Search PubMed⌕ Search

Biomedical subjects

S R Davis

Publications and source records attributed to S R Davis.

At least 37 records · Page 2Linked to original sources
PubMed2002

Preliminary indication of a high prevalence of polycystic ovary syndrome in indigenous Australian women.

We aimed to estimate the likely prevalence of polycystic ovary syndrome (PCOS) in indigenous Australian women in a cross-sectional survey based on structured interviews. In the Kimberley region of Western Australia and south-western Victoria, between February and June 1999, women over the age of 18 available for interview and willing to participate were included. Menstrual status, anthropometric measures, fasting blood biochemistry and hirsutism were assessed. A total of 38 premenopausal women completed the survey. Of these, 50% had regular menstrual cycles of normal duration and no hirsutism; seven had oligomenorrhea and hirsutism/hyperandrogenemia; and of the nine women with hirsutism and regular menses, three had hyperandrogenemia. Thus, possibly ten women fulfilled the criteria of PCOS. This unique data set suggests a high prevalence of PCOS in indigenous Australian women. Further research to document this formally is warranted, in view of the potential adverse effects of PCOS on reproduction and metabolism.

Adult↗
PubMed2002

Differing effects of low-dose estrogen-progestin therapy and pravastatin in postmenopausal hypercholesterolemic women.

BACKGROUND: Most studies examining the potential cardioprotective effects of postmenopausal estrogen have been undertaken in healthy women, with doses that may not be appropriate for long-term intervention. New low-dose estrogen-progestin regimens alleviate postmenopausal symptoms with a favorable side-effect profile; however, little is known of the impact of such regimens in women at increased risk of cardiovascular disease. Hence, we have evaluated the effects of low-dose oral estrogen-progestin therapy on serum lipoprotein lipids, brachial artery reactivity and fibrinogen in hypercholesterolemic postmenopausal women in direct comparison with the effects of pravastatin, a lipid-lowering agent known to reduce cardiovascular events in women. METHODS: In a randomized, double-blind, double-dummy, parallel trial, we studied the effects of continuous combined estrogen-progestin therapy (1 mg 17beta-estradiol with 500 micro g norethisterone acetate daily) or pravastatin (20 mg daily) in 72 postmenopausal women with fasting serum low-density lipoprotein (LDL) cholesterol levels greater than 124 mg/dl after an 8-week run-in diet, over a 24-week period. The primary end-point was percentage change in LDL cholesterol from baseline. RESULTS: The intention-to-treat population comprised 65 women, mean age 59 +/- 6.3 years, and 29 in each group completed the trial. Diet alone reduced LDL cholesterol significantly in both treatment groups, in association with a reduction in weight during this period. Compared with respective baseline values, pravastatin decreased LDL cholesterol and total cholesterol to a greater extent than hormone therapy (p = 0.0001 and 0.003 for difference between treatments, respectively). High-density lipoprotein (HDL) cholesterol levels decreased with hormone therapy, but did not change with pravastatin (p = 0.01). Lipoprotein(a) decreased significantly with hormone therapy only (-14%, 95% confidence interval (CI) -21 to -6%, p = 0.01 for difference between groups). Brachial artery flow-mediated dilatation (FMD) was impaired at baseline, and this increased with hormone therapy (absolute mean change in artery diameter as percentage units 2.07, 95% CI 0.57-3.57, p = 0.009) versus no change with pravastatin (0.19, 95% CI -1.1 to 1.5, p = 0.78), with a near-significant difference between the two groups (p = 0.058). A significant correlation between improved brachial artery FMD and reduction in LDL cholesterol was not observed. Fibrinogen decreased significantly in both treatment groups with no difference between treatments. CONCLUSIONS: In postmenopausal hypercholesterolemic women, pravastatin and hormone therapy exhibited divergent effects. The former lowered total and LDL cholesterol more effectively, whereas hormone therapy lowered lipoprotein(a) significantly and improved brachial artery endothelium-dependent dilatation, independent of the reduction in LDL cholesterol. The modest increase in brachial artery FMD seen is consistent with hypercholesterolemia compromising endothelial integrity, and suggests that the important effect of estrogen on the endothelial microenvironment may be attenuated in women with endothelial dysfunction.

Aged↗
PubMed2001

Women's health issues in haemodialysis patients.

