Rapid HPLC measurement of thiamine and its phosphate esters in whole blood

Regulation of thiamine and pyruvate decarboxylase genes by Pdc2 in Nakaseomyces glabratus (Candida glabrata) is complex

Thiamine (vitamin B1) is essential for glucose catabolism. In the yeast species, Nakaseomyces glabratus (formerly Candida glabrata) and Saccharomyces cerevisiae, the transcription factor Pdc2 (with Thi3 and Thi2) upregulates pyruvate decarboxylase (PDC) genes and thiamine biosynthetic and acquisition (THI) genes during starvation. There have not been genome-wide analyses of Pdc2 binding. Previously, we identified small regions of Pdc2-regulated genes sufficient to confer thiamine regulation. Here, we performed deletion analyses on these regions. We observed that when the S. cerevisiae PDC5 promoter is introduced into N. glabratus, it is thiamine starvation inducible but does not require the Thi3 coregulator. The ScPDC5 promoter contains a 22-bp duplication with an AT-rich spacer between the 2 repeats, which are important for regulation. Loss of the first 22-bp element does not eliminate regulation, but the promoter becomes Thi3 dependent, suggesting cis architecture can generate a Thi3-independent, thiamine starvation inducible response. Whereas many THI promoters only have 1 copy of this element, addition of the first 22-bp element to a Thi3-dependent promoter confers Thi3 independence. Finally, we performed fluorescence anisotropy and chromatin immunoprecipitation sequencing. Pdc2 and Thi3 bind to regions that share similarity to the 22-bp element in the ScPDC5 promoter and previously identified cis elements in N. glabratus promoters. Also, while Pdc2 binds to THI and PDC promoters, neither Pdc2 nor Thi3 appears to bind the evolutionarily new NgPMU3 promoter that is regulated by Pdc2. Further study is warranted because PMU3 is required for cells to acquire thiamine from environments where thiamine is phosphorylated, such as in the human bloodstream.

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.

Race explains substantial variance in whole blood thiamine diphosphate concentrations

Deficiency for thiamine (vitamin B1), traditionally assessed via the activity of the thiamine-dependent enzyme erythrocyte transketolase, has been reported in individuals with alcohol use disorder (AUD) and in people with HIV; concentrations of the metabolically active diphosphate form, however, have yet to be reported in HIV cohorts and results in AUD are equivocal. In this cross-sectional study, samples from 170 AUD, 130 HIV, and 100 healthy control individuals were analyzed to test the hypothesis that AUD and HIV groups relative to healthy controls would show low whole blood thiamine diphosphate (TDP) concentrations related to peripheral neuropathy. TDP concentrations were not different in the 3 study groups (P = .6141) but were lower in Black (n = 172) relative to White (n = 155) individuals (P < .0001) regardless of group. In a multiple regression, race relative to diagnoses explained more than 10 times the variance in whole blood TDP concentrations (F4,395 = 3.5, P = .0086; r2 = 15.1]. Performance on a measure of peripheral neuropathy (2-point discrimination) was worse in the HIV and AUD cohorts relative to the healthy control group (P < .0001) but was not associated with TDP concentrations. These findings suggest that Black individuals carry a heightened vulnerability for low whole blood TDP concentrations, but the clinical significance and mechanisms underlying these results remain to be determined.

Assessment of Erythrocyte Transketolase, Whole Blood Thiamine Diphosphate, and Human Milk Thiamine Concentrations to Identify Infants and Young Children Responding Favorably to Therapeutic Thiamine Administration: Findings from the Lao Thiamine Study, a Prospective Cohort Study

Background

There is limited information on relationships among biomarkers of thiamine status (whole blood thiamine diphosphate [ThDP], erythrocyte transketolase activity coefficient [ETKac], and human milk thiamine [MTh]) and clinical manifestations of thiamine deficiency.

Objectives

This study aimed to explore correlations among these biomarkers and thiamine responsive disorders (TRDs), a diagnosis based on favorable clinical response to thiamine.

Methods

Hospitalized infants and young children (aged 21 d to <18 mo) with respiratory, cardiac, and/or neurological symptoms suggestive of thiamine deficiency were treated with parenteral thiamine (100 mg daily) for ≥3 d alongside other treatments and re-examined systematically. Clinical case reports were reviewed by 3 pediatricians, who determined TRD or non-TRD status. Children in a community comparison group were matched by age, sex, and residence. Venous whole blood ThDP and MTh were determined by high-performance liquid chromatography fluorescence detection and ETKac in washed erythrocytes by ultraviolet spectrophotometry. Associations between biomarkers were assessed using Spearman correlations, and biomarker cutoffs predictive of TRD and ETKac >1.25 were explored using area under the receiver operating characteristic curve framework.

Results

Thiamine biomarkers were available for 287 hospitalized children and 228 community children (mean age 4.7 mo; 59.4% male). Median (interquartile range [IQR]) ThDP and ETKac were 66.9 nmol/L (IQR: 41.4, 96.9 nmol/L) and 1.25 nmol/L (IQR: 1.11, 1.48 nmol/L), respectively, among hospitalized children, and 64.1 nmol/L (IQR: 50.0, 85.3 nmol/L) and 1.22 nmol/L (IQR: 1.12, 1.37 nmol/L) among 228 community children (P > 0.05 for both). Forty-five percent of breastfeeding mothers of infants <6 mo had MTh <90 μg/L. ThDP and ETKac, but not MTh, were significantly different between 152 children with TRD and 122 without TRD, but overlapping distributions undermined prediction of individual responses to thiamine.

Conclusions

Although ETKac, ThDP, and MTh are useful biomarkers of population thiamine status, none of the biomarkers reliably identified individual children with TRD. ThDP is more practical for population assessment because preparing washed erythrocytes is not required.This trial was registered at clinicaltrials.gov as NCT03626337.

THI3 contributes to isoamyl alcohol biosynthesis through thiamine diphosphate homeostasis

Isoamyl alcohol is a precursor of isoamyl acetate, an aromatic compound that imparts the ginjo aroma to sake. The isoamyl alcohol biosynthesis pathway in yeasts involves the genes PDC1, PDC5, PDC6, ARO10, and THI3 encoding enzymes that decarboxylate α-ketoisocaproic acid to isovaleraldehyde. Among these genes, THI3 is the main gene involved in isoamyl alcohol biosynthesis. Decreased production of isoamyl alcohol has been reported in yeast strains with disrupted THI3 (Δthi3). However, it has also been reported that high THI3 expression did not enhance decarboxylase activity. Therefore, the involvement of THI3 in isoamyl alcohol biosynthesis remains unclear. In this study, we investigated the role of THI3 in isoamyl alcohol biosynthesis. While reproducing previous reports of reduced isoamyl alcohol production by the Δthi3 strain, we observed that the decrease in isoamyl alcohol production occurred only at low yeast nitrogen base concentrations in the medium. Upon investigating individual yeast nitrogen base components, we found that the isoamyl alcohol production by the Δthi3 strain reduced when thiamine concentrations in the medium were low. Under low-thiamine conditions, both thiamine and thiamine diphosphate (TPP) levels decreased in Δthi3 cells. We also found that the decarboxylase activity of cell-free extracts of the Δthi3 strain cultured in a low-thiamine medium was lower than that of the wild-type strain, but was restored to the level of the wild-type strain when TPP was added. These results indicate that the loss of THI3 lowers the supply of TPP, a cofactor for decarboxylases, resulting in decreased isoamyl alcohol production.

