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.

Context: CTLA4IgG that binds to B7 effectively inhibits the signaling of CD28/B7 pathway and induces antigen-specific T-cell unresponsiveness in vitro and in vivo. We examined whether the development of obliterative bronchiolitis in a murine heterotopic airway transplantation model is T cell dependent and whether CTLA4IgG abrogates the development of obliterative bronchiolitis.', 'Tracheae with main bronchi from C3H/He (H2k), BALB/C (H2d), or C57BL/6 (H2b) mice were transplanted heterotopically into subcutaneous pockets on the backs of BALB/C or BALB/C nu/nu mice on day 0. Recipient mice were untreated or intraperitoneally treated with either CTLA4IgG or human IgG with different time and dose schedules.', 'The development of obliterative bronchiolitis, which leads to luminal obliteration by fibrous tissue in a murine heterotopic airway transplantation model, was T cell dependent and the development of obliterative bronchiolitis was significantly abrogated by the CTLA4IgG treatment. However, the normal ciliated columnar respiratory epithelial cells in allografts were lost and replaced by flattened attenuated epithelial cells even after the CTLA4IgG treatment. We further demonstrated that CTLA4IgG treatment did not result in the induction of donor-specific unresponsiveness.\Question: Does blocking the CD28-B7 T-cell costimulatory pathway abrogate the development of obliterative bronchiolitis in a murine heterotopic airway model?
We demonstrated that the development of obliterative bronchiolitis in a murine heterotopic airway model involves both CD28/B7-dependent and -independent processes. The luminal obliteration by fibrous tissue is clearly CD28/B7 dependent and can be inhibited by CTLA4IgG. The luminal obliteration of allografted trachea by fibrous tissues and the loss of ciliated columnar respiratory epithelial cells represent distinct disease processes.

Context: Analyses of the pattern of p53 mutations have been essential for epidemiologic studies linking carcinogen exposure and cancer. We were concerned by the inclusion of dubious reports in the p53 databases that could lead to controversial analysis prejudicial to the scientific community.', 'We used the universal mutation database p53 database (21,717 mutations) combined with a new p53 mutant activity database (2,300 mutants) to perform functional analysis of 1,992 publications reporting p53 alterations. This analysis was done using a statistical approach similar to that of clinical meta-analyses.', 'This analysis reveals that some reports of infrequent mutations are associated with almost normal activities of p53 proteins. These particular mutations are frequently found in studies reporting multiple mutations in one tumor, silent mutations, or lacking mutation hotspots. These reports are often associated with particular methodologies, such as nested PCR, for which key controls are not satisfactory.\Question: Does meta-analysis of the p53 mutation database for mutant p53 biological activity reveal a methodologic bias in mutation detection?
We show the importance of accurate functional analysis before inferring any genetic variation. The quality of the p53 databases is essential in order to prevent erroneous analysis and/or conclusions. The availability of functional data from our new p53 web site (http://p53.free.fr and http://www.umd.be:2072/) will allow functional prescreening to identify potential artifactual data.

Context: Lymph node ratio (LNR), positive nodes divided by nodes examined, has been proposed for prognostication in melanoma to mitigate problems with low node counts. However, it is unclear if LNR offers superior prognostication over total counts of positive nodes and nodes examined. Additionally, the prognostic value of LNR may change if a threshold number of nodes are examined. We evaluated whether LNR is more prognostic than positive nodes and nodes examined, and whether the prognostic value of LNR changes with minimum thresholds.', "Using the National Cancer Data Base Participant User File, we identified 74,692 incident cases with nodal dissection during 2000-2006. We compared LNR versus counts of examined and positive nodes based on Harrell's C, a measure of predictive ability. We then stratified by total nodes examined: greater versus fewer than ten for axillary lymph node dissection (ALND) and greater versus fewer than five for inguinal lymph node dissection (ILND).", "Overall, LNR had a Harrell's C of 0.628 (95\xa0% confidence interval [CI] 0.625-0.631). Examined and positive nodes were not significantly different from this, with a Harrell's C of 0.625 (95\xa0% CI 0.621-0.630). In ALND, LNR had a Harrell's C of 0.626 (95\xa0% CI 0.610-0.643) with ≥10 nodes versus 0.554 (95\xa0% CI 0.551-0.558)\xa0<\xa010 nodes. In ILND, LNR had a Harrell's C of 0.679 (95\xa0% CI 0.664-0.694) with ≥5 nodes versus C of 0.601 (95\xa0% CI 0.595-0.606)\xa0<\xa05 nodes.\Question: Does lymph Node Ratio be Less Prognostic in Melanoma When Minimum Node Retrieval Thresholds Are Not Met?

LNR provides no prognostic superiority versus counts of examined and positive nodes. Moreover, the prognostic value of LNR diminishes when minimum node retrieval thresholds are not met.