مجله علوم پایه پزشکی ایران
سال:1389 | دوره: | شماره: |تعداد مقالات:12

Objective(s): To determine the potential toxic effects of manual soldering flux cored solder wire on lung of the rat as an experimental model.Materials and Methods: A total number of 48 adult male rats were divided into experimental (n=30) and control (n=18) groups. Based on exposure time to solder fume, each group was further subdivided into 2, 4 and 6 week subgroups. Rats of experimental groups were exposed to fume in exposure chamber for 1 hour/day (Research Center of Zahedan University of Medical Sciences, 12 Apr 2005 to 14 May 2005). The amount of fumes were measured daily by standard methods. At the end of experiment, lung specimens were collected from each experimental and control subgroups. Tissue samples were processed routinely and thickness of epithelium in bronchioles and interalveolar septas were measured in stained microscopic slides. Obtained data were analyzed by SPSS.Results: Statistical analysis of data for thickness of epithelium in bronchioles showed that there was only a significant difference between 4 week experimental and control subgroups (P<0.001). Analysis of data for thickness of interalveolar septa showed statistically significant differences between experimental and control subgroups of 4 and 6 weeks (P<0.001). Histological examination was also revealed an inflammatory process in bronchioles and disorganized architecture in alveoli of lung in experimental subgroups.Conclusion: The result showed that solder fume can change the normal architectures of epithelium in bronchioles and alveoli of the lung and it seems that the severities of changes were dependent on the exposure time.

Objective(s): Some properties of neuraminidase produced by Pseudomonas aeruginosa PAO1 growth in a defined medium (BHI) were examined and evaluated for its features.Materials and Methods: The obtained supernatant enzyme of P. aeruginosa PAO1 cultures was used in a sensitive fluorometric assay by using 2'-(4-methylumbelliferyl) a-D-N acetylneuraminic acid as substrate. As hydrolyzing MUN with neuraminidase; free N-acetylneuraminic acid and 4-methylumbelliferone were formed with a shift in the fluorescence spectra from 315/374 nm (substrate) to 365/450 nm (product). Enzyme activity was then measured by the fluorescence of 4-methylumbelliferone at 450 nm.Results: Among the culture media to determine the enzyme production, the highest production of P. aeruginosa PAO1 neuraminidase was found in BHI culture media. Neuraminidase production in P. aeruginosa PAO1 paralleled bacterial growth in defined medium (BHI) and was maximal in the late logarithmic phase of growth but decreased during the stationary phase, probably due to protease production or thermal instability. The neuraminidase of P. aeruginosa PAO1 possessed an optimum temperature of 56oC and the activity was pH-dependent with maximal activity at pH 5. Heating the enzyme at 56oC for 45 min in the presence of bovine serum albumin destroyed 33.1% of the activity while the addition of Ca+2, EDTA and N-acetyl neuraminic acid (NANA) decreased activity markedly.Conclusion: Overall, the results indicated that neuraminidase of P. aeruginosa PAO1 is more an extracellular enzyme than K. pneumonia neuraminidase is.

Objective(s): Bone marrow is the traditional source of human multipotent mesenchymal stem cells (MSCs), but adipose tissue appears to be an alternative and more readily available source. In this study, rat adipose-derived stem cells (ADSCs) were induced to differentiate into Schwann-like cells and compared with rat bone marrow stem cells (BMSCs) for their Schwann-like cells differentiation potential.Materials and Methods: BMSCs and ADSCs were characterized for expression of MSCs-specific markers, osteogenic and adipogenic differentiation. They were induced to differentiate into Schwann-like cells and analyzed for expression of the Schwann specific markers. The immunocytochemical differentiation markers were S-100 and real time quantitative Real-time polymerase chain reaction (RT-PCR) markers were S100, P75 and glial fibrillary acidic protein (GFAP). 3-(4, 5-Dimethylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and Annexin V-Fluorescein isothiocyanate (FITC)/ Propidium iodide (PI) double labeling method were employed to detect early stage cell apoptosis.Results: BMSCs and ADSCs showed similarities in expression of the MSC-specific markers, osteogenic and adipogenic differentiation. Both quantitative RT-PCR and immunocytochemical analysis demonstrated that BMSCs and ADSCs had equal expression of the Schwann-specific markers following Schwann-like cells differentiation. However, gene expression of P75 was higher in BMSCs compared with ADSCs. MTT assay and flow cytometry found that of the total BMSCs and ADSCs in the culture medium, 20% to 30% of the cells died, but the remaining cell population remained strongly attached to the substrate and differentiated.Conclusion: Comparative analysis showed that Schwann-like cell differentiation potential of ADSCs was slightly decreased in comparison with BMSCs. Therefore, BMSCs are more favorable choice than ADSCs for tissue engineering.