Risk factors for anaemia among women and their young children hospitalised with suspected thiamine deficiency in northern Lao PDR

Anaemia among women and young children remains a major public health concern. This secondary study describes the anaemia prevalence among young hospitalised children and their mothers in northern Lao People's Democratic Republic and explores possible nutritional causes and risk factors for anaemia. Hospitalised children (ages 21 days to <18 months) with clinical symptoms suggestive of thiamine deficiency disorders were eligible along with their mothers. Venous blood was collected for determination of haemoglobin, ferritin, soluble transferrin receptor (sTfR), retinol-binding protein (RBP), erythrocyte glutathione reductase activation coefficient (EGRac), thiamine diphosphate (ThDP) and acute phase proteins. Risk factors for anaemia were modelled using minimally adjusted logistic regression controlling for age. Haemoglobin results were available for 436 women (mean ± SD age 24.7 ± 6.4 years; 1.6% pregnant) and 427 children (4.3 ± 3.5 months; 60.3% male). Anaemia prevalence (Hb < 120 g/L for nonpregnant women and <110 g/L for pregnant women and children) was 30.7% among women and 55.2% among children. In bivariate analyses, biomarkers significantly associated with anaemia in women were ferritin, sTfR, RBP, EGRac and ThDP. Other risk factors for women were lower BMI, mid-upper arm circumference < 23.5 cm, lower education, lower socioeconomic index, food insecurity, Hmong ethnicity, not/rarely having attended antenatal care, not having taken antenatal iron-containing supplements and not meeting minimum dietary diversity. Risk factors for anaemia among children were older age, male sex, stunting, sTfR, ThDP and alpha-1-acid-glycoprotein. Anaemia was common among women and their hospitalised children and was associated with micronutrient deficiencies and socioeconomic, dietary and health care-seeking risk factors, suggesting that multiple strategies are required to prevent anaemia among women and children.

Wernicke encephalopathy: limitations in a laboratory and radiological diagnosis

Wernicke encephalopathy is an emergent neurological disorder caused by vitamin B1 (thiamine) deficiency. Here, we present a case of Wernicke encephalopathy in a male patient in his 70s with normal serum thiamine levels and MRI findings on admission. He had a history of heavy alcohol consumption and a gradual decrease in food intake. On arrival at the hospital, his consciousness was impaired which persisted even after glucose replacement. Moreover, horizontal nystagmus and cerebellar ataxia were observed. Head CT scan and MRI revealed no abnormal findings. Further, his serum thiamine level was within the normal range. The patient was clinically diagnosed with Wernicke encephalopathy, and high-dose thiamine therapy was started. Then, his symptoms improved immediately. Thus, in case of clinical suspicion, treatment for Wernicke encephalopathy must be initiated promptly even in patients with normal serum thiamine levels.

Effect of adjuvant thiamine and ascorbic acid administration on the neurologic outcomes of out-of-hospital cardiac arrest patients: A before-and-after study

AIM

This study aimed to evaluate the impact of early thiamine and ascorbic acid administration on the neurologic outcome in out-of-hospital cardiac arrest (OHCA) patients treated with targeted temperature management (TTM).

METHODS

This before-and-after cohort study used data extracted from two hospitals of the Korean Hypothermia Network prospective registry. The treatment group incorporated patients enrolled from December 2019 to May 2021, that received intravenous thiamine (200 mg) and ascorbic acid (3 g) at 12-hour intervals for a total of six doses. The control group incorporated those enrolled from May 2018 to November 2019. The one-month good neurologic outcome, defined as a Cerebral Performance Category score ≤ 2, between the groups was evaluated using inverse probability of treatment weighting (IPTW).

RESULTS

Among the 234 OHCA survivors with TTM, 102 were included in the treatment group and 132 were included in the control group. The one-month (31.4 % vs. 29.5 %, respectively; P = 0.76) good neurologic outcome rates did not differ between the treatment and control groups. After adjusting using the IPTW, vitamin supplementation was not associated with good neurologic outcome (odds ratio [OR], 1.134; 95 % confidence interval [CI], 0.644-1.999; P = 0.66). In subgroup analysis, vitamin administration was significantly associated with a good neurologic outcome in older (≥65 years) patients (adjusted OR, 5.53; 95 % CI, 1.21-25.23; P = 0.03).

CONCLUSION

Adjuvant thiamine and ascorbic acid administration in OHCA survivors with TTM did not improve their neurologic outcome after one month. Further clinical trials are warranted.

Alcohol-Related Metabolic Emergencies

Patients with alcohol use disorders are commonly identified and managed in the emergency department. Although the alcohol-intoxicated patient has a high risk for significant injury and diseases, the majority will be allowed to sober in the emergency department and can be discharged without incident. However, there are metabolic derangements in these patients, such as alcoholic ketoacidosis, Wernicke-Korsakoff, and potomania that very commonly present similar to intoxication and can be misdiagnosed by emergency clinicians.

Pyruvate decarboxylase and thiamine biosynthetic genes are regulated differently by Pdc2 in S. cerevisiae and C. glabrata

Understanding metabolism in the pathogen Candida glabrata is key to identifying new targets for antifungals. The thiamine biosynthetic (THI) pathway is partially defective in C. glabrata, but the transcription factor CgPdc2 upregulates some thiamine biosynthetic and transport genes. One of these genes encodes a recently evolved thiamine pyrophosphatase (CgPMU3) that is critical for accessing external thiamine. Here, we demonstrate that CgPdc2 primarily regulates THI genes. In Saccharomyces cerevisiae, Pdc2 regulates both THI and pyruvate decarboxylase (PDC) genes, with PDC proteins being a major thiamine sink. Deletion of PDC2 is lethal in S. cerevisiae in standard growth conditions, but not in C. glabrata. We uncover cryptic cis elements in C. glabrata PDC promoters that still allow for regulation by ScPdc2, even when that regulation is not apparent in C. glabrata. C. glabrata lacks Thi2, and it is likely that inclusion of Thi2 into transcriptional regulation in S. cerevisiae allows for a more complex regulation pattern and regulation of THI and PDC genes. We present evidence that Pdc2 functions independent of Thi2 and Thi3 in both species. The C-terminal activation domain of Pdc2 is intrinsically disordered and critical for species differences. Truncation of the disordered domains leads to a gradual loss of activity. Through a series of cross species complementation assays of transcription, we suggest that there are multiple Pdc2-containing complexes, and C. glabrata appears to have the simplest requirement set for THI genes, except for CgPMU3. CgPMU3 has different cis requirements, but still requires Pdc2 and Thi3 to be upregulated by thiamine starvation. We identify the minimal region sufficient for thiamine regulation in CgTHI20, CgPMU3, and ScPDC5 promoters. Defining the cis and trans requirements for THI promoters should lead to an understanding of how to interrupt their upregulation and provide targets in metabolism for antifungals.

Ataxias: Hereditary, Acquired, and Reversible Etiologies

A variety of etiologies can cause cerebellar dysfunction, leading to ataxia symptoms. Therefore, the accurate diagnosis of the cause for cerebellar ataxia can be challenging. A step-wise investigation will reveal underlying causes, including nutritional, toxin, immune-mediated, genetic, and degenerative disorders. Recent advances in genetics have identified new genes for both autosomal dominant and autosomal recessive ataxias, and new therapies are on the horizon for targeting specific biological pathways. New diagnostic criteria for degenerative ataxias have been proposed, specifically for multiple system atrophy, which will have a broad impact on the future clinical research in ataxia. In this article, we aim to provide a review focus on symptoms, laboratory testing, neuroimaging, and genetic testing for the diagnosis of cerebellar ataxia causes, with a special emphasis on recent advances. Strategies for the management of cerebellar ataxia is also discussed.

Thiamine deficiency in pregnancy and lactation: implications and present perspectives

During pregnancy, many physiologic changes occur in order to accommodate fetal growth. These changes require an increase in many of the nutritional needs to prevent long-term consequences for both mother and the offspring. One of the main vitamins that are needed throughout the pregnancy is thiamine (vitamin B1) which is a water-soluble vitamin that plays an important role in many metabolic and physiologic processes in the human body. Thiamine deficiency during pregnancy can cause can have many cardiac, neurologic, and psychological effects on the mother. It can also dispose the fetus to gastrointestinal, pulmonological, cardiac, and neurologic conditions. This paper reviews the recently published literature about thiamine and its physiologic roles, thiamine deficiency in pregnancy, its prevalence, its impact on infants and subsequent consequences in them. This review also highlights the knowledge gaps within these topics.

