Schubert Gernot, Reck Günter, Jancke Harald, Kraus Werner, Patzelt Christoph
Vivantes Klinikum im Friedrichshain, Institut für Laboratoriumsdiagnostik, Landsberger Allee 49, 10249 Berlin, Germany.
Urol Res. 2005 Jun;33(3):231-8. doi: 10.1007/s00240-005-0467-5. Epub 2005 May 29.
In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this huge sample, 15 specimens originating from a total of eight patients were observed showing similar characteristics but escaping unambiguous identification with any of the substances that have been described so far in urinary concrements. Therefore, the unknown substance was submitted to a more extended analytical regimen. Structural analysis by x-ray crystallography turned out to be most successful, identifying the unknown material as uric acid monohydrate. Uric acid monohydrate crystallizes in the monocline space group P2(1)/c. Within the crystal, uric acid and water molecules form continuous layers by hydrogen bonds. This is in contrast to uric acid in its water free and its dihydrate forms, which both crystallize by forming 3-dimensional networks To the best of our knowledge , the existence of a monohydrate form of uric acid has not been reported so far. Accordingly, this is the first report on uric acid monohydrate as a urinary stone component. The frequency of only 0.015% in our survey indicates that uric acid monohydrate is rarely the main component in concrements, in contrast to uric acid and uric acid dihydrate with frequencies of 10% and 6%, respectively. The infrared spectrum of uric acid monohydrate is very similar to that of the other crystal forms of uric acid. Because of this similarity and its low frequency, uric acid monohydrate may have been overlooked as a component of urinary concrements. X-ray diffraction allows for better differentiation in routine stone analysis. All samples of uric acid monohydrate were found by solid state NMR spectroscopy to be highly contaminated by amorphous material. This material consisted of long aliphatic chains reminiscent of lipids and fatty acids, respectively. Concrements consisting of other forms of uric acid or urate lacked this amorphous component. Therefore, a role of this aliphatic material has to be taken into consideration when discussing the conditions that may favour the rare formation of concrements from uric acid monohydrate. As for as the metabolic situation of the affected patients is concerned, no common peculiarities became evident by a retrospective survey.
自1972年以来，我们实验室已分析了超过100,000颗尿结石。在这个庞大的样本中，观察到来自8名患者的15个标本具有相似的特征，但无法用目前已报道的任何尿结石成分明确鉴定。因此，将这种未知物质进行了更广泛的分析。通过X射线晶体学进行的结构分析最为成功，确定未知物质为一水合尿酸。一水合尿酸在单斜空间群P2(1)/c中结晶。在晶体中，尿酸和水分子通过氢键形成连续的层。这与无水尿酸及其二水合物形式不同，它们都通过形成三维网络结晶。据我们所知，迄今为止尚未报道过一水合尿酸形式的存在。因此，这是关于一水合尿酸作为尿结石成分的首次报道。我们的调查中其频率仅为0.015%，这表明与频率分别为10%和6%的尿酸和二水合尿酸相比，一水合尿酸很少是结石的主要成分。一水合尿酸的红外光谱与尿酸的其他晶体形式非常相似。由于这种相似性及其低频率，一水合尿酸可能被忽视作为尿结石的一种成分。X射线衍射在常规结石分析中能实现更好的区分。通过固态核磁共振光谱发现，所有一水合尿酸样品都被非晶态物质高度污染。这种物质由分别让人联想到脂质和脂肪酸的长脂肪链组成。由其他形式的尿酸或尿酸盐组成的结石缺乏这种非晶态成分。因此，在讨论可能有利于一水合尿酸罕见形成结石的条件时，必须考虑这种脂肪族物质的作用。就受影响患者的代谢情况而言，回顾性调查未发现明显的共同特点。
