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Biomedical subjects

M G Chapman

Publications and source records attributed to M G Chapman.

At least 19 recordsLinked to original sources
PubMed2001

Testing hypotheses about management to enhance habitat for feeding birds in a freshwater wetland.

The level of water was manipulated in a freshwater wetland, with the aim of enhancing abundances of benthic animals and, ultimately, improving habitat for feeding birds (Japanese Snipe, Gallinago hardwickii). We tested whether these actions had the predicted and desired effects on benthic animals, by contrasting changes in two managed locations to one control location which was left unmanipulated. The number of taxa and abundances of chironomids decreased strongly and significantly in the manipulated locations, while the abundance of oligochaetes appeared to vary in a seasonal manner. Temporal variability of the structure and composition of assemblages was also increased in manipulated locations. Such effects have previously been suggested to indicate stress in benthic assemblages. Therefore, in contrast to what was predicted, managerial actions made benthic fauna less abundant and thus, less suitable as habitat for feeding birds. Several general lessons can be learned from these results. (1) Effects of managerial actions like these are difficult to predict a priori and can only be reliably evaluated with an experimental framework. (2) Because abundances of animals vary naturally, evaluations of managerial actions must include appropriate spatial replication. (3) Sampling at hierarchical temporal scales is important, because abundances of animals may vary in an unpredictable manner at short temporal scales and because changes in temporal variability may be a symptom of stress. (4) Combined use of uni- and multivariate techniques provides a comprehensive set of tools to assess the effects of restoration and creation of new habitats. Finally, these results emphasise the need for clear predictions about desired outcomes and specific experimental plans about how to test whether the desired results were achieved, before managerial actions are taken. Although this is often very difficult to achieve in real situations, it is necessary for practices of management to evolve on the basis of sound empirical experience.

Animals↗
PubMed2001

Status epilepticus.

Status epilepticus is a medical emergency that requires rapid and vigorous treatment to prevent neuronal damage and systemic complications. Failure to diagnose and treat status epilepticus accurately and effectively results in significant morbidity and mortality. Cerebral metabolic decompensation occurs after approximately 30 min of uncontrolled convulsive activity, and the window for treatment is therefore limited. Therapy should proceed simultaneously on four fronts: termination of seizures; prevention of seizure recurrence once status is controlled; management of precipitating causes of status epilepticus; management of the complications. This article reviews current opinions about the classification, aetiology and pathophysiology of adult generalised convulsive status epilepticus and details practical management strategies for treatment of this life-threatening condition.

Adult↗
PubMed2001

Collaboration in maternity care: a randomised controlled trial comparing community-based continuity of care with standard hospital care.

OBJECTIVE: To test whether a new community-based model of continuity of care provided by midwives and obstetricians improved maternal clinical outcomes, in particular a reduced caesarean section rate. DESIGN: Randomised controlled trial. SETTING: A public teaching hospital in metropolitan Sydney, Australia. Sample 1089 women randomised to either the community-based model (n = 550) or standard hospital-based care (n = 539) prior to their first antenatal booking visit at an Australian metropolitan public hospital. MAIN OUTCOME MEASURES: Data were collected on onset and outcomes of labour, antenatal, intrapartum and postnatal complications, antenatal admissions to hospital and neonatal mortality and morbidity. RESULTS: There was a significant difference in the caesarean section rate between the groups, 13.3% (73/550) in the community-based group and 17.8% in the control group (96/539). This difference was maintained after controlling for known contributing factors to caesarean section (OR = 0.6, 95% CI 0.4-0.9, P = 0.02). There were no other significant differences in the events during labour and birth. Eighty babies (14.5%) from the community-based group and 102 (18.9%) from the control group were admitted to the special care nursery, but this difference was not significant (OR 0.75, 95% CI 0.5-1.1, P = 0.12). Eight infants died during the perinatal period (four from each group), for an overall perinatal mortality rate of 7.3 per 1000 births. CONCLUSION: Community-based continuity of maternity care provided by midwives and obstetricians resulted in a significantly reduced caesarean section rate. There were no other differences in clinical outcomes.

Adult↗
PubMed1994

Effect of tibolone on postmenopausal bone loss.

