Fatigue and microgap behaviour of a three-unit implant-fixed dental prosthesis combining conventional and dynamic abutments

This is an in vitro study composed by a fatigue test followed by an optical microscopy analysis. Dynamic abutments concept, recently introduced on screw-retained implant dental prosthesis, consists on the screw channel customisation according to the individual needs of each rehabilitation. Geometry and tightening torque differences advise the assessment of their mechanical performance. Clarify whether the combination of dynamic and conventional abutments in a three-unit implant-fixed prosthesis has detrimental effects either on the mechanical performance under cyclic loading or on the implant-abutment microgap dimensions. The fatigue test was performed in agreement with the ISO standard 14801. Then on the samples that resisted 5 million cycles, the implant-abutment microgap was measured on dynamic and conventional abutments using optical microscopy. Two unloaded samples were used as control group. The samples supported a load of 1050 N. The implant-abutment microgap measurement did not show statistically significant differences (p=.086) between loaded and unloaded groups, but the loaded conventional abutments showed a significant lower implant-abutment microgap (p=.05) than the loaded dynamic abutments. The combination of conventional and dynamic abutments do not seem to produce a decrease in fatigue resistance to a level below the mastication forces or an increase in the joint dimensions.The study was supported in part by SciTech - Science and Technology for Competitive and Sustainable Industries, and the R&D project was cofinanced by the North Portugal Regional Operational Program ("NORTE2020") and the European Regional Development Fund (FEDER)

Purified Cas9 Fusion Proteins for Advanced Genome Manipulation.

The CRISPR/Cas9 system (CRISPR = clustered regularly interspaced short palindromic repeats) has rapidly become one of the most versatile genome manipulation technologies, and different methods to introduce the Cas9 nuclease activity into cells have been developed. The direct delivery of purified Cas9 protein complexed with a guide RNA as a ribonucleoprotein (RNP) has emerged as an advantageous approach, as it provides instant, but limited activity of the enzyme, thereby reducing off-target cleavage. The usefulness of the CRISPR/Cas9 system has recently been extended by the generation of Cas9 or dead (d) Cas9 fusion genes. However, these systems have so far been mainly explored when delivered by expression plasmids. Here, a variety of purified Cas9 fusion proteins are generated, and their utility is tested in a number of assays. This work illustrates that Cas9 fused to green-or redfluorescent proteins can be usefully employed to increase the frequency of targeted cells when transfected as RNPs. Furthermore, it is demonstrated that purified dCas9 fused to a dual transactivation domain can potently activate gene expression when transfected as an RNP into embryonic stem cells. The results show that purified Cas9 fusion proteins are versatile and efficient reagents that facilitate advanced genome manipulation

Assessment of a new questionnaire for self-reported sun sensitivity in an occupational skin cancer screening program

<p>Abstract</p> <p>Background</p> <p>Sun sensitivity of the skin is a risk factor for the development of cutaneous melanoma and other skin cancers. Epidemiological studies on causal factors for the development of melanoma must control for sun sensitivity as a confounder. A standardized instrument for measuring sun sensitivity has not been established yet. It is assumed that many studies show a high potential of residual confounding for sun sensitivity. In the present study, a new questionnaire for the assessment of self-reported sun sensitivity is administered and examined.</p> <p>Methods</p> <p>Prior to an occupational skin cancer screening program, the 745 participating employees were asked to fill in a questionnaire for self-assessment of sun sensitivity. The questionnaire was developed by experts of the working group "Round Table Sunbeds" (RTS) to limit the health hazards of sunbed use in Germany. A sun sensitivity score (RTS-score) was calculated using 10 indicators. The internal consistency of the questionnaire and the agreement with other methods (convergent validity) were examined.</p> <p>Results</p> <p>The RTS-score was calculated for 655 study participants who were 18 to 65 years of age. The correlation of the items among each other was between 0.12 and 0.62. The items and the RTS-score correlated between 0.46 and 0.77. The internal consistency showed a reliability coefficient with 0.82 (Cronbach's alpha). The comparison with the Fitzpatrick classification, the prevailing standard, was possible in 617 cases with a rank correlation of r_s= 0.65. The categorization of the RTS-score in four risk groups showed correct classification to the four skin types of Fitzpatrick in 75% of the cases. Other methods for the assessment of sun sensitivity displayed varying agreements with the RTS-score.</p> <p>Conclusion</p> <p>The RTS questionnaire showed a sufficient internal consistency. There is a good convergent validity between the RTS-score and the Fritzpatrick classification avoiding shortcomings of the prevailing standard. The questionnaire represents a simple, reliable and valid instrument for the assessment of sun sensitivity. The questionnaire can be useful for epidemiological studies as well as for skin cancer prevention. Further development and standardization of sun sensitivity assessments is necessary to strengthen the evidence of epidemiological studies on causal factors of melanoma and other skin cancers.</p