Chemokine receptors on infiltrating leucocytes in inflammatory pathologies of the central nervous system (CNS)

Haematogenous leucocytes enter the central nervous system (CNS) during diverse disorders of varied aetiologies. Understanding the trafficking cues that mediate CNS leucocyte infiltration might promote the development of flexible and selective means to modulate inflammation to achieve clinical benefit. The trafficking machinery of leucocytes has been elucidated during the past decade and consists of cell-surface adhesion molecules, chemoattractant cytokines (chemokines) and their receptors. Recent work in our laboratory characterized chemokine receptors found on T lymphocytes and monocytes in brain sections from subjects with one pathological subtype of multiple sclerosis (MS), an immune-mediated inflammatory demyelinating disease. In these tissues, the types 1 and 5 CC chemokine receptors (CCR1 and CCR5) were detected on perivascular monocytic cells whereas only CCR5 was present on parenchymal macrophages. The type 3 CXC chemokine receptor (CXCR3) was present on virtually all CD3-positive T cells. In the current study, we evaluated the expression of these receptors on the infiltrating cells present in cases of other inflammatory CNS disorders including those of dysimmune, infectious, neoplastic, and vascular aetiology. Perivascular and parenchymal monocytic cells expressed CCR1 in all cases and CXCR3 was consistently present on a substantial proportion of CD3+ T cells. The occurrence of CCR5 on parenchymal macrophages was much less uniform across the varied disorders. These data implicate CCR1 in monocyte infiltration of the CNS and are consistent with reports of studies in CCR1-deficient mice. CXCR3 is also likely to play a role in accumulation of T cells in the inflamed CNS. By contrast, our findings suggest that regulation of CCR5 on phagocytic macrophages may be contingent on the lesion environment.

Chemokine expression in the central nervous system of mice with a viral disease resembling multiple sclerosis: roles of CD4+ and CD8+ T cells and viral persistence

During the first 45 days after intracerebral infection with Theiler's murine encephalomyelitis virus (TMEV), the levels of mRNAs encoding chemokines MCP-1/CCL2, RANTES/CCL5, and IP-10/CXCL10 in the central nervous system (CNS) are closely related to the sites of virus gene expression and tissue inflammation. In the present study, these chemokines were monitored during the latter 135 days of a 6-month course of TMEV-induced disease in susceptible (PLJ) or resistant (C57BL/6) mice that possessed or lacked either CD4+ or CD8+ T cells. These data were additionally correlated to mouse genotype, virus persistence in the CNS, antiviral antibody titers, mortality, and the severity of neurological disease. Surprisingly, the major determinant of chemokine expression was virus persistence: the factors of susceptible or resistant genotype, severity of neuropathology, and presence or absence of regulatory T cells exerted minimal effects. Our observations indicated that chemokine expression in the CNS in this chronic viral disorder was intrinsic to the CNS innate immune response to infection and was not governed by elements of the adaptive immune system.

P2X7-like receptor activation in astrocytes increases chemokine monocyte chemoattractant protein-1 expression via mitogen-activated protein kinase

Leukocyte infiltration in the CNS after trauma or inflammation is triggered in part by upregulation of the chemokine, monocyte chemoattractant protein-1 (MCP-1), in astrocytes. However the signals that induce the upregulation of MCP-1 in astrocytes are unknown. We have investigated the roles for ATP P2X7 receptor activation because ATP is an intercellular signaling transmitter that is released in both trauma and inflammation and P2X7 receptors are involved in immune system signaling. Astrocytes in primary cell culture and acutely isolated from the hippocampus were immunopositive for P2X7 receptors. In astrocyte cultures, application of the selective P2X7 agonist, benzoyl-benzoyl ATP (Bz-ATP), activated MAP kinases extracellular signal receptor-activated kinase 1 (ERK1), ERK2, and p38. Purinergic antagonists depressed this activation with a profile suggesting P2X7 receptors. Bz-ATP also increased MCP-1 expression in cultured astrocytes, and again P2X7 antagonists prevented this increase. Blocking either the ERK1/ERK2 or the p38 pathway (with PD98059 or SB203580, respectively) significantly inhibited Bz-ATP-induced MCP-1 expression. Coapplication of both antagonists caused a greater depression. We also tested the roles for ATP receptor activation in inducing MCP-1 upregulation in corticectomy, an in vivo model of trauma. This model of cortical trauma was previously shown to increase MCP-1 expression in vivo principally in astrocytes. Suramin, a wide-spectrum purinergic receptor antagonist, significantly depressed the rapid (3 hr) trauma-induced increase in MCP-1 mRNA. These data indicate that purinergic transmitter receptors in astrocytes are important in regulating chemokine synthesis. The regulation of MCP-1 in astrocytes by ATP may be important in mediating communication with hematopoietic inflammatory cells.

