Papers by hassan tavakoli
Journal of biomedical physics and engineering, 2024
Journal of Military Medicine, Sep 19, 2018
Background and Aim: Electromagnetic waves consist of a combination of two perpendicular magnetic ... more Background and Aim: Electromagnetic waves consist of a combination of two perpendicular magnetic and electrical fields that do not require a material environment to propagate. Exposure to electromagnetic radiation in different occupations can increase tissue heat and damage to the health of individuals. The aim of this study was to determine the ability of a protective layer made of aluminum metal in the sheet and net mode to reduce electromagnetic radiation. Methods: This study was a descriptive-interventional study with a laboratory method in 2016. In this study, a non-ionizing radiation generator used to create electromagnetic waves at 900 MHz to radiate on the aluminum layers in sheet and net shapes in the same laboratory conditions. The wavelength of the aluminum metal was measured using anelectromagnetic radiation measuring apparatus. Data were analyzed using SPSS-18 software. Results: The findings showed that electromagnetic waves in laboratory conditions of aluminum are less than that of the lattice. The aluminum network with a 1 mm pore size is more potent than the ratio of the network with 5 mm pores in reducing the transmission of waves with a frequency of 900 MHz. The behavior of radio waves varies in different frequencies. In general, with increasing thickness, the ability to protect against the passage of waves increases very slightly. The aluminum network has less power compared to its laminar mode for electromagnetic waveguide protection at a wavelength of 900 MHz.
Iranian journal of child neurology, 2023
Journal of paramedical sciences, 2014
Various stresses during life can affect metabolism and brain activities, immune and endocrine sys... more Various stresses during life can affect metabolism and brain activities, immune and endocrine systems directly and indirectly, and ultimately, causes animal behavior change. The cellular and molecular level change in neurotransmitter and hormone concentrations led to the functional changes of operating systems in the intracellular organelles. These events cause of course oxidative stress. All these reactions cause general or limited inflammation that is characterized by increased phenomena of inflammatory cytokines. Electromagnetic waves are the most important stimulus of ions and biomolecules therefore they change ions movement in a living organism. This process can lead to neuronal and behavioral changes. Yet, certainly, radiation pattern, intensity and magnetic field strength will be highly effective in response (reaction). In the present study, short-term (one day) and medium-term (3 days and 7days) and long-term (19 days and 21 days) effects of extremely low-frequency waves (E...
archives of razi institute, 2021
Today, the production of Extremely Low-Frequency Electromagnetic Fields (ELF-EMFs) has significan... more Today, the production of Extremely Low-Frequency Electromagnetic Fields (ELF-EMFs) has significantly increased. This study aimed to investigate the effect of the ELF-EMFs on the structure and function of the brain in male Rhesus monkeys in terms of visual learning (VL), visual memory (VM), and visual working memory (VWM). Four monkeys were selected, of whom two monkeys irradiated by 0.7 Microtesla ELF-EMFs, 12 Hz, and two monkeys tested without irradiation (control group). A blood sample was taken in three stages, pre-, post-irradiated, and the recovery phases. Changes in the plasma levels of sodium, potassium, and adrenocorticotropic hormone (ACTH) were evaluated. Also, gene expression of N-methyl-D-aspartate (NMDA) receptors was assessed. The anatomical change of the brain’s prefrontal area was assessed by magnetic resonance imaging (MRI) and Digital Imaging and Communications in Medicine (DICOM) LiteBox file. The visual learning, visual memory, and visual working memory abilities...
Www Sjimu Medilam Ac Ir, Mar 15, 2015
Biomedical and Biotechnology Research Journal (BBRJ)
International Journal of Biological Macromolecules, 2005
The kinetics and thermodynamics of the effects of paraoxon (POX) and ethylparathion (EPA) on chol... more The kinetics and thermodynamics of the effects of paraoxon (POX) and ethylparathion (EPA) on choline oxidase (ChOx) were studied. Lineweaver-Burk plots of initial velocity data showed a parallel pattern indicating uncompetitive inhibition versus choline. The inhibition constant (K I) obtained from the secondary plots for POX and EPA were 0.14 ± 0.01 and 0.48 ± 0.05 mM, respectively, suggesting that POX is a more potent inhibitor of ChOx than EPA. UV absorption was used to monitor the denaturation of ChOx by POX and EPA. A decrease in FAD fluorescence associated with the interaction of POX and EPA with ChOx suggested a tertiary structural change. Interaction of the enzyme molecule with POX or EPA resulted in inhibition and subsequently denaturation of the enzyme. The results indicate that inhibition and denaturation of the enzyme by POX and EPA are linked, but not parallel events, with inhibition occurring at lower concentrations with respect to denaturation. This suggests that the loss of initial velocity of the enzyme is an active site specific effect and not due to global conformational changes induced by the inhibitors.
