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Background Biofilm formation is an essential virulence factor that creates a highly protected growth mode for Staphylococcus aureus ( S. aureus ) to survive in any hostile environment. Antibiotic sub-minimal inhibitory concentration (sub-MIC) may modulate the biofilm formation ability of bacterial pathogens, thereby affecting bacterial pathogenesis and infection outcomes. Intense antimicrobial therapy to treat biofilm-associated infections can control the pathogenic infection aggravation but cannot guarantee its complete eradication. Objective This study aimed to assess the sub-MICs effect of 5 different antimicrobial classes on biofilm-forming capacity among Staphylococcus aureus clinical isolates using three different biofilm quantitation techniques. Methods In this study, the effects of 5 different antimicrobial agents, namely, azithromycin, gentamicin, ciprofloxacin, doxycycline, and imipenem, at sub-MICs of 12.5%, 25%, and 50% were tested on 5 different clinical isolates of S. aureus . The biofilms formed in the absence and presence of different antimicrobial sub-MICs were then assessed using the following three different techniques: the crystal violet (CV) staining method, the quantitative PCR (qPCR) method, and the spread plate method (SPM). Results Biofilm formation was significantly induced in 64% of the tested conditions using the CV technique. On the other hand, the qPCR quantifying the total bacterial count and the SPM quantifying the viable bacterial count showed significant induction only in 24% and 17.3%, respectively (Fig. 1). The difference between CV and the other techniques indicates an increase in biofilm biomass without an increase in bacterial growth. As expected, sub-MICs did not reduce the viable cell count, as shown by the SPM. The CV staining method revealed that sub-MICs of imipenem and ciprofloxacin had the highest significance rate (80%) showing an inductive effect on the biofilm development. On the other hand, doxycycline, azithromycin, and gentamicin displayed lower significance rates of 73%, 53%, and 47%, respectively. Conclusion Exposure to sub-MIC doses of antimicrobial agents induces the biofilm-forming capacity of S. aureus via increasing the total biomass without significantly affecting the bacterial growth of viable count.

The current work presents a new structure based on Au/PVA/SiO2/p-Si/Al that has not been studied before. An aqueous solution of polyvinyl alcohol (PVA) polymer gel was deposited on the surface of SiO2/Si using the spin-coating technique. The silicon wafer was left to be oxidized in a furnace at 1170 k for thirty minutes, creating an interdiffusion layer of SiO2. The variations in the dielectric constant (Є′), dielectric loss (Є″), and dielectric tangent (tanδ) with the change in the frequency, voltage, and temperature were analyzed. The results showed an increase in the dielectric constant (Є′) and a decrease in the dielectric loss (Є″) and tangent (tanδ); thus, the Au/PVA/SiO2/p-Si/Al heterostructure has opened up new frontiers for the semiconductor industry, especially for capacitor manufacturing. The Cole–Cole diagrams of the Є″ and Є′ have been investigated at different temperatures and voltages. The ideality factor (n), barrier height (Φb), series resistance (Rs), shunt resistance (Rsh), and rectification ratio (RR) were also measured at different temperatures.

Besides its antimicrobial action, doxycycline (DX) has lately been repurposed as a small-molecule drug for osteogenic purposes. However, osteogenic DX application is impeded by its dose-dependent cytotoxicity. Further, high-dose DX impairs cell differentiation and mineralization. Integrating DX into a biomaterial-based delivery system that can control its release would not only ameliorate its cytotoxic actions but also augment its osteogenic activity. In this work, we managed to engineer novel composite DX-hydroxyapatite-polycaprolactone nanoparticles (DX/HAp/PCL) to modify DX osteogenic potential. Employing a 2 -factorial design, we first optimized HApN for surface-area attributes to maximize DX loading. Composite DX/HAp/PCL were then realized using a simple emulsification technique, characterized using various in vitro methods, and evaluated for in vitro osteogenesis. The developed HApN exhibited a favorable crystalline structure, Ca:P elemental ratio (1.67), mesoporous nature, and large surface area. DX/HAp/PCL achieved the highest reported entrapment efficiency (94.77%±1.23%) of DX in PCL-based particles. The developed composite system achieved controlled release of the water-soluble DX over 24 days. Moreover, the novel composite nanosystem managed to significantly ameliorate DX cytotoxicity on bone-marrow stem cells, as well as enhance its overall proliferation potential. Alkaline phosphatase and mineralization assays revealed superior osteodifferentiation potential of the composite system. Quantification of gene expression demonstrated that while DX solution was able to drive bone-marrow stem cells down the osteogenic lineage into immature osteoblasts after 10-day culture, the innovative composite system allowed maturation of osteodifferentiated cells. To the best of our knowledge, this is the first work to elaborate the impact of DX on the expression of osteogenic genes: , OSP, and BSP. Further, the osteogenicity of a DX-loaded particulate-delivery system has not been previously investigated. Our findings indicate that repurposing low-dose DX in complementary biomaterial-based nanosystems can offer a prominent osteogenic candidate for bone-regeneration purposes.

