Iranian Journal of Basic Medical Sciences
Year:2011 | Volume:14 | Issue:3 (50)|Papers Count:12

The thioredoxin system, comprising thioredoxin (Trx), thioredoxin reductase (TrxR) and NADPH, is one of the major cellular antioxidant systems, implicated in a large and growing number of biological functions. Trx acts as an oxidoreductase via a highly conserved dithiol/disulfide motif located in the active site (-Trp-Cys-Gly-Pro- Cys-Lys-). Different factors are involved in the regulation of Trx activity, including its expression level, localization, protein-protein interactions, post-translational modifications and some chemical inhibitors. Mammalian TrxRs are selenoproteins which have a –Cys-Val-Asn-Val-Gly-Cys- N-terminal active site, as well as a C-terminal selenium-containing active site. Besides two Cys-residues in the redox-regulatory domain of cytosolic Trx (Trx1), human Trx1 has three additional Cys-residues. Post-translational modifications of human Trx1 which are involved in the regulation of its activity can happen via modification of Cys-residues includingthiol oxidation, glutathionylation and S-nitrosylation or via modification of other amino acid residues such asnitration of Tyr-49. Because of the numerous functions of the thioredoxin system, its inhibition (mainly happens via the targeting TrxR) can result in major cellular consequences, which are potentially pro-oxidant in nature, leading to cell death via necrosis or apoptosis if overexpression of Trx and other antioxidative enzymes can not recuperate cell response. Considering this feature, several anticancer drugs have been used which can inhibit TrxR. Elevated levels of Trx and/or TrxR have been reported in many different humanmalignancies, positively correlated with aggressive tumor growth and poor prognosis. Moreover, anti oxidative and antiapoptotic effects of Trx are reasons to study its clinical application as a drug.

Objective(s): Although photodynamic therapy is considered as a noninvasive method, most photosensitizers are susceptible to ultrasound. Therefore, it is expected that the combination of two activation methods might have a synergistic effect. This probable effect has been investigated in this study.Materials and Methods: This study was conducted on colon carcinoma tumor in Balb/c mice. The tumors were induced by subcutaneous injection of CT26 cells. Ultrasound and light irradiations were performed on tumors 24 hr after injection of liposomal Zn (II)-phthalocyanine. The treatment efficacy was evaluated using daily measurement of the tumor dimensions.Results: Ten days post treatment, relative tumor volumes of all groups were significantly reduced in comparison with the main control group. The best response was observed when one of the two treatment methods had been applied. The longest doubling time of tumor was related to the treatment group namely photodynamic, sonodynamic and combination technique, while the shortest belonged to the control group.Conclusion: This study showed that liposomal Zn phthalocyanine is both photosensitizer and sonosensitizer. Photodynamic and sonodynamic therapies can be efficient in retarding tumor growth rate. In this study, the combination of two methods didn’t show any improvement in therapeutic outcomes. It is predicted that latest results are related to the treatments sequence and could be optimized in the future.

Objective(s): Despite the enormous heterogeneity of genetic hearing loss, most non-syndromic hearing losses are caused by mutations in the GJB2 gene. We aimed to characterize the mutation profiles of 100 Iranian deaf patients that were under 10 years old.Materials and Methods: Patients were tested with direct sequencing of entire coding region of the GJB2 gene.Results: Eight known mutations plus one novel (358delGAG) were found in 25% of study group. The 35delG mutation (64%) constituted the majority of GJB2 mutations.Conclusion: Role of GJB2 mutation in Iranian young deaf population is more prominent than previous study that can be a result of higher consanguine marriage in population. But our result shows that there is only 25% nonsyndromic hearing loss due to high frequency of consanguine marriage in Iranian population. Identification of other genes involved in genetic deafness will help us understand the fundamental mechanisms of normal hearing, both in early diagnosis and therapy

