High-performance liquid chromatographic method for profiling 2-oxo acids in urine and its application in evaluating vitamin status in rats.

B-group vitamins are involved in the catabolism of 2-oxo acids. To identify the functional biomarkers of B-group vitamins, we developed a high-performance liquid chromatographic method for profiling 2-oxo acids in urine and applied this method to urine samples from rats deficient in vitamins B1 and B6 and pantothenic acid. 2-Oxo acids were reacted with 1,2-diamino-4,5-methylenebenzene to produce fluorescent derivatives, which were then separated using a TSKgel ODS-80Ts column with 30 mmol/L of KH2PO4 (pH 3.0):acetonitrile (7:3) at a flow rate of 1.0 mL/min. Vitamin B1 deficiency increased urinary levels of all 2-oxo acids, while vitamin B6 deficiency only increased levels of sum of 2-oxaloacetic acid and pyruvic acid, and pantothenic acid deficiency only increased levels of 2-oxoisovaleric acid. Profiles of 2-oxo acids in urine samples might be a non-invasive way of clarifying the functional biomarker of B-group vitamins.

Thiamine deficiency and its correlation with dyslipidaemia in diabetics with microalbuminuria.

OBJECTIVE: To measure and correlate the levels of thiamine and dyslipidaemia in microalbuminuric diabetics. METHODS: Cross-sectional comparative study was conducted at the Department of Biochemistry and Molecular Biology, Army Medical College, Rawalpindi, from January 2009 to December 2010, and comprised 60 known diabetic patients, who were inducted from diabetic clinics of Rawalpindi. These patients were divided into three equal groups, with group I (n=20) being normal healthhy individuals, group II comprised of microalbuminurics type 2 diabetics (n=20) and group III (n=20) were macroalbuminuric type 2 diabetics, based on their albumin excretion rate. The healthy volunteers (n=20) had blood glucose less than 6 mmol/L and were inducted as the comparison group. Fasting blood samples of diabetic and control groups were analysed for glucose, glycosylated haemoglobin, lipid profile, thiamine chloride and thiamine monophosphate. Besides, 24-hour urine samples were analysed for microalbuminuria, thiamine chloride and thiamine monophosphate. RESULTS: Plasma thiamine chloride and thiamine monophosphate levels were found to be significantly (p<0.001) reduced in the diabetics (n=60) compared to the controls (n=20). Furthermore, there was a progressive decline in these levels with increasing albuminuria; the lowest being in the macroalbuminuric group (group IV). Urinary thiamine levels were significantly (p<0.001) higher in the diabetics compared to the controls. These changes were more pronounced as albuminuria level increased; the highest being in group IV. The parameters of lipid profile, including triglycerides, total cholesterol and low-density lipoprotein cholesterol, were significantly (p<0.001) higher in diabetics and showed progressive increase with worsening albuminuria. Whereas, the high-density lipoprotein cholesterol levels were significantly (p<0.001) reduced in diabetics and showed progressive decline as the microalbuminuria status worsened. Furthermore, a significant negative correlation was found between plasma thiamine and all the parameters of lipid profile except high-density lipoprotein cholesterol which had a significant positive correlation. A significant linear regression of microalbuminuria on plasma thiamine was also found. CONCLUSION: Thiamine levels were reduced in the diabetic population and this reduction in thiamine level was negatively correlated with lipid profile in microalbuminuric diabetics.

[Influence of lead on metabolism of vitamins B group in alimentary iron deficient rats]. / Vliianie svintsa na obmen vitaminov gruppy B pri alimentarnoí nedostatochnosti zheleza u krys.

Experimentally induced lead poisoning especially under simultaneous iron deficit leads to the development of secondary thiamine insufficiency. Erythrocyte riboflavin content and erythrocyte glutathion reductase and aspartate aminotransferase activities have been demonstrated to be increased. Lead treatment is accompanied with the increase of urinary excretion of riboflavin, 4-pyridoxic acid and 1-vtthylnicotinamide in rats fed with adequate diet. Thus lead intoxication and iron deficiency influence vitamin B group metabolism.

Thiamin, riboflavin and vitamin B6: impact of restricted intake on physical performance in man.

