Modulation of both mechanical properties and biocompatibilities of hyaluronic acid (HA) hydrogels is very importance for their applications in biomaterials. Pure HA solution was converted into a hydrogel by using butanediol diglycidyl ether (BDDE) as a crosslinking agent. Mechanical properties of the HA hydrogels have been evaluated by adding up different amount of BDDEs. While the mechanical properties of the obtained HA hydrogels were evaluated by measuring their crosslinking degrees, elastic modulus and viscosity, their in vitro biocompatibilities were done by measuring the degrees of anti-inflammatory reactions, cell viabilities and cytotoxicity. The degrees of anti-inflammatory reactions were determined by measuring the amount of nitric oxides (NOs) released from lipopolysaccharide(LPS)(+)-induced macrophages; cell viability was evaluated by observing differences in the behaviors of fibroblasts covered with the HA hydrogels, compared with those covered with the films of Teflon and Latex. Cytotoxicity of the HA hydrogels was also evaluated by measuring the degrees of viability of the cells exposed on the extracts of the HA hydrogels over those of Teflon, Latex and pure HA solutions by the assays of thiazoly blue tetrazolium bromide (MTT), neutral reds, and bromodeoxyuridine (BrdU). The results showed that employment of BDDEs beyond critical amounts showed lower biocompatibility of the crosslinked HA hydrogels but higher crosslinking degrees and mechanical properties, indicating the importance of controlling the HA concentrations, BDDE amounts and their reaction times for the synthesis of the crosslinked HA hydrogels for their clinical applications as biomaterials.
Background Aromatase inhibitors (AIs) are the preferred endocrine treatment for postmenopausal hormonal receptor-positive breast cancer. However, there is controversy on the long-term cardiovascular and cerebrovascular safety of AIs over that of tamoxifen. Methods We analyzed the National Health Information Database (NHID) of 281,255 women over a 20-year-old diagnosed with breast cancer between 2009 and 2016. Cardiovascular events (CVEs) were defined as the development of the following, acute coronary syndrome (ACS), ischemic and hemorrhagic stroke, defined by using insurance claim records. The model was constructed by Cox proportional hazard regression and this model was used to analyze the effects of AI and tamoxifen on CVE. Results We included 47,569 women for the final analysis. Patients were classified into ‘No hormonal treatment (n = 18,807), ‘Switch ( n = 2097)’, ‘Tamoxifen ( n = 7081)’ and ‘AI ( n = 19,584)’. There were 2147 CVEs in 2032 patients (4.1%). Univariate analysis showed that women with tamoxifen had significantly lower risk for CVEs compared to no-treatment (hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.74–0.97) while AI showed no such effect (HR 0.93, 95% CI 0.84–1.02). After adjusting for other risk factors (hypertension, dyslipidemia, family history), the use of tamoxifen was associated with significant protective effect against ACS (HR 0.63, 95% CI 0.47–0.84). Conclusions Our results, based on the NHID, supports the protective effect of tamoxifen against CVE in Korean breast cancer patients aged 55 and older that is not seen with AIs. Our results can guide the selection of adjuvant hormonal treatment agents for Korean breast cancer patients based on their risk of developing CVE.
Background) Empirical Software Engineering (SE) strives to provide empirical evidence about the pros and cons of SE approaches. This kind of knowledge becomes relevant when the issue is whether to change from a currently employed approach to a new one or not. An informed decision is required and is particularly important in the development of safety-critical systems. For example, for the safety analysis of safety-critical embedded systems, methods such as Failure Mode and Effect Analysis (FMEA) and Fault Tree Analysis (FTA) are used. With the advent of model-based systems and software development, the question arises whether safety engineering methods should also be adopted. New technologies such as Component Integrated Fault Trees (CFT) come into play. Industry demands to know the benefits of these new methods over established ones such as Fault Trees (FT). (Methods) For the purpose of comparing CFT and FT with regard to the capabilities of the safety analysis methods (such as quality of the results) and to the participants' rating of the consistency, clarity, and maintainability of the methods, we designed a comparative study as a controlled experiment using a within-subject design. The experiment was run with seven academic staff members working towards their PhD. The study was replicated with eleven domain experts from industry. (Results) Although the analysis of the tasks' solutions showed that the use of CFT did not yield a significantly different number of correct or incorrect solutions, the participants rated the modeling capacities of CFT higher in terms of model consistency, clarity, and maintainability. (Conclusion) From this first evidence, we conclude that CFT have the potential of being beneficial for companies looking for a safety analysis approach for projects using model-based development.
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