Vacuolation Of White Matter Research Articles

Treatment with Cerebrolysin Prolongs Lifespan in a Mouse Model of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare familial neurological disorder caused by mutations in the NOTCH3 gene and characterized by migraine attacks, depressive episodes, lacunar strokes, dementia, and premature death. Since there is no therapy for CADASIL the authors investigate whether themulti-modal neuropeptide drug Cerebrolysin may improve outcome in a murine CADASIL model. Twelve-month-old NOTCH3R169C mutant mice (n=176) are treated for nine weeks with Cerebrolysin or Vehicle and histopathological and functional outcomes are evaluated within the subsequent ten months. Cerebrolysin treatment improves spatial memory and overall health, reduces epigenetic aging, and prolongs lifespan, however, CADASIL-specific white matter vacuolization is not affected. On the molecular level Cerebrolysin treatment increases expression of Calcitonin Gene-Related Peptide (CGRP) and Silent Information Regulator Two (Sir2)-like protein 6 (SIRT6), decreasesexpression of Insulin-like Growth Factor 1 (IGF-1), and normalizes the expression of neurovascular laminin. In summary, Cerebrolysin fosterslongevity and healthy aging without specifically affecting CADASIL pathology. Hence, Cerebrolysin may serve a therapeutic option for CADASIL and other disorders characterized by accelerated aging.

Naturally occurring histological findings and Alzheimer's-like pathology in the brain of aging African green monkeys (Chlorocebus sabaeus).

Nonhuman primates (NHPs) are important to study the pathophysiology of neurodegenerative disease and evaluate therapies targeting the central nervous system (CNS). Understanding the age-associated incidence of natural CNS pathology in a given NHP species is critical to assess the safety of potential treatments for neurodegenerative disorders like Alzheimer's disease (AD). We describe background and age-related neuropathology in the St. Kitts African green monkey (AGM), a recognized translational model for neurodegenerative research, additionally defining the age progression of AD-associated neuropathology in this species. Seventy-one AGM brains were examined, representing age groups of 3-6years (n=20), 7-9years (n=20), 10-15years (n=20), and >15years (n=11). A subset of brains (n=31) was assessed immunohistochemically for AD-related pathology, including expressions of Aβ, tau, and GFAP. Age-related microscopic findings included hemosiderosis, spheroid formation, neuronal lipofuscinosis and neuromelanosis, white matter and neuropil vacuolation, astrocytosis, and focal microgliosis. Non-age-related findings included perivascular ceroid-laden macrophages, meningeal melanosis, and vascular mineralization. Immunohistochemistry revealed 4G8-immunopositive Aβ plaques and vascular deposits in the prefrontal, frontal, cingulate, and temporal cortices of nine animals over 15years of age, with associated increase in GFAP expression. In 12 animals, 11 over the age of 10years, phosphorylated tau CP13-immunoreactive neurons, neuropil, and oligodendrocyte-like cells were seen in the prefrontal, frontal, cingulate, orbital, temporal, and entorhinal cortices as well as the hippocampus; no neurofibrillary tangles were observed. AD-related pathology showed an age-related development in cognitive-associated areas in the AGM, highlighting the value of the AGM as a natural model for these neurodegenerative diseases.

The Effect of Interleukin-1 Antagonists on Brain Volume and Cognitive Function in Two Patients With Megalencephalic Leukoencephalopathy With Subcortical Cysts

BackgroundMegalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare leukodystrophy characterized by early-onset macrocephaly and progressive white matter vacuolation. The MLC1 protein plays a role in astrocyte activation during neuroinflammation and regulates volume decrease following astrocyte osmotic swelling. Loss of MLC1 function activates interleukin (IL)-1β-induced inflammatory signals. Theoretically, IL-1 antagonists (such as anakinra and canakinumab) can slow the progression of MLC. Herein, we present two boys from different families who had MLC due to biallelic MLC1 gene mutations and were treated with the anti-IL-1 drug anakinra. MethodsTwo boys from different families presented with megalencephaly and psychomotor retardation. Brain magnetic resonance imaging findings in both patients were compatible with the diagnosis of MLC. The diagnosis of MLC was confirmed via Sanger analysis of the MLC1 gene. Anakinra was administered to both patients. Volumetric brain studies and psychometric evaluations were performed before and after anakinra treatment. ResultsAfter anakinra therapy, brain volume in both patients decreased significantly and cognitive functions and social interactions improved. No adverse effects were observed during anakinra therapy. ConclusionsAnakinra or other IL-1 antagonists can be used to suppress disease activity in patients with MLC; however, the present findings need to be confirmed via additional research.

