Journal of Sciences, Islamic Republic of Iran
Volume:16 Issue: 1, Winter 2005

tation in p53 tumor suppressor gene is highly frequent in different cancers. It was reported that the efficiency of Microarray and ABI 310 system in identification all types of p53 gene mutations (for fresh tissues) are 95% and 91%, respectively and detection of point mutations by Microarray and ABI 310 system are 100% and 92%, respectively. In the present study, Microarray and ABI 310 analysis were used to detect p53 gene mutations in esophageal carcinoma from archived tissues. For this purpose, formalin-fixed, paraffin-embedded esophageal tissues from cancer patients diagnosed with esophageal squamous cell carcinoma (ESCC) were collected. DNA was extracted by Microdissection method (with and without laser) and was purified with Microcon 50 filters (Millipore) before performing PCR. p53 gene mutations were identified in 9 analyzed samples by ABI 310 system. For these samples, the genomic DNA were obtained from microdissected-samples without laser. Microarray could detect mutations in 3 of 9 analyzed ESCC specimens from Iranian patients, which were identified p53 gene mutations by ABI 310 system. In addition, in laser-microdissected samples mutations were identified by ABI 310 system. The extracted DNA obtained from laser-microdissected samples was insufficient for the assessment of p53 gene mutations with Microarray. It was determined that Microarray was dependent on the amount of tissues used in DNA extraction. The results indicated that the choice of method for extracting DNA from test samples to assess mutation in p53 gene is very important. The efficiency of ABI 310 system and Microarray in detection of p53 gene mutations (for exons 5-8) was 100% and 30%, respectively for archived samples. Therefore, it is recommended to use fresh tissues for Microarray analysis.

A highly sensitive spectroscopic method using dichlorofluorescin (LDCF) was employed to study the rate of electron-transfer reaction in presence of dsDNA, ssDNA and some metal ions and imidazole derivative (N-trans cinnamoyl imidazole).Our results show that both kinds of DNA possess an enzyme-like catalytic activity in oxidative conversion of non fluorescent LDCF to fluorescent DCF. A biphasic saturation curve was observed when the reaction velocities were measured at fixed concentration of dsDNA, ssDNA and variable amounts of cinnamoyl imidazole. Each of biphasic phase gave the values of Km1=1×10−6 M, and Vm1=20.8 ΔF/min with Km2=1×10−4 M, Vm2=8.7 ΔF/min for dsDNA and Km1=2×10−6 M, Vm1=16.62 ΔF/min and Km2=4×10−4 M, Vm2=29.2 ΔF/min for ssDNA. Among investigated metal ions Mn and Cd caused inhibition of ET reaction in presence of DNA and imidazole while Cu and Ca activated the reaction. A linear correlation was found between conductivity of each metal ion and activation or inhibition of reaction in presence of dsDNA and ssDNA. A model was devised based on the catalytic properties of DNA in reaction with cinnamoyl imidazole and metal ions in which the release of electron produced by reaction could be facilitated by the presence of the cinnamoyl imidazole which could transfer the electron through its conjugated structure to the DNA chord via metal ion. The more conductive metal, the higher was the catalysis.

Glucose 6-phosphate dehydrogenase (G6PD) was purified from Streptomyces aureofaciens and inactivated with butanedione and diethylpyrocarbonate. Incubation of the enzyme with butanedione resulted in a rapid activity loss (80%) within 5 min, followed by a slow phase using a molar ratio to enzyme concentration of 100. Fluorescence studies showed a conformational change in the butanedione-modified enzyme. NAD+, NADP+ and glucose 6-phosphate protected the enzyme against inactivation. Diethylpyrocarbonate (2 mM) completely inactivated the enzyme after 2 min. Stoichiometry of the inactivation showed 2 moles of histidine residues per mole of enzyme with complete activity loss. Maximum emission spectrum of the enzyme decreased (23%) upon modification and the presence of NAD+ or NADP+ further decreased the fluorescence by 27% and 10.5%, respectively. The data suggest that essential arginine and histidine residues may be involved in the catalytic activity of Streptomyces aureofaciens G6PD.

