Improved EGFR mutation detection using combined exosomal RNA and circulating tumor DNA in NSCLC patient plasma.

Background: A major limitation of circulating tumor DNA (ctDNA) for somatic mutation detection has been the low level of ctDNA found in a subset of cancer patients. We investigated whether using a combined isolation of exosomal RNA (exoRNA) and cell-free DNA (cfDNA) could improve blood-based liquid biopsy for EGFR mutation detection in non-small-cell lung cancer (NSCLC) patients. Patients and methods: Matched pretreatment tumor and plasma were collected from 84 patients enrolled in TIGER-X (NCT01526928), a phase 1/2 study of rociletinib in mutant EGFR NSCLC patients. The combined isolated exoRNA and cfDNA (exoNA) was analyzed blinded for mutations using a targeted next-generation sequencing panel (EXO1000) and compared with existing data from the same samples using analysis of ctDNA by BEAMing. Results: For exoNA, the sensitivity was 98% for detection of activating EGFR mutations and 90% for EGFR T790M. The corresponding sensitivities for ctDNA by BEAMing were 82% for activating mutations and 84% for T790M. In a subgroup of patients with intrathoracic metastatic disease (M0/M1a; n = 21), the sensitivity increased from 26% to 74% for activating mutations (P = 0.003) and from 19% to 31% for T790M (P = 0.5) when using exoNA for detection. Conclusions: Combining exoRNA and ctDNA increased the sensitivity for EGFR mutation detection in plasma, with the largest improvement seen in the subgroup of M0/M1a disease patients known to have low levels of ctDNA and poses challenges for mutation detection on ctDNA alone. Clinical Trials: NCT01526928.

Death receptor-based enrichment of Cas9-expressing cells.

BACKGROUND: The CRISPR/Cas9 genome editing system has greatly facilitated and expanded our capacity to engineer mammalian genomes, including targeted gene knock-outs. However, the phenotyping of the knock-out effect requires a high DNA editing efficiency. RESULTS: Here, we report a user-friendly strategy based on the extrinsic apoptosis pathway that allows enrichment of a polyclonal gene-edited cell population, by selecting Cas9-transfected cells that co-express dominant-negative mutants of death receptors. The extrinsic apoptosis pathway can be triggered in many mammalian cell types, and ligands are easy to produce, do not require purification and kill much faster than the state-of-the-art selection drug puromycin. Stringent assessment of our advanced selection strategy via Sanger sequencing, T7 endonuclease I (T7E1) assay and direct phenotyping confirmed a strong and rapid enrichment of Cas9-expressing cell populations, in some cases reaching up to 100 % within one hour. Notably, the efficiency of target DNA cleavage in these enriched cells reached high levels that exceeded the reliable range of the T7E1 assay, a conclusion that can be generalized for editing efficiencies above 30 %. Moreover, our data emphasize that the insertion and deletion pattern induced by a specific gRNA is reproducible across different cell lines. CONCLUSIONS: The workflow and the findings reported here should streamline a wide array of future low- or high-throughput gene knock-out screens, and should largely improve data interpretation from CRISPR experiments.

[Schooling of patients exhibiting Autism Spectrum Disorders without mental retardation]. / La scolarisation des patients atteints par des troubles du spectre autistique sans retard mental.

