In vivo testing of a non-invasive prototype device for the continuous monitoring of intracerebral hemorrhage.

BACKGROUND: Intracerebral hemorrhage (ICH) is a stroke subtype with the highest mortality rate. Hematoma expansion and re-bleeding post-ICH are common and exacerbate the initial cerebral insult. There is a need for continuous monitoring of the neurologic status of patients with an ICH injury. NEW METHOD: A prototype device for non-invasive continuous monitoring of an ICH was developed and tested in vivo using a porcine ICH model. The device consists of receiving and transmitting antennae in the 400-1000 MHz frequency range, placed directly in line with the site of the ICH. The device exploits the differences in the dielectric properties and geometry of tissue media of a healthy brain and a brain with an ICH injury. The power received by the receiving antenna is measured and the percent change in power received immediately after infusion of blood and 30 min after the infusion, allowing for the blood to clot, is calculated. RESULTS: An increase in the received power in the presence of an ICH is observed at 400 MHz, consistent with previous in vitro studies. Frequency sweep experiments show a maximum percent change in received power in the 750-1000 MHz frequency range. COMPARISON WITH EXISTING METHODS: Currently, CT, MRI and catheter angiography (CA) are the main clinical neuroimaging modalities. However, these techniques require specialized equipment and personnel, substantial time, and patient-transportation to a radiology suite to obtain results. Moreover, CA is invasive and uses intra-venous dye or vascular catheters to accomplish the imaging. CONCLUSIONS: The device has the potential to significantly improve neurologic care in the critically ill brain-injured patient.

Plasma proteins in edematous white matter after intracerebral hemorrhage confound immunoblots: an ELISA to quantify contamination.

Intracerebral hemorrhage (ICH) and traumatic brain injury can induce brain tissue edema (i.e., interstitial and/or vasogenic), containing high concentrations of plasma proteins. To understand biochemical processes in edema development following these insults, it would be useful to examine alterations in various proteins (e.g., transcription factors, signaling). However, determining altered protein responses in edematous brain tissue using standard immunoblotting techniques is problematic due to contaminating plasma proteins. To solve this problem, we developed an enzyme-linked immunosorbent assay (ELISA) method to quantify the two major plasma proteins, albumin and immunoglobulin G (IgG), that comprise about 80% of the total plasma proteins. We tested our method on edematous white matter samples from our porcine ICH model. To induce ICH, we infused autologous arterial whole blood (3 mL) into frontal hemispheric white matter of pentobarbital- anesthetized pigs ( approximately 20 kg) over 15 min. We froze brains in situ at various times up to 24 h post- ICH and sampled white matter adjacent and contralateral to hematomas. We prepared cytoplasmic extracts that we subjected to ELISA and immunoblotting analyses. Our results demonstrate that this ELISA method is accurate, reproducible, and enables the concentrations of albumin and IgG in edematous brain tissue samples to be accurately determined. By using this correction method, equal amounts of cellular protein can be loaded onto gels during immunoblotting procedures. This method is applicable to edematous tissue samples in brain injury models in which high plasma protein concentrations result from interstitial or vasogenic edema development.

Plasma infusions into porcine cerebral white matter induce early edema, oxidative stress, pro-inflammatory cytokine gene expression and DNA fragmentation: implications for white matter injury with increased blood-brain-barrier permeability.

Plasma infused into porcine cerebral white matter induces both acute interstitial and delayed vasogenic edema. Edematous white matter contains extracellular plasma proteins and rapidly induces oxidative stress as evidenced by increased protein carbonyl formation and heme oxygenase-1 induction. We tested the hypothesis that edematous white matter would also upregulate pro-inflammatory cytokine gene expression and develop DNA damage. We infused autologous plasma into the frontal hemispheric white matter of pentobarbital-anesthetized pigs. We monitored and controlled physiological variables and froze brains in situ at 1, 4 or 24 hrs. We determined edema volumes by computer-assisted morphometry. We measured white matter protein carbonyl formation by immunoblotting, cytokine gene expression by standard RT-PCR methods and DNA fragmentation by agarose gel electrophoresis. White matter edema developed acutely (1 hr) after plasma infusion and increased significantly in volume between 4 and 24 hrs. Protein carbonyl formation also occurred rapidly in edematous white matter with significant elevations (3 to 4-fold) already present at 1 hr. This increase remained through 24 hrs. Pro-inflammatory cytokine gene expression was also rapidly increased at 1 hr post-infusion. Evidence for DNA fragmentation began at 2 to 4 hrs, and a pattern indicative of both ongoing necrosis and apoptosis was robust by 24 hrs. Plasma protein accumulation in white matter induces acute edema development and a cascade of patho-chemical events including oxidative stress, pro-inflammatory cytokine gene expression and DNA damage. These results suggest that in diseases with increased blood-brain barrier (BBB) permeability or following intracerebral hemorrhage or traumatic brain injury, interstitial plasma can rapidly damage white matter.