Background Chemical Plaque control by antimicrobial agent application can defend the teeth against caries. S. mutans is considered the main etiologic factor for caries. This was an in vitro study to compare between the efficacy of chlorhexidine diaceteate varnish, and an organoselenium sealant, to prevent S. mutans biofilm formation on human teeth. Methods Fourty five premolars extracted for orthodontic purposes were randomly divided into 3 groups of 15 teeth each. One control group and two test groups, chlorhexidine diaceteate varnish and an organoselenium sealant. The teeth were autoclaved before S. mutans biofilm was induced on to each in their respective groups. The reading T1 was taken for each tooth to assess the number of S. mutans attached in order to compare for differences in surface area among the 3 groups. The respective test materials were applied onto the teeth and biofilm induced onto them in their respective groups. The reading T2 was taken for the 2 test groups. The 3 groups were then subjected to aging for a period equivalent to 5 months before the biofilm was induced to take the reading T3 for the number of S. mutans . We used vortexing of the teeth to disrupt the biofilm at time points T1, T2 and T3. S. mutans count was then done using PCR. Results There were significantly lower S. mutans counts in the control group as compared to the chlorhexidine diacetate group at T3.There were no other statistically significant differences found. Conclusion Both organoselenium and Chlorhexidine diacetate do not inhibit S. mutans biofilm attachment onto the teeth.

In rod-shaped bacteria, the bacterial actin ortholog MreB is considered to organize the incorporation of cell wall precursors into the side-wall, whereas the tubulin homologue FtsZ is known to tether incorporation of cell wall building blocks at the developing septum. For intracellular bacteria, there is no need to compensate osmotic pressure by means of a cell wall, and peptidoglycan has not been reliably detected in Chlamydiaceae. Surprisingly, a nearly complete pathway for the biosynthesis of the cell wall building block lipid II has been found in the genomes of Chlamydiaceae. In a previous study, we discussed the hypothesis that conservation of lipid II biosynthesis in cell wall-lacking bacteria may reflect the intimate molecular linkage of cell wall biosynthesis and cell division and thus an essential role of the precursor in cell division. Here, we investigate why spherical-shaped chlamydiae harbor MreB which is almost exclusively found in elongated bacteria (i.e. rods, vibrios, spirilla) whereas they lack the otherwise essential division protein FtsZ. We demonstrate that chlamydial MreB polymerizes in vitro and that polymerization is not inhibited by the blocking agent A22. As observed for MreB from Bacillus subtilis, chlamydial MreB does not require ATP for polymerization but is capable of ATP hydrolysis in phosphate release assays. Co-pelleting and bacterial two-hybrid experiments indicate that MreB from Chlamydophila (Chlamydia) pneumoniae interacts with MurF, MraY and MurG, three key components in lipid II biosynthesis. In addition, MreB polymerization is improved in the presence of MurF. Our findings suggest that MreB is involved in tethering biosynthesis of lipid II and as such may be necessary for maintaining a functional divisome machinery in Chlamydiaceae.

