Prevention of Kidney Stone Crystal Retention

描述(由申请人提供)：肾结石是一个严重的医疗问题，会导致发病率，并因急诊室就诊、药物治疗、碎石或其他程序而产生费用。这项工作的长期目标是生产一种适合在人体上进行测试的晶体沉积抑制剂。这项工作的总体假设是，晶体附着抑制剂将是临床肾结石的有效治疗剂。具体目的如下：1.检测分子抑制一水草酸钙(COM)晶体附着于内髓集合管(IMCD)细胞或相互附着的能力。我们将分别使用体外细胞培养和聚集试验，测试阴离子均聚物聚(天冬氨酸)、聚(谷氨酸)和聚(丙烯酸)酸，以确定COM晶体与IMCD细胞和彼此附着的最有效的抑制剂。此外，我们还将确定具有其他阴离子功能位的聚合物，如聚丝氨酸、硫化碳水化合物依诺肝素和戊聚糖、一些含唾液酸寡糖以及磷酸化蛋白质和多肽均聚物是否对晶体附着有类似的影响。2.检测晶体附着抑制物对实验动物晶体沉积的影响。多阴离子和含有可能干扰晶体附着的其他官能团的小到中等分子量聚合物将被测试，当使用植入的渗透微泵给药时，它们抑制乙二醇和NH4C1处理的大鼠的草酸钙晶体沉积的能力。我们还将通过用荧光染料或生物素标记化合物以允许检测，来确定有效的草酸钙晶体保留抑制剂进入尿液的情况。还将对这些动物的肾功能进行测量，以寻找早期的肾毒性。3.确定口服哪种抑制剂有效。使用植入的微泵给药时，有效防止草酸钙晶体滞留的抑制剂将在口服时测试其抑制晶体滞留的能力。必要时将采用给药方案、喂养策略、全身用药或辅助剂，以通过口服途径输送足够量的抑制剂。4.确定有效的抑制剂是否具有显著的短期和中期全身毒性和肾脏毒性。几种口服有效的抑制剂将以其有效剂量的5-10倍给大鼠服用，最长可达180天。将观察动物的总体健康状况，那些生病或达到研究期结束的动物将进行一系列完整的实验室测试。所有患病的动物和在研究结束时看起来健康的部分动物都将进行尸检。在该项目结束时，我们预计将有三种试剂适合进行更全面的动物毒性研究，估计是由具有满足FDA要求的经验的商业实验室进行的。如果它们中的任何一个适当地无毒，第一阶段的人体试验将被考虑，大概是由持牌人进行的。

DESCRIPTION (provided by applicant): Kidney stones are a significant medical problem, causing morbidity and entailing expenses due to emergency room visits, medications, and lithotripsy or other procedures. The long-term goal of this work is to produce an inhibitor of crystal deposition that would be suitable for testing in humans. The overall hypothesis of this work is that inhibitors of crystal attachment will be effective therapeutic agents in clinical nephrolithiasis. Specific objective are as follows: 1. To test molecules for the ability to inhibit calcium oxalate monohydrate (COM) crystal attachment to inner medullary collecting duct (IMCD) cells or to one another. We will test the anionic homopolymers poly(aspartic), poly(glutamic), and poly(acrylic) acids to determine the most effective inhibitors of COM crystal attachment to IMCD cells and to each other, using in vitro cell culture and aggregation assays, respectively. In addition, we will determine whether polymers with other anionic functional sites, poly(serine), the sulfated carbohydrates enoxiparin and pentosan, some sialie acid-containing oligosaccharides, and phosphorylated proteins and peptide homopolymers, have similar ef- fects on crystal attachment. 2. To test inhibitors of crystal attachment to cultured cells for their ability to ameliorate crystal deposition in ex- perimental animals. Polyanions and small to intermediate MW polymers containing other functional groups that may interfere with crys- tal attachment will be tested for their ability to inhibit calcium oxalate crystal deposition in rats treated with ethylene glycol and NH4C1 when administered using implanted osmotic minipumps. We will also determine the delivery to urine of effective inhibitors of calcium oxalate crystal retention by labeling compounds with fluorescent dyes or with biotin to permit detection. Renal function will also be measured in these animals to look for early renal toxicity. 3. To determine which of the inhibitors are effective when given orally. Inhibitors that are effective at preventing calcium oxalate crystal retention when administered using the implanted minipumps will be tested for their ability to inhibit crystal retention when given orally. Dosage regimens, feeding strategies, systemic medications, or accompany- ing agents will be employed as necessary to deliver adequate amounts of inhibitors via the oral route. 4. To determine whether the effective inhibitors have significant short and intermediate-term general and renal toxicity. Several inhibitors that are effective with oral dosing will be administered to rats at 5-10 times their effective doses for up to 180 days. Animals will be observed for general well being, and those that become sick or reach the end of the study period will have a complete battery of laboratory tests drawn. All ill animals and a selection of animals that appear healthy at the end of the study period will have necropsies performed. At the conclusion of this project, we expect to have three agents suitable for more comprehensive animal toxicity studies, presumably performed by a commercial laboratory with experience in satisfying FDA requirements. Should any of them be suitably free of toxicity, Phase I testing in human would be contemplated, presumably by a licensee.