All-Cause and Cardiovascular-Related Mortality in CKD Patients With and Without Heart Failure: A Population-Based Cohort Study in Kaiser Permanente Southern California.

Rationale & Objective: Heart failure and chronic kidney disease (CKD) frequently coexist reflective of the strong interplay between these organ systems. A better understanding of the prevalence of different types of heart failure (preserved and reduced ejection fraction) and their subsequent mortality risks among advanced CKD patients would provide important epidemiologic insights and may pave the way for more focused and proactive management strategies. Study Design: Retrospective cohort study. Setting & Population: Patients aged ≥18 years with incident CKD (estimated glomerular filtration rate ≤45 mL/min/1.73 m2) with and without heart failure in a large integrated health care system in Southern California. Exposure: Heart failure, heart failure with preserved ejection fraction (HFpEF), heart failure with reduced ejection fraction (HFrEF). Outcomes: All-cause and cardiovascular-related mortality within one year of CKD identification. Analytical Approach: HRs were estimated using Cox proportional-hazards model for risk of all-cause mortality and Fine-Gray subdistribution hazard model for risk of cardiovascular-related mortality within 1 year. Results: The study cohort included 76,688 patients with incident CKD between 2007 and 2017, of which 14,249 (18.6%) had prevalent heart failure. Among these patients, 8,436 (59.2%) had HFpEF and 3,328 (23.3%) had HFrEF. Compared with patients without heart failure, the HR for 1-year all-cause mortality was 1.70 (95% CI, 1.60-1.80) among patients with heart failure. The HRs were 1.59 (95% CI, 1.48-1.70) for patients with HFpEF and 2.43 (95% CI, 2.23-2.65) for patients with HFrEF. Compared with patients without heart failure, the 1-year cardiovascular-related mortality HR for patients with heart failure was 6.69 (95% CI, 5.93-7.54). Cardiovascular-related mortality HR was even higher among those with HFrEF (HR, 11.47; 95% CI, 9.90-13.28). Limitations: Retrospective design with a short 1-year follow-up period. Additional variables including medication adherence, medication changes, and time-varying variables were not accounted for in this intention-to-treat analysis. Conclusions: Among patients with incident CKD, heart failure was highly prevalent with HFpEF accounting for over 70% among patients with known ejection fraction. Although the presence of heart failure was associated with higher 1-year all-cause and cardiovascular-related mortality, patients with HFrEF were the most vulnerable.

Real-world use patterns of angiotensin receptor-neprilysin inhibitor (sacubitril/valsartan) among patients with heart failure within a large integrated health system.

BACKGROUND: Sacubitril/valsartan is a first-in-class angiotensin receptor-neprilysin inhibitor (ARNI) that is now preferred in guidelines over angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) for patients with heart failure with reduced ejection fraction (HFrEF). However, it has not been broadly adopted in clinical practice. OBJECTIVE: To characterize ARNI use within a large diverse real-world population and assess for any racial disparities. METHODS: We conducted a cross-sectional study within Kaiser Permanente Southern California. Adult patients with HFrEF who received ARNIs, ACEIs, or ARBs between January 1, 2014, and November 30, 2020, were identified. The prevalence of ARNI use among the cohort and patient characteristics by ARNIs vs ACEIs/ARBs use were described. Multivariable regression was performed to estimate odds ratios and 95% CIs of receiving ARNI by race and ethnicity. RESULTS: Among 12,250 patients with HFrEF receiving ACEIs, ARBs, or ARNIs, 556 (4.54%) patients received ARNIs. ARNI use among this cohort increased from 0.02% in 2015 to 7.48% in 2020. Patients receiving ARNIs were younger (aged 62 vs 69 years) and had a lower median ejection fraction (27% vs 32%) compared with patients receiving ACEIs/ARBs. They also had higher use of mineralocorticoid antagonists (24.1% vs 19.8%) and automatic implantable cardioverterdefibrillators (17.4% vs 13.3%). There were no significant differences in rate of ARNI use by race and ethnicity. CONCLUSIONS: Within a large diverse integrated health system in Southern California, the rate of ARNI use has risen over time. Patients given ARNIs were younger with fewer comorbidities, while having worse ejection fraction. Racial minorities were no less likely to receive ARNIs compared with White patients. DISCLOSURES: Dr Huang had stock ownership in Gilead and Pfizer. Dr Liang received support for article processing and medical writing.

