Effect of the photoactivation method on composite resin cure.

For composite resins to obtain good properties, they must present a high degree of conversion and minimal polymerization contraction. To minimize this contraction, alternative photoactivation techniques have been suggested. The objective of this study was to compare the hardness of a photoactivated composite resin using the pulse-delay, soft start and continuous conventional technique, in thicknesses of 1, 2 and 3mm. The resin was activated with halogen light and the photoactivation time and intensity varied according to the technique. The samples were stored in an oven at 37ºC for one week and submitted to the Vickers microhardness test, on both the irradiated surface and the opposite surface. The results were submitted to ANOVA and the Tukey’s test with a level of significance of 5%. It was concluded that the hardness was higher with photoactivation of 40 seconds and for the techniques that had the same photoactivation time (20 seconds) there was no difference in terms of hardness. Therefore the hardness is not influenced by the technique, but rather, by the polymerization time

The Inhibitor of Growth Protein 5 (ING5) Depends on INCA1 as a Co-Factor for Its Antiproliferative Effects

The proteins of the Inhibitor of Growth (ING) family are involved in multiple cellular functions such as cell cycle regulation, apoptosis, and chromatin remodeling. For ING5, its actual role in growth suppression and the necessary partners are not known. In a yeast-two-hybrid approach with human bone marrow derived cDNA, we identified ING5 as well as several other proteins as interaction partners of Inhibitor of cyclin A1 (INCA1) that we previously characterized as a novel interaction partner of cyclin A1/CDK2. ING5 expression in leukemic AML blasts was severely reduced compared to normal bone marrow. In line, ING5 inhibited bone marrow colony formation upon retroviral transduction. However, Inca1−/− bone marrow colony formation was not suppressed by ING5. In murine embryonic fibroblast (MEF) cells from Inca1+/+ and Inca1−/− mice, overexpression of ING5 suppressed cell proliferation only in the presence of INCA1, while ING5 had no effect in Inca1−/− MEFs. ING5 overexpression induced a delay in S-phase progression, which required INCA1. Finally, ING5 overexpression enhanced Fas-induced apoptosis in Inca1+/+ MEFs, while Inca1−/− MEFs were protected from Fas antibody-induced apoptosis. Taken together, these results indicate that ING5 is a growth suppressor with suppressed expression in AML whose functions depend on its interaction with INCA1

Electrospun poly(d/l-lactide-co-l-lactide) hybrid matrix: a novel scaffold material for soft tissue engineering

Electrospinning is a long-known polymer processing technique that has received more interest and attention in recent years due to its versatility and potential use in the field of biomedical research. The fabrication of three-dimensional (3D) electrospun matrices for drug delivery and tissue engineering is of particular interest. In the present study, we identified optimal conditions to generate novel electrospun polymeric scaffolds composed of poly-d/l-lactide and poly-l-lactide in the ratio 50:50. Scanning electron microscopic analyses revealed that the generated poly(d/l-lactide-co-l-lactide) electrospun hybrid microfibers possessed a unique porous high surface area mimicking native extracellular matrix (ECM). To assess cytocompatibility, we isolated dermal fibroblasts from human skin biopsies. After 5 days of in vitro culture, the fibroblasts adhered, migrated and proliferated on the newly created 3D scaffolds. Our data demonstrate the applicability of electrospun poly(d/l-lactide-co-l-lactide) scaffolds to serve as substrates for regenerative medicine applications with special focus on skin tissue engineering

Risk factors for Coronavirus disease 2019 (Covid-19) death in a population cohort study from the Western Cape province, South Africa

Risk factors for coronavirus disease 2019 (COVID-19) death in sub-Saharan Africa and the effects of human immunodeficiency virus (HIV) and tuberculosis on COVID-19 outcomes are unknown. We conducted a population cohort study using linked data from adults attending public-sector health facilities in the Western Cape, South Africa. We used Cox proportional hazards models, adjusted for age, sex, location, and comorbidities, to examine the associations between HIV, tuberculosis, and COVID-19 death from 1 March to 9 June 2020 among (1) public-sector “active patients” (≥1 visit in the 3 years before March 2020); (2) laboratory-diagnosed COVID-19 cases; and (3) hospitalized COVID-19 cases. We calculated the standardized mortality ratio (SMR) for COVID-19, comparing adults living with and without HIV using modeled population estimates.Among 3 460 932 patients (16% living with HIV), 22 308 were diagnosed with COVID-19, of whom 625 died. COVID19 death was associated with male sex, increasing age, diabetes, hypertension, and chronic kidney disease. HIV was associated with COVID-19 mortality (adjusted hazard ratio [aHR], 2.14; 95% confidence interval [CI], 1.70–2.70), with similar risks across strata of viral loads and immunosuppression. Current and previous diagnoses of tuberculosis were associated with COVID-19 death (aHR, 2.70 [95% CI, 1.81–4.04] and 1.51 [95% CI, 1.18–1.93], respectively). The SMR for COVID-19 death associated with HIV was 2.39 (95% CI, 1.96–2.86); population attributable fraction 8.5% (95% CI, 6.1–11.1)

