Transketolase Activity Research Articles

Faecal thiaminase, plasma lactate and pyruvate concentrations and erythrocyte transketolase activity changes in apparently normal replacement ewes after the initiation to the pasture

A study was made to investigate faecal thiaminase and the thiamine-related biochemical changes in apparently normal replacement ewes with a feed change, after the initiation without adaptation to the new pasture. Twenty-four female ewes were divided into two groups. Group A was managed in a system based on pasture and was compared with group B system based on a diet of concentrate and straw until moving to pasture 9 weeks after. Blood samples for lactate, pyruvate and erythrocyte transketolase activity determinations and faeces for thiaminase estimation were evaluated chronologically. At the end of a 126 days experimental period, live weights of groups were similar. We confirmed that clinically normal sheep may have thiaminase activity in the faeces and concluded that the thiaminase release increased during the diet changes, from concentrate to pasture, and that their continued excretion could develop some degree of thiamine deficiency.

The Effect of Thiamine Injection on Upstream Migration, Survival, and Thiamine Status of Putative Thiamine‐Deficient Coho Salmon

AbstractA diet containing a high proportion of alewives Alosa pseudoharengus results in a thiamine deficiency that has been associated with high larval salmonid mortality, known as early mortality syndrome (EMS), but relatively little is known about the effects of the deficiency on adults. Using thiamine injection (50 mg thiamine/kg body weight) of ascending adult female coho salmon Oncorhynchus kisutch on the Platte River, Michigan, we investigated the effects of thiamine supplementation on migration, adult survival, and thiamine status. The thiamine concentrations of eggs, muscle (red and white), spleen, kidney (head and trunk), and liver and the transketolase activity of the liver, head kidney, and trunk kidney of fish injected with thiamine dissolved in physiological saline (PST) or physiological saline only (PS) were compared with those of uninjected fish. The injection did not affect the number of fish making the 15‐km upstream migration to a collection weir but did affect survival once fish reached the upstream weir, where survival of PST‐injected fish was almost twice that of controls. The egg and liver thiamine concentrations in PS fish sampled after their upstream migration were significantly lower than those of uninjected fish collected at the downstream weir, but the white muscle thiamine concentration did not differ between the two groups. At the upper weir, thiamine levels in the liver, spleen, head kidney, and trunk kidney of PS fish were indistinguishable from those of uninjected fish (called “wigglers”) suffering from a severe deficiency and exhibiting reduced equilibrium, a stage that precedes total loss of equilibrium and death. For PST fish collected at the upstream weir, total thiamine levels in all tissues were significantly elevated over those of PS fish. Based on the limited number of tissues examined, thiamine status was indicated better by tissue thiamine concentration than by transketolase activity. The adult injection method we used appears to be a more effective means of increasing egg thiamine levels than immersion of eggs in a thiamine solution.

Outbreak of Life-Threatening Thiamine Deficiency in Infants in Israel Caused by a Defective Soy-Based Formula

