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Biomedical subjects

D J Hunter

Publications and source records attributed to D J Hunter.

At least 271 records · Page 15Linked to original sources
PubMed1992

A quantitative assessment of oral contraceptive use and risk of ovarian cancer.

OBJECTIVE: To provide a quantitative assessment of the association between oral contraceptive (OC) use and ovarian cancer using results from the published literature. DATA SOURCES: We conducted a MEDLINE literature search for all epidemiologic studies of OC and ovarian cancer published in English between 1970-1991. The reference list for each article was reviewed to locate additional published articles. METHODS OF STUDY SELECTION: We included 20 studies in which a relative risk and either a standard error, confidence interval, or P value was reported, or sufficient data were presented to allow us to calculate these measures. DATA EXTRACTION AND SYNTHESIS: We summarized the findings using weighted averages and regression analyses. We found a summary relative risk of 0.64 (95% confidence interval 0.57-0.73) associated with ever-use of OC, indicating a 36% reduction in ovarian cancer risk. The risk of ovarian cancer decreased with increasing duration of OC use; we noted a 10-12% decrease in risk with 1 year of use and approximately a 50% decrease after 5 years of use. The reduced risk was present among both nulliparous and parous women and it appeared to last for at least 10 years after cessation of use. Although most studies assessed the use of cessation of use. Although most studies assessed the use of OC formulations from the 1960s and 1970s, data from the Cancer and Steroid Hormone Study indicate that the decreased ovarian cancer risk may also be present with current lower-dose formulations. CONCLUSION: The protective effect of OC against ovarian cancer risk should be considered in a woman's decision to use OC.

Contraceptives, Oral↗
PubMed1991

An extensive experience with postoperative pain relief using postoperative fentanyl infusion.

From October 1, 1987 through December 31, 1989, 517 patients who were undergoing both thoracic and abdominal surgical procedures were treated for postoperative pain with epidural fentanyl citrate infusion under the direction of an anesthesia pain service. Infusion rates of 4 micrograms/mL of solution were essentially the same for all subjects. Sixty-five percent of patients experienced superior pain control without the use of adjunctive analgesia. Twenty-eight percent of subjects achieved satisfactory pain control but required additional low-dose analgesics. Only 7% of patients remained uncomfortable despite additional intravenous narcotic administration. There were no deaths or respiratory arrests. Six percent of patients experienced nausea, and 0.8% of the cohort required catheterization for urinary retention. This technique of postoperative pain control was safe and provided excellent results. Catheter position was a major determinant of the efficacy of the method.

Abdomen↗
PubMed1991

Managing medicine: a response to the 'crisis'.

A feature of many developed healthcare systems is the attempt to replace provider-driven services by managerially-driven services which are ostensibly more responsive to consumer preferences. Policy-makers anxious over the 'crisis' of escalating costs in healthcare delivery and over the efficiency of some medical treatments and interventions are turning to managerial solutions as a means of holding professionals--primarily the medical profession--to account for their actions. The paper uses developments in the British NHS as a case study to review and explore the issue of managing medicine. Recent and proposed reforms are designed to strengthen the managerial grip on the service. The paper casts some doubt over the likely outcome of these developments. It argues that the success of attempts to shift the frontier between management and clinical work in favour of management is by no means guaranteed. It also points to a major tension which remains to be resolved, namely, the optimum balance to be struck between a doctor's responsibility to each individual patient on the one hand and his/her responsibility to a whole population on the other.

Delivery of Health Care↗
PubMed1991

Knowledge of AIDS among secondary school pupils in Bagamoyo and Dar-Es-Salaam, Tanzania.

We assessed knowledge of AIDS among pupils in selected schools in Tanzania in August 1989. Four hundred and eight-one pupils from four randomly selected secondary schools, two from Dar-Es-Salaam (a city) and two from Bagamoyo (a semi-rural town), were interviewed using a structured questionnaire. Of these, 476 (99.0%) had heard of AIDS, and 447 (92.9%) were able to mention spontaneously at least one sexually transmitted disease (STD), of whom 374 (83.7%) mentioned AIDS. Knowledge was found to increase with age and tended to be higher among women in Dar-Es-Salaam than in Bagamoyo. These data suggest that communication channels directed at women in rural areas should be strengthened. While knowledge of sexual transmission of HIV was generally high, and prevalence of reported misconceptions about modes of transmission was very low, knowledge of non-sexual means of transmission (transfusions, injections, vertical) was lacking. Although 80% of pupils mentioned reduction of number of sexual partners as a means of AIDS prevention, only 22% mentioned condom use, and less than 5% reported that they had ever used a condom. Future research should concentrate on means of promoting sexual behavior change, the ultimate aim of any AIDS prevention strategy.

