Cod Liver Oil,but Not Retinoic Acid,Treatment Restores Bone Thickness in a Vitamin A-Deficient Rat

Vitamin A plays a prominent role for maintaining optimal bone status, but its impact upon the bone in response to vitamin A deficiency is not well defined. The purpose of this study was to evaluate how replenishing vitamin A by either whole food cod liver oil (COD) or the active metabolite of vitamin A, retinoic acid (RA), altered bone thickness of vitamin A-deficient (VAD) rats. Weanling rats were administered a control diet (CTRL) or VAD diet for 9 weeks. This was followed by four weeks of treatment in which the VAD group was divided into the following 4 subgroups: (1) VAD (9 weeks)-VAD (4 weeks); (2) VAD-CTRL; (3) VAD-COD; and (4) VAD-RA. Compared to controls, VAD rats had thicker bones which showed marked dysplasia. VAD-rats treated with COD produced a thinner bone that was not significantly different from that of untreated rats. In contrast, RA did not significantly change the thicker bone, and also had significantly greater periosteal and endosteal osteoblast numbers compared to VAD-COD. Active osteoclasts were not detected in VAD rats, nor during the treatment period. These findings suggest that the abnormal bone thickness in VAD rats appears to be more effectively restored to bone thickness of untreated control rats when treated with COD.     

Medical genetics and genomics training in obstetrics and gynecology residencies: are we ready for the future?*

Objective: The primary objective of this study is to evaluate the availability and duration of formal medical genetics and genomics (MGG) education during obstetrics and gynecology (OB/GYN) residency training in the United States compared to other noncore OB/GYN rotations.

Methods: We performed a review of rotation schedules published in all American Council for Graduate Medical Education (ACGME)-accredited OB/GYN residency programs’ websites during the month of December 2016. Information regarding availability and duration of MGG rotation and other noncore OB/GYN rotations (ultrasound, breast health, and family planning) were collected.

Results: Among 256 ACGME-accredited OB/GYN residency programs, rotation schedule was available for 238 (93%). Only 34 programs (14.3%) had some form of MGG rotations. In the GLM, when compared to other noncore OB/GYN rotations, the mean duration of MGG rotation was significantly less than ultrasound (0.07 versus 0.57 months, p?p?Conclusions: Despite the growing importance of MGG in day-to-day OB/GYN practice, only a limited number of ACGME-accredited OB/GYN residency programs offer an MGG rotation. When compared to other noncore OB/GYN rotations, such as, ultrasound and family planning, any MGG rotation was significantly shorter. With clear evidence that MGG will continue to radically change practice of OB/GYN in the future, it is imperative that steps need to be taken to address this deficiency in training.     

Fetoplacental regional variations in the expression of angiopoietin-1, angiopoietin-2, and Tie2 in normal-term and near-term pregnancies

Background: Angiopoietin-1 (Ang1), angiopoietin-2 (Ang2), and the receptor tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) are known to be involved in fetoplacental angiogenesis adequacy, which is a primary determinant of fetal growth. Regional variations in Ang1, Ang2, and Tie2 remain unknown, although fetoplacental vascularity and gene expressions differ between the placental center and the periphery.

Objective: The aim of this study was to test the hypothesis that there are regional variations in the expression of these angiopoietins in human placentas from uncomplicated term and near term pregnancies.

Study design: In this prospective study, central and peripheral samples were collected from fresh placentas from normal-term and near-term pregnancies delivered by Cesarean section (n?=?7, 36–41 week gestation) prior to the onset of labor. Regional differences in Ang1, Ang2, and Tie2 protein expressions were measured by Western blot and densitometric analyses with b-actin normalization, and their fetoplacental regional localization assessed by immunohistochemistry. The Ang1 and Ang2 ratios at central and peripheral sites were determined. Statistical analysis was performed using Student’s t-test.

Results: Ang1 protein expression was higher in the placental periphery than in the center (2.48?±?0.42 versus 1.74?±?0.27, p?=?0.01). In contrast, Ang2 protein expression was greater in the placental center than in the periphery (10.10?±?1.82 versus 7.15?±?1.12, respectively, p?=?0.03). The Ang1–Ang2 ratio reflected these differential expressions. Tie2 protein expression was higher in the placental periphery than in the center (0.21?±?0.02 versus 0.16?±?0.02, p?=?0.003). The immunoreactivity of Ang1 and Tie2 was stronger in the periphery than in the center, and that of Ang2 was stronger in the center than in the periphery.

Conclusions: Ang1, Ang2, and Tie2 are differentially expressed in placental center and periphery. Ang1/Ang2 ratio reflects this regional variation in the angiogenic balance that has implications for fetoplacental villous angiogenesis. The results also demonstrate the importance of considering the location of placental sampling sites for any future investigations of fetoplacental villous angiogenesis.     

Fat embolism: Evolution of histopathological changes in the rat lung

The pathophysiology of Fat Embolism Syndrome (FES) is poorly understood and subject to some controversy. Evaluation of the evolution of histological changes in the lungs of patients with FES is impractical. The current theories of FES were established through acute clinical observations and acute animal experiments, but sequential changes in the histology of lungs over a prolonged period have not been made. The progressive effects of fat embolization of the lungs were examined in a rat model over a period of 11 days. Triolein, a major bone marrow fat, was administered to conscious Sprague‐Dawley rats via the caudal vein. Rats were euthanized at 24, 48, 96 h, and 11 days, but some died within a few hours. Histomorphometric evaluations of lung tissue were made, including stains for fat, collagen, and smooth muscle actin. Arterial and arteriolar patency decreased progressively up to 96 h, but returned toward normal after 11 days. A striking finding was the very early presence of inflammation and fibrosis after only several hours, persisting up to 11 days. The results of this study provide evidence of both very early and prolonged changes due to fat embolization. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:191–197, 2010