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Biomedical subjects

P Stephenson

Publications and source records attributed to P Stephenson.

At least 19 recordsLinked to original sources
PubMed1995

Cytotoxic and clastogenic effects of benzyl isothiocyanate towards cultured mammalian cells.

Benzyl isothiocyanate (BITC), a compound found in cruciferous vegetables present in the human diet, has previously been shown to induce chromosome aberrations in an Indian muntjac cell line. The results of this study show that it also induces both chromosome aberrations and sister chromatid exchanges (SCEs) in Chinese hamster ovary (CHO) cells in the absence of an exogenous metabolic activation system and induces DNA strand breaks as measured by the single-cell gel electrophoresis assay. However, whereas it increased the number of aberrations four-fold, it was not able to raise SCE levels by more than 50% and there was a levelling-off in the dose-response curve. Whereas the survival curve of CHO cells exposed to BITC was linear in shape, that of the human colorectal adenocarcinoma cell line HT29 was found to fit the exponential model (with an alpha equivalent of 0.28 and a beta equivalent of 2.80, where the concentration of BITC is measured in micrograms/ml). This pattern of clastogenic and cytotoxic activities is reminiscent of that generated by ionizing radiation and certain radiomimetic chemotherapeutic agents.

Adenocarcinoma↗
PubMed1995

Selective toxicity of compounds naturally present in food toward the transformed phenotype of human colorectal cell line HT29.

It has previously been observed that allyl isothiocyanate, a compound naturally present in the diet, is more cytotoxic toward the human colorectal adenocarcinoma cell line HT29 in its control transformed state than after exposure to sodium butyrate or to dimethylformamide, which slow growth and induce differentiation (detransformation). In the present study, a range of other dietary compounds were assayed for such selective toxicity. These compounds were chosen as constituents of foodstuffs that have been identified from epidemiologic studies as being potentially antitumorigenic and also as having anticarcinogenic activity in experimental models. Benzyl and phenethyl isothiocyanate, benzyl thiocyanate, and quercetin showed decreased toxicity towards HT29 after detransformation of the cells by one or both treatments, whereas no change was observed in the sensitivity to diallyl sulfide or diallyl disulfide. It is proposed that the presence of such selectively toxic compounds in the diet may inhibit the development of tumors by interfering with the growth of preneoplastic lesions while having little effect on normal cells. The cumulative effects of these inhibitions may contribute to the chemopreventive properties of the parent foodstuffs observed in epidemiologic studies.

Adenocarcinoma↗
PubMed1995

Changes in locus-of-control attitudes about drug misuse in a self-help group in a methadone maintenance clinic.

Clients of a methadone-maintenance clinic in Brooklyn, New York participating in a clinically-guided self-help (CGSH) program plus standard treatment (methadone maintenance plus individual counseling) demonstrated statistically significant changes in locus-of-control beliefs, from external to internal causation, about personal responsibility for drug misuse. Members of two control groups--one participating in a didactic lecture program plus standard treatment and the other receiving only standard treatment--failed to demonstrate similar changes. This increase in internal locus of control in the CGSH group suggests the potential efficacy of CGSH as a relapse-prevention therapeutic technique.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Careprovider and obstetrical interventions--a comparative study of four European countries.

The purpose of this study was to compare the treatment recommendations of obstetricians and midwives in four European countries: the Czech Republic, Finland, Hungary, and Slovenia. Intervention orientation was examined with six hypothetical patient cases. We wanted to learn whether midwives differ from obstetricians in their choices, and whether there is any variation among countries regarding the willingness of staff to intervene. In Finland the two professions were quite similar in their recommendations for interventions, but in Hungary and Slovenia, midwives and obstetricians differed from each other. There were also differences between the countries in the treatment recommendations, and there was disparity between opinions and actual obstetrical practices. Slovenian obstetrical staff were the most interventionistic in many cases, compared with others, although the actual frequency of interventions was no greater than in other countries. In Finland the staff were the most passive in their opinions, yet the actual proportion of interventions was greatest.

Adult↗
PubMed1993

Audit of a system for dealing with a practice's laboratory test results.

In order to improve efficiency in a non-computerized practice of 4700 patients the system for dealing with laboratory test results and communicating them to patients was audited over a two-week period. The audit involved a questionnaire for the practice team, a postal questionnaire to 36 patients, and an analysis of doctors' and receptionists' workload when dealing with laboratory test results. A new system was introduced, with two receptionists logging investigation details into a newly designed results book, and with date/process stamping of results. The new system was re-audited using another practice questionnaire and analysis of doctors' and receptionists' workload and found to be as effective as the old system but less time consuming, largely owing to the layout of the new results book. All members of the practice team were more satisfied with the new system. The function of a results book and its role in doctor-patient communication is discussed.

Diagnostic Services↗
PubMed1992

Health care consequences of the European economic community in 1993 and beyond.