Radiation Measurements, 2010
This report describes the detection and dosimetry of gamma ray emitted from Thallium-201 (201 Tl)... more This report describes the detection and dosimetry of gamma ray emitted from Thallium-201 (201 Tl) and Technetium-99m (99m Tc) based on chemiluminescence technique. H 2 O 2 produced by two gamma emitter radioisotopes of 201 Tl and 99m Tc were quantitatively measured by chemiluminescence method. Upon producing H 2 O 2 in a luminol alkaline solution, in the presence of diperiodatocuprate, as catalyst a chemical reaction was accrued and consequently the emitted light was measured. The determined H 2 O 2 concentration was correlated with the gamma ray detection and dosimetry. The sensitivity of chemiluminescence technique for 201 Tl and 99m Tc dosimetry was determined to be 0.20 and 0.08 MBq/l (Mega Becquerel per liter) respectively (R.S.D. ¼ %5, N ¼ 3). The plotted calibration curves showed detection limits of 3.24 and 1.76 MBq/l for 201 Tl and 99m Tc, respectively.
Journal of the Iranian Chemical Society, 2010
In the presence of low energy gamma emitter radioisotopes of thallium-201 (201 Tl) or technetium-... more In the presence of low energy gamma emitter radioisotopes of thallium-201 (201 Tl) or technetium-99m (99m Tc), H 2 O 2 was generated via radiolysis of water. The produced H 2 O 2 was amperometrically determined using an anthraquinone 2-carboxylic acid modified horseradish peroxidase on glassy carbon electrode. In the presence of each radioisotope, the cathodic current produced due to the amperometric detection of H 2 O 2 , was designated as biosensor response. At the applied potential of-550 mV (vs. Ag/AgCl), the biosensor showed the sensitivities of 1.937 and 2.278 nA h µGy-1 towards H 2 O 2 produced by 201 Tl and 99m Tc respectively. Finally, the calibration curves for dose rate determination of 201 Tl and 99m Tc have been presented and the correlations between biosensor response to H 2 O 2 and the gamma emitter dose rates for 201 Tl and 99m Tc are established.
Organophosphorous compounds are important neuroactive molecules whose presents significant analyt... more Organophosphorous compounds are important neuroactive molecules whose presents significant analytical challenges. New monoenzyme biosensor introduced here, is used for the measurement of the level of two organophosphorous compounds, paraoxon (POX) and ethyl parathion (EPA), in phosphate buffer. Prussian blue electrodepositionized on a graphite electrode served as a template for immobilization of monoenzyme layer. A monoenzyme layer containing choline oxidase was immobilized along with nafion and bovine serum albumin, by cross-linking with glutaraldehyde. The results revealed that the response of the proposed biosensor was linear between 5 µM and 80 µM in the presence of POX and EPA. Detection limits were 0.4 µM in both cases. Also, for the optimization of the biosensor performance, temperature and pH dependency, concentration of choline chloride as substrate of choline oxidase and incubation time were determined. The results showed that the optimum values for temperature, pH, substrate concentration and incubation time were room temperature, pH 7, 4 mM and 30 min, respectively.
Iranian journal of basic medical sciences, 2017
In the present study the effect of stress on monkeys that had learned to retrieve food from a fiv... more In the present study the effect of stress on monkeys that had learned to retrieve food from a five-chamber receptacle, as well as the relationship between their behavior and the serum cortisol and epinephrine levels and relative size of the amygdala was evaluated. Six male rhesus monkeys were individually given access to the food reward orderly. They could easily retrieve the rewards from all chambers except for the chamber 4, which a brief, mild electric shock (3 V) was delivered to them upon touching the chamber's interior. The coping behaviors were video-recorded and analyzed offline. Baseline serum cortisol and epinephrine levels were measured before the experiments using monkey enzyme-linked immunosorbent assay kit. One week after the behavioral experiment, the monkeys' brains were scanned using magnetic resonance imaging under general anesthesia. The cross-sectional area of the left amygdala in sagittal plane relative to the area of the whole brain in the same slice wa...
