J. C. Goodman

Extracellular lactate and glucose alterations in the brain after head injury measured by microdialysis.

OBJECTIVE To study cerebral glucose and lactate metabolism in head-injured patients using microdialysis. DESIGN Prospective, nonrandomized, clinical study. SETTING Neurosurgical intensive care unit in a university-affiliated county hospital. PATIENTS One hundred twenty-six head-injured patients. INTERVENTIONS Cerebral cortical neurochemical monitoring using microdialysis coupled with systemic hemodynamic and oxygenation monitoring, measurement of cerebral perfusion pressure and intracranial pressure, and measurement of global cerebral oxygenation using jugular venous oxygen saturation in all 126 patients. In selected cases, cerebral blood flow was also measured using cortical thermodilution probes in 33 patients, and regional cerebral oxygenation was measured using PO2 probes in 65 patients. MEASUREMENTS AND MAIN RESULTS Elevated extracellular lactate, reduced glucose, and an elevated lactate/glucose ratio were observed with cerebral hypoxia and ischemia. Elevated lactate and an increased lactate/glucose ratio strongly correlated with death. Other more subtle alterations of lactate and glucose were seen early after injury that may reflect compensatory alterations in cerebral metabolism. CONCLUSIONS Clinical neurochemical monitoring of glucose and lactate levels in the extracellular space of the cerebral cortex is technically feasible and provides insight into the bioenergetic status of the brain. Increased lactate and decreased glucose, indicating accelerated glycolysis, commonly occurred with cerebral ischemia or hypoxia, and increased anaerobic glycolysis in this setting is associated with a poor outcome.

The Identification and Characterization of Breast Cancer CTCs Competent for Brain Metastasis

EpCAM− CTCs isolated from breast cancer patients express markers needed to promote brain metastasis. Cancer Cells in Blood, Directed to the Brain Circulating tumor cells (CTCs) have been touted as exciting sources of diagnostic information, where the number of CTCs may correlate with disease progression or treatment success. However, little is known about the biology of these cells and why they are in the bloodstream, mostly because technology has prevented their long-term culture and analysis outside the body. Now, Zhang et al. have figured out how to isolate CTCs from breast cancer patients and study their metastatic potential. Starting with cancer-associated circulating cells isolated from eight patients, the authors ultimately selected a population of CTCs from three patients that was EGFR+/HPSE+/ALDH1+/CD45−/EpCAM−. These CTCs were then grown as cell lines in culture, which allowed the authors to study their cancerous behavior in more detail. Zhang et al. hypothesized that a specific protein signature was present in these cells, essentially “telling” these cells to metastasize to the brain. After identifying the “brain metastasis selected markers (BMSMs)” as HER2+/EGFR+/HPSE+/Notch1+, the authors injected these selected patient CTCs into mice. By 6 weeks, between 60 and 80% of the BMSM CTCs metastasized to brain compared with only 0 to 20% for the parental CTC lines. This protein signature, derived from human cells and tested in mice, could possibly govern brain metastatic breast cancer in patients. The next step will be to validate the presence of this BMSM CTC signature in a large number of breast cancer patients with brain metastases, with the goal of not only predicting disease course but also better understanding metastatic cancer. Brain metastatic breast cancer (BMBC) is uniformly fatal and increasing in frequency. Despite its devastating outcome, mechanisms causing BMBC remain largely unknown. The mechanisms that implicate circulating tumor cells (CTCs) in metastatic disease, notably in BMBC, remain elusive. We characterize CTCs isolated from peripheral blood mononuclear cells of patients with breast cancer and also develop CTC lines from three of these patients. In epithelial cell adhesion molecule (EpCAM)–negative CTCs, we identified a potential signature of brain metastasis comprising “brain metastasis selected markers (BMSMs)” HER2+/EGFR+/HPSE+/Notch1+. These CTCs, which are not captured by the CellSearch platform because of their EpCAM negativity, were analyzed for cell invasiveness and metastatic competency in vivo. CTC lines expressing the BMSM signature were highly invasive and capable of generating brain and lung metastases when xenografted in nude mice. Notably, increased brain metastatic capabilities, frequency, and quantitation were detected in EpCAM− CTCs overexpressing the BMSM signature. The presence of proteins of the BMSM CTC signature was also detected in the metastatic lesions of animals. Collectively, we provide evidence of isolation, characterization, and long-term culture of human breast cancer CTCs, leading to the description of a BMSM protein signature that is suggestive of CTC metastatic competency to the brain.

Cerebral hemodynamic effects of phenylephrine and L-arginine after cortical impact injury.

