Erythrocyte Transketolase Activity Research Articles

In thiamine deficiency, activation of erythrocyte transketolase by thiamine in vivo exceeds activation by cofactor in vitro

In 60 thiamine deficient patients, the mean erythrocyte transketolase activity after activation by thiamine diphosphate cofactor in vitro, representing the apparent sum of holoenzyme and apoenzyme activities, was 0.609 (SD 0.166) U/g Hb before thiamine therapy and rose to 0.772 (SD 0.152) U/g Hb immediately after the administration of thiamine to the patients. The difference between these values, 0.163 (SD 0.130) U/g, is the mean activity of transketolase protein which can be activated by thiamine in vivo but not by thiamine diphosphate in vitro. This difference correlated with low initial erythrocyte transketolase activity in these patients, but not with their alcohol intake, liver function or diagnoses.

Abnormalities of Peripheral Nerve Conduction in Relation to Thiamine Status in Alcoholic Patients

Thiamine status was evaluated using the erythrocyte transketolase activation assay in 20 alcoholic patients admitted on a voluntary basis to a Detoxification Unit. Electromyographic evaluation revealed significant reductions of motor and sensory conduction velocities in the alcoholic group. 38% of alcoholic patients showed significant erythrocyte transketolase activation deficits indicative of severe thiamine deficiency. In the case of peroneal nerve, reduced conduction velocities were negatively correlated with abnormal transketolase parameters. These findings are consistent with a contributory (but not exclusive) role of thiamine deficiency in the pathogenesis of alcoholic peripheral neuropathy. Deficiencies of other vitamins as well as direct neurotoxic effects of alcohol could also be involved in this phenomenon.

Bioavailability Assessment of the Lipophilic Benfotiamine as Compared to a Water-Soluble Thiamin Derivative

The bioequivalence of thiamin in 2 therapeutically used preparations was tested in 10 healthy young men. Thiamin was orally administered either as lipophilic benfotiamine or as water-soluble thiamin mononitrate. Biokinetic data, measured as area under the curve and maximal concentration in plasma and hemolysate after ingestion, demonstrated a significantly improved bioavailability from the lipophilic derivative despite an ingested dose of only 40% as compared with the water-soluble salt. A superior cellular efficacy of benfotiamine was also concluded from the short-term stimulation of the thiamin-dependent transketolase activity in erythrocytes.

Transketolase activities in human lymphocytes and granulocytes

Transketolase activities (TKA) were measured in human lymphocytes, granulocytes and erythrocytes by a NADH-dependent method. Lymphocyte and granulocyte TKA were 125 and 152 times greater, respectively, than erythrocyte. Xylulose-5-phosphate, at a final concentration of 3.6 mmol/L, was needed for optimal lymphocyte and granulocyte TKA, but had no apparent effect on erythrocyte TKA.

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 ≥ 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.

Thiamine deficiency in sheep exported live by sea

Three shipments of sheep being exported live by sea were examined to determine their thiamine status. Measurements were made of thiamine concentration in liver and ruminal contents, transketolase activity in erythrocytes and thiaminase activity in ruminal liquor. Sheep that died or were clinically ill and euthanased had significantly lower hepatic and ruminal thiamine concentrations than clinically healthy control sheep. A high proportion had thiamine concentrations comparable to those found in sheep that die with polioencephalomalacia. Thiamine concentrations decreased with increasing time that sheep were in pre-embarkation feedlots and on board ship. Destruction of thiamine in the rumen by thiaminase was not a significant factor. Erythrocyte transketolase activities indicated that many of the sheep that arrived in the Middle East without signs of clinical disease were also in a state of thiamine insufficiency.

Thiamine Status in Urban Adolescents

To evaluate thiamine status in an urban adolescent population, we performed two investigations. In Study I, we compared whole blood thiamine levels in 101 healthy adolescents from varied racial backgrounds with those that had been obtained previously in 146 healthy white adults from a different geographic locale. Blood thiamine values were significantly lower in the adolescents as a group, but the differences were entirely due to the lower levels in the black adolescents. To explore further these differences (Study II), we compared thiamine status in 34 adolescents with that of their parents using measures of both whole blood thiamine content and of erythrocyte transketolase activity. White adolescents had significantly higher total whole blood thiamine values than black adolescents, and white parents had significantly higher thiamine values than black parents by both total whole blood assay and level of transketolase activity. There were no differences in thiamine status between adolescents and parents of the same race. Racial composition is an important variable to consider in population surveys of thiamine status.

