Abnormality of a thiamine-requiring enzyme in patients with Wernicke-Korsakoff syndrome

Exploring the impact of age, and body condition score on erythrocytic B1-Dependent transketolase activity in cats: A comprehensive analysis of thiamine status

One of the key factors influencing aging and morbidity is the overall antioxidant status and regenerative capacity. In examining contributors to the antioxidant status, we analyzed the thiamine status in felines and the influence of age, gender, and body condition score. We measured erythrocytic B1-dependent specific transketolase (STKT) activity, an enzyme in the pentose phosphate pathway, in a group of 60 sexually intact, healthy, and specific pathogen-free felines (44 females, 16 males, aged 1-17 years) with thiamine diphosphate (TDP; 0.3 and 3 mM) and without it. Only two parameters (STKT activity with and without 0.3 mM TDP) decreased with age. After adjusting for age, statistical thresholds were established using these and other age-independent parameters, identifying 15 felines with subclinical thiamine deficiency. The red blood cell proteomics analysis revealed that the pentose phosphate shunt, glycolysis, and oxidative stress response were the most affected pathways in deficient felines, confirming the above diagnosis. Age emerged as the primary factor associated with thiamine deficiency, supported by the enrichment of neurodegenerative diseases with a proteotoxicity component; five young-adult felines showed marginal or acute B1 deficiency, and six were adult-mature with a more chronic deficiency, possibly linked to cognitive decline, all with an underweight to ideal body condition scores. Only three senior-adult felines were deficient and overweight-obese. Detecting thiamine deficiency emphasizes the need for more accurate reference values, the establishment of advanced preventive or therapeutic measures to enhance the well-being of aging companion animals, and potential extensions to human health, particularly concerning cognitive function.

Pharmacological Doses of Thiamine Benefit Patients with the Charcot-Marie-Tooth Neuropathy by Changing Thiamine Diphosphate Levels and Affecting Regulation of Thiamine-Dependent Enzymes

Charcot-Marie-Tooth (CMT) neuropathy is a polygenic disorder of peripheral nerves with no effective cure. Thiamine (vitamin B1) is a neurotropic compound that improves neuropathies. Our pilot study characterizes therapeutic potential of daily oral administration of thiamine (100 mg) in CMT neuropathy and its molecular mechanisms. The patient hand grip strength was determined before and after thiamine administration along with the blood levels of the thiamine coenzyme form (thiamine diphosphate, ThDP), activities of endogenous holo-transketolase (without ThDP in the assay medium) and total transketolase (with ThDP in the assay medium), and transketolase activation by ThDP [1 - (holo-transketolase/total transketolase),%], corresponding to the fraction of ThDP-free apo-transketolase. Single cases of administration of sulbutiamine (200 mg) or benfotiamine (150 mg) reveal their effects on the assayed parameters within those of thiamine. Administration of thiamine or its pharmacological forms increased the hand grip strength in the CMT patients. Comparison of the thiamin status in patients with different forms of CMT disease to that of control subjects without diagnosed pathologies revealed no significant differences in the average levels of ThDP, holo-transketolase, or relative content of holo and apo forms of transketolase. However, the regulation of transketolase by thiamine/ThDP differed in the control and CMT groups: in the assay, ThDP activated transketolase from the control individuals, but not from CMT patients. Thiamine administration paradoxically decreased endogenous holo-transketolase in CMT patients; this effect was not observed in the control group. Correlation analysis revealed sex-specific differences in the relationship between the parameters of thiamine status in both the control subjects and patients with the CMT disease. Thus, our findings link physiological benefits of thiamine administration in CMT patients to changes in their thiamine status, in particular, the blood levels of ThDP and transketolase regulation.

Nystagmus in a child with nephrotic syndrome

We report a child with steroid-dependent nephrotic syndrome presenting with excessive irritability, double vision and inability to walk for 5 days. On examination, the child was irritable with Glasgow coma sccale (GCS of 12/15, had bilateral convergent squint (R>L), vertical nystagmus, ataxia without any focal neurological deficits and normal fundus. MRI brain with venogram showed bilateral symmetric FLAIR hyperintensity in the medial thalamus and periaqueductal grey matter showing diffuse restriction with normal venogram. A possibility of Wernicke encephalopathy (WE) was considered and the child was started on thiamine supplementation, following which he had significant improvement in his symptoms. His irritability reduced with significant improvement in the range of eye movements and vertical nystagmus. At 3-month follow-up, the child is asymptomatic with normal gait. Although WE is uncommon in children with nephrotic syndrome, the possibility has to be kept in mind when a child presents with atypical neurological symptoms.

Posttranslational Acylations of the Rat Brain Transketolase Discriminate the Enzyme Responses to Inhibitors of ThDP-Dependent Enzymes or Thiamine Transport

