STUDY ON MECHANISM OF URATE STONE FORMATION

I. LIGHT MICROSCOPIC STUDY

Abstract

Existence of uric acid and urate stone was reported before Christ and also reported as a complication of gout. Complications of uric acid and urate stone with hyperuricemia are said to be 5 to 33% and hyperuricemia has been recently studied extensively. It has become possible to produce hyperuricemia experimentally since Johnson et al., in 1969, succeeded in making an experimental animal hyperuricemia with oxonic acid potassium salt as uricase inhibitor.
In this study, male rats of Wister line weighing about 150g were used and a control group and was fed on JAPAN-CLEA-CE-2 alone and an experimental group was fed on calculus meals of 2% of uric acid, 5% of oxonic acid potassium salt and 93% of JAPAN-CLEA-CE-2 to induced hyperuricemia and urate renal stone and time-course measurement was done on blood urea nitrogen, serum creati nine, serum uric acid and body weight. The following results were obtained after light microscopic observation of the kidney for the generation mechanism of urate stone.
1) In comparison with the control group, blood urea nitrogen, serum creatinine and serum uric acid increased as time elapsed and body weihgt decreased remarkably in an experimental group.
2) Rat kidney of the experimental group was somewhat atrophic and hard, its surface was uneven, a fan-shaped deposition of yellowish white granullar substances were seen corresponding with renal pyramid at the section and many cysts were observed at the cortico-marrow junction. Many small crashable stones were observed in the renal pelvis and the ureter.
3) During light microscopic observation of experimental rats, no marked change was seen in the glomerulus and the vascular system, and in renal tubules, edema-like swellings and degenerations of epithelial cells were observed and the epithelial cells was PAS positive. Inside of the tubule cavity, there observed PAS positive muddy substances, PAS positive protein-like substances, PAS positive casts, decidual cells and inflammatory cells.
4) Collecting tubules showed degreneration of epithelial cells and PAS positive protein-like substances, amorphous substances, cellular casts and hyaline casts were seen in the tubule cavity and the amorphous substances were present either inside of cellular casts or surrounded by inflammatory cells and exfoliated cells.
5) Intra-tubular amorphous substances showed positive by De Galantha's stain and urate crystals were observed like radiating pins in the center of them. Deposition of urates, however, was not recognized in the epithelial cells and on the basal membrane of the collecting tubule.
6) Although strong fibrication, proliferation of connective tissue and infiltration of lymphocytes were recognized in stroma, no depositiion of urate was recognized.