Cenegenics New York

Dr. Keith Fleischman is a Senior Physician Partner at Cenegenics New York with more than 28 years of clinical experience and a lifelong dedication to health, fitness, and human performance. His work in Age Management Medicine is fueled by a deeply personal belief: the ability to sustain strength, vitality, and peak function throughout life is both achievable and transformative when approached proactively.

Dr. Fleischman earned his medical degree from the University of New England College of Osteopathic Medicine and completed his residency in Anesthesiology at St. Barnabas Medical Center in Livingston, New Jersey. During his training, he received the prestigious Robert Dripps Award for Outstanding Resident in Anesthesiology and went on to pursue advanced postgraduate training in Obstetric Anesthesia and Critical Care. He later served as Section Chief of Obstetric Anesthesia and has been recognized as a “Top Doc in New Jersey” by New Jersey Magazine based on peer nominations from nursing professionals.

Throughout his career, Dr. Fleischman has remained actively involved in medical education, teaching physicians and medical students and maintaining an academic association with Robert Wood Johnson Medical School. His clinical background in high-acuity care informs a disciplined, systems-based approach to longevity, one that emphasizes prevention, optimization, and long-term performance rather than reactive treatment.

Dr. Fleischman’s passion for Age Management Medicine is rooted in lived experience. From early exposure to yoga philosophy and martial arts—achieving black belt proficiency, to ongoing participation in yoga, martial arts, and competitive soccer as both player and coach, he embodies the principles he brings to his members. Having personally experienced the benefits of a proactive approach to aging, he is deeply committed to helping others achieve lifelong health, resilience, and peak performance.

Outside the clinic, Dr. Fleischman enjoys travel, scuba diving, skiing, and hiking. Married to a Brazilian American, he maintains a home in Brazil and is fluent in Portuguese, with conversational proficiency in Spanish. His global perspective and active lifestyle further reflect the Cenegenics mission: physician-led, precision-driven longevity care that empowers individuals to perform at their highest level, at every stage of life.

Dr. Haran Sivakumar is a triple board-certified physician whose work sits at the intersection of preventive medicine, metabolic optimization, and behavioral health, allowing him to deliver deeply personalized, whole-person longevity care. His expertise in Family Medicine, Obesity Medicine, and Addiction Medicine enables him to address both the biological and behavioral drivers of long-term health and performance.

As a board-certified Family Medicine physician and weight management specialist, Dr. Sivakumar is highly experienced in preventive care, metabolic health optimization, hormone health, and evidence-based strategies for weight management and chronic disease reversal. He integrates lifestyle medicine, targeted pharmacologic therapies, and advanced diagnostics to help members improve body composition, metabolic resilience, and overall vitality.

Dr. Sivakumar’s training in Addiction Medicine adds a critical dimension to his approach. He is skilled in multiple psychotherapeutic modalities—including Motivational Interviewing (MI), Cognitive Behavioral Therapy (CBT), Dialectical Behavioral Therapy (DBT), Motivational Enhancement Therapy (MET), and EMDR—allowing him to address mental health, habit formation, and behavior change with nuance and precision. He is also experienced in the thoughtful use of psychotropic medications when appropriate, ensuring comprehensive and individualized care.

At Cenegenics, Dr. Sivakumar applies a data-driven, integrative approach to longevity medicine, recognizing that sustainable health optimization requires alignment between physiology, mindset, and behavior. His work reflects Cenegenics’ commitment to physician-led, personalized programs that empower members to not only prevent disease, but to perform at their highest level across every stage of life.

Dr. Bertha Mayorquin is a board-certified Internal Medicine physician whose commitment to preventive care and longevity medicine is rooted in both personal experience and clinical excellence. Her passion for medicine began early, shaped by witnessing multiple family members struggle with Type 2 diabetes—a catalyst that drove her dedication to disease prevention through education, metabolic optimization, and proactive medical care.

Dr. Mayorquin earned her medical degree from the Universidad Autónoma de Guadalajara and completed both her internship and residency in Internal Medicine at Jersey City Medical Center, an affiliate of the Mount Sinai School of Medicine in New York. She is a Diplomate of the American Board of Internal Medicine and completed physician training and certification in Age Management Medicine through Cenegenics in New York.