OBJECTIVES: To describe reproductive health issues in women with end-stage renal disease (ESRD) treated with haemodialysis. STUDY DESIGN: Cross-sectional survey based on structured interviews. SETTING: Nephrology units of two major metropolitan tertiary referral hospitals in Victoria and their satellite dialysis centres between 1 November 1998 to 30 June 1999. METHODS: Women aged 20 years or over in haemodialysis programs. OUTCOME MEASURES: Menstrual status; prevalence of menstrual and climacteric symptoms; use of gynaecological screening; and prevalence of comorbidities that may benefit from hormone replacment therapy. RESULTS: 48 women completed the survey. They were similar to the 485 women undergoing haemodialysis in Victoria in age (mean age, 55.5 years; range, 20-84 years), years on dialysis (mean age, 3.9 years; range, 1 month-17 years) and primary diagnosis. Eleven of the 15 premenopausal women reported menstrual cycles of 22-35 days, 13 reported common premenstrual symptoms, and six reported dysmenorrhoea that interfered with daily activities. Average age at menopause was 47.7 years (95% CI, 45.6-49.9 years), and six of the 31 postmenopausal women underwent menopause before 45 years. Eight had ever been prescribed hormone replacement therapy (oral in all cases). Over half the women (26) had not had a Pap smear in the last two years, and 12 of those aged over 50 (38%) had not had a mammogram in the same period. CONCLUSION: Despite their risk of early menopause, cardiovascular disease and bone fracture, few women undergoing haemodialysis were offered hormone replacement therapy. Nor were they adequately screened for gynaecological cancers. Women's health issues seem to be neglected among haemodialysis patients.

Adult↗
PubMed2001

The effects of Chinese medicinal herbs on postmenopausal vasomotor symptoms of Australian women. A randomised controlled trial.

OBJECTIVE: To evaluate the effects of a defined formula of Chinese medicinal herbs (CMH) on menopausal symptoms. DESIGN: A double-blind randomised placebo-controlled trial. METHODS: Between August 1998 and April 1999, 55 postmenopausal Australian women recruited from an urban population completed 12 weeks of intervention with either a defined formula of CMH (n = 28) or placebo (n = 27) taken twice daily as a beverage. MAIN OUTCOME MEASURES: The primary end-point was change in frequency of vasomotor events (hot flushes and night sweats). The secondary end-points were changes in score for the domains measured in the Menopause Specific Quality of Life (MENQOL) Questionnaire. RESULTS: There was a reduction in average weekly frequency of vasomotor events with CMH (-15%; 95% CI, -31% to +1%) and with placebo (-31%; 95% CI, -42% to -21%). The difference between groups favoured the use of placebo; however, this was not significant (P=0.09). Although significant reductions in scores for the various domains of the MENQOL Questionnaire were observed for both CMH and placebo, there were no significant differences between the two treatment groups for any domain. There was evidence for effect modification by previous use of natural therapies for the vasomotor, physical and sexual domains of the MENQOL Questionnaire: women with no prior use of natural therapies for their menopausal symptoms responded to therapy, whereas prior users did not. CONCLUSIONS: The defined formula of CMH was no more effective than placebo in reducing vasomotor episodes in Australian postmenopausal women, or in improving any of the four symptom domains in the MENQOL Questionnaire. Three of the MENQOL Questionnaire domains were modified by prior use of natural therapies. This finding has implications for future studies.

Aged↗
PubMed2001

A double exposed portal image comparison between electronic portal imaging hard copies and port films in radiation therapy treatment setup confirmation to determine its clinical application in a radiotherapy center.

PURPOSE: At the William Buckland Radiotherapy Center (WBRC), field-only electronic portal image (EPI) hard copies are used for radiation treatment field verification for whole brain, breast, chest, spine, and large pelvic fields, as determined by a previous study. A subsequent research project, addressing the quality of double exposed EPI hard copies for sites where field only EPI was not considered adequate to determine field placement, has been undertaken. The double exposed EPI hard copies were compared to conventional double exposed port films for small pelvic, partial brain, and head and neck fields and for a miscellaneous group. METHODS AND MATERIALS: All double exposed EPIs were captured during routine clinical procedures using liquid ion chamber cassettes. EPI hard copies were generated using a Visiplex multi-format camera. In sites where port film remained the preferred verification format, the port films were generated as per department protocol. In addition EPIs were collected specifically for this project. Four radiation oncologists performed the evaluation of EPI and port film images independently with a questionnaire completed at each stage of the evaluation process to assess the following: Adequacy of information in the image to assess field placement. Adequacy of information for determining field placement correction. Clinician's preferred choice of imaging for field placement assessment RESULTS: The results indicate that double exposed EPI hard copies generally do containsufficient information to permit evaluation of field placement and can replace conventionaldouble exposed port films in a significant number of sites. These include the following:pelvis fields < 12 X 12 cm, partial brain fields, and a miscellaneous group. However forradical head and neck fields, the preferred verification image format remained port film dueto the image hard copy size and improved contrast for this media. Thus in this departmenthard copy EPI is the preferred modality of field verification for all sites except radical headand neck treatments. This should result in an increase in efficiency of workloadmanagement and patient care.

