0.001).

Binding, Competitive↗
PubMed1987

Mitochondrial creatine kinase in cancer patients.

We have developed a quantitative immunoassisted enzyme assay to screen for creatine kinase isoenzymes BB (CK-BB) and mitochondrial (CK-m) using commercial antibodies and reagents. Presence of CK-m activity was subsequently confirmed by electrophoretic separation of samples with elevated values. A prospective clinical trial was undertaken in 117 subjects: Normal (30), cirrhosis patients (30), myocardial infarction patients (30), and untreated oncology patients with metastatic malignancy (27). In 12 patients with malignancy CK-m activities were elevated; all had adenocarcinomas. No significant activity was detected in patients with other malignancies. CK-m positive tumour patients had a significantly higher mortality rate, and in two instances death was preceded by a sudden rise in CK-m activity. We suggest CK-m is a marker of adenocarcinoma and its presence in serum signifies increased mortality.

Adenocarcinoma↗