Objective. Between October and No- vember 2003, several infants with encephalopathy were hospitalized in pediatric intensive care units in Israel. Two died of cardiomyopathy. Analysis of the accumu- lated data showed that all had been fed the same brand of soy-based formula (Remedia Super Soya 1), specifi- cally manufactured for the Israeli market. The source was identified on November 6, 2003, when a 5.5-month-old infant was admitted to Sourasky Medical Center with upbeat nystagmus, ophthalmoplegia, and vomiting. Wer- nicke's encephalopathy was suspected, and treatment with supplementary thiamine was started. His condition improved within hours. Detailed history revealed that the infant was being fed the same formula, raising sus- picions that it was deficient in thiamine. The formula was tested by the Israeli public health authorities, and the thiamine level was found to be undetectable ( 25% indicates severe deficiency. Blood lactate levels (normal: 0.5-2 mmol/L) were measured in 6 infants, cerebrospinal fluid lactate in 2 (normal: 0.5-2 mmol/L), and blood pyruvate in 4 (nor- mal: 0.03-0.08 mmol/L). The diagnostic criteria for thia- mine deficiency were abnormal transketolase activity and/or unexplained lactic acidosis. Treatment consisted of intramuscular thiamine 50 mg/day for 14 days com- bined with a switch to another infant formula. Results. Early symptoms were nonspecific and in- cluded mainly vomiting (n 8), lethargy (n 7), irrita- bility (n 5), abdominal distension (n 4), diarrhea (n 4), respiratory symptoms (n 4), developmental delay (n 3), and failure to thrive (n 2). Infection was found in all cases. Six infants were admitted with fever. One pa- tient had clinical dysentery and group C Salmonella sep- sis; the others had mild infection: acute gastroenteritis (n 2); upper respiratory infection (n 2); and broncho- pneumonia, acute bronchitis, and viral infection (n 1 each). Two infants were treated with antibiotics. Three infants had neurologic symptoms of ophthalmoplegia with bilateral abduction deficit with or without upbeat nystagmus. All 3 had blood lactic acidosis, and 2 had high cerebrospinal fluid lactate levels. Patient 1, our in- dex case, was hospitalized for upbeat nystagmus and ophthalmoplegia, in addition to daily vomiting episodes since 4 months of age and weight loss of 0.5 kg. Findings on brain computed tomography were normal. Blood lac- tate levels were high, and TPPE was 37.8%. Brain mag- netic resonance imaging (MRI) revealed no abnormali- ties. Patient 2, who presented at 5 months with lethargy, vomiting, grunting, and abdominal tenderness, was found to have intussusception on abdominal ultrasound and underwent 2 attempts at reduction with air enema several hours apart. However, the lethargy failed to re- solve and ophthalmoplegia appeared the next day, lead- ing to suspicions of Wernicke's encephalopathy. Labora- tory tests showed severe thiamine deficiency (TPPE 31.2%). In patients 1 and 2, treatment led to complete resolution of symptoms. The third infant, a 5-month-old girl, was admitted on October 10, 2003, well before the outbreak was recognized, with vomiting, fever, and oph- thalmoplegia. Her condition deteriorated to seizures, ap- nea, and coma. Brain MRI showed a bilateral symmetri- cal hyperintense signal in the basal ganglia, mamillary bodies, and periaqueductal gray matter. Suspecting a metabolic disease, vitamins were added to the intrave- nous solution, including thiamine 250 mg twice a day. Clinical improvement was noted 1 day later. TPPE assay performed after treatment with thiamine was started was still abnormal (17.6%). Her formula was substituted after 4 weeks, after the announcement about the thiamine deficiency. Although the MRI findings improved 5 weeks later, the infant had sequelae of ophthalmoplegia

Effects of Chloramphenicol on Photosynthesis, Protein Profiles and Transketolase Activity under Extremely High CO2 Concentration in an Extremely-high-CO2-tolerant Green Microalga, Chlorococcum littorale

An extremely-high-CO2-tolerant alga, Chlorococcum littorale, showed high quantum efficiency of PSII (PhiII) in the light at 40% CO2, as well as at 5% CO2. However, PhiII decreased greatly when chloramphenicol (CAP) was added at 40% CO2, while no such decrease was observed at 5% CO2. Cycloheximide showed no effect on PhiII at either 5% or 40% CO2. The amount of a 76 kDa polypeptide (p76) on SDS-PAGE decreased markedly in the presence of CAP at 40% CO2 but not at 5% CO2. A partial amino acid sequence of p76 was 71-100% identical (10-14 identical residues out of 14 amino acids determined) to those of transketolases (TKLs) reported in higher plants and a cyanobacterium. In agreement with these observations, the TKL activity in C. littorale was decreased by CAP at 40% CO2, but not at 5% CO2. The transient decrease in TKL activity caused by CAP under 40% CO2 was well correlated with that in PhiII. These results indicate that the addition of CAP directly or indirectly influences the stability of TKL in C. littorale at 40% CO2, but not at 5% CO2, and that photosynthetic activity was reduced by a decrease in TKL activity.

