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Biomedical subjects

B F Schwartz

Publications and source records attributed to B F Schwartz.

At least 19 recordsLinked to original sources
PubMed2005

Laparoscopic renal cryotherapy: biology, techniques and outcomes.

AIM: The development of minimally invasive approaches to renal cell carcinoma (RCC) over the last 10 years has given rise to newer therapies such as renal cryotherapy. Patients with significant comorbidities who are not suitable for open surgery may be candidates for this procedure. Herein, we review the biology, techniques and outcomes of laparoscopic renal cryotherapy as performed at our institution. METHODS: We present our initial experience with laparoscopic cryotherapy for the treatment of small, peripheral renal lesions and provide a review of the literature. A retrospective review was performed on our first 25 patients treated with transperitoneal laparoscopic cryotherapy for small peripheral renal lesions by a single surgeon between 2002 and 2003. RESULTS: We treated 25 patients, average age of 65 years (range 32-83) with transperitoneal laparoscopic renal cryotherapy for small, enhancing, peripheral lesions suspicious for RCC. Mean pretreatment creatinine of 1.06 was unchanged after treatment. Mean tumor size was 2.4 cm (range 1.5-3.6 cm), with a mean EBL of 80 mL. Pathology revealed 72% RCC, 2 oncocytomas, one each arterio-nephrosclerosis, inflammatory tissue, focal-segmental glomerulosclerosis, angiomyolipoma and one normal tissue specimen. Average tumor grade was 2.3 (range 2-4). Mean hospital stay was 2.3 days (range 1-5). Three cases were converted to open. Two complications included transfusion and hydronephrosis, both managed conservatively. Mean follow-up is 16.2 months (range 6-36 months). There have been no recurrences to date despite a rigorous surveillance protocol. CONCLUSIONS: Renal cryotherapy is a viable option for nephron sparing surgery in small, peripheral, renal lesions. The procedure is well tolerated, may be considered in patients who are not good candidates for open surgical approaches, results in minimal morbidity, and has very encouraging treatment results. Close surveillance post-treatment is essential. Longer follow-up data will be necessary to establish the durability of laparoscopic renal cryotherapy.

Adult↗
PubMed2001

Treatment of refractory kidney transplant ureteral strictures using balloon cautery endoureterotomy.

OBJECTIVES: To report our long-term clinical results with the use of endoureterotomy in patients undergoing renal transplant with a minimum follow-up of 23 months. METHODS: Six renal transplant patients developed persistent ureteral obstruction demonstrated by elevated serum creatinine levels, renal ultrasound, and antegrade pyelography. Stent placement and balloon dilation were performed as the initial therapy in all patients. Persistent ureteral obstruction was managed with balloon cautery endoureterotomy. Ureteral stents were removed cystoscopically 6 weeks after the procedure. RESULTS: Four men and 2 women, mean age 45 years (range 38 to 54), underwent eight procedures: six by way of an antegrade percutaneous approach and two in an endoscopic retrograde fashion. The sites of ureteral stricture were ureterovesical junction (n = 4), ureteropelvic junction (n = 1), and midureteroureteral (n = 1). Two patients required a second endoureterotomy 3 months after the first attempt. Patients were followed up for a mean of 27 months (range 23 to 34). The mean serum creatinine level for all patients at follow-up was 2.6 mg/dL (range 1.6 to 3.9), including a mean serum creatinine level of 1.8 mg/dL (range 1.6 to 1.9) for nonrejected kidneys and a mean of 3.4 mg/dL (range 2.5 to 3.9) in those found to have concurrent rejection. Overall, five (63%) of eight procedures were successful in 5 (83%) of 6 patients. No intraoperative complications occurred and no blood transfusions were required. CONCLUSIONS: Balloon cautery endoureterotomy was successful in this select group of renal transplant patients with persistent ureteral strictures after initial balloon dilation and stenting failed. This modality proved durable to 27 months of follow-up without significant complications.

Adult↗
PubMed2001

Radially expanding single-step nephrostomy tract dilator.

