Characterisation of conditioning layers formed by exopolymeric substances of Pseudomonas NCIMB 2021 on surfaces of AISI 316 stainless steel

This investigation aimed to characterise conditioning layers formed on AISI 316 stainless steel by different types of extracellular polymeric substances (EPS), i.e. biofilm, planktonic and capsular exopolymers, isolated from continuous cultures of marine Pseudomonas received from the National Collection of Industrial and Marine Bacteria (strain NCIMB 2021). Colorimetric assays and gas chromatography‐mass spectrometry analysis confirmed previously obtained results based on a FTIR and SDS‐PAGE study of Pseudomonas NCIMB 2021 EPS demonstrating the presence of protein, neutral and amino sugars and uronic acids. The content and the ratio of these macromolecules differed depending on the type of EPS. X‐ray photoelectron spectroscopy revealed that conditioning layers formed upon exposure of steel to EPS solutions were chemically dissimilar. It is proposed that the observed difference in the chemistry of conditioning layers is the likely reason for reported differences in attachment of Pseudomonas cells to EPS‐conditioned steel surfaces.     

A live bioprobe for studying diatom-surface interactions

Atomic force microscopy has been employed to compare the adhesion of Navicula species I diatoms to surfaces of a hydrophobic elastomer, Intersleek, and a hydrophilic mineral, mica. This was accomplished using tipless atomic force microscopy cantilevers functionalized with live diatom cells. Both surfaces were tested with the same diatom bioprobe. Force versus distance curves generated during these experiments revealed comparable cell adhesion strengths on Intersleek and mica, indicating that Navicula diatoms secrete extracellular polymeric substances with hydrophobic and hydrophilic properties. A statistical analysis of force curves was carried out and the average values of works of detachment of a diatom from Intersleek and mica surfaces were determined.     

Oxidant and antioxidant status of Turkish marasmic children: A single center study

The aim of this study was to investigate plasma oxidant and antioxidant status in Turkish marasmic children. The study population consisted of 38 marasmic children (group I) and 28 age-matched children (group II) who were apparently well, with weight-forage >80% of the standards in the same region. After overnight fasting, venous blood samples were drawn and immediately transferred to heparinized and normal tubes. Plasma antioxidant potential (AOP), and malondialdehyde (MDA) levels were measured in both groups. The plasma MDA levels were found to be higher in group I than in group II. However, plasma AOP values were lower in group I than in group II. The present study suggests that AOP is reduced due to an impaired antioxidant system in the plasma of malnourished patients. This oxidant stress causes significant peroxidation. Also, the antioxidant defense system of the patients is deteriorated in marasmus.     

Iloprost (ZK 36374) modulates the responses to beta-adrenoceptor agonists in guinea-pig airways and pulmonary vasculature

The effect of iloprost on airway smooth muscles and its influence on the actions of beta-agonists and histamine were studied in the isolated perfused lung and isolated tracheal strips from guinea-pigs. Bolus injection of iloprost into the pulmonary artery elicited a concentration-dependent decrease in pulmonary perfusion pressure and an increase in airway resistance. These effects are not mediated through cholinergic, serotoninergic and histaminergic receptors. A rapid tachyphylaxis affected the effect of iloprost in airway resistance but not in pulmonary perfusion pressure. Iloprost did not induce a response in the isolated tracheal strips and did not alter the effect of histamine in both tracheal strips and airway resistance. This compound, however, caused an inhibition in the airway resistance-reducing effect of adrenaline and isoprenaline in the isolated perfused lung and a potentiation in the perfusion pressure-increasing effect of adrenaline. Iloprost also inhibited the relaxing effect of adrenaline and isoprenaline in the isolated tracheal strips precontracted with histamine and potentiated the inhibitory effect of propranolol against adrenaline and isoprenaline. From these results it was concluded that: Iloprost, a stable analogue of prostacyclin, modulates the beta-adrenoceptor blocking effect of propranolol in both airway smooth muscles and pulmonary vasculature.     

A current approach to the control of filamentous fungal growth in media: microparticle enhanced cultivation technique

Various strategies have been carried out to date in order to overcome the problem of the adverse effects of bulk fungal growth in bioreactors. Nevertheless, previous conventional methods such as modifying the cultivation temperature or pH resulted in limited biomass production and consequently lower yields. In recent years microparticle enhanced cultivation (MPEC) techniques are one of the most remarkable and novel methods employed for submerged fungal production to overcome bulk microbial growth. In addition to low cost advantages, MPEC also provides benefits such as not interfering with fungal metabolism, enhancing final product concentration and improving homogeneity in the fermentation broth. In this review, a comparison of conventional and novel methods to control fungal morphology has been discussed. Additionally, the application of microparticles in fungal fermentations, their benefits to the process in terms of fungal morphology, biomass accumulation, substrate consumption, and product formation also effect mechanisms of microparticle function are discussed in detail.     

