Sparsentan versus Irbesartan in Focal Segmental Glomerulosclerosis

BACKGROUND

An unmet need exists for focal segmental glomerulosclerosis (FSGS) treatment. In an 8-week, phase 2 trial, sparsentan, a dual endothelin-angiotensin receptor antagonist, reduced proteinuria in patients with FSGS. The efficacy and safety of longer-term treatment with sparsentan for FSGS are unknown.

METHODS

In this phase 3 trial, we enrolled patients with FSGS (without known secondary causes) who were 8 to 75 years of age; patients were randomly assigned to receive sparsentan or irbesartan (active control) for 108 weeks. The surrogate efficacy end point assessed at the prespecified interim analysis at 36 weeks was the FSGS partial remission of proteinuria end point (defined as a urinary protein-to-creatinine ratio of ≤1.5 [with protein and creatinine both measured in grams] and a >40% reduction in the ratio from baseline). The primary efficacy end point was the estimated glomerular filtration rate (eGFR) slope at the time of the final analysis. The change in eGFR from baseline to 4 weeks after the end of treatment (week 112) was a secondary end point. Safety was also evaluated.

RESULTS

A total of 371 patients underwent randomization: 184 were assigned to receive sparsentan and 187 to receive irbesartan. At 36 weeks, the percentage of patients with partial remission of proteinuria was 42.0% in the sparsentan group and 26.0% in the irbesartan group (P = 0.009), a response that was sustained through 108 weeks. At the time of the final analysis at week 108, there were no significant between-group differences in the eGFR slope; the between-group difference in total slope (day 1 to week 108) was 0.3 ml per minute per 1.73 m2 of body-surface area per year (95% confidence interval [CI], -1.7 to 2.4), and the between-group difference in the slope from week 6 to week 108 (i.e., chronic slope) was 0.9 ml per minute per 1.73 m2 per year (95% CI, -1.3 to 3.0). The mean change in eGFR from baseline to week 112 was -10.4 ml per minute per 1.73 m2 with sparsentan and -12.1 ml per minute per 1.73 m2 with irbesartan (difference, 1.8 ml per minute per 1.73 m2; 95% CI, -1.4 to 4.9). Sparsentan and irbesartan had similar safety profiles, and the frequency of adverse events was similar in the two groups.

CONCLUSIONS

Among patients with FSGS, there were no significant between-group differences in eGFR slope at 108 weeks, despite a greater reduction in proteinuria with sparsentan than with irbesartan. (Funded by Travere Therapeutics; DUPLEX ClinicalTrials.gov number, NCT03493685.).

Uveitis intermedia as the initial presentation of a primary lymphoma of the central nervous system

Primary central nervous system lymphoma is one of the most infrequent brain tumours, accounting for 3% of primary central nervous system neoplasms. In addition to its low prevalence, clinical presentation is usually nonspecific, leading to diagnostic delay. Intraocular involvement occurs in 15% of cases, and disease onset in this location is even rarer. We present a case of a patient with intermediate uveitis as the first clinical manifestation of this neoplasm.

Early Response in Albuminuria and Long-Term Kidney Protection during Treatment with an Endothelin Receptor Antagonist: A Prespecified Analysis from the SONAR Trial

BACKGROUND

Whether early reduction in albuminuria with atrasentan treatment predicts its long-term kidney-protective effect is unknown.

METHODS

To assess the long-term effects on kidney outcomes of atrasentan versus placebo in the SONAR trial, we enrolled patients who had type 2 diabetes and CKD (stage 2-4) and a urinary albumin creatinine ratio (UACR) of 300-5000 mg/g; participants were receiving maximum tolerated renin-angiotensin system inhibition. After 6 weeks exposure to 0.75 mg/day atrasentan (enrichment period), participants were randomized (stratified by UACR response during enrichment, ranging from ≤60% to >0%) to continue atrasentan or transition to placebo. Primary kidney outcome was a composite of sustained serum creatinine doubling or ESKD.

RESULTS

UACR response to atrasentan during enrichment persisted throughout the double-blind treatment phase and predicted the primary kidney outcome, whereas UACR levels with placebo remained below pre-enrichment values in the two highest UACR response strata, and exceeded pre-enrichment values in the two lowest strata. As a result, early UACR response to atrasentan during enrichment was also associated with the primary kidney outcome during placebo. Accordingly, the predictive effect of early albuminuria changes during atrasentan was eliminated after placebo correction, leading to a consistent relative risk reduction for the primary kidney outcome with atrasentan compared with placebo, irrespective of the initial UACR response. The difference between atrasentan and placebo in UACR during double-blind treatment was also consistent across UACR response strata.

CONCLUSIONS

Our findings do not support UACR response as a causal predictor of atrasentan's treatment effect. However, the variable trajectory in UACR with placebo, aspects of the trial design, day-to-day variability in albuminuria, and potential long-lasting effects of atrasentan may have contributed.

