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Biomedical subjects

E Dunphy

Publications and source records attributed to E Dunphy.

8 recordsLinked to original sources
PubMed2000

Tat-specific cytotoxic T lymphocytes select for SIV escape variants during resolution of primary viraemia.

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections are characterized by early peaks of viraemia that decline as strong cellular immune responses develop. Although it has been shown that virus-specific CD8-positive cytotoxic T lymphocytes (CTLs) exert selective pressure during HIV and SIV infection, the data have been controversial. Here we show that Tat-specific CD8-positive T-lymphocyte responses select for new viral escape variants during the acute phase of infection. We sequenced the entire virus immediately after the acute phase, and found that amino-acid replacements accumulated primarily in Tat CTL epitopes. This implies that Tat-specific CTLs may be significantly involved in controlling wild-type virus replication, and suggests that responses against viral proteins that are expressed early during the viral life cycle might be attractive targets for HIV vaccine development.

AIDS Vaccines↗
PubMed2000

Alcohol sales to underage adolescents: an unobtrusive observational field study and evaluation of a police intervention.

AIMS: The aims of this study were to assess the ease with which adolescents in the United Kingdom are able to buy alcohol, to obtain information concerning vendors' perceptions of alcohol sales to adolescents, and to evaluate a police intervention intended to reduce underage alcohol sales. DESIGN, SETTING, SUBJECTS: An unobtrusive naturalistic field study was conducted in two urban locations. Pairs of 13- and 16-year-old boys and girls were trained to attempt the purchase of different types of alcohol (alcopops, beer, cider, wine, spirits) from four different types of retail outlets (corner shops, off-licence, public houses and supermarkets), under the supervision of a researcher and typically a parent. The assessment was repeated, with the omission of the 13-year-old boys, following a police intervention in one of the performance sites, consisting of warning letters and visits to vendors, and the issue of a small number of police cautions. A total of 62 underage confederates in all attempted 470 test purchases in phase 1 and 348 in phase 2. Between the two waves of test purchases a sample (n = 95) of the same vendors was surveyed by telephone. FINDINGS: In phase 1, sales resulted from 88.1% of purchase attempts by 16-year-old girls, 77% of attempts by 16-year-old boys, 41.6% of 13-year-old girls and 4.1% of 13-year-old boys. These figures were generally comparable across locations, alcohol types and outlet types. Refusals were more likely when another vendor was present. Eighty per cent of sales to 16-year-olds and 65% of sales to 13-year-old girls were made without challenge. "Prove-It" ID cards were requested in fewer than 12% of purchase attempts in both age groups. Overall, there was no evidence that the police intervention reduced sales of alcohol to 16-year-olds. There was a hint that the intervention may have caused a very short-lasting decrease in sales to 13-year-old girls, but this was contained within an overall increase in sales to this group. Alcohol vendors reported that they rarely encountered underage customers or refused sale though 90% of vendors said that if they became suspicious, they would request ID. Only two vendors believed that they were likely to suffer adverse consequences if they sold alcohol to minors. CONCLUSIONS: These data suggest that 16-year-olds, and girls as young as 13, have little difficulty in purchasing alcohol, and that there is little difference between different types of outlets in their willingness to sell alcohol to minors. Vendors perceive little risk in selling alcohol to adolescents. The fact that the police intervention failed to decrease sales suggests that vendors do not change their behaviour in response to the threat of legal action.

Adolescent↗
PubMed1996

Prolonged c-jun expression in irradiated ataxia telangiectasia fibroblasts.

PURPOSE: Ataxia telangiectasia (AT) is an autosomal recessive disorder associated with radiation sensitivity and an increased incidence of leukemia, lymphoma, and some solid tumors. After exposure to ionizing radiation, cells from patients with AT demonstrate an attenuated G1-phase checkpoint. Because c-jun is known to regulate, in part, the exit from G1 and the onset of DNA replication, we analyzed c-jun transcription in irradiated AT fibroblasts. METHODS AND MATERIALS: AT5BI fibroblasts were irradiated and RNA was extracted and assayed for c-jun expression by Northern blot analysis. Transcriptional regulation of c-jun was evaluated by use of the 5' untranslated region of the jun promoter linked to the chloramphenicol acetyl transferase (CAT) reporter gene. Deletion mutants of the RSRF, SP-1, AP-1 and CCAAT domains within the jun promoter linked to the CAT reporter were transfected into AT5BI cells. Transfectants were irradiated, and CAT expression was quantified. After x-irradiation, nuclear protein binding to CCAAT was evaluated by an electrophoretic mobility shift assay. RESULTS: X-ray-mediated c-jun expression was sustained in AT5BI cells as compared to only transient expression in irradiated normal diploid fibroblasts. Mutation of either the AP-1 or CCAAT domains within the c-jun promoter reduced transcription by 50% and combined deletion of both AP-1 and CCAAT cis-acting elements entirely eliminated radiation-mediated transcriptional activation. Electrophoretic mobility gel shift assay of the nuclear proteins isolated from irradiated AT fibroblasts demonstrated their increased binding to the CCAAT sequence at 30 min after irradiation. Competition for nuclear protein binding to the CCAAT sequence with excess cold CCAAT demonstrated that protein binding to this sequence was specific. These findings were distinct from induction by phorbol esthers in that the RSRF cis-acting element and DNA segments upstream of -132 base pairs do participate in c-jun induction by phorbol esthers but not by radiation. CONCLUSIONS: Radiation-mediated transcriptional regulation of c-jun is prolonged in AT fibroblasts and is regulated in combinatorial control by the AP-1 and CCAAT domains, and transcriptional regulation is distinct from that induced by phorbol esthers.

