RecQ helicase expression in patients with telomeropathies.

BACKGROUND: Telomeropathies are a group of inherited disorders caused by germline pathogenic variants in genes involved in telomere maintenance, resulting in excessive telomere attrition that affects several tissues, including hematopoiesis. RecQ and RTEL1 helicases contribute to telomere maintenance by unwinding telomeric structures such as G-quadruplexes (G4), preventing replication defects. Germline RTEL1 variants also are etiologic in telomeropathies. METHODS AND RESULTS: Here we investigated the expression of RecQ (RECQL1, BLM, WRN, RECQL4, and RECQL5) and RTEL1 helicase genes in peripheral blood mononuclear cells (PBMCs) from human telomeropathy patients. The mRNA expression levels of all RecQ helicases, but not RTEL1, were significantly downregulated in patients' primary cells. Reduced RecQ expression was not attributable to cell proliferative exhaustion, as RecQ helicases were not attenuated in T cells exhausted in vitro. An additional fifteen genes involved in DNA damage repair and RecQ functional partners also were downregulated in the telomeropathy cells. CONCLUSION: These findings indicate that the expression of RecQ helicases and functional partners involved in DNA repair is downregulated in PBMCs of telomeropathy patients.

Laser and plasma dental soldering techniques applied to Ti-6Al-4V alloy: ultimate tensile strength and finite element analysis.

STATEMENT OF PROBLEM: The literature provides limited information regarding the performance of Ti-6Al-4V laser and plasma joints welded in prefabricated bars in dental applications. PURPOSE: The purpose of this study was to evaluate the mechanical strength of different diameters of Ti-6Al-4V alloy welded with laser and plasma techniques. MATERIAL AND METHODS: Forty-five dumbbell-shaped rods were created from Ti-6Al-4V and divided into 9 groups (n=5): a control group with 3-mm and intact bars; groups PL2.5, PL3, PL4, and PL5 (specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with plasma); and groups L2.5, L3, L4, and L5 (specimens with 2.5-, 3-, 4-, and 5-mm diameters welded with laser). The specimens were tested for ultimate tensile strength (UTS), and elongation percentages (EP) were obtained. Fractured specimens were analyzed by stereomicroscopy, and welded area percentages (WAP) were calculated. Images were made with scanning electron microscopy. In the initial analysis, the data were analyzed with a 2-way ANOVA (2×4) and the Tukey Honestly Significant Difference (HSD) test. In the second analysis, the UTS and EP data were analyzed with 1-way ANOVA, and the Dunnett test was used to compare the 4 experimental groups with the control group (α=.05). The Pearson and Spearman correlation coefficient tests were applied to correlate the study factors. Finite element models were developed in a workbench environment with boundary conditions simulating those of a tensile test. RESULTS: The 2-way ANOVA showed that the factors welding type and diameter were significant for the UTS and WAP values. However, the interaction between them was not significant. The 1-way ANOVA showed statistically significant differences among the groups for UTS, WAP, and EP values. The Dunnett test showed that all the tested groups had lower UTS and EP values than the control group. The 2.5- and 3-mm diameter groups showed higher values for UTS and WAP than the other test groups. A positive correlation was found between welded area percentage and UTS and a negative correlation between these parameters and the diameters of the specimens. No statistically significant difference was found between the weld techniques. CONCLUSIONS: Under the experimental conditions described, diameters of 2.5 and 3 mm resulted in higher UTS and WAP for both laser and plasma welding and appear to be the best option for joining prefabricated rods in this kind of union.

Conventional (MG-BR46 Conquista) and transgenic (BRS Valiosa RR) soybeans have no mutagenic effects and may protect against induced-DNA damage in vivo.

In the present study, we evaluated the pesticide and metal concentrations as well as the antimutagenic and mutagenic properties of commercial soybeans (Glycine max). Male Swiss mice were fed diets containing 1%, 10%, or 20% (w/w) transgenic soybeans (BRS Valiosa RR) or parental isogenic conventional soybeans (MG-BR46 Conquista). Cyclophosphamide (50 mg kg⁻¹ b.w.) was added in a single dose 24 h before euthanasia as an induction agent. There was no difference in the composition (ash, total fat, protein, moisture, and carbohydrates) of the diets containing the same soybean concentration. The results show that the commercially available Brazilian soybeans tested are free of organochlorine, organophosphate, and carbamate pesticides and contain acceptable heavy metal concentrations. Both cyclophosphamide and soybean treatments were not sufficient to cause detectable oxidative damage on liver by the levels of malondialdehyde and protein carbonyl. The transgenic soybeans are also nonmutagenic and have protective effects against DNA damage similar to those of conventional soybeans but to a lesser percentage (64%-101% for conventional and 23%-33% for transgenic diets).