[Relationship between water supply and consumption of main planting tree species of protection forests in loess area of western Shanxi Province]

Based on three years point-fixed observation, this paper analyzed the relationship between water supply and consumption of black locust(Robinia pseudoscacia L.) and Chinese pine(Pinus tabulaeformis Carr.), the main tree species of protection forests in the loess area of the western Shanxi Province. In April, May and June, the water supply was less than water consumption, while in raining season, the water supply was abundant, and the water storage in soil was increased. During dry seasons and years, more water consumption and less available water supply occurred in high-density stand, showing a serious water deficiency. The water deficiency was in order of south-facing slope > semi-south-facing slope > north-facing slope. The study shows that water consumption characters coefficient could be used as an index to indicate the growth pattern of trees, and the relationship between water supply and consumption.

Temporal lobe volume determined by magnetic resonance imaging in schizotypal personality disorder and schizophrenia

The volumes of the whole temporal lobe, the superior temporal gyrus and the corpus callosum were measured on magnetic resonance images from 13 patients with schizotypal personality disorder (SPD), 27 patients with schizophrenia, and 31 age- and sex-matched controls. Temporal lobe structures were traced on consecutive 1.2mm thick SPGR images. Both patient groups had smaller temporal lobes than normal volunteers, a difference that was more marked for the area outside the superior temporal gyrus than for the STG. Correcting for brain volume diminished differences between normal subjects and schizophrenia patients, but the differences between normal subjects and SPD patients remained. Normal volunteers and SPD patients showed significant correlations between the sagittal section area of the posterior portion of the corpus callosum, which carries temporal interhemispheric connections, and the white matter volume of the temporal lobe. While the sample size is modest, taken together, these results suggest that the psychopathological symptoms of SPD may be related to temporal gray matter loss with relatively intact white matter connectivity, while the cognitive and psychotic symptoms of schizophrenia may be related to temporal gray loss combined with disruption of normal patterns of white matter development.

Monocyte chemoattractant protein (MCP)-1 is rapidly expressed by sympathetic ganglion neurons following axonal injury

EDI-immunoreactive macrophages, absent from the superior cervical ganglia (SCG) of normal rats, appear in these ganglia within 48h after postganglionic axotomy. Further, resident macrophages show changes after axotomy. Since chemokines function as chemoattractants and activators of leukocytes, the effects of axotomy on chemokine expression in the SCG were examined. Within 6 h after nerve transection, increases were seen in mRNA levels for monocyte chemoattractant protein (MCP)-1. MCP-1 mRNA was concentrated in a population of neurons, while MCP-1 protein was localized to endothelial cells. This axotomy-induced neuronal MCP-1 expression may trigger the infiltration and/or activation of macrophages in SCG after injury.

[Sequence analysis of RAN4 of a severe isolate of rice stripe virus in China]

RNA4 segment of a severe isolate of Rice stripe virus, isolated from Liaoning province and designated as PJ isolate, was amplified, cloned and sequenced. RNA4 of PJ isolate had 2157 nucleotide in length. When compared with RNA4 of T and M isolates of Japan and CX isolate of Yunnan province of China that had been previously reported, we found that these four isolates could be divided into two groups. PJ, T and M isolates shared 97.0% and 97.0%-97.5% identities in vORF4 and vcOFR4 at the nucleotide level, respectively and formed one group. The sequences in 5' and 3' terminal non-encoding region were completely identical among these three isolates. In this group, PJ isolate was more closely related to T isolate than to M isolate. The length of intergenic region(IR4) of PJ isolate was as same as that of T isolate, and had 93.0% sequence identity. However, PJ IR4 had an insertion of 19 bp in length compared with isolate M and had only 85.0% sequence identity. CX isolate belonged to another group, which shared only 94.0% and 92.5%-93.5% sequences identities in vORF4 and vcORF4 at the nucleotide level, respectively, even though there were not significant difference between these two group at the amino acid level. There was an insertion of 84 bp in length in the IR4 of CX isolate compared with PJ isolate and the sequence identity between two group reached to 72.0%-75.0%. Even though no base variation occurred in 5' terminal non-coding region, there was two bases substitution in 3' terminal non-coding region. These results showed that the isolates were grouped according to their geographical location. Additionally, highly consensus in 5' and 3' non-encoding region suggested that these regions played an very important role in transcription and replication of viral genome. Finally, the molecular epidemiology and gene functions of Rice stripe virus were discussed in this paper.

