Characterization and optimization of a ß detector for 18F radio-guided surgery.

Radio-Guided Surgery (RGS) is a nuclear medicine technique to support the surgeon during surgery towards a complete tumor resection. It is based on intraoperative detection of radiation emitted by a radio-pharmaceutical that bounds selectively to tumoral cells. In the past years, an approach that exploits ß- emitting radiotracers has been pursued to overtake some limitations of the traditional RGS based on γ emission. A particle detector dedicated to this application, demonstrating very high efficiency to ß- particles and remarkable transparency to photons, has been thus developed. As a by-product, its characteristics suggested the possibility to utilize it with ß+ emitting sources, more commonly in use in nuclear medicine. In this paper, performances of such detector on 18F liquid sources are estimated by means of Monte Carlo simulations (MC) and laboratory measurements. The experimental setup with a 18F saline solution comprised a "positron signal" spot (a 7 × 10 mm cylinder representing the tumor residual), and a surrounding "far background" volume, that represented for the detector an almost isotropic source of annihilation photons. Experimental results show good agreement with MC predictions, thus confirming the expected performances of the detector with 18F, and the validity of the developed MC simulation as a tool to predict the gamma background determined by a diffuse source of annihilation photons.

GPU-accelerated Monte Carlo simulation of electron and photon interactions for radiotherapy applications.

Objective. The Monte Carlo simulation software is a valuable tool in radiation therapy, in particular to achieve the needed accuracy in the dose evaluation for the treatment plans optimisation. The current challenge in this field is the time reduction to open the way to many clinical applications for which the computational time is an issue. In this manuscript we present an innovative GPU-accelerated Monte Carlo software for dose valuation in electron and photon based radiotherapy, developed as an update of the FRED (Fast paRticle thErapy Dose evaluator) software.Approach. The code transports particles through a 3D voxel grid, while scoring their energy deposition along their trajectory. The models of electromagnetic interactions in the energy region between 1 MeV-1 GeV available in literature have been implemented to efficiently run on GPUs, allowing to combine a fast tracking while keeping high accuracy in dose assessment. The FRED software has been bench-marked against state-of-art full MC (FLUKA, GEANT4) in the realm of two different radiotherapy applications: Intra-Operative Radio Therapy and Very High Electron Energy radiotherapy applications.Results. The single pencil beam dose-depth profiles in water as well as the dose map computed on non-homogeneous phantom agree with full-MCs at 2% level, observing a gain in processing time from 200 to 5000.Significance. Such performance allows for computing a plan with electron beams in few minutes with an accuracy of ∼%, demonstrating the FRED potential to be adopted for fast plan re-calculation in photon or electron radiotherapy applications.

Inter-fractional monitoring of [Formula: see text]C ions treatments: results from a clinical trial at the CNAO facility.

The high dose conformity and healthy tissue sparing achievable in Particle Therapy when using C ions calls for safety factors in treatment planning, to prevent the tumor under-dosage related to the possible occurrence of inter-fractional morphological changes during a treatment. This limitation could be overcome by a range monitor, still missing in clinical routine, capable of providing on-line feedback. The Dose Profiler (DP) is a detector developed within the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) collaboration for the monitoring of carbon ion treatments at the CNAO facility (Centro Nazionale di Adroterapia Oncologica) exploiting the detection of charged secondary fragments that escape from the patient. The DP capability to detect inter-fractional changes is demonstrated by comparing the obtained fragment emission maps in different fractions of the treatments enrolled in the first ever clinical trial of such a monitoring system, performed at CNAO. The case of a CNAO patient that underwent a significant morphological change is presented in detail, focusing on the implications that can be drawn for the achievable inter-fractional monitoring DP sensitivity in real clinical conditions. The results have been cross-checked against a simulation study.

Targeted deletions of complement lectin pathway genes improve outcome in traumatic brain injury, with MASP-2 playing a major role.

