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Even in the absence of serious injuries and fatalities, landslide and flood events can have significant socio-economic impacts. These include the severance of access to and from relatively remote communities for services and markets for goods; employment, health and educational opportunities; and social activities. The economic impacts can be classified as: direct economic impacts, direct consequential economic impacts, and indirect consequential economic impacts. In addition, the vulnerability shadow cast can be extensive, and its geographical extent can be determined by the transport network rather than the relatively small footprint of the event itself. Using a number of debris flow events and a flood event in Scotland this paper places values on the economic impacts of landslides and floods. It also demonstrates the widespread impact of the events by means of the vulnerability shadow that is cast.

In terms of both construction and operation, tunnels are the most energy demanding of road infrastructure assets. The construction of a road tunnel is energy intensive due to the volume of excavation required and the energy embodied in the materials that form the structure of the tunnel. In operating a tunnel, energy is consumed to provide adequate lighting, signing and ventilation for drivers, to maintain drainage systems and to deal with emergency situations. The European Directive on the Safe Operation of Road Tunnels requires the installation of engineering and safety systems to maintain the safe operation of the tunnel. As the operational lifetime of a tunnel is typically in excess of 100 years, energy usage through operation can soon outweigh that due to construction and therefore, the former provides the focus for this project. The Realistic Energy Efficient Tunnel Solutions (REETS) project aims to enhance the energy efficiency of road tunnel operation through the promotion and implementation of appropriate technologies.REETS commenced with a wide-ranging review of energy-efficient technologies. This covered technologies developed for tunnels, which could bring benefit through wider adoption, and those used for other applications that have proved effective, and could be used in tunnels. Technologies were considered for each of the main services that together maintain the functionality of a tunnel including: lighting, ventilation, drainage, and temperature regulation, with emphasis placed on the more energy demanding services. The review also covered technologies that can reduce energy consumption, by addressing energy provision and storage, and vehicle-oriented technologies that can improve safety and traffic flow. The various technologies might be implemented during the construction of the tunnel or be retrofitted later in the life cycle. The minimum criteria for technology were to (i) maintain or enhance the current levels of safety and comfort experienced by drivers using tunnels on national road networks, and (ii) meet or challenge existing standards for constructing and operating road tunnels.In the next stage of the REETS project, the most promising technologies will be evaluated through a quantitative assessment of carbon emissions and cost of implementation. The final stage will focus on facilitating the adoption of the most promising technologies through ‘hypothetical deployment’ case studies to identify barriers to the adoption of technologies and appropriate reconciliatory measures.

Most research focuses on overt stroke caused by blockage of major blood vessels. Less attention has been paid to small vessel disease which gives rise to covert stroke that often leads to vascular cognitive impairment (VCI). One reason for this may be the relative lack of relevant animal models. Herein, we describe, a model of VCI induced in middle-aged Sprague-Dawley rats exposed to a diet high in saturated fats, salt and refined sugar (HFSS). In Experiment 1, rats were fed HFSS and subjected to a small mediodorsal (MD) thalamic stroke with or without concomitant permanent bilateral carotid artery occlusion. MD lesions produce significant executive dysfunction in an attention set-shift task ( p = 0.012). In Experiment 2, rats were exposed to either HFSS or control diet and functional effects assessed. We found significant hypertension ( p = 0.013), blockage of brain microvessels ( p = 0.018) and white matter atrophy ( p = 0.039) in HFSS diet animals. As in Experiment 1, profound, specific set-shifting executive dysfunction was noted ( p = 0.003) following both small MD infarcts (0.332 mm3) and the HFSS diet. In summary, these data describe a middle-aged animal model of VCI that includes clinically relevant metabolic disturbances and small vessel disease and as such may be helpful in developing new cognitive therapies.

Cognitive dysfunction, as a consequence of dementia, is a significant cause of morbidity lacking efficacious treatment. Females comprise at least half of this demographic but have been vastly underrepresented in preclinical studies. The current study addressed this gap by assessing the protective efficacy of physical exercise and cognitive activity on learning and memory outcomes in a rat model of vascular dementia. Forty ovariectomized Sprague-Dawley rats (~6 months old) were exposed to either a diet high in saturated fats and refined sugars or standard laboratory chow and underwent either chronic bilateral carotid occlusion or Sham surgery. Learning and memory abilities were evaluated using standard cognitive outcomes over the ensuing 6 months, followed by histologic analyses of hippocampal CA1 neurons. In Experiment 1, we confirmed hypoperfusion-induced cognitive dysfunction using a 2 × 2 (Surgery × Diet) experimental design, without alterations in hippocampal architecture. In Experiment 2, hypoperfused animals were either exposed to alternating days of physical (wheel running) and cognitive activity (modified Hebb–Williams maze) or sedentary housing. In contrast to males, this combination rehabilitation paradigm did not improve cognition or histopathologic outcomes in hypoperfused animals. These findings, highlighting differences between female and male animals, show the necessity of including both sexes in preclinical experimentation.

Inflammation modulates tissue damage in relapsing-remitting multiple sclerosis (MS) both acutely and chronically, but its severity is difficult to evaluate with conventional MRI analysis. In mice with experimental allergic encephalomyelitis (EAE, a model of MS), we administered ultra small particles of iron oxide to track macrophage-mediated inflammation during the onset (relapse) and recovery (remission) of disease activity using high field MRI. We performed MRI texture analysis, a sensitive measure of tissue regularity, and T2 assessment both in EAE lesions and the control tissue, and measured spinal cord volume. We found that inflammation was 3 times more remarkable at onset than at recovery of EAE in histology yet demyelination appeared similar across animals and disease course. In MRI, lesion texture was more heterogeneous; T2 was lower; and spinal cord volume was greater in EAE than in controls, but only MRI texture was worse at relapse than at remission of EAE. Moreover, MRI texture correlated with spinal cord volume and tended to correlate with the extent of disability in EAE. While subject to further confirmation, our findings may suggest the sensitivity of MRI texture analysis for accessing inflammation.

Most basic science research has focused on overt stroke caused by blockage of major blood vessels. Less attention has been paid to small vessel disease giving rise to covert stroke that often leads to vascular cognitive impairment (VCI). One reason for this may be the relative lack of relevant animal models. This talk will describe a model of VCI induced in middle-aged Sprague-Dawley rats exposed to a diet high in saturated fats, salt and refined sugar (HFSS). In Experiment 1, rats fed HFSS and subjected to a small mediodorsal (MD) thalamic stroke with or without concomitant cerebral hypoperfusion experienced significant executive dysfunction. In Experiment 2, dietary influences on functional, physiological and anatomical parameters were assessed. We found significant hypertension, blockage of brain microvessels (2-photon microscopy) and white matter atrophy in HFSS diet animals. As in Experiment 1, profound, specific set-shifting executive dysfunction was noted following both small MD infarcts (0.332 mm3) and the HFSS diet. In summary, these data describe a middle-aged animal model of VCI that includes clinically-relevant metabolic disturbances and small vessel disease and as such may be helpful in developing new cognitive therapies.

