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Tiopronin
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Tiopronin is an acylated sulfhydryl-containing derivative of glycine with reducing and complexing properties. It breaks the disulfide bond of cystine (an oxidized dimeric form of cysteine) and binds the sulfhydryl group of the resultant cysteine monomers to form a soluble tiopronin-cysteine-mixed disulfide, which is more water-soluble than cystine and is readily excreted. This leads to a reduction in urinary cystine concentration and subsequently reduces cystine stone formation. Tiopronin is indicated as a second-line for the prevention of kidney stone formation in patients with severe homozygous cystinuria. This drug may also be used as a mucolytic drug and to bind metal nanoparticles in Wilson’s disease, which is an overload of copper in the body (1,2).
Urolithiasis
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Thomas Johnston, James Armitage, Oliver Wiseman
Cystinuria like most inborn errors of metabolism is inherited in an autosomal recessive pattern with the gene defect located on Chromosome 2. It has been classified into three types (I, II and III) according to the specific gene mutation although this differentiation is of little clinical relevance. The incidence of heterozygous cystinuria is about 1 in 20,000 and these individuals are at high risk of recurrent cystine urolithiasis. Patients with cystinuria have defective absorption in the jejunum of cystine, and the other dibasic amino acids ornithine, lysine and arginine. The reabsorption of these amino acids in the proximal convoluted tubule of the kidney is also abnormal leading to high levels in the urine. Cystine, in contrast to ornithine, lysine and arginine, is relatively insoluble at physiological urine pH and has a pKa of 8.3. At pH < 7.0 the solubility of cystine is approximately 250 mg/L but at pH > 7.5 its solubility increases considerably to more than 500 mg/L [12]. Patients with heterozygous cystinuria excrete <200 mg/day and usually do not form stones whereas cystine excretion in homozygous cystinurics is typically 600–1400 mg/day.
The urinary tract and male reproductive system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Luis Beltran, Daniel M. Berney
The main types of urinary calculi are as follows: Calcium-containing stones, the calcium salt being predominantly oxalate with lesser amounts of calcium phosphate. These comprise more than 75% of all urinary calculi and are characteristically laid down in an acid urine.Complex triple phosphate stones including magnesium, ammonium, carbonate, and calcium components. These comprise 15% of urinary calculi and are laid down in alkaline urine. They may form an outer laminated deposit on other stones and are strongly associated with urinary tract infection.Uric acid and urate–uric acid stones comprise 5% of urinary calculi but affect up to 20% of patients with gout. Similar to calcium-containing stones they are typically laid down in an acid urine. Pure uric acid stones are radiolucent, rendering their detection on a plain abdominal radiograph virtually impossible.Cystine stones occur in primary cystinuria, a rare but important renal disease in childhood.
Increased plasma glutamate in non-smokers with vasospastic angina pectoris is associated with plasma cystine and antioxidant capacity
Published in Scandinavian Cardiovascular Journal, 2022
Minako Oda, Kousuke Fujibayashi, Minoru Wakasa, Shintaro Takano, Wataru Fujita, Michihiko Kitayama, Hiroaki Nakanishi, Kazuyuki Saito, Yasuyuki Kawai, Kouji Kajinami
In addition to oxidative stress, decreased antioxidant capacity may be responsible for endothelial dysfunction. Glutathione is an important antioxidant that attenuates coronary vasospasm in patients with vasospastic angina pectoris (VSAP) [11] and reverses endothelial dysfunction in patients with atherosclerosis [12]. The synthesis of glutathione depends on the availability of the amino acid precursors, glutamate, glycine and cysteine [13]. Cystine is an oxidative form comprising two cysteines that are taken up by a specific cystine/glutamate antiporter system (XC–) in association with glutamate export. Extracellular glutamate competitively inhibits cystine import into endothelial cells [14–16]. Therefore, extracellular glutamate and cystine concentrations are crucial for glutathione biosynthesis.
Safety profile of D-penicillamine: a comprehensive pharmacovigilance analysis by FDA adverse event reporting system
Published in Expert Opinion on Drug Safety, 2021
Vijay Kumar, Anand Prakash Singh, Nicholas Wheeler, Cristi L. Galindo, Jong-Joo Kim
D-pen is also used to treat cystinuria, an inherited autosomal recessive disease caused by mutations in SLC3A1 and SLC7A9 genes. These mutations manifest high concentrations of the amino acid cystine in the urine, which enhances the formation of cystine stones in the kidneys, ureter, and bladder [20,21]. Cystinuria patients cannot properly reabsorb cystine into their bloodstream, leading to the accumulation of cystine in their urine. The excess cystine forms crystals and becomes stones that can create blockages in the urinary tract and provide sites for bacterial infections [20,21]. D-pen is used to reduce urine levels of cystine. D-pen combines and forms disulfide bonds with cysteine, resulting in the formation of a D-pen-cysteine disulfide compound that is more soluble than cystine and thereby facilitates the excretion in urine [22,23].
Novel plasma metabolite markers of attention-deficit/hyperactivity disorder identified using high-performance chemical isotope labelling-based liquid chromatography-mass spectrometry
Published in The World Journal of Biological Psychiatry, 2021
Liang-Jen Wang, Wen-Jiun Chou, Ching-Shu Tsai, Min-Jing Lee, Sheng-Yu Lee, Chia-Wei Hsu, Pei-Chun Hsueh, Chih-Ching Wu
5-hydroxylysine is a hydroxylated derivative of the amino acid lysine that is present in certain collagens. Patients with glutaric aciduria type 1, an inborn error of hydroxylysine, have been found to exhibit neuroaxonal damage, demyelination, and astrocytosis in the right frontal white matter and right lentiform nuclei (Kurul et al. 2004; Radha Rama Devi et al. 2016). L-cystine is the L-enantiomer of the sulfur-containing amino acid cystine. Glutamate exported by system x(c) is largely responsible for the extracellular glutamate concentration in the brain, while imported cystine is required to synthesise the major endogenous antioxidant. L-cystine may serve as a neuroprotective protein and signalling pathway (Albrecht et al. 2010). The results of this study showed that L-cystine was strongly and positively correlated with ADHD symptoms, which suggests that patients suffering from more severe ADHD symptoms may need more L-cystine to compensate for neurodevelopment.