Neonatology/Perinatology

Research Activities

Rakesh Sahni, Sudha Kashyap, Helen Towers

Despite the many exciting advances being made daily in molecular biology and molecular genetics, investigation of intact, functioning human beings still forms the foundation of clinical research. This is particularly true of developmental human biology. In some ways, studies of human infants are inordinately difficult. Each infant is biologically unique, measurements must be noninvasive and are often unsystematic, important variables are necessarily uncontrolled or unmeasurable, and studies are often performed while infants are receiving aggressive and confounding therapies. But there are advantages as well. Growing low birth weight infants are available for long periods of observation, their intake and output can be very accurately measured and controlled, physical activity is much easier to quantify, and they can be studied serially across a wide window of development, during which time body mass may double, or even triple. Our former director, Dr. Stanley James was among the first neonatologists to appreciate that a special patient care site(s), complete with pre-configured, hard-wired instrumentation would facilitate clinical research in the NICU without impeding nursing care. Over the last two decades the Human Infant Physiology Laboratory at Children's Hospital has focused on the study of low birth weight infants under actual nursing conditions. The theme that ties together all studies from this facility is the measurement of energy expenditure. Energy expenditure must be investigated from both sides of the equation. Over the last few years we have studied the relationships between alterations in the amount and quality of dietary intake and the associated changes in gaseous metabolism (oxygen consumption and carbon dioxide consumption). Recently, as evidence accumulates that early dietary intake may influence cardiovascualar health in adulthood, we have expanded our focus to include studies of the effects of diet on cardiovascular and metabolic function with an eye on possible mechanisms for "metabolic programming." Another major area of interest for our group is the effect of prone vs supine positioning on the autonomic control of the heart and lungs.


Molecular and Structural Biology

Thomas Diacovo

The formation of adhesive interactions between circulating blood cells and endothelium is critical not only for preventing excessive bleeding due to vascular injury, but also for directing immuno-competent cells to sites of inflammation. Our investigations center on these areas:

Inflammation: The recruitment of leukocytes into inflamed tissues is dependent upon a series of sequential adhesive events that occur between these cells and the microvasculature. Critical to this process is the activation of the PI3K signaling pathway, which was initially thought to contribute solely to the directed migration of leukocytes into areas of inflammation. We have made the novel observation that PI3Ks are also expressed in endothelium and are essential for the ability of this cell type to form adhesive interactions with circulating white blood cells. Using various molecular, biochemical, and biophysical approaches, we are determining how PI3Ks regulate this process and whether pharmacological inhibition of this signaling pathway may affect inflammatory conditions in humans associated with various disease states such as atherosclerosis. Work is currently focused on the role of PI3Kdelta and PI3Kgamma in supporting neutrophil, monocyte, and T cell function as well as trafficking into tissues by using animals deficient in these signaling pathways as well as specific inhibitors. A state-of-the-art confocal imaging system is employed to study the in vivo behavior of circulating white blood cells as they travel through the microcirculation of living animals.

Hemostasis and thrombosis: One focus of the Diacovo laboratory is to elucidate mechanisms that promote platelet interactions with von Willebrand factor (VWF), a plasma protein serves as biological glue, thus permitting platelets to seal off areas vascular damage. Although this interaction is beneficial in the setting of acute vascular injury (prevents blood loss), it can have deleterious effects when it occurs in diseased blood vessels due to atherosclerosis. In the latter case, this results in the inappropriate formation of blood clots in arteries that can reduce blood flow to vital organs such as the heart and brain, causing a heart attack or stroke, respectively. Using various molecular, biochemical, structural, and biophysical approaches, the Diacovo laboratory has begun to uncover how naturally occurring genetic mutations in VWF cause bleeding in humans. Knowledge gained from these studies has enabled his lab to generate genetically altered mice bearing such mutations that simulate the bleeding phenotype in the human disease state. Moreover, this approach has lead to the development of a mouse model that permits the in vivo study of human platelet behavior at sites of vascular injury that will ultimately expedite preclinical screening of antithrombotic therapies that target human platelets.

