Dibasic Amino Acids Ornithine Research Articles

Cystinuria in Dogs and Cats: What Do We Know after Almost 200 Years?

Simple SummaryCystinuria, as an inborn error of metabolism, is a problem with worldwide distribution and has been reported in various canine and feline breeds. Transepithelial transport of cystine is mediated by COLA transporter and the mutation in genes coding this transporter may cause cystinuria. Urolithiasis associated with typical clinical signs may be the clinical consequence of cystinuria. The mutation causing cystinuria and the mode of inheritance have been determined only in several canine breeds. This makes cystinuria difficult to control and gradually decreases its prevalence. In cats, cystinuria occurs only rarely.The purpose of this review is to summarize current knowledge on canine and feline cystinuria from available scientific reports. Cystinuria is an inherited metabolic defect characterized by abnormal intestinal and renal amino acid transport in which cystine and the dibasic amino acids ornithine, lysine, and arginine are involved (COLA). At a normal urine pH, ornithine, lysine, and arginine are soluble, but cysteine forms a dimer, cystine, which is relatively insoluble, resulting in crystal precipitation. Mutations in genes coding COLA transporter and the mode of inheritance were identified only in some canine breeds. Cystinuric dogs may form uroliths (mostly in lower urinary tract) which are associated with typical clinical symptoms. The prevalence of cystine urolithiasis is much higher in European countries (up to 14% according to the recent reports) when compared to North America (United States and Canada) where it is approximately 1–3%. Cystinuria may be diagnosed by the detection of cystine urolithiasis, cystine crystalluria, assessment of amino aciduria, or using genetic tests. The management of cystinuria is aimed at urolith removal or dissolution which may be reached by dietary changes or medical treatment. In dogs with androgen-dependent cystinuria, castration will help. In cats, cystinuria occurs less frequently in comparison with dogs.

In silico analysis of SLC3A1 and SLC7A9 mutations in Iranian patients with Cystinuria.

Cystinuria is an autosomal recessive defect in reabsorptive transport of cystine and the dibasic amino acids ornithine, arginine, and lysine from renal tubule and small intestine. Mutations in two genes: SLC3A1, encoding the heavy chain rbAT of the renal cystine transport system and SLC7A9, the gene of its light chain b0, + AT have a crucial role in the diseases. In our previous studies from Iranian populations with Cystinuria totally six and eleven novel mutations respectively identified in SLC3A1 and SLC7A9 genes. In this study, we conducted an in silico functional analysis to explore the possible association between these genetic mutations and Cystinuria. MutationTaster, PolyPhen-2, PANTHER, FATHMM. PhDSNP and MutPred was applied to predict the degree of pathogenicity for the missense mutations. Furthermore, Residue Interaction Network (RIN) and Intron variant analyses was performed using Cytoscape and Human Slicing Finder softwares. These genetic variants can provide a better understanding of genotype-phenotype relationships in patients with Cystinuria. In the future, the findings may also facilitate the development of new molecular diagnostic markers for the diseases.

Metabolomics Reveals Amino Acids Contribute to Variation in Response to Simvastatin Treatment

Statins are widely prescribed for reducing LDL-cholesterol (C) and risk for cardiovascular disease (CVD), but there is considerable variation in therapeutic response. We used a gas chromatography-time-of-flight mass-spectrometry-based metabolomics platform to evaluate global effects of simvastatin on intermediary metabolism. Analyses were conducted in 148 participants in the Cholesterol and Pharmacogenetics study who were profiled pre and six weeks post treatment with 40 mg/day simvastatin: 100 randomly selected from the full range of the LDL-C response distribution and 24 each from the top and bottom 10% of this distribution (“good” and “poor” responders, respectively). The metabolic signature of drug exposure in the full range of responders included essential amino acids, lauric acid (p<0.0055, q<0.055), and alpha-tocopherol (p<0.0003, q<0.017). Using the HumanCyc database and pathway enrichment analysis, we observed that the metabolites of drug exposure were enriched for the pathway class amino acid degradation (p<0.0032). Metabolites whose change correlated with LDL-C lowering response to simvastatin in the full range responders included cystine, urea cycle intermediates, and the dibasic amino acids ornithine, citrulline and lysine. These dibasic amino acids share plasma membrane transporters with arginine, the rate-limiting substrate for nitric oxide synthase (NOS), a critical mediator of cardiovascular health. Baseline metabolic profiles of the good and poor responders were analyzed by orthogonal partial least square discriminant analysis so as to determine the metabolites that best separated the two response groups and could be predictive of LDL-C response. Among these were xanthine, 2-hydroxyvaleric acid, succinic acid, stearic acid, and fructose. Together, the findings from this study indicate that clusters of metabolites involved in multiple pathways not directly connected with cholesterol metabolism may play a role in modulating the response to simvastatin treatment.Trial RegistrationClinicalTrials.gov NCT00451828

Necessity of Fractionated Urine Collection for Monitoring Patients with Cystinuria

To the Editor: Cystinuria is an inherited form of nephrolithiasis caused by mutations in the SLC7A9 1 [solute carrier family 7 (cationic amino acid transporter, y+ system), member 9] and SLC3A1 [solute carrier family 3 (cystine, dibasic and neutral amino acid transporters, activator of cystine, dibasic and neutral amino acid transport), member 1] genes, which encode the luminal transporter b(0,+) AT subunit and rBAT subunit, respectively. The disease is characterized by impaired proximal tubular and intestinal reabsorption of cystine and the dibasic amino acids ornithine, lysine, and arginine (1). Treatment of cystinuria aims to prevent new stone formation and consists of increased fluid intake, urine alkalinization, and cystine-binding drugs for avoiding urinary cystine hypersaturation, which occurs …

LC‐MS/MS determination of dibasic amino acids for the diagnosis of cystinuria. Application in a family affected by a novel splice‐acceptor site mutation in the SLC7A9 gene

Cystinuria is an autosomal recessive disorder caused by defective transport of cystine and the dibasic amino acids ornithine, lysine and arginine across cell membranes. Poor solubility of cystine in urine leads to kidney stones and associated symptoms and complications. Mutations of genes SLC3A1 and SLC7A9 encoding for amino acid transport systems are responsible for different types of cystinuria. In this study we describe a new LC-MS/MS assay for these amino acids in urine. Moreover, we report a novel splice-acceptor site mutation in the SLC7A9 gene that we believe is the cause of the phenotype observed in four siblings from a first-cousin marriage. Into the wells of a 96-well microtitre plate, 10 microl of urine was mixed with 90 microl of a solution containing [(2)H4]cystine, [(2)H2]ornithine, [(13)C,(2)H4]arginine and [(2)H5]glutamine that was used as an internal standard for lysine. Chromatographic separation was achieved isocratically and detection was in the selected-reaction monitoring mode. The injection-to-injection time was 8 min. Calibration curves were linear up to 1000 micromol/L. Intra-day (n = 10) and inter-day (n = 6) variations (750 and 10 micromol/L) were less than 11.4%. Urine samples from healthy individuals (n = 135) were analysed and age-matched reference ranges were generated. The method was applied retrospectively and prospectively to analyse samples (n = 13) from nine cystinuria patients. The mutation reported here was not found in 100 controls with similar ethnicity to the studied family and is believed to have consequences for the transcribed mature RNA and protein structure and function.