Fact-based nutrition for infants and lactating mothers-The NUTRISHIELD study

Background

Human milk (HM) is the ideal source of nutrients for infants. Its composition is highly variable according to the infant's needs. When not enough own mother's milk (OMM) is available, the administration of pasteurized donor human milk (DHM) is considered a suitable alternative for preterm infants. This study protocol describes the NUTRISHIELD clinical study. The main objective of this study is to compare the % weight gain/month in preterm and term infants exclusively receiving either OMM or DHM. Other secondary aims comprise the evaluation of the influence of diet, lifestyle habits, psychological stress, and pasteurization on the milk composition, and how it modulates infant's growth, health, and development.

Methods and design

NUTRISHIELD is a prospective mother-infant birth cohort in the Spanish-Mediterranean area including three groups: preterm infants <32 weeks of gestation (i) exclusively receiving (i.e., >80% of total intake) OMM, and (ii) exclusively receiving DHM, and (iii) term infants exclusively receiving OMM, as well as their mothers. Biological samples and nutritional, clinical, and anthropometric characteristics are collected at six time points covering the period from birth and until six months of infant's age. The genotype, metabolome, and microbiota as well as the HM composition are characterized. Portable sensor prototypes for the analysis of HM and urine are benchmarked. Additionally, maternal psychosocial status is measured at the beginning of the study and at month six. Mother-infant postpartum bonding and parental stress are also examined. At six months, infant neurodevelopment scales are applied. Mother's concerns and attitudes to breastfeeding are registered through a specific questionnaire.

Discussion

NUTRISHIELD provides an in-depth longitudinal study of the mother-infant-microbiota triad combining multiple biological matrices, newly developed analytical methods, and ad-hoc designed sensor prototypes with a wide range of clinical outcome measures. Data obtained from this study will be used to train a machine-learning algorithm for providing dietary advice to lactating mothers and will be implemented in a user-friendly platform based on a combination of user-provided information and biomarker analysis. A better understanding of the factors affecting milk's composition, together with the health implications for infants plays an important role in developing improved strategies of nutraceutical management in infant care.

Clinical trial registration

https://register.clinicaltrials.gov, identifier: NCT05646940.

The effect of cardiopulmonary bypass on blood thiamine concentration and its association with post-operative lactate concentration

Objective

Cardiothoracic surgery is a large field in Australia, and evidence suggests post-cardiopulmonary bypass (CPB) hyperlactataemia is associated with higher morbidity and mortality. Low thiamine levels are a potentially common yet treatable cause of hyperlactataemia and may occur in the setting of exposure to CPB non-biological material. We hypothesized that cardiopulmonary bypass would result in decreased whole-blood thiamine levels, which may therefore result in increased whole-blood lactate levels in the post-operative period.

Methods

Adult patients undergoing non-emergent CPB were recruited in a single centre, prospective, analytic observational study at Townsville University Hospital, Australia. The primary outcome was a comparison of pre- and post-CPB thiamine diphosphate level, secondarily aiming to assess any relationship between lactate and thiamine levels. Prospective pre- and post-CPB blood samples were taken and analysed at a central reference laboratory.

Results

Data was available for analysis on 78 patients. There was a statistically significant increase in thiamine diphosphate level from pre-CPB: 1.36 nmol/g Hb, standard deviation (SD) 0.31, 95% confidence intervals (CI) 1.29–1.43, to post-CPB: 1.77 nmol/g Hb, SD 0.53, 95% CI 1.43–1.88, p value < 0.001. There was a non-statistically significant (p > 0.05) trend in rising whole-blood lactate levels with increasing time. Analysis of lactate levels at varying time periods found a significant difference between baseline measurements and increased levels at 13–16 h (p < 0.05). There was no significant relationship observed between whole-blood thiamine levels and post-operative lactate levels.

Conclusion

Whole-blood thiamine levels were found to increase immediately post-CPB in those undergoing elective cardiac surgery. There was no correlation between whole-blood thiamine levels and post-operative arterial lactate levels.

Evaluation of blood thiamine concentration in hospitalized dogs with and without critical illness

OBJECTIVE

To evaluate blood thiamine concentration in healthy and critically ill hospitalized dogs over 72 hours of hospitalization and to identify any association of thiamine concentration with patient morbidity and mortality.

DESIGN

Prospective, observational, clinical study.

SETTING

University veterinary teaching hospital.

ANIMALS

Thirty-one hospitalized healthy dogs and 37 dogs with critical illness. Dogs with critical illness had nonseptic (n = 24) or septic (n = 13) etiologies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Whole blood EDTA samples were collected within 24 hours of admission and 72 hours later. Samples were stored at -80°C and batch analyzed. Total thiamine (tB1) and thiamine diphosphate (TDP) concentrations were measured using high-performance liquid chromatography, and free thiamine concentration was determined using liquid chromatography with tandem mass spectrometry. Collected patient data included CBC, biochemistry profile, plasma lactate concentration, shock index, Acute Patient Physiologic and Laboratory Evaluation Score (APPLE_fast ) score, comorbid conditions, and patient outcome. Approximately 92% of tB1 present in whole blood is measured as TDP. TDP concentration was strongly correlated with tB1 (R = 0.97, P < 0.0001). Thiamine concentration, represented by TDP, was not different at admission or at 72 hours in all dogs. TDP concentration was lower in septic dogs requiring surgery at admission (P = 0.044) and 72 hours later (P = 0.008), compared to dogs not requiring surgery. TDP concentration was not different between dogs with and without stable chronic diseases at any time point. Older dogs had lower TDP concentration. Positive correlations were seen between TDP and body weight, APPLE_fast score, and WBC count. Critically ill dogs with lower admission plasma lactate concentration were more likely to have an increase in thiamine over time (P = 0.0142).

CONCLUSIONS

Differences in thiamine concentration were not identified in hospitalized healthy or critically ill dogs. Further investigation into the clinical relevance of thiamine deficiency is indicated in septic dogs undergoing surgery.

Thiamine Level in Out-of-hospital Cardiac Arrest Patients

BACKGROUND: Thiamine deficiency is more common in critically ill patients. Administration of thiamine in cardiac arrest mice has improved survival and neurological outcomes. Evidence for thiamine deficiency in cardiac arrest humans is insufficient to support routine use of thiamine in cardiac arrest patients. AIM: This study aimed to determine thiamine blood levels in cardiac arrest patients to understand whether the presence of thiamine deficiency is common in cardiac arrest patients. METHODS: A prospective descriptive study from April 2017 to March 2018, on 24 adult out-of-hospital cardiac arrest patients. We used the high-performance liquid chromatography technique to determine whole blood thiamine pyrophosphate levels in cardiac arrest patients who arrived at the emergency department within 1 h of the onset of a cardiac arrest. RESULTS: The mean thiamine pyrophosphate level within 1 h of the onset of a cardiac arrest was 170.9 ± 56.7 nmol/L. Only one participant had thiamine deficiency according to the cut-off level for thiamine pyrophosphate in whole blood of <70 nmol/L. Fourteen patients had spontaneous return of circulation. Thiamine pyrophosphate levels were not different between the two groups of patients who had and did not have the return of spontaneous circulation at the emergency department. CONCLUSION: Little evidence was found to support thiamine deficiency as a feature among our cardiac arrest patients. A study with a larger population is required for more meaningful statistical analysis. As there is no consensus on cut-off level for thiamine deficiency diagnosis, the level of thiamine pyrophosphate in specific populations should be evaluated to establish reference values.