Bioelectrochemistry, 2015
H2O2 generated during water radiolysis was measured electrochemically as an alternative dosimetry... more H2O2 generated during water radiolysis was measured electrochemically as an alternative dosimetry method. A biosensor was fabricated by immobilising modified horseradish peroxidase (HRP) on a glassy carbon electrode (GCE) followed by evaluation of its analytical parameters. Anthraquinone 2-carboxylic acid was used to modify HRP. To assess sensor performance, phosphate buffer solutions were irradiated with 0.510 Gy of gamma ray emitted from (60)Co. The results showed that this sensor can detect low quantities of hydrogen peroxide in water radiolysis. Sensitivity, detection limit and linear range of the biosensor were 260 nA/Gy, 0.392 Gy and 0.5-5 Gy, respectively. Long term stability studies showed that sensor responses were stable for at least a month. The cathodic peak current, as biosensor response, subsequently decreased to 20% of its initial value.
Radiation Protection Dosimetry, 2012
Growth arrest DNA damage-inducible 45a gene (Gadd45a) and immediate early response gene 5 (Ier5) ... more Growth arrest DNA damage-inducible 45a gene (Gadd45a) and immediate early response gene 5 (Ier5) have been emphasised as ideal radiation biomarkers in several reports. However, some aspects of radiation-induced transcriptional alterations of these genes are unknown. In this study, gender-dependency and dose-dependency as two factors that may affect radiationinduced transcription of Gadd45a and Ier5 genes were investigated. Human lymphocyte cells from six healthy voluntary blood donors (three women and three men) were irradiated in vitro with doses of 0.5-4.0 Gy from a 60 Co source and RNA isolated 4 h later using the High Pure RNA Isolation Kit. Dose and gender dependency of radiation-induced transcriptional alterations of Gadd45a and Ier5 genes were studied by quantitative real-time polymerase chain reaction. The results showed that as a whole, Gadd45a and Ier5 gave responses to gamma rays, while the responses were independent of radiation doses. Therefore, regardless of radiation dose, Gadd45a and Ier5 can be considered potential radiation biomarkers. Besides, although radiation-induced transcriptional alterations of Gadd45a in female and male lymphocyte samples were insignificant at 0.5 Gy, at other doses, their quantities in female samples were at a significantly higher level than in male samples. Radiationinduced transcription of Ier5 of females samples had a reduction in comparison with male samples at 1 and 2 Gy, but at doses of 0.5 and 4 Gy, females were significantly more susceptible to radiation-induced transcriptional alteration of Ier5.
Introduction: It seems that demographic and clinical features of patients referred for myocardial... more Introduction: It seems that demographic and clinical features of patients referred for myocardial perfusion scintigraphy (MPS) is different among populations and healthcare settings. The purpose of the current study is to evaluate the clinical features and risk factors of patients referred for myocardial perfusion scintigraphy to a military hospital. Methods: As a cross-sectional study, the clinical and laboratory data of all patients who were referred for MPS were recorded. MPS was performed using 99m Tc-Sestamibi or Thallium-201 (Tl-201) as the radiotracer. Results: From March 2005 to March 2006, the data of 1392 consecutive patients were recorded. The mean age of the patients was 55.3±14.8 years. 45.6% of the patients had no major risk factor, while 38.5% had one and 15.9% had two risk factors. Hypertension was the most common risk factor, while cigarette smoking was reported by eight percent of the patients. The method of stress protocol was dipyridamole infusion in 69.2%, Treadmill exercise test in 28.4% and dobutamine infusion in 2.4% of the cases. The sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of MPS in detection of angiographically positive CAD were 88.5%, 71.4%, 94.3%, 46.8% and 75.3%, respectively. Conclusion: In our population hypertension is the most frequent risk factor, so extensive social programs should be implemented aiming at controlling this variable, in order to prevent its possible cardiac complications. Cigarette smoking is less common than general population, which could be due to social characteristics of the target community and their beliefs, so this distinctiveness should be well defined and promoted. The differences in the pattern of cardiovascular symptoms and risk factors can be considered as indirect evidences to the fact that the pattern of referral for MPS in our country is significantly different from those in developed countries, a fact that warrants further evaluation in order to confirm its appropriateness based on the validated international guidelines.
