Contribution of somatic and dendritic SK channels in the firing rate of deep cerebellar nuclei: implication in cerebellar ataxia

Introduction: Loss of inhibitory output from Purkinje cells leads to hyperexcitability of the Deep Cerebellar Nuclei [DCN], which results in cerebellar ataxia. Also, inhibition of small-conductance calcium-activated potassium [SK] channel increases firing rate of DCN, which could cause cerebellar ataxia. Therefore, SK channel activators can be effective in reducing the symptoms of this disease, and used for the treatment of cerebellar ataxia. In this regard, we hypothesized that blockade of SK channels in different compartments of DCN would increase firing rate with different value. The location of these channels has different effects on increasing firing rate

Methods: In this study, multi-compartment computational model of DCN was used. This computational stimulation allowed us to study the changes in the firing activity of DCN neuron without concerns about interfering parameters in the experiment

Results: The simulation results demonstrated that blockade of somatic and dendritic SK channel increased the firing rate of DCN. In addition, after hyperpolarization [AHP] amplitude increased with blocking SK channel, and its regularity and resting potential changed. However, action potentials amplitude and duration had no significant changes. The simulation results illustrated a more significant contribution of SK channels on the dendritic tree to the DCN firing rate. SK channels in the proximal dendrites have more impact on firing rate compared to distal dendrites

Discussion: Therefore, inhibition of SK channel in DCN can cause cerebellar ataxia, and SK channel openers can have a therapeutic effect on cerebellar ataxia. In addition, the location of SK channels could be important in therapeutic goals. Dendritic SK channels can be a more effective target compared to somatic SK channels

Effectiveness of cognitive behavioral therapy on the quality of sleep in women with multiple sclerosis: a randomized controlled trial study

Background: multiple sclerosis is accompanied by secondary clinical signs such as insomnia. Considering the side effects of drugs and also increasing acceptability of psychotherapy methods in health systems, we aimed to determine the effect of group cognitive behavioral therapy on the quality of sleep in women with multiple sclerosis in 2014

Methods: this study is a randomized controlled clinical conducted on 72 women with multiple sclerosis who referred to medical centers of Isfahan. After convenience sampling, participants were randomly allocated into two equal groups of control [n=36] and intervention [n=36]. In the intervention group, cognitive behavioral therapy was performed in 8 sessions. The control group, along with receiving the common drugs, participated in 3 group sessions and talked about their feelings and experiences. Data were gathered using Pittsburgh Sleep Quality Index [PSQI] and analyzed through independent t-test, Chi-square, Mann Whitney, ANOVA with repeated measure, using SPSS 18

Results: there was a significant difference between the mean score of sleep quality of the control and intervention groups immediately and one month after the intervention [P<0.001]. ANOVA with repeated measure test showed that the mean score of sleep quality of patients in the intervention group had a significant difference at three stages of before, immediately and one month after the intervention

Conclusions: according to the results of this study, cognitive behavioral therapy, as an effective and cost-effective therapy, could improve sleep quality in patients with multiple sclerosis

Computational insights into the neuroprotective action of riluzole on 3-acetylpyridine-induced ataxia in rats

Intra-peritoneal administration of riluzole has been shown to preserve the membrane properties and firing characteristics of Purkinje neurons in a rat model of cerebellar ataxia induced by 3-acetylpyridine [3-AP]. However, the exact mechanism[s] by which riluzole restores the normal electrophysiological properties of Purkinje neurons is not completely understood. Changes in the conductance of several ion channels, including the BK channels, have been proposed as a neuro protective target of riluzole. In this study, the possible cellular effects of riluzole on Purkinje cells from 3-AP-induced ataxic rats that could be responsible for its neuro protective action have been investigated by computer simulations. This is a computational stimulation study. The simulation environment enabled a change in the properties of the specific ion channels as the possible mechanism of action of riluzole. This allowed us to study the resulted changes in the firing activity of Purkinje cells without concerns about its other effects and interfering parameters in the experiments. Simulations were performed in the NEURON environment [Version 7.1] in a time step of 25 micro s; analyses were conducted using MATLAB r2010a [The Mathworks]. Data were given as mean +/- SEM. Statistical analyses were performed by the student's t test, and differences were considered significant if p<0.05. The computational findings demonstrated that modulation of an individual ion channel current, as suggested by previous experimental studies, should not be considered as the only possible target for the neuro protective effects of riluzole to restore the normal firing activity of Purkinje cells from ataxic rats. Changes in the conductance of several potassium channels, including voltage-gated potassium [Kv1, Kv4] and big Ca[2+]-activated K[+] [BK] channels may be responsible for the neuro protective effect of riluzole against 3-AP induced alterations in the firing properties of Purkinje cells in a rat model of ataxia

[Detection and assessment of antimicrobial resistance properties in Escherichia coli O157 isolated from pheasant, partridge, duck and goose meat]

Despite the high value of poultry meat, there is no accurate control and inspection on poultry carcasses in the slaughterhouse. Therefore, the possibility of transmission of some bacteria like Escherichia coli which is one of the main causes of food poisoning is not unexpected. The present study was carried out to detect and analyse antibiotic resistance pattern of Escherichia coli O157 isolated from pheasant, partridge, duck and goose meat in Gilan, Mazandaran, Isfahan and Fars provinces, Iran. For doing the experiments, 25, 17, 22 and 36 samples from pheasant, partridge, duck and goose chest muscle meat were collected, respectively. The samples were immediately transferred to the laboratory in cooler ice-pack. All samples were cultured and DNA was extracted from the typical bacterial colonies which represent Escherichia coli. Polymerase chain reaction was used to confirme the diagnosis and to detect O157 serogroup. Finally, the antibiotic resistance pattern was studied using simple disk diffusion method. The results showed that 27% of samples were positive for presence of Escherichia coli; 6 of them had the O157 serogroup. The goose and partridge meat had the highest and lowest frequencies of bacterium and O157 serogroup, respectively. The Escherichia coli which were isolated from poultry meat had the highest antibiotic resistance to sulfamethoxazol and vancomycinand the lowest antibiotic resistance to ciprofloxacinand gentamycin. A significant statistical difference [P < 0.05] was seen between the prevalence rate of the bacterium and O157 serogroup in goose and partridge meat and between the levels of resistance to various antibiotics. We recommended using Polymerase Chain Reaction as an accurate, rapid and safe method to control presence of some pathogens like Escherichia coli. This study showed that using simple disk diffusion method is very essential before antibiotic prescription.