Impaired Cell Cycle Regulation in a Natural Equine Model of Asthma.

Recurrent airway obstruction (RAO) is a common and potentially debilitating lower airway disease in horses, which shares many similarities with human asthma. In susceptible horses RAO exacerbation is caused by environmental allergens and irritants present in hay dust. The objective of this study was the identification of genes and pathways involved in the pathology of RAO by global transcriptome analyses in stimulated peripheral blood mononuclear cells (PBMCs). We performed RNA-seq on PBMCs derived from 40 RAO affected and 45 control horses belonging to three cohorts of Warmblood horses: two half-sib families and one group of unrelated horses. PBMCs were stimulated with hay dust extract, lipopolysaccharides, a recombinant parasite antigen, or left unstimulated. The total dataset consisted of 561 individual samples. We detected significant differences in the expression profiles between RAO and control horses. Differential expression (DE) was most marked upon stimulation with hay dust extract. An important novel finding was a strong upregulation of CXCL13 together with many genes involved in cell cycle regulation in stimulated samples from RAO affected horses, in addition to changes in the expression of several HIF-1 transcription factor target genes. The RAO condition alters systemic changes observed as differential expression profiles of PBMCs. Those changes also depended on the cohort and stimulation of the samples and were dominated by genes involved in immune cell trafficking, development, and cell cycle regulation. Our findings indicate an important role of CXCL13, likely macrophage or Th17 derived, and the cell cycle regulator CDC20 in the immune response in RAO.

A new universal, standardized implant database for product identification: a unique tool for arthroplasty registries.

INTRODUCTION Every joint registry aims to improve patient care by identifying implants that have an inferior performance. For this reason, each registry records the implant name that has been used in the individual patient. In most registries, a paper-based approach has been utilized for this purpose. However, in addition to being time-consuming, this approach does not account for the fact that failure patterns are not necessarily implant specific but can be associated with design features that are used in a number of implants. Therefore, we aimed to develop and evaluate an implant product library that allows both time saving barcode scanning on site in the hospital for the registration of the implant components and a detailed description of implant specifications. MATERIALS AND METHODS A task force consisting of representatives of the German Arthroplasty Registry, industry, and computer specialists agreed on a solution that allows barcode scanning of implant components and that also uses a detailed standardized classification describing arthroplasty components. The manufacturers classified all their components that are sold in Germany according to this classification. The implant database was analyzed regarding the completeness of components by algorithms and real-time data. RESULTS The implant library could be set up successfully. At this point, the implant database includes more than 38,000 items, of which all were classified by the manufacturers according to the predefined scheme. Using patient data from the German Arthroplasty Registry, several errors in the database were detected, all of which were corrected by the respective implant manufacturers. CONCLUSIONS The implant library that was developed for the German Arthroplasty Registry allows not only on-site barcode scanning for the registration of the implant components but also its classification tree allows a sophisticated analysis regarding implant characteristics, regardless of brand or manufacturer. The database is maintained by the implant manufacturers, thereby allowing registries to focus their resources on other areas of research. The database might represent a possible global model, which might encourage harmonization between joint replacement registries enabling comparisons between joint replacement registries.

The localization and identification of candidate tumor suppressor genes involved in prostate cancer

Frequent loss of heterozygosity (LOH) at specific chromosomal regions are highly associated with the inactivation of tumor suppressor genes (TSGs) (Weinberg, 1991; Bishop, 1989). Chromosome 8p is the most frequently reported site of LOH (∼60%) in prostate cancer (PC), suggesting that there may be inactivated TSG(s) involved in PC on chromosome 8p. (Bergerheim et. al., 1991; Kagan et. al., 1995). In order to identify the smallest common regions of frequent LOH (SCLs) on chromosome 8, we screened 52 PC patient/tumor samples with 39 polymorphic markers in successive screenings. In the course of refining the SCLs, we identified 3 tumors with >6 Mb homozygous deletions (HZDs) at 8p22 and 8p21, suggesting the presence of candidate TSGs at both loci. These HZDs spanned the two SCLs at 8p22 (46%) and 8p21 (45%). The SCLs were narrowed to 3.2 cM at 8p22 and less than 3 cM at 8p21. ^ In order to identify candidate TSGs within the SCLs on 8p, two approaches were used. In the candidate gene approach, thirty genes that mapped to the SCLs were evaluated for expression in normal prostate and in PC cell lines. One of the candidate genes, Clusterin, showed decreased expression in 4/7 (57%) prostate cancer cell lines by Northern blot analysis. Clusterin will be further examined as a candidate TSG. ^ The second approach involved utilizing subtractive hybridization and hybrid affinity capture to generate pools of expressed sequence tags (ESTs) enriched for genes that are downregulated or deleted in PC and that map to specific regions of interest. We took advantage of a prostate cancer cell line (PC3) with a known HZD of a candidate TSG, CTNNA1 on 5q31, to develop and validate a model system. We then developed subtracted libraries enriched for 8p22 and 8p21 ESTs by this method, using two cell lines, MDAPCa-2b and PC3. The ESTs were cloned, and 40 were sequenced and evaluated for expression in normal prostate and PC cell lines. Three ESTs from the subtracted libraries, C2, C17 and F12, showed decreased expression in 29–57% of the prostate tumor cell lines studied, and will be further examined as candidate TSGs. ^