Acquired Immunodeficiency Syndrome↗
PubMed1990

The cellular location and specificity of bacterial cytochrome c peroxidases.

The locations of cytochrome c peroxidase and catalase activities in the two Gram-negative bacteria Pseudomonas stutzeri (N.C.I.B. 9721) and Paracoccus denitrificans (N.C.I.B. 8944) were investigated by the production of spheroplasts. In both species the cytochrome c peroxidase was predominantly periplasmic: 92% of total activity in Ps. stutzeri and 98% of nonmembrane-bound activity in Pa. denitrificans were found in this cellular compartment. In contrast, the catalase was mostly in the cytoplasmic fraction. Purification of the Pa. denitrificans cytochrome c peroxidase showed it to be the haem c-containing polypeptide of Mr 42,000 that has already been described by Bosma, Braster, Stouthamer & Van Versefeld [(1987) Eur. J. Biochem. 165, 665-670] but was not identified by them as a peroxidase. The visible-absorption spectra of the enzyme closely resemble those of cytochrome c peroxidase from Pseudomonas aeruginosa but the donor specificity is different, with the Pa. denitrificans enzyme preferring the basic mitochondrial cytochromes c to the acidic cytochromes c-551 and reacting well with the Pa. denitrificans cytochrome c-550.

Bacterial Proteins↗
PubMed1990

A prospective study of selenium status and breast cancer risk.

Low dietary intake of selenium has been proposed as a risk factor for breast cancer. To address this hypothesis, we collected toenail clippings from 62,641 women in the Nurses' Health Study cohort who were free from cancer (other than nonmelanoma skin cancer) in 1982 and 1983. The selenium concentration in nails has been shown to reflect dietary intake of selenium. During 53 months of follow-up, 434 cases of breast cancer were diagnosed among women who had submitted a set of toenail clippings, and we matched one control free from breast and other cancers to each case. The mean selenium level in toenails in the cases (0.823 microgram/g; SD, 0.197) was almost identical to that of the controls (0.821 microgram/g; SD, 0.174). After controlling for known breast cancer risk factors, the relative risk for women in the highest quintile of selenium as compared with the lowest quintile was 1.10 (95% confidence interval, 0.70 to 1.72) and there was no trend across quintiles. Results were similar for both premenopausal and postmenopausal women. Although these data do not exclude a possible influence of selenium intake before adulthood on subsequent risk of breast cancer, selenium intake later in life is not likely to be an important factor in the etiology of breast cancer.

Adult↗
PubMed1990

Risk factors for basal cell carcinoma in a prospective cohort of women.

In a prospective study of self-reported demographic, constitutional, and life-style factors in relation to basal cell carcinoma of the skin, we followed a cohort of 73,366 nurses in the United States who were 34 to 59 years of age in 1980 and who had no previous skin or other cancer. In 4 years of follow-up, compared with women living in the Northeast, women residing in California (age-adjusted relative risk [RR] = 1.57; 95% confidence interval [CI] = 1.30 to 1.89) and Florida (RR = 2.12; 95% CI = 1.54 to 2.92) were more likely to develop basal cell carcinoma. Compared with women having naturally dark brown hair, the age-adjusted relative risk of basal cell carcinoma was increased among women with red (RR = 2.45; 95% CI = 1.89 to 3.19), blonde (RR = 1.37; 95% CI = 1.09 to 1.71), or light brown hair (RR = 1.27; 95% CI = 1.08 to 1.49) and was decreased among women with black hair (RR = 0.66; 95% CI = 0.41 to 1.06). Risk was positively associated in a dose-response manner both with tendency to sunburn as a child or adolescent and with lifetime number of severe and painful sunburns on the face or arms. These risk factors remained significant predictors of disease when included simultaneously in multivariate analyses. Tendency to tan was associated with decreased risk, although this risk was not significant after controlling for the other constitutional determinants and region. Cigarette smoking did not alter the risk of basal cell carcinoma. These prospective data emphasize the importance of sunlight, and skin response to sunlight, as determinants of basal cell carcinoma among women.

Adult↗
PubMed1990

No hiding place: on the discomforts of researching the contemporary policy process.

It has never been easy to conduct research into currently sensitive policy issues, but there is now accumulating evidence to indicate that various forms of resistance to scholarly investigation are on the increase. Such a climate handicaps all social policy research, but may have the greatest impact on ethnographic projects. Yet, it is argued, ethnography is increasingly widely recognised among academics as having a particularly valuable contribution to make to the study of the policy process. Unfortunately, many policy practitioners (and occasionally some academic colleagues) perceive ethnographic research as being of questionable validity and low helpfulness. This behaves policy-oriented ethnographers to demonstrate that they do indeed have procedures for assuring validity, even if their style of investigation is never likely to be popular with government.

