Noninvasive,In Vivo Assessment of Mouse Retinal Structure Using Optical Coherence Tomography

Background

Optical coherence tomography (OCT) is a novel method of retinal in vivo imaging. In this study, we assessed the potential of OCT to yield histology-analogue sections in mouse models of retinal degeneration.

Methodology/Principal Findings

We achieved to adapt a commercial 3^rd generation OCT system to obtain and quantify high-resolution morphological sections of the mouse retina which so far required in vitro histology. OCT and histology were compared in models with developmental defects, light damage, and inherited retinal degenerations. In conditional knockout mice deficient in retinal retinoblastoma protein Rb, the gradient of Cre expression from center to periphery, leading to a gradual reduction of retinal thickness, was clearly visible and well topographically quantifiable. In Nrl knockout mice, the layer involvement in the formation of rosette-like structures was similarly clear as in histology. OCT examination of focal light damage, well demarcated by the autofluorescence pattern, revealed a practically complete loss of photoreceptors with preservation of inner retinal layers, but also more subtle changes like edema formation. In Crb1 knockout mice (a model for Leber''s congenital amaurosis), retinal vessels slipping through the outer nuclear layer towards the retinal pigment epithelium (RPE) due to the lack of adhesion in the subapical region of the photoreceptor inner segments could be well identified.

Conclusions/Significance

We found that with the OCT we were able to detect and analyze a wide range of mouse retinal pathology, and the results compared well to histological sections. In addition, the technique allows to follow individual animals over time, thereby reducing the numbers of study animals needed, and to assess dynamic processes like edema formation. The results clearly indicate that OCT has the potential to revolutionize the future design of respective short- and long-term studies, as well as the preclinical assessment of therapeutic strategies.     

Preterm birth makes the immature intestine sensitive to feeding-induced intestinal atrophy

Preterm birth and formula feeding predispose to small intestinal dysfunction, which may lead to necrotizing enterocolitis (NEC). In piglets, we tested whether the physiological and environmental transitions occurring at birth affect the response of the immature intestine to enteral feeding. Pig fetuses (106 days gestation, term = 115 days) were prepared with esophageal feeding tubes and fed either sow's colostrum (n = 8) or infant formula (n = 7) in utero. After 24 h of oral feeding, the pig fetuses were delivered by cesarean section and their gastrointestinal morphology and function were compared with those of preterm newborn (NB) littermates that were not fed (n = 8) or fed colostrum (n = 7) or formula (n = 13) for 24 h after birth. Before birth, both colostrum and formula feeding resulted in marked increases in intestinal mass, brush-border enzyme activities, and plasma glucagon-like peptide 2 concentrations, to levels similar to those in NB colostrum-fed piglets. In contrast, NB formula-fed piglets showed reduced intestinal growth, decreased brush-border enzyme activities, and intestinal lesions, reflecting NEC. NB formula-fed pigs also showed impaired enterocyte endocytotic function and decreased antioxidative capacity, whereas brush-border enzyme mRNA levels were unaltered, relative to NB colostrum-fed pigs. Our results indicate that the feeding-induced growth and enzyme maturation of the immature intestine are not birth dependent. However, with a suboptimal diet (milk formula), factors related to preterm birth (e.g., microbial colonization and metabolic and endocrine changes) make the immature intestine sensitive to atrophy and development of NEC.     

The hypothalamic arcuate nucleus: a key site for mediating leptin's effects on glucose homeostasis and locomotor activity

Leptin is required for normal energy and glucose homeostasis. The hypothalamic arcuate nucleus (ARH) has been proposed as an important site of leptin action. To assess the physiological significance of leptin signaling in the ARH, we used mice homozygous for a FLPe-reactivatable, leptin receptor null allele (Lepr(neo/neo) mice). Similar to Lepr(db/db) mice, these mice are obese, hyperglycemic, hyperinsulinemic, infertile, and hypoactive. To selectively restore leptin signaling in the ARH, we generated an adeno-associated virus expressing FLPe-recombinase, which was delivered unilaterally into the hypothalamus using stereotaxic injections. We found that unilateral restoration of leptin signaling in the ARH of Lepr(neo/neo) mice leads to a modest decrease in body weight and food intake. In contrast, unilateral reactivation markedly improved hyperinsulinemia and normalized blood glucose levels and locomotor activity. These data demonstrate that leptin signaling in the ARH is sufficient for mediating leptin's effects on glucose homeostasis and locomotor activity.     

