Iranian Biomedical Journal
Volume:7 Issue: 3, Jul 2003

Xanthan gum is a microbial polysaccharide of great commercial importance as it has unusualrheological 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 at443nm, 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 Ltype Ca2+ 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 Ca2+ current. In a Na+-K+ free solution, nifedipine dissolved in 60 and 120 mM ethanol decreased resting membrane potential of Ca2+ spikes and caused asignificant reduction in amplitude, duration and an increase in threshold of Ca2+ spikes. Furthermore, Ca2+ current was inhibited by ethanol in a concentration-dependent manner, so that the reduction of L-type Ca2+ 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 Ca2+ currents and ethanol-dependent enhancment of a Ca2+-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-cellstage) 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 were inhibited by high concentration of SNP (1 and 10 μM). In contrast, 0.1 μM of SNP stimulated the embryo development. Similarly, the inhibition of NO by NOS inhibitor resulted in the dose-dependentinhibition of embryo development, but the addition of 0.1 μM 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.

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 32ºC. 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 IC50 of the crude extract (equivalent to 1 g of plant leaves powder per ml) and the purified active component were found to be 42 µl and 1.3 µM, 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 G1 phase of the cell progression cycle. This data may provide a mechanism for the antiproliferative action of the plant. Iran.

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 (GalNAc) 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 GalNAc lectins were demonstrated during the sensitive time of motoneuron differentiation. There was no reaction with other tested GalNAc 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 report 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.