MO230A PHASE 3, RANDOMIZED, DOUBLE-BLIND, PLACEBO CONTROLLED STUDY OF ATRASENTAN IN PATIENTS WITH IGA NEPHROPATHY (THE ALIGN STUDY)

Background and Aims

IgA nephropathy (IgAN) is the most common primary glomerulonephritis globally and an important cause of chronic kidney disease (CKD). Up to 40% of IgAN patients are at risk of progressing to end-stage kidney disease (ESKD) and proteinuria is the strongest predictor of progression. There are no approved therapies for IgAN, leaving an important need for new strategies to lower proteinuria and preserve kidney function in high-risk patients.

Endothelin A (ETA) receptor activation drives proteinuria, along with kidney inflammation and fibrosis. Atrasentan, a potent and selective ETA antagonist, has been studied extensively in >5,000 patients with type 2 diabetes and kidney disease (DKD), demonstrating clinically significant and sustained reductions in proteinuria when administered on top of a maximum tolerated dose of RAS inhibitor (RASi). In a global Phase 3 outcome study in DKD (SONAR), atrasentan demonstrated a 35% reduced risk of the primary composite outcome of doubling of serum creatinine or end stage kidney disease (95% CI: 0.49, 0.88; P = 0.005). The most common adverse event was fluid retention.

Selective ETA blockade represents a promising approach to reduce proteinuria and preserve kidney function in high risk IgAN patients.

This is a presentation of a global, phase 3, double-blind, placebo-controlled trial to determine the effect of atrasentan in IgAN patients at high risk of kidney function loss.

Method

Approximately 320 patients across North America, South America, Europe, and Asia-Pacific with biopsy-proven IgAN will be randomized to receive 0.75 mg atrasentan or placebo daily for 132 weeks. Patients will continue receiving a maximally tolerated and stable dose of a RAS inhibitor as standard of care. The study will also include patients that are unable to tolerate RAS inhibitor therapy. Additional eligibility criteria include urine protein creatinine ratio (UPCR) ≥1 g/g and eGFR ≥30 mL/min/1.73 m2. Participants will have study assessments over two and a half years with options for remote study visits using telemedicine and home health visits. The primary objective is to evaluate the effect of atrasentan versus placebo on proteinuria at Week 24. Secondary objectives include evaluating the change from baseline in eGFR, safety, and tolerability, and quality of life.

Results

N/A

Conclusion

N/A

Uveitis intermedia as the initial presentation of a primary lymphoma of the central nervous system

Primary central nervous system lymphoma is one of the most infrequent brain tumours, accounting for 3% of primary central nervous system neoplasms. In addition to its low prevalence, clinical presentation is usually nonspecific, leading to diagnostic delay. Intraocular involvement occurs in 15% of cases, and disease onset in this location is even rarer. We present a case of a patient with intermediate uveitis as the first clinical manifestation of this neoplasm.

Inter-individual variability in atrasentan exposure partly explains variability in kidney protection and fluid retention responses: A post hoc analysis of the SONAR trial

AIM

To evaluate whether atrasentan plasma exposure explains between-patient variability in urinary albumin-to-creatinine ratio (UACR) response, a surrogate for kidney protection, and B-type natriuretic peptide (BNP) response, a surrogate for fluid expansion.

METHODS

Type 2 diabetic patients with chronic kidney disease (n = 4775) received 0.75 mg atrasentan for 6 weeks in the active run-in period. Individual area under the concentration-time-curve (AUC) was estimated using a population pharmacokinetic model. The association between atrasentan AUC, other clinical characteristics, and UACR and BNP response, was estimated using linear regression.

RESULTS

The median atrasentan AUC was 43.8 ng.h/mL with a large variation among patients (2.5th-97.5th percentiles [P]: 12.6 to 197.5 ng.h/mL). Median UACR change at the end of enrichment was -36.0% and median BNP change was 8.7%, which also varied among patients (UACR, 2.5th-97.5th P: -76.2% to 44.5%; BNP, 2.5th-97.5th P: -71.5% to 300.0%). In the multivariable analysis, higher atrasentan AUC was associated with greater UACR reduction (4.88% per doubling in ng.h/mL [95% confidence interval {CI}: 6.21% to 3.52%], P < .01) and greater BNP increase (3.08% per doubling in ng.h/mL [95% CI: 1.12% to 4.11%], P < .01) independent of estimated glomerular filtration rate, haemoglobin or BNP. Caucasian patients compared with black patients had greater UACR reduction (7.06% [95% CI: 1.38% to 13.07%]) and also greater BNP increase (8.75% [95% CI: 1.65% to 15.35%]). UACR response was not associated with BNP response (r = 0.06).

CONCLUSION

Atrasentan plasma exposure varied among individual patients and partially explained between-patient variability in efficacy and safety response.

