Slc7a9 knockout mouse is a good cystinuria model for antilithiasic pharmacological studies

The reaction of ninhydrin with primary amino groups to form the purple dye now called Ruhemann's purple (RP) was discovered by Siegfried Ruhemann in 1910. In addition, imines such as pipecolic acid and proline, the guanidino group of arginine, the amide groups of asparagine, the indole ring of tryptophan, the sulfhydryl group of cysteine, amino groups of cytosine and guanine, and cyanide ions also react with ninhydrin to form various chromophores of analytical interest. Since its discovery, extensive efforts have been made to apply manual and automated ninhydrin reactions as well as ninhydrin spray reagents to the detection, isolation, and analysis of numerous compounds of interest across a broad spectrum of disciplines. These include agricultural, biochemical, clinical, environmental, food, forensic, histochemical, microbiological, medical, nutritional, plant, and protein sciences. This reaction is unique among chromogenic reactions in that at pH 5.5 it results in the formation of the same soluble chromophore by all primary amines which react, be they amines, amino acids, peptides, proteins, and even ammonia. Because the chromophore is not chemically bound to the protein or other insoluble material, it is not lost when the insoluble substrate is removed by centrifugation or filtration after the reaction is completed. The visible color of the chromophore is distinctive and is generally not affected by the yellow colors present in many food, plant, and tissue extracts. Adaptations of the classical ninhydrin reaction to specialized needs in analytical chemistry and biochemistry include the use of acid, alkaline, and fluorogenic ninhydrin reagents. To cross-fertilize information among several disciplines wherein an interest in the ninhydrin reaction has developed, and to enhance its utility, this review attempts to integrate and correlate the widely scattered literature on ninhydrin reactions of a variety of structurally different compounds. Specifically covered are the following aspects: historical perspective, chemistry and mechanisms, applications, and research needs. A better understanding of these multifaceted ninhydrin reactions provide a scientific basis for further improvements of this important analytical technique.

Atherosclerosis is a chronic inflammatory disease, and is the primary cause of heart disease and stroke in Western countries. Derivatives of cannabinoids such as delta-9-tetrahydrocannabinol (THC) modulate immune functions and therefore have potential for the treatment of inflammatory diseases. We investigated the effects of THC in a murine model of established atherosclerosis. Oral administration of THC (1 mg kg(-1) per day) resulted in significant inhibition of disease progression. This effective dose is lower than the dose usually associated with psychotropic effects of THC. Furthermore, we detected the CB2 receptor (the main cannabinoid receptor expressed on immune cells) in both human and mouse atherosclerotic plaques. Lymphoid cells isolated from THC-treated mice showed diminished proliferation capacity and decreased interferon-gamma secretion. Macrophage chemotaxis, which is a crucial step for the development of atherosclerosis, was also inhibited in vitro by THC. All these effects were completely blocked by a specific CB2 receptor antagonist. Our data demonstrate that oral treatment with a low dose of THC inhibits atherosclerosis progression in the apolipoprotein E knockout mouse model, through pleiotropic immunomodulatory effects on lymphoid and myeloid cells. Thus, THC or cannabinoids with activity at the CB2 receptor may be valuable targets for treating atherosclerosis.

Cystinuria (MIM 220100) is a common recessive disorder of renal reabsorption of cystine and dibasic amino acids. Mutations in SLC3A1, encoding rBAT, cause cystinuria type I (ref. 1), but not other types of cystinuria (ref. 2). A gene whose mutation causes non-type I cystinuria has been mapped by linkage analysis to 19q12-13.1 (Refs 3,4). We have identified a new transcript, encoding a protein (bo, +AT, for bo,+ amino acid transporter) belonging to a family of light subunits of amino acid transporters, expressed in kidney, liver, small intestine and placenta, and localized its gene (SLC7A9) to the non-type I cystinuria 19q locus. Co-transfection of bo,+AT and rBAT brings the latter to the plasma membrane, and results in the uptake of L-arginine in COS cells. We have found SLC7A9 mutations in Libyan-Jews, North American, Italian and Spanish non-type I cystinuria patients. The Libyan Jewish patients are homozygous for a founder missense mutation (V170M) that abolishes b o,+AT amino-acid uptake activity when co-transfected with rBAT in COS cells. We identified four missense mutations (G105R, A182T, G195R and G295R) and two frameshift (520insT and 596delTG) mutations in other patients. Our data establish that mutations in SLC7A9 cause non-type I cystinuria, and suggest that bo,+AT is the light subunit of rBAT.