Reduced White Matter Fiber Density in Patients with Multiple Sclerosis

Introduction: Improved understanding of multiple sclerosis (MS) symptomatology, disease mechanisms, and clinical effectiveness can be achieved by investigating microstructural damage. The aim was to gain deeper insights into changes in white matter (WM) tracts in MS patients. Methods: Diffusion magnetic resonance imaging-based tractography was utilized to segment WM tracts into regions of interest for further quantitative analysis. However, tractography is susceptible to false-positive findings, reducing its specificity and clinical feasibility. To address these limitations, the Convex Optimization Modeling for Microstructure Informed Tractography (COMMIT) technique was used. COMMIT was used to derive measures of intracellular compartment (IC) and isotropic compartments from multishell diffusion data of 40 healthy controls (HCs) and 40 MS patients. Results: The analysis revealed a widespread pattern of significantly decreased IC values in MS patients compared with HCs across 61,581 voxels (pFWE < 0.05, threshold-free cluster enhancement [TFCE] corrected). Similar WM structures studied using the fractional anisotropy (FA) value also showed a reduction in FA among MS patients compared with HCs across 57,304 voxels (pFWE < 0.05, TFCE corrected). Out of the 61,581 voxels exhibiting lower IC, a substantial overlap of 47,251 voxels (76.72%) also demonstrated lower FA in MS patients compared with HCs. Discussion: The data suggested that lower IC values contributed to the explanation of FA reductions. In addition, IC showed promising potential for evaluating microstructural abnormalities in WM in MS, potentially being more sensitive than the frequently used FA value.

Study of structural network connectivity using DTI tractography in insomnia disorder

Most of tractography studies on insomnia disorder (ID) have reported decreased structural connectivity between cortical and subcortical structures. Tractography based on standard diffusion tensor imaging (DTI) can generate high number of false-positive streamlines connections between gray matter regions. In the present study, we employed the convex optimization modeling for microstructure informed tractography-2 (COMMIT2) to improve the accuracy of the reconstructed whole-brain connectome and filter implausible brain connections in 28 patients with ID and compared with 27 healthy controls. Then, we used NBS-predict (a prediction-based extension to the network-based statistic method) in the COMMIT2-weighted connectome. Our results revealed decreased structural connectivity between subregions of the left somatomotor, ventral attention, frontoparietal, dorsal attention and default mode networks in the insomnia group. Moreover, there is a negative correlation between sleep efficiency and structural connectivity within the left frontoparietal, visual, default mode network, limbic, dorsal attention, right dorsal attention as well as right default mode networks. By comparing with standard connectivity analysis, we showed that by removing of false-positive streamlines connections after COMMIT2 filtering, abnormal structural connectivity was reduced in patients with ID compared to controls. Our results demonstrate the importance of improving the accuracy of tractography for understanding structural connectivity networks in ID.

Circulating levels of miR125a, miR126, and miR146a-5p in patients with obstructive sleep apnea and their relation with markers of endothelial dysfunction

BACKGROUND

obstructive sleep apnea (OSA) is a prevalent sleep disorder that is associated with increased risk factors for cardiovascular diseases (CVDs). Oxidative stress, insulin resistance, inflammation, and endothelial dysfunction are increased in OSA patients and microRNAs (miRs) are regulatory elements that influence these pathological mechanisms. miR125a, miR126, and miR146a-5p play a role in these pathological mechanisms and have not been evaluated in patients with OSA.

METHOD

This case-control study was performed on 90 OSA patients and 34 controls. Circulating levels of miR125a, miR126, and miR146a-5 were determined using real-time PCR, and serum levels of hsCRP, ICAM-1, and VCAM-1 were evaluated using ELISA kits.

RESULTS

miR125a and miR146a were elevated in patients with OSA compared to controls while miR126 decreased significantly. All three miRs indicated a remarkable difference between the mild-OSA group compared to the severe-OSA group. Furthermore, patients with OSA showed elevated levels of hsCRP, ICAM-1, and VCAM-1. Multiple linear regression indicated an independent association of miR125a with ICAM-1 and hsCRP, miR126 associated with VCAM-1 and total cholesterol, and miR146a-5p represented an association with apnea-hypopnea index and ICAM-1. Furthermore, miR146a-5p illustrated a good diagnostic ability to differentiate between OSA and controls.