Abstract 078: Nephron-Specific Deletion of Intraflagellar Transport 88 Alters Renal Electrolyte Excretion in the Absence of Cystic Kidney Disease in a Sex-Specific Manner

Defects in primary cilia in the nephron can cause cystic kidney disease, however, the physiological role of nephron primary cilia is largely unknown. To address this, nephron primary cilia were disrupted by targeting the intraflagellar transport 88 ( IFT88 ) gene. IFT88 f/f mice containing loxP-flanked exons 4-6 of the IFT88 gene were bred with doxycycline-inducible Pax8-rtTA/tetO7-CMV*-Cre knockin mice. Inactivation of IFT88 (KO) was induced with 2 mg/ml doxycycline in drinking water supplemented with 2% sucrose for 12 days at 2 months of age; controls were the same genotype but without doxycycline treatment; mice were studied 2-4 months after doxycycline treatment. Renal IFT88 gene recombination was observed in KO mice associated with an 88±5% decrease in whole kidney IFT88 mRNA. Metabolic cage studies were conducted under a normal-Na + (0.3% Na + , 5 days), a low-Na + (0.03% Na + , 7 days), and a high-Na + (3.2% Na + , 7 days) diet (N=10 males and 10 females per group). No significant differences were found in food intake, water intake, urine volume (UV), urinary Na + excretion (UNaV), or urinary K + excretion (UKV) between KO and control mice under either a normal-Na + or a low-Na + diet. In contrast, water intake, UV, UNaV, and UKV were higher on days 2-7 of high-Na + diet in male, but not female, KO compared with control mice (p<0.05); no differences in food intake were noted. Plasma renin concentration was similar between high-Na + diet-treated KO and control mice. Both urinary nitrite/nitrate excretion (UNOxV) and urinary prostaglandin E2 excretion (UPGE2V) were increased in high-Na + diet-treated male, but not female, KO mice (p<0.05). No cysts or tubule dilation were evident in KO mice at the end of experiments. In summary, nephron-specific deletion of IFT88 increases urinary fluid and electrolyte excretion during high salt intake associated with increases in UNOxV and UPGE2V; these differences are evident in male, but not female, mice. These data suggest that primary cilia regulate nephron function independent of cystogenesis and in a sex-specific manner.

Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial

BACKGROUND

Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes.

METHODS

We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18-85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR) 25-75 mL/min per 1·73 m² of body surface area, and a urine albumin-to-creatinine ratio (UACR) of 300-5000 mg/g who had received maximum labelled or tolerated renin-angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders) were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days) or end-stage kidney disease (eGFR <15 mL/min per 1·73 m² sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure) in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532.

FINDINGS

Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325) or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4-2·9). 79 (6·0%) of 1325 patients in the atrasentan group and 105 (7·9%) of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR] 0·65 [95% CI 0·49-0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%) of 1325 patients in the atrasentan group and 34 (2·6%) of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85-2·07]; p=0·208). 58 (4·4%) patients in the atrasentan group and 52 (3·9%) in the placebo group died (HR 1·09 [95% CI 0·75-1·59]; p=0·65).

INTERPRETATION

Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease.

FUNDING

AbbVie.

Baseline characteristics and enrichment results from the SONAR trial

AIM

The SONAR trial uses an enrichment design based on the individual response to the selective endothelin receptor antagonist atrasentan on efficacy (the degree of the individual response in the urinary albumin-to-creatinine ratio [UACR]) and safety/tolerability (signs of sodium retention and acute increases in serum creatinine) to assess the effects of this agent on major renal outcomes. The patient population and enrichment results are described here.

METHODS

Patients with type 2 diabetes with an estimated glomerular filtration rate (eGFR) within 25 to 75 mL/min/1.73 m² and UACR between 300 and 5000 mg/g were enrolled. After a run-in period, eligible patients received 0.75 mg/d of atrasentan for 6 weeks. A total of 2648 responder patients in whom UACR decreased by ≥30% compared to baseline were enrolled, as were 1020 non-responders with a UACR decrease of <30%. Patients who experienced a weight gain of >3 kg and in whom brain natriuretic peptide exceeded ≥300 pg/mL, or who experienced an increase in serum creatinine >20% (0.5 mg/dL), were not randomized.

RESULTS

Baseline characteristics were similar for atrasentan responders and non-responders. Upon entry to the study, median UACR was 802 mg/g in responders and 920 mg/g in non-responders. After 6 weeks of treatment with atrasentan, the UACR change in responders was -48.8% (95% CI, -49.8% to -47.9%) and in non-responders was -1.2% (95% CI, -6.4% to 3.9%). Changes in other renal risk markers were similar between responders and non-responders except for a marginally greater reduction in systolic blood pressure and eGFR in responders.

CONCLUSIONS

The enrichment period has successfully identified a population with a profound UACR reduction without clinical signs of sodium retention in whom a large atrasentan effect on clinically important renal outcomes is possible. The SONAR trial aims to establish whether atrasentan confers renal protection.

Longitudinal Assessment of the Effect of Atrasentan on Thoracic Bioimpedance in Diabetic Nephropathy: A Randomized, Double-Blind, Placebo-Controlled Trial

Background

Fluid retention is a common adverse event in patients who receive endothelin (ET) receptor antagonist therapy, including the highly selective ETA receptor antagonist, atrasentan.

