Biomedical subjects
Publications and source records attributed to A Calder.
Perturbation imprinting at a flat interface by a rippled shock has been observed in a laser hydrodynamics experiment. A strong shock was driven through a three-layer target, with the first interface rippled, and the second flat. The chosen thickness of the second layer gave instability growth with opposite phases at the two interfaces, consistent with two-dimensional simulations and rippled shock theory.
OBJECTIVE: To describe the work of the Scottish Programme for Clinical Effectiveness in Reproductive Health (SPCERH) in order to draw lessons applicable to other clinical effectiveness programmes. DESIGN: Overview of an integrated clinical effectiveness programme relating to reproductive health. SETTING: Scotland. SUBJECTS: The programme is designed to reach all professionals who share responsibility for reproductive healthcare--including obstetrician/gynaecologists, midwives, general practitioners, family planning doctors, commissioners of services and NHS managers. RESULTS: During its first three-year Workplan, SPCERH has conducted an integrated programme of audit, guideline and educational activities. Findings have been disseminated using multi-faceted approaches including publications, presentations and interactive meetings. Evidence from surveys undertaken within the Programme indicates that clinicians have changed or reconsidered their practice in several key areas in response to audit and guideline recommendations made by the Programme. CONCLUSIONS: As a way of funding and organising clinical effectiveness activities, the integrated Programme has many advantages over the stand-alone Project. These advantages include: enabling the linkage of national audits to national guidelines and other forms of NHS guidance; enabling the re-audit of topics after a time interval sufficient to allow for the implementation of change; the building of expertise within a dedicated team and the use of that expertise across a range of linked projects; the availability of an experienced team which can respond to new priority issues at short notice.
OBJECTIVE: The purpose of the study was to examine the effects of tibolone, a synthetic steroid that alleviates climacteric symptoms and prevents bone loss without inducing monthly bleeds, on lipoprotein cardiovascular risk markers and to compare the effects with those of a standard combined estrogen/progestogen preparation. DESIGN: Ninety-seven postmenopausal women were randomly allocated to receive either tibolone 2.5 mg/day or conjugated equine estrogens 0.625 mg/day with norgestrel 0.15 mg/day for 12 of each 28 days. Fasting serum levels of lipids, lipoproteins, and apolipoproteins (Apo) were monitored during 18 months of treatment. Women on the cyclical preparation had levels determined during both estrogen-only and combined phases. RESULTS: Tibolone caused reductions in triglycerides (33%, p < 0.001), very low density lipoprotein (VLDL) cholesterol (43%, p < 0.001), and high density lipoprotein (HDL) cholesterol (18%, p < 0.001). The HDL2/HDL3 ratio fell by 22% (p < 0.001). Levels of Apo AI and AII were reduced by 18 and 8%, respectively (p < 0.001). The combined preparation caused reductions in VLDL cholesterol (23%, p < 0.001) and low density lipoprotein cholesterol (15%, p < 0.001). There were small reductions in HDL3 cholesterol and in Apo AII and Apo B. All parameters, except for Apo AII and Apo B and lipoprotein (a) [Lp (a)], showed cyclical changes. Lp (a) levels were reduced significantly by both treatments. CONCLUSIONS: The cyclical preparation had potentially beneficial effects on LP risk markers. The reduction in HDL induced by tibolone constitutes a potentially adverse change, which may be offset by the substantial falls in triglycerides, VLDL cholesterol, and Lp (a).
OBJECTIVE: To investigate the effect of amniotic fluid on prostaglandin synthesis and metabolism in the fetal membranes. DESIGN: A cell culture study of amnion and chorion obtained at elective cesarean section incubated with amniotic fluid collected following either spontaneous labor and delivery, or elective cesarean section. SUBJECTS: Forty-eight pregnant women at 3742 weeks gestation: 24 in spontaneous labor and 24 delivered by elective cesarean section. RESULTS: Significantly more PGE2 and PGF2alpha were produced by amnion and chorion treated with amniotic fluid from spontaneous labor compared with elective cesarean section. Spontaneous labor amniotic fluid favors PGE2 and PGFM production by amnion and chorion respectively; while elective section fluid stimulates PGE2 synthesis by both tissues (reflected as PGEM in chorion). Amniotic fluid, from either spontaneous labor or elective section, had no effect on the metabolism of exogenous PGE2 or PGF2alpha by chorion cells. CONCLUSION: Spontaneous labor is associated with the presence of a substance in amniotic fluid which facilitates prostaglandin synthesis in the fetal membranes, but which is without effect on prostaglandin metabolism.