Vitamin supplementation of patients receiving haemodialysis.

In order to assess the necessity of vitamin supplementation for patients who are receiving haemodialysis, measurements of vitamin status were made, and both dietary and supplementary intakes were assessed, in 26 patients who were undergoing haemodialysis. Blood samples were collected from these patients before they underwent haemodialysis, after an overnight fast, for the measurement of plasma retinol, alpha-tocopherol and ascorbate levels. Serum and erythrocyte folate levels were measured also. Thiamin status was assessed by the effect of added thiamin pyrophosphate on erythrocyte transketolase activity and pyridoxine status was assessed by the effect of added pyridoxal-5'-phosphate on erythrocyte aminotransferase activity. All patients had elevated plasma retinol levels; 48% of patients had elevated plasma alpha-tocopherol levels; the plasma ascorbate level was low in 50% of patients but was elevated in 25% of patients; and plasma and erythrocyte folate levels were elevated in 76% and 91% of patients, respectively. Thiamin status was normal in all but one patient and the pyridoxine level appeared to be low in two other patients. Many patients had low dietary intakes of vitamin C, folate and vitamin B6. We conclude that supplements of vitamins A and E are not required and, when dietary intakes of water-soluble vitamins are marginal, these should be supplemented at a dose as near as possible to the recommended dietary intake.

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.

Riboflavin and thiamin status and birth outcome as a function of maternal aerobic exercise

Twenty-eight healthy pregnant women taking vitamin-mineral supplements served as controls or participated in a walking program from 22 to 30 wk gestation to determine the effects of aerobic exercise on maternal riboflavin and thiamin status and birth outcome. Aerobic capacity was evaluated by heart rate (HR) and relative oxygen consumption (RVO2) during submaximal treadmill walking. HR responses at 30 wk gestation were significantly lower for walking (n = 18) than nonwalking (n = 10) groups at 2 and 4 min of exercise. RVO2 for walkers decreased significantly from 22 to 30 wk at 2, 4, and 6 min. Riboflavin and thiamin status, determined by erythrocyte glutathione reductase and transketolase activity coefficients, was adequate for 86 and 96% of the subjects, respectively. Birth-outcome measurements were similar for all subjects. Participation in the walking program slightly improved aerobic capacity without affecting riboflavin or thiamin status or birth outcome in pregnant women taking vitamin-mineral supplements.

Thiamin Status of the Offspring of Diabetic Rats

Erythrocyte transketolase activity and thiamin pyrophosphate effect were examined in the offspring of streptozotocin-diabetic rats. Thiamin reserve was found to be significantly reduced in litters of untreated diabetic rats as compared to control and to insulin-treated diabetic rats. Supplementation of the untreated diabetic dams throughout pregnancy with oral thiamin was associated with a significantly improved thiamin status of the litters. We conclude that, due to enhanced fetal glucose turnover during diabetic gestation, a fetal thiamin deficiency state may evolve; this condition can be remedied with maternal thiamin supplementation.

CHANGES IN THE ACTIVATION OF RED BLOOD CELL TRANSKETOLASE OF ALCOHOLIC PATIENTS DURING TREATMENT

Erythrocyte transketolase activation by thiamin diphosphate has been studied in alcoholic patients on admission and after treatment, which included vitamin therapy. The high proportion of the patients who showed an abnormal activation of transketolase, not only by 0.3 mM thiamin diphosphate but also further activation by increasing the thiamin diphosphate to 3 mM, was reduced considerably after treatment. A few patients, however, still showed continuing abnormalities even after treatment. Further study of the enzyme activation in vitro confirmed the presence of an enzyme variant, abnormal both in the ease with which the thiamin diphosphate could be removed and in requiring a high concentration of thiamin diphosphate for activation. Since the modified transketolase activation test appears not only to monitor the effectiveness of thiamin therapy but also independently to warn of persisting enzyme abnormalities, it could prove to be of general use in alcohol detoxification units.