Malaria remains one of the major causes of human morbidity and mortality, particularly in some developing countries such as Iran. The importation of malaria also into a place or region where they are not endemic raises many concerns, including the timely delivery of appropriate care, safety of the blood supply, the risk of autochthonous and transmission. Although different methods are appli-cable for detection of parasites which cause malaria, some of them do not have enough sensitivity. In this study a direct polymerase chain reaction (PCR) and light microscopy approaches were compared to detect Plasmodium falciparum in terms of sensitivity and specificity using blood samples from people with malaria-like symptoms and fever. A target DNA sequence of the plasmodial 18S ribosomal DNA (206 bp) was amplified by PCR. The assay showed a threshold of parasite density (detection limit) of one P. falciparum parasite/20microliter. Matching results were obtained for 18 people who presented malaria-like symptoms and fever. Our results showed that the direct PCR method proved to be a more sensitive and useful tool than the light microscopy assay to determine P. falciparum. Microscopy assay showed a low sensitivity (37.3%) when compared with falciparum-DNA detection by direct PCR (87.5%). In conclusion it was determined that direct PCR is a reliable method for detection of malaria parasites and it may be a useful tool for detection of other parasites as well.

Protein synthesis is one of the most complex cellular processes, involving numerous translation components that interact in multiple sequential steps. The most complex stage in protein synthesis is the initiation process. The basal set of factors required for translation initiation has been determined, and biochemical, genetic, and structural studies are now beginning to reveal details of their individual functions in this process. In Saccharomyces cerevisiae, eIF4E is the central component of the eIF4F complex, which binds the 5′ cap structure of the mRNA. This complex is significant in many ways. First of all, it is essential for translational initiation, mediating the initial interactions of ribosomes with the mRNA 5′ end. Secondly, because of its key role in interacting with the 5′ end of the mRNA, and possibly also with proteins such as the poly (A) binding protein (PABP) at the 3′ end of the mRNA, the eIF4F complex is thought to be involved in the process of mRNA degradation. Thirdly, eIF4F is a site of translational regulation, responding to signals communicated along the signal transduction pathway that are induced by stress conditions or hormones. To study about the interactions of eIF4E within the eIF4F complex, we tried to find conditions that would enable us to obtain structural data about S. cerevisiae eIF4E/eIF4G/Pab1p interactions. To yield information about the eIF4E/eIF4G/Pab1p complex, affinity chromatography was conducted using synthetic biotinylated capped mRNAs. For this purpose, a capped 55-nucleotide RNA was synthesised and labeled with Biotin-21-UTP at the 3′-end in an in vitro transcription reaction. For Biotin labeling of mRNA, rUTP was substituted with Biotin-21-UTP in the reaction. Soft Link Avidin Resin was used for the isolation of biotinylated mRNA, which can bind eIF4E via the capped structure at the 5′-end of the mRNA and Pab1p via the poly (A) tail at 3′ end. These results confirm that a highly pure eIF4E/eIF4G/Pab1p/RNA complex can be generated using the procedures outlined.

Reaction of 2-hydrazinocarbonyl-3-chloro-5-phenoxy-benzo[b] thiophene with different substituted phenyl isothiocyanate gave N-substituted arylthiosemi-carbazide derivatives (1a-h). 1,3,4-Thiadiazole derivatives (2a-h) were prepared by the cyclization of arylthiosemicarbazides (1a-h) with concentrated sulphuric acid. All the compounds were screened for their antitubercular activity against Mycobacterium tuberculosis (H37Rv) and antimicrobial activity against various microorganisms.

A simple, efficient, and general method has been developed for the chemoselective acetalization of aldehydes with 1,3-propanediol, 1,2-ethanediol and trimethyl orthoformate in the presence of solid lithium perchlorate under solvent-free conditions. Both cyclic and acyclic acetals of aldehydes were obtained under environmentally benign conditions in good to excellent yields.