CONCLUSIONS

Circulating miR125a, miR126, and miR146a-5p fluctuations in patients with OSA and their relations with markers of endothelial dysfunction provide in vivo evidence and suggest a potential role for these miRs with endothelial dysfunction in patients with OSA.

Lack of structural brain alterations associated with insomnia: findings from the ENIGMA-Sleep Working Group

Existing neuroimaging studies have reported divergent structural alterations in insomnia disorder (ID). In the present study, we performed a large-scale coordinated meta-analysis by pooling structural brain measures from 1085 subjects (mean [SD] age 50.5 [13.9] years, 50.2% female, 17.4% with insomnia) across three international Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA)-Sleep cohorts. Two sites recruited patients with ID/controls: Freiburg (University of Freiburg Medical Center, Freiburg, Germany) 42/43 and KUMS (Kermanshah University of Medical Sciences, Kermanshah, Iran) 42/49, while the Study of Health in Pomerania (SHIP-Trend, University Medicine Greifswald, Greifswald, Germany) recruited population-based individuals with/without insomnia symptoms 75/662. The influence of insomnia on magnetic resonance imaging-based brain morphometry using an insomnia brain score was then assessed. Within each cohort, we used an ordinary least-squares linear regression to investigate the link between the individual regional cortical and subcortical volumes and the presence of insomnia symptoms. Then, we performed a fixed-effects meta-analysis across cohorts based on the first-level results. For the insomnia brain score, weighted logistic ridge regression was performed on one sample (Freiburg), which separated patients with ID from controls to train a model based on the segmentation measurements. Afterward, the insomnia brain scores were validated using the other two samples. The model was used to predict the log-odds of the subjects with insomnia given individual insomnia-related brain atrophy. After adjusting for multiple comparisons, we did not detect any significant associations between insomnia symptoms and cortical or subcortical volumes, nor could we identify a global insomnia-related brain atrophy pattern. Thus, we observed inconsistent brain morphology differences between individuals with and without insomnia across three independent cohorts. Further large-scale cross-sectional/longitudinal studies using both structural and functional neuroimaging are warranted to decipher the neurobiology of insomnia.

Discriminating Paradoxical and Psychophysiological Insomnia Based on Structural and Functional Brain Images: A Preliminary Machine Learning Study

Insomnia disorder (ID) is a prevalent mental illness. Several behavioral and neuroimaging studies suggested that ID is a heterogenous condition with various subtypes. However, neurobiological alterations in different subtypes of ID are poorly understood. We aimed to assess whether unimodal and multimodal whole-brain neuroimaging measurements can discriminate two commonly described ID subtypes (i.e., paradoxical and psychophysiological insomnia) from each other and healthy subjects. We obtained T1-weighted images and resting-state fMRI from 34 patients with ID and 48 healthy controls. The outcome measures were grey matter volume, cortical thickness, amplitude of low-frequency fluctuation, degree centrality, and regional homogeneity. Subsequently, we applied support vector machines to classify subjects via unimodal and multimodal measures. The results of the multimodal classification were superior to those of unimodal approaches, i.e., we achieved 81% accuracy in separating psychophysiological vs. control, 87% for paradoxical vs. control, and 89% for paradoxical vs. psychophysiological insomnia. This preliminary study provides evidence that structural and functional brain data can help to distinguish two common subtypes of ID from each other and healthy subjects. These initial findings may stimulate further research to identify the underlying mechanism of each subtype and develop personalized treatments for ID in the future.

IL-1α and TNF-α as an inducer for ROS-mediated NLRP1/NLRP3 inflammasomes activation in mononuclear blood cells from individuals with chronic insomnia disorder

BACKGROUND

There are some evidence that cytokines may play an important role in sleep deprivation; however, the underlying mechanisms are still unknown. So, the present study aim to evaluate the relationship between NLRP1 and NLRP3 inflammasomes activation of blood cells and serum levels of cytokines in individuals with chronic insomnia disorder (CID).

