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Biomedical subjects

M L Stoller

Publications and source records attributed to M L Stoller.

At least 55 records · Page 3Linked to original sources
PubMed1997

Uric acid-related nephrolithiasis.

Abnormalities in uric acid metabolism are associated with uric acid and calcium oxalate urolithiasis. Clinical stone formation depends on multiple identifiable risk factors that affect uric acid and calcium oxalate solubility. The understanding of urinary pH is critical to direct appropriate treatment of uric acid-related nephrolithiasis. Understanding uric acid metabolism and the pathophysiology of uric acid and calcium oxalate stone formation leads to a rational treatment approach to uric acid and hyperuricosuric calcium oxalate stone disease.

Calcium↗
PubMed1997

Acalculous cystinuria.

We compared quantitative urinary cystine values in stone-forming family members and unaffected relatives based on an index stone-forming patient. A family pedigree of 39 members was identified. Quantitative urinalyses and serum biochemical profiles were collected with the subjects on similar diets over 72 hours. Detailed medical histories were obtained. Three family members are stone-forming cystinuric patients with a mean urinary cystine excretion of 496 mg/g of creatinine per day. Six persons without a history of stones (mean age 50) had a mean urinary cystine excretion of 364 mg/g of creatinine per day. Thirty-four family members had elevated urinary cystine concentrations (mean 151 mg/g of creatinine per day), and only two family members had normal urinary cystine excretion. Fifteen subjects with elevated urinary cystine values (> 150 mg/g of creatinine per day) had no history of urinary stones despite a mean age of 44 years. Urinary electrolytes and volumes were similar in the stone-forming and non-stone-forming groups. Thirty-nine per cent of the persons from this family pedigree had elevated quantitative urinary cystine concentrations and no history of urinary stones despite a mean age of 44 years. Acalculous cystinuria is an elevated urinary cystine concentration without evidence of urinary stone disease. Despite abnormal urinary cystine excretion, acalculous cystinuria does not necessarily culminate in clinical urinary stone disease.

Adolescent↗
PubMed1997

Urinary stone disease: a practical guide to metabolic evaluation.

Urolithiasis is the third most common affliction of the urinary tract, after infections and diseases of the prostate. Approximately 10% of the North American population will have at least one urinary calculus by age 70. A thorough history and physical examination will usually confirm the diagnosis of urinary stone disease. A simplified laboratory evaluation may be performed for patients with a single stone episode. A more extensive evaluation is required for patients with recurrent, metabolically active stones and patients at high risk (ie, cystine stone formers and those who develop bladder dysfunction or nephrosclerosis). Intravenous pyelography with tomography remains the gold standard for imaging of the urinary tract to confirm the diagnosis and formulate a treatment plan.

Colic↗
PubMed1997

Endoscopic management of upper tract urothelial tumors.

We evaluated renal-preserving endourology in the diagnosis and management of upper tract urothelial tumors. Referral patients were identified for the endourologic management of upper urinary tract tumors between January 1990 and May 1996 at two tertiary care referral centers. Chart reviews, indications for intervention, and treatment outcomes were assessed. Twenty patients (mean age 66 years; range 32-89; males 14; females 6) underwent endourologic diagnosis and/or management of upper tract urothelial neoplasms. Mean follow-up was 25 months. The diagnosis of transitional cell carcinoma (TCC) was endoscopically confirmed in all cases. Twenty-one biopsies were performed for pathological diagnoses; one identified pathological muscle that assisted in clinical staging. Percutaneous approaches were required in four patients (six kidneys) as a result of inadequate retrograde access or excessive tumor burden. Four (44%) renal pelvic tumors recurred after long-term follow-up; ureteral recurrences occurred in 4 (80%) of 5 patients. Open surgery was required in six patients for excessive tumor burden/concurrent muscle invasive bladder tumors. No endoscopically managed patient developed metastatic disease. No patient died as a result of TCC. Endourologic biopsies are small, yet sufficient for pathological diagnoses of upper tract tumors; most biopsies lack muscle to evaluate staging. Recurrent upper tract tumors are common and may require multiple staged endoscopic interventions. Successful endoscopic management of upper urinary tract neoplasms is primarily related to tumor burden and pathological grade. Minimally invasive endourologic management of upper tract tumors should be considered in select patients. Open surgical management does not equate with failure.