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

This review summarizes the current knowledge on essential vitamins B1, B2, B3, and B5. These B-complex vitamins must be taken from diet, with the exception of vitamin B3, that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B3, is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

Hiding in Plain Sight: Modern Thiamine Deficiency

Thiamine or vitamin B1 is an essential, water-soluble vitamin required for mitochondrial energetics—the production of adenosine triphosphate (ATP). It is a critical and rate-limiting cofactor to multiple enzymes involved in this process, including those at the entry points and at critical junctures for the glucose, fatty acid, and amino acid pathways. It has a very short half-life, limited storage capacity, and is susceptible to degradation and depletion by a number of products that epitomize modern life, including environmental and pharmaceutical chemicals. The RDA for thiamine is 1.1–1.2 mg for adult females and males, respectively. With an average diet, even a poor one, it is not difficult to meet that daily requirement, and yet, measurable thiamine deficiency has been observed across multiple patient populations with incidence rates ranging from 20% to over 90% depending upon the study. This suggests that the RDA requirement may be insufficient to meet the demands of modern living. Inasmuch as thiamine deficiency syndromes pose great risk of chronic morbidity, and if left untreated, mortality, a more comprehensive understanding thiamine chemistry, relative to energy production, modern living, and disease, may prove useful.

Comparative studies on vitamin B1 deficiency inwholeblood of chronically haemodialysed patients: chromatographic, fluorimetricandPCAstudy

The levels of thiamine diphosphate (ThDP), the most active biologically form of vitamin B₁, were assessed in whole blood oflong-term haemodialysed patients (n = 50), by applying chromatographic methods based on RP-HPLC technique with isocratic elution and fluorescence detection. The target analyte, thiochrome diphosphate (ThODP), was obtained by pre-column derivatization of vitamin B₁ contained in blood samples, applying deproteination with trichloroacetic acid, following by oxidation with alkaline solution of potassium ferricyanide(III) and stabilization with DTT before assays. A simple and sensitive assay was developed, and the results were referenced to the commercially available test. Steady-state and time-resolved studies on emissive properties of ThODP enabled optimization of the proposed assay. The F-Snedecor test shown no statistically significant differences between both approaches. Assessed parameters of the proposed assay, such as linearity, precision, sensitivity, and recovery, were satisfactory if compared to the reference one. The LOQ value for ThDP in whole blood of studied group of patients was of 0.5 ng/mL and the recovery of88%. The results disclosed high individual variabilities in the interdialytic deficiencies of ThDP among the patients - ranged from afew percent to values close to 100%. A comprehensive clinical data, characterizing patients under study, were processed together, and analysed by employing achemometric discriminative tool, the Principal Components Analysis,to find interdependences among clinical data characterizing patients. The three Principal Components were disclosed, that in sum explained almost 50% of the observed variability of the clinical data set. Among the clinical parameters involved in PCs were dialyzer membrane and type, duration as well as levels of creatinine, haemoglobin, and red blood cells in patients' whole blood.

Co-cultivation of Streptomyces and microalgal cells as an efficient system for biodiesel production and bioflocculation formation

The phytohormone producing Streptomyces rosealbus MTTC 12,951 (S.R) and green microalga Chlorella vulgaris MSU-AGM 14 (C.V) were cultivated in co-culture system to evaluate exogenous hormonal activity. Biosynthesis of indole-3-acetic acid (IAA) and their precursors were quantitatively evaluated by employing High Performance Liquid Chromatography (HPLC). The concentration of IAA (0.72 ± 0.02 µg mL^-1) was observed to be elevated in co-cultivation system due to symbiotic interaction between Streptomyces and microalgae. In exchange, microalgae produced adequate volume of tryptophan (Trp) to induce IAA biosynthesis. The Trp stress in late exponential phase encouraged lipid accumulation (175 ± 10 mg g^-1). The bioflocculation property of microalgae ensures potential and economic viable harvesting process by reducing 148% input energy compared to conventional method. The overall results evidenced that C.V co-cultivation with S.R exhibits promotional behavior and serves as a promising cultivation process for microalgae in terms of cost efficiency and energy conservation.

How is vitamin B1 oxidized to thiochrome? Elementary processes revealed by a DFT study

The oxidation reaction of thiamine (vitamin B1) to thiochrome was investigated by DFT calculations. Three reaction systems, [A] thiamine + methyl peroxy radical + (H2O)8, [B] thiamine + cyanogen bromide + HO-(H2O)8 and [C] thiamine + mercury(ii) chloride + HO-(H2O)8, were investigated. wB97X-D/6-311+G** for [A] and [B] and wB97X-D/SDD&6-311(+)G** for [C] geometry optimizations were carried out with the solvent effect (water). The effect is of the self-consistent reaction field (SCRF) with the polarizable continuum model (PCM). In [A], the H3C-O2˙ adduct of thiamine undergoes simultaneous cleavage of the C-H and O-O bonds, leading to a very stable 2(3H)-thiazolone intermediate. The same intermediate was obtained after the cleavage of the C-H and O-H bonds of the HO adduct of thiamine in [B] and [C]. After the formation of the key intermediate, the N-protonated thiochrome was afforded via three steps. In reflection of the water-soluble character of vitamin B1, proton transfers along hydrogen bonds of the water cluster enhance those steps.

Low-dose thiamine supplementation of lactating Cambodian mothers improves human milk thiamine concentrations: a randomized controlled trial

BACKGROUND

Infantile beriberi-related mortality is still common in South and Southeast Asia. Interventions to increase maternal thiamine intakes, and thus human milk thiamine, are warranted; however, the required dose remains unknown.

OBJECTIVES

We sought to estimate the dose at which additional maternal intake of oral thiamine no longer meaningfully increased milk thiamine concentrations in infants at 24 wk postpartum, and to investigate the impact of 4 thiamine supplementation doses on milk and blood thiamine status biomarkers.

METHODS

In this double-blind, 4-parallel arm randomized controlled dose-response trial, healthy mothers were recruited in Kampong Thom, Cambodia. At 2 wk postpartum, women were randomly assigned to consume 1 capsule, containing 0, 1.2 (estimated average requirement), 2.4, or 10 mg of thiamine daily from 2 through 24 weeks postpartum. Human milk total thiamine concentrations were measured using HPLC. An Emax curve was plotted, which was estimated using a nonlinear least squares model in an intention-to-treat analysis. Linear mixed-effects models were used to test for differences between treatment groups. Maternal and infant blood thiamine biomarkers were also assessed.

RESULTS

In total, each of 335 women was randomly assigned to1 of the following thiamine-dose groups: placebo (n = 83), 1.2 mg (n = 86), 2.4 mg (n = 81), and 10 mg (n = 85). The estimated dose required to reach 90% of the maximum average total thiamine concentration in human milk (191 µg/L) is 2.35 (95% CI: 0.58, 7.01) mg/d. The mean ± SD milk thiamine concentrations were significantly higher in all intervention groups (183 ± 91, 190 ± 105, and 206 ± 89 µg/L for 1.2, 2.4, and 10 mg, respectively) compared with the placebo group (153 ± 85 µg/L; P < 0.0001) and did not significantly differ from each other.

CONCLUSIONS

A supplemental thiamine dose of 2.35 mg/d was required to achieve a milk total thiamine concentration of 191 µg/L. However, 1.2 mg/d for 22 wk was sufficient to increase milk thiamine concentrations to similar levels achieved by higher supplementation doses (2.4 and 10 mg/d), and comparable to those of healthy mothers in regions without beriberi. This trial was registered at clinicaltrials.gov as NCT03616288.

