مجله دانشکده پزشکی اصفهان
پیاپی 257 (هفته سوم آذر 1392)

Cochlear implants are widely accepted as the unique and most effective way for individuals with severe to profound hearing loss to restore some degree of hearing. Speech enhancement strategies play an extremely important role in optimizing the cochlear implant. In this study, a noise reduction algorithm was proposed for cochlear implant. To improve the performance of cochlear implants in noisy environments, a noise reduction algorithm was proposed for cochlear implant that applied a spectral subtraction using the classifications between the speech and the noise dominants in each channel. The proposed classifications use the standard deviation of the spectrum of observation signal in each channel. The performance of the proposed noise reduction algorithm was evaluated by segmental signal-to-noise ratio (SNR) using Noisy92 sentences embedded in babble, car noise and train at 0–20 dB. SNR and subjective listening tests were assessed with 15 normal hearing listeners using a specific cochlear implant (CI) simulator in Clinical audiology of Isfahan University of Medical Sciences, Iran, in June 2012. In addition, to evaluate the effect of the channel on speech recognition, 6, 8 and 16 channels of filter banks were used. At all SNR values, subjects performed better with proposed enhanced algorithm by 45 percentage points. Based on comparing segmental SNR with spectral subtraction, and visually inspecting the enhanced spectrograms and subjective listening test, the proposed method was found to effectively reduce noise while minimizing distortion to speech.

Transient ischemic attack (TIA) is a frequent diagnosis in the emergency department. Currently, we have not the accurate approach for follow-up in these patients as outpatients or hospitalized. Recently, efforts have been made to stratify high-risk patients presenting with transient ischemic attack through scoring systems such as the ABCD2 score. The aim of study was assessment of ABCD2 score in Iranian population. Patients hospitalized in neurology department of Rasol Akram hospital, Tehran, Iran, in 2010 and 2011 were enrolled in this study and followed one week later. All the patients had transient ischemic attack without symptoms in brain CT scan within 24 hours of symptom onset. 100 cases participated in this study at two equal groups: ABCD2 ≤ 4 (low-risk) and ABCD2 > 4 (high-risk). The mean ABCD2 score was 4.7 ± 1.1. One week follow-up showed transient ischemic attack in 11 patients (8 in high-risk and 3 in low-risk groups).The increase of transient ischemic attack incidence and diabetes prevalence were significantly different in two groups (high-risk: P = 0.037 and low-risk: P = 0.029). Sensitivity and specificity rate of ABCD2 score were 72.7% and 52.8%, respectively According to the findings, we can say although ABCD2 score is a useful tool in determining the prognosis of patients with transient ischemic attack in the first week following but it has not high sensitivity and specificity and relying on it alonely cannot be a good result.

N-acetylcysteine (NAC), an acetylated variant of L-cysteine, is commonly used as an antidote for acetaminophen overdose and antimucolytic agent in chronic obstructive pulmonary disease. Recently, NAC is found to have anti-inflammatory and antioxidant properties. The aim of the present study was to evaluate the analgesic effect of NAC in rat model of plantar test.

Male Wistar rats were randomly divided into six groups (n = 8). Animals received either normal saline (1 ml/kg) or different doses of NAC (200, 400, 600 mg/kg), morphine (10 mg/kg), or acetaminophen (50 mg/kg) intraperitoneally and the analgesic effect was assessed by plantar test apparatus at baseline, 30, 60 and 120 minutes after drug or vehicle administration.

NAC provided significant analgesia at 30 minutes post-administration compared to control (normal saline) group while in the other time points, there were no significant differences between NAC and control group in plantar test.

We found that NAC had analgesic effect and in order to find the involved mechanisms, further studies are needed.

Pterygium is a common disease of the eye affected by environmental factors, especially climatic parameters. The purpose of this study was to evaluate the influence of climatic factors on pterygium in the cities of Mashhad and Zahedan in Iran eastern half. The data of 130,464 patients referred to Zahedan Alzahra Ophthalmology Clinic (from them, 28,776 patients with pterygium) and 974,542 patients referred to Mashhad Khatam ol-Anbia Ophthalmology Clinic (from them, 20,222 patients with pterygium) during 2006-2011 were used. Climatic data elements including sunshine hours, dusty days, wind speed, ultraviolet and total sunshine index, maximum and minimum temperature, and humidity for two stations in Zahedan and Mashhad were obtained from the Iran Meteorological Organization. To study and compare the relationship of climatic factors and pterygium, correlation model, to analyze time delays, autocorrelation functions (ACF) and partial and autocorrelation functions (PACF), to assess seasonal differences in prevalence of pterygium model, ANOVA test, and to compare the prevalence of pterygium among patients in both two cities, independent sample t-test were used. In Zahedan, dusty days, sunshine hours, wind speed indicator, and ultraviolet and total sunshine indexes were the most effective factors on the prevalence of pterygium, respectively; while in Mashhad, wind speed, dusty days, and ultraviolet index were the most effective factors, respectively. ANOVA test showed no significant differences in terms of prevalence in different seasons. The t-test results showed that the prevalence of eye disease among patients in Zahedan was more than the city of Mashhad significantly. There was delay time in influencing the prevalence of pterygium by seasonal climate elements. In general, the incidence of pterygium was higher in Zahedan than Mashhad. It seems that the role of climatic factors in the incidence and severity of pterygium is more notable in Zahedan.

Cocaine is a central nervous system stimulant and is an inhibitor of monoamine (serotonin, norepinephrine and dopamine) reuptake; so increases their concentration in central nervous system. Monoamines such as serotonin and nor epinephrine have a role in anti-inflammatory effects and in modulating of immune system. The aim of this study was to investigate the effect of systemic and spinal administration of cocaine (none selective inhibitor of monoamine reuptake) on inflammatory paw edema and the role of serotonin neurotransmitter in these effects at the spinal level.

56 Male Wistar rats (200-250 g) were set in 8 groups: Intraperitoneal Saline, Intraperitoneal Saline/Dimethyl sulfoxide (DMSO), Intraperitoneal Cocaine 25 mg/kg, Intrathecal Saline, Intrathecal Saline/DMSO, Intrathecal Cocaine 100 µg/10 µl, Intrathecal Cyproheptadine 33 µg/10 µl and Intrathecal Cyproheptadine 33 µg/10 µl/Cocaine 100 µg/10 µl. Inflammation was induced by subplantar injection of formalin.

Anti-inflammatory effects of cocaine was significant in intraperitoneal cocaine 25 mg/kg (P < 0.001) and intrathecal cocaine 100 µg/10 µl (P < 0.001) groups. In intrathecal cyproheptadine 33 µg/10 µl group, there was no influence on inflammation. In intrathecal cyproheptadine 33 µg/10 µl/cocaine 100 µg/10 µl, cyproheptadine decreased a part of anti-inflammatory effect of cocaine (P < 0.001).

Serotonergic terminals coming from higher center to the spinal cord interacts with spinal neurons such as primary afferent C fibers. Probably, the inhibition of primary afferent fibers by serotonin inhibits release of inflammatory agent from these fibers and causes anti-inflammatory effects. It is likely that inhibition of serotonin receptor at the spinal level by intrathecal administration of cyproheptadine has reduced anti-inflammatory effects of cocaine.