Dementia is a major cause of morbidity in the western society. Pharmacological therapies to delay the progression of cognitive impairments are modestly successful. Consequently, new therapies are urgently required to improve cognitive deficits associated with dementia. We evaluated the effects of physical and cognitive activity on learning and memory in a rat model of vascular dementia (VasD). Male Sprague-Dawley rats (6 months old) were exposed to either regular chow or a diet rich in saturated fats and sucrose and chronic bilateral common carotid artery occlusion or sham surgery. First, this model of VasD was validated using a 2 × 2 experimental design (surgery × diet) and standard cognitive outcomes. Next, using identical surgical procedures, we exposed animals to a paradigm of cognitive rehabilitation or a sedentary condition. At 16 weeks post surgery, VasD animals demonstrated significant learning and memory deficits in the Morris water maze, independent of diet. Rehabilitation significantly attenuated these cognitive deficits at this time point as well as at 24 weeks. Further, rehabilitation normalized hippocampal CA1 soma size (area and volume) to that of control animals, independent of cell number. Importantly, these findings demonstrate beneficial neuroplasticity in early middle-aged rats that promoted cognitive recovery, an area rarely explored in preclinical studies.

Many therapies have shown promise in preclinical stroke studies, but few benefit patients. A greater understanding of stroke pathophysiology is needed to successfully develop therapies, and this depends on appropriate animal models. The collagenase and blood infusion models of intracerebral hemorrhage (ICH) are widely used; yet, investigators often prefer using one model for a variety of reasons. Thus, we directly compared these to highlight advantages and limitations of each as well as the assessment approach. An ICH was created by infusing blood or bacterial collagenase into the rats' striatum. We matched initial hematoma volume in each model (Experiment 1) and assessed the time course of bleeding (Experiment 2). Functional deficits and the progression of injury were tracked over 6 weeks using behavior, magnetic resonance imaging, and histology (Experiment 3). Despite similar initial hematoma volumes, collagenase-induced ICH resulted in a greater blood—brain barrier breakdown and more damage to the striatum, substantia nigra, white matter, and cortex. Magnetic resonance imaging revealed faster hematoma resolution in the blood model, and little increase in the volume of tissue lost from 1 to 6 weeks. In contrast, tissue loss continued over 4 weeks in the collagenase model. Finally, functional deficits recovered more quickly and completely in the blood model. This study highlights key differences between these models and that neither closely replicates the human condition. Thus, both should be used whenever possible taking into account the significant differences between these models and their limitations. Furthermore, this work illustrates significant weaknesses with several outcome measures.

Inflammatory leukocytes infiltrate the CNS parenchyma in neuroinflammation. This involves cellular migration across various structures associated with the blood-brain barrier: the vascular endothelium, the glia limitans, and the perivascular space between them. Leukocytes accumulate spontaneously in the perivascular space in brains of transgenic (Tg) mice that overexpress CCL2 under control of a CNS-specific promoter. The Tg mice show no clinical symptoms, even though leukocytes have crossed the endothelial basement membrane. Pertussis toxin (PTx) given i.p. induced encephalopathy and weight loss in Tg mice. We used flow cytometry, ultra-small superparamagnetic iron oxide-enhanced magnetic resonance imaging, and immunofluorescent staining to show that encephalopathy involved leukocyte migration across the glia limitans into the brain parenchyma, identifying this as the critical step in inducing clinical symptoms. Metalloproteinase (MPs) enzymes are implicated in leukocyte infiltration in neuroinflammation. Unmanipulated Tg mice had elevated expression of tissue inhibitor of metalloproteinase-1, matrix metalloproteinase (MMP)-10, and -12 mRNA in the brain. PTx further induced expression of tissue inhibitor of metalloproteinase-1, metalloproteinase disintegrins-12, MMP-8, and -10 in brains of Tg mice. Levels of the microglial-associated MP MMP-15 were not affected in control or PTx-treated Tg mice. PTx also up-regulated expression of proinflammatory cytokines IL-1β and TNF-α mRNA in Tg CNS. Weight loss and parenchymal infiltration, but not perivascular accumulation, were significantly inhibited by the broad-spectrum MP inhibitor BB-94/Batimastat. Our finding that MPs mediate PTx-induced parenchymal infiltration to the chemokine-overexpressing CNS has relevance for the pathogenesis of human diseases involving CNS inflammation, such as multiple sclerosis.

The intraluminal suture model of transient middle cerebral artery occlusion (MCAO) in the Sprague Dawley strain of rats characteristically results in an inconsistently sized brain lesion. The purpose of the investigation reported here was to determine whether there were strong point-to-point correlations between the degree of cortical lesion size, as assessed in vivo using T2-weighted magnetic resonance imaging (MRI) and corresponding cortical lesion size using routine histopathological techniques. Moreover, we aimed to investigate if cortical lesion size as determined by these two modalities correlates with neurological and/or skilled motor deficits observed in individual animals. Baseline behavioral scores were obtained on the animals prior to receiving 60 min of transient MCAO. Following MCAO, animals were tested for 1-21 days for neurological deficits. T2-weighted MRIs of the cortex were taken at two and seven days post-MCAO. At 30 and 60 days the rats were retested for forelimb dexterity in the staircase test. Subsequently, the cortex was examined for histopathological damage. Indeed, there were highly significant correlations between lesion size determined by MRI and histopathology. The degree of cortical damage observed in the T2-weighted MRI, as well as the size of the histopathological lesions were, in turn, highly correlated with the degrees of deficiencies observed in the composite neurological assessments and with the deficits involving skilled use of the contralateral forepaw (damaged side).

Dietary intake of omega-3 polyunsaturated fatty acids has been associated with decreased clotting ability and increased risk of hemorrhagic stroke. The aim of the current study was to assess the effect of dietary supplementation of omega-3 polyunsaturated fatty acid on functional outcome after hemorrhagic stroke. Rats were maintained on a diet containing approximately 30% of energy as either fish oil (rich in omega-3 fatty acids) or safflower oil (rich in omega-6 fatty acids) and subjected to either intracerebral hemorrhage or sham surgery. Behavioral tests, infarct measurement, and MR imaging techniques were used to assess outcome. While there was no significant difference in infarct volume between rats on different diets, animals maintained on a diet enriched with fish oil exhibited increased cerebral blood flow after surgery. These animals were significantly more impaired than rats fed the safflower-oil-enriched diet in tests of forelimb dexterity and fine motor control. These results suggest that high intake of omega-3 polyunsaturated fatty acids may not only increase the risk of hemorrhagic stroke as shown in previous studies, but most importantly may lead to a more severe motor impairment and a poorer functional outcome after such an event.

Periventricular/intraventricular hemorrhage (PVH/IVH) into brain can occur in premature infants and is associated with poor developmental outcome. The purpose of this study was to develop and characterize a model of PVH/IVH in newborn mouse. We hypothesized that periventricular germinal matrix would exhibit reduced cell proliferation. PVH/IVH was induced in 1-day-old mice by injection of autologous blood into the periventricular tissue. Magnetic resonance images (MRI) were obtained from 15 minutes to 14 days later. Mice were killed 4 hours to 28 days later. Cell proliferation, dying cells, astrocyte and microglial reactions, neutrophils, and lymphocytes were quantified. Histological studies showed that MRI accurately localizes the hematoma but overestimates its size. The hematoma, located in the striatum and germinal tissue, always extended into the lateral ventricles. Cell proliferation, measured by Ki67 immunoreactivity, was suppressed bilaterally in germinal matrix and beyond from 8 hours to 7 days. Increased cell death was observed in the ipsilateral striatum and germinal matrix 1 and 2 days after PVH/IVH. Astrocyte and microglia reaction peaked at 2 days and persisted up to 28 days. Inflammatory response was minimal. Extravasated blood might play an important role in brain damage following PVH/IVH through suppression of cell proliferation.

