Immunohistochemical localization of nephrocalcin, a kidney-specific glycoprotein, to renal cell carcinoma

OBJECTIVES

Nephrocalcin (NC), an acidic glycoprotein produced by renal proximal tubule cells and functioning as an inhibitor of calcium oxalate monohydrate crystalization, has been previously shown to have increased urinary excretion in patients with renal cell carcinoma (RCC). The current study uses immunohistochemical techniques to localize NC to cells of primary RCC.

METHODS

We studied 29 kidneys removed because of RCC. Slides were deparaffinized and stained after incubating with anti-NC antibody by using the avidin-biotin-peroxidase complex techniques. Uptake of stain by tumor cells and adjacent normal renal cells was compared.

RESULTS

Twenty-seven kidneys (93%) showed positive staining for RCC tumor cells; 2 kidneys staining positive for normal proximal tubule cells failed to stain adjacent RCC tumor cells (7%).

CONCLUSIONS

The data suggest that enhanced production of urinary NC in patients with RCC derives from cells of the primary tumor.

Use of a neural network to predict stone growth after shock wave lithotripsy

OBJECTIVES

To determine whether a neural network is superior to standard computational methods in predicting stone regrowth after shock wave lithotripsy (SWL) and to determine whether the presence of residual fragments, as an independent variable, increases risk.

METHODS

We reviewed the records of 98 patients with renal or ureteral calculi treated by primary SWL at a single institution and followed up for at least 1 year; residual stone fragment growth or new stone occurrence was determined from abdominal radiographs. A neural network was programmed and trained to predict an increased stone volume over time utilizing input variables, including previous stone events, metabolic abnormality, directed medical therapy, infection, caliectasis, and residual fragments after SWL. Patient data were partitioned into a training set of 65 examples and a test set of 33. The neural network did not encounter the test set until training was complete.

RESULTS

The average follow-up period was 3.5 years (range 1 to 10). Of 98 patients, 47 had residual stone fragments 3 months after SWL; of these 47, 8 had increased stone volume at last follow-up visit. Of 51 patients stone free after SWL, 4 had stone recurrence. Coexisting risk factors were incorporated into a neural computational model to determine which of the risk factors was individually predictive of stone growth. The classification accuracy of the neural model in the test set was 91%, with a sensitivity of 91%, a specificity of 92%, and a receiver operating characteristic curve area of 0.964, results significantly better than those yielded by linear and quadratic discriminant function analysis.

CONCLUSIONS

A computational tool was developed to predict accurately the risk of future stone activity in patients treated by SWL. Use of the neural network demonstrates that none of the risk factors for stone growth, including the presence of residual fragments, is individually predictive of continuing stone formation.

Use of continuous-infusion alfentanil for analgesia during spark-gap lithotripsy

The painful stimuli produced by a new generation of electrohydraulic/electromagnetic lithotripters are such that continuous infusion analgesia rather than general or regional anesthesia is appropriate. We describe our experience with continuous alfentanil infusion supplemented with intravenous bolus midazolam in caring for patients treated with an unmodified Medstone STS 1050 lithotripter. Ninety consecutive treatments using this technique averaged 63 minutes, compared with 69 minutes for 14 treatments done with general anesthesia and 88 minutes for 58 treatments done with epidural anesthesia. The stone burden, kilovoltage, and number of shocks were similar for the three groups, as was the immediate stone fragmentation rate. Only 2 of 90 patients received inadequate analgesia with the intravenous technique and required the induction of general anesthesia. Continuous-infusion analgesia appears sufficient to blunt the stimulus provided by the unmodified spark-gap lithotripters still in common use.

Racial variation in gender frequency of calcium urolithiasis

Calcium oxalate stones are known to occur most frequently in the fifth and sixth decades of life and in a male-to-female ratio of approximately 2:1. However, previous data are from predominantly white populations or from multiracial populations that have included patients with infection stones. We reviewed a population of 444 consecutive patients (189 white, 123 black and 132 Hispanic) from 1 urban hospital treated by shock wave lithotripsy for symptomatic renal and ureteral calculi, and added a population of 260 patients treated at a university hospital in Japan. Patients with infection stones and those with uric acid or cystine stones were excluded. We found men to be more commonly afflicted in the white (62%) and Asian (64%) populations but noted a reversal of gender frequency in the black and Hispanic populations, of which women comprised 68% and 60% of the stone population, respectively. We conclude that calcium urolithiasis is more common in women than previously reported, and discuss the possible etiologies.