Identification and characterization of virulence factors in Enterococcus faecalis

Enterococci are one of the leading causes of nosocomial infections, and Enterococcus faecalis causes the majority of enterococcal infections. However, the mechanisms of enterococcal pathogenesis are still not yet understood. In our initial screening of E. faecalis strain OG1RF genomic libraries, autolysin and a homolog of a protein of Enterococcus faecium previously designated P54 were found to be two major antigens that reacted with human patient sera, and an antigen designated MH-1 antigen that reacted with serum from a endocarditis patient was also identified. To explore a possible role for these antigens in enterococcal infections, the genes encoding these three antigens were disrupted in Enterococcus faecalis OG1RF. ^ To explore a possible role of an E. faecalis gelatinase (encoded by gelE), which belongs to a family of Zn-metalloproteases that have been shown to be virulence factors in other organisms, in enterococcal infections, an insertion mutant was constructed in OG1RF and tested in the mouse peritonitis model. The mice infected with the gelE mutant showed a significantly prolonged survival compared to the wild type strain. To study the expression of gelE, the regions flanking gelE were sequenced. Sequence analysis of the gelE flanking regions revealed three genes (fsrA, fsrB and fsrC) upstream of gelE that show homology to the genes in a locus (agr) that globally regulates the expression of virulence factors in Staphylococcus aureus and one open reading frame (sprE) with homology to bacterial serine protease downstream of gelE. ^ In conclusion, in this study of identification of possible virulence factors in E. faecalis surface and secreted proteins, of three genes encoding antigens detected by human patient sera, none could be shown to effect virulence in the mouse peritonitis model. Inactivation of one of these antigens (autolysin) was shown to slightly increase the tolerance of E. faecalis to penicillin. A serine protease and a locus (fsr) that regulates the expression of gelE and sprE were shown to be important for enterococcal infection in the mouse peritonitis model. (Abstract shortened by UMI.)^

Cytochrome P450 4F isoforms in different species: Identification, gene regulation and putative roles in inflammation

The cytochrome P450 4F subfamily comprises a group of enzymes that metabolize derivatives of arachidonic acid such as prostaglandins, lipoxins leukotrienes and hydroxyeicosatetraenoic acids, which are important mediators involved in the inflammatory response. Therefore, we speculate that CYP4Fs might be able to modulate the extent of the inflammation by controlling of the tissue levels of these inflammatory mediators, especially, leukotriene B4. One way to provide support for this hypothesis is to test whether the expression of CYP4Fs changes under inflammatory conditions, since these changes are required to adjust the levels of inflammatory mediators. ^ A lipopolysacchride (LPS) induced rat inflammation model was used to analyze the expressions of rat CYP4F4 and CYP4F5 in liver and kidney. LPS administration did not change the constitutive expression level of CYP4F4 and CYP4F5. In liver, the expressions of CYP4F4 and CYP4F5 decreased to 50–60% of the untreated level. The same effect of LPS on CYP4F4 and CYP4F5 expression can be mimicked in hepatocyte primary cultures treated with LPS, indicating a direct of effect of LPS on hepatocytes. LPS treatment also decreased the activity of liver microsomes towards chlorpromazine, however, antibody inhibition study revealed that liver CYP4Fs are not the only players in metabolizing chlorpromazine. To study further the underlying mechanism, CYP4F5 gene was isolated, characterized, and the promoter region was defined. ^ Accumulating evidence showed that peroxisome proliferator-activated receptors (PPARs) play an active role in inflammation. To investigate the possible role of PPARα in regulating CYP4F expression by inflammation or by clofibrate treatment, the expressions of two new mouse 4F isoforms were analyzed in PPARα knockout mice upon LPS or clofibrate challenge. A novel induction of CYP4F15 by LPS and clofibrate was observed in kidney, and this effect is totally dependent on the presence of PPARα. Renal CYP4F16 expression was not affected by LPS or clofibrate in both (+/+) and (−/−) mice. In contrast, hepatic expressions of CYP4F15 and CYP4F16 were reduced significantly in (+/+) mice, but much less in (−/−) mice, suggesting that PPARα is partially responsible for this down-regulation. Clofibrate treatment reduced the expression of CYP4F16 in liver, but has no effect on CYP4F15 and PPARα does not have a role in hepatic CYP4F expression regulated by clofibrate. In general, CYP4Fs are regulated in an isoform-, tissue- and species-specific manner. ^ A human CYP4F isoform, CYP4F11, was isolated. The genomic structure was also solved by using database mining and bioinformatics tools. Localization of CYP4F11 to chromosome 19, 16 kb upstream of CYP4F2, suggests that human CYP4F genes may form a cluster on chromosome 19. This novel human 4F is highly expressed in liver, as well as in kidney, heart and skeletal muscle. Further study of the activity and gene regulation on CYP4F11 will provide us more insights into the physiological functions of CYP4F subfamily. ^

