Selenium Nanoparticles as Candidates for Antibacterial Substitutes and Supplements against Multidrug-Resistant Bacteria.

In recent years, multidrug-resistant (MDR) bacteria have increased rapidly, representing a major threat to human health. This problem has created an urgent need to identify alternatives for the treatment of MDR bacteria. The aim of this study was to identify the antibacterial activity of selenium nanoparticles (SeNPs) and selenium nanowires (SeNWs) against MDR bacteria and assess the potential synergistic effects when combined with a conventional antibiotic (linezolid). SeNPs and SeNWs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential, and UV-visible analysis. The antibacterial effects of SeNPs and SeNWs were confirmed by the macro-dilution minimum inhibitory concentration (MIC) test. SeNPs showed MIC values against methicillin-sensitive S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA), and vancomycin-resistant enterococci (VRE) at concentrations of 20, 80, 320, and >320 µg/mL, respectively. On the other hand, SeNWs showed a MIC value of >320 µg/mL against all tested bacteria. Therefore, MSSA, MRSA, and VRSA were selected for the bacteria to be tested, and SeNPs were selected as the antimicrobial agent for the following experiments. In the time-kill assay, SeNPs at a concentration of 4X MIC (80 and 320 µg/mL) showed bactericidal effects against MSSA and MRSA, respectively. At a concentration of 2X MIC (40 and 160 µg/mL), SeNPs showed bacteriostatic effects against MSSA and bactericidal effects against MRSA, respectively. In the synergy test, SeNPs showed a synergistic effect with linezolid (LZD) through protein degradation against MSSA and MRSA. In conclusion, these results suggest that SeNPs can be candidates for antibacterial substitutes and supplements against MDR bacteria for topical use, such as dressings. However, for use in clinical situations, additional experiments such as toxicity and synergistic mechanism tests of SeNPs are needed.

Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria.

Multidrug-resistant (MDR) bacteria are increasing due to the abuse and misuse of antibiotics, and nosocomial infections by MDR bacteria are also increasing. The aim of this study was to identify new substances that can target MDR bacteria among 12 plant extracts that are known to have antibacterial effects. The experiments were performed by the disk diffusion test and microdilution minimum inhibitory concentration (MIC) test, as described by the Clinical and Laboratory Standards Institute (CLSI). By screening against methicillin-sensitive Staphylococcus aureus (MSSA), grapefruit seed extract (GSE) was selected from 12 plant extracts for subsequent experiments. GSE showed antibacterial effects against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) in the disk diffusion test. Even at the lowest concentration, GSE showed antibacterial activity in the microdilution MIC test. As a result, we can conclude that GSE is a naturally derived antibacterial substance that exhibits a favorable antibacterial effect even at a very low concentration, so it is a good candidate for a natural substance that can be used to prevent or reduce nosocomial infections as coating for materials used in medical contexts or by mixing a small amount with other materials.

The Biomineralization of a Bioactive Glass-Incorporated Light-Curable Pulp Capping Material Using Human Dental Pulp Stem Cells.

The aim of this study was to investigate the biomineralization of a newly introduced bioactive glass-incorporated light-curable pulp capping material using human dental pulp stem cells (hDPSCs). The product (Bioactive® [BA]) was compared with a conventional calcium hydroxide-incorporated (Dycal [DC]) and a light-curable (Theracal® [TC]) counterpart. Eluates from set specimens were used for investigating the cytotoxicity and biomineralization ability, determined by alkaline phosphatase (ALP) activity and alizarin red staining (ARS). Cations and hydroxide ions in the extracts were measured. An hDPSC viability of less than 70% was observed with 50% diluted extract in all groups and with 25% diluted extract in the DC. Culturing with 12.5% diluted BA extract statistically lowered ALP activity and biomineralization compared to DC (p < 0.05), but TC did not (p > 0.05). Ca (~110 ppm) and hydroxide ions (pH 11) were only detected in DC and TC. Ionic supplement-added BA, which contained similar ion concentrations as TC, showed similar ARS mineralization compared to TC. In conclusion, the BA was similar to, yet more cytotoxic to hDPSCs than, its DC and TC. The BA was considered to stimulate biomineralization similar to DC and TC only when it released a similar amount of Ca and hydroxide ions.

Inclusion of phytogenic blends in different nutrient density diets of meat-type ducks.

A total of 160 1-day-old ducklings (average initial body weight of 53 g), were used in a 42-d feeding trial to evaluate the effects of reducing nutrient density of diets, and supplementing the diets with a phytogenic blend (quillaja, anise, and thyme) on their growth, carcass quality, and nutrient digestibility. After checking body weight on d 1, the birds were sorted into pens with 5 birds/pen and 8 pens/treatment. The treatments were: T1, Basal diet; T2, T1+150 ppm phytogenic blend; T3, T1-(1% CP, 0.04% Lys, 0.05% Met+Cys, 0.02% Ca, and 0.02% P, and 50 kcal ME); T4, T3+150 ppm phytogenic blend. The results indicated that reducing nutrient density of the diets had an adverse effect (P<0.05) on body weight gain (BWG) on d 1 to 21, d 21 to 42, and the overall experimental period. Supplementing the diets with the phytogenic blend improved (P<0.05) BWG and feed conversion ratio (FCR) on d 21 to 42 and the overall experimental period. Feed intake was not affected by treatments. Low nutrient density diets increased (P<0.05) the cooking loss percentage of breast meat. Supplementing the diets with the phytogenic blend decreased (P<0.05) the lightness of breast meat. The percentage of drip loss was influenced (P<0.05) by nutrient density and the phytogenic blend on d 1 and d 7. The relative weights of breast meat, abdominal fat, gizzard, liver, spleen, and bursa of Fabricius, pH, and TBARS values were not affected by the treatments. The digestibility of dry matter, energy, nitrogen, ADF, and NDF was decreased (P<0.05) by reducing nutrients density of the diets, but addition of the phytogenic blend alleviated (P<0.05) the negative effects of lowering the nutrient density. The results indicated that the ducks fed high nutrient density diets supplemented with the phytogenic blend showed higher BWG and nutrient digestibility and lower FCR, cooking loss, drip loss, and TBARS value, without any negative effect on meat quality and relative organs weights.

A study on the fracture strength of implant-supported restorations using milled ceramic abutments and all-ceramic crowns.

PURPOSE: The purpose of this study was to compare five different abutment-crown combinations for single implant-supported restorations regarding their capabilities to withstand loads. MATERIALS AND METHODS: Fifty implants were placed into resin blocks, and the restorations were connected to the implants. The five tested restorations were: (1) metal-ceramic crowns cemented to titanium abutments, (2) In-Ceram crowns cemented to titanium abutments, (3) Celay feldspathic crowns cemented to titanium abutments, (4) In-Ceram crowns cemented to milled ceramic abutments, and (5) Celay feldspathic crowns cemented to milled ceramic abutments. The specimens were loaded at 0- and 45-degree angles to the long axis, and the load values at the moment of failure were recorded using a universal testing machine. RESULTS: The fracture strengths under vertical loading were greater than those under oblique loading. The fracture strengths of metal-ceramic crowns cemented to the titanium abutments were higher than those of all-ceramic crowns cemented on the milled ceramic abutments, regardless of loading direction. There were no differences in the fracture strengths of the ceramic crowns between the two different abutment types under oblique loading. CONCLUSION: All-ceramic crowns on the milled ceramic abutments were weaker than the metal-ceramic crowns on the titanium abutments under oblique loading.