Current Fellows

Chief Gastroenterology Fellow
Nelson Valentin, MD

Year III
MS:  University of Puerto Rico School of Medicine
R:  Mt. Sinai Beth Israel

Fun Facts

Nelson Valentin, MD

Hometown:  Mayaguez, Puerto Rico

Undergraduate College:  University of Puerto Rico-Mayaguez Campus (2011)

Career Interests:  Gastrointestinal Motility Disorders and Functional GI

Lives In:  Squirrel Hill

Life Outside of Medicine:  I enjoy reading, playing sports, and spending time with my dog Ollie

Favorite things to do in Pittsburgh:  Going to Frick Park, hiking, golfing, and trying new restaurants

Favorite things about the UPMC GI Fellowship:  UPMC offers world class, nationally ranked care in an environment that provides the support and resources for you to succeed as an academic gastroenterologist. There is a well rounded exposure to a diverse set of pathologies and there is plenty of collaboration across departments to facilitate learning while providing high quality care. I enjoy the comradery among the fellows and the approachability of the faculty. There are always exciting, cutting edge medical advancements occurring at UPMC and you get to play in integral part of it. It is an excellent place to train.

Advanced Endoscopy Fellow
Jacob Lipkin, MD

MS:  Penn State University
R:  UPMC

Fun Facts

Jake Lipkin, MD

Hometown:  Doylestown, PA

Undergraduate College:  Franklin & Marshall College (2012)

Career Interests:  Advanced Endoscopy

Lives In:  Shadyside

Life Outside of Medicine:  Enjoy playing sports, going on hikes and to the park with my wife and doc, traveling (during non-COVID times)

Favorite things to do in Pittsburgh:  Going to the parks, exploring new breweries and restaurants

Favorite things about the UPMC GI Fellowship:  Comradery among fellows.

Advanced IBD Fellow
Amir-Ali Ghaffari, MD

MS:  University of Caifornia, Los Angeles
R:  UPMC

Fun Facts

Amir-Ali Ghaffari, MD

Hometown:  Tehran, Iran 

Undergrad: University of California, Irvine

Career Interests:  IBD physician researcher

Lives In:  Squirrel Hill

Life Outside of Medicine:  Photography, drawing, spending time with friends and family, traveling

Favorite things to do in Pittsburgh: Checking out different restaurants/neighborhoods, hiking, Pittsburgh symphony orchestra.

Favorite things about the UPMC GI Fellowship:  My colleagues, exposure to wide range of GI disorders, working at different hospital settings

Advanced Transplant Hepatology Fellow
Ricardo Cabello, MD

MS:  University of Pittsburgh School of Medicine
R:  Mt. Sinai Beth Israel

Fun Facts

Ricardo Cabello, MD

Hometown:  Lima, Peru

Undergraduate College:  University of Virginia (2009)

Career Interests:  Hepatology

Lives In:  Downtown Pittsburgh

Life Outside of Medicine:  Enjoy playing soccer on the weekends. I have been surfing for many years and when on vacation (and able to travel), I usually go on surf trips about twice a year.

Favorite things to do in Pittsburgh:  I like running down by the Point and eating in the Downtown and Lawrenceville restaurant scenes. Definitely enjoy going to watch the Steelers and Penguins play as well.

Favorite things about the UPMC GI Fellowship:  Very supportive environment. I have had excellent mentors in Hepatology. My cofellows are very supportive and easy to work with.

Advanced Transplant Hepatology Fellow
Nabeeha Mohy-ud-din, MD
Year I
MS: Khyber Medical University
R: Allegheny Health Network

Fun Facts

Nebeeha Mohy-Ud-Din, MD

Hometown: Peshawar, Pakistan

Undergraduate College: Khyber Medical University

Career Interests: Transplant Hepatology

Lives In: Station Square

Life Outside of Medicine: Reading. Traveling. Watching the top 10 TV shows on Netflix.

Favorite things to do in Pittsburgh: Exploring different restaurants. Hiking in the parks. Visiting museums.