Objective(s): The mitochondrial defects in Friedreich's ataxia have been reported in many researches. Mitochondrial DNA is one of the candidates for defects in mitochondrion, and complex I is the first and one of the largest catalytic complexes of oxidative phosphorylation (OXPHOS) system.Materials and Methods: We searched the mitochondrial ND4L gene for mutations by TTGE and sequencing on 30 FRDA patients and 35 healthy controls.Results: We found 3 missense mutations [m.10506A>G (T13A), m.10530G>A (V21M), and m.10653G>A (A62T)] in four patients whose m.10530G>A and m.10653G>A were not reported previously. In two patients, heteroplasmic m.10530G>A mutation was detected. They showed a very early ataxia syndrome. Our results showed that the number of mutations in FRDA patients was higher than that in the control cases (P=0.0287).Conclusion Although this disease is due to nuclear gene mutation, the presence of these mutations might be responsible for further mitochondrial defects and the increase of the gravity of the disease. Thus, it should be considered in patients with this disorder.

Objective(s): Deregulation of the immune system through allied factors and cytokine responses are thought to be important contributors to the pathogenesis of asthma. Vitamin D3 and its nuclear receptor appear to be factors that maybe involved in regulating I mmune responses during the progression of asthma. The aim of this study was to investigate the association between polymorphisms in intron 8 and exon 9 of the vitamin D receptor (VDR) and this disease.Materials and Methods This study was performed on 100 asthmatic patients and 100 healthy controls. PCR-RFLP was performed to examine polymorphisms in intron 8 and exon 9 of VDR gene.Results Our results showed a statistically significant difference in the Taq-1 evaluated genotypes of exon 9 of the VDR gene when comparing healthy patients to asthmatic patients.Conclusion Based on our results, it can be concluded that VDR and its functional polymorphisms may play an important role in the pathogenesis of asthma.

Objective(s): Gastric ulceration is induced by various forms of stress like surgery, ischemia and trauma. The female sex has more resistance to stress and the gastrointestinal lesions happen fewer than male sex. The purpose of this study was to evaluate the role of estradiol and progesterone on the gastric acid and pepsin levels following traumatic brain injury (TBI) induction.Materials and Methods: Diffuse TBI was induced by Marmarou method in female rats. Rats randomly assigned into 9 groups: intact, OVX (ovarectomized rat), Sham+OVX, TBI (intact rats under TBI), TBI+OVX (ovarectomized rats under TBI) and treated OVX rats with vehicle (sesame oil), E2 (estradiol), P4 (progesterone) or E2+P4 combination. The acid content and pepsin levels of each gastric washout sample were measured 5days after the TBI induction.Results: There was no significant difference in gastric acid output between groups either after TBI induction or after treatment with E2 or P4 or E2+P4. Gastric pepsin levels were increased in Sham+OVX, TBI (P<0.001) and TBI+OVX (P< 0.05) compared to intact group. Gastric pepsin levels were significantly lower in E2 and E2+P4 treated rats than vehicle treated group (P< 0.01). P4 treatment increased gastric pepsin level compared to TBI+OVX group (P< 0.05) and this increment was higher than rats that were treated with the E2 and E2+P4 (P<0.01).Conclusion: These results suggest that protective effect of estradiol and E2+P4 combination against mucosal damage after TBI, might be mediated by inhibition of pepsin secretion.

Objective(s): The effect of tamoxifen as a selective estrogen receptor modulator which is widely used for treatment of early and metastatic breast cancer was investigated on the folliculogenesis in rat's fetuses and neonates.Materials and Methods: The pregnant rats assigned into test and control groups. Control group received olive oil and treatment groups received either 17-b-estradiol (10 mg/kg/day) or tamoxifen(0.4 mg/kg/day) between days 8-13 of pregnancy. On day 20th of pregnancy the rats euthanized and the blood samples were collected for determination of FSH, E2, and the fetuses fixed for histological studies. Another group of pregnant rats went forward to obtain their neonates and we euthanized the neonates and the genital system was collected for further histopathological analyses on day 5th.Results: The histological examinations of the fetus’s and neonate's ovaries and biochemical data showed significant changes in the rats which treated with tamoxifen. The absence of folliculogenesis and an increase in E2 level in tamoxifen-treated group which accompanied with sharp decrease of FSH level in comparison with the control group were demonstrated. By contrary, E2 treated group showed a positive progress in development in terms of the formation of secondary follicles and also supportive connective tissues in comparison with the control group.Conclusion: In conclusion, this study supports the previous findings showing that tamoxifen has effects on the development of ovaries and therefore, it should be avoided or used with great caution in pregnant women.

