Physicians' beliefs and behaviour during a randomized controlled trial of episiotomy: consequences for women in their care.

OBJECTIVE: To evaluate whether physicians'' beliefs concerning episiotomy are related to their use of procedures and to differential outcomes in childbirth. DESIGN: Post-hoc cohort analysis of physicians and patients involved in a randomized controlled trial of episiotomy. SETTING: Two tertiary care hospitals and one community hospital in Montreal. PARTICIPANTS: Of the 703 women at low risk of medical or obstetric problems enrolled in the trial we studied 447 women (226 primiparous and 221 multiparous) attended by 43 physicians. Subjects attended by residents or nurses were excluded. MAIN OUTCOME MEASURES: Patients: intact perineum v. perineal trauma, length of labour, procedures used (instrumental delivery, oxytocin augmentation of labour, cesarean section and episiotomy), position for birth, rate of and reasons for not assigning women to a study arm, postpartum perineal pain and satisfaction with the birth experience, physicians: beliefs concerning episiotomy. RESULTS: Women attended by physicians who viewed episiotomy very unfavorably were more likely than women attended by the other physicians to have an intact perineum (23% v. 11% to 13%, p < 0.05) and to experience less perineal trauma. The first stage of labour was 2.3 to 3.5 hours shorter for women attended by physicians who viewed episiotomy favourably than for women attended by physicians who viewed episiotomy very unfavorably (p < 0.05 to < 0.01), and the former physicians were more likely to use oxytocin augmentation of labour. Physicians who viewed episiotomy more favourably failed more often than those who viewed the procedure very unfavourably to assign patients to a study arm late in labour (odds ratio [OR] 1.88, p < 0.05), both overall and because they felt that "fetal distress" or cesarean section necessitated exclusion of the subject. They used the lithotomy position for birth more often (OR 3.94 to 4.55, p < 0.001), had difficulty limiting episiotomy in the restricted-use arm of the trial and diagnosed fetal distress and perineal inadequacy more often than the comparison groups. The patients of physicians who viewed episiotomy very favourably experienced more perineal pain (p < 0.01), and of those who viewed episiotomy favourably and very favourably experienced less satisfaction with the birth experience (p < 0.01) than the patients of physicians who viewed the procedure very unfavourably. CONCLUSIONS: Physicians with favourably views of episiotomy were more likely to use techniques to expedite labour, and their patients were more likely to have perineal trauma and to be less satisfied with the birth experience. This evidence that physician beliefs can influence patient outcomes has both clinical and research implications.     

Hemodynamic consequences of rapid changes in posture in humans.

Tolerance to +G(z) gravitational stress is reduced when +G(z) stress is preceded by exposure to hypogravity (fraction, 0, or negative G(z)). For example, there is an exaggerated fall in eye-level arterial pressure (ELAP) early on during +G(z) stress (head-up tilt; HUT) when this stress is immediately preceded by -G(z) stress (head-down tilt; HDT). The aims of the present study were to characterize the hemodynamic consequences of brief HDT on subsequent HUT and to test the hypothesis that an elevation in leg vascular conductance induced by -G(z) stress contributes to the exaggerated fall in ELAP. Young healthy subjects (n = 3 men and 4 women) were subjected to 30 s of 30 degrees HUT from a horizontal position and to 30 s of 30 degrees HUT when HUT was immediately preceded by 20 s of -15 degrees HDT. Four bouts of HDT-HUT were alternated between five bouts of HUT in a counterbalanced designed to minimize possible time effects of repeated exposure to gravitational stress. One minute was allowed for recovery between tilts. Brief exposure to HDT elicited an exaggerated fall in ELAP during the first seconds of the subsequent HUT (-17.9 +/- 1.4 mmHg) compared with HUT alone (-12.4 +/- 1.2 mmHg, P <0.05) despite a greater rise in stroke volume (Doppler ultrasound) and cardiac output over this brief time period in the HDT-HUT trials compared with the HUT trials (thereafter stroke volume fell under both conditions). The greater fall in ELAP was associated with an exaggerated increase in leg blood flow (femoral artery Doppler ultrasound) and was therefore largely (70%) attributable to an exaggerated rise in estimated leg vascular conductance, confirming our hypotheses. Thus brief exposure to -G(z) stress leads to an exaggerated fall in ELAP during subsequent HUT, owing to an exaggerated increase in estimated leg vascular conductance.     