Favorite things about the UPMC GI Fellowship: Exposure to high transplant volumes. Outstanding teaching. Multi-disciplinary teams and conferences.

Gastroenterology Fellows

Adeyinka Adejumo, MD

Year III
MS:  University of Ibadan College of Medicine
R:  North Shore Medical Center

Fun Facts

Adeyinka Adejumo, MD

Hometown:  Nigeria

Undergraduate College:  University of Ibadan (2009)

Career Interests:  General GI, Hepatology, Pancreas

Lives In:  Monroeville, PA

Life Outside of Medicine:  Watch European soccer leagues

Favorite things to do in Pittsburgh:  Restaurants

Favorite things about the UPMC GI Fellowship:  The atmosphere in the program is quite friendly.  All the fellows, chief fellow, faculty, and staff members are very nice and eager to help others.  By rotating through several hospitals (VA, Presby, Montefiore, Shadyside, Magee) all within a very short distance, we get exposed to a diverse population of cases.  I am so glad to be here!

Muaz Aijazi, MD
Year I
MS:  Baterjee Medical College
R:  UPMC Mercy

Fun Facts

Muaz Aijazi, MD

Hometown: Jeddah, Saudi Arabia

Career Interests: Pancreatology, Advanced Endoscopy

Lives In: Shadyside

Life Outside of Medicine: Basketball, soccer, traveling, and good food.

Favorite things to do in Pittsburgh: Eating at Salem’s. Hanging out in Schenley Park.

Favorite things about the UPMC GI Fellowship: The people! From our co-fellows to faculty, program leadership, program coordinator, and literally all members of staff, the people here are all incredible.

Stela Celaj, MD, PhD

Year II
MS:  Northwestern University The Feinberg School of Medicine
R:  McGaw Medical Center of Northwestern University

Fun Facts

Stela Celaj, MD, PhD

Undergraduate College:  Utrecht University, The Netherlands

Career Interests:  Hepatology

Lives In:  Shadyside

Life Outside of Medicine:  travel (precovid), pub trivia, volleyball, binge-watching HBO/Netflix, mochi (green tea, but I’ll be happy with other kinds too).

Favorite things to do in Pittsburgh:   coffeeshops, walking around the many different neighborhoods and the parks! (so many)

Favorite things about the UPMC GI Fellowship:  my awesome co-fellows, supportive faculty, great exposure of diverse liver and GI pathology.

Zheng (John) Che, MD
Year I
MS:  University of Toledo
R:  University of Michigan

Fun Facts

Zheng (John) Che, MD

Hometown:  Columbus, OH

Undergrad: Ohio State University

Career Interests:  Hepatology and General Gastroenterology

Lives In:  Shadyside

Life Outside of Medicine:  Golf, watching Ohio State football, being a foodie

Favorite things to do in Pittsburgh:  Exploring the many breweries/restaurants and easily accessible parks

Favorite things about the UPMC GI Fellowship:  Camaraderie and support from co-fellows. Night float system. Learning endoscopy.

Kathan Chintamaneni, MD

Year III
MS:  Medical College of Wisconsin
R:  LAC + USC Medical Center

Fun Facts

Kathan Chintamaneni, MD

Hometown:  Milwaukee, WI

Undergraduate College:  Washington University in St. Louis, MO (2012)

Career Interests:  General GI, Advanced Endoscopy

Lives In:  Point Breeze

Life Outside of Medicine:  Plant daddy, Zillow addict and obsessive Dyson user with an exercise addiction

Favorite things to do in Pittsburgh:  Exploring my new city on foot, trying out new coffee shops and breweries (not necessarily together) and finding spots with a nice view for picnics.

Favorite things about the UPMC GI Fellowship:  Supportive attendings who care about their patients, hands-on training from day 1, and having a night float system is a big perk too! Definitely a better work-life balance with built in mechanisms to reduce burnout.