Objective

We performed longitudinal assessments of thoracic bioimpedance in patients with type 2 diabetes mellitus and nephropathy to determine whether a decrease in bioimpedance accurately reflected fluid retention during treatment with atrasentan.

Study Design

We conducted a randomized, double-blind, placebo-controlled study in 48 patients with type 2 diabetes mellitus and nephropathy who were receiving stable doses of renin angiotensin system inhibitors and diuretics.

Methods

Patients were randomized 1:1:1 to placebo, atrasentan 0.5 mg, or atrasentan 1.25 mg once daily for 8 weeks. Thoracic bioimpedance, vital signs, clinical exams, and serologies were taken at weeks 1, 2, 4, 6, and 8, with the exception of serum hemoglobin, which was not taken at week 1, and serum brain natriuretic peptide, which was only taken at baseline, week 4, and week 8.

Results

Alterations in bioimpedance were more often present in those who received atrasentan than in those who received placebo, though overall differences were not statistically significant. Transient declines in thoracic bioimpedance during the first 2 weeks of atrasentan exposure occurred before or during peak increases in body weight and hemodilution (decreased serum hemoglobin).

Conclusions

We conclude that thoracic bioimpedance did not reflect changes in weight gain or edema with atrasentan treatment in this study. However, the sample size was small, and it may be of interest to explore the use of thoracic bioimpedance in a larger population to understand its potential clinical use in monitoring fluid retention in patients with chronic kidney disease who receive ET receptor antagonists.

Rationale and protocol of the Study Of diabetic Nephropathy with AtRasentan (SONAR) trial: A clinical trial design novel to diabetic nephropathy

AIMS

Individuals with diabetes and chronic kidney disease (CKD) are at high risk for renal events. Recent trials of novel treatments have been negative, possibly because of variability in response to treatment of the target risk factor. Atrasentan is a selective endothelin A receptor antagonist that reduces urinary albumin-to-creatinine ratio (UACR), with a large variability between patients. We are assessing its effect on renal outcomes in the Study Of diabetic Nephropathy with AtRasentan (SONAR; NCT01858532) with an enrichment design (>30% lowering of albuminuria) to select patients most likely to benefit.

MATERIALS AND METHODS

SONAR is a randomized, double-blind, placebo-controlled trial with approximately 3500 participants who have stage 2-4 CKD and macroalbuminuria and are receiving a maximum tolerated dose of a renin-angiotensin system inhibitor.

RESULTS

After 6 weeks of exposure to atrasentan 0.75 mg once daily (enrichment period), participants with ≥30% UACR decrease and no tolerability issues (responders) were randomly assigned to placebo or atrasentan 0.75 mg/day. The responder group will be used for primary efficacy and safety analyses. Approximately 1000 participants with <30% UACR reduction (non-responders) were also randomized to placebo or atrasentan. The primary endpoint is a composite of a sustained doubling of serum creatinine or end-stage renal disease. The original power calculation indicated that a total of 425 primary renal events in the responder group provides 90% power to detect a 27% reduction in relative risk (alpha level of .05).

CONCLUSION

SONAR aims to determine whether atrasentan added to guideline-recommended therapies safely reduces the risk of CKD progression and delays the onset of end-stage renal disease in patients with type 2 diabetes and nephropathy. SONAR also aims to establish whether the enrichment of patients based on their initial "surrogate" response to atrasentan will deliver a trial design in accord with personalized treatment of diabetic kidney disease.

Impact of Angiotensin Type 1A Receptors in Principal Cells of the Collecting Duct on Blood Pressure and Hypertension

The main actions of the renin-angiotensin system to control blood pressure (BP) are mediated by the angiotensin type 1 receptors (AT1Rs). The major murine AT1R isoform, AT1AR, is expressed throughout the nephron, including the collecting duct in both principal and intercalated cells. Principal cells play the major role in sodium and water reabsorption. Although aldosterone is considered to be the dominant regulator of sodium reabsorption by principal cells, recent studies suggest a role for direct actions of AT1R. To specifically examine the contributions of AT1AR in principal cells to BP regulation and the development of hypertension in vivo, we generated inbred 129/SvEv mice with deletion of AT1AR from principal cells (PCKO). At baseline, we found that BPs measured by radiotelemetry were similar between PCKOs and controls. During 1-week of low-salt diet (<0.02% NaCl), BPs fell significantly (P<0.05) and to a similar extent in both groups. On a high-salt (6% NaCl) diet, BP increased but was not different between groups. During the initial phase of angiotensin II-dependent hypertension, there was a modest but significant attenuation of hypertension in PCKOs (163±6 mm Hg) compared with controls (178±2 mm Hg; P<0.05) that was associated with enhanced natriuresis and decreased alpha epithelial sodium channel activation in the medulla of PCKOs. However, from day 9 onward, BPs were indistinguishable between groups. Although effects of AT1AR on baseline BP and adaptation to changes in dietary salt are negligible, our studies suggest that direct actions of AT1AR contribute to the initiation of hypertension and epithelial sodium channel activation.

