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Biomedical subjects

R Brent

Publications and source records attributed to R Brent.

65 records · Page 4Linked to original sources
PubMed1984

Assessing borderline personality disorder with self-report, clinical interview, or semistructured interview.

The authors compared three methods of assessing borderline personality disorders. Test-retest reliability for the self-report Personality Diagnostic Questionnaire was adequate and compared favorably with the interrater reliability of the DSM-III-oriented clinical interview and the semistructured research interview. The overall prevalence of personality disorders scored on the questionnaire was similar to that generated by the clinical interview. The specificity and sensitivity of the questionnaire for the diagnosis of borderline personality disorder were slightly higher than 60%, which suggests that it may be a useful and economical instrument for identifying patients with borderline personality disorder.

Adolescent↗
PubMed1983

LexA protein is a repressor of the colicin E1 gene.

LexA protein is a repressor of several chromosomal genes involved in the SOS response in Escherichia coli. In previous experiments, we found that LexA protein may also be a repressor of the colicin E1 gene. We now present evidence that the purified LexA protein strongly repressed the in vitro transcription of the colicin E1 gene. As determined in DNase I protection experiments, LexA protein bound with a high affinity to the approximately 40-base pair long sequence between the Pribnow box and the start codon of the colicin E1 gene. The sequence of the binding site was composed of two overlapped "SOS boxes" to which the LexA protein bound in a cooperative manner.

Bacterial Proteins↗
PubMed1981

Mechanism of action of the lexA gene product.

Genetic experiments have suggested that the lexA gene product of Escherichia coli represses a number of genes involved in the response to DNA damage, including recA and lexA. We purified the lexA gene product from bacterial strains that bear plasmids that direct the synthesis of large amounts of the protein. Purified lexA protein bound to two symmetrical DNA sequences in front of lexA and one in front of recA, protecting them from digestion with DNase I and blocking methylation of purines in the major groove. lexA protein repressed transcription of both genes in vitro. lexA protein binds to the two sites in front of the lexA gene with approximately the same affinity and with greater affinity to the single site in front of the recA gene. The affinity of lexA protein for its operator sites was measured under conditions that mimic conditions in vivo. Differences in the affinity with which lexA protein binds to the operators of genes it represses may account for the differences in the timing and extent of their induction after DNA damage.

Bacterial Proteins↗
PubMed1981

Fluphenazine resistant psychosis.

A fifty year old female chronic schizophrenic was admitted to hospital following a relapse of her psychosis. She had previously responded well to treatment with trifluoperazine but because of her history of medication non-compliance, a trial of fluphenazine enanthate was instituted. Despite the close chemical similarity between trifluoperazine and fluphenazine the patient failed to respond to the latter in either its oral or depot intramuscular form. Although it is not unusual for a patient to respond to one antipsychotic and not to another, the above case of intra-class non-responsiveness is indeed rare and not readily explained. We present this unusual case and discuss some possible explanations.

Chronic Disease↗
PubMed1981

Rat trophoblastic cell antigenicity.

Trophoblast cells were isolated from the trophoblast giant cell (TGC) layer associated with the rat parietal yolk sac and from the chorioplacenta. Antisera to these cells were produced in the rabbit and analysed with several test systems. Anti-TGC sera reacted with Reichert's membrane (RM), TGC, and chorioplacental trophoblast cells (CTC) by immunodiffusion, and immunofluorescent localization showed that antisera produced against both preparations of trophoblast cells reacted with antigens present in RM and the maternal and renal glomeruli. There was no localization in the trophoblast cells themselves. The abortifacient effects of trophoblastic antisera, which were previously reported, were not found to be due to antisera produced to specific antigens of the trophoblastic preparations which were utilized. In fact the only abortigenic effect observed could be eliminated if the TGC antisera were absorbed with RM. There are several possibilities to explain the presence of antigens in the TGC and CTC which cross-react with RM, and these are discussed, but it is important to recognize that, in the rat, the preparations of antisera to TGC and CTC may produce abortigenic and embryotoxic effects by their actions not on the chorioplacenta, but on the yolk sac placentae. Both the previous reports of embryotoxicity of trophoblastic antisera and our own findings only raise many new questions that have obviously not been answered by this study. But these studies make it quite apparent that any immunological, embryotoxic or teratological studies in the rodent that deal with antigens of the chorioplacenta must include simultaneous immunological and biological studies involving the yolk sac placentae, since dysfunction in either of these placentae can result in various types of reproductive failure.

Animals↗
PubMed1980

The lexA gene product represses its own promoter.

The products of the lexA and recA genes of Escherichia coli regulate the cellular response to DNA damage (the SOS response). Here we describe the cloning of the wild-type lexA gene and the identification of its 24,000-dalton protein product. We also describe construction, by recombination in vitro, of a phage that bears the lexA promoter fused to the lacZ gene. Experiments with this fusion phage and with multicopy plasmids that carry the lexA gene showed that the lexA gene product represses of its own promoter. This repression occurs even if the cell has no recA gene, showing that the lexA protein need not be complexed to the recA protein for activity. Moreover, the presence of multicopy plasmids that carry the lexA gene blocks expression of all SOS responses tested. This presumably results from two effects: (i) repression of the recA gene, the product of which is required to activate many of these responses; and (ii) direct repression of other functions involved in the SOS response.

Bacterial Proteins↗
PubMedDate not supplied

Regulation and autoregulation by lexA protein.

The lexA protein represses many genes in E. coli. When the cell's DNA is damaged, lexA protein is inactivated and these genes are induced. Three aspects of lexA protein's repressor function are reviewed: how it regulates genes of the SOS response, how it regulates its own synthesis, and how it recognizes its operator sites. Recent studies of lexA protein's repressor function have suggested that the concentration of intact lexA protein after induction may determine the detailed control of the SOS response.

Bacterial Proteins↗