Null genotype of GSTT1 contributes to increased Parkinson's disease risk in Caucasians: evidence from a meta-analysis

Disease Duration Influences Gene Expression in Neuromelanin-Positive Cells From Parkinson's Disease Patients

Analyses of gene expression in cells affected by neurodegenerative disease can provide important insights into disease mechanisms and relevant stress response pathways. Major symptoms in Parkinson’s disease (PD) are caused by the degeneration of midbrain dopamine (mDA) neurons within the substantia nigra. Here we isolated neuromelanin-positive dopamine neurons by laser capture microdissection from post-mortem human substantia nigra samples recovered at both early and advanced stages of PD. Neuromelanin-positive cells were also isolated from individuals with incidental Lewy body disease (ILBD) and from aged-matched controls. Isolated mDA neurons were subjected to genome-wide gene expression analysis by mRNA sequencing. The analysis identified hundreds of dysregulated genes in PD. Results showed that mostly non-overlapping genes were differentially expressed in ILBD, subjects who were early after diagnosis (less than five years) and those autopsied at more advanced stages of disease (over five years since diagnosis). The identity of differentially expressed genes suggested that more resilient, stably surviving DA neurons were enriched in samples from advanced stages of disease, either as a consequence of positive selection of a less vulnerable long-term surviving mDA neuron subtype or due to up-regulation of neuroprotective gene products.

Xenobiotic transport and metabolism in the human brain

Organisms have metabolic pathways responsible for eliminating endogenous and exogenous toxicants. Generally, we associate the liver par excellence as the organ in charge of detoxifying the body; however, this process occurs in all tissues, including the brain. Due to the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB), the Central Nervous System (CNS) is considered a partially isolated organ, but similar to other organs, the CNS possess xenobiotic transporters and metabolic pathways associated with the elimination of xenobiotic agents. In this review, we describe the different systems related to the detoxification of xenobiotics in the CNS, providing examples in which their association with neurodegenerative processes is suspected. The CNS detoxifying systems include carrier-mediated, active efflux and receptor-mediated transport, and detoxifying systems that include phase I and phase II enzymes, as well as those enzymes in charge of neutralizing compounds such as electrophilic agents, reactive oxygen species (ROS), and free radicals, which are products of the bioactivation of xenobiotics. Moreover, we discuss the differential expression of these systems in different regions of the CNS, showing the different detoxifying needs and the composition of each region in terms of the cell type, neurotransmitter content, and the accumulation of xenobiotics and/or reactive compounds.

The glutathione system in Parkinson's disease and its progression

Redox dysfunctions and neuro-oxidative stress play a major role in the pathophysiology and progression of Parkinson's disease (PD). Glutathione (GSH) and the reduced/oxidized glutathione (GSH/GSSG) ratio are lowered in oxidative stress conditions and may lead to increased oxidative toxicity. GSH is involved not only in neuro-immune and neuro-oxidative processes, including thiol redox signaling, but also in cell proliferation and differentiation and in the regulation of cell death, including apoptotic pathways. Lowered GSH metabolism and a low GSH/GSSG ratio following oxidative stress are associated with mitochondrial dysfunctions and constitute a critical factor in the neuroinflammatory and neurodegenerative processes accompanying PD. This review provides indirect evidence that GSH redox signaling is associated with the pathophysiology of PD. Nevertheless, it has not been delineated whether GSH redox imbalances are a causative factor in PD or whether PD-associated pathways cause the GSH redox imbalances in PD. The results show that antioxidant approaches, including neuroprotective and anti-neuroinflammatory agents, which neutralize reactive oxygen species, may have therapeutic efficacy in the treatment of PD and its progression.

