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Dive into the research topics where Mehrtash Hashemzadeh is active.

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Featured researches published by Mehrtash Hashemzadeh.


The American Journal of Gastroenterology | 2007

Trends in the Utilization of Endoscopic Retrograde Cholangiopancreatography (ERCP) in the United States

M. Mazen Jamal; Eugene J. Yoon; Altaf Saadi; Theodore Y. Sy; Mehrtash Hashemzadeh

OBJECTIVES:To evaluate nationwide trends in the utilization of endoscopic retrograde cholangiopancreatography (ERCP) in relation to the advent of noninvasive methods of visualizing the biliary and pancreatic tree.METHODS:Retrospective cohort study. The Nationwide Inpatient Sample (NIS) database was used to calculate the age-adjusted rate for ERCPs performed from 1988 to 2002. The State Ambulatory Surgery Database (SASD) was used to evaluate trends in outpatient ERCPs from 1997 to 2003. Linear Poisson multivariate regression model was used to control for variations in age, gender, and ethnicity among the overall patient population.RESULTS:The NIS database contained 402,343 patients who had an ERCP performed from 1988 to 2002. The mean age for these patients was 60.21 ± 19.56 yr old. From 1988 to 1996; the age-adjusted rate for ERCPs increased by nearly threefold, from 25.66 per 100,000 in 1988 to 74.95 in 1996. The rate of 74.95 in 1996 declined to a rate of 59.70 by the year 2002. The rates of diagnostic ERCPs in men and women were 26.76 and 31.58 per 100,000 in 1988–1990, respectively. This rate then increased to 35.66 and 43.18 per 100,000 in 1994–1996, which then declined to 29.01 and 29.06 in 2000–2002. The age-adjusted rate for therapeutic ERCPs in men and women was 13.74 and 15.61 per 100,000 in 1988–1990, respectively, which continued to increase throughout the time span to 38.76 and 43.75 in 2000–2002. The SASD revealed a continual decline in outpatient ERCPs from 25.45 per 100,000 in 1997 down to 16.17 per 100,000 in the year 2003.CONCLUSION:The utilization of ERCP dramatically increased from 1988 to 1996; however, since the advent of noninvasive diagnostic techniques such as endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP), there has been a steady decline in the utilization of diagnostic ERCPs from 1996 to 2002.


Chest | 2005

The Prevalence of Pulmonary Embolism and Pulmonary Hypertension in Patients With Type II Diabetes Mellitus

Mohammad Reza Movahed; Mehrtash Hashemzadeh; M. Mazen Jamal

BACKGROUND Patients with diabetes mellitus (DM) have a hypercoagulable state that may increase their risk for thromboembolism. However, the data about this association are contradictory in the literature. The goal of this study was to evaluate the occurrence of pulmonary embolism (PE) and pulmonary hypertension (PHT) in patients with DM after adjusting for coronary artery disease (CAD), congestive heart failure (CHF), hypertension, and smoking using a large database. METHOD We used patient treatment file documents to inpatient hospital admissions containing discharge diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes) from Veterans Health Administration Hospitals. The patients were classified into two groups: a DM group with an ICD-9-CM code for DM (293,124), and a control group with an ICD-9-CM code for hypertension but no DM (552,623). The ICD-9-CM code for PE (415.19) and the ICD-9-CM code for PHT (416.0) were used to study prevalence of these diseases in DM patients vs control patients. We performed univariate and multivariate analyses adjusting for CAD, CHF, and smoking. Continuous variables were analyzed by unpaired t test. Binary variables were analyzed by chi(2) and Fisher exact tests. RESULTS PE was present in 2,011 patients with DM (0.7%) vs 2,759 patients (0.5%) in the control group. PHT was present in 3,356 patients with DM (1.1%) vs 3,357 patients (0.6%) in the control group. Using multivariate analysis, DM remained independently associated with PE (odds ratio [OR], 1.27; 95% confidence interval [CI], 1.19 to 1.35; p < 0.001) and with PHT (OR, 1.53; 95% CI, 1.45 to 1.60; p < 0.001). CONCLUSION Patients with DM have significantly higher prevalence of PE and PHT independent of CAD, hypertension, CHF, or smoking. The pathogenesis of this association is not known at this time.