Jacqueline Estevez, MD

Year III
MS:  Boston University School of Medicine
R:  Cleveland Clinic

Fun Facts

Jacqueline Estevez, MD

Hometown:  Philadelphia, PA 

Career Interests:  Hepatology 

Lives In:  Downtown Pittsburgh 

Life Outside of Medicine:  Hiking, traveling, exploring the city (restaurants, bars, art) 

Favorite things to do in Pittsburgh:  Exploring various parks 

Favorite things about the UPMC GI Fellowship:  Friendly approachable colleagues, subspecialty consult services, night float system

Sagar Joshi, MD
Year I
MS:  University of Texas, Medical Branch
R:  University of Michigan

Fun Facts

Sagar Joshi, MD

Hometown:  Houston, TX

Undergrad: University of Texas at Austin

Career Interests:  General Gastroenterology and Esophagology

Lives In:  Shadyside

Life Outside of Medicine:  Mixology. Coffee enthusiast. Board and video games.

Favorite things to do in Pittsburgh:  Exploring all of the restaurants within walking and driving distance.

Favorite things about the UPMC GI Fellowship:  I did both EGDs and colonoscopies during my first week of fellowship. The attendings are great and are always willing to give scoping, life, and career advice. Also, my co-fellows are the best!

Michal Kloska, MD, PhD

Year II
MS:  Poznan University of Medical Sciences, Faculty of Medicine I, Poland
R:  Lehigh Valley Health Network

Fun Facts

Michal Kloska, MD, PhD

Hometown:  Miedzyrzecz, Poland

Undergrad: Poznan University of Medical Sciences

Career Interests:  General GI, Advanced Endoscopy

Lives In:  Gibsonia

Life Outside of Medicine:  I enjoy cooking new cuisines, reading about ancient history, and spending time with my wife

Favorite things to do in Pittsburgh:  Spending time with family in the Burgh and still exploring this awesome city.

Favorite things about the UPMC GI Fellowship:  Diverse patient population and the amazing co-fellows and faculty

Fei-Pi (Phobe) Lin, MD
Year I
MS:  Virginia Commonwealth University School of Medicine
R:  University of Pittsburgh Medical Center

Fun Facts

Fei-Pi (Phoebe) Lin, MD

Hometown:  Richmond, VA

Undergrad: College of William and Mary

Career Interests:  Hepatology and General Gastroenterology

Lives In:  Bloomfield

Life Outside of Medicine:  Hiking. Paddleboarding. Propagating/taking care of my indoor plants.

Favorite things to do in Pittsburgh:  Going to the Penguins games, Pirates games, etc. Trying different local restaurants in the surrounding neighborhoods. Running in Frick Park.

Favorite things about the UPMC GI Fellowship:  Great sense of camaraderie among the fellows, supportive faculty/staff, learning to scope early on.

Gabriel Marrero-Rivera, MD

Year I
MS:  University of Puerto Rico, Medical Science Campus
R:  University of Illinois at Chicago

Fun Facts

Gabriel Marrero-Rivera, MD

Hometown:  San Juan, Puerto Rico

Undergrad: University of Puerto Rico, Rio Piedras Campus

Career Interests:  General Gastroenterology

Lives In:  South Side / Station Square

Life Outside of Medicine:  Playing guitar and piano. Cooking. Salsa dancing. Tennis. Avid Cubs fan!

Favorite things to do in Pittsburgh:  Getting to know the city and exploring new trails, restaurants, and breweries.

Favorite things about the UPMC GI Fellowship:  Supportive faculty. Night float system. Vast exposure to complex GI/hepatology cases in an academic environment. Amazing co-fellows.

Zain Moosvi, MD

Year II
MS:  University of Maryland School of Medicine
R:  University of California – Irvine

Fun Facts

Zain Moosvi, MD

Hometown:  Frederick, MD

Undergrad: University of Maryland

Career Interests:  Advanced Endoscopy

Lives In:  Shadyside

Life Outside of Medicine:  Playing sports, working out, hanging out with friends

Favorite things to do in Pittsburgh:  Exploring the city and checking out the many parks

Favorite things about the UPMC GI Fellowship:  The fellows are all awesome and the attendings are very supportive and excellent instructors. The program is very strong clinically and procedurally heavy with ample exposure to all fields within GI.