Biological functions of selenium and its potential influence on Parkinson's disease

Parkinson's disease is characterized by the death of dopaminergic neurons, mainly in the substantia nigra, and causes serious locomotor dysfunctions. It is likely that the oxidative damage to cellular biomolecules is among the leading causes of neurodegeneration that occurs in the disease. Selenium is an essential mineral for proper functioning of the brain, and mainly due to its antioxidant activity, it is possible to exert a special role in the prevention and in the nutritional management of Parkinson's disease. Currently, few researchers have investigated the effects of selenium on Parkinson´s disease. However, it is known that very high or very low body levels of selenium can (possibly) contribute to the pathogenesis of Parkinson's disease, because this imbalance results in increased levels of oxidative stress. Therefore, the aim of this work is to review and discuss studies that have addressed these topics and to finally associate the information obtained from them so that these data and associations serve as input to new research.

Comparison of Postoperative Events between Spinal Anesthesia and General Anesthesia in Laparoscopic Cholecystectomy: A Systemic Review and Meta-Analysis of Randomized Controlled Trials

Background. Laparoscopic cholecystectomy is usually carried out under general anesthesia. There were a few studies which have found spinal anesthesia as a safe alternative. We aimed to evaluate the postoperative events between spinal anesthesia and general anesthesia in patients undergoing laparoscopic cholecystectomy. Methods. We searched PubMed, Embase, and Cochrane Library (from inception to January 2016) for eligible studies. The primary outcome was the visual analogue scale score. Secondary outcomes included postoperative nausea and vomiting and urine retention 24 hours postoperatively. We calculated pooled risk ratios and 95% confidence interval using random- or fixed-effects models. Results. Eight trials involving 723 patients were listed. Meta-analysis showed that patients in spinal anesthesia groups have lower visual analogue scale score 24 hours postoperatively. There were significant decreases in the occurrence of postoperative nausea and vomiting in spinal anesthesia group when compared with general anesthesia group (odds ratios: 0.38, 95% confidence interval: 0.19-0.76; P = 0.006) with heterogeneity accepted (I (2) = 13%; P = 0.33), while urine retention rate was increased in patients with spinal anesthesia (odds ratios: 4.95, 95% confidence interval: 1.24-19.71; P = 0.02) without any heterogeneity (I (2) = 0%; P = 0.98). Conclusions. Spinal anesthesia may be associated with less postoperative pain and postoperative nausea and vomiting compared with general anesthesia.

NAT2 polymorphisms and risk for Parkinson's disease: a systematic review and meta-analysis

INTRODUCTION

Several studies suggested a possible association between certain polymorphisms in the N-acetyl-transferase 2 (NAT2) gene (which encodes a very important enzyme involved in xenobiotic metabolism) and the risk for Parkinson's disease (PD). As the results of studies on this issue are controversial, we conducted a systematic review and a meta-analysis of eligible studies on this putative association.

AREAS COVERED

The authors revised the relationship between NAT2 polymorphisms and the risk of developing PD using several databases, and performed a meta-analysis using the software Meta-Disc1.1.1. In addition heterogeneity between studies was analyzed. A description of studies regarding gene-gene interactions and gene-environmental interactions involving NAT2 polymorphisms is also made.

EXPERT OPINION

Despite several recent meta-analyses showing an association between several polymorphisms in genes related with detoxification mechanisms such as cytochrome P4502D6 (CYP2D6), and glutathione transferases M1 and T1 (GSTM1, and GSTT1), data on NAT2 gene polymorphisms obtained from the current meta-analysis do not support a major association with PD risk, except in Asian populations. However, data from many studies are incomplete and therefore insufficient data exists to draw definitive conclusions. Several studies suggesting gene-gene and gene-environmental factors involving NAT2 gene in PD risk await confirmation.

Advances in understanding genomic markers and pharmacogenetics of Parkinson's disease

INTRODUCTION

The inheritance pattern of Parkinson's disease (PD) is likely multifactorial (owing to the interplay of genetic predisposition and environmental factors). Many pharmacogenetic studies have tried to establish a possible role of candidate genes in PD risk. Several studies have focused on the influence of genes in the response to antiparkinsonian drugs and in the risk of developing side-effects of these drugs.