Comparative Biochemical Profiling of Aluminum Chloride and Sodium Azide Induced Neuroinflammation and Cardiometabolic Disturbance

Comorbidities in human beings signify the numerous risk factors that increase the incidences of neuro- and cardio-metabolic disorders. Experimental models depicting comorbidities are important to explore the molecular pathophysiology that can help suggest appropriate treatment strategies. Tissue-accumulating potential and pathological effects of aluminium chloride (AlCl3)and sodium azide (NaN3) are well recognized. Hence, in the current work, we have for the first time aimed to investigate the unexplored potential of graded dose effects of AlCl3 and NaN3 in inducing early inflammation and cardiometabolic toxicity via comparative biochemical analysis of AlCl3 and/or NaN3. Rats were allocated into seven groups (n = 6). Group 1 was normal control. Remaining groups were given graded doses of AlCl3 and/or NaN3, as LD-AlCl3 (AlCl3 40 mg), MD-AlCl3 (AlCl3 45 mg), and HD-AlCl3 (AlCl3 50 mg) representing low dose, medium dose, and high dose of AlCl3, respectively, and the remaining as LD-NaN3 (NaN3 13 mg), MD-NaN3 (NaN3 15 mg), and HD-NaN3 (NaN3 17 mg) representing low dose, medium dose, and high dose of NaN3, respectively. Serum levels of glucose, insulin, lipid profile, inflammatory mediators like IL-6 and oxidative stress marker, and malondialdehyde (MDA) were analyzed. Likewise, subacute toxicity parameters were analyzed. Immunohistochemistry (IHC) and histopathology (H&E/Masson's trichrome staining) of brain, heart, and pancreatic tissues were done. ECG pattern of all groups was observed. HD-AlCl3 was associated with elevated levels of inflammatory biomarkers, MDA, and glycemic and lipid profiles, whereas it decreased the insulin levels. HD-NaN3 also showed the similar effects of aggravated inflammatory biomarkers, impaired glycemic and lipid profiles, but depicted the maximum mortality rate as compared to HD-AlCl3. IHC showed prominent amyloid plaques and neurofibrillary tangle formation with MD-AlCl3 and HD-AlCl3 as compared to NaN3-treated groups. Likewise, in brain tissues, vacuolation of white matter, vascular congestion, and hemorrhage were seen in HD-AlCl3 treated group, while HD-NaN3 induced death in animals. AlCl3 exposure resulted in an inverted QRS complex, while exposure to NaN3 showed ST depression but with increased mortality. AlCl3 has better controlled results as compared to NaN3 for induction of comorbid experimental animal model depicting early neuroinflammation and cardiometabolic disruption. These determined efforts facilitate the researchers for the development of clinically effective treatment strategies using such experimental models.

Neuropathology of feral conures with bromethalin toxicosis.

Bromethalin is a widely used neurotoxic rodenticide sometimes affecting nontarget wildlife. However, the effects of bromethalin on avian species are largely unknown. Here, we report the neuropathology of 14 feral conures (Psittacara sp.) with bromethalin toxicosis. Clinically, all birds presented with different degrees of paraparesis that sometimes progressed to dysphagia, ataxia, and tetraparesis. Histologically, there was astrogliosis, pallor, and vacuolation of white matter in the brain. This was usually more prominent in the medial longitudinal fasciculus, pons, optic tectum, cerebellar peduncle, and ventral funiculus. In most affected areas, there was loss of oligodendrocytes, and axons had extensive myelin loss or marked intramyelinic edema with splitting of myelin sheaths at the intraperiod line. Conures with bromethalin toxicosis had neuropathological changes similar to those of mammals exposed to bromethalin but with a characteristic distribution, probably related to higher susceptibility to cytotoxic edema in certain regions of the avian brain.

Megalencephalic leukoencephalopathy with subcortical cysts is a developmental disorder of the gliovascular unit.

