Thiamine deficiency and cardiovascular disorders.

BACKGROUND AND AIM: Thiamine, also known as vitamin B1, functions as a cofactor in the metabolism of carbohydrates and amino acids. Thiamine deficiency has been suggested to be associated with many cardiovascular diseases (CVDs) and risk factors including type 1 and type 2 diabetes (T1D and T2D, respectively), obesity, chronic vascular inflammation, dyslipidemia, heart failure (HF), myocardial infarction (MI) and conduction defects, and depression. The aim of this review was to explore the evidence of thiamine deficiency among subjects with CVDs or risk factors, illustrate the theories explaining the thiamine-CVDs associations, and describe the effect of thiamine supplementation. METHODS: Human and animal studies were collected from various scientific databases following the PRISMA guidelines without limitation regarding the publication year. Studies investigating the prevalence of thiamine deficiency among patients with CVDs and the effect of thiamine supplementation on their conditions were summarized. RESULTS AND CONCLUSIONS: Thiamine deficiency could have a role in the development of CVDs. Future studies should focus on the impact of thiamine supplementation on reversing CVDs and risk factors associated with its deficiency.

Product inhibition of mammalian thiamine pyrophosphokinase is an important mechanism for maintaining thiamine diphosphate homeostasis.

BACKGROUND: Thiamine diphosphate (ThDP), an indispensable cofactor for oxidative energy metabolism, is synthesized through the reaction thiamine + ATP ⇆ ThDP + AMP, catalyzed by thiamine pyrophosphokinase 1 (TPK1), a cytosolic dimeric enzyme. It was claimed that the equilibrium of the reaction is in favor of the formation of thiamine and ATP, at odds with thermodynamic calculations. Here we show that this discrepancy is due to feedback inhibition by the product ThDP. METHODS: We used a purified recombinant mouse TPK1 to study reaction kinetics in the forward (physiological) and for the first time also in the reverse direction. RESULTS: Keq values reported previously are strongly underestimated, due to the fact the reaction in the forward direction rapidly slows down and reaches a pseudo-equilibrium as ThDP accumulates. We found that ThDP is a potent non-competitive inhibitor (Ki ≈ 0.4 µM) of the forward reaction. In the reverse direction, a true equilibrium is reached with a Keq of about 2 × 10-5, strongly in favor of ThDP formation. In the reverse direction, we found a very low Km for ThDP (0.05 µM), in agreement with a tight binding of ThDP to the enzyme. GENERAL SIGNIFICANCE: Inhibition of TPK1 by ThDP explains why intracellular ThDP levels remain low after administration of even very high doses of thiamine. Understanding the consequences of this feedback inhibition is essential for developing reliable methods for measuring TPK activity in tissue extracts and for optimizing the therapeutic use of thiamine and its prodrugs with higher bioavailability under pathological conditions.

Wernicke's encephalopathy in women with hyperemesis gravidarum - Case series and literature review.

Whilst nausea affects around 80% of pregnant women, hyperemesis gravidarum, an extreme form of the same, affects only 0.5% to 3%, but may lead to severe nutritional deficiency. Wernicke's encephalopathy is an acute neuropsychiatric disorder which occurs due to thiamine deficiency and needs emergency treatment to prevent neurological morbidity and mortality. Wernicke's encephalopathy is characterised by a clinical triad of oculomotor abnormalities, cerebellar dysfunction and altered mental state. Korsakoff's psychosis is a chronic condition and consequence of Wernicke's encephalopathy, resulting from its delayed treatment. Wernicke's encephalopathy is a well-known complication of chronic alcohol abuse. Not many are aware of its association with hyperemesis gravidarum. Although it is a rare complication, if not diagnosed and treated promptly, it may result in permanent and irreversible neurological sequelae. The objective of our retrospective observational study was to analyse the clinical profile and outcome (short and long term) in a rare yet preventable complication of pregnancy.

Insights Into Thiamine Supplementation in Patients With Septic Shock.

Septic shock is associated with unacceptably high mortality rates, mainly in developing countries. New adjunctive therapies have been explored to reduce global mortality related to sepsis. Considering that metabolic changes, mitochondrial dysfunction and increased oxidative stress are specific disorders within the path of septic shock, several micronutrients that could act in cellular homeostasis have been studied in recent decades. Thiamine, also known as vitamin B1, plays critical roles in several biological processes, including the metabolism of glucose, synthesis of nucleic acids and reduction of oxidative stress. Thiamine deficiency could affect up to 70% of critically ill patients, and thiamine supplementation appears to increase lactate clearance and decrease the vasopressor dose. However, there is no evident improvement in the survival of septic patients. Other micronutrients such as vitamin C and D, selenium and zinc have been tested in the same context but have not been shown to improve the outcomes of these patients. Some problems related to the neutrality of these clinical trials are the study design, doses, route, timing, length of intervention and the choice of endpoints. Recently, the concept that multi-micronutrient administration may be better than single-micronutrient administration has gained strength. In general, clinical trials consider the administration of a single micronutrient as a drug. However, the antioxidant defense is a complex system of endogenous agents in which micronutrients act as cofactors, and the physiological interactions between micronutrients are little discussed. In this context, the association of thiamine, vitamin C and corticoids was tested as an adjunctive therapy in septic shock resulting in a significant decrease in mortality. However, after these initial results, no other study conducted with this combination could reproduce those benefits. In addition, the use of low-dose corticosteroids is recommended in patients with septic shock who do not respond to vasopressors, which can affect the action of thiamine. Therefore, given the excellent safety profile, good biologic rationale and promising clinical studies, this review aims to discuss the mechanisms behind and the evidence for single or combined thiamine supplementation improving the prognosis of patients with septic shock.

