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Biomedical subjects

T S Koh

Publications and source records attributed to T S Koh.

34 records · Page 2Linked to original sources
PubMed1987

Copper and selenium deficiency in cattle: an evaluation of methods of oral therapy and an observation of a copper-selenium interaction.

The efficacies of oxidised copper particles, selenium bullets and soluble glass bullets in raising the copper and/or selenium reserves of young cattle marginally deficient in both trace elements were examined. Selenium bullets were associated with a reduced copper uptake when selenium bullets and oxidised copper particles were given together. Responses in liveweight gains to trace-element supplementation and relationships between copper or selenium in blood components and liver are presented.

Administration, Oral↗
PubMed1986

A comparison of blood lead levels in dogs from a lead-mining, lead-smelting, urban and rural island environment.

A survey of blood lead concentrations was undertaken with 368 dogs from a lead-mining (Broken Hill), lead-smelting (Port Pirie), urban (Adelaide) and rural island (Kangaroo Island) environment. Least squares mean blood lead concentrations differed significantly (p less than 0.001) between locations and were 1.05, 0.80, 0.38 and 0.32 mumol/L respectively; there were also significant differences between young (0.75) and older (0.52) dogs (p less than 0.01) and between male (0.71) and female (0.57) dogs (p less than 0.05). Approximately 14% of dogs from Broken Hill and 10% from Port Pirie had blood lead concentration in excess of 1.7 mumol/L. It is likely that a higher proportion of the dogs at Broken Hill and Port Pirie were asymptomatically suffering from the insidious effects of lead that has not been detected.

Animals↗
PubMed1983

Critical re-appraisal of fluorometric method for determination of selenium in biological materials.

The reaction of 2,3-diaminonaphthalene (DAN) with Se(IV) to form a fluorescent Se-DAN complex is the basis of a fluorometric method for determination of Se. With the aid of metabolically incorporated 75Se the method was critically re-examined. The study showed that loss of 75Se was negligible when liver or blood was microwave-dried or thermally dried at temperatures up to 120 degrees C; during HCl reduction of Se(VI) to Se(IV), a temperature up to 210 degrees C could be used with no loss of 75Se; it was unnecessary to perform pH adjustment of solution for formation of Se-DAN complex before solvent extraction; it was unnecessary to carry out the chelation/extraction step in diffuse light; solvent phase containing Se-DAN complex could be left in contact with aqueous phase up to one week under fluorescent light with no effect on analytical results. From this study we were able to dispute or overcome a number of criticisms and myths which have been laid against the fluorometric method for many years. As a result, an improved single tube method was developed. The within-batch variation of the improved method was about 2%, while the between-batch variation over a period of 2 years was less than 10%. The method can handle 200 samples per batch and is applicable to a wide range of biological samples including liver, orchard leaves, barley, wheat, lucerne (alfalfa), poultry feed, fish, hair, blood, urine, and milk.

2-Naphthylamine↗
PubMed1980

Trace element analysis of bovine liver: interlaboratory survey in Australia and New Zealand.

An interlaboratory survey of the determination of trace elements in bovine liver was undertaken. Thirty-three laboratories from Australia and 15 from New Zealand returned results. Moisture determination results were variable despite the use of a recommended drying procedure. For the 10 trace elements determined, the mean values (microgram/g) with their interlaboratory coefficients of variation (CV) were: cadmium, 1.2 (42.5%); cobalt, 0.21 (9.5%); copper, 110 (6.0%); iron, 276 (11.0%); lead, 0.6 (48.9%); manganese, 8.6 (13.9%); mercury, 0.03 (30.0%); molybdenum, 2.5 (45.6%); selenium, 1.0 (17.5%); zinc, 219 (8.2%). The intralaboratory CV for determining each of these elements was less than 9% except for the lead CV which was 20.2%. Results for the determination of sodium, potassium, calcium, and magnesium were also reported. The survey shows that while the use of a standard reference material can improve the performance of laboratories in trace element analysis, it may also introduce analytical bias.

Animals↗
PubMedDate not supplied

Interlaboratory study of blood selenium determinations.

Fifty-one laboratories from 14 countries participated in a survey on the determination of selenium (Se) in 8 bovine blood samples with Se concentrations ranging from 0.2 mumol/L (0.016 microgram/mL) to 14 mumol/L (1.1 micrograms/mL). The methods used (and the percentage of participants using each method) were fluorometry (61), hydride-generation atomic absorption spectrophotometry (AAS) (23), graphite-furnace AAS (6), gas chromatography (4), neutron activation analysis (4), and X-ray fluorometry (2). There was little difference in the mean Se results obtained by fluorometry or hydride-generation AAS (P greater than 0.05). Mean intralaboratory coefficients of variation (CVs) from known replicates ranged from 4 to 14% for all samples. Interlaboratory CVs were related to blood Se concentration and increased to 55% at Se levels below 0.4 mumol/L (0.032 microgram/mL). Laboratories that used quality control (QC) schemes had lower interlaboratory CVs than those that did not, but the advantage began to diminish at blood Se concentration below 0.4 mumol/L (0.032 microgram/mL). The high interlaboratory CVs, coupled with the false assurance from the low intralaboratory CVs and the ineffectiveness of the QC schemes at blood Se concentrations below 0.4 mumol/L (0.032 microgram/mL), are of concern in diagnosis of marginal Se deficiency in livestock where the concentrations of interest are in the range 0.15-0.5 mumol/L (0.012-0.039 microgram/mL).

Animals↗