Absence of the astrocyte-specific membrane protein MLC1 is responsible for megalencephalic leukoencephalopathy with subcortical cysts (MLC), a rare type of leukodystrophy characterized by early-onset macrocephaly and progressive white matter vacuolation that lead to ataxia, spasticity, and cognitive decline. During postnatal development (from P5 to P15 in the mouse), MLC1 forms a membrane complex with GlialCAM (another astrocytic transmembrane protein) at the junctions between perivascular astrocytic processes. Perivascular astrocytic processes along with blood vessels form the gliovascular unit. It was not previously known how MLC1 influences the physiology of the gliovascular unit. Here, using the Mlc1 knock-out mouse model of MLC, we demonstrated that MLC1 controls the postnatal development and organization of perivascular astrocytic processes, vascular smooth muscle cell contractility, neurovascular coupling, and intraparenchymal interstitial fluid clearance. Our data suggest that MLC is a developmental disorder of the gliovascular unit, and perivascular astrocytic processes and vascular smooth muscle cell maturation defects are primary events in the pathogenesis of MLC and therapeutic targets for this disease.

Mutations in the adenosine deaminase ADAR1 that prevent endogenous Z-RNA binding induce Aicardi-Goutières-syndrome-like encephalopathy

Mutations in the adenosine-to-inosine RNA-editing enzyme ADAR1 p150, including point mutations in the Z-RNA recognition domain Zα, are associated with Aicardi-Goutières syndrome (AGS). Here, we examined the invivo relevance of ADAR1 binding of Z-RNA. Mutation of W197 in Zα, which abolished Z-RNA binding, reduced RNA editing. Adar1W197A/W197A mice displayed severe growth retardation after birth, broad expression of interferon-stimulated genes (ISGs), and abnormal development of multiple organs. Notably, malformation of the brain was accompanied by white matter vacuolation and gliosis, reminiscent of AGS-associated encephalopathy. Concurrent deletion of the double-stranded RNA sensor MDA5 ameliorated these abnormalities. ADAR1 (W197A) expression increased in a feedback manner downstream of type I interferons, resulting in increased RNA editing at a subset of, but not all, ADAR1 target sites. This increased expression did not ameliorate inflammation in Adar1W197A/W197A mice. Thus, editing of select endogenous RNAs by ADAR1 is essential for preventing inappropriate MDA5-mediated inflammation, with relevance to the pathogenesis of AGS.

A Hypomorphic Dars1 D367Y Model Recapitulates Key Aspects of the Leukodystrophy HBSL.

Hypomyelination with brain stem and spinal cord involvement and leg spasticity (HBSL) is a leukodystrophy caused by missense mutations of the aspartyl-tRNA synthetase-encoding gene DARS1. The clinical picture includes the regression of acquired motor milestones, spasticity, ataxia, seizures, nystagmus, and intellectual disabilities. Morphologically, HBSL is characterized by a distinct pattern of hypomyelination in the central nervous system including the anterior brainstem, the cerebellar peduncles and the supratentorial white matter as well as the dorsal columns and the lateral corticospinal tracts of the spinal cord. Adequate HBSL animal models are lacking. Dars1 knockout mice are embryonic lethal precluding examination of the etiology. To address this, we introduced the HBSL-causing Dars1D367Y point mutation into the mouse genome. Surprisingly, mice carrying this mutation homozygously were phenotypically normal. As hypomorphic mutations are more severe in trans to a deletion, we crossed Dars1D367Y/D367Y mice with Dars1-null carriers. The resulting Dars1D367Y/− offspring displayed a strong developmental delay compared to control Dars1D367Y/+ littermates, starting during embryogenesis. Only a small fraction of Dars1D367Y/− mice were born, and half of these mice died with hydrocephalus during the first 3 weeks of life. Of the few Dars1D367Y/− mice that were born at term, 25% displayed microphthalmia. Throughout postnatal life, Dars1D367Y/− mice remained smaller and lighter than their Dars1D367Y/+ littermates. Despite this early developmental deficit, once they made it through early adolescence Dars1D367Y/− mice were phenotypically inconspicuous for most of their adult life, until they developed late onset motor deficits as well as vacuolization and demyelination of the spinal cord white matter. Expression levels of the major myelin proteins were reduced in Dars1D367Y/− mice compared to controls. Taken together, Dars1D367Y/− mice model aspects of the clinical picture of the corresponding missense mutation in HBSL. This model will enable studies of late onset deficits, which is precluded in Dars1 knockout mice, and can be leveraged to test potential HBSL therapeutics including DARS1 gene replacement therapy.