Nephrocalcin in patients with renal cell carcinoma

Nephrocalcin, an acidic glycoprotein that inhibits calcium oxalate crystal growth, has been previously localized in proximal tubules of kidneys by an immunohistochemical staining method and purified from tissue culture media of 2 renal carcinoma cell lines. A polyclonal antibody specific to nephrocalcin was raised in rabbits and the level of nephrocalcin was quantitatively determined in urine of 19 renal cell carcinoma patients (0.241 +/- 0.341 microgram nephrocalcin per mg. creatinine) and compared to healthy controls (0.022 +/- 0.012 micrograms nephrocalcin per mg. creatinine). Nephrocalcin levels after tumor nephrectomy decreased dramatically in 5 patients and to a lesser degree in 7. A specific nephrocalcin fraction that was eluted from an anion exchange column with low ionic strength was detected in urine of the renal cell carcinoma patients, and this fraction decreased or disappeared after tumor nephrectomy in 6 of 9 patients studied. Amino acid composition, phosphate content and dissociation constants toward calcium oxalate monohydrate crystals were investigated in the nephrocalcin from tumor patients and compared to that from healthy controls. Our studies demonstrate that nephrocalcin in patients with renal cell carcinoma is atypical and usually in much higher quantity. Further studies are needed to determine the clinical significance of these observations.

Use of radionuclide renal imaging for clinical followup after extracorporeal shock wave lithotripsy of renal stones

Patients treated by extracorporeal shock wave lithotripsy (ESWL) are usually evaluated by excretory urography within 1 month after treatment to determine the clearance of stone debris and rule out asymptomatic obstruction. In an attempt to obtain more precise functional information, we used 99mtechnetium-diethylenetriaminepentaacetic acid and 131iodine-hippurate radionuclide renal imaging studies, and a plain abdominal radiograph as the initial followup study after ESWL of 64 kidneys in 55 patients. Of 53 kidneys studied within 60 days after ESWL 42 had abnormal radionuclide renal imaging studies demonstrating pelviocaliceal stasis, excretory delay or poor function, 8 of which required subsequent interventions for obstructing stone debris. Five patients had excretory delay after ESWL that was unexpected based on a pre-ESWL excretory urogram showing normal function without dilation. A subset of 23 patients with large stone burden or anatomical deformity from a prior operation had baseline radionuclide renal imaging studies before ESWL; function improved in 4 and worsened in 5 by radionuclide renal imaging studies after completion of treatment. A total of 19 patients had radionuclide renal imaging studies earlier (within 17 days) after ESWL because of poor function and/or large stone burden, and as expected they had evidence of obstruction from stone debris, which necessitated further followup. Our experience suggests that followup of ESWL by radionuclide renal imaging studies provides specific functional information that is of particular value in the management of patients with obstructing stone debris and/or diminished renal function. Radionuclide renal imaging studies may also reveal unsuspected obstruction or functional impairment after ESWL of uncomplicated stones, and is recommended as routine followup after ESWL.

Extracorporeal shock wave lithotripsy for struvite renal calculi: prospective study with extended followup

To clarify the significance of retained stone particles after extracorporeal shock wave lithotripsy (ESWL) for struvite renal calculi we followed 22 otherwise healthy women for 16 to 52 months (mean 39 months). Each patient had persistent Proteus mirabilis bacteriuria before ESWL and received a standardized regimen of antimicrobial therapy in the perioperative period only. Of the 22 patients 19 (86%) were cured of the persistent bacteriuria. Of these 19 patients 16 had retained stone particles at the beginning of surveillance and 10 had retained particles at last followup. None of the particles produced symptoms or enlarged. However, 1 of the patients who was rendered stone-free had a P. mirabilis reinfection at 20 months and a new stone developed. Of the 22 patients 3 (14%) had continued persistent P. mirabilis bacteriuria after ESWL. Two patients were subsequently cured of the infection with antibiotics alone (1), and with antibiotics and extraction of a new ureteral stone (1). The remaining patient had expansion of retained stone particles after 51 months of surveillance. We conclude that a stone-free kidney is an unrealistic objective of ESWL monotherapy for struvite renal calculi. However, the treatment usually will eradicate the accompanying persistent bacteriuria and sterile stone particles will not enlarge during the first 2 to 4 years after treatment.

Diagnostic artificial erection without corpus cavernosum injection

The vacuum erection device can be used to produce an artificial erection for documentation of penile curvature. This technique is illustrated in the preoperative evaluation of a patient with Peyronie's disease.