Objective: To determine the effects of a pressor agent (phenylephrine and L-arginine) on the abnormal cerebral hemodynamics and on neurologic outcome after a severe cortical impact injury in rats. Design: Prospective, randomized study. Setting: University Iaboratory. Subjects: Male Long-Evans rats, weighing 300 to 400 g, fasted overnight. Interventions : The animals were anesthetized with isoflurane, and a severe cortical impact injury (velocity, 5 m/sec; deformation, 3 mm) was produced In the right parietal cortex. Five minutes after impact injury, one of the following three treatments were infused: 1 mL saline Intravenously for 10 mlns, 300 mg/kg L-arginine In 1 mL saline intravenously for 10 mins, or 0.3 μg/ kg/min phenylephrine intravenously for 3 hrs. Mean arterial pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP), and laser Doppler flow (LDF) at the impact site and in the contralateral parietal cortex were monitored for 3 hrs after the impact injury. Histologic examination of the brain was performed at 2 wks after injury In a separate group of L-arginine- and saline-treated animals. Measurements and Main Results: The immediate response to the Impact injury was an increase in ICP, and a decrease in mean arterial pressure, CPP, and LDF. In the saline-treated animals, LDF decreased to <25% of the baseline values at the impact site and stayed at that level for the entire 3-hr monitoring period. On the contralateral side, LDF decreased Initially and recovered gradually to approximately 50% of the preimpact baseline value. Infusion of both phenylephrine and L-arginine increased LDF back to near-baseline levels. However, phenylephrine increased ICP significantly, whereas ICP with L-arginine did not change. L-arginine treatment reduced the contusion volume from a median value of 5.28 mm 3 to 0.63 mm 3 . Conclusions: Phenylephrine increased cerebral blood flow (CBF) by increasing CPP. L-arginine, however, Increased CBF without changing CPP. The improvement in CBF was accompanied by a decrease in neurologic injury. Although the pressor agents are used currently to increase CBF after traumatic brain injury, other strategies may also increase CBF without the potential adverse effects of Induced hypertension.

MicroRNA-1258 Suppresses Breast Cancer Brain Metastasis by Targeting Heparanase

Heparanase (HPSE) is a potent protumorigenic, proangiogenic, and prometastatic enzyme that is overexpressed in brain metastatic breast cancer (BMBC). However, little is known about the regulation of this potential therapeutic target in BMBC, which remains very poorly managed in the clinic. We hypothesized that HPSE gene expression might be regulated by micro RNA that might be exploited therapeutically. Using miRanda and RNAhybrid, we identified miR-1258 as a candidate micro RNA that may directly target HPSE and suppress BMBC. In support of our hypothesis, we found that miR-1258 levels inversely correlated with heparanase expression, enzymatic activity, and cancer cell metastatic propensities, being lowest in highly aggressive BMBC cell variants compared with either nontumorigenic or nonmetastatic human mammary epithelial cells. These findings were validated by analyses of miR-1258 and heparanase content in paired clinical specimens of normal mammary gland versus invasive ductal carcinoma, and primary breast cancer versus BMBC. In regulatory experiments, miR-1258 inhibited the expression and activity of heparanase in BMBC cells, whereas modulating heparanase blocked the phenotypic effects of miR-1258. In functional experiments, stable expression of miR-1258 in BMBC cells inhibited heparanase in vitro cell invasion and experimental brain metastasis. Together, our findings illustrate how micro RNA mechanisms are linked to brain metastatic breast cancer through heparanase control, and they offer a strong rationale to develop heparanase-based therapeutics for treatment of cancer patients with brain metastases, BMBC in particular.

Hyperglycemia increases brain injury caused by secondary ischemia after cortical impact injury in rats.

OBJECTIVE To examine the effects of glucose infusion on the histologic brain damage caused by controlled cortical impact injury alone and by cortical impact injury complicated by secondary ischemia. DESIGN Prospective, randomized study. SETTING University laboratory. SUBJECTS Male Long-Evans rats. INTERVENTIONS Three experimental conditions were studied: a) 2.5-mm deformation impact (velocity 4 m/sec) injury followed by 40 mins of bilateral carotid occlusion; b) sham impact injury followed by 40 mins of bilateral carotid occlusion; and c) 2.5-mm deformation impact (velocity 4 m/sec) injury followed by sham carotid occlusion. For each experimental condition, animals were randomized to receive either glucose solution or saline solution before the induced injury and the sham impact injury. Contusion volume and neuron density in the CA1 and CA3 regions of the hippocampus were measured 2 wks after the injury. MEASUREMENTS AND MAIN RESULTS Parenteral administration of 2.2 g/kg glucose solution increased the blood glucose concentration from 6.7 +/- 3.3 to 17.9 +/- 10.6 mmol/L before the impact injury, and to 12.3 +/- 5.6 mmol/L before carotid occlusion. Hyperglycemia had the greatest effect on the consequences of the impact injury complicated by secondary ischemia, increasing contusion volume from 1 to 30.6 mm3 in the animals that received saline or glucose solution, respectively (p = .005), and reducing the density of normal appearing neurons in the CA1 area of the hippocampus from 201 to 144 cells/mm2 in the animals that received saline solution and glucose solution, respectively (p = .038). The impact injury alone and bilateral carotid occlusion alone caused minimal neuronal loss in the hippocampus and minimal contusion or infarction at the impact site. Individually, these mild injuries were not adversely affected by infusion of glucose solution. CONCLUSION Hyperglycemia increases brain damage when traumatic brain injury is complicated by secondary ischemia.