The lectin pathway (LP) of complement activation is believed to contribute to brain inflammation. The study aims to identify the key components of the LP contributing to TBI outcome as possible novel pharmacological targets. We compared the long-term neurological deficits and neuropathology of wild-type mice (WT) to that of mice carrying gene deletions of key LP components after experimental TBI. WT or MASP-2 (Masp2-/-), ficolin-A (Fcna-/-), CL-11 (Colec11-/-), MASP-1/3 (Masp1-/-), MBL-C (Mbl2-/-), MBL-A (Mbl1-/-) or MBL-/- (Mbl1-/-/Mbl2-/-) deficient male C57BL/6J mice were used. Mice underwent sham surgery or TBI by controlled cortical impact. The sensorimotor response was evaluated by neuroscore and beam walk tests weekly for 4 weeks. To obtain a comparative analysis of the functional outcome each transgenic line was rated according to a health score calculated on sensorimotor performance. For selected genotypes, brains were harvested 6 weeks after injury for histopathological analysis. MASP-2-/-, MBL-/- and FCN-A-/- mice had better outcome scores compared to WT. Of these, MASP-2-/- mice had the best recovery after TBI, showing reduced sensorimotor deficits (by 33% at 3 weeks and by 36% at 4 weeks). They also showed higher neuronal density in the lesioned cortex with a 31.5% increase compared to WT. Measurement of LP functional activity in plasma from MASP-2-/- mice revealed the absence of LP functional activity using a C4b deposition assay. The LP critically contributes to the post-traumatic inflammatory pathology following TBI with the highest degree of protection achieved through the absence of the LP key enzyme MASP-2, underlining a therapeutic utility of MASP-2 targeting in TBI.

Tumor-non-tumor discrimination by a ß- detector for Radio Guided Surgery on ex-vivo neuroendocrine tumors samples.

This paper provides a first insight of the potential of the ß- Radio Guided Surgery (ß--RGS) in a complex surgical environment like the abdomen, where multiple sources of background concur to the signal at the tumor site. This case is well reproduced by ex-vivo samples of 90Y-marked Gastro-Entero-Pancreatic Neuroendocrine Tumors (GEP NET) in the bowel. These specimens indeed include at least three wide independent sources of background associated to three anatomical districts (mesentery, intestine, mucose). The study is based on the analysis of 37 lesions found on 5 samples belonging to 5 different patients. We show that the use of electrons, a short range particle, instead of γ particles, allows to limit counts read on a lesion to the sum of the tumor signal plus the background generated by the sole hosting district.The background on adjacent districts in the same specimen/patient is found to differ up to a factor 4, showing how the specificity and sensitivity of the ß--RGS technique can be fully exploited only upon a correct measurement of the contributing background. This locality has been used to set a site-specific cut-off algorithm to discriminate tumor and healthy tissue with a specificity of 100% and a sensitivity, on this test data sample, close to 100%. Factors influencing the sensitivity are also discussed. One of the specimens set allowed us evaluate the volume of the lesions, thus concluding that the probe was able to detect lesions as small as 0.04 mL in that particular case.

Characterisation of a ß detector on positron emitters for medical applications.

PURPOSE: Radio Guided Surgery (RGS) is a technique that helps the surgeon to achieve an as complete as possible tumor resection, thanks to the intraoperative detection of particles emitted by a radio tracer that bounds to tumoral cells. In the last years, a novel approach to this technique has been proposed that, exploiting ß- emitting radio tracers, overtakes some limitations of established γ-RGS. In this context, a first prototype of an intraoperative ß particle detector, based on a high light yield and low density organic scintillator, has been developed and characterised on pure ß- emitters, like 90Y. The demonstrated very high efficiency to ß- particles, together with the remarkable transparency to photons, suggested the possibility to use this detector also with ß+ emitting sources, that have plenty of applications in nuclear medicine. In this paper, we present upgrades and optimisations performed to the detector to reveal such particles. METHODS: Laboratory measurement have been performed on liquid Ga68 source, and were used to validate and tune a Monte Carlo simulation. RESULTS: The upgraded detector has an ~80% efficiency to electrons above ~110keV, reaching a plateau value of ~95%. At the same time, the probe is substantially transparent to photons below ~200keV, reaching a plateau value of ~3%. CONCLUSIONS: The new prototype seems to have promising characteristics to perform RGS also with ß+ emitting isotopes.

Secondary radiation measurements for particle therapy applications: Charged secondaries produced by 16O ion beams in a PMMA target at large angles.

