Methods for Casting Airways
Joan Gil in Models of Lung Disease, 2020
Although the ancients knew that the lung contains a system of branching airways, it was not until late last century that a detailed study of the bronchial tree was made by Aeby (1880). He used metal casts to demonstrate the pattern of branching in the lungs of various animals. The next advance in the technique of casting was made by Schummer (1935), who introduced methyl methacrylate. This was followed the next year with the use of vinyl compounds by Narat et al. (1936). Latex has been used extensively for vascular injection studies, notably by Lieb (1940), because of its property of flexibility. Pump (1964) adapted this technique for airway casting, using moulage, another latex. The use of polyester resins for making lung casts was reported by Scales (1950), and the technique was perfected by Tompsett (1970). These resins make excellent rigid casts. Frank and Yoder (1966) introduced silicone rubber as a casting medium; its use was developed by Phalen et al. (1973) for making airway casts in situ. It is a very satisfactory material for making flexible casts that hold their shape better than latex.
Structure, Photochemistry, and Organic Chemistry of Bilirubin*
Karel P. M. Heirwegh, Stanley B. Brown in Bilirubin, 1982
The structure of bilirubin-IXα was proved conclusively by total synthesis and reported in 1942 by Fischer and Plieninger.23 The presence of vinyl groups and the nonsymmetrical ordering of the side chains (pyrrole β-substituents) made the synthesis difficult and tedious. In its time, it represented one of the monumental accomplishments of natural products total synthesis and is outlined in Figures 12 to 15. Bilirubin was obtained by bisulfite reduction of biliverdin, a reduction which is commonly carried out today by use of sodium borohydride.1.24 One of the key synthetic steps involved coupling two different oxodipyrromethene “halves” to afford a biliverdinoid tetrapyrrole. This solved the problem of making an unsymmetrical tetrapyrrole because in the acid-catalyzed coupling shown in Figure 12, the oxodipyrromethene aldehyde must react with an “unsubstituted” oxodipyrromethene half and, under the reaction conditions employed, neither oxodipyrromethene can react with itself (and lead to a symmetrically substituted tetrapyrrole). In this procedure, the two oxodipyrromethene “halves” can (with the proper ordering of their pyrrole β-substituents) provide the desired unsymmetrical ordering of β-substituents in the final tetrapyrrole. The other key step overcame difficulties associated with the preparation of material with (reactive) vinyl substituents by masking the incipient vinyl group as a urethane derivative. The urethane group was hydrolyzed in due course to an amine which was permethylated and eliminated under Hoffmann conditions as described in Figure 12.
Herbal Extracts and Their Bioactivities: Comparative Phytoconstituent Analysis of Selected Medicinal Plants Using GC-MS/FTIR Techniques
Megh R. Goyal, Hafiz Ansar Rasul Suleria, Ramasamy Harikrishnan in The Role of Phytoconstitutents in Health Care, 2020
The outcome of the FT-IR spectral analysis of A. conyzoides showed the following functional groups (Table 2.7): Alcohols;Aliphatic amines;Alkanes, aromatic organophosphorus compounds;Arenes;Aromatic nitro compounds;Aromatics;Bonded phosphorus oxide;Bromoalkanes;Disulfides;Meta-substituted benzenes;Phenols;Saturated aldehydes;Terminal alkynes;Tri-substituted alkenes;Vinyl group.