Study of the development of fetal baboon brain using magnetic resonance imaging at 3 Tesla. Liu F, Garland M, Duan Y, Stark RI, Xu D, Dong Z, Bansal R, Peterson BS, Kangarlu A. Neuroimage. 2008 Mar 1;40(1):148-59.

Molecular cloning of the baboon UDP-glucuronosyltransferase 1A gene family: evolution of the primate UGT1 locus and relevance for models of human drug metabolism. Pharmacogenet Genomics. 2007 Jan;17(1):11-24.

Fetal morphine metabolism and clearance are constant during late gestation. Drug Metab Dispos. 2006 Apr;34(4):636-46.

Local coherence oscillations in the EEG during development in the fetal baboon. Clin Neurophysiol. 2005 Sep;116(9):2121-8.


Divisional Core-Lab of Developmental Biology

Vadim Ten, Veniamin Ratner

The main focus is research on role of mitochondrial dysfunction in pathogenesis of cellular injury in neonatal diseases: asphyxia, BPD, NEC. Specifically, we study changes in mitochondrial production of ATP and formation of reactive oxygen species, membrane potential, Ca++ upload capacity in response to the modeling of the disease of our interest. The goal is to identify a molecular target for attenuation of mitochondrial dysfunction and to offer clinically relevant strategy to protect cells from injurious factors (ischemia, oxidative stress, inflammation).


Prognosis, Risk Perception, Informed Consent and Decision Making in Neonatal Care

K. Orfali

In neonatal care many crucially important decisions involve assessing long term consequences in terms of impairments and disabilities, and reliable medical and statistical evidence on the probabilities of the various outcomes often fail to be available. In such a context, the prerequisite of informed consent for parents, a crucial aspect of medical ethics and bedside care, may become elusive because of the potentially subjective nature of the neonatologists prognosis. Dr Orfali's interdisciplinary and international research focuses on risk perception and assessment, exploring how neonatologists elaborate a prognosis and make decisions in critical uncertain cases, when statistical evidence does not exist and probabilistic assessments cannot even be derived from a consensual professional opinion. Among the outcomes of the study, she hopes to develop a practical tool for physician to assess their optimism and pessimism index compared to peers. Other topics of interest are related to ethical dilemmas, parental choices and life and death decision-making as well as shifting paradigms in neonatal care in a cross-cultural perspective.

David Bateman

Dr. Bateman has participated in several observational epidemiological studies related to infants born at Harlem Hospital. These include descriptions of the effect of intrauterine cocaine exposure on the growth and neurological status of newborns,the neurodevelopment of children exposed to cocaine in utero,the risk factors associated with maternal HIV infection and congenital syphilis, and the outcome of unattended out of hospital births. Related studies include cost estimates of intrauterine cocaine exposure and congenital syphilis.

Decision Making in the Care of Extremely Premature Infants

J.M. Lorenz

There are many complex issues involved in balancing maternal and neonatal risks and benefits of intrapartum and neonatal care of the extremely premature fetus or newborn. These include maternal morbidity attendant to interventions to prolong pregnancy in the face of premature labor or complications of pregnancy, long-term survival and morbidity of the infant, suffering of the infant and family, parental values and autonomy, and consumption of limited communal resources. Informed decisions about whether to administer intensive care to extremely premature infants require the best data that is feasibly available, as well as presentation of this information to the parents in a way that is most comprehendable. Because communal resources are invariably expended in the care of these infants and because infants are valued in and of themselves, physicians also need more explicit direction from the larger community about the range of options that may be reasonably offered to parents regarding the care of their extremely premature infant. Dr. Lorenz' research focuses on these related issues: first, defining long-term outcomes of the extremely premature infant and exploring the effect of difference in the application of intensive care on these outcomes; second, investigating the effect on parental decisions of varying methods of presenting relevant information to parents; and, thirdly, developing a systematic approach to applying cost-effectiveness data and balancing competing moral values in policy formulation.