Viruses play an important role in cancer development as about 12% of cancer types are linked to viral infections. Viruses that induce cellular transformation are known as oncoviruses. Although the mechanisms of viral oncogenesis differ between viruses, all oncogenic viruses share the ability to establish persistent chronic infections with no obvious symptoms for years. During these prolonged infections, oncogenic viruses manipulate cell signaling pathways that control cell cycle progression, apoptosis, inflammation, and metabolism. Importantly, it seems that most oncoviruses depend on these changes for their persistence and amplification. Metabolic changes induced by oncoviruses share many common features with cancer metabolism. Indeed, viruses, like proliferating cancer cells, require increased biosynthetic precursors for virion production, need to balance cellular redox homeostasis, and need to ensure host cell survival in a given tissue microenvironment. Thus, like for cancer cells, viral replication and persistence of infected cells frequently depend on metabolic changes. Here, we draw parallels between metabolic changes observed in cancers or induced by oncoviruses, with a focus on pathways involved in the regulation of glucose, lipid, and amino acids. We describe whether and how oncoviruses depend on metabolic changes, with the perspective of targeting them for antiviral and onco-therapeutic approaches in the context of viral infections.

Heterologous overexpression of foreign proteins in Escherichia coli often leads to insoluble aggregates of misfolded inactive proteins, so-called inclusion bodies. To solve this problem use of chaperones or in vitro refolding procedures are the means of choice. These methods are time consuming and cost intensive, due to additional purification steps to get rid of the chaperons or the process of refolding itself. We describe an easy to use lab-scale method to avoid formation of inclusion bodies. The method systematically combines use of co-solvents, usually applied for in vitro stabilization of biologicals in biopharmaceutical formulation, and periplasmic expression and can be completed in one week using standard equipment in any life science laboratory. Demonstrating the unique power of our method, we overproduced and purified for the first time an active chlamydial penicillin-binding protein, demonstrated its function as penicillin sensitive DD-carboxypeptidase and took a major leap towards understanding the \"chlamydial anomaly.\"

The optical properties of mono‐ and trilayer graphene on SiO2/Si substrate are studied at hydrogen Lyman‐alpha (121.6 nm) spectral line for the first time. The optical anisotropy of graphene at this wavelength is experimentally demonstrated by retrieving the anisotropic “effective” optical constants. The results confirm that the axis of symmetry is nearly perpendicular to the surface and coherently related to the π‐orbitals’ structural orientation. Furthermore, it is observed that graphene strongly affects the performances of the substrate by inducing a pseudo‐Brewster angle downshift, which depends on the number of graphene layers. This finding is in contrast with what occurs in the visible spectral range, where the upshift of the pseudo‐Brewster angle is experienced in similar samples. Remarkable optical properties of graphene are investigated experimentally in the vacuum ultraviolet spectral region. A layer dependent downshift of the pseudo‐Brewster angle is observed at 121.6 nm line in case of substrate covered with mono and tri‐layer graphene. First experimental evidence of optical anisotropy and anisotropic optical constants of graphene (1 and 3 L) are deduced at hydrogen Lyman alpha.

Thalassemia is one of the most prevalent causes of chronic hemolysis worldwide and the commonest cause of chronic hemolysis in Egypt. It results from hemoglobinopathies, consisted of 2 main types (thalassemia major and thalassemia minor) and each type has many different subtypes.Beta-thalassemia major ( β -thalassemia) presents after 6 months of age with symptoms of chronic hemolysis as facial bone deformities, fatigue, growth failure, dyspnea, jaundice and hepatosplenomegaly. Glucose 6 phosphate dehydrogenase (G6PD) is the enzyme responsible for catalyzing the first step in the pentose phosphate pathway (the hexose monophosphate shunt) to generate Nicotineamide Adenine Dinucleotide Phosphate (NADPH) which is subsequently utilized in processes that reduce hydrogen peroxide (H2O2) to water, ameliorating oxidative stress in red blood cells (RBCs). Approximately 400 million people worldwide are G6PD deficient making it the most common human enzyme deficiency.Nowadays, blood donors are not routinely screened for G6PD deficiency, and blood centre policies differ regarding deferral of known G6PD-deficient donors, so RBC transfusion-dependent patients may be at greater risk of receiving blood from G6PD?deficient donors.Because G6PD activity decreases as RBCs age in vivo the question was raised as to whether the same phenomenon occurs during refrigerated storage. Studies of G6PD activity during RBC storage under standard blood-banking conditions show a range of results, with some demonstrating no decrease in G6PD activity or activity decreases of up to 35% , may be attriubated to difference in storage methods