Disease-Specific Factors Associated with Readmissions or Mortality After Hospital Discharge in COVID-19 Patients: a Retrospective Cohort Study.

BACKGROUND: Understanding the implications of disease-specific factors beyond baseline patient characteristics for coronavirus disease 2019 (COVID-19) may allow for identification of indicators for safe hospital discharge. OBJECTIVE: Assess whether disease-specific factors are associated with adverse events post-discharge using a data-driven approach. DESIGN: Retrospective cohort study. SETTING: Fifteen medical centers within Kaiser Permanente Southern California. PARTICIPANTS: Adult patients (n=3508) discharged alive following hospitalization for COVID-19 between 05/01/2020 and 09/30/2020. INTERVENTIONS: None. MAIN MEASURES: Adverse events defined as all-cause readmission or mortality within 14 days of discharge. Least absolute shrinkage and selection operator (LASSO) was used for variable selection and logistic regression was performed to estimate odds ratio (OR) and 95% confidence interval (CI). KEY RESULTS: Four variables including age, Elixhauser index, treatment with remdesivir, and symptom duration at discharge were selected by LASSO. Treatment with remdesivir was inversely associated with adverse events (OR: 0.46 [95%CI: 0.36-0.61]), while symptom duration ≤ 10 days was associated with adverse events (OR: 2.27 [95%CI: 1.79-2.87]) in addition to age (OR: 1.02 [95%CI: 1.01-1.03]) and Elixhauser index (OR: 1.15 [95%CI: 1.11-1.20]). A significant interaction between remdesivir and symptom duration was further observed (p=0.01). The association of remdesivir was stronger among those with symptom duration ≤10 days vs >10 days at discharge (OR: 0.30 [95%CI: 0.19-0.47] vs 0.62 [95%CI: 0.44-0.87]), while the association of symptom duration ≤ 10 days at discharge was weaker among those treated with remdesivir vs those not treated (OR: 1.31 [95%CI: 0.79-2.17] vs 2.71 [95%CI 2.05-3.59]). CONCLUSIONS: Disease-specific factors including treatment with remdesivir, symptom duration, and their interplay may help guide clinical decision making at time of discharge.

Statin Use and Mortality among Patients Hospitalized with Sepsis: A Retrospective Cohort Study within Southern California, 2008-2018.

Background: Despite early goal-directed therapy, sepsis mortality remains high. Statins exhibit pleiotropic effects. Objective: We sought to compare mortality outcomes among statin users versus nonusers who were hospitalized with sepsis. Methods: Retrospective cohort study of patients (age ≥18 years) during 1/1/2008-9/30/2018. Mortality was compared between statin users and nonusers and within statin users (hydrophilic versus lipophilic, fungal versus synthetic derivation, and individual statins head-to-head). Multivariable Cox regression models were used to estimate hazard ratios (HR) for 30-day and 90-day mortality. Inverse probability treatment weighting (IPTW) analysis was performed to account for indication bias. Results: Among 128,161 sepsis patients, 34,088 (26.6%) were prescribed statin drugs prior to admission. Statin users compared to nonusers had a 30-day and 90-day mortality HR (95% CI) of 0.80 (0.77-0.83) and 0.79 (0.77-0.81), respectively. Synthetic derived statin users compared to fungal derived users had a 30- and 90-day mortality HR (95% CI) of 0.86 (0.81-0.91) and 0.85 (0.81-0.89), respectively. Hydrophilic statin users compared to lipophilic users had a 30-day and 90-day mortality HR (95% CI) of 0.90 (0.81-1.01) and 0.86 (0.78-0.94), respectively. Compared to simvastatin, 30-day mortality HRs (95% CI) were 0.85 (0.66-1.10), 0.87 (0.82-0.92), 0.87 (0.76-0.98), and 1.22 (1.10-1.36) for rosuvastatin, atorvastatin, pravastatin, and lovastatin, respectively. Conclusion: Statin use was associated with lower mortality in patients hospitalized with sepsis. Hydrophilic and synthetic statins were associated with better outcomes than lipophilic and fungal-based preparations.

