Human adipose derived stem cell exosomes enhance the neural differentiation of PC12 cells

Molecular Biology Reports - Human adipose stem cells (hADSCs) are proper cell sources for tissue regeneration. They mainly mediate their therapeutic effects through paracrine factors as exosomes....     

Antimicrobial susceptibility profiles associated with bacterial meningitis among children: a referral hospital-based study in Iran

Bacterial meningitis continues to be associated with high morbidity and mortality rate worldwide, especially in the pediatric age group. This study was performed to identify the microbial etiologies of meningitis among 31 children, who were admitted in the Emergency Ward of a referral pediatric hospital in Iran. Culture identification showed that Streptococcus pneumoniae (12 subjects), Haemophilus influenzae (11 subjects) were the most common bacteria, followed by Escherichia coli (7 cases) and Neisseria meningitidis (only one case). Antibiotic susceptibility tests revealed that vancomycin had the best effect on S. pneumoniae in comparison with other antibiotics, whereas H. influenzae and E. coli were more susceptible to ceftriaxone, ceftazidime, and ceftizoxime than other antibiotics. In conclusion, despite the advances in antibiotic therapy and vaccine development, bacterial meningitis still is a health problem. S. pneumoniae, H. influenzae, and N. meningitidis are the main sources of bacterial meningitis, but other organisms such as E. coli should also be suspected, when a case is admitted to a referral pediatric hospital.     

An efficient in vitro refolding of recombinant bacterial laccase in Escherichia coli

Laccases (benzenediol oxygen oxidoreductases, EC 1.10.3.2) are important multicopper enzymes that are used in many biotechnological processes. A recombinant form of laccase from Bacillus sp. HR03 was overexpressed in Escherichia coli BL-21(DE3). Inclusion body (IB) formation happens quite often during recombinant protein production. Hence, developing a protocol for efficient refolding of proteins from inclusion bodies to provide large amounts of active protein could be advantageous for structural and functional studies. Here, we have tried to find an efficient method of refolding for this bacterial enzyme. Solubilization of inclusion bodies was carried out in phosphate buffer pH 7, containing 8 M urea and 4 mM β-mercaptoethanol and refolding was performed using the dilution method. The effect of different additives was investigated on the refolding procedure of denaturated laccase. Mix buffer (phosphate buffer and citrate buffer, 100 mM) containing 4 mM ZnSO₄ and 100 mM sorbitol was selected as an optimized refolding buffer. Also Kinetic parameters of soluble and refolded laccase were analyzed.     

Response of microbial activity and community structure to decreasing soil osmotic and matric potential

Low soil water content (low matric potential) and salinity (low osmotic potential) occur frequently in soils, particularly in arid and semi-arid regions. Although the effect of low matric or low osmotic potential on soil microorganisms have been studied before, this is the first report which compares the effect of the two stresses on microbial activity and community structure. A sand and a sandy loam, differing in pore size distribution, nutrient content and microbial biomass and community structure, were used. For the osmotic stress experiment, salt (NaCl) was added to achieve osmotic potentials from ?0.99 to ?13.13 MPa (sand) and from ?0.21 to 3.41 MPa (sandy loam) after which the soils were pre-incubated at optimal water content for 10d. For the matric stress experiment, soils were also pre-incubated at optimal water content for 10d, after which the water content was adjusted to give matric potentials from ?0.03 and ?1.68 MPa (sand) and from ?0.10 to 1.46 MPa (sandy loam). After amendment with 2% (w/w) pea straw (C/N 26), soil respiration was measured over 14d. Osmotic potential decreased with decreasing soil water content, particularly in the sand. Soil respiration decreased with decreasing water potential (osmotic?+?matric). At a given water potential, respiration decreased to a greater extent in the matric stress experiment than in the osmotic stress experiment. Decreasing osmotic and matric potential reduced microbial biomass (sum of phospholipid fatty acids measured after 14 days) and changed microbial community structure: fungi were less tolerant to decreasing osmotic potential than bacteria, but more tolerant to decreasing water content. It is concluded that low matric potential may be more detrimental than a corresponding low osmotic potential at optimal soil water content. This is likely to be a consequence of the restricted diffusion of substrates and thus a reduced ability of the microbes to synthesise osmolytes to help maintain cell water content. The study also highlighted that it needs to be considered that decreasing soil water content concentrates the salts, hence microorganisms in dry soils are exposed to two stressors.     

