ISSN:
1573-2665
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Erythrocyte thiamin metabolism and transport were investigated in 7 patients from Brazil, Israel and Italy suffering from thiamin-responsive megaloblastic anaemia (TRMA) associated with diabetes mellitus and sensorineural deafness. All patients discontinued thiamin therapy for 4–7 days before the investigation. TRMA patients showed invariably reduced total thiamin levels in erythrocytes (percentage reduction compared with healthy controls, −46.8±3%; mean±SEM). The proportions of individual thiamin compounds, expressed as a percentage of total thiamin content, were within the normal range, whereas their absolute amounts were significantly decreased in the following order: thiamin monophosphate 〉 thiamin pyrophosphate 〉 thiamin. Thiamin pyrophosphokinase activity was also reduced as compared with controls (mean reduction±SEM, −25.9±1%). The saturable, specific component of thiamin uptake, which normally prevails at physiological concentrations of thiamin (〈2µmol/L), was absent in erythrocytes obtained from TRMA patients, while the non-saturable (diffusive) component of uptake was normally present. These results confirm observations made previously in two patients and demonstrate that TRMA is consistently associated with a state of thiamin deficiency, which is presumably secondary to reduced thiamin cellular transport and absorption (caused by lack of a membrane-specific carrier), and to impaired intracellular pyrophosphorylation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00712009
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