Transketolase (TKT) is an essential thiamine diphosphate (ThDP)-dependent enzyme of the non-oxidative branch of the pentose phosphate pathway, with the glucose-6P flux through the pathway regulated in various medically important conditions. Here, we characterize the brain TKT regulation by acylation in rats with perturbed thiamine-dependent metabolism, known to occur in neurodegenerative diseases. The perturbations are modeled by the administration of oxythiamine inhibiting ThDP-dependent enzymes in vivo or by reduced thiamine availability in the presence of metformin and amprolium, inhibiting intracellular thiamine transporters. Compared to control rats, chronic administration of oxythiamine does not significantly change the modification level of the two detected TKT acetylation sites (K6 and K102) but doubles malonylation of TKT K499, concomitantly decreasing 1.7-fold the level of demalonylase sirtuin 5. The inhibitors of thiamine transporters do not change average levels of TKT acylation or sirtuin 5. TKT structures indicate that the acylated residues are distant from the active sites. The acylations-perturbed electrostatic interactions may be involved in conformational shifts and/or the formation of TKT complexes with other proteins or nucleic acids. Acetylation of K102 may affect the active site entrance/exit and subunit interactions. Correlation analysis reveals that the action of oxythiamine is characterized by significant negative correlations of K499 malonylation or K6 acetylation with TKT activity, not observed upon the action of the inhibitors of thiamine transport. However, the transport inhibitors induce significant negative correlations between the TKT activity and K102 acetylation or TKT expression, absent in the oxythiamine group. Thus, perturbations in the ThDP-dependent catalysis or thiamine transport manifest in the insult-specific patterns of the brain TKT malonylation and acetylations.

Observations on the Clinical Features of the Wernicke-Korsakoff Syndrome

This paper begins with a short case report of florid, spontaneous confabulation in a 61-year-old man with an alcohol-induced Wernicke-Korsakoff syndrome. His confabulation extended across episodic and personal semantic memory, as well as orientation in time and place, as measured on Dalla Barba's Confabulation Battery. Five other brief case summaries will then be presented, followed by a summary of the clinical, neurological, and background neuropsychological findings in three earlier series of Korsakoff patients. These observations will be considered in light of Wijnia's recent and my own, earlier reviews of the Korsakoff syndrome. Taken together, they indicate the need for a multi-faceted approach (clinical, neurological, neuropsychological, and neuroimaging) to the assessment and diagnosis of the disorder.

Pharmacological thiamine levels as a therapeutic approach in Alzheimer's disease

of the study.

SLC19A1 Genetic Variation Leads to Altered Thiamine Diphosphate Transport: Implications for the Risk of Developing Wernicke-Korsakoff's Syndrome

AIMS

Wernicke-Korsakoff syndrome (WKS) is commonly associated with chronic alcohol misuse, a condition known to have multiple detrimental effects on thiamine metabolism. This study was conducted to identify genetic variants that may contribute to the development of WKS in individuals with alcohol dependence syndrome through alteration of thiamine transport into cells.

METHODS

Exome sequencing data from a panel of genes related to alcohol metabolism and thiamine pathways were analysed in a discovery cohort of 29 individuals with WKS to identify possible genetic risk variants associated with its development. Variant frequencies in this discovery cohort were compared with European frequencies in the Genome Aggregation Database browser, and those present at significantly higher frequencies were genotyped in an additional cohort of 87 alcohol-dependent cases with WKS and 197 alcohol-dependent cognitively intact controls.

RESULTS

Thirty non-synonymous variants were identified in the discovery cohort and, after filtering, 23 were taken forward and genotyped in the case-control cohort. Of these SLC19A1:rs1051266:G was nominally associated with WKS. SLC19A1 encodes the reduced folate carrier, a major transporter for physiological folate in plasma; rs1051266 is reported to impact folate transport. Thiamine pyrophosphate (TPP) efflux was significantly decreased in HEK293 cells, stably transfected with rs1051266:G, under thiamine deficient conditions when compared with the efflux from cells transfected with rs1051266:A (P = 5.7 × 10-11).

CONCLUSION

This study provides evidence for the role of genetic variation in the SLC19A1 gene, which may contribute to the development of WKS in vivo through modulation of TPP transport in cells.

Repurposing Treatment of Wernicke-Korsakoff Syndrome for Th-17 Cell Immune Storm Syndrome and Neurological Symptoms in COVID-19: Thiamine Efficacy and Safety, In-Vitro Evidence and Pharmacokinetic Profile

Coronavirus disease identified in 2019 (COVID-19) can be complicated by the Th17 cell-mediated IL-17 proinflammatory response. We tested if thiamine can effectively lower the Th17 response in a clinical study [Proinflammatory state in alcohol use disorder patients termed as disease controls (DC)] and corroborated the results using an in vitro study. We developed an effective dose range and model for key pharmacokinetic measures with the potential of targeting the cytokine storm and neurological symptoms of COVID-19. Three-week 200 mg dose of thiamine was administered to sixteen DC patients. Eight healthy volunteers (HV) were also included in this investigation. A subsequent in vitro study was performed to validate the effectiveness of thiamine [100 mg/day equivalent (0.01 μg/ml)] treatment in lowering the Th17 proinflammatory response in a mouse macrophage cell line (RAW264.7) treated with ethanol. Based on recent publications, we compared the results of the IL-17 response from our clinical and in vitro study to those found in other proinflammatory disease conditions (metabolic conditions, septic shock, viral infections and COVID-19) and effective and safe dose ranges of thiamine. We developed a pharmacokinetic profile for thiamine dose range as a novel intervention strategy in COVID-19. DC group showed significantly elevated proinflammatory cytokines compared to HV. Thiamine-treated DC patients showed significant lowering in IL-17 and increase in the IL-22 levels. In humans, a range of 79-474 mg daily of thiamine was estimated to be effective and safe as an intervention for the COVID-19 cytokine storm. A literature review showed that several neurological symptoms of COVID-19 (∼45.5% of the severe cases) occur in other viral infections and neuroinflammatory states that may also respond to thiamine treatment. Thiamine, a very safe drug even at very high doses, could be repurposed for treating the Th17 mediated IL-17 immune storm, and the subsequent neurological symptoms observed in COVID-19. Further studies using thiamine as an intervention/prevention strategy in COVID-19 patients could identify its precise anti-inflammatory role.