Forty post-menopause women using a preparation of 2 mg 17 beta-oestradiol and 1 mg norethisterone acetate (Kliofem) for a mean duration of 2.9 years were investigated in an open, prospective, method comparison study. Main outcome measures were the histology of endometrial biopsy in comparison with clinical evaluation of the endometrium during panoramic hysteroscopy and endometrial thickness measured by transvaginal ultrasound. Thirty-six women had either an inactive atrophic or unassessable endometrial biopsy, the remaining four (10%) showed benign endometrial changes. In the majority of patients the endometrium had a thin and regular appearance on hysteroscopy (92.5% of cases) with an endometrial thickness not exceeding 7 mm (90% of cases). Non-agreement between histology and hysteroscopy or transvaginal ultrasound findings was associated with the presence of polyps and submucosal fibroids, or innocuous endometrial changes such as a pseudodecidual pattern. No case of malignancy was encountered in any patient in this study. The present study suggests that continuous combined hormone replacement therapy appears to be safe with regard to endometrial health. In the majority of women an inactive endometrium or non-assessable biopsy result will be encountered. However, the numbers examined here are small and endometrial carcinoma has been reported to occur. Continuing follow-up of patients on continuous combined HRT is therefore essential.
The purpose of this study was to examine the effects on lipoprotein risk markers for CHD of oestradiol given alone and in combination with the androgenic progestogen, norethisterone. Eighty postmenopausal women were randomly allocated to receive oestradiol (2 mg/day) alone or with continuous norethisterone (1 mg/day). Serum lipoprotein levels, including lipoprotein(a), were monitored during 12 months on treatment in all the women, and in a sub-set of 32 patients cholesterol was measured in the two major density subfractions of LDL. Oestradiol caused a transient rise in triglycerides, a small decrease in LDL cholesterol (significant only at 3 and 6 months, P < 0.05) and a consistent significant increase in HDL cholesterol (16%, P < 0.01). There was a downward trend in lipoprotein(a) levels which did not achieve statistical significance. The combined preparation caused significant, sustained decreases in triglycerides (31%, P < 0.01), total cholesterol (15%, P < 0.001), VLDL (42%, P < 0.01), LDL (9%, P < 0.05) and HDL (11%, P < 0.001). Lipoprotein(a) was also reduced (39%, P < 0.05). In the sub-set of patients in which LDL subfractions were measured, the reduction in LDL induced by oestradiol monotherapy was significant only at the 3-month visit (6%, P < 0.05). This was due to a decrease in the 'light' (1.025 < d < 1.044 g/ml) subfraction (10%, P < 0.05) and resulted in an apparent shift in subfraction distribution towards the 'heavy' (1.044 < d < 1.060 g/ml) subfraction, although there was no absolute increase in the latter. None of these changes was statistically significant at 12 months. Oestradiol/norethisterone caused sustained decreases in both 'light' (15%, P < 0.05) and 'heavy' (29%, P < 0.05) subfractions, with no significant change in the relative amounts. The changes in 'light' and 'heavy' LDL in this group were highly correlated with changes in triglyceride levels (r = -0.57, P < 0.05 and r = 0.82, P < 0.01 respectively). Therefore, at the end of 1 year's treatment with unopposed oestradiol the only statistically significant change was an increase in HDL cholesterol. Addition of norethisterone to the preparation reversed this potentially beneficial change, but favourably influenced triglycerides, VLDL, LDL subfraction profile and lipoprotein(a), which may counteract the adverse effect on HDL.
Twenty young women (20.3 +/- 1.0 years) participated in a weight training program in which upper and lower body exercises were done twice per week for 20 weeks. Ten other women (20.2 +/- 0.4 years) served as a control group. Training resulted in significant (p < 0.05) increases in arm curl (73%), bench press (33%), and leg press (23%) lifting performance. Whole body (3.7%), trunk (3.0%), arm (9.7%), and leg (3.3%) lean tissue mass also increased significantly, based on measurements made by dual energy x-ray absorptiometry (DEXA). Changes in the control group were small and nonsignificant. In contrast, training did not increase DEXA-measured bone mineral content (BMC) and density (BMD) in a whole body measure nor in arm, leg, ribs, thoracic and lumbar spine, and pelvis segments. Similarly, hip BMC and BMD at femoral neck, trochanter, intertrochanter, and Ward's triangle sites, and total hip did not increase with training. The data indicate that a resistance training program that effectively increases strength and lean tissue mass in young women may fail to increase BMC or BMD over a 20-week training period.