NIMG-60. ATYPICAL POSTERIOR REVERSIBLE LEUKOENCEPHALOPATHY SYNDROME MIMICKING TUMOR IN 1ST TRIMESTER PREGNANCY-’DON’T BELIEVE EVERYTHING YOU SEE’

Abstract Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiographic diagnosis characterized by headache, confusion, visual disturbances, seizures and most commonly bilateral vasogenic edema. PRES during first trimester gestation is exceptional and in our report mimicking CNS tumor. An 18-year-old G1P0 Hispanic woman was admitted with headache, left-sided hemiparesis and left-sided visual loss for 4 days. Exam was consistent for drowsiness, dysarthria, left homonymous hemianopia, left facial droop and left hemiplegia with left hemi-sensory loss. By pelvic ultrasound she had a single 9-week intrauterine pregnancy with no detectable fetal heart tone. MRI brain: large area of increased T2 signal in the right parietal occipital and upper temporal and posterior right frontal lobe white matter with mass effect of 6mm midline shift and no evidence of hemorrhage. There was high suspicion for a glial neoplasm. MRA of head and neck and EEG were unremarkable. IR cerebral angiogram had no evidence of vascular abnormalities. Eventual MR spectroscopy, choline/NAA ratio was (< 2/1), elevated lactate/fat peak suggestive of inflammatory versus infectious process. She had D&C for missed abortion and pathology was negative for malignancy. Further brain biopsy on day 5 demonstrated reactive astrogliosis with microglial activation, scattered macrophages with white matter vacuolation. Biopsy specimen was negative for infections. TPO Ab, NMO/AQP4, Ttg IgA and rheumatologic panel were negative. The pathology was most compatible with PRES. Repeat MRI had decreasing mass effect and increased patchy subcortical restricted diffusion in the right occipital and temporo-parietal lobes. She had inpatient rehabilitation leading to complete recovery.

Detection of atypical porcine pestivirus genome in newborn piglets affected by congenital tremor and high preweaning mortality1.

Recently, piglets from a high-health status farm began exhibiting congenital tremors, high preweaning mortality and incidence of splayed legs. Postmortem histological examination identified a small number of scattered white matter vacuoles in the cerebellum and underlying brainstem of affected piglets. Presence of potential viral sources associated with this neurologic condition was initially infirmed using quantitative PCR for atypical porcine pestivirus (APPV), porcine teschovirus, and porcine sapelovirus. Using metagenomic analysis, APPV was identified as the main microbial species in serum obtained from piglets affected by congenital tremor. These piglets had higher preweaning mortality rates (46.4% vs. 15.3%) and incidence of splayed legs (33.0% vs. 0.8 %) compared to unaffected piglets. Piglets affected by congenital tremor had higher viral titer (P < 0.15) and larger birth weights (P < 0.05) compared to normal litter mates. Whole-genome sequencing and genome assembly of the novel APPV strain (MK728876) was carried out using Oxford Nanopore and related bioinformatics pipelines. Phylogenic analysis demonstrated that this strain along with other completely sequenced APPV strains were grouped into 2 clades, both including strains-inducing congenital tremor. Strains appear to cluster based on region but there were still significant differences within regions. Future research needs to address potential underdiagnosis due to genetic diversity but also to understand mode of transmission, variation in virulence, and the role of host genetics in APPV susceptibility.