The Borujerd complex of western Iran is composed of intrusions and their surrounding contact aureole, with, pegmatites and quartz veins. Pegmatites differ in mineralogy, origin and age, and two groups can be distinguished. The Older Pegmatites (about 120 Ma age) intruded contact metamorphic rocks from the early magmatic stage, while the Younger pegmatites (52-70 Ma age) formed during the late magmatic stage. Fluid inclusions from quartz veins, pegmatites and hornfelses have been studied using microthermometry, scanning electron microscopy, laser Raman spectroscopy and crush leach analysis to evaluate the source of fluids from which pegmatites formed. Host minerals of fluid inclusions in pegmatites are quartz and tourmaline, whereas in the hornfelses they are andalusite and quartz. Low salinity H2O inclusions are common in the Older Pegmatites and quartz veins whereas high salinity H2O inclusions occur in Younger Pegmatites. CO2-H2O fluid inclusions occur in Older Pegmatites and hornfelses, and in addition pure CO2 inclusions are observed in some hornfelses. The distribution of the different types of fluid inclusions suggests that CO2 fluids evaluated during metamorphism. The source of the carbon may be graphite which is present in hornfelses and the basement mica schists. Low salinity fluids in Older Pegmatites, quartz veins and hornfelses could have formed from low salinity late magmatic fluids. However, some mixing took place between magmatic fluids and metamorphic fluids to form CO2-H2O inclusions. High salinity magmatic fluids are only associated with Younger pegmatites and show low first ice melting temperature (−61.0 to −75.5°C), probably due to the presence of Ca.

The spatial distribution of saturated hydraulic conductivity based on data measured or observed at well locations is necessary for the numerical simulation of various ground water flow and transport problems. An Artificial Neural Network (ANN) model for estimating of hydraulic conductivity of a saturated granular porous medium from easily measured grain size distribution curve was developed and tested. Five types of porous media are considered in this work: loamy sand, sand, sandy-loam, sand-clay-loam, and silt-clay-loam family. The application of artificial neural network technology for estimating of saturated hydraulic conductivity from grain size distribution curve has been investigated. It has been found that reasonable estimates of this parameter can be obtained with the help of a network that uses the percent finer of the aquifer material as the input neurons, and the logarithm of the hydraulic conductivity value as the output neuron. A better estimate is obtained with a model that takes into account the logarithm of sigmoid function in hidden layer as a transform function. The artificial neural network models are found to give better estimates of saturated hydraulic conductivity of the individual group of soil as input neuron rather than all type of soil groups as input neuron for training step. For the loamy sand soils, the prediction of hydraulic conductivity was the best estimator. A comparison between the measured values of hydraulic conductivity of an unconfined Aquifer in Zahedan by pumping test and predicted value from their grain size distribution curve using the artificial neural network model shows a reasonable estimate of this parameter when using the model which trained by loamy sand data.

In this paper, we obtain the upper exponential bounds for the tail probabilities of the quadratic forms for negatively dependent subgaussian random variables. In particular the law of iterated logarithm for quadratic forms of independent subgaussian random variables is generalized to the case of negatively dependent subgaussian random variables.

In a celebrated work by Shao [13] several inequalities for negatively associated random variables were proved. In this paper we obtain some maximal inequalities for associated random variables. Also we establish a maximal inequality for demimartingales which generalizes and improves the result of Christofides [4].

So far the static properties of hadrons have been introduced in various models. The static properties of hadrons (charge radius, magnetic moment, etc.) are useful for understanding the quark structure of hadron. In this work we have introduced the hypercentral constituent quark and isospin dependent potentials. Here constituent quarks interact with each other via a potential in which we have taken into account the three body force effect and standard two-body potential contributions. According to our model the static properties of hadrons containing u, d, and s quarks are better than the other models and closer to the experiment. The two key ingredients of this improvement are the effective quark-gluon hypercentral potentials, the hyperfine interaction and isospin-dependence potential.PACS index12.39. Ba, 12.39. Ki, 12.39. Pn,