Objective(s): Considering fair response to inhaled corticosteroids and reports of severe air way hyper responsiveness in chemical warfare victims (CWV), a role for eosinophilic inflammation (i.e. asthma) was postulated. The objective of this study was to determine the presence of eosinophilic inflammation in CWV by evaluation of Sputum cellularity and eosinophil cationic protein (ECP).Materials and Methods: Forty CWV and 15 control subjects entered this cross sectional study. Demographic data, dyspnea severity scale, spirometry results and 6 min walk test were determined. Sputum was collected with inducing by nebulizing hypertonic saline and analyzed for totalinflammatory cell count, the cellular differential count and ECP level. Control group was normal volunteers with PC20 more than 8 mg/ml.Results: Mean±SD of eosinophil percentage (11.7±11.1%) and ECP level in sputum of CWV(46.1±19.5ng/ml) were significantly more than control group. Regression analysis showed significant correlation between ECP leveland percentage of eosinophils in sputum (r=+0.43, P<0.01). ECP level of CWV subjects with obstructive pattern did not show any significant difference from CWV with normal spirometry. ECP level in CWV subjects who revealed more than 12% improvement in forced expiratory volume in one second (FEV1) was significantly higher than CWV who had improvement less than 12% (P=0.01). BO and asthma as final clinical diagnosis of CWV did not show any significant difference of sputum ECP.Conclusion: Bronchial inflammation in different types of pulmonary complication of CWV is eosinophil dependent. ECP level of sputum in CWV could guide physician to select CWV who would respond to corticosteroids.

Objective(s): The aim of this study was to investigate the effects of aerobics, pilates exercises and low calorie diet on leptin levels and some lipid profiles and anthropometric factors in sedentary women.Materials and Methods: Forty six women (age 36.41±3.47) were recruited and divided into four groups: aerobic exercise group (EX), Pilates exercise group (Pilates), low calorie diet (LCD) and control group (C). Sampling was random. Exercise trials consisted of 45 min of aerobics or Pilates exercise at 60-75% of maximum heart rate for 16 weeks. All subjects were asked to complete a medical examination as well as a medical questionnaire to ensure that they were not taking any medication and were free of any diseases. Waist and hip circumferences, leptin and lipid profiles (TG, TC, LDL-C, and HDL-C) were measured at baseline and at the end of the study.Results: The probability levels of significance were based on the two paired sample t-test and one way ANOVA. Significant was assigned at P< 0.05 for all analyses. Serum leptin concentrations (ng/dl) showed significant decrease (P< 0.05) in LCD (0.15±0.09), EX (0.37±0.06), Pilates (0.69±0.13) after 16 wk follow-up, and were different among experimental groups (P< 0.05), though in control group did not different significantly (P> 0.05). Significant reductions (P< 0.05) were found in waist-hip ratio (WHR) within LCD (0.733±0.07), EX (0.805±0.06), Pilates (0.768±0.054), and between experimental groups (P< 0.05). The blood profiles and lipoproteins didn’t change significantly in LCD, EX, Pilates and C groups (P> 0.05). The ratio of HDLC/ LDL-C increased significantly (P< 0.05) in LCD (0.815±0.104), EX (0.948±0.068), Pilates (0.753±0.139) and between experimental groups (P< 0.05).Conclusion: In conclusion, serum leptin concentrations and waist-hip ratio (WHR) showed significant changes within and between exercise and diet groups. A combination of diet and exercise may be closely related to significant decreases in lipid profiles.