Developmental Electrophysiology

Buddy Stark, Philip Grieve, Joseph Isler

The laboratory staff studies the development of infant brain function using high spatial density EEG recordings from human infants. Data is obtained from both spontaneous studies of resting EEG and stimulus-driven event-related potentials (ERPs). Data is collected at the bedside in the NICU and Well Baby Nurseries in collaboration with Dr. Rakesh Sahni and Dr. Kimon Violaris of Pediatrics/Neonatology and from outpatients seen at the Vanderbilt Clinic in collaboration with Dr. William Fifer from the Department of Psychiatry. Our work is focused on the differences in the development of brain function between extremely premature and term infants and their relationship to perinatal risks for poor neurodevelopmental outcome. To that end we are studying normative perinatal development of higher-level cognitive functions. Sensory processing, perceptual integration, control of behavior, and conscious awareness are all subserved by synchronization and nonlinear coupling of electric field potential oscillations within and between cortical regions. Our lab is developing data analysis and modeling techniques aimed at understanding how these neural mechanisms can be studied in EEG and ERP recordings.

Selected papers
Reduced functional connectivity in visual evoked potentials in children with autism spectrum disorder. Isler JR, Martien KM, Grieve PG, Stark RI, Herbert MR. Clin Neurophysiol. 2010 Dec;121(12):2035-43..

EEG functional connectivity in term age extremely low birth weight infants. Grieve PG, Isler JR, Izraelit A, Peterson BS, Fifer WP, Myers MM, Stark RI. Clin Neurophysiol. 2008 Dec;119(12):2712-20.

Electrocortical functional connectivity in infancy: response to body tilt. Grieve PG, Stark RI, Isler JR, Housman SL, Fifer WP, Myers MM. Pediatr Neurol. 2007 Aug;37(2):91-8.

Frequency domain analyses of neonatal flash VEP. Isler JR, Grose-Fifer J, Fifer WP, Housman S, Stark RI, Grieve PG. Pediatr Res. 2007 Nov;62(5):581-5.

Topographic localization of electrocortical activation in newborn and two- to four-month-old infants in response to head-up tilting. Grieve PG, Myers MM, Stark RI, Housman S, Fifer WP. Acta Paediatr. 2005 Dec;94(12):1756-63.

Spatial correlation of the infant and adult electroencephalogram. Grieve PG, Emerson RG, Fifer WP, Isler JR, Stark RI. Clin Neurophysiol. 2003 Sep;114(9):1594-608.


Neuroimaging of neonates; biological treatments of arrhythmias

Tove Rosen

My research consists of both basic and clinical research. I work in collaboration with Drs. Michael Rosen and Peter Danilo of the Department of Pharmacology on a dog model using a gene therapy approach in the prevention and treatment of cardiac arrhythmias. The arrhythmias of interest are ventricular tachycardia and atrial flutter and fibrillation - the latter group also including those patients who, post-Mustard or Fontan procedures, develop reentrant atrial tachycardias. The reason for a gene therapy approach is that the pharmacological, surgical and device-based approaches to these arrhythmias are inadequate for many patients and cause significant morbidity/mortality in their own right. The tools of gene therapy offer us opportunities to overexpress novel ion channel and gap junctional constructs or to deliver small interfering RNA to suppress selected targets contributing to arrhythmias. Using these approaches we can highly selectively alter the properties of pathways contributing to arrhythmias in ways that our preliminary data suggest should offer a far more beneficial approach than those available at present.

My clinical research consists of determining the effects of drugs of abuse on brain structure and metabolite concentrations as well as the behavioral correlates in infants and children who were exposed to these drugs in utero and a non-exposed control group. The drugs we are interested in are cocaine/crack, heroin/methadone, marijuana and methamphetamines. We enroll subjects during pregnancy and at delivery. Psychosocial data is collected during pregnancy as are random urine samples for toxicology. After birth each infant has a physical, neurological exam and evaluation for withdrawal symptoms. A MRI is performed within the first 2 months of life in order to obtain high resolution anatomical MRI, Diffusion Tensor Imaging and Magnetic Resonance Spectroscopy in order to measure and compare volumes of various brain regions, measure and compare metabolites and diffusion tensor maps across all groups. After discharge the infant is seen in the follow-up clinic at 4, 6, 9, 12, 18,24,30 and 36 months of life for neurological, developmental and behavioral assessments. These assessment outcomes will then be correlated to the MRI findings and psychosocial and environmental variables. Findings will also be compared to a non-exposed control group. Many of our exposed and non-exposed mothers have a history of depression. Some have been treated with antidepressants such as SSRIs or are being presently treated. As a consequence we are now enrolling pregnant women with the diagnosis of depression on/or off medications as an additional control group who will have the same evaluations as above group.