Alan Noll, MD

 Year II
MS:  Tulane University School of Medicine
R:  Emory University

Fun Facts

Alan Noll, MD

Hometown:  Cleveland, OH

Undergrad: Baldwin Wallace University

Career Interests:  Transplant Hepatology, Bioethics, Implementation Science

Lives In:  Oakland neighborhood

Life Outside of Medicine:  Cooking (eating), golf, podcasts and kayaking

Favorite things to do in Pittsburgh:  Biking through Schenley Park, dining at Pusadee’s Garden and kayaking in North Park

Favorite things about the UPMC GI Fellowship:  All the supportive and welcoming co-fellows.

Joseph Sleiman, MD

Year II
MS: University of Balamand, Lebanon
R:  Cleveland Clinic Foundation

Fun Facts

Joseph Sleiman, MD

Hometown: Lebanon

Undergrad: University of Balamand

Career Interests:  IBD, immunotherapy colitis and colorectal neoplasia

Lives In:  Pittsburgh’s East End

Life Outside of Medicine:  Hiking and camping trips, Comics fan, foodie, and raising a cat

Favorite things to do in Pittsburgh:  kayaking and exploring parks

Favorite things about the UPMC GI Fellowship:  Scoping!

Yujie (Richie) Sun, MD

Year I
MS:  Zucker School of Medicine at Hofstra/Northwell
R:  UPMC

Fun Facts

Yujie (Richie) Sun, MD

Hometown:  Northfield, MN

Undergrad: Northwestern University

Career Interests:  General Gastroenterology and Advanced Endoscopy

Lives In:  Bloomfield

Life Outside of Medicine:  Fishing (both fresh and saltwater). Backyard gardening. Traveling.

Favorite things to do in Pittsburgh:  Going to Steelers games in the fall. Biking around different neighborhoods and exploring new restaurants. Walking around the numerous parks in the city.

Favorite things about the UPMC GI Fellowship:  Amazing faculty and wonderful co-fellows. Night float system. Diverse pathology.

Linda Wang, MD
Year I
MS:  University of Pittsburgh
R:  Beth Israel Deaconess Medical Center

Fun Facts

Linda Wang, MD

Hometown:  York, PA

Undergrad: University of Pennsylvania

Career Interests:  IBD and General Gastroenterology

Lives In:  Shadyside

Life Outside of Medicine:  Knitting and bouldering.

Favorite things to do in Pittsburgh:  Exploring the food scene. Walking through different neighborhoods.

Favorite things about the UPMC GI Fellowship:  Friendly people, interesting cases, and learning to scope.

Jonathan Wilen, MD
Year III
MS:  University of Pennsylvania Perelman School of Medicine
R:  Columbia University Irving Medicine Center

Fun Facts

Jonathan Wilen, MD

Hometown:  Pittsburgh, PA

Undergraduate College:  University of Michigan (2012)

Career Interests:  Advanced Endoscopy

Lives In:  Upper St. Clair (South Hills, ~25m drive)

Life Outside of Medicine:  Playing sports (ice hockey, soccer) and exploring new restaurants with my wife and friends

Favorite things to do in Pittsburgh:  Exploring different neighborhoods, going to concerts, eating diverse foods, and walking through Schenley and Mellon Parks

Favorite things about the UPMC GI Fellowship:  Broad spectrum of faculty expertise (get to round with generalists, hepatologists, IBD experts, advanced endoscopists, etc.), early scoping experience (EGD on day one!), awesome co-fellows who are both hardworking and relaxed

Contact Us

Division of Gastroenterology,
Hepatology and Nutrition

Mezzanine Level, C-Wing, PUH
200 Lothrop Street
Pittsburgh, PA 15213
412-864-7091  |  Email

UPMC Digestive Disorders Center

1-866-4GASTRO (442-7876)

Center for Liver Diseases

1-800-447-1651

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