The role of long-term loading of cholesterol in renal crystal formation.

We studied the effects of cholesterol load on urinary stone in rats receiving a standard diet or a high fat diet. Sixty male rats were randomized to two groups and were fed either a standard diet (SD group) or a high fat diet (HFD group) for 8 weeks. Then the two groups were further divided into four groups. SD group, HFD group, SD + EG group (with standard diet + ethylene glycol administration for two weeks), and HFD + EG group (with high fat diet + ethylene glycol administration). The starting date of EG administration was considered to be week 0. Twenty-four-hour urine samples were collected in week 0, week 1, and week 2, and oxalate excretion and citrate excretion were measured by capillary electrophoresis analyzer The excretion of phosphorus, magnesium, and creatinine for 24 hours was measured using an automated analyzer Serum sodium, potassium, chloride, calcium, phosphate, magnesium, creatinine, total cholesterol, triglyceride, HDL-cholesterol and glucose were determined using an automated analyzer The kidney tissues were obtained to perform hematoxyline-eosine staining and Pizzolato's staining to detect oxalate-containing crystals. The average body weight in HFD groups and HFD + EG group in week 0 was significantly higher than that of SD group and SD + EG group. The calcium oxalate crystal deposition was not observed in all groups in week 0. HFD + EG group in week 1 had sporadically calcium oxalate crystal deposition in renal distal tubular cells and tubular lumens. In week 2, the number of crystal deposition in HFD + EG group was increased remarkably. The crystals were slightly observed in SD + EG group in week 2. The excretion of urinary calcium and phosphate in HFD group and HFD + EG group was significantly higher than that of the SD group and SD + EG group in week 0. The amount of urinary citrate excretion in the SD group and SD + EG group showed a significantly higher value compared with that of the HFD group and HFD + EG group in week 0. The level of serum total cholesterol in the HFD group and HFD + EG group was higher compared to that in the SD group and SD + EG group. The serum triglyceride level was not significantly different in the four groups in week 0. Interestingly, the level of triglyceride of EG administration groups (SD + EG and HFD + EG group) was significantly higher than that in EG no-administration groups (SD group and HFD group) in week 1 and week 2. The serum glucose level in the HFD group and HFD + EG group was significantly higher than that in the SD group and SD + EG group in week 0. In week 2, the glucose level of EG administration groups (HDF + EG group and SD + EG group) was significantly lower than that of EG no-administration groups (HFD group and SD group). In conclusion, this result suggested that long-term loading of cholesterol could increase renal calcium stone formation.

Successful formation of calcium oxalate crystal deposition in mouse kidney by intraabdominal glyoxylate injection.

The establishment of an experimental animal model would be useful to study the mechanism of kidney stone formation. A calcium kidney stone model in rats induced by ethylene glycol has been used for research; however, to investigate the genetic basis affecting kidney stone formation, which will contribute to preventive medicine, the establishment of a kidney stone model in mice is essential. This study indicates the optimum conditions for inducing calcium oxalate stones in normal mouse kidney. Various doses of oxalate precursors, ethylene glycol, glycolate and glyoxylate, were administered either by free drinking or intraabdominal injection for 2 months as a preliminary study. Stone formation was detected with light microscopy, polarized light optical microscopy and electron microscopy. Stone components were detected with X-ray diffraction analysis. The expression of osteopontin (OPN), a major stone-related protein, was detected with immunohistochemical staining, in situ hybridization and quantitative reverse transcriptase polymerase chain reaction. Kidney stones were not detected in ethylene glycol- or glycolate-treated groups even at the highest dose of LD(50). Whereas, numerous kidney stones were detected in glyoxylate-treated mice (more than 60 mg/kg) at 3, 6 and 9 days after glyoxylate were administered intraabdominally. However, the number of kidney stones decreased gradually at day 12, and was hardly detected at day 15. The stone component was further analyzed as calcium oxalate monohydrate. A dramatic increase in the expression of OPN was observed by the administration of glyoxylate. We established a mouse kidney stone experimental system in this study. The difficulty of inducing kidney stones suggested that mice have greater intrinsic ability to prevent stone formation with hyperoxaluric stress than rats. The differing response to hyperoxaluric stress between mice and rats possibly contributes to the molecular mechanism of kidney stone formation and will aid preventive medicine in the future.

[Optimal treatment of urolithiasis pain].

Many drugs have been used in the treatment of renal colic, but the safest and most effective drug has not yet been clearly defined. A questionnaire was used to collate the types of treatment for renal colic used by Japanese urologists. The main treatments were nonsteroidal analgesic (suppository) and anticholinergic agent. A new protocol was developed on the basis of this result, and its effect on renal colic was verified. The combination of an injection of a local anesthetic and pointillage was found to be superior to non-steroidal analgesic anti-inflammatory drugs and anticholinergic agent in terms of both duration of action and effectiveness.