Functional coupling of TRPM2 and extrasynaptic NMDARs exacerbates excitotoxicity in ischemic brain injury.

Excitotoxicity induced by NMDA receptor (NMDAR) activation is a major cause of neuronal death in ischemic stroke. However, past efforts of directly targeting NMDARs have unfortunately failed in clinical trials. Here, we reveal an unexpected mechanism underlying NMDAR-mediated neurotoxicity, which leads to the identification of a novel target and development of an effective therapeutic peptide for ischemic stroke. We show that NMDAR-induced excitotoxicity is enhanced by physical and functional coupling of NMDAR to an ion channel TRPM2 upon ischemic insults. TRPM2-NMDAR association promotes the surface expression of extrasynaptic NMDARs, leading to enhanced NMDAR activity and increased neuronal death. We identified a specific NMDAR-interacting motif on TRPM2 and designed a membrane-permeable peptide to uncouple the TRPM2-NMDAR interaction. This disrupting peptide protects neurons against ischemic injury in vitro and protects mice against ischemic stroke in vivo. These findings provide an unconventional strategy to mitigate excitotoxic neuronal death without directly targeting NMDARs.

TRPM2 deficiency in mice protects against atherosclerosis by inhibiting TRPM2-CD36 inflammatory axis in macrophages.

Atherosclerosis is the major cause of ischemic heart disease and stroke, the leading causes of mortality worldwide. The central pathological features of atherosclerosis include macrophage infiltration and foam cell formation. However, the detailed mechanisms regulating these two processes remain unclear. Here we show that oxidative stress-activated Ca2+-permeable transient receptor potential melastatin 2 (TRPM2) plays a critical role in atherogenesis. Both global and macrophage-specific Trpm2 deletion protect Apoe -/- mice against atherosclerosis. Trpm2 deficiency reduces oxidized low-density lipoprotein (oxLDL) uptake by macrophages, thereby minimizing macrophage infiltration, foam cell formation and inflammatory responses. Activation of the oxLDL receptor CD36 induces TRPM2 activity, and vice versa. In cultured macrophages, TRPM2 is activated by CD36 ligands oxLDL and thrombospondin-1 (TSP1), and deleting Trpm2 or inhibiting TRPM2 activity suppresses the activation of CD36 signaling cascade induced by oxLDL and TSP1. Our findings establish the TRPM2-CD36 axis as a molecular mechanism underlying atherogenesis, and suggest TRPM2 as a potential therapeutic target for atherosclerosis.

Association Between Dexamethasone Treatment After Hospital Discharge for Patients With COVID-19 Infection and Rates of Hospital Readmission and Mortality.