Head and Neck Neoplasms↗
PubMed2001

Metallothionein expression protects against carbon tetrachloride-induced hepatotoxicity, but overexpression and dietary zinc supplementation provide no further protection in metallothionein transgenic and knockout mice.

Metallothionein and zinc have been implicated in cellular defense against a number of cytotoxic agents. With respect to the free radical-generating hepatotoxin carbon tetrachloride, conclusions about a defensive role were reached from in vitro studies, in vivo studies using inducers of metallothionein and studies using injections of pharmacological amounts of zinc. Metallothionein knockout (null) and metallothionein transgenic mice are more direct models to examine the effects of metallothionein expression on induced cytotoxicity. Similarly, zinc presented via the diet is a more physiological model than that presented via injection. We examined whether metallothionein-overexpressing mice or metallothionein knockout mice had altered sensitivity to carbon tetrachloride and whether supplemental dietary zinc reduced sensitivity to carbon tetrachloride in these genotypes. Metallothionein knockout mice produced no metallothionein and were unable to sequester additional hepatic zinc in response to elevated dietary zinc. Hepatotoxicity, as measured by serum alanine aminotransferase activity, histological analyses and hepatic thiol levels, was greater in the knockout mice than in controls 12 h after carbon tetrachloride treatment but not at later time points (up to 48 h). In contrast, metallothionein-overexpressing mice produced more metallothionein and sequestered more liver zinc than control mice, but hepatotoxicity was similar between genotypes. Supplemental dietary zinc had no effect on hepatotoxicity with either genotype. These data suggest metallothionein null mice were more susceptible to carbon tetrachloride-induced hepatotoxicity than were control mice. However, neither metallothionein overexpression nor supplemental dietary zinc provided further protection.

Alanine Transaminase↗
PubMed2001

Users of oestrogen replacement therapy have more knee cartilage than non-users.

BACKGROUND: Osteoarthritis (OA) is increasingly prevalent in the years after menopause. Epidemiological data suggest that the use of oestrogen replacement therapy (ERT) may protect against knee OA. AIM: To test the hypothesis that long term ERT (longer than five years) is associated with increased knee cartilage in postmenopausal women. METHODS: The study involved 81 women (42 current users (> or = five years) of ERT and 39 who had never used it). Articular cartilage volumes were determined by processing images acquired in the sagittal plane using a T1 weighted fat suppressed magnetic resonance sequence on an independent work station. RESULTS: After bone size had been accounted for, ERT users had higher tibial cartilage volume than non-users. Total tibial cartilage volume was 7.7% (0.23 ml) greater in the group of ERT users (2.98 (0.47) ml; mean (SD)) than in the untreated group (2.75 (0.50) ml). The difference, after adjustment for the significant explanatory factors (years since menopause, body mass index, age at menopause, and smoking), between the ERT users and non-users increased from 0.23 ml to 0.30 ml (95% confidence interval 0.08 to 0.52, p=0.008). These differences persisted after exclusion of women with OA. CONCLUSIONS: After adjustment for multiple confounders, women using long term ERT have more knee cartilage than controls. This may indicate that ERT prevents loss of knee articular cartilage.

Aged↗
PubMed2001

Minireview: aromatase and the regulation of estrogen biosynthesis--some new perspectives.