Variation in growth,yield and protein concentration in <Emphasis Type="Italic">Saccharina latissima</Emphasis> (Laminariales,Phaeophyceae) cultivated with different wave and current exposures in the Faroe Islands

Ropes seeded directly with Saccharina latissima were deployed at different exposures (sheltered, current exposed and wave exposed) in a Faroese sound and characteristics of growth and quality of the biomass and surroundings were evaluated during the growth season from March to August 2015. Saccharina latissima individuals cultivated at the current exposed location were heavier compared to the individuals cultivated at the other locations; however, the total biomass yield was significantly lower at the current exposed location. The protein and nutritional value of the biomass varied with season but showed no correlation with exposure. The highest protein levels and EAA (essential amino acid) score were measured in the spring (April and May) samples. The amino acid composition was dominated by glutamate followed by aspartic acid; however, this was replaced by methionine in the July samples. Total Kjeldahl nitrogen was significantly higher in May and August compared to July, and the nitrate concentration in the biomass was significantly lower in May and August compared to July. Nitrate was most available in the seawater at the time of deployment (3rd of March) and decreased during spring and summer. Saccharina latissima was cultivated successfully at the sheltered, current exposed and wave exposed locations using a direct seeding method. However, our results indicate that the lower biomass yield at the current exposed cultivation location compared to the sheltered and wave exposed are due to the direct seeding method, and possible limitations using this method need further testing and optimization.     

Identifying the risk regions of house break‐ins caused by Tibetan brown bears (Ursus arctos pruinosus) in the Sanjiangyuan region,China

Damage to homesteads by brown bears (Ursus arctos) has become commonplace in Asia, Europe, and the Americas. Science‐based solutions for preventing damages can contribute to the establishment of mechanisms that promote human–bear coexistence. We examined the spatial distribution patterns of house break‐ins by Tibetan brown bears (U. a. pruinosus) in Zhiduo County of the Sanjiangyuan region in China. Occurrence points of bear damage were collected from field surveys completed from 2017 to 2019. The maximum entropy (MaxEnt) model was then used to assess house break‐in risk. Circuit theory modeling was used to simulate risk diffusion paths based on the risk map generated from our MaxEnt model. The results showed that (a) the total risk area of house break‐ins caused by brown bears was 11,577.91 km², accounting for 29.85% of Zhiduo County, with most of the risk areas were distributed in Sanjiangyuan National Park, accounting for 58.31% of the total risk area; (b) regions of alpine meadow located in Sanjiangyuan National Park with a high human population density were associated with higher risk; (c) risk diffusion paths extended southeast to northwest, connecting the inside of Sanjiangyuan National Park to its outside border; and (d) eastern Suojia, southern Zhahe, eastern Duocai, and southern Jiajiboluo had more risk diffusion paths than other areas examined, indicating higher risk for brown bear break‐ins in these areas. Risk diffusion paths will need strong conservation management to facilitate migration and gene flow of brown bears and to alleviate bear damage, and implementation of compensation schemes may be necessary in risk areas to offset financial burdens. Our analytical methods can be applied to conflict reduction efforts and wildlife conservation planning across the Qinghai–Tibet Plateau.     

Understanding the evolution of the windlass mechanism of the human foot from comparative anatomy: Insights,obstacles, and future directions

Humans stand alone from other primates in that we propel our bodies forward on a relatively stiff and arched foot and do so by employing an anatomical arrangement of bones and ligaments in the foot that can operate like a “windlass.” This is a significant evolutionary innovation, but it is currently unknown when during hominin evolution this mechanism developed and within what genera or species it originated. The presence of recently discovered fossils along with novel research in the past two decades have improved our understanding of foot mechanics in humans and other apes, making it possible to consider this question more fully. Here we review the main elements thought to be involved in the production of an effective, modern human‐like windlass mechanism. These elements are the triceps surae, plantar aponeurosis, medial longitudinal arch, and metatarsophalangeal joints. We discuss what is presently known about the evolution of these features and the challenges associated with identifying each of these specific components and/or their function in living and extinct primates for the purpose of predicting the presence of the windlass mechanism in our ancestors. In some cases we recommend alternative pathways for inferring foot mechanics and for testing the hypothesis that the windlass mechanism evolved to increase the speed and energetic efficiency of bipedal gait in hominins. Am J Phys Anthropol 156:1–10, 2015 © 2014 Wiley Periodicals, Inc.     

The discovery of UK-369003, a novel PDE5 inhibitor with the potential for oral bioavailability and dose-proportional pharmacokinetics

This paper describes our recent efforts to design and synthesise potent and selective PDE5 inhibitors and the use of in vitro predictors of clearance, absorption and permeability to maximise the potential for dose-proportional pharmacokinetics and good oral bioavailability in man. Optimisation of the preclinical profile resulted in the identification of UK-369003 (19a) and its nomination as a clinical candidate. The clinical pharmacokinetic and safety profile has enabled us to progress the compound to test its efficacy in patients with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) and a paper describing its efficacy has recently been published.