Engineering Allosteric Ribozymes to Detect Thiamine Pyrophosphate in Whole Blood

Thiamine deficiency contributes to several human diseases including Alzheimer's. As its biologically active form, thiamine pyrophosphate (TPP) has been considered as a potential biomarker for Alzheimer's disease (AD) based on several clinical reports that apparently lower blood TPP levels were found in patients with mild cognitive impairment to AD. However, highly sensitive and high-throughput detection of TPP in biological fluids remains an analytical challenge. Here, we report engineering RNA-based sensors to quantitatively measure TPP concentrations in whole blood samples with a detection limit down to a few nM. By fusing a TPP-specific aptamer with the hammerhead ribozyme for in vitro selection, we isolated an allosteric ribozyme with an EC₅₀ value (68 nM) similar to the aptamer's K_D value (50 nM) for TPP, which for the first time demonstrates the possibility to maintain the effector binding affinity of the aptamer in such engineered allosteric RNA constructs. Meanwhile, we developed a new blood sample preparation protocol to be compatible with RNA. By coupling the TPP-induced ribozyme cleavage event with isothermal amplification, we achieved fluorescence monitoring of whole blood TPP levels through the "mix-and-read" operation with high-throughput potential. We expect that the engineered TPP-sensing RNAs will facilitate clinical research on AD as well as other thiamine-related diseases.

Thiamine Status in Children with Septic Shock from a Developing Country: A Prospective Case-Control Study

OBJECTIVE

Mitochondrial dysfunction is central to sepsis-induced multi-organ dysfunction. Thiamine deficiency may contribute to mitochondrial dysfunction and thus high mortality. Study was planned to assess thiamine status in children with septic shock in comparison to healthy controls from a developing country and to study the effect of thiamine levels on its outcome.

METHODS

A prospective case-control study (April 2017 to May 2018) enrolling consecutive children with septic shock as 'cases' (n = 76), their healthy siblings (n = 51) and apparently healthy children from immunization clinic (n = 35) as 'controls'. Whole blood total thiamine (WBTT) level was measured on days 1, 10 and 1-month post-discharge. Outcome parameters were acute care area free days on days 14 and 28, and mortality.

RESULTS

WBTT [nMol/l; median (interquartile range, IQR)] was significantly lower on day 1 in cases compared with sibling controls [23.1 (21.8-26.3) vs. 36.9 (33.6-40.5); p < 0.001]. It fell further on day 10 [20.8 (18.1-21.1); p < 0.02]. Levels rose significantly 1-month post-discharge [35.5 (31.2-36.6)] and became comparable to sibling controls (p = 0.4). Immunization clinic controls also had lower WBTT [42.3 (40.1-45.9)], but was significantly higher than sibling controls and cases at 1-month post-discharge (p < 0.001). Survivors and non-survivors of septic shock were similar. WBTT levels did not correlate with any of the severity indicators of septic shock or its outcomes.

CONCLUSIONS

WBTT was significantly low in all children, and fell further during septic shock. Observed severe deficiency might have precluded any further association of thiamine levels with severity of septic shock and its outcome. Data obtained may inform trials on metabolic resuscitation in paediatric septic shock in developing countries. Lay summaryThiamine deficiency may contribute to high mortality in paediatric septic shock as thiamine is an essential factor for functioning of mitochondria, the powerhouse of the cells. This prospective case-control study was conducted to assess thiamine status in children with septic shock in comparison with healthy controls in a developing country. Consecutive children with fluid-refractory septic shock were enrolled as 'cases'. Their apparently healthy siblings, and apparently healthy children from immunization clinic, were enrolled as 'controls'. The whole blood total thiamine (WBTT) level was measured on days 1, 10 and 1 month after hospital discharge. Seventy-six children were enrolled as cases, 51 children as sibling controls and 35 children as immunization clinic controls. WBTT was significantly lower on day 1 in cases as compared with their sibling controls. It fell further on day 10. The level rose significantly after a month of discharge and became comparable to sibling controls. Immunization clinic controls also had lower WBTT but was significantly higher compared with sibling controls and cases at 1-month post-discharge. Survivors and non-survivors of septic shock had similar WBTT levels. Observed severe deficiency might have precluded any further association of thiamine levels with septic shock outcome.

Association between thiamine deficiency and hyperlactatemia among critically ill patients with diabetes infected by SARS-CoV-2

BACKGROUND

The present study aims to verify the association between diabetes and thiamine deficiency in critically ill patients infected by severe acute respiratory syndrome coronavirus 2.

METHODS

This is a descriptive cross-sectional study, whose demographic, anthropometric, and laboratory data (arterial lactate, bicarbonate, and plasma thiamine) were obtained in the first hours of admission to the intensive care unit. Patients with diabetes were compared with individuals without diabetes, and the correlation was performed between thiamine and lactate levels. Thiamine levels <28 μg/L were considered as thiamine deficiency.

RESULTS

Overall, 270 patients met the inclusion criteria; 51.1% were men, and the median age was 74 years (66.8-81). The median value of thiamine was 54.0 μg/L (38-72.3), and 15.6% had thiamine deficiency. Among patients with diabetes, 26.3% had thiamine deficiency, and 69.3% had hyperlactatemia. There was an association between thiamine deficiency and diabetes (odds ratio 4.28; 95% CI, 2.08-8.81; P < .001). There was a strong negative correlation between thiamine and arterial lactate in patients with diabetes (r = -0.711, P < .001) and a moderate negative correlation in critically ill patients without diabetes (r = -0.489, P < .001).

CONCLUSIONS

The prevalence of thiamine deficiency in critically ill patients due to coronavirus disease 2019 is higher in patients with diabetes. There is a negative correlation between thiamine and arterial lactate levels, which is higher in people with diabetes.

Effects of thiamine on vasopressor requirements in patients with septic shock: a prospective randomized controlled trial

Background

Thiamine, an essential vitamin for aerobic metabolism and glutathione cycling, may decrease the effects of critical illnesses. The objective of this study was to determine whether intravenous thiamine administration can reduce vasopressor requirements in patients with septic shock.

Methods

This study was a prospective randomized double-blind placebo-controlled trial. We included adult patients with septic shock who required a vasopressor within 1–24 h after admission between March 2018 and January 2019 at a tertiary hospital in Thailand. Patients were divided into two groups: those who received 200 mg thiamine or those receiving a placebo every 12 h for 7 days or until hospital discharge. The primary outcome was the number of vasopressor-free days over 7 days. The pre-defined sample size was 31 patients per group, and the study was terminated early due to difficult recruitment.

Results

Sixty-two patients were screened and 50 patients were finally enrolled in the study, 25 in each group. There was no difference in the primary outcome of vasopressor-free days within the 7-day period between the thiamine and placebo groups (mean: 4.9 days (1.9) vs. 4.0 days (2.7), p = 0.197, mean difference − 0.9, 95% CI (− 2.9 to 0.5)). However, the reductions in lactate (p = 0.024) and in the vasopressor dependency index (p = 0.02) at 24 h were greater among subjects who received thiamine repletion vs. the placebo. No statistically significant difference was observed in SOFA scores within 7 days, vasopressor dependency index within 4 days and 7 days, or 28-day mortality.

Conclusions

Thiamine was not associated to a significant reduction in vasopressor-free days over 7-days in comparison to placebo in patients with septic shock. Administration of thiamine could be associated with a reduction in vasopressor dependency index and lactate level within 24 h. The study is limited by early stopping and low sample size.

Trial registration

TCTR, TCTR20180310001. Registered 8 March 2018, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=3330.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12871-020-01195-4.

A novel PET tracer 18F-deoxy-thiamine: synthesis, metabolic kinetics, and evaluation on cerebral thiamine metabolism status

Background

Some neuropsychological diseases are associated with abnormal thiamine metabolism, including Korsakoff–Wernicke syndrome and Alzheimer’s disease. However, in vivo detection of the status of brain thiamine metabolism is still unavailable and needs to be developed.

Methods

A novel PET tracer of ¹⁸F-deoxy-thiamine was synthesized using an automated module via a two-step route. The main quality control parameters, such as specific activity and radiochemical purity, were evaluated by high-performance liquid chromatography (HPLC). Radiochemical concentration was determined by radioactivity calibrator. Metabolic kinetics and the level of ¹⁸F-deoxy-thiamine in brains of mice and marmosets were studied by micro-positron emission tomography/computed tomography (PET/CT). In vivo stability, renal excretion rate, and biodistribution of ¹⁸F-deoxy-thiamine in the mice were assayed using HPLC and γ-counter, respectively. Also, the correlation between the retention of cerebral ¹⁸F-deoxy-thiamine in 60 min after injection as represented by the area under the curve (AUC) and blood thiamine levels was investigated.

