A late diagnosis of alkaptonuria in an elderly patient

Pigmented transverse nasal band: A review

Pigmented transverse nasal band/groove is an asymptomatic benign condition, characterized by the development of erythematous to hyperpigmented, well-demarcated, transverse groove at the junction of middle and lower two-third of the nasal dorsum. Although the pathogenesis is unclear, embryologic origin seems to be the most plausible hypothesis. This condition is often associated other related dermatological conditions such as milia, comedones, seborrheic dermatitis and atopic dermatitis. Diagnosis is mostly clinical, while reassurance is the mainstay of therapy. In persistent cases, topical retinoids have been used. In this article, we have reviewed the different aspects of this condition including treatment, along with the recent updates to create awareness about this dermatological entity.

LC-MS/MS study of the degradation processes of nitisinone and its by-products

Nitisinone (2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione, NTBC) was the first synthetically produced triketone herbicide. However, its unsatisfactory herbicidal properties, negative impact on the natural environment and the high cost of synthesis have hindered its commercialization as a plant protection agent. Nevertheless, NTBC has become the medical treatment of choice for a rare hereditary metabolic disease -hepatorenal tyrosinemia. Literature review shows that most research on nitisinone focuses on its medical applications, while there are neither in-depth studies of its stability nor its degradation pathways. Therefore, the aim of our study was to employ liquid chromatography coupled with mass spectrometry (LC-MS/MS) to determine the stability of NTBC in different experimental conditions (pH of solution, temperature, time of incubation, ultraviolet radiation), identify its degradation products and determine the stability of the latter. Electrospray ionization (ESI) in the negative ion mode was used as an ionization method and the analytes were detected by multiple reaction monitoring. We show that nitisinone stability increases with increasing pH of the solution. At pH similar to that of gastric juice in the human stomach, two major products of NTBC degradation are formed: 2-amino-4-(trifluoromethyl)benzoic acid (ATFA) and 2-nitro-4-(trifluoromethyl)benzoic acid (NTFA), which show considerable stability under studied conditions. The results of these studies shed new light on the properties of NTBC, therefore contributing to better understanding of possible risks and benefits of its medical application.