Astrogliopathy and oligodendrogliopathy are early events in CNS demyelination.

We examined the phenotypic composition of cells and the underlying mechanisms of demyelination following injection of lipopolysaccharide (LPS) into the corpus callosum of rats. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay showed fragmented DNA, which co-localized with oligodendrocytes in areas of demyelination following intracerebral injection with LPS. Immunostaining showed the presence of caspase 3 in cells which expressed the oligodendrocyte markers, suggesting activation of the apoptotic pathway. Commensurate reduction in glial fibrillary acid protein (GFAP)+/ gap junction protein connexin43+ (Cx43) cells, was also seen in the corpus callosum prior to histochemical evidence of demyelination. Expression of mRNA for proinflammatory cytokines was maximal 3 day postinjection, at a time when the numbers of TUNEL positive cells in the corpus callosum were declining and the total number of CD68+ cells peaked at day 14 postinjection. Our studies suggest that death of oligodendrocytes is an early event in LPS model of demyelination. We believe that the innate immune model of oligodendrocyte death will be useful in the development of neuroprotective agents capable of rescuing oligodendrocytes from apoptosis.

An 80-year-old man with a ring-enhancing right basal ganglia lesion.

Cerebral phaeohyphomycosis is a rare diagnosis that designates a central nervous system (CNS) infection by dematiaceous fungi. These organisms most commonly cause cutaneous infections in humans, but much less commonly, they cause CNS disease with evidence of neurotropism. We describe here the clinical course and post-mortem findings in a fatal case of cerebral phaeohyphomycosis occurring in an 80-year-old man. He had a long and complex past medical history and approximately 7 weeks prior to his death, he presented to an outside institution with imaging findings reported to be consistent with a cerebrovascular accident. He was treated with thrombolytic therapy and sent to a rehabilitation program. Approximately 2 weeks prior to his death, he was transferred to our institution with worsening chronic heart failure symptoms. Imaging after admission showed a ring-enhancing lesion and the differential diagnosis shifted to include a primary neoplasm vs. an abscess. There was a downward clinical course and neurosurgical biopsy was declined secondary to predicted poor outcome. A full autopsy was performed and confirmed the pre-mortem imaging findings of a cerebral abscess with multiple satellite lesions. The histologic and microbiologic findings were characteristic of cerebral phaeohyphomycosis. Microbiological features and disease characteristics of these organisms as well as incidence and populations affected are also discussed.

Lithium treatment prevents neurocognitive deficit resulting from cranial irradiation.

Curative cancer treatment regimens often require cranial irradiation, resulting in lifelong neurocognitive deficiency in cancer survivors. This deficiency is in part related to radiation-induced apoptosis and decreased neurogenesis in the subgranular zone of the hippocampus. We show that lithium treatment protects irradiated hippocampal neurons from apoptosis and improves cognitive performance of irradiated mice. The molecular mechanism of this effect is mediated through multiple pathways, including Akt/glycogen synthase kinase-3beta (GSK-3beta) and Bcl-2/Bax. Lithium treatment of the cultured mouse hippocampal neurons HT-22 induced activation of Akt (1.5-fold), inhibition of GSK-3beta (2.2-fold), and an increase in Bcl-2 protein expression (2-fold). These effects were sustained when cells were treated with lithium in combination with ionizing radiation. In addition, this combined treatment led to decreased expression (40%) of the apoptotic protein Bax. The additional genes regulated by lithium were identified by microarray, such as decorin and Birc1f. In summary, we propose lithium treatment as a novel therapy for prevention of deleterious neurocognitive consequences of cranial irradiation.

Biochemical and phenotypic abnormalities in kynurenine aminotransferase II-deficient mice.