Results

The ¹⁸F-deoxy-thiamine was stable both in vitro and in vivo. The uptake and clearance of ¹⁸F-deoxy-thiamine were quick in the mice. It reached the max standard uptake value (SUVmax) of 4.61 ± 0.53 in the liver within 1 min, 18.67 ± 7.04 in the kidney within half a minute. The SUV dropped to 0.72 ± 0.05 and 0.77 ± 0.35 after 60 min of injection in the liver and kidney, respectively. After injection, kidney, liver, and pancreas exhibited high accumulation level of ¹⁸F-deoxy-thiamine, while brain, muscle, fat, and gonad showed low accumulation concentration, consistent with previous reports on thiamine distribution in mice. Within 90 min after injection, the level of ¹⁸F-deoxy-thiamine in the brain of C57BL/6 mice with thiamine deficiency (TD) was 1.9 times higher than that in control mice, and was 3.1 times higher in ICR mice with TD than that in control mice. The AUC of the tracer in the brain of marmosets within 60 min was 29.33 ± 5.15 and negatively correlated with blood thiamine diphosphate levels (r = − 0.985, p = 0.015).

Conclusion

The ¹⁸F-deoxy-thiamine meets the requirements for ideal PET tracer for in vivo detecting the status of cerebral thiamine metabolism.

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.

Thiamine Level in Type I and Type II Diabetes Mellitus Patients: A Comparative Study Focusing on Hematological and Biochemical Evaluations

Objective Diabetes has been found to be associated with low levels of thiamine stores in the body, as thiamine directly affects carbohydrate metabolism. Amplified renal clearance of thiamine has been found in both type I and type II diabetic patients. It has been shown that high-dose thiamine therapy may have a therapeutic effect on early-stage diabetic nephropathy. The aim of this study was to evaluate various biochemical parameters and serum thiamine levels in type I and type II diabetic patients and compare them with a healthy control group. Methods A case-control study was carried out in the diabetic out-patient multi-centers in Karachi. A total of 90 participants were selected by using a non-probability convenient sampling technique and divided into three groups, each with 30 subjects. Group A included healthy non-diabetic subjects, while group B included subjects with type I diabetes mellitus (DM), and group C included subjects with type II DM. After receiving informed consent, blood samples were collected from all the participants for hematological and biochemical evaluation. The duration of the study was eight months. Results The study results revealed that the patients with type II DM had significantly higher mean fasting blood sugar (FBS), random blood sugar (RBS), and hemoglobin A1c (HbA1c) levels than those with type I DM or the control group (p<0.001 for all). Furthermore, the patients with type I or II DM had significantly higher mean levels of triglyceride (p<0.001) and total cholesterol (0.013) while significantly lower mean levels of high-density lipoprotein (HDL) (p=0.014) than controls. The study results further revealed that the patients with type I or II DM had significantly lower serum thiamine levels than controls (14.89±4.82 and 7.35±1.90 vs. 69.56±12.75, p<0.001). Conclusion The study results revealed that FBS, RBS, HbA1c, triglyceride, and total cholesterol levels were significantly higher in both type I and type II diabetes patients compared to controls. Furthermore, HDL and serum thiamine levels were found to be significantly lower in both type I and type II diabetic patients than in controls.

Prevalence of Low Plasma Vitamin B1 in the Stroke Population Admitted to Acute Inpatient Rehabilitation

OBJECTIVE

To determine the prevalence of vitamin B1 (VitB1) deficiency in the stroke population admitted to acute inpatient rehabilitation.

DESIGN

Retrospective cohort study.

SETTING

Acute inpatient rehabilitation facility at an academic medical center.

PARTICIPANTS

119 consecutive stroke patients admitted to stroke service from 1 January 2018 to 31 December 2018.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Plasma VitB1 level.

RESULTS

There were 17 patients (14%; 95% CI 9-22%) with low VitB1 with a range of 2-3 nmol/L, an additional 58 (49%; CI 40-58%) patients had normal low VitB1 with a range of 4-9 nmol/L, twenty-five patients (21%; CI 15-29%) had normal high VitB1 with a range of 10-15 nmol/L, and nineteen patients (16%; CI 10-24%) had high VitB1 with a range of 16-43 nmol/L.

CONCLUSIONS

In this cohort of patients admitted to the stroke service at an acute rehabilitation facility, there is evidence of thiamine deficiency. Moreover, the data suggest that there is inadequate acute intake of VitB1. Given the role of thiamine deficiency in neurologic function, further study of the role of thiamine optimization in the acute stroke rehabilitation population is warranted.

A high performance liquid chromatography fluorescence method for the analysis of both pyridoxal-5-phosphate and thiamine pyrophosphate in whole blood

BACKGROUND AND AIMS

The active coenzymes of the water soluble vitamins B1 and B6 (thiamine pyrophosphate (TPP) and pyridoxal-5-phosphate (P5P) respectively) play an important role in numerous bodily functions. The simultaneous analysis of both these analytes is limited to either mass spectrometry based methods or commercial kit suppliers. In this study we developed a novel method for analysis of both TPP and P5P by fluorescence detection.

METHODS

Briefly, whole blood samples are precipitated by trichloroacetic acid, and P5P and TPP are both derivatised before separation on a C18-PFP column. The new assay's performance was compared against a recent cycle from an external quality assurance program (RCPAQAP) and the current only existing commercial kit (n = 76).

RESULTS

Linearity for both analytes was above 0.99 (r²) up to a concentration range of: 4000 nmol/L (P5P) and 2000 nmol/L (TPP). Precision of the method (intra-day and inter-day) compared against commercial quality control material was below 6% (coefficient of variation). Recovery of both compounds exceeded 90%. Accuracy of the protocol displayed satisfactory results in proficiency testing and had an acceptable level of agreement with the existing current kit method.

CONCLUSIONS

Overall, this method provides an economical alternative in routine clinical diagnostic laboratories wishing to perform P5P and TPP analysis.

Establishing a case definition of thiamine responsive disorders among infants and young children in Lao PDR: protocol for a prospective cohort study

INTRODUCTION

Diagnosis of infantile thiamine deficiency disorders (TDD) is challenging due to the non-specific, highly variable clinical presentation, often leading to misdiagnosis. Our primary objective is to develop a case definition for thiamine responsive disorders (TRD) to determine among hospitalised infants and young children, which clinical features and risk factors identify those who respond positively to thiamine administration.

METHODS AND ANALYSIS

This prospective study will enrol 662 children (aged 21 days to <18 months) seeking treatment for TDD symptoms. Children will be treated with intravenous or intramuscular thiamine (100 mg daily for a minimum of 3 days) alongside other interventions deemed appropriate. Baseline assessments, prior to thiamine administration, include a physical examination, echocardiogram and venous blood draw for the determination of thiamine biomarkers. Follow-up assessments include physical examinations (after 4, 8, 12, 24, 36, 48 and 72 hours), echocardiogram (after 24 and 48 hours) and one cranial ultrasound. During the hospital stay, maternal blood and breast-milk samples and diet, health, anthropometric and socio-demographic information will be collected for mother-child pairs. Using these data, a panel of expert paediatricians will determine TRD status for use as the dependent variable in logistic regression models. Models identifying predictors of TRD will be developed and validated for various scenarios. Clinical prediction model performance will be quantified by empirical area under the receiver operating characteristic curve, using resampling cross validation. A frequency-matched community-based cohort of mother-child pairs (n=265) will serve as comparison group for evaluation of potential risk factors for TRD.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from The National Ethics Committee for Health Research, Ministry of Health, Lao PDR and the Institutional Review Board of the University of California Davis. The results will be disseminated via scientific articles, presentations and workshops with representatives of the Ministry of Health.

TRIAL REGISTRATION NUMBER

NCT03626337.

