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.

[EX Q]: Context: To ascertain the prevalence of psychiatric symptoms and substance use disorders among adolescents with a lifetime history of foster care placement, using data from a nationally representative sample of U.S. adolescents.', 'We studied adolescents aged 12-17 years in the public use file of the 2000 National Household on Drug Abuse (n = 19,430, including 464 adolescents with history of foster care placement). Psychiatric symptoms and substance use disorders were ascertained through direct interviewing of adolescents. Logistic regression analyses were used to estimate the odds of past-year psychiatric symptoms and substance use disorders among adolescents involved with foster care, as compared to those without a lifetime history of foster care placement (comparison group).', 'Adolescents involved with foster care had more past-year psychiatric symptoms, and especially more conduct symptoms, and past-year substance use disorders than those never placed in foster care. Adolescents involved with foster care were about four times more likely to have attempted suicide in the preceding 12 months (adjusted odds ratio [AOR] 3.95; 95% confidence interval [CI] 2.78, 5.61), and about five times more likely to receive a drug dependence diagnosis in the same period (AOR 4.81; 95% CI 3.22, 7.18).\Question: Do psychiatric symptoms and substance use disorders in a nationally representative sample of American adolescents involved with foster care?
[EX A]: Adolescents involved with foster care have a higher prevalence of psychiatric symptoms and drug use disorders than those never placed in foster care. Additionally, the results of this study suggest that they may be at elevated risk for suicide attempts.

[EX Q]: Context: Cytokeratin 19 is significant for indicating cancer cells, and Cyfra 21-1 is a fragment of cytokeratin 19. This retrospective study was designed to define the prognostic value of serum Cyfra 21-1 in epithelial ovarian cancers (EOC).', 'Serum Cyfra 21-1 concentration was obtained from 42 patients with EOC prior to treatment. Various prognostic aspects were examined using univariable and multivariable analyses. The standard serum marker cancer antigen 125 was measured simultaneously and compared in this analysis.', 'Serum levels of both Cyfra 21-1 and cancer antigen 125 were associated with positive retroperitoneal lymph nodes and platinum resistance; higher levels of Cyfra 21-1 (3.0ng/mL as the cut-off) were associated with shorter disease-free survival (16 months vs. 28 months, p=0.001) and overall survival (29 months vs. 41 months, p=0.007) than lower levels. Further univariable analysis showed that Cyfra 21-1, poor differentiation, and retroperitoneal lymph node metastasis were related to platinum resistance and mortality. Multivariable analysis indicated retroperitoneal lymph node metastasis and serum Cyfra 21-1 were independent risk factors for both disease-free survival and overall survival.\Question: Is serum cytokeratin-19 fragment ( Cyfra 21-1 ) a prognostic indicator for epithelial ovarian cancer?
[EX A]: The pretreatment level of serum Cyfra 21-1 had remarkable prognostic significance for EOC, indicating poor survival when it was elevated above 3.0ng/mL.

[EX Q]: Context: Exosomes are 30-100 nm membrane vesicles of endocytic origin, mediating diverse biological functions including tumor cell invasion, cell-cell communication and antigen presentation through transfer of proteins, mRNAs and microRNAs. Recent evidence suggests that microRNAs can be released through ceramide-dependent secretory machinery regulated by neutral sphingomyelinase 2 (nSMase2) enzyme encoded by the smpd3 gene that triggers exosome secretion. However, whether exosome-mediated microRNA transfer plays any role in cell invasion remains poorly understood. Thus, the aim of this study was to identify the exosomal microRNAs involved in breast cancer invasion.', 'The expression level of endogenous and exosomal miRNAs were examined by real time PCR and the expression level of target proteins were detected by western blot. Scanning electron and confocal microscopy were used to characterize exosomes and to study its uptake and transfer. Luciferase reporter plasmids and its mutant were used to confirm direct targeting. Furthermore, the functional significance of exosomal miR-10b was estimated by invasion assay.', 'In this study, we demonstrate that microRNA carrying exosomes can be transferred among different cell lines through direct uptake. miR-10b is highly expressed in metastatic breast cancer MDA-MB-231 cells as compared to non-metastatic breast cancer cells or non-malignant breast cells; it is actively secreted into medium via exosomes. In particular, nSMase2 or ceramide promotes the exosome-mediated miR-10b secretion whereas ceramide inhibitor suppresses this secretion. Moreover, upon uptake, miR-10b can suppress the protein level of its target genes such as HOXD10 and KLF4, indicating its functional significance. Finally, treatment with exosomes derived from MDA-MB-231 cells could induce the invasion ability of non-malignant HMLE cells.\Question: Does exosome-mediated transfer of miR-10b promote cell invasion in breast cancer?
[EX A]:
Together, our results suggest that a set of specific microRNAs may play an important role in modulating tumor microenvironment through exosomes. Thus, a better understanding of this process may aid in the development of novel therapeutic agents.