TASK DEFINITION: In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.
PROBLEM: Expression of the receptor-type tyrosine phosphatase LAR was studied in cells of the murine hemopoietic system. The gene is expressed in all cells of the T cell lineage but not in cells of any other hemopoietic lineage and the level of expression in T cells is developmentally regulated. The CD4(-)8(-)44(+) early thymic immigrants and mature (CD4(+)8(-)/CD4(-)8(+)) thymocytes and T cells express low levels, whereas immature (CD4(-)8(-)44(-) and CD4(+)8(+)) thymocytes express high levels of LAR. Among bone marrow cells only uncommitted c-kit(+)B220(+)CD19(-) precursors, but not B cell lineage committed c-kit(+)B220(+)CD19(+) precursors, express low levels of LAR. In contrast to the c-kit(+)B220(+)CD19(+) pre-BI cells from normal mice, counterparts of pre-BI cells from PAX-5-deficient mice express LAR, indicating that PAX-5-mediated commitment to the B cell lineage results in suppression of LAR. During differentiation of PAX-5-deficient pre-BI cell line into non-T cell lineages, expression of LAR is switched off, but it is up-regulated during differentiation into thymocytes. Thus, within the hemopoietic system, LAR appears to be a T cell lineage-specific receptor-type phosphatase. However, surprisingly, truncation of its phosphatase domains has no obvious effect on T cell development, repertoire selection or function.

SOLUTION: Within the hemopoietic system, LAR phosphatase is a T cell lineage-specific adhesion receptor-like protein whose phosphatase activity appears dispensable for T cell development, repertoire selection and function.

PROBLEM: Caspase recruitment domain-containing membrane-associated guanylate kinase protein-1 (CARMA1) is a critical component of the NF-kappaB signaling cascade mediated by TCR engagement. In addition to activation of naive T cells, TCR signaling is important for the development of agonist-selected T-cell subsets such as Treg, NKT cells, and CD8-alpha alpha T cells. However, little is known about the role of CARMA1 in the development of these lineages. Here we show that CARMA1-deficient mice (CARMA1(-/-)) have altered populations of specific subsets of agonist-selected T cells. Specifically, CARMA1(-/-) mice have impaired natural and adaptive Treg development, whereas NKT cell numbers are normal compared with wild-type mice. Interestingly, CD8-alpha alpha T cells, which may also be able to develop through an extrathymic selection pathway, are enriched in the gut of CARMA1(-/-) mice, whereas memory-phenotype CD4(+) T cells (CD62L(low)/CD44(high)) are present at reduced numbers in the periphery. These results indicate that CARMA1 is essential for Treg development, but is not necessary for the development of other agonist-selected T-cell subsets. Overall, these data reveal an important but differential role for CARMA1-mediated TCR signaling in T-cell development.

SOLUTION: Differential requirement for CARMA1 in agonist-selected T-cell development.

PROBLEM: The epidemiological evidence that a high-fat diet promotes the development of obesity is considered suggestive but not definitive. The purpose of this paper is to provide a review of various epidemiological methods that have been used to address this issue as well as an updated summary of the existing evidence. Ecological studies describing dietary fat intake and obesity at the population level provide mixed results and are likely to be biased by both confounding and unknown data quality factors that differ systematically across the populations studied. Cross-sectional studies are generally in agreement that the concentration of fat in the diet is positively associated with relative weight. Prospective studies of diet in relation to subsequent weight change give inconsistent results. This may be due to behavioural factors such as dieting in response to weight gain; in addition, this type of study rarely takes into account the possible interaction between genetic predisposition and dietary fat in promoting weight gain. Finally, intervention studies in free-living subjects are considered, providing evidence of a consistent but short-lived period of active weight loss on low-fat diets. The experimental evidence on this relationship is more conclusive than the epidemiological evidence, although biological mechanisms remain controversial. Some areas for future epidemiological research involve: longitudinal studies of dietary fat intake as a predictor of growth in children; observational studies relating total dietary fat and specific types of fat to overall as well as regional adiposity; and randomized intervention studies of the effect of low-fat diets with particular emphasis on and familial predisposition to obesity and other possible modifying factors.

SOLUTION:
Dietary fat and obesity: evidence from epidemiology.