Visual pigment concentration and photoreceptor outer segment length in the human retina

Purpose: The Beer–Lambert law suggests that visual pigment optical density (OD) should be linearly related to the length of photoreceptor outer segments (POSs). Mammalian studies indicate that visual pigment concentration increases with POS length, but the nature of this relationship may vary due to factors such as visual pigment packing density or retinal eccentricity, and may not necessarily be linearly related. The purpose of this study was to establish the relationship between OD and POS length in humans. Methods: Spectral domain optical coherence tomography (OCT) was used to image POS, and imaging retinal densitometry (IRD) was used to measure OD at corresponding locations in 19 healthy participants (age range 25–82 years). POS length and OD measurements were extracted from OCT and IRD images at 23 discrete locations spanning the central 9° of the retina. The averaged data from all participants were fitted with models based on the Beer–Lambert law to establish the relationship between OD and POS length. Results: Visual pigment OD increased monotonically with POS length, but the relationship was non‐linear, and a straight‐line fit, based on a simple interpretation of the Beer–Lambert law, provided a poor description. A model allowing for different rod and cone visual pigment concentrations provided a superior fit. Specifically, the data were well described by a model where the molar concentration of visual pigment in cones and rods were 3.8 × 10−3 mol/L and 1.8 × 10−3mol/L, respectively. Conclusions: In accordance with the Beer–Lambert law, the results indicate that OD increases monotonically with POS length in humans, but the precise relationship is dependent on photoreceptor type. These results suggest that visual pigment concentration in rods is only about 48% of that found in cones. This may be due to the ubiquitous nature of artificial light that works to reduce the concentration of rhodopsin in rod photoreceptors

Abstracts of Scientifica 2022

This book contains the abstracts of the papers presented at Scientifica 2022, Organized by the Sancheti Institute College of Physiotherapy, Pune, Maharashtra, India, held on 12–13 March 2022. This conference helps bring researchers together across the globe on one platform to help benefit the young researchers. There were six invited talks from different fields of Physiotherapy and seven panel discussions including over thirty speakers across the globe which made the conference interesting due to the diversity of topics covered during the conference. Conference Title:  Scientifica 2022Conference Date: 12–13 March 2022Conference Location: Sancheti Institute College of PhysiotherapyConference Organizer: Sancheti Institute College of Physiotherapy, Pune, Maharashtra, Indi

Pharmapolymers in the 21st century: Synthetic polymers in drug delivery applications

The administration of drugs, as a main challenge of pharmaceutical and medicinal applications, has certainly benefited from the application of synthetic polymers. However, despite an enormous effort to develop new materials for drug delivery applications, only few of them have entered the market due to the hurdles of regulation, production, cost efficiency and both industrial's and patients' acceptance. In this review, we summarize all these classes of synthetic polymers, which are on the market as well as the latest developments in clinical trials, and describe their application in polymer-drug conjugates, as excipients, in nano-/microscopic and macroscopic drug carriers, as polymeric coatings, or as polymeric drugs. Our intention is to create a link between the underlying chemical structures, the properties of the polymers, and their area of application, where they are often just known by their trade names or abbreviations. In addition selected types of synthetic polymers are highlighted that feature interesting properties and have the potential to make it to the market in future. (C) 2018 Elsevier B.V. All rights reserved

Analysis of Outcomes in Ischemic vs Nonischemic Cardiomyopathy in Patients With Atrial Fibrillation A Report From the GARFIELD-AF Registry

IMPORTANCE Congestive heart failure (CHF) is commonly associated with nonvalvular atrial fibrillation (AF), and their combination may affect treatment strategies and outcomes