Biomedical subjects
J Robinson
Publications and source records attributed to J Robinson.
Knee-chest postural management for breech at term: a randomized controlled trial.
BACKGROUND: In 3 to 4 percent of all term births, the fetus presents as a breech. The objectives of this trial were to assess if assuming the knee-chest position reduced the frequency of breech presentation at delivery, increased the success of the subsequent external cephalic version, or both, and to determine if this management plan reduced the need for cesarean delivery. METHODS: A randomized clinical trial recruited 100 women from two hospitals in Adelaide, South Australia, with a singleton breech presentation and a gestational age equal to or more than 36 weeks. Women in the treatment group were advised to assume the knee-chest position for 15 minutes three times a day for one week. Women in the control group did not perform postural management. All participants were reviewed one week later, and women whose baby remained as a breech presentation were offered an external cephalic version. RESULTS: Postural management did not increase the success of the external cephalic version, reduce the frequency of breech presentation at delivery, or reduce the need for cesarean delivery in women with a breech presentation at term. CONCLUSIONS: Findings from this trial included in a meta-analysis of postural management for breech presentation at term suggested that this is not an effective form of care to be offered routinely to women with a breech presentation at term.
A complication of the tapered aortouni-iliac graft for endovascular aneurysm repair.
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Ultrasound evaluation of the uterine zonal anatomy during in-vitro fertilization and embryo transfer.
This study was designed to establish if ultrasound could detect differences in uterine zonal anatomy between conception and non-conception in-vitro fertilization (IVF)/embryo transfer cycles. A transvaginal ultrasound scan was performed on the day of down regulation (D0), on day 8 of ovulation induction (D8), on the day of human chorionic gonadotrophin (HCG) injection, at the time of oocyte retrieval, and at embryo transfer. Thicknesses of endometrium, junctional zone, myometrium and full thickness of the uterus were recorded for every patient and comparisons made at all the assessment points. Differences between measurements on D0 and all other measurements (temporal changes) and between every subsequent measurement (dynamic changes) were also compared. There were no statistically significant differences in endometrial thickness between pregnant and non-pregnant groups at any time. The diameter of the uterus increased during therapy and was significantly greater in the pregnant subset at the time of HCG injection, oocyte retrieval and embryo transfer (P < 0.02, 0.03 and 0.02 respectively). The myometrium was significantly thicker in the pregnant group on D0, on D8 and at HCG administration (P < 0.03, 0.004 and 0.02). There was a decrease in junctional zone thickness in both groups during the first week of ovulation induction, and on D8 the junctional zone in pregnant patients was significantly thinner (P < 0.04). The junctional zone became significantly thicker at embryo transfer in the pregnant group (P < 0.01). This was confirmed by significant temporal and dynamic changes at the time of oocyte retrieval and embryo transfer (P < 0.01, 0.0001 and P < 0.05, 0.01 respectively). In the patients who did not conceive, changes in the junctional zone were less pronounced. In conclusion, it was not possible to predict the likelihood of pregnancy from endometrial thickness at any time during the IVF cycle, but changes occurred in other uterine layers that were more pronounced in conception cycles. The responsiveness of the junctional zone seems to be associated with implantation, and its measurements at the time of downregulation and embryo transfer can be used to predict treatment outcome.
Ovarian hyperstimulation syndrome and benign intracranial hypertension in pregnancy after in-vitro fertilization and embryo transfer: case report.
Ovarian hyperstimulation syndrome (OHSS) is a dangerous and sometimes life-threatening complication of ovulation induction with exogenous gonadotrophins. While many complications of severe OHSS are recognized we have only identified one review detailing neurological problems. This report concerns a 32-year-old patient with bilateral tubal blockage who achieved her first pregnancy following in-vitro fertilization (IVF) and embryo transfer. Shortly after embryo transfer she developed clinical signs of moderate OHSS with symptoms which were later diagnosed as benign intracranial hypertension (BIH). The BIH was treated effectively using repeated lumbar puncture and diuretics. Spontaneous labour and delivery occurred at 40 weeks' gestation. There was no neurological sequel and no recurrence of the BIH 2 years after the pregnancy. The possible link between OHSS and BIH is discussed as well as the risks of further pregnancy.