Agglomeration of magnetic nanoparticles and its effects on magnetic hyperthermia

Magnetic fluid hyperthermia (MFH) is a promising approach for organ-confined tumor treatment. In MFH, magnetic nanoparticles (MNP) are magnetically targeted at the tumor site and heated in an alternating magnetic field. The heat produced by the MNP is used to cause tumor cell death. At the tumor site, MNP bind to the cell membrane and form agglomerates before they are internalized into the intracellular compartments. Intracellular immobilization and the formation of agglomerates influence heating properties of MNP making it difficult to control the local heating inside the tumor. In this study, we investigated MNP agglomerated samples for their heating efficiency. We found an increase in heating of 22 % upon agglomeration. If MNP are additionally immobilized, however, the heating decreases by 30 %. Consequently, due to the binding of bigger MNP agglomerates at cellular level, heating efficiency inside tumors is assumed to decrease

Vibrio cholerae biofilm dispersal regulator causes cell release from matrix through type IV pilus retraction

The extracellular matrix is a defining feature of bacterial biofilms and provides structural stability to the community by binding cells to the surface and to each other. Transitions between bacterial biofilm initiation, growth, and dispersion require different regulatory programs, all of which result in modifications to the extracellular matrix composition, abundance, or functionality. However, the mechanisms by which individual cells in biofilms disengage from the matrix to enable their departure during biofilm dispersal are unclear. Here, we investigated active biofilm dispersal of Vibrio cholerae during nutrient starvation, resulting in the discovery of the conserved Vibrio biofilm dispersal regulator VbdR. We show that VbdR triggers biofilm dispersal by controlling cellular release from the biofilm matrix, which is achieved by inducing the retraction of the mannose-sensitive hemagglutinin (MSHA) type IV pili and the expression of a matrix protease IvaP. We further show that MSHA pili have numerous binding partners in the matrix and that the joint effect of MSHA pilus retraction and IvaP activity is necessary and sufficient for causing biofilm dispersal. These results highlight the crucial role of type IV pilus dynamics during biofilm dispersal and provide a new target for controlling V. cholerae biofilm abundance through the induction and manipulation of biofilm dispersal

Linear structures of magnetic nanoparticles in hyperthermia and magnetic particle imaging

The development of theranostic devices combining magnetic particle imaging (MPI) and magnetic hyperthermia opens new possibilities for clinical applications of magnetic nanoparticles (MNP), e.g., hyperthermia-mediated drug delivery. Enhancing MNP performance for such applications can be achieved by using linear structures of MNP (i.e. chains, elongated clusters) instead of randomly distributed MNP. Here, we investigate the hyperthermia and MPI performance of two types of MNP linear structures: one generated by exposing MNP to a static magnetic field inside a hydrogel and the other by extruding a mixture of polypropylene and MNP to hybrid fibers. For both types of linear structures, an increase in heating efficiency and MPI signal was observed when the linear structure orientation is in the direction of the excitation field. In summary, the generation of MNP linear structures is a promising approach to increase their performance in MPI and magnetic hyperthermia. For MPI image reconstruction, the orientation of the linear structures relative to the drive field direction should be considered

Micro-hardness evaluation of a micro-hybrid composite resin light cured with halogen light, light-emitting diode and argon ion laser

This in vitro study aimed to determine whether the micro-hardness of a composite resin is modified by the light units or by the thickness of the increment. Composite resin disks were divided into 15 groups (n = 5), according to the factors under study: composite resin thickness (0 mm, 1 mm, 2 mm , 3 mm and 4 mm) and light units. The light activation was performed with halogen light (HL) (40 s, 500 mW/cm(2)), argon ion laser (AL) (30 s, 600 mW/cm(2)) or light-emitting diode (LED) (30 s, 400 mW/cm(2)). Vickers micro-hardness tests were performed after 1 week and were carried out on the top surface (0 mm-control) and at different depths of the samples. Analysis of variance (ANOVA) and Tukey tests (P a parts per thousand currency signaEuro parts per thousand 0.05) revealed no statistically significant difference among the light units for the groups of 0 mm and 1 mm thickness. At 2 mm depth, the AL was not statistically different from the HL, but the latter showed higher micro-hardness values than the LED. In groups with 3 mm and 4 mm thickness, the HL also showed higher micro-hardness values than the groups activated by the AL and the LED. Only the HL presented satisfactory polymerization with 3 mm of thickness. With a 4 mm increment no light unit was able to promote satisfactory polymerization.Sao Paulo Research Foundation/FAPESP[99/08433-4]Sao Paulo Research Foundation/FAPESP[99/11408-1