A 2-year non-randomized prospective study was carried out in a teaching hospital menopause clinic to assess the effect on the skeleton of tibolone (Livial, Organon) 2.5 mg daily in recently postmenopausal women. One hundred women who were between 6 and 36 months since their last menstrual period and had raised gonadotrophin levels consistent with the menopause were allocated into two groups. One group received 2.5 mg tibolone daily and the other group no medication. Bone densitometry of the spine and femur was performed at 0, 6, 12 and 24 months and biochemical markers of bone metabolism were assessed at these points. Severity of hypo-oestrogenic symptoms was assessed at baseline and at 1 and 2 years. After 2 years there was a significant increase in bone mass as measured by dual energy X-ray absorptiometry (DXA) of 2.5% in the spine, and 3.5% in the neck of femur in the women who took tibolone (n = 46), whereas in the control group (n = 45) bone loss occurred (spine, 2.9%; femur, 3.7%). When these changes were compared they were significantly different for both sites (p < 0.001). In the treatment group the urinary hydroxyproline/creatinine and calcium/creatinine ratios fell from 0.014 (0.002-0.027) to 0.010 (0.000-0.111) (mol/l) (mmol/l) (p < 0.01) and 0.47 (0.08-0.96) to 0.33 (0.09-1.20) (mmol/l) (mmol/l) (p < 0.001) respectively, while the serum osteocalcin and alkaline phosphatase decreased from 1.90 (0.20-4.70) to 1.00 (0.00-3.00) mmol/l (p < 0.01) and 190 (92-301) to 138 (91-283) mmol/l (p < 0.001) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

A study of the effect of tibolone on the vagina in postmenopausal women.

Tibolone is a synthetic compound with weak oestrogenic, progestagenic and androgenic properties. It does not appear to stimulate the endometrium, and therefore has appeal to the postmenopausal woman as a 'bleedfree' form of hormone replacement therapy (HRT). In the present study the vaginal cytological findings and symptoms were evaluated in 100 recently postmenopausal women, 50 of whom were started on tibolone 2.5 mg daily and 50 of whom received no medication. After 2 years in the tibolone group, cytological assessment showed a significant increase in the karyopyknotic index (P < 0.001) and maturation value (P < 0.01) whereas there was no change in the control group. Significant symptomatic improvement occurred in vaginal dryness (P < 0.001), dyspareunia (P < 0.001), sexual enjoyment (P < 0.001) and libido (P < 0.05). It is therefore concluded that tibolone has a significant oestrogenic effect on the vagina as demonstrated by vaginal cytology. In addition, improvement in the symptoms of vaginal dryness, dyspareunia, sexual enjoyment and libido occurs.

Estrogen Replacement Therapy↗
PubMed1994

Artificial induction of the acrosome reaction in human spermatozoa.

This study investigated the use of human follicular fluid and pentoxifylline as inducers of the human sperm acrosome reaction in vitro. Motile sperm suspensions were prepared using a discontinuous Percoll gradient, preincubated for 3 h, divided into aliquots and exposed to various concentrations of non-heat-inactivated follicular fluid for 1 and 24 h and pentoxifylline for 30 min. Detection of the acrosome reaction involved the combined use of a fluorescent vital stain, H33258, and fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA). A short (1 h) exposure to follicular fluid at concentrations of 50% or more, did not compromise sperm motility and significantly increased the proportion of spermatozoa having completed the acrosome reaction. Similarly, a 30 min exposure to pentoxifylline also significantly increased the proportion of spermatozoa having completed the acrosome reaction.

Acrosome↗
PubMed1994

Pharmacological stimulation of sperm motility.

The treatment of male factor infertility is a rapidly developing field. The introduction of microsurgical fertilization techniques allows assisted conception units to treat couples who previously would not have benefited from in-vitro fertilization techniques. However, these techniques are only used for the minority of subfertile men in andrological practice. Many subfertile men are still treated pharmacologically or by sperm selection methods to enhance sperm fertilizing ability. Numerous pharmacological compounds have been described that enhance sperm motility and thus, potentially, sperm fertilizing capacity. This paper attempts to review these compounds and assess their role in treatment of the subfertile male.

Caffeine↗
PubMed1994

The incidence of vaginal bleeding with tibolone treatment.

