Separation of the complex DNA binding domain of EBNA-1 into DNA recognition and dimerization subdomains of novel structure.

EBNA-1 is essential for replication of the latent episomal form of the Epstein-Barr virus genome and is involved in regulation of viral latency promoters. EBNA-1 activity is mediated through direct DNA binding. The DNA binding and dimerization functions of EBNA-1 have previously been located to a carboxy-terminal domain, amino acids (aa) 459 to 607. To identify and define the subdomains for these two functions, we created an extensive series of deletions and point mutations in an EBNA-1 (aa 408 to 641) background. The ability of the EBNA-1 mutants to heterodimerize with a wild-type EBNA-1 (aa 459 to 641) Immunoprecipitation assays with a monoclonal antibody, EBNA.OT1x, that recognizes EBNA-1 (aa 408 to 641) but not EBNA-1 (aa 459 to 641). These experiments revealed that mutations affecting dimerization occurred over two separate regions, aa 501 to 532 and aa 554 to 598. DNA binding was tested in mobility shift assays against a panel of oligonucleotide-binding sites. Dimerization was a prerequisite for DNA binding. The DNA recognition domain was localized to a separate region, aa 459 to 487, upstream of the dimerization domain. EBNA-1 variants carrying substitutions at aa 467 and 468 and at aa 477 gave a pattern of binding to mutant oligonucleotide probes that implicates these particular amino acids in DNA recognition. EBNA-1 appears to utilize novel mechanisms for both DNA recognition and dimerization since neither domain conforms to previously described structural motifs.     

Compliance therapy in psychotic patients: randomised controlled trial.

OBJECTIVE--To determine whether compliance therapy, a cognitive-behavioural intervention, could improve compliance with treatment and hence social adjustment in acutely psychotic inpatients, and if so, whether the effect persisted six months later. DESIGN--Randomised controlled trial of compliance therapy and non-specific counselling, each comprising 4-6 sessions lasting 10-60 minutes. SETTING--Acute psychiatric admissions ward serving an inner London catchment area. SUBJECTS--47 patients with psychosis. MAIN OUTCOME MEASURES--Informant and observer reported measure of compliance; observer assessed global functioning after intervention and three and six months later; self-rated attitudes to drug treatment after the intervention and one month later; symptom scores after intervention and six months later. RESULTS--25 patients received compliance therapy and showed significantly greater improvements in their attitudes to drug treatment and in their insight into illness and compliance with treatment compared with the control group. These gains persisted for six months. The intervention group was 5.2 times more likely than the control group to reach a criterion level of compliance (95% confidence interval 1.5 to 18.3). Global functioning showed a tendency to improve more in the intervention group after a delay (odds ratio 3.0 (0.8 to 11.5) to reach the criterion level at six months). Four subjects given compliance therapy and six in the control group were readmitted during follow up (odds ratio 2.0 (0.48 to 8.2)). CONCLUSIONS--Compliance therapy is a pragmatic method for improving compliance with drug treatment in psychotic inpatients and its gains persist for at least six months. Overall functioning may also be enhanced.     

Prenatal diagnosis of cystic fibrosis by assay of amniotic fluid microvillar enzymes

Summary Activities of the microvillar enzymes -glutamyl-transpeptidase (GGTP), aminopeptidase M (APM), phosphodiesterase and maltase have been examined in second-trimester amniotic fluid as possible aids to the early prenatal diagnosis of cystic fibrosis (CF). The two peptidases, GGTP and APM, gave best results. If the fifth percentile of the normal range is used as an action line, the sensitivity of a positive test (low GGTP value) is 78% and the predictability 84%. At the tenth percentile the sensitivity is 100% and the predictability 77%. These approximate figures apply only to pregnancies where there has been a previous affected child. Until the primary protein defect in CF is discovered, this may prove an acceptable form of prenatal diagnosis to the high-risk mother.     

Effect of glycaemic control and duration of disease on overnight albumin excretion in diabetic children.

Urine albumin excretion rates were measured in overnight timed samples from diabetic and non-diabetic schoolchildren. The excretion rates in the diabetics were significantly higher than those in the controls and were positively correlated with age, duration of diabetes, and glycaemic control. Diabetic children aged 12 years and older had significantly higher albumin excretion rates than younger diabetic children matched for duration of disease. Among the non-diabetic controls there was no correlation between albumin excretion rate and age and the girls excreted significantly more albumin than the boys. Measurement of the overnight albumin excretion rate may provide a useful early indicator of the progression to clinical proteinuria in diabetes and is free from random variations such as that due to exercise.     

Characterization of some isolates of newly recovered avian sarcoma virus.

We previously reported the isolation of a newly recovered avian sarcoma virus (rASV) from tumors of chickens injected with transformation-defective (td) mutants of the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV). In this paper, we present further biological and biochemical characterization of the recovered sarcoma viruses. High titers of rASV's were generally obtained by cocultivation of tumor cells with normal chicken embryo fibroblasts or by homogenization of tumor tissues. Most rASV isolates were similar to SR-RSV, subgroup A (SR-RSV-A), in their growth characteristics and were nondefective in replication. The subgroup specificity of rASV's and the electrophoretic mobilities of their structural proteins were the same as those parental td viruses. The nondefectiveness of rASV's was further substantiated by the size of their genomic RNA, which was indistinguishable from that of SR-RSV-A and substantially larger than that of parental td RNA. Molecular hybridization using complementary DNA specific to the src gene of SR-RSV (cDNAsrc) showed that the RNAs of td mutants used in this study contained extensive deletions within the src gene (7 to 30% hybridization with cDNAsrc); the same probe hybridized up to 90% with RNA from two isolates of rASV. These data indicate that rASV has regained genetic information which had been deleted in the td mutants and strongly suggest that the generation of rASV involves a genetic interaction between td virus and host cell genetic information.     

Fc-receptor heterogeneity of human suppressor T cells.

Concanavalin A (Con A) stimulated the IgM-binding subpopulation of human T cells (TM) to suppress the pokeweed mitogen-induced differentiation of B lymphocytes to plasma cells. Control TM cells that had not been Con A activated did not suppress. The degree of suppression was related to the number of Con A-TM cells added to the cultures and it was abolished by irradiation of the T lymphocytes either before or after the 24-hr culture period with Con A. Suppression did not require the presence of TG cells, whose suppressor potential has been previously established. These findings indicate that suppressor activity is not confined to the TG subpopulation but may be expressed by TM cells also.