In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
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Question: Context: Environmental conditions (eg, latitude) play a critical role in the susceptibility and severity of many autoimmune disorders, including multiple sclerosis (MS). Here, we investigated the mechanisms underlying the beneficial effects of immune regulatory processes induced in the skin by moderate ultraviolet B (UVB) radiation on central nervous system (CNS) autoimmunity.', 'Effects of UVB light were analyzed in a murine model of CNS autoimmunity (experimental autoimmune encephalomyelitis). Additionally, patients with relapsing-remitting MS were treated with narrowband UVB phototherapy. Immunomodulatory effects were examined in skin biopsies, serum samples, and immune cells of the peripheral blood.', 'Regulatory T cells (Tregs), which are induced locally in the skin-draining lymph nodes in response to UVB exposure, connect the cutaneous immune response to CNS immunity by migration to the sites of inflammation (blood, spleen, CNS). Here, they attenuate the inflammatory response and ameliorate disease symptoms. Treg-inducing tolerogenic dendritic cells (DCs) were further necessary for induction of this systemic immune regulation by UVB radiation, because ablation of Langerhans cells abolished the UVB-induced phenotype. MS patients treated with UVB phototherapy showed an increase in induced Tregs and tolerogenic DCs accompanied by the downregulation of the T-cell effector cytokine interleukin 21. The treatment further induced elevated serum levels of vitamin D.\Question: Does ultraviolet B light attenuate the systemic immune response in central nervous system autoimmunity?

Answer: Local UVB radiation of the skin influences systemic immune reactions and attenuates systemic autoimmunity via the induction of skin-derived tolerogenic DCs and Tregs. Our data could have implications for the understanding or therapeutic modulation of environmental factors that influence immune tolerance.


Question: Context: An association between mitral valvar prolapse and low body mass index has been proposed. The goal of this study was to evaluate this suggested association using two independent and large databases. For comparison, we evaluated the association, if any, between bicuspid aortic valve and low body mass index.', 'We retrospectively analyzed, using uni- and multivariate analysis, 1742 echocardiograms that were performed as a part of a cardiac screening of teenage athletes and 24,265 echocardiograms performed between 1984 and 1998 for various clinical indications.', 'The first database included a total of 12,926 (53%) female and 11,339 (47%) male patients. The second database included a total of 1172 male (67%) and 570 female (33%) high school athletes. Mitral valvar prolapse was independently associated with low body mass index in addition to mitral regurgitation in both data bases. An index less than 30 occurred in 78 of 13,874 (0.6%) as opposed to 7 of 3236 (0.2%) in the echo data base, p equal to 0.03, odds ratio: 2.4 confidence intervals: 1.1-5.2, and an index less than 20 occurred in 7 of 354 (2%) as opposed to 6 of 944 (0.6%) in the athletic data base, p equal to 0.03, odds ratio: 3.2 confidence intervals: 1.05-9.5. The finding of a bicuspid aortic valve did not have any association with low body mass index.\Question: Is mitral valvar prolapse significantly associated with low body mass index in addition to mitral and tricuspid regurgitation?

Answer: In our two independent databases, mitral valvar prolapse was independently associated with low body mass index in addition to mitral and tricuspid regurgitation. The cause of this association remains unknown.


Question: Context: Morbidly obese patients usually present vitamin D deficiency or secondary hyperparathyroidism. Low vitamin D levels have been recently related to non-alcoholic fatty liver disease (NAFLD). The aim of this study was to analyse the relationship between vitamin D, bone turnover markers and non-alcoholic fatty liver disease and metabolic syndrome in severely obese patients.', 'One hundred and ten patients who underwent bariatric surgery were included. Liver biopsy was taken during surgery. Two univariate analyses were carried out in order to i) analyse the relationship between liver histology and vitamin D-bone turnover markers (intact parathyroid hormone (PTH), osteocalcin and Carboxy-terminal collagen crosslinks) and ii) establish the association between metabolic syndrome components-insulin resistance (HOMA) and vitamin D-bone turnover markers.', '70% of the patients had lower levels of vitamin D or secondary hyperparathyroidism. None of the components of liver histology were associated with levels of vitamin D or with bone turnover parameters. Patients with metabolic syndrome showed lower levels of PTH and osteocalcin (72,42 (29,47) vs 61.25(19.59) p-Value: 0.022; 19.79 (10.43) vs 16.87(10.25) p-Value: 0,028, respectively). HOMA was not related to Vitamin D or bone turnover markers.\Question: Are vitamin D levels and bone turnover markers related to non-alcoholic fatty liver disease in severely obese patients?

Answer:
Low levels of vitamin D or hyperparathyroidism are common in severely obese patients. Vitamin D and bone metabolism markers were associated neither to NAFLD nor with metabolic syndrome in our series of obese morbid patients.