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Ultraviolet and Light Absorption Spectrometry
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Zoltan M. Dinya, Ferenc J. Sztaricskai
Although cephalosporins show characteristic UV absorption, the ultraviolet and visible spectrophotometric analysis of this group of antibiotics has not been wide spread. The official prescriptions [13—16] utilize the hydroxylamine method in the case of cefazolin sodium, cephacetrile sodium, cephapirin sodium, cephradine, cephalexin, and cefoxitin sodium. According to the results reported so far, it can be concluded that many of the spectrophotometric assay procedures introduced for penicillins cannot be used for cephalosporins. This is so because the chemical reactions characteristic of penicillins proceed generally less readily (or do not proceed at all) with cephalosporins, due to the greater stability of the cephem skeleton.
Reactivities of Amino Acids and Proteins with Iodine
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
Stearylcoenzyme A desaturase, a microsomal enzyme, catalyzes the formation of mon- ounsaturated fatty acids in the liver, and it contains 24 tyrosyl residues. Nitration (tetrani- tromethane) of one to two residues decreases the enzymic activity by 83%. Complete inactivation is observed after nitrating two to five residues, or acetylating (acetic anhydride) four. The effect is not reversed by hydroxylamine. Both types of modification cause a loss of the iron prosthetic group from the protein.354
Leprosy: Therapy-related emergencies
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
DDS gets metabolized by either N-acetylation or N-hydroxylation. The N-acetylation pathway has no role in any of the adverse effects. Hydroxylamine, which is a toxic intermediate metabolite formed by the N-hydroxylation pathway, is responsible for hemolytic anemia, methemoglobinemia, and DHS [7,19]. An association between HLA-B*13:01 and DHS, which has overlapping clinical features with DRESS, has been found in a genome-wide Chinese study [20].
Dapsone-induced methemoglobinemia and hemolysis in a woman without G6PD deficiency presenting with idiopathic urticaria
Published in Hematology, 2022
Yang Hu, Mimansa Geere, Maham Awan, Andrew D. Leavitt, Laura E. Brown, Hadley J. Pearson, Jocelyn S. Gandelman, Scott C. Kogan
The ‘bite cell’ is an aberrant feature of mature red blood cells seen on peripheral smear characterized by removal of one or more portions of the biconcave disc rim of red blood cells by splenic macrophages at sites where hemoglobin has been abnormally deposited [1]. Occasionally, ‘blister cells’, which have a large vacuole along the periphery, may also form alongside ‘bite cells.’ Oxidative injury of red blood cells can result in hemoglobin sulfhydryl group oxidation, which can precipitate the formation of these abnormal red blood cell features. They are most commonly associated with hemolysis and methemoglobinemia in patients with G6PD deficiency exposed to triggers such as medications including dapsone [14,15]. Dapsone is a sulfone antibiotic used as first line therapy for leprosy and second line therapy for Pneumocystis pneumonia [16]. It can also be used as a second line therapy for chronic spontaneous urticaria [2,17]. Dapsone is converted to the metabolite hydroxylamine, which can accumulate in red blood cells and generate free radicals that deplete glutathione stores, leading to oxidative damage of the red blood cell membrane [18]. G6PD is a key enzyme that participates in restoring glutathione. In the rare case of dapsone overdose, hydroxylamine can accumulate to excess levels to overwhelm the protective effect of glutathione and cause oxidative damage to red blood cells even in the presence of normal G6PD levels [11].
N-acetyltransferase: the practical consequences of polymorphic activity in man
Published in Xenobiotica, 2020
Investigation has shown that 2-amino-3-methylimidazol[4,5-f]quinoline (IQ), a carcinogenic heterocyclic amine formed during the cooking of meat and fish as a condensation product of creatine and creatinine with amino acids and proteins (Skog et al., 1998) is not a good substrate for N-acetylation. Nevertheless, following structural alteration by oxidation via cytochrome P4501A2 or prostaglandin H synthase 2 (Liu & Levy, 1998) the hydroxylamine produced is rapidly O-acetylated producing a more reactive acetoxyheterocyclic amine that is capable of forming adducts with nucleic acids (Probst et al., 1992; Vatis & Weber, 1997). A similar situation occurs with a related compound known as PhIP (2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine), another heterocyclic amine produced in cooked meats. Following N-oxidation by cytochrome P4501A2, further metabolism by O-acetylation may increase its potency and mutagenic potential (Felton et al., 1997; Frandsen & Alexander, 2000; Sadrieh et al., 1996; Wild et al., 1995)
Hypoxic targeting and activating TH-302 loaded transcatheter arterial embolization microsphere
Published in Drug Delivery, 2020
Pengkai Ma, Jianhua Chen, Haixian Qu, Ye Li, Xiaohui Li, Xuemei Tang, Zhigang Song, Hainan Xin, Jinbang Zhang, Jingxue Nai, Zhiping Li, Zhijun Wang
TH-302 was purchased from Abmole Bioscience Inc (Shanghai, China). PLGA polymers were purchased from Jinan Daigang Biomaterial Co., Ltd (Jinan, Shandong Province, China). PVA-124, methanol, methylene chloride, Tween 20/80, and other chemical reagents were obtained from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Dulbecco’s modified Eagle’s medium (DMEM), 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), and fetal bovine serum (FBS) were purchased from Gibco Life Technology Company (Grand Island, NY). Microguide wire (MAK501N) was purchased from Merit Medical System Inc (South Jordan, UT). Micro-catheter (STD130-22S) was purchased from ASAHI INTECC Co., Ltd. (Tokyo, Japan). A venous indwelling needle (18G) was purchased from B. Braun Medical Inc. (Melsungen, Germany). The contrast agent Ultravist was purchased from Bayer HealthCare Co., Ltd. (Leverkusen, Germany). Hydroxylamine hydrochloride and ketamine hydrochloride were provided by the experimental animal center of the Chinese PLA General Hospital.