Intracerebral hemorrhage (ICH) is characterized by parenchymal hematoma formation with surrounding inflammation. Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of neurological diseases defined by inflammation and cell death. To investigate the expression profile and pathogenic aspects of MMPs in ICH, we examined MMP expression in vivo using a collagenase-induced rat model of ICH. ICH increased brain MMP-2, -3, -7, and -9 mRNA levels relative to sham-injected (control) animals in the vicinity of the hematoma, but MMP-12 (macrophage metalloelastase) was the most highly induced MMP (>80-fold). Immunohistochemistry showed MMP-12 to be localized in activated monocytoid cells surrounding the hematoma. In vitro studies showed that thrombin, released during ICH, induced MMP-12 expression in monocytoid cells, which was reduced by minocycline application. Similarly, in vivo minocycline treatment significantly reduced MMP-12 levels in brain. Neuropathological studies disclosed marked glial activation and apoptosis after ICH that was reduced by minocycline treatment. Neurobehavioral outcomes also were improved with minocycline treatment compared with untreated ICH controls. Thus, select MMPs exhibit increased expression after ICH, whereas minocycline is neuroprotective after ICH by suppressing monocytoid cell activation and downregulating MMP-12 expression.

To perform multinuclear magnetic resonance spectroscopy and imaging, a coil with a high signal-to-noise ratio and spatially uniform B1 field that covers the same volume of interest at several frequencies is preferred. The design of a surface coil that reduces contaminating signals from the surface-lying tissues and improves uniformity of the B1 field within the same preselected volume for both31P and 1H is described. Testing of the coil demonstrated acquisition of proton images and 31P spectra from a selected voxel in rat liver at 7 T. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 17B: 11–16, 2003.

Nitrobenzylthioinosine (NBMPR) can potentiate the actions of adenosine through inhibition of adenosine influx mediated by the equilibrative nucleoside transporter subtype 1 (ENT1). As adenosine can decrease ischemic neuronal injury, we tested the hypothesis that peripheral administration of the pro-drug NBMPR-phosphate (NBMPR-P) can increase brain adenosine levels and reduce ischemia-induced loss of hippocampal CA1 neurons. Pre-ischemic, but not post-ischemic, peripheral administration of NBMPR-P significantly (P = 0.03) increased neuronal survival. Mechanistically, NBMPR-induced neuroprotection was associated with significant (P = 0.03) increases in adenosine levels relative to saline-treated controls. Hypothermia was tested for but did not account for the beneficial effects of NBMPR. Together, these data suggest that selective inhibition of ENT1 adenosine transporters can increase post-ischemic levels of adenosine and reduce ischemic neuronal death.

Adenosine levels increase in brain during cerebral ischemia, and adenosine has receptor-mediated neuroprotective effects. This study was performed to test the hypothesis that nitrobenzylthioinosine (NBMPR), a selective and potent inhibitor of one adenosine transporter subtype termed ENT1, or es, can protect against ischemic neuronal injury by enhancing adenosine levels and potentiating adenosine receptor-mediated effects, including attenuation of the cellular production and release of tumor necrosis factor-alpha (TNF-alpha). In rats, the phosphorylated prodrug form of NBMPR, NBMPR-phosphate, or saline was administered by intracerebroventricular injection 30 min before forebrain ischemia. Seven days following the ischemic episode, rats were killed, and neuronal damage in the CA1 region of the hippocampus was assessed. The number of pyramidal neurons was significantly (p < 0.001) greater in the NBMPR-P treatment group. A trend toward protection was still evident at 28 days postreperfusion. Adenosine increased significantly during ischemia to levels eight- to 85-fold above basal. NBMPR-P treatment did not cause statistically significant increases in ischemic adenosine levels; however, this treatment tended to increase adenosine levels in all brain regions at 7 min postreperfusion. Ischemia-induced expression of TNF-alpha was not altered by NBMPR-P treatment, and the nonselective adenosine receptor antagonist 8-(p-sulfophenyl) theophylline did not abolish the neuroprotective effects of NBMPR-P treatment. These data indicate that NBMPR can protect CA1 pyramidal neurons from ischemic death without statistically significant effects on adenosine levels or adenosine receptor-mediated inhibition of the proinflammatory cytokine TNF-alpha.

Because free radical mechanisms may contribute to brain injury in hemorrhagic stroke, the effect of the free radical trapping agent disodium 4-[(tert-butylimino)methyl]benzene-1,3-disulfonate N-oxide (NXY-059) was investigated on outcome following intracerebral hemorrhage (ICH) in rat. ICH was induced in 20 adult rats by infusion of collagenase into the caudate-putamen. Thirty minutes later rats were treated with NXY-059 (50 mg/kg subcutaneous plus 8.8 mg/kg/h for 3 days subcutaneous delivered via implanted osmotic pumps) or saline (equivalent volumes). Magnetic resonance imaging 24 h after ICH confirmed that the hemorrhage was uniform in the two groups, and subsequent imaging at 7 and 42 days post-ICH showed that the hematoma resolved similarly in the two groups. Behavioral testing on days 1, 3, 7, 14, and 21 after ICH showed that rats treated with NXY-059 had significantly decreased neurological impairment at all times. Deficits in skilled forelimb use 4–5 weeks post-ICH, and in striatal function 6 weeks post-ICH, were not reduced by treatment with NXY-059. Treatment with NXY-059 significantly reduced the neutrophil infiltrate observed 48 h post-hemorrhage in the vicinity of the hematoma, and the number of TUNEL-positive cells 48 h post-hemorrhage at the hematoma margin. However, by 6 weeks there were no differences in neuronal densities in treated and control rats.

Background and Purpose —Tumor necrosis factor-α (TNF-α) expression is increased in brain after cerebral ischemia, although little is known about its abundance and role in intracerebral hemorrhage (ICH). A TNF-α–specific antisense oligodeoxynucleotide (ORF4-PE) was used to study the extent to which TNF-α expression influenced neurobehavioral outcomes and brain damage in a collagenase-induced ICH model in rat. Methods —Male Sprague-Dawley rats were anesthetized, and ICH was induced by intrastriatal administration of heparin and collagenase. Immediately before or 3 hours after ICH induction, ORF4-PE was administered directly into the site of ICH. TNF-α mRNA and protein levels were measured by reverse transcriptase–polymerase chain reaction and immunoblot analyses. Cell death was measured by terminal deoxynucleotidyl transferase–mediated uridine 5′triphosphate-biotin nick end labeling (TUNEL). Neurobehavioral deficits were measured for 4 weeks after ICH. Results —ICH induction (n=6) elevated TNF-α mRNA and protein levels ( P P P P P P Conclusions —These results indicate a pathogenic role for TNF-α during ICH and demonstrate that reducing TNF-α expression using antisense oligodeoxynucleotides is neuroprotective.