METHODS

Blood samples were collected from 24 individuals with CID and 24 healthy volunteers. The inflammasomes activation was evaluated using real time PCR of NLRP1, NLRP3, ASC, and Caspase-1; western blot of NLRP1 and NLRP3; caspase-1 activity assay; and serum levels of IL-1β, IL-18 and other cytokines using enzyme-linked immunosorbent assay (ELISA). ROS generation in blood cells were detected by flow cytometry assay. As well, MRI scans were obtained on a Siemens Magnetom Avanto 1.5 T MRI whole body scanner using an 8-channel head coil.

RESULTS

We found the increased activity of NLRP1 and NLRP3 inflammasomes in blood cells; the increased serum levels of pro-inflammatory cytokines; and the decreased serum levels of IL-10 and TGF-β in individuals with CID. We observed significant correlation between increased serum concentration of IL-1β and the severity of insomnia in individuals with CID. The levels of ROS in blood cells was found to be correlated with IL-1α and TNF-α concentrations in serums from individuals with CID. Moreover, the included individuals with CID demonstrated the increased right-cerebellum-cortex and lateral ventricle MD bilaterally compared to controls.

CONCLUSIONS

This study provided new insights on the pathogenesis of CID and the effects of cytokines on inflammasome activation.

Controlling risky behavior associated with AIDS: the role of social support, family functioning, self-efficacy and AIDS risk perception

Objectives

We believe that major steps can be taken towards Acquired Immunodeficiency Syndrome (AIDS) prevention through identifying the relevant factors that are apt to predict risky behavior. The main purpose of the present study was to analyze and evaluate the relationship of social support, family functioning, self-efficacy and AIDS risk perception to controlling risky behavior associated with AIDS.

Methods

To conduct this cross-sectional study, 765 subjects (59% female) were selected from the youth inhabiting the western provinces of Iran through cluster sampling. Five questionnaires were used: AIDS risk perception, self-efficacy in controlling risky behavior associated with AIDS, controlling risky behavior associated with AIDS, the multidimensional scale of perceived social support, and the family assessment device.

Results

The results demonstrated that all two models enjoyed acceptable fitness, and the mediating roles of self-efficacy and AIDS risk perception were confirmed. Moreover, family functioning and perceived social support together could predict 20% of the variance of controlling risky behavior associated with AIDS. The results also indicated that family functioning with a standardized coefficient of − 0.24 and self-efficacy in controlling risky behavior associated with AIDS with a standardized coefficient of 0.58 could predict the controlling risky behavior associated with AIDS (p < 0.01).

Conclusions

Our findings suggest that self-efficacy and AIDS risk perception play major roles in controlling risky behavior associated with AIDS. Therefore, it is recommended that families and psychologists promote self-efficacy in order to prevent the occurrence of high-risk behaviors.

ENIGMA-Sleep: Challenges, opportunities, and the road map

Neuroimaging and genetics studies have advanced our understanding of the neurobiology of sleep and its disorders. However, individual studies usually have limitations to identifying consistent and reproducible effects, including modest sample sizes, heterogeneous clinical characteristics and varied methodologies. These issues call for a large-scale multi-centre effort in sleep research, in order to increase the number of samples, and harmonize the methods of data collection, preprocessing and analysis using pre-registered well-established protocols. The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium provides a powerful collaborative framework for combining datasets across individual sites. Recently, we have launched the ENIGMA-Sleep working group with the collaboration of several institutes from 15 countries to perform large-scale worldwide neuroimaging and genetics studies for better understanding the neurobiology of impaired sleep quality in population-based healthy individuals, the neural consequences of sleep deprivation, pathophysiology of sleep disorders, as well as neural correlates of sleep disturbances across various neuropsychiatric disorders. In this introductory review, we describe the details of our currently available datasets and our ongoing projects in the ENIGMA-Sleep group, and discuss both the potential challenges and opportunities of a collaborative initiative in sleep medicine.