Particle therapy is a therapy technique that exploits protons or light ions to irradiate tumor targets with high accuracy. Protons and 12C ions are already used for irradiation in clinical routine, while new ions like 4He and 16O are currently being considered. Despite the indisputable physical and biological advantages of such ion beams, the planning of charged particle therapy treatments is challenged by range uncertainties, i.e. the uncertainty on the position of the maximal dose release (Bragg Peak - BP), during the treatment. To ensure correct 'in-treatment' dose deposition, range monitoring techniques, currently missing in light ion treatment techniques, are eagerly needed. The results presented in this manuscript indicate that charged secondary particles, mainly protons, produced by an 16O beam during target irradiation can be considered as candidates for 16O beam range monitoring. Hereafter, we report on the first yield measurements of protons, deuterons and tritons produced in the interaction of an 16O beam impinging on a PMMA target, as a function of detected energy and particle production position. Charged particles were detected at 90° and 60° with respect to incoming beam direction, and homogeneous and heterogeneous PMMA targets were used to probe the sensitivity of the technique to target inhomogeneities. The reported secondary particle yields provide essential information needed to assess the accuracy and resolution achievable in clinical conditions by range monitoring techniques based on secondary charged radiation.

Review and performance of the Dose Profiler, a particle therapy treatments online monitor.

Particle therapy (PT) can exploit heavy ions (such as He, C or O) to enhance the treatment efficacy, profiting from the increased Relative Biological Effectiveness and Oxygen Enhancement Ratio of these projectiles with respect to proton beams. To maximise the gain in tumor control probability a precise online monitoring of the dose release is needed, avoiding unnecessary large safety margins surroundings the tumor volume accounting for possible patient mispositioning or morphological changes with respect to the initial CT scan. The Dose Profiler (DP) detector, presented in this manuscript, is a scintillating fibres tracker of charged secondary particles (mainly protons) that will be operating during the treatment, allowing for an online range monitoring. Such monitoring technique is particularly promising in the context of heavy ions PT, in which the precision achievable by other techniques based on secondary photons detection is limited by the environmental background during the beam delivery. Developed and built at the SBAI department of "La Sapienza", within the INSIDE collaboration and as part of a Centro Fermi flagship project, the DP is a tracker detector specifically designed and planned for clinical applications inside a PT treatment room. The DP operation in clinical like conditions has been tested with the proton and carbon ions beams of Trento proton-therapy center and of the CNAO facility. In this contribution the detector performances are presented, in the context of the carbon ions monitoring clinical trial that is about to start at the CNAO centre.

Early ficolin-1 is a sensitive prognostic marker for functional outcome in ischemic stroke.

BACKGROUND: Several lines of evidence support the involvement of the lectin pathway of complement (LP) in the pathogenesis of acute ischemic stroke. The aim of this multicenter observational study was to assess the prognostic value of different circulating LP initiators in acute stroke. METHODS: Plasma levels of the LP initiators ficolin-1, -2, and -3 and mannose-binding lectin (MBL) were measured in 80 stroke patients at 6 h only and in 85 patients at 48 h and later. Sixty-one age- and sex-matched healthy individuals served as controls. Stroke severity was measured on admission using the National Institutes of Health Stroke Scale (NIHSS). The outcome was measured at 90 days by the modified Rankin Scale (mRS). RESULTS: Ficolin-1 was decreased in patients compared with controls measured at 6 h (median 0.13 vs 0.33 µg/ml, respectively, p < 0.0001). At 48 h, ficolin-1 was significantly higher (0.45 µg/ml, p < 0.0001) compared to the 6 h samples and to controls. Likewise, ficolin-2 was decreased at 6 h (2.70 vs 4.40 µg/ml, p < 0.0001) but not at 48 h. Ficolin-3 was decreased both at 6 and 48 h (17.3 and 18.23 vs 21.5 µg/ml, p < 0.001 and <0.05, respectively). For MBL no difference was detected between patients and controls or within patients at the different time points. In multivariate analysis, early ficolin-1 was independently associated with unfavorable mRS outcome (adjusted odds ratio (OR): 2.21, confidence interval (CI) 95 % 1.11-4.39, p = 0.023). Early ficolin-1 improved the discriminating ability of an outcome model including NIHSS and age (area under the curve (AUC) 0.95, CI 95 % 0.90-0.99, p = 0.0001). CONCLUSIONS: The ficolins are consumed within 6 h after stroke implicating activation of the LP. Early ficolin-1 is selectively related to 3-month unfavorable outcome.