INTRODUCTION: Autism Spectrum Disorders belong to Pervasive Development Disorders. Although access to education is recommended by the French National High Authority for Health (HAS), the practice remains limited and the reasons for the low education rate of these children have still not been sufficiently explored in the literature. OBJECTIVE: The main objective of this study was to analyze the links between Autism Spectrum Disorder without mental retardation, psychiatric comorbidity and education. The secondary objective was to analyze the cognitive and contextual factors that could limit educational inclusion. METHOD: Eighty-three autistic patients (3-18years old; 73 males and 10 females) with childhood autism, atypical autism or Asperger's syndrome (criteria from the International Classification of Diseases-10) without mental retardation and in education were assessed at the Alpine Centre for Early Diagnosis of Autism. The sample included 45 subjects with childhood autism, 12 subjects with atypical autism and 26 subjects with Asperger's syndrome. The diagnosis was based on the Autism Diagnostic Interview Revised (ADI-R), in accordance with the recommendations of the HAS, the Autism Diagnostic Observation Schedule (ADOS) and the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV). RESULTS: Our results showed that childhood autism and atypical autism were mainly found in nursery and primary school, whereas Asperger's syndrome was mainly found in secondary school (Chi(2)=18.23; df=6; P<.006). Individuals with childhood autism and atypical autism were more likely to receive the support of a special educational assistant (Chi(2)=15.61; df=2; P<.000) and underwent a higher number of consultations and treatment episodes than those with Asperger's syndrome (Chi(2)=27.83; df=14; P<.015). The cognitive profiles obtained with the WISC-IV also differed: the Verbal Comprehension Index (VCI) and Working Memory Index (WMI) were higher for Asperger's syndrome than for childhood autism and atypical autism (respectively, F=23.11, P<.000; df=2; partial η(2)=.576 and F=8.06, P<.001; df=2; partial η(2)=.357). Linear regression showed that the VCI and Processing Speed Index (PSI) were inversely correlated to the number of hours spent with a special educational assistant: the lower these indexes, the greater the amount of time spent with a special educational assistant. No link was found between psychiatric comorbidity, type of psychological and psychiatric treatment, and education. DISCUSSION: The use of special educational assistants seems to be linked to the diagnosis of Autism Spectrum Disorders and neuropsychological functioning, as assessed by WISC-IV, along a continuum that ranges from childhood autism (more needs and deficits) to atypical autism to Asperger's syndrome. The Verbal Comprehension Index (VCI) and the Processing Speed Index (PSI) could be used to evaluate the number of hours of support needed by children and to better target the deficits and specific needs of children without mental retardation who are in education. A study on a larger scale could help to more closely address the question of the cognitive abilities of children with Autism Spectrum Disorder without mental retardation, so as to better help them in their education.

Preoperative left ventricular hypertrophy is associated with reduced patient survival after liver transplantation.

UNLABELLED: Left ventricular hypertrophy (LVH) has been described in the context of cirrhotic cardiomyopathy. The influence of LVH on survival of liver transplant (LT) recipients has not been clarified. Therefore, we evaluated the effect of LVH on survival in LT recipients. In total, data from 352 LT patients were analyzed. LVH was diagnosed by echocardiographic measurement of left ventricular wall thickness before LT. Patients were followed up for a mean of 4.2 yr. LVH was diagnosed in 135 (38.4%) patients. Patients with LVH had significantly more frequently male gender (p = 0.046), diastolic dysfunction (p < 0.001), and hepatocellular carcinoma (HCC; p = 0.004). Furthermore, LVH patients were older (p < 0.001) and had a higher body mass index (BMI; p = 0.001). There was no difference in frequency of arterial hypertension, pre-transplant diabetes mellitus, or etiology of liver cirrhosis. Patients without LVH had a better survival (log rank: p = 0.05) compared with LVH patients. In a multivariate Cox regression LVH (p = 0.031), end-stage renal disease (ESRD; p = 0.003) and lack of arterial hypertension (p = 0.004) but not MELD score (p = 0.885) were associated with poorer survival. CONCLUSION: LVH is frequently diagnosed in patients on the waiting list and influences survival after LT.

Diet-dependent function of the extracellular matrix proteoglycan Lumican in obesity and glucose homeostasis.

