Putamina involvement in Wernicke encephalopathy induced by Janus Kinase 2 inhibitor

Comparison of beriberi cases in indigenous and non-indigenous people, Brazil, 2013 to 2018

Beriberi is the clinical manifestation of severe and prolonged thiamine (vitamin B1) deficiency. It is a neglected disease that affects low-income populations facing food and nutrition insecurity. The aim of this study was to compare cases of beriberi among indigenous and non-indigenous people in Brazil. We conducted a cross-sectional study using data on cases of beriberi during the period July 2013-September 2018 derived from beriberi notification forms available on the FormSUS platform. Cases in indigenous and non-indigenous patients were compared using the chi-squared test or Fisher's exact test, adopting a significance level of 0.05. A total of 414 cases of beriberi were reported in the country during the study period, 210 of which (50.7%) were among indigenous people. Alcohol consumption was reported by 58.1% of the indigenous patients and 71.6% of the non-indigenous patients (p = 0.004); 71.0% of the indigenous patients reported that they consumed caxiri, a traditional alcoholic drink. Daily physical exertion was reported by 76.1% of the indigenous patients and 40.2% of the non-indigenous patients (p < 0.001). It is concluded that beriberi disproportionately affects indigenous people and is associated with alcohol consumption and physical exertion.

On the dynamic and even reversible nature of Leigh syndrome: Lessons from human imaging and mouse models

Leigh syndrome (LS) is a neurodegenerative disease characterized by bilaterally symmetric brainstem or basal ganglia lesions. More than 80 genes, largely impacting mitochondrial energy metabolism, can underlie LS, and no approved medicines exist. Described 70 years ago, LS was initially diagnosed by the characteristic, necrotic lesions on autopsy. It has been broadly assumed that antemortem neuroimaging abnormalities in these regions correspond to end-stage histopathology. However, clinical observations and animal studies suggest that neuroimaging findings may represent an intermediate state, that is more dynamic than previously appreciated, and even reversible. We review this literature, discuss related conditions that are treatable, and present two new LS cases with radiographic improvement. We review studies in which hypoxia reverses advanced LS in a mouse model. The fluctuating and potentially reversible nature of radiographic LS lesions will be important in clinical trial design. Better understanding of this plasticity could lead to new therapies.

A patient with Korsakoff syndrome of psychiatric and alcoholic etiology presenting as DSM-5 mild neurocognitive disorder

Background: Wernicke's encephalopathy (WE) and Korsakoff syndrome (KS) are underdiagnosed. The DSM-5 has raised the diagnostic threshold by including KS in the major neurocognitive disorders, which requires that the patient needs help in everyday activities. Methods: We report clinical, neuropsychological, and radiological findings from a patient who developed Wernicke-Korsakoff syndrome as a result of alcohol use and weight loss due to major depression. We assess the diagnosis in the context of the scientific literature on KS and according to the DSM-IV and the DSM-5. Results: The patient developed ataxia during a period of weight loss, thus fulfilling current diagnostic criteria of WE. WE was not diagnosed, but the patient partially improved after parenteral thiamine treatment. However, memory problems became evident, and KS was considered. In neuropsychological examination, the Logical Memory test and the Word List test were abnormal, but the Verbal Pair Associates test was normal (Wechsler Memory Scale-III). There were intrusions in the memory testing. The Wisconsin Card Sorting Test was broadly impaired, but the other test of executive functions (difference between Trail Making B and Trail Making A tests) was normal. There was atrophy of the mammillary bodies, the thalamus, the cerebellum, and in the basal ganglia but not in the frontal lobes. Diffusion tensor imaging showed damage in several tracts, including the uncinate fasciculi, the cinguli, the fornix, and the corona radiata. The patient remained independent in everyday activities. The patient can be diagnosed with KS according to the DSM-IV. According to the DSM-5, the patient has major neurocognitive disorders. Conclusions: Extensive memory testing is essential in the assessment of KS. Patients with a history of WE and typical clinical, neuropsychological, and radiological KS findings may be independent in everyday activities. Strict use of the DSM-5 may worsen the problem of Wernicke-Korsakoff syndrome underdiagnosis by excluding clear KS cases that do not have very severe functional impairment.

Thiamine deficiency in childhood with attention to genetic causes: Survival and outcome predictors

Primary and secondary conditions leading to thiamine deficiency have overlapping features in children, presenting with acute episodes of encephalopathy, bilateral symmetric brain lesions, and high excretion of organic acids that are specific of thiamine-dependent mitochondrial enzymes, mainly lactate, alpha-ketoglutarate, and branched chain keto-acids. Undiagnosed and untreated thiamine deficiencies are often fatal or lead to severe sequelae. Herein, we describe the clinical and genetic characterization of 79 patients with inherited thiamine defects causing encephalopathy in childhood, identifying outcome predictors in patients with pathogenic SLC19A3 variants, the most common genetic etiology. We propose diagnostic criteria that will aid clinicians to establish a faster and accurate diagnosis so that early vitamin supplementation is considered. Ann Neurol 2017;82:317-330.

