Blood vitamin B1, transketolase and thiamine pyrophosphate (TPP) effect in beriberi patients, with studies employing discriminant analysis

Protocol and application of basal erythrocyte transketolase activity to improve assessment of thiamine status

Thiamine (vitamin B1) is an essential micronutrient required as a cofactor in many metabolic processes. Clinical symptoms of thiamine deficiency are poorly defined, hence biomarkers of thiamine status are important. The erythrocyte transketolase activity coefficient (ETKac) is a sensitive measure of thiamine status, but its interpretation may be confounded where the availability of the transketolase enzyme is limited. Basal ETK activity per gram of hemoglobin provides a complementary biomarker of thiamine status; however, its measurement and calculation are poorly described. Here, we describe in detail the assessment of basal ETK activity, including the calculation of path length in microplates and the molar absorption coefficient of NADH specific to the assay, and the measurement of hemoglobin in sample hemolysates. To illustrate the application of the methods, we present ETKac and basal ETK activity from women in The Gambia and UK. In conclusion, we present a clear protocol for the measurement of basal ETK activity that will permit the harmonization of methods to improve replication between laboratories.

Immunocapture and microplate-based activity and quantity measurement of pyruvate dehydrogenase in human peripheral blood mononuclear cells

BACKGROUND

Pyruvate dehydrogenase (PDH) activity is altered in many human disorders. Current methods require tissue samples and yield inconsistent results. We describe a modified method for measuring PDH activity from isolated human peripheral blood mononuclear cells (PBMCs). RESULTS/METHODOLOGY: We found that PDH activity and quantity can be successfully measured in human PBMCs. Freeze-thaw cycles cannot efficiently disrupt the mitochondrial membrane. Processing time of up to 20 h does not affect PDH activity with proteinase inhibitor addition and a detergent concentration of 3.3% showed maximum yield. Sample protein concentration is correlated to PDH activity and quantity in human PBMCs from healthy subjects.

CONCLUSION

Measuring PDH activity from PBMCs is a novel, easy and less invasive way to further understand the role of PDH in human disease.

Wernicke encephalopathy in children and adolescents

BACKGROUND

Wernicke encephalopathy is caused by thiamine (vitamin B1) deficiency. It is generally considered to be a disease of adult alcoholics. However, it is known to occur in the pediatric population and in non-alcoholic conditions.

DATA SOURCES

We searched PubMed with the key words Wernicke, thiamine, pediatric, children and adolescents and selected publications that were deemed appropriate.

RESULTS

The global prevalence rates of hunger, poverty and resultant nutrient deprivation have decreased in the 21st century. However, several scenarios which may predispose to Wernicke encephalopathy may be increasingly prevalent in children and adolescents such as malignancies, intensive care unit stays and surgical procedures for the treatment of obesity. Other predisposing conditions include magnesium deficiency and defects in the SLC19A3 gene causing thiamine transporter-2 deficiency. The classic triad consists of encephalopathy, oculomotor dysfunction and gait ataxia but is not seen in a majority of patients. Treatment should be instituted immediately when the diagnosis is suspected clinically without waiting for laboratory confirmation. Common magnetic resonance findings include symmetric T2 hyperintensities in dorsal medial thalamus, mammillary bodies, periaqueductal gray matter, and tectal plate.

CONCLUSIONS

Wernicke encephalopathy is a medical emergency. Delay in its recognition and treatment may lead to significant morbidity, irreversible neurological damage or even death. This article aims to raise the awareness of this condition among pediatricians.

Whole cell immobilized amperometric biosensor based on Saccharomyces cerevisiae for selective determination of vitamin B1 (thiamine)

A new amperometric whole cell biosensor based on Saccharomyces cerevisiae immobilized in gelatin was developed for selective determination of vitamin B1 (thiamine). The biosensor was constructed by using gelatin and crosslinking agent glutaraldehyde to immobilize S. cerevisiae cells on the Teflon membrane of dissolved oxygen (DO) probe used as the basic electrode system combined with a digital oxygen meter. The cells were induced by vitamin B1 in the culture medium, and the cells used it as a carbon source in the absence of glucose. So, when the vitamin B1 solution is injected into the whole cell biosensor system, an increase in respiration activity of the cells results from the metabolic activity and causes a decrease in the DO concentration of interval surface of DO probe related to vitamin B1 concentration. The response time of the biosensor is 3 min, and the optimal working conditions of the biosensor were carried out as pH 7.0, 50mM Tris-HCl, and 30 degrees C. A linear relationship was obtained between the DO concentration decrease and vitamin B1 concentration between 5.0 x 10(-3) and 10(-1) microM. In the application studies of the biosensor, sensitive determination of vitamin B1 in the vitamin tablets was investigated.

