Beriberi, which was considered a disease of the past, reappeared around 1973. Recently, cases of severe lactic acidosis induced by vitamin B₁ deficiency during total parenteral nutrition have been reported. Diagnosis of vitamin B₁ deficiency requires on assay and standard values for human blood vitamin B₁. We standardized measurement of whole blood vitamin B₁ levels using three HPLC techniques (post-column reversed-phase HPLC, pre-column reversed-phase HPLC, and pre-column GP-HPLC). The reference range was obtained in 54 volunteers administered a 1,800 kcal diet with 2 mg of vitamin B₁ (1.74mg measured) daily to avoid marginal vitamin B₁ deficiency in the population. The range for each assay was 26-47ng/ml, 28-51ng/ml and 28-56ng/ml, respectively. Our data suggest that 26-28ng/ml is the lower limit of normal for whole blood vitamin B₁, but further studies in a larger population are needed to obtain more definitive results.

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Among various methods used, high-performance liquid chromatography (HPLC) has been well recognized as a powerful tool for separating and determinating biologically important substances, in particular, polar and/or unstable compounds. The great success of this methodology can be ascribed to the development of excellent software for the detection system as well as fine instrumentation and column technology hardware. To obtain high sensitivity and specificity, precolumn derivatization has been widely carried out in labeling with a fluorophore, chromophore or electrophore. However, this technique includes a tedious procedure under nonphysiological conditions. Recently, a hyphenated method with mass spectrometry, LC/MS, has been used with increasing frequency in the bioanalytical field. Among numerous interfaces, electrospray ionization (ESI) has been considered more useful for detection and determination of biologically important compounds containing ionic group (s). In this paper, we describe the separation and determination of bile acids conjugated with sulfic acid or glucuronic acid in biological fluids by LC/ESI-MS.

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A new assay of serum complement activity was developed for complement analysis of serum with a low total complement activity level (CHSO). The principle of this method is to detect amounts of C3 convertase in the classical complement pathway (C42) generated by the test serum. Hemolysis of sensitized sheep erythrocytes (EA) was measured after incubation with diluted test serum for various incubation periods, followed by another 60 min incubation with guinea-pig serum diluted in EDTA buffer. Formation and decay of C42 on EA was estimated from the C42-T_max curve, obtained by plotting the hemolytic ratio on the ordinate against the incubation period on the abscissa. For pooled normal human serum (NHS) diluted 1: 600 in gelatin veronal buffer, the C42-T_max. curve showed a T_max (time of maximal hemolysis) at 4-5 min and Y_max (hemolytic ratio at T_max) of 60-90% lysis. The decrease in hemolytic ratio after T_max is probably due to the decay of active C2 from EA. C42-T_max obtained with various sera showed that Y_max was decreased in low CH50 serum after classical complement pathway activation, depending on the degree of complement activation. Furthermore, low CH50 serum after alternative complement pathway activation as well as C7-or C9-deficient serum showed C42-T_max curves similar to that by NHS. Thus, C42-T_max is a simple and rapid assay for serum complement activity as a combination activity of C1, C4, and C2.

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