High-dose thiamine therapy counters dyslipidaemia in streptozotocin-induced diabetic rats

Cardiovascular disease in diabetes is linked to increased risk of atherosclerosis, increased levels of triglyceride-rich lipoproteins and enhanced hepatic lipogenesis. The hepatic hexosamine pathway has been implicated in signalling for de novo lipogenesis by the liver. In this study, we assessed if decrease of flux through the hexosamine pathway induced by high-dose thiamine therapy counters diabetic dyslipidaemia. The model of diabetes used was the streptozotocin-induced diabetic rat with maintenance insulin therapy. Normal control and diabetic rats were studied for 24 weeks with and without oral high-dose therapy (7 and 70 mg/kg) with thiamine and benfotiamine. Plasma total cholesterol, HDL cholesterol and triglycerides were determined at 6-week intervals and hepatic metabolites and transketolase activity after death of the rats at 24 weeks. We found that thiamine therapy (70 mg/kg) prevented diabetes-induced increases in plasma cholesterol and triglycerides in diabetic rats but did not reverse the diabetes-induced decrease of HDL. This was achieved by prevention of thiamine depletion and decreased transketolase activity in the liver of diabetic rats. There was a concomitant decrease in hepatic UDP-N-acetylglucosamine and fatty acid synthase activity. Thiamine also normalised food intake of diabetic rats. A lower dose of thiamine (7 mg/kg) and the thiamine monophosphate prodrug benfotiamine (7 and 70 mg/kg) were ineffective. High-dose thiamine therapy prevented diabetic dyslipidaemia in experimental diabetes probably by suppression of food intake and hexosamine pathway signalling but other factors may also be involved. Benfotiamine was ineffective.

Metabolic Profile of Imatinib Resistance in CML Cells.

We previously reported that imatinib decreased glucose uptake in the BCR-ABL+ cells in a dose- and timedependent fashion by switching from glycolysis to Krebs cycle metabolism and improving the cell energy state. The goal of this study was to evaluate metabolic aspects of imatinib resistance in paired imatinib-sensitive and resistant clones of two CML cell lines, K562 and LAMA84. LAMA84-r cells are resistant due to BCR-ABL and P-glycoprotein overexpression, the mechanism of resistancy in K562-r cells is still unknown (may be implicating other tyrosine kinases). Resistant clones were grown in imatinib containing medium (K562-r: 5μM; LAMA84-r: 1μM). Sensitive cells were incubated with 1μM imatinib for 24h. [1-13C] glucose was added to all cells for the last 4h. Magnetic resonance spectroscopy (MRS) was performed on cell extracts to evaluate glucose metabolism (1H, 13C) and energy state (31P). In imatinib treated sensitive cells mitochondrial glucose metabolism was slightly improved (C4-glutamate signal increased to 137% and 114% vs. untreated K562-s and LAMA84-s). No significant changes in glycolysis rate or glucose uptake were seen. In resistant K562-r cells mitochondrial activity was significantly lower (C4-glutamate decreased to 47%, p<0.001) with decreased citrate (p<0.05) and pyruvate (p<0.05) concentrations and decreased NTP/NDP-ratios (45%, vs. K562-s p<0.05). The de novo13C-lactate production decreased in K562-r cells (46%, p<0.05), but increased in the media (168%, p<0.05, all compared to K562-s), in order to keep the intracellular pH stable. K562-r showed a significant increase in glucose uptake vs. sensitive cells (17.2 compared to 13.6 mmol/l/g, p<0.05). Even though LAMA84-r showed the same metabolic pattern, the changes in this cell line were not statistically significant. The pronounced decrease in phosphodiester concentrations, markers for membrane degradation, clearly distinguished resistant from the sensitive cells (21%, p<0.005 (K562) and 55%, p<0.05 (LAMA84)). In LAMA84-r cells concentration of phosphocholine, a marker for membrane biosynthesis, was increased to 293% of LAMA84-s (p<0.001). Preliminary GC-MS studies on K562-r cells showed that imatinib is unable to inhibit non-oxidative nucleic acid ribose and deoxyribose synthesis. A significantly increased activity of transketolase (p<0.05) the enzyme responsible for non-oxidative ribose synthesis in the pentose cycle, may be a putative mechanism for this salvage reaction. In summary, despite their different mechanisms of resistance, K562-r and LAMA84-r cells showed a metabolic profile of the resistant phenotype with same directional changes compared to their sensitive counterparts. Mitochondrial metabolism and energy state were decreased significantly in K562-r (p<0.05), while non-oxidative metabolism was not affected. These changes were present but non-significant in LAMA84-r. We therefore conclude that the failure of imatinib in inhibiting cytosolic glycolysis and improving mitochondrial metabolism, as well as in restricting the use of glucose carbons for de novo nucleic acid synthesis could serve as a metabolic signature of imatinib resistance. This can be readily measured by MRS and may be used as a clinical endpoint for early detection of treatment failure.