Relationship between Sleep Problems and Self-Injury: A Systematic Review

Objective/Background: Previous studies suggested that sleep problems were related to non-suicidal self-injury. The current systematic review investigated more thoroughly this relationship.Methods: PubMED and Embase databases were searched. The keywords were "self-injury" OR "self-harm" OR "non-suicidal self-injury" OR "self-injurious behavior" OR "self-destructive behavior" OR "self-mutilation" AND "sleep problem" OR "sleep disturbance" OR insomnia OR nightmare OR "poor sleep quality" or "sleep disorders." A total of 16 studies were included in the present review.Results: The pattern of results indicated that sleep problems such as short sleep duration, sleep disturbances, and poor sleep quality were associated with non-suicidal self-injury. Additionally, emotional dysregulation, depression, and post-traumatic stress disorder appeared to mediate this relationship. Above all adolescents and young adults with sleep disruptions were at higher risk of non-suicidal self-injury.Conclusions:g Interventions to improve sleep quality and sleep duration might concomitantly decrease the risk of non-suicidal self-injury.

Increased the circulating levels of malondialdehyde in patients with obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

Obstructive sleep apnea (OSA) is a prevalent sleep disorder associated with increased risk of cardiovascular disease. Several studies have demonstrated elevated oxidative stress in patients with OSA. This oxidative stress is a direct inducer of lipid peroxidation. Malondialdehyde (MDA), a robust marker of lipid peroxidation, has been evaluated in patients with OSA but results have been inconsistent. The present systematic review and meta-analysis was performed to quantify the circulating levels of MDA in patients with OSA compared to controls.

METHODS

Search was performed in data bases of PubMed, Scopus, EMBASE, Web of Science, and Cochrane library, to find out those studies that measured MDA in patients with OSA compared to controls.

RESULTS

The search produced 563 records and after removing duplicates, 383 records remained. Screening by title and abstract and the evaluation of the full text resulted in the selection of 14 articles, which were included in the meta-analysis. Pooled analysis demonstrated higher levels of MDA in the patients compared to the controls (SMD (95% CI): 1.18 (0.68, 1.68), p < 0.0001).

CONCLUSION

The results of this meta-analysis demonstrated considerable elevation of MDA in patients with OSA compared to controls. The meta-analysis also indicated a positive association of MDA levels with the degree of severity of OSA. These results suggest a state of increased lipid peroxidation in patients with OSA.

Alterations of Subcortical Brain Structures in Paradoxical and Psychophysiological Insomnia Disorder

Insomnia disorder (ID) is a common illness associated with mood and cognitive impairments. Subtyping ID is an ongoing debate in sleep medicine, but the underlying mechanisms of each subtype is poorly understood. Growing evidence suggests that subcortical brain structures play the key roles in pathophysiology of ID and its subtypes. Here, we aimed to investigate structural alteration of subcortical regions in patients with two common ID subtypes i.e., paradoxical and psychophysiological insomnia. Fifty-five patients and 49 healthy controls were recruited for this study and T1-weighted images and subjective and objective sleep parameters (i.e., Pittsburgh Sleep Quality Index and polysomnography) were collected from participants. Subcortical structures including the hippocampus, amygdala, caudate, putamen, globus pallidus, nucleus accumbens, and thalamus were automatically segmented in FSL. Volume and shape (using surface vertices) of each structure were compared between the groups, controlled for covariates, and corrected for multiple comparisons. In addition, correlations of sleep parameters and surface vertices or volumes were calculated. The caudate's volume was smaller in patients than controls. Compared with controls, we found regional shrinkage in the caudate, nucleus accumbens, posterior putamen, hippocampus, thalamus, and amygdala in paradoxical insomnia and shrinkage in the amygdala, caudate, hippocampus, and putamen in psychophysiological insomnia. Interestingly, comparing two patients groups, shape alteration in the caudate, putamen, and nucleus accumbens in paradoxical insomnia and shrinkage in the thalamus, amygdala, and hippocampus in psychophysiological insomnia were observed. Both subjective and objective sleep parameters were associated with these regional shape alterations in patients. Our results support the differential role of subcortical brain structures in pathophysiology of paradoxical and psychophysiological insomnia.

Circulating levels of oxidized low-density lipoprotein in patients with obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with an increased risk of developing atherosclerotic cardiovascular disease (ASCVD). Patients with OSA have increased levels of oxidative stress and several studies have shown higher levels of oxidative stress markers. Oxidized-LDL (Ox-LDL) is an important risk factor for ASCVD and a number of studies have measured its levels in patients with OSA, though results from these studies are conflicting. This meta-analysis aimed to reassess circulating levels of Ox-LDL in patients with OSA in comparison with controls.

