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Composite Materials for Oral and Craniofacial Repair or Regeneration
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Teresa Russo, Roberto De Santis, Antonio Gloria
Poly-Methyl-Methacrylate (PMMA) is the polymer most widely used for cranioplasty. Its history is longer than half a century and in some instance it showed better long-term outcomes compared to frozen autologous bone (Moreira-Gonzalez et al. 2003; Piitulainen et al. 2015). PMMA can be adopted according to all the four approaches listed earlier. For the in situ forming approach, PMMA is provided to surgeons in the form of a solid powder phase made of PMMA and/or copolymers and a liquid monomer component. By mixing the powder and liquid phases the paste is applied in vivo and a radical polymerization reaction occurs driven by benzoyl-peroxide and amines (i.e., activators/co-initiators for the formation of radicals) contained in the powder and liquid phase, respectively (Harris et al. 2014; De Santis et al. 2003). Once polymerized, mechanical properties (Table 7.1) of PMMA are in between those of the spongy and cortical bone (McElhaney et al. 1970; Ronca et al. 2014). Heat developed during the exothermic reaction of PMMA limits the direct intra-operative use of this bone cement, especially if large cranial defects need to be restored. However, PMMA can be easily processed through the moulding strategies (van Putten et al. 1992; Cheng et al. 2018; Maricevich et al. 2019). The main advancement of PMMA relies on modifications of the acrylic cement to improving biological and mechanical functions. The loading of antibiotics (i.e., gentamicin) is suggested to prevent infection (Minelli et al. 2011; Worm et al. 2016). However, a slight reduction of mechanical properties for gentamicin loaded PMMA has been observed (De Santis et al. 2003). The realization of PMMA based nano-composites has been suggested for antimicrobial purposes by incorporating silver (Oei et al. 2012) and gold (Russo et al. 2017) nanoparticles into the polymeric matrix. The integration of phase-change particles has been suggested to reduce temperature levels during polymerization (De Santis et al. 2006). Several PMMA based composites for cranioplasty have been advised for improving osteoconductivity and biocompatibility. Hydroxyapatite (Itokawa et al. 2007; Zebarjad et al. 2011) and bioactive glass (Peltola et al. 2012) represent the most common type of particles functionalizing and reinforcing the acrylic matrix (Table 7.1). Medical-grade PMMA filaments represent the future trends in cranioplasty through AM (Espalin et al. 2010), and gentamicin doped filaments have also been investigated (Mills et al. 2018).
Antioxidant, antibacterial and insecticidal activities of cypress (Cupressus sempervirens L.) essential oil
Published in International Journal of Environmental Health Research, 2023
Jazia Sriti, Mahjouba Haj Salem, Wissem Aidi Wannes, Olfa Bachrouch, Houda Mejri, Souhir Belloumi, Nadia Fares, Slim Jallouli, Soumaya Haoual-Hamdi, Jouda Mediouni-Ben Jemâa, Ferid Limam
The antibacterial activity of cypress EO was tested against nine strains. Only three bacterial strains showed a susceptibility of different oils. Akermi et al. (2022) mentioned that the antibacterial activity of gentamicin was higher against Gram-negative bacteria than Gram-positive with an IZ = 25 mm and an MIC = 2.5 μg/mL against Gram-negative (S. enterica and E. coli), and an IZ = 20 mm and an MIC of 12.5 μg/mL against Gram-positive (S. aureus and L. monocytogenes). Gentamicin is an aminoglycoside bactericidal and is a broad-spectrum antibiotic active against a wide range of bacterial infections; mostly Gram-negative bacteria (O’Sullivan et al. 2020). According to Khubeiz et al. (2016), the antibacterial activity of cypress essential oils was more pronounced against Gram-positive than Gram-negative bacteria. The higher resistance among Gram-negative bacteria could be ascribed to the presence of their outer phospholipidic membrane, almost impermeable to lipophilic compounds (Selim et al. 2013). The hydrophobic nature of terpenoids is related to their attraction to cell membranes and cell walls (Jaroque et al. 2019). The antibacterial activity of cypress essential oil could be mainly due to its major constituents such as α- pinene, δ-3-carene and cedrol that have been reported to display antimicrobial effects (Argui et al. 2021).
Ocimum gratissimum (Linn) leaves extract attenuates oxidative stress and liver injury in gentamicin-induced hepatotoxicity in rats
Published in Egyptian Journal of Basic and Applied Sciences, 2021
Oluwadare J. Ogundipe, Omolola F. Akinpelu, Abiodun. Oyerinde, Oyelade R. Oluwakemi
Gentamicin (GEN) belongs to the family of antibiotics that are widely used in the treatment of serious and life-threatening gram-negative bacterial infection. Its adverse effect on some vital organs in the body, such as kidney, liver, etc., makes its use limited in clinical settings [1]. The main side effects include liver damage, which is one of the major factors of liver inefficiency in a significant number of people taking this medication [2,3]. Increased production of Reactive Oxygen Species (ROS), which can be seen after the use of gentamicin in cells, is effective in inducing toxic impacts of this drug on the structure and function of tissues [4–6].
Identification of microbes from textile dye wastewater and its antibiotic resistance from local textile factory
Published in Bioremediation Journal, 2023
Nur Hanis Mohamad Hanapi, Hadieh Monajemi, Azimah Ismail, Zarizal Suhaili, Hafizan Juahir
Streptomycin, an antibiotic that has similar characteristics with streptothricin, derived from Streptomyces and shown to have same activity as streptothricin, to against E.coli, B. subtilis, A. aerogenes, and P. vulgaris while less active to against S. aureus and few certain strains of Salmonella, and showed much more activity toward B. mycoides, B.cereus, Mycobacterium phlei, Serratia marcescens, Ps. aeruginosa, Ps. Fluorescens, and Cl. Butylicum. It possesses strong bactericidal properties, soluble in water and has selective activities against gram-positive and gram-negative bacteria (Schatz et al. 2005). Rifampicin, an antibiotic has been reported to be effective against tuberculosis which is caused by Mycobacterium tuberculosis (Hughes and Brandis 2013; Grumbach, Canetti, and Le Lirzin 1969; Maggi et al. 1966). Rand, Houck, and Silverman (2007) stated in the study of the mechanism of rifampicin that rifampicin acts by entering the cell cytoplasm, and inhibiting the transcription process by binding to RNA polymerase (rpoβ). The act of resistance to rifampicin is usually because of the substitutions of amino acid clusters in the three known resistance clusters in the rifampicin-binding site of rpoβ (Campbell et al. 2001). Luna et al. (2007) in their study reported that a few species of Bacillus; B. anthracis, B. thuringiensis, B. cereus, B. mycoides and B. pseudomycoides showed a susceptible activity toward rifampicin. The last antibiotic used in the study is gentamicin. Gentamicin as reported by Jao and Jackson (1964) is isolated from culture filtrates from species of Micromonospora, a bacterium and has shown the clinical efficacy toward Pseudomonas and Proteus organisms of gram-negative bacilli which inhibition process were active and as well as to staphylococci, Aerobacter and coliform bacteria. Gentamicin inhibits the activity of bacteria by interrupting the protein synthesis through irreversible binding of 30S of subunit of bacteria ribosome. Kauffman et al. (1978) reported that gentamicin-resistant includes gram-negative bacilli such as Pseudomonas and Klebsiella though no gram-positive bacilli were mentioned. However, based on the results obtained, it can be deduced that all the isolates (C1, C3K and C3W) showed an intermediate response toward gentamicin.