Prediction of the effect of atrasentan on renal and heart failure outcomes based on short-term changes in multiple risk markers

BACKGROUND

A recent phase II clinical trial (Reducing Residual Albuminuria in Subjects with Diabetes and Nephropathy with AtRasentan trial and an identical trial in Japan (RADAR/JAPAN)) showed that the endothelin A receptor antagonist atrasentan lowers albuminuria, blood pressure, cholesterol, hemoglobin, and increases body weight in patients with type 2 diabetes and nephropathy. We previously developed an algorithm, the Parameter Response Efficacy (PRE) score, which translates short-term drug effects into predictions of long-term effects on clinical outcomes.

DESIGN

We used the PRE score on data from the RADAR/JAPAN study to predict the effect of atrasentan on renal and heart failure outcomes.

METHODS

We performed a post-hoc analysis of the RADAR/JAPAN randomized clinical trials in which 211 patients with type-2 diabetes and nephropathy were randomly assigned to atrasentan 0.75 mg/day, 1.25 mg/day, or placebo. A PRE score was developed in a background set of completed clinical trials using multivariate Cox models. The score was applied to baseline and week-12 risk marker levels of RADAR/JAPAN participants, to predict atrasentan effects on clinical outcomes. Outcomes were defined as doubling serum creatinine or end-stage renal disease and hospitalization for heart failure.

RESULTS

The PRE score predicted renal risk changes of -23% and -30% for atrasentan 0.75 and 1.25 mg/day, respectively. PRE scores also predicted a small non-significant increase in heart failure risk for atrasentan 0.75 and 1.25 mg/day (+2% vs. +7%). Selecting patients with >30% albuminuria reduction from baseline (responders) improved renal outcome to almost 50% risk reduction, whereas non-responders showed no renal benefit.

CONCLUSIONS

Based on the RADAR/JAPAN study, with short-term changes in risk markers, atrasentan is expected to decrease renal risk without increased risk of heart failure. Within this population albuminuria responders appear to contribute to the predicted improvements, whereas non-responders showed no benefit. The ongoing hard outcome trial (SONAR) in type 2 diabetic patients with >30% albuminuria reduction to atrasentan will allow us to assess the validity of these predictions.

Thromboxane prostanoid receptors enhance contractions, endothelin-1, and oxidative stress in microvessels from mice with chronic kidney disease

Cardiovascular disease is frequent in chronic kidney disease and has been related to angiotensin II, endothelin-1 (ET-1), thromboxane A2, and reactive oxygen species (ROS). Because activation of thromboxane prostanoid receptors (TP-Rs) can generate ROS, which can generate ET-1, we tested the hypothesis that chronic kidney disease induces cyclooxygenase-2 whose products activate TP-Rs to enhance ET-1 and ROS generation and contractions. Mesenteric resistance arterioles were isolated from C57/BL6 or TP-R+/+ and TP-R-/- mice 3 months after SHAM-operation (SHAM) or surgical reduced renal mass (RRM, n=6/group). Microvascular contractions were studied on a wire myograph. Cellular (ethidium: dihydroethidium) and mitochondrial (mitoSOX) ROS were measured by fluorescence microscopy. Mice with RRM had increased excretion of markers of oxidative stress, thromboxane, and microalbumin; increased plasma ET-1; and increased microvascular expression of p22(phox), cyclooxygenase-2, TP-Rs, preproendothelin and endothelin-A receptors, and increased arteriolar remodeling. They had increased contractions to U-46,619 (118 ± 3 versus 87 ± 6, P<0.05) and ET-1 (108 ± 5 versus 89 ± 4, P<0.05), which were dependent on cellular and mitochondrial ROS, cyclooxygenase-2, and TP-Rs. RRM doubled the ET-1-induced cellular and mitochondrial ROS generation (P<0.05). TP-R-/- mice with RRM lacked these abnormal structural and functional microvascular responses and lacked the increased systemic and the increased microvascular oxidative stress and circulating ET-1. In conclusion, RRM leads to microvascular remodeling and enhanced ET-1-induced cellular and mitochondrial ROS and contractions that are mediated by cyclooxygenase-2 products activating TP-Rs. Thus, TP-Rs can be upstream from enhanced ROS, ET-1, microvascular remodeling, and contractility and may thereby coordinate vascular dysfunction in chronic kidney disease.