Some Identification Issues in Nonparametric Linear Models with Endogenous Regressors

In applied work economists often seek to relate a given response variable y to some causal parameter mu* associated with it. This parameter usually represents a summarization based on some explanatory variables of the distribution of y, such as a regression function, and treating it as a conditional expectation is central to its identification and estimation. However, the interpretation of mu* as a conditional expectation breaks down if some or all of the explanatory variables are endogenous. This is not a problem when mu* is modelled as a parametric function of explanatory variables because it is well known how instrumental variables techniques can be used to identify and estimate mu*. In contrast, handling endogenous regressors in nonparametric models, where mu* is regarded as fully unknown, presents di±cult theoretical and practical challenges. In this paper we consider an endogenous nonparametric model based on a conditional moment restriction. We investigate identification related properties of this model when the unknown function mu* belongs to a linear space. We also investigate underidentification of mu* along with the identification of its linear functionals. Several examples are provided in order to develop intuition about identification and estimation for endogenous nonparametric regression and related models.

Corruption and Growth Under Weak Identification

The goal of this paper is to revisit the influential work of Mauro [1995] focusing on the strength of his results under weak identification. He finds a negative impact of corruption on investment and economic growth that appears to be robust to endogeneity when using two-stage least squares (2SLS). Since the inception of Mauro [1995], much literature has focused on 2SLS methods revealing the dangers of estimation and thus inference under weak identification. We reproduce the original results of Mauro [1995] with a high level of confidence and show that the instrument used in the original work is in fact 'weak' as defined by Staiger and Stock [1997]. Thus we update the analysis using a test statistic robust to weak instruments. Our results suggest that under Mauro's original model there is a high probability that the parameters of interest are locally almost unidentified in multivariate specifications. To address this problem, we also investigate other instruments commonly used in the corruption literature and obtain similar results.

Comparison of a traditional and a multilevel Cox Proportional Hazards model

Hierarchically clustered populations are often encountered in public health research, but the traditional methods used in analyzing this type of data are not always adequate. In the case of survival time data, more appropriate methods have only begun to surface in the last couple of decades. Such methods include multilevel statistical techniques which, although more complicated to implement than traditional methods, are more appropriate. ^ One population that is known to exhibit a hierarchical structure is that of patients who utilize the health care system of the Department of Veterans Affairs where patients are grouped not only by hospital, but also by geographic network (VISN). This project analyzes survival time data sets housed at the Houston Veterans Affairs Medical Center Research Department using two different Cox Proportional Hazards regression models, a traditional model and a multilevel model. VISNs that exhibit significantly higher or lower survival rates than the rest are identified separately for each model. ^ In this particular case, although there are differences in the results of the two models, it is not enough to warrant using the more complex multilevel technique. This is shown by the small estimates of variance associated with levels two and three in the multilevel Cox analysis. Much of the differences that are exhibited in identification of VISNs with high or low survival rates is attributable to computer hardware difficulties rather than to any significant improvements in the model. ^

Identification and characterization of antigens and potential virulence factors in Enterococcus