American Journal of Cardiology | 2009

Trends in the age adjusted mortality from acute ST segment elevation myocardial infarction in the United States (1988-2004) based on race, gender, infarct location and comorbidities.

Mohammed Reza Movahed; Jooby John; Mehrnoosh Hashemzadeh; M. Mazen Jamal; Mehrtash Hashemzadeh

Treatment of acute ST-segment elevation myocardial infarction (STEMI) has dramatically changed over the past 2 decades. The goal of this study was to determine trends in the mortality of patients with acute STEMIs in the United States over a 16-year period (1988 to 2004) on the basis of gender, race, infarct location, and co-morbidities. The Nationwide Inpatient Sample database was used to analyze the age-adjusted mortality rates for STEMI from 1988 to 2004 for inpatients age >40. International Classification of Diseases, Ninth Revision, Clinical Modification codes consistent with acute STEMI were used. The Nationwide Inpatient Sample database contained a total of 1,316,216 patients who had diagnoses of acute STEMIs from 1988 to 2004. The mean age of these patients was 66.92 +/- 12.82 years. A total of 163,915 hospital deaths occurred during the study period. From 1988, the age-adjusted mortality rate decreased gradually for all acute STEMIs for the entire study period (in 1988, 406.86 per 100,000, 95% confidence interval 110.25 to 703.49; in 2004, 286.02 per 100,000, 95% confidence interval 45.21 to 526.84). Furthermore, unadjusted mortality decreased from 15% in 1988 to 10% in 2004 (p <0.01). This decrease was similar between the genders, among most ethnicities, and in patients with diabetes and those with congestive heart failure. However, women and African Americans had higher rates of acute STEMI-related mortality compared to men and Caucasians over the years studied. In conclusion, age-adjusted mortality from acute STEMIs has significantly decreased over the past 16 years, with persistent higher mortality rates in women and African Americans the study period.


American Journal of Medical Genetics | 2007

Novelty seeking and the dopamine D4 receptor gene (DRD4) revisited in Asians: Haplotype characterization and relevance of the 2-repeat allele†

Christopher Reist; Vural Ozdemir; Eric T. Wang; Mehrtash Hashemzadeh; Steven Mee; Robert K. Moyzis

The relationship of the dopamine D4 receptor gene (DRD4) to the behavioral trait of novelty seeking has not been uniformly consistent. A methodological shortcoming in previous studies may relate to the way different DRD4 variants were categorized. Because of evolutionary and functional (e.g., diminished potency to reduce cAMP) similarities between the 2‐ and 7‐repeat (2R, 7R) alleles of the DRD4, we suggest grouping of these two alleles together may facilitate detection of biologically meaningful and reproducible association findings with behavioral traits. We measured novelty seeking with the Tridimensional Personality Questionnaire (TPQ) in a community sample of Caucasian, Korean, and Filipino subjects (N = 171) who were subsequently characterized for the DRD4 variable number of tandem repeats (VNTR). In the Korean sample, those with a 2R and/or 7R allele scored significantly higher on novelty seeking scale (P < 0.05). By contrast, grouping the VNTR alleles by size (2, 3, 4 vs. 5, 6, 7), as has been done in similar studies of Asian subjects, was not significant. Using the extreme discordant phenotype (EDP) strategy in the pooled sample and selecting the individuals within the upper and lower decile, we observed a trend for association with higher novelty seeking in individuals who carry the 2R and/or 7R alleles (P = 0.06). We also confirmed that the 2R allele in the Korean and Filipino subjects was the result of a one‐step recombination event between the 4R and 7R alleles. This study suggests that genetic association analyses can benefit by consideration of the shared functional and evolutionary attributes of the DRD4 2R and 7R alleles.