OBJECTIVE: To determine the incidence of breakthrough bleeding and its significance in recently postmenopausal women who take tibolone (Livial-Organon). DESIGN: A two year comparative nonrandomised prospective study of women taking tibolone (2.5 mg) and control subjects not on medication. SETTING: Teaching hospital menopause and well women clinic. SUBJECTS: One hundred women who were recently menopausal (between 6 and 36 months since last menstrual period). Fifty were commenced on tibolone and 50 received no medication. MAIN OUTCOME MEASURES: Episodes of bleeding throughout the two year study period were recorded. Oestradiol levels were measured at baseline and at six, 12 and 24 months. The age of menopause and time since last menstrual period (LMP) were noted. RESULTS: Twenty percent (12/59) (95% CI 11.0% to 32.8%) of women in the tibolone group had breakthrough bleeding compared with 9.4% (5/23) (95% CI 3.1% to 20.7%) in the control group. Of the women who bled in the tibolone group, 50% had LMP between six and 12 months prior to entering the study, and 83% were younger than the average age of menopause. Sixty-seven percent had detectable oestradiol levels on at least one occasion over the two years (five women had detectable oestradiol levels and did not bleed). None had evidence of endometrial stimulation at dilatation and curettage. Eighty percent of women who bled in the control group were between six and 12 months since LMP on entry into the study, and 80% had detectable oestradiol levels during the study. At dilatation and curettage there was no evidence of endometrial stimulation. CONCLUSIONS: A minority of women will bleed on tibolone therapy. Women who are likely to bleed are younger, are recently menopausal, and may have remaining endogenous oestrogen production.

Anabolic Agents↗
PubMed1992

T cell responses to the human papillomavirus type 16 E7 protein in mice of different haplotypes.

The response of murine T cells to the E7 molecule of human papillomavirus type 16 (HPV-16) was studied using eight different mouse strains of six distinct H-2 haplotypes. HPV-16 E7 protein was prepared as a fusion protein with glutathione-S-transferase, purified by affinity chromatography and used for immunization. Cells from the lymph nodes were cultured with whole fusion protein, glutathione-S-transferase or HPV-16 E7 protein synthetic peptides. All the mouse strains tested, with the exception of BALB/c, recognized the E7 molecule, as evidenced by a proliferative response to at least two of the peptides. The profile of responses to peptides varied between and within a strain, but five distinct immunodominant regions could be identified. These regions were defined on the basis of a reaction to one or more peptides in a given part of the E7 molecule by at least four strains. The five regions were encompassed by amino acid residues 1 to 9, 17 to 32, 42 to 59, 62 to 77 and 87 to 98. The findings suggest that in an outbred population, such as man, the E7 molecule of HPV-16 would be recognized by a large proportion of the population. However, the poor response of two mouse strains [B10.RIII (71NS) and BALB/c] could also have a corollary in man.

Animals↗
PubMed1991

Attitudes of donors and recipients to gamete donation.

An anonymous questionnaire was circulated at two gamete donation clinics to survey the attitudes of donor insemination patients (n = 71; 89% response rate), sperm donors (n = 52; 85% response rate) and ovum donors (n = 5; 63% response rate) to the release of medical records with non-identifying information, or with identifying information of the donor involved. The majority of established sperm donors agreed to the release of medical records with or without identifying information. In the subset of potential sperm donors 85% would not enter a sperm donation programme unless anonymity was maintained, but 60% would agree to the release of non-identifying medical records. Sixty per cent of recipients of donated spermatozoa would agree to the release of medical records with identifying information of the donor, but 85% stated that they would not tell their children of their genetic origin. There is a significant difference between the attitudes of potential sperm donor recruits to these questions and those of established donors and recipients of donated spermatozoa. In conclusion, the results of this survey show that although established sperm donors would continue to donate spermatozoa if their status of anonymity was withdrawn, recruitment of new donors would be significantly reduced. This would be to the detriment of gamete donation programmes and to the subfertile couples who request this form of treatment.

Attitude↗
PubMed1991

A comparison of the transient hyperprolactinaemic stress response obtained using two different methods of analgesia for ultrasound-guided transvaginal oocyte retrieval.

