School of Medicine
Showing 321-340 of 13,183 Results
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Zainab (Zaina) Alzawad
Clinical Assistant Professor, Emergency Medicine
BioDr. Zaina Alzawad is a clinical strategist with extensive experience advancing patient care through research, data-driven innovation, and interdisciplinary collaboration. She currently serves as a Clinical Development and Data Strategy Consultant in the Emergency Department at Stanford Health Care, where she leads and supports research and quality initiatives aimed at improving care delivery, operational efficiency, and clinical outcomes.
Dr. Alzawad’s research background is grounded in pediatric intensive care, with a growing focus on emergency care systems and innovation. She brings specialized expertise in psychometrics, quantitative and qualitative methodologies, and healthcare data analysis, supported by advanced training in measurement, statistics, and nursing science. She previously served as a Nurse Scientist at Stanford Health Care, where she led interdisciplinary studies and mentored clinical teams in research and evaluation. Driven by a passion for inquiry and impact, Dr. Alzawad actively mentors interdisciplinary teams and contributes to the design, implementation, and dissemination of studies that inform clinical practice. -
Derek F. Amanatullah, M.D., Ph.D.
Associate Professor of Orthopaedic Surgery
BioDerek F. Amanatullah, M.D., Ph.D., is an internationally recognized expert in hip and knee replacement. He helps patients with advanced arthritis and complex joint problems regain mobility and confidence. In addition to primary hip and knee replacements, he is frequently sought out for difficult revision surgeries, often fixing complications such as infection, instability, or persistent pain from prior procedures.
Dr. Amanatullah focuses on what truly lowers surgical risk: the skill, preparation, and coordination of the surgical team. He believes patients deserve care that relies on evidence and expert technique rather than placing the burden solely on weight or other patient factors. This patient-centered approach was highlighted by The New York Times.
As a researcher, he discovered an important new way certain infections can remain “hidden” in the body, shaping how surgeons diagnose and treat joint infections. His impact on the field earned him induction into The Knee Society, an honor held by fewer than 200 surgeons worldwide. Patients choose Dr. Amanatullah for his precision, innovation, and commitment to providing the safest, most effective joint care possible. -
Manuel R. Amieva
Professor of Pediatrics (Infectious Diseases) and of Microbiology and Immunology
Current Research and Scholarly InterestsMy laboratory studies how bacteria colonize our bodies for long periods of time, and how interactions between bacteria and the epithelial surfaces of the gastrointestinal tract and skin may lead to disease. Epithelial surfaces are the first barrier against infection, but they also where our bodies meet and co-evolve with the microbial world.. Several of our studies have focused on the epithelial junctions as a target for bacterial pathogens. The host epithelium uses its epithelial junctions to form a tight but dynamic barrier with an external surface that is inhospitable to microbial attachment, secretes anti-microbial compounds, and has a rapid rate of self-renewal. The balance in the microbe-epithelial relationship results in silent commensalism or symbiosis; an imbalance results in diseases ranging from acute bacterial invasive disease to chronic ulcers or carcinoma.
Our laboratory has developed novel microscopy applications such as quantitative 3D confocal microscopy, electron microscopy, time-lapse imaging, microinjection and micromanipulation to visualize the interaction of pathogens with epithelial cells in culture and in animal and human tissues. Many of out studies focus on the gastric pathogen Helicobacter pylori, but we have also expanded our investigations to include the intestinal pathogens Listeria monocytogenes and Salmonella enterica, and the skin pathogen and colonizer Staphylococcus aureus. I believe that elucidating how microbes communicate with and alter our epithelial cells at a molecular level will be important for finding novel therapeutic targets to control mucosal colonization and prevent invasive disease.
Using this perspective, we have uncovered several novel concepts of how bacteria colonize and breach our epithelial surfaces. For example, we discovered that Helicobacter pylori target the intercellular junctions, and in particular that the virulence factor CagA affects junction assembly and cell polarity. This confers H. pylori the ability to extract nutrients and grow directly on the epithelial surface. We also found that these properties of CagA have consequences for cellular transformation of the epithelium. For instance, we showed that H. pylori affect the activity and state of epithelial stem cells in the stomach by colonizing the epithelial surface deep in the gastric glands. This gland-associated population is essential for pathological inflammation and hyperplasia in animal models, and confers significant colonization advantages to the bacteria. Our Listeria research uncovered a new mechanism and site where bacteria can breach the gastrointestinal epithelial barrier to invade. We found that Listeria find their receptor for invasion at sites of epithelial senescence, where the epithelial junctions undergo dynamic turnover. To study Salmonella and H. pylori we have developed a human organoid model to study their interactions with human gut epithelium in vitro. To study Staphylococcus aureus pathogenesis, we have developed methods to visualize infection at the scale of a single bacterial microcolony using an organoid culture system of human keratinocytes and fibroblasts that grow into a 3D skin-equivalent. We recently identified several proteins at the eptithelial junctions as host factors involved in the pathogenesis of one of Staphylococcus aureus major toxins.
