Nobuo Ogata

Elevated Interleukin-8 Levels in the Urine of Children with Renal Scarring and/or Vesicoureteral Reflux

PURPOSE Elevation of urinary levels of interleukin-6 and 8 has been observed in patients with acute urinary tract infections. However, to our knowledge there have been no studies concerning the secretion of interleukin-6 and 8 into the urine after acute inflammation has resolved and renal scarring has occurred. On the other hand, it is well known that cytokines are variously related to glomerular diseases and, thus, it is possible that the progression of reflux nephropathy depends on interleukin-6 or 8. Therefore, we assessed urinary levels of interleukin-6 and 8 in children with vesicoureteral reflux and/or renal scarring. MATERIALS AND METHODS We evaluated interleukin-6 and interleukin-8 levels in the urine of 32 children without a urinary tract infection who presented or were admitted to our hospital because of vesicoureteral reflux between April and December 1994. Interleukin-6 and 8 were determined using a commercially available human enzyme-linked immunosorbent assay kit and the 2-step sandwich method. RESULTS Urinary interleukin-6 levels were below the lower detection limit (less than 10 pg./ml.) in all samples. There were statistically significant differences between urinary interleukin-8 levels in children with and without renal scarring (p = 0.001), and with and without vesicoureteral reflux (p = 0.0246). CONCLUSIONS Urinary interleukin-8 is an effective marker for renal scarring and vesicoureteral reflux.

Antioxidant Effect on Renal Scarring following Infection of Mannose-Sensitive-Piliated Bacteria

Renal scars have been considered to occur in later stages of chronic pyelonephritis. In our experimental pyelonephritis model, bacteria which possessed mannose-sensitive (MS) pili on the surface promoted renal scarring following inoculation to the renal parenchyma. Polyethylene glycol-modified superoxide dismutase (PEG-SOD) and 2-O-octadecylascorbic acid (CV3611) significantly suppressed scarring when administered orally or parenterally during the early stage of kidney infection with MS-piliated bacteria. These findings suggest that the superoxide and other active oxygens play an important role in renal scarring following infection and that PEG-SOD and CV3611 may be agents capable of preventing renal scarring following bacterial pyelonephritis.

Role of superoxide in renal scarring following infection by mannose-sensitive piliated bacteria

SummaryThe role of superoxide in scar formation following renal infection caused by mannose-sensitive (MS) piliated strains of bacteria was studied in the experimental pyelonephritis model using female Sprague-Dawley rats. The MS piliated strain stimulated renal scarring to a significantly greater extent than either the non-piliated or MR-piliated strain. Modulation of leukocytes by administering cyclophosphamide to induce neutropenia and colchicine to inhibit leukocyte migration was effective in preventing renal scarring. Treatment with superoxide dismutase during the early stage of infection was also effective in preventing scar formation. Finally, the production of superoxide by rat leukocytes was significantly larger following stimulation by MS piliated than either the nonpiliated or MR piliated strains. These observations suggest that superoxide released from leukocytes plays a critical role in the development of renal scarring following a bacterial infection, especially by MS piliated strains.

Neutrophil function in hyperosmotic NaCl is preserved by phosphoenol pyruvate

SummaryHyperosmolority in the urinary tract inhibits the host defense against bacterial infection. NaCl contributes most to osmolority in the renal medulla and urine. Therefore, we studied the effect of hyperosmolar NaCl on neutrophil function. When osmolarity was increased by NaCl, polymorphonuclear leukocytes (PMNL) became defective in phagocytosis, intracellular killing of bacteria, chemotactic activity, and superoxide production. This coincided with a decrease in the intracellular adenosine triphosphate (ATP) content of PMNL. Both the inhibition of superoxide production and the reduction in ATP content did not occur at 4°C. By increasing ATP content, phosphoenol pyruvic acid (PEP) protected against the decrease in superoxide production. These results suggest that leukocyte function is inhibited by high concentrations of NaCl due to the activation of the Na+−K+ pump. PEP, an ATP precursor, can protect PMNL against osmotic stress by raising the intracellular concentration of ATP.

Effect of Prednisolone on Renal Scarring in Rats Following Infection with Serratia marcescens

Renal scarring is considered a criterion of reflux nephropathy and the end stage of pyelonephritis. Prednisolone, a strong anti-inflammatory drug, at doses of 1 or 2 mg/kg prevented renal scarring in rats following infection with Serratia marcescens. Four or 8 mg/kg of prednisolone, however, did not inhibit renal scar formation. In a time course experiment, renal scarring was prevented when 4-day treatment with prednisolone was initiated 2, 5, or 13 days after infection. These results show that prednisolone is effective in preventing such scarring and suggest the clinical use of this drug for preventing renal scar formation after pyelonephritis and reflux nephropathy.