Junctional zone contractions and embryo transfer: is it safe to use a tenaculum?
Applying a tenaculum to the cervix is a common practice when the correction of uterine position prior to embryo transfer is required. Our study was designed to assess junctional zone contractility before and after this procedure in 20 patients at the time of mock embryo transfer (mid-luteal phase, at commencement of down-regulation). Real-time transvaginal ultrasound and computer technology was used to evaluate the contraction pattern and frequency. When a tenaculum was applied, the total number of contractions, the number of cervico-fundal, random and opposing contractions all increased significantly (P values 0.0003, 0.005, 0. 001 and 0.007 respectively). Eleven women displayed cervico-fundal contractions, prominent opposing and random contractions were observed in all 20 patients and four patients generated fundo-cervical waves not seen in any case before stimulation with the instrument. In conclusion, manipulation with a tenaculum in the cervical area stimulates junctional zone contractions and is best avoided at the time of embryo transfer.
Statin prescribing in Nottingham general practices: a cross-sectional study.
BACKGROUND: The aim of the study was to determine the effect of deprivation on variations in statin prescribing in Nottingham general practices. Deprivation is used as a measure of population cardiovascular morbidity and need for statin treatment. The setting was all 118 general practices in contract with Nottingham Health Authority. METHODS: A cross-sectional study was undertaken. Statin prescribing in general practice during 1996 was related to indices of practice deprivation based on enumeration district (ED) level data from the 1991 Census. The relationship between statin prescribing per 1000 patients aged 35-69 and practice deprivation (measured both as Townsend score and as Jarman UPA(8) score) with additional adjustment for practice characteristics (number of partners, training status, total list size, fundholding status) cardiovascular prescribing costs net of lipid prescribing and hospital activity (total and medical admissions and new general practitioner total and medical out-patient referrals) for each practice. RESULTS: The prescription of statins during 1996 varied between nil and 14.1 'statin-years' of prescribing per 1000 patients aged 35-69. There was a significant inverse relationship between the rate of statin prescribing and the level of deprivation of that practice (p < 0.0001). Deprivation, as measured by Townsend index, accounted for 13 per cent of the total variability in statin prescribing, which rose to 19 per cent after adjustment. The prescribing of other lipid lowering agents of the fibrate class was positively associated with statin prescribing (p=0.001) and this association persisted after adjusting for deprivation. None of the other practice characteristics were found to be significantly associated with rates of statin prescribing. CONCLUSIONS: General practices with high deprivation indices serve more deprived populations with a higher prevalence of cardiovascular disease, and may be assumed to have a greater need for statins. Despite this, practices with higher deprivation indices prescribed fewer statins to their patients than less deprived practices. It was not possible to identify whether the more deprived general practices had successfully identified at risk individuals but it is likely that special efforts are needed to increase the uptake of effective health care in their patients.
Partners in care: a model of collaboration.
It is estimated that 3 million persons in the United States have congestive heart failure. This diagnosis accounts for more than 5% of total health expenditures. A method to decrease the costs of health care was initiated through the partners-in-care model of collaborative practice. A research study exploring the use of nurse case managers in collaboration with cardiologists and primary care physicians is being conducted with persons older than 65 years. This care encompasses both inpatient and outpatient care. The intervention comprises nurse visits in the hospital and in the home as well as telephone support for 6 months after the index hospitalization. The outcomes of quality of life, functional status, mortality, morbidity, and costs are being examined. Collaborative health care partnerships may be an effective strategy to decrease health care costs and improve quality of life and functional status of older persons with congestive heart failure.
Long term effects of tibolone on the genital tract in postmenopausal women.