Vitamin Status of High Altitude (3660 m) Acclimatized Human Subjects During Consumption of Tinned Rations

To find out the nutritional status of sea-level residents acclimated to an altitude of 3660 m with respect to vitamin and nutrient requirements while consuming fresh and tinned rations. Initially, high altitude acclimatized human subjects (n = 40) were evaluated for their general nutritional status along with energy intake and expenditure and physical fitness score while they were on fresh rations. Thereafter, subjects were fed tinned rations in two groups of 20 each. Of the two groups, one group had vitamin supplementation and the other was without any vitamin supplementation for 30 days. Thereafter, all the variables were studied once again. Daily total energy intake when subjects consumed fresh and tinned rations was 19.087 +/- 0.347 MJ and 19.417 +/- 0.342 MJ, respectively, whereas the total energy expenditure was 15.705 +/- 1.054 MJ per day for both the groups. After consuming tinned rations for 30 days, the placebo group showed a significant (P < .01) decrease in levels of plasma vitamin A and erythrocyte trans-ketolase activity (a marker of thiamin status) in comparison to the status when subjects were on fresh rations. However, levels of these variables were well within acceptable range. Subjects maintained their body weights and physical fitness scores. No clinical deficiency was seen after consuming tinned rations for 30 days. The study indicates that no additional vitamin supplementation is required at high altitude after acclimatization when consuming fresh rations and at least for 30 days when consuming tinned rations.

A hitherto unknown transketolase—catalyzed reaction

Yeast transketolase, in addition to catalyzing the transferase reaction through utilization of two substrates—the donor substrate (ketose) and the acceptor substrate (aldose)—is also able to catalyze a one-substrate reaction with only aldose (glycolaldehyde) as substrate. The interaction of glycolaldehyde with holotransketolase results in formation of the transketolase reaction intermediate, dihydroxyethyl-thiamin diphosphate. Then the glycolaldehyde residue is transferred from dihydroxyethyl-thiamin diphosphate to free glycolaldehyde. As a result, the one-substrate transketolase reaction product, erythrulose, is formed. The specific activity of transketolase was found to be 0.23 U/mg and the apparent K m for glycolaldehyde was estimated as 140 mM.

Toxicity of glyoxals--role of oxidative stress, metabolic detoxification and thiamine deficiency.

Glyoxals are reactive alpha-oxoaldehydes that are formed endogenously from sugars, the levels of which are increased in various pathological conditions associated with hyperglycaemia and thiamine deficiency. However, the molecular cytotoxic mechanisms of glyoxal are not known. Results presented here and in the other studies cited provide a glimpse into the cytotoxicity mechanisms involved and their pathological implications. We found that glyoxal (10 microM) markedly increased the susceptibility of hepatocyte glutathione (GSH) to oxidation by hydrogen peroxide (H(2)O(2)) and markedly increased cytotoxicity by compromising the cellular antioxidant enzyme system. At higher concentrations, glyoxal was cytotoxic towards hepatocytes, which can be attributed to GSH depletion, oxidative stress and mitochondrial toxicity. Aminoguanidine or penicillamine protected the hepatocytes. Glyoxal cytotoxicity was prevented by increasing glyoxal metabolism with thiamine or NAD(P)H generators, and was increased in GSH- or thiamine-deficient hepatocytes. It was also found that feeding rats reduced thiamine levels in a diet high in simple sugars increased the number of aberrant crypt foci/colon in the absence of clinical evidence of beriberi. This was associated with decreased plasma thiamine and low erythrocyte transketolase activity. Western diets, which are frequently poor in thiamine and high in sugars, could result in increased levels of endogenous glyoxals, which in turn may lead to a predisposition to AGE (advanced glycation end-product)-related pathologies and neoplastic conditions.