Evoked potentials as a translatable biomarker to track functional remyelination

Enhancing remyelination is a key therapeutic strategy for demyelinating diseases such as multiple sclerosis. To achieve this goal, a central challenge is being able to quantitatively and longitudinally track functional remyelination, especially with translatable biomarkers that can be performed in both preclinical models and in the clinic. We developed the methodology to stably measure multi-modal sensory evoked potentials from the skull surface over the course of months in individual mice and applied it to a genetic mouse model of oligodendrocyte ablation and demyelination. We found that auditory and somatosensory evoked potential latencies reliably increased over time during the early phase of the model and recovered spontaneously and almost completely during a later phase. Histological examination supported the interpretation that the evoked potential latency changes dynamically reflect changes in CNS myelination. Specifically, we found reduction of myelination in corresponding brain regions at the time that sensory evoked potentials were maximally impacted. Importantly, we also found that myelination levels recovered when evoked potential latencies recovered. Other changes known to associate with demyelination were also observed at the time of delayed evoked potentials, including the emergence of white matter vacuoles and increased markers for activated microglia and macrophages; these changes also fully reversed by the time that evoked potentials recovered. Our results support the hypothesis that skull-surface recorded evoked potential latencies can dynamically track CNS myelination changes. The methods developed here allow for longitudinally tracking functional myelination changes in vivo in preclinical rodent models with a quantitative biomarker that can also be applied clinically and will facilitate translational development of CNS remyelinating therapies.

Abstract WP417: Novel Animal Model for Cerebral Small Vessel Disease

Introduction: Cerebral small vessel disease (SVD) is a common finding in patients with stroke. It can manifest as white matter hyperintensities (WMH), microbleeds or lacunar strokes. Presence of SVD is an independent risk factor for stroke and is considered a poor prognostic factor in stroke recovery. In addition, SVD has been associated with vascular dementia, depression and gait disorder. There are no good animal models to study SVD. Hypothesis: The precise mechanism behind development of SVD is not clearly understood. It’s likely a result of multiple different processes including decreased blood flow, inflammation with blood brain barrier disruption, degeneration and myelin breakdown. We try to study the role of reduced blood flow and inflammation in the development of SVD with the eventual goal of developing an agent that may prevent the development or progression of SVD. Methods: We remodeled a novel murine SVD model - asymmetric common carotid artery surgery (ACAS), published recently. We placed an ameroid constrictor around the right common carotid artery (CCA) which gradually narrows and eventually occludes vessels by releasing hygroscopic casein material, and a microcoil around the left CCA in mice. This model causes gradual narrowing of the vessels and a significant reduction of cerebral blood flow as detected by Laser Speckle Imager. These mice were compared to sham control which underwent a sham surgery without any vessel occlusion (n=7 per group). Animals were monitored for 30 days. Results: In the ACAS group, the model caused morbidity in all mice and death in 2 of 7 mice. Histologically, we observed marked vacuoles in white matter evaluated by H&amp;E staining. We devised a severity score based on the extent of white matter damage and presence of infarcts under microscope. Based on this score, the damage was significantly worse in the ACAS group as compared with sham controls. Conclusions: These findings demonstrate the role of gradual blood flow reduction in development of SVD. We plan to further study the mechanisms behind SVD and develop novel treatments with the goal of preventing SVD.

Posterior reversible encephalopathy syndrome in stroke-prone spontaneously hypertensive rats on high-salt diet

Stroke-prone spontaneously hypertensive rats (SHRSP) on high-salt diet are characterized by extremely high arterial pressures, and have been endorsed as a model for hypertensive small vessel disease and vascular cognitive impairment. However, rapidly developing malignant hypertension is a well-known cause of posterior reversible encephalopathy syndrome (PRES) in humans, associated with acute neurological deficits, seizures, vasogenic cerebral edema and microhemorrhages. In this study, we aimed to examine the overlap between human PRES and SHRSP on high-salt diet. In SHRSP, arterial blood pressure progressively increased after the onset of high-salt diet and seizure-like signs emerged within three to five weeks. MRI revealed progressive T2-hyperintense lesions suggestive of vasogenic edema predominantly in the cortical watershed and white matter regions. Histopathology confirmed severe blood–brain barrier disruption, white matter vacuolization and microbleeds that were more severe posteriorly. Hematological data suggested a thrombotic microangiopathy as a potential underlying mechanism. Unilateral common carotid artery occlusion protected the ipsilateral hemisphere from neuropathological abnormalities. Notably, all MRI and histopathological abnormalities were acutely reversible upon switching to regular diet and starting antihypertensive treatment. Altogether our data suggest that SHRSP on high-salt diet recapitulates the neurological, histopathological and imaging features of human PRES rather than chronic progressive small vessel disease.