Tears contain the complement regulator CD59 as well as decay-accelerating factor (DAF)

Previous studies have shown that DAF (or CD55), a cell surface inhibitor of autologous C3 activation, is present in tears and that > 90% of the C3 convertase regulatory activity in tear fluid resides in this protein (Lass JH et al., Invest Ophth Vis Sci 1990; 31:1136-48). This study investigated whether (i) the membrane cofactor protein (MCP or CD46), an additional factor that regulates C3 activation, and (ii) the membrane inhibitor of reactive lysis (MIRL or CD59), a cell surface regulator that acts to prevent formation of the membrane attack complex, are also present in tears, and if so, are functional. Two-site immunoradiometric assays showed that MCP is present in tears at low levels (42 + 8 ng/ml, n = 8) while CD59 is present at levels (222 + 78 ng/ml, n = 14) comparable to those of DAF (325 + 289 ng/ml, n = 12). The concentrations of CD59 (i) were increased two-fold or more in closed eye tears, and (ii) were decreased in reflex tears. Western blotting showed that CD59 protein in tears migrates with an apparent mol. wt similar to membrane CD59 protein. Phenyl-Sepharose adsorption and Triton X-114 partitioning of tear CD59 as well as of tear DAF however, showed that both proteins are devoid of GPI anchors. Assays using cobra venom factor-activated human serum and guinea pig erythrocytes showed that CD59 is functionally active in inhibiting autologous C5b-9-mediated lysis and, under constitutive conditions, accounts for > 85% of the C9 inhibitory activity in tear fluid.

Regulation of monocyte chemoattractant protein (MCP)-1 transcription by interferon-gamma (IFN-gamma) in human astrocytoma cells: postinduction refractory state of the gene, governed by its upstream elements

Monocyte chemoattractant protein (MCP)-1 is expressed by astrocytes in diverse inflammatory states and is a key regulator of monocyte recruitment to the central nervous system (CNS). In the current study, we addressed mechanisms by which transcription of the human MCP-1 gene (hMCP-1) was terminated, after induction by interferon (IFN)-gamma. Our results demonstrated that IFN-gamma-induced transcription of hMCP-1 was followed by a refractory state, during which hMCP-1 was resistant to restimulation by either IFN-gamma or heterologous activators such as TNF-alpha. This refractory state affected the hMCP-1 gene selectively, as other IFN-gamma-inducible genes remained responsive to restimulation. The IFN-gamma-induced hMCP-1 refractory state was governed at the transcriptional level and was sensitive to protein synthesis inhibitors, suggesting a requirement for newly expressed components. A minimal 213 base pair hMCP-1 regulatory element directed both IFN-gamma-mediated transcription and the subsequent refractory state. We previously demonstrated that IFN-gamma treatment resulted in coordinate protein occupancy in vivo of two hMCP-1 promoter elements, a gamma-activated site (GAS) and a GC-rich element. During the refractory state, IFN-gamma treatment failed to induce protection of either the hMCP-1 GAS element or the GC box. These results furnish insight into the expression of hMCP-1 during CNS inflammation and provide the first delineation of an IFN-gamma-induced transcriptional refractory state.

Absent or reduced expression of the caspase 8 gene occurs frequently in neuroblastoma, but not commonly in Ewing sarcoma or rhabdomyosarcoma

PROCEDURE

To clarify whether the caspase 8 gene is involved in the pathogenesis of neuroblastoma (NB), we examined alterations of the caspase 8 gene in 15 NB, seven Ewing sarcoma (ES), and eight rhabdomyosarcoma (RMS) cell lines, using reverse transcription-polymerase chain reaction (RT-PCR) and RT-PCR single-strand conformation polymorphism (SSCP) analyses.

RESULTS

The caspase 8 gene was not expressed in 11 (73%) of 15 NB cell lines, it was absent in only one of seven ES cell lines, but was present in all eight RMS cell lines examined. No mutations were detected in any cell lines examined.

CONCLUSIONS

Inactivation of the caspase 8 gene is considered to be involved in the pathogenesis of NB, but not ES or RMS.