OBJECTIVES: To assess the effects of six years tibolone therapy on the genital tract in postmenopausal women against matched voluntary controls. DESIGN: Prospective, non-randomised, open label study of the efficacy of tibolone. METHODS: Symptoms were assessed by questionnaires every six months. Assessment of genital tract cellular activity comprised annual vaginal smear and endometrial biopsy/smear in the tibolone group (n = 58) and vaginal smear alone in the control group (n = 55). As a recent protocol addition, transvaginal ultrasound assessment of endometrial thickness was performed in all women who gave consent. Endometrial biopsy was performed in control women if the endometrial thickness was > 5 mm. Karyopyknotic index and maturation index were calculated from the vaginal smears. RESULTS: The rate of amenorrhoea between six months and six years treatment was 90% in the tibolone group compared with 91% in the controls (P was not significant). There was improvement in reported vaginal symptomatology in the treatment group but not in the controls. Median endometrial thickness increased slightly in the tibolone treated group (3.2 mm tibolone vs 2.5 mm control; P < 0.05). There were no cases of cytologically proven endometrial stimulation in asymptomatic women in either group. Both vaginal karyopyknotic index and maturation index increased significantly in the tibolone treated group over six years, but not in the control group. CONCLUSIONS: Tibolone is effective at maintaining an inactive endometrium while providing oestrogenisation of the lower genital tract over a six year period.
Child sexual abuse prevention programs in Texas public elementary schools.
This survey determined if selected Texas public school districts provided an established child sexual abuse prevention program for elementary schools. The survey examined the type of program being implemented, training available for faculty and staff type of evaluation used, involvement of local agencies, and type of funding sources. Survey data were obtained from a nonrandomized sample of 89 largest public school districts in Texas, all recording an average daily attendance over 5,000. Fifty-eight of the 89 districts addressed child sexual abuse as a formal prevention program or as an awareness program. Training for child sexual abuse prevention program presenters was offered in 89% of districts. Consistent, effective evaluation was minimal. Funding for prevention programs was limited or unknown. Results confirmed the need for consistent, effective child sexual abuse prevention programs in elementary schools.
Courage revisited.
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High resolution ultrasound assessment of the carotid artery: its relevance in postmenopausal women and the effects of tibolone on carotid artery ultrastructure.
OBJECTIVES: Hormone replacement therapy protects from cardiovascular disease at the menopause in part by reduction of menopausal pro-atherogenic serum lipid changes. Tibolone has beneficial effects on lipids, although serum high density lipoprotein levels decrease. This study aimed primarily to establish the effects of long-term administration of tibolone on a new surrogate marker for cardiovascular disease risk, the measurement of carotid artery intima-media thickness (CIMT) using high-resolution ultrasound. METHODS: Measurement of CIMT and assessment of carotid atherosclerotic plaques were undertaken in 31 women on tibolone and 30 voluntary controls from an ongoing open-label study of tibolone. RESULTS: The two groups were comparable, except for mean age and prevalence of current smokers. Repeatability of CIMT measurements was acceptable (CV, 10.0%). CIMT was significantly thicker in those with atherosclerotic plaques and increased systolic blood pressure. Prevalence of plaques was raised in those who had ever smoked, and those with elevated systolic blood pressure. There was no influence of tibolone on CIMT, whether plaques were present or not. CONCLUSIONS: This reliable technique demonstrates associations between CIMT and established risk factors. CIMT was significantly thicker in those with existing plaques. We did not demonstrate an effect of long-term tibolone use on either CIMT or prevalence of plaques.
Why an acceptable cloning policy will be hard to achieve.
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Methods for grouping shapes of synaptic currents recorded from sets of synapses.
Synaptic currents due to transmitter release at sets of synapses, such as those formed by a single nerve terminal on adjacent smooth muscle cells or a nerve terminal on a dendrite, possess different amplitudes and time courses, that is different shapes. It is possible that different shape groupings exist that may be each associated with a particular synapse in the set recorded from. Two methods, involving the distance between two synaptic currents, namely multidimensional scaling and hierarchical clustering, were used to suggest possible groupings. A test of differences between a pair of synaptic currents was developed by comparing the distances from pairs of synaptic currents with the distances from pairs of failures from the same experiment. This allowed observation of significance levels between and within the suggested groups. These methods were applied to loose-patch recordings of excitatory junctional currents (EJCs) in mouse vas deferens made with extracellular electrodes, some of which were visualised using DiOC2(5) staining to identify varicosities. Groups of EJC shapes could be distinguished supporting a hypothesis of several categories of shapes. However, each method showed that the number of shape-groupings was much larger than the number of visualised varicosities. Possible reasons for this discrepancy are analysed, including a model in which different shape groupings can be generated by a single synaptic site.
