Vadim G. Krivoshapkin

Lifestyle Incongruity, Stress and Immune Function in Indigenous Siberians : The Health Impacts of Rapid Social and Economic Change

The purpose of this study was to investigate the impact of economic and cultural change on immune function and psychosocial stress in an indigenous Siberian population. We examined Epstein-Barr virus antibodies (EBV), an indirect biomarker of cell-mediated immune function, in venous whole blood samples collected from 143 Yakut (Sakha) herders (45 men and 98 women) in six communities using a cross-sectional study design. We modeled economic change through the analysis of lifestyle incongruity (LI), calculated as the disparity between socioeconomic status and material lifestyle, computed with two orthogonal scales: market and subsistence lifestyle. EBV antibody level was significantly negatively associated with both a market and a subsistence lifestyle, indicating higher cell-mediated immune function associated with higher material lifestyle scores. In contrast, LI was significantly positively associated with EBV antibodies indicating lower immune function, and suggesting higher psychosocial stress, among individuals with economic status in excess of material lifestyle. Individuals with lower incongruity scores (i.e., economic status at parity with material resources, or with material resources in excess of economic status) had significantly lower EBV antibodies. The findings suggest significant health impacts of changes in material well-being and shifting status and prestige markers on health during the transition to a market economy in Siberia. The findings also suggest that relative, as opposed to absolute, level of economic status or material wealth is more strongly related to stress in the Siberian context.

Seasonal variation in basal metabolic rates among the yakut (Sakha) of Northeastern Siberia

Objectives: Previous research has shown that indigenous circumpolar populations have elevated basal metabolic rates (BMRs), yet few studies have explored whether metabolic rates increase during the winter. This study addresses this gap by examining seasonal variation in BMR and its associations with thyroid function and lifestyle factors among the Yakut (Sakha) of Siberia.

Circumpolar Adaptation, Social Change, and the Development of Autoimmune Thyroid Disorders Among the Yakut (Sakha) of Siberia

Alterations in thyroid function appear to play a central role in adaptation to Arctic environments. Increased thyroid activity in indigenous circumpolar populations is associated with upregulated metabolism, including elevated basal metabolic rate (BMR); however, little is known about the possible health consequences of these climate‐induced changes on thyroid function. The focus of the present study is to determine the prevalence of autoimmune thyroid disorders and their lifestyle and metabolic correlates among a sample of indigenous Yakut adults from northeastern Siberia.

Seasonal and Socioeconomic Influences on Thyroid Function Among the Yakut (Sakha) of Eastern Siberia

Previous research has shown that the extreme cold and short day lengths of polar winters promote increased production and uptake of thyroid hormones, resulting in marked declines in free triiodothyronine (fT3). However, this “polar T3 syndrome” has been documented almost exclusively on small samples of male sojourners and little is known about seasonal changes in thyroid function among indigenous circumpolar groups. The present study addresses this gap by examining seasonal changes in thyroid hormone levels among the indigenous Yakut (Sakha) of northeastern Siberia.

Viliuisk encephalomyelitis: intrathecal synthesis of oligoclonal IgG

Viliuisk encephalomyelitis (VE) is a neurodegenerative disorder expressed as subacute meningo-encephalitis progressing to a more prolonged pan-encephalitic syndrome with a fatal outcome within 1 to 10 years. Some patients survive to a steady state of global dementia and severe spasticity that may last for over 20 years. Multiple micronecrotic foci surrounded by inflammatory infiltrates are observed throughout the cerebral cortex and other gray matter areas. Infectious etiology of VE is strongly suspected, but the causative agent has not been identified. We conducted a search for assays that might be helpful for VE diagnosis and established for the first time that the majority of patients with definite VE show evidence for intrathecal IgG synthesis correlating with the clinical manifestations of the disease. This indicates that the detection of oligoclonal IgG banding in the cerebrospinal fluid is a valuable diagnostic assay for VE. Implications of these findings for a possible etiology of VE are discussed.

Family clustering of Viliuisk encephalomyelitis in traditional and new geographic regions

Transmission occurs through patient contact; human migration from disease-endemic villages leads to disease emergence in new communities.

Objectively measured physical activity and sedentary behaviour of Yakut (Sakha) adults.

