The impact of temperature on Ophthalmic Viscoelastic Devices and clinical implications - a pilot study: Temperature effect on Ophthalmic Viscoelastic Devices.

PURPOSE: To evaluate how temperature impacts the rheology of common Ophthalmic Viscoelastic Devices (OVDs) and clinical implications. SETTING: Tennent Institute of Ophthalmology, Glasgow, with Department of Mechanical and Aerospace Engineering, and Advanced Materials Research Laboratory, University of Strathclyde, Glasgow, UK. DESIGN: Laboratory pilot study. METHODS: The viscous and elastic responses of three OVDs (Eyefill-SC/Eyefill-C/Eyefill-HD; Bausch & Lomb) were measured using rotational and extensional rheometers at clinically relevant temperatures (5°C, 25°C, 37°C). Thermal properties were evaluated using differential scanning calorimetry and laser-flash analysis. RESULTS: The OVDs tested exhibited viscoelastic properties and shear-thinning behaviour. Apparent viscosities and relaxation time were higher at lower temperatures. The Eyefill-C and Eyefill-SC exhibited predominantly viscous character at low frequencies with a transition to predominantly elastic behaviour at high frequencies. An increase in temperature led to a decrease in relaxation time under shear and extension. At low frequencies, Eyefill-C and Eyefill-SC moduli increase with decreasing temperatures. Eyefill-HD at 25°C and 37°C displays two cross-over points, with the storage modulus dominating at low and high frequencies indicating a predominantly elastic behaviour. Thermal property analysis revealed Eyefill-C had the lowest thermal conductivity. CONCLUSIONS: This pilot study confirms our clinical experience that OVD properties are affected by low temperatures, with increased viscosities at low shear rates and higher relaxation times.Cold OVD can cause greater resistance to initiation of IOL injection system forces (compared to warmer OVD). Excessively forced injection using cold OVD could contribute to inadvertent cannula detachment if incorrectly assembled, or uncontrolled IOL release leading to avoidable injury.

Strategies to Broaden the Applications of Olive Biophenols Oleuropein and Hydroxytyrosol in Food Products.

Oleuropein (OLE) and hydroxytyrosol (HT) are olive-derived phenols recognised as health-promoting agents with antioxidant, anti-inflammatory, cardioprotective, antifungal, antimicrobial, and antitumor activities, providing a wide range of applications as functional food ingredients. HT is Generally Recognised as Safe (GRAS) by the European Food Safety Authority (EFSA) and the Food and Drug Administration (FDA), whereas OLE is included in EFSA daily consumptions recommendations, albeit there is no official GRAS status for its pure form. Their application in food, however, may be hindered by challenges such as degradation caused by processing conditions and undesired sensorial properties (e.g., the astringency of OLE). Among the strategies to overcome such setbacks, the encapsulation in delivery systems and the covalent and non-covalent complexation are highlighted in this review. Additionally, the synthesis of OLE and HT derivatives are studied to improve their applicability. All in all, more research needs however to be carried out to investigate the impact of these approaches on the sensory properties of the final food product and its percussions at the gastrointestinal level, as well as on bioactivity. At last limitations of these approaches at a scale of the food industry must also be considered.

Can we induce spermatogenesis in the domestic cat using an in vitro tissue culture approach?

The reduced number of animals in most wild felid populations implies a loss of genetic diversity. The death of juveniles, prior to the production of mature sperm, represents a loss of potential genetic contribution to future populations. Since 2011 mouse testicular organ culture has introduced an alternative mechanism to produce sperm in vitro from immature tissue. However, extension of this technology to other species has remained limited. We have used the domestic cat (Felis catus) as a model for wild felids to investigate spermatogenesis initiation and regulation, with the mouse serving as a control species. Testicular tissue fragments were cultured in control medium or medium supplemented with knockout serum replacement (KSR), AlbuMax, beta-estradiol or AlbuMax plus beta-estradiol. Contrary to expectations, and unlike results obtained in mouse controls, no germ cell differentiation could be detected. The only germ cells observed after six weeks of culture were spermatogonia regardless of the initial stage of tubule development in the donor tissue. Moreover, the number of spermatogonia decreased with time in culture in all media tested, especially in the medium supplemented with KSR, while AlbuMax had a slight protective effect. The combination of AlbuMax and beta-estradiol led to an increase in the area occupied by seminiferous tubules, and thus to an increase in total number of spermatogonial cells. Considering all the media combinations tested the stimulus for felid germ cell differentiation in this type of system seems to be different from the mouse. Studies using other triggers of differentiation and tissue survival factors should be performed to pursue this technology for the genetic diversity preservation in wild felids.