Vancomycin: An analysis and evaluation of eight population pharmacokinetic models for clinical application in general adult population.

INTRODUCTION: Based on the recent guidelines for vancomycin therapeutic drug monitoring (TDM), the area under the curve to minimum inhibitory concentration ratio was to be employed combined with the usage of population pharmacokinetic (popPK) model for dosing adaptation. Yet, deploying these models in a clinical setting requires an external evaluation of their performance. OBJECTIVES: This study aimed to evaluate existing vancomycin popPK models from the literature for the use in TDM within the general patient population in a clinical setting. METHODS: The models under external evaluation were chosen based on a review of literature covering vancomycin popPK models developed in general adult populations. Patients' data were collected from Charles-Le Moyne Hospital (CLMH). The external evaluation was performed with NONMEM® (v7.5). Additional analyses such as evaluating the impact of number of samples on external evaluation, Bayesian forecasting, and a priori dosing regimen simulations were performed on the best performing model. RESULTS: Eight popPK models were evaluated with an independent dataset that included 40 patients and 252 samples. The model developed by Goti and colleagues demonstrated superior performance in diagnostic plots and population predictive performance, with bias and inaccuracy values of 0.251% and 22.7%, respectively, and for individual predictive performance, bias and inaccuracy were -4.90% and 12.1%, respectively. When limiting the independent dataset to one or two samples per patient, the Goti model exhibited inadequate predictive performance for inaccuracy, with values exceeding 30%. Moreover, the Goti model is suitable for Bayesian forecasting with at least two samples as prior for the prediction of the next trough concentration. Furthermore, the vancomycin dosing regimen that would maximize therapeutic targets of area under the curve to minimum inhibitory concentration ratio (AUC24/MIC) and trough concentrations (Ctrough) for the Goti model was 20 mg/kg/dose twice daily. CONCLUSION: Considering the superior predictive performance and potential for Bayesian forecasting in the Goti model, future research aims to test its applicability in clinical settings at CLMH, both in a priori and a posteriori scenario.

Characterization of cyanobacterial isolates from freshwater and saline subtropical desert lakes.

Characterization of Cyanobacteria in lakes with different physicochemical properties provides insights into the diversity of this phylum and knowledge of their features that are relevant to biotechnology applications. Six Cyanobacterial isolates were recovered from freshwater Lake Nasser and saline Lake Qarun, Egypt. The isolates were identified based on both morphology and molecular markers, 16S rRNA, and RuBisCO cbbL genes. The isolates SN1, SN2, SN3, SN4, Q1, and Q2 showed homologies with Merismopedia, Oscillatoria, Limnothrix, Persinema, and Jacksonvillea, respectively. The cbbL sequences for isolates SN1, Q1, and Q2 represented the first records for candidates relating to the genera Merismopedia and Persinema, and Jacksonvillea, respectively. Biochemical contents, carbohydrates, proteins, lipids, pigments, and ash-free dry weight were measured for each isolate. Isolate SN2 had the highest content of allophycocyanin, 71 ± 4.8 mg/g DW, and phycoerythrin, 98 ± 6.7 mg/g DW, while the isolate SN4 had the highest composition of total protein, lipid, carotenoid, and chlorophyll a, recording 364.7 ± 6.4 mg/g DW, 67.6 ± 0.2 mg/g DW, 0.261 ± 0.01 mg/g DW, and 10 ± 0.6 mg/g DW, respectively. Isolate Q1 recorded the maximum amount of phycocyanin, 114 ± 20.7 mg/g DW among isolates. The isolate Q2 was observed to have the highest carbohydrate content, 274 ± 14.5 (mg/g DW), and ash-free dry weight, 891.8 ± 2.8 mg/g DW. Thus, the study indicated that the current isolates may represent promising resources for biotechnological applications.

Silver nanoparticles as a viricidal agent to inhibit plant-infecting viruses and disrupt their acquisition and transmission by their aphid vector.

Silver nanoparticles (AgNPs) are a potentially effective tool for preventing viral plant diseases. This study was carried out to evaluate the effectiveness of AgNPs for managing bean yellow mosaic virus (BYMV) disease in faba bean plants from the plant-virus-vector interaction side. AgNPs were evaluated as foliar protective and curative agents. In addition, the effect of AgNPs on virus acquisition and transmission by its vector aphid was investigated. The results indicated that AgNPs exhibited curative viricidal activity and were able to inactivate BYMV when applied 48 hours after virus inoculation. The occurrence of disease was prevented using an AgNP concentration as low as 100 mg L-1, whereas virus infection was completely inhibited when plants were preventatively treated with AgNPs at a concentration of to 200 mg L-1 24 h before virus inoculation. AgNPs proved to be highly bio-reactive, binding to viral particles and suppressing their replication and accumulation within plant tissues. Moreover, AgNPs, at all concentrations tested, were found to upregulate the pathogenesis-related gene PR-1 and induce the production of defense-related oxidizing enzymes in treated plants. Exposure of aphids to AgNPs-treated plants before virus acquisition reduced BYMV acquisition and transmission efficiency by 40.65 to 100% at 24 h post-application, depending on the AgNP dosage. At 10 days after treatment, virus acquisition was reduced by 36.82% and 79.64% upon exposure to AgNPs at a concentration of 250 and 300 mg L-1, respectively. These results suggest that AgNPs have curative viricidal activity due to targeting the virus coat protein and affecting virus-vector interactions. Accordingly, AgNPs may contribute to alleviating the natural disease and virus transmission under field conditions. This is the first report on the activity of nanomaterials against plant virus acquisition and transmission by insects.