Enterococci are normal flora in the human intestinal tract, and also one of the leading causes of nosocomial infections, with most of the clinical isolates being Enterococcus faecalis and Enterococcus faecium. Despite extensive studies on the antibiotic resistance, the pathogenicity of enterococci is not well understood, especially for E. faecium. To identify potential virulence factors based on their antigenicity during infection, E. faecium genomic libraries were constructed and screened using sera from patients with E. faecium endocarditis. ^ As one of my projects, total polysaccharides were extracted from E. faecalis OG1RF and from two epa mutants constructed previously, TX5179 and TX5180, and western blots with patient sera showed that an immuno-reactive polysaccharide present in wild type OG1RF was not produced by either of the two epa mutants. The epa mutants were more sensitive to ethanol stress, neutrophil killing and neutrophil phagocytosis than the wild type OG1RF. ^ Expression of virulence factors is commonly regulated by two component systems. A BLAST search was performed to identify potential two component systems in the E. faecalis V583 genome database using PhoP/PhoS as query sequences, and 11 gene pairs were identified, seven of which were disrupted in E. faecalis OGIRF. ^ Finally, an in vitro translocation model was established for enterococci. E. faecalis strain OG1RF and E. faecium strain DO were shown to be able to translocate across a T84 monolayer, while E. coli strain DH5α and E. faecalis strain E1 could not. ^ In conclusion, several E. faecium antigens expressed in infection (whose antibodies present in sera from patients with E. faecium endocarditis) were identified, two of which, SagA and GlyA, were characterized and suggested to be involved in cell wall metabolism. E. faecalis epa gene cluster (involving in polysaccharide biosynthesis and known to be involved in virulence of E. faecalis in mice) was shown to be involved in hindering neutrophil killing. Several two-component systems were identified in E. faecalis and two of which, EtaRS and EtbRS, were involved in E. faecalis virulence in a mouse peritonitis model.^

Characterization of healing tissue in a tooth extraction socket in a rabbit model

The histology of healing in a tooth extraction socket has been described in many studies. The focus of research in bone biology and healing is now centered on molecular events that regulate repair of injured tissue. Rapid progress in cellular and molecular biology has resulted in identification of many signaling molecules (growth factors and cytokines) associated with formation and repair of skeletal tissues. Some of these include members of the transforming growth factor-β superfamily (including the bone morphogenetic proteins), fibroblast growth factors, platelet derived growth factors and insulin like growth factors. ^ Healing of a tooth extraction socket is a complex process involving tissue repair and regeneration. It involves chemotaxis of appropriate cells into the wound, transformation of undifferentiated mesenchymal cells to osteoprogenitor cells, proliferation and differentiation of committed bone forming cells, extracellular matrix synthesis, mineralization of osteoid, maturation and remodeling of bone. Current data suggests that these cellular events are precisely controlled and regulated by specific signaling molecules. A plethora of cytokines; have been identified and studied in the past two decades. Some of these like transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF) and fibroblast growth factors (FGFs) are well conserved proteins involved in the initial response to injury and repair in soft and hard tissue. ^ The purpose of this study was to characterize the spatial and temporal localization of TGF-βl, VEGF, PDGF-A, FGF-2 and BMP-2, and secretory IgA in a tooth extraction socket model, and evaluate correlation of spatial and temporal changes of these growth factors to histological events. The results of this study showed positive correlation of histological events to spatial and temporal localization of TGF-β1, BMP-2, FGF-2, PDGF-A, and VEGF in a rabbit tooth extraction model. ^

The identification and characterization of the Staphylococcus aureus microbial immunomodulatory molecules (MIMS) Map and Efb