Objective(s): Theophylline, a xanthenes derivative, is still widely used as an effective bronchodilator in the management of asthmatic patients. It is used both as a prophylactic drug and to prevent acute exacerbations of asthma. The aim of study was to formulate and evaluate effect of the microencapsulation of theophylline loaded nanoparticles on the reduction of burst release.Materials and Methods: Microparticles (simple and composite) and nanoparticles were prepared by using water-in-oil-in-water (W1/O/W2 double-emulsion solvent diffusion/evaporation method), taking different ratios of drug/polymer. Solvent systems consist of ethyl acetate and dichloromethane for microspheres and nanospheres, respectively. In the current study formulations were characterized by loading efficiency, yield, particle size, zeta potential, X-ray diffraction (XRD) and differential scanning calorimetry (DSC).Results: In microparticles, the best drug to polymer ratio was 0.8:1 (F3). F3 formulation had minimum burst effect (37.81%), high loading efficiency (95.88%). In nanoparticles, F4 formulation (0.4:1 drug/polymer ratio) showed high production yield (40.8%), loading efficiency (99.05%), low particle size (756 nm) and minimum burst effect compared with other nanoparticle formulations. The drug loaded composite microspheres (F9) showed minimum burst effect, acceptable release and mean particle size 17.696 mm. The XRD and DSC showed stable character of theophylline in the drug loaded microspheres. The drug release was found to be diffusion and erosion controlled.Conclusion: The burst was significantly lower with composite microparticles and may be explained by lower diffusion of the drug from double polymeric wall formed by the nanoparticles matrix followed by another diffusion step through the microparticle polymeric wall.

Objective(s): The role of Elaeagnus angustifolia fruit as an analgesic agent in acute pain has been proved earlier. In this study, the effects of aqueous extracts of three parts of this fruit (pericarp, medulla and seed) on chronic pain were investigated in mice.Materials and Methods: A partial nerve injury was made using a tight ligature around the sciatic nerve, then doses (0.5, 1, 1.5 g/kg, i.p.) of pericarp, medulla and seed extracts were injected in nerve ligated mice. The effect of different doses of three parts of this fruit on chronic pain was examined 14 days after sciatic nerve ligation using the hot-plate test. Controls received saline (5 ml/kg, i.p.) and imipramine (40 mg/kg).Results: In the hot plate test, intraperitoneal injection of different doses of three parts of this fruit showed considerable analgesic effect on nerve ligated mice that was dose dependent with duration of action of 120 min.Conclusion: Administration of the aqueous extracts of pericarp, medulla and seed of E. angustifolia fruit indicated significant analgesic effect on chronic pain in nerve ligated animals.

Objective(s): Physiological changes in the body may be utilized as potential triggers for controlled drug delivery. Based on these mechanisms, stimulus-responsive drug delivery has been developed.Materials and Methods: In this study, a kind of poly (N-isopropyl acrylamide-acrylamide) membrane was prepared by radical copolymerization. Changes in swelling ratios and diameters of the membrane were investigated in terms of temperature. On-off regulation of drug permeation through the membrane was then studied at temperatures below and above the phase transition temperature of the membrane. Two drugs, vitamin B12 and acetaminophen were chosen as models of high and low molecular weights here, respectively.Results: It was indicated that at temperatures below the phase transition temperature of the membrane, copolymer was in a swollen state. Above the phase transition temperature, water was partially expelled from the functional groups of the copolymer. Permeation of high molecular weight drug models such as vitamin B12 was shown to be much more distinct at temperatures below the phase transition temperature when the copolymer was in a swollen state. At higher temperatures when the copolymer was shrunken, drug permeation through the membrane was substantially decreased. However for acetaminophen, such a big change in drug permeation around the phase transition temperature of the membrane was not observed.Conclusion: According to the pore mechanism of drug transport through hydrogels, permeability of solutes decreased with increasing molecular size. As a result, the relative permeability, around the phase transition temperature of the copolymer, was higher for solutes of high molecular weight.