Importance: Current guidelines recommend use of dexamethasone, 6 mg/d, up to 10 days or until discharge for patients hospitalized with COVID-19. Whether patients who received less than 10 days of corticosteroids during hospitalization for COVID-19 benefit from continuing treatment at discharge has not been determined. Objective: To assess whether continuing dexamethasone treatment at discharge is associated with reduced all-cause readmissions or mortality postdischarge. Design, Setting, and Participants: A retrospective cohort study was conducted at 15 medical centers within Kaiser Permanente Southern California. The population included adults who received less than 10 days of dexamethasone, 6 mg/d, until discharge during hospitalization for COVID-19 and were discharged alive between May 1 and September 30, 2020. Exposures: Continued dexamethasone treatment at discharge. Main Outcomes and Measures: All-cause readmissions or mortality within 14 days from discharge. Results: A total of 1164 patients with a median age of 55 (IQR, 44-66) years were identified. Most patients were of Hispanic ethnicity (822 [70.6%]) and male (674 [57.9%]) and required oxygen support during hospitalization (1048 [90.0%]). Of the 1164 patients, 692 (59.5%) continued dexamethasone, 6 mg/d, at discharge. A balanced cohort was created using propensity score and inverse probability of treatment weighting. The adjusted odds ratio (OR) for readmissions or mortality within 14 days was 0.87 (95% CI, 0.58-1.30) for patients who continued dexamethasone therapy at discharge compared with those who did not. Similar results were produced by a sensitivity analysis that restricted the treatment group to those who received exactly 10 days of dexamethasone (OR, 0.89; 95% CI, 0.55-1.43) and by subgroup analyses stratified by the duration of dexamethasone treatment as an inpatient (1-3 days: OR, 0.71; 95% CI, 0.43-1.16; 4-9 days: OR, 1.01; 95% CI, 0.48-2.12), oxygen requirement at discharge (room air: OR, 0.91; 95% CI, 0.53-1.59; supplemental oxygen use: OR, 0.76; 95% CI, 0.42-1.37), and disease duration at discharge (≤10 days: OR, 0.81; 95% CI, 0.49-1.33; >10 days: OR, 0.94; 95% CI, 0.48-1.86). Conclusions and Relevance: In this cohort study of patients with COVID-19, continuing treatment with dexamethasone, 6 mg/d, at discharge was not associated with a reduction in 14-day all-cause readmission or mortality. This finding suggests that dexamethasone should not be routinely prescribed beyond discharge for individuals with COVID-19.

CNNM proteins selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells.

Magnesium is essential for cellular life, but how it is homeostatically controlled still remains poorly understood. Here, we report that members of CNNM family, which have been controversially implicated in both cellular Mg2+ influx and efflux, selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells. Coexpression of CNNMs with the channel markedly increased uptake of divalent cations, which is prevented by an inactivating mutation to the channel's pore. Knockout (KO) of TRPM7 in cells or application of the TRPM7 channel inhibitor NS8593 also interfered with CNNM-stimulated divalent cation uptake. Conversely, KO of CNNM3 and CNNM4 in HEK-293 cells significantly reduced TRPM7-mediated divalent cation entry, without affecting TRPM7 protein expression or its cell surface levels. Furthermore, we found that cellular overexpression of phosphatases of regenerating liver (PRLs), known CNNMs binding partners, stimulated TRPM7-dependent divalent cation entry and that CNNMs were required for this activity. Whole-cell electrophysiological recordings demonstrated that deletion of CNNM3 and CNNM4 from HEK-293 cells interfered with heterologously expressed and native TRPM7 channel function. We conclude that CNNMs employ the TRPM7 channel to mediate divalent cation influx and that CNNMs also possess separate TRPM7-independent Mg2+ efflux activities that contribute to CNNMs' control of cellular Mg2+ homeostasis.

Ca2+ Signaling in Cardiac Fibroblasts and Fibrosis-Associated Heart Diseases.

Cardiac fibrosis is the excessive deposition of extracellular matrix proteins by cardiac fibroblasts and myofibroblasts, and is a hallmark feature of most heart diseases, including arrhythmia, hypertrophy, and heart failure. This maladaptive process occurs in response to a variety of stimuli, including myocardial injury, inflammation, and mechanical overload. There are multiple signaling pathways and various cell types that influence the fibrogenesis cascade. Fibroblasts and myofibroblasts are central effectors. Although it is clear that Ca2+ signaling plays a vital role in this pathological process, what contributes to Ca2+ signaling in fibroblasts and myofibroblasts is still not wholly understood, chiefly because of the large and diverse number of receptors, transporters, and ion channels that influence intracellular Ca2+ signaling. Intracellular Ca2+ signals are generated by Ca2+ release from intracellular Ca2+ stores and by Ca2+ entry through a multitude of Ca2+-permeable ion channels in the plasma membrane. Over the past decade, the transient receptor potential (TRP) channels have emerged as one of the most important families of ion channels mediating Ca2+ signaling in cardiac fibroblasts. TRP channels are a superfamily of non-voltage-gated, Ca2+-permeable non-selective cation channels. Their ability to respond to various stimulating cues makes TRP channels effective sensors of the many different pathophysiological events that stimulate cardiac fibrogenesis. This review focuses on the mechanisms of Ca2+ signaling in fibroblast differentiation and fibrosis-associated heart diseases and will highlight recent advances in the understanding of the roles that TRP and other Ca2+-permeable channels play in cardiac fibrosis.