We are also starting a study to evaluate the brain structure of premature infants less than 28 weeks gestation at close to term gestation with MRI studies. There have been several reports of poor neurobehavioral outcome of these premature infants without ventricular hemorrhage or signs of PVL on head USG. There have also been reports of abnormalities on the MRI in this group of infants that has correlated with outcome.


Kidney Development

Elvira Parravicini

Dr. Parravicini has been working on kidney development. At the beginning of her career as neonatal attending at the University of Milan (Italy) she studied the natural course of mild hydronephrosis diagnosed in utero (1-2). During her neonatal fellowship at Columbia University she joined the laboratory of Dr Jonathan Barasch, MD, PhD (Department of Nephrology, Columbia University) and collaborated to the identification of leukemia inhibitory factor (LIF) as inducer of mesenchymal to epithelial conversion during kidney development (3). Her current research focuses on the study of urinary Neutrophil Gelatinase-Associated Lipocalin (UNGAL) as an early biomarker of acute renal failure in very low birth weight (VLBW) infants. This study has been developed in collaboration with Dr Jonathan Barasch, MD, PhD (Department of Nephrology), who is responsible of the basic aspect of the research.

The rationale of this research lies in the fact that most VLBW premature infants experience some degree of renal impairment, as it is associated with common conditions of prematurity, such as patency of the ductus arteriosus, sepsis, necrotizing enterocolitis, and the use of nephrotoxic drugs. Although renal impairment is a well-recognized clinical condition in VLBW infants, there is no consensus about the criteria for its diagnosis. In this category of infants glomerular filtration rate cannot be inferred from an absolute value of serum creatinine, as serum creatinine concentration at birth is a function of maternal creatinine concentration, muscle mass, glomerular filtration rate and tubular absorption. Moreover, creatinine rises slowly in renal failure and is not a sensitive marker of early renal impairment. Thus, an earlier and more easily interpreted indicator of renal impairment would be especially useful for VLBW infants. Such a marker might also be an early indicator of associated diseases.

NGAL was originally purified from activated human neutrophils, but is present in several tissues, including the kidney. NGAL induces epithelial differentiation of mesenchyme in the developing kidney and in the mature kidney is actively produced in settings of tubular injury. Urinary NGAL (UNGAL) is markedly elevated in adults and children with acute renal failure, anticipating the rise of creatinine by 24 to 48 hours. The objective of this study is two-fold. First aim is to establish normative values for UNGAL in a population of VLBW infants without risk factors for acute renal failure and laboratory evidence for renal impairment. Once a reference range is determined, the second objective is verifying whether UNGAL can be used in clinical setting to identify acute renal failure. A potential third objective is the use of UNGAL for early detection of ARF-associated diseases such as symptomatic PDA, sepsis and necrotizing enterocolitis.

Selected papers
Ureteropelvic junction obstruction in utero and ex utero. Ghidini A, Sirtori M, Vergani P, Orsenigo E, Tagliabue P, Parravicini E. Obstet Gynecol. 1990 May;75(5):805-8.

Storia naturale dell' idronefros lieve diagnosticata in utero (Natural course of mild hydronephrosis diagnosed in utero). Parravicini E, Paterlini G, Tagliabue P, Flauto U, Vergani P, Carmignani L, DellAgnola CA, Rocco F. Acta Uro Ital. 1993;2:145-146.

Mesenchymal to epithelial conversion in rat metanephros is induced by LIF. Barasch J, Yang J, Ware CB, Taga T, Yoshida K, Erdjument-Bromage H, Tempst P, Parravicini E, Malach S, Aranoff T, Oliver JA. Cell. 1999 Nov 12;99(4):377-86.