Elucidation of the cytogenotoxic potential of vigabatrin and its in silico computer-assisted DNA interaction
Published in Drug and Chemical Toxicology, 2023
İbrahim Halil Kenger, Hamit Yıldız, Mehmet Tahir Hüsunet, Lale DÖNbak, Ahmet Kayraldız
Epilepsy is one of the most common chronic neurological diseases worldwide (Falco-Walter 2020). According to data from the World Health Organization (WHO), it is known to affect more than 50 million people worldwide (WHO 2019). Epilepsy is a recurrent, spontaneous seizure state that occurs when the balance between inhibition and excitation resulting from abnormal discharge of nerve cells is disturbed (Scharfman 2007). The aim of epilepsy treatment is to keep it under control seizures epilepsy. For this; Multiple treatments are available, including medications, implantable devices, and surgery. However, the most effective of these are antiepileptic drugs (AED). Epileptic seizures are controlled in approximately 70% of children treated with these drugs (AEDs) (Sankaraneni and Lachhwani 2015). One of the drugs commonly used in AEDs is vigabatrin (VGB), belongs to the new class of anti-epileptic drugs and is also used in the treatment of infantile spasms (IS). VGB is a GABA-ergic antiepileptic drug and is one of 2 approved drugs available to treat IS (Jastrzembski et al.2020). Gamma-aminobutyric acid transaminase (GABA-T) is an enzyme that breaks down GABA (Gamma-aminobutyric acid), and VGB is an irreversible inhibitor of GABA-T. It is structurally identical to the vinyl group GABA. VGB acts as a substrate for GABA-T, which releases GABA at the synaptic cleft (Patsalos et al.2018, Sills and Rogawski 2020).
Novel 3-chloro-6-nitro-1H-indazole derivatives as promising antileishmanial candidates: synthesis, biological activity, and molecular modelling studies
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Mohamed Mokhtar Mohamed Abdelahi, Youness El Bakri, Chin-Hung Lai, Karthikeyan Subramani, El Hassane Anouar, Sajjad Ahmad, Mohammed Benchidmi, Joel T. Mague, Jelena Popović-Djordjević, Souraya Goumri-Said
The structures of compounds isolated have been identified by 1H NMR and 13 C NMR spectral data. The 1H NMR spectrum (DMSO-d6) of 2 shows an allylic proton signal at 5.23 ppm and a multiplet centred at 6.04 (6.14, 6.03, and 6.01) ppm attributable to vinyl protons CH = CH2. The 13 C NMR spectra of 2 show the presence of a characteristic signal of the allyl group at 133.92 and one at 115.45 ppm corresponding to the vinylic CH and the methylene vinyl group. Two signals correlating to the methylene group adjacent to the nitrogen atoms appear at 51.63 ppm.
Preparation and use of nanogels as carriers of drugs
Published in Drug Delivery, 2021
Cuixia Li, Sreekanth Reddy Obireddy, Wing-Fu Lai
The precipitation/crosslinking method is to have water-soluble polymers being precipitated out of a homogeneous aqueous solution to form nanoparticles. After that, crosslinking reactions are performed to make the polymers in the particles crosslinked to generate nanogels. Xia et al. (2003) prepared nanogels in a salt solution without using an emulsifier. The size and size distribution of the nanogels are closely related to the salt concentration and the reaction temperature. The LCST of the aqueous solution of the polymer decreased with the increase of the NaCl concentration. Then, crosslinking reactions are performed. Unfortunately, the functioning of the crosslinking agent used to prepare the nanogels requires the availability of a strongly alkaline medium, which in general is not available during the drug loading process. For this, Cai et al. (2003) first modified the molecular chain of the polymer so that its side chain was either connected to the vinyl group through the degradable ester linkage or directly connected to the acrylate group. Then the free radical polymerization reaction was initiated by heating the polymer solution above the LCST. Recently, Shen et al. (2007) prepared pH-responsive nanogels with the particle size of 70-80 nm by adding an ethylenediamine diacetic acid diacetaldehyde (EDTAA) crosslinking agent into an aqueous solution of chitosan. The nanogel has a positive charge when pH <4.8, and a negative charge when pH > 5.2. The change of pH of the surrounding medium can make the surface charge of the nanogel reverse. Nanogels can also be formed through electrostatic interactions if some polyelectrolytes with specific structures are added into an aqueous solution of chitosan (Ethirajan et al., 2008). The concentration of water-soluble polymers used to prepare nanogels by using this method should not be too high; otherwise, large gels are easily formed. The efficiency of this preparation method is, therefore, relatively low.
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