Recovery of soil respiration after drying

Soils are frequently exposed to drying and wetting events and previous studies have shown that rewetting results in a strong but short-lived flush of microbial activity. The aim of this study was to determine the effect of the water content during the dry period on the size and duration of the flush and on the rate of recovery. Two soils (a sand and a sandy loam) were maintained at different water contents (WC) 30, 28 and 25 g water kg^?1 soil (sand) and 130, 105 and 95 g water kg^?1 soil (sandy loam) for 14 days, then rewet to the water content at which respiration was optimal [WC 35 (sand), WC200 (sandy loam)] and maintained at this level until day 68. Ground pea straw (C/N 26) was added and incorporated on day 1. The controls were maintained at the optimal water content throughout the 68 days. Respiration rates during the dry phase (days 1?C14) decreased with decreasing water content. The flush of respiration after rewetting peaked on day 15 in the sandy loam and on day 16 in the sand; it was greatest in the soils that had been maintained at the lowest water content [WC25 (sand) and WC95 (sandy loam)]. Cumulative respiration during the remainder of the incubation period in which all soils were maintained at optimal water content increased more strongly in the soils that had been dry compared to the constantly moist control. On the final day of the dry period (day 14), cumulative respiration in the dry soils was 29?C65% (sand) and 67?C94% (sandy loam) of the constantly moist control whereas on day 68 it was 80?C84% (sand) and 86?C96% (sandy loam). The greater increase in cumulative respiration in the previously dry soils can be explained by the reduced decomposition rates during the dry period which resulted in higher substrate availability on day 14 compared to the constantly moist control. Microbial community structure assessed by phospholipid fatty acid analyses changed over time in all treatments but was less affected by water content than respiration; it differed only between the highest and the lowest water content. These differences were maintained throughout the incubation period in the sandy loam and transiently in the sand. It can be concluded that the soil water content during the dry phase affects the size of the flush in microbial activity upon rewetting and that microbial activity in previously dried soils may not be fully restored even after 54 days of moist incubation, suggesting that drying of soil can have a significant and long-lasting impact on microbial functioning.     

Metformin functionalized dendritic fibrous nanosilica (KCC-1-nPr-Met) as an innovative and green nanocatalyst for the efficient synthesis of tetrahydro-4H-chromene derivatives

An innovative nanocatalyst (KCC-1-nPr-Met) has been prepared from the covalent attachment of metformin on the channels and the pores of n-propyl amine functionalized dendritic fibrous nanosilica (DFNS) and used towards efficient, green, and high yield synthesis of tetrahydro-4H-chromenes derivatives by one-pot three-component reaction of aromatic aldehydes, malononitrile, and dimedone in H₂O-EtOH at room temperature. The designed nanocatalyst has been characterized by energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and adsorption/desorption analysis (BET) techniques. Also, field emission scanning electron microscopy (FE-SEM) was used to study the morphology of prepared nanocatalyst. The engineered nanocatalyst with uniform fibrous spheres has dendritic structure, high pore volume (0.35 cm³/g), and great surface area (178 m²/g). Hence, the specific dendritic structure of the prepared nanocatalyst not only improve the diffusion ability of the reactants and products, but also, increase the availability of dynamic sites in the pores and channels of the catalyst. According to the obtained results, a unique strategy was proposed towards the synthesis of important biologically active scaffolds in the presence of nontoxic and environmental friendly nanocatalyst and media. Milder reaction conditions (room temperature), shorter reaction times (5-30 minutes), excellent yields (92%-98%) of the products with higher purity, very simple workup procedure, and using of EtOH: H₂O as a green solvent are the advantages of the presented work.     