An Isogenic Human ESC Platform for Functional Evaluation of Genome-wide-Association-Study-Identified Diabetes Genes and Drug Discovery.

Genome-wide association studies (GWASs) have increased our knowledge of loci associated with a range of human diseases. However, applying such findings to elucidate pathophysiology and promote drug discovery remains challenging. Here, we created isogenic human ESCs (hESCs) with mutations in GWAS-identified susceptibility genes for type 2 diabetes. In pancreatic beta-like cells differentiated from these lines, we found that mutations in CDKAL1, KCNQ1, and KCNJ11 led to impaired glucose secretion in vitro and in vivo, coinciding with defective glucose homeostasis. CDKAL1 mutant insulin+ cells were also hypersensitive to glucolipotoxicity. A high-content chemical screen identified a candidate drug that rescued CDKAL1-specific defects in vitro and in vivo by inhibiting the FOS/JUN pathway. Our approach of a proof-of-principle platform, which uses isogenic hESCs for functional evaluation of GWAS-identified loci and identification of a drug candidate that rescues gene-specific defects, paves the way for precision therapy of metabolic diseases.

Identification of key amino acid residues responsible for internal and external pH sensitivity of Orai1/STIM1 channels.

Changes of intracellular and extracellular pH are involved in a variety of physiological and pathological processes, in which regulation of the Ca(2+) release activated Ca(2+) channel (I CRAC) by pH has been implicated. Ca(2+) entry mediated by I CRAC has been shown to be regulated by acidic or alkaline pH. Whereas several amino acid residues have been shown to contribute to extracellular pH (pHo) sensitivity, the molecular mechanism for intracellular pH (pHi) sensitivity of Orai1/STIM1 is not fully understood. By investigating a series of mutations, we find that the previously identified residue E106 is responsible for pHo sensitivity when Ca(2+) is the charge carrier. Unexpectedly, we identify that the residue E190 is responsible for pHo sensitivity when Na(+) is the charge carrier. Furthermore, the intracellular mutant H155F markedly diminishes the response to acidic and alkaline pHi, suggesting that H155 is responsible for pHi sensitivity of Orai1/STIM1. Our results indicate that, whereas H155 is the intracellular pH sensor of Orai1/STIM1, the molecular mechanism of external pH sensitivity varies depending on the permeant cations. As changes of pH are involved in various physiological/pathological functions, Orai/STIM channels may be an important mediator for various physiological and pathological processes associated with acidosis and alkalinization.

A phase 2 study of idelalisib plus rituximab in treatment-naïve older patients with chronic lymphocytic leukemia.

Idelalisib is a first-in-class oral inhibitor of PI3Kδ that has shown substantial activity in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). To evaluate idelalisib as initial therapy, 64 treatment-naïve older patients with CLL or small lymphocytic leukemia (median age, 71 years; range, 65-90) were treated with rituximab 375 mg/m(2) weekly ×8 and idelalisib 150 mg twice daily continuously for 48 weeks. Patients completing 48 weeks without progression could continue to receive idelalisib on an extension study. The median time on treatment was 22.4 months (range, 0.8-45.8+). The overall response rate (ORR) was 97%, including 19% complete responses. The ORR was 100% in patients with del(17p)/TP53 mutations and 97% in those with unmutated IGHV. Progression-free survival was 83% at 36 months. The most frequent (>30%) adverse events (any grade) were diarrhea (including colitis) (64%), rash (58%), pyrexia (42%), nausea (38%), chills (36%), cough (33%), and fatigue (31%). Elevated alanine transaminase/aspartate transaminase was seen in 67% of patients (23% grade ≥3). The combination of idelalisib and rituximab was highly active, resulting in durable disease control in treatment-naïve older patients with CLL. These results support the further development of idelalisib as initial treatment of CLL. This study is registered at ClinicalTrials.gov as #NCT01203930.