Disilicate Dental Ceramic Surface Preparation by 1070 nm Fiber Laser: Thermal and Ultrastructural Analysis.

Lithium disilicate dental ceramic bonding, realized by using different resins, is strictly dependent on micro-mechanical retention and chemical adhesion. The aim of this in vitro study was to investigate the capability of a 1070 nm fiber laser for their surface treatment. Samples were irradiated by a pulsed fiber laser at 1070 nm with different parameters (peak power of 5, 7.5 and 10 kW, repetition rate (RR) 20 kHz, speed of 10 and 50 mm/s, and total energy density from 1.3 to 27 kW/cm²) and the thermal elevation during the experiment was recorded by a fiber Bragg grating (FBG) temperature sensor. Subsequently, the surface modifications were analyzed by optical microscope, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS). With a peak power of 5 kW, RR of 20 kHz, and speed of 50 mm/s, the microscopic observation of the irradiated surface showed increased roughness with small areas of melting and carbonization. EDS analysis revealed that, with these parameters, there are no evident differences between laser-processed samples and controls. Thermal elevation during laser irradiation ranged between 5 °C and 9 °C. A 1070 nm fiber laser can be considered as a good device to increase the adhesion of lithium disilicate ceramics when optimum parameters are considered.

Microhardness evaluations of CAD/CAM ceramics irradiated with CO2 or Nd:YAP laser.

BACKGROUND AND AIMS: The aim of this study was to measure the microhardness values of irradiated computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics surfaces before and after thermal treatment. MATERIALS AND METHODS: Sixty CAD/CAM ceramic discs were prepared and grouped by material, i.e. lithium disilicate ceramic (Emax CAD) and zirconia ceramic (Emax ZirCAD). Laser irradiation at the material surface was performed with a carbon dioxide laser at 5 Watt (W) or 10 W power in continuous mode (CW mode), or with a neodymium:yttrium aluminum perovskite (Nd:YAP) laser at 10 W on graphite and non-graphite surfaces. Vickers hardness was tested at 0.3 kgf for lithium disilicate and 1 kgf for zirconia. RESULTS: Emax CAD irradiated with CO2 at 5 W increased microhardness by 6.32 GPa whereas Emax ZirCAD irradiated with Nd:YAP decreased microhardness by 17.46 GPa. CONCLUSION: CO2 laser effectively increases the microhardness of lithium disilicate ceramics (Emax CAD).

Shear bond, wettability and AFM evaluations on CO2 laser-irradiated CAD/CAM ceramic surfaces.

The purpose of this study is to determine the CO2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS), roughness (Rg) and wettability (Wt) of resin cement to CAD/CAM ceramics. Sixty (CAD/CAM) ceramic discs were prepared and distributed into six different groups: group A, control lithium disilicate (Li); group B, control zirconia (Zr); group C, Li: CO2/HF/Si; group D, Li: HF/Si; group E, Zr: CO2/Sb/Si; group F, Zr: Sb/Si. Result showed significant difference between irradiated and non-irradiated in terms of shear bond strength for zirconia ceramics (p value = 0.014). Moreover, partial surface wettability for irradiated and non-irradiated ceramics. Irradiated surface demonstrated more rough surface in lithium disilicate than zirconia ceramics. CO2 irradiation could increase shear bond strength, surface roughness and wettability for both CAD/CAM ceramics.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

BACKGROUND AND AIMS: The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. MATERIAL AND METHODS: Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. RESULTS: The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CONCLUSION: CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

Aerophytic Cyanophyceae (cyanobacteria) from some Cairo districts, Egypt.

Twenty three aerophytic blue-green algal species were isolated and identified from 5 districts in Cairo, namely: Nasr City, Abassiya, Downtown, Maadi and Tebbin. Downtown contained the highest numbers of total algal species (13 species) during the study throughout the years 2004-2005 in comparison to other districts. The composition of aeroalgal taxa varied with seasonal changes. Chroococcus limenticus, Lyngbya lagerheimii, Phormidium ambigum and Schizothrix purpurascens have been isolated during the both years 2004-2005, while the rest of algal species (nineteen species) have been trapped either in 2004 or 2005. Nostoc spp. is the most common isolate of all algal isolates during the study. Analysis of air pollutants such as SO2, NO2, suspended particles less than 10 micro (PM10), black smoke and lead are also recorded. Downtown showed the highest concentration of SO2, NO2 and PM10 level during the present study in comparison to other sites. The interaction between air pollutants and aerophytic Cyanophyceae species was concerned.