OBJECTIVE: Extracellular matrix remodeling is required for adipose expansion under increased caloric intake. In turn, inhibited expandability due to aberrant collagen deposition promotes insulin resistance and progression towards the metabolic syndrome. An emerging role for the small leucine-rich proteoglycan Lumican in metabolically driven nonalcoholic fatty liver disease sparks an interest in further understanding its role in diet-induced obesity and metabolic complications. METHODS: Whole body ablation of Lumican (Lum-/-) gene and adeno-associated virus-mediated over-expression were used in combination with control or high fat diet to assess energy balance, glucose homeostasis as well as adipose tissue health and remodeling. RESULTS: Lumican was found to be particularly enriched in the stromal cells isolated from murine gonadal white adipose tissue. Likewise murine and human visceral fat showed a robust increase in Lumican as compared to fat from the subcutaneous depot. Lumican null female mice exhibited moderately increased fat mass, decreased insulin sensitivity and increased liver triglycerides in a diet-dependent manner. These changes coincided with inflammation in adipose tissue and no overt effects in adipose expandability, i.e. adipocyte formation and hypertrophy. Lumican over-expression in visceral fat and liver resulted in improved insulin sensitivity and glucose clearance. CONCLUSIONS: These data indicate that Lumican may represent a functional link between the extracellular matrix, glucose homeostasis, and features of the metabolic syndrome.

Frequency of calpain-3 c.550delA mutation in limb girdle muscular dystrophy type 2 and isolated hyperCKemia in German patients.

OBJECTIVE: Calpain-3 deficiency is the most common cause of autosomal-recessive limb girdle muscular dystrophy (LGMD2). The c.550delA mutation in the CAPN3 gene was frequently identified in LGMD2A patients from Eastern Europe and is considered a Slavic founder mutation. METHODS: We screened for the c.550delA mutation in unrelated German patients with LGMD2 (n = 98) and in patients with asymptomatic or minimally symptomatic (myalgia or fatigue) hyperCKemia of unknown origin (n = 102). Results of Western blot analysis were available in 75 patients with LGMD2 and 65 patients with hyperCKemia. In samples that were heterozygous for the c.550delA mutation, the whole CAPN3 gene was analyzed by sequencing in order to detect the second mutation. RESULTS: The c.550delA mutation was found in 8.1% of LGMD2 (n = 1 homozygous, n = 7 heterozygous) and 1.9% of hyperCKemia patients (n = 2 heterozygous). In 8 of the 9 hetrozygous patients, a second CAPN3 mutation was identified by direct sequencing. Two mutations (Val509Phe and Gln565Stop) have not been reported before. Absent or deficient calpain-3 protein in Western blot analysis was found in 22.5% of the LGMD2 patients and 11% of the patients with hyperCKemia. Western blot results were available in 9 out of the 10 patients with genetically confirmed LGMD2A and were clearly abnormal in 6 patients, suspicious in 2 and entirely normal in 1. Two LGMD2 patients with the c.550delA mutation and onset within the first 2 decades had joint contractures. Muscle biopsy revealed inflammatory changes in three patients. CONCLUSION: The CAPN3 gene mutation c.550delA is rather frequently observed in German patients with LGMD2, but also occasionally in cases with isolated hyperCKemia.

Interface Adhesion and Structural Characterization of Rolled-up GaAs/In0.2Ga0.8As Multilayer Tubes by Coherent Phonon Spectroscopy.

We present a detailed experimental and theoretical study of the acoustic phonon modes in rolled-up multilayers with thickness of the layers in the nanometre and diameters in the micrometre range. We compare our results to planar, unrolled multilayers grown by molecular beam epitaxy. For the planar multilayers the experimentally obtained acoustic modes exhibit properties of a superlattice and match well to calculations obtained by the Rytov model. The rolled-up superlattice tubes show intriguing differences compared to the planar structures which can be attributed to the imperfect adhesion between individual tube windings. A transfer matrix method including a massless spring accounting for the imperfect adhesion between the layers yields good agreement between experiment and calculations for up to five windings. Areas with sufficient mechanical coupling between all windings can be distinguished by their acoustic mode spectrum from areas where individual windings are only partially in contact. This allows the spatially resolved characterization of individual tubes with micrometre spatial resolution where areas with varying interface adhesion can be identified.