Role of TRP channels in the cardiovascular system.

The transient receptor potential (TRP) superfamily consists of a large number of nonselective cation channels with variable degree of Ca(2+)-permeability. The 28 mammalian TRP channel proteins can be grouped into six subfamilies: canonical, vanilloid, melastatin, ankyrin, polycystic, and mucolipin TRPs. The majority of these TRP channels are expressed in different cell types including both excitable and nonexcitable cells of the cardiovascular system. Unlike voltage-gated ion channels, TRP channels do not have a typical voltage sensor, but instead can sense a variety of other stimuli including pressure, shear stress, mechanical stretch, oxidative stress, lipid environment alterations, hypertrophic signals, and inflammation products. By integrating multiple stimuli and transducing their activity to downstream cellular signal pathways via Ca(2+) entry and/or membrane depolarization, TRP channels play an essential role in regulating fundamental cell functions such as contraction, relaxation, proliferation, differentiation, and cell death. With the use of targeted deletion and transgenic mouse models, recent studies have revealed that TRP channels are involved in numerous cellular functions and play an important role in the pathophysiology of many diseases in the cardiovascular system. Moreover, several TRP channels are involved in inherited diseases of the cardiovascular system. This review presents an overview of current knowledge concerning the physiological functions of TRP channels in the cardiovascular system and their contributions to cardiovascular diseases. Ultimately, TRP channels may become potential therapeutic targets for cardiovascular diseases.

Idelalisib, a selective inhibitor of phosphatidylinositol 3-kinase-δ, as therapy for previously treated indolent non-Hodgkin lymphoma.

Idelalisib (GS-1101, CAL-101), an oral inhibitor of phosphatidylinositol 3-kinase-δ, was evaluated in a phase I study in 64 patients with relapsed indolent non-Hodgkin lymphoma (iNHL). Patients had a median (range) age of 64 (32-91) years, 34 (53%) had bulky disease (≥1 lymph nodes ≥5 cm), and 37 (58%) had refractory disease. Patients had received a median (range) of 4 (1-10) prior therapies. Eight dose regimens of idelalisib were evaluated; idelalisib was taken once or twice daily continuously at doses ranging from 50 to 350 mg. After 48 weeks, patients still benefitting (n = 19; 30%) enrolled into an extension study. Adverse events (AEs) occurring in 20% or more patients (total%/grade ≥3%) included diarrhea (36/8), fatigue (36/3), nausea (25/3), rash (25/3), pyrexia (20/3), and chills (20/0). Laboratory abnormalities included neutropenia (44/23), anemia (31/5), thrombocytopenia (25/11), and serum transaminase elevations (48/25). Twelve (19%) patients discontinued therapy due to AEs. Idelalisib induced disease regression in 46/54 (85%) of evaluable patients achieving an overall response rate of 30/64 (47%), with 1 patient having a complete response (1.6%). Median duration of response was 18.4 months, median progression-free survival was 7.6 months. Idelalisib is well tolerated and active in heavily pretreated, relapsed/refractory patients with iNHL. These trials were registered at clinicaltrials.gov as NCT00710528 and NCT01090414.

Idelalisib, an inhibitor of phosphatidylinositol 3-kinase p110δ, for relapsed/refractory chronic lymphocytic leukemia.