Experienced in advanced biohacking strategies, Dr. Mayorquin integrates nutrigenomics, gut health optimization, precision weight management, and hormone balancing into her personalized care plans. She understands that genetic expression, microbiome health, metabolic efficiency, and endocrine balance are interconnected drivers of long-term vitality. By leveraging targeted nutrition, strategic supplementation, hormone optimization, and data-driven diagnostics, she helps members improve resilience, body composition, cognitive clarity, and overall performance.

In addition to her clinical work, Dr. Mayorquin serves as a faculty attending physician and finds deep fulfillment in mentoring internal medicine residents. Her role as an educator reflects her belief that advancing medicine requires both compassionate patient care and the development of future physician leaders.

Her transition into age management medicine was driven by the recognition that the most powerful approach to aging is proactive, not reactive. At Cenegenics, she focuses on preserving optimal physical and cognitive function, preventing chronic disease, correcting metabolic and hormonal imbalances, and reducing frailty through comprehensive, precision-based longevity programs.

Dr. Mayorquin’s clinical philosophy reflects the Cenegenics mission: physician-led, data-driven care designed not only to prevent disease, but to help members live stronger, healthier, and more fulfilling lives at every stage.

Dr. Joseph Bosiljevac is a physician–scientist whose career spans five decades at the intersection of advanced surgery, regenerative medicine, and longevity-focused care. Trained originally as a cardiovascular surgeon, Dr. Bosiljevac brings a rare depth of experience in both conventional Western medicine and natural, systems-based approaches to healing and optimization.

Early in his career, Dr. Bosiljevac earned a doctorate in natural medicine alongside his surgical training, allowing him to integrate evidence-based conventional care with complementary and regenerative therapies long before such approaches became mainstream. More than 16 years ago, he relocated to New York City to focus exclusively on age management medicine, where a simple clinical truth became clear: tissues, joints, and organs wear down over time, and restoring function requires more than symptom management.

This realization led Dr. Bosiljevac to develop deep expertise in regenerative medicine and stem cell–based therapies. Beginning with retired professional NFL and NBA athletes, he pioneered joint and soft tissue regenerative treatments aimed at restoring mobility, reducing pain, and extending physical performance. His work later expanded to include military special operations personnel, where he applied systemic regenerative approaches to complex conditions involving liver and lung injury, traumatic brain injury, and recovery from extreme physiological stress.

As his clinical experience grew, Dr. Bosiljevac further refined regenerative strategies for autoimmune and inflammatory conditions, always with the goal of supporting the body’s intrinsic capacity to repair, regenerate, and function optimally.

At Cenegenics, Dr. Bosiljevac applies this extensive background to longevity medicine, integrating regenerative therapies within a precision-based, physician-led framework designed to preserve performance, resilience, and quality of life. His approach reflects the Cenegenics mission: combining advanced science with individualized care to help members not only extend lifespan, but maintain strength, function, and vitality well into later decades.

Dr. Benjamin LaFerriere is a physician whose career reflects an uncommon blend of high-performance medicine, military service, and precision-driven longevity care. Trained in anesthesiology and certified in Age Management Medicine, he brings a calm, systems-based approach to optimizing health, resilience, and long-term performance.

Dr. LaFerriere earned his undergraduate degree from Willamette University before completing medical school at Oregon Health & Science University. He completed residency training in Anesthesiology at St. Barnabas Medical Center sharpening his expertise in physiology, critical decision-making, and managing complex human systems under pressure.

In parallel with his medical career, Dr. LaFerriere has served in the United States military for nearly two decades. He was a General Medical Officer in the U.S. Air Force Reserve and previously served as a Black Hawk helicopter pilot with the Oregon Army National Guard. His aviation and military experience instilled a deep respect for preparation, precision, and performance, principles that continue to guide his clinical philosophy.

Dr. LaFerriere became certified in Age Management Medicine in 2015, transitioning his focus from acute care to proactive longevity medicine. At Cenegenics, he partners with members to design personalized programs grounded in advanced diagnostics, hormone optimization, and lifestyle strategies that support sustained physical and cognitive performance over time.

His approach reflects the Cenegenics mission: physician-led, data-driven care for individuals who demand more than conventional medicine, care designed not just to extend lifespan, but to preserve strength, clarity, and capability at every stage of life.