Introduction There is no doubt that in breast-feeding women, suckling with its associated hyperprolactinaemia prevents the resumption of ovarian activity for prolonged periods (see McNeilly, 1979). The extent of this suppression varies greatly among species but in all for which there are adequate data it appears to depend critically upon the intensity of the suckling stimulus (Lamming, 1978). Our recent data from women show that in the pattern of suckling, frequency and duration, throughout the day, are both key factors in maintaining the elevation of basal levels of prolactin associated with lactation (McNeilly, Howie & Houston, 1980a; Howie & McNeilly, 1982). Suckling also releases large quantities of prolactin, maintaining a physiological hyperprolactinaemic state which is directly associated with the duration of lactational amenorrhoea (Delvoye, Badawi, Demaegd & Robyn, 1978; Duchen & McNeilly, 1980). The question remains, how does suckling suppress ovarian activity? The levels of prolactin in blood during peak
Summary. Active immunization of 6 Damline ewes against LHRH during seasonal anoestrus resulted in an inhibition of ovarian cyclicity throughout 2 subsequent breeding seasons. This was associated with a significant suppression of plasma LH and FSH concentrations but no significant effect on prolactin. The ovaries of LHRH-immunized ewes 30 months after primary immunization contained no follicles > 2·5 mm in diameter and a greater proportion of follicles between 1 and 2 mm were atretic than in control ewes (N = 8). In-vitro production of testosterone and androstenedione were similar in follicles 1–2 mm in both control and LHRH-immunized ewes (N = 6) and all had little or no ability to secrete oestradiol. However, basal and hCG-stimulated progesterone secretion was suppressed in the follicles from LHRH-immunized ewes. These results show that follicular development beyond 2·5 mm in the ewe is dependent on adequate stimulation by both LH and FSH.
PURPOSE: To determine whether participation in an intensive domestic violence interclerkship (DVI) improved the knowledge, attitudes, and skills of two successive cohorts of students at the University of Massachusetts Medical School. METHOD: The authors measured the knowledge, attitudes, and skills pertaining to domestic violence of third-year students in the classes of 1997 and 1998 using a validated written examination administered before, immediately after, and six months after participation in a 3.5-day or two-day DVI, respectively; they compared the scores using paired t-tests. Nine months after the DVI, the students' domestic violence screening skills were measured by a performance-based assessment (OSCE); using unpaired t-tests, the authors compared the OSCE scores with those of a previous third-year class that had not participated in a DVI. Immediately after the OSCE, the students reported their levels of confidence in domestic violence screening and their satisfaction with the domestic violence curriculum; using chi-square analysis, those self-reports were compared with those of the class with no DVI. RESULTS: The students who participated in the DVIs immediately and significantly improved their knowledge, attitudes, and skills (p < .001), and fully or partially sustained those improvements six months later (p < .001). Nine months after the DVI, the students performed domestic violence screening more effectively (p < .001), expressed greater comfort with domestic violence screening (p < .001), and felt better-prepared by the curriculum to address domestic violence issues (p < .001) than did the students with no DVI. CONCLUSION: Participation in a short, focused DVI curriculum produced sustainable improvements in knowledge, attitudes, and skills that were successfully applied by third-year medical students to effective domestic violence screening. Interclerkships are an effective way to fit into the clinical curriculum those subjects that transcend the traditional biomedical domain and intersect all areas of medical practice.
Abstract. To examine the effects of prolactin (Prl) and human chorionic gonadotrophin (hCG) on progesterone production by murine ovarian explants, immature female mice were injected with 4 IU pregnant mare's serum gonadotrophin (PMSG) to induce follicular maturation. After 24 or 40 h mice were killed, ovaries removed, cut into fragments and maintained as explants for 24 h in the presence or absence of ovine or human Prl (25–2500 ng/ml). None of these doses of Prl affected basal progesterone accumulation into media over 24 h. To determine if Prl could modify the capacity of ovarian explants to respond to gonadotrophin, ovaries were incubated with 25 IU/ml hCG for 3 h after an initial 24 h incubation period with or without Prl. Prl had no effect on basal progesterone accumulation but significantly enhanced hCG-stimulated progesterone accumulation during the 3 h incubation period. We conclude that Prl does not inhibit but may enhance progesterone secretion by pre-ovulatory follicles in the mouse.