OBJECTIVE: A combined marginally deficient status of thiamin, riboflavin, vitamin B6 and vitamin C may affect physical performance, but the relative contribution of each vitamin can only be speculated. In a previous study we did not find any effect of restricted intake of vitamin C individually. Therefore, the functional effect of restriction of thiamin, riboflavin or vitamin B6, individually or in conjunction, was investigated. METHODS: A double-blind, 2 x 2 x 2 complete factorial experiment on the effects of thiamin, riboflavin and vitamin B6 restriction on physical performance was executed with 24 healthy men. During 11 weeks of low vitamin intake, the subjects were given a daily diet of regular food products providing no more than 55% of the Dutch Recommended Dietary Allowances (RDA) for thiamin, riboflavin and vitamin B6. Other vitamins were supplemented at twice the RDA level. RESULTS: In vitamin-restricted subjects, blood vitamin levels, erythrocytic enzyme activities and urinary vitamin excretion decreased and in vitro erythrocytic enzyme stimulation increased. Short-time vitamin restriction had no harmful effects on health. A significant overall decrease was observed in aerobic power (VO2-max; 11.6%), onset of blood lactate accumulation (OBLA; 7.0%) and oxygen consumption at this power output (VO2-OBLA; 12.0%), peak power (9.3%), mean power (6.9%) and related variables (p < 0.01). However, the observed performance decrements could not be attributed to marginal deficiency for any of the vitamins studied. CONCLUSION: The absence of vitamin-specific effects on performance decrements due to thiamin, riboflavin and vitamin B6 restriction suggests quantitatively similar but non-additive effects of these B-vitamins on mitochondrial metabolism.

Thiamine deficiency in patients with congestive heart failure receiving long-term furosemide therapy: a pilot study.

PURPOSE: To test the hypothesis that long-term furosemide therapy in patients with congestive heart failure (CHF) is associated with clinically significant thiamine deficiency via urinary loss. DESIGN: (1) Biochemical evaluation of thiamine status in hospitalized patients with CHF treated with long-term furosemide and in age-matched control patients. (2) Uncontrolled trial of the effect of intravenous thiamine on cardiac performance in a subset of six patients with CHF. SETTING: General medical ward of a teaching community hospital. PATIENTS: Twenty-three patients with chronic CHF receiving furosemide, and 16 age-matched control patients without heart failure and not taking diuretics. Daily furosemide doses were 80 to 240 mg, and duration of furosemide therapy was 3 to 14 months. Patients with identifiable causes of inadequate thiamine intake, absorption, or utilization or increased metabolic requirements were excluded. INTERVENTION: A 7-day course of intravenous thiamine, 100 mg twice daily, in six consenting patients with CHF. RESULTS: A high thiamine pyrophosphate effect (TPPE), indicating thiamine deficiency, was found in 21 of 23 furosemide-treated patients and in two of 16 controls (p less than 0.001). The mean (+/- SE) TPPE (normal: 0% to 15%) in furosemide-treated and control patients was 27.7 +/- 2.5% and 7.1 +/- 1.6%, respectively (p less than 0.001). Despite the high TPPE, the mean (+/- SE) urinary thiamine excretion in the furosemide-treated patients (n = 18) was inappropriately high (defined as greater than 130 micrograms/g creatinine), 410 +/- 95 micrograms/g creatinine, even in comparison with that in the controls (n = 14): 236 +/- 69 micrograms/g creatinine. In six patients treated with intravenous thiamine, the elevated TPPE decreased to normal, from a mean (+/- SE) of 27.0 +/- 3.8% to 4.5 +/- 1.3% (p less than 0.001), indicating normal thiamine utilization capacity. Left ventricular ejection fraction increased in four of five of these patients studied by echocardiography. CONCLUSIONS: These preliminary findings suggest that long-term furosemide therapy may be associated with clinically significant thiamine deficiency due to urinary loss and contribute to impaired cardiac performance in patients with CHF. This deficit may be prevented or corrected by appropriate thiamine supplements.

Studies on metabolism of thiamine chloride ester monophosphate of bis-D-glucosamine. II. Effect of TCMPG in vitamin B1-deficient rats.

In order to investigate the metabolism of thiamine chloride ester monophosphate of bis-D-glucosamine (TCMPG) urinary excretion, blood levels and tissue content of thiamine in vitamin B1-deficient rats were measured after intraperitoneal injection of this compound or of thiamine monophosphate or of a mixture of thiamine monophosphate and glucosamine. The greater retention and the higher levels of vitamin observed in the blood and in the tissues of animals treated with TCMPG compared with the control rats confirm the hypothesis that a more efficient utilization of vitamin B1 is obtained by the organism when it is administered salified with glucosamine.

[Thiamine and pyruvic acid content in the urine of patients with ununited fractures and pseudarthroses]. / Soderzhanie tiamina i pirovinogradnoi kisloty v moche u bol'nykh s nesrosshimisia perelomami i lozhnymi sustavami

The authors report the results of studies on the thiamine and pyruvic acid content in the urine of 170 individuals (34 healthy persons and 136 patients with no union of fractures and pseudarthrosis). In patients with nonunited fractures and pseudarthrosis a deficiency of vitamin B1 is observed.