Heart-fatty acid-binding and tau proteins relate to brain injury severity and long-term outcome in subarachnoid haemorrhage patients.

BACKGROUND: Vasospasm and other secondary neurological insults may follow subarachnoid haemorrhage (SAH). Biomarkers have the potential to stratify patient risk and perhaps serve as an early warning sign of delayed ischaemic injury. METHODS: Serial cerebrospinal fluid (CSF) samples were collected from 38 consecutive patients with aneurysmal SAH admitted to the neurosurgical intensive care unit. We measured heart-fatty acid-binding protein (H-FABP) and tau protein (τ) levels in the CSF to evaluate their association with brain damage, and their potential as predictors of the long-term outcome. H-FABP and τ were analysed in relation to acute clinical status, assessed by the World Federation of Neurological Surgeons (WFNS) scale, radiological findings, clinical vasospasm, and 6-month outcome. RESULTS: H-FABP and τ increased after SAH. H-FABP and τ were higher in patients in poor clinical status on admission (WFNS 4-5) compared with milder patients (WFNS 1-3). Elevated H-FABP and τ levels were also observed in patients with early cerebral ischaemia, defined as a CT scan hypodense lesion visible within the first 3 days after SAH. After the acute phase, H-FABP, and τ showed a delayed increase with the occurrence of clinical vasospasm. Finally, patients with the unfavourable outcome (death, vegetative state, or severe disability) had higher peak levels of both proteins compared with patients with good recovery or moderate disability. CONCLUSIONS: H-FABP and τ show promise as biomarkers of brain injury after SAH. They may help to identify the occurrence of vasospasm and predict the long-term outcome.

The genetics of small-vessel disease.

Cerebral small-vessel disease (SVD) is a well-known cause of stroke, dementia and death, but its pathogenesis is not yet completely understood. The spectrum of neuroradiological manifestations associated with SVD is wide and may result from chronic and diffuse or acute and focal ischemia (leukoaraiosis and lacunar infarction) as well as from small-vessel rupture (cerebral microbleeds and intracerebral hemorrhage). Several lines of evidence from family and twin studies support the hypothesis that genetic factors may contribute to SVD pathogenesis. Identification of genetic susceptibility factors for SVD may improve our knowledge of SVD pathogenesis and help to identify new therapeutic targets to reduce the burden of SVD-related cognitive decline and stroke disability. A number of monogenic conditions presenting with clinical features of SVD have been described. Although monogenic disorders account for only a small proportion of SVD, study of these diseases may provide further insight into the pathogenesis of SVD. In most cases, however, SVD is thought to be a multifactorial disorder. Several genetic association studies, conducted using the candidate gene and, more recently, the genome-wide approach, have so far failed to demonstrate a convincing association between SVD and genetic variants. Methodological issues, particularly related to inaccurate or heterogeneous phenotyping and insufficient sample sizes, have been invoked as possible reasons for this. Large collaborative efforts and robust replication, as well as implementation of new genetic approaches, are necessary to identify genetic susceptibility factors for complex SVD.

Advances in imaging of new targets for pharmacological intervention in stroke: real-time tracking of T-cells in the ischaemic brain.