Therapeutic Prospects for Th-17 Cell Immune Storm Syndrome and Neurological Symptoms in COVID-19: Thiamine Efficacy and Safety, In-vitro Evidence and Pharmacokinetic Profile

Introduction Emerging infectious diseases, especially the coronavirus disease identified in 2019 (COVID-19), can be complicated by a severe exacerbation in the Th17 cell-mediated IL-17 proinflammatory immune storm. This enhanced immune response plays a major role in mortality and morbidity, including neurological symptoms. We hypothesized that countering the cytokine storm with thiamine may have therapeutic efficacy in lowering the Th17 cell proinflammatory response. We used an in vitro study and corroborated those results in disease controls (DC). We developed an effective dose range and model for key pharmacokinetic measures with the potential of targeting the cytokine storm and neurological symptoms of COVID-19. Study Participants and Methods We investigated the effect of a three-week 200 mg dose of thiamine in lowering the Th17 response in sixteen DC (proinflammatory origin due to heavy alcohol drinking) patients; and eight healthy control/volunteers (HV) as a pilot clinical-translational investigation. To further investigate, we performed an in vitro study evaluating the effectiveness of thiamine treatment in lowering the Th17 proinflammatory response in a mouse macrophage cell line (RAW264.7) treated with ethanol. In this in vitro study, 100 mg/day equivalent (0.01 ug/ml) thiamine was used. Based on recent publications, we compared the results of the IL-17 response from our clinical and in vitro study to those found in other proinflammatory disease conditions (metabolic conditions, septic shock, viral infections and COVID-19), including symptoms, and dose ranges of effective and safe administration of thiamine. We developed a dose range and pharmacokinetic profile for thiamine as a novel intervention strategy in COVID-19 to alleviate the effects of the cytokine storm and neurological symptoms. Results The DC group showed significantly elevated proinflammatory cytokines compared to HV. Three-week of 200 mg daily thiamine treatment significantly lowered the baseline IL-17 levels while increased IL-22 levels (anti-inflammatory response). This was validated by an in vitro macrophage response using a lower thiamine dose equivalent (100 mg), which resulted in attenuation of IL-17 and elevation of IL-22 at the mRNA level compared to the ethanol-only treated group. In humans, a range of 79-474 mg daily of thiamine was estimated to be effective and safe as an intervention for the COVID-19 cytokine storm. A literature review showed that several neurological symptoms of COVID-19 (which exist in 45.5% of the severe cases) occur in other viral infections and neuroinflammatory states that may also respond to thiamine treatment. Discussion The Th17 mediated IL-17 proinflammatory response can potentially be attenuated by thiamine. Thiamine, a very safe drug even at very high doses, could be repurposed for treating the cytokine/immune storm of COVID-19 and the subsequent neurological symptoms observed in COVID-19 patients. Further studies using thiamine as an interventional/prevention strategy in severe COVID-19 patients could identify its precise anti-inflammatory role.

Don't seek, don't find: The diagnostic challenge of Wernicke's encephalopathy

Wernicke’s encephalopathy is caused by thiamine deficiency and has a range of presenting features, including gait disturbance, altered cognitive state, nystagmus and other eye movement disorders. In the past, Wernicke’s encephalopathy was described almost exclusively in the alcohol-dependent population. However, in current times, Wernicke’s encephalopathy is also well recognized in many other patient groups, including patients following bariatric surgery, gastrointestinal surgery, cancer and pancreatitis. Early recognition of Wernicke’s encephalopathy is vital, as prompt treatment can restore cognitive or ocular function and can prevent permanent disability. Unfortunately, Wernicke’s encephalopathy is often undiagnosed – presumably because it is relatively uncommon and has a variable clinical presentation. Clinical biochemists have a unique role in advising clinicians about potential nutritional or metabolic causes of unexplained neurological symptoms and to prompt consideration of thiamine deficiency as a potential cause in high-risk patient groups. The aim of this review is to summarize the clinical features, diagnosis and treatment of Wernicke’s encephalopathy and to highlight some non-traditional causes, such as after bariatric surgery.

Review of thiamine deficiency disorders: Wernicke encephalopathy and Korsakoff psychosis

Wernicke encephalopathy (WE) and Korsakoff psychosis (KP), together termed Wernicke-Korsakoff syndrome (WKS), are distinct yet overlapping neuropsychiatric disorders associated with thiamine deficiency. Thiamine pyrophosphate, the biologically active form of thiamine, is essential for multiple biochemical pathways involved in carbohydrate utilization. Both genetic susceptibilities and acquired deficiencies as a result of alcoholic and non-alcoholic factors are associated with thiamine deficiency or its impaired utilization. WKS is underdiagnosed because of the inconsistent clinical presentation and overlapping of symptoms with other neurological conditions. The identification and individualized treatment of WE based on the etiology is vital to prevent the development of the amnestic state associated with KP in genetically predisposed individuals. Through this review, we bring together the existing data from animal and human models to expound the etiopathogenesis, diagnosis, and therapeutic interventions for WE and KP.