Lily Poisoning in Domestic Cats

Background: Cases of plant intoxication in small animals are observed frequently in the domestic environment, mainly because most dogs and cats live in households and occasionally have access to streets and rural areas. Among such toxic agents, ornamental plants of the genus Lilium and Hemerocallis, which are potentially nephrotoxic to the feline species, are highlighted. Affected cats start presenting clinical signs 1-6 h after plant ingestion. Renal failure takes place in 12-72 h, and death may occur in an interval ranging from three to seven days. The objective of this article is to describe the epidemiological, clinical and pathological findings of lily (Lilium sp.) poisoning in two cats.Case: The aspects of lily poisoning in two cats are described (cat #1 and cat #2). Cat #1 was a 3-year-old, mixed breed female cat, which presented a clinical history of anorexia, apathy, drooling, vomiting and polydipsia. Serum biochemical analysis revealed creatinine elevation (21.2 mg/dL), as well as hyperphosphatemia (19 mg/dL). Seventy-two h after the onset of clinical signs, renal failure progressed to anuria, followed by death. The second animal of this report (cat #2) was a 2-year-old, mixed-breed male cat. The animal was found dead by the owner without displaying any previous clinical signs. Cats #1 and #2 ingested leaves of lily, which were present in their households as ornamental plants. At necropsy, the kidneys of both cats presented mild enlargement. Moderate perirenal edema was also noted. Cat #1 showed morphologic extrarenal uremic lesions, characterized by ulcers in the oral mucosa and in the margin of the tongue ventral surface. Microscopic lesions observed in both cases were similar and compatible with acute toxic nephropathy. Histologically, severe epithelial cell degeneration and necrosis of proximal and distal convoluted tubules were noted. Other renal microscopic findings included hyaline and granular casts, tubule regeneration and occasional birefringent oxalate crystals. Cat #1 also presented moderate white matter vacuolation in the telencephalon and cerebellum.Discussion: The epidemiologic, clinical and pathological findings reported in the present study are similar to previous descriptions of lily poisoning in cats. Lily poisoning has been described in both males and females, without breed and age predisposition, similarly to what has been found in the present study. Kidney metabolite excretion, including the elimination of molecules such as creatinine, urea, and phosphorus is usually compromised in these cases, which was noted in cat #1. The same animal showed extrarenal manifestations of renal failure, leading to a clinical presentation of uremic syndrome, which is not frequent in these intoxications. Animals intoxicated by lily usually die from renal failure and anuria. In most cases, lesions are restricted to the kidneys. In the reported cases, the microscopical lesions consisted of tubule epithelial cells degenerative changes and necrosis. Acute lily intoxication in cats must be differentiated from other conditions, such as intoxications due to aminoglycoside antibiotics, heavy metals, nonsteroidal anti-inflammatory drugs, antifungal agents, chemotherapeutic drugs, and ethylene glycol. The knowledge regarding the toxic potential of ornamental plants is fundamental in order to prevent such events of intoxication, as well as to reach the final diagnosis. Epidemiological, clinical and pathological findings were essential to conclude the final diagnosis.

Brain Vacuolation Resulting From Administration of the Type II Ampakine CX717 Is An Artifact Related to Molecular Structure and Chemical Reaction With Tissue Fixative Agents.

Ampakines are small molecule positive allosteric modulators of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). One class II ("low impact") ampakine, CX717, has been implicated to have a neurotoxic effect based on findings in nonclinical, long-term toxicity studies. The neurotoxicity concerns, which halted the clinical development of the molecule, arose due to a finding of extensive white matter vacuolation in multiple brain regions of animals that were administered high doses of CX717 in several test species (unpublished data). This work characterized the features and a potential mechanism by which ampakines induce vacuoles in brain tissue. Brain sections from adult rats given CX717 (750 mg/kg BID by oral gavage) exhibited no vacuoles with acute or short-term dosing. However, after 14 or more days of treatment, vacuoles were prominent in cerebellum, globus pallidus, and hippocampus. Vacuole margins were lined by glial fibrillary acidic protein (GFAP), and by transmission electron microscopy were shown to be astrocyte processes. CX717-associated vacuoles occurred in formaldehyde-fixed specimens but not flash-frozen samples. Time-course experiments showed that brain tissue slices from CX717-treated animals exhibit no vacuoles until immersed in formaldehyde fixative, whereupon vacuoles form and expand in a time-dependent manner. Chemical interactions in test tube experiments have demonstrated that the combination of CX717 and formalin in an aqueous solution produces an exothermic reaction. Taken together, the data indicate that CX717 does not induce vacuoles in vivo, but rather is associated with astrocyte vacuolation post mortem, likely as the ampakine reacts with formalin to produce gas pockets in brain parenchyma.