Land use change in Asia and the ecological consequences

Viewed within a historical context, Asia has experienced dramatic land transformations, and currently more than 50% of Asian land area is under agriculture. The consequences of this transformation are manifold. Southeast Asia has the highest deforestation rate of any major tropical region. Many of the world’s large rivers and lakes in Asia have been heavily degraded. About 11 of 19 world megacities with more than 10 million inhabitants are in Asia. These land use activities have resulted in substantial negative ecological consequences, including increased anthropogenic CO₂ emissions, deteriorated air and water quality, alteration of regional climate, an increase of disease and a loss of biodiversity. Although land use occurs at the local level, it has the potential to cause ecological impact across local, regional and global scales. Reducing the negative environmental impacts of land use change while maintaining economic viability and social acceptability is an major challenge for most developing countries in Asia.     

Calcium channels and pumps in cancer: changes and consequences

Increases in intracellular free Ca(2+) play a major role in many cellular processes. The deregulation of Ca(2+) signaling is a feature of a variety of diseases, and modulators of Ca(2+) signaling are used to treat conditions as diverse as hypertension to pain. The Ca(2+) signal also plays a role in processes important in cancer, such as proliferation and migration. Many studies in cancer have identified alterations in the expression of proteins involved in the movement of Ca(2+) across the plasma membrane and subcellular organelles. In some cases, these Ca(2+) channels or pumps are potential therapeutic targets for specific cancer subtypes or correlate with prognosis.     

Progressive changes in the pulpo-dentinal complex and their clinical consequences

With changes in the age structure and oral health in the population, changes in the pulpo-dentinal complex are becoming more relevant clinically. Age-related changes in the structure of dentine and pulp are reviewed. The influence of these changes on restorative dentistry are considered with particular emphasis on endodontics and the use of adhesive restorative materials.     

Functional consequences of sphingomyelinase-induced changes in erythrocyte membrane structure

Inflammation enhances the secretion of sphingomyelinases (SMases). SMases catalyze the hydrolysis of sphingomyelin into phosphocholine and ceramide. In erythrocytes, ceramide formation leads to exposure of the removal signal phosphatidylserine (PS), creating a potential link between SMase activity and anemia of inflammation. Therefore, we studied the effects of SMase on various pathophysiologically relevant parameters of erythrocyte homeostasis. Time-lapse confocal microscopy revealed a SMase-induced transition from the discoid to a spherical shape, followed by PS exposure, and finally loss of cytoplasmic content. Also, SMase treatment resulted in ceramide-associated alterations in membrane–cytoskeleton interactions and membrane organization, including microdomain formation. Furthermore, we observed increases in membrane fragility, vesiculation and invagination, and large protein clusters. These changes were associated with enhanced erythrocyte retention in a spleen-mimicking model. Erythrocyte storage under blood bank conditions and during physiological aging increased the sensitivity to SMase. A low SMase activity already induced morphological and structural changes, demonstrating the potential of SMase to disturb erythrocyte homeostasis. Our analyses provide a comprehensive picture in which ceramide-induced changes in membrane microdomain organization disrupt the membrane–cytoskeleton interaction and membrane integrity, leading to vesiculation, reduced deformability, and finally loss of erythrocyte content. Understanding these processes is highly relevant for understanding anemia during chronic inflammation, especially in critically ill patients receiving blood transfusions.     