Objective(s): Several studies have reported improved response of exercised hearts to myocardial infarction (MI). This study was aimed to evaluate the preventive role of treadmill exercise and diosgenin on cardiac marker enzymes, thiobarbituric acid reactive substances (TBARS), total antioxidant status (TAS), lipids, and electrocardiographic (ECG) patterns in isoproterenol (ISO)-induced myocardial infarction (MI) in male Wistar rats.Materials and Methods: One hundred Wistar rats were divided into ten groups: Control rats (C), saline (S), L-cremephor (LC), exercise (E), diosgenin dissolved in L-cremephor (15 mg/kg/day) (D), exercise+ diosgenin (E+D), ISO injected (150 mg/kg) (ISO), exercise + ISO (E+ISO), diosgenin +ISO (D+ISO) and exercise+ diosgenin+ ISO (E+D+ISO). At the end of the experiment all animals anesthetized and blood samples were collected for biochemical estimation and also the ECG patterns were recorded.Results: Exercise and diosgenin pretreatment significantly decreased the lactate dehydrogenase (LDH) and TBARSlevel in ISO injected animals. Exercise and diosgenin pretreatment significantly decreased serum total cholesterol and increased high density lipoprotein (HDL-C). ISO-treated rats showed pathological Q waves along with elevated ST segments. The altered electrocardiograms (ECG) of ISO-treated rats were also restored to near normal by diosgenin and exercise, but exercise and diosgenin had synergistic effects.Conclusion: The present investigation demonstrates that combination of diosgenin and exercise exhibited significant protection against ISO induced electrocardiographical and biochemical changes. The cadioprotective mechanism(s) appear to be through changing lipid metabolism.

Objective(s): Oxidative stress plays an important role in diabetic nephropathy pathogenesis. Rosmarinic acid, a plant phenolic compound, was first used as an antioxidant agent for inhibition of diabetic nephropathy.Material and Methods: Forty male rats were uninephrectomized from the left flank.The rats were divided in four groups randomly; group one as control, group two diabetic untreatment, groups three and four treatment with rosmarinic acid by 100 or 200 mg/kg/d orally respectively. Diabetes was induced in the second, third and fourth groups by alloxan injection subcutaneously. After 8 weeks treatment, serum malondialdehyde was measured by thiobarbituric acid (TBA) test. Serum creatinine and serum urea were measured by kits. Kidney paraffin sections were prepared and stained by periodic acid Schiff method.Glomerular volume and glomerular number were estimated by stereological rules and glomerular sclerosis was studied semi-quantitatively. Data were analyzed by non-parametric Man Whitney test (using SPSS 13 software) and P< 0.05 was considered significant.Results: Rosmarinic acid (100 or 200 mg/kg) significantly inhibited glomerular hypertrophy, glomerular number loss, glomerulosclerosis, lipid peroxidation, serum urea and creatinine compared with the diabetic untreated group. The level of glomerular number and serum malondialdehyde in the treated groups (100 mg/kg or 200 mg/kg of rosmarinic acid) was maintained at the same level as compared to the control group.Conclusion: Rosmarinic acid could significantly reduce glomerular hypertrophy, loss of glomerular number, glomerulosclerosis and attenuated serum urea and serum creatinine in diabetic rats.

Objective(s): We determined the effect of a high fructose diet either alone or in combination with Iranian shallot or garlic extract on cognitive functions, plasma lipid profile, and the intraperitoneal glucose tolerance test (IPGTT).Materials and Methods: Following induction of insulin resistance in fructose-fed rats (Fru-fed), theywere randomly assigned to three subgroups. The first subgroup was kept as Fru-fed while the two other subgroups were daily treated by aqueous garlic or shallot extract.Results: Twelve weeks treatment with shallot or garlic significantly prevented the learning and memory deficits induced by fructose-feeding. Administration of garlic, but not shallot extract could significantly diminish the levels of cholesterol and low-density lipoprotein. Treatment with garlic or shallot extract can significantly improve the IPGTT in the Fru-fed rats.Conclusion: The high fructose diet may contribute to spatial memory deficits. Iranian shallot or garlic extracts appear to improve learning and memory impairments in fructose-fed rats.