Role of chemokines, neuronal projections, and the blood-brain barrier in the enhancement of cerebral EAE following focal brain damage

The role of focal brain damage as a trigger for autoimmune inflammation in multiple sclerosis (MS) is unclear. In this study we examine mechanisms by which experimental autoimmune encephalomyelitis (EAE) is enhanced by focal brain damage. EAE was produced in Lewis rats by footpad inoculation; focal brain damage, in the form of a cortical cryolesion (cryolesion-EAE), was induced 8 days post-inoculation (d.p.i.). The distribution of inflammation and chemokine production in cryolesion-EAE and EAE-only were compared. Inflammation in the brain, measured by immunocytochemistry for T lymphocytes (W3/13) and microglial activation (MHC class II -OX6), was significantly enhanced in cryolesion-EAE 11-15 d.p.i. (p < 0.01-0.05) but by 20-40 d.p.i., equated with EAE-only. Inflammation in cryolesion-EAE related to breakdown of the blood-brain barrier (BBB) at the site of the cryolesion and also to the corticospinal tracts and thalamus, reflecting the afferent and efferent neuronal connections with the cryolesioned cortex. Semiquantitative RT/PCR dot-blot hybridization assay showed a 6-fold increase in mRNA for specific chemokines in the brain in cryolesion-EAE at 9 d.p.i. (MCP-1) and 11 d.p.i. (MCP-1 and MCP-5) with no significant increase in RANTES, GRO-alpha, or MIP-1alpha. By 14 d.p.i., the levels of MCP-1 and MCP-5 mRNA equated with EAE-only animals. These results suggest that enhancement and location of autoimmune inflammation in the brain following focal cortical injury initially involve chemokines such as the macrophage chemoattractants MCP-1 and MCP-5, and the activities of afferent and efferent neuronal connections with the site of damage. By analogy, similar factors may modulate or reactivate autoimmune inflammation in MS.

Visual target detection paradigm for the study of selective attention

The current protocol can be used to examine selective attention. It has been used to acquire behavioral performance data in neurologically healthy normal control subjects and schizophrenic patients. A modified version, also described here, has been used to acquire functional neuroimaging data in normal subjects using positron emission tomography. Subject response accuracy and reaction times are recorded while subjects detect visual stimuli in either hemifield (left vs. right of a fixation point) or along the vertical meridian (above or below fixation). The lateralized presentation of stimuli permits the study of hemispheric specialization for selective attentional processes. Attentional load is manipulated by presenting larger-sized target stimuli alone (i.e., the letter 'O') or smaller-sized target stimuli surrounded by flanking letters. This protocol report includes a description of subject exclusion criteria, procedural details, relevant experimental conditions and variables, suggestions for data analysis, expected results, and a discussion of the protocol's significance for attentional research along with suggestions for future research.

Nitric oxide induces oxidative stress and apoptosis in neuronal cells

Within the central nervous system and under normal conditions, nitric oxide (NO) is an important physiological signaling molecule. When produced in large excess, NO also displays neurotoxicity. In our previous report, we have demonstrated that the exposure of neuronal cells to NO donors induced apoptotic cell death, while pretreatment with free radical scavengers L-ascorbic acid 2-[3, 4-dihydro-2,5,7,8-tetramethyl-2-(4,8, 12-trimethyltridecyl)-2H-1-benzopyran-6-yl-hydrogen phosphate] potassium salt (EPC-K1) or superoxide dismutase attenuated apoptosis effectively, suggesting that reactive oxygen species (ROS) may be involved in the cascade of events leading to apoptosis. In the present investigation, we directly studied the kinetic generation of ROS in NO-treated neuronal cells by flow cytometry using 2', 7'-dichloro-fluorescein diacetate and dihydrorhodamine 123 as redox-sensitive fluorescence probes. The results indicated that exposure of cerebellar granule cells to the NO donor S-nitroso-N-acetylpenicillamine (SNAP) induced oxidative stress, which was characterized by the accumulation of cytosolic and mitochondrial ROS, the increase in the extracellular hydrogen peroxide level, and the formation of lipid peroxidation products. SNAP treatment also induced apoptotic cell death as confirmed by the formation of cytosolic mono- and oligonucleosomes. Pretreating cells with the novel antioxidant EPC-K1 effectively prevented oxidative stress induced by SNAP, and attenuated cells from apoptosis.

Feedback-controlled negative pressure ventilation in patients with stable severe hypercapnic chronic obstructive pulmonary disease

BACKGROUND

In recent studies, the efficacy of intermittent rest of the inspiratory muscles as an option of treating patients with severe chronic obstructive pulmonary disease (COPD) has become questionable.