Covalent binding of glutathione to hemoglobin. II. Functional consequences and structural changes reflected in NMR spectra

Binding of glutathione by disulfide linkage to Cys-beta 93 of hemoglobin tetramers within sickle cells increases the oxygen affinity and significantly inhibits sickling at low partial oxygen pressure (Garel, M-C., Domenget, C., Caburi-Martin, J., Prehu, C., Galacteros, F., and Beuzard, Y. (1986) J. Biol. Chem. 261, 14704-14709). This article reports a characterization of the oxygen-binding properties of glutathionyl hemoglobin (G-Hb) in solution in the presence or absence of allosteric effectors. The studies reveal a nearly 6-fold increase in oxygen affinity compared to native HbA and a Hill coefficient at half-saturation (n50) of 1.50 compared to n50 of approximately 2.9 for HbA. The oxygen Bohr effect measured in the alkaline pH range is reduced by 38%. Addition of 2,3-diphosphoglycerate decreases the oxygen affinity of G-Hb and HbA to a similar extent and increases the Bohr effect, indicating that the binding sites for organic phosphates are not perturbed in G-Hb. The rate of autooxidation of G-HbO2 is slower than of HbAO2. Oxidation by ferricyanide of G-HbCO is also reduced and is biphasic, demonstrating a heterogeneous susceptibility of the hemes in G-Hb. Flash photolysis experiments indicate that the tetramer-dimer dissociation constant is 1 order of magnitude greater for G-HbCO than for HbACO. High resolution NMR spectra at 400 MHz show that in G-Hb: the tertiary structure of the beta heme pocket is significantly perturbed, particularly in the F helix and the EF corner; the formation of the salt bridge between His-beta 146 and Asp-beta 94, a feature of the deoxy state, is precluded; and a deoxy interchain (alpha 1 beta 2) contact between Asp beta 2 99 and Tyr alpha 1 42 is appreciably destabilized. The NMR data provide a structural basis for interpreting the high oxygen affinity, reduced cooperativity, and diminished polymerization of G-HbS.     

Population consequences of changes in an ant-seed mutualism in Sanguinaria canadensis

Summary Seed dispersal by ants was studied in three populations of the myrmecochore, Sanguinaria canadensis, located in three habitats, each of which showed a different level of disturbance. Frequency of seed removal and the distances seeds were carried by ants were related to plant density, dispersion and the relative proportions of sexual and asexual reproduction in each population. Seeds in the least disturbed habitat were removed frequently and carried, by a wide variety of ants, distances of up to 12 m. Plant density was low and clone size was small. There was a relatively low level of sexual (seed) reproduction but seeds were generally transported well beyond the boundaries of the parent clones. By contrast, at the most disturbed site, plant density was high and clone size was very large. While there was a high level of seed production, seeds were rarely moved by ants and since removal distances were short, the probability of a seed being relocated beyond the limits of the parent clone was miniscule. The third population from a habitat which was intermediate in disturbance yielded data intermediate to the others. The data show that habitat disturbance, in disrupting the ant fauna and hence the ant-seed mutualism, has profound effects upon population density, dispersion and patterns of reproduction. Density-dependent regulation of sexual output predicted, for example, by the Strawberry-Coral model (Williams 1975), is maladaptive when the antseed mutualism is disturbed. We discuss the implications of this for theoretical modeling, the significance of mutualisms and the assessment of disturbance for conservation.     

The functional consequences of alternative promoter use in mammalian genomes

We are beginning to appreciate the increasing complexity of mammalian gene structure. A phenomenon that adds an important dimension to this complexity is the use of alternative gene promoters that drive widespread cell type, tissue type or developmental gene regulation. Recent annotations of the human genome suggest that almost one half of the protein-coding genes contain alternative promoters, including those of many disease-associated genes. Aberrant use of one promoter over another has been found to be associated with various diseases, including cancer. Here we discuss the functional consequences of use and misuse of alternative promoters in normal and disease genomes and review the molecular mechanisms regulating alternative promoter use in mammalian genomes.     