Identification of transketolase as a target of PARIS in substantia nigra

Recently, PARIS (ZNF746) is introduced as authentic substrate of parkin and transcriptionally represses PGC-1α by binding to insulin responsive sequences (IRSs) in the promoter of PGC-1α. The overexpression of PARIS selectively leads to the loss of dopaminergic neurons (DN) and mitochondrial abnormalities in the substantia nigra (SN) of Parkinson's disease (PD) models. To identify PARIS target molecules altered in SN region-specific manner, LC-MS/MS-based quantitative proteomic analysis is employed to investigate proteomic alteration in the cortex, striatum, and SN of AAV-PARIS injected mice. Herein, we find that the protein and mRNA of transketolase (TKT), a key enzyme in pentose phosphate pathway (PPP) of glucose metabolism, is exclusively decreased in the SN of AAV-PARIS mice. PARIS overexpression suppresses TKT transcription via IRS-like motif in the TKT promoter. Moreover, the reduction of TKT by PARIS is found in primary DN but not in cortical neurons, suggesting that PARIS-medicated TKT suppression is cell type-dependent. Interestingly, we observe the reduced level of TKT in the SN of PD patients but not in the cortex. These findings indicate that TKT might be a SN-specific target of PARIS, providing new clues to understand the mechanism underlying selective DNs death in PD.

Role of HIF-1α in the hypoxia inducible expression of the thiamine transporter, SLC19A3

Ensuring continuous intracellular supply of thiamine is essential to maintain metabolism. Cellular homeostasis requires the function of the membrane bound thiamine transporters THTR1 and THTR2. In the absence of increased dietary intake of thiamine, varying intracellular levels to meet metabolic demands during pathophysiological stressors, such as hypoxia, requires adaptive regulatory mechanisms to increase thiamine transport capacity. Previous work has established the up-regulation of SLC19A3 (THTR2) gene expression and activity during hypoxic stress through the activity of the hypoxia inducible transcription factor 1 alpha (HIF-1α). However, it is unknown whether HIF-1α acts directly or indirectly to trans-activate expression of SLC19A3. This work utilized the breast cancer cell line BT-474 treated with 1% O2 or a hypoxia chemical mimetic deferoxamine to determine the minimal promoter region of SLC19A3 responsible for hypoxia responsiveness. In silico sequence analysis determined two contiguous hypoxia responsive elements in close proximity to the transcriptional start site of the SLC19A3 gene. Using a HIF-1α transcriptional factor ELISA assay, HIF-1α was capable of binding to a dsDNA construct of the SLC19A3 minimal promoter. Chromatin immunoprecipitation assay established that SP1 was bound to the SLC19A3 minimal promoter region under normoxic conditions. However, HIF-1α binding to the minimal promoter region occurred during hypoxic treatments, while no SP1 binding was observed under these conditions. This work demonstrates the direct binding and activation of SLC19A3 expression by HIF-1α during hypoxic stress, suggesting an important adaptive regulatory role for HIF-1α in maintaining thiamine homeostasis.

Advances in clinical determinants and neurological manifestations of B vitamin deficiency in adults

B vitamin deficiency is a leading cause of neurological impairment and disability throughout the world. Multiple B vitamin deficiencies often coexist, and thus an understanding of the complex relationships between the different biochemical pathways regulated in the brain by these vitamins may facilitate prompter diagnosis and improved treatment. Particular populations at risk for multiple B vitamin deficiencies include the elderly, people with alcoholism, patients with heart failure, patients with recent obesity surgery, and vegetarians/vegans. Recently, new clinical settings that predispose individuals to B vitamin deficiency have been highlighted. Moreover, other data indicate a possible pathogenetic role of subclinical chronic B vitamin deficiency in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In light of these findings, this review examines the clinical manifestations of B vitamin deficiency and the effect of B vitamin deficiency on the adult nervous system. The interrelationships of multiple B vitamin deficiencies are emphasized, along with the clinical phenotypes related to B vitamin deficiencies. Recent advances in the clinical determinants and diagnostic clues of B vitamin deficiency, as well as the suggested therapies for B vitamin disorders, are described.

[Clinical appearance and scalable profile Thiamine deficiency in prison in Guinea: study of thirty-eight observations]

Cardiovascular and neurological manifestations associated with thiamine deficiency in Guinean prisons are common but not reported.We performed a prospective study of 38 cases related to vitamin B1 deficiency over a period of 4 years. In this population, the literature of traditional data gathered: frequency peak after thirty (92.6%) and clear representation male (sex ratio M/F: 18/1). The clinical symptomatology remains essentially dominated by sensorimotor polyneuropathy and pure sensory (52.2%), overall heart failure (31.5%) and to a lesser degree by Gayet Wernicke's encephalopathy (7.8%) and shoshin beriberi with severe evolution (5.2%). The study of nutritional status by body mass index (BMI) of the World Health Organization, by the criteria of Detsky and biological markers including albumin, shows that these patients are severely malnourished.

Vitamin B1 (thiamine) and dementia

The earliest and perhaps best example of an interaction between nutrition and dementia is related to thiamine (vitamin B1). Throughout the last century, research showed that thiamine deficiency is associated with neurological problems, including cognitive deficits and encephalopathy. Multiple similarities exist between classical thiamine deficiency and Alzheimer's disease (AD) in that both are associated with cognitive deficits and reductions in brain glucose metabolism. Thiamine-dependent enzymes are critical components of glucose metabolism that are reduced in the brains of AD patients and by thiamine decline, and a decrease in their levels could account for the reduction in glucose metabolism. In preclinical models, reduced thiamine can drive AD-like abnormalities, including memory deficits, neuritic plaques, and hyperphosphorylation of tau. Furthermore, excess thiamine diminishes AD-like pathologies. In addition to dietary deficits, drugs or other manipulations that interfere with thiamine absorption can cause thiamine deficiency. Elucidating the reasons why the brains of AD patients are functionally thiamine deficient and determining the effects of thiamine restoration may provide critical information to help treat patients with AD.