ESWL monotherapy for large-volume renal calculi: efficacy and morbidity

We assessed the efficacy and morbidity of extracorporeal shock-wave lithotripsy (ESWL) monotherapy in the treatment of 25 consecutive patients with large-volume renal calculi (surface area greater than or equal to 5.0 cm2). Eighteen of the calculi were infection (struvite) stones and 7 were sterile stones. In 21 cases internal ureteral stents were positioned before ESWL, but no patient underwent pretreatment percutaneous nephrostomy (PCN) or percutaneous nephrostolithotomy (PNL). An average of 2.1 procedures including ESWL, PCN, or ureteral interventions were required to achieve a stone-free renal collecting system and ureter, or residual stone particles less than 4 mm in diameter confined to the renal collecting system. Sixty percent of the patients required no ancillary procedures after ESWL. There were no differences in the mean duration of hospitalization, need for post-treatment ancillary procedures, time to clearance of ureteral fragments, and incidence of residual stone particles among patients with infection and sterile stones. Of 23 patients observed greater than three months (mean 10.9 mos) after ESWL, 43 percent had residual stone particles in the renal collecting system. Expansion of these particles or stone recurrence in the absence of residual particles has not been observed. We conclude that large volume renal calculi may be managed effectively and safely with ESWL monotherapy.

Bacteriuria following extracorporeal shock wave lithotripsy of infection stones

Extracorporeal shock wave lithotripsy effectively pulverizes infected (struvite) renal calculi. However, after treatment minute residual fragments that may harbor bacteria and cause persistent bacteriuria remain in the renal collecting system for months. We investigated prospectively the incidence of persistent Proteus mirabilis bacteriuria after extracorporeal shock wave lithotripsy among 15 consecutive women with Proteus mirabilis urinary tract infections and struvite calculi. All patients received parenteral gentamicin for 3 to 8 days (mean 4.7 days) immediately before and after extracorporeal shock wave lithotripsy. Oral antimicrobials then were administered for 14 to 34 days (mean 25 days). Ten patients have maintained a sterile urine or experienced urinary reinfection by other organisms during 8 to 19 months (mean 13 months) of subsequent bacteriological surveillance. Of these 10 patients 9 had residual fragments. Five patients had Proteus mirabilis bacteriuria after 1 to 7 months of surveillance, including 3 with residual fragments. The mean stone size, methods and duration of renal drainage procedures, and duration of antimicrobial therapy were similar for the 2 patient groups. Proteus mirabilis was isolated from the cultures of only 3 of 11 retrievable stone fragments. In contrast to intact infected renal calculi, residual stone fragments after extracorporeal shock wave lithotripsy often are susceptible to sterilization with antimicrobials.

Inferior epigastric varix masquerading as a pelvic mass

We report a case of an inferior epigastric varix as another disease entity to be considered in the differential diagnoses of pelvic masses.

Effect of D-mannose and D-glucose on Escherichia coli bacteriuria in rats

The effect of D-mannose and D-glucose on bacteriuria due to Escherichia coli with mannose-sensitive adhesins was investigated in adult male Sprague-Dawley rats undergoing diuresis. Inocula of 10(5), 10(7), or 10(8) bacteria in 0.1 ml of normal saline or 2.5% or 10% D-mannose or D-glucose were injected intravesically and urine was cultured 1, 3, 5, 7 and 9 days later. The levels of bacteriuria on days 1 and 5 were significantly lower in rats inoculated with 10(5) E coli and 10% D-mannose than in controls (p less than 0.05 and 0.01 respectively) and the percentages of rats with less than 100 bacteria/ml were higher on days 1 and 3 (p = 0.05 and 0.02 respectively). Bacteriuria was significantly lower in rats inoculated with 10(7) bacteria and 10% D-mannose than in controls on days 5 and 7 (p less than 0.01 for each day) and the percentage of rats with less than 100 bacteria/ml was higher on day 7 (p = 0.01). D-glucose reduced bacteriuria significantly only with a concentration of 10% after instillation of 10(5) E. coli (p less than 0.05, day 1). The results indicate that D-mannose and D-glucose can significantly reduce bacteriuria within 1 day and that their efficacy is dependent upon the concentration of both saccharide and bacteria.

Ventral bladder hernia facilitates study of urinary tract infections in rats

Previous studies have demonstrated that after intravesical inoculation of Escherichia coli, rats drinking 5% glucose-water remained bacteriuric for up to 21 days while rats drinking tap water became abacteriuric within a few days. To facilitate accurate monitoring of bacteriuria, we created a ventral bladder hernia for percutaneous aspiration of urine. After intravesical inoculation with 10(8) E. coli, rats with ventral bladder hernias demonstrated clearance of bacteria at a rate comparable to that observed in rats with intrapelvic bladders (p less than 0.01). Of rats drinking tap water, 6 of 7 (85%) with intrapelvic bladders and 8 of 9 (89%) with ventral hernias had less than 10 colony forming units per ml of urine within 9 days of inoculation. Of rats drinking 5% glucose-water, 4 of 5 (80%) with intrapelvic bladders and 6 of 8 (75%) with ventral bladder hernias had greater than 10(5) colony forming units per ml of urine 9 days after inoculation. The results suggest that this technique does not alter the antibacterial response of control or polyuric rats to E. coli inoculated intravesically.