Kynurenic acid (KYNA) can act as an endogenous modulator of excitatory neurotransmission and has been implicated in the pathogenesis of several neurological and psychiatric diseases. To evaluate its role in the brain, we disrupted the murine gene for kynurenine aminotransferase II (KAT II), the principal enzyme responsible for the synthesis of KYNA in the rat brain. mKat-2(-/-) mice showed no detectable KAT II mRNA or protein. Total brain KAT activity and KYNA levels were reduced during the first month but returned to normal levels thereafter. In contrast, liver KAT activity and KYNA levels in mKat-2(-/-) mice were decreased by >90% throughout life, though no hepatic abnormalities were observed histologically. KYNA-associated metabolites kynurenine, 3-hydroxykynurenine, and quinolinic acid were unchanged in the brain and liver of knockout mice. mKat-2(-/-) mice began to manifest hyperactivity and abnormal motor coordination at 2 weeks of age but were indistinguishable from wild type after 1 month of age. Golgi staining of cortical and striatal neurons revealed enlarged dendritic spines and a significant increase in spine density in 3-week-old mKat-2(-/-) mice but not in 2-month-old animals. Our results show that gene targeting of mKat-2 in mice leads to early and transitory decreases in brain KAT activity and KYNA levels with commensurate behavioral and neuropathological changes and suggest that compensatory changes or ontogenic expression of another isoform may account for the normalization of KYNA levels in the adult mKat-2(-/-) brain.

Differential loss of synaptic proteins in Alzheimer's disease: implications for synaptic dysfunction.

The objective of our research was to determine synaptic protein levels in brain specimens from AD subjects and age-matched control subjects. Further, to determine whether presynaptic or postsynaptic compartments of neurons are preferentially affected in AD patients, we studied 3 presynaptic vesicle proteins (synaptotagmin, synaptophysin, and Rab 3A), 2 synaptic membrane proteins (Gap 43 and synaptobrevin), and 2 postsynaptic proteins (neurogranin and synaptopodin) in specimens from AD and age-matched control brains. Two brain regions--the frontal and parietal cortices--were assessed for protein levels by immunoblotting analysis. We found a loss of both presynaptic vesicle proteins and postsynaptic proteins in all brain specimens from AD patients compared to those from age-matched control subjects. Further, we found that the loss of synaptic proteins was more severe in the frontal cortex brain specimens than in the parietal cortex brain specimens from the AD subjects compared to those from the control subjects, suggesting that the frontal brain may be critical for synaptic function in AD. Using immunohistochemistry techniques, we also determined the distribution pattern of all synaptic proteins in both the frontal and parietal cortices brain specimens from control subjects. Of the 7 synaptic proteins studied, the presynaptic proteins synaptophysin and rab 3A and the postsynaptic protein synaptopodin were the most down-regulated. Our study suggests that postsynaptic proteins and presynaptic proteins are important for synaptic function and may be related to cognitive impairments in AD.

Distribution of dopamine D2-like receptors in the human thalamus: autoradiographic and PET studies.

The distribution of dopamine (DA) D(2)-like receptors in the human thalamus was studied using in vitro autoradiographic techniques and in vivo positron emission tomography in normal control subjects. [(125)I]Epidepride, which binds with high affinity to DA D(2) and D(3) receptors, was used in autoradiographic studies to determine the distribution and density of D(2)-like receptors, and the epidepride analogue [(18)F]fallypride positron was used for positron emission tomography studies to delineate D(2)-like receptors in vivo. Both approaches revealed a heterogeneous distribution of thalamic D(2/3) receptors, with relatively high densities in the intralaminar and midline thalamic nuclei, including the paraventricular, parataenial, paracentral, centrolateral, and centromedian/parafascicular nuclei. Moderate densities of D(2/3) sites were seen in the mediodorsal and anterior nuclei, while other thalamic nuclei expressed lower levels of D(2)-like receptors. Most thalamic nuclei that express high densities of D(2)-like receptors project to forebrain DA terminal fields, suggesting that both the thalamic neurons expressing D(2)-like receptors and the projection targets of these neurons are regulated by DA. Because the midline/intralaminar nuclei receive prominent projections from both the ascending reticular activating core and the hypothalamus, these thalamic nuclei may integrate activity conveying both interoceptive and exteroceptive information to telencephalic DA systems involved in reward and cognition.