Comparison of Transketolase Activity and Thiamin Pyrophosphate Levels in Erythrocytes and Liver of Rainbow Trout (Salmo gairdneri) as Indicators of Thiamin Status

Yearling rainbow trout (Salmo gairdneri) were fed a purified diet with and without thiamin supplementation for 30 wk, at which time overt signs of thiamin deficiency appeared in the deficient group. Overt signs of thiamin deficiency were anorexia, darkening and ataxia. Death rapidly followed the development of overt thiamin deficiency. Transketolase activity and thiamin pyrophosphate levels were measured monthly in erythrocyte and liver samples. Significant differences in erythrocyte tranketolase activity between fish fed the thiamin-deficient and control diets were measured after 24 wk of feeding. No significant difference in liver transketolase activity was found between trout fed diets with or without thiamin supplementation. Thiamin pyrophosphate levels were significantly lower in erythrocytes and liver of fish fed the thiamin-deficient diet after 16 wk of feeding. Thiamin pyrophosphate levels in erythrocytes and liver were found to be a more sensitive indicator of thiamin status of rainbow trout than erythrocyte or liver transketolase activity.

Natural establishment of thiaminase activity in the alimentary tract of newborn lambs and effects on thiamine status and growth rates.

Thiaminase activity was detected in the faeces of lambs at 2 to 5 days of age. Levels of activity increased for 10 days and then declined over the next 3 to 4 weeks. Decreased erythrocyte transketolase activity indicated thiamine insufficiency in lambs with high thiaminase activity. Mean growth rates were 17% less in lambs with high thiaminase activity than in lambs with zero or low thiaminase activity. Bacillus thiaminolyticus was the only organism isolated which produced thiaminase. Treatment of newborn lambs with intramuscular injections of sulphadoxine did not prevent them from excreting thiaminase in their faeces. It is proposed that oral thiamine supplementation of lambs at 2 to 3 weeks of age may be the most appropriate prevention and treatment for subclinical thiamine deficiency of the cause described.

The activation of red blood cell transketolase in groups of patients especially at risk from thiamin deficiency.

Erythrocyte transketolase activation by thiamin diphosphate has been studied in elderly patients with moderate or severe chronic dementia, acute alcoholic admissions and chronic alcoholics with evidence of brain damage, mostly of the Wernicke-Korsakoff type. Significantly more patients in each group than controls showed abnormal activation of transketolase, not only by 0.3 mM thiamin diphosphate (TDP) but also in further activation by increase to 3 mM. This indicated the presence in a proportion of the alcoholic and the demented patients of an abnormal enzyme variant, similar to that previously found in vitro. The modified transketolase activation test may warn not only of marginal thiamin deficiency but also independently, of susceptibility to brain damage in patients at risk.

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.

Increased axonal transport in peripheral nerves of thiamine-deficient rats

Thiamine deficiency has been implicated as a signifccant contributing factor in the development of peripheral neuropathies in chronic alcoholic patients. We hypothezized that thiamine deficiency may lead to an alteration in axonal transport because it has been associated with “dying-back” neuropathies and its importance in neural tissue has been demonstrated with antimetabolites. To test this possibility rats were made thiamine-deficient by feeding a liquid diet lacking thiamine. Control rats were pair-fed a complete liquid diet. The deficiency developed after 3 to 4 weeks and was evidenced by anorexia, weight-loss, and a significant increase in the erythrocyte transketolase activity ratio. Also, the sural nerve conduction velocity was found to be significantly reduced in these animals (18.74 m/s) relative to that of pair-fed control rats (31.99 m/s). In vitro transport experiments utilizing dorsal root ganglia-sciatic nerve preparations indicated that twice as much [ 35S]methionine-labeled protein accumulated at a ligation by fast transport in the thiamine-deficient rats as in nerves of their pair-fed controls. There was no difference in the level of incorporation of radioactive precursor into the dorsal root ganglia. The increase in transport suggests that thiamine deficiency per se has no detrimental effects on the transport machinery and process, but may indicate extensive regenerative activity in the distal portions of these axons.

Blood thiamine levels in outpatients with diabetes mellitus.

