Rabbit immunoglobulin kappa genes: structure of a germline b4 allotype J-C locus and evidence for several b4-related sequences in the rabbit genome.

To investigate the genetic mechanism by which certain rabbits can express immunoglobulins unexpected on the basis of their pedigree (i.e., "latent" allotypes), we have begun a study of the rabbit immunoglobulin kappa gene locus. Here we report the structure of a germline genomic clone that encodes the b4 allotype of rabbit kappa immunoglobulin and corresponds to the kappa gene expressed by the rabbit-mouse hybridoma 12F2. The nucleotide sequences of the joining (J) and constant (C) regions reveal structures generally similar to the homologous mouse and human loci, although only one of the five J-like sequences of this rabbit gene is apparently expressed. Southern blotting analysis of DNA from several rabbit allotypic strains by using probes derived from the cloned b4 gene demonstrates that, in contrast to mouse and human, rabbits possess multiple kappa-related sequences. Rabbits of the nominal b4, b5, b6, and b9 allotypes each contain at least two b4-related sequences that are associated with their own J regions and that are highly homologous to the cloned b4 gene in both coding and flanking regions.     

Postural imbalance: An early sign in HIV-1 infected patients

Summary We have recorded postural performance in 50 HIV-infected patients in different stages of the disease (Walter Reed (WR) stages I–VI) by means of a force measuring platform. The results were compared with 50 age-matched controls. A significant instability was particularly evident when standing on an unstable foot support. In patients standing with eyes closed, postural sway was significantly higher in every patient group (WR I–II:P<0.02, WR III–V:P<0.001, WR VI:P<0.001). Patients in stage WR I–II showed no relevant neurological abnormalities. In agreement with other neurophysiological data in the literature we suggest that postural imbalance could be an early sign of central nervous system penetration of HIV. No correlation with electromyographic or cerebrospinal fluid findings could be found.     

Tri-dimensional automatic segmentation of PET volumes based on measured source-to-background ratios: influence of reconstruction algorithms.

A method for automatic volume segmentation of functional imaging based on a relationship between source-to-background ratio and the iso-activity level to be used is described. Such method, which has been established with radioactive spheres in a phantom, is independent of the a priori knowledge of the lesion of interest and is valid for small (>2 ml) and/or poorly contrasted (S/B>1.5) lesions. Accuracy varies slightly with the image reconstruction algorithm used.