Generally, health services are not covered by the treaties of the European Community. However, to an increasing extent the EC has and will have an influence on national health systems. In particular the effects of regulations made for other sectors have repercussions for health. For example the free movement of labour and the harmonization initiatives have direct effects on the educational curricula for health professions and may, in time increase professional migration within the community. Within the EC research programmes health related topics have been included to an increasing extent. This goes in particular for medical informatics, standardization, quality assurance systems and pharmaceuticals. Indirect effects of the single market will probably appear within the area of insurance, public purchasing and building and other types of construction works. Other areas that probably will be influenced are record security and occupational health benefits.

Cross-Cultural Comparison↗
PubMed1992

Commentary: the public health consequences of restricted induced abortion--lessons from Romania.

The question of whether abortion should be legal is currently being decided in many countries. Although much of the discussion has focused on ethical issues, the public health consequences should not be overlooked and should be addressed realistically and responsibly. Nowhere are the public health manifestations of restricted abortion more apparent than in Romania. The pronatalist policies of the Ceaucescu regime resulted in the highest maternal mortality rate in Europe (approximately 150 maternal deaths per 100,000 live births) and in thousands of unwanted children in institutions.

Abortion, Illegal↗
PubMed1991

In vitro cleavage of an N-ras messenger-like RNA by a ribozyme.

A cDNA library was constructed in lambda gt10 from T-15 cells, a transformed mouse fibroblast line. The transforming N-ras sequence was recovered and subsequently used as a substrate for ribozyme cleavage. The design of the ribozyme was based on that of the hammerhead structure of the satellite tobacco ringspot autolytic processing sequence. Specificity to the N-ras substrate was conferred by 10 nucleotides homologous to the target site on the mRNA positioned on either side of the catalytic unit. The cleavage reaction was most efficient at higher temperatures but efficiency at lower temperatures was improved by the inclusion of urea in the reaction mixture. The ribozyme failed to cut an antisense ras sequence even at high temperature or in the presence of urea.

3T3 Cells↗
PubMed1990

Comparison of non-mydriatic retinal photography with ophthalmoscopy in 2159 patients: mobile retinal camera study.

OBJECTIVE: To determine whether non-mydriatic Polaroid retinal photography was comparable to ophthalmoscopy with mydriasis in routine clinic screening for early, treatable diabetic retinopathy. DESIGN: Prospective study of ophthalmoscopic findings according to retinal camera screening and ophthalmoscopy and outcome of referral to ophthalmologist. SETTING: Outpatient diabetic clinics of three teaching hospitals and three district general hospitals. PATIENTS: 2159 Adults selected randomly from the diabetic clinics, excluding only those registered as blind or those in wheelchairs and unable to enter the screening vehicle. MAIN OUTCOME MEASURES: Numbers of patients and eyes correctly identified by each technique as requiring referral with potentially treatable retinopathy (new vessel formation and maculopathy) and congruence in numbers of microaneurysms, haemorrhages, and exudates reported. RESULTS: Camera screening missed two cases of new vessel formation and did not identify a further 12 but indicated a need for referral. Ophthalmoscopy missed five cases of new vessel formation and indicated a need for referral in another four for other reasons. Maculopathy was reported in 147 eyes with camera screening alone and 95 eyes by ophthalmoscopy only (chi 2 = 11.2; p less than 0.001), in 66 and 29 of which respectively maculopathy was subsequently confirmed. Overall, 38 eyes received laser treatment for maculopathy after detection by camera screening compared with 17 after ophthalmoscopic detection (chi 2 = 8.0; p less than 0.01). Camera screening underestimated numbers of microaneurysms (chi 2 = 12.9; p less than 0.001) and haemorrhages (chi 2 = 7.4; p less than 0.01) and ophthalmoscopy underestimated hard exudates (chi 2 = 48.2; p less than 0.001). CONCLUSIONS: Non-mydriatic Polaroid retinal photography is at least as good as ophthalmoscopy with mydriasis in routine diabetic clinics in identifying new vessel formation and absence of retinopathy and is significantly better in detecting exudative maculopathy.

Adolescent↗
PubMed1988

MMPI-168 profiles of male narcotic addicts by ethnic group and city.

MMPI-168 profiles were obtained on 225 male narcotic addicts who were attending methadone maintenance clinics in Baltimore and New York City during 1983 and 1984. Data were collected on Black and White (Anglo, other than Hispanic) addicts in Baltimore and on Black, Hispanic, and White addicts in New York City. In general, the profiles indicated high levels of psychopathology, with particularly high elevations on the F, D, PD, PT, and Sc scales. Consistent across cities and in agreement with earlier findings, profiles of Whites indicated somewhat more maladjustment than those for Blacks, while the profiles of Hispanics displayed essentially the same levels of disturbance as those for Whites. Comparisons by city revealed greater deviance for New York City subjects, a finding more evident among Whites than among Blacks.