Beyond drug-drug interactions: effects of transporter inhibition on endobiotics, nutrients and toxins

INTRODUCTION

Membrane transport proteins play a central role in regulating the disposition of endobiotics, dietary nutrients and environmental toxins. The inhibition of transporters by drugs has potential physiologic consequences. The full extent of the effect of drugs on the function of transporters is poorly understood because only a small subset of the hundreds of transporters expressed in humans - primarily those mediating the rate-determining step in the elimination of specific drugs - are assessed during clinical development. Areas covered: We provide a comprehensive overview of literature reports implicating the inhibition of transporters as the mechanism for off-target effects of drugs. Expert opinion: Transporter inhibition, the mechanism of action of many marketed drugs, appears to play an underappreciated role in a number of side effects including vitamin deficiency, edema, dyslipidemia, cholestasis and gout. Cell systems more broadly expressing transporter networks and methods like unbiased metabolomics should be incorporated into the screening paradigm to expand our understanding of the impact of drugs on the physiologic function of transporters and to allow for these effects to be taken into account in drug discovery and clinical practice.

Treatment of rats with the JAK-2 inhibitor fedratinib does not lead to experimental Wernicke's encephalopathy

Recent clinical trials suggest that patients with myelofibrosis can develop Wernicke's encephalopathy (WE) when treated with fedratinib, a specific Janus kinase-2 (JAK-2) inhibitor. To investigate this issue, we have examined (1) if fedratinib can produce or alter the course of this disorder, (2) its effects on thiamine-dependent enzyme activity and thiamine status, and (3) its influence on the uptake of thiamine. Animals administered fedratinib for 28days at a comparable dose used to treat human cases of myelofibrosis showed no evidence of clinical signs of thiamine deficiency (TD). Rats treated with a combination of fedratinib and TD exhibited no neurological differences in their progress to the symptomatic stage when compared to thiamine-deficient animals only. Treatment with the JAK-2 inhibitor did not compromise erythrocyte transketolase activity, and thiamine status was not affected in a major way unlike animals with TD. In addition, treatment of cultured astrocytes with fedratinib did not diminish the uptake of thiamine into these cells. Our findings suggest that treatment with fedratinib does not lead to or alter the progress of TD, and do not support the notion that administration of this JAK-2 inhibitor directly results in the development of WE due to inhibition of thiamine transport. Known adverse effects of fedratinib involving compromised gastrointestinal function may be an important indirect contributing factor to previously reported cases of WE in patients with myelofibrosis.

Interaction of 2,4-Diaminopyrimidine-Containing Drugs Including Fedratinib and Trimethoprim with Thiamine Transporters

Inhibition of thiamine transporters has been proposed as a putative mechanism for the observation of Wernicke's encephalopathy and subsequent termination of clinical development of fedratinib, a Janus kinase inhibitor (JAKi). This study aimed to determine the potential for other JAKi to inhibit thiamine transport using human epithelial colorectal adenocarcinoma (Caco-2) and thiamine transporter (THTR) overexpressing cells and to better elucidate the structural basis for interacting with THTR. Only JAKi containing a 2,4-diaminopyrimidine were observed to inhibit thiamine transporters. Fedratinib inhibited thiamine uptake into Caco-2 cells (IC₅₀ = 0.940 µM) and THTR-2 (IC₅₀ = 1.36 µM) and, to a lesser extent, THTR-1 (IC₅₀ = 7.10 µM) overexpressing cells. Two other JAKi containing this moiety, AZD1480 and cerdulatinib, were weaker inhibitors of the thiamine transporters. Other JAKi-including monoaminopyrimidines, such as momelotinib, and nonaminopyrimidines, such as filgotinib-did not have any inhibitory effects on thiamine transport. A pharmacophore model derived from the minimized structure of thiamine suggests that 2,4-diaminopyrimidine-containing compounds can adopt a conformation matching several key features of thiamine. Further studies with drugs containing a 2,4-diaminopyrimidine resulted in the discovery that the antibiotic trimethoprim also potently inhibits thiamine uptake mediated by THTR-1 (IC₅₀ = 6.84 µM) and THTR-2 (IC₅₀ = 5.56 µM). Fedratinib and trimethoprim were also found to be substrates for THTR, a finding with important implications for their disposition in the body. In summary, our results show that not all JAKi have the potential to inhibit thiamine transport and further establish the interaction of these transporters with xenobiotics.

Wernicke encephalopathy in a patient with liver failure: Clinical case report

Early recognition and diagnosis of Wernicke encephalopathy is pivotal for the prognosis of this medical emergency, especially in patients with liver failure which predisposes individuals to develop hepatic encephalopathy. For these patients, distinguishing between hepatic encephalopathy and Wernicke encephalopathy is a challenge in real-world clinical practice.A male patient with 21-year medical history of liver cirrhosis presented diarrhea and ascites. One month before this visit, he was noted to have poor appetite and progressive fatigue. After admission, although several major symptoms, including diarrhea, ascites, hyponatremia, and hypoproteinemia, were greatly improved through appropriate treatments, his laboratory indicators were not changed much. His appetite was not reversed at discharge. On the 5th day after discharge, the patient suddenly became reluctant to speak and did not remember the recent happenings. Simultaneously, unsteady gait and strabismus occurred. On the basis of clinical manifestations and brain magnetic resonance imaging scan results, the patient was diagnosed as Wernicke encephalopathy and these relative symptoms were resolved after intravenous vitamin B1.To our knowledge, this is the second case report of Wernicke encephalopathy developing in a critically ill cirrhotic patient without hepatocellular carcinoma or operative intervention. Wernicke encephalopathy may be underdiagnosed in these patients and this case raises physicians' awareness of its possible onset.