American Journal of Cardiology | 2009

Rate of acute ST-elevation myocardial infarction in the United States from 1988 to 2004 (from the Nationwide Inpatient Sample).

Mohammad Reza Movahed; Radhakrishnan Ramaraj; Mehrnoosh Hashemzadeh; M. Mazen Jamal; Mehrtash Hashemzadeh

Advances in the management of atherosclerosis risk factors have been dramatic in the previous 10 years. The goal of this study was to evaluate any decrease in age-adjusted incidence of acute ST-elevation myocardial infarction (STEMI) in a very large database of inpatient admissions from 1988 to 2004. The Nationwide Inpatient Sample database was used to calculate the age-adjusted rate for STEMI from 1988 to 2004 retrospectively. Specific International Classification of Diseases, Ninth Revision, codes for MIs consistent with STEMI were used. Patient demographic data were also analyzed and adjusted for age. The Nationwide Inpatient Sample database contained 1,352,574 patients >40 years of age who had a diagnosis of STEMI from 1988 to 2004. Mean age for these patients was 66.06 +/- 13.69 years. Men had almost 2 times the age-adjusted STEMI rate as women (men 62.4%, women 37.6%). From 1988 the age-adjusted rate for all acute STEMIs remained steady for 8 years (108.3 per 100,000, 95% confidence interval [CI] 99.0 to 117.5, in 1988 and 102.5 per 100,000, 95% CI 94.7 to 110.4, in 1996). However, from 1996 onward, the age-adjusted incidence of STEMI steadily decreased to 1/2 the incidence of the previous 8 years (50.0 per 100.000, 95% CI 46.5 to 53.5, by 2004, p <0.01). This decrease was similar across various races and genders. In conclusion, the incidence of STEMI was stable from 1988 to 1996, with a steady linear decrease to 1/2 by 2004. The cause of the steady decrease in STEMI rate most likely reflects the advancement in management of patients with atherosclerosis.


European Journal of Gastroenterology & Hepatology | 2008

Decreasing in-hospital mortality for oesophageal variceal hemorrhage in the USA.

M. Mazen Jamal; Jason B. Samarasena; Mehrtash Hashemzadeh

Background To date, no study has analyzed nationwide trends of in-hospital mortality related to oesophageal variceal hemorrhage in the USA. The aim of this study was to analyze trends of in-hospital mortality related to oesophageal variceal bleeding over the past two decades using a large national database. In addition, our aim was to study patient demographics and to identify risk factors for in-hospital mortality based on administrative data routinely collected in this population. Methods The nationwide inpatient sample database was used from 1988 to 2004. Patients with an International Classification of Diseases, ninth revision, Clinical Modification discharge diagnosis of oesophageal variceal bleeding were included. Patient demographics, hospital, and admission characteristics were collected. t-test and Poisson regression analysis were used to evaluate trends. Logistic regression analysis was performed to determine the relationship between mortality and patient/hospital characteristics. Results From 1988 to 2004, crude in-hospital mortality decreased from 18 to 11.5%, whereas the age-adjusted in-hospital mortality rate decreased 45.4% from 1289 per 100 000 to 704 per 100 000 (P<0.01). Mortality was consistently higher for males and for African–Americans over the study period. For the 2001 dataset, multivariate logistic regression analysis showed that male sex, African–American race, age, large hospital size, urban location, teaching hospitals, and hospitals located in the northeast were independent risk factors for increased mortality. Conclusion The in-hospital mortality of patients with oesophageal variceal bleeding has decreased over the past two decades and is likely due to the advances made in the acute management of variceal bleeding as well as improved resuscitative methods. Male sex, African–American race, age, large hospital size, urban location, teaching hospitals, and hospitals located in the northeast are independent risk factors for increased in-hospital mortality.


