Sanehiro Hokama

Oxalate-Degrading Enterococcus faecalis

An oxalate‐degrading Enterococcus faecalis was isolated from human stools under anaerobic conditions. The bacteria required a poor nutritional environment and repeated subculturing to maintain their oxalate‐degrading ability. The E. faecalis produced 3 proteins (65, 48, and 40 kDa) that were not produced by non‐oxalate‐degrading E. faecalis as examined by SDS‐PAGE. Antibodies against oxalyl‐coenzyme A decarboxylase (65 kDa) and formyl‐coenzyme A transferase (48 kDa) obtained from Oxalobacter formigenes (an oxalate‐degrading anaerobic bacterium in the human intestine) reacted with 2 of the proteins (65 and 48 kDa) from the E. faecalis as examined by Western blottings. This is the first report on the isolation of oxalate‐degrading facultative anaerobic bacteria from humans.

Urolithiasis in Okinawa, Japan : A relatively high prevalence of uric acid stones

Aim:  The aim of the present study was to investigate the composition of urinary tract stones in patients from Okinawa, the most southern island group of Japan.

URINARY SATURATION AND RISK FACTORS FOR CALCIUM OXALATE STONE DISEASE BASED ON SPOT AND 24-HOUR URINE SPECIMENS

In 222 random spot urine specimens, the calcium concentration and calcium oxalate saturation [DG(CaOx)] were significantly higher among stone formers than among non-stone formers, while the citrate and creatinine-corrected citrate concentrations were lower. In 188 24-hour urine specimens, magnesium excretion was lower among stone formers than non-stone formers, while the creatinine-corrected calcium concentration and DG(CaOx) were higher. Among stone formers, there was no gender difference in the urinary concentrations of calcium, oxalate, citrate, magnesium, and DG(CaOx), but the creatinine-corrected calcium, citrate, and magnesium concentrations were higher in women, as well as 24-hour citrate excretion. The levels of calcium and oxalate have a major influence on DG(CaOx), while citrate and magnesium levels have a minor influence. DG(CaOx) was correlated with calcium and oxalate excretion, as well as with the creatinine-corrected calcium and oxalate concentrations. Approximately 5% of 24-hour urine specimens showed critical supersaturation, 80% showed metastable supersaturation, and 15% were unsaturated. Hypercalciuria or hyperoxaluria was fairly common (30% and 40%) in critically supersaturated urine, while it was less common (22.4% and 8.6%) in metastably supersaturated urine and was not detected in unsaturated urine. Hypocitraturia and/or hypomagnesiuria was more common (63.8-80%) at any saturation. The urinary calcium, oxalate, and citrate concentrations, as well as the creatinine-corrected calcium, oxalate, citrate, and magnesium concentrations and DG(CaOx), showed a significant correlation between 57 paired early morning spot urine and 24-hour urine specimens. The creatinine-corrected calcium and citrate concentrations of the early morning urine specimens were significantly correlated with the levels of calcium and citrate excretion in the paired 24-hour urine specimens. In conclusion, no parameter other than urinary saturation gives more than a vague indication of the risk of lithogenesis, so DG(CaOx) in either early morning urine or 24-hour urine specimens appears to be the best predictor of stone risk. Finally, the creatinine-corrected calcium and citrate concentrations in early morning urine can be used as a substitute for measuring 24-hour excretion.

Oxalate-degrading Providencia rettgeri isolated from human stools.

Abstract  Background:  Oxalate‐degrading bacteria are thought to metabolize intestinal oxalate and thus decrease the urinary excretion of oxalate by reducing its intestinal absorption.

Milk and calcium prevent gastrointestinal absorption and urinary excretion of oxalate in rats.

Dietary oxalate plays a very important role in the formation of calcium oxalate stones, and dietary intake of calcium may decrease oxalate absorption and its subsequent urinary excretion. The purpose of the present study was to determine the effect on urinary oxalate excretion of an acute oral calcium load, standard milk, or high-calcium low-fat milk followed by a dose of oxalic acid. Male Wistar rats weighing 180-200 g were divided into 7 groups of 6 rats each. All animals were fasted for about 24 hours, anesthetized, and hydrated with normal saline at 3-4 mL/hour. Then the animals were given 1 mL of normal saline [Control], 10 mg (111.1 micromol) of oxalic acid [Ox alone], 2 mL of standard milk (calcium: 1.16 mg or 29 micromol/mL) [NCa milk], 2 mL of high-calcium low-fat milk (calcium: 2.05 mg or 51.3 micromol/mL) [HCa milk], equimolar calcium (4.44 mg or 111 micromol) followed by 10 mg of oxalic acid [Ca + Ox], 2 mL of high-calcium low-fat milk followed by 10 mg of oxalic acid [HCa milk + Ox], or 2 mL of standard milk followed by 10 mg of oxalic acid [NCa milk + Ox]. All treatments were administered via a gastrostomy. Urine samples were collected by bladder puncture just before administration and at hourly intervals up to 5 hours afterwards. Urinary oxalate was measured by capillary electrophoresis, while urinary calcium, magnesium and phosphorus were measured by inductively coupled plasma spectrometry. Urinary oxalate excretion peaked at 1 hour in the Ox alone group, while it peaked at 2 or 3 hours in the Ca + Ox, HCa milk + Ox, and NCa milk + Ox groups. Urinary oxalate excretion decreased significantly when 10 mg of oxalate was administered immediately after the administration of equimolar calcium, high-calcium low-fat milk, or standard milk. The cumulative urinary oxalate excretion over 5 hours was approximately 13.6%, 3.5%, 1.6%, and 2.4% in the Ox alone, Ca + Ox, HCa milk + Ox, and NCa milk + Ox groups, respectively. In conclusions, this study demonstrated that calcium salt, or dairy products containing calcium (especially high-calcium low-fat milk) could decrease the gastrointestinal absorption and subsequent urinary excretion of oxalate.

