Iranian Biomedical Journal
Year:2003 | Volume:7 | Issue:3|Papers Count:9

Xanthan gum is a microbial polysaccharide of great commercial importance as it has ‎unusual rheological properties in solution and consequent range of applications. In ‎this study, a series of mutants were isolated from Xanthomonas campestris PTCC ‎‎1473 by ethyl methanesulfonate mutagenesis. The polysaccharide yield of one mutant, ‎XC1473E2, was 30% better than that of the parent strain. It also showed higher ‎Xanthan formation and glucose consumption rates compared to the parent strain. ‎Xanthan produced by the mutant had enhanced viscosity, higher pseudoplasticity and ‎larger molecular weight. Since mutant XC1473E2 appeared white on agar plates, it ‎underwent pigment extraction with methanol. Contrary to the Parent strain, the mutant showed no absorption at 443nm, i.e. the wavelength related ‎to yellow pigment. This finding suggested that yellow pigmentation and normal ‎Xanthan biosynthesis are not necessarily concurrent. In general, mutant XC1473E2 ‎seems to be a strain with interesting characteristics for use in commercial production ‎of Xanthan‏.‏

There is strong evidence demonstrating that nifedipine dissolved in ethanol selectively ‎inhibits only L-type Ca^2+ current. In addition, acute ethanol exposure reduces ‎voltage-dependent calcium currents. In the present study, we investigated the ‎antagonistic effect of fixed concentration of nifedipine dissolved in different ‎concentration of ethanol on L-type Ca^2+ current. In a Na^+-K^+ free solution, ‎nifedipine dissolved in 60 and 120 mM ethanol decreased resting membrane potential ‎of Ca^2+ spikes and caused a significant reduction in amplitude, duration and an ‎increase in threshold of Ca^2+ spikes. Furthermore, Ca^2+ current was inhibited by ‎ethanol in a concentration-dependent manner, so that the reduction of L-type Ca^2+ ‎current by nifedipine/60 and 120 mM ethanol was statistically significant. Meanwhile; ‎ethanol concentration-dependent response of Ca2+ currents was observed at its late ‎component in more positive potentials. These results may be consistent with ethanol-‎dependent inhibition of L-type Ca^2+ currents and ethanol-dependent enhancement of ‎a Ca^2+-activated potassium current‏.‏

Clinical studies have shown that in pathological conditions such as endometriosis and ‎reproductive tract infection (male and female) there is an activation status of ‎macrophages that produce large quantities of nitric oxide (NO) in addition to other ‎effector molecules. Large amounts of NO may have embryotoxic roles and produce ‎infertility. This study was designed to evaluate the effect of different concentrations ‎of NO on mouse pre-implantation embryo development in vitro. Mouse embryos (2-‎cell stage) were cultured in media containing different concentrations of sodium ‎nitroprusside (SNP), an NO donor, or L-arginine methyl ester (L-NAME), an NO ‎syntase (NOS) inhibitor. At the end of culture, cell apoptosis was studied by the ‎terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) ‎technique. The results showed that development of preimplantation embryos was ‎inhibited by high concentration of SNP (1 and 10 pM). In contrast, 0.1 pM of SNP ‎stimulated the embryo development. Similarly, the inhibition of NO by NOS inhibitor ‎resulted in the dose-dependent inhibition of embryo development, but the addition of ‎‎0.1 pM SNP with L-NAME reversed the inhibitory effect of L-NAME. TUNEL ‎technique showed that high concentration of NO could induce apoptosis in the ‎embryo, but at low concentration, it decreased apoptotic cell death. Iran‏.‏

The effect of onion and garlic extracts on fungal growth and keratinolytic activity was ‎studied in Trichophyton mentagrophytes as one of the major etiologic agents of ‎human and animal dermatophytosis in Iran and other parts of the world. In order to ‎find out the best keratinase producer for further steps, culture conditions for 30 strains ‎of T. mentagrophytes isolated from human dermatophytosis were optimized on ‎specific solid and liquid media. All of the isolates produced the enzyme on both ‎selective culture media. The maximum keratinolytic activity at submerged cultivation ‎was reported for cultures of T. mentagrophytes isolate No. 1 grown for a 12-day ‎period at 32°C. Extracellular keratinase activity was in the range of 0.28 to 2.18 u/mg ‎protein in different isolates at predetermined optimal conditions. The growth of T. ‎mentagrophytes isolate No. 1 was inhibited in the presence of various concentrations ‎of onion and garlic extracts. This inhibition reached to a maximum of 100% for both ‎extracts at 10% v/v concentrations. Keratinase synthesis was also inhibited by two ‎extracts as a dose-dependent manner with maximums about 58.54 and 71.36 percent ‎at 5% concentrations, accordingly. In contrast to the fungal growth, keratinolytic ‎activity was inhibited more by garlic as compared with onion extract. This is the first ‎report on keratinase inhibition by these two natural compounds. Since fungal growth ‎and keratinolytic activity are important factors in pathogenesis of the dermatophytes, ‎their inhibition by onion and garlic indicate that these substances may have potential ‎values for treatment of human and animal dermatophytosis‏.‏

