Three gene families that rearrange during the somatic development of T cells have been identified in the murine genome. Two of these gene families (alpha and beta) encode subunits of the antigen-specific T-cell receptor and are also present in the human genome. The third gene family, designated here as the gamma-chain gene family, is rearranged in murine cytolytic T cells but not in most helper T cells. Here we present evidence that the human genome also contains gamma-chain genes that undergo somatic rearrangement in leukaemia-derived T cells. Murine gamma-chain genes appear to be encoded in gene segments that are analogous to the immunoglobulin gene variable, constant and joining segments. There are two closely related constant-region gene segments in the human genome. One of the constant-region genes is deleted in all three T-cell leukaemias that we have studied. The two constant-region gamma-chain genes reside on the short arm of chromosome 7 (7p15); this region is involved in chromosomal rearrangements identified in T cells from individuals with the immunodeficiency syndrome ataxia telangiectasia and observed only rarely in routine cytogenetic analyses of normal individuals. This region is also a secondary site of beta-chain gene hybridization.
To assess familial aggregation of autism, 86 autistic subjects were linked to the Utah Genealogical Database. Kinship coefficients were estimated for all possible pairs of autistic subjects and then averaged. Fifty replicate sets of matched control subjects (86 members in each set) were drawn randomly from the database, and the average kinship coefficient was computed for all possible pairs of individuals in each set. The average kinship coefficient for the autistic subjects was approximately 1/1,000, while the average kinship coefficients for the 50 control groups ranged from 4/100,000 to 1.6./10,000. These results indicate a strong tendency for autism to cluster in families. When kinship was analyzed by specific degrees of relationship, it was shown that the familial aggregation of autism is confined exclusively to sib pairs and does not extend to more remote degrees of relationship. This finding indicates that a single‐gene model is unlikely to account for most cases of autism.
Background: Normal cardiovascular control involves nonstationary complex interactions between a variety of variables such as heart rate (HR), arterial blood pressure (ABP), and respiratory activity.Methods: To account for both the complexity and transient nature of these phenomena, a closedloop bivariate and time-variant (moving window) model was implemented using autoregressive parametric techniques to identify the typical HR and ABP spectral parameters of low frequency power (LF, 0.03-0.15 Hz), high frequency power (HF, 0.15-0.45 Hz), and their ratio LF/HF. In addition, cross-parameters, such as the gain, phase, and coherent power, between HR, ABP, and changes in instantaneous lung volume (ILV) were computed in both the LF and HF regions.
Results:The cross-relations included the HR baroreflex (ABP-HR, alpha), respiratory sinus arrhythmia (ILV-HR), the mechanical influence of respiration (ILV-ABP), and the mechanical feedforward of HR (HR-ABP, beta). The analyses were performed on data from a gradual tilt protocol, which simulates the physiological nonstationarities encountered in daily life.
Conclusions:The results were similar to those obtained using a bivariate batch (nonmoving window) Levinson-Wiggins-Robinson algorithm, but the time-variant technique was able to provide nearly continuous parameters, allowing for a real-time continuous monitoring of circulatory control. heart rate variability; arterial blood pressure variability; baroreflex; respiratory sinus arrhythmia;autonomic nervous system; time-variant spectral analysis
Functional analysis of mutant class II major histocompatibility complex molecules has begun to identify regions important for antibody binding and for T-cell activa-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.