A Novel cis Element Achieves the Same Solution as an Ancestral cis Element During Thiamine Starvation in Candida glabrata

Regulatory networks often converge on very similar cis sequences to drive transcriptional programs due to constraints on what transcription factors are present. To determine the role of constraint loss on cis element evolution, we examined the recent appearance of a thiamine starvation regulated promoter in Candida glabrata. This species lacks the ancestral transcription factor Thi2, but still has the transcription factor Pdc2, which regulates thiamine starvation genes, allowing us to determine the effect of constraint change on a new promoter. We identified two different cis elements in C. glabrata - one present in the evolutionarily recent gene called CgPMU3, and the other element present in the other thiamine (THI) regulated genes. Reciprocal swaps of the cis elements and incorporation of the S. cerevisiaeThi2 transcription factor-binding site into these promoters demonstrate that the two elements are functionally different from one another. Thus, this loss of an imposed constraint on promoter function has generated a novel cis sequence, suggesting that loss of trans constraints can generate a non-convergent pathway with the same output.

Nutritional neuropathies

Neuropathies associated with nutritional deficiencies are routinely encountered by the practicing neurologist. Although these neuropathies assume different patterns, most are length-dependent, sensory axonopathies. Cobalamin deficiency neuropathy is the exception, often presenting with a non-length-dependent sensory neuropathy. Patients with cobalamin and copper deficiency neuropathy characteristically have concomitant myelopathy, whereas vitamin E deficiency is uniquely associated with a spinocerebellar syndrome. In contrast to those nutrients for which deficiencies produce neuropathies, pyridoxine toxicity results in a non-length-dependent sensory neuronopathy. Deficiencies occur in the context of malnutrition, malabsorption, increased nutrient loss (such as with dialysis), autoimmune conditions such as pernicious anemia, and with certain drugs that inhibit nutrient absorption. When promptly identified, therapeutic nutrient supplementation may result in stabilization or improvement of these neuropathies.

Development and validation of a dried blood spot test for thiamine deficiency among infants by HPLC-fluorimetry

Thiamine deficiency, if detected early in infancy, can be treated with thiamine supplementation and can prevent seizures, other disabilities and death. The dried blood spot (DBS) sampling technique is an attractive sample collection technique for infants. The present study reports the development and validation of a highly sensitive and precise method for quantification of thiamine diphosphate from DBS. The method utilizes full-spot analysis of a volumetrically deposited 40 μl DBS. The analyte was extracted from the DBS using 50% methanol and then derivatized using potassium ferricyanide to thiochrome. Separation was achieved with the help of an Inertsil ODS C₁₈ column (5.0 μm, 250 × 4.6 mm) using 150 mm phosphate buffer pH 7-acetonitrile (90:10, % v/v) as the mobile phase. The use of a fluorimetric detector gave a good response to the thiochrome derivative offering good sensitivity for the method. The excitation and emission wavelengths were 367 and 435 nm, respectively. The limit of detection and lower limit of quantification were 5 and 10 ng/ml, respectively. Linearity was demonstrated from 10 to 1000 ng/ml, and precision (CV) was <12.08%, at all tested quality control levels. The method accuracy was 89.34-118.89% with recoveries >80%. Bland-Altman analysis of DBS sampling vs. whole blood demonstrated a mean bias of only 1.16 ng/ml, with a majority of the 60 investigated patient samples lying within 7.2% of the corresponding concentration measured in blood, thereby meeting the clinical desirable biological specification criterion and showing that the two methods are comparable.

Periplasmic binding protein-based magnetic isolation and detection of thiamine in complex biological matrices

Deficiencies in thiamine (vitamin B1) cause a host of neurological and reproductive impairments yielding morbidity and mortality across environmental and clinical realms. In a technique analogous to immunomagnetic separation, we introduce the use of thiamine periplasmic binding protein (TBP)-conjugated magnetic beads to isolate thiamine from complex matrices. TBP expressed in Escherichia coli is highly specific to thiamine and provides an alternative to antibodies for this non-immunogenic target. After incubation with the sample and removal of unbound matrix constituents, thiamine is simultaneously released and converted to its fluorescent oxidation product thiochrome by alkaline potassium ferricyanide. Subsequent measurement of fluorescence at thiochrome-specific wavelengths provides a second layer of specificity for the detection of thiamine. Thiamine could be quantified at concentrations as low as 5 nM ranging up to 240 nM. Within, we apply this technique to selectively capture and quantify thiamine in complex salmonid fish egg and tissue matrices. Our results showed no measurable non-specific binding to the beads by endogenous fluorophores in the fish egg matrix. Thiamine levels as low as 0.2 nmol/g of fish egg can be detected using this approach, which is sufficient to assess deficiencies causing morbidity and mortality in fish that occur at 1.0 nmol/g of egg. This practical method may find application in other resource limited settings for clinical, food, or dietary supplement analyses.

Utility of Whole Blood Thiamine Pyrophosphate Evaluation in TPK1-Related Diseases

TPK1 mutations are a rare, but potentially treatable, cause of thiamine deficiency. Diagnosis is challenging given the phenotypic overlap that exists with other metabolic and neurological disorders. We report a case of TPK1-related disease presenting with Leigh-like syndrome and review the diagnostic utility of thiamine pyrophosphate (TPP) blood measurement. The proband, a 35-year-old male, presented at four months of age with recurrent episodes of post-infectious encephalopathy. He subsequently developed epilepsy, learning difficulties, sensorineural hearing loss, spasticity, and dysphagia. There was a positive family history for Leigh syndrome in an older brother. Plasma lactate was elevated (3.51 mmol/L) and brain MRI showed bilateral basal ganglia hyperintensities, indicative of Leigh syndrome. Histochemical and spectrophotometric analysis of mitochondrial respiratory chain complexes I, II+III, and IV was normal. Genetic analysis of muscle mitochondrial DNA was negative. Whole exome sequencing of the proband confirmed compound heterozygous variants in TPK1: c. 426G>C (p. Leu142Phe) and c. 258+1G>A (p.?). Blood TPP levels were reduced, providing functional evidence for the deleterious effects of the variants. We highlight the clinical and bioinformatics challenges to diagnosing rare genetic disorders and the continued utility of biochemical analyses, despite major advances in DNA sequencing technology, when investigating novel, potentially disease-causing, genetic variants. Blood TPP measurement represents a fast and cost-effective diagnostic tool in TPK1-related diseases.

Development of an IPRP-LC-MS/MS method to determine the fate of intracellular thiamine in cancer cells

Understanding the mechanisms underlying cancer cell survival is critical toward advancing drug discovery efforts in this field. Supplemental vitamins have been proposed to play a role in cancer cell metabolism because the increased supply of nutrients is thought to provide cofactors supporting the higher metabolic rate of cancer cells. Particularly, the role of thiamine (vitamin B1) in many biochemical pathways that supports cancer cell metabolism has been investigated. Consequently, the analysis of thiamine and its derivatives in a manner that reflects its dynamic response to genetic modification and pathophysiological stimuli is essential. In this work, we developed a mass spectrometry based-analytical method to track metabolites derived from stable isotope tracers for a better understanding of the metabolic fate of thiamine in cancer cells. This method used ion-pair reversed phase liquid chromatography to simultaneously quantify underivatized thiamine, thiamine monophosphate (TMP) and thiamine pyrophosphate (TPP) in cells. Hexylamine was used as an ion-pairing agent. The method was successfully validated for accuracy, precision and selectivity in accordance with U.S. FDA guidance. Furthermore, the method was then applied for the determination of thiamine and its derivatives with stable isotope labeling to explore the metabolic fate of intracellular thiamine in cancer cells. The finding shows that thiamine is rapidly converted to TPP however, the TPP does not return to thiamine. It appears that TPP may be utilized for other purposes rather than simply being an enzyme cofactor, suggesting unexplored roles for thiamine in cancer.

