Background and Aims: Disc displacement is the most common temporomandibular joint disorder and magnetic resonance imaging (MRI) is the gold standard in its diagnosis. This disorder can lead to changes in signal intensity of magnetic resonance (MR). The purpose of this study was evaluation of correlation between relative signal intensity of MR images of retrodiscal tissue, superior and inferior head of lateral ptrygoid muscle with type of anterior disk displacement and condylar head flattening in patients with temporomandibular disorder (TMD).Materials and Methods: In this retrospective study, 31 MR images of patients who had anterior disc displacement were evaluated. After relative signal intensity measurement for retrodiscal tissue, superior and inferior head of lateral ptrygoid muscle, the correlation between relative signal intensity and type of anterior disc displacement was evaluated with repeated measure ANOVA test. In each of these 3 areas, t-test was used to compare the groups with and without condylar head flattening.Results: The correlation between relative signal intensity of MR images and type of anterior disc displacement in retrodiscal tissue, superior and inferior head of lateral ptrygoid muscle was not significant. There was also no statistically significant correlation between relative signal intensity of MR images and flattening of condylar head in retrodiscal tissue, superior and inferior head of lateral ptrygoid muscle (P>0.05).Conclusion: According to findings of this study, relative signal intensity of MR images in retrodiscal tissue, superior and inferior head of ptrygoid muscle is not a good predictor for type of anterior disc displacement and flattening of condylar head. It seems that this cannot be used as a diagnostic marker for TMD progression.

Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion torque (IT) (final torque force) and resonance frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

Background: The study of the molecular dynamics of proteins based on internal motions is crucial for understanding the mechanism of protein function. Internal movements of proteins play an important role in both protein folding processes and the mechanism of action of enzyme. Knowledge about these movements will help us in understanding these processes correctly. Osmolites are small organic molecules which are utilized by the cells of all organisms, except hallobacteria. Osmolites are produced under extreme stressful conditions in order to help in stabilizing macro-molecules and retaining their biological function. They interact directly with macromolecules, but they exert their effect only when the characteristics or conditions of the solvent present around the cell change. Therefore, their presence affects the stability of the protein indirectly.Materials and Methods: In this work we studied the effect (s) of the osmolite Sorbitol on the dynamics of Hen Egg White Lysozyme, and through our study we used NMR Hydrogen-Deuterium Exchange to characterize the effect (s). We performed spectrometery in two different conditions, in the absence and presence of sorbitol. The extent of peptide hydrogen exchange was assigned as a function time and in a decreasing manner in the intensity of the peak corresponding to amino acids. The resulting TOCSY spectra were assigned using SPARKY software, as well as we integrated the peaks using this software.Results: The speed of hydrogen exchange, hydrogen atoms of the peptide bond, will give us information about the local structural oscillations where the exchange is taking place. The rate of hydrogen exchange varies from one amino acid to another, and the intensity of the peak of these hydrogen decreases as time passes by.Conclusion: We found that the presence of sorbitol causes a decrease in proton exchange rate, and since there is no noticeable chemical shifts in the peaks of the spectra, in the presence or absence of sorbitol, we can conclude that sorbitol did not cause any change in the three dimensional structure. It seems that the decrease in the rate of exchange is a representative of a decrease in the accessible surface area or to strengthening of hydrogen bonds, and sorbitol caused one of these two possibilities.

Tumor detection and isolation in magnetic resonance imaging (MRI) is a significant consideration, but when done manually by people, it is very time consuming and may not be accurate. Also, the appearance of the tumor tissue varies from patient to patient, and there are similarities between the tumor and the natural tissue of the brain. In this paper, we have tried to provide an automated method for diagnosing and displaying brain tumors in MRI images. Images of patients with glioblastoma were used after applying pre-processing and removing areas that have no useful information (such as eyes, scalp, etc.). We used a bounding box algorithm, to create a projection for to determining the initial range of the tumor in the next step, an artificial bee colony algorithm, to determine an initial point of the tumor area and then the Grow cut algorithm for, the exact boundary of the tumor area. Our method is automatic and extensively independent of the operator. comparison between results of 12 patients in our method with other similar methods indicate a high accuracy of the proposed method (about 98%) in comparison s.