Objective(s): Different types of extended spectrum beta-lactamases (ESBLs) are encountered in the clinical settings worldwide. There are a few studies regarding the prevalence of ESBL genes among Klebsiella pneumonia isolates at Tehran especially those of blaPER and blaCTX. The aim of this study was to determine the prevalence of blaSHV, blaTEM, blaPER and blaCTX genes among clinical K. pneumoniae of different hospitals in Tehran.Materials and Methods: Two hundred isolates of K. pneumoniae were received from different clinical specimens. The susceptibility of the isolates to 10 different antibiotics was examined by disk diffusion test. The MICs for ceftazidime were also determined using micro-broth dilution assay. Isolates showing MIC³ 4 mg/ml for ceftazidime were screened for ESBL production by phenotypic confirmatory test (PCT) and subjected to PCR for studied genes. Variation among four amplified genes was evaluated using PCR-RFLP.Results: By disk diffusion test, resistance to ceftazidime and cefotaxime were 34.7% and 33.5% respectively. However, all strains were susceptible to imipenem. Eighty isolates showed MICs³4 mg/ml for ceftazidime of which 77 (96%) were positive for ESBL in PCT. The prevalence of blaSHV, blaCTX-M, blaTEM and blaPER among these isolates were 26%, 24.5%, 18% and 7.5%, respectively. No variation was detected in the genes by PCR-RFLP.Conclusion: As far as we know this is the first report of the blaPER-1 in K. pneumoniae in Iran. The blaCTX-M was the second most common gene detected among the ESBL positive isolates of K. pneumoniae. For rapid identification of ESBL producing isolates it was recommended that clinical laboratories adopt simple test based on CLSI recommendation for confirming ESBL production in enterobacterial species.

Objective(s): Current study was undertaken to investigate the analgesic and anti-inflammatory effects of the aqueous extract of Teucrium chamaedrys in mice and rats.Materials and Methods: For evaluating of analgesic and anti-inflammatory activity, we used the carrageenan- and dextran-induced paw oedema, acetic acid-induced writhing and tail flick and formalin pain tests.Results: The extract of T. chamaedrys (50-200 mg/kg) and acetylsalicylic acid (100 mg/kg) produced a significant (P<0.01) inhibition of the second phase response in the formalin pain model, while only the high dose (200 mg/kg) of the extract showed an analgesic effect in the first phase. The extract also inhibited acetic acid-induced abdominal writhes in a dose-dependent manner. The tail flick latency was dose dependently enhanced by the extract but this was significantly (P<0.05) lower than that produced by morphine (10 mg/kg). The extract (25-250 mg/kg) administered 1 hr before carrageenan-induced paw swelling produced a dose dependent inhibition of the oedema. No effect was observed with the dextran-induced oedema model. Results of the phytochemical screening show the presence of alkaloids, flavonoids and triterpenoids in the extract.Conclusion: The data obtained also suggest that the anti-inflammatory and analgesic effects of the extract may be mediated via both peripheral and central mechanisms. The role of alkaloids, flavonoids and triterpenoids will evaluate in future studies.

Objective(s): In the present study, the differences in the relaxant effects of aqueous, ethyl acetate and n-butanol fractions of Rosa damascena on tracheal smooth muscle of guinea pigs were examined.Materials and Methods: The relaxant effects of three cumulative concentrations of each fraction (0.1, 0.2 and 0.4 g%) in comparison with saline and three cumulative concentrations of theophylline (0.1, 0.2, and 0.4 mM) were examined on precontracted tracheal chains of guinea pig by 60 mM KCl (group 1, n=5) and 10 mM methacholine (group 2, n=8).Results: In group 1, all concentrations of theophylline, ethyl acetate fraction and two final concentrations of n-butanol fraction showed significant relaxant effects in comparison with saline (p<0.05 to P<0.001). In group 2, all concentrations of theophylline, ethyl acetate and aqueous fractions showed concentration dependent relaxant effects compared to that of saline (p<0.01 to P<0.001). In addition, the effect of ethyl acetate fraction in group 1 was significantly higher than those of theophylline (p<0.05 to p<0.001). However, the effects of other fractions were significantly lower than theophylline in both groups (p<0.01 to p<0.001). There were significant correlations between the relaxant effects and concentrations for theophylline and all fractions (except aqueous fractions in group 1) in both groups.Conclusion: The results showed a potent relaxant effect for ethyl acetate fraction of R. damascena on tracheal smooth muscle comparable to that of theophylline but a relatively weak relaxant effect for aqueous and n-butanol fractions at concentrations used.