Progressing MoodSwings. The upgrade and evaluation of MoodSwings 2.0: An online intervention for bipolar disorder.

MoodSwings 2.0 is a self-guided online intervention for bipolar disorder. The intervention incorporates technological improvements on an earlier validated version of the intervention (MoodSwings 1.0). The previous MoodSwings trial provides this study with a unique opportunity to progress previous work, whilst being able to take into consideration lesson learnt, and technological enhancements. The structure and technology of MoodSwings 2.0 are described and the relevance to other online health interventions is highlighted. An international team from Australia and the US updated and improved the programs content pursuant to changes in DSM-5, added multimedia components and included larger numbers of participants in the group discussion boards. Greater methodological rigour in this trial includes an attention control condition, quarterly telephone assessments, and red flag alerts for significant clinical change. This paper outlines these improvements, including additional security and safety measures. A 3 arm RCT is currently evaluating the enhanced program to assess the efficacy of MS 2.0; the primary outcome is change in depressive and manic symptoms. To our knowledge this is the first randomized controlled online bipolar study with a discussion board attention control and meets the key methodological criteria for online interventions.

The cartilage-derived, C-type lectin (CLECSF1): structure of the gene and chromosomal location.

Cartilage is a tissue that is primarily extracellular matrix, the bulk of which consists of proteoglycan aggregates constrained within a collagen framework. Candidate components that organize the extracellular assembly of the matrix consist of collagens, proteoglycans and multimeric glycoproteins. We describe the human gene structure of a potential organizing factor, a cartilage-derived member of the C-type lectin superfamily (CLECSF1; C-type lectin superfamily) related to the serum protein, tetranectin. We show by Northern analysis that this protein is restricted to cartilage and locate the gene on chromosome 16q23. We have characterized 10.9 kb of sequence upstream of the first exon. Similarly to human tetranectin, there are three exons. The residues that are conserved between CLECSF1 and tetranectin suggest that the cartilage-derived protein forms a trimeric structure similar to that of tetranectin, with three N-terminal alpha-helical domains aggregating through hydrophobic faces. The globular, C-terminal domain that has been shown to bind carbohydrate in some members of the family and plasminogen in tetranectin, is likely to have a similar overall structure to that of tetranectin.

Single-nucleotide polymorphisms in soybean.

Single-nucleotide polymorphisms (SNPs) provide an abundant source of DNA polymorphisms in a number of eukaryotic species. Information on the frequency, nature, and distribution of SNPs in plant genomes is limited. Thus, our objectives were (1) to determine SNP frequency in coding and noncoding soybean (Glycine max L. Merr.) DNA sequence amplified from genomic DNA using PCR primers designed to complete genes, cDNAs, and random genomic sequence; (2) to characterize haplotype variation in these sequences; and (3) to provide initial estimates of linkage disequilibrium (LD) in soybean. Approximately 28.7 kbp of coding sequence, 37.9 kbp of noncoding perigenic DNA, and 9.7 kbp of random noncoding genomic DNA were sequenced in each of 25 diverse soybean genotypes. Over the >76 kbp, mean nucleotide diversity expressed as Watterson's theta was 0.00097. Nucleotide diversity was 0.00053 and 0.00111 in coding and in noncoding perigenic DNA, respectively, lower than estimates in the autogamous model species Arabidopsis thaliana. Haplotype analysis of SNP-containing fragments revealed a deficiency of haplotypes vs. the number that would be anticipated at linkage equilibrium. In 49 fragments with three or more SNPs, five haplotypes were present in one fragment while four or less were present in the remaining 48, thereby supporting the suggestion of relatively limited genetic variation in cultivated soybean. Squared allele-frequency correlations (r(2)) among haplotypes at 54 loci with two or more SNPs indicated low genome-wide LD. The low level of LD and the limited haplotype diversity suggested that the genome of any given soybean accession is a mosaic of three or four haplotypes. To facilitate SNP discovery and the development of a transcript map, subsets of four to six diverse genotypes, whose sequence analysis would permit the discovery of at least 75% of all SNPs present in the 25 genotypes as well as 90% of the common (frequency >0.10) SNPs, were identified.