In 46 diabetic outpatients consisting of 20 males and 26 females not given thiamine treatment, the blood thiamine level was 46.9 +/- 28.5 ng/ml (mean +/- SD) and only 23.9% of all cases had a value of more than the normal lower limit (50 ng/ml). Erythrocyte transketolase activity was 443.8 +/- 107.7 micrograms/ml/h and only 20.9% had a value of ore than the normal lower limit (50 micrograms/ml/h), and the erythrocyte TPP effect was 16.6 +/- 13.2%. Moreover, there was a significant positive correlation (r = 0.97) between the blood thiamine level and erythrocyte transketolase activity, and a significant inverse correlation (r = -0.525, r = -0.576) between blood thiamine level and/or erythrocyte transketolase activity and the erythrocyte TPP effect. In 24 diabetic outpatients consisting of 14 males and 10 females given thiamine treatment, the blood thiamine level was 96.5 +/- 44.5 ng/ml/h excluding one case (621.7 ng/ml), and it was higher than the normal lower limit in 83% of all cases. Erythrocyte transketolase activity was 513.9 +/- 133.4 micrograms/ml/h and it was higher than the normal lower limit in 58.3%. Erythrocyte TPP effect was 5.84 +/- 8.39%. There was also a significant positive correlation (r = 0.663) between blood thiamine level and erythrocyte transketolase activity, and a significant inverse correlation (r = 0.0668, r = 0.834) between blood thiamine level and/or erythrocyte transketolase activity and erythrocyte TPP effect. Blood thiamine level and erythrocyte transketolase activity were significantly higher in diabetic outpatients given thiamine treatment than in diabetic outpatients not given thiamine treatment, while the erythrocyte TPP effect was significantly lower in diabetic outpatients given thiamine treatment than in diabetic outpatients not given thiamine treatment. There was no direct relationship between the lowered response of patellar tendon reflex and the biochemical status of thiamine. From the above findings it was concluded that diabetic outpatients tend to have a low blood thiamine level, with low erythrocyte transketolase activity and high erythrocyte TPP effect, and showed marginal thiamine deficiency.

The haematic thiamine level in the course of alcoholic neuropathy.

The specific roles of ethanol and malnutrition in the pathogenesis of neurological disorders of chronic alcoholism remain unclear. We measured plasmatic thiamine levels and erythrocyte transketolase activity in 30 alcoholics with peripheral neuropathy and in 4 with a Wernicke-Korsakoff (W-K) syndrome. Thiamine levels in the first group were comparable to those of normal subjects while a significantly lower concentration was found in W-K syndrome. Transketolase activity was lower for both groups in comparison with normal subjects. We suggest that a defect in thiamine utilization is involved in peripheral neuropathy of alcoholics, rather than a lack of thiamine itself.

The relationship between blood thiamine levels and dietary thiamine content in diabetic outpatients and healthy subjects.

Forty-six diabetic outpatients consumed (1,533 +/- 308 kcal (mean +/- SD) per day, 205 +/- 42 g of carbohydrates, 73 +/- 18 g of protein, 49 +/- 18 g of fat, and 0.05 +/- 0.34 mg of thiamine. No significant correlation was found in 46 diabetic between blood thiamine level and the intake of dietary energy, carbohydrate or thiamine. In 13 healthy subjects given prepared diets, a significant correlation was found between blood thiamine level and dietary thiamine content, thiamine content per 1,000 kcal, and 24-h urinary thiamine amount divided by urinary creatinine. When 9 healthy subjects (6 males, 3 females) consumed 1,600 kcal with 0.6 mg of thiamine for two days, their blood thiamine level was 47 +/- 29.1 ng/ml before and 29.7 +/- 7.1 ng/ml after eating the diet, showing low blood thiamine levels due to the low content of dietary thiamine. When 5 or 6 healthy female subjects consumed 1,400 kcal with 1.6 mg of thiamine or 2,000 kcal with 1.9 mg of thiamine for two days, their blood thiamine level was 45.3 +/- 4.8 ng/ml or 57.7 +/- 8.4 ng/ml before and 51.5 +/- 11.7 ng/ml or 56.4 +/- 11.7 ng/ml after eating the diets, respectively. In both diabetic outpatients and healthy subjects, a significant positive correlation was found between blood thiamine levels and dietary thiamine concentrations per 1,000 kcal, and a significant positive correlation was also found between erythrocyte transketolase activity and dietary thiamine content.(ABSTRACT TRUNCATED AT 250 WORDS)