Adult↗
PubMed1996

High resolution radiography of cadaveric kidneys: unraveling the mystery of Randall's plaque formation.

PURPOSE: We used high resolution radiography to identify and characterize Randall's plaques in cadaveric kidneys. MATERIALS AND METHODS: A total of 50 consecutive sets of cadaveric kidneys was fixed, bivalved and imaged with micro-focal spot magnification radiography. Papillary calcifications were identified, localized and processed for light microscopy. Special immunohistochemical stains were implemented to aid localization of ectopic calcifications. Patient medical records and autopsy results were retrospectively evaluated and correlated with radiographic papillary calcifications. RESULTS: Of the 92 renal units with complete data 52 (57%) had radiographic evidence of renal medullary calcifications consistent with Randall's plaques. Unlike the original description of this condition, calcifications extended deep into the papilla. A history of hypertension was the only clinical parameter correlating with papillary calcifications. Calcium deposition was localized to the basement membrane of collecting tubules and vasa recta, and papillary interstitium. CONCLUSIONS: Randall's plaques are not merely subepithelial deposits. Rather, they appear to extend deep within the papilla, and are intimately associated with collecting tubules and vasa recta. An association between papillary calcifications and urinary stone formation has yet to be proved but is under investigation.

Cadaver↗
PubMed1996

Outcome assessment of double-J stents during extracorporeal shockwave lithotripsy of small solitary renal calculi.

The utility of indwelling double-J ureteral stents during extracorporeal shockwave lithotripsy (SWL) of renal calculi is ill defined. We evaluated 179 patients treated with SWL for small (< 20 mm in diameter) solitary renal calculi with (N = 27) or without (N = 152) indwelling ureteral stents. There was no significant difference in the stone-free rates at 1 month (both 52%) and 3 months (61% nonstented group v 67% stented group; P = 0.45) or in the retreatment rates (13.3% nonstented group v 14.8% stented group; P = 0.60). The incidence and severity of pain/renal colic were similar for the two treatment groups. There was minimal morbidity associated with SWL in either group. Placement of double-J stents for the purpose of improving stone-free rates, alleviating pain, or preventing ureteral obstruction in conjunction with SWL of solitary renal calculi < 20 mm in diameter is unnecessary.

Evaluation Studies as Topic↗
PubMed1996

Efficacy of retrograde endopyelotomy in children.

PURPOSE: Endopyelotomy has been performed extensively in adults for the treatment of ureteropelvic junction obstruction. To determine its applicability to the pediatric population we reviewed our experience with retrograde endopyelotomy in children. MATERIALS AND METHODS: Eight children 4 to 15 years old were treated with retrograde endopyelotomy and results were compared to those of a concurrent group of 8 treated with open pyeloureteroplasty. RESULTS: Retrograde endopyelotomy was done in all of our patients with lower ureteral dilatation (as an adjunct measure in 5). Seven patients had symptomatic and radiographic improvement. The patient in whom the procedure failed had a crossing lower pole vessel. Postoperative analgesia, length of hospitalization and cost were lower in the endopyelotomy group. CONCLUSIONS: Retrograde endopyelotomy is feasible in children older than age 4 years and it results in reduced morbidity. The success rate is high but open surgery remains the standard, particularly when a crossing lower pole vessel is identified preoperatively.

Adolescent↗
PubMed1996

The influence of diet on urinary stone disease.

PURPOSE: Conflicting data on the role of diet in the pathogenesis of nephrolithiasis prompted us to review the relevant literature regarding the impact of diet on urinary stone disease. MATERIALS AND METHODS: MEDLINE searches were obtained from 1966 to date using a variety of key words, including urolithiasis, nephrolithiasis, diet, protein, carbohydrate, fat, calcium, oxalate, phosphate, magnesium, sulfate, citrate, sodium, potassium, fiber, fluids, alcohol and vitamins. References earlier than 1966 were obtained through bibliographies of these MEDLINE searches. The search included in vitro and in vivo animal and human studies. RESULTS: Of the extracted articles 83% addressed the issue of nephrolithiasis and diet, and were included in this report. All articles were independently reviewed by each of us. The reviews were summarized and compiled according to each dietary component. CONCLUSIONS: Appropriate dietary manipulation may be beneficial in the prevention of recurrent urolithiasis in only a select group of patients.