There is a growing awareness that androgens and estrogens have general metabolic roles that are not directly involved in reproductive processes. These include actions on vascular function, lipid and carbohydrate metabolism, as well as bone mineralization and epiphyseal closure, in both sexes. In postmenopausal women, as in men, estrogen is no longer solely an endocrine factor, but instead is produced in a number of extragonadal sites and acts locally at these sites in a paracrine and intracrine fashion. These sites include breast, bone, vasculature, and brain. Within these sites, aromatase action can generate high levels of E2 locally without significantly affecting circulating levels. Circulating C(19) steroid precursors are essential substrates for extragonadal estrogen synthesis. The levels of these androgenic precursors decline markedly with advancing age in women, possibly from the mid to late reproductive years. This may be a fundamental reason why women are at increased risk for bone mineral loss and fracture and possibly decline of cognitive function, compared with men. Aromatase expression in these various sites is under the control of tissue-specific promoters regulated by different cohorts of transcription factors. Thus, in principle, it should be possible to develop selective aromatase modulators that block aromatase expression, for example, in breast, but allow unimpaired estrogen synthesis in other tissues such as bone.

Aging↗
PubMed2001

Evidence that parenteral testosterone therapy may improve endothelium-dependent and -independent vasodilation in postmenopausal women already receiving estrogen.

The gender difference in cardiovascular disease has been partly attributed to higher androgenic hormone levels. Although testosterone in women may not affect lipids, it remains unknown whether it negates favorable estrogenic effects on endothelial function. We have investigated the effects of testosterone implant therapy on arterial reactivity encompassing endothelial-dependent and -independent vasodilation in women using hormone replacement therapy (HRT). B-mode ultrasound measurements of resting brachial artery diameter, following reactive hyperemia [endothelium-dependent flow- mediated dilation (FMD)] and following glyceryl trinitrate (GTN) (endothelium-independent dilation), were recorded in 33 postmenopausal women stabilized on HRT (>6 months), at baseline, and 6 weeks after a testosterone implant (50 mg), with 15 postmenopausal nonusers of HRT serving as controls. In the brachial artery, baseline resting diameter was similar (0.40 +/- 0.01 vs. 0.41 +/- 0.01 cm, P = 0.5). In the treated group, testosterone levels increased (0.99 +/- 0.08 to 4.99 +/- 0.3 nmol/L, P < 0.001), associated with a mean 42% increase in FMD (6.4% +/- 0.7 to 9.1% +/- 1.1, P = 0.03). The control group did not change (8.1% +/- 1.4 to 5.6% +/- 1.0, P = 0.4). ANOVA of repeated measures (P = 0.04) and mean change (P = 0.02) in FMD both demonstrated significantly greater improvement with testosterone compared with controls. GTN induced vasodilation increased with testosterone treatment (14.9% +/- 0.9 to 17.8% +/- 1.2, P = 0.03). Our preliminary data indicate that parenteral testosterone therapy improves both endothelial-dependent (flow-mediated) and endothelium-independent (GTN-mediated) brachial artery vasodilation in postmenopausal women using long-term estrogen therapy. The mechanisms underlying these potentially beneficial cardiovascular effects require further investigation.

Brachial Artery↗
PubMed2000

Why do women aged 40 and over need a different diet? What are their specific requirements and are these met?

Many Australian women over 40 years consume insufficient zinc, calcium and fibre. Greater consumption of foods rich in vitamins A, C and E and fibre is associated with a lower risk of breast cancer. Concentrated supplements of A, C and E have no effect on breast cancer risk when dietary intake is adequate, but vitamin A supplementation in women whose dietary intake of vitamin A is inadequate appears to reduce the risk of breast cancer. Alcohol consumption by women has been associated with a linear increase in breast cancer risk.

Adult↗
PubMed2000

What is the role of phytoestrogens in treating menopausal symptoms?

Most randomised placebo-controlled trials show no benefit of phytoestrogens in managing menopausal vasomotor symptoms. Concentrated phytoestrogen supplements appear to have oestrogenic actions in the breast and may interfere with the therapeutic use of tamoxifen. Unlike concentrated supplements, foods rich in phytoestrogens, such as vegetables, grains and legumes, are also excellent sources of fibre, unsaturated protein, vitamins and minerals and their consumption should be encouraged.

Adult↗
PubMed2000

Eligibility audits for the randomized neuropathic bone pain trial (TROG 96.05).