Establishment and characterization of the follicular thyroid carcinoma cell line ML-1.

The present study focuses on the establishment and characterization of a new follicular thyroid carcinoma cell line. The human cell line ML-1 was derived from a dedifferentiated follicular thyroid carcinoma relapse, which progressed despite preceding surgery followed by two radioiodine therapies. More than 90% of the cells of this line express thyroglobulin, chondroitin sulfate, and vimentin antigens, but only about 70% show cytokeratin filaments and a negative surface charge density such as human erythrocytes. More importantly, cells of this line are able to take up iodine and/or glucose both in vitro and in vivo and to secrete thyroglobulin, chondroitin sulfate, and fibronectin into the interstitial space. In addition, triiodothyronine is released constitutively into culture supernatants. Moreover, it is also suitable for xenotransplantation studies because it is tumorigenic in NMRI nude mice in vivo. The cell line forms tumors with follicular structures when transplanted to nude mice. Due to these unique features the ML-1 cell line can be considered as a very suitable test model for pharmacological and cell biological studies. Since chemicals may interfere with the production of thyroid hormones, this cell line represents also a tool for toxicological investigations.

Differential effects of growth hormone on cardiomyocyte and extracellular matrix protein remodeling following experimental myocardial infarction.

OBJECTIVES: Growth hormone (GH) causes cardiomyocyte hypertrophy without development of fibrosis in the normal rat heart. The aim of this study was to evaluate the effects of GH on cardiac remodeling following experimental myocardial infarction (MI). METHODS: Following ligation of the left coronary artery or sham operation, rats were randomized to receive 2 IU GH/kg/day or vehicle for four weeks (n = 140). Extracellular matrix proteins were assessed in the non-infarcted myocardium of the posterior wall using immunohistochemistry and automatic image analysis. In addition, cardiomyocyte size was measured. RESULTS: Compared to sham, vehicle-treated rats with moderate (20-40%) and large (> 40%) infarct size showed left ventricular (LV)-dilatation, reduced fractional shortening as well as increases in LV end-diastolic and right atrial pressures, LV/body weight (BW) ratio and LV posterior wall thickness. Compared to vehicle-treated MI-rats, treatment with GH considerably increased fractional shortening and attenuated LV-dilatation. Vehicle-treated MI-rats displayed progressive increases in cardiomyocyte width and deposition of collagen I, compared to sham rats. Treatment with GH nearly doubled the increase in cardiomyocyte width and reduced collagen I accumulation by 50%. CONCLUSIONS: Our study demonstrates that GH, given early after large MI, elicits a unique pattern of structural effects characterized by enhanced cardiomyocyte hypertrophy and reduced adaptive fibrosis. This attenuation of pathological remodeling translates into a significant improvement in systolic and diastolic LV-function.

Development of heart failure following isoproterenol administration in the rat: role of the renin-angiotensin system.