BACKGROUND AND PURPOSE: T-cells may play a role in the evolution of ischaemic damage and repair, but the ability to image these cells in the living brain after a stroke has been limited. We aim to extend the technique of real-time in situ brain imaging of T-cells, previously shown in models of immunological diseases, to models of experimental stroke. EXPERIMENTAL APPROACH: Male C57BL6 mice (6-8 weeks) (n= 3) received a total of 2-5 x 10(6) carboxyfluorescein diacetate succinimidyl ester (CFSE)-labelled lymphocytes from donor C57BL6 mice via i.v. injection by adoptive transfer. Twenty-four hours later, recipient mice underwent permanent left distal middle cerebral artery occlusion (MCAO) by electrocoagulation or by sham surgery under isoflurane anaesthesia. Female hCD2-green fluorescent protein (GFP) transgenic mice that exhibit GFP-labelled T-cells underwent MCAO. At 24 or 48 h post-MCAO, a sagittal brain slice (1500 microm thick) containing cortical branches of the occluded middle cerebral artery (MCA) was dissected and used for multiphoton laser scanning microscopy (MPLSM). KEY RESULTS: Our results provide direct observations for the first time of dynamic T-cell behaviour in living brain tissue in real time and herein proved the feasibility of MPLSM for ex vivo live imaging of immune response after experimental stroke. CONCLUSIONS AND IMPLICATIONS: It is hoped that these advances in the imaging of immune cells will provide information that can be harnessed to a therapeutic advantage.

Imaging T-cell movement in the brain during experimental cerebral malaria.

T-cells are known to play a role in the pathology associated with experimental cerebral malaria, although it has not previously been possible to examine their behaviour in brain. Using multiphoton laser scanning microscopy, we have examined the migration and movement of these cells in brain tissue. We believe that this approach will help define host-parasite interactions and examine how intervening in these relationships affects the development of cerebral pathology.

Neuroprotective effect of C1-inhibitor following traumatic brain injury in mice.

BACKGROUND: The goal of the study was to evaluate the effects of Cl-inhibitor (C1-INH), an endogenous glycoprotein endowed with multiple anti-inflammatory actions, on cognitive and histological outcome following controlled cortical impact (CCI) brain injury. METHODS: Male C57B1/6 mice (n=48) were subjected to CCI brain injury. After brain injury, animals randomly received an intravenous infusion of either C1-INH (15 U either at 10 minutes or 1 hour postinjury) or saline (equal volume, 150 microl at 10 min postinjury). Uninjured control mice received identical surgery and saline injection without brain injury. Cognitive function was evaluated at 4 weeks postinjury using the Morris Water Maze. Mice were subsequently sacrificed, the brains were frozen and serial sections were cut. Traumatic brain lesion was assessed by dividing the area of the ipsilateral hemisphere for the area of the contralateral one at the level of the injured area of the brain. FINDINGS: Brain-injured mice receiving C1-INH at 10 min postinjury showed attenuated cognitive dysfunction compared to brain-injured mice receiving saline (p < 0.01). These mice also showed a significantly reduced traumatic brain lesion compared to mice receiving saline (p < 0.01). Mice receiving C1-INH at 1 hour post injury did not show a significant improvement in either cognitive or histological outcome. Conclusions Our results suggest that administration of C1-INH at 10 minutes postinjury attenuates cognitive deficits and histological damage associated with traumatic brain injury.

Effect of traumatic brain injury on cognitive function in mice lacking p55 and p75 tumor necrosis factor receptors.

BACKGROUND: Tumor necrosis factor (TNF)-alpha has been suggested to play both a deleterious and beneficial role in neurobehavioral dysfunction and recovery following traumatic brain injury (TBI). The goal of this study was to evaluate the specific role of tumor necrosis factor (TNF) receptors p55 and p75 in mediating cognitive outcome following controlled cortical impact (CCI) brain injury by comparing post-traumatic cognitive function in mice with genetically engineered deletion of the gene for either p55 (-/-) or p75 (-/-) receptors. METHOD: Male C57B1/6 mice (WT, n=29), and mice genetically engineered to delete p55 TNF (p55 (-/-), n=8) or p75 TNF (p75 (-/-), n=23) receptors were used. They were anesthetized with intraperitoneal (i.p.) administration of sodium pentobarbital (65 mg/kg) and subjected to CCI brain injury of moderate severity. Sham-injured control mice were anesthetized and surgically prepared similarly but they received no impact. Assessment of mRNA expression of inflammatory, proapoptotic and antiapoptotic genes was done by real time-polymerase chain reaction (RT-PCR). Cognitive outcome was evaluated at 4 weeks postinjury using the Morris water maze (MWM). FINDINGS: mRNA expression of inflammatory, proapoptotic and antiapoptotic genes prior to TBI did not reveal any baseline difference between p55 and p75 (-/-) mice. WT mice showed greater baseline expression of inflammatory genes. The learning ability of p55 (-/-) brain-injured mice was significantly better than that observed in p75 (-/-) brain-injured mice (p < 0.05). Cognitive learning in WT control mice fell between the p55 (-/-) and p75 (-/-) mice. CONCLUSIONS: These data suggest that TNF-alpha may both exacerbate cognitive dysfunction via p55 receptor and attenuate it via p75 receptor.