Thiamine blood levels and high doses of diuretics in patients with moderate to severe congestive heart failure symptoms

Background: The no pharmacological management of congestive heart failure (CHF) has been understudied. Thiamine deficiency causes high-output CHF and restoration of its body stores is associated with complete reversal. Therefore we assessed thiamine blood levels (pmol/ml) and its association with the use of high-doses of furosemide. Methods: In a cohort of 22 patients (pts) with moderate to severe CHF (NYHA III/IV) using the erythrocyte transketolase activity thiamine levels were determined. The pts were then divided according to daily furosemide doses (group I<120 mg and group II≥120 mg).

The effects of spironolactone on thiamine blood levels in patients with congestive heart failure on chronic high doses of loop-diuretics

Background: The nonpharmacological management of congestive heart failure (CHF) has been understudied. The importance of micronutrients such as vitamin B1 (thiamine) has long been known since its deficiency is associated with the development of high-output CHF. In the present study, we studied the relationship between adding to ACE inhibition further aldosterone suppression with spironolactone and thiamine blood levels (pmol/ml). Methods: A total of 22 patients (pts) with moderate to severe CHF symptoms (NYHA II/IV) were divided in two groups according to the use of spironolactone [group I-spironolactone 25 mg/qd (n 11) and group II no spironolactone (n 11)]. Thiamine blood levels were determined using the erythrocyte transketolase activity. The groups were compared regarding food intake, furosemide doses, demographics and thiamine blood levels (mean SD) using a student’s t test. Chi-square and Kruskal-Wallis tests were used to assess variables associated with thiamine levels. Results: Group I and II were similar regarding food intake, daily furosemide doses (110.9 30.2 and 105.5 26.9 mg, respectively; p 0.05), demographics (etiology of CHF, age, hypertension, diabetes, smoking, alcohol abuse, dyslipidemia and adjuvant drug CHF treatment). Patients in group I showed significantly higher thiamine blood levels when compared to patients in group II (277.2 89.8 and 154.7 35.7 pmol/ml, respectively) (p 0.001). None of the dependent variables cited above were associated with thiamine blood levels. Conclusion: In a cohort of ambulatory CHF patients (NYHAII/IV) on high doses of loop diuretics the use of spironolactone is associated with higher thiamine blood levels. The significance of this finding remains to be established by future studies with prospective design and larger sample sizes. Safety and Efficacy of Intermittent, Short-Term, Outpatient Nesiritide Infusions for the Treatment of Decompensated Heart Failure Ghaith M. Mulki, Carol Pisano, Gallagher Colleen, Cianci Pamela, Muhyaldeen Dia, Marc A. Silver1—Department of Medicine and the Heart Failure Institute, Advocate Christ Medical Center, Oak Lawn, IL

Vitamin B1 blocks damage caused by hyperglycemia.

Diabetes accelerates the aging process and leads to complications that include blindness, renal failure, nerve damage, stroke, and cardiovascular disease. It has been hypothesized that high plasma glucose concentrations are responsible for increased mitochondrial free radical production and subsequent inactivation of glyceraldehyde phosphate dehydrogenase (GAPDH) in vascular endothelial cells and other cells implicated in these complications. As a result of the decreased ability of GAPDH to process upstream metabolites, three pathways of metabolic damage are activated, which include the advanced glycation end-product formation pathway, the protein kinase C pathway, and the hexosamine pathway. All three pathways have been implicated in abnormal cell signaling in diabetes. A group of German and U.S. scientists has now found that treating diabetic rats with high doses of benfotiamine, a lipid-soluble form of vitamin B1, can prevent diabetic retinopathy and all three forms of metabolic damage by stimulating transketolase activity and thus diverting excess metabolites toward the pentose pathway. Although vitamin B1 is available over the counter, the researchers at this time do not advocate self-treatment without further clinical data.

Biochemical changes in apparently normal sheep from flocks affected by polioencephalomalacia.

