Effects of urinary tract obstruction on renal function

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

Double pigtail ureteral stenting and renal pelvic lavage for renal-sparing treatment of obstructive pyonephrosis in dogs: 13 cases (2008-2012)

OBJECTIVE

To describe the technical aspects and clinical outcome of endoscopic- and fluoroscopic-guided ureteropelvic lavage and ureteral stent placement for treatment of obstructive pyonephrosis in dogs.

DESIGN

Retrospective case series.

ANIMALS

13 client-owned dogs (14 obstructed ureters).

PROCEDURES

All patients with obstructive pyonephrosis were treated with a ureteral stent. Medical records were reviewed for history, clinical signs, pre- and postprocedural clinical and imaging data, and short- and long-term outcomes.

RESULTS

13 dogs (14 ureters) had unilateral or bilateral ureteral obstructions and pyonephrosis due to ureterolithiasis (n = 13) or a suspected ureteral stricture (1). Eleven dogs had positive results of bacteriologic culture of urine obtained from the bladder, renal pelvis, or both. Ten were thrombocytopenic, and 8 were azotemic. Stents were placed fluoroscopically with endoscopic (n = 11) or surgical (3) assistance. Median hospitalization time was 48 hours (range, 6 to 260 hours). Median follow-up time was 480 days (range, 2 to 1,460 days). Intraoperative complications occurred in 2 patients (stent occlusion from shearing of a guide wire, and wire penetration of the ureter at the location of a stone). Short-term complications included a bladder hematoma (n = 1) and transient dysuria (1). Long-term complications included stent encrustation (n = 1), stent migration (1), and tissue proliferation at the ureterovesicular junction (5), which had no clinical implications. Recurrent urinary tract infections were documented in 7 dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Ureteral stenting was a successful renal-sparing treatment for obstructive pyonephrosis in dogs and could often be performed in a minimally invasive manner. There were few major complications. This technique may be considered as an effective treatment option for this condition in dogs.

A randomized comparison of cisplatin and oral vinorelbine as radiosensitizers in aged or comorbid locally advanced cervical cancer patients

OBJECTIVE

Chemoradiation with cisplatin is considered the standard of care for patients with locally advanced cervical cancer; however, cisplatin could be difficult to use in aged patients or patients with comorbidities such as diabetes mellitus and blood hypertension; hence, it is important to investigate nonplatinum drugs for radiosensitization. In addition, oral cytotoxics may overcome the drawbacks of intravenous infusions and could be of easier administration.

METHODS

In this small randomized trial, we tested cisplatin against oral vinorelbine as radiosensitizers in these patients. A total of 39 patients 65 years or older or diabetic and hypertensive patients of any age were randomized to cisplatin or oral vinorelbine at 40 mg/m² or 60 mg/m², respectively. Both drugs were administered weekly for 6 courses during pelvic external-beam radiotherapy and brachytherapy radiation. Efficacy and safety were assessed.

RESULTS

Nineteen patients received oral vinorelbine, and 20 patients received cisplatin. The median cumulative dose to point A was 80.8 Gy for both groups, and the overall treatment time was 48 (42-54) and 50 (43-55) days for vinorelbine and cisplatin groups, respectively. Patients in both arms received a median of 5 applications of chemotherapy. Treatment was well tolerated in both arms. The most frequent toxicity in both arms was lymphopenia grades 2 and 3. At a median follow-up time of 16 months (4-19), there were no differences in either progression-free survival or overall survival between groups.

CONCLUSIONS

Our results suggest that these patient populations can safely be treated with either cisplatin or navelbine as radiosensitizers; however, a larger randomized study is needed to demonstrate the noninferiority of oral vinorelbine as an easier and practical alternative for radiosensitization in cervical cancer.

Pharmacotherapy options for locally advanced and advanced cervical cancer

Cervical cancer continues to be a significant health burden worldwide. Globally, the majority of cancers are locally advanced at diagnosis; hence, radiation remains the most frequently used therapeutic modality. Currently, the value of adding cisplatin or cisplatin-based chemotherapy to radiation for the treatment of locally advanced cervical cancer is strongly supported by randomized studies and meta-analyses. Nevertheless, despite these significant achievements, therapeutic results are far from optimal; thus, novel therapies need to be investigated. A recent, randomized, phase III trial has shown for the first time that combination chemotherapy with cisplatin and gemcitabine concurrently with radiation improves parameters of survival over cisplatin alone and establishes a new standard for the management of locally advanced cervical cancer. On the other hand, advanced disease, presenting either as an International Federation of Gynecology and Obstetrics (FIGO) stage IVB or as persistent or recurrent to primary therapy without local curative options, remains a devastating group of diseases with no options other than palliative chemotherapy. Recent results from the GOG (Gynecologic and Oncologic Group)-204 study demonstrate that cisplatin-doublets with paclitaxel, vinorelbine, gemcitabine or topotecan only produce small improvements in survival, although with different toxicity patterns; hence, patient-related factors are important when choosing any one of these regimens. The role of targeted therapies both in locally advanced and advanced disease is promising, but still at an investigational stage.