HSV-1-mediated IL-1 receptor antagonist gene therapy ameliorates MOG(35-55)-induced experimental autoimmune encephalomyelitis in C57BL/6 mice.

Primary proinflammatory cytokines, such as IL-1beta, play a crucial pathogenic role in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE), and may represent, therefore, a suitable therapeutic target. We have previously established the delivery of anti-inflammatory cytokine genes within the central nervous system (CNS), based on intracisternal (i.c.) injection of non-replicative HSV-1-derived vectors. Here we show the therapeutic efficacy of i.c. administration of an HSV-1-derived vector carrying the interleukin-1receptor antagonist (IL-1ra) gene, the physiological antagonist of the proinflammatory cytokine IL-1, in C57BL/6 mice affected by myelin oligodendrocyte glycoprotein-induced EAE. IL-1ra gene therapy is effective preventively, delaying EAE onset by almost 1 week (22.4+/-1.4 days post-immunization vs 15.9+/-2.1 days in control mice; P=0.0229 log-rank test), and decreasing disease severity. Amelioration of EAE course was associated with a reduced number of macrophages infiltrating the CNS and in a decreased level of proinflammatory cytokine mRNA in the CNS, suggesting an inhibitory activity of IL-1ra on effector cell recruitment, as antigen-specific peripheral T-cell activation and T-cell recruitment to the CNS is unaffected. Thus, local IL-1ra gene therapy may represent a therapeutic alternative for the inhibition of immune-mediated demyelination of the CNS.

Travel time and trajectory moments of conservative solutes in two-dimensional convergent flows.

We address advective transport of a solute traveling toward a single pumping well in a two-dimensional randomly heterogeneous aquifer. The two random variables of interest are the trajectory followed by an individual particle from the injection point to the well location and the particle travel time under steady-state conditions. Our main objective is to derive the predictors of trajectory and travel time and the associated uncertainty, in terms of their first two statistical moments (mean and variance). We consider a solute that undergoes mass transfer between a mobile and an immobile zone. Based on Lawrence et al. [Lawrence, A.E., Sánchez-Vila, X., Rubin, Y., 2002. Conditional moments of the breakthrough curves of kinetically sorbing solute in heterogeneous porous media using multirate mass transfer models for sorption and desorption. Water Resour. Res. 38 (11), 1248, doi:10.1029/2001WR001006.], travel time moments can be written in terms of those of a conservative solute times a deterministic quantity. Moreover, the moments of solute particles trajectory do not depend on mass transfer processes. The resulting mean and variance of travel time and trajectory for a conservative species can be written as functions of the first, second moments and cross-moments of trajectory and velocity components. The equations are developed from a consistent second order expansion in sigmaY (standard deviation of the natural logarithm of hydraulic conductivity). Our solution can be completely integrated with the moment equations of groundwater flow of Guadagnini and Neuman [Guadagnini, A., Neuman, S.P., 1999a. Nonlocal and localized analyses of conditional mean steady state flow in bounded, randomly non uniform domains 1. Theory and computational approach. Water Resour. Res. 35(10), 2999-3018.,Guadagnini, A., Neuman, S.P., 1999b. Nonlocal and localized analyses of conditional mean steady state flow in bounded, randomly non uniform domains 2. Computational examples. Water Resour. Res. 35(10), 3019-3039.], it is free of distributional assumptions regarding the log conductivity field, and formally includes conditioning. We present analytical expressions for the unconditional case by making use of the results of Riva et al. [Riva, M., Guadagnini, A., Neuman, S.P., Franzetti, S., 2001. Radial flow in a bounded randomly heterogeneous aquifer. Transport in Porous Media 45, 139-193.]. The quality of the solution is supported by numerical Monte Carlo simulations. Potential uses of this work include the determination of aquifer reclamation time by means of a single pumping well, and the demarcation of the region potentially affected by the presence of a contaminant in the proximity of a well, whenever the aquifer is very thin and Dupuit-Forchheimer assumption holds.

