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Dive into the research topics where Charles D. Howell is active.

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Featured researches published by Charles D. Howell.


Nature Genetics | 2013

A variant upstream of IFNL3 ( IL28B ) creating a new interferon gene IFNL4 is associated with impaired clearance of hepatitis C virus

Ludmila Prokunina-Olsson; Brian Muchmore; Wei Tang; Ruth M. Pfeiffer; Heiyoung Park; Harold Dickensheets; Dianna Hergott; Patricia Porter-Gill; Adam Mumy; Indu Kohaar; Sabrina Chen; Nathan Brand; McAnthony Tarway; Luyang Liu; Faruk Sheikh; Jacquie Astemborski; Herbert L. Bonkovsky; Brian R. Edlin; Charles D. Howell; Timothy R. Morgan; David L. Thomas; Barbara Rehermann; Raymond P. Donnelly; Thomas R. O'Brien

Chronic infection with hepatitis C virus (HCV) is a common cause of liver cirrhosis and cancer. We performed RNA sequencing in primary human hepatocytes activated with synthetic double-stranded RNA to mimic HCV infection. Upstream of IFNL3 (IL28B) on chromosome 19q13.13, we discovered a new transiently induced region that harbors a dinucleotide variant ss469415590 (TT or ΔG), which is in high linkage disequilibrium with rs12979860, a genetic marker strongly associated with HCV clearance. ss469415590[ΔG] is a frameshift variant that creates a novel gene, designated IFNL4, encoding the interferon-λ4 protein (IFNL4), which is moderately similar to IFNL3. Compared to rs12979860, ss469415590 is more strongly associated with HCV clearance in individuals of African ancestry, although it provides comparable information in Europeans and Asians. Transient overexpression of IFNL4 in a hepatoma cell line induced STAT1 and STAT2 phosphorylation and the expression of interferon-stimulated genes. Our findings provide new insights into the genetic regulation of HCV clearance and its clinical management.


Molecular Psychiatry | 2002

A prospective study of the incidence and open-label treatment of interferon-induced major depressive disorder in patients with hepatitis C

Peter Hauser; J. Khosla; H. Aurora; J. Laurin; M. A. Kling; J. Hill; M. Gulati; A. J. Thornton; R. L. Schultz; A. D. Valentine; Christina A. Meyers; Charles D. Howell

Interferon (IFN) therapy has been associated with the development of Major Depressive Disorder (MDD) when given to patients with hepatitis C (HCV). The incidence, time course, risk factors, and treatment of IFN-induced MDD are poorly understood. The objectives of the present study were to determine the incidence of IFN-induced MDD, as well as to determine the efficacy of open-label antidepressant treatment, in particular selective seretonin reuptake inhibitors (SSRIs) for IFN-induced MDD. Thirty-nine HCV patients on IFN therapy were monitored weekly using the Beck Depression Inventory (BDI). Those who became depressed were treated with citalopram, a SSRI antidepressant. Main outcome measures included the incidence of IFN-induced MDD, as well as response rates to antidepressants in those patients who developed IFN-induced MDD. Our results showed that 13 of 39 patients (33%) developed IFN-induced MDD. There were no differences in age, gender, past history of MDD, or substance use between those who became depressed and those who did not. However, there were significantly fewer African American patients in the depressed group. Patients who developed IFN-induced MDD were on IFN therapy for an average of 12.1 weeks prior to the development of MDD. Eleven of 13 patients (85%) were responsive to antidepressant treatment. We conclude that IFN-induced MDD is common in HCV patients. Health care providers should follow IFN-treated HCV patients for the development of MDD, particularly between the 2nd and 5th months of IFN therapy. SSRIs, in particular citalopram, are an effective treatment for IFN-induced depression in HCV patients.


Hepatology | 2004

Peginterferon alfa‐2a (40 kd) and ribavirin for black American patients with chronic HCV genotype 1

Lennox J. Jeffers; William M. Cassidy; Charles D. Howell; Sylvia Hu; K. Rajender Reddy

Black Americans (blacks) have a high prevalence of chronic hepatitis C virus (HCV) infection and respond poorly to therapy with interferon alfa‐based regimens, but they have been underrepresented in clinical trials. The aim of this study was to assess the rate of sustained virological response (SVR) to peginterferon alfa‐2a (40 kd) in combination with ribavirin in black patients chronically infected with HCV genotype 1. In a prospective, multicenter, open‐label trial, 78 black and 28 white American interferon‐naïve patients were enrolled to receive once weekly subcutaneous injections of 180 μg peginterferon alfa‐2a plus oral ribavirin (1000 mg/d for patients weighing less than 75 kg and 1200 mg/d for patients weighing 75 kg or more) for 48 weeks. Pre‐ and post‐treatment liver biopsies were evaluated for necroinflammation and fibrosis. SVR, defined as undetectable (<50 IU/mL) HCV RNA, was 26% in the black group and 39% in the white group. Although the SVR rate was lower in blacks than in whites, the SVR of 26% represents an improvement over previously reported SVR rates from smaller, retrospective studies of black patients. We also observed improvement in fibrosis in 25% of the black patients. No unexpected adverse events occurred. In conclusion, this prospective study evaluating responses of black patients with chronic hepatitis C to peginterferon alfa‐2a/ribavirin has demonstrated that treatment can be safely offered to such individuals with reasonable antiviral and histological benefit. (HEPATOLOGY 2004;39:1702–1708.)