OBJECTIVE: High dosages of catecholamines induce cardiomyocyte necrosis and interstitial fibrosis in rats. We investigated whether this initial damage is followed by the development of heart failure and assessed the particular role of the renin-angiotensin system using ramipril. METHODS AND RESULTS: Following the administration of 0 mg or 150 mg isoproterenol/kg 6 groups of Wistar rats were followed for 2 or 16 weeks: Sham, isoproterenol, isoproterenol + ramipril. Isoproterenol induced significant increases of echocardiographically measured left ventricular end-diastolic posterior wall thickness and dimension, whereas ramipril treatment significantly attenuated these changes. Left ventricular end-diastolic pressure was markedly increased in isoproterenol-treated rats and normalized following ramipril. Isoproterenol rats were further characterized by hormonal activations including transient elevations of plasma renin activity, aldosterone and cardiac angiotensin converting enzyme activity. Histomorphological characterization of isoproterenol-treated hearts demonstrated cardiomyocyte necrosis and reparative fibrosis. Ramipril treatment only slightly reduced the amount of necrosis as well as the expression of extracellular matrix proteins. CONCLUSIONS: In rats, a toxic dosage of isoproterenol caused characteristic myocardial damage that subsequently resulted in mild heart failure. Ramipril administration following isoproterenol was highly effective to attenuate hemodynamic and hormonal alterations as well as the development of left ventricular hypertrophy, but had only little influence on the expression of extracellular matrix proteins. Since angiotensin converting enzyme inhibition had no impact on the initial myocardial injury, the development of heart failure in this model seems to require functional integrity of the renin-angiotensin system.

New onset of diabetes after transplantation is associated with improved patient survival after liver transplantation due to confounding factor.

BACKGROUND: The influence of NODAT on survival of liver transplant recipients has not been clarified. Therefore, we evaluated the effect of NODAT on survival in LT recipients. METHODS: Data from 352 LT patients were totally analyzed. 97 patients with pretransplant diabetes mellitus were excluded, and 255 patients without diabetes mellitus at time of transplantation were included. RESULTS: NODAT was diagnosed in 41 patients (16.1%). There was no difference in frequency of NODAT according to the etiology of liver cirrhosis. NODAT was associated with a higher body weight (p=0.004) and BMI (p=0.002) 5years after LT, but not with weight gain (p=0.201) or increase in BMI (p=0.335) 5years after LT. HbA1c 5years after LT was significantly higher in patients with NODAT (p=0.001), but mean HbA1c still remained lower than 6.5% (6.4(±1.2) %). Patients with NODAT showed better survival rates (log rank: p=0.002) compared to LT recipients without diabetes. According to all existing knowledge of diabetes mellitus (DM) better survival cannot be a direct effect of this disease. Our results are rather influenced by an not known confounding factor (possibly recovery from cachexia) associated with better survival and NODAT, while complications of NODAT will not appear during the relatively short postoperative time and observation period (mean follow up 6.08 (±2.67) years). CONCLUSION: NODAT is frequently diagnosed in LT recipients and is associated with an improved 5year survival after LT due to a not exactly known confounding factor.

Progress in adeno-associated virus type 2 vector production: promises and prospects for clinical use.

Vectors derived from the human parvovirus AAV-2 (adeno-associated virus type 2) are among the most promising gene delivery vehicles currently being developed. These vectors are not only capable of transducing a large variety of human cell types in vitro and in vivo, but in immunocompetent animal models can establish long-term gene expression without being pathogenic to the recipient. However, a limitation of this vector system with respect to its clinical application has long been the laborious work needed to prepare high-titer and pure AAV-2 vector stocks. A number of improvements to the basic manufacturing protocol have recently been reported that now allow the production of AAV-2 vectors of significantly higher quality and quantity. This article considers the most relevant approaches taken so far, which include modifications to the conventional transfection/infection protocol as well as the development of helper virus-free packaging methods and the establishment of vector producer cell lines. The various novel protocols are discussed, including their advantages and drawbacks, with a particular focus being put on their prospects for clinical use. Despite these advancements, the development of an ideal AAV-2 vector production method fully suiting clinical requirements obviously remains a challenging issue.

Novel tools for production and purification of recombinant adenoassociated virus vectors.