OBJECTIVES: To compare the radial and axial forces produced by balloon, Amplatz, and radially expanding single-step nephrostomy (RESN) systems and report our initial clinical results using the new RESN device. Balloon, Amplatz, and Alken dilators are commonly used to establish nephrostomy tracts in percutaneous surgery. They require multiple steps, with the potential for kinking and displacement of the working guidewire. In contrast, the new RESN tract dilator expands a unique sleeve conduit and places an Amplatz-like sheath in a single step with less dependence on a guidewire for dilation. METHODS: An experimental model was designed using a perforated silicon disc with a 10F central opening to measure the axial force transmission as 30F balloon, Amplatz, and RESN systems were inserted through the silicon discs. We also report our first 9 patients who underwent percutaneous dilation with the RESN system. RESULTS: Thirty French expansion was achieved with each dilator tested. Substantially lower axial forces were transmitted with the RESN device compared with the balloon and Amplatz dilators (5.2 versus 13.1 and 19.2 lb, respectively, P <0.001). Intraoperatively, all 9 patients were successfully dilated, and the kidney was relatively stationary as imaged with fluoroscopy. One patient with multiple prior renal procedures was successfully dilated with RESN system after failed attempts with balloon dilation. CONCLUSIONS: The RESN dilator is a rapid, single-step access system successfully used in our first 9 patients. Intraluminal sleeve dilation eliminates guidewire dependence for maintaining access, limits renal displacement, and facilitates appropriate vector force for percutaneous dilation.

Dilatation↗
PubMed2001

Rethinking the role of urinary magnesium in calcium urolithiasis.

BACKGROUND AND PURPOSE: The role of magnesium in urinary stone formation remains undefined. In vivo, magnesium inhibits stone formation in hyperoxaluric rats, and small clinical studies suggest a protective effect of magnesium supplementation in calcium oxalate stone formers. We performed a retrospective review of more than 7,000 stone patients to see if there is a relation between urinary magnesium and other stone risk variable constituents. MATERIALS AND METHODS: A national database of stone formers categorized by residential ZIP code was queried, and, using strict inclusion criteria, 2,147 patients having pure calcium oxalate stones were identified. There were 1,912 (89%) eumagnesuric (43-246 mg/24 hours) and 235 (11%) hypomagnesuric (<43 mg/24 hours) patients. RESULTS: Patients with decreased urinary magnesium excretion had significantly less daily urine excretion of citrate, calcium, oxalate, uric acid, and sodium than the eumagnesuric group (p < 0.0001). Stone recurrence was slightly more common in the hypomagnesuric group, although the difference was not statistically significant. The percentage of patients voiding <1 L of urine per day was significantly higher in the hypomagnesuric group. In the eumagnesuric group, males outnumbered females 2:1, whereas hypomagnesuric patients showed a female predominance of 1.4:1. CONCLUSION: The beneficial effects of urinary magnesium on stone formation may be less than previously reported. The role of oral magnesium supplementation and the subsequent increase in urinary magnesium in calcium urinary stone formation remains unknown. Our data suggest that its effect on or interaction with citrate may be influential on urinary citrate concentrations. If magnesium has a protective effect, it may work through pathways that enhance citrate excretion.

Calcium Oxalate↗
PubMed2000

Diagnosis of prostate adenocarcinoma using transurethral resection of the prostate after multiple negative transrectal biopsies and persistently elevated prostate-specific antigen level.

We report a case of prostate cancer diagnosis by transurethral resection of the prostate in a man who underwent more than 50 needle biopsies by three different physicians for an increasing prostate-specific antigen level. Radical prostatectomy resulted in removal of an organ-confined tumor (T2aN0M0), and a short follow-up revealed an undetectable prostate-specific antigen level.

Adenocarcinoma↗
PubMed2000

Gahat: a Napalese cure for urolithiasis?