METHODS

Studies evaluating Ox-LDL levels in patients with OSA and controls were explored in databases of PubMed, EMBASE, Scopus, and Web of Science. Two authors independently performed the search from January 1990 to February 2019. Two authors independently screened the studies according to title, abstract, and full text. In addition, the Newcastle-Ottawa Quality Assessment Scale was utilized to evaluate the quality of the studies. The impact of OSA on Ox-LDL levels was determined using the random effects model.

RESULTS

Of 195 articles retrieved, 98 were duplicates, 49 were excluded by title, 20 excluded by abstract, and 22 by full texts. Six eligible studies were included in the meta-analysis. Pooled analysis demonstrated that Ox-LDL increased in patients with OSA compared with controls. In addition, subgroup analysis revealed that studies matching age or BMI between OSA patients and controls showed no significant difference between patients with OSA and healthy controls, while unmatched studies had higher levels of Ox-LDL in patients with OSA in comparison with controls.

CONCLUSION

This study demonstrated higher circulating concentrations of Ox-LDL in patients with OSA. However, no significant difference was found in studies in which patients and controls were matched for age and BMI, suggesting the involvement of these two confounding factors as a cause for elevated concentrations of circulating Ox-LDL in patients with OSA.

The impact of continuous positive airway pressure therapy on circulating levels of malondialdehyde: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder which associated with increased oxidative stress and cardiovascular diseases. Malondialdehyde (MDA) is a reliable marker of lipid peroxidation and is elevated in patients with OSA. Studies reported inconsistent findings on the effect of continuous positive airway pressure (CPAP) therapy on MDA levels. As the study power maybe a reason for the inconsistent findings, we aimed to use meta-analysis to assess effect of CPAP therapy on MDA in patients with OSA.

METHOD

Electronic search was performed to find out studies on the effect of CAPA on MDA levels in OSA patients. Search carried out in databases of PubMed, EMBASE, Scopus, Cochrane library and web of science.

RESULTS

Search resulted in 161 records of which 83 remained after removing duplicated records. Further, 51 articles were removed by title and abstract and 22 records evaluated by full text. Finally 13 articles were included in the intended meta-analysis. Pooled analysis demonstrated that CPAP therapy reduced MDA levels significantly [SMD (-1.51) (95% CI, -2.06 to -0.97) p < 0.05]. Subgroup analyses showed that CPAP therapy was effective in categories of age (≤50 and > 50 years), BMI (≤30 and > 30 kg/m²) and therapy duration (≤12 week and >12 week).

CONCLUSION

the results of the present study demonstrated considerable effect of CPAP therapy on MDA as independent risk factor for cardiovascular diseases and robust marker of lipid peroxidation.

Impact of low level radiation on concentrations of some trace elements in radiation workers

INTRODUCTION

Small variations in trace element levels may cause important physiological changes in the human body. This study aims to evaluate five important trace elements in radiation workers.

METHOD

In this study, 44 radiation workers and an equal number of non-radiation workers were selected as the case and control group, respectively. The concentrations of iron, magnesium, zinc, copper, and selenium in the serum of the participants were measured using an Atomic Absorption Spectrometry (AAS).

RESULTS

The mean concentrations of iron, magnesium, zinc, copper, and selenium for the case group were 107.3 µg/dl, 2.3 mg/dl, 80.9 µg/dl, 112.6 µg/dl and 216.7 ng/ml, respectively. The results for the control group were 121.9 µg/dl, 2.3 mg/dl, 82.3 µg/dl, 112.8 µg/dl and 225.2 ng/ml, respectively.

CONCLUSIONS

The mean concentration of iron in the case group was significantly lower than the control group (p-value = 0.012), while the concentrations of other elements in both of the groups were not significantly different. In the case group, except magnesium (p-value = 0.021), no significant relationship was found between age and the elemental concentrations. According to Spearman's test, there was a meaningful statistical correlation between the sex and concentration of iron, Mg, Zn, and Se. Also, the correlation between the concentration of magnesium and the weights of radiation workers was significant (p-value =0.044).