AREAS COVERED

This review presents an overview of current knowledge, with particular emphasis on the most recent advances, both in case-control association studies on the role of candidate genes in the risk for PD as well as pharmacogenetic studies on the role of genes in the development of side effects of antiparkinsonian drugs. The most reliable results should be derived from meta-analyses of case-control association studies on candidate genes involving large series of PD patients and controls, and from genome-wide association studies (GWAS).

EXPERT OPINION

Prospective studies of large samples involving several genes with a detailed history of exposure to environmental factors in the same cohort of subjects, should be useful to clarify the role of genes in the risk for PD. The results of studies on the role of genes in the development of side-effects of antiparkinsonian drugs should, at this stage, only be considered preliminary.

No difference in clinical outcomes after total knee arthroplasty between patellar eversion and non-eversion

PURPOSE

Multiple surgical techniques in minimally invasive total knee arthroplasty (TKA) are associated with clinical differences. However, whether patellar eversion impairs clinical outcomes remains controversial. We conducted a systematic review of randomized controlled trials (RCTs) to provide current understanding on this topic.

METHODS

A literature search of the PubMed, Embase, and Cochrane library databases was performed to identify RCTs comparing patellar eversion with patellar non-eversion (PN). Two authors independently selected the studies, assessed methodological quality, and extracted data.

RESULTS

Five RCTs involving 379 knees were included. The results revealed no significant differences in functional scores, pain, quality of life, quadriceps strength, patellar height, alignment, or complication rate between patellar eversion and PN. Power analysis showed that the power of the individual study and meta-analysis ranged from 5.0 to 70.8%, with the exception of the power of alignment and patellar height in two of the individual studies, which was 100.0 and 99.9%, respectively.

CONCLUSIONS

Based on the current evidence, patellar eversion during TKA could not definitely lead to inferior postoperative outcomes. Patellar eversion and patellar non-eversion could achieve similar clinical outcomes.

LEVEL OF EVIDENCE

Systematic review and meta-analysis, Level I.

Dexamethasone versus ondansetron in the prevention of postoperative nausea and vomiting in patients undergoing laparoscopic surgery: a meta-analysis of randomized controlled trials

Background

Dexamethasone is an antiemetic alternative to ondansetron. We aimed to compare the effects of dexamethasone and ondansetron in preventing postoperative nausea and vomiting (PONV) in patients undergoing laparoscopic surgery.

Methods

We searched PubMed, Embase, Medline and Cochrane Library (from inception to July 2014) for eligible studies. The primary outcome was the incidence of PONV during the first 24 h after surgery. The secondary outcomes included PONV in the early postoperative stage (0–6 h), PONV in the late postoperative stage (6–24 h), and the postoperative anti-emetics used at both stages. We calculated pooled risk ratios (RR) and 95 % CIs using random- and fixed-effects models.

Results

Seven trials involving 608 patients were included in this meta-analysis, which found that dexamethasone had a comparable effectiveness in preventing PONV (RR, 0.91; 95 % CI, 0.73-1.13; P = 0.39) with that of ondansetron within 24 h of laparoscopic surgery, with no evidence of heterogeneity among the studies (I² = 0 %; P = 0.71). In the early postoperative stage (0–6 h), ondansetron was better at decreasing PONV than dexamethasone (RR, 1.71; 95 % CI, 1.05-2.77; P = 0.03), while in the late postoperative stage (6–24 h), dexamethasone was more effective in preventing PONV than ondansetron (RR, 0.51; 95 % CI, 0.27-0.93; P = 0.03). There was no significant difference in the postoperative anti-emetics used (RR, 0.90; 95 % CI, 0.67-1.19; P = 0.45).

Conclusions

Dexamethasone was as effective and as safe as ondansetron in preventing PONV. Dexamethasone should be encouraged as an alternative to ondansetron for preventing PONV in patients undergoing laparoscopic surgery.