Objective(s): As an important class of natural products, coumarins exhibit many biological activities and the diversity of their bioactivity is so huge that the pharmacological promiscuity has been applied on their case. Oxypeucedanine also named as prangolarin is a linear furanocoumarin with an oxygenated prenylated substitution at C-5 of the nucleus. To our knowledge, there are few reports on pharmacological and biological activities of this compound. In the present work, we focused on some bioactive aspects of it.Materials and Methods: In the present work, the compound was purified from Prangos uloptera using TLC and its phytotoxic, antibacterial, antifungal, antioxidant and cytotoxic effects were evaluated by Lettuce assay, disc diffusion method, mycelia radial growth, DPPH and MTT assays, respectively.Results: Our results revealed that oxypeucedanin exhibit considerable phytotoxic activity and might play an allelopathic role for plants. The compound indicated high cytotoxic activity with IC50 value of 314 mg/ml. No antipathogenic and antioxidant activity were found for oxypeucedanin in this study.Conclusion: We conclude that oxypeucedanin (found in some vegetables) can be considered as an antiproliferative agent.

Objective(s): Neutrophil gelatinase-associated lipocalin (NGAL/Lcn2), comprise a group of small extracellular proteins with a common b-sheet-dominated 3-dimensional structure. In the past, it was assumed that the predominant role of lipocalin was acting as transport proteins. Recently it has been found that oxidative stress induces Lcn2 expression. It has been also proved that electromagnetic field (EMF) produces reactive oxygen species (ROS) in different tissues. Expression of Lcn2 following exposure to electromagnetic field has been investigated in this study.Materials and Methods: Balb/c mice (8 weeks old) were exposed to 3 mT, 50 HZ EMF for 2 months, 4 hr/day. Afterwards, the mice were sacrificed by cervical dislocation and livers were removed. The liver specimens were stained with Haematoxylin- Eosin (H&E) and analyzed under an optical microscope. Total RNA was extracted from liver and reverse transcription was performed by SuperScript III reverse transcriptase with 1 mg of total RNA. Assessment of Lcn2 expression was performed by semiquantitative and real time- PCR.Results: The light microscopic studies revealed that the number of lymphocyte cells was increased compared to control and dilation of sinosoids was observed in the liver. Lcn2 was up-regulated in the mice exposed to EMF both in mRNA and protein levels.Conclusion: To the extent of our knowledge, this is the first report dealing with up-regulation of Lcn2 in liver after exposure to EMF. The up-regulation might be a compensatory response that involves cell defense pathways and protective effects against ROS. However, further and complementary studies are required in this regards.

Objective(s): The aim of this study was to evaluate the effects of regular exercise in preventing diabetes complication in the hippocampus of streptozotocin (STZ)-induced diabetic rat.Materials and Methods: A total of 48 male wistar rats were divided into four groups (control, control exercise, diabetic and diabetic exercise). Diabetes was induced by injection of single dose of STZ. Exercise was performed for one hr every day, over a period of 8 weeks. The antioxidant enzymes (SOD, GPX, CAT and GR) and oxidant indexes with brain-derived neurotrophic factor (BDNF) protein and its mRNA and apoptosis were measured in hippocampus of rats.Results: A significant decrease in antioxidant enzymes activities and increased malondialdehyde (MDA) level were observed in diabetic rats (P=0.004). In response to exercise, antioxidant enzymes activities increased (P=0.004). In contrast, MDA level decreased in diabetic rats (P=0.004). Induction of diabetes caused an increase of BDNF protein and its mRNA expression. In response to exercise, BDNF protein and its mRNA expression reduced in hippocampus of diabetic rats.Conclusion: Diabetes induced oxidative stress and increased BDNF gene expression. Exercise ameliorated oxidative stress and decreased BDNF gene expression.