Conventional double quantum (DQ) editing techniques recover resonances of one metabolite at a time and are thus inefficient for monitoring metabolic changes involving several metabolites. A DQ coherence transfer double editing sequence using a dual-band DQ coherence read pulse is described here. The sequence permits simultaneous spectral editing for two metabolites with similar J coupling constants in a single scan. Simultaneous editing for taurine and gamma-aminobutyric acid (GABA) is demonstrated using solution phantoms and rat brain tissue. Selectivity of the double editing sequence for the target metabolites is as good as that achieved using conventional DQ editing which selects each metabolite individually. With experimental parameters of the double editing sequence chosen to optimize GABA editing, the sensitivity for GABA detection is the same as that with GABA editing only, while the sensitivity for taurine detection is decreased slightly compared to that with taurine editing only.

Creatine kinase (CK) catalyzes the reversible phosphorylation of MgADP by phosphocreatine and thus regulates cellular concentrations of ADP and ATP. The temperature dependence of this reaction has been determined in rat brain in vivo between 30 and 40°C using 31P NMR saturation transfer measurements. The pseudo-first-order rate constant for the forward CK reaction, kf, varies little with temperature over this range, with an apparent activation energy Ea = 14.2 ± 4.9 kJ/mol. This is considerably lower than the values of Ea for isolated CK enzymes. However, when changes in [MgADP] and [H+] with temperature are considered, a substrate concentration-independent value of Ea = 65.3 ± 9.7 kJ/mol is obtained for the maximum forward reaction velocity Vmax. This agrees well with literature values for the isolated brain-type isoform of CK.Key words: creatine kinase, activation energy, temperature, brain, rat.

Noninvasive detection of taurine, an important amino acid involved in numerous physiological processes, by in vivo 1H magnetic resonance (MR) spectroscopy is complicated by severe overlap of the taurine resonances with those of a number of other metabolites. Unambiguous differentiation of the taurine resonances requires spectral editing. In this study, the development of a localized spectral editing technique based on double-quantum filtering optimized for in vivo detection of taurine is described. The sequence recovers the taurine signal while substantially eliminating overlapping resonances and provides excellent three-dimensional spatial localization. The performance of the sequence is demonstrated both in phantoms and in rat brain in vivo. Magn Reson Med 42:454–460, 1999. © 1999 Wiley-Liss, Inc.

A conventional gradient-selected double-quantum lactate editing sequence was combined with fourth order two-dimensional longitudinal Hadamard encoding and slice-selective refocusing to acquire lactate-edited spectra in a 3 x 3 matrix of voxels. The performance of the sequence was verified in phantoms at 9.4 T and in focally ischemic rat brain at 7.0 T. Efficient suppression of water, lipid, and the singlet resonances of creatine, choline, and N-acetylaspartate was achieved, giving multi-voxel localized lactate-edited spectra with good signal-to-noise ratio.

Conventional double-quantum editing techniques recover only one metabolite at a time, and are thus inefficient for monitoring metabolic changes involving several metabolites. In this paper, a stimulated-echo-enhanced selective double-quantum coherence transfer (STE-SelDQC) sequence is described, which allows simultaneous observation of lactate and other metabolites in a single scan while leaving fat and water signals suppressed. A frequency selective double-quantum filter designed for lactate editing suppresses fat and water resonances and a stimulated-echo window of adjustable frequency and bandwidth is incorporated into the double-quantum filter for simultaneous observation of other metabolites. The performance of the sequence is demonstrated in phantoms and rat brain tissue.

Feline immunodeficiency virus (FIV) is a lentivirus that causes immune suppression and neurological disease in cats. Among animal viruses, individual viral strains have been shown to be neurovirulent, but the role of viral strain specificity among lentiviruses and its relationship to systemic immune suppression in the development of neurological disease remains uncertain. To determine the extent to which different FIV strains caused neurological disease, FIV V1CSF and Petaluma were compared in ex vivo assays and in vivo. Both viruses infected and replicated in macrophage and mixed glial cell cultures at similar levels, but V1CSF induced significantly greater neuronal death than Petaluma in a neurotoxicity assay. V1CSF-infected animals showed significant neurodevelopmental delay compared to the Petaluma-infected and uninfected animals. Magnetic resonance spectroscopy studies of frontal cortex revealed significantly reducedN-acetyl aspartate/creatine ratios in the V1CSF group compared to the other groups. Cyclosporin A treatment of Petaluma-infected animals caused neurodevelopmental delay and reducedN-acetyl aspartate/creatine ratios in the brain. Reduced CD4+ and CD8+ cell counts were observed in the V1CSF-infected group compared to the uninfected and Petaluma-infected groups. These findings suggest that neurodevelopmental delay and neuronal injury is FIV strain specific but that systemic immune suppression is also an important determinant of FIV-induced neurovirulence.

Iron compounds formed in the degradation of a hematoma can accelerate the formation of free radicals in adjacent ischemic or hypoperfused tissue. The purpose of this study was to examine the efficacy of compounds that quench free radicals in improving the outcome in rats with experimental intracerebral hemorrhage. Intracerebral hemorrhage was induced in rats by injection of bacterial collagenase and heparin into the caudate nucleus. Rats were treated with alpha-tocopherol plus ascorbic acid starting before hemorrhage, or with dimethylthiourea or alpha-phenyl-N-tert-butyl nitrone starting 2 h after hemorrhage, with treatment continued for 10 days after induction of hemorrhage. Outcome was assessed by behavioral analyses, magnetic resonance imaging, and histopathology. A trend towards behavioral improvement was found for rats treated with alpha-tocopherol/ascorbic acid, while behavior was significantly improved following intracerebral hemorrhage in rats treated with dimethylthiourea or alpha-phenyl-N-tert-butyl nitrone. These results suggest that free radicals may play a role in the development of brain injury following intracerebral hemorrhage, and that compounds that interrupt the free radical cascade may improve outcome. However, treatment did not significantly affect edema, resolution of the hematoma, or neuronal injury in tissue adjacent to the hemorrhage.

A number of metabolic alterations are initiated by cerebral ischemia including dramatic increases in lactate concentration, decreases in N-acetylaspartate, choline, and creatine concentrations, as well as changes in amino acid levels. A review of proton nuclear magnetic resonance spectroscopy studies of focal and global cerebral ischemia in rats is presented here. In particular, studies in neonatal rats have shown that a continued elevation of lactate levels without recovery after hypoxia-ischemia or a decrease in N-acetylaspartate concentration at any time are indicative of deleterious outcome. Studies of the effect of temperature on ischemic damage in a model of focal ischemia showed that outcome improved with mild hypothermia. Again, lack of recovery of lactate upon reperfusion was shown to be indicative of poor outcome. Dichloroacetic acid was used to treat rats with focal ischemic damage. Animals subjected to transient ischemia that were treated with dichloroacetic acid showed significant decreases in lactate concentration.

