Biomedical subjects

D L Gentle

Publications and source records attributed to D L Gentle.

9 recordsLinked to original sources

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↗

PubMed1997

Geriatric urolithiasis.

PURPOSE: We define the differences between geriatric patients with urinary stone disease compared to a younger cohort. MATERIALS AND METHODS: A data base, including serum biochemical profiles, 24-hour urinalyses and standardized questionnaires, was retrospectively evaluated from more than 6,000 consecutive patients with urinary stone disease. RESULTS: Geriatric stone formers comprised 12% (721) of all stone patients. Two-thirds of these elderly patients had aberrant urinary values and 29% had isolated hypocitraturia compared to 17% in the younger group. Of geriatric stone forming patients 76% had recurrent urinary stones (mean 3.5 stone episodes), which was similar to the younger comparable group (77%, mean 3.3 stone episodes). The severity of urinary stone disease was similar between the 2 groups based on the need for urological intervention. Geriatric stone patients, in general, experienced the first stone episode later in life (after age 50 years) compared with younger patients. Elderly patients had an increased incidence of uric acid stones, but had a similar incidence of struvite calculi. Geriatric stone patients underwent parathyroid surgery more frequently (2.7 versus 0.7%). Geriatric stone forming patients rarely had renal failure. CONCLUSIONS: The incidence, recurrence and severity of recurrent urinary stone disease were similar between geriatric and younger stone forming patients. Geriatric stone patients had an increased incidence of isolated hypocitraturia, uric acid calculi and previous parathyroidectomy. The geriatric stone population is not merely an extension of younger stone forming patients presenting at an older age. Rather, geriatric patients commonly experience the first symptomatic stone episode later in life.

Age Distribution↗

PubMed1997

Protease inhibitor-induced urolithiasis.

OBJECTIVES: To describe protease inhibitor-induced urinary stone disease in patients with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) who are taking indinavir sulfate (Crixivan), a protease inhibitor, for the treatment of AIDS. METHODS: Patients with HIV/AIDS and symptomatic renal colic temporally related to the initiation of indinavir sulfate therapy were prospectively identified. Seven patients (mean age 42 years; all men) with HIV and renal colic who were taking indinavir were identified. Retrospective chart reviews and patient interviews were performed. RESULTS: Indinavir therapy averaged 5.7 months prior to presentation with renal colic. All patients had microscopic hematuria. One patient presented with acute azotemia from bilateral urinary obstruction. Six patients had no history of urinary stones prior to initiating indinavir. The median number of symptomatic urinary stone episodes after initiating indinavir was two stones per patient. All patients had moderate- to high-grade urinary obstruction from radiolucent calculi. Abdominal computed tomography (CT) demonstrated hydronephrosis without urinary calcifications. Three patients spontaneously passed stones and 4 required intervention. Yellow debris and/or brown matrix-like material was seen endoscopically. Stone analysis revealed pure protease inhibitor. Six patients (86%) eventually discontinued protease inhibitor therapy. CONCLUSIONS: Protease inhibitor-induced urinary stones are radiolucent and can cause high-grade ureteral obstruction. Protease inhibitor-induced urinary stones were not identified on unenhanced abdominal CT scans. The radiolucent gelatinous nature of such stones makes lithotripsy a poor choice of treatment. Ureteral stenting may allow spontaneous stone passage if symptomatic obstruction occurs. Urologists may encounter a greater number of patients with symptomatic protease inhibitor-induced urinary calculi as these medications become more popular.

Adult↗

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

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

Renal cortical neoplasm in a child with dialysis-acquired cystic kidney disease.

Acquired cystic disease of the kidney is a common phenomenon in long-term adult dialysis patients with endstage renal disease. Malignant degeneration with cortical neoplasms is also well documented in this patient population. Although the prevalence of this disease process is common in adults, the literature is sparse concerning its occurrence in children. To our knowledge, we report the youngest case of renal cortical neoplasm associated with dialysis-acquired renal cystic disease in a 13-year-old boy.