Journal of Investigative Medicine | 2007

Cosegregation of Gastrointestinal Ulcers and Schizophrenia in a Large National Inpatient Discharge Database: Revisiting the “Brain-Gut Axis” Hypothesis in Ulcer Pathogenesis

Vural Ozdemir; M. Mazen Jamal; Klara Osapay; Martin R. Jadus; Zsuzsanna Sandor; Mehrtash Hashemzadeh; Sandor Szabo

The lifetime prevalence of duodenal ulcer in the United States is 8 to 10%, whereas another 1% of the population is affected by gastric ulcer. Both central and peripheral dopamine pathways may influence ulcer pathogenesis. Dopamine agonists prevent whereas antagonists augment stress- and chemically induced gastrointestinal ulcers in preclinical models. The dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,36-tetrahydropyridine (MPTP) depletes central dopamine and induces lesions in the substantia nigra, and, if given in high doses, MPTP induces a Parkinson disease-like syndrome and gastric ulcers. Because schizophrenia is attributed, in part, to an overactive dopaminergic system, persons with schizophrenia may display a reduced susceptibility toward gastrointestinal ulcers. A case-control study was conducted in patients represented in the 2002 National Inpatient Sample, the largest all-payer inpatient care database in the United States, consisting of 5 to 8 million inpatient hospital stays per year, which approximates a 20% sample of community hospitals. A significant association was observed between schizophrenia and diminished risk for duodenal (odds ratio [OR] 0.55; 95% confidence interval [CI] 0.45-0.67) and gastric (OR 0.54; 95% CI 0.46-0.63) (p < .01) ulcers but not for gastrojejunal ulcers (OR 0.44; 95% CI 0.16-1.20) (p = .11). Potential confounders such as age, gender, race, tobacco or alcohol dependence, and Helicobacter pylori infection were controlled in multivariate analyses. This observational study in a large sample of patients in community hospitals suggests that schizophrenia and attendant neurobiologic mechanisms (eg, variability in dopamine pathways) may act in concert to modify the composite risk for gastrointestinal ulcers. Dopamine pathways warrant further prospective research as new potential drug targets in ulcer disease.


Clinical Gastroenterology and Hepatology | 2008

Declining hospitalization rate of esophageal variceal bleeding in the United States.

M. Mazen Jamal; Jason B. Samarasena; Mehrtash Hashemzadeh; Kenneth J. Vega

BACKGROUND & AIMS In recent years, there have been many advances in the primary and secondary prophylaxis of variceal bleeding. The aim of this study was to evaluate nationwide trends in the hospitalization rate of bleeding esophageal varices in the advent of these new modalities. In addition, our aims were to study the incidence trends of nonbleeding esophageal varices over the past 2 decades while studying hospitalization rates for cirrhosis over the same study period. METHODS The Nationwide Inpatient Sample database was used for inpatient data analysis (1988-2002) and the State Ambulatory Surgery Database was used for outpatient analysis. Patients discharged with International Classification of Diseases, ninth revision, Clinical Modification discharge diagnoses related to esophageal varices were included. RESULTS The hospitalization rate of bleeding varices increased 13.7% from 10.9 per 100,000 in the 1988 to 1990 period to 12.4 per 100,000 in the 1994 to 1996 period (P < .01), and then decreased 14.5% to 10.6 per 100,000 in the 2000 to 2002 period (P < .01). In-hospital nonbleeding varices increased 55% from 6.0 to 9.3 per 100,000 from the 1988 to 1990 period to the 2000 to 2002 period (P < .01). Outpatient nonbleeding esophageal varices increased 20% from 5.5 to 6.6 per 100,000 from 1997 to 2003. CONCLUSIONS The hospitalization rate for bleeding esophageal varices has been on the decline in recent years and may be a reflection of the advances in primary and secondary prophylaxis. The incidence rate of nonbleeding esophageal varices is increasing and likely is owing to the increasing burden of portal hypertensive liver disease in the nation.