Wernicke's Encephalopathy due to Non-Alcoholic Gastrointestinal Tract Disease.

INTRODUCTION: Wernicke's encephalopathy (WE) is an underdiagnosed neuropsychiatric disorder especially in non-alcoholic groups that causes morbidity-mortality if diagnosis is delayed. Korsakoff syndrome is a chronic consequence of this condition characterized by persistent memory impairment. In this study we present a series of non-alcoholic patients with WE. The purpose of this study was to analyze the predisposing factors in non-alcoholic patients with WE and emphasize the importance of early diagnosis and treatment with thiamine supplementation. METHODS: The clinical records of 6 cases with WE followed by gastrointestinal tract disease and/or surgery who were admitted to our Medical Faculty between 2012 and 2014 were retrospectively reviewed. RESULTS: The study included 3 men and 3 women in the age range of 24 to 55. All patients had gastrointestinal tract diseases and/or had undergone gastrointestinal surgeries, and were non-alcoholic. Vomiting, weight loss, and parenteral nutrition were the frequent precipitating factors. The classic triad of mental impairment, oculomotor alterations and gait ataxia was present in 4 of the 6 patients. Magnetic Resonance Imaging showed typical signal alterations in the medial thalami, mammillary bodies and the periaqueductal region of patients in various degrees. Clinical improvement was seen in each patient after thiamine supplementation. DISCUSSION: Physicians should be aware of the predisposing factors and symptoms to prevent or optimize the management of this potentially devastating disease. Thiamine supplementation should be considered in patients with gastrointestinal tract diseases or those who have undergone surgery.

Thiamine deficiency in tachypnoeic Cambodian infants.

BACKGROUND: Beriberi is endemic in South-east Asia. Diagnosis is based on clinical findings, but correlation of clinical features with blood thiamine concentrations is uncertain. OBJECTIVES: To investigate in tachypnoeic Cambodian infants the correlation between whole blood thiamine diphosphate (TDP) concentrations, clinical findings and blood TDP levels after therapy. METHODS: Infants hospitalised with tachypnoea were enrolled from October 2011 to January 2012. Initial clinical features, diagnostic test results and final diagnoses were recorded. Blood for TDP determination was collected prior to treatment and at discharge. Matched infants from the general outpatient clinic with minor complaints were enrolled as controls. Thiamine was administered at the discretion of the treating paediatrician. RESULTS: Of the 47 tachypnoeic and 47 control infants, median initial blood TDP concentrations were 83 and 93 nmol/L, respectively (P = 0·69), and were below the estimated limit of normal (<70 nmol/L) in 43% vs 34% (P = 0·40). Median initial TDP levels were 72 and 91 nmol/L in tachypnoeic infants who did or did not receive thiamine, respectively (P = 0·56); at hospital discharge, median TDP concentration had increased by 107 and 3·5 nmol/L in these two subgroups (P<0·001). Classical findings of beriberi such as dysphonia, tachycardia and hepatomegaly did not correlate with low initial TDP concentrations, but infant age, Tiger Balm use, absence of wheezing and low blood CRP levels were associated with low initial TDP levels. Use of infant formula was associated with higher initial TDP levels. CONCLUSIONS: Thiamine deficiency is common in tachypnoeic Cambodian infants, but routine clinical assessments do not accurately identify those with low blood TDP concentrations. Parenteral thiamine administration markedly increases TDP levels. Empirical thiamine treatment should be considered for tachypnoeic infants in regions with endemic thiamine deficiency.

Thiamine deficiency in tachypnoeic Cambodian infants.

Background: Beriberi is endemic in South-east Asia. Diagnosis is based on clinical findings, but correlation of clinical features with blood thiamine concentrations is uncertain. Objectives: To investigate in tachypnoeic Cambodian infants the correlation between whole blood thiamine diphosphate (TDP) concentrations, clinical findings and blood TDP levels after therapy. Methods: Infants hospitalised with tachypnoea were enrolled from October 2011 to January 2012. Initial clinical features, diagnostic test results and final diagnoses were recorded. Blood for TDP determination was collected prior to treatment and at discharge. Matched infants from the general outpatient clinic with minor complaints were enrolled as controls. Thiamine was administered at the discretion of the treating paediatrician. Results: Of the 47 tachypnoeic and 47 control infants, median initial blood TDP concentrations were 83 and 93 nmol/L, respectively (P = 0·69), and were below the estimated limit of normal (<70 nmol/L) in 43% vs 34% (P = 0·40). Median initial TDP levels were 72 and 91 nmol/L in tachypnoeic infants who did or did not receive thiamine, respectively (P = 0·56); at hospital discharge, median TDP concentration had increased by 107 and 3·5 nmol/L in these two subgroups (P<0·001). Classical findings of beriberi such as dysphonia, tachycardia and hepatomegaly did not correlate with low initial TDP concentrations, but infant age, Tiger Balm use, absence of wheezing and low blood CRP levels were associated with low initial TDP levels. Use of infant formula was associated with higher initial TDP levels. Conclusions: Thiamine deficiency is common in tachypnoeic Cambodian infants, but routine clinical assessments do not accurately identify those with low blood TDP concentrations. Parenteral thiamine administration markedly increases TDP levels. Empirical thiamine treatment should be considered for tachypnoeic infants in regions with endemic thiamine deficiency.