Medroxyprogesterone acetate in reindeer bulls: testes histology, cfos activity in the brain, breeding success, and semen quality.

A previous study reported that a 400-mg dose of medroxyprogesterone acetate (MPA) reduced male reindeer aggression and blocked development of secondary sexual characteristics but did not completely impair fertility. Here we have repeated that protocol in two separate trials. In 2017, tissues and blood samples, collected from MPA and control (CTL) reindeer bulls, euthanized at 30 and 60 d post-treatment were used to evaluate testes histology and morphometrics, cfos activity in the brain and androgen levels. While testes weight tended to decline from August to September in both groups, indices of spermatogenesis remained high. By September, indices of spermatogenesis were declining in both groups with sperm density lower (P = 0.05) in MPA compared to CTL bulls. Aug CTL bulls had the highest concentrations of androstenedione (A4) (P = 0.009) and testosterone (T) (P = 0.08), whereas these androgens were baseline in Aug MPA bulls. By September, A4 and T levels in CTL bulls declined to levels measured in MPA bulls. Cfos activity had a greater number (P = 0.02) of cfos positive neurons in the central amygdala in MPA compared to CTL bulls, suggesting a heightened fear response among the MPA bulls. In the second trial (2019), MPA-treated bulls, with (E, n = 4) and without (IE, n = 4) breeding experience, were blood sampled at key points from July through September when they were put in individual harems with estrous-synchronized cows. Concentrations of T were greatest (P < 0.001) among E bulls prior to MPA treatment but 1 mo after treatment, both T and A4 were baseline in all eight reindeer. Semen collected by electroejaculation at 60 d post-MPA treatment revealed only minor differences in sperm abnormalities between E and IE bulls using both fresh and frozen/thawed semen. Only three bulls (2 E and 1 IE) sired offspring. Breeding success was not related to previous breeding experience, body weight, or bull age. The failure of some MPA bulls to breed appears to be a behavioral, not a physiological, limitation. Limited application of MPA is clearly a useful tool for managing rut-aggression in non-breeding reindeer. However, the possibility that semen could be collected from MPA-treated bulls using restraint and mild sedation rather than general anesthesia should be investigated. This could improve the quality of semen collection while enhancing the safety of both handlers and animals.

A single 400 mg dose of MPA given to reindeer bulls just before the onset of rut eliminates aggressive behavior and suppresses androgen concentrations without dramatic differences in the gross or histological structure of the testes within the first 30 d of treatment. By 60 d post-treatment, there is evidence of smaller testes size and decreased sperm density in treated bulls. However, if given the opportunity, some treated bulls can still successfully breed. Breeding success in MPA bulls was not solely related to previous breeding experience, body weight, or bull age. Androgen concentrations and semen characteristics did not vary with previous breeding experience. Failure of some treated bulls to breed appears to be a behavioral limitation. Differences in brain activity between control and treated bulls were few except for increased cfos activity in the central amygdala of MPA bulls, potentially increasing the fear response in these reindeer.

Design principles for effective video-based professional development.

BACKGROUND: Most studies of teacher professional development (PD) do not rigorously test impact on teaching practice and student learning. This makes it difficult to define what is truly "effective." The Science Teachers Learning from Lesson Analysis (STeLLA) PD program, in contrast, was studied in a cluster randomized experimental design that examined impact on teaching practice and student learning. The STeLLA video-based PD (VbPD) program demonstrated significant impact, with high effect sizes, on elementary teachers' science teaching practice and their students' learning. Previously published reports provide details about research methods and findings but only broad sketches of the STeLLA program design and implementation. Deeper explorations of the STeLLA design principles can contribute evidence-based knowledge about the features of effective PD and enrich the existing but limited consensus model of effective PD. This article addresses the following questions:What design principles guided the development, implementation, leadership, and scaling up of a video-based PD program that had significant impact on student learning?What do the STeLLA design principles contribute to the existing knowledge base about effective video-based PD? RESULTS: Results from rigorous studies of the STeLLA program are summarized in this paper; details are reported elsewhere and included here as supplementary materials. This article is not a standard research results paper but instead describes the design principles guiding the development, implementation, leadership, and scaling up of the STeLLA VbPD program. CONCLUSIONS: The authors argue that this set of design principles is powerful for four reasons: 1) its demonstrated impact on teaching practice and student learning, 2) its strong theoretical and research foundations, 3) the stability and usefulness of the design principles as implemented in changing contexts over a 10-year period, and 4) the coherence and interconnectedness of the principles. The STeLLA VbPD design principles contribute to the field by empirically supporting and advancing the existing consensus model of effective PD. Further study can build on this effort to strengthen our understanding of effective PD based on evidence of impact on teaching practice and student learning.

Beginning the discussion of commercialism in dentistry.

There is increasing concern over commercialism in dentistry. Multiple factors contribute to this trend, which has the potential for fragmenting the profession, exacerbating the access issue, and eroding the public's confidence in dentistry. There are both positive and negative aspects of commercialism. Positive approaches for promoting oral health in the face of commercialism hold the greatest promise. The core theme in the recommendations from Ethics Summit on Commercialism is that competent, comprehensive, and continuous oral health care is appropriate and should be promoted to the American public.

Dental education: a leadership challenge for dental educators and practitioners.

By all outward signs, the dental profession is prospering. However, signs of a looming crisis in dental education threaten the future effectiveness of the profession. Transforming dental education through the application of principles espoused by the ADEA Commission on Change and Innovation in Dental Education (CCI) is essential for securing the future of the profession. To meet the future oral health needs of the public, dental schools must retain their research mission and prepare students for evidence-based practice. To accomplish this, both the curricular content and the environment and approach to dental education must change. Besides the knowledge and abilities needed to care for a more diverse and aging population, future practitioners must possess tools needed to thrive in the world of small business and have the ethical foundation to conduct themselves as responsible professionals. Ensuring the future of the profession is a leadership challenge to be shared by both dental educators and practitioners.