Molecular and cellular mechanisms of ultraviolet corneal crosslinking

In the presented mainly experimental work, the regularities and mechanisms of ultrastructural transformation and changes in corneal metabolism under ultraviolet exposure are established. High-quality saturation of the stroma with riboflavin is necessary to perform safe and effective UV crosslinking of the cornea, which can be achieved mainly due to a sufficient area of de-epithelization (at least 8-9 mm). It was found that UV crosslinking of the cornea with the use of developed riboflavin solutions (Dextralink, Ribolink and Khitolink) as photosensitizers increases its strength properties associated with changes in the structural state of collagen fibrils. It is proved that the riboflavin-UV effect on the optical shell of the eyeball is caused by a short-term local increase in free radical processes, a decrease in the overall antioxidant status, and the absence of necrotic and significant inflammatory reactions. It is shown that the lack of riboflavin in the stroma forms a cascade of pathomorphological events of an irreversible nature, leading to the loss of the native structure of the cornea. On the basis of the conducted studies, the necessity of a differentiated approach to the use of riboflavin-containing solutions during ultraviolet crosslinking of the cornea is justified. Key words: ultraviolet corneal crosslinking, molecular-cellular mechanisms, photosensitizers, riboflavin.

The Effect of UV Irradiation on Tensile Strength of Polypropylene Reinforced Kenaf Fiber and Peat Soil

Nowadays, natural fiber polymer composites have been widely used in many industries and applications because of their low cost, renewable and eco–friendly. However, exposing this material to the outdoor environment will affect the material properties as it is exposed to various situations such as ultraviolet exposure, raining, etc. This paper studies the degradation of kenaf fiber, polypropylene strengthened with peat soil combustion at 600ºC upon ultraviolet exposure. The wood–plastic composites (WPCs) produced into two batches, kenaf fiber mixing with polypropylene and kenaf fiber and peat soil mixing with polypropylene. All the specimen has exposed in ultraviolet (UV) irradiation at 0 hour, 100 hours, and 200 hours, respectively. The UV irradiation accelerated weathering tester machine was conducting the water spray cycle, which is 4 hours of water spray and 8 hours without water spray continuously until achieved the target time. The finding obtained from the tensile test, the composition with the highest contain of kenaf fiber in a polymer composite, has the lowest tensile strength after exposed with 200 hours of UV irradiation, which is 20.23 MPa. While the adding peat soil as reinforcement has shown the increasing the percentage of tensile strength after 200 UV exposure.

Assessment of Shellac and Lemongrass Oil Blend as Edible Coating to Prolong Shelf Life of Pili Nut (Canarium ovatum)

Shelf life in ground and tree nuts are often assessed based on aesthetic appearance, nut integrity, color and most importantly, taste and edibleness. Nuts with considerable level of rancidity and free fatty acids due to degradation of oils indicate expiration or decay. We prepared a shellac-lemongrass oil blend coating using food-grade ingredients and assessed its potential to extend shelf life of Pili nut (Canarium ovatum) kernels. A glossy, hard but considerably brittle coating for the pili kernels were prepared with varying numbers of layers. On average, the mass of coating added per dip is 0.10 g, and the thickness of 5-layers of coating is 0.3 mm. The obtained reflectance spectra of the coated pili kernels implied the translucent nature of the coating, but becomes opaque as the number of layers are increased. Peroxide value (PV) and free fatty acid value (FFAV), were also measured at 10 days after application of coating. PV was lowest in the nuts with 5 coating layers, while this treatment did not reduce FFAV. These results indicate the effectiveness of our coatings in preventing peroxide production probably by blocking oxygen penetration and ultraviolet exposure, which are important triggers production of peroxide and other free radicals. Further tests and time-series experiments are planned to assess the dynamics of peroxide levels and the overall potential of our coating technology for Pili nut.

Bringing Light into Darkness—Comparison of Different Personal Dosimeters for Assessment of Solar Ultraviolet Exposure

(1) Measuring personal exposure to solar ultraviolet radiation (UVR) poses a major challenges for researchers. Often, the study design determines the measuring devices that can be used, be it the duration of measurements or size restrictions on different body parts. It is therefore of great importance that measuring devices produce comparable results despite technical differences and modes of operation. Particularly when measurement results from different studies dealing with personal UV exposure are to be compared with each other, the need for intercomparability and intercalibration factors between different measurement systems becomes significant. (2) Three commonly used dosimeter types—(polysulphone film (PSF), biological, and electronic dosimeters)—were selected to perform intercalibration measurements. They differ in measurement principle and sensitivity, measurement accuracy, and susceptibility to inaccuracies. The aim was to derive intercalibration factors for these dosimeter types. (3) While a calibration factor between PSF and electronic dosimeters of about 1.3 could be derived for direct irradiation of the dosimeters, this was not the case for larger angles of incidence of solar radiation with increasing fractions of diffuse irradiation. Electronic dosimeters show small standard deviation across all measurements. For biological dosimeters, no intercalibration factor could be found with respect to PSF and electronic dosimeters. In a use case, the relation between steady-state measurements and personal measurements was studied. On average, persons acquired only a small fraction of the ambient radiation.

Mucocutaneous Squamous Cell Carcinoma in a Yucatan Minipig

Minipigs are commonly utilized in dermal toxicology studies, necessitating documentation of background findings, including neoplastic lesions. We describe a case of a Yucatan minipig with a squamous cell carcinoma at the mucocutaneous junction of the lip. The neoplasm appeared grossly as a slightly raised area of skin with ulceration. Histologically, there were nests and trabeculae of neoplastic squamous epithelial cells undergoing keratinization. Multifocally, rafts of these cells were within lymphatic vessels. Squamous cell carcinoma has not previously been reported in Yucatan or other laboratory minipigs, however, has been reported uncommonly in nonlaboratory pot-bellied pigs. Although squamous cell carcinoma has been associated with ultraviolet exposure or papillomavirus in various species, this was unable to be confirmed in this case.

Behind the Scene: Exploiting MC1R in Skin Cancer Risk and Prevention

Melanoma and non-melanoma skin cancers (NMSCs) are the most frequent cancers of the skin in white populations. An increased risk in the development of skin cancers has been associated with the combination of several environmental factors (i.e., ultraviolet exposure) and genetic background, including melanocortin-1 receptor (MC1R) status. In the last few years, advances in the diagnosis of skin cancers provided a great impact on clinical practice. Despite these advances, NMSCs are still the most common malignancy in humans and melanoma still shows a rising incidence and a poor prognosis when diagnosed at an advanced stage. Efforts are required to underlie the genetic and clinical heterogeneity of melanoma and NMSCs, leading to an optimization of the management of affected patients. The clinical implications of the impact of germline MC1R variants in melanoma and NMSCs’ risk, together with the additional risk conferred by somatic mutations in other peculiar genes, as well as the role of MC1R screening in skin cancers’ prevention will be addressed in the current review.