Megalencephalic leukoencephalopathy with cysts: theGlialcam‐null mouse model

ObjectiveMegalencephalic leukoencephalopathy with cysts (MLC) is a genetic infantile‐onset disease characterized by macrocephaly and white matter edema due to loss of MLC1 function. Recessive mutations in either MLC1 or GLIALCAM cause the disease. MLC1 is involved in astrocytic volume regulation; GlialCAM ensures the correct membrane localization of MLC1. Their exact role in brain ion‐water homeostasis is only partly defined. We characterized Glialcam‐null mice for further studies.MethodsWe investigated the consequences of loss of GlialCAM in Glialcam‐null mice and compared GlialCAM developmental expression in mice and men.Results Glialcam‐null mice had early‐onset megalencephaly and increased brain water content. From 3 weeks, astrocytes were abnormal with swollen processes abutting blood vessels. Concomitantly, progressive white matter vacuolization developed due to intramyelinic edema. Glialcam‐null astrocytes showed abolished expression of MLC1, reduced expression of the chloride channel ClC‐2 and increased expression and redistribution of the water channel aquaporin4. Expression of other MLC1‐interacting proteins and the volume regulated anion channel LRRC8A was unchanged. In mice, GlialCAM expression increased until 3 weeks and then stabilized. In humans, GlialCAM expression was highest in the first 3 years to then decrease and stabilize from approximately 5 years.Interpretation Glialcam‐null mice replicate the early stages of the human disease with early‐onset intramyelinic edema. The earliest change is astrocytic swelling, further substantiating that a defect in astrocytic volume regulation is the primary cellular defect in MLC. GlialCAM expression affects expression of MLC1, ClC‐2 and aquaporin4, indicating that abnormal interplay between these proteins is a disease mechanism in megalencephalic leukoencephalopathy with cysts.

White matter pathology in sporadic frontotemporal lobar degeneration with TDP-43 proteinopathy.

To characterize white matter pathology in frontotemporal lobar degeneration (FTLD) with TDP-43 proteinopathy (FTLD-TDP) and its relationship to gray matter pathology. Fiber tracts from frontal and temporal lobes of 10 sporadic cases of FTLD and 8 controls. Density and spatial patterns of vacuolation, glial cell nuclei, and glial inclusions (GI) were studied in 4 fiber tracts from each case. Densities of vacuoles but not glial cells were greater in FTLD-TDP than controls. No GI were observed in controls, while in FTLD-TDP, greatest densities of GI were observed in the cortex of early-onset cases. Vacuoles, glial cell nuclei, and GI were distributed in clusters which were regularly distributed across the tract. Densities of vacuoles in white matter were positively correlated with those in adjacent gray matter, and correlations were also present between GI in white matter and TDP-43-immunoreactive pathology in gray matter. (1) Degeneration of white matter in sporadic FTLD-TDP was characterized by increased vacuolation and GI, (2) pathological changes were topographically distributed, which suggests propagation of pathological TDP-43 in specific groups of fibers, and (3) both white matter pathology and gray matter pathology need to be considered to quantify the pathological "load" in FTLD-TDP. .

Suppressing N-Acetyl-l-Aspartate Synthesis Prevents Loss of Neurons in a Murine Model of Canavan Leukodystrophy.

This is the first demonstration of cortical and cerebellar neuron depletion and progressive cerebral cortical thinning in an animal model of Canavan disease. Genetic suppression of N-acetyl-l-aspartate (NAA) synthesis, previously shown to block brain vacuolation in aspartoacylase-deficient mice, also prevents neuron loss and cerebral cortical atrophy in these mice. These results suggest that lowering the concentration of NAA in the brains of children with Canavan disease would prevent or slow progression of neurological deficits.

