Impact of perinatal factors on continuous early monitoring of brain electrocortical activity in very preterm newborns by amplitude-integrated EEG.

Background:Amplitude-integrated electroencephalogram (aEEG) is increasingly used for neuromonitoring in preterms. We aimed to quantify the effects of gestational age (GA), postnatal age (PNA), and other perinatal factors on the development of aEEG early after birth in very preterm newborns with normal cerebral ultrasounds.Methods:Continuous aEEG was prospectively performed in 96 newborns (mean GA: 29.5 (range: 24.4-31.9) wk, birth weight 1,260 (580-2,120) g) during the first 96 h of life. aEEG tracings were qualitatively (maturity scores) and quantitatively (amplitudes) evaluated using preestablished criteria.Results:A significant increase in all aEEG measures was observed between day 1 and day 4 and for increasing GA (P < 0.001). The effect of PNA on aEEG development was 6.4- to 11.3-fold higher than that of GA. In multivariate regression, GA and PNA were associated with increased qualitative and quantitative aEEG measures, whereas small-for-GA status was independently associated with increased maximum aEEG amplitude (P = 0.003). Morphine administration negatively affected all aEEG measures (P < .05), and caffeine administration negatively affected qualitative aEEG measures (P = 0.02).Conclusion:During the first few days after birth, aEEG activity in very preterm infants significantly develops and is strongly subjected to the effect of PNA. Perinatal factors may alter the early aEEG tracing and interfere with its interpretation.

In vitro biotransformation of the selective serotonin reuptake inhibitor citalopram, its enantiomers and demethylated metabolites by monoamine oxidase in rat and human brain preparations

This study was conducted to identify enzyme systems eventually catalysing a local cerebral metabolism of citalopram, a widely used antidepressant of the selective serotonin reuptake inhibitor type. The metabolism of citalopram, of its enantiomers and demethylated metabolites was investigated in rat brain microsomes and in rat and human brain mitochondria. No cytochrome P-450 mediated transformation was observed in rat brain. By analysing H2O2 formation, monoamine oxidase A activity in rat brain mitochondria could be measured. In rat whole brain and in human frontal cortex, putamen, cerebellum and white matter of five brains monoamine oxidase activity was determined by the stereoselective measurement of the production of citalopram propionate. All substrates were metabolised by both forms of MAO, except in rat brain, where monoamine oxidase B activity could not be detected. Apparent Km and Vmax of S-citalopram biotransformation in human frontal cortex by monoamine oxidase B were found to be 266 microM and 6.0 pmol min(-1) mg(-1) protein and by monoamine oxidase A 856 microM and 6.4 pmol min(-1) mg(-1) protein, respectively. These Km values are in the same range as those for serotonin and dopamine metabolism by monoamine oxidases. Thus, the biotransformation of citalopram in the rat and human brain occurs mainly through monoamine oxidases and not, as in the liver, through cytochrome P-450.

