Nicotinamide restricts neural precursor proliferation to enhance catecholaminergic neuronal subtype differentiation from mouse embryonic stem cells

Emerging evidence indicates that a strong relationship exists between brain regenerative therapies and nutrition. Early life nutrition plays an important role during embryonic brain development, and there are clear consequences to an imbalance in nutritional factors on both the production and survival of mature neuronal populations and the infant’s risk of diseases in later life. Our research and that of others suggest that vitamins play a fundamental role in the formation of neurons and their survival. There is a growing body of evidence that nicotinamide, the water-soluble amide form of vitamin B₃, is implicated in the conversion of pluripotent stem cells to clinically relevant cells for regenerative therapies. This study investigated the ability of nicotinamide to promote the development of mature catecholaminergic neuronal populations (associated with Parkinson’s disease) from mouse embryonic stem cells, as well as investigating the underlying mechanisms of nicotinamide’s action. Nicotinamide selectively enhanced the production of tyrosine hydroxylase-expressing neurons and serotonergic neurons from mouse embryonic stem cell cultures (Sox1GFP knock-in 46C cell line). A 5-Ethynyl-2´-deoxyuridine (EdU) assay ascertained that nicotinamide, when added in the initial phase, reduced cell proliferation. Nicotinamide drove tyrosine hydroxylase-expressing neuron differentiation as effectively as an established cocktail of signalling factors, reducing the proliferation of neural progenitors and accelerating neuronal maturation, neurite outgrowth and neurotransmitter expression. These novel findings show that nicotinamide enhanced and enriched catecholaminergic differentiation and inhibited cell proliferation by directing cell cycle arrest in mouse embryonic stem cell cultures, thus driving a critical neural proliferation-to-differentiation switch from neural progenitors to neurons. Further research into the role of vitamin metabolites in embryogenesis will significantly advance cell-based regenerative medicine, and help realize their role as crucial developmental signalling molecules in brain development.

Th17 cells increase in RRMS as well as in SPMS, whereas various other phenotypes of Th17 increase in RRMS only

Background

The nature and extent of inflammation seen in multiple sclerosis (MS) varies throughout the course of the disease. Changes seen in CD4+ T-helper cells in relapsing–remitting (RR) MS and secondary progressive (SP) MS might differ qualitatively and/or quantitatively.

Objective

The objective of this paper is to study the frequencies of all major CD4+ T-helper subtypes – Th17, Th22 and Th1 lineage cells – in relapse, remission and secondary progression alongside CCR6 status, a chemokine receptor involved in migration of these cells into the central nervous system.

Methods

We compared 100 patients (50 RRMS and 50 SPMS) and 50 healthy volunteers and performed flow cytometric analysis of lymphocytes in blood samples.

Results

We demonstrated raised frequencies of various cell types along the Th17 axis; Th17, Th17.1 (IL-17+ interferon gamma+) and dual IL-17+ IL-22+ cells in RRMS. Th22 and CCR6+ Th1 cells (nonclassical Th1) were also increased in RRMS. All these cells were CCR6+. Only Th17 frequencies were elevated in SPMS.

Conclusions

Increased frequencies of Th17 cells are implicated both in RRMS and SPMS. The CCR6 pathway includes Th17, Th22 and Th1 nonclassical cells, of which Th22 and Th1 cells represent the greatest subsets in MS.

Nicotinamide alone accelerates the conversion of mouse embryonic stem cells into mature neuronal populations

Introduction

Vitamin B₃ has been shown to play an important role during embryogenesis. Specifically, there is growing evidence that nicotinamide, the biologically active form of vitamin B₃, plays a critical role as a morphogen in the differentiation of stem cells to mature cell phenotypes, including those of the central nervous system (CNS). Detailed knowledge of the action of small molecules during neuronal differentiation is not only critical for uncovering mechanisms underlying lineage-specification, but also to establish more effective differentiation protocols to obtain clinically relevant cells for regenerative therapies for neurodegenerative conditions such as Huntington’s disease (HD). Thus, this study aimed to investigate the potential of nicotinamide to promote the conversion of stem cells to mature CNS neurons.

Methods

Nicotinamide was applied to differentiating mouse embryonic stem cells (mESC; Sox1GFP knock-in 46C cell line) during their conversion towards a neural fate. Cells were assessed for changes in their proliferation, differentiation and maturation; using immunocytochemistry and morphometric