Central nervous system malformations induced by triamcinolone acetonide in nonhuman primates: pathology

Diabetic retinopathy in pregnancy - A review

Diabetes and gestational diabetes (GD) are areas of concern worldwide. GD can eventually lead to serious development of diabetic retinopathy (DR) during pregnancy or worsening of an already existing DR. GD confers future risk of diabetes, both in the mother and fetus, further complicating their lives. DR in pregnant women has been intriguing in terms of understanding the prevalence, assessing risk factors causing pathogenesis, and problems associated with treating them. Pregnancy itself is a risk factor for progression of DR. Physiological changes such as metabolic, vascular, immunologic, and hormonal changes that occur during pregnancy can cause development as well as worsening of DR. This can eventually lead to permanent visual loss if not addressed on time. Timing of laser, choice of treatment for diabetic macular edema with laser, intravitreal anti-vascular endothelial growth factor agents (VEGF), and intravitreal steroids pose a serious challenge in managing these patients without causing damage to the mother and fetus. This review article showcases the prevalence, risk factors, and pathogenesis, outlines the management of DR in pregnancy, and recommends guidelines based on the available evidence. PubMed and MEDLINE searches were performed pertaining to the prevalence of GD in India, DR in pregnancy, risk factors for progression of DR, role of vasoactive mediators in DR, role of angiopoietic factors in DR, hormonal influence of DR, role of growth factors in DR, use of fluorescein and indocyanine green angiography, retinal lasers, anti-VEGF agents, intravitreal steroids, anesthesia, and retinal surgery, all pertaining to pregnancy and guidelines and recommendations for managing DR in pregnancy.

Adverse event following live attenuated chikungunya vaccine in a cynomolgus macaque with pre-existing chronic hydrocephalus

A cynomolgus macaque (Macaca fascicularis) with a pre-existing, undiagnosed, subclinical but severe cerebral hydrocephalus was enrolled in a study of long-term immunogenicity of the IRES/CHIK vaccine. The animal began showing signs of neurological dysfunction post-vaccination, which progressed and ultimately resulted in euthanasia. The underlying brain abnormality was revealed at necropsy and was subsequently investigated with gross and microscopic examination. This becomes the first reported case of an adverse event following administration of a live attenuated vaccine and suggests the possibility of an increased susceptibility risk of unwanted adverse outcome associated with vaccination in populations with pre-existing conditions such as hydrocephalus.

Expanding the test set: Chemicals with potential to disrupt mammalian brain development

High-throughput test methods including molecular, cellular, and alternative species-based assays that examine critical events of normal brain development are being developed for detection of developmental neurotoxicants. As new assays are developed, a "training set" of chemicals is used to evaluate the relevance of individual assays for specific endpoints. Different training sets are necessary for each assay that would comprise a developmental neurotoxicity test battery. In contrast, evaluation of the predictive ability of a comprehensive test battery requires a set of chemicals that have been shown to alter brain development after in vivo exposure ("test set"). Because only a small number of substances have been well documented to alter human neurodevelopment, we have proposed an expanded test set that includes chemicals demonstrated to adversely affect neurodevelopment in animals. To compile a list of potential developmental neurotoxicants, a literature review of compounds that have been examined for effects on the developing nervous system was conducted. The search was limited to mammalian studies published in the peer-reviewed literature and regulatory studies submitted to the U.S. EPA. The definition of developmental neurotoxicity encompassed changes in behavior, brain morphology, and neurochemistry after gestational or lactational exposure. Reports that indicated developmental neurotoxicity was observed only at doses that resulted in significant maternal toxicity or were lethal to the fetus or offspring were not considered. As a basic indication of reproducibility, we only included a chemical if data on its developmental neurotoxicity were available from more than one laboratory (defined as studies originating from laboratories with a different senior investigator). Evidence from human studies was included when available. Approximately 100 developmental neurotoxicity test set chemicals were identified, with 22% having evidence in humans.

Chronic maternal methanol inhalation in nonhuman primates (Macaca fascicularis): reproductive performance and birth outcome

The present study was designed to characterize maternal reproductive performance and early offspring effects following exposure to methanol (MeOH) vapor in a nonhuman primate model. The two-cohort study design used 48 adult female Macaca fascicularis (24/cohort) monkeys exposed to 0, 200, 600, or 1800 ppm MeOH vapor for approximately 2.5 h/day, 7 days/week prior to breeding and throughout pregnancy. Maternal body weight measurement, clinical observations and health assessments were conducted routinely throughout the study. Menstrual cyclicity was monitored during the pre-breeding and breeding periods and timed matings were conducted with nonexposed males. Females were monitored closely during the last month of pregnancy. At birth, infant physical characteristics were measured and a newborn health assessment was conducted. Methanol exposure did not alter menstrual cycles, the number of breedings to conception or conception rate. A total of 34 live-born infants were delivered (control=8, 200 ppm=9, 600 ppm=8, 1800 ppm=9). One female each in the control and 600-ppm group delivered a stillborn infant and a cesarean section (C-section) was required to deliver a hydrocephalic infant who died in utero in the maternal 1800-ppm group. Although not statistically significant, five MeOH-exposed females were C-sectioned due to pregnancy complications such as uterine bleeding and prolonged unproductive labor. These complications were not observed in the control group. The mean length of pregnancy in the MeOH-exposed groups was significantly decreased by 6 to 8 days when compared to controls. There were no MeOH-related effects on offspring birthweight or newborn health status. The consistent reduction in length of pregnancy observed in the MeOH females may reflect a treatment effect on the fetal neuroendocrine system. Given that the fetal hypothalamic--pituitary-adrenal axis controls pregnancy length in most species, these results suggest a modest but significant effect of MeOH on the biochemical events that control the timing of birth.