Abstract Background: Circumpolar regions are undergoing social and economic transition, which often corresponds to a behavioural transition. Yet, physical activity and sedentary behaviour are rarely objectively measured within these groups. Aim: This study aimed to characterize objectively measured physical activity and sedentary behaviour in a sample of indigenous Siberians. Subjects and methods: Yakut (Sakha) adults (n = 68, 32 men) underwent anthropometry, interviews and wore a triaxial accelerometer for two days. Time spent in moderate-to-vigorous physical activity (MVPA) or sedentary behaviour was calculated using a single axis and also all three axes. Results: Men spent significantly more time in MVPA than women, although no sex difference was found in sedentary behaviour. Participants were far more active and less sedentary when classified using all three axes (vector magnitude) than a single axis. Television viewing time significantly related to sedentary behaviour in men only. Conclusion: The Yakut have gender differences in amount and predictors of physical activity and sedentary behaviour. Triaxial accelerometry is more sensitive to daily physical activity in free living populations than single axis.

Do physical activity and sedentary behavior relate to cardio-metabolic risk factor clustering in indigenous Siberian adults?

To investigate whether having multiple risk factors for cardio‐metabolic disease is associated with objectively measured physical activity or sedentary behavior within a sample of Yakut (Sakha) of Siberia.

Viliuisk encephalomyelitis in Northeastern Siberia is not caused by Borrelia burgdorferi infection

Viliuisk encephalomyelitis (VE) is an endemic neurological disease in Northeastern Siberia and generally believed to be a chronic encephalomyelitis of unknown origin. We investigated 17 patients with a clinical diagnosis of VE within the Viliuiski region of Sakha (Yakutian) Republic to explore the core clinical syndrome of chronic VE and subsequently whether VE is caused by Borrelia burgdorferi infection. We found a chronic myelopathy as the core of the syndrome, often following an acute phase with a meningo-radiculo-neuropathy, suggestive of chronic neuroborreliosis. A search for inflammatory parameters in a larger cohort in blood (39 VE patients and 41 controls) and CSF samples (10 VE patients and 7 controls) excluded an ongoing chronic infection, but revealed evidence for an immunological scar or a chronic inflammatory (“autoimmune”) response in the CSF. In addition, we detected signs of a previous exposure to Borrelia burgdorferi antigens in a subset of chronic VE patients with positive serological results using ELISA/immunoblot in 54/10% and 22/0% of VE patients and controls, respectively (p values of 0.003/0.034; Fisher’s exact test). However, CSF analyses did not show a link between exposure or at least immunological reaction against Borrelia and the risk of suffering from VE. Our data provide the first evidence of the presence of Borrelia burgdorferi or similar pathogens in Northeastern Siberia, but do not support a causative role of these pathogens in the aetiopathogenesis of VE.

Communicating Hydrocephalus Following Eosinophilic Meningitis Is Pathogenic for Chronic Viliuisk Encephalomyelitis in Northeastern Siberia

Background Viliuisk encephalomyelitis (VE) is an endemic neurological disease in Northeast Siberia and generally considered to be a chronic encephalomyelitis of unknown origin actually spreading in the Sakha (Yakutian) Republic. Methodology and Principle Findings In search for the pathophysiology and causative agent of VE, we performed a cross-sectional study on clinical, serological and neuroimaging data on chronic VE patients during two medical expeditions to three villages within the Viliuiski river basin in the Republic of Sakha in 2000 and to the capital Yakutsk in 2006. The severity of the core clinical picture with predominant sensory ataxia, gait apraxia, lower limb spasticity, cognitive impairment and bladder dysfunction correlated with the degree of MRI findings showing enlargement of inner ventricular spaces as in communicating hydrocephalus. Laboratory studies revealed transient eosinophilia during the preceding acute meningitis-like phase, but no ongoing inflammatory process in the CSF. We found immune reactions against Toxocara canis in the majority of chronic VE patients but rarely in controls (P = 0.025; Fishers exact test). Histological analysis of subacute to subchronic VE brain samples showed eosinophilic infiltrations with no signs of persistent Toxocara canis infection. Conclusions and Significance Our data showed that pressure by the communicating hydrocephalus as a mechanical factor is the major pathogenic mechanism in chronic VE, most likely triggered by eosinophilic meningitis. There are no signs for an ongoing inflammatory process in chronic VE. The past eosinophilic reaction in VE might be caused by Toxocara ssp. infection and might therefore represent the first hint for an initial cause leading to the development of chronic VE. Our data provide a framework for future studies and potential therapeutic interventions for this enigmatic epidemic neurological disease potentially spreading in Sakha Republic.