The endothelin antagonist atrasentan lowers residual albuminuria in patients with type 2 diabetic nephropathy

Despite optimal treatment, including renin-angiotensin system (RAS) inhibitors, patients with type 2 diabetic nephropathy have high cardiorenal morbidity and mortality related to residual albuminuria. We evaluated whether or not atrasentan, a selective endothelin A receptor antagonist, further reduces albuminuria when administered concomitantly with maximum tolerated labeled doses of RAS inhibitors. We enrolled 211 patients with type 2 diabetes, urine albumin/creatinine ratios of 300-3500 mg/g, and eGFRs of 30-75 ml/min per 1.73 m(2) in two identically designed, parallel, multinational, double-blind studies. Participants were randomized to placebo (n=50) or to 0.75 mg/d (n=78) or 1.25 mg/d (n=83) atrasentan for 12 weeks. Compared with placebo, 0.75 mg and 1.25 mg atrasentan reduced urine albumin/creatinine ratios by an average of 35% and 38% (95% confidence intervals of 24 to 45 and 28 to 47, respectively) and reduced albuminuria≥30% in 51% and 55% of participants, respectively. eGFR and office BP measurements did not change, whereas 24-hour systolic and diastolic BP, LDL cholesterol, and triglyceride levels decreased significantly in both treatment groups. Use of atrasentan was associated with a significant increase in weight and a reduction in hemoglobin, but rates of peripheral edema, heart failure, or other side effects did not differ between groups. However, more patients treated with 1.25 mg/d atrasentan discontinued due to adverse events. After stopping atrasentan for 30 days, measured parameters returned to pretreatment levels. In conclusion, atrasentan reduced albuminuria and improved BP and lipid spectrum with manageable fluid overload-related adverse events in patients with type 2 diabetic nephropathy receiving RAS inhibitors.

Reduced ENaC activity and blood pressure in mice with genetic knockout of the insulin receptor in the renal collecting duct

To elucidate the role of the insulin receptor (IR) in collecting duct (CD), we bred mice with IR selectively deleted from CD principal cells using an aquaporin-2 promoter to drive Cre-recombinase expression. Young, adult male knockout (KO) mice had altered plasma and electrolyte homeostasis under high- (HS) and low-sodium (LS) diets, relative to wild-type (WT) littermates. One week of LS feeding led to a significant reduction in urine potassium (K(+)) and sodium (Na(+)) excretion in KO, and a reduction in the ratio of Na(+) to chloride (Cl(-)) in plasma, relative to WT. HS diet (1 wk) increased plasma K(+) and reduced urine Na(+) to Cl(-) ratio in the KO. Furthermore, KO mice had a significantly (P = 0.025) blunted natriuretic response to benzamil, an epithelial sodium channel (ENaC) antagonist. Western blotting of cortex homogenates revealed modestly, but significantly (∼15%), lower band density for the β-subunit of ENaC in the KO vs. WT mice, with no differences for the α- or γ-subunits. Moreover, blood pressure (BP), measured by radiotelemetry, was significantly lower in KO vs. WT mice under basal conditions (mmHg): 112 ± 5 (WT), 104 ± 2 (KO), P = 0.023. Chronic insulin infusion reduced heart rate in the WT, but not in the KO, and modestly reduced BP in the WT only. Overall, these results support a fundamental role for insulin through its classic receptor in the modulation of electrolyte homeostasis and BP.

Abstract 42: AT1 Angiotensin Receptors in Principal Cells of the Collecting Duct Have Minimal Impact on Blood Pressure and the Development of Hypertension

The main actions of the renin angiotensin system to control blood pressure (BP) are mediated by the angiotensin type 1 receptors (AT 1 R). The major murine AT 1 R isoform, AT 1A is highly expressed in epithelial cells throughout the nephron, including the collecting duct (CD). The CD consists of two cell types, principal (PC) and intercalated cells (IC) with distinct functions. Activation of AT 1 R in PC stimulates solute reabsorption in the CD by increasing the activity of epithelial sodium channels. To examine the role of the AT 1A R in the PC to BP regulation and the development of hypertension in vivo , we generated inbred 129SvEv mice with cell-specific deletion of AT 1A R in PC (PC-KO, n=6). AQP2-Cre transgenic mouse line was used to excise the floxed Agtr1a allele in PC. mTmG reporter mouse line was used to confirm specific expression of AQP2-Cre transgene in PC, and found the pattern of expression to be predominantly in medullary CD. Using RT-PCR, mRNA levels for AT 1A R were reduced by ≈50% in the inner medulla of PC-KO mice ( P <0.05), but unaffected in cortex. Baseline BP measured by radiotelemetry was similar between PC-KO (122±1.6 mm Hg) and controls (122±1.6 mm Hg). During one week of feeding a low salt (<0.002% NaCl) diet, MAP fell significantly (P<0.05) and to a similar extent in both groups, (PC-KO: 116±1 mm Hg; Controls: 117±2 mm Hg). High salt (6% NaCl) diet increased BP (P<0.01), but was not different between groups (PC-KO: 129±2 mm Hg; Controls: 131±2 mm Hg). Finally, we induced hypertension with chronic infusion of Ang II (1000 ng/kg/min) by osmotic mini-pumps. During the initial phase (days 1-8), there was a modest but significant attenuation of hypertension in PC-KO (167±7 mm Hg) compared to controls (178±3 mm Hg, P<0.001). However, by day 9 levels of BP were indistinguishable between groups and there was no difference in BP in the later phase (days 9-14) of hypertension (PC-KO: 175±12 mm Hg; Controls: 177±7 mm Hg). Heart to body weight ratio after Ang II infusion was not different between groups. In summary, AT 1A R in PC of the medullary CD have little influence on BP, adaptation to changes in dietary salt intake or development of hypertension. We suggest that other mediators, such as aldosterone, may have a more important role to influence sodium handling in this nephron segment.