OBJECTIVE

The aim of our study was to analyze the effects of feedback-controlled intermittent negative pressure ventilation (INPV) on stable, but severely hypercapnic COPD patients.

METHODS

21 clinically stable, hypercapnic patients with severe COPD underwent INPV with chest shells for 3 weeks, 6 h a day. The INPV sessions were optimized by a visual biofeedback system, which enabled control over the decrease in diaphragmatic activity. Respiratory muscle (RM) function parameters, lung function parameters, blood gases and exercise capacity were analyzed.

RESULTS

In the end, 19 patients concluded INPV treatment. They had PaO(2) of 56.5 +/- 11.8 mm Hg, PaCO(2) of 50.2+/-2.7 mm Hg (mean +/- SD) and FEV(1) of 27.8 +/- 4.3% predicted before treatment. There was no statistically significant change in lung function parameters, RM function parameters, physical performance and level of dyspnea after 3 weeks of INPV.

CONCLUSION

We conclude that intermittent RM rest induced by INPV can relax inspiratory muscles in most patients with stable severe COPD, but fails to improve RM function and exercise capacity.

Mechanisms of apoptosis in rat cerebellar granule cells induced by hydroxyl radicals and the effects of EGb761 and its constituents

In this study investigation is made on whether oxidative stress produced by treatment with hydroxyl radicals can induce apoptosis in rat cerebellar granule cells. The protective effects of Ginkgo biloba extract (EGb761) and its active constituents against apoptosis are also examined. The results show that hydroxyl radicals generated by the Fenton reaction induced apoptosis in cerebellar granule cells, which was associated with the decrease in the Bcl-2 mRNA level and the increase in the protein levels of the transcription factors Fos and Jun. Moreover, hydroxyl radicals induced time-dependent lipid peroxidation in cells and caused the changes in the sulfhydryl group binding sites on the membrane proteins. Hydroxyl radicals may induce apoptosis via different signaling pathways. EGb761 attenuated these changes and its different constituents showed different effects. The total flavonoid component of EGb761 and a mixture of flavonoids and terpenes protected cerebellar granule cells from oxidative damage and apoptosis induced by hydroxyl radicals. Total terpenes of EGb761 did not protect against apoptosis. Flavonoids and terpenes did not show a synergistic effect in this regard.

Shape and size of the corpus callosum in schizophrenia and schizotypal personality disorder

The size and shape of the corpus callosum were assessed on sagittal section magnetic resonance images in 27 patients with schizophrenia, 13 patients with schizotypal personality disorder (SPD), and 30 healthy volunteers. High-resolution 1.2mm axial SPGR images were acquired and resectioned so that the sagittal plane passed through the anterior and posterior commissures and was parallel to the interhemispheric fissure. The corpus callosum and the whole brain were traced on midsagittal section slices of each brain, and the callosum was divided into 30 anteroposterior sectors. Pixel-by-pixel chi-square and thin-plate spline analyses were used to assess between-group shape differences. Size of the corpus callosum was smaller anteriorly in the genu of the corpus callosum and posteriorly in the splenium in schizophrenic patients than in normal controls. The genu of the corpus callosum was larger in SPD patients than in schizophrenic patients or normal controls. The posterior corpus callosum was largest in normal controls, smaller in SPD patients, and smallest in schizophrenic patients. Shape analysis was consistent with these size comparisons, and suggested a downward bowing of the corpus callosum in schizophrenic and SPD patients. SPD patients also had a region of the callosum just posterior to the genu that was narrower than in the other two groups. The decreases in corpus callosal size in schizophrenia varied directly with length of illness, perhaps indicative of a progressive process. The patient-control differences in callosal size and shape are consistent with a hypothesis of decreased connectivity between the left and the right hemispheres in schizophrenia and SPD.

Biphasic and regionally-restricted chemokine expression in the central nervous system in the Theiler's virus model of multiple sclerosis