Detection of structural abnormalities of cortical and subcortical gray matter in patients with MRI-negative refractory epilepsy using neurite orientation dispersion and density imaging

PURPOSE

NODDI (Neurite Orientation Dispersion and Density Imaging) and DTI (Diffusion tensor imaging) may be useful in identifying abnormal regions in patients with MRI-negative refractory epilepsy. The aim of this study was to determine whether NODDI and DTI maps including neurite density (ND), orientation dispersion index (ODI), mean diffusivity (MD) and fractional anisotropy (FA) can detect structural abnormalities in cortical and subcortical gray matter (GM) in these patients. The correlation between these parameters and clinical characteristics of the disease was also investigated.

METHODS

NODDI and DTI maps of 17 patients were obtained and checked visually. Region of interest (ROI) was drawn on suspected areas and contralateral regions in cortex. Contrast-to-noise ratio (CNR) was determined for each region. Furthermore volumetric data and mean values of ND, ODI, FA and MD of subcortical GM structures were calculated in both of the patients and controls. Finally, the correlations of these parameters in the subcortical with age of onset and duration of epilepsy were investigated.

RESULTS

Cortical abnormalities on ODI images were observed in eight patients qualitatively. CNR of ODI was significantly greater than FA and MD. The subcortical changes including decrease of FA and ND and increase of ODI in left nucleus accumbens and increase of the volume in right amygdala were detected in the patients.

CONCLUSIONS

The results revealed that NODDI can improve detection of microstructural changes in cortical and subcortical GM in patients with MRI negative epilepsy.

Designing and Dosimetry of a Shield for Photon Fields of Radiation Therapy in Oral Cavity Cancer

The cancer of oral cavity is related to lesions of mucous membrane of tongue and gum that can be treated with radiation therapy. A lateral photon field can be used to treat this kind of tumor, which has a side-effect on normal tissue in the opposite side of the oral cavity. In this study the dosimetric effect of the various shields in oral cavity is evaluated. In this study, a special phantom similar to the structure of oral cavity with capability of film dosimetry was designed and constructed. The various shield slabs were made of five materials: Lead, Plexiglas, Acrylic resin, Silicon and Plaster. For irradiation, Cobalt 60 (60Co) and 6 MV photon beams were used. The film dosimetry before and after the shield was performed using GAFCHROMIC EBT2 films. The film before the shield measures the magnitude of backscattering radiation from the shield. The prescribed dose was 150 cGy. Results showed that 3 cm of the lead in both energies had the maximum absorption of radiation. The absorbed dose to opposite side of shield for 6 MV photon beams and 60Co were 21 and 32 cGy, respectively. The minimum attenuation on radiation was observed in silicon shield for which the dose of opposite side were 116 and 147 cGy for 6 MV and 60Co respectively. The maximum backscattered dose was measured 177 cGy and 219 cGy using 3 cm thickness of lead, which was quite considerable. The minimum backscattering where for acrylic resin 101 and 118 cGy for 6 MV and cobalt. In this study, it was concluded that the amount of backscattering for 3 cm Lead shield is quite considerable and increases the dose significantly. A composite layer of shield with 1-2 cm lead and 1 cm acrylic resin can have the protective effect and low backscattering radiation at the same time.

Monte Carlo simulation and film dosimetry for electron therapy in vicinity of a titanium mesh

Titanium (Ti) mesh plates are used as a bone replacement in brain tumor surgeries. In the case of radiotherapy, these plates might interfere with the beam path. The purpose of this study is to evaluate the effect of titanium mesh on the dose distribution of electron fields. Simulations were performed using Monte Carlo BEAMnrc and DOSXYZnrc codes for 6 and 10 MeV electron beams. In Monte Carlo simulation, the shape of the titanium mesh was simulated. The simulated titanium mesh was considered as the one which is used in head and neck surgery with a thickness of 0.055 cm. First, by simulation, the percentage depth dose was obtained while the titanium mesh was present, and these values were then compared with the depth dose of homogeneous phantom with no titanium mesh. In the experimental measurements, the values of depth dose with titanium mesh and without titanium mesh in various depths were measured. The experiments were performed using a RW3 phantom with GAFCHROMIC EBT2 film. The results of experimental measurements were compared with values of depth dose obtained by simulation. In Monte Carlo simulation, as well as experimental measurements, for the voxels immediately beyond the titanium mesh, the change of the dose were evaluated. For this purpose the ratio of the dose for the case with titanium to the case without titanium was calculated as a function of titanium depth. For the voxels before the titanium mesh there was always an increase of the dose up to 13% with respect to the same voxel with no titanium mesh. This is because of the increased back scattering effect of the titanium mesh. The results also showed that for the voxel right beyond the titanium mesh, there is an increased or decreased dose to soft tissues, depending on the depth of the titanium mesh. For the regions before the depth of maximum dose, there is an increase of the dose up to 10% compared to the dose of the same depth in homogeneous phantom. Beyond the depth of maximum dose, there was a 16% decrease in dose. For both 6 and 10 MeV, before the titanium mesh, there was always an increase in dose. If titanium mesh is placed in buildup region, it causes an increase of the dose and could lead to overdose of the adjacent tissue, whereas if titanium mesh is placed beyond the buildup region, it would lead to a decrease in dose compared to the homogenous tissue.