Resonance and ferroresonance in power systems are categorized as two destructive phenomena especially in HV networks which their occurrence are being initiated in consequence of a power system event. Also, Ferroresonance phenomenon may be initiated by non-power system event such as lightning strike. Hence, the study of resonance and ferroresonance requires an exhaustive evaluation of possible network events in different network configurations. In each event, the analysis of network voltages is conducted based on identified allowable limits by IEEE 519 standard as an evaluation critera. In this paper, a novel comprehensive study approach is proposed for study of ferroresonance phenomena in power networks. The proposed approach comprises different steps including substation equipment modeling, EMT simulation of the probable switching events, evaluation of correspondence results, and finally detecting the probable ferroresonance occurrence. Furthermore, a novel approach for resonance study is also presented. Voltage and current limits are implemented to define an impedance criteria for performing resonance evaluation of network buses. Findings – The proposed method is implemented for study of resonance and ferroresonance in all HV substations of the Khuzestan regional electricity network. By performing the proposed evaluations, the probable condition which may lead to resonance and ferroresonance occurrence are identified. The results are highly valuable for network operators in prevention of unintended overvoltages occurrence.

Background: Differentiation between benign and malignant parotid tumors before surgery is important because it can change the therapeutic planning for patients. In this study we evaluated the role of Magnetic resonance spectroscopy (MRS) in differentiation of benign from malignant parotid tumors. Materials and Methods: 40 patients entered with salivary gland tumor especially parotid) that candidated for surgery in this study. Patients selected in Amiralam hospital and did MRI in Imam Khomeini hospital. In this study, on these patients Magnetic resonance spectroscopy (MRS) was performed at 135 and 270 Time of Echo, and the choline/creatine ratio was determined. Regarding to the cytological results, patient divided to warthin, benign and malignant tumors and ROC curves used to determine the best cut off points. Results: 40 patients entered in this study, 25 had benign non warthin tumors, 9 malignant tumors and 6 warthin tumors. In differentiation benign from malignant tumors TE136 was stronger. The best cut off point of Choline to Creatine ratio in TE: 136 was 1. 92 with sensitivity 81 % and specificity 89% and in TE 270 was 1. 76 with Sensitivity 89% and specificity 71%. Choline/creatine ratio <1. 25 can rule out the malignancy with sensitivity of 92% and ratio > 1. 76 strongly suggest malignancy (with10% specificity). MRS was not able to differentiate benign non warthin from warthin tumors. Conclusion: According to this study, Choline/ creatine ratio in MRSpectroscopy can be helpful as noninvasive method in differentiation of benign from malignant tumors.

Background and purpose: The complexity of anatomical variation of Willis circle (CW) has made it susceptible to variation. The goal of this study was to determine the prevalence of the CW variations using magnetic resonance angiography (MRA) without contrast agent in patients attending Sari Imam Khomeini Hospital.Materials and methods: In a cross-sectional study, 200 subjects referring for MRA were analyzed. Variables included hypoplasia, agenesis, stenosis, aneurysm, dolichoectasia, fenestration and duplication. Logistic regression model was applied to estimate the association between variation states in CW and other variables.Results: The most common variation was hypoplasia in left and right posterior communicating arteries (n=118 (59.3%) and n=107 (54%), respectively). Stenosis and dolichoectasia were more prevalent in anterior cerebral artery and basilar artery, respectively. Among the participants 90 (45%) were diagnosed with stenosis and 31 (15.5%) were reported to have dolichoectasia.Conclusion: Typical circles were seen only in 28 (14%) individuals and the rest had other variations. Therefore, MRA could be beneficial for diagnosis, treatment and prognosis.