A Case of Bladder Pheochromocytoma

The clinical picture of bladder pheochromocytoma is usually typical; however, the diagnosis is occasionally delayed because of the rarity of this neoplasm. We report a case of unsuspected bladder pheochromocytoma in which the patient had a hypertensive episode during transurethral resection. A 67-year-old male presented with the chief complaint of painless macrohematuria. Cystoscopy revealed a submucosal tumor on the right lateral wall of the bladder. The tumor was operated on transurethrally, followed by partial cystectomy. The pathological diagnosis was pheochromocytoma, primarily occurring in the bladder. Treatment of this lesion requires a high degree of clinical suspicion based on the patient’s symptom complex in order to enable adequate preparation prior to surgical manipulation.

Significance of urinary endotoxin concentration in patients with urinary tract infection.

SummaryEndotoxin is a component of the outer membrane of gram-negative rods (GNR). Since GNR are responsible for the majority of urinary tract infection (UTI), we measured the concentration of endotoxin in urine using chromogenic endotoxin-specific assay and examined its diagnostic utility in patients with suspected UTI. In all 18 urine samples with an endotoxin concentration exceeding 350 pg/ml and 2 samples with 10–350 pg/ml of endotoxin concentration, GNR were detected at a count of 104 cfu/ml. Negative for endotoxin were 3 samples of culture positive for grampositive cocci (GPC), 2 samples containing various bacterial contaminants and all 37 samples with no growth on culture. Two urine samples collected 5 h after antibiotic dosage showed negative culture for GNR but a significant concentration of endotoxin. In an in vitro experiment, a residual concentration of antibiotic in urine inhibited bacterial growth, leading to a falsenegative culture. These results suggest that chromogenic endotoxin assay is a reliable method for diagnosing UTI caused by GNR and detecting false-negative culture of GNR.

Enhancement of superoxide production of polymorphonuclear neutrophils by ofloxacin and the effects of the inhibitors of protein kinase C

Polymorphonuclear neutrophils (PMN) represent an important defense mechanism against bacterial infection. Superoxide is one of the most important factors released by PMN following various stimulations including bacteria. Augmentation of chemiluminescence response of PMN stimulated by phorbol myristate acetate was observed following the addition of 25-200 micrograms/ml of ofloxacin, a new quinolone antimicrobial agent. In addition, the effects of two inhibitors of protein kinase C, staurosporine and H-7, were examined. The augmented superoxide production was inhibited by 1 or 2 microM of staurosporine or 50 or 100 microM of H-7. These results suggest that ofloxacin augments superoxide production of PMN and that this augmentation is probably due to the enhancement of leukocyte protein kinase C.

Suppression of Chemotactic Activity of Neutrophils in Hyperosmotic Conditions Comparable to the Renal Medulla: Partial Preservation by Phosphoenolpyruvate

Chemotaxis is one of the most important functions of the polymorphonuclear leukocyte (PMN). In the host defense against pyelonephritis, the renal medulla is a site of interaction between bacteria and PMNs. At this site the osmotic pressure is elevated due to a high concentration of NaCl and urea. We evaluated the in vitro chemotactic activity of PMNs under the hyperosmolar conditions created by high concentrations of NaCl and urea. This activity was suppressed by the stimulation of opsonized zymosan and formyl-methionyl-leucyl-phenylalanine. The inhibition of chemotaxis was partially preserved by phosphoenolpyruvic acid (PEP), a precursor of adenosine triphosphate (ATP), in hyperosmolar NaCl but not in urea. The intracellular content of ATP was increased by supplementing the hyperosmolar NaCl with PEP. These observations suggest that inhibition of the chemotactic activity of PMNs is due to differing mechanisms for each NaCl and urea, and that PEP may protect the PMNs against hyperosmolar NaCl by maintaining ATP content.

Direct Inactivation of Human Polymorphonuclear Leukocyte by Hyperosmotic Urea Comparable to the Renal Medulla

Hyperosmolarity in the renal medulla inhibits host defenses against bacterial pyelonephritis. Urea and NaCl contribute most to high osmolarity in the renal medulla. We therefore examined the inhibitory mechanism of urea on superoxide generation by human polymorphonuclear leukocytes. Superoxide production was inhibited by high concentration of urea. This inhibition was found to be direct and immediate. In addition, direct inactivation of NADPH oxidase, the key enzyme complex of superoxide generation, was shown by an NADPH oxidase activity assay using cell lysates of polymorphonuclear leukocytes stimulated by phorbol myristate acetate. The inhibitory effect of urea on NADPH oxidase was reversed by washing urea out of the assay system of cell lysates. Kinetic analysis of the inhibition of NADPH oxidase activity by urea showed decreased Vmax and Km, suggesting uncompetitive inhibition. These findings suggested that urea inactivated polymorphonuclear leukocyte superoxide production through a direct and uncompetitive inhibition of NADPH oxidase.