Techniques for thick-section Golgi impregnation of formalin-fixed brain tissue.

The histologic staining technique for central nervous system (CNS) tissue known as the Golgi technique was initially developed more than 125 yr ago. It was with this technique that, for the first time, whole nerve cells and their processes were simultaneously observed microscopically. Although the technique was widely used in the early 20th century, its use languished to some extent until the late 1900s when, used in conjunction with ultrastructural studies, it began to provide new insights into microscopic anatomy and pathology of the CNS. Several permutations of the technique have evolved since its early stages. The one represented in this chapter was developed so that Golgi-impregnated CNS tissues could be embedded in polymerized plastic and cut into relatively thick sections for light microscopic study. The advantages are that (a) sections of the clear and almost colorless plastic allow enhanced visualization of the intricate structure and ramification of dendritic elements of CNS neurons, (b) because of the relatively thick microscopic sections (25-30 micro m), details of lengths and arborization of dendritic "trees" can be studied and photographed to provide greater detail than in thinner sections, and (c) numbers and morphologic characteristics of synaptic spines can be precisely evaluated.

Hypermotor seizures in patients with temporal pole lesions.

Hypermotor seizures are considered to be characteristic of frontal lobe epilepsy, with only rare occurrence in temporal lobe epilepsy. After noting hypermotor seizures in several patients with lesions involving the pole of the temporal lobe, we investigated whether temporal pole lesions were associated with hypermotor seizures. We systematically reviewed medical records, MRI images and pathological findings in consecutive patients who underwent epilepsy surgery over the preceding 10 years in our institution and identified eight patients with temporal pole lesions and intractable complex partial seizures. We analyzed all recorded seizures for semiology, classifying seizures as hypermotor or typical "psychomotor." Four patients exhibited hypermotor seizure semiology and four patients manifested typical psychomotor seizure characteristics. In patients with hypermotor seizures, scalp EEG tended to demonstrate lateral anterior temporal ictal onset, with lesser involvement of the sphenoidal electrode, while the patients with psychomotor seizures had initial inferomesial temporal rhythmic theta activity. Two patients with hypermotor seizures had implanted frontal and temporal subdural grids demonstrating orbitofrontal spread before hypermotor behavior. Patients underwent either anterior temporal lobectomy or lesionectomy. All improved considerably, with six patients seizure-free since surgery. We conclude that hypermotor seizures occur frequently in patients with temporal pole lesions. A search for temporal pole pathology is recommended for patients with hypermotor seizures and temporal epileptiform discharges. Modification of the surgical approach to include this region should be considered in patients who exhibit hypermotor seizures.

High-resolution 7T MRI of the human hippocampus in vivo.

PURPOSE: To describe an initial experience imaging the human hippocampus in vivo using a 7T magnetic resonance (MR) scanner and a protocol developed for very high field neuroimaging. MATERIALS AND METHODS: Six normal subjects were scanned on a 7T whole body MR scanner equipped with a 16-channel head coil. Sequences included a full field of view T1-weighted 3D turbo field echo (T1W 3D TFE: time of acquisition (TA)=08:58), T2*-weighted 2D fast field echo (T2*W 2D FFE: TA=05:20), and susceptibility-weighted imaging (SWI: TA=04:20). SWI data were postprocessed using a minimum intensity projection (minIP) algorithm. Total imaging time was 23 minutes. RESULTS: T1W 3D TFE images with 700 microm isotropic voxels provided excellent anatomic depiction of macroscopic hippocampal structures. T2*W 2D FFE images with 0.5 mm in-plane resolution and 2.5 mm slice thickness provided clear discrimination of the Cornu Ammonis and the compilation of adjacent sublayers of the hippocampus. SWI images (0.5 mm in-plane resolution, 1.0 mm slice thickness) delineated microvenous anatomy of the hippocampus. CONCLUSION: In vivo 7T MR imaging can take advantage of higher signal-to-noise and novel contrast mechanisms to provide increased conspicuity of hippocampal anatomy.

