Irradiation with 365 nm and 405 nm wavelength shows differences in DNA damage of swine pancreatic islets

INTRODUCTION

3D printing is being used more extensively in modern biomedicine. One of the problems is selecting a proper crosslinking method of bioprinted material. Amongst currently used techniques we can distinguish: physical crosslinking (e.g. Ca2+ and Sr2+) and chemical crosslinking-the UV light crosslinking causing the biggest discussion. UV radiation is selectively absorbed by DNA, mainly in the UV-B region but also (to some extent) in UV-A and UV-C regions. DNA excitement results in typical photoproducts. The amount of strand breaks may vary depending on the period of exposition, it can also differ when cells undergo incubation after radiation.

AIM

The aim of this study was to show whether and how the time of irradiation with 405 nm and 365 nm wavelengths affect DNA damage in cell lines and micro-organs (pancreatic islets).

MATERIALS AND METHODS

The degree of DNA damage caused by different wavelengths of radiation (405 nm and 365 nm) was evaluated by a comet assay. The test was performed on fibroblasts, alpha cells, beta cells and porcine pancreatic islets after 24 hours incubation period. Samples without radiation treatment were selected as a control group. Results analysis consisted of determining the percent of cells with damaged DNA and the tail intensity evaluation.

RESULTS

The degree of DNA damage in pancreatic islets after exposure to 405 nm wavelength oscillated between 2% and 6% depending on the tested time period (10 - 300 seconds). However, treating islets using 365 nm wavelength resulted in damage up to 50%. This clearly shows significantly less damage when using 405 nm wavelength. Similar results were obtained for the tested cell lines.

CONCLUSIONS

Crosslinking with 405 nm is better for pancreatic islets than crosslinking with 365 nm UV light.

Observations of mineralised tissues of teeth in X-ray micro-computed tomography

BACKGROUND

The one of the most recent imaging technology is X-ray microtomography which allows non-invasive three-dimensional visualisation of structures. It also offers the opportunity to conduct a comprehensive quantitative analysis of the tested objects such as measuring the shares of the various phases, determining the material density and distribution of the size of pores and particles. The aim of the paper was to present an overview on the applicability and relevance of X-ray microtomography in the study of mineralised tissues of the teeth.

MATERIALS AND METHODS

The article is based on the most recent and significant literature and own observations.

RESULTS

The use of X-ray microtomography in dentistry has recently increased and includes, inter alia, the assessment of the density of minerals in enamel and dentin, the detection of demineralisation in an artificially and a naturally induced caries, the automatic measurement of the depth of cavities in dentin, the measurement of the amount of removed dentin in preparation of carious lesions by various methods, the assessment of microleakage around fillings and fissure sealants, cortical bone density measurement, evaluation of root canal morphology, comparison of the accuracy of root canal working and filling by various methods.

CONCLUSIONS

X-ray microtomography offers within the analysis of mineralised tissues - complex structures of bone, teeth and biomedical materials, turn out to be indispensable since it opens new opportunities for cognitive and implementation research.

Engineering biological gradients

Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients.