White Matter Components Research Articles

Regional structural hypo- and hyperconnectivity of frontal-striatal and frontal-thalamic pathways in behavioral variant frontotemporal dementia.

Behavioral variant frontotemporal dementia (bvFTD) has been predominantly considered as a frontotemporal cortical disease, with limited direct investigation of frontal-subcortical connections. We aim to characterize the grey and white matter components of frontal-thalamic and frontal-striatal circuits in bvFTD. Twenty-four patients with bvFTD and 24 healthy controls underwent morphological and diffusion imaging. Subcortical structures were manually segmented according to published protocols. Probabilistic pathways were reconstructed separately from the dorsolateral, orbitofrontal and medial prefrontal cortex to the striatum and thalamus. Patients with bvFTD had smaller cortical and subcortical volumes, lower fractional anisotropy, and higher mean diffusivity metrics, which is consistent with disruptions in frontal-striatal-thalamic pathways. Unexpectedly, regional volumes of the striatum and thalamus connected to the medial prefrontal cortex were significantly larger in bvFTD (by 135% in the striatum, p = .032, and 217% in the thalamus, p = .004), despite smaller dorsolateral prefrontal cortex connected regional volumes (by 67% in the striatum, p = .002, and 65% in the thalamus, p = .020), and inconsistent changes in orbitofrontal cortex connected regions. These unanticipated findings may represent compensatory or maladaptive remodeling in bvFTD networks. Comparisons are made to other neuropsychiatric disorders suggesting a common mechanism of changes in frontal-subcortical networks; however, longitudinal studies are necessary to test this hypothesis.

Influence of k-space trajectory corrections on proton density mapping with ultrashort echo time imaging: Application for imaging of short T2 components in white matter

PurposeTo evaluate the impact of MR gradient system imperfections and limitations for the quantitative mapping of short T2* signals performed by ultrashort echo time (UTE) acquisition approach. Materials and methodsThe measurement of short T2* signals from a phantom and a healthy volunteer study (8 subjects of average age 28 ± 4 years) were performed on a 3T scanner. The characteristics of the gradient system were obtained using calibration method performed directly on the measured subject or phantom. This information was used to calculate the actual sampling trajectory with the help of a parametric eddy current model. The actual sample positions were used to reconstruct corrected images and compared with uncorrected data. ResultsComparison of both approaches, i.e., without and with correction of k-space sampling trajectories revealed substantial improvement when correction was applied. The phantom experiments demonstrate substantial in-plane signal intensity variations for uncorrected sampling trajectories. In the case of the volunteer study, this led to significant differences in relative proton density (RPD) estimation between the uncorrected and corrected data (P = 0.0117 by Wilcoxon matched-pairs test) and provides for about ~15% higher values for short T2* components of white matter (WM) in the case of uncorrected images. ConclusionThe imperfection of the applied gradients could induce errors in k-space data sampling which further propagates into the fidelity of the UTE images and jeopardizes precision of quantification. However, the study proved that measurement of gradient errors together with correction of sample positions can contribute to increased accuracy and unbiased characterization of short T2* signals.

Leukodystrophies due to astroyctic dysfunction.

Leukodystrophies are genetically determined disorders due to defects in any structural components of the brain white matter. This mini-symposium presents a selection of leukodystrophies due to astrocytic dysfunction, the astrocytopathies. Examples are provided of astrocytopathies due to defects in astrocyte-specific proteins and in which astrocytes play a major role in the pathophysiology. Knowledge on the disease mechanisms underlying these leukodystrophies also provides information how loss of physiologic functions and gain of detrimental functions in astrocytes leads to degeneration of the white matter.

Autoantibodies to myelin proteins as biomarkers to identify nervous system injuries in Gulf War Illness and other neuromuscular disorders

Abstract A study on veterans with Gulf War Illness (GWI) from Madison VA Hospital demonstrated a widespread disruption of damages to the white matter using magnetic resonance brain imaging suggesting a cause of prolonged chronic musculoskeletal pain. We hypothesized that exposure to various chemicals could cause delayed neurotoxicity and that myelin is an important white matter component, which play a critical role in neural function and plasticity. Any disruption to myelin may result in reduced brain connectivity, musculoskeletal pain, and cognitive dysfunction. Since myelin is composed of various proteins, dysregulation or damage over a period will form a distinguishable biomarker in CSF and in serum/plasma. Further, continued damage could elicit an immune response. With these reasoning, we measured serum/plasma levels of myelin proteins and autoantibodies specific to myelin proteins by ELISA in Veterans with Gulf War Illness (GWI) and other patients with neuronal disorders (Multiple Sclerosis (MS), Parkinson’s disease (PD), mild Traumatic Brain Injury (TBI), Flight Crews with chronic pain and veterans with Chronic Fatigue Syndrome (CFS) and Lupus (SLE)). We quantitated several myelin proteins (MPZ, MAG, MBP MOG, MOBP, PMP2, and NF155) to determine the intensity of disruption. Autoantibody levels in MS patients were used as positive control and since all the samples (n=10) tested showed the highest level of IgG specific autoantibodies compared to other cohorts. Significantly increased levels of NF155, MOG, MOBP, and MAG were observed among all groups compared to controls (p<0.001). Elevated levels of MPZ and PMP2 characterized PD and SLE (p<0.01) and GWI veterans showed elevated levels of MBP compared CFS and healthy cohorts.

Double Diffeomorphism: Combining Morphometry and Structural Connectivity Analysis.

The brain is composed of several neural circuits which may be seen as anatomical complexes composed of grey matter structures interconnected by white matter tracts. Grey and white matter components may be modeled as 3-D surfaces and curves, respectively. Neurodevelopmental disorders involve morphological and organizational alterations which cannot be jointly captured by usual shape analysis techniques based on single diffeomorphisms. We propose a new deformation scheme, called double diffeomorphism, which is a combination of two diffeomorphisms. The first one captures changes in structural connectivity, whereas the second one recovers the global morphological variations of both grey and white matter structures. This deformation model is integrated into a Bayesian framework for atlas construction. We evaluate it on a data-set of 3-D structures representing the neural circuits of patients with Gilles de la Tourette syndrome (GTS). We show that this approach makes it possible to localise, quantify, and easily visualise the pathological anomalies altering the morphology and organization of the neural circuits. Furthermore, results also indicate that the proposed deformation model better discriminates between controls and GTS patients than a single diffeomorphism.

Meynert’s Nucleus Complex White Matter Abnormalities in Autism Spectrum Disorders: An MRI Study

Introduction: Cholinergic dysfunction has been proposed to play a role in autistic symtomatology. However, to date, its structural correlates are poorly understood. Methods: Twenty-five low-functioning, non-verbal males with Autism Spectrum Disorders (ASD) and 25 controls were enrolled in the study. All underwent MR T1-weighted 3D Structural Imaging and Diffusion Tensor Imaging. Grey and white matter components of the Meynert’s Nucleus Complex were then identified on MR images, and both grey matter density and white matter mean Fractional Anisotropy in the Meynert’s Nucleus region of interest were quantified for each subject. Non-verbal IQ was assessed in all subjects with ASD. Results: We showed reduced white matter Fractional Anisotropy in the bundles surrounding the Meynert’s Nucleus in ASD subjects compared to controls. Fractional Anisotropy in these bundles was positively associated with non-verbal IQ, independently from whole brain white matter mean Fractional Anisotropy. ASD subjects did not show significant abnormalities in Meynert’s Nucleus grey matter density. Conclusions: Our findings suggest that white matter abnormalities in the Meynert’s Nucleus might be involved in the cholinergic deficits of ASD.

A Post-stroke Therapeutic Regimen with Omega-3 Polyunsaturated Fatty Acids that Promotes White Matter Integrity and Beneficial Microglial Responses after Cerebral Ischemia.

White matter injury induced by ischemic stroke elicits sensorimotor impairments, which can be further deteriorated by persistent proinflammatory responses. We previously reported that delayed and repeated treatments with omega-3 polyunsaturated fatty acids (n-3 PUFAs) improve spatial cognitive functions and hippocampal integrity after ischemic stroke. In the present study, we report a post-stroke n-3 PUFA therapeutic regimen that not only confers protection against neuronal loss in the gray matter but also promotes white matter integrity. Beginning 2h after 60min of middle cerebral artery occlusion (MCAO), mice were randomly assigned to receive intraperitoneal docosahexaenoic acid (DHA) injections (10mg/kg, daily for 14days), alone or in combination with dietary fish oil (FO) supplements starting 5days after MCAO. Sensorimotor functions, gray and white matter injury, and microglial responses were examined up to 28days after MCAO. Our results showed that DHA and FO combined treatment-facilitated long-term sensorimotor recovery and demonstrated greater beneficial effect than DHA injections alone. Mechanistically, n-3 PUFAs not only offered direct protection on white matter components, such as oligodendrocytes, but also potentiated microglial M2 polarization, which may be important for white matter repair. Notably, the improved white matter integrity and increased M2 microglia were strongly linked to the mitigation of sensorimotor deficits after stroke upon n-3 PUFA treatments. Together, our results suggest that post-stroke DHA injections in combination with FO dietary supplement benefit white matter restoration and microglial responses, thereby dictating long-term functional improvements.

Language, aging, and cognition: frontal aslant tract and superior longitudinal fasciculus contribute toward working memory performance in older adults.

Previous research has documented change in white matter tract integrity with increasing age. Both interhemispheric and intrahemispheric tracts that underlie language processing are susceptible to these age-related changes. The aim of the current study was to explore age and white matter integrity in language-related tracts as predictors of cognitive task performance in younger and older adults. To this end, we carried out principal component analyses of white matter tracts and confirmatory factor analysis of neuropsychological measures. We next carried out a series of regression analyses that used white matter components to predict scores on each of the neuropsychological components. For both younger and older adults, age was a significant predictor of processing speed and working memory. However, white matter integrity did not contribute independently toward these models. In older adults only, both age and a white matter component that included the bilateral frontal aslant tract and left superior longitudinal fasciculus were significant predictors of working memory. Taken together, these results extend our understanding of the contributions of language-related white matter structure to cognitive processing and highlight the effects of age-related differences in both frontal and dorsal tracts.

Simulations on the influence of myelin water in diffusion-weighted imaging

While myelinated axons present an important barrier to water diffusion, many models used to interpret DWI signal neglect other potential influences of myelin. In this work, Monte Carlo simulations were used to test the sensitivity of DWI results to the diffusive properties of water within myelin. Within these simulations, the apparent diffusion coefficient (Dapp) varied slowly over several orders of magnitude of the coefficient of myelin water diffusion (Dm), but exhibited important differences compared to Dapp values simulated that neglect Dm (=0). Compared to Dapp, the apparent diffusion kurtosis (Kapp) was generally more sensitive to Dm. Simulations also tested the sensitivity of Dapp and Kapp to the amount of myelin present. Unique variations in Dapp and Kapp caused by differences in the myelin volume fraction were diminished when myelin water diffusion was included. Also, expected trends in Dapp and Kapp with experimental echo time were reduced or inverted when accounting for myelin water diffusion, and these reduced/inverted trends were seen experimentally in ex vivo rat brain DWI experiments. In general, myelin water has the potential to subtly influence DWI results and bias models of DWI that neglect these components of white matter.

Characterization of White Matter Injury in a Rat Model of Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion can lead to ischemic white matter injury resulting in vascular dementia. To characterize white matter injury in vascular dementia, we investigated disintegration of diverse white matter components using a rat model of chronic cerebral hypoperfusion. Chronic cerebral hypoperfusion was modeled in Wistar rats by permanent occlusion of the bilateral common carotid arteries. We performed cognitive behavioral tests, including the water maze task, odor discrimination task, and novel object test; histological investigation of neuroinflammation, oligodendrocytes, myelin basic protein, and nodal or paranodal proteins at the nodes of Ranvier; and serial diffusion tensor imaging. Cilostazol was administered to protect against white matter injury. Diverse cognitive impairments were induced by chronic cerebral hypoperfusion. Disintegration of white matter was characterized by neuroinflammation, loss of oligodendrocytes, attenuation of myelin density, structural derangement at the nodes of Ranvier, and disintegration of white matter tracts. Cilostazol protected against cognitive impairments and white matter disintegration. White matter injury induced by chronic cerebral hypoperfusion can be characterized by disintegration of diverse white matter components. Cilostazol might be a therapeutic strategy against white matter disintegration in patients with vascular dementia.

Neuroimaging of white matter abnormalities in pediatric hydrocephalus

Hydrocephalus (HCP) is a severe pathologic condition in which the ventricular system enlarges in response to abnor- mal cerebrospinal fluid production and absorption mechanisms. While accumulating evidence implicates damage to various white matter (WM) structures as one of the major neurobiological mechanisms underlying poor behavioral outcomes in children with HCP, current evaluation of such damage remains limited. Diffusion tensor imaging (DTI) is a unique magnetic resonance technique that exploits differences in the diffusion properties of water molecules in different tissue. Anisotropic diffusion prop- erties, as measured by DTI, are strongly influenced by the micro-structural components of WM and thus can help to assess the properties in tissue constituents, tissue microstructure and cytoarchitecture. Initial clinical studies have shown that DTI is a sen- sitive imaging tool for investigating WM damage as well as the extent of recovery in HCP. A key study has shown that the periventricular WM and corona radiata in children between 12-18 years exhibited increased pre-operative fractional anisotropy (FA) driven by a slightly increased axial diffusivity and a more dramatic decreased radial diffusivity. Post-operatively the FA in these regions returned to normal in most patients. In contrast, the corpus callosum was found to have low FA pre-operatively which did not respond to cerebrospinal fluid diversion surgery. A more recent study reported a similar lower FA and higher mean diffusivity in the corpus callosum in infants. However, the abnormalities in the internal capsule were found to be more heterogeneous. Longitudinal study showed that most DTI measurements returned to normal post-operatively. In experimental studies, similar abnormalities in DTI were found in both neonatal and infantile rats with induced HCP. These findings correlated with increased astrocyte and microglial reactivity and reduced myelination. This review also discusses interpretations regarding the different patterns of DTI abnormalities seen in HCP in different WM regions. Overall, support is growing for DTI as a useful non-invasive imaging tool in the diagnosis and treatment of pediatric hydrocephalus.

Acetaldehyde, not ethanol, impairs myelin formation and viability in primary mouse oligodendrocytes.

Excessive ethanol (EtOH) drinking is associated with white matter loss in the brain at all stages of life. Myelin-forming oligodendrocytes (OLs) are a major component of white matter, but their involvement in EtOH-mediated white matter loss is unclear. Myelination continues throughout the life with highest rates during fetal development and adolescence. However, little is known about the effects of EtOH and its principal metabolite acetaldehyde (ACD) on OLs at the cellular level. We compared the responses to different concentrations of EtOH or ACD by primary OLs in culture. EtOH did not cause significant cell death at concentrations lower than 120 mM, even after 24 hours. In comparison, ACD was highly lethal at doses above 50 μM. High concentrations of EtOH (120 mM) and ACD (500 μM) for 24 hours did not reduce myelin in mature OLs. Myelin production and OL differentiation were significantly impaired by 7 days exposure to 500 or 50 μM ACD but not 120 mM EtOH. This study shows that OLs are relatively resistant to EtOH, even at a concentration more than 4 times the typical blood EtOH concentrations associated with social drinking (10 to 30 mM). In contrast, OLs are much more sensitive to ACD than EtOH, particularly with long-term exposure. This suggests that part of white matter loss in response to EtOH, especially during high rates of myelin formation, may be due in part to the effects of its principal metabolite ACD.

Premyelinated central axons express neurotoxic NMDA receptors: relevance to early developing white-matter injury.

Ischemic-type injury to developing white matter is associated with the significant clinical condition cerebral palsy and with the cognitive deficits associated with premature birth. Premyelinated axons are the major cellular component of fetal white matter and loss of axon function underlies the disability, but the cellular mechanisms producing ischemic injury to premyelinated axons have not previously been described. Injury was found to require longer periods of modelled ischemia than at latter developmental points. Ischemia produced initial hyperexcitability in axons followed by loss of function after Na(+) and Ca(2+) influx. N-methyl-D-aspartate- (NMDA) type glutamate receptor (GluR) agonists potentiated axon injury while antagonists were protective. The NMDA GluR obligatory Nr1 subunit colocalized with markers of small premyelinated axons and expression was found at focal regions of axon injury. Ischemic injury of glial cells present in early developing white matter was NMDA GluR independent. Axons in human postconception week 18 to 23 white matter had a uniform prediameter expansion phenotype and postembedded immuno-gold labelling showed Nr1 subunit expression on the membrane of these axons, demonstrating a shared key neuropathologic feature with the rodent model. Premyelinated central axons therefore express high levels of functional NMDA GluRs that confer sensitivity to ischemic injury.

Age related differences in reaction time components and diffusion properties of normal-appearing white matter in healthy adults

Deterioration of the white matter (WM) is viewed as the neural substrate of age differences in speed of information processing (reaction time, RT). However, the relationship between WM and RT components is rarely examined in healthy aging. We assessed the relationship between RT components derived from the Ratcliff diffusion model and micro-structural properties of normal-appearing WM (NAWM) in 90 healthy adults (age 18–82 years). We replicated all major extant findings pertaining to age differences in RT components and WM: lower drift rate, greater response conservativeness, longer non-decision time, lower fractional anisotropy (FA), greater mean (MD), axial (AD) and radial (RD) diffusivity were associated with advanced age. Age differences in anterior regions of the cerebral WM exceeded those in posterior regions. However, the only relationship between RT components and WM was the positive association between DR in the body of the corpus callosum and non-decision time. Thus, in healthy adults, age differences in NAWM diffusion properties are not a major contributor to age differences in RT components. Longitudinal studies with more precise and specific estimates of regional myelin content and evaluation of the contribution of age-related vascular risk factors are necessary to understand cerebral substrates of age-related cognitive slowing.

Can lactate serve as an energy substrate for axons in good times and in bad, in sickness and in health?

In the mammalian white matter, glycogen-derived lactate from astrocytes plays a critical role in supporting axon function using the astrocyte-neuron lactate transfer shuttle (ANLTS) system with specialized monocarboxylate transporters (MCTs). A rapid breakdown of glycogen to lactate during increased neuronal activity or low glucose conditions becomes essential to maintain axon function. Therefore astrocytes actively regulate their glycogen stores with respect to ambient glucose levels such that high ambient glucose upregulates glycogen and low levels of glucose depletes glycogen stores. Although lactate fully supports axon function in the absence of glucose and becomes a preferred energy metabolite when axons discharge at high frequency, it fails to benefit axon function during an ischemic episode in white matter. Emerging evidence implies a similar lactate transport system between oligodendrocytes and the axons they myelinate, suggesting another metabolic coupling pathway in white matter. Therefore the conditions that activate this lactate shuttle system and the signaling mechanisms that mediate activation of this system are of great interest. Future studies are expected to unravel the details of oligodendrocyte-axon lactate metabolic coupling to establish how white matter components metabolically cooperate and that lactate may be the universal metabolite to sustain CNS function.

White matter injury: Ischemic and nonischemic.

Ischemic pathologies of white matter (WM) include a large proportion of stroke and developmental lesions while multiple sclerosis (MS) is the archetype nonischemic pathology. Growing evidence suggests other important diseases including neurodegenerative and psychiatric disorders also involve a significant WM component. Axonal, oligodendroglial, and astroglial damage proceed via distinct mechanisms in ischemic WM and these mechanisms evolve dramatically with maturation. Axons may pass through four developmental stages where the pattern of membrane protein expression influences how the structure responds to ischemia; WM astrocytes pass through at least two and differ significantly in their ischemia tolerance from grey matter astrocytes; oligodendroglia pass through at least three, with the highly ischemia intolerant pre-oligodendrocyte (pre-Oli) stage linking the less sensitive precursor and mature phenotypes. Neurotransmitters play a central role in WM pathology at all ages. Glutamate excitotoxicity in WM has both necrotic and apoptotic components; the latter mediated by intracellular pathways which differ between receptor types. ATP excitotoxicity may be largely mediated by the P2X7 receptor and also has both necrotic and apoptotic components. Interplay between microglia and other cell types is a critical element in the injury process. A growing appreciation of the significance of WM injury for nonischemic neurological disorders is currently stimulating research into mechanisms; with curious similarities being found with those operating during ischemia. A good example is traumatic brain injury, where axonal pathology can proceed via almost identical pathways to those described during acute ischemia.

Human brain connections

The Atlas of Human Brain Connections by Catani and Thiebaut de Schotten (2012) covers the long association, commissural and projection systems of the cerebral hemispheres as studied with diffusion tensor tractography. The atlas begins with an extensive and well-illustrated historical survey of these systems and the disconnection syndromes that result from their interruption. This is followed by chapters on the individual systems, including an atlas of each in serial axial, coronal and parasagittal sections, and an atlas of all the systems combined. The book ends with an overview of diffusion tensor imaging tractography and its applications. I must have dissected the long association systems of the cerebral hemispheres numerous times during lab courses for students or neurological residents. Blunt dissection of fibre systems is a method of great antiquity, but became more precise with the preservation of the brain in alcohol. The 1840s witnessed an important change in methodology, with blunt dissection of fibre systems replaced by microscopy of serial sections, as introduced by Benedict Stilling in his atlases of the brainstem (1846). This method allowed nuclei and the components of white matter to be distinguished with much greater precision and solved the problem inherent in blunt dissection, namely its inability to trace fibre bundles beyond the point where they merge or are crossed by other fascicles (Voogd and van Baarsen, 2013). ![Graphic][1] Stilling (1846) used wet unstained sections, relying on the differential refraction of myelin to obtain contrast. However, his method was greatly improved with the subsequent development of fixation and staining techniques. The first systematic microscopical study of the long association systems was published by Dejerine, and was followed by the atlases of Wernicke, and then Jelgersma. Wernicke’s atlas is remarkable because it consists of original photographic prints of sections in the three major planes; however, even before … [1]: /embed/inline-graphic-1.gif

Sporadic meningioangiomatosis: imaging findings with histopathologic correlations in seven patients

Meningioangiomatosis (MA) is a rare benign cerebral lesion. We aimed to evaluate the CT and MR features of sporadic MA, with a focus on the correlation between imaging and histopathologic findings. CT (n = 7) and MR (n = 8) images of eight patients (6 men and 2 women; mean age, 12.8 years; range, 4-22 years) with pathologically proven MA were retrospectively reviewed. After dividing the MA lesions according to their distribution into cortical and subcortical white matter components, the morphologic characteristics were analyzed and correlated with histopathologic findings in seven patients. CT and MR images showed cortical (n = 4, 50%) and subcortical white matter (n = 7, 88%) components of MA. All four cortical components revealed hyperattenuation on CT scan and T1 isointensity/T2 hypointensity on MR images, whereas subcortical white matter components showed hypoattenuation on CT scan and T1 hypointensity/T2 hyperintensity on MR images. Two cortical components (25%) demonstrated enhancement and one subcortical white matter component demonstrated cystic change. Seven cases were available for imaging-histopathologic correlation. In all seven cases, the cortex was involved by MA and six patients (86%) showed subcortical white matter involvement by MA. There were excellent correlations between the imaging and histopathologic findings in subcortical white matter components, and the accuracy was 100% (seven of seven); whereas there were poor correlations in cortical components, and the accuracy was 43% (three of seven). The cerebral cortex and subcortical white matter were concomitantly involved by MA. Subcortical white matter components of MA were more apparent than cortical components on CT and MR imaging.