Gomez-Lopez-Hernandez syndrome.

We describe a case of Gomez-Lopez-Hernandez syndrome in an 18-month-old boy. Imaging findings included rhombencephalosynapsis with a single dentate nucleus. In addition, MR angiography revealed an azygous anterior cerebral artery. The clinical presentation, MRI findings and pathogenesis are discussed.

A combined deficiency of vitamins E and C causes severe central nervous system damage in guinea pigs.

A short period of combined deficiency of vitamins E and C causes profound central nervous system (CNS) dysfunction in guinea pigs. For this report, CNS histopathology was studied to define the nature and extent of injury caused by this double deficiency. Weanling guinea pigs were fed a vitamin E-deficient or -replete diet for 14 d. Then vitamin C was withdrawn from the diet of some guinea pigs. Four diet groups were thus formed: replete, vitamin E deficient, vitamin C deficient, and both vitamin E and C deficient. From 5 to 11 d after institution of the doubly deficient diet, 9 of 12 guinea pigs developed paralysis, and 2 more were found dead. The remaining guinea pig in the doubly deficient group and all animals in the other 3 groups survived without clinical impairment until the experiment was terminated at 13-15 d. Brains and spinal cords were serially sectioned and stained for examination. Only the combined deficiency produced damage in the CNS. The damage consisted mainly of nerve cell death, axonal degeneration, vascular injury, and associated glial cell responses. The spinal cord and the ventral pons in the brainstem were most severely affected, often exhibiting asymmetric cystic lesions. Several features of the lesions suggest that the primary damage was to blood vessels. These results indicate that the paralysis and death caused by combined deficiency of vitamins E and C in guinea pigs is caused by severe damage in the brainstem and spinal cord.

Detection of chlamydial bodies and antigens in the central nervous system of patients with multiple sclerosis.

To examine a possible relationship between Chlamydia pneumoniae infection and multiple sclerosis (MS), we undertook an immunohistochemical (IHC), molecular, and ultrastructural comparison of central nervous system (CNS) tissue and cerebrospinal fluid (CSF) sediment from patients with MS and control individuals with other neurological diseases (ONDs). In 7 of 20 MS cases, IHC staining was seen in association with ependymal surfaces and periventricular regions of formalin-fixed brain tissue, by use of 3 different antichlamydial antibodies. There was no staining with any of the 3 antichlamydial antibodies in formalin-fixed brain tissue from OND controls (n=17). With available frozen CNS tissue, polymerase chain reaction (PCR) studies for the presence of C. pneumoniae genes were performed. The presence of a PCR signal was confirmed in 5 of 8 MS cases and in 3 of 18 OND controls. In an examination of CSF sediment by electron microscopy, we observed electron-dense structures resembling chlamydial organisms in CSF sediments from 11 of 20 MS cases and 2 of 12 OND controls. The presence of immunogold-labeled electron-dense bodies was correlated with the presence of a PCR signal in 10 of 11 MS cases. Results of studies using these different approaches support our suspicion of the presence of chlamydial organisms in the CNS, in a subset of patients with MS.

The perceptual reality of synesthetic colors.

Synesthesia is a remarkable, rare condition where an individual has multimodal perceptual experiences from a unimodal sensory event. We have studied such an individual, an adult male for whom achromatic words and alphanumeric characters are seen in vivid, reliable colors. We used a variety of perceptual tasks to document the perceptual reality of synesthetic colors and to begin to localize the stage of visual processing where this anomalous binding of externally specified form and internally generated color may take place. Synesthetic colors were elicited by forms defined solely by binocular cues or solely by motion cues, which implies a central locus of visual processing for synesthetic binding of form and color. Also included among our measurements was a difficult visual search task on which non-synesthetic subjects required an effortful search through the visual display. Our subject, in contrast to non-synesthetic subjects, accomplished the task with relative ease because the target of the search had a different synesthetic color from the distractors. Thus, synesthetic experiences appear to originate from a binding of color and form that takes place within central stages of visual processing.