Blood samples were obtained for determination of the activities of lactate, pyruvate and erythrocyte transketolase, and faeces as samples for estimation of thiaminase, from 190 apparently healthy sheep from 19 flocks in which at least one animal had been diagnosed with polioencephalomalacia (PEM), from 59 control animals and from 7 affected by PEM. Feed and pasture grass samples were collected for thiaminase analysis and thiaminase was assayed in ryegrass and fescue. Decreased erythrocyte transketolase activity, accompanied by a corresponding rise in the thiamin pyrophosphate effect, and estimation of the thiaminase content in faeces, may be useful diagnostic procedures by which to identify periods of greater risk, during which animals could develop PEM. The changes in the diet probably acted as a primary factor for microbial production of thiaminases in replacement ewes. In these, the prevalence was higher in the spring months.

A fluorogenic assay for transketolase from Saccharomyces cerevisiae

In order to generate transketolase (TK) with new or improved properties by in vitro evolution, an efficient screening system is an absolute prerequisite for identifying the evolved enzyme variants. We report here an assay allowing us to detect wild type TK activity in vitro by fluorescence. We examined the use of the fluorogenic compound 1 as donor substrate of TK, which is itself non fluorescent but releases a fluorescent product: umbelliferone.

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.

Paraquat and menadione exposure of rainbow trout ( Oncorhynchus mykiss)—Studies of effects on the pentose-phosphate shunt and thiamine levels in liver and kidney

Possible xenobiotic interactions with thiamine were studied in salmonid fish, by repeatedly injecting two model substances, paraquat and menadione, into juvenile rainbow trout ( Oncorhynchus mykiss). These two substances were chosen because of their well-known ability to redox-cycle and cause depletion of NADPH in several biological systems. Depletion of NADPH increases metabolism through the pentose-phosphate shunt and may thereby increase the need for thiamine diphosphate by heightened transketolase activity. A special food was produced with lower thiamine content than commercial food, usually enriched with thiamine, which could mask an effect on the thiamine level. After 9 weeks of exposure, glucose-6-phosphate dehydrogenase, transketolase, glutathione reductase and ethoxyresorufin O-deethylase were analysed in liver and kidney cellular sub-fractions as well as analysis of total thiamine concentrations in liver, kidney and muscle. The results showed that paraquat caused a large increase in hepatic glutathione reductase activity and induced hepatic glucose-6-phosphate dehydrogenase activity, i.e., the rate-limiting enzyme in the oxidative part of the pentose-phosphate shunt. Despite this paraquat exposure did not affect transketolase activity and total thiamine concentration.

Thiamin, selenium, and copper levels in patients with idiopathic dilated cardiomyopathy taking diuretics.

To analyze the association of thiamin, selenium, and copper serum levels with cardiac function in patients with idiopathic dilated cardiomyopathy using diuretics, and also to compare them with levels in control patients with no evidence of disease. The study comprised 30 patients with heart disease and 30 healthy control individuals. Thiamin was analyzed by measuring the activity of erythrocytic transketolase and the effect of thiamin pyrophosphate. Selenium and copper serum levels were measured by hydride generation and flame atomic absorption spectrophotometry, respectively. Thiamin deficiency was observed in 10% of the control individuals and in 33% of the patients with heart disease (p=0.02). The mean selenium and copper serum levels in control individuals and patients with heart disease were, respectively, 73.2+/-9.9 microg/L (56.5 to 94.5 microg/L) and 72.3+/-14.3 microg/L (35.5 to 94 microg/L) (p=0.77); 1.1+/-0.4 mg/L (0.6 to 1.8 mg/L) and 1.2+/- 0.4 mg/L (0.6 to 2.2 mg/L) (p=0.27). No association between the levels of these nutrients and cardiac function was observed. Thiamin deficiency was significantly more frequent in patients with heart disease. No significant difference was observed between the mean selenium and copper serum levels in control individuals and in patients with heart disease. The results suggest possible benefits with thiamin replacement in patients taking diuretics.

Cerebrospinal fluid levels of thiamine in patients with Alzheimer's disease.