In a phase 1 trial, idelalisib (GS-1101, CAL-101), a selective inhibitor of the lipid kinase PI3Kδ, was evaluated in 54 patients with relapsed/refractory chronic lymphocytic leukemia (CLL) with adverse characteristics including bulky lymphadenopathy (80%), extensive prior therapy (median 5 [range 2-14] prior regimens), treatment-refractory disease (70%), unmutated IGHV (91%), and del17p and/or TP53 mutations (24%). Patients were treated at 6 dose levels of oral idelalisib (range 50-350 mg once or twice daily) and remained on continuous therapy while deriving clinical benefit. Idelalisib-mediated inhibition of PI3Kδ led to abrogation of Akt phosphorylation in patient CLL cells and significantly reduced serum levels of CLL-related chemokines. The most commonly observed grade ≥3 adverse events were pneumonia (20%), neutropenic fever (11%), and diarrhea (6%). Idelalisib treatment resulted in nodal responses in 81% of patients. The overall response rate was 72%, with 39% of patients meeting the criteria for partial response per IWCLL 2008 and 33% meeting the recently updated criteria of PR with treatment-induced lymphocytosis.(1,2) The median progression-free survival for all patients was 15.8 months. This study demonstrates the clinical utility of inhibiting the PI3Kδ pathway with idelalisib. Our findings support the further development of idelalisib in patients with CLL. These trials were registered at clinicaltrials.gov as #NCT00710528 and #NCT01090414.

Identification and characterization of genes required for compensatory growth in Drosophila.

To maintain tissue homeostasis, some organs are able to replace dying cells with additional proliferation of surviving cells. Such proliferation can be localized (e.g., a regeneration blastema) or diffuse (compensatory growth). The relationship between such growth and the growth that occurs during development has not been characterized in detail. Drosophila melanogaster larval imaginal discs can recover from extensive damage, producing normally sized adult organs. Here we describe a system using genetic mosaics to screen for recessive mutations that impair compensatory growth. By generating clones of cells that carry a temperature-sensitive cell-lethal mutation, we conditionally ablate patches of tissue in the imaginal disc and assess the ability of the surviving sister clones to replace the lost tissue. We have used this system together with a modified whole-genome resequencing (WGS) strategy to identify several mutations that selectively compromise compensatory growth. We find specific alleles of bunched (bun) and Ribonucleoside diphosphate reductase large subunit (RnrL) reduce compensatory growth in the imaginal disc. Other genes identified in the screen, including two alleles of Topoisomerase 3-alpha (Top3α), while also required for developmental growth, appear to have an enhanced requirement during compensatory growth. Compensatory growth occurs at a higher rate than normal growth and may therefore have features in common with some types of overgrowth. Indeed, the RnrL allele identified compromises both these types of altered growth and mammalian ribonucleotide reductase and topoisomerases are targets of anticancer drugs. Finally, the approach we describe is applicable to the study of compensatory growth in diverse tissues in Drosophila.

Intravesical resiniferatoxin for the treatment of interstitial cystitis: a randomized, double-blind, placebo controlled trial.

PURPOSE: Interstitial cystitis is a painful bladder condition of unknown etiology and poorly understood pathophysiology. Current therapies have met with limited success. Vanilloid receptor agonists such as resiniferatoxin (RTX) desensitize C-fibers that transmit pain; it is hypothesized that such drugs will be effective in the treatment of interstitial cystitis and painful bladder syndrome by decreasing the pain that leads to urinary frequency and urgency. MATERIALS AND METHODS: A randomized, double-blind, placebo controlled study was conducted in 163 patients with interstitial cystitis. Participants were randomly assigned to receive a single intravesical dose of 50 ml of either RTX 0.01 microM, 0.05 microM, 0.10 microM, or placebo. Safety and efficacy was evaluated over 12 weeks. The primary efficacy endpoint was the Global Response Assessment, a 7-point scale rating overall change in symptoms of interstitial cystitis after 4 weeks. Secondary efficacy endpoints included reduction in pain, urgency, frequency, nocturia, average void volume, and the O'Leary-Sant Symptom and Problem Indexes. RESULTS: RTX did not improve overall symptoms, pain, urgency, frequency, nocturia, or average void volume during 12 weeks followup. RTX resulted in a dose-dependent increase in the incidence of instillation pain, but was otherwise generally well tolerated. CONCLUSIONS: In the largest prospective, randomized clinical trial reported to date with intravesical vanilloid therapy, single administration of RTX at doses of 0.01 microM to 0.10 microM was not effective in patients with interstitial cystitis.