The role of C-Jun N-terminal kinase in a mouse model of intracerebral hemorrhage

Background: Intracerebral hemorrhage (ICH) is a subtype of stroke characterized by a haematoma within the brain parenchyma resulting from blood vessel rupture and with a poor outcome. In ICH, the blood entry into the brain triggers toxicity resulting in a substantial loss of neurons and an inflammatory response. At the same time, blood-brain barrier (BBB) disruption increases water content (edema) leading to growing intracranial pressure, which in turn worsens neurological outcome. Although the clinical presentation is similar in ischemic and hemorrhagic stroke, the treatment is different and the stroke type needs to be determined beforehand by imaging which delays the therapy. C-Jun N-terminal kinases (JNKs) are a family of kinases activated in response to stress stimuli and involved in several pathways such as apoptosis. Specific inhibition of JNK by a TAT-coupled peptide (XG-102) mediates strong neuroprotection in several models of ischemic stroke in rodents. Recently, we have observed that the JNK pathway is also activated in a mouse model of ICH, raising the question of the efficacy of XG-102 in this model. Method: ICH was induced in the mouse by intrastriatal injection of bacterial collagenase (0,1 U). Three hours after surgery, animals received an intravenous injection of 100 mg/kg of XG-102. The neurological outcome was assessed everyday until sacrifice using a score (from 0 to 9) based on 3 behavioral tests performed daily until sacrifice. Then, mice were sacrificed at 6 h, 24 h, 48 h, and 5d after ICH and histological studies performed. Results: The first 24 h after surgery are critical in our ICH mice model, and we have observed that XG-102 significantly improves neurological outcome at this time point (mean score: 1,8 + 1.4 for treated group versus 3,4+ 1.8 for control group, P<0.01). Analysis of the lesion volume revealed a significant decrease of the lesion area in the treated group at 48h (29+ 11mm3 in the treated group versus 39+ 5mm3 in the control group, P=0.04). XG-102 mainly inhibits the edema component of the lesion. Indeed, a significant inhibition Journal of Cerebral Blood Flow & Metabolism (2009) 29, S490-S493 & 2009 ISCBFM All rights reserved 0271-678X/09 $32.00 www.jcbfm.com of the brain swelling was observed in treated animals at 48h (14%+ 13% versus 26+ 9% in the control group, P=0.04) and 5d (_0.3%+ 4.5%versus 5.1+ 3.6%in the control group, P=0.01). Conclusions: Inhibition of the JNK pathway by XG- 102 appears to lead to several beneficial effects. We can show here a significant inhibition of the cerebral edema in the ICH model providing a further beneficial effect of the XG-102 treatment, in addition to the neuroprotection previously described in the ischemic model. This result is of interest because currently, clinical treatment for brain edema is limited. Importantly, the beneficial effects observed with XG-102 in models of both stroke types open the possibility to rapidly treat stroke patients before identifying the stroke subtype by imaging. This will save time which is precious for stroke outcome.

Longitudinal MR assessment of hypoxic ischemic injury in the immature rat brain.

Extremely preterm infants commonly show brain injury with long-term structural and functional consequences. Three-day-old (P3) rat pups share some similarities in terms of cerebral development with the very preterm infant (born at 24-28 weeks of gestation). The aim of this study was to assess longitudinally the cerebral structural and metabolic changes resulting from a moderate neonatal hypoxic ischemic injury in the P3 rat pup using high-field (9.4 T) MRI and localized (1) H magnetic resonance spectroscopy techniques. The rats were scanned longitudinally at P3, P4, P11, and P25. Volumetric measurements showed that the percentage of cortical loss in the long term correlated with size of damage 6 h after hypoxia-ischemia, male pups being more affected than female. The neurochemical profiles revealed an acute decrease of most of metabolite concentrations and an increase in lactate 24 h after hypoxia-ischemia, followed by a recovery phase leading to minor metabolic changes at P25 in spite of an abnormal brain development. Further, the increase of lactate concentration at P4 correlated with the cortical loss at P25, giving insight into the early prediction of long-term cerebral alterations following a moderate hypoxia-ischemia insult that could be of interest in clinical practice.

The JNK binding domain of islet-brain 1 inhibits IL-1 induced JNK activity and apoptosis but not the transcription of key proapoptotic or protective genes in insulin-secreting cell lines.

The stress-activated protein kinase c-Jun NH2-terminal kinase (JNK) is a central signal for interleukin-1beta (IL-1beta)-induced apoptosis in insulin-producing beta-cells. The cell-permeable peptide inhibitor of JNK (JNKI1), that introduces the JNK binding domain (JBD) of the scaffold protein islet-brain 1 (IB1) inside cells, effectively prevents beta-cell death caused by this cytokine. To define the molecular targets of JNK involved in cytokine-induced beta-cell apoptosis we investigated whether JNKI1 or stable expression of JBD affected the expression of selected pro- and anti-apoptotic genes induced in rat (RIN-5AH-T2B) and mouse (betaTC3) insulinoma cells exposed to IL-1beta. Inhibition of JNK significantly reduced phosphorylation of the specific JNK substrate c-Jun (p&lt;0.05), IL-1beta-induced apoptosis (p&lt;0.001), and IL-1beta-mediated c-fos gene expression. However, neither JNKI1 nor JBD did influence IL-1beta-induced NO synthesis or iNOS expression or the transcription of the genes encoding mitochondrial manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase rho (GSTrho), heat shock protein (HSP) 70, IL-1beta-converting enzyme (ICE), caspase-3, apoptosis-inducing factor (AIF), Bcl-2 or Bcl-xL. We suggest that the anti-apoptotic effect of JNK inhibition by JBD is independent of the transcription of major pro- and anti-apoptotic genes, but may be exerted at the translational or posttranslational level.