OBJECTIVES: Gahat (Vigna unguiculata) is a legume used for centuries in Nepal and Pakistan to treat the symptoms associated with urinary calculi. We prospectively evaluated the effect of Gahat consumption on 24-hour urine parameters in an attempt to assess its in vivo effect in normal volunteers. METHODS: Eight non-stone-forming volunteers collected 24-hour urine specimens while on their routine diets for baseline data. Urine was analyzed for pH, volume, calcium, citrate, phosphate, sodium, magnesium, uric acid, and oxalate. The Gahat was prepared according to local custom. No additives were used to enhance flavor. The pureed mixture (8 ounces) was ingested three times daily for 2 days. Subjects were instructed to maintain their normal diet, including fluid intake and activity during the study period. Twenty-four hours after the start of Gahat intake, a second 24-hour urine collection was initiated while volunteers continued the Gahat. Results of the urine samples before and after Gahat intake were analyzed, using the paired Student t test. RESULTS: There were no significant differences in urinary electrolytes between the urine samples before and after Gahat intake. Magnesium, urine volume, and uric acid differences approached clinical significance. CONCLUSIONS: Gahat increased urinary magnesium through an unknown mechanism and had no effect on other routine 24-hour urine electrolytes. The increase in urinary volume is attributed to the increase in fluid consumption by the subjects. If this legume is effective in preventing or dissolving urinary calculi, it may act through mechanisms not identified in 24-hour urine electrolytes.

Citrates↗
PubMed2000

Impact of body weight on urinary electrolytes in urinary stone formers.

OBJECTIVES: Obesity increases the risk of developing chronic medical conditions such as diabetes mellitus, hypertension, and coronary artery disease. We performed a retrospective review of a large data base on urinary stones to determine if differences are found in urine and serum chemistries among obese and nonobese stone-forming patients. The effect of body weight on stone recurrence among urinary stone formers was also determined. METHODS: A national data base containing serum biochemical profiles, 24-hour urine specimens, and standardized questionnaires was retrospectively evaluated from 5942 consecutive patients with urinary stone disease. Stone-forming patients were classified by body weight: nonobese men, less than 100 kg and nonobese women, less than 85 kg; intermediate men, 100 to 120 kg and intermediate women, 85 to 100 kg; and obese men, more than 120 kg and obese women, more than 100 kg. RESULTS: Obese stone formers comprised 6.8% (n = 404) of the patient population. The mean weight in the nonobese and obese groups was 81 kg versus 134 kg, respectively, for men and 64 kg versus 112 kg, respectively, for women. Obese patients represented 3.8% of the male and 12.6% of the female population. Obese patients had increased urinary excretion of sodium, calcium, magnesium, citrate, sulfate, phosphate, oxalate, uric acid, and cystine; obesity was associated with increased urinary volumes and urine osmolality compared with the nonobese patients. Obese men had increased concentration of urinary sodium, oxalate, uric acid, sulfate, and phosphate when corrected for urinary volume. Obese women had increased concentrations of sodium, uric acid, sulfate, phosphate, and cystine. The mean number of stone episodes in nonobese versus obese men was similar (3.55 and 3.56), whereas mean stone episodes were 2.93 and 3.38 (P = 0.045) for nonobese versus obese women. CONCLUSIONS: Among known stone formers, obesity is associated with unique changes in both serum and urinary chemistries. These changes are associated with an increased incidence of urinary stone episodes in obese women but not in obese men.

Adolescent↗
PubMed2000

Percutaneous management of caliceal diverticula.

The diagnosis of a caliceal diverticulum may be serendipitous or established owing to patient symptoms. Once the decision to treat a diverticulum has been made, a percutaneous approach should be considered. If stones are present, complete stone removal and obliteration of the diverticulum should be the goals of surgery. The authors prefer the direct puncture technique whenever possible to limit the risk for bleeding and to facilitate stone removal. Use of a percutaneous approach in properly selected patients affords high success rates and results in few complications.

Catheterization↗
PubMed2000

The vesical calculus.