An investigation of gamma background radiation in Hamadan province, Iran

The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province.

The ability of hippocampal CA1 area for induction of long-term potentiation is persistently reduced by prior treatment with cysteamine: an in vitro study

Using field potential recording in the CA1 region of hippocampal slices from rats injected with cysteamine (200 mg/kg, s.c.), changes in activity and plasticity of Schaffer collateral-CA1 pyramidal cell synapses were examined. Extracellular field potential recording prior to and following either theta-pattern primed bursts (PBs), perfusion with low Mg(2+) or with high Ca(2+), indicated long-term potentiation (LTP) of population spikes amplitude (PSA). The extent of LTP of PSA was significantly lower in cysteamine-treated rats. It is concluded that cysteamine can entail lasting modifications in susceptibility of hippocampal CA1 for synaptic plasticity induced by tetanus. Similarly, disability in function of CA1 synapses can be traced by other protocols of LTP induction. The relevancy of the results to the facilitatory role of endogenous somatostatin in the function of Schaffer collateral-CA1 pyramidal cell synapses is also discussed.

Anticonvulsant action of 2-chloroadenosine injected focally into the perirhinal cortex in amygdaloid kindled rats

Possible anticonvulsant effects of 2-chloroadenosine injected focally into the perirhinal cortex of amygdala kindled rats were investigated over a 2 h period. Animals were microinfused (1 microl) with 2-chloroadenosine (2-CLA; 5, 10, 15, 25 and 100 nM) or artificial cerebrospinal fluid applied through a cannula located in the perirhinal cortex. At the doses employed, 2-CLA significantly reduced afterdischarge duration and stage 5 seizure duration. The latency to stage 4 seizure was increased only at the highest dose of 2-CLA (100 nM), while even at this dose no significant change in seizure stage could be seen. The maximum effect of 2-CLA was obtained 30 min after microinfusion of the drug. Pre-treatment (intraperirhinal cortex) of animals with the nonselective adenosine antagonist, caffeine (50 microM; 1 microl), blocked the anticonvulsant activity of 2-CLA. These results suggest that adenosine receptors located in the perirhinal cortex may play an important role in the suppression of seizure activity elicited from the amygdala.

Intra-amygdala infusion of 2-chloroadenosine suppresses amygdala-kindled seizures

The seizure-modulating effects of 2-chloroadenosine (2-CLA) infused directly into the amygdala were investigated. Different groups of amygdala-kindled rats were infused (1 microliter) with 2-CLA (0.25, 1, 10 and 25 nM), caffeine (200 microM and 2 mM), a combination of the two or artificial cerebrospinal fluid (ACSF) applied directly through a cannula located in the amygdala. Infusion of 2-CLA dramatically suppressed seizure stage (SS), after discharge duration (ADD) and stage 5 seizure duration (S5D), while the latency to bilateral forelimb clonus (S4L) was significantly prolonged. These anticonvulsant effects were evident after 5 min, reached a maximum at the 60 min time point and were still detectable 360 min post-2-CLA infusion. Pretreatment with caffeine blocked the anticonvulsant effects of 2-CLA dose-dependently. These results may suggest that in amygdaloid-kindled rats, adenosine receptors located in the amygdala play a major role in the expression of the anticonvulsant activity of 2-CLA.