Research Interests: Developmental and maturation aspects of myocardial metabolism and function of the neonatal and pathological myocardium and the role of gender and sex hormones. Also, their response to oxygen stress (hypoxia, hyperoxia). The role of contaminants in marine mammals, their health and impact on humans.
Dr. Wittnich's research programs focus on 2 areas; one is the "high risk" heart patient population, with particular emphasis on newborn children and women; the other on the role of contaminants in marine mammals and potential implications for human health.
The heart research tackles the issue of development and maturation and the role of gender in the heart's ability to tolerate stress and how this influences heart disease patterns. Her research program studies heart performance and metabolism from the whole body, molecular and genetic perspectives. One ongoing study looks at why newborn children undergoing heart surgery have a significantly higher complication and death rate compared to adult or older children. It was found that newborn hearts were more susceptible to ischemic injury and that several metabolic differences exist that could contribute to this apparent age related difference. Age related differences in sensitivity to extracellular calcium have also been identified which could exacerbate ischemic damage in newborn hearts. Ongoing research on the mechanisms for these differences explores molecular and second messengers in our hope to shed light on these issues. Low oxygen (cyanosis) is common in newborn children with heart abnormalities, yet what effect this has on their metabolic and functional profile continues to be unclear. Our research has identified a threshold level of oxygen deprivation, below which rapid metabolic stress is seen, including reductions in energy levels in the heart. These reductions are of concern since we had earlier identified that reduced ATP levels rendered a heart at significantly greater risk of earlier damage, despite the use of techniques such as hypothermia to reduce metabolic stress. It is also taught and accepted that oxygen is our friend and this, until recently, has remained unchallenged and unstudied, particularly in the newborn. Children can be exposed to PaO2's ranging from 250-500mmHg for periods of a few hours to days, especially when on extracorporeal membrane oxygenation. When carefully studied in our laboratory, it was found that high oxygen (PaO2 = 250-500mmHg) exposure resulted in immediate sustained reductions in blood pressure and metabolic alterations, which we continue to explore. "High risk" patients are not just restricted to the newborn age group. Another issue that has come to light lately is the potential role of gender in susceptibility of, and to, heart disease. The various potential influences of sex hormones on metabolism and organ function are currently under investigation. We have identified a number of metabolic seemingly gender-related differences that appear to be mediate by sex hormones. As well, gender differences in the hearts responses to increased afterload (hypertension) are being identified and the mechanisms for these differences elucidated. The information obtained in these research efforts we hope will lead to a number of changes in the management of patients, with clinical studies currently underway to explore our research findings.
The program in contaminants in marine mammals has identified longstanding heavy metal levels such as mercury in various species along Canada coastline and explores the trends over time. As well other critical ecological issues such as red tide and oil spill effects are investigated and have resulted in a number of publications; and the tracking of world-wide stranding data in a comparative fashion has elucidated new awareness of these issues.
Procedures: HPLC, mass spectrometry.
Analytical balances, benchtop centrifuge, HPLC, low and high-speed centrifuge, low and ultralow freezers, water baths.
Committee member/officer of national or international scientific organizations:
Member of United Nations Atlas of the Oceans
Member of Network of Healthcare Advisors
Member of CVMA Advisory Board, Canadian Veterinary Reserve
Observer Member of CVMA Secretariat
Deputy Chair of Clinician Working Group