Polycystic kidney disease (PKD) is the fourth most common cause of end-stage renal disease and the most common potentially lethal inherited disease in humans. Early identification of carriers of dominant PKD in the absence of genetic markers is problematic in both humans and the Han:SPRD-cy/+ rat, a model of PKD that shares many features of human disease. We undertook a proton magnetic resonance imaging (MRI) study of young Han:SPRD-cy/+ and unaffected Han:SPRD(-)+/+ animals to determine whether carrier status could be identified based upon image appearance or signal characteristics. Affected animals demonstrated significant prolongation of longitudinal relaxation time (T1) and transverse relaxation time (T2) in both cystic renal cortex and noncystic renal medulla. Both of these measurements correlated significantly with whole kidney section tubular luminal space measurements, a correlate of water space, in the renal cortex, but only T1 in renal medulla showed a relationship to tubular luminal volume measured throughout the kidney. Urine and perchloric acid kidney extracts were studied using proton nuclear magnetic resonance (1H-NMR) spectroscopy to test the hypothesis that imaging differences implied specific urinary and tissue biochemical differences between affected and normal animals. 1H-NMR spectra of urine from cy/+ animals showed significantly increased excretion of alanine, citrate, succinate, and, 2-oxoglutarate but not methylamine compounds compared with +/+ animals. 1H-NMR spectra of aqueous perchloric acid kidney extracts confirmed reduced concentrations of the above ions and others involved in the citric acid cycle, as well the osmolytes betaine, taurine, and glycerophosphocholine PKD in the Han:SPRD-cy/+ rat is associated with distinct early MRI changes and alterations in urinary and tissue levels of organic anions and osmolytes.

Background and Purpose Intracerebral hemorrhage is associated with a considerable proportion of strokes and head injuries. The mechanism of brain cell injury associated with hemorrhage may be different from that due to pure ischemia. Therefore, it is essential that models of intracerebral hemorrhage be developed and well characterized. The purpose of this study was to obtain high-field MR images of rat brain at progressive times after induction of intracerebral hemorrhage and to correlate the images with behavior and histological evolution. Methods Intracerebral hemorrhage was induced in rats by injection of bacterial collagenase and heparin into the caudate nucleus. Histopathological changes and corresponding MR images were studied from 30 minutes to 3 weeks after injection. Behavioral changes were also followed for 3 weeks. Results Histological correlation showed that MR is capable of resolving the accumulation and degeneration of the hematoma, a centripetal wave of neutrophils infiltrating from the surrounding tissue beginning at 12 hours, and centripetal invasion of macrophages beginning at 48 hours. Widespread white matter edema was clearly evident on MR images for 1 week after the hemorrhage. Medium-sized striatal neurons were lost in the tissue surrounding the hematoma. Behavioral improvement was rapid during resolution of the edema but incomplete at 3 weeks. Conclusions MR images correlate very well with histological changes in this experimental model of intracerebral hemorrhage and can therefore be used to follow changes due to drug treatments in vivo. The intense neutrophilic response to this lesion may contribute to neuronal injury at the periphery of the hematoma.

Caffeine-augmented electroconvulsive therapy has been introduced into medical practice without experimental confirmation that such seizure modification does not result in neuronal injury. In this report rats pretreated with caffeine prior to a series of nine electrically induced convulsions showed neuronal injury confined to hippocampal sectors and striatum. Electrically induced convulsions without caffeine pretreatment did not result in injury. The potential deleterious effects of caffeine augmentation of human electroconvulsive therapy require rigorous clinical assessment.

Background and Purpose The severity of brain injury in animal models of forebrain ischemia increases with blood glucose level. During ischemia, energy failure is slower and maintenance of ion gradients is prolonged as the level of glycemia increases. It is not clear how the level of glycemia influences recovery of ion homeostasis on reperfusion. It has been shown that changes in the intensity of the multiple-quantum 23 Na nuclear magnetic resonance (NMR) signals reflect changes in intracellular Na + levels. We have used 23 Na NMR spectroscopy to evaluate the influence of the level of glycemia on changes in Na + concentration during and after forebrain ischemia in rats. Methods Single-quantum (SQ) and double-quantum (DQ) 23 Na NMR spectra were measured before and during 10-minute forebrain ischemia and during reperfusion in hypoglycemic, normoglycemic, and hyperglycemic rats. Results The DQ 23 Na NMR signal increased to 210% of preischemia intensity in all rats, but a delay in this increase was observed in normoglycemic and hyperglycemic animals. The rate of the DQ 23 Na NMR signal increase was fastest in hypoglycemic (apparent first-order rate constant 0.673±0.046 min −1 , P −1 , P −1 ) and normoglycemic (0.464±0.047 min −1 ) rats, whereas in hyperglycemic animals recovery was slow (0.108±0.044 min −1 , P 23 Na NMR signal intensity increased to 117% of preischemia level in hypoglycemic ( P Conclusions The slower increase in the 23 Na DQ NMR signal intensity during forebrain ischemia in rats with higher blood glucose levels suggests that Na + homeostasis is maintained longer in these animals. On reperfusion, the slower recovery of the DQ 23 Na NMR signal intensity in hyperglycemic animals likely indicates a slower recovery of Na + homeostasis, perhaps contributing to the increased neuronal injury after cerebral ischemia in hyperglycemic animals.

Dichloroacetate (DCA) activates the pyruvate dehydrogenase complex (PDHC), and improves the recovery of cerebral pH, lactate, ATP, and PCr following reperfusion in animal models of forebrain ischemia. In order to determine whether this results in neuroprotection, rats were administered NaDCA (100 mg/kg or 10mg/kg i.v.) 10 min before 12 min of normothermic forebrain ischemia (bilateral carotid artery occlusion plus systemic hypotension, 45 mmHg). Neuronal injury assessed histopathologically 7 days post-ischemia was significantly reduced in the CA1 region of the hippocampus, the dorsal lateral striatum, and the neocortex, in rats treated with 100 mg/kg NaDCA, but not in rats treated with 10 mg/kg NaDCA.

The distribution and levels of the astrocytic gap junction protein, connexin43 (Cx43) was analyzed in various regions of brain as a function of time after neuronal loss and consequent reactive gliosis induced by bilateral carotid occlusion in rats. In the striatum 2 days after induction of ischemia, immunostaining intensity for Cx43 increased in animals exhibiting mild to moderate striatal damage, whereas areas of reduced staining surrounded by elevated levels of Cx43 immunoreactivity were observed in animals with severe ischemic damage. Immunolabelling of glial cell bodies was evident in ischemic, but not normal, striatum. Similar, though less dramatic, changes were seen at 7 days post-ischemia. Compared with the fine punctate pattern of Cx43 staining seen in normal striatum, ischemic striatal areas contained large aggregates of punctate profiles. In the hippocampus, increased immunostaining was seen at 2 and 7 days post-ischemia and, unlike normal hippocampus, neurons in the CA3 pyramidal cell layer were surrounded by a network of Cx43-immunoreactive puncta at the latter survival time. Immuno-EM analysis of ischemic tissue revealed numerous immunolabelled gap junctions among astrocytic processes in the vicinity of degenerating neurons and elevated levels of intracellular Cx43 immunoreactivity in astrocytic processes and cell bodies. No differences in protein levels or phosphorylation states of Cx43 were detected in either hippocampus or striatum by Western blot analyses of ischemic and control tissue. These results suggest that astrocytes respond to an ischemic insult by reorganizing their gap junctions, that the qualitative nature of their response is dependent on the severity of neuronal damage or loss, and that a pool of Cx43 normally undetectable by immunohistochemistry may contribute to the ischemia-induced elevations of immunolabelling for this protein.

Two peaks were observed in the inorganic phosphate region in 31P NMR spectra obtained during and shortly after incomplete forebrain ischemia induced in rats under normoglycemic conditions. Pre-ischemia, a single Pi peak was observed at a chemical shift of 2.5 ppm (pH 7.2). This peak shifted upfield to 1.6 ppm (pH 6.5) and, following reperfusion, returned to its pre-ischemia value. During ischemia and for a short time following reperfusion, a second, smaller peak was observed which we assigned to a second pool of inorganic phosphate. The data support the proposal by Kraig and coworkers of pH compartmentation between neurons and glia during and following transient forebrain ischemia.