Adverse effects in lumbar spinal cord morphology and tissue biochemistry in Sprague Dawley male rats following exposure to a continuous 1-h a day 900-MHz electromagnetic field throughout adolescence

Cell phones, an indispensable element of daily life, are today used at almost addictive levels by adolescents. Adolescents are therefore becoming increasingly exposed to the effect of the electromagnetic field (EMF) emitted by cell phones. The purpose of this study was to investigate the effect of exposure to a 900-MHz EMF throughout adolescence on the lumbar spinal cord using histopathological, immunohistochemical and biochemical techniques. Twenty-four Sprague Dawley (28.3–43.9g) aged 21days were included in the study. These were divided equally into three groups – control (CG), sham (SG) and electromagnetic (ELMAG). No procedure was performed on the CG rats until the end of the study. SG and ELMAG rats were kept inside an EMF cage (EMFC) for 1h a day every day at the same time between postnatal days 22 and 60. During this time, ELMAG rats were exposed to the effect of a 900-MHz EMF, while the SG rats were kept in the EMFC without being exposed to EMF. At the end of the study, the lumbar regions of the spinal cords of all rats in all groups were extracted. Half of each extracted tissue was stored at −80°C for biochemical analysis, while the other half was used for histopathological and immunohistochemical analyses. In terms of histopathology, a lumbar spinal cord with normal morphology was observed in the other groups, while morphological irregularity in gray matter, increased vacuolization and infiltration of white matter into gray matter were pronounced in the ELMAG rats. The cytoplasm of some neurons in the gray matter was shrunken and stained dark, and vacuoles were observed in the cytoplasms. The apoptotic index of glia cells and neurons were significantly higher in ELMAG compared to the other groups. Biochemical analysis revealed a significantly increased MDA value in ELMAG compared to CG, while SOD and GSH levels decreased significantly. In conclusion, our study results suggest that continuous exposure to a 900-MHz EMF for 1h a day through all stages of adolescence can result in impairments at both morphological and biochemical levels in the lumbar region spinal cords of Sprague Dawley rats.

Oligodendroglial deletion of ESCRT-I component TSG101 causes spongiform encephalopathy.

Vacuolation of the central nervous system (CNS) is observed in patients with transmissible spongiform encephalopathy, HIV-related encephalopathy and some inherited diseases, but the underlying cellular mechanisms remain poorly understood. Mice lacking the mahogunin ring finger-1 (MGRN1) E3 ubiquitin ligase develop progressive, widespread spongiform degeneration of the CNS. MGRN1 ubiquitinates and regulates tumour susceptibility gene 101 (TSG101), a central component of the endosomal trafficking machinery. As loss of MGRN1 is predicted to cause partial TSG101 loss-of-function, we hypothesised that CNS vacuolation in Mgrn1 null mice may be caused by the accumulation of multi-cisternal endosome-like 'class E' vacuolar protein sorting (vps) compartments similar to those observed in Tsg101-depleted cells in culture. To test this hypothesis, Tsg101 was deleted from mature oligodendroglia in vivo. This resulted in severe spongiform encephalopathy, histopathologically similar to that observed in Mgrn1 null mutant mice but with a more rapid onset. Vacuoles in the brains of Tsg101-deleted and Mgrn1 mutant mice labelled with endosomal markers, consistent with an endosomal origin. Vacuoles in the brains of mice inoculated with Rocky Mountain Laboratory (RML) prions did not label with these markers, indicating a different origin, consistent with previously published studies that indicate RML prions have a primary effect on neurons and cause vacuolation in an MGRN1-independent manner. Oligodendroglial deletion of Rab7, which mediates late endosome-to-lysosome trafficking and autophagosome-lysosome fusion, did not cause spongiform change. Our data suggest that the formation of multi-cisternal 'class E' vps endosomal structures in oligodendroglia leads to vacuolation. This work provides the first evidence that disrupting multi-vesicular body formation in oligodendroglia can cause white matter vacuolation and demyelination. HIV is known to hijack the endosomal sorting machinery, suggesting that HIV infection of the CNS may also act through this pathway to cause encephalopathy.