Diet↗
PubMed1996

Effectiveness and safety of the Dornier compact lithotriptor: an evaluative multicenter study.

PURPOSE: We evaluated the efficacy and safety of the Dornier compact lithotriptor for management of renal stones. MATERIALS AND METHODS: We administered 191 treatments to 169 patients with renal stones on 176 occasions with the patient under combined parental sedation and analgesia. The Dornier Compact lithotriptor is mobile and ultrasound guided, and uses an electromagnetic energy source. RESULTS: A total of 22 patients required a second treatment (13%), 123 (72.8%) were stone-free, 26 (15.4%) had fragments less than 4 mm. large, 16 (9.5%) had stone fragments larger than 4 mm, and 4 (2.4%) required auxiliary therapy (treatment failures). The side effects were mostly mild to moderate, with nausea and/or vomiting reported in 26 patients (14%), colic or pain in 66 (39%), ureteral obstruction in 2, steinstrasse in 7 (4%) and fever in 1. Our clinical results indicate that extracorporeal shock wave lithotripsy was effective for treatment of stones in the kidney, with a low incidence of complications and adverse effects. The lithotriptor used is much smaller, less expensive and user friendly with no installation requirements, rendering it mobile. CONCLUSIONS: The success rate with newer generation devices compares well with results obtained using other stationary and larger versions.

Adult↗
PubMed1996

Dietary manipulation with lemonade to treat hypocitraturic calcium nephrolithiasis.

PURPOSE: Pharmacological treatment of hypocitraturic calcium nephrolithiasis requires as many as 12 tablets, or numerous crystal packages or liquid supplements taken throughout the day. In addition to added cost, this cumbersome regimen decreases patient compliance, which may increase stone recurrence rates. We evaluated the urinary biochemical effects of dietary citrate supplementation in hypocitraturic calcium stone formers in an attempt to decrease or eliminate the need for pharmacological therapy. MATERIALS AND METHODS: A total of 12 patients who were either noncompliant with or intolerant of pharmacological citrate therapy supplemented their routine diet with citrate in the form of lemonade, consisting of 4 ounces of reconstituted lemon juice (5.9 gm. citric acid) mixed with tap water to a total volume of 2 l. and consumed at uniform intervals throughout the day. Urine specimens (24-hour) were obtained for biochemical analysis after 6 days of lemonade therapy and compared to pre-lemonade baseline values. RESULTS: Of the 12 patients 11 had increased urinary citrate levels during lemonade therapy (average 204 mg. per day). Average levels increased from 142 mg. daily (range less than 10 to 293) at baseline to 346 mg. daily (range 89 to 814) after treatment (p < 0.001). Daily total urinary volumes were similar (2.7 versus 2.9 l.). Seven of 12 patients became normocitraturic while consuming lemonade. Urinary calcium excretion decreased an average of 39 mg. daily, while oxalate excretion was unchanged. The lemonade mixture was well tolerated. Two patients complained of mild indigestion that did not require cessation of therapy. CONCLUSIONS: Citrate supplementation with lemonade increased urinary citrate levels more than 2-fold without changing total urinary volume. Lemon juice, which contains nearly 5 times the concentration of citric acid compared to orange juice, is an inexpensive and well tolerated dietary source of citrate. Lemonade therapy may improve patient compliance, and may be useful as adjunctive treatment for patients with hypocitraturic calcium nephrolithiasis.

Beverages↗
PubMed1995

Current indications for open stone surgery in an endourology center.

OBJECTIVES: To evaluate the current indications and outcome of open stone surgery in a tertiary endourology unit. METHODS: A 3-year retrospective review (1990 to 1993) of all endoscopic and open stone surgery was undertaken. RESULTS: Twenty-five open procedures were performed on 20 patients of a total of 799 stone treatment procedures (3.13%). The most common indications for open stone surgery included large stone burdens in association with abnormal anatomy limiting endoscopic access (31%), concurrent open surgical procedures (24%), or previous failed endourologic procedures (17%). Anatomic factors contributing to the need for open surgery included renal transplantation, morbid obesity, and severe limb contractures. CONCLUSIONS: Open stone surgery has become more complex. Patients undergoing open surgery, who failed endourologic techniques, or for anatomic or medical reasons, currently are the cohorts who may still benefit from treatment for calculus disease using open surgical techniques.