Abstract 233: Evidence for an Interaction Between Systemic and Renal Angiotensinogen in the Control of Arterial Pressure

Both the liver and proximal tubule make angiotensinogen (AGT), and overexpression of AGT in either region increases blood pressure (BP). To determine the relative contributions of renal and systemic AGT in modulating BP, mice were used with AGT overexpression in kidney (K), liver (L) or both sites (KL). Male transgenic and wildtype (WT) controls aged 24 weeks underwent BP recording via telemetry and metabolic cage studies on normal (0.25%) and high (3.2%) sodium diets. Mean BP (MAP) was higher in K and KL vs L and WT mice fed normal salt, while MAP in L mice was higher than controls. High salt intake did not alter MAP in WT, K or KL mice but increased it in L mice. Plasma AGT levels, plasma renin concentration, urine Na excretion and urine volume were similar between groups regardless of sodium intake. Urinary AGT (ng/day) on normal sodium intake was: WT: 5±1, L: 4±1, K: 20±5 and KL: 34±9. High salt increased urine AGT in all groups (WT: 19±4, L: 42±8, K: 290±75, KL: 407± 72). High salt did not alter plasma AGT levels but reduced plasma renin concentration in all groups. Taken together, these data show a correlation between urinary AGT and BP. Mice with renal AGT overexpression may be maximally hypertensive on a normal sodium diet since renal AGT is already high. Mice with liver AGT overexpression have mild hypertension on a normal sodium diet that is exacerbated by high sodium intake; this is associated with a significant increase in urinary AGT as compared to WT animals. Thus, systemic AGT may have the potential to regulate renal AGT and this effect may be a key determinant of BP.

[Using interaction-intensive therapeutic nursing measures and "home remedies" in nursing care. An explorative study as a plea for integrated nursing practice]

BACKGROUND

Until today there existed no major studies about the wide range of currently utilized methods or potential sociodemographic and institutional influences on utilization despite an immense interest among nurses in alternative nursing methods (in this study referred to as home remedies).

METHODS

In this study, from standardized questionnaires with a convenience sample of three different settings of nursing practice, i.e. acute-care, nursing homes, and home health care were analyzed using the statistical program SPSS.

RESULTS

Our analysis showed that a wide range of traditional home remedies is being utilized, e.g. application of heat and cold or herbal infusion (herbal teas). Furthermore, lay approaches such as aromatherapy were also commonly used. The statistical analysis revealed complex influences of age, duration of nursing practice and institutional setting in the utilization of home remedies.

CONCLUSION

There is need for more systematic studies to further examine the alternative methods or home remedies so popular among nurses and their patients. Regarding a more consistent naming of the variety of different methods coming from naturopathy, folk and lay medicine, the authors suggest the term "integrative nursing care".

Otologic surgery in patients with HIV-1 and AIDS

Otologic disease in patients infected with HIV occurs frequently and usually represents rhinologic disease and associated eustachian tube dysfunction rather than manifestations of HIV infection. As in all patients, the decision to operate on an HIV-infected individual who would benefit from major otologic surgery is a balance between the risks of the procedure and the possible benefits to the patient. Many concerns regarding wound infection and healing have been raised. The objective of this study is to evaluate the outcome of otologic procedures in this population. The charts of 9 men and 4 women were reviewed. Seven patients (54%) met the Centers for Disease Control and Prevention criteria for AIDS. Patients with chronic otitis media (46%) underwent tympanomastoidectomies, and the cases of acute mastoiditis (31%) were managed with simple mastoidectomies. Other procedures included repair of cerebrospinal fluid leak (15%) and stapedectomy (8%). Two patients had early complications and died during their hospitalizations. Three patients had prolonged hospital courses requiring long-term antibiotics. These 5 patients underwent urgent procedures and were severely immunocompromised. Of the remaining 8 patients only 2 had AIDS, and all had an uncomplicated postoperative course. Six of these patients were followed up for more than 1 year, and only 2 developed subsequent otologic disease.

[The practical realization of the hospice concept in health facilities]

In a qualitative study the concept of hospices and their practical realization were reconstructed. Based on interviews with two nurses, each from a different hospice, and one nurse from a palliative ward, it is was found that fundamental differences in institutional structures exist between the hospices and the palliative ward. This has consequences for the care of a seriously ill patient and his family. These institutional differences are manifested in the two main points of the study "everyday life in the hospice" and "taking leave of the deceased".

Uncommon lesions presenting as tumors of the internal auditory canal and cerebellopontine angle

OBJECTIVE

The aim of this study was to identify distinguishing characteristics of uncommon lesions of the cerebellopontine angle (CPA) and internal auditory canal (IAC) in order to attain the correct diagnosis and thus formulate an appropriate therapeutic protocol.

STUDY DESIGN

A retrospective chart analysis was performed on all patients with surgically managed lesions of the IAC and CPA referred to neuropathology from January 1985 to April 1996.