Neurological, Psychiatric, and Biochemical Aspects of Thiamine Deficiency in Children and Adults

Thiamine (vitamin B1) is an essential nutrient that serves as a cofactor for a number of enzymes, mostly with mitochondrial localization. Some thiamine-dependent enzymes are involved in energy metabolism and biosynthesis of nucleic acids whereas others are part of the antioxidant machinery. The brain is highly vulnerable to thiamine deficiency due to its heavy reliance on mitochondrial ATP production. This is more evident during rapid growth (i.e., perinatal periods and children) in which thiamine deficiency is commonly associated with either malnutrition or genetic defects. Thiamine deficiency contributes to a number of conditions spanning from mild neurological and psychiatric symptoms (confusion, reduced memory, and sleep disturbances) to severe encephalopathy, ataxia, congestive heart failure, muscle atrophy, and even death. This review discusses the current knowledge on thiamine deficiency and associated morbidity of neurological and psychiatric disorders, with special emphasis on the pediatric population, as well as the putative beneficial effect of thiamine supplementation in autism spectrum disorder (ASD) and other neurological conditions.

A novel LC-MS/MS assay for vitamin B1, B2 and B6 determination in dried blood spots and its application in children

Thiamin, riboflavin and pyridoxal phosphate (PLP) concentrations are useful indices for evaluating vitamin B₁, B₂ and B₆ status. Several HPLC assays have been developed for determining thiamin, riboflavin and PLP in biological matrix. However, no existing LC-MS/MS methods can be used to quantify thiamin, riboflavin and PLP in dried blood spots (DBSs), which are often used as a sampling/storage vessel for blood from infants and children. This study evaluated the validity, reliability and stability of an LC-MS/MS assay for measuring thiamin, riboflavin and PLP in DBS cards. DBS samples were deproteinized by adding trichloroacetic acid containing thiamine-[¹³C₄], riboflavin-[¹³C₄,¹⁵N₂] and pyridoxal-d₃ as internal standards. Thiamin, riboflavin and PLP were separated on a C8 column with a 5-min run time. Both the between-run and within-run variable coefficients (CV% values) were < 8.56%. The accuracies were good and showed relative errors (RE% values) from -7.40% to 3.12%. The lower limits of quantification (LLOQs) ranged from 0.2 to 0.5 ng/mL, and the recoveries were from 81.49% to 112.23% for all 3 analytes. The matrix effects (ME% values) were acceptable, and the CV% values of the internal standard-normalized matrix factors were <15% (n = 6). Thiamin, riboflavin and PLP were stable on the DBS card during at least 15 days of room-temperature storage under vacuum in the dark, and the measurements of thiamin, riboflavin and PLP in the DBSs showed good agreement with the corresponding concentrations determined from liquid blood (R² values >0.96). The validated method was successfully applied to the nutritional assessment of vitamins B₁, B₂, and B₆ in 48 Chinese children.

Prevalence of thiamine deficiency in older hospitalized patients

Purpose

Despite some reports of high prevalence of thiamine deficiency in elderly people, the reported prevalence is controversial mainly due to the methods used in assessing thiamin concentrations. In this study, we sought to investigate the prevalence of vitamin B1 deficiency, using the high-performance liquid chromatography (HPLC) method, among older hospitalized patients.

Patients and methods

This cross-sectional study retrospectively analyzed the results of routine measurements of vitamin B1 of 238 older patients who were consecutively hospitalized to a geriatric acute care ward. Whole blood vitamin B1 concentrations were measured using the HPLC method at hospital admission, and the whole blood vitamin B1 level of <20 ng/mL was considered as deficiency.

Results

Of 238 patients, with a mean age of 82.1±7.1 years, 63% of patients were women. In total, the mean whole blood vitamin B1 level was 66.1±24.8 ng/mL (range 29.5-215 ng/mL), indicating no vitamin B1 deficiency in the entire population. In addition, no significant differences in the mean whole blood vitamin B1 concentrations between sexes were observed (P=0.356).

Conclusion

This study indicates that the mean whole blood vitamin B1 concentrations using the HPLC method were within the normal range in older hospitalized patients suggesting that thiamine deficiency appears to be rather uncommon among these patients.

Beriberi disease in an 11-year-old girl with total colectomy

Beriberi or vitamin B1 deficiency is a rare disease in the developed world and more common in developing countries due to poverty and malnutrition. It usually presents with neurological manifestations (dry beriberi) or cardiovascular signs (wet beriberi). We report a case of dry beriberi in an 11-year-old girl with total colectomy who presented to our hospital with ataxic gait and muscle weakness. Her symptoms started 1 week after she underwent cholecystectomy for her chronic abdominal pain. Nerve conduction study showed sensory demyelinating neuropathy and she had low levels of serum vitamin B1. Her condition improved significantly after taking vitamin B1 supplementation. To the best of our knowledge, this is the first case report of thiamine deficiency in a child with a total colectomy.

Thiamine deficiency disorders: diagnosis, prevalence, and a roadmap for global control programs

Thiamine is an essential micronutrient that plays a key role in energy metabolism. Many populations worldwide may be at risk of clinical or subclinical thiamine deficiencies, due to famine, reliance on staple crops with low thiamine content, or food preparation practices, such as milling grains and washing milled rice. Clinical manifestations of thiamine deficiency are variable; this, along with the lack of a readily accessible and widely agreed upon biomarker of thiamine status, complicates efforts to diagnose thiamine deficiency and assess its global prevalence. Strategies to identify regions at risk of thiamine deficiency through proxy measures, such as analysis of food balance sheet data and month-specific infant mortality rates, may be valuable for understanding the scope of thiamine deficiency. Urgent public health responses are warranted in high-risk regions, considering the contribution of thiamine deficiency to infant mortality and research suggesting that even subclinical thiamine deficiency in childhood may have lifelong neurodevelopmental consequences. Food fortification and maternal and/or infant thiamine supplementation have proven effective in raising thiamine status and reducing the incidence of infantile beriberi in regions where thiamine deficiency is prevalent, but trial data are limited. Efforts to determine culturally and environmentally appropriate food vehicles for thiamine fortification are ongoing.

A single-step method for simultaneous quantification of thiamine and its phosphate esters in whole blood sample by ultra-performance liquid chromatography-mass spectrometry

Thiamine and its phosphate esters play vital physiological roles and thiamine deficiency causes deleterious effects on human body. It is important to quantify accurately the thiamine metabolites in body fluids. However, due to the lack of appropriate internal standards, poor inter-laboratory standardization and time-consuming pretreatment procedure, the existing methods are limited in clinical applications. Hence, we developed a single-step HPLC-MS/MS method for accurate and precise measurement of thiamine and its phosphate esters in human whole blood. Whole blood samples were deproteinized and the supernatants were collected. The levels of thiamine diphosphate (TDP), thiamine monophosphate (TMP), and thiamine were determined by HPLC-MS/MS method after adding isotopic internal standards. The method was linear from 15.625-3.125-1.563 nmol/L to 1000-200-100 nmol/L for TDP-TMP-thiamine. The lower limit of quantification was 15.625-3.125-1.563 nmol/L. The intra-day and inter-day precisions and accuracy for all QCs samples were ≤15.9% and ≤11.1%, respectively. The matrix effect was not significant. Recoveries were 103.7% for TDP, 102.7% for TMP, and 105.3% for thiamine. All QCs were stable for three freeze-thaw cycles, or at room temperature for 3 h, or at -80 °C for 15 days. We compared this new method with an established HPLC method based on derivatization of thiamine metabolites. It is found that this method correlated well with HPLC method for TDP determination (R² = 0.93). However, the correlation was not ideal for TMP (R² = 0.40) or thiamine (R² = 0.72) determination. Subject's diet was shown to have no significant effect on the concentrations of thiamine metabolites in their blood samples. To conclude, we developed a single-step, non-derivatization HPLC-MS/MS method that can detect thiamine and its phosphate esters in human whole blood accurately and quickly.