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Results for “THIAMINE PYROPHOSPHATE”

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At least 109 records · Page 6Linked to original sources
PubMed1999

Thiamin deficiency in HIV-positive patients: evaluation by erythrocyte transketolase activity and thiamin pyrophosphate effect.

BACKGROUND AND AIMS: The aim of the study was to determine the thiamin status in HIV-positive patients. METHODS: Measurement of erythrocyte transketolase activity (ETK) and thiaminpyrophosphate (TPP) effect in 55 consecutive HIV-positive patients of a specialized outpatient clinic were grouped into five groups according to their CD4 counts. Comparison of results of HIV-positive patients with age-matched control group of 22 healthy subjects. RESULTS: Of the patients, 27% had a pathologically-increased TPP effect, 18% of the patients had pathologically-low ETK. The percentage of pathological values of TPP effect in the patients was significantly higher compared with the control group. There was no statistically significant correlation between pathological thiamin status and stage of the disease, zidovudine therapy or nutritional status of the patients. CONCLUSIONS: Thiamin deficiency in HIV-positive patients was found in a higher percentage than previously reported. Thiamine deficiency is not only present in advanced stages of HIV-infection, but also in clinically asymptomatic patients.

Adult↗
PubMed1976

Preparation of Escherichia coli pyruvate oxidase utilizing a thiamine pyrophosphate affinity column.

An improved procedure is reported for the purification of Escherichia coli pyruvate oxidase (pyruvate:ferricytochome b1 oxidoreductase, EC 1.2.2.2), a peripheral membrane flavo-enzyme, which is much more reproducible and requires considerably less time than the original purification scheme. The key element in this protocol is a new Sepharose-based affinity resin designed for the isolation of thiamine pyrophosphate-requiring enzymes. The synthesis, partial characterization, and use of two such affinity resins is described. Pyruvate oxidase is a pure, homogenous protein as it is eluted from the affinity resin. The enzyme is a tetramer with a subunit molecular weight of approx. 60 000. The subunits appear to be identical. The isoelectric point of pyruvate oxidase is 5.6.

Chromatography, Affinity↗
PubMed1996

Thiamine pyrophosphate effect and normalized erythrocyte transketolase activity ratio in Wernicke-Korsakoff patients and acute alcoholics undergoing detoxification.

Thiamine deficiency may be assessed clinically by an abnormally low specific erythrocyte transketolase activity and/or by abnormally large activation by thiamine diphosphate in vitro (or 'TPP effect'). In the present investigation, we report erythrocyte transketolase activation by TPP in acute alcoholics and Wernicke-Korsakoff patients undergoing detoxification. A new age-dependent parameter was used to improve the reliability of transketolase activity as an indicator of marginal thiamine deficiency. Thus normalized transketolase activity ratio (NTKZ), primary activation ratio (PAR) and further activation ratio (FAR) were measured in 29 acute alcoholics and 12 Wernicke-Korsakoff patients upon admission, and also on 47 control subjects. It was possible to follow up 14 of the 29 acute alcoholics after 7 days of treatment. Twenty-one per cent of the acute alcoholics and 33% of the Wernicke-Korsakoff patients, on admission to the detoxification Unit, had NTKZ values beyond the defined critical conditions for thiamine deficiency, whereas 7% of the former and 25% of the latter had PAR values beyond these critical conditions. Furthermore, all three parameters were significantly different in the Wernicke-Korsakoff patients compared to the other groups. The pattern of improvement of the different parameters on follow-up varied considerably and is difficult to explain, as only the NTKZ was statistically significant. Hence, only eight out of 14 acute alcoholics showed improvement in NTKZ, seven showed improvement of PAR and six showed improvement of FAR after treatment. Five patients showed improvement of both NTKZ and PAR and none of the patients showed improvement of all three parameters. We conclude that our findings confirm previous reports and that this modified transketolase activation test improves its reliability as an indicator of marginal thiamine deficiency.

Adult↗
PubMed2000

Vitamin B(1) status assessed by direct measurement of thiamin pyrophosphate in erythrocytes or whole blood by HPLC: comparison with erythrocyte transketolase activation assay.

BACKGROUND: The concentration of thiamin diphosphate (TDP) in erythrocytes is a useful index of thiamin status. We describe an HPLC method for TDP and its results in patients at risk of thiamin deficiency. METHODS: We used reversed-phase HPLC with postcolumn derivatization with alkaline potassium ferricyanide and fluorescence detection. Samples were deproteinized and injected directly onto a C(18) column. TDP concentrations in erythrocytes were compared with those in whole blood. Reference intervals for erythrocyte TDP (n = 147; 79 males and 68 females; mean age, 54 years) and whole blood TDP (n = 124; 68 males and 56 females; mean age, 54 years) were determined in an apparently healthy population. We compared erythrocyte TDP with results of the erythrocyte transketolase activation test in 63 patients who were considered at risk of thiamin deficiency. RESULTS: The method was linear to at least 200 microgram/L. The between-run CV was <8%. The lower limit of quantification for both whole blood and packed erythrocytes was 300 pg on column with a detection limit of 130 pg on column. Recovery of TDP from blood samples was >90%. TDP in erythrocytes correlated strongly with that in whole blood (r = 0.97). Reference intervals for erythrocyte and whole blood TDP were 280-590 ng/g hemoglobin and 275-675 ng/g hemoglobin, respectively. Of the 63 patients suspected of thiamin deficiency, 46 were normal by both TDP and activation tests, 13 were deficient by both tests, 1 was deficient by the activation test but had normal erythrocyte TDP concentrations, and 4 were normal by the activation test but had low TDP. CONCLUSIONS: The HPLC method is precise and yields results similar to the erythrocyte activation assay.

Chromatography, High Pressure Liquid↗
PubMed1983

[Enzyme activity of thiamine pyrophosphate in the rat after oxythiamine administration].

Intraperitoneal injection of hydroxythiamine to rats (1 mmol per kg bw) resulted after 2-4 h in a more than 4-fold decrease in the activity of the oxoglutarate dehydrogenase complex, pyruvate dehydrogenase complex and NADP-dependent isocitrate dehydrogenase in adrenal mitochondria. Inhibition of hyaloplasmic transketolase, 6-phosphogluconate dehydrogenase and NADP-dependent malate dehydrogenase occurred later. Based on the correlation of the time course of enzymatic activity in the adrenals and the decreased concentration of 11-hydroxycorticosteroids in the blood the paramount role in the maintenance of the steroidogenesis among thiamine pyrophosphate-containing enzymes is assigned to the oxoglutarate dehydrogenase and pyruvate dehydrogenase complexes.

11-Hydroxycorticosteroids↗