Staphylococcus aureus is an opportunistic pathogen that is a major health threat in the clinical and community settings. An interesting hallmark of patients infected with S. aureus is that they do not usually develop a protective immune response and are susceptible to reinfection, in part because of the ability of S. aureus to modulate host immunity. The ability to evade host immune responses is a key contributor to the infection process and is critical in S. aureus survival and pathogenesis. This study investigates the immunomodulatory effects of two secreted proteins produced by S. aureus, the MHC class II analog protein (Map) and the extracellular fibrinogen-binding protein (Efb). Map has been demonstrated to modulate host immunity by interfering with T cell function. Map has been shown to significantly reduce T cell proliferative responses and significantly reduce delayed-type hypersensitivity responses to challenge antigen. In addition, the effects of Map on the infection process were tested in a mouse model of infection. Mice infected with Map− S. aureus (Map deficient strain) presented with significantly reduced levels of arthritis, osteomyelitis and abscess formation compared to mice infected with the wild-type Map+S. aureus strain suggesting that Map−S. aureus is much less virulent than Map+S. aureus. Furthermore, Map−S. aureus-infected nude mice developed arthritis and osteomyelitis to a severity similar to Map +S. aureus-infected controls, suggesting that T cells can affect disease outcome following S. aureus infection and Map may attenuate cellular immunity against S. aureus. The extracellular fibrinogen-binding protein (Efb) was identified when cultured S. aureus supernatants were probed with the complement component C3. The binding of C3 to Efb resulted in studies investigating the effects of Efb on complement activation. We have demonstrated that Efb can inhibit both the classical and alternative complement pathways. Moreover, we have shown that Efb can inhibit complement mediated opsonophagocytosis. Further studies have characterized the Efb-C3 binding interaction and localized the C3-binding domain to the C-terminal region of Efb. In addition, we demonstrate that Efb binds specifically to a region within the C3d fragment of C3. This study demonstrates that Map and Efb can interfere with both the acquired and innate host immune pathways and that these proteins contribute to the success of S. aureus in evading host immunity and in establishing disease. ^

Identification and functional characterization of novel phosphotyrosine and phosphoserine residues in the interleukin-2 receptor complex

Interleukin-2 (IL-2) is a major T cell growth factor and plays an essential role in the development of normal immune responses. The Janus kinases (Jaks) and Signal transducers and activators of transcription (Stats) are critical for transducing signals from the IL-2 receptors (IL2Rs) to the nucleus to control cell growth and differentiation. In recent years there has been increasing evidence to indicate that the IL-2 activated Jak3/Stat5 pathway provides a new molecular target for immune suppression. Thus, understanding the regulation of this effector cascade has important therapeutic potential.^ One objective of this work was to identify and define the role and molecular mechanism of novel phosphorylation sites in Jak3. Using functional proteomics, three novel Jak3 phosphorylation sites, Y904, Y939 and S574 were identified. Phosphospecific antibodies confirmed that phosphorylation of Y904 and Y939 were mediated by IL-2 and other IL-2 family cytokines in distinct cell types. Biochemical analysis demonstrated that phosphorylation of both Y904 and Y939 positively regulated Jak3 enzymatic activity, while phosphorylation of S574 did not affect Jak3 in vitro kinase activity. However, a gain-of-function mutation of S574 in Jak3 abrogated IL-2 mediated Stat5 activation, suggesting that phosphorylation of this residue might serve a negative role to attenuate IL-2 signaling. Furthermore, mechanistic analysis suggested that phosphorylation of Y904 in Jak3 affects the KmATP of Jak3, while phosphorylation of Y939 in Jak3 was required to bind one of its substrates, Stat5.^ The second objective was to determine the role of serine/threonine phosphatases in the regulation of the IL2R complex. Activation of Jak3 and Stat5 by IL-2 is a transient event mediated by phosphorylation. Using a specific PP1/PP2A inhibitor, we observed that inhibition of PP1/PP2A negatively regulated the IL-2 activated Jak3/Stat5 signaling pathway in a human NK cell line (YT) and primary human T cells. More importantly, coimmunoprecipitation assays indicated that inhibition of PP1/PP2A blocked the formation of an active IL2R complex. Pretreatment of cells with the inhibitor also reduced the electrophoretic mobility of the IL2Rβ and IL2Rγ subunits in YT cells, suggesting that inhibition of PP1/PP2A directly or indirectly regulates undefined serine/threonine kinases which phosphorylate these proteins. Based on these observations, a model has emerged that serine/threonine phosphorylation of the IL2Rβ and IL2Rγ subunits causes a conformational change of these proteins, which disrupts IL2R dimerization and association of Jak3 and Stat5 to these receptors.^

Roadmap for implementing the Chronic Care Model for weight management: Healthcare Institution's Response to Obesity (HIRO)