Ethnology↗
PubMed1990

Predictors of selenium concentration in human toenails.

To assess the validity of the selenium concentration in human toenails as a measure of selenium intake and to determine other correlates of toenail selenium level, the authors examined the predictors of toenail selenium within two subgroups of a large cohort study of US women. Mean toenail selenium was higher among 38 consumers of selenium supplements (0.904 micrograms/g, standard deviation (SD) 0.217) than among 96 nonusers (0.748 micrograms/g, SD 0.149; p less than 0.001), and a dose-response relation was observed among supplement users (Spearman's r = 0.32; p = 0.05). In a second subgroup of 677 women, selenium supplement use was also associated with higher mean toenail selenium (0.906 micrograms/g, SD 0.214, among 18 users and 0.801 micrograms/g, SD 0.148, among 659 nonusers; p = 0.02), and the dose-response relation was also significant (Spearman's r = 0.50; p = 0.03). The geographic variation in toenail selenium levels was consistent with the geographic distribution of selenium in forage crops. Toenail selenium declined with age and was significantly reduced among cigarette smokers (mean = 0.746, SD 0.124, among 146 current smokers and mean = 0.817, SD 0.159, among 311 never smokers; p less than 0.001) but was not materially affected by alcohol consumption. A dietary selenium score calculated from a food frequency questionnaire failed to predict toenail selenium level, demonstrating the suspected inability of diet questionnaires to measure individual selenium intake because of the highly variable selenium composition of different samples of the same food.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The role of cytochrome c4 in bacterial respiration. Cellular location and selective removal from membranes.

The cellular location of cytochrome c4 in Pseudomonas stutzeri and Azotobacter vinelandii was investigated by the production of spheroplasts. Soluble cytochrome c4 was found to be located in the periplasm in both organisms. The remaining cytochrome c4 was membrane-bound. The orientation of this membrane-bound cytochrome c4 fraction was investigated by proteolysis of the cytochrome on intact spheroplasts. In P. stutzeri, 78% of the membrane-bound cytochrome c4 could be proteolysed, whilst 82% of the spheroplasts remained intact, suggesting that the membrane-bound cytochrome c4 is on the periplasmic face of the membrane in this organism. Cytochrome c4 was not susceptible to proteolysis on A. vinelandii spheroplasts, in spite of being digestible in the purified state. Cytochrome c5 was shown to have a similar cellular distribution to cytochrome c4. Selective removal of cytochrome c4 from membranes of P. stutzeri was accomplished by the use of sodium iodide and propan-2-ol, with the retention of most of the ascorbate-TMPD (NNN'N'-tetramethylbenzene-1,4-diamine) oxidase activity associated with the membrane. Sodium iodide removed most of the cytochrome c4 from A. vinelandii membranes with retention of 62% of the ascorbate-TMPD oxidase activity. Cytochrome c4 could be returned to the washed membranes, but with no recovery of this enzyme activity. We conclude that cytochrome c4 is not involved in the ascorbate-TMPD oxidase activity associated with the membranes of these two organisms.

Azotobacter↗
PubMed1989

Food-based validation of a dietary questionnaire: the effects of week-to-week variation in food consumption.

The reproducibility and validity of responses for 55 specific foods and beverages on a self-administered food frequency questionnaire were evaluated. One hundred and seventy three women from the Nurses' Health Study completed the questionnaire twice approximately 12 months apart and also recorded their food consumption for seven consecutive days, four times during the one-year interval. For the 55 foods, the mean of correlation coefficients between frequencies of intake for first versus second questionnaire was 0.57 (range = 0.24 for fruit punch to 0.93 for beer). The mean of correlation coefficients between the dietary records and first questionnaire was 0.44 (range = 0.09 for yellow squash to 0.83 for beer and tea) and between the dietary records and the second questionnaire was 0.52 (range = 0.08 for spinach to 0.90 for tea). Ratios of within- to between-person variance for the 55 foods were computed using the mean four one-week dietary records for each person as replicate measurements. For most foods this ratio was greater than 1.0 (geometric mean of ratios = 1.88), ranging from 0.25 (skimmed milk) to 14.76 (spinach). Correlation coefficients comparing questionnaire and dietary record for the 55 foods were corrected for the within-person variation (mean corrected value = 0.55 for dietary record versus first questionnaire and 0.66 versus the second). Mean daily amounts of each food calculated by the questionnaire and by the dietary record were also compared; the observed differences suggested that responses to the questionnaire tended to over-represent socially desirable foods. This analysis documents the validity and reproducibility of the questionnaire for measuring specific foods and beverages, as well as the large within-person variation for food intake measured by dietary records. Differences in the degree of validity for specific foods revealed in this type of analysis can be useful in improving questionnaire design and in interpreting findings from epidemiological studies that use the instrument.

Adult↗