Transplantation | 1997

Continuous intravenous infusion of epoprostenol for the treatment of portopulmonary hypertension.

Paul C. Kuo; Lynt B. Johnson; Jeffrey S. Plotkin; Charles D. Howell; Stephen T. Bartlett; Lewis J. Rubin

The association of pulmonary hypertension with portal hypertension, also called portopulmonary hypertension (PPHTN), is a known complication of chronic liver disease. Previously, the presence of PPHTN was considered to be a contraindication to orthotopic liver transplantation (OLT). Although there are selected case reports of successful OLT in the setting of PPHTN, an excessive mortality rate is associated with OLT and PPHTN. Heretofore, therapy for chronic management of PPHTN was lacking. Recently, continuous intravenous infusion of epoprostenol has been demonstrated to improve symptomatology and survival in the general population of patients with primary pulmonary hypertension. We now report the use of epoprostenol in the more specific instance of PPHTN. Over a period of 6-14 months, epoprostenol (10-28 ng/kg/min) therapy was associated with a 29-46% decrease in mean pulmonary artery pressure, a 22-71% decrease in pulmonary vascular resistance, and a 25-75% increase in cardiac output in a group of four patients. These results suggest that effective chronic therapy for PPHTN is available. In conjunction with inhaled nitric oxide as acute intraoperative therapy, epoprostenol infusion represents an additional therapeutic option for treatment of PPHTN in the liver transplant candidate.


The American Journal of Gastroenterology | 2007

Prevention and management of gastroesophageal varices and variceal hemorrhage in cirrhosis

Guadalupe Garcia-Tsao; Arun J. Sanyal; Norman D. Grace; William D. Carey; Margaret C. Shuhart; Gary L. Davis; Kiran Bambha; Andrés Cárdenas; Stanley M. Cohen; Timothy J. Davern; Steven L. Flamm; Steven Han; Charles D. Howell; David R. Nelson; K. Rajender Reddy; Bruce A. Runyon; John Wong; Colina Yim; Nizar N. Zein; John M. Inadomi; Darren S. Baroni; David Bernstein; William R. Brugge; Lin Chang; William D. Chey; John T. Cunningham; Kenneth R. DeVault; Steven A. Edmundowicz; Ronnie Fass; Kelvin Hornbuckle

Prevention and Management of Gastroesophageal Varices and Variceal Hemorrhage in Cirrhosis Guadalupe Garcia-Tsao, M.D.,1 Arun J. Sanyal, M.D.,2 Norman D. Grace, M.D., FACG,3 William D. Carey, M.D., MACG,4 the Practice Guidelines Committee of the American Association for the Study of Liver Diseases and the Practice Parameters Committee of the American College of Gastroenterology 1Section of Digestive Diseases, Yale University School of Medicine and VA-CT Healthcare System, New Haven, Connecticut; 2Division of Gastroenterology, Virginia Commonwealth University Medical Center, Richmond, Virginia; 3Division of Gastroenterology, Brigham and Women’s Hospital, Boston, Massachusetts; 4The Cleveland Clinic, Cleveland, Ohio


Journal of Virology | 2007

Changes in Gene Expression during Pegylated Interferon and Ribavirin Therapy of Chronic Hepatitis C Virus Distinguish Responders from Nonresponders to Antiviral Therapy

Milton W. Taylor; Takuma Tsukahara; Leonid Brodsky; Joel Schaley; Corneliu Sanda; Matthew J. Stephens; Jeanette N. McClintick; Howard J. Edenberg; Lang Li; John E. Tavis; Charles D. Howell; Steven H. Belle