TKTL1 expression in human malign and benign cell lines

Background

Overexpression of transketolase-like 1 protein TKTL1 in cancer cells has been reported to correlate with enhanced glycolysis and lactic acid production. Furthermore, enhanced TKTL1 expression was put into context with resistance to chemotherapy and ionizing radiation. Here, a panel of human malign and benign cells, which cover a broad range of chemotherapy and radiation resistance as well as reliance on glucose metabolism, was analyzed in vitro for TKTL1 expression.

Methods

17 malign and three benign cell lines were characterized according to their expression of TKTL1 on the protein level with three commercially available anti-TKTL1 antibodies utilizing immunohistochemistry and Western blot, as well as on mRNA level with three published primer pairs for RT-qPCR. Furthermore, sensitivities to paclitaxel, cisplatin and ionizing radiation were assessed in cell survival assays. Glucose consumption and lactate production were quantified as surrogates for the “Warburg effect”.

Results

Considerable amounts of tktl1 mRNA and TKTL1 protein were detected only upon stable transfection of the human embryonic kidney cell line HEK293 with an expression plasmid for human TKTL1. Beyond that, weak expression of endogenous tktl1 mRNA was measured in the cell lines JAR and U251. Western blot analysis of JAR and U251 cells did not detect TKTL1 at the expected size of 65 kDa with all three antibodies specific for TKTL1 protein and immunohistochemical staining was observed with antibody JFC12T10 only. All other cell lines tested here revealed expression of tktl1 mRNA below detection limits and were negative for TKTL1 protein. However, in all cell lines including TKTL1-negative HEK293-control cells, antibody JFC12T10 detected multiple proteins with different molecular weights. Importantly, JAR and U251 did neither demonstrate an outstanding production of lactic acid nor increased resistance against chemotherapeutics or to ionizing radiation, respectively.

Conclusion

Using RT-qPCR and three different antibodies we observed only exceptional occurrence of TKTL1 in a panel of malignant human cell lines in vitro. The presence of TKTL1 was unrelated to either the rate of glucose consumption/lactic acid production or resistance against chemo- and radiotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-15-2) contains supplementary material, which is available to authorized users.

Transketolase is upregulated in metastatic peritoneal implants and promotes ovarian cancer cell proliferation

Ovarian cancer, the most lethal gynaecological cancer, is characterised by the shedding of epithelial cells from the ovarian surface, followed by metastasis and implantation onto the peritoneal surfaces of abdominal organs. Our proteomic studies investigating the interactions between peritoneal (LP-9) and ovarian cancer (OVCAR-5) cells found transketolase (TKT) to be regulated in the co-culture system. This study characterized TKT expression in advanced stage (III/IV) serous ovarian cancers (n = 125 primary and n = 54 peritoneal metastases), normal ovaries (n = 6) and benign serous cystadenomas (n = 10) by immunohistochemistry. In addition, we also evaluated the function of TKT in ovarian cancer cells in vitro. Nuclear TKT was present in all primary serous ovarian cancer tissues examined (median 82.0 %, range 16.5-100 %) and was significantly increased in peritoneal metastases compared with matching primary cancers (P = 0.01, Wilcoxon Rank test). Kaplan-Meier survival and Cox regression analyses showed that high nuclear TKT positivity in peritoneal metastases (>94 %) was significantly associated with reduced overall survival (P = 0.006) and a 2.8 fold increased risk of ovarian cancer death (95 % CI 1.29-5.90, P = 0.009). Knockdown of TKT by siRNAs significantly reduced SKOV-3 cell proliferation but had no effect on their motility or invasion. Oxythiamine, an inhibitor of TKT activity, significantly inhibited the proliferation of four ovarian cancer cell lines (OV-90, SKOV-3, OVCAR-3 and OVCAR-5) and primary serous ovarian cancer cells isolated from patient ascites. In conclusion, these findings indicate that TKT plays an important role in the proliferation of metastatic ovarian cancer cells and could be used as novel therapeutic target for advanced disease.

Identification of vitamin B1 metabolism as a tumor-specific radiosensitizing pathway using a high-throughput colony formation screen

Colony formation is the gold standard assay for determining reproductive cell death after radiation treatment, since effects on proliferation often do not reflect survival. We have developed a high-throughput radiosensitivity screening method based on clonogenicity and screened a siRNA library against kinases. Thiamine pyrophosphokinase-1 (TPK1), a key component of Vitamin B1/thiamine metabolism, was identified as a target for radiosensitization. TPK1 knockdown caused significant radiosensitization in cancer but not normal tissue cell lines. Other means of blocking this pathway, knockdown of thiamine transporter-1 (THTR1) or treatment with the thiamine analogue pyrithiamine hydrobromide (PyrH) caused significant tumor specific radiosensitization. There was persistent DNA damage in cells irradiated after TPK1 and THTR1 knockdown or PyrH treatment. Thus this screen allowed the identification of thiamine metabolism as a novel radiosensitization target that affects DNA repair. Short-term modulation of thiamine metabolism could be a clinically exploitable strategy to achieve tumor specific radiosensitization.