The effects of changes in consequences on hens' performance in delayed-matching-to-sample tasks

A delayed-matching-to-sample (DMTS) task was used to investigate remembering with domestic hens. In Conditions 1 and 3 of Experiment 1, six hens responded under a mixed-delay procedure with delays of 0.25, 2, and 8 s. In Condition 2, the reinforcer for correct responding was delayed for 6 s after each correct matching response on 2-s delay trials. In Condition 1, discrimination performance decreased monotonically over the three delays. With the delay to the reinforcer, the decreases were non-monotonic as a result of the considerable drop in the accuracy of discrimination on the 2-s delay trials. Performance at the 2-s delay did not recover completely in Condition 3. In Conditions 1 and 3 of Experiment 2, five hens responded under a mixed-delay procedure with delays of 0, 4, and 16 s. In Condition 2 no reinforcers were provided for correct responding on 0- and 16-s delay trials. When reinforcers were available on all trials discrimination performance decreased monotonically with delay. There were non-monotonic changes in discrimination with delay when there was extinction at two delays resulting mainly from a large drop in discrimination performance at 0 s. In addition, response latencies increased markedly at the two delays associated with extinction. Performance recovered completely in Condition 3. The data support the ideas that remembering involves a temporal discrimination that the effects of delaying reinforcement and removing reinforcement may differ, and that the measurement of response latencies may be a useful tool in DMTS procedures.     

Fitness consequences of individual specialisation in resource use and trophic morphology in European eels

Individual specialisation can lead to the exploitation of different trophic and habitat resources and the production of morphological variability within a population. Although the ecological causes of this phenomenon are relatively well known, its consequences on individual fitness are less recognised. We have investigated the extent of individual specialisation in resource use and trophic morphology and its fitness consequences through a combination of tagging–recapture, stable isotope analyses and telemetry. The European eel (Anguilla anguilla) was the model species as it displays significant variability in head shape. Independent to their body length, individuals with broader heads displayed a significantly higher trophic position (δ¹⁵N) than individuals with narrower heads. This corresponded with a significantly higher proportion of prey fish in their diet compared with invertebrates and was associated with the use of a habitat niche located further from the river bank. The European eel therefore provides a rare empirical example of individual specialisation in resource use and trophic morphology in a natural population occurring at a very small spatial scale. Individuals with intermediate head morphology displayed lower body condition (a proxy of fitness) than individuals with extreme head morphology (i.e. narrower and broader headed individuals), demonstrating the existence of disruptive selection associated with individual specialisation.     

Neuropeptides, apoptosis and ion changes in prostate cancer. Methods of study and recent developments

It has been suggested that neuroendocrine (NE) cells provide paracrine stimuli for the propagation of local carcinoma cells and that NE differentiation is associated with the progression of prostate cancer toward an androgen-independent state. Apoptosis comprises a critical intracellular defense mechanism against tumorigenic growth and is associated with a number of changes in the elemental content of the cell. The neuropeptides bombesin and calcitonin, which inhibit etoposide-induced apoptosis, also inhibit the etoposide-induced elemental changes in prostate carcinoma cells. This important fact strengthens the link between apoptosis and changes in the intracellular elemental content. This protective effect on etoposide-induced apoptosis appears to be quite similar in androgen-dependent and androgen-independent cell lines. This confirms that neuropeptides confer antiapoptotic capabilities on non-neuroendocrine cells in close proximity to neuroendocrine cells. It can therefore be speculated that certain neuroendocrine peptides can increase the survival and further growth of neighboring cells and may thereby contribute to the aggressive clinical course of prostate tumors containing neuroendocrine elements. In addition, this correlation provides an objective basis for the study of neuropeptide target points and may be helpful for alternative therapeutic protocols using neuropeptide inhibitors in the treatment of patients with advanced prostatic carcinoma. The culture techniques described were, thus, designed in order to achieve two important goals. First, the development of an in vitro model that allows an approach to neuroendocrine differentiation in prostate cancer and its role in apoptosis blockage. Second, the method has been designed in order to permit rapid cryofixation of intact cell monolayers for subsequent x-ray microanalysis.