Thiamine is an essential cofactor for several important enzymes involved in brain oxidative metabolism, such as the alpha-ketoglutarate dehydrogenase complex (KGDHC), pyruvate-dehydrogenase complex (PDHC), and transketolase. Some investigators reported decreased thiamine-diphosphate levels and decreased activities of KGDHC, pyruvate-dehydrogenase complex and transketolase in the brain tissue of Alzheimer's disease (AD) patients. We measured cerebrospinal (CSF) levels of thiamine-diphosphate, thiamine-monophosphate, free thiamine, and total thiamine, using ion-pair reversed phase high performance liquid chromatography, in 33 patients with sporadic AD and 32 matched controls. The mean CSF levels of thiamine-derivatives did not differ significantly from those of controls, while the mean plasma levels of thiamine-diphosphate, free and total thiamine were significantly lower in the AD-patient group. CSF and plasma thiamine levels were not correlated with age, age at onset, duration of the disease, and scores of the MiniMental State Examination, with the exception of plasma thiamine-diphosphate with MiniMental State Examination (r = 0.41, p < 0.05) in the AD-patients group. CSF and plasma values did not predict dementia progression, assessed with the MiniMental State Examination scores. These results suggest that CSF thiamine levels are not related with the risk for and the progression of AD.

Physiological, biochemical and morphological studies of Baltic salmon yolk-sac fry with an experimental thiamine deficiency: relations to the M74 syndrome

Sea-run Baltic salmon ( Salmo salar) populations are suffering from the M74 syndrome, a reproduction disorder affecting both broodfish and their progeny. The syndrome is usually manifested during the middle part of the yolk-sac fry stage and has been shown to be associated with a thiamine (vitamin B 1) deficiency. Development of the disease is reversible by thiamine treatments of broodfish or progeny. This study aimed at investigating the ability of the thiamine antagonist pyrithiamine, administered by microinjections 3 days after hatch, to cause M74-like signs i.e. typical clinical symptoms, high mortality rates and histopathological changes. Furthermore, the effects of pyrithiamine on hepatic activities of the thiamine-dependent enzyme transketolase (TK), the glucose-6-phosphate dehydrogenase (G6PDH) and the cytochrome P4501A (CYP1A) were evaluated. Six family groups with differing thiamine status were sampled on three occasions during the yolk-sac fry stage. All pyrithiamine exposed groups, with the exception of the one with the highest thiamine concentration, showed M74-like symptoms and suffered from high mortality. Enzyme activities were not different in pyrithiamine groups as compared with controls. However, the TK-activities were strongly associated with the thiamine concentrations. The G6PDH-activity demonstrated small variations with the highest activities in the M74-groups. The [TK]/[G6PDH]-ratios were considerably lower in the M74-groups than in the healthy controls, indicating an imbalance between the oxidative and the non-oxidative part of the pentose–phosphate shunt due to a deficit in thiamine. The pyrithiamine-injections induced several M74-like symptoms including incoordination, lethargy, whitened liver and yolk-sac precipitates. They also caused high mortality rates, in addition to lowered glycogen levels and increased prevalence of necrotic brain cells. Moreover, the study demonstrates that the TK, G6PDH and CYP1A-activities are associated with the thiamine content.

Effects of furazolidone, PCB77, PCB126, Aroclor 1248, paraquat and p, p′-DDE on transketolase activity in embryonal chicken brain

The effect of in ovo exposure to PCBs, DDE and paraquat on transketolase activity was measured in 19-day-old chicken embryos. Furazolidone was used as a positive control for decreased activity of the enzyme. The potency of contaminants to interact with transketolase was also tested in an in vitro system, using control brain 7000× g supernatants containing the enzyme. No effects were found on transketolase activity after in ovo or in vitro exposure to PCB126, Aroclor, DDE or paraquat. PCB77 decreased transketolase activity in vitro, but only at concentrations that, extrapolated to in ovo exposure, would be lethal to the embryo. Furazolidone decreased transketolase activity both in ovo and in vitro. For this contaminant, thiamine residues were analysed in the yolk sacs, but no differences were found between exposed and non-exposed eggs. Transketolase is dependent on thiamine pyrophosphate as a cofactor, and therefore, the decreased enzyme activity could be the result of an interaction between furazolidone and thiamine metabolism. Since thiamine residues were not affected by furazolidone and transketolase inhibition in vitro was similar to the inhibition after in ovo exposure, it was concluded that furazolidone interacted with transketolase on the enzymatic level rather than by a depletion of thiamine.