Transient hyperprolactinaemia has been shown to accompany the procedure of oocyte retrieval under laparoscopic control. This study was concerned with establishing whether transvaginal oocyte retrieval was also associated with hyperprolactinaemia and whether the hyperprolactinaemic response was dependent on the method of anaesthesia/analgesia employed. Two distinct patterns were recorded. Oocyte retrieval under general anaesthesia was accompanied by a rapid rise in prolactin levels, which peaked after 40 min. Oocyte retrieval under intravenous sedation was associated with a slow rise in circulating prolactin concentrations. Significant differences in the prolactin rise between the general anaesthesia and sedation groups appeared within 10 min of the start of the procedure. It is concluded that although the surgical stress of oocyte recovery is associated with mild transient hyperprolactinaemia, most of the hyperprolactinaemic response is due to the anaesthetic.

Analgesia↗
PubMed1990

Premenopausal bone loss in the lumbar spine and neck of femur: a study of 225 Caucasian women.

Two hundred and twenty-five premenopausal women were studied to evaluate age-related changes in trabecular bone mass. Measurements were made at the lumbar spine and femoral neck by dual photon absorptiometry. It was found that spinal bone density increased significantly from the 20s to reach a peak in the mid-30s. Identical trends were observed in total bone mass and bone mass normalized by length. Bone loss then proceeded at a rate of 1% per year, and by the early 50s, 10% of peak spinal density was lost. There was no peak in femoral neck density; loss commenced in the late 20s and continued at a rate of 0.4% per year. The cumulative premenopausal loss from the femur at 9% was comparable to that in the spine. It is concluded that significant amounts of trabecular bone are lost from both the spine and femoral neck before the menopause. The implications of these findings for the prevention of osteoporosis are discussed.

Absorptiometry, Photon↗
PubMed1990

Structural cardiac abnormalities in the fetus: reliability of prenatal diagnosis and outcome.

The outcomes of 129 pregnancies in which the fetus was found to have a structural cardiac abnormality are reviewed. Over a 30-month period from January 1985 to June 1987, 1924 patients were referred to the British Heart Foundation Research Centre for Perinatal Cardiology at Guy's Hospital for fetal cardiac scanning. A total of 129 structural cardiac abnormalities was diagnosed; 53% of these patients were referred because of an abnormal 'four-chamber view' on ultrasound at the referring hospital; 47 of the pregnancies (69% of the 68 patients referred before 28 weeks) were terminated, and in the remaining 82 pregnancies outcome was poor with only 20 infants (16%) surviving longer than 11 months. The prenatal diagnosis was fully or partly correct in 96% of the 111 cases where it was possible to verify the diagnosis by post-mortem or postnatal diagnosis. In the 82 pregnancies not terminated, 13 of the 22 cases given a moderate or good prognosis survived more than 11 months (59% survival), but only seven of the 60 (12% survival) given a fatal, poor or uncertain prognosis. The benefits of a multidisciplinary approach are discussed.

Chromosome Aberrations↗
PubMed1989

Ovulation induction in polycystic ovarian disease by pure FSH (Metrodin). A comparison between chronic low-dose pulsatile administration and i.m. injections.

A randomized cross-over study was performed to assess the value of pulsatile versus i.m. administration of pure FSH in polycystic ovarian disease. All patients admitted to the study had failed to respond to treatment with clomiphene citrate, while four had also been unsuccessfully treated with i.m. Pergonal. Sixteen cycles with i.m. FSH and 15 cycles with pulsatile s.c. FSH were analysed. The results showed no statistically significant differences in the dosage, the rate of ovulation or pregnancy rate. Hyperstimulation occurred in 30% of both the treatment groups. It is concluded that chronic low-dose pulsatile administration of pure FSH (Metrodin, Serono) has no advantage over chronic low-dose i.m. administration.

Adult↗
PubMed1989

Circulating levels of placental protein 12 and chorionic gonadotrophin following RU 38486 and gemeprost for termination of first trimester pregnancy.

First trimester termination of pregnancy was successfully induced in ten patients with RU 38486 followed 2 days later by a prostaglandin (Gemeprost) pessary. Human chorionic gonadotrophin (HCG) values remained unaltered until after the abortion. The levels of placental protein 12 (PP12) showed an immediate and significant fall following RU 38486, then rose to values substantially higher than those at the initial visit after 2 days. These findings show that RU 38486 has a direct inhibitory effect on tissues producing PP12 and confirm the progesterone dependency of this protein.

Abortifacient Agents↗