Intracerebral infection of susceptible strains of mice with Theiler's murine encephalomyelitis virus (TMEV) induces a biphasic disease characterized by acute polioencephalitis followed by chronic demyelination and viral persistence in the spinal cord white matter. There has been limited study of soluble mediators responsible for the initial recruitment of inflammatory cells into the gray matter, and the secondary influx into the white matter during infection with TMEV. We used sensitive and specific RT - PCR/dot blot hybridization assays to quantitate the relative levels of chemokine mRNA in the brains and spinal cords during the acute and chronic phases of TMEV infection in mice susceptible (B10.M, H-2f) and resistant (B10, H-2b) to virus-induced demyelination. TMEV infection resulted in robust expression of mRNA for IP-10, RANTES, and MCP-1, but not GRO-alpha, in brains and spinal cords in both strains of mice within 5 days. By day 21, virus was cleared, inflammation reduced, and expression of all three chemokines subsided to baseline levels in the brains and spinal cords of resistant mice, and the brains of susceptible mice. Chemokine expression was also reduced in the spinal cords of susceptible mice, corresponding to a shift in TMEV replication from the gray to the white matter. During the chronic, demyelinating phase of infection, there was a resurgence in IP-10, RANTES, and MCP-1 mRNA in spinal cords of susceptible B10.M mice. This study demonstrates the coordinated regulation and regionally restricted expression of chemokines in a biphasic disease of the central nervous system and provides greater understanding of the mechanism by which inflammation is established and maintained in the CNS.

Unique chromosome identification and sequence-specific structural analysis with short PNA oligomers

We have extended our earlier work to show that individual 14-20mer peptide nucleic acid probes directed against interspersed alpha-satellite sequences can specifically identify chromosomes. Peptide nucleic acid (PNA) probes were used to detect chromosomal abnormalities and repeat structure in the human genome by fluorescence in situ hybridization (FISH). The hybridization of a single PNA probe species directed against a highly abundant alpha-satellite DNA repeat sequence was sufficient to absolutely identify a chromosome. Selection of highly repetitive or region-specific DNA repeats involved DNA database analysis. Distribution of a specific repeat sequence in human genome was estimated through two means: a computer program "whole genome" approach based on approximately 400 Mb (12%) human genomic sequence. The other method involved directed search for alpha satellite sequences. In total, approximately 240 unique DNA repeat candidates were found. Forty-two PNA probes were designed for screening chromosome-specific probes. Ten chromosome-specific PNA probes for human Chromosomes (Chrs) 1, 2, 7, 9, 11, 17, 18, X, and Y have been identified. Interphase and metaphase results demonstrate that chromosome-specific PNA probes are capable of detecting simple aneuploidies (trisomies) in human. Another set of PNA probes showed distinct banding-like patterns and could be used as sequence-specific stains for chromosome "bar coding". Potential application of PNA probes for investigating repeat structure and function is also discussed.

Caspase 8 is deleted or silenced preferentially in childhood neuroblastomas with amplification of MYCN

Caspase 8 is a cysteine protease regulated in both a death-receptor-dependent and -independent manner during apoptosis. Here, we report that the gene for caspase 8 is frequently inactivated in neuroblastoma, a childhood tumor of the peripheral nervous system. The gene is silenced through DNA methylation as well as through gene deletion. Complete inactivation of CASP8 occurred almost exclusively in neuroblastomas with amplification of the oncogene MYCN. Caspase 8-null neuroblastoma cells were resistant to death receptor- and doxorubicin-mediated apoptosis, deficits that were corrected by programmed expression of the enzyme. Thus, caspase 8 acts as a tumor suppressor in neuroblastomas with amplification of MYCN.

Whole-brain diffusion MR histograms differ between MS subtypes

OBJECTIVE

To determine whether quantitative whole-brain MR diffusion histograms in patients with MS differ from those of normal control subjects.

BACKGROUND

MRI detects macroscopic cerebral lesions in MS, but the white matter lesion burden on MRI correlates imperfectly to clinical disability. Previous reports have further suggested abnormalities in white matter of MS patients with no visible lesions on conventional MRI.

METHODS

A total of 25 subjects (13 with MS [9 relapsing-remitting, 4 secondary progressive] and 12 healthy control subjects) underwent diffusion-weighted echoplanar MRI encompassing the entire brain. The average apparent diffusion coefficient (ADCave, or diffusion trace) was calculated on a pixel-by-pixel basis after segmentation of intracranial space from calvarium and extracranial soft tissues. Whole-brain ADCave histograms were calculated and plotted for statistical comparison.

RESULTS

Mean whole-brain MR ADCave in MS patients was elevated and histograms were shifted to higher values compared with normal control subjects. Mean whole-brain ADCave of secondary progressive patients was shifted to higher values compared with relapsing-remitting patients. Whole-brain ADCave histograms of relapsing-remitting patients showed no significant difference from normal control subjects.

CONCLUSION

Whole-brain MR diffusion histograms may quantitate overall cerebral lesion load in patients with MS and may be able to discern differences between clinical subgroups.