Thiamine and magnesium deficiencies: keys to disease

Thiamine deficiency (TD) is accepted as the cause of beriberi because of its action in the metabolism of simple carbohydrates, mainly as the rate limiting cofactor for the dehydrogenases of pyruvate and alpha-ketoglutarate, both being critical to the action of the citric acid cycle. Transketolase, dependent on thiamine and magnesium, occurs twice in the oxidative pentose pathway, important in production of reducing equivalents. Thiamine is also a cofactor in the dehydrogenase complex in the degradation of the branched chain amino acids, leucine, isoleucine and valine. In spite of these well accepted facts, the overall clinical effects of TD are still poorly understood. Because of the discovery of 2-hydroxyacyl-CoA lyase (HACL1) as the first peroxisomal enzyme in mammals found to be dependent on thiamine pyrophosphate (TPP) and the ability of thiamine to bind with prion protein, these factors should improve our clinical approach to TD. HACL1 has two important roles in alpha oxidation, the degradation of phytanic acid and shortening of 2-hydroxy long-chain fatty acids so that they can be degraded further by beta oxidation. The downstream effects of a lack of efficiency in this enzyme would be expected to be critical in normal brain metabolism. Although TD has been shown experimentally to produce reversible damage to mitochondria and there are many other causes of mitochondrial dysfunction, finding TD as the potential biochemical lesion would help in differential diagnosis. Stresses imposed by infection, head injury or inoculation can initiate intermittent cerebellar ataxia in thiamine deficiency/dependency. Medication or vaccine reactions appear to be more easily initiated in the more intelligent individuals when asymptomatic marginal malnutrition exists. Erythrocyte transketolase testing has shown that thiamine deficiency is widespread. It is hypothesized that the massive consumption of empty calories, particularly those derived from carbohydrate and fat, results in a high calorie/thiamine ratio as a major cause of disease. Because mild to moderate TD results in pseudo hypoxia in the limbic system and brainstem, emotional and stress reflexes of the autonomic nervous system are stimulated and exaggerated, producing symptoms often diagnosed as psychosomatic disease. If the biochemical lesion is recognized at this stage, the symptoms are easily reversible. If not, and the malnutrition continues, neurodegeneration follows and results in a variety of chronic brain diseases. Results from acceptance of the hypothesis could be tested by performing erythrocyte transketolase tests to pick out those with TD and supplementing the affected individuals with the appropriate dietary supplements.

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.

Structure and functioning mechanism of transketolase

Studies of thiamine diphosphate-dependent enzymes appear to have commenced in 1937, with the isolation of the coenzyme of yeast pyruvate decarboxylase, which was demonstrated to be a diphosphoric ester of thiamine. For quite a long time, these studies were largely focused on enzymes decarboxylating α-keto acids, such as pyruvate decarboxylase and pyruvate dehydrogenase complexes. Transketolase, discovered independently by Racker and Horecker in 1953 (and named by Racker) [1], did not receive much attention until 1992, when crystal X-ray structure analysis of the enzyme from Saccharomyces cerevisiae was performed [2]. These data, together with the results of site-directed mutagenesis, made it possible to understand in detail the mechanism of thiamine diphosphate-dependent catalysis. Some progress was also made in studies of the functional properties of transketolase. The last review on transketolase, which was fairly complete, appeared in 1998 [3]. Therefore, the publication of this paper should not seem premature.

Double-blind, randomized placebo-controlled clinical trial of benfotiamine for severe alcohol dependence

Alcohol dependence is associated with severe nutritional and vitamin deficiency. Vitamin B1 (thiamine) deficiency erodes neurological pathways that may influence the ability to drink in moderation. The present study examines tolerability of supplementation using the high-potency thiamine analog, benfotiamine (BF), and BF's effects on alcohol consumption in severely affected, self-identified, alcohol dependent subjects. A randomized, double-blind, placebo-controlled trial was conducted on 120 non-treatment seeking, actively drinking, alcohol dependent men and women volunteers (mean age=47 years) from the Kansas City area who met DSM-IV-TR criteria for current alcohol dependence. Subjects were randomized to receive 600 mg benfotiamine or placebo (PL) once daily by mouth for 24 weeks with 6 follow-up assessments scheduled at 4 week intervals. Side effects and daily alcohol consumption were recorded. Seventy (58%) subjects completed 24 weeks of study (N=21 women; N=49 men) with overall completion rates of 55% (N=33) for PL and 63% (N=37) for BF groups. No significant adverse events were noted and alcohol consumption decreased significantly for both treatment groups. Alcohol consumption decreased from baseline levels for 9 of 10 BF treated women after 1 month of treatment compared with 2 of 11 on PL. Reductions in total alcohol consumption over 6 months were significantly greater for BF treated women (BF: N=10, -611 ± 380 standard drinks; PL: N=11, -159 ± 562 standard drinks, p-value=0.02). BF supplementation of actively drinking alcohol dependent men and women was well-tolerated and may discourage alcohol consumption among women. The results do support expanded studies of BF treatment in alcoholism.

Wernicke's encephalopathy following Hyperemesis gravidarum. A report of three cases

Wernicke's encephalopathy (WE) due to causes other than chronic alcohol abuse is an uncommon and often misdiagnosed condition. In the setting of hyperemesis gravidarum, an acute deficiency of thiamine results from body stores being unable to meet increased metabolic demands. The condition produces typical clinical and radiological findings and when diagnosed early and treated promptly has a good prognosis. Magnetic resonance imaging (MRI) is sensitive and specific for diagnosis. We describe three patients with hyperemesis gravidarum who developed WE, and highlight a range of clinical and imaging features important for appropriate diagnosis. A high degree of clinical suspicion is essential. Treatment is often empirical pending results of investigation, and consists of parenteral repletion of thiamine stores. Reversal of MRI findings parallels clinical improvement. Neurologic outcomes are usually good, but half the pregnancies complicated by this condition do not produce healthy children.