A New Imaging Software To Evaluate The Centration Of Capsulorhexis And Intraocular Lens (IOL) After Cataract Surgery

Purpose: IOL centration and stability after cataract surgery is of high interest for cataract surgeons and IOL-producing companies. We present a new imaging software to evaluate the centration of the rhexis and the centration of the IOL after cataract surgery.Methods: We developed, in collaboration with the Biomedical Imaging Group (BIG), EPFL, Lausanne, a new working tool in order to assess precisely outcomes after IOL-implantation, such as ideal capsulorhexis and IOL-centration. The software is a plug-in of ImageJ, a general-purpose image processing and image-analysis package. The specifications of this software are: evaluation of the rhexis-centration and evaluation the position of the IOL in the posterior chamber. The end points are to analyze the quality of the centration of a rhexis after cataract surgery, the deformation of the rhexis with capsular bag retraction and the centration of the IOL after implantation.Results: This software delivers tools to interactively measure the distances between limbus, IOL and capsulorhexis and its changes over time. The user is invited to adjust nodes of three radial curves for the limbus, rhexis and the optic of the IOL. The radial distances of the curves are computed to evaluate the IOL implantation. The user is also able to define patterns for ideal capsulorhexis and optimal IOL-centration. We are going to present examples of calculations after cataract surgery.Conclusions: Evaluation of the centration of the rhexis and of the IOL after cataract surgery is an important end point for optimal IOL implantation after cataract surgery. Especially multifocal or accommodative lenses need a precise position in the bag with a good stability over time. This software is able to evaluate these parameters just after the surgery but also its changes over time. The results of these evaluations can lead to an optimizing of surgical procedures and materials.

Selective distribution of lactate dehydrogenase isoenzymes in neurons and astrocytes of human brain.

In vertebrates, the interconversion of lactate and pyruvate is catalyzed by the enzyme lactate dehydrogenase. Two distinct subunits combine to form the five tetrameric isoenzymes of lactate dehydrogenase. The LDH-5 subunit (muscle type) has higher maximal velocity (Vmax) and is present in glycolytic tissues, favoring the formation of lactate from pyruvate. The LDH-1 subunit (heart type) is inhibited by pyruvate and therefore preferentially drives the reaction toward the production of pyruvate. There is mounting evidence indicating that during activation the brain resorts to the transient glycolytic processing of glucose. Indeed, transient lactate formation during physiological stimulation has been shown by 1H-magnetic resonance spectroscopy. However, since whole-brain arteriovenous studies under basal conditions indicate a virtually complete oxidation of glucose, the vast proportion of the lactate transiently formed during activation is likely to be oxidized. These in vivo data suggest that lactate may be formed in certain cells and oxidized in others. We therefore set out to determine whether the two isoforms of lactate dehydrogenase are localized to selective cell types in the human brain. We report here the production and characterization of two rat antisera, specific for the LDH-5 and LDH-1 subunits of lactate dehydrogenase, respectively. Immunohistochemical, immunodot, and western-blot analyses show that these antisera specifically recognize their homologous antigens. Immunohistochemistry on 10 control cases demonstrated a differential cellular distribution between both subunits in the hippocampus and occipital cortex: neurons are exclusively stained with the anti-LDH1 subunit while astrocytes are stained by both antibodies. These observations support the notion of a regulated lactate flux between astrocytes and neurons.

Inflammatory responses in aggregating rat brain cell cultures subjected to different demyelinating conditions.

To study inflammatory reactions occurring in relation to demyelination, aggregating rat brain cell cultures were subjected to three different demyelinating insults, i.e., (i) lysophosphatidylcholine (LPC), (ii) interferon-gamma combined with lipopolysaccharide (IFN-gamma+LPS), and (iii) anti-MOG antibodies plus complement (alpha-MOG+C). Demyelination was assessed by measuring the expression of myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG), and the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP). The accompanying inflammatory reactions were examined by the quantification of microglia-specific staining, by immunostaining for glial fibrillary acidic protein (GFAP), and by measuring the mRNA expression of a panel of inflammation-related genes. It was found that all three demyelinating insults decreased the expression of MBP and MOG, and induced microglial reactivity. LPC and alpha-MOG+C, but not IFN-gamma+LPS, decreased CNP activity; they also caused the appearance of macrophagic microglia, and increased GFAP staining indicating astrogliosis. LPC affected also the integrity of neurons and astrocytes. LPC and IFN-gamma+LPS upregulated the expression of the inflammation-related genes IL-6, TNF-alpha, Ccl5, Cxcl1, and iNOS, although to different degrees. Other inflammatory markers were upregulated by only one of the three insults, e.g., Cxcl2 by LPC; IL-1beta and IL-15 by IFN-gamma+LPS; and IFN-gamma by alpha-MOG+C. These findings indicate that each of the three demyelinating insults caused distinct patterns of demyelination and inflammatory reactivity, and that of the demyelinating agents tested only LPC exhibited general toxicity.