Radiosensitizers in cervical cancer. Cisplatin and beyond

Cervical cancer continues to be a significant health burden worldwide. Globally, the majority of cancers are locally advanced at diagnosis; hence, radiation remains the most frequently used therapeutical modality. Currently, the value of adding cisplatin or cisplatin-based chemotherapy to radiation for treatment of locally advanced cervical cancer is strongly supported by randomized studies and meta-analyses. Nevertheless, despite these significant achievements, therapeutic results are far from optimal; thus, novel therapies need to be assayed. A strategy currently being investigated is the use of newer radiosensitizers alone or in combination with platinum compounds. In the present work, we present preclinical information on known and newer cytotoxic agents as radiosensitizers on cervical cancer models, as well as the clinical information emanating from early phase trials that incorporate them to the cervical cancer management. In addition, we present the perspectives on the combined approach of radiation therapy and molecular target-based drugs with proven radiosensitizing capacity.

A phase I study of carboplatin concurrent with radiation in FIGO stage IIIB cervix uteri carcinoma

PURPOSE

Chemoradiation based on cisplatin, most commonly weekly, is the standard treatment of locally advanced cervical cancer; however, the nephrotoxic potential and the requirement for hydration of cisplatin somewhat restrains its use. The objective of this study was to determine the recommended dose of carboplatin when administered weekly during pelvic radiation (RT).

METHODS AND MATERIALS

Twenty-four histologically proven, International Federation of Gynecology and Obstetrics Stage IIIB patients were treated with standard pelvic RT concurrently with six weekly applications of carboplatin at the following dose levels: 100 mg/m(2), 116 mg/m(2), 133 mg/m(2), and 150 mg/m(2). Six patients per level were treated. Acute toxicity was assessed according to the Radiation Therapy Oncology Group Acute Radiation Morbidity Scoring Criteria. The recommended dose was defined as the one that was one level below the level at which dose-limiting toxicity was present in more than one-third of patients.

RESULTS

Between September 2001 and July 2002, 24 patients were accrued. All but two completed external beam radiotherapy and intracavitary treatment. The treatment was well tolerated. The median number of weekly applications of carboplatin was six, and the mean dose to points A and B was 85.6 Gy (range 75.2-91.6) and 62.9 Gy (range 58.2-74.6), respectively. RT was delivered within 41.7 days (range 33-70). Dose-limiting toxicity (leukopenia and/or neutropenia) was present in 50% of patients treated at the higher dose level (150 mg/m(2)). At the recommended dose of 133 mg/m(2), 33% of patients presented with Grade 3 leukopenia. At treatment completion, 75% of patients had a complete clinical response.

CONCLUSION

Carboplatin at 133 mg/m(2), weekly for 6 weeks, is a well tolerated and effective radiosensitizer in cervical cancer patients.

Experimental partial ureteric obstruction in newborn rats. IV. Do the morphological effects progress continuously?

Partial obstruction of the ureter was created in newborn rats, and its effects were studied after 1, 2, 3, 6 and 9 weeks--that is, until adult age. Within 1 week, a considerable hydronephrosis had appeared. Within 2 weeks, parenchymal weight was found slightly reduced (8 per cent) on the obstructed side, and, within 3 weeks, equivalently increased on the contralateral, intact side. After these points in time, there was no further deterioration. Histological examination revealed marked deformation of the papilla and minor foci of degeneration and inflammation within 1 to 2 weeks which tended to become chronic in type after 3 to 9 weeks. Arterial hypertension was not noted. Thus, the effects of partial ureteric obstruction on the renal parenchyma are 1) discrete, 2) not in proportion to the degree of hydronephrosis, 3) fully compensated by contralateral hypertrophy and 4), after reaching an early maximum, not increasing with time.

Experimental obstructive hydronephrosis in newborn rats. III. Long-term effects on renal function

A partial obstruction of 1 ureter was created in newborn rats and its effects were studied in the adult rat. The obstructed pelvis was found to be considerably enlarged. Nevertheless, the GFR (glomerular filtration rate) was only slightly decreased (10 per cent), completely compensated by increase on the contralateral, non-obstructed side. The reduction in GFR was less than the reduction in number of glomeruli (19 per cent), indicating a raised filtration rate per glomerulus. Water excretion was slightly increased and potassium excretion moderately decreased; sodium and osmolar excretion were not significantly affected. There was no correlation between these changes and the degree of pelvic enlargement. Thus, in this model, in which there is no urinary tract infection or pyelonephritis, partial obstructive uropathy caused less damage to the kidney function than might have been expected.