Proceedings of the Symposium ‘Angiotensin AT1 Receptors: From Molecular Physiology to Therapeutics’: PHYSIOLOGICAL ACTIONS OF ANGIOTENSIN II MEDIATED BY AT1 AND AT2 RECEPTORS IN THE BRAIN

• 1 Autoradiographic binding studies have shown that the AT₁ receptor is the predominant angiotensin II (AngII) receptor subtype in the central nervous system (CNS). Major sites of AT₁ receptors are the lamina terminalis, hypothalamic paraventricular nucleus, the lateral parabrachial nucleus, rostral and caudal ventrolateral medulla, nucleus of the solitary tract and the intermediolateral cell column of the thoraco-lumbar spinal cord.
• 2 While there are differences between species, AT₂ receptors are found mainly in the cerebellum, inferior olive and locus coeruleus of the rat.
• 3 Circulating AngII acts on AT₁ receptors in the subfornical organ and organum vasculosum of the lamina terminalis (OVLT) to stimulate neurons that may have a role in initiating water drinking.
• 4 Centrally administered AngII may act on AT₁ receptors in the median preoptic nucleus and elsewhere to induce drinking, sodium appetite, a sympathetic vasoconstrictor response and vasopressin secretion.
• 5 Recent evidence shows that centrally administered AT₁ antagonists inhibit dipsogenic, natriuretic, pressor and vasopressin secretory responses to intracerebroventricular infusion of hypertonic saline. This suggests that an angiotensinergic neural pathway has a role in osmoregulatory responses.
• 6 Central angiotensinergic pathways which include neural inputs to the rostral ventrolateral medulla may use AT₁ receptors and play a role in the function of sympathetic pathways maintaining arterial pressure.

     

Left ventricular volumes measured by MR imaging

We assessed the potential of proton magnetic resonance (MR) imaging for accurately measuring left ventricular volumes using 15 latex casts of excised human left ventricles. The casts were submerged in water to stimulate the endocardial left ventricular cavity interface in in vivo imaging conditions. Tomographic image sections perpendicular to the long axis of the cast were obtained, spanning each cast from apex to base. Simpson's rule was used to calculate the cast volumes. Correlation between the actual cast volumes (as measured by the displacement method) and the calculated volumes using MR imaging for the 15 casts was excellent. Our data demonstrate that MR imaging accurately measures cardiac chamber volumes in this in vitro model.     

How Do Physicians and Midwives Manage the Third Stage of Labor?

ABSTRACT: Background: Current practice guidelines recommend active management of the third stage of labor. We compared practices of three maternity care provider disciplines in management of third‐stage labor and the justifications for their approach. Methods: This study is a cross‐sectional survey of maternity practitioners in usual practice settings in British Columbia. All 199 obstetricians, all 82 midwives, and a random sample of family physicians practicing intrapartum maternity care (one‐third, or 346) were surveyed The three main outcome measures by discipline were the method preferred in managing third‐stage labor, the reasons given for the chosen method, and views on the appropriateness of the current third‐stage labor guideline. Results: The overall response rate was 57.8 percent. Response rates indicating that the participants were “aware of guideline” were the following: obstetricians, 85.3 percent; family physicians, 53.7 percent; and midwives, 97.8 percent. Response rates indicating that the participants “agreed with guideline” were the following: obstetricians, 95.2 percent; family physicians, 97.6 percent; and midwives, 51.2 percent. Response rates indicating that “oxytocin should be given with anterior shoulder” were the following: obstetricians, 71.1 percent; family physicians, 68.3 percent; and midwives, 26.7 percent. Response rates indicating that “routine active management of third stage of labor should be the norm” were the following: obstetricians, 79.2 percent; family physicians, 60.2 percent; and midwives, 17 percent. All results were statistically significant (p < 0.01). Conclusions: A major difference was found between physicians and midwives in the management of third‐stage labor. Physicians routinely implemented active management of the third stage of labor; midwives preferred expectant approaches, principally based on women’s preference. Provincial data did not show differences in postpartum hemorrhage or transfusion rates by practitioner type. (BIRTH 35:3 September 2008)     

Morphological changes due to Lead exposure and the influence of DMSA on the gill tissues of the freshwater fish, Catla catla

Catla catla fingerlings were reared in freshwater and exposed to 15.5 ppm concentration of lead for 60 days. The morphological changes on the gill of the C. catla fingerlings due to lead intoxication and the effect of DMSA (meso 2,3-dimercaptosuccinic acid) on the affected tissues were observed using Scanning Electron Microscope. It has been found that the lead treated gill tissues showed certain marked changes, such as cell hypertrophy, alteration in the lamellar surfaces, epithelial hyperplasia and the fusion of adjacent lamellae. The antidote DMSA treatment reduces the toxic effects and helps the recovery of gill tissue and its return to the level of the control/normal.     

Nurse socialization: issues and problems

A comparative study was conducted of the professional socialization process of student nurses in three nurse education centres in South Wales. Patterns and problem areas can be identified of relevance to issues in role theory and with practical implications for the more effective implementation of Project 2000. Three cohorts of students were interviewed using a semi-structured interview schedule whilst in the introductory block and at the end of the first year. The teaching and ward staff directly involved in the socialization process were also interviewed so that their views could be compared with those of the students. There were differences between the types of ward in the opportunities they offered for role modelling. It was doubtful whether the three categories of students, teaching staff and ward staff were all employing a single conception of 'the good nurse'. The student has to find her own pathway through the divergent and often conflicting values and philosophies of the teaching staff and those in authority on the wards. It is recommended that a more unified approach be adopted to reduce the conflict which learners experience. In accordance with Project 2000, the teaching staff should act as practitioners and thereby be perceived as a professional role model with clinical credibility.     

Spondylometaphyseal dysplasia, corner fracture type: a heritable condition associated with coxa vara

The authors present the radiographic features of a previously incompletely delineated bone dysplasia, which they call spondylometaphyseal dysplasia, corner fracture type. This is a dominant heritable condition associated with short stature and developmental coxa vara. The progressive hip deformity usually causes significant disability requiring surgical correction. Developmental coxa vara, simulated corner fractures of long tubular bones, and vertebral body abnormalities result in a diagnostic constellation. Knowledge of these distinctive radiologic features allows accurate diagnosis, which in turn should lead to appropriate genetic counseling and possibly to earlier, more efficacious surgical treatment of the coxa vara.