ABSTRACT Treating chronic hepatitis C virus (HCV) infection using pegylated alpha interferon and ribavirin leads to sustained clearance of virus and clinical improvement in approximately 50% of patients. Response rates are lower among patients with genotype 1 than with genotypes 2 and 3 and among African-American (AA) patients compared to Caucasian (CA) patients. Using DNA microarrays, gene expression was assessed for a group of 33 African-American and 36 Caucasian American patients with chronic HCV genotype 1 infection during the first 28 days of treatment. Results were examined with respect to treatment responses and to race. Patients showed a response to treatment at the gene expression level in RNA isolated from peripheral blood mononuclear cells irrespective of degree of decrease in HCV RNA levels. However, gene expression responses were relatively blunted in patients with poor viral response (<1.5 log10-IU/ml decrease at 28 days) compared to those in patients with a marked (>3.5 log10-IU/ml decrease) or intermediate (1.5 to 3.5 log10-IU/ml decrease) response. The number of genes that were up- or down-regulated by pegylated interferon and ribavirin treatment was fewer in patients with a poor response than in those with an intermediate or marked viral response. However AA patients had a stronger interferon response than CA patients in general. The induced levels of known interferon-stimulated genes such as the 2′5′-oligoadenylate synthetase, MX1, IRF-7, and toll-like receptor TLR-7 genes was lower in poor-response patients than in marked- or intermediate-response patients. Thus, the relative lack of viral response to interferon therapy of hepatitis C virus infection is associated with blunted interferon cell signaling. No specific regulatory gene could be identified as responsible for this global blunting or the racial differences.


Transplantation | 1998

Successful use of chronic epoprostenol as a bridge to liver transplantation in severe portopulmonary hypertension

Jeffrey S. Plotkin; Paul C. Kuo; Lewis J. Rubin; Sean Gaine; Charles D. Howell; Jacqueline Laurin; Mary J. Njoku; James W. Lim; Lynt B. Johnson

BACKGROUND Portopulmonary hypertension, defined as mean pulmonary artery pressure >25 mmHg in the presence of a normal pulmonary capillary wedge pressure and portal hypertension, is a known complication of end-stage liver disease that has been associated with high morbidity and mortality at the time of liver transplantation. We have recently reported the successful treatment of portopulmonary hypertension with chronic intravenous epoprostenol and now report the first patient with severe portopulmonary hypertension successfully treated with epoprostenol who subsequently underwent successful liver transplantation. METHODS A patient with severe portopulmonary hypertension was treated with intravenous epoprostenol, 23 ng/kg/min, for a 4-month period, after which the portopulmonary hypertension resolved and the patient underwent successful liver transplantation. RESULTS The patient was discharged, continues to do well, and at 3 months is off epoprostenol with near normal pulmonary artery pressures. CONCLUSIONS Chronic epoprostenol, in conjunction with a multidisciplinary, well-planned perioperative evaluation and treatment plan, may be the answer to a heretofore untreatable disease.


Proceedings of the National Academy of Sciences of the United States of America | 2007

A functional SNP of interferon-γ gene is important for interferon-α-induced and spontaneous recovery from hepatitis C virus infection

Ying Huang; Huiying Yang; Brian B. Borg; Xiaowen Su; Shannon L. Rhodes; Kai Yang; Xiaomei Tong; George Tang; Charles D. Howell; Hugo R. Rosen; Chloe L. Thio; David L. Thomas; Harvey J. Alter; Ronda K. Sapp; T. Jake Liang

Cytokine polymorphisms are associated with disease outcome and interferon (IFN) treatment response in hepatitis C virus (HCV) infection. We genotyped eight SNPs spanning the entire IFN-γ gene in two cohorts and assessed the association between those polymorphisms and treatment response or spontaneous viral clearance. The first cohort was composed of 284 chronically HCV-infected patients who had received IFN-α-based therapy and the second was 251 i.v. drug users who had either spontaneously cleared HCV or become chronically infected. A SNP variant located in the proximal IFN-γ promoter region next to the binding motif of heat shock transcription factor (HSF), −764G, was significantly associated with sustained virological response [P = 0.04, odds ratio (OR) = 3.51 (confidence interval 1.0–12.5)]. The association was independently significant in multiple logistic regression (P = 0.04) along with race, viral titer, and genotype. This variant was also significantly associated with spontaneous recovery [P = 0.04, OR = 3.51 (1.0–12.5)] in the second cohort. Functional analyses show that the G allele confers a two- to three-fold higher promoter activity and stronger binding affinity to HSF1 than the C allele. Our study suggests that the IFN-γ promoter SNP −764G/C is functionally important in determining viral clearance and treatment response in HCV-infected patients and may be used as a genetic marker to predict sustained virological response in HCV-infected patients.


