Genetic Carriers and Genomic Distribution of cadA6—A Novel Variant of a Cadmium Resistance Determinant Identified in Listeria spp.

Listeria monocytogenes is a pathogen responsible for severe cases of food poisoning. Listeria spp. strains occurring in soil and water environments may serve as a reservoir of resistance determinants for pathogenic L. monocytogenes strains. A large collection of Listeria spp. strains (155) isolated from natural, agricultural, and urban areas was screened for resistance to heavy metals and metalloids, and the presence of resistance determinants and extrachromosomal replicons. Of the tested strains, 35% were resistant to cadmium and 17% to arsenic. Sequence analysis of resistance plasmids isolated from strains of Listeria seeligeri and Listeria ivanovii, and the chromosome of L. seeligeri strain Sr73, identified a novel variant of the cadAC cadmium resistance efflux system, cadA6, that was functional in L. monocytogenes cells. The cadA6 cassette was detected in four Listeria species, including strains of L. monocytogenes, isolated from various countries and sources—environmental, food-associated, and clinical samples. This resistance cassette is harbored by four novel composite or non-composite transposons, which increases its potential for horizontal transmission. Since some cadAC cassettes may influence virulence and biofilm formation, it is important to monitor their presence in Listeria spp. strains inhabiting different environments.     

Poly(chitosan-ester-ether-urethane) Hydrogels as Highly Controlled Genistein Release Systems

Polymeric hydrogels play an increasingly important role in medicine, pharmacy and cosmetology. They appear to be one of the most promising groups of biomaterials due to their favorable physicochemical properties and biocompatibility. The objective of the presented study was to synthesize new poly(chitosan-ester-ether-urethane) hydrogels and to study the kinetic release of genistein (GEN) from these biomaterials. In view of the above, six non-toxic hydrogels were synthesized via the Ring-Opening Polymerization (ROP) and polyaddition processes. The poly(ester-ether) components of the hydrogels have been produced in the presence of the enzyme as a biocatalyst. In some cases, the in vitro release rate of GEN from the obtained hydrogels was characterized by near-zero-order kinetics, without “burst release” and with non-Fickian transport. It is important to note that developed hydrogels have been shown to possess the desired safety profile due to lack of cytotoxicity to skin cells (keratinocytes and fibroblasts). Taking into account the non-toxicity of hydrogels and the relatively highly controlled release profile of GEN, these results may provide fresh insight into polymeric hydrogels as an effective dermatological and/or cosmetological tool.     

Sex typing and androgyny: further explorations of the expressive domain

Previous research by Bem has indicated that androgynous individuals of both sexes display "masculine" independence when under pressure to conform as well as "feminine" nurturance when interacting with a kitten. In contrast, sex-typed individuals were low in one or both of these behaviors. The two studies reported here were designed to replicate the low nurturance of the masculine male and to clarify the unexpected finding that feminine females were low in both independence and nurturance. In the first study subjects interacted with a human infant, and in the second study they listened to a lonely student. Taken together, the results of these two studies conceptually replicated the low nurturance of the masculine male and demonstrated that the low nurturance of the feminine female does not extend to her interaction with humans. Finally, evidence was presented in support of Spence, Helmreich, and Stapp's distinction between "androgynous" individuals, who are high in both masculinity and feminity, and "undifferentiated" individuals, who are low in both of these characteristics.     

Microphotoluminescence and perfect ordering of SiGe islands on pit-patterned Si(001) substrates

We show that both the morphology and the optoelectronic properties of SiGe islands growing in the pits of periodically pre-patterned Si(001) substrates are determined by the amount of Ge deposited per unit cell of the pattern. Pit-periods (p) ranging from 300 to 900 nm were investigated, and Ge growth was performed by molecular beam epitaxy (MBE) at temperatures of 690 and 760?°C. The ordered SiGe islands show photoluminescence (PL) emission, which becomes almost completely quenched, once a critical island volume is exceeded. By atomic force and transmission electron microscope images we identify the transition from pyramid-shaped to dome-shaped islands with increasing p. Eventually, the nucleation of dislocations in the islands leads to PL quenching. Below a critical Ge coverage a narrowing and a blue shift of the PL emission is observed, as compared to islands grown on a planar reference area of the same sample.     

An assessment of natural concentrations of selected metals in the bone tissues of the femur head

The study was aimed at assessing the natural concentrations of copper, iron, potassium, lead and cadmium in the femur head using regression analysis. The material was collected during the operation of total hip arthroplasty from patients of southern and central Poland suffering from diagnosed coxarthrosis. In total, 197 samples were collected, including 68 samples of spongious bone, 59 samples of cortical bone and 70 samples of cartilage surface. After wet microwave digestion, the metal content in the samples was measured by atomic absorption spectrophotometry. The average concentrations of metals in the femur head were 67.30 microgFe/g, 760.58 microgK/g, 0.07 microgCd/g, 0.81 microgCu/g and 2.76 microgPb/g. A comparison of metal concentrations in bone tissues assessed by regression analysis to the findings of other authors revealed that the technique can be used to assess the natural concentration of elements in tissues and the results may provide a basis for the evaluation of metal concentrations in the human organism.     

Three Component Composite Scaffolds Based on PCL,Hydroxyapatite, and L-Lysine Obtained in TIPS-SL: Bioactive Material for Bone Tissue Engineering

In this research, we describe the properties of three-component composite foam scaffolds based on poly(ε-caprolactone) (PCL) as a matrix and hydroxyapatite whiskers (HAP) and L-Lysine as fillers (PCL/HAP/Lys with wt% ratio 50/48/2). The scaffolds were prepared using a thermally induced phase separation technique supported by salt leaching (TIPS-SL). All materials were precisely characterized: porosity, density, water uptake, wettability, DSC, and TGA measurements and compression tests were carried out. The microstructure of the obtained scaffolds was analyzed via SEM. It was found that the PCL/HAP/Lys scaffold has a 45% higher Young’s modulus and better wettability compared to the PCL/HAP system. At the same time, the porosity of the system was ~90%. The osteoblast hFOB 1.19 cell response was also investigated in osteogenic conditions (39 °C) and the cytokine release profile of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α was determined. Modification of PCL scaffolds with HAP and L-Lysine significantly improved the proliferation of pre-osteoblasts cultured on such materials.