SETTING

All patients were treated by New York University faculty at a tertiary referral center.

PATIENTS

Among 426 surgical cases identified, 384 patients (90.1%) with acoustic neuromas and 18 patients (4.2%) with meningiomas were excluded. The remaining 24 cases, involving 17 women and seven men with a median age of 34 years, were analyzed.

INTERVENTION

Most patients underwent audiovestibular evaluations, as well as magnetic resonance imaging (MRI) and computed tomographic (CT) scanning, and all patients underwent neurotologic surgery as part of their management protocol.

MAIN OUTCOME MEASURES

Correlating patient presentation, preoperative imaging, and surgical findings often identified distinguishing characteristics of unusual CPA and IAC lesions.

RESULTS

Unusual lesions identified at the CPA and IAC included: four epidermoids, four lipomas, two facial neuromas, two arachnoid cysts, two choroid plexus papillomas, two metastatic adenocarcinomas, one metastatic neuroblastoma, one ependymoma, one lymphoma, one cholesterol cyst, one angioleiomyoma, one venous hemangioma, one cavernous angioma, and one pontine glioma.

CONCLUSIONS

Preoperative tumor differentiation based on the patient history, physical examination, audiovestibular testing, CT, and MRI help the surgeon to formulate an appropriate treatment protocol.

Cochlear implants in the management of bilateral acoustic neuromas

Multichannel cochlear implants currently provide the only modality for successful auditory rehabilitation of patients with bilateral profound sensorineural hearing loss who derive no benefit from amplification. We have developed a protocol for patients with neurofibromatosis and bilateral acoustic neuromas in which every effort is made to preserve hearing in at least one ear. Failing that, the cochlear nerve is spared, potentially allowing for the insertion of a cochlear implant. We present our data on one such patient whose auditory function was restored with a Nucleus mini 22-channel cochlear implant following removal of his acoustic neuroma.

Otologic disease in AIDS patients: CT correlation

The contrast-enhanced computed tomographic (CT) scans of the temporal bone and brain in 18 patients with otologic disease and acquired immunodeficiency syndrome (AIDS) were retrospectively reviewed. Seven scans revealed middle ear and mastoid disease; three scans were consistent with central nervous system (CNS) pathology; and eight scans demonstrated no abnormalities. CT scanning was found useful in localizing otopathology and diagnosing CNS toxoplasmosis, aural polyps, osteomyelitis, mastoiditis, and middle ear effusion due to hypertrophic lymphoid tissue. The authors conclude that AIDS patients with sensorineural hearing loss should undergo contrast-enhanced brain CT scans to rule out CNS pathology; AIDS status does not alter criteria for CT scanning in patients with conductive hearing loss; and that images of the nasopharynx should be included on temporal bone CT scans of patients with conductive hearing loss in order to exclude eustachian tube obstruction by hypertrophic lymphoid tissue.

Frontal bone reconstruction with split calvarial and cancellous iliac bone

An autogenous split-thickness calvarial bone graft that was used to correct a marked depression in the frontal region of the forehead resulted in excellent cosmesis. Cancellous bone from the iliac crest, which was applied between the posterior wall of the frontal sinus and the anterior calvarial bone graft, eliminated the dead space and made infection less likely in an area prone to such infections.

Rhinomanometric evaluation of two nasal steroid sprays in rhinitis

A prospective, randomized study comparing the effectiveness of two nasal steroid sprays, flunisolide and beclomethasone dipropionate, in the treatment of nasal obstruction associated with allergic or vasomotor rhinitis has been conducted at New York University Medical Center-Bellevue Hospital. All patients underwent routine history and physical examinations and a modified radioallergosorbent test. Paranasal sinus films were used to exclude patients with sinusitis. The Rhinotest microprocessor rhinomanometer was used to quantify pretreatment and posttreatment total nasal air flow and resistance during a period of 2 months. These findings were assessed in conjunction with the patients' subjective complaints. Results demonstrated that anterior rhinomanometric assessment of the nasal airway during inhalant therapy correlated well with the patients' own subjective impressions of nasal air flow. Both steroid inhalants were effective; however, flunisolide provided for earlier and more substantial symptomatic relief. Beclomethasone dipropionate had milder side effects.

Otologic disease in patients with acquired immunodeficiency syndrome

A 5-year retrospective study evaluating otologic disease in patients with acquired immunodeficiency syndrome (AIDS) was conducted at the New York University Medical Center-Bellevue Hospital Center. Twenty-six patients with documented otologic disease who met the Centers for Disease Control criteria for AIDS were identified and their charts were analyzed according to presenting complaints, physical examination, diagnostic modalities, pathologic condition, management, and outcome. A marked diversity of otologic diseases of varying severity was noted. The majority of patients complained of hearing loss and otalgia during their hospitalization for treatment of AIDS-related opportunistic infections. The most frequent diagnoses were otitis externa, acute otitis media, and otitis media with effusion. Sensorineural hearing loss frequently appeared to be related to ototoxic medications and neurologic infections.