The effect of a 9-month hybrid intradialytic exercise training program on nerve conduction velocity parameters in patients receiving hemodialysis therapy.

INTRODUCTION AND AIMS: Neurological complications such as peripheral neuropathy are very common in the end-stage renal disease (ESRD) patients, occurring in 60-80% of this specific population. The aim of the present study was to examine whether a 9-month hybrid intradialytic exercise training program could alter motor and sensory nerve conduction study (NCS) parameters in hemodialysis population. METHODS: Seventeen stable patients undergoing HD with no clinical evidence of uremic polyneuropathy were included in the study (15 M/2F, 59 ± 13.7 years). All patients completed a 9-month supervised exercise training program composed of both aerobic cycling and resistance training (hybrid) during HD. Functional capacity was assessed by a battery of tests, while pain levels and fatigue profile were assessed via validated questionnaires. Motor and sensory NCS on bilateral median, ulnar, peroneal and tibial nerves as well as F-wave were assessed using a full neurographic electromyography (EMG) assessment. RESULTS: After the 9-month exercise training intervention, exercise capacity was increased by 65% and functional capacity by an average of 40%. The neurological assessment showed that conduction velocity from tibial and peroneal nerves was improved by 3.7% and 4.2%, respectively, while tibial F-wave latency and peroneal and sural nerve distal latency were significantly improved by 4.2%, 4.9% and 10%, respectively. Fatigue and pain were improved after the exercise intervention while fatigue score was positively correlated with conduction velocity and amplitude values. CONCLUSIONS: The results of the current study demonstrate that 9-month hybrid exercise training induces beneficial effects on both sensory and motor NCS parameters, improving conduction velocity and F-wave latency. Improvements in neural activity were accompanied by changes in fatigue score and pain-related aspects. The parallel improvement in motor nerve conduction velocity and its correlations with functional tests supports the hypothesis that exercise could be beneficial for preventing a decline in neural function in HD patients.

Pesticides, cognitive functions and dementia: A review.

Pesticides are widely-used chemicals commonly applied in agriculture for the protection of crops from pests. Depending on the class of pesticides, the specific substances may have a specific set of adverse effects on humans, especially in cases of acute poisoning. In past years, evidence regarding sequelae of chronic, low-level exposure has been accumulating. Cognitive impairment and dementia heavily affect a person's quality of life and scientific data has been hinting towards an association between them and antecedent chronic pesticide exposure. Here, we reviewed animal and human studies exploring the association between pesticide exposure, cognition and dementia. Additionally, we present potential mechanisms through which pesticides may act neurotoxically and lead to neurodegeneration. Study designs rarely presented homogeneity and the estimation of the exposure to pesticides has been most frequently performed without measuring the synergic effects and the possible interactions between the toxicants within mixtures, and also overlooking low exposures to environmental toxicants. It is possible that a Real-Life Risk Simulation approach would represent a robust alternative for future studies, so that the safe exposure limits and the net risk that pesticides confer to impaired cognitive function can be examined. Previous studies that evaluated the effect of low dose chronic exposure to mixtures of pesticides and other chemicals intending to simulate real life exposure scenarios showed that hormetic neurobehavioral effects can appear after mixture exposure at doses considered safe for individual compounds and these effects can be exacerbated by a coexistence with specific conditions such as vitamin deficiency. However, there is an overall indication, derived from both epidemiologic and laboratory evidence, supporting an association between exposure to neurotoxic pesticides and cognitive dysfunction, dementia and Alzheimer's disease.

Cardiac autonomic function during intradialytic exercise training.

Objectives: Cardiac autonomic nervous system (ANS) dysfunction is a common feature in patients receiving hemodialysis (HD) therapy, whilst is associated with an increased risk of ventricular arrhythmias and sudden cardiac death. The aim of this study is to investigate and compare the hemodynamic changes and responses of ANS function in HD patients using pupillometry and Heart Rate Variability (HRV) parameters. Methods: Sixteen chronic kidney diseases (CKD) patients receiving HD (52.18 ± 17.7 years) underwent both pupillometric measurements using a portable handheld pupil-measuring device and standard HRV analysis pre HD, every hour and 30 min post-HD session under two different scenarios: at rest while the patient resting at HD bed and when the patient performed a single bout of intradialytic aerobic exercise lasting for 45 min during the second hour of the HD therapy. Results: No significant changes in ANS values were observed in neither of the pupillometric and the HRV values pre HD, for each hour and post-HD session. HRV parameters were significantly correlated with pupillometric parameters at pre HD and immediately after the single bout of intradialytic exercise. ANS activity did not differ during the conventional HD session and during the session included intradialytic exercise. Moreover, sympatho-vagal balance indices deriving from pupillometric assessment showed beneficial changes after the exercise event. Conclusion: Pupillometry is a promising and robust technique with fewer artifacts compared to HRV especially in studies involving exercise sessions. Thus, pupillometry can be used as a complementary tool in the evaluation of cardiac autonomic dysfunction.

