Anestesia e doença de Alzheimer – Percepções atuais

Background and objectives

It has been speculated that the use of anesthetic agents may be a risk factor for the development of Alzheimer disease. The objective of this review is to describe and discuss pre‐clinical and clinical data related to anesthesia and this disease.

Fio‐guia perdido – lições aprendidas

Central venous catheter placement is a relatively common procedure in current practice, but it is not devoid of risks. Utmost care must be taken to follow a correct technique, and only appropriately trained and/or supervised medical professionals should perform this invasive act. One of the possible complications, completely avoidable by appropriate care, is the intravascular loss of the guide wire during insertion, which is a potentially serious complication. We describe one such case.     

Effect of photobiomodulation therapy on oxidative stress markers of gastrocnemius muscle of diabetic rats subjected to high-intensity exercise

This study aimed to determine whether photobiomodulation therapy (PBMT) in diabetic rats subjected to high-intensity exercise interferes with the expression of the oxidative stress marker in the gastrocnemius muscle. Twenty-four male Wistar rats were included in this study comprising 16 diabetic and eight control rats. The animals were allocated into three groups—control, diabetic fatigue, and diabetic PBMT fatigue groups. Diabetes was induced via the intraperitoneal administration of streptozotocin (50 mg/kg). We subsequently assessed blood lactate levels and PBMT. The animals of the diabetic fatigue group PBMT were irradiated before the beginning of the exercises, with dose of 4 J and 808 nm, were submitted to treadmill running with speed and gradual slope until exhaustion, as observed by the maximum volume of oxygen and lactate level. The animals were euthanized and muscle tissue was removed for analysis of SOD markers, including catalase (CAT), glutathione peroxidase (GPx), and 2-thiobarbituric acid (TBARS) reactive substances. CAT, SOD, and GPx activities were significantly higher in the diabetic PBMT fatigue group (p?<?0.05) than in the diabetic fatigue group. Outcomes for the diabetic PBMT fatigue group were similar to those of the control group (p?>?0.05), while their antioxidant enzymes were significantly higher than those of the diabetic fatigue group. PBMT mitigated the TBARS concentration (p?>?0.05). PBMT may reduce oxidative stress and be an alternative method of maintaining physical fitness when subjects are unable to perform exercise. However, this finding requires further testing in clinical studies.     

The unexpected presence of iron in bone biopsies of hemodialysis patients

Purpose

Bone biopsy defines classical diseases that constitute the renal osteodystrophy. There is a recent concern regarding other histological findings that are not appreciated by using the turnover, mineralization, and volume (TMV) classification. Iron (Fe) overload has been considered a new challenge and the real significance of the presence of this metal in bones is not completely elucidated. Therefore, the main goal of the current study was to not only to identify bone Fe, but also correlate its presence with demographic, and biochemical characteristics.

Methods

This is a cross-sectional analysis of bone biopsies performed in 604 patients on dialysis from 2010 to 2014 in a tertiary academic Hospital.

Results

Histomorphometric findings revealed the presence of Fe in 29.1%. Fe was associated with higher levels of serum ferritin and serum calcium. No TMV status was related to Fe bone overload.

Conclusion

Our study has highlighted that the presence of Fe in one-third of bone samples has unknown clinical significance. The lack of other contemporary bone biopsy study reporting Fe prevents us from comparison. The findings presented here should be specifically addressed in a future research and will require attention prior to implementation of any clinical guideline. If any proposed treatment, however, would change the bone Fe-related morbidity is undetermined.

     

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.     

Profiles of vagal withdrawal to challenging interactions: Links with preschoolers’ conceptual shifting ability

The current study investigated profiles of vagal withdrawal in response to a challenging task in preschoolers. Also, the association between those profiles and conceptual shifting ability was assessed. Electrocardiogram of 43 four-year-olds was registered during a sequence of games including a win phase and a lose phase, while conceptual shifting ability was assessed via a standardized test. Cluster analyses revealed three profiles of cardiac vagal response to the task. Children in the first cluster displayed significant vagal withdrawal, children in the second cluster showed nonsignificant vagal withdrawal, while children in the third group displayed vagal augmentation to the challenge. These profiles differentiated preschoolers’ conceptual shifting ability. Specifically, children with vagal withdrawal had the best performance in categorization and flexibility tasks and committed fewer perseverative errors compared to children who showed blunted vagal withdrawal or vagal augmentation to the challenge. Implications for theory and practice are discussed.     

The contribution of active and passive mechanisms of 5mC and 5hmC removal in human T lymphocytes is differentiation‐ and activation‐dependent

In mammals, the 5’‐methylcytosine (5mC) modification in the genomic DNA contributes to the dynamic control of gene expression. 5mC erasure is required for the activation of developmental programs and occurs either by passive dilution through DNA replication, or by enzymatic oxidation of the methyl mark to 5‐hydroxymethylcytosine (5hmC), which can persist as such or undergo further oxidation and enzymatic removal. The relative contribution of each mechanism to epigenetic control in dynamic biological systems still remains a compelling question. To explore this critical issue, we used primary human T lymphocytes, in which two cellular states can be clearly identified, namely quiescent naïve T cells, which are slowly or rarely proliferating, and rapidly proliferating activated T cells. We found that active mechanisms of methylation removal were selectively at work in naïve T cells, while memory T lymphocytes entirely relied on passive, replication‐dependent dilution, suggesting that proliferative capacity influences the choice of the preferential demethylation mechanism. Active processes of demethylation appear to be critical in quiescent naïve T lymphocytes for the maintenance of regulatory regions poised for rapid responses to physiological stimuli.