TASK DEFINITION: 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.
PROBLEM: Context: To investigate the existence condition of hepatitis B surface antigen(HBsAg) termination codon bias.', 'A total of 174 reference sequences of all kinds of Hepatitis B virus(HBV) genotypes were chosen from GenBank, and compared by BioEdit. Then secondary structure of RNA was constructed and analyzed together.', '(1) There were two types of HBsAg termination codon: TAA and TGA in 174 reference sequences. TAA was in 124 cases (71.26%); and TGA in 50 cases (28.74%). (2) There was codon bias selection in HBsAg termination codon, and it could affect the secondary structure of RNA and amino acid sequence encoding protein.\Question: Does [ Hepatitis B surface antigen terminate codon bias selection ]?

SOLUTION: HBsAg termination codon bias exists and may be related to RNA structure and the conservation of protein function in the evolutionary progress.

PROBLEM: Context: To assist in the development of preventive strategies, we studied whether the neighbourhood environment or modifiable behavioural parameters, including cardiorespiratory fitness (CRF) and physical activity (PA), are independently associated with obesity and metabolic risk markers in children.', 'We carried out a cross-sectional analysis of 502 randomly selected first and fifth grade urban and rural Swiss schoolchildren with regard to CRF, PA and the neighbourhood (rural vs urban) environment. Outcome measures included BMI, sum of four skinfold thicknesses, homeostasis model assessment of insulin resistance (HOMA-IR) and a standardised clustered metabolic risk score.', 'CRF and PA (especially total PA, but also the time spent engaged in light and in moderate and vigorous intensity PA) were inversely associated with measures of obesity, HOMA-IR and the metabolic risk score, independently of each other, and of sociodemographic and nutritional parameters, media use, sleep duration, BMI and the neighbourhood environment (all p < 0.05). Children living in a rural environment were more physically active and had higher CRF values and reduced HOMA-IR and metabolic risk scores compared with children living in an urban environment (all p < 0.05). These differences in cardiovascular risk factors persisted after adjustment for CRF, total PA and BMI.\Question: Are reduced cardiorespiratory fitness , low physical activity and an urban environment independently associated with increased cardiovascular risk in children?

SOLUTION: Reduced CRF, low PA and an urban environment are independently associated with an increase in metabolic risk markers in children.

PROBLEM: Context: Regulatory T cells (Tregs) are essential in the control of tolerance. Evidence implicates Tregs in human autoimmune conditions. Here we investigated their role in systemic sclerosis (SSc).', 'Patients were subdivided as having limited cutaneous SSc (lcSSc, n = 20) or diffuse cutaneous SSc (dcSSc, n = 48). Further subdivision was made between early dcSSc (n = 24) and late dcSSc (n = 24) based upon the duration of disease. 26 controls were studied for comparison. CD3+ cells were isolated using FACS and subsequently studied for the expression of CD4, CD8, CD25, FoxP3, CD127, CD62L, GITR, CD69 using flow cytometry. T cell suppression assays were performed using sorted CD4CD25(high)CD127(-) and CD4CD25(low)CD127(high) and CD3(+) cells. Suppressive function was correlated with CD69 surface expression and TGFbeta secretion/expression. The frequency of CD4(+)CD25(+) and CD25(high)FoxP3(high)CD127(neg) T cells was highly increased in all SSc subgroups. Although the expression of CD25 and GITR was comparable between groups, expression of CD62L and CD69 was dramatically lower in SSc patients, which correlated with a diminished suppressive function. Co-incubation of Tregs from healthy donors with plasma from SSc patients fully abrogated suppressive activity. Activation of Tregs from healthy donors or SSc patients with PHA significantly up regulated CD69 expression that could be inhibited by SSc plasma.\Question: Is increased frequency and compromised function of T regulatory cells in systemic sclerosis ( SSc ) related to a diminished CD69 and TGFbeta expression?

SOLUTION:
These results indicate that soluble factors in SSc plasma inhibit Treg function specifically that is associated with altered Treg CD69 and TGFbeta expression. These data suggest that a defective Treg function may underlie the immune dysfunction in systemic sclerosis.