Hepatology | 2011

Quantitation of pretreatment serum interferon‐γ–inducible protein‐10 improves the predictive value of an IL28B gene polymorphism for hepatitis C treatment response

Jama M. Darling; Jeroen Aerssens; Gregory Fanning; John G. McHutchison; David B. Goldstein; Alexander J. Thompson; Nezam H. Afdhal; Michael L. Hudson; Charles D. Howell; Willem Talloen; Jacques Bollekens; Mieke De Wit; Annick Scholliers; Michael W. Fried

Polymorphisms of the IL28B gene are highly associated with sustained virological response (SVR) in patients with chronic hepatitis C treated with peginterferon and ribavirin. Quantitation of interferon‐γ–inducible protein‐10 (IP‐10) may also differentiate antiviral response. We evaluated IP‐10 levels in pretreatment serum from 115 nonresponders and 157 sustained responders in the Study of Viral Resistance to Antiviral Therapy of Chronic Hepatitis C cohort, including African American (AA) and Caucasian American (CA) patients. Mean IP‐10 was lower in sustained responders compared with nonresponders (437 ± 31 vs 704 ± 44 pg/mL, P < 0.001), both in AA and CA patients. The positive predictive value of low IP‐10 levels (<600 pg/mL) for SVR was 69%, whereas the negative predictive value of high IP‐10 levels (>600 pg/mL) was 67%. We assessed the combination of pretreatment IP‐10 levels with IL28B genotype as predictors of treatment response. The IL28B polymorphism rs12979860 was tested in 210 participants. The CC, CT, and TT genotypes were found in 30%, 49%, and 21% of patients, respectively, with corresponding SVR rates of 87%, 50%, and 39% (P < 0.0001). Serum IP‐10 levels within the IL28B genotype groups provided additional information regarding the likelihood of SVR (P < 0.0001). CT carriers with low IP‐10 had 64% SVR versus 24% with high IP‐10. Similarly, a higher SVR rate was identified for TT and CC carriers with low versus high IP‐10 (TT, 48% versus 20%; CC, 89% versus 79%). IL28B genotype and baseline IP‐10 levels were additive but independent when predicting SVR in both AA and CA patients. Conclusion: When IL28B genotype is combined with pretreatment serum IP‐10 measurement, the predictive value for discrimination between SVR and nonresponse is significantly improved, especially in non‐CC genotypes. This relationship warrants further investigation to elucidate the mechanisms of antiviral response and prospective validation. (Hepatology 2011;)


Hepatology | 2014

Randomized, double-blind, controlled study of glycerol phenylbutyrate in hepatic encephalopathy

Don C. Rockey; John M. Vierling; Parvez S. Mantry; Marwan Ghabril; Robert S. Brown; Olga Alexeeva; Igor A. Zupanets; Vladimir Grinevich; Andrey Baranovsky; Larysa Dudar; Galyna Fadieienko; Nataliya Kharchenko; Iryna Klaryts'ka; Vyacheslav Morozov; Priya Grewal; Timothy M. McCashland; K. Gautham Reddy; K. Rajender Reddy; Vasyl Syplyviy; Nathan M. Bass; Klara Dickinson; Catherine Norris; Dion F. Coakley; Masoud Mokhtarani; Bruce F. Scharschmidt; Aijaz Ahmed; Luis A. Balart; B. Berk; Kimberly A. Brown; A. Frolov

Glycerol phenylbutyrate (GPB) lowers ammonia by providing an alternate pathway to urea for waste nitrogen excretion in the form of phenylacetyl glutamine, which is excreted in urine. This randomized, double‐blind, placebo‐controlled phase II trial enrolled 178 patients with cirrhosis, including 59 already taking rifaximin, who had experienced two or more hepatic encephalopathy (HE) events in the previous 6 months. The primary endpoint was the proportion of patients with HE events. Other endpoints included the time to first event, total number of events, HE hospitalizations, symptomatic days, and safety. GPB, at 6 mL orally twice‐daily, significantly reduced the proportion of patients who experienced an HE event (21% versus 36%; P = 0.02), time to first event (hazard ratio [HR] = 0.56; P < 0.05), as well as total events (35 versus 57; P = 0.04), and was associated with fewer HE hospitalizations (13 versus 25; P = 0.06). Among patients not on rifaximin at enrollment, GPB reduced the proportion of patients with an HE event (10% versus 32%; P < 0.01), time to first event (HR = 0.29; P < 0.01), and total events (7 versus 31; P < 0.01). Plasma ammonia was significantly lower in patients on GPB and correlated with HE events when measured either at baseline or during the study. A similar proportion of patients in the GPB (79%) and placebo groups (76%) experienced adverse events. Conclusion: GPB reduced HE events as well as ammonia in patients with cirrhosis and HE and its safety profile was similar to placebo. The findings implicate ammonia in the pathogenesis of HE and suggest that GPB has therapeutic potential in this population. (Clinicaltrials.gov, NCT00999167). (Hepatology 2014;59:1073‐1083)

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Nezam H. Afdhal

Beth Israel Deaconess Medical Center

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K. Rajender Reddy

University of Pennsylvania

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Lynt B. Johnson

MedStar Georgetown University Hospital

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Paul C. Kuo

Loyola University Medical Center

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