Nutritional disorders in tropical neurology

About three-fourths of the total world population live in the tropics but consume only 6% of worldwide food production and contribute 15% of the world's net revenue explaining the short life expectancy, high infantile mortality, and poor daily caloric intake; moreover, lack of clean drinking water and deficient sanitation promote water-borne infections, diarrhea, and risk of malabsorption that contribute to the prevalence of malnutrition in the tropics. One-third of the world's population consumes insufficient iodine increasing the risk for mental retardation and deafness due to maternal hypothyroidism. The main nutritional syndromes comprise protein-energy malnutrition (marasmus and kwashiorkor); nutritional neuropathies, myelopathies and neuromyelopathies, as well as specific deficiencies of vitamins and micronutrients including iodine, iron, zinc, and selenium.

The Neurological Complications of Nutritional Deficiency following Bariatric Surgery

Neurologic complications of bariatric surgery have become increasingly recognized with the rising numbers of procedures and the increasing prevalence of obesity in the US. Deficits are most commonly seen with thiamine, vitamin B(12), folate, vitamin D, vitamin E, and copper deficiencies. The neurological findings observed with these nutritional deficiencies are variable and include encephalopathy, optic neuropathy, myelopathy, polyradiculoneuropathy, and polyneuropathy. We review the neurological complications of bariatric surgery and emphasize that these findings may vary based on the specific type of bariatric surgery and time elapsed from the procedure.

FLNA genomic rearrangements cause periventricular nodular heterotopia

OBJECTIVE

To identify copy number variant (CNV) causes of periventricular nodular heterotopia (PNH) in patients for whom FLNA sequencing is negative.

METHODS

Screening of 35 patients from 33 pedigrees on an Affymetrix 6.0 microarray led to the identification of one individual bearing a CNV that disrupted FLNA. FLNA-disrupting CNVs were also isolated in 2 other individuals by multiplex ligation probe amplification. These 3 cases were further characterized by high-resolution oligo array comparative genomic hybridization (CGH), and the precise junctional breakpoints of the rearrangements were identified by PCR amplification and sequencing.

RESULTS

We report 3 cases of PNH caused by nonrecurrent genomic rearrangements that disrupt one copy of FLNA. The first individual carried a 113-kb deletion that removes all but the first exon of FLNA. A second patient harbored a complex rearrangement including a deletion of the 3' end of FLNA accompanied by a partial duplication event. A third patient bore a 39-kb deletion encompassing all of FLNA and the neighboring gene EMD. High-resolution oligo array CGH of the FLNA locus suggests distinct molecular mechanisms for each of these rearrangements, and implicates nearby low copy repeats in their pathogenesis.

CONCLUSIONS

These results demonstrate that FLNA is prone to pathogenic rearrangements, and highlight the importance of screening for CNVs in individuals with PNH lacking FLNA point mutations.

Thiamin(e): the spark of life

One of the earliest vitamins to be discovered and synthesized, thiamin was originally spelled with an "e". The terminal "e" was dropped when it was found that it was not an amine. It is still spelled with and without the "e" depending on the text. This chapter provides a brief historical review of the association of thiamin with the ancient scourge of beriberi. It emphasizes that beriberi is the model for high calorie malnutrition because of its occurrence in predominantly white rice consuming cultures. Some of the symptomatology of this ancient scourge is described, emphasizing the difference from that seen in starvation. High calorie malnutrition, due to excessive ingestion of simple carbohydrates, is widely encountered in the U.S.A. today. Thiamin deficiency is commonly associated with this, largely because of its cofactor status in the metabolism of glucose. The biochemistry of the three phosphorylated esters of thiamin and the transporters are discussed and the pathophysiology of thiamin deficiency reviewed. The role of thiamin, and particularly its synthetic derivatives as therapeutic agents, is not fully appreciated in Western civilization and a clinical section describes some of the unusual cases described in the scientific literature and some experienced by the author. The possible role of high calorie malnutrition and related thiamin deficiency in juvenile crime is hypothesized.

Role of thiamine in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in elderly individuals and is associated with progressive neurodegeneration of the human neocortex. Thiamine levels and the activity of thiamine-dependent enzymes are reduced in the brains and peripheral tissues of patients with AD. Genetic studies have provided the opportunity to determine what proteins link thiamine to AD pathology (ie, transketolase, apolipoprotein E, α-1-antitrypsin, pyruvate dehydrogenase complex, p53, glycogen synthetase kinase-3β, c-Fos gene, the Sp1 promoter gene, and the poly(ADP-ribosyl) polymerase-1 gene). We reviewed the association between histopathogenesis and neurotransmitters to understand the relationship between thiamine and AD pathology. Oral thiamine trials have been shown to improve the cognitive function of patients with AD; however, absorption of thiamine is poor in elderly individuals. In the early stage of thiamine-deficient encephalopathy (Wernicke's encephalopathy), however, parental thiamine has been used successfully. Therefore, further studies are needed to determine the benefits of using parental thiamine as a treatment for AD.