Ophtalmologie. Nouvelles tendances dans la chirurgie de la cataracte [Ophthalmology. New trends in cataract surgery].

Cataract surgery is the most frequent surgery performed in the world. Modernization of cataract surgery is a continuous process and recent technological progress have enlarged the spectrum of treatable refractive errors, improved safety of surgery, speed of visual recovery and reduction of complications rate. Thus, during the last years, refractive intraocular lenses such as toric and multifocal IOLS have been introduced in practice, as well as torsional phacoemulsification and corneal microincision. For endophthalmitis prophylaxis, modern management includes intracameral injection of antibiotics. The future of cataract surgery is probably to replace phacoemulsification surgery by laser surgery, which is safer and more reproducible.

Thyrotropin-releasing hormone-stimulated thyrotropin expression involves islet-brain-1/c-Jun N-terminal kinase interacting protein-1.

Islet-brain-1 (IB1)/c-Jun N-terminal kinase interacting protein 1 (JIP-1) is a scaffold protein that is expressed at high levels in neurons and the endocrine pancreas. IB1/JIP-1 interacts with the c-Jun N-terminal kinase and mediates the specific physiological stimuli (such as cytokines). However, the potential role of the protein in the pituitary has not been evaluated. Herein, we examined expression of the gene encoding IB1/JIP-1 and its translated product in the anterior pituitary gland and a pituitary cell line, GH3. We then examined the potential role of IB1/JIP-1 in controlling TSH-beta gene expression. Exposure of GH3 cells to TRH stimulated the expression of IB1/JIP-1 protein levels, mRNA, and transcription of the promoter. The increase of IB1/JIP-1 content by transient transfection study of a vector encoding IB1/JIP-1 or by the stimulation of TRH stimulates TSH-beta promoter activity. This effect is not found in the presence of a mutated nonfunctional (IB1S59N) IB1/JIP-1 protein. Together, these facts point to a central role of the IB1/JIP-1 protein in the control of TRH-mediated TSH-beta stimulation.

Differential transgene expression profiles from rAAV2/1 vectors using the tetON and CMV promoters in the rat brain.

The biodistribution of transgene expression in the CNS after localized stereotaxic vector delivery is an important issue for safety of gene therapy for neurological diseases. The cellular specificity of transgene expression from rAAV2/1 vectors using the tetON expression cassette in comparison with the CMV promoter was investigated in the rat nigrostriatal pathway. After intrastriatal injection, although GFP was mainly expressed into neurons with both vectors, the relative proportions of DARPP-32+ projection neurons and parvalbumin+ interneurons were respectively 13:1 and 2:1 for the CMV and tetON vectors. DARP32+ neurons projecting to the globus pallidus were strongly GFP+ with both vectors, whereas those projecting to the substantia nigra pars reticulata (SNpr) were efficiently labeled by the CMV but poorly by the tetON vector. Numerous GFP+ cells were evidenced in the subventricular zone with both vectors. However, in the olfactory bulb (OB), GFP+ neurons were observed with the CMV but not the tetON vector. We conclude that the absence of significant amounts of transgene product in distant regions (SN and OB) constitutes a safety advantage of the AAV2/1-tetON vector for striatal gene therapy. Midbrain injections resulted in selective GFP expression in tyrosine hydroxylase+ neurons by the tetON vector whereas with the CMV vector, GFP+ cells covered a widespread area of the midbrain. The biodistribution of GFP protein corresponded to that of the transcripts and not of the viral genomes. We conclude that the rAAV2/1-tetON vector constitutes an interesting tool for specific transgene expression in midbrain dopaminergic neurons.