Background. Excess weight and obesity are at epidemic proportions in the United States and place individuals at increased risk for a variety of chronic conditions. Rates of diabetes, high blood pressure, coronary artery disease, stroke, cancer, and arthritis are all influenced by the presence of obesity. Small reductions in excess weight can produce significant positive clinical outcomes. Healthcare organizations have a vital role to play in the identification and management of obesity. Currently, healthcare providers do not adequately diagnose and manage excess weight in patients. Lack of skill, time, and knowledge are commonly cited as reasons for non-adherence to recommended standards of care. The Chronic Care Model offers an approach to healthcare organizations for chronic disease management. The model consists of six elements that work together to empower both providers and patients to have more productive interactions: the community, the health system itself, self-management support, delivery system design, decision support, and clinical information systems. The model and its elements may offer a framework through which healthcare organizations can adapt to support, educate, and empower providers and patients in the management of excess weight and obesity. Successful management of excess weight will reduce morbidity and mortality of many chronic conditions. Purpose. The purpose of this review is to synthesize existing research on the effectiveness of the Chronic Care Model and its elements as they relate to weight management and behaviors associated with maintaining a healthy weight. Methods: A narrative review of the literature between November 1998 and November 2008 was conducted. The review focused on clinical trials, systematic reviews, and reports related to the chronic care model or its elements and weight management, physical activity, nutrition, or diabetes. Fifty-nine articles are included in the review. Results. This review highlights the use of the Chronic Care Model and its elements that can result in improved quality of care and clinical outcomes related to weight management, physical activity, nutrition, and diabetes. Conclusions. Healthcare organizations can use the Chronic Care Model framework to implement changes within their systems to successfully address overweight and obesity in their patient populations. Specific recommendations for operationalizing the Chronic Care Model elements for weight management are presented.^

DISCHARGE PLANNING: A PROCESS MODEL

As the requirements for health care hospitalization have become more demanding, so has the discharge planning process become a more important part of the health services system. A thorough understanding of hospital discharge planning can, then, contribute to our understanding of the health services system. This study involved the development of a process model of discharge planning from hospitals. Model building involved the identification of factors used by discharge planners to develop aftercare plans, and the specification of the roles of these factors in the development of the discharge plan. The factors in the model were concatenated in 16 discrete decision sequences, each of which produced an aftercare plan.^ The sample for this study comprised 407 inpatients admitted to the M. D. Anderson Hospital and Tumor Institution at Houston, Texas, who were discharged to any site within Texas during a 15 day period. Allogeneic bone marrow donors were excluded from the sample. The factors considered in the development of discharge plans were recorded by discharge planners and were used to develop the model. Data analysis consisted of sorting the discharge plans using the plan development factors until for some combination and sequence of factors all patients were discharged to a single site. The arrangement of factors that led to that aftercare plan became a decision sequence in the model.^ The model constructs the same discharge plans as those developed by hospital staff for every patient in the study. Tests of the validity of the model should be extended to other patients at the MDAH, to other cancer hospitals, and to other inpatient services. Revisions of the model based on these tests should be of value in the management of discharge planning services and in the design and development of comprehensive community health services.^

Early identification of symptomatic aortic stenosis using echocardiographic data

Background: Heart failure (CHF) is the most frequent and prognostically severe symptom of aortic stenosis (AS), and the most common indication for surgery. The mainstay of treatment for AS is aortic valve replacement (AVR), and the main indication for an AVR is development of symptomatic disease. ACC/AHA guidelines define severe AS as an aortic valve area (AVA) ≤1cm², but there is little data correlating echocardiogram AVA with the onset of symptomatic CHF. We evaluated the risk of developing CHF with progressively decreasing echocardiographic AVA. We also compared echocardiographic AVA with Jet velocity (V2) and indexed AVA (AVAI) to assess the best predictor of development of symptomatic CHF.^ Methods and Results: This retrospective cohort study evaluated 518 patients with asymptomatic moderate or severe AS from a single community based cardiology practice. A total of 925 echocardiograms were performed over an 11-year period. Each echocardiogram was correlated with concurrent clinical assessments while the investigator was blinded to the echocardiogram severity of AS. The Cox Proportional hazards model was used to analyze the relationship between AVA and the development of CHF. The median age of patients at entry was 76.1 years, with 54% males. A total of 116 patients (21.8%) developed new onset CHF during follow-up. Compared to patients with AVA >1.0cm², patients with lower AVA had an exponentially increasing risk of developing CHF for each 0.2cm² decrement in AVA, becoming statistically significant only at an AVA less than 0.8 cm². Also, compared to V2 and AVAI, AVA added more information to assessing risk for development of CHF (p=0.041). ^ Conclusion: In patients with normal or mildly impaired LVEF, the risk of CHF rises exponentially with decreasing valve area and becomes statistically significant after AVA falls below 0.8cm². AVA is a better predictor of CHF when compared to V2 or AVAI.^