METABOLIC CHANGES IN THE BRAIN DURING TRANSIENT ISCHEMIA MEASURED WITH MICRODIALYSIS

Forty-four patients with severe head injury were monitored for episodes of cerebral ischemia using jugular venous oxygen saturation (sjvO2), brain tissue pO2 (ti-pO2), and a microdialysis probe. The concentration of lactate and glucose were measured in the microdialysate. A total of 10 episodes of global ischemia were observed. The characteristic pattern of a simultaneous decrease in sjvO2 and brain ti-pO2 with an increase in the concentration of lactate occurred in all 10 patients. In addition, 3 episodes of regional ischemia were observed. Although brain ti-pO2 decreased to very low values and the concentration of lactate increased in the microdialysate, sjvO2 remained unchanged. Brain ti-pO2 adds another dimension to our cerebral monitoring by allowing the detection of regional cerebral ischemia.

Pro-inflammatory and pro-apoptotic elements of the neuroinflammatory response are activated in traumatic brain injury

BACKGROUND The inflammatory response may contribute to cerebral edema, increased intracranial pressure and cellular loss in traumatic brain injury (TBI). Cytokines are biomarkers of this inflammatory response and new methods allow simultaneous measurement of multiple cytokines. METHODS We examined the IL-1beta, IL-6, IL-8 and IL-12, TNFalpha, and IL-10 in arterial and jugular blood as well as cerebrospinal fluid in patients with severe traumatic brain injury. FINDINGS Multiple cytokines, particularly pro-inflammatory cytokines, are up-regulated following TBI. Cerebrospinal fluid and arteriovenous differences of some of the cytokines suggest production within the central nervous system. Antiinflammatory cytokines are not up-regulated. CONCLUSIONS Cytokine up-regulation may contribute to the neuroinflammatory reaction that follows traumatic brain injury and may contribute to secondary injury.

Lactic Acid and Amino Acid Fluctuations Measured Using Microdialysis Reflect Physiological Derangements in Head Injury

We examined the extracellular neurochemical milieu in 34 head injured patients using microdialysis while simultaneously monitoring intracranial pressure, cerebral perfusion pressure, and jugular venous oxygen saturation. Derangements of anaerobic metabolism reflected by increased lactate and lactate/pyruvate ratios, and release of amino acids were seen at the same time as physiological deterioration in the majority of instances. Clinical microdialysis may provide insights into the neurochemistry of head injury, and such information may lead to new methods of monitoring and treating head injured patients.

Extracellular Glutamate and Aspartate in Head Injured Patients

Eighty-six patients in coma from a severe head injury underwent monitoring of extracellular concentrations of glutamate and aspartate by a microdialysis technique during the first few days after injury. The median value for glutamate was 7.4 microM (interquartile range 3.6-18.8 microM). The median value for aspartate was 2.4 microM (interquartile range 1.1-5.0 microM). Average values for the dialysate concentrations of glutamate and aspartate, were closely related to outcome (p < .001 and p = .002, respectively). Patients who died of their head injury had significantly higher dialysate glutamate and aspartate concentrations compared to patients who recovered to a Glasgow Outcome Score of good recovery or moderate disability. Dialysate glutamate and aspartate levels were also significantly related to type of injury (p = .008 and p = .004, respectively). The highest values were found in patients with gunshot wounds, followed by patients with evacuated and unevacuated mass lesions. Patients with diffuse injuries had the lowest values of glutamate and aspartate. These results suggest that excitatory amino acids may play a role in the evolution of injury to the brain after trauma.

Substance P causes seizures in neurocysticercosis.

Neurocysticercosis (NCC), a helminth infection of the brain, is a major cause of seizures. The mediators responsible for seizures in NCC are unknown, and their management remains controversial. Substance P (SP) is a neuropeptide produced by neurons, endothelial cells and immunocytes. The current studies examined the hypothesis that SP mediates seizures in NCC. We demonstrated by immunostaining that 5 of 5 brain biopsies from NCC patients contained substance P (SP)-positive (+) cells adjacent to but not distant from degenerating worms; no SP+ cells were detected in uninfected brains. In a rodent model of NCC, seizures were induced after intrahippocampal injection of SP alone or after injection of extracts of cysticercosis granuloma obtained from infected wild type (WT), but not from infected SP precursor-deficient mice. Seizure activity correlated with SP levels within WT granuloma extracts and was prevented by intrahippocampal pre-injection of SP receptor antagonist. Furthermore, extracts of granulomas from WT mice caused seizures when injected into the hippocampus of WT mice, but not when injected into SP receptor (NK1R) deficient mice. These findings indicate that SP causes seizures in NCC, and, suggests that seizures in NCC in humans may be prevented and/or treated with SP-receptor antagonists.