Lack of class I H-2 antigens in cells transformed by radiation leukemia virus is associated with methylation and rearrangement of H-2 DNA

Transformation of murine thymocytes by radiation leukemia virus is associated with reduced expression of the class I antigens encoded in the major histocompatibility complex (MHC) and increased methylation and altered restriction enzyme patterns of MHC DNA. These changes may play a role in host susceptibility to virus-induced leukemogenesis and accord with the notion that viral genomes play a regulatory function when they integrate adjacent to histocompatibility genes.     

Murine leukemia virus sequences are encoded in the murine major histocompatibility complex.

The studies reported here localize murine leukemia viral sequences to the TL region of the major histocompatibility complex, H-2. We examined a battery of 38 cosmids, isolated from two large genomic libraries constructed from C57BL/10 spleen DNA, that define 25 class I gene sequences. The viral probes used hybridized with only four cosmids, containing overlapping mouse sequences, that define four class I gene-related sequences in a region of 90 kilobases of DNA. The data show that two distinct viral envelope sequences are contained in the cluster. One of these sequences is situated with its 3' end next to the 3' end of a class I sequence. The other sequence, which does not contain the entire viral envelope, is proximal to the 3' end of a different class I sequence. Hybridization of the viral probes with the H-2 cosmid clones does not appear to be due to homology between viral and H-2 sequences. Rather, the viral sequences detected appear to be linked to or inserted amid class I genes. These findings may be significant in understanding molecular mechanisms involved in the generation of H-2 class I gene diversity.     

Structure and expression of genes encoding murine Qa-2 class I antigens.

DNA structural analysis of the Qa region in two BALB/c mouse substrains with different Qa-2 phenotypes reveals that a deletion of DNA has occurred in BALB/cBy (Qa-2-) mice relative to BALB/c (Qa-2+) mice. We propose that this deletion arises from unequal crossing-over and recombination between adjacent BALB/c class I genes and results in the generation of a hybrid class I gene in BALB/cBy mice. Furthermore, we suggest that this is a direct cause of the change in Qa-2 phenotype. Further support for this model was obtained from transfection experiments in which cloned genes from the equivalent part of the Qa region in C57BL/10 mice were introduced into L cells. Four C57BL/10 genes, arranged in two almost identical pairs, encode polypeptides that are precipitated from lysates of transfectants with anti-Qa-2/3 antiserum. Although loss of one pair of these genes in BALB/c mice has no qualitative effect on Qa-2 phenotype, the loss of both pairs of genes via gene fusion leads to the loss of the Qa-2+ phenotype in BALB/cBy mice.     

A test of the resource security and the body mass index reference point hypotheses of body dissatisfaction amongst adolescents in eight countries

Objective. This study aimed to identify cultural-level variables that may influence the extent to which adolescents from different cultural groups are dissatisfied with their bodies.

Design. A sample of 1730 male and 2000 female adolescents from Australia, Fiji, Malaysia, Tonga, Tongans in New Zealand, China, Chile, and Greece completed measures of body satisfaction, and the sociocultural influences on body image and body change questionnaire, and self-reported height and weight. Country gross domestic product and national obesity were recorded using global databases.

Results. Prevalence of obesity/overweight and cultural endorsement of appearance standards explained variance in individual-level body dissatisfaction (BD) scores, even after controlling for the influence of individual differences in body mass index and internalization of appearance standards.

Conclusions. Cultural-level variables may account for the development of adolescent BD.     

Complications of a simple procedure: de Quervain's disease revisited

We reviewed the results of 22 operations performed on 21 patients for the relief of de Quervain's disease over the last six years. At a mean follow-up of 34 months (range 4-78 months), 18 of 22 wrists had complete relief of their original symptoms. One patient required reoperation because of inadequate decompression, and two others await further surgery. Most operations (14 out of 22) were performed under local anaesthesia, and 17 out of 22 used a longitudinal incision. The use of a longitudinal incision was associated with a significant risk of complications: four patients had a poor cosmetic result, and six showed evidence of superficial radial nerve injury. Two patients had a wound infection, and one developed reflex sympathetic dystrophy. Although surgical decompression for de Quervain's disease is effective in curing the symptoms in most patients, using a longitudinal incision is associated with poor wound healing and damage to the terminal branches of the radial nerve.     

Magnetic resonance imaging in neurological disorders.

To investigate the role of magnetic resonance imaging (MRI) in neurological disorders, 115 children were studied in two groups. Group A (78 patients) was studied by paired computed tomography and MRI cranial scans. Group B (37 patients) was studied by paired computed tomography assisted myelography (CTM) and MRI spinal scans. In group A, the scans were generally equivalent for supratentorial tumours and for investigating fits, hydrocephalus, benign intracranial hypertension, and cerebral atrophies, but MRI scanning was superior for posterior fossa tumours and cysts. In group B, MRI scans were superior for intramedullary spinal tumours, spinal dysraphic problems with tethering or syrinx, and were complementary to CTM in diastematomyelia.