Journal of the Iranian Chemical Society, 2010
Organophosphorous compounds are important neuroactive molecules whose presents significant analyt... more Organophosphorous compounds are important neuroactive molecules whose presents significant analytical challenges. New monoenzyme biosensor introduced here, is used for the measurement of the level of two organophosphorous compounds, paraoxon (POX) and ethyl parathion (EPA), in phosphate buffer. Prussian blue electrodepositionized on a graphite electrode served as a template for immobilization of monoenzyme layer. A monoenzyme layer containing choline oxidase was immobilized along with nafion and bovine serum albumin, by cross-linking with glutaraldehyde. The results revealed that the response of the proposed biosensor was linear between 5 µM and 80 µM in the presence of POX and EPA. Detection limits were 0.4 µM in both cases. Also, for the optimization of the biosensor performance, temperature and pH dependency, concentration of choline chloride as substrate of choline oxidase and incubation time were determined. The results showed that the optimum values for temperature, pH, substrate concentration and incubation time were room temperature, pH 7, 4 mM and 30 min, respectively.
Biomolecules and Therapeutics, 2014
Studies have demonstrated that electromagnetic waves, as the one of the most important physical f... more Studies have demonstrated that electromagnetic waves, as the one of the most important physical factors, may alter cognitive and non-cognitive behaviors, depending on the frequency and energy. Moreover, non-ionizing radiation of low energy waves e.g. very low frequency waves could alter this phenomenon via alterations in neurotransmitters and neurohormones. In this study, short, medium, and long-term exposure to the extremely low frequency electromagnetic field (ELF-EMF) (1 and 5 Hz radiation) on behavioral, hormonal, and metabolic changes in male Wistar rats (250 g) were studied. In addition, changes in plasma concentrations for two main stress hormones, noradrenaline and adrenocorticotropic hormone (ACTH) were evaluated. ELF-EMF exposure did not alter body weight, and food and water intake. Plasma glucose level was increased and decreased in the groups which exposed to the 5 and 1Hz wave, respectively. Plasma ACTH concentration increased in both using frequencies, whereas noradrenaline concentration showed overall reduction. At last, numbers of rearing, sniffing, locomotor activity was increased in group receiving 5 Hz wave over the time. In conclusions, these data showed that the effects of 1 and 5 Hz on the hormonal, metabolic and stress-like behaviors may be different. Moreover, the influence of waves on stress system is depending on time of exposure.
Radiation Physics and Chemistry, 2014
ABSTRACT
Journal of Radiation Research, 2003
Radioprotective/Citrus/Flavonoid/γ-Irradiation/Micronuclei. The radioprotective effects of citrus... more Radioprotective/Citrus/Flavonoid/γ-Irradiation/Micronuclei. The radioprotective effects of citrus extract were investigated by using the micronucleus test for anticlastogenic and cell proliferation activity. A single intraperitoneal (i.p.) injection of citrus extract (Citrus aurantium var. amara) at 250, 500, 1,000 mg/kg body weight 1 h prior to γ-ray irradiation (1.5 Gy) reduced the frequencies of micronucleated polychromatic erythrocytes (MnPCES) and normochromatic erythrocytes (MnNCES). All three doses of citrus extract significantly reduced the frequencies of MnPCEs and MnNCEs in mice bone marrow compared to non-drug-treated irradiated control (p < 0.005-0.05). The optimum dose for protection in mouse was 250 mg/kg to protect mice bone marrow 2.2-fold against the side effects of γirradiation with respect to the non-drug-treated irradiated control. The flavonoids were contained in citrus extract, probably to show protective activity, and reduced the clastogenic effect of radiation on mice bone marrow. Therefore fruits and vegetables contain flavonoids to be useful as protective effects under such stress conditions as irradiation.
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Papers by hassan tavakoli