Adolescent↗

PubMed1996

Use of neodymium: yttrium-aluminum-garnet laser for removal of a congenital posterior urethral polyp in a 3-year-old child: a case report and review of the literature.

Congenital posterior urethral polyps are an uncommon but well-described disease process known to cause hematuria or bladder outlet obstruction in boys. Conventional treatment has included transurethral resection or open cystotomy for complete removal of the polyp. We report the first use of the neodymium:yttrium-aluminum-garnet laser for endoscopic excision of a posterior urethral polyp in a 3-year-old boy.

Child, Preschool↗

PubMed1996

Mini-laparotomy pelvic lymph node dissection minimizes morbidity, hospitalization and cost of pelvic lymph node dissection.

PURPOSE: We compared efficacy, morbidity and cost of mini-laparotomy pelvic lymph node dissection and laparoscopic pelvic lymph node dissection. MATERIALS AND METHODS: A total of 40 patients underwent mini-laparatomy, laparoscopic or standard pelvic lymph node dissection during a 24-month period. Nodal yield, complications, hospitalization and postoperative analgesic requirements were retrospectively evaluated. Operative expenses and the cost of postoperative hospitalization were standardized to a base cost for comparison. RESULTS: Mini-laparotomy pelvic lymph node dissection has an operative time (90 minutes) and nodal yield (9) similar to those of standard pelvic lymph node dissection, and morbidity and postoperative hospitalization (1.3 days) are comparable to those of laparoscopic pelvic lymph node dissection. The expense of the mini-laparotomy procedure is approximately 50% that of the laparoscopic procedure due primarily to the prolonged operative time (190 minutes) and disposable instrument costs ($665) of laparoscopic pelvic lymph node dissection. CONCLUSIONS: Mini-laparotomy pelvic lymph node dissection competes successfully with laparoscopic pelvic lymph node dissection in terms of efficacy and morbidity at significant cost savings.

Aged↗

PubMed1989

Evaluation of a Bayesian method for predicting vancomycin dosing.

The purpose of this study is to evaluate the performance of a vancomycin dosing program in predicting dosages necessary to achieve desired serum vancomycin concentrations in a relatively large patient population. With the completion of initial performance evaluation, revised pharmacokinetic parameter estimates derived in the initial evaluation are used to reevaluate program performance. The program uses population estimates of vancomycin's volume of distribution (Vd) and clearance (Cl) to initially predict dosing, then individualizes those estimates by a Bayesian algorithm (iterations) which uses dosing and the resulting serum vancomycin concentration data. Use of the Bayesian forecaster with one iteration significantly increases the calculated Cl value as compared with population estimates; two and three iterations significantly increase both Vd and Cl when compared with population estimates. Absolute values of the predicted minus observed peak serum vancomycin concentrations (accuracy) are 17.7 +/- 14.0, 6.1 +/- 3.6, and 3.4 +/- 2.1 mg/L for dosing using population estimates, Bayesian with one iteration, and Bayesian with two iterations, respectively. Similarly, accuracy of predictions for trough concentrations is 13.8 +/- 12.4, 3.5 +/- 3.2, and 3.2 +/- 2.6 mg/L for each method, respectively. Bias of dosing predictions in achieving desired peak and trough serum vancomycin concentrations is also significantly reduced by using the Bayesian algorithm. Use of the mean Vd and Cl values from three iterations as the starting parameters in a new group of 12 patients significantly improves program performance when compared with use of initial population parameters. Time of sampling for peak serum concentrations has no effect on program performance. In patients with impaired renal function, use of population estimates resulted in less accurate dosing prediction, but this less accurate performance was not observed with use of the Bayesian forecaster. These data demonstrate the accuracy and lack of bias in individualized dosing predictions using the Bayesian dosing method and the ability of revised pharmacokinetic parameter estimates to improve performance.

Bacterial Infections↗