Journal of Interventional Cardiology | 2009

Nationwide trends in the utilization of multivessel percutaneous coronary intervention (MVPCI) in the United States across different gender and ethnicities

Mohammad Reza Movahed; M.H.S.A. Radhakrishnan Ramaraj M.D.; M. Mazen Jamal; Mehrtash Hashemzadeh

BACKGROUND To evaluate nationwide trends in the utilization of Multivessel Percutaneous Coronary Intervention (MVPCI) in the past compared to recent years using a large database from 1988 to 2004. METHOD The Nationwide Inpatient Sample (NIS) database was utilized to calculate the age-adjusted rate for multivessel percutaneous coronary intervention (MVPCI) from 1988 to 2004. Specific ICD-9-CM codes for MVPCI were used to compile the data. Patient demographic data were also analyzed from the database. RESULTS According to the NIS database, MVPCI was performed in 241,319 patients from 1988 to 2004. Males underwent MVPCI twice as many as compared to females (male: 67.87%, female 32.13%). The mean age for these patients was 64.89 +/- 11.84 years old. From 1988, the age-adjusted rate for MVPCI gradually increased to more than three times in 1998 [(6.62 per 100,000 (95%CI = 5.92-7.33) in 1988 to 23.92 per 100,000 (95%CI = 21.62-26.22, P < 0.01) in 1998] and accelerated to more than 6 times that of 1988 at the end of the study in 2004 (41.50 per 100,000 (95%CI = 37.84-45.16). In recent years, this trend was similar for both genders and ethnicities. CONCLUSION The utilization of MVPCI has increased six times from 1988 to 2004, with acceleration in recent years. The cause of this acceleration is most likely related to the advancement in the percutaneous coronary interventional techniques.


Journal of Clinical Gastroenterology | 2009

The clinical presentation of chronic hepatitis B virus infection in Asian Americans: a single center retrospective study.

Jonathan S. Mellen; Victor W. Xia; Mehrtash Hashemzadeh; David K. Imagawa; M. Mazen Jamal; John Hoefs; Ke-Qin Hu

Background The clinical course of chronic hepatitis B virus (HBV) infection varies with ethnicity. Little is known about the clinical presentation of chronic HBV infection in Asian Americans. Objectives To define the clinical presentation of chronic HBV infection in Asian Americans. Methods This is a retrospective study that used systematic chart review and statistical analysis to investigate 213 Asian-American patients with chronic HBV infection who presented to a university medical center. Results This cohort included 55.8% male patients, 97.9% were born outside the US, and 52.3% reported a family history of HBV infection. Of the 56 patients with liver biopsy, 34.0% had stage 3 to 4 fibrosis. In patients with available data, 21.5% were hepatitis B e antigen positive [HBeAg (+)] and 31.1% had HBV DNA levels >1×106 copies/mL. Patients with HBeAg (+) HBV infection were diagnosed at a younger age (P=0.002) and with higher alanine aminotransferase (P=0.001) and HBV DNA (P=0.001) levels. Although only 3.3% presented with obesity (ie, body mass index ≥30 kg/m2), 43.4% had evidence of hepatic steatosis. Presentation of hepatocellular carcinoma was associated with an older age at diagnosis (P<0.001), male sex (P<0.001), tobacco use (P<0.001), a greater degree of fibrosis on liver biopsy (P=0.01), and higher alanine aminotransferase, aspartate aminotransferase (P<0.001), and α fetoprotein (P<0.001) levels. Conclusions Chronic HBV infection in foreign-born Asian Americans was characterized by a low rate of HBeAg (+) and male predominance as well as high rates of family history of HBV infection, hepatic fibrosis, and hepatic steatosis.

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M. Mazen Jamal

University of California

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Kenneth J. Vega

University of Oklahoma Health Sciences Center

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Ali Khoynezhad

Cedars-Sinai Medical Center

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Eugene J. Yoon

University of California

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