Inflammatory response and glia activation in developing rat hippocampus after status epilepticus.

PURPOSE: We investigated the activation of microglia and astrocytes, induction of cytokines, and hippocampal neuronal damage, 4 and 24 h after kainic acid-induced status epilepticus (SE) in postnatal day (PN) 9, 15, and 21 rats. METHODS: Limbic seizures were induced by systemic injection of kainic acid. Glia activation and neuronal cell loss were studied by using immunocytochemistry and Western blot. Cytokine expression was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) followed by Southern blot quantification. RESULTS: After SE onset, hippocampal glia activation, cytokine expression, and neuronal damage are all age-dependent phenomena. In the hippocampus, neuronal injury occurs only when cytokines are induced in glia, and cytokine synthesis precedes the appearance of degenerating neurons. Neuronal injury is more pronounced when interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) are produced in addition to IL-1beta. CONCLUSIONS: This study shows that cytokine induction in rat brain after sustained seizures is age dependent, and it is associated with the appearance of cell injury.

Glia activation and cytokine increase in rat hippocampus by kainic acid-induced status epilepticus during postnatal development.

In adult rats, status epilepticus (SE) induces cytokine production by glia especially when seizures are associated with neuronal injury. This suggests that cytokines may play a role in seizure-induced neuronal damage. As SE-induced injury is age-specific, we used rats of different ages (with distinct susceptibilities to seizure-induced neuronal injury) to elucidate the role of cytokines in this process. Thus, we investigated the activation of microglia and astrocytes, induction of cytokines, and hippocampal neuronal injury 4 and 24 h following kainic acid-induced SE in postnatal day (PN) 9, 15, and 21 rats. At PN9, there was little activation of microglia and astrocytes at any time point studied. Interleukin-1beta (IL), tumor necrosis factor-alpha (TNF), and IL-6 or the naturally occurring IL-1 receptor antagonist (Ra) mRNA expression did not increase. No evidence of cell injury has been detected. At PN15, immunostaining of microglia and astrocytes was enhanced, but only IL-1beta mRNA expression was increased. These changes were observed 4 h after SE. Scattered injured neurons in CA3 and subiculum, but not in any other region, were present 24 h following SE. At PN21, immunostaining of microglia and astrocytes and the mRNA expression of all cytokines studied was significantly increased already 4 h after SE. At 24 h, many injured neurons were present in CA1 and CA3 regions and in 40% of rats in other forebrain areas. These data show that (i) the pattern of glia activation and cytokine gene transcription induced by SE is age-dependent and (ii) neuronal injury in the hippocampus occurs only when cytokines are induced and their synthesis precedes the appearance of neuronal damage. Thus, cytokine expression in immature brain is associated specifically with cell injury rather than with seizures per se, suggesting that proinflammatory cytokines may contribute to the occurence of SE-induced hippocampal damage.

Neuroprotection by complement (C1) inhibitor in mouse transient brain ischemia.

The authors investigated the effect of the C1 inhibitor (C1-INH), the only known inhibitor of complement C1, in a murine model of transient focal ischemia. Ischemia was induced by intraluminal occlusion of the middle cerebral artery. After 2 hours, reperfusion was produced by removing the nylon monofilament occluding the artery. The effect of 15 U C1-INH (intravenously) was evaluated in terms of general and focal neurologic deficits, ischemic volume, neutral red staining (to identify the brain areas subject to ischemic damage), and glial fibrillary acidic protein immunoreactivity (to show astrocytic response). Forty-eight hours after ischemia, C1-INH significantly improved general and focal deficits by 36% and 54%, respectively, and significantly reduced infarct volume (CI-INH, 6.69% +/- 2.93%; saline, 24.24% +/- 8.24%) of total brain. Neutral red staining further showed the strong protective effect of C1-INH in cortex, hippocampus, and striatum. Astrocyte activation induced by ischemia was not affected by C1-INH. These findings show that C1-INH displayed a potent neuroprotective action by effectively reducing ischemia-reperfusion injury.