Modulation of arterial baroreflexes by antisense oligodeoxynucleotides to NMDAR1 receptors in the nucleus tractus solitarius.
An antisense oligodeoxynucleotide which specifically blocked the production of the glutamate receptor subtype NMDAR1 was administered to the nucleus tractus solitarius (NTS) in order to examine the role of this receptor in baroreflex control of heart rate. Baseline blood pressure and heart rate were unchanged by NTS treatment with the antisense oligodeoxynucleotide to the NMDAR1 receptor subunit. However, the reflex bradycardia evoked in response to the hypertension induced by bolus administration of phenylephrine was significantly attenuated following bilateral NTS antisense oligodeoxynucleotide treatment. Administration of the corresponding mismatched antisense oligodeoxynucleotide did not significantly alter the reflex bradycardia. These data indicate that NMDAR1 receptors are involved in neurotransmission in the baroreflex arc at the level of the NTS. The specificity of antisense oligodeoxynucleotides may prove to be a useful technique to analyze the role of receptor subtypes mediating neurotransmission in central pathways.
Darwinian Daisyworld.
The Daisyworld model was developed to show that organisms can collectively regulate the global environment without assuming conscious or altruistic behaviour, i.e. that Gaia is feasible. We studied the effects of adaptive evolution of Daisyworld by allowing daisies to shift their optimal growth temperatures toward the prevailing temperature. This estimates Daisyworld's homeostatic ability, suggesting a trade-off between the ability of organisms to collectively regulate the environment and the abilities of evolving genotypes to adapt to it.
Structure of an HIV gp120 envelope glycoprotein in complex with the CD4 receptor and a neutralizing human antibody.
The entry of human immunodeficiency virus (HIV) into cells requires the sequential interaction of the viral exterior envelope glycoprotein, gp120, with the CD4 glycoprotein and a chemokine receptor on the cell surface. These interactions initiate a fusion of the viral and cellular membranes. Although gp120 can elicit virus-neutralizing antibodies, HIV eludes the immune system. We have solved the X-ray crystal structure at 2.5 A resolution of an HIV-1 gp120 core complexed with a two-domain fragment of human CD4 and an antigen-binding fragment of a neutralizing antibody that blocks chemokine-receptor binding. The structure reveals a cavity-laden CD4-gp120 interface, a conserved binding site for the chemokine receptor, evidence for a conformational change upon CD4 binding, the nature of a CD4-induced antibody epitope, and specific mechanisms for immune evasion. Our results provide a framework for understanding the complex biology of HIV entry into cells and should guide efforts to intervene.
The antigenic structure of the HIV gp120 envelope glycoprotein.
The human immunodeficiency virus HIV-1 establishes persistent infections in humans which lead to acquired immunodeficiency syndrome (AIDS). The HIV-1 envelope glycoproteins, gp120 and gp41, are assembled into a trimeric complex that mediates virus entry into target cells. HIV-1 entry depends on the sequential interaction of the gp120 exterior envelope glycoprotein with the receptors on the cell, CD4 and members of the chemokine receptor family. The gp120 glycoprotein, which can be shed from the envelope complex, elicits both virus-neutralizing and non-neutralizing antibodies during natural infection. Antibodies that lack neutralizing activity are often directed against the gp120 regions that are occluded on the assembled trimer and which are exposed only upon shedding. Neutralizing antibodies, by contrast, must access the functional envelope glycoprotein complex and typically recognize conserved or variable epitopes near the receptor-binding regions. Here we describe the spatial organization of conserved neutralization epitopes on gp120, using epitope maps in conjunction with the X-ray crystal structure of a ternary complex that includes a gp120 core, CD4 and a neutralizing antibody. A large fraction of the predicted accessible surface of gp120 in the trimer is composed of variable, heavily glycosylated core and loop structures that surround the receptor-binding regions. Understanding the structural basis for the ability of HIV-1 to evade the humoral immune response should assist in the design of a vaccine.