Methylglyoxal inhibition of cytosolic ascorbate peroxidase from Nicotiana tabacum

Methylglyoxal (MG) is one of the aldehydes accumulated in plants under environmental stress. Cytosolic ascorbate peroxidase (cAPX) plays a key role in the protection of cells from oxidative damage by scavenging reactive oxygen species in higher plants. A cDNA encoding cAPX, named NtcAPX, was isolated from Nicotiana tabacum. We characterized recombinant NtcAPX (rNtcAPX) as a fusion protein with glutathione S‐transferase to investigate the effects of MG on APX. NtcAPX consists of 250 amino acids and has a deduced molecular mass of 27.5 kDa. The rNtcAPX showed a higher APX activity. MG treatments resulted in a reduction of APX activity and modifications of amino groups in rNtcAPX with increasing K_m for ascorbate. On the contrary, neither NaCl nor cadmium reduced the activity of APX. The present study suggests that inhibition of APX is in part due to the modification of amino acids by MG. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:315–321, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21423     

An investigation on acarbose inhibition and the number of active sites in an amylopullulanase (L14-APU) from an Iranian Bacillus sp.

An amylopullulanase (L₁₄-APU) from an Iranian thermophilic bacterium was purified and the effect of acarbose, as a general inhibitor of α-amylases, on pullulan and starch hydrolysis catalyzed by L₁₄-APU was investigated. The inhibition is a competitive type whereas inhibition constants for pullulan and starch are 99 μM and 72 μM, respectively. Investigation of the reaction rate in a system contains competitive substrates and the inhibition type of acarbose in presence of different substrates suggests that L₁₄-APU possesses only one active site for two activities. The analysis of metal ions and other reagents effects has shown that Ca²⁺, Mg²⁺, Mn²⁺ and Co²⁺ enhanced both activities of the enzyme while N-bromosuccinimide treatment leads to the complete inactivation of the enzyme. The enzyme activity increased in the presence of low concentration of SDS as a surfactant.     

Expression Patterns of ABC Transporter Genes in Fluconazole-Resistant <Emphasis Type="Italic">Candida glabrata</Emphasis>

Clinical management of fungal diseases is compromised by the emergence of antifungal drug resistance in fungi, which leads to elimination of available drug classes as treatment options. An understanding of antifungal resistance at molecular level is, therefore, essential for the development of strategies to combat the resistance. This study presents the assessment of molecular mechanisms associated with fluconazole resistance in clinical Candida glabrata isolates originated from Iran. Taking seven distinct fluconazole-resistant C. glabrata isolates, real-time PCRs were performed to evaluate the alternations in the regulation of the genes involved in drug efflux including CgCDR1, CgCDR2, CgSNQ2, and CgERG11. Gain-of-function (GOF) mutations in CgPDR1 alleles were determined by DNA sequencing. Cross-resistance to fluconazole, itraconazole, and voriconazole was observed in 2.5 % of the isolates. In the present study, six amino acid substitutions were identified in CgPdr1, among which W297R, T588A, and F575L were previously reported, whereas D243N, H576Y, and P915R are novel. CgCDR1 overexpression was observed in 57.1 % of resistant isolates. However, CgCDR2 was not co-expressed with CgCDR1. CgSNQ2 was upregulated in 71.4 % of the cases. CgERG11 overexpression does not seem to be associated with azole resistance, except for isolates that exhibited azole cross-resistance. The pattern of efflux pump gene upregulation was associated with GOF mutations observed in CgPDR1. These results showed that drug efflux mediated by adenosine-5-triphosphate (ATP)-binding cassette transporters, especially CgSNQ2 and CgCDR1, is the predominant mechanism of fluconazole resistance in Iranian isolates of C. glabrata. Since some novel GOF mutations were found here, this study also calls for research aimed at investigating other new GOF mutations to reveal the comprehensive understanding about efflux-mediated resistance to azole antifungal agents.