Summary: The effect of domoic acid-induced seizure activity on energy metabolism and on brain pH in mice was studied by continuous EEG recording and in vivo 31P nuclear magnetic resonance (NMR) spectroscopy. Mice were divided into ventilated (n = 6) and nonventilated (n = 7) groups. Baseline EEG was 0.1-mV amplitude with frequence of >30-Hz and of 4-5 Hz. After intraperitoneal (i.p.) administration of domoic acid (6 mglkg), electrographic spikes appeared at increasing frequency, progressing to high-amplitude (0.1-0.8 mV) continuous seizure activity (status epilepticus). In ventilated mice, the ["PJNMR spectra showed that high-energy phosphate levels and tissue pH did not change after domoic acid administration or during the intervals of spiking or status epilepticus. Nonventilated mice showed periods of EEG suppression accompanied by decreases in the levels of high-energy phosphate metabolites and in pH, corresponding to episodic respiratory suppression during the spiking interval. In all animals, status epilepticus was followed by a marked decrease in EEG amplitude that progressed rapidly to isoelectric silence. [3 IPINMR spectra obtained after this were indicative of total energy failure and tissue acidosis. In a separate group of ventilated mice (n = 4), domoic acid-induced status epilepticus was accompanied initially by an increase in mean arterial blood pressure (MAP) that slowly returned to baseline level. Isoelectric silence was accompanied by a decrease in MAP to 75 ? 8 mm Hg. These experiments suggest that domoic acid-induced seizures are not accompanied by an increase in substrate demand that exceeds supply. Key Words: Domoic acid-"P Spectroscopy-Status epilepticus-Neurologic models.

Summary: Epilepsy-prone and epilepsy-resistant substrains were selectively bred from a strain of BALB/c mice; audiogenic-sensitive epilepsy-prone animals showed enhanced sensitivity to chemical convulsants. Treatment with pyridoxine (100 mg/L in drinking water) initiated at mating and continued throughout pregnancy and the life of the offspring abolished the enhanced sensitivity to chemical convulsants and reduced the severity of audiogenic seizures. Withdrawal of pyridoxine restored the enhanced seizure sensitivity. [1H] Nuclear magnetic resonance (NMR) spectroscopy of perchloric acid extracts of tissue was used to determine the concentrations of several compounds [N-acetylaspartate (NAA), GABA, glutamate, aspartate, alanine, taurine, creatine, cholines, inositol] in the hippocampus, neocortex, brainstem, and cerebellum of untreated and pyridoxine-treated 6-week-old female animals. The ratios of the concentrations of excitatory to inhibitory putative neurotransmitteramino acids tended to be higher in epilepsy-prone animals, with the most pronounced difference being a significantly elevated glutamate/GABA ratio in every brain region examined. Pyridoxine treatment abolished this imbalance in the hippocampus, brainstem, and cerebellum, but not in the neocortex. Treatment of epilepsy-resistant animals with pyridoxine using the same protocol decreased the glutamate/GABA concentration ratio in the hippocampus, brainstem, and neocortex and resulted in impaired development of the animals. The amino acid imbalance and the accompanying seizure susceptibility in these genetically epilepsy prone mice may originate from an inborn error in pyridoxine metabolism or in a pyridoxine-dependent enzyme system. ReSUMe A partir d'une souche de souris BALB/c, des pedigrees de souris predisposees a l'epilepsie et resistantes a l'epilepsie ont ete selectivement obtenus avec des animaux predisposes a l'epilepsie, sensibles aux stimulations audiogeniques, qui presentaient une sensibilite augmentee aux convulsivants chimiques. Le traitement par la pyridoxine (100 mg/L dans l'eau de boisson) commence au moment de la copulation, poursuivi pendant la gestation et pendant toute la vie du rat a aboli l'augmentation de sensibilite aux convulsivants chimiques, et a reduit la severite des crises audiogtnes. L'arret de la pyridoxine a retabli l'augmentation de sensibilite aux crises. La spectroscopie RMN [1H] d'extraits de tissus traites par acide perchlorique a ete utilisee pour determiner les concentrations de differents composes (N-acetylaspartate, GABA, glutamate, aspartate, alanine, taurine, creatine, cholines, inositol) au niveau de l'hippocampe, du neocortex, du tronc cerebral et du cervelet, chez des souris femelles non traitees et traitees par pyridoxine, âgees de 6 semaines. Les rapports de concentration des acides amines neurotransmetteurs excitateurshnhibiteurs tendaient B ttre plus eleves chez les animaux predisposes B l'epilepsie, la difference la plus importante representant un rapport significativement augmente glutamate/GABA au niveau de chaque region cerebrale examinee. Le traitement par pyridoxine a aboli ce desequilibre au niveau de l'hippocampe, du tronc cerebral et du cervelet mais pas au niveau du neocortex. Le traitement des animaux resistant B l'epilepsie par la pyridoxine, suivant le mtme protocole a diminue les rapports de concentrations de glutamate/GABA au niveau de l'hippocampe, du tronc cerebral et du neocortex et a entraino un trouble du developpement de ces animaux. Le desequilibre des amino-acides et la susceptibilite aux crises, qui semblent associCs chez ces rats genetiquement predisposes B l'epilepsie, peut provenir d'une erreur innee du metabolisme de la pyridoxine ou d'un systeme enzymatique pyridoxino-dependant. RESUMEN Se han seleccionado sub-cepas resistentes a la epilepsia y tambikn cepas de ratones BALB/c que tenian epilepsia sensible a estimulos radiogknicos y mostraron un aumento de su sensibilidad a convulsivantes quimicos. Un tratamiento con piridoxina (100 mg/L administrada en agua) iniciado en el momento de la copulacion y continuada a lo largo del embarazo y de la vida de los animales-hijo elimino el incremento de la sensibilidad a convulsivantes quimicos y redujo la severidad de los ataques audiogknicos. La interrupcion de la piridoxina restauro el incremento de la sensibilidad de los ataques. Se ha utilizado la espectroscopia con Resonancia Magnetica para extractos de acido perclorico de los tejidos con intention de determinar las concentraciones de varios compuestos (N-acetilaspartato, GABA, glutamato, aspartato, alanina, taurina, creatina, colina, inositol) en el hipocampo, neocortex, tronco cerebral y cerebelo de los animales hembras de 6 semanas de edad tratados y no tratados con piridoxina. Las relaciones entre la concentracion de aminoacidos neurotransmisores putativamente considerados como excitatorios o inhibitorios, mostraron una tendencia a estar mas elevadas en animales con tendencia a la epilepsia con una diferencia mas pronunciada demostrada por una elevation significativa de la relacion glutamato-GABA en cada region cerebral examinada. El tratamiento con piridoxina elimino este desequilibrio en el hipocampo, el tronco cerebral y el cerebelo per0 no en el neocortex. El tratamiento de los animales resistentes a la epilepsia con piridoxina utilizando el mismo protocolo redujo la concentracion de la relacion glutamatolGABA en el hipocampo, tronco cerebral y neocortex, y condujo a un desarrollo de los animales sin ningdn tip0 de trastorno. El desequilibrio de aminoacidos y la asociada susceptibilidad para los ataques en estos ratones con una tendencia genktica a la epilepsia puede originarse a traves de un error congenito del metabolismo de la piridoxina o en sistemas enzimaticos piridoxina-dependientes. ZUSAMMENFASSUNG Epilepsieanfallige und Epilepsieresistente Untergruppen wurden von einem Stamm BALB/c-Mausen gezuchtet, wobei die Tiere mit einer audiogen-sensitiven Epilepsieneigung eine erhohte Empfindlichkeit gegenuber chemischen Konvulsiva zeigten. Eine Behandlung mit Pyridoxin (100 mg/l Trinkwasser), die bei der Paarung begonnen wurde und wahrend der Tragezeit und dem ganzen Leben der Nachkommen aufrecht erhalten wurde, brachte die erhohte Empfindlichkeit gegenuber chemischen Konvulsiva zum Verschwinden und reduzierte den Schweregrad der audiogenen Anfalle. Ein Pyridoxin-Entzug stellte die erhohte Anfallsempfindlichkeit wieder her. Mit Hilfe einer [1H] NMR-Spektroskopie von Perchlorsaureextrakten wurden die Konzentrationen von verschiedenen Bestandteilen (N-Acethylaspartat, GABA, Glutamat, Aspartat, Alanin, Taurin, Kreatin, Cholinen, Inositol) im Hippokampus, Neokortex, Hirnstamm und Cerebellum von unbehandelten und Pyridoxinbehandelten 6 Wochen alten weiblichen Tieren bestimmt. Das Verhaltnis in den Konzentrationen von exzitatorischen zu inhibitorischen moglichen Neurotransmitter-Aminosauren zeigte bei den Epilepsie-anfalligen Tieren eine Tendenz zur Erhohung, mit der deutlichsten Differenz in Form einer signifikanten Erhohung des Glutamat/GABA Verhaltnisses in jeder untersuchten Hirnregion. Die Pyridoxin-Behandlung brachte dieses Ungleichgewicht im Hippokampus, Hirnstamm und Kleinhirn zum Verschwinden, jedoch nicht im Neokortex. Die Behandlung von Epilepsie -resistenten Tieren mit Pyridoxin unter dem gleichen Protokoll fuhrte zu einer Verminderung des Glutamat/GABA- Konzentrationsverhaltnisses im Hippokampus, Hirnstamm und Neokortex und resultierte in einer behinderten Entwicklung der Tiere. Die Aminosaurenimbalance und die begleitende Anfallsempfindlichkeit bei diesen genetisch zu einer Epilepsie neigenden Mausen rahrt moglicherweise von einer angeborenen Storung im Pyridoxinmetabolismus oder in einem Pyridoxin- abhangigen Enzymsystem her.