Individual susceptibility to Wernicke-Korsakoff syndrome and alcoholism-induced cognitive deficit: impaired thiamine utilization found in alcoholics and alcohol abusers

To investigate mechanisms predisposing to alcoholic brain damage, thiamine (vitamin B1 ), riboflavin (vitamin B2 ) and pyridoxine (vitamin B6 ) status was compared in persistent alcohol misusers (PAM) admitted for detoxification without evidence of significant brain damage, in alcoholics known to have severe chronic brain damage (BDAM), and in age, gender and ethnicity matched controls. Thus, activities of thiamine-dependent transketolase (ETK), riboflavin-dependent glutathione reductase, and pyridoxine-dependent aspartate amino transferase were assayed, together with the enzyme activities following addition of the appropriate co-factor. Twenty per cent of the PAM group had an abnormally low ETK activity and an abnormally high activation ratio, while 45% were abnormal in either one or both parameters. An additional 10% of the PAM group had an abnormally high activation ratio but normal ETK activity, as did 30% of the BDAM group. These subgroups of alcohol misusers may have increased requirements for thiamine secondary to an abnormality of the transketolase protein that may predispose such patients to alcoholic brain damage. There was no evidence of riboflavin or pyridoxine deficiency in either of the patient groups. We conclude that thiamine deficiency was commonly present in the alcoholic patients, and that a subgroup of patients may be predisposed to more severe brain damage as a consequence of abnormalities in the transketolase protein.

Postgastrectomy polyneuropathy with thiamine deficiency

OBJECTIVE

Polyneuropathy has been reported after gastrectomy performed to treat various lesions. Although thiamine deficiency is a possible cause of this neuropathy, the pathogenesis still remains to be clarified. Seventeen patients with peripheral neuropathy with thiamine deficiency after gastrectomy are described.

METHODS

Seventeen patients with polyneuropathy after gastrectomy accompanied by thiamine deficiency were selected. Patients were restricted to those with total or subtotal gastric resection to treat ulcer or neoplasm. Patients who had undergone operations to treat morbid obesity were excluded.

RESULTS

Intervals between the operation and onset of neuropathy varied from 2 months to 39 years. Most patients did not seem malnourished. Serum concentrations of B vitamins other than thiamine were nearly normal. Symmetric motor-sensory polyneuropathy, predominantly involving the lower limbs, had progressed over intervals varying from 3 days to 8 years. Relative degrees of motor and sensory impairment also varied extensively. Some cases that progressed rapidly mimicked Guillain-Barré syndrome. Electrophysiological and pathological findings were those of axonal neuropathy. Substantial functional recovery from polyneuropathy was seen in most patients by 3 to 6 months after initiating thiamine supplementation. Motor recovery was better than sensory recovery.

CONCLUSIONS

Various symptoms were seen in patients with postgastrectomy neuropathy. Thiamine deficiency should be considered in the differential diagnosis of motor-sensory polyneuropathy after gastrectomy.

Determination of thiamine by high-performance liquid chromatography

High-performance liquid chromatographic methods for the determination of thiamine (vitamin B1) in foodstuffs or biological tissues and fluids are outlined and discussed. The methods are often similar and interchangeable, sample extraction and clean up procedures being the major difference. Most of the methods use either ultraviolet or fluorescence detection. Fluorescence detection requires either precolumn or postcolumn oxidation of thiamine to thiochrome. A number of methods are recommended and problems with standardization are emphasized.

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.

Acute beriberi following liver transplantation

Patients scheduled for orthotopic liver transplantation (OLT) undergo extensive routine preoperative cardiac assessment. We describe a 32-year-old male who underwent uneventful OLT for endstage liver failure on the basis of chronic hepatitis C and alcoholism. Despite a normal preoperative cardiac workup, the patient developed acute pulmonary edema on the second postoperative day. A diagnosis of beriberi was entertained and confirmed by (1) the thiamine diphosphate effect and (2) the dramatic response to intravenous thiamine. Possible precipitating factors are described. Thiamine, which has no significant toxicity, should probably be routinely supplemented in all patients undergoing OLT, especially those with a previous history of alcohol abuse.