Ethnicity↗
PubMed1988

High esophageal stricture: a complication of "inlet patch" mucosa.

High esophageal stricture associated with a circumferential "inlet patch" of heterotopic gastric mucosa is reported in 2 patients. Biopsy specimens taken from the strictures demonstrated inflamed or ulcerated gastric fundal-type mucosa in both cases. Dilatation of the strictures followed by treatment with histamine H2-antagonists produced almost complete resolution of dysphagia in both patients.

Adult↗
PubMed1988

Differences among treatment clinic types in attitudes toward narcotic addiction.

Factor analysis of data from a general survey of attitudes and opinions concerning narcotic addiction and its treatment revealed 10 major dimensions, five of which were likely to have significant implications for drug abuse intervention strategies. For these latter dimensions, differences were determined among clients and staff according to type of treatment clinic (three types involving the provision of methadone maintenance in various combinations with other treatments and one involving the use of abstinence only). The most pronounced differences were between the methadone clinics and those offering abstinence only. Both the clients and staff of abstinence clinics were more skeptical concerning treatment effectiveness, were more negative regarding the use of narcotic drugs, and were more disposed to the use of ex-addict counselors and group procedures in treatment.

Black or African American↗
PubMed1987

Angina bullosa haemorrhagica: clinical and laboratory features in 30 patients.

Angina bullosa haemorrhagica (ABH) is a relatively recently recognized bullous disorder in which recurrent oral blood blisters appear in the absence of any identified systemic disorder. This study has examined the clinical, histologic, immunologic, and hemostatic features of 30 British patients and demonstrates that ABH is predominantly a localized disorder of middle-aged or elderly patients of either sex that is evident mainly as blood blisters on the soft palate. Trauma appears to be the most common identifiable precipitating factor, but the essential tissue defect is as yet unidentified.

Aged↗
PubMed1987

Angina bullosa haemorrhagica: lesional immunostaining and haematological findings.

The aetiology of angina bullosa haemorrhagica remains obscure. Fourteen patients with clinical features suggestive of angina bullosa haemorrhagica were investigated. Haemostatic function tests were carried out on an initial 5 patients and immunostain studies on a total of 12 patients. The results indicate that the aetiology of angina bullosa haemorrhagica is associated with neither a haemostatic defect, nor an immunopathogenic basis, and the cause is, as yet, unclear.

Aged↗
PubMed1987

Attitudes toward narcotic addiction.

In an effort to isolate the major dimensions of attitude and expectation regarding narcotic addiction and its treatment and to compare different groups of addict/clients and agency staff on these factors, a comprehensive questionnaire was administered to 900 addict/clients and 237 agency personnel in 25 drug treatment clinics in six states. Results of a factor analysis, which used questionnaire data from all of the 1137 subjects so that direct group comparisons could be made, indicated the presence of 10 major dimensions of attitude and expectation. Results also suggested considerable variation, particularly by status (client vs. staff) and ethnic group, on these dimensions. An additional analysis of staff attitudes and expectations revealed correlations with years of education, ex-addict status, and years of work experience. Such findings suggest the need to consider client/staff characteristics and attitudes in the planning of treatment services for narcotic addicts. An abbreviated (53-item) attitude and expectation questionnaire was developed for this purpose.

Adult↗
PubMed1987

Products of in vitro cleavage and polyadenylation of simian virus 40 late pre-mRNAs.

Formation of mRNA 3' termini involves cleavage of an mRNA precursor and polyadenylation of the newly formed end. Cleavage of simian virus 40 late pre-mRNA in a crude nuclear extract generated two RNAs, 5' and 3' half-molecules. These RNAs were unmodified and linear. The 5' half-molecule contained sequences upstream but not downstream of the poly(A) site and ended in a 3'-terminal hydroxyl. The 3' half-molecules comprised a family of RNAs, each of which contains only sequences downstream of the poly(A) site, and ends in a 5'-terminal phosphate. These RNAs differed only in the locations of their 5' terminus. The 3' terminus of the 5' half-molecule was the adenosine 10 nucleotides downstream of AAUAAA, at the +1 position. The 5' terminus of the longest 3' half-molecule was at +2. Thus, these two RNAs contain every nucleoside and phosphate of the precursor. The existence of these half-molecules demonstrates that endonucleolytic cleavage occurs near the poly(A) site. 5' half-molecules generated in the presence of EDTA (which blocks polyadenylation, but not cleavage) ended at the adenosine at position +1 of the precursor. When incubated in the extract under suitable conditions, they became polyadenylated. 5' half-molecules formed in 3'-dATP-containing reactions contained a single 3'-deoxyadenosine (cordycepin) residue added onto the +1 adenosine and were poor polyadenylation substrates. We infer that the +1 adenosine of the precursor becomes the first A of the poly(A) tract and provides a 3' hydroxyl group to which poly(A) is added posttranscriptionally.

Alkaline Phosphatase↗