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Futuristic Approaches in Vitreoretinal Surgery
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
The Lipschitz macular implant [LMI] is based on the Cassegrain telescopic system. It uses small mirrors in such a manner that the reflected image gets magnified 2.5 times on the retina. It is similar to a conventional IOL in its dimensions, 13 mm in overall diameter with 6.5-mm optic. It is implanted into the capsular bag through a 6.5-mm incision. Within the optic, there are two mirrors [1–2 mm in thickness], anterior [measuring 1.4 mm] and posterior [measuring 2.8 mm]. There is a 1.4-mm central opening in the posterior mirror. The mirrors are coated on their reflecting surface with titanium oxide and silicone dioxide. To improve biocompatibility, the entire lens is coated with poly-paraxylene. The outer zone of the optic allows normal peripheral vision. The newer LMI-SI is a non-foldable IOL that needs to be placed over a regular IOL implanted into the capsular bag.
Oxime Research
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
The chain linking two quaternary nitrogens in bispyridinium oximes exerts a great effect on the reactivating efficacy, although this part of the oxime does not play any role in the dephosphylation process. It is a major factor in influencing oxime access to the active site of AChE and its reactivation rates. The length of the linker between both pyridinium rings (for bisquaternary pyridinium reactivators) plays an important role in its potency to reactivate nerve agent–inhibited AChE (Kuca et al., 2003c; Pang et al., 2003). There is relationship between the length of the n-methylene linkage chain and the type of nerve agent used for inhibition. The optimal length of the reactivator’s linker for satisfactory potency to reactivate tabun, sarin, or VX-inhibited AChE is three or four methylenes. On the other hand, one methylene group seems to be the most potent for the reactivation of cyclosarin-inhibited AChE. Unfortunately, this rule is satisfied only in the case of n-methylene linkage chains and oxime groups in position four at the pyridinium ring. Compounds with oxygen, sulfur, or other structural fragments differing from the methylene that are incorporated into the linker and compounds with different positions of oxime groups do not fulfill this rule (Acharya et al., 2009b; Musilek et al., 2005, 2006b; Oh et al., 2006; Pang et al., 2003). These differences could be caused by the presence of the free electrons in the linker and subsequent interactions of this part of the reactivator’s molecule with the inside of the enzyme cavity. An important structural factor influencing the reactivation process could also be the “rigidity” of the linking chain. Due to the rigidity of the linker, the spatial orientation of the pyridinium rings in the enzyme cavity is limited. Compounds with a certain level of rigidity of the linker were synthesized with the aim of elucidating the influence of rigidity on reactivation potency. Z- and E-but-2-ene and ortho-, meta-, and para-xylene moieties were inserted into the linkage chain (Musilek et al., 2005, 2006b, 2007b).
A Comparative Study of the Kinetics and Bioavailability of Pure and Soil-Adsorbed Benzene, Toluene, and M-Xylene after Dermal Exposure
Published in Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach, Health Risk Assessment, 2017
Mohamed S. Abdel-Rahman, Gloria A. Skowronski, Rita M. Turkall
Several dermal bioavailability studies have been performed on 2,3,7,8-tetrachlorodi-benzo-p-dioxin (TCDD), a compound persistent in soil.6-8 Less attention has been given to dermal bioavailability determinations of volatile pollutants in soil. Benzene together with toluene and xylene are among the most prevalent volatile contaminants identifed at dumpsites as well as being the major aromatic components of gasoline.9,10 Benzene is used both as a solvent and as a starting material in chemical synthesis.11,12 Because of its leukemia- and cancer-causing properties,13,14 benzene is often considered to be more hazardous to health than toluene or xylene. Toluene is employed as a solvent for paints, plastics, varnishes, and resins, and in the manufacture of explosives, drugs, perfumes, and other synthetic chemicals.15 Although toluene lacks benzene’s chronic hematopoietic effects, animal experiments indicate that toluene is more acutely toxic than benzene. High concentrations of inhaled toluene cause symptoms of central nervous system (CNS) depression such as headache, dizziness, weakness, and loss of coordination. Furthermore, chronic exposure to toluene may cause permanent CNS damage.11,15,16 Commercial xylene is a mixture of three isomers, ortho-, meta-, and para-xylene, with m-xylene predominating (usually 60 to 70%).17 Xylene is extensively used as a solvent, a cleaning agent, a degreaser, and a starting material and intermediate in the chemical industry. Xylene is also present in a broad range of consumer products such as aerosols, paints, varnishes, shellacs, and rust preventatives.17 Gerarde reported that xylene may be more acutely toxic than benzene or toluene.18 When inhaled at high concentrations, symptoms included disturbed vision, dizziness, tremors, salivation, cardiac stress, CNS depression, confusion, and coma.19 Xylene causes dehydration and defatting of the skin which may lead to erythema, blistering, or dermatitis.18
Examination of xylene exposure in the U.S. Population through biomonitoring: NHANES 2005–2006, 2011–2016
Published in Biomarkers, 2021
Víctor R. De Jesús, Daniel F. Milan, Young M. Yoo, Luyu Zhang, Wanzhe Zhu, Deepak Bhandari, Kevin S. Murnane, Benjamin C. Blount
Xylenes are aromatic hydrocarbons commonly used for industrial applications due to their superior solvent properties (Angerer and Lehnert, 1979, Mohammadyan and Baharfar 2015). They are synthetically derived from crude oil or coal tar and used in various commercial products such as petrochemicals, plastics, and paints. Additionally, other xylene sources in the environment include landfill gases, emissions from petroleum refineries, vehicle exhaust fumes, and tobacco smoke (Chambers et al.2011, Niaz et al.2015, Staszewska et al.2012, Saliba et al.2017). Xylene exists as three different positional isomers: ortho-, meta-, and para-xylene (o-xylene, m-xylene, and p-xylene). Throughout this report, the term xylene refers to a mixture of the three positional isomers unless otherwise stated.
Modification of sodium aescinate into a safer, more stable and effective water-soluble drug by liposome-encapsulation: an in vitro and in vivo study
Published in Drug Delivery, 2022
Sifan Huang, Xinyu Wang, Mengmeng Liu, Zhizhe Lin, Wenqian Gu, Haili Zhao, Yanqiu Zhang, Baoyue Ding, Jiyong Liu, Xin Wu, Wei Fan, Jianming Chen
Mouse ear swelling models are sensitive to steroidal anti-inflammatory drugs (SAIDs) and less sensitive to NSAIDs. SA-Lip-I (1.8, 3.6 and 7.2 mg/kg) demonstrated a dose-dependent inhibition on paraxylene-induced ear swelling in mice (Figure 3(A)). The inhibition rate of the low-dose (1.8 mg/Kg) SA-Lip group has comparable therapeutic effects with the SA-I group, above all that of the middle-dose (3.6 mg/kg) and high-dose (7.2 mg/kg) group was significantly higher and significantly different from the SA-I group (p < .05).