An alternative method to minimize pain in the split-thickness skin graft donor site

In the art of plastic surgery, the reconstruction of tissue defects to obtain cosmetic and functional recovery is the major concern. Skin grafting is the most frequently used procedure for reconstructing defects of various size and anatomical localizations. On the other hand, donor-site problems associated with this invaluable procedure are inevitable. Various methods are used in the postoperative management of the partial-thickness donor site created during the harvest of a split-thickness skin graft. Each technique has the potential for complications of fluid loss, excessive pain, prolonged period of healing and immobilization, hypertrophic scarring, and undesirable pigmentation. Donor-site pain is probably the most disturbing complication in the early postoperative period. The aim of this article is to point out the significance of donor-site pain, which has not been emphasized thoroughly in the literature, and to introduce flap skin as a potential graft donor site for patients in whom reduction of donor-site morbidity is of primary concern. The principal goal of the technique described in this article is to eliminate donor-site pain by harvesting the graft from the flap that is insensate after the elevation. In 15 patients, the overlying skin of the flap that had been used for reconstructive purposes was used as the donor site (group I). In the remaining 23 patients, the posterolateral thigh was used as the donor site (group II). Donor-site discomfort was recorded during the first 8 days postoperatively using a visual analogue scale. To analyze the data, we used the Friedman test, Dunn's multiple comparison test, and Mann-Whitney U test. It was observed that the visual analogue scale of both of the groups showed a significant decrease within days (group I, p < 0.0001; group II, p < 0.0001). The mean pain scores were significantly lower in group I than in group II (p < 0.0001). When donor-site pain is of primary concern, this procedure provides uneventful and comfortable healing while avoiding postoperative pain in the donor site. For that reason, this technique might be used in appropriate cases to minimize donor-site pain.     

Interchanging Functionality Among Homologous Elongation Factors Using Signatures of Heterotachy

Numerous models of molecular evolution have been formulated to describe the forces that shape sequence divergence among homologous proteins. These models have greatly enhanced our understanding of evolutionary processes. Rarely are such models empirically tested in the laboratory, and even more rare, are such models exploited to generate novel molecules useful for synthetic biology. Here, we experimentally demonstrate that the heterotachy model of evolution captures signatures of functional divergence among homologous elongation factors (EFs) between bacterial EF-Tu and eukaryotic eEF1A. These EFs are GTPases that participate in protein translation by presenting aminoacylated-tRNAs to the ribosome. Upon release from the ribosome, the EFs are recharged by nucleotide exchange factors EF-Ts in bacteria or eEF1B in eukaryotes. The two nucleotide exchange factors perform analogous functions despite not being homologous proteins. The heterotachy model was used to identify a set of sites in eEF1A/EF-Tu associated with eEF1B binding in eukaryotes and another reciprocal set associated with EF-Ts binding in bacteria. Introduction of bacterial EF-Tu residues at these sites into eEF1A protein efficiently disrupted binding of cognate eEF1B as well as endowed eEF1A with the novel ability to bind bacterial EF-Ts. We further demonstrate that eEF1A variants, unlike yeast wild-type, can function in a reconstituted in vitro bacterial translation system.     

Kinetic analysis of a Golgi UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-alpha-glucosaminyltransferase from Dictyostelium

Mucin-type O-glycosylation in Dictyostelium is initiated in the Golgi by a UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-alpha-glucosaminyltransferase (Dd-pp alphaGlcNAcT2) whose sequence is distantly related to the sequences of animal polypeptide-Thr/Ser N-acetyl-alpha-galactosaminyltransferases, such as murine Mm-pp alphaGalNAcT1. To evaluate the significance of this similarity, highly purified Dd-pp alphaGlcNAcT2 was assayed using synthetic peptides derived from known substrates. Dd-pp alphaGlcNAcT2 strongly prefers UDP-GlcNAc over UDP-GalNAc, preferentially modifies the central region of the peptide, and modifies Ser in addition to Thr residues. Initial velocity measurements performed over a matrix of UDP-GlcNAc donor and peptide acceptor concentrations indicate that the substrates bind to the enzyme in ordered fashion before the chemical conversion. Substrate inhibition exerted by a second peptide, and the pattern of product inhibition exerted by UDP, suggest that UDP-GlcNAc binds first and the peptide binds second, consistent with data reported for Mm-pp alphaGalNAcT1. Two selective competitive inhibitors of Mm-pp alphaGalNAcT1, retrieved from a screen of neutral-charge uridine derivatives, also inhibit Dd-pp alphaGlcNAcT1 competitively with only slightly less efficacy. Inhibition is specific for Dd-pp alphaGlcNAcT2 relative to two other Dictyostelium retaining glycosyltransferases. These data support a phylogenetic model in which the alphaGlcNAcT function in unicellular eukaryotes converted to an alphaGalNAcT function in the metazoan ortholog while conserving a similar reaction mechanism and active site architecture.