Continuous four hours EEG (electroencephalogram) recordings and its power ‎spectrum analysis using fast Fourier transform (FFT) in urethane anesthetized male ‎Charles Foster rats were performed in two groups: open brain injury and p-CPA ‎‎(para-Chlorophenylalanine) pretreated before brain injury, respectively, and compared ‎with the EEG power spectrum of control rats. The EEG power spectrum analysis ‎showed that there was a faster recovery in p-CPA pretreated group than the injury ‎group of rats. The results showed that the p-CPA (a 5-HT inhibitor) prevents ‎pathological changes following brain injury. Simultaneously, the inference can also be ‎drawn that EEG power spectrum analysis is a useful technique for monitoring the ‎brain injury and its recovery following pharmacological treatments.‎

In our search for new anticancer medicinal plants, the antiproliferative activity of the ‎methanol extract of Daphne mucronata (Thymelaeaceae) was evaluated using human ‎myelogenous leukemia K562 cells. The cells responded to plant treatments in a dose ‎dependent manner and the IC__50 of the crude extract (equivalent to 1 g of plant ‎leaves powder per ml) and the purified active component were found to be 42 Id and ‎‎1.3 pM, respectively. The antiproliferative activity of the plant was also evaluated ‎using flow cytometry technique. The results indicated that the crude extract and the ‎active purified component are capable of arresting the cells in G, phase of the cell ‎progression cycle. This data may provide a mechanism for the antiproliferative action ‎of the plant

During early neurogenesis, the floor plate plays an essential role(s) in the differentiation of the ventral portion of neural tube. In this study, we detected the specific distribution of unique glycoconjugate during the floor plate differentiation. Formalin fixed paraffin sections of BALB/c mice (10-14 embryonic days) were processed for histochemical studies using horseradish peroxidase-labelled N-acetylgalactosamine (GaINAc) sensitive lectins. Histochemical analysis has revealed the presence of unique Wisteria floribunda (WFA)-sensitive glycoconjugate reaction in the floor plate area and surrounding extracellular matrix. Weak reaction also was observed in the outer surface of the basal zone of the neural tube. Extensive differences among the GaINAc lectins were demonstrated during the sensitive time of motoneuron differentiation. There was no reaction with other tested GaINAc lectins. The duration and distribution of WFA lectin reactions suggest that these molecules may play a key role(s) in tissue interactions and subsequent formation of the adjacent tissues including floor plate and basal plate differentiation during critical morphogenic period. Furthermore, our findings indicate that among considered early neuronal morphogenic (embryonic) days, WFA reactions were increased and expanded near the end of gestation period.

In Iranian traditional medicine, there are some reports regarding the anticonvulsant ‎effect of Ferula gummosa Boiss. In this study, anticonvulsant activity, neurological ‎deficits and lethality of the root acetone extract of this plant were evaluated in mice. ‎The extract exhibited dose-dependent prevention of tonic seizures induced by ‎pentylenetetrazole (ED50 = 154.4 mg/kg). However, the extract produced sedation ‎and motor impairment with TD50 value of 546 mg/kg. Preliminary phytochemical ‎analysis showed the presence of terpenoids, alkaloids and a little amount of ‎cardenolids in the extract. It seems that the anticonvulsant and neurotoxic effects of ‎the extract is related in part to the terpenoid compounds. The acceptable protective ‎index of the extract (3.5) recommends further studies on Ferula gummosa‏.‏

Analysis of the phenylalanine hydroxylase (PAH; McKusick 261600) gene in different populations has revealed more than 320 different mutations associated with phenylketonuria (PKU). One of these mutations, IVS10nt546, results in severe PAH deficiency due to defective mRNA splicing. It accounts for about 40 percent of all mutant alleles in Turkish and between 10 to 20 percent of all mutant alleles in Spanish, Italian, Sicilian, and Bulgarian populations [1-6]. This allele is rare in Western Europe and is mostly absent in northern and eastern European populations [1, 7].Analysis of variable number of tandem repeat (VNTR) polymorphism linked to the IVS10nt546 mutation in Turkey, Israel, Italy, Spain, Germany, Switzerland and Denmark showed that in these populations the IVS10nt546 mainly linked to allele VNTR with 7 repeat (based on 252 observed IVS10nt546) [1, 3-5]. However, only in 3 cases from Italy the mutant allele was linked with VNTR8 [1, 5]. Unfortunately, there is no information about the frequency of IVS10nt546 and its linkage(s) with VNTR alleles in Iranian populations.We extracted genomic DNA from patient’s leukocytes and used for PCR. Mutation analysis on 8 PKU patients, showed 5 alleles of IVS10nt546 in 3 patients (two patients were homozygous and one patient was heterozygous for the IVS10nt546 allele). Interestingly, all of these alleles were linked with 8 repeats of VNTR. Although the sample size was small, it is suggested that the IVS10nt546 allele linked to VNTR8 have high frequency in Iranian PKU patients.In European populations from 252 observed IVS10nt546 alleles, only in 3 cases from Italy the mutant allele was linked with VNTR8 [1, 5]. Fisher’s exact two-tailed test showed the statistically significant difference for the frequency of IVS10nt546-VNTR8 between Iranian and European PKU patients (P = 0.0000013). Therefore, our results revealed that Iranian population has similarity with Turkish population for high frequency of IVS10nt546 allele, but there is a remarkable difference for linkage of VNTR alleles and IVS10nt546 between Iran and Turkey. The high difference of a PAH gene mutation linked with a specific repeat of VNTR in an Iranian population compared with European populations, is probably a reflection of the complex demographic history of Iran at the crossroad of prehistoric and historical demographic in this area. However, more data are needed to discuss about the geographical distribution and origin of the IVS10nt546-VNTR8.This study was supported by Shiraz University.