William M Armstead

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Traumatic brain injury is a global health concern and is the leading cause of traumatic morbidity and mortality in children. Despite a lower overall mortality than in adult traumatic brain injury, the cost to society from the sequelae of pediatric traumatic brain injury is very high. Predictors of poor outcome after traumatic brain injury include altered(More)
The present study was designed to characterize the influence of early developmental changes on the relationship among systemic arterial pressure, cerebral hemodynamics, and cerebral oxygenation during the first 3 h following percussion brain injury. Anesthetized newborn (1-5 days old) and juvenile (3-4 weeks old) pigs equipped with a closed cranial window(More)
Previously, it had been observed that nitric oxide (NO) contributes to hypoxia-induced pial artery dilation in the newborn pig. Additionally, it was also noted that activation of ATP-sensitive K+ channels (KATP) contribute to cGMP-mediated as well as to hypoxia-induced pial dilation. Although somewhat controversial, adenosine is also thought to contribute(More)
Cerebrospinal fluid (CSF) adrenomedullin (ADM) levels are increased in female, but remain unchanged in male, piglets after fluid percussion injury (FPI) of the brain. Subthreshold vascular concentrations of ADM restore impaired hypotensive pial artery dilation after FPI more in males than females. Extracellular signal-related kinase (ERK) mitogen-activated(More)
This study was designed to compare the effect of fluid percussion brain injury (FPI) on the hypotensive cerebrovascular response in newborn and juvenile pigs as a function of time postinsult and to determine the role of endothelin-1 (ET-1) in any age-dependent differences in hypotensive cerebrovascular regulation after injury. Ten minutes of hypotension(More)
BACKGROUND AND PURPOSE Pial artery dilation in response to activators of the ATP-sensitive K(+) (K(ATP)) and calcium-sensitive K(+) (K(Ca)) channels is impaired after fluid percussion brain injury (FPI). Vasopressin, when coadministered with the K(ATP) and K(Ca) channel agonists cromakalim and NS1619 in a concentration approximating that observed in(More)
BACKGROUND AND PURPOSE Although activation of the N-methyl-D-aspartate (NMDA) receptor is thought to contribute to altered cerebrovascular regulation after traumatic brain injury, the effects of such injury on the vascular response to NMDA itself has been less well appreciated. The newly described opioid nociceptin/orphanin FQ (NOC/oFQ) elicits pial artery(More)
BACKGROUND Cardiac dysfunction after brain death has been described in a variety of brain injury paradigms but is not well understood after severe pediatric traumatic brain injury (TBI). Cardiac dysfunction may have implications for organ donation in this patient population. MATERIALS AND METHODS We conducted a retrospective cohort study of pediatric(More)
Traumatic brain injury (TBI) is a leading cause of morbidity in children and boys are disproportionately represented. Hypotension is common and worsens outcome after TBI. Previous studies show that adrenomedullin, a cerebrovasodilator, prevented sex dependent impairment of autoregulation during hypotension after piglet fluid percussion brain injury (FPI).(More)
The present study was designed to investigate the contribution of opioids and nitric oxide (NO) to hypoxia-induced pial vasodilation. Newborn pigs equipped with a closed cranial window were used to measure pial arteriolar diameter and to collect cortical periarachnoid cerebrospinal fluid (CSF) for assay of opioids and guanosine 3',5'-cyclic monophosphate(More)