Brain alpha-ketoglutarate dehydrogenase complex activity in Alzheimer's disease

We measured the activity of the alpha-ketoglutarate dehydrogenase complex (alpha-KGDHC), a rate-limiting Krebs cycle enzyme, in postmortem brain samples from 38 controls and 30 neuropathologically confirmed Alzheimer's disease (AD) cases, in both the presence and absence of thiamine pyrophosphate (TPP), the enzyme's cofactor. Statistically significant correlations between brain pH and lactate levels and alpha-KGDHC activity in the controls were observed, suggesting an influence of agonal status on the activity of alpha-KGDHC. As compared with the controls, mean alpha-KGDHC activity, with added TPP, was significantly (p < 0.005) reduced in AD brain in frontal (-56%), temporal (-60%), and parietal (-68%) cortices, with the reductions (-25 to -53%) in the occipital cortex, hippocampus, amygdala, and caudate failing to reach statistical significance. In the absence of exogenously administered TPP, mean alpha-KGDHC activity was reduced to a slightly greater extent in all seven AD brain areas (-39 to -83%), with the reductions now reaching statistical significance in the four cerebral cortical areas and hippocampus. A statistically significant negative correlation was observed between alpha-KGDHC activity and neurofibrillary tangle count in AD parietal cortex, the brain area exhibiting the most marked reduction in enzyme activity; this suggests that the enzyme activity reduction in AD brain may be related to the disease process and severity. In each brain area examined, TPP produced a greater stimulatory effect on alpha-KGDHC activity in the AD group (23-280% mean stimulation) as compared with the controls (-4 to +50%); this TPP effect could be explained by reduced endogenous TPP levels in AD brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced proteolytic activities in cultured fibroblasts of Alzheimer patients are revealed by peculiar transketolase alterations

Characteristic alterations of transketolase (TK) in extracts from cultured Alzheimer fibroblasts have previously been reported (Paoletti et al. (1990) Biochem. Biophys. Res. Commun., 172: 396-401). These abnormalities, encountered in 9 out of 13 Alzheimer patients, were revealed following isoelectric focusing and consisted of enzyme forms having unusually high alkaline pI values (alkaline bands). The present work has shown that immunologically detected alkaline bands were progressively expressed when Alzheimer fibroblasts were incubated for three weeks without medium changes. Full expression of the altered enzyme pattern was not linked to relative cell density in the petri dish; rather, it appeared to be dependent directly on the time elapsed since cell confluence was reached. Alkaline bands could artificially be induced also in both crude and pure TK preparations from normal cells by a treatment with commercial proteases, particularly chymotrypsin. Moreover, specific inhibitors of endogenous cysteine-proteases were capable of abolishing TK alkaline bands in Alzheimer fibroblasts thus turning a pathological into a normal enzyme pattern. Results obtained suggest that Alzheimer fibroblasts contain enhanced Ca(2+)-independent cysteine-proteolytic activities as compared to normal and other pathological cells. These enzymes, exhibiting chymotrypsin-like activity, might exert their degradative effects at the time of cell extraction using TK and probably other cell components as potential substrates. However, peculiar TK abnormalities represent so far an useful biochemical marker detectable in fibroblasts of living Alzheimer patients and closely associated to this neurological disorder.

The relationship between erythrocyte transketolase activity and the 'TPP effect' in Wernicke's encephalopathy and other thiamine deficiency states

Patients (n = 104) were judged to be thiamine deficient by the criteria of erythrocyte transketolase activity (ETK) less than 0.6 U/g of hemoglobin, or greater than 17% increase in this activity on addition of thiamine pyrophosphate in vitro (TPP effect). ETK activated by TPP in vitro (AETK) was related to ETK by a linear regression of slope greater than or equal to 1, implying that transketolose apoenzyme (apoTK) was constant or decreased as ETK decreased. For most patient groups the value of apoTK was 0.1 U/g and the slope 1.033 to 1.050. In the subgroup of non-vomiting drinkers with Wernicke's encephalopathy (WE), the slope of the linear regression of AETK on ETK was 1.21, so that apoTK decreased as ETK decreased. Comparison of these data is consistent with a difference in the TK of WE drinkers from that of others. Generally, any variation of TPP effect was due only to variation of ETK. We recommend measurement of ETK, without TPP effect, for the assessment of thiamine nutrition.

The evaluation of erythrocyte thiamin diphosphate as an indicator of thiamin status in man, and its comparison with erythrocyte transketolase activity measurements

HPLC measurement of the major physiological form of thiamin, thiamin diphosphate, in erythrocytes (ETDP) has been assessed as an indicator of thiamin status and compared with erythrocyte transketolase activity (ETKA) before and after activation with exogenous thiamin diphosphate (TDP effect). The comparison was made by following the response of the parameters to incubation of erythrocytes with thiamin and by measurements in alcoholic, elderly and student groups. All parameters were responsive to the thiamin content of their environment, but ETDP was at least as sensitive as TDP effect and more sensitive than ETKA in reflecting thiamin uptake and utilisation by erythrocytes. There was a better correlation between ETDP and ETKA than between ETDP and TDP effect. All the groups showed a significant positive correlation between ETDP and ETKA, but only the elderly and the alcoholic groups showed a significant negative correlation between ETDP and TDP effect. The lack of correlation between ETDP and TDP effect in the student group may be due to the relative imprecision of TDP effect measurements at the lower end of the reference range. ETDP is more stable than ETKA in frozen erythrocytes, is easier to standardise and is not affected by various factors which can influence the enzyme assay. Measurement of ETDP is, therefore, recommended for first line assessment of thiamin status.