The electric dipole moments of o-ClC6H4PCl2 1, C6H5PF4 2, o-ClC6H4PF4 3, C6H5P(O)F2 4, C6H5P(O)HF 5. C6H5P(O)H(OH) 6, and o-ClC6H4P(O)Cl2 7, were determined in dilute benzene solution at 25°C. The phosphoryl bond moment PO in compounds 4, 5, and 7 was estimated using simple bond-additivity calculations. The results obtained were 4.55D, 3.64D, and 5.52D for compounds 4, 5, and 7, respectively. Dipole moments for compounds 2 and 3 were also calculated theoretically using INDO MO techniques. The calculated values differed from the experimental values by about 12%.

Transient forebrain ischemia was induced in rats whose brain temperature was 31, 33, 35, 38, or 40°C. The development of regional injury was followed using magnetic resonance (MR) imaging, with the ultimate extent of neuronal injury quantified histopathologically. Animals in the hypothermic groups showed minimal changes in MR images over 4 days; normothermic animals snowed intensity enhancement attributed to progressive edema developing in the striatum and, later, in the hippocampus. Ischemia at 40°C resulted in widespread edema formation by I day post-ischemia; animals in this group did not survive beyond 30 hours. Histopathological analysis at 4 days (1 day for the hyperthermic group) post-ischemia showed that neuronal damage in the normothermic group was confined to the hippocampus and striatum. Minimal damage was found in the hypothermic groups; damage in the hyperthermic group was severe throughout the forebrain. There were no differences in the pre-ischemia 31P MR spectra for the different groups. During ischemia, the increase in intensity of the Pi peak and the fall in tissue pH increased with temperature in the order hypothermic < normothermic < hyperthermic group of animals. Post-ischemia energy recovery was similar in all groups, while pH recovered more rapidly in hypothermic animals.

The 1H NMR spectrum of the putative neurotransmitter dipeptide N-acetylaspartylglutamate (NAAG) is described, along with its identification in acid extracts of tissues of the central and peripheral nervous systems of the rat. The N-acetyl methyl resonance of NAAG (2.058 ppm) is close to that of N-acetylaspartate (NAA, 2.022 ppm), a prominent signal in 1H NMR spectra of the brain. The tissue concentration of NAAG is such that resonances of NAAG do not contribute greatly to 1H NMR spectra of the brain, except in studies of the brain stem or thalamus. In the spinal cord and peripheral nerves the level of NAAG is similar to that of NAA, and NAAG is a major metabolite contributing to the 1H NMR spectrum. The implications of these observations for 1H NMR spectra in vivo are discussed.

Internal rotational potentials for rotation about the Csp2—O bond in C6H5OCF3 and its 4-fluoro derivative are computed at the STO-3G and 3-12G levels of molecular orbital theory. As for anisole, the perpendicular conformer is calculated as least stable for C6H5OCF3 but the height of the internal barrier is considerably lower than in anisole. The 4-fluoro substituent reduces the twofold component significantly, indicating reduced p …π conjugation, but does not much change the values of the higher terms in the theoretical potentials. The internal potentials are rather flat with minima between about 30° and 45°, these angles measuring the twist away from planarity. The 1H, 13C, and 19F nuclear magnetic resonance spectra in polar and nonpolar solution yield long-range coupling constants, nJ(1H,19F) and nJ(13C,19F). These parameters are qualitatively consistent with relatively low barriers to rotation about the Csp2—O bonds in these molecules and with only a small dependence on solvent polarity. Key words: C6H5OCF3 and 4-F-C6H4OCF3: 1H NMR, 19F NMR, conformations, MO computations.

Inflammation, demyelination, and blood-spinal cord barrier (BSB) breakdown occur in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. The purpose of this study was to evaluate the utility of MRI for detecting lesions and BSB disruption in vivo during EAE in the mouse lumbar spinal cord, to determine how MR features of BSB disruption change during the course of disease, and to relate such changes to clinical signs and histological features of disease. Following induction of EAE in C57BL/6 mice, contrast-enhanced (CE) T1-weighted MR images were acquired to detect BSB disruption in the lumbar spinal cord at the early stage of disease, at peak disease, and at remission, and T2weighted images were obtained to monitor spinal cord morphology. Following imaging the spinal cords were assessed in situ for general features of inflammation, BSB leakage, activated macrophages/microglia, and demyelination. No focal lesions were evident on T2-weighted MR images. BSB disruption was greatest at the onset of signs of disease, and decreased progressively thereafter. Inflammation and demyelination were pronounced at the initial stage of disease and at peak disease, and were decreased at remission. Nonuniform contrast enhancement indicated that breakdown of the BSB occurred predominantly within the white matter (WM) of the spinal cord. Magn Reson Med 58:298 –305, 2007. © 2007 Wiley-Liss, Inc.

