Površinska obrada laserom Mg-Al-Zn legura

In this paper the structure and properties investigations results of the cast magnesium alloys in the as cast state, after heat treatment and laser surface treatment are presented. The aim of this work was to improve the surface layer properties of the Mg-Al-Zn cast magnesium alloys by melting and feeding of TiC, VC, WC, SiC, NbC and Al2O3 particles onto the surface. Laser processing was carried out using high diode power laser (HDPL). A series of experiments was carried out with varying scan rates and laser power. The resulting surface layers were examined using metallographic optical microscopy, scanning electron microscopy, X-ray diffraction, microhardness measurements and corrosion resistance tests. Mg-Al-Zn alloys after laser treatment are characterized by two zones: alloyed zone (AZ) and heat affected zone (HAZ) with different thickness and shape depending on laser power and ceramic powder used. Alloyed zone is composed mostly of dendrites with the Mg17Al12 lamellar eutectic and Mg in the interdendritic areas. The increase of microhardness from about 50 HV0,1 to about 200 HV0,1 in alloyed zone were observed.U ovom radu prezentirana je struktura i mehanička svojstva ljevačke magnezijske legure u ljevačkom stanju, nakon toplinske obrade i obrade površine laserom. Cilj ovog rada je unaprijediti svojstva površinskog sloja Mg-Al-Zn ljevačke magnezijske legure taljenjem i dodavanjem čestica TiC, VC, WC, SiC, NbC i Al2O3 na površinu. Obrada laserom izvodila se laserom visoke snage na diodi (HDPL). Serija eksperimenata izvodila se varirajući brzinu skeniranja i snagu lasera. Rezultirajući sloj na površini ispitivalo se metalografskim svjetlosnim mikroskopom, scanning elektronskim mikroskopom, difrakcijom x-zrakama, mjerenjem tvrdoće i mikrotvrdoće i testovima korozijske otpornosti. Poboljšanje proizvodne tehnike i kemijskog sastava kao i metoda toplinske obrade dovode do razvoja projektiranja materijala za optimalna fizikalna i mehanička svojstva novorazvijenih legura

Anterior abdominal fixation — a new option in the surgical treatment of pelvic organ prolapse

Objectives: To present anterior abdominal fixation — a new surgical technique for the treatment of pelvic organ prolaps (POP) and to evaluate the results of the treatment of patients with stage III and IV POP operated using this technique.Material and methods: Anterior abdominal fixation for treating stage III and IV POP was carried out in 42 women, who were qualified according to the Pelvic Organ Prolapse Quantification System (POP-Q) scale at baseline and after 12 months. The Pelvic Floor Disability Index-20 (PFDI-20), along with its symptom scales, were evaluated.Results: The mean age 42 operated women was 64.5 years, and the average BMI was 27.3 (83% women were overweight). At baseline, 29 (69%) women had POP stage IV, and 13 (31%) women had POP stage III. Overall, 14 (33%) underwent laparoscopy, 28 (67%) underwent laparotomy. At 12 months, 14 (33.3%) women had POP stage I; 21 (50%) women had POP stage II. Seven patients (16.6%) experienced a recurrence of disease with advancement at the degree of III/IV; 4 (9.5%) women required adjuvant surgery in the form of anterior and posterior vaginal wall surgery. No early complications after surgery were observed. The comparison of the results before and after surgery showed statistically significant improvement in terms of the P-QoL score as well as PFDI-20 along with its 3 symptom scales.Conclusions: Anterior abdominal fixation of the uterus to the anterior abdominal wall is effective, safe, and technically easy to perform in the treatment of POP of advanced stage

Dimeric peroxiredoxins are druggable targets in human Burkitt lymphoma

Burkitt lymphoma is a fast-growing tumor derived from germinal center B cells. It is mainly treated with aggressive chemotherapy, therefore novel therapeutic approaches are needed due to treatment toxicity and developing resistance. Disturbance of red-ox homeostasis has recently emerged as an efficient antitumor strategy. Peroxiredoxins (PRDXs) are thioredoxin-family antioxidant enzymes that scavenge cellular peroxides and contribute to red-ox homeostasis. PRDXs are robustly expressed in various malignancies and critically involved in cell proliferation, differentiation and apoptosis. To elucidate potential role of PRDXs in lymphoma, we studied their expression level in B cell-derived primary lymphoma cells as well as in cell lines. We found that PRDX1 and PRDX2 are upregulated in tumor B cells as compared with normal counterparts. Concomitant knockdown of PRDX1 and PRDX2 significantly attenuated the growth rate of lymphoma cells. Furthermore, in human Burkitt lymphoma cell lines, we isolated dimeric 2-cysteine peroxiredoxins as targets for SK053, a novel thiol-specific small-molecule peptidomimetic with antitumor activity. We observed that treatment of lymphoma cells with SK053 triggers formation of covalent PRDX dimers, accumulation of intracellular reactive oxygen species, phosphorylation of ERK1/2 and AKT and leads to cell cycle arrest and apoptosis. Based on site-directed mutagenesis and modeling studies, we propose a mechanism of SK053-mediated PRDX crosslinking, involving double thioalkylation of active site cysteine residues. Altogether, our results suggest that peroxiredoxins are novel therapeutic targets in Burkitt lymphoma and provide the basis for new approaches to the treatment of this disease