Bladder calculi account for 5% of urinary calculi and usually occur because of foreign bodies, obstruction, or infection. Males with prostate disease or previous prostate surgery and women who undergo anti-incontinence surgery are at higher risk for developing bladder calculi. Patients with SCI with indwelling Foley catheters are at high risk for developing stones. There appears to be a significant association between bladder calculi and the formation of malignant bladder tumors in these patients. Transplant recipients are not at increased risk for developing vesical calculi in the absence of intravesical suture fragments and other foreign bodies. Patients who undergo bladder-augmentation procedures using a vascularized gastric patch appear to be protected from vesicolithiasis, perhaps by the acidic environment. Ileum and colon tissues, however, are colonized by urease-producing organisms, producing an alkaline pH that promotes stone formation. Children remain at high risk for bladder-stone development in endemic areas. Diet, voiding dysfunction, and uncorrected anatomic abnormalities, such as posterior urethral valves and vesicoureteral reflux, predispose them to bladder-calculus formation. Finally, there are a number of techniques and modalities available to remove bladder stones. Relieving obstruction, eliminating infection, meticulous surgical technique, and accurate diagnosis are essential in their treatment.

Adult↗
PubMed2000

An in vitro assessment of the flow characteristics of spiral-ridged and smooth-walled JJ ureteric stents.

OBJECTIVE: To assess drainage through spiral-ridged and smooth-walled JJ ureteric stents (designed to ensure upper tract drainage) and thus determine whether drainage preferentially occurs around rather than through the spiral-ridged stent, promoting renal flow and potentially facilitating the passage of urinary stone fragments. Materials and methods A mechanical ureteric model was constructed to mimic the funnel characteristics of the renal pelvis. A motor pump was used to help simulate respiratory and skeletal movement, resulting in differential motion between the intraluminal stent and the surrounding ureteric wall. Tubes of varying internal diameters were used to simulate different sizes of ureter. Flow rates of standard 7 F smooth-walled stents were compared with 7 F spiral-ridged stents with and without occluded lumens, and with and without standardized excursions. RESULTS: Extraluminal flow (mean rates) with and without movements simulating respiratory excursions were significantly higher with the spiral stent for all stent diameters evaluated. All flow rates increased as the ureteric diameter increased. Total flow past the spiral stent was significantly greater than flow with the smooth-walled stent under all conditions tested. Flows measured around the spiral stent under conditions of excursion were the highest of all categories, 20-fold higher than in smooth-walled, closed, stationary stents. CONCLUSION: Spiral-ridged JJ stents provided substantially greater flow in this in vitro model. Extraluminal flow was markedly increased with the spiral-ridged configuration. The difference in flow rates was more pronounced at the smaller pseudo-ureteric tube diameters, simulating dimensions found in clinical practice. The flow rate also was increased when the central lumen remained open, and was greater still when there was dynamic excursion with respiratory movements.

Humans↗
PubMed2000

Endourologic management of urinary fistulae.

PURPOSE: Historically, aggressive surgical exploration of renal fistulae has been associated with a 20% nephrectomy rate. We evaluated the role of minimally invasive techniques in the management of urinary fistulae. MATERIALS AND METHODS: A retrospective review identified 10 renal fistulae in nine patients. Six renal-cutaneous, two renal-colonic, and two renal-pleural fistulae were referred for evaluation and treatment. RESULTS: Five men and four women (mean age 54 years, range 32-76) were referred to the University of California, San Francisco Urinary Stone Center from 1988 to 1996. Of the six renal-cutaneous fistulae, four were spontaneous and two were iatrogenic. The iatrogenic fistulae occurred after an open pyelolithotomy (1) and a renal exploration performed after extracorporeal shock wave lithotripsy (1). The spontaneous fistulae resulted from obstructing calyceal calculi (2), infundibular stenosis (1), and obstructed nephrostomy tube (1). The two renal-colonic fistulae resulted from percutaneous nephrolithotomies, and the two renal-pleural fistulae developed after renal surgery. Eight of 10 fistulae resolved with minimally invasive endoscopic techniques and relief of urinary obstruction. One nephrectomy was performed for a small nonfunctioning kidney after failed open pyelolithotomy. One patient refused all treatment and the fistula resolved spontaneously. CONCLUSIONS: Conservative management of both spontaneous and iatrogenic renal fistulae is possible by relieving urinary obstruction and using minimally invasive endoscopic techniques. Low nephrectomy rates can be expected using these methods.