We have developed a novel multiscale localized image texture analysis technique, based upon the polar Stockwell Transform (PST). In this paper we characterized image texture in vivo using the PST in histologically verified lesion areas in T2-weighted MRI of an animal model of multiple sclerosis. Both high and low frequency signals, representing inflammation and demyelination, were significantly increased in pathological regions compared to normal control tissue. This suggests that this new local spatial-frequency measure of image texture may provide a sensitive and precise indication of disease activity.

Endothelin-1 (ET-1), a potent vasoconstrictor, reduces local blood flow to levels that produce ischemic injury when injected directly into brain tissue. The purpose of this study was to compare 4 different methods of inducing focal ischemia with ET-1: (1) topical application to the forelimb motor region of the cortex, (2) intracerebral injection into the forelimb motor region of the cortex, (3) a combination of intracortical and intrastriatal injections and 4. injection of ET-1 adjacent to the middle cerebral artery (MCA). We examined the effect of delivery method and dose of ET-1 on lesion size, inter-animal variability and behavioral outcome on 3 separate tests of motor function and limb preference. We calculated success rate as the percentage of animals that survived surgery and developed a significant impairment (>20% decrease in performance post-surgery) in the staircase-reaching test. All 4 methods produced similar deficits in the staircase, balance beam, and cylinder tests, but the application of ET-1 adjacent to the MCA, though widely used, provided the lowest success rate. The combined cortical and striatal ET-1 produced a high success rate and consequently we examined cerebral blood flow (CBF), the apparent diffusion coefficient (ADC) and T2-weighted magnetic resonance imaging (MRI) changes for this model. We found that infarct volume measured using T2-weighted MRI correlated with histological measurements and that ADC and CBF together predicted which areas will suffer permanent injury. The combined cortical and striatal injection model offers a number of advantages for studies of recovery of function.

Minocycline reduces infarct volume measured up to 1 week after focal cerebral ischemia, but it has not been shown that this results in lasting improvement in functional outcome. This study examined behavioral outcome in rats out to 3 weeks after focal ischemia induced by injection of the vasoconstrictor endothelin (ET)-1 (400 pmol in 1 microL of saline) into the striatum. Magnetic resonance imaging confirmed reduced blood flow after administration of ET-1, and was used to determine lesion volumes at 1 and 21 days postischemia. In control rats, intraperitoneal injection of minocycline resulted in plasma levels of 6.6 +/- 2.7 microg mL(-1) between 1 and 8 hours after administration. Based on these results, intraperitoneal minocycline treatment was started either 1 hour before or 3 hours after ET-1 administration, and was repeated daily for 5 days. Outcome, assessed using a composite behavioral deficit score (days 2, 4, 7, 14, and 21) and a test of asymmetric forelimb use (days 7 and 21), was significantly better in both groups of rats treated with minocycline, and the improvement was maintained for the 3-week study period. No differences were found in infarct volumes between groups.

Neonatal periventricular hemorrhage (PVH) is a devastating complication of prematurity in the human infant. Based upon observations made primarily in adult rodents and the fact that the immature brain uses proteolytic systems for cell migration and growth, we hypothesized that thrombin and plasmin enzyme activities contribute to the brain damage after PVH. The viability of mixed brain cells derived from newborn rat periventricular region was suppressed by whole blood and thrombin, but not plasmin. Following injection of autologous blood into the periventricular region of newborn rat brain, proteolytic activity was detected in a halo around the hematoma using membrane overlays impregnated with thrombin and plasmin fluorogenic substrates. Two-day old rats received periventricular injection of blood, thrombin, and plasminogen. After 2 days, thrombin and blood were associated with significantly greater damage than saline or plasminogen. Two-day old mice received intracerebral injections of blood in combination with saline or the proteolytic inhibitors hirudin, alpha2macroglobulin, or plasminogen activator inhibitor-1. After 2 days, hirudin significantly reduced brain cell death and inflammation. Two-day-old mice then received low and high doses of hirudin mixed with blood after which behavioral testing was conducted repeatedly. At 10 weeks there was no statistically significant evidence for behavioral or structural brain protection. These results indicate that thrombin likely plays a role in neonatal periventricular brain damage following PVH. However, additional factors are likely important in the recovery from this result.

Lentiruses cause neurological disease depending on the virus strain and its neurotropism, yet it remains uncertain to what the impact of infectious virus quantity in the brain early in infection is on the subsequent development of neurological disease or neurovirulence. We investigated the relationship between infectious virus input titer and the resulting neurovirulence, using ex vivo and in vivo assays of feline immunodeficiency virus (FIV)-induced neurovirulence. FIV infection of cell cultures and neonatal cats was performed using 102.5 (low-titer) or 104.5 (high-titer) 50% tissue culture infectious doses (TCID50)/ml of the neurovirulent FIV strain, V1CSF. Ex vivo neurotoxicity assays revealed that conditioned medium (CM) from feline macrophages infected with high-titer (P < .001) or low-titer (P < .01) V1CSF induced greater neuronal death than CM from mock-infected cells. In vivo, animals infected intracranially with high-titer V1CSF showed neurodevelopmental delays compared to mock-infected animals (P < .001) and animals infected with low-titer V1CSF (P < .02), concurrent with reduced weight gains and greater depletion of CD4+ cells over a 12-week period. Neuropathological changes, including astrogliosis, macrophage activation, and neuronal damage, were evident in V1CSF-infected animals and were viral titer dependent. In vivo magnetic resonance (MR) spectroscopy and proton nuclear magnetic resonance (1H-NMR) spectroscopy of tissue extracts revealed evidence of neuronal injury, including reduced N-acetyl aspartate/creatine (P < .05) and increased trimethylamine/creatine (P < .05) ratios, in the frontal cortex of high-titer V1CSF-infected animals compared to the other groups. T2-weighted MR imaging detected increased signal intensities in the frontal cortex and white matter of V1CSF-infected animals relative to controls, which was more evident as viral titer increased (P < .01). The present findings indicate that lentivirus infectious titers in the brain during the early stages of infection determine the severity of neurovirulence, reflected by neurobehavioral deficits, together with neuroradiological and neuropathological findings of activation of innate immunity and neuronal injury.

The vasoconstrictive peptide endothelin-1 (ET-1) has been used previously to transiently occlude the middle cerebral artery (MCA) in rats. However, the duration of the resulting reduction in cerebral blood flow (CBF) and the reperfusion characteristics are poorly understood. In this study perfusion and T2-weighted MRI were used together with histology to characterize the cerebral perfusion dynamics and lesion development following ET-1 injection. Twenty-two rats received an intracerebral injection of ET-1 adjacent to the MCA. CBF was reduced to 30–50% of control levels, and a significant reduction persisted for 16 h in the cortex and 7 h in the striatum. The lesion size measured by T2-weighted imaging at 48 h correlated with the final infarct size measured by histology at 7 d. The sustained reduction in CBF and the gradual development of the ischemic lesion resemble human stroke evolution, suggesting that this model may be useful for evaluating therapeutic agents, particularly when treatment is delayed. Magn Reson Med 46:827–830, 2001. © 2001 Wiley-Liss, Inc.