Human but Not Laboratory Borna Disease Virus Inhibits Proliferation and Induces Apoptosis in Human Oligodendrocytes In Vitro.

Borna disease virus (BDV) is a neurotropic virus that produces neuropsychiatric dysfunction in a wide range of warm-blooded species. Several studies have associated BDV with human psychiatric illness, but the findings remain controversial. Although oligodendrocytes are a major glial component of brain white matter and play a pivotal role in neuronal cell function, BDV's effects on human oligodendrocytes have not been clarified. Here, the effects of two BDV strains, Hu-H1 (isolated from a bipolar patient) and Strain V (a laboratory strain), on the proliferation and apoptosis of human oligodendrocytes were investigated. Three experimental cell lines were constructed: Hu-H1-infected oligodendroglioma (Hu-H1) cells, Strain V-infected oligodendroglioma (Strain V) cells, and non-infected oligodendroglioma (control) cells. BDV infection was assayed by BDV nucleoprotein (p40) immunofluorescence, cell proliferation was assayed by Cell Counting Kit-8 (CCK8), and cell cycle phases and apoptosis were assayed by flow cytometry. Expressions of the apoptosis-related proteins Bax and Bcl-2 were measured by Western blotting. p40 expression was confirmed in Hu-H1 and Strain V on and after day three post-infection. Strain V cells showed significantly greater cellular proliferation than Hu-H1 cells on and after day three post-infection. In Hu-H1 cells, Bax and Bcl-2 expression were significantly increased and decreased, respectively, on and after day three post-infection. In contrast, in Strain V cells, Bax and Bcl-2 expression were significantly decreased and increased, respectively, on and after day three post-infection. In conclusion, Hu-H1 inhibits cellular proliferation and promotes apoptosis in human oligodendrocytes via Bax upregulation and Bcl-2 downregulation. In contrast, Strain V promotes cellular proliferation and inhibits apoptosis in human oligodendrocytes via Bax downregulation and Bcl-2 upregulation. The effects of the Hu-H1 strain (isolated from a bipolar patient) are opposite from those of Strain V (a laboratory strain), thereby providing a proof of authenticity for both.

Myelin and Axon Abnormalities in Schizophrenia Measured with Magnetic Resonance Imaging Techniques

In schizophrenia (SZ), disturbances in integration of activity among brain regions seem to be as important as abnormal activity of any single region. Brain regions are connected through white matter (WM) tracts, and diffusion tensor imaging has provided compelling evidence for WM abnormalities in SZ. However, diffusion tensor imaging alone cannot currently pinpoint the biological basis of these abnormalities. In this study, we combined a myelin-specific and an axon-specific magnetic resonance imaging approach to examine potentially distinct abnormalities of WM components in SZ. Magnetization transfer ratio (MTR) provides information on myelin content, whereas diffusion tensor spectroscopy provides information on metabolite diffusion within axons. We collected data from a 1 × 3 × 3 cm voxel within the right prefrontal cortex WM at 4 Tesla and studied 23 patients with SZ and 22 age- and sex-matched healthy control participants. The MTR was significantly reduced in SZ, suggesting reduced myelin content. By contrast, the apparent diffusion coefficient of N-acetylaspartate (NAA) was significantly elevated, suggesting intra-axonal abnormalities. Greater abnormality of both MTR and the apparent diffusion coefficient of NAA correlated with more adverse outcomes in the patient group. The results suggest that WM abnormalities in SZ include both abnormal myelination and abnormal NAA diffusion within axons. These processes might be associated with abnormal signal transduction and abnormal information processing in SZ.