Solid Organ Transplantation During COVID-19 Pandemic: An International Web-based Survey on Resources’ Allocation

Background. Solid organ transplants (SOTs) are life-saving interventions, recently challenged by coronavirus disease 2019 (COVID-19). SOTs require a multistep process, which can be affected by COVID-19 at several phases. Methods. SOT-specialists, COVID-19-specialists, and medical ethicists designed an international survey according to CHERRIES guidelines. Personal opinions about continuing SOTs, safe managing of donors and recipients, as well as equity of resources' allocation were investigated. The survey was sent by e-mail. Multiple approaches were used (corresponding authors from Scopus, websites of scientific societies, COVID-19 webinars). After the descriptive analysis, univariate and multivariate ordinal regression analysis was performed. Results. There were 1819 complete answers from 71 countries. The response rate was 49%. Data were stratified according to region, macrospecialty, and organ of interest. Answers were analyzed using univariate- multivariate ordinal regression analysis and thematic analysis. Overall, 20% of the responders thought SOTs should not stop (continue transplant without restriction); over 70% suggested SOTs should selectively stop, and almost 10% indicated they should completely stop. Furthermore, 82% agreed to shift resources from transplant to COVID-19 temporarily. Briefly, main reason for not stopping was that if the transplant will not proceed, the organ will be wasted. Focusing on SOT from living donors, 61% stated that activity should be restricted only to "urgent"cases. At the multivariate analysis, factors identified in favor of continuing transplant were Italy, ethicist, partially disagreeing on the equity question, a high number of COVID-19- related deaths on the day of the answer, a high IHDI country. Factors predicting to stop SOTs were Europe except-Italy, public university hospital, and strongly agreeing on the equity question. Conclusions. In conclusion, the majority of responders suggested that transplant activity should be continued through the implementation of isolation measures and the adoption of the COVID-19-free pathways. Differences between professional categories are less strong than supposed

Površinska obrada laserom Mg-Al-Zn legura

In this paper the structure and properties investigations results of the cast magnesium alloys in the as cast state, after heat treatment and laser surface treatment are presented. The aim of this work was to improve the surface layer properties of the Mg-Al-Zn cast magnesium alloys by melting and feeding of TiC, VC, WC, SiC, NbC and Al2O3 particles onto the surface. Laser processing was carried out using high diode power laser (HDPL). A series of experiments was carried out with varying scan rates and laser power. The resulting surface layers were examined using metallographic optical microscopy, scanning electron microscopy, X-ray diffraction, microhardness measurements and corrosion resistance tests. Mg-Al-Zn alloys after laser treatment are characterized by two zones: alloyed zone (AZ) and heat affected zone (HAZ) with different thickness and shape depending on laser power and ceramic powder used. Alloyed zone is composed mostly of dendrites with the Mg17Al12 lamellar eutectic and Mg in the interdendritic areas. The increase of microhardness from about 50 HV0,1 to about 200 HV0,1 in alloyed zone were observed.U ovom radu prezentirana je struktura i mehanička svojstva ljevačke magnezijske legure u ljevačkom stanju, nakon toplinske obrade i obrade površine laserom. Cilj ovog rada je unaprijediti svojstva površinskog sloja Mg-Al-Zn ljevačke magnezijske legure taljenjem i dodavanjem čestica TiC, VC, WC, SiC, NbC i Al2O3 na površinu. Obrada laserom izvodila se laserom visoke snage na diodi (HDPL). Serija eksperimenata izvodila se varirajući brzinu skeniranja i snagu lasera. Rezultirajući sloj na površini ispitivalo se metalografskim svjetlosnim mikroskopom, scanning elektronskim mikroskopom, difrakcijom x-zrakama, mjerenjem tvrdoće i mikrotvrdoće i testovima korozijske otpornosti. Poboljšanje proizvodne tehnike i kemijskog sastava kao i metoda toplinske obrade dovode do razvoja projektiranja materijala za optimalna fizikalna i mehanička svojstva novorazvijenih legura