Burton and Bruce's (1992) model of face naming predicts a "fan effect", in which naming of famous people about whom many descriptive properties are known should be slower than naming of celebrities about whom few properties are known. An experiment is reported that showed that, contrary to this prediction, knowledge of many descriptive properties facilitated face-naming latency. An alternative architecture for an interactive activation model is proposed in which descriptive properties are represented in separate pools of units for each domain of information and in which names are represented by a separate pool of lexical output units. Computer simulations showed that this model could simulate the previously available empirical data as effectively as Burton and Bruce's (1992) original model. However, the proposed model could also simulate the effect of the number of known descriptive properties upon face-naming latency observed in the experiment reported. The new architecture also has the advantage of being more compatible with current models of speech production, and it allows preserved access to unique semantic properties in the context of impaired face naming as reported in the neuropsychological literature.
The purpose of this investigation was to determine the short-term reproducibility of measurements of whole-body and subregion bone mass and density, as well as body composition, made by dual energy x-ray absorptiometry. Bone mineral content, bone mineral density and body composition were measured on two occasions, 1 to 2 weeks apart, in 21 women (average age, 20.9 [standard deviation 1.6] years). The method errors of the duplicate measurements, expressed as a percentage of the combined mean values from the two sets of measurements (i.e., as a coefficient of variation), for whole-body bone mineral content, bone mineral density, lean tissue mass and fat mass were 1.6%, 1.1%, 1.4% and 1.8% respectively. The method errors for bone mineral density in the hip were 2.2%, 1.1% and 2.5% for the neck, trochanter and Ward's triangle respectively. On the basis of the method errors and the expected treatment effects, the sample sizes needed for intervention trials (e.g., exercise training) were calculated. All of the whole-body and most of the subregion bone mineral density and lean tissue mass measurements made by dual-energy x-ray absorptiometry were sufficient for detecting the small changes (about 2%) expected in trials with 20 subjects, whereas measurements of subregion bone mineral content and fat mass were less precise.
The relationship between maternal peripheral plasma concentrations of prostaglandin E2 and prostaglandin F2 alpha metabolites (bicyclo-PGEM and PGFM respectively) and the level of uterine activity in spontaneous labour was studied in 10 nulliparous and 10 multiparous women. Plasma prostaglandin metabolites were measured by radioimmunoassay. Uterine activity was quantified by computer analysis of changes in intrauterine pressure and expressed as mean active pressure (MAP). As labour progressed, both parity groups showed a significant rise in MAP which was associated with a significant increase in the levels of PGFM. However, the percentage rise in PGFM did not significantly correlate with the percentage rise in MAP. At all stages in labour PGFM and MAP levels were higher in the nulliparous group compared with the multiparous group. Bicyclo-PGEM levels showed no significant change in the nulliparous group but rose in late first stage/second stage in the multiparous group. Our observations support a role for prostaglandin F2 alpha in the generation of uterine activity in spontaneous labour. However, further study is required to elucidate the mechanisms controlling prostaglandin production by the fetal membranes and decidua in vivo, and how this relates to maternal peripheral plasma prostaglandin metabolite concentrations and the level of uterine activity.
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A commercially produced domiciliary fetal monitoring (DFM) system was assessed in four centres in the UK (Bristol, Glasgow, London and Nottingham) chosen to allow for comprehensive assessment in various settings in many different women. Overall, 825 recordings were made from 368 women (2.24 per woman). There were 56 unsuccessful attempts at transmission (6.8%), most were due to problems with telephone equipment. The system worked most efficiently when a dedicated direct line was used. The data transmission time varied between 40 and 60 s. The median telephone time (including data transmission and conversation) with a dedicated direct line was 7 min. Mean acceptance times from the four centres were between 70 and 80%. All recordings with acceptance times of 40% or more were interpretable. Ten recordings were abnormal. The women and mid-wives were equally proficient at using the DFM system. The DFM system represents an important addition to current methods of fetal assessment. Specific guidelines are outlined.
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