Female↗
PubMed1995

Cost-effectiveness v patient preference in the choice of treatment for distal ureteral calculi: a literature-based decision analysis.

Ureteroscopy (URS) and extracorporeal shockwave lithotripsy (SWL) battle for supremacy in the management distal ureteral calculi. In order to clarify issues surrounding this controversy, we created a decision tree modeling URS or SWL with literature-based probabilities and used as endpoints both cost and patient preferences. Ureteroscopy was more successful than single-session or multiple-session SWL, 92.1% v 74.3% or 84.5%, and had a lower retreatment/complication rate. Although initial SWL was only slightly more expensive than URS, $4,420 v $4,337, the difference increased when the additional costs of complications and retreatment were calculated, $6,745 v $5,555. Using values for an "average" patient, SWL was preferred to URS in terms of patient satisfaction. The most important factors distinguishing between URS and SWL were the success of treatment, the cost of initial therapy, and patient attitudes toward unplanned ancillary procedures and retreatment. Although no alteration of success rates and cost figures within reasonable ranges made URS less cost-effective than SWL, individual differences in patients' aversion for complications allowed URS to be preferred to SWL in some situations. Therefore, SWL is less cost-effective than URS and is not necessarily preferred by patients. The physician should be aware of the principal determinants of the choice between URS and SWL treatment of distal ureteral calculi.

Cost-Benefit Analysis↗
PubMed1995

Sodium fluoride dissolution of human calcium oxalate/phosphate stone particles.

The dissolutive effects of sodium fluoride on human calcium stone particles were investigated in an in vitro model. Stone particles composed of 65% calcium oxalate and 35% calcium phosphate dissolved in a dose-dependent fashion with NaF exposure. Stone particles exposed to 60 mM NaF had a 17% reduction in particle mass after 24 hours and a 62% reduction after 7 days in comparison with experimental controls bathed in physiologic normal saline. The systemic toxicity of the dose of oral fluoride necessary to achieve the optimal tested urinary concentrations would likely preclude oral administration, but NaF may have an adjunctive role in upper urinary tract irrigation for residual stone fragments after lithotripsy or in chronic low-dose oral administration for prophylaxis against recurrent calcium nephrolithiasis.

Administration, Oral↗
PubMed1995

Intraperitoneal versus extraperitoneal insufflation of carbon dioxide as for laparoscopy.

In order to compare the effects of intraperitoneal and extraperitoneal insufflation of CO2, we obtained blood gas measurements and chest radiographs in dogs during insufflation into three sites: the peritoneal cavity alone, the retroperitoneal space with communication into the peritoneal cavity, and the retroperitoneal space alone. The blood pH fell a mean of 0.11 +/- 0.03 and the PaCO2 rose a mean of 16.0 +/- 3.7 mm Hg when insufflation included the peritoneal cavity, whereas when insufflation was limited to the retroperitoneum, the pH fell a mean of 0.05 +/- 0.03 and the PaCO2 rose a mean of 7.5 +/- 2.8 mm Hg. Extrapleural thoracic dissection of gas was noted in one animal after insufflation limited to the retroperitoneal space. These findings confirm that there is significant absorption of CO2 from the peritoneal cavity during laparoscopy with CO2 insufflation, whether the pneumoperitoneum is primary or occurs secondary to retroperitoneal insufflation. If the insufflated gas is limited to the retroperitoneal space, however, the absorption of CO2 appears to be reduced in this animal model. The risk of thoracic dissection of gas may be greater during extraperitoneal insufflation than during intraperitoneal insufflation.

Absorption↗
PubMed1995

Pseudo-crossed renal ectopia secondary to ureteropelvic junction obstruction.

To our knowledge we report the first case of pseudo-crossed renal ectopia without an apparent displacing retroperitoneal mass that was documented on sequential radiological studies. Ureteropelvic junction obstruction of the crossed kidney appeared to be the cause of pseudo-crossed renal ectopia. Our case is compared with previously described instances of pseudo-crossed renal ectopia and the pathophysiological basis of this condition is discussed.

Adult↗