Pesticide exposure and cognitive function: Results from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD).

BACKGROUND: Results from studies to date, regarding the role of chronic pesticide exposure on cognitive function remain contradictory. OBJECTIVE: To investigate the relationship between self-reported pesticide exposure and cognitive function. METHODS: Data from a population-based cohort study of older adults (HEllenic Longitudinal Investigation of Aging and Diet) in Greece was used. Pesticide exposure classification was based on 1) living in areas that were being sprayed; 2) application of spray insecticides/pesticides in their gardens; and 3) occupational application of sprays. Associations between z-scores of cognitive performance and self-reported pesticide exposure were examined with linear regression analyses. Adjusted models were applied, for all analyses. RESULTS: Non-demented individuals who reported that they had been living in areas near sprayed fields, had poorer neuropsychological performance, compared to those who had never lived in such areas. Sub-analyses revealed poorer performance in language, executive and visual-spatial functioning, and attention. These associations remained after a sensitivity analysis excluding subjects with mild cognitive impairment. CONCLUSION: Self-reported exposure to pesticides was negatively associated with cognitive performance.

Cognitive impairment in heart failure.

Cognitive impairment (CI) is increasingly recognized as a common adverse consequence of heart failure (HF). Although the exact mechanisms remain unclear, microembolism, chronic or intermittent cerebral hypoperfusion, and/or impaired cerebral vessel reactivity that lead to cerebral hypoxia and ischemic brain damage seem to underlie the development of CI in HF. Cognitive decline in HF is characterized by deficits in one or more cognition domains, including attention, memory, executive function, and psychomotor speed. These deficits may affect patients' decision-making capacity and interfere with their ability to comply with treatment requirements, recognize and self-manage disease worsening symptoms. CI may have fluctuations in severity over time, improve with effective HF treatment or progress to dementia. CI is independently associated with disability, mortality, and decreased quality of life of HF patients. It is essential therefore for health professionals in their routine evaluations of HF patients to become familiar with assessment of cognitive performance using standardized screening instruments. Future studies should focus on elucidating the mechanisms that underlie CI in HF and establishing preventive strategies and treatment approaches.

Angiotensin-converting enzyme tag single nucleotide polymorphisms in patients with intracerebral hemorrhage.

OBJECTIVES: Studies investigating the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and the risk of intracerebral hemorrhage (ICH) have provided conflicting results. Moreover, it is possible that the ACE I/D polymorphism may not represent the functional variant of the gene. The objective of this study was to clarify the influence of the ACE gene region on the risk of ICH by genotyping tag polymorphisms along ACE gene in two independent ethnically different cohorts. METHODS: We included 250 Greek and 169 Polish unrelated patients with ICH and 250 Greek and 322 Polish normal controls in the study. To cover the majority of the genetic variability across the extended ACE gene region, we identified five tag single nucleotide polymorphisms (rs4343, rs4461142, rs7221780, rs8066276, rs8066114) from the HapMap using a pairwise tagging approach and an r2 greater than or equal to 0.8. Single nucleotide polymorphisms and haplotypes were analyzed for associations with ICH risk, ICH subtype (lobar/nonlobar), and age of disease onset using logistic and Cox regression models. Correction for multiple comparisons was carried out. RESULTS: In the Polish cohort, we observed a trend toward an association between the rs4461142 and the age of ICH onset (hazard ratio 0.50, 95% confidence interval 0.27-0.90, P=0.02). A common haplotype (GTCTC) also showed a trend for increased ICH risk in the Polish cohort (odds ratio 0.19, 95% confidence interval 0.04-0.85, P=0.02). These results were not replicated in the Greek cohort. CONCLUSIONS: Our results did not provide clear evidence for a role of ACE gene in the development of ICH.