Ataxia Telangiectasia↗
PubMed1995

C-jun and Egr-1 participate in DNA synthesis and cell survival in response to ionizing radiation exposure.

Exposure of mammalian cells to ionizing radiation results in the induction of the immediate early genes, c-jun and Egr-1, which encode transcription factors implicated in cell growth as well as the cellular response to oxidative stress. We studied the role of these immediate early genes in cell cycle kinetics and cell survival following x-irradiation of clones containing inducible dominant negatives to c-jun and Egr-1. The dominant negative constructs to c-jun (delta 9) and Egr-1 (WT/Egr) prevented x-ray induction of transcription through the AP-1 and Egr binding sites, respectively. Twenty percent of confluent, serum-deprived SQ20B human tumor cells, normal fibroblasts, and fibroblasts from patients with ataxia telangiectasia entered S phase within 5 h of irradiation. Clones containing inducible delta 9 and WT/Egr dominant negative constructs demonstrated attenuation of the percentage of cells exiting G1 phase and reduced survival following irradiation. These data indicate that the dominant negatives to the stress-inducible immediate early genes Egr-1 and c-jun prevent the onset of S phase and reduce the survival of human cells exposed to ionizing radiation.

Cell Cycle↗
PubMed1992

Occurrence of p53 gene deletions and human papilloma virus infection in human head and neck cancer.

Little is known regarding the molecular genetic events in head and neck carcinoma. Epidemiological evidence suggests that both alcohol and tobacco use are related to the development of these neoplasms, and viral infections have also been postulated to play a role in some tumors. Loss of p53 tumor suppressor gene function has been found in many malignancies and can occur through either gene mutation or by interaction with the E6 protein of oncogenic human papilloma viruses (HPV). Because the mucosal surfaces of the head and neck are exposed to mutagens and HPVs, we studied DNA derived from 30 stage I-IV squamous cell carcinomas of the head and neck (9 primary tumors and 21 early passage cell lines) for p53 gene mutations as well as for the presence of oncogenic HPV DNA. Exons 2 through 11 of the p53 gene were examined using single strand conformation polymorphism analysis followed by direct genomic sequencing of all variants. HPV detection was done using polymerase chain reaction amplification with HPV E6 region type specific primers as well as L1 region degenerate ("consensus") primers; HPV type was determined by restriction fragment length polymorphism analysis of the amplified fragment as well as by Southern blotting of genomic DNA. Sixteen of 30 tumors (53%) had p53 mutations and oncogenic HPV DNA was detected in 3 of 30 (10%) tumors, none of which had p53 mutations. The p53 mutational spectrum observed was characterized by equal frequencies of transversions (6 of 16), transitions (5 of 16), and deletions (5 of 16). This distribution of mutations differs from the spectrum of p53 mutation reported in esophageal (P = 0.05) and lung (P = 0.02) cancers, two other tobacco associated neoplasms. A previously undescribed clustering of 3 mutations at codon 205 was also observed. A trend toward a shorter time to tumor recurrence after treatment was noted for those patients with tumors exhibiting p53 gene mutations, and no relationship between p53 mutations and tumor stage or node status was noted. Alteration in p53 gene function appears common in head and neck cancer, and the mutational spectrum observed may reflect the role of different mutagens or mutagenic processes than those responsible for the p53 mutations in lung and esophageal neoplasms.

Alcohol Drinking↗
PubMed1985

The labelling index of human and mouse tumours assessed by bromodeoxyuridine staining in vitro and in vivo and flow cytometry.

Bromodeoxyuridine (BrdUrd) incorporation and flow cytometry were used to measure human tumour kinetic parameters in vitro and in vivo. The technique was validated by comparison of labelling index estimates of mouse tumours in vivo and in vitro using BrdUrd and flow cytometry with tritiated thymidine (3HdThd) autoradiography. Similar labelling indices were obtained with both in vivo and in vitro incorporation into DNA of the two different precursors. Measurements of human tumour labelling indices were similar following in vitro incubation with either BrdUrd or 3HdThd. The use of BrdUrd allowed the visualization of a population of S-phase cells that did not appear to incorporate BrdUrd or 3HdThd. The human tumour labelling indices obtained with BrdUrd incorporation were similar to previously reported values using autoradiography studies. Preliminary studies demonstrated that significant human tumour labelling could be achieved with an intravenous injection of 500 mg BrdUrd.

Animals↗
PubMed1975

Appendicitis. A critical review of diagnosis and treatment in 1,000 cases.

One thousand cases of appendicitis seen from 1963 to 1973 were reviewed. The overall negative appendectomy rate was 20%, but in women between ages 20 and 40 it exceeded 40%. Two thirds of the negative appendectomies were due to nonsurgical lesions. Mesenteric adenitis, gastroenteritis, and abdominal pain of unknown cause accounted for one third of the errors in females and two thirds in males. These diseases were best distinguished from appendicitis on the basis of temperature and white blood cell count. The remainder of the errors in females were due to pelvic inflammatory disease or other gynecologic diagnosis and were best distinguished from appendicitis on the basis of history and physical findings. The rate of perforation was 21% overall. The incidence of wound infection was 8.5%. Use of systemic antibiotics did not affect the wound infection rate.

Adolescent↗