Changes of bladder activity and glycine levels in the lumbosacral cord after partial bladder outlet obstruction in rats

Objectives:  We investigated the time course of changes in bladder activity as well as in spinal and serum levels of glutamate and glycine after partial bladder outlet obstruction (BOO) in rats.

Migration of a metal clip into the urinary bladder

Migration of metal clips into the urinary tract is rare. We present a case in which migration of a metal clip into the urinary bladder occurred after retropubic radical prostatectomy. A 75-year-old man, who had undergone retropubic radical prostatectomy three years before, presented with painful micturition and gross hematuria. Radiography and cystoscopy showed two vesical stones. As treatment for these stones, transurethral holmium laser lithotripsy was performed. One of the stones had formed around a metal clip that had presumably migrated into the urinary bladder. After removal of both stones, the patient was able to void freely. In conclusion, it is important to remember that metal clips may migrate postoperatively and cause secondary complications. Therefore, metal clips should be applied sparingly at the vesicourethral anastomosis during retropubic radical prostatectomy.

Prognosis of bedridden patients with end-stage renal failure after starting hemodialysis

BackgroundThe mean age of starting hemodialysis (HD) in patients with end-stage renal failure is gradually increasing in Japan. It is not uncommon for HD to be commenced in bedridden elderly patients who cannot give informed consent, because of brain damage. However, we have not been able to provide useful advice to their families because there was no relevant information available about the prognosis of bedridden patients on HD. Therefore, we examined the prognosis of bedridden HD patients.MethodsTwo hundred and nineteen patients who received HD were enrolled. These subjects were divided into five groups; (aged <50, 50–59, 60–69, 70–79, and ≥80 years at the commencement of HD), and we compared the overall prognosis between bedridden and nonbedridden patients, as well as that for each age group.ResultsThere were 76 bedridden patients among the 219 HD patients, and the main cause of their bedridden state before starting HD was cerebrovascular disease. The 50% survival time after the start of HD was 120 months for the nonbedridden patients versus 56 months for bedridden patients. However, the mean (±SD) age of the bedridden patients was higher than that of nonbedridden patients (70 ± 13 versus 64 ± 14 years). In patients under age 50 years at the start of dialysis, the survival rate was lower in the bedridden than in the nonbedridden patients, but there were no differences between survival rates for bedridden and nonbedridden patients in the other four age groups.ConclusionsThe prognosis of HD patients is poor compared with the general life expectancy of the Japanese population, but whether these patients are bedridden or not has little influence on their survival.

PARTIAL NEPHRECTOMY USING A VASCULAR SEALING SYSTEM

PURPOSE The margin resected at partial nephrectomy is so fragile that it is not easy to control bleeding. To control bleeding we developed a new technique using a vascular sealing system for hemostasis. MATERIALS AND METHODS A 38-year-old woman with renal cell carcinoma underwent partial nephrectomy. A tumor was identified in the lower pole of the left kidney. The kidney was exposed with the perinephric fat and the main renal artery was identified and clamped. Along the incision line the renal cortex was cut sharply to 10 to 15 mm. deep. A jaw of the vascular sealing system was carefully inserted into the sinus space between the renal pelvis and medulla. The jaws were gradually clamped together, and the renal medulla and vasculature were compressed and then sealed completely by computer controlled current. Because the renal pelvis was involved by tumor, the pelvis was removed partially with the tumor and approximated with absorbable sutures. RESULTS Before reperfusion only a few additional sutures were needed for hemostasis. Warm ischemia time was 19 minutes. CONCLUSIONS Our technique seems to be a promising method of rapidly achieving reliable hemostasis for partial nephrectomy.

Effect of dehydroepiandrosterone on oxalate metabolism in rats.

Urinary oxalate plays an important role in the formation of calcium oxalate stone, and endogenous oxalate metabolism mainly occurs in the liver. Since dehydroepiandrosterone (DHEA) is known to have an effect on hepatocellular proliferation and on some hepatic enzymes, we examined the influence of DHEA on the activity of hepatic oxalate-related enzymes and on urinary oxalate excretion in rats. Fourteen male rats were castrated and divided into two groups. The control group was fed a standard diet, while the other rats were fed a diet containing 0.5% DHEA. After 4 weeks, the liver weight and the urinary levels of oxalate, glycolate, and glycine were significantly higher in the DHEA-treated rats than in the controls, while body weight did not differ between the two groups. Hepatic alanine:glyoxylate aminotransferase and glyoxylate reductase showed significantly higher activity in the DHEA-treated rats than in the controls, while glycolate oxidase activity was significantly reduced. Treatment with DHEA induced hyperoxaluria along with hepatocyte proliferation. This hyperoxaluria was probably caused by hepatocyte proliferation, but it could not be explained simply by the changes of hepatic oxalate-related enzymes. Investigation of the modulation of peroxisomal enzymes by peroxisomal proliferators or inhibitors may provide further insights into hepatocyte oxalate metabolism.