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.

[Q]: 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?
[A]: 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.


[Q]: Context: Although the echolucent plaque in carotid stenosis is associated with future ischemic stroke, the predictive value of echogenicity in small and medium size carotid plaques on vascular events has not been thoroughly examined. Thus, we prospectively tested the hypothesis that plaque echogenicity of carotid atheroma can predict the future total cardiovascular events in patients with vascular risk factors.', 'Ultrasound assessment of carotid intima-media complex thickness (IMT) and plaque echogenicity using integrated backscatter (IBS) analysis was performed in 596 patients aged 40 or more, with any history of vascular events or with at least 1 risk factor, who were enrolled between 2001 and 2006 in the Osaka Follow-up Study for Carotid Atherosclerosis, part 2 (OSACA2). We followed the incidence of total cardiovascular events including cerebrovascular events, coronary heart disease (CHD), and peripheral artery disease (PAD) for 6.4 years. We divided the patients into two groups according to the IBS index above (echorich plaques) and under (echolucent plaque) the median value, and calculated the hazard ratios (HR) of the echolucent group compared with the echogenic group in the risk of cardiovascular events.', 'Among 596 patients, carotid stenosis was found only in 87 patients. During the follow-up period, we observed 121 cardiovascular events including 63 cerebrovascular events, 45 CHD cases, and 13 PAD cases. The patients with incident cardiovascular events had larger plaque thickness and lower IBS index than those without incident vascular events. The relative risk of vascular events for echolucent versus echorich plaques was 1.45 (95% confidence interval [CI] 0.99-2.13, p = 0.058) after adjustment for risk factors and plaque thickness. In patients with plaque size above the median value (>2.1 mm), the relative risk of vascular events for echolucent plaques was 1.72 (95% CI 1.06-2.85, p = 0.029), but this association was not observed in patients with plaque size <2.0 mm.\Question: Does echogenicity of medium-to-large carotid plaques predict future vascular events?
[A]: The association between echogenicity of carotid plaque and incident vascular events is dependent on the plaque size. Echolucent medium-to-large plaques, but not small plaques, are associated with the risk of future total cardiovascular events. This finding suggests that measurement of echolucency in medium-to-large carotid plaques may improve selection of patients at high risk for total vascular events.


[Q]: Context: The aim of this study was to compare the clinical outcome of percutaneous radiofrequency (RF) ablation, conventional percutaneous ethanol injection (PEI), and higher-dose PEI in treating hepatocellular carcinoma (HCC) 4 cm or less.', 'A total of 157 patients with 186 HCCs 4 cm or less were randomly assigned to 3 groups (52 patients in the conventional PEI group, 53 in the higher-dose PEI group, and 52 in the RF group). Clinical outcomes in terms of complete tumor necrosis, overall survival, local tumor progression, additional new tumors, and cancer-free survival were compared across 3 groups.', 'The rate of complete tumor necrosis was 88% in the conventional PEI group, 92% in the higher-dose PEI group, and 96% in the RF group. Significantly fewer sessions were required to achieve complete tumor necrosis in the RF group than in the other 2 groups (P < .01). The local tumor progression rate was lowest in the RF group (vs the conventional PEI group, P = .012; vs the higher-dose PEI group, P = .037). The overall survival rate was highest in the RF group (vs the conventional PEI group, P = .014; vs the higher-dose PEI group, P = .023). The cancer-free survival rate was highest in the RF group (vs the conventional PEI group, P = .019; vs the higher-dose PEI group, P = .024). Multivariate analysis determined that tumor size, tumor differentiation, and the method of treatment (RF vs both methods of PEI) were significant factors in relation to local tumor progression, overall survival, and cancer-free survival.\Question: Does radiofrequency ablation improve prognosis compared with ethanol injection for hepatocellular carcinoma < or =4 cm?
[A]:
The results show that RF ablation yielded better clinical outcomes than conventional and higher-dose PEI in treating HCC 4 cm or less.