Low-level laser therapy improves the VO<Subscript>2</Subscript> kinetics in competitive cyclists

Some evidence supports that low-level laser therapy (LLLT) reduces neuromuscular fatigue, so incrementing sports performance. A previous randomized controlled trial of our group showed increased exercise tolerance in male competitive cyclists treated with three different LLLT doses (3, 6, and 9 J/diode; or 135, 270, and 405 J/thigh) before time-to-exhaustion cycling tests. Now, the present study was designed to evaluate the effects of these LLLT doses on the VO₂ kinetics of athletes during cycling tests. Twenty male competitive cyclists (29 years) participated in a crossover, randomized, double-blind, and placebo-controlled trial. On the first day, the participants performed an incremental cycling test to exhaustion to determine maximal oxygen uptake (VO_2MAX) and maximal power output (PO_MAX), as well as a familiarization with the time-to-exhaustion test. In the following days (2 to 5), all participants performed time-to-exhaustion tests at PO_MAX. Before the exhaustion test, different doses of LLLT (3, 6, and 9 J/diode; or 135, 270, and 405 J/thigh, respectively) or placebo were applied bilaterally to the quadriceps muscle. All exhaustion tests were monitored online by an open-circuit spirometry system in order to analyze the VO₂ amplitude, VO₂ delay time, time constant (tau), and O₂ deficit. Tau and O₂ deficit were decreased with LLLT applications compared to the placebo condition (p < 0.05). No differences (p > 0.05) were found between the experimental conditions for VO₂ amplitude and VO₂ delay time. In conclusion, LLLT decreases tau and O₂ deficit during time-to-exhaustion tests in competitive cyclists, and these changes in VO₂ kinetics response can be one of the possible mechanisms to explain the ergogenic effect induced by LLLT.     

In vitro bond strength of an epoxy resin-based root canal sealer to root dentin irradiated with high-power lasers and adhesive interface analyses

The aim of this study was to evaluate in vitro the influence of high-power lasers (Nd:YAG and diode 980 nm) associated with mineral coal as fotopotencializer on bond strength of an epoxy resin-based root canal sealer to root dentin, using the pushout test, and on the dentin/filling material interface, using confocal laser microscopy. For this purposes, 50 canines were instrumented with Mtwo rotary system up to #50.04 instrument and randomly assigned to five groups (n = 10): group I—control EDTAC; group II—EDTAC and Nd:YAG laser; group III—EDTAC and diode laser 980 nm; group IV—EDTAC, Nd:YAG laser and mineral coal 5 g/100 mL; and group V—EDTAC, diode laser 980 nm and mineral coal 5 g/100 mL. All data were analyzed by ANOVA (at 5% significance level) following the Kruskal-Wallis, Dunn and Tukey tests. The group I increased more bond strength of the sealer to root dentin that treated with only EDTAC 17% (17.21 ± 21.75 MPa), similar to the group II (12.21 ± 18.20 MPa) and group IV (14.92 ± 28.06 MPa), both treated with Nd:YAG laser, with the exception of group IV, which was added to mineral coal. The group V (8.75 ± 13.42 MPa) had similar results to the groups II and IV, but the same similarity were found when compared with group III (7.11 + 11.28 MPa), with lower results. Regarding the root thirds, the apical third (23.27 ± 29.21 MPa) presented a statistically higher value on bond strength than the cervical third (5.92 ± 5.33 MPa) and middle third (6.93 ± 7, 11 MPa) (p > 0.05). Group II (86.27 μm) showed the highest tags penetration values, with a statistically difference to the group III (51.57 μm), IV (36.77 μm) and V (32.37 μm) (p < 0.05). Group I (71.63 μm) was statistically similar to groups II and III (p > 0.05). Group IV had the lowest values and was statistically similarity to groups III and V (p > 0.05). It was concluded that the treatment with Nd:YAG laser provides better results than the diode 980 nm laser, except when was added mineral coal. The control and diode 980 nm laser groups presented less adhesive failures and more mists failures than the other groups. Both lasers did not interfere negatively compared to the control group.     

Insulin resistance and sex hormone‐binding globulin are independently correlated with low free testosterone levels in obese males

Male obesity is associated with decreased testosterone levels but the pathophysiological mechanisms behind this association are not completely understood. This study aimed to investigate the impact of hyperglycaemia/insulin resistance and sex hormone‐binding globulin (SHBG) levels on testosterone levels in a population of obese men. We investigated the impact of several clinical, anthropometric and analytic measures on testosterone levels in 150 obese males. Testosterone deficiency was present in 52.0% of the enrolled patients. This percentage dropped to 17.6% when only calculated free testosterone (FT) was accounted, as SHBG levels were correlated negatively with body mass index (r = ?.20; p < .05). Older age (p < .05) and higher homoeostasis model assessment of insulin resistance (HOMA‐IR) (p < .01) and lower SHBG levels (p < .05) were independently correlated with lower FT. Weight and fasting plasma glucose lost their statistical significance after multivariate adjustment. Patients with type 2 diabetes mellitus and pre‐diabetes had lower FT than those with normal glucose tolerance (p < .05 and p < .01 respectively). Insulin resistance, and not hyperglycaemia and weight per se, seems to be the main determinant of low testosterone levels in obese males. Low SHBG levels are correlated with low FT even after HOMA‐IR adjustment. This suggests that SHBG can be associated with testosterone deficiency beyond the influence of insulin resistance unlike previously reported.     

The association of statin therapy with the primary patency of femoral and popliteal artery stents

Objective

It has long been known that hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) broadly reduce cardiovascular events in patients with peripheral vascular disease. It was the goal of this study to determine whether there is an association between statin therapy and primary patency after stenting of superficial femoral and popliteal arteries.

Preclinical and Translational Studies in Small Ruminants (Sheep and Goat) as Models for Osteoporosis Research

Purpose of the Review

This review summarizes research on the use of sheep and goats as large animal models of human osteoporosis for preclinical and translational studies.

Recent Findings

The most frequent osteoporotic sheep model used is the ovariectomized sheep with 12 months post-operatively or more and the combined treatment of ovariectomized sheep associated to calcium/vitamin D-deficient diet and glucocorticoid applications for 6 months, but other methods are also described, like pinealectomy or hypothalamic-pituitary disconnection in ovariectomized sheep. The goat model for osteoporosis research has been used in a very limited number of studies in osteoporosis research relative to sheep. These osteoporotic small ruminant models are applied for biomaterial research, bone augmentation, efficacy of implant fixation, fragility fracture-healing process improvement, or bone-defect repair studies in the osteopenic or osteoporotic bone.

Summary

Sheep are a recognized large animal model for preclinical and translational studies in osteoporosis research and the goat to a lesser extent. Recently, the pathophysiological mechanism underlying induction of osteoporosis in glucocorticoid-treated ovariectomized aged sheep was clarified, being similar to what occurs in postmenopausal women with glucocorticoid-induced osteoporosis. It was also concluded that the receptor activator of NF-κB ligand was stimulated in the late progressive phase of the osteoporosis induced by steroids in sheep. The knowledge of the pathophysiological mechanisms at the cellular and molecular levels of the induction of osteoporosis in small ruminants, if identical to humans, will allow in the future, the use of these animal models with greater confidence in the preclinical and translational studies for osteoporosis research.