The influence of hepatic insufficiency due to alcoholic cirrhosis on the erythrocyte transketolase activity (ETKA)

The erythrocyte transketolase activity (ETKA), the stimulated erythrocyte transketolase activity (ETKAS), and the thiaminepyrophosphate effect (TPPE) were measured in 21 alcoholic patients with cirrhosis and hepatic insufficiency, 13 alcoholic patients without cirrhosis and 21 non-alcoholic persons before and after oral treatment with 100 mg of thiamine daily for 2 weeks in order to investigate the influence of hepatic insufficiency on these variables. A statistically significant rise in ETKA and fall in TPPE were found in all three groups. ETKA, ETKAS and TPPE did not differ from each other in alcoholic patients with and without cirrhosis, but TPPE was significantly higher in these patients than in the non-alcoholic persons. The conclusions are that severe cirrhosis does not affect the erythrocyte transketolase apoenzyme, the ability of the tissues to convert thiamine to thiaminepyrophosphate for use in the erythrocytes or the absorption of thiamine from the gastrointestinal tract. Besides alcoholism seems to dispose to thiamine deficiency to a higher degree than cirrhosis, and the role of the liver as a thiamine store appears to be of minor importance in the development of thiamine deficiency. Finally, ETKA, ETKAS, and TPPE are considered to be usable as thiamine deficiency indicators in patients with cirrhosis as well as in patients without cirrhosis.

Adult thiamine requirements and the continuing need to fortify processed cereals

Erythrocyte transketolase activity as measured by a new fluorimetric method was used to define the tissue thiamine status of an age-stratified sample of 42 adults. Concurrent 7-day dietary assessments were made. 26% of subjects (6/21 men, 5/21 women) were biochemically abnormal. Subjects who were biochemically normal had mean daily thiamine intakes that were 41% (for men) and 36% (for women) greater than those for biochemically abnormal subjects. Differences in absolute thiamine intake (mg/day) were greater and more significant (p = 0.007 and 0.005) than the corresponding differences in thiamine intake expressed as mg/1000 kcal (p = 0.04). Absolute daily thiamine requirement (1.22 mg for men, 1.03 mg for women) was more useful in predicting biochemical thiamine status than thiamine intake expressed as mg/1000 kcal. The withdrawal of thiamine fortification of processed cereals would have serious implications for public health.

A fluorimetric method for measurement of erythrocyte transketolase activity

A method for measuring erythrocyte transketolase activity (ETKA) is described that is precise, economical of reagents and capable of high throughput with partial or full automation. The transketolase-dependent transformation of ribose-5-phosphate, yielding glyceraldehyde-3-phosphate, is linked via 'indicator enzymes' to glycerol production and NADH consumption, the latter being followed fluorimetrically. Conditions under which ETKA and 'TPP Effect' are derived have been examined and optimised. Values are comparable with those obtained by other methods but a relatively narrow adult reference range for ETKA is observed. Data are presented for optimal preparation and storage of samples.

Studies on interactions of vitamin E with thiamine, niacin and vitamin B12

The effects of simultaneous administration of thiamine, niacin or vitamin B12 with vitamin E on plasma vitamin E levels were studied in 20 adult male volunteers belonging to the low socio-economic class. The effect of vitamin E on the nutritional status of pyridoxine, riboflavin and thiamine as judged by the erythrocyte enzymes, aspartate aminotransferase, glutathione reductase and transketolase, respectively was also studied. None of the members of the B-complex vitamins studied here had any effect on plasma vitamin E levels. This was in contrast to the observation made earlier that pyridoxine and riboflavin can reduce plasma vitamin E. There was a transient reduction in both the basal and stimulated activities of erythrocyte aspartate aminotransferase, the significance of which needs further investigation.

Erythrocyte transketolase activity in uremia

We performed a study concerning the activity of erythrocyte transketolase and thiamine metabolism in 73 uremic patients with or without neuropathy and 67 normal control subjects. Although the total vitamin B1 level in whole blood was high in the uremic patients, the transketolase activity in the hemolysate and the thiamine pyrophosphate effect on it were lower than those of normal subjects. The values of the transketolase activity of the two groups were statistically correlated with the levels of the thiamine pyrophosphate effect and the vitamin B1 content of the blood. Inhibition of transketolase activity was apparent in the uremic patients. However, this inhibition did not seem to be the only cause for the development of uremic neuropathy since no significant difference in these activities was observed among uremic patients with and without neuropathy. Moreover, a direct correlation could not be confirmed between transketolase activity and motor nerve conduction velocity.