Standard protocols for the generation of adenoassociated virus type 2 (AAV-2)-based vectors for human gene therapy applications require cotransfection of cells with a recombinant AAV (rAAV) vector plasmid and a packaging plasmid that provides the AAV rep and cap genes. The transfected cells must also be overinfected with a helper virus, e.g., adenovirus (Ad), which delivers multiple helper functions necessary for rAAV production. Therefore, rAAV stocks produced using these protocols are contaminated with helper adenovirus. The generation of a novel packaging/helper plasmid, pDG, containing all AAV and Ad functions required for amplification and packaging of AAV vector plasmids, is described here. Cotransfection of cells with pDG and an AAV vector plasmid was sufficient for production of infectious rAAV, resulting in helper virus-free rAAV stocks. The rAAV titers obtained using pDG as packaging plasmid were up to 10-fold higher than those achieved using conventional protocols for rAAV production. Replacement of the AAV-2 p5 promoter by an MMTV-LTR promoter in pDG led to reduced expression of Rep78/68; however, expression of the VP proteins was significantly increased compared with VP levels from standard packaging plasmids. Immunofluorescence analyses showed that the strong accumulation of VP proteins in pDG-transfected cells resulted in enhanced AAV capsid assembly, which is limiting for efficient rAAV production. Furthermore, using a monoclonal antibody highly specific for AAV-2 capsids (A20), an rAAV affinity purification procedure protocol was established. The application of the tools described here led to a significant improvement in recombinant AAV vector production and purification.

Purification of recombinant adeno-associated virus by iodixanol gradient ultracentrifugation allows rapid and reproducible preparation of vector stocks for gene transfer in the nervous system.

Recombinant adeno-associated virus (rAAV) vectors have become attractive tools for in vivo gene transfer. The production and purification of high-titer rAAV vector stocks for experimental and therapeutic gene transfer continue to undergo improvement. Standard rAAV vector purification protocols include the purification of the vector by cesium chloride (CsCl)-density gradient centrifugation followed by extensive desalination via dialysis against a physiological buffer for in vivo use. These procedures are extremely time consuming and frequently result in a substantial loss of the infectious vector titer. As an alternative to CsCl we have investigated the use of Iodixanol, an X-ray contrast solution, as the density-gradient medium. Purification of rAAV vectors by Iodixanol shortened the centrifugation period to 3 hr and resulted in reproducible concentration and purification of rAAV-vector stocks. We show that injection of rAAV derived from an Iodixanol gradient can be used for in vivo gene transfer applications in the brain and spinal cord without detectable cytopathic effects and directing stable transgene expression for at least 2 months.

Blockade of the renin-angiotensin system in cardiac pressure-overload hypertrophy in rats.

Left ventricular hypertrophy in response to pressure overload may be modified by neurohumoral activation. To investigate the contribution of the renin-angiotensin system, we studied rats after banding of the ascending aorta that developed severe left ventricular hypertrophy associated with normal plasma renin but elevated cardiac angiotensin-converting enzyme (ACE) levels. Rats were treated with vehicle, ACE inhibitor (ramipril), angiotensin II type 1 receptor antagonist (losartan), or vasodilator (hydralazine) during weeks 7 through 12 after aortic banding. A significant regression of left ventricular mass index as determined by serial echocardiography was observed in ramipril- and losartan-treated groups during weeks 9 through 12 after banding, whereas hypertrophy further increased in vehicle- and hydralazine-treated groups. Twelve weeks after banding, relative left ventricular weights and myocyte widths were markedly increased in vehicle- and hydralazine-treated groups, whereas ramipril and losartan significantly reduced these parameters. In addition, molecular adaptations in left ventricular hypertrophy, such as upregulation of left ventricular atrial natriuretic peptide and downregulation of sarcoplasmic reticulum Ca(2+)-ATPase mRNA levels, were blunted by ramipril or losartan treatment. Hypertrophic regression was associated with reduced mortality in rats treated with ramipril (11%) and losartan (13%) versus hydralazine (20%) and vehicle (31%). Thus, the renin-angiotensin system may be involved in the maintenance of chronic left ventricular hypertrophy. Blockade of the system may result in regression of the hypertrophic phenotype and improve survival in rats despite persistent pressure overload.