Wernicke's Encephalopathy in a Patient with Peptic Ulcer Disease

We report a 74-year-old man with Wernicke's encephalopathy (WE) whose only prior illness was peptic ulcer disease. Upper gastrointestinal endoscopy demonstrated gastric ulcer scars accompanied by marked deformity, without pathologic evidence of malignancy. WE due to peptic ulcer disease in previous reports was substantially associated with thiamine deficiency due to recurrent vomiting or surgical procedures. In our case, however, there was no history of vomiting or gastrointestinal surgery. Besides, we thoroughly ruled out other known clinical settings related to WE. There is the possibility that peptic ulcer disease itself provoked thiamine deficiency due to malabsorption.

Clinical and pathological features of alcohol-related brain damage

One of the sequelae of chronic alcohol abuse is malnutrition. Importantly, a deficiency in thiamine (vitamin B(1)) can result in the acute, potentially reversible neurological disorder Wernicke encephalopathy (WE). When WE is recognized, thiamine treatment can elicit a rapid clinical recovery. If WE is left untreated, however, patients can develop Korsakoff syndrome (KS), a severe neurological disorder characterized by anterograde amnesia. Alcohol-related brain damage (ARBD) describes the effects of chronic alcohol consumption on human brain structure and function in the absence of more discrete and well-characterized neurological concomitants of alcoholism such as WE and KS. Through knowledge of both the well-described changes in brain structure and function that are evident in alcohol-related disorders such as WE and KS and the clinical outcomes associated with these changes, researchers have begun to gain a better understanding of ARBD. This Review examines ARBD from the perspective of WE and KS, exploring the clinical presentations, postmortem brain pathology, in vivo MRI findings and potential molecular mechanisms associated with these conditions. An awareness of the consequences of chronic alcohol consumption on human behavior and brain structure can enable clinicians to improve detection and treatment of ARBD.

Thiamine (Vitamin B1)

Thiamine (vitamin B 1) was the first B vitamin to have been identified. It serves as a cofactor for several enzymes involved in energy metabolism. The thiamine-dependent enzymes are important for the biosynthesis of neurotransmitters and for the production of reducing substances used in oxidant stress defenses, as well as for the synthesis of pentoses used as nucleic acid precursors. Thiamine plays a central role in cerebral metabolism. Its deficiency results in dry beriberi, a peripheral neuropathy, wet beriberi, a cardiomyopathy with edema and lactic acidosis, and Wernicke—Korsakoff syndrome, whose manifestations consist of nystagmus, ophthalmoplegia, and ataxia evolving into confusion, retrograde amnesia, cognitive impairment, and confabulation. Patients on a strict thiamine-deficient diet display a state of severe depletion within 18 days. The most common cause of thiamine deficiency in affluent countries is either alcoholism or malnutrition in nonalcoholic patients. Treatment by thiamine supplementation is beneficial for diagnostic and therapeutic purposes.

Thiamine-deficient encephalopathy due to excessive intake of isotonic drink or overstrict diet therapy in Japanese children

AIM

To report on two children with encephalopathy caused by dietary thiamine deficiency due to newly developing nutritional problems in contemporary Japan.

SUBJECTS

A 1-year-old boy who had consumed 1l of isotonic drinks per day for 4 months after an episode of diarrhea, and presented with ocular movement disorder, dystonia, and unconsciousness. The other subject was an 11-month-old boy who suffered from vomiting and somnolence; he and his mother had atopic dermatitis, and he had been on a low-allergen diet that strictly restricted intake of eggs, dairy products, meat, and fish since his early infancy.

RESULTS

Both patients showed decreased blood thiamine levels and magnetic resonance imaging revealed striatal and thalamic lesions. Thiamine administration yielded prompt improvement of symptoms, but cavitiform lesions in the bilateral putamen persisted in the first patient, accompanied by residual generalized dystonia. Marked elevation of blood/cerebrospinal lactate levels and severe hyponatremia were present in this patient.

CONCLUSION

Thiamine-deficient encephalopathy in Japanese children due to excessive intake of sports drink or overstrict diet therapy for atopic dermatitis has been increasingly reported during the last decade, but is still not broadly recognized. These children may visit hospitals due to persistent vomiting as a symptom of thiamine deficiency, but glucose infusion without thiamine supplementation can aggravate their condition. Knowledge of these facts in medical and public settings is necessary to correct the erroneous impression that nutritional options given to ill children are necessarily beneficial for health, and promote awareness that they can be harmful when consumed in excess.

Neurologic presentations of nutritional deficiencies

Optimal functioning of the central and peripheral nervous system is dependent on a constant supply of appropriate nutrients. The first section of this review discusses neurologic manifestations related to deficiency of key nutrients such as vitamin B(12), folate, copper, vitamin E, thiamine, and others. The second section addresses neurologic complications related to bariatric surgery. The third sections includes neurologic presentations caused by nutrient deficiencies in the setting of alcoholism. The concluding section addresses neurologic deficiency diseases that have a geographic predilection.

A review on research progress of transketolase

Transketolase (TK), a thiamine diphosphate (ThDP)-dependent enzyme, catalyzes several key reactions of non-oxidative branch of pentose phosphate pathway. TK is a homodimer with two active sites that locate at the interface between the contacting monomers. Both ThDP and bivalent cations are strictly needed for TK activation, just like that for all ThDP-dependent enzymes. TK exists in all organisms that have been investigated. Up to now, one TK gene (TKT) and two transketolase-like genes (TKTL1 and TKTL2) have been identified in human genome. TKTL1 is reported to play a pivotal role in carcinogenesis and may have important implications in the nutrition and future treatment of patients with cancer. Researchers have found TK variants and reduced activities of TK enzyme in patients with neurodegenerative diseases, diabetes, and cancer. Recent studies indicated TK as a novel role in the prevention and therapy of these diseases.