In February 1996 the Trans-Tasman Radiation Oncology Group (TROG) initiated a two-arm, multicentre, prospective randomized trial on radiotherapy for neuropathic pain due to bone metastases (TROG 96.05). This trial compares the response to a single 8-Gy fraction with 20 Gy in five fractions. The accrual target is 270 patients. In order to evaluate compliance with eligibility criteria after approximately 1 year of accrual, an independent audit of the first 42 randomized patients was commissioned. This found that only one of these patients did not have genuine neuropathic pain, but that this patient and seven others (19%) had infringements of other eligibility/exclusion criteria for the trial. Accordingly it was decided to continue the full audit up to 90 patients. This detected no further patients without genuine neuropathic pain, and found only one other eligibility infringement (1/48; 2%). It is concluded that this quality assurance (QA) measure undertaken early in the trial led to significantly improved clinician awareness of, and compliance with, eligibility/exclusion criteria. It also enabled an accurate comparison of outcome data for all randomized versus all eligible patients at the time of the preplanned first interim analysis at 90 patients. In view of the excellent compliance demonstrated in the second audit, a one-in-five sampling is proposed for future audits from centres that have already accrued at least five consecutive eligible patients. This is consistent with TROG QA guidelines now operational.

Bone Neoplasms↗
PubMed2000

Metallothionein expression in animals: a physiological perspective on function.

An integration of knowledge concerning regulation of metallothionein expression with research on metallothionein's proposed functions is necessary to delineate how this metalloprotein affects cellular processes, especially zinc metabolism. Metallothionein expression is driven by a number of physiological mediators through several response elements in the metallothionein gene promoter. Cellular accumulation of metallothionein depends on both gene expression and protein degradation. Both depend largely on availability of cellular zinc derived from the dietary zinc supply. Metallothionein expression is related to zinc accumulation in certain organs. Evidence has been produced, which suggests that metallothionein could act in a number of biochemical processes. It may act in zinc trafficking and/or zinc donation to apoproteins, including zinc finger proteins that act in cellular signaling and transcriptional regulation. As a result, metallothionein expression may affect a number of cellular processes including gene expression, apoptosis, proliferation and differentiation. The ability of metallothionein to exchange other metals with zinc in these proteins may explain a role in metal toxicity. Similarly, mobilization of zinc from metallothionein by oxidative stresses may explain its proposed antioxidant function. Apparent good health of metallothionein-deficient mice argues against a critical biological role for metallothionein; however, expression may be critical in times of stress.

Animals↗
PubMed2000

Effects of mammary engorgement and feed withdrawal on microvascular function in lactating goat mammary glands.

The responses of the mammary microvasculature in lactating goats (n = 8) during feed withdrawal (18-20 h) and mammary engorgement (26-28 h of milk accumulation) were compared using an indicator-dilution technique with FITC-albumin and [(14)C]sucrose as the intravascular and diffusible indicators, respectively. Feed withdrawal and mammary engorgement caused a 50-60% decrease in mammary arterial flow and in the permeability-surface area product (PS) values for sucrose. Only feed withdrawal increased the mean transit time [from 17.3 to 30.0 s, SE of the difference (SED) = 2.16, P < 0.01] of FITC-albumin, whereas only mammary engorgement reduced sucrose extraction (0.63 to 0.51, SED = 0.04, P < 0.05). Mammary engorgement also caused a substantial reduction in the sucrose-accessible extravascular space from 92 to 44 ml (SED = 15.2, P < 0.01). In a separate experiment using five goats, milking after mammary engorgement did not immediately restore arterial flow or sucrose extraction, indicating that the effect of milk accumulation was not mediated simply via increased intramammary pressure. In conclusion, feed withdrawal resulted in slower flow in the capillary bed but apparently no change in capillary recruitment, whereas mammary engorgement caused capillary derecruitment.

Animals↗
PubMed2000

The state of antibiotic resistance surveillance: an overview of existing activities and new strategies.

The growing global problem of antibiotic resistance requires a worldwide surveillance strategy to characterize the magnitude of the problem, guide clinical care decisions, and assess the impact of prevention and control interventions. Because many existing antibiotic resistance surveillance activities have developed independently of one another and vary greatly in their focus, key organizations are promoting strategies to standardize surveillance activities and build collaboration to promote effective global surveillance. With medical facilities operating throughout the world to support a highly mobile beneficiary population, the Department of Defense's Military Health System could benefit from partnership with civilian efforts to achieve global antibiotic resistance surveillance. This article's overview of existing surveillance activities and new strategies provides information requisite to the Department of Defense undertaking of development of a worldwide antibiotic resistance surveillance program to complement and integrate with civilian programs.

Centers for Disease Control and Prevention, U.S.↗