Adult↗
PubMed1999

Autologous blood use in percutaneous nephrolithotomy.

OBJECTIVES: Preoperative autologous blood (AUB) donation has decreased patient exposure to allogenic blood (ALB) products and associated infectious risk. The risk of contracting hepatitis C and human immunodeficiency virus is 1 in 103,000 and 1 in 678,000, respectively, after receiving 1 U ALB. Elective surgical procedures require surgeons to offer preoperative AUB donation in California. Unused AUB is discarded. We report our use of AUB obtained for percutaneous nephrolithotomy. METHODS: A retrospective study of 144 consecutive patients who underwent 193 percutaneous nephrolithotomies between January 1994 and April 1998 at one of four teaching hospitals at the University of California, San Francisco was performed. Preoperative AUB donation, transfusion rates, hemoglobin levels, blood use, and costs were analyzed. RESULTS: Ninety-six units of blood were collected from 63 patients (44%) and were available for 70 procedures (36%). The overall transfusion rate per procedure was 7%, with 13 patients receiving a total of 24 U, 7 AUB and 17 ALB. Eighty-nine units (92.7%) of AUB were discarded, and the transfusion rate in donors and nondonors was similar. There was no significant difference in preoperative hemoglobin or operative blood loss between donors and nondonors. The 13 transfused patients had a lower preoperative hemoglobin ( 11.5 versus 12.8 g/dL; P = 0.029) and higher operative blood loss as measured by hemoglobin level (3.2 versus 1.6 g/dL; P <0.001). Blood bank charges for ALB and AUB were $ 119/U and $244 to $498/U, respectively, depending on transportation and thawing charges. CONCLUSIONS: Routine preoperative blood donation adds substantial cost for minimal benefit, given the low infectious risk of ALB and the two- to fourfold higher cost of AUB. In our series, women had an increased incidence of blood transfusion compared with men. AUB donation may provide peace of mind but is rarely used and is discarded 93% of the time.

Adolescent↗
PubMed1999

Nonsurgical management of infection-related renal calculi.

Struvite calculi can be a debilitating affliction for which the cure is mainly surgical. If left untreated, infection-related calculi can cause failure to thrive, anemia, chronic renal insufficiency, renal failure and death. There has been much research aimed at non-surgical intervention and prevention of these calculi especially in this "non-invasive" era. The historic and current non-surgical treatment modalities of struvite calculi are discussed.

Humans↗
PubMed1999

The effect of colonoscopy on serum prostate specific antigen levels.

OBJECTIVE: To evaluate, in a prospective trial, the effect of colonoscopy on serum prostate specific antigen (PSA) levels (which are known to increase after cystoscopy and prostatic needle biopsy) in men aged 50-70 years, as they commonly undergo colonoscopy and PSA screening together. SUBJECTS AND METHODS: Twenty-four consecutive men (mean age 61 years, range 37-78) were enrolled in the study. All subjects had their serum PSA measured 24-72 h before undergoing colonoscopy. Further values were obtained 24 h, 7 and 30 days after the procedure. The values before and after colonoscopy were compared to evaluate the effect of colonoscopy on serum PSA levels. RESULTS: Of 24 patients, seven (35%) had insignificant increases at 24 h after colonoscopy; 12 (50%) patients had an insignificant increase in PSA level 30 days after the procedure. None of the 24 patients had a significant increase after colonoscopy when compared with baseline values. CONCLUSION: Flexible colonoscopy does not adversely affect serum PSA levels. Although individuals may have a 30% daily fluctuation in serum values, this study detected no significant change in serum PSA levels after prolonged transrectal prostatic manipulation with a colonoscope.

Adult↗