A Guide to Competencies, Educational Goals, and Learning Objectives for Teaching Medical Histology in an Undergraduate Medical Education Setting.

Horizontal and vertical integration within medical school curricula, truncated contact hours available to teach basic biomedical sciences, and diverse assessment methods have left histology educators searching for an answer to a fundamental question-what ensures competency for medical students in histology upon completion of medical school? The Liaison Committee for Medical Education (LCME) and the Commission on Osteopathic College Accreditation (COCA) advocate faculty to provide medical students with a list of learning objectives prior to any educational activities, regardless of pedagogy. It is encouraged that the learning objectives are constructed using higher-order and measurable action verbs to ensure student-centered learning and assessment. A survey of the literature indicates that there is paucity of knowledge about competencies, goals, and learning objectives appropriate for histology education in preclinical years. To address this challenge, an interactive online taskforce, comprising faculty from across the United States, was assembled. The outcome of this project was a desired set of competencies for medical students in histology with educational goals and learning objectives to achieve them.

Congenital Malformations Attributed to Prenatal Exposure to Cyclophosphamide.

Cyclophosphamide (CPA) remains one of the most widely prescribed anticancer drugs. It is also used in the treatment of rheumatoid arthritis, childhood nephrotic syndrome and systemic lupus erythematosus. It is a potent immunosuppressive agent. It is commonly used in blood and bone marrow transplantation. With the growing trend among women postponing childbearing, the number of women who are diagnosed with breast cancer is also increasing thus escalating the chances of exposure of the unborn child to antineoplastic drugs. A review of the literature provides strong evidence for the teratogenic effects on infants prenatally exposed to CPA. Both sporadic case reports and larger case series have demonstrated that babies with cyclophosphamide embryopathy are afflicted with intrauterine growth restriction, small for gestational age, and craniofacial malformations including eye anomalies, cleft/arched palate, hydrocephaly, micrognathia, low set microtia, hearing defects, craniosynostosis, and facial asymmetry. Also observed in these cases are limb defects such as radial, ulnar and tibial hypoplasia, club foot, digital defects of the hand and feet as well as vertebral fusion, brevicolis, and occasional Sprengel's deformity. These anomalies vary in consistency of occurrence and severity of the phenotype across cases and lack the specificity of thalidomide embryopathy or rubella embryopathy. However, they do occur is no longer in doubt. First trimester of pregnancy seems to be particularly susceptible to fetal malformations, although CPA effects on fetuses of later stages of gestation (hearing defects, growth restriction for example) are also reported occasionally. One of the major concerns from a mechanistic point of view is our inability to dissect the teratogenic effects of CPA from those of other drugs administered together with CPA as combination therapy. Animal experiments have been of particular value in that they are able to circumvent the numerous extraneous variables inherent to human case reports. They have also revealed the detrimental effects of CPA on gametes, preimplantation embryos, organogenesis as well as their potential teratogenic mechanisms. Of particular importance are the role of genetic polymorphisms, male mediated teratogenesis, ovarian failure, preimplantation embryo loss, epigenetic modifications, proxidant-antioxidant imbalance, autophagy, apoptosis, microRNAs and postclosure neural tube defects induced by CPA -all of which are areas for further research in CPA teratogenesis.

Experimental studies on cervical and lumbar ribs in mouse embryos.

In humans, the presence of cervical and lumbar ribs is of particular clinical significance. However, the relevance of their occurrence in the offspring of experimental animals in reproductive toxicologic studies is poorly understood. Maternal toxicity has been implicated in the etiology but conclusive evidence is lacking. The present study was undertaken to determine the incidence of supernumerary ribs (SNR) in mouse fetuses prenatally exposed to valproic acid (VPA) and retinoic acid (RA), and to compare their differential developmental susceptibility and morphological association with other axial skeletal anomalies. Single doses of valproic acid (VPA) or retinoic acid (RA) were administered to groups of mice on one of gestation days (GD) 7-12. Fetuses were collected on GD 18 and their skeletons examined for SNR. VPA treatment on GD 7 and GD 8 resulted in a high incidence of cervical and lumbar ribs, respectively. Cervical neural arch anomalies in the GD 7 group, and eight pairs of sternal ribs and seven sternebrae in the GD 8 group were observed in excess of the background SNR suggesting a direct effect of VPA on the developing mouse skeletal system. In the RA groups, GD 8-12 were susceptible for lumbar rib induction but increased incidence of cervical ribs was observed only from GD 9-12. Peak incidence of cervical ribs was found in the GD 10 and 11 groups and that of the lumbar ribs in the GD 8 and 11 groups. Although SNR incidence generally increased with increasing dose of RA, a strict dose-response relationship was lacking. Cervical arch anomalies were observed in as many embryos as those with cervical ribs, but eight pairs of sternal ribs and seven sternebrae did not correlate well with the lumbar ribs in the peak day groups. Interrupted cervical neural arches correlated well with lumbar ribs. The reduction in the frequency of presacral vertebrae from 26 to 25 in the VPA groups was limited to GD 7 (30%) and 8 (18%) groups. RA-induced reduction in presacral vertebral number extended to GD 9 and was greater in the GD 8 than in the GD 9 groups. Sternal anomalies occurred both in VPA and RA experiments and did not strictly correlate with the frequency of SNR. VPA had a narrow window of susceptibility, whereas RA effects on sternum extended from GD 9-12. The incidence of sternal anomalies generally increased with increasing dose and advancing developmental stage at which RA exposure occurred. These developmental susceptibility windows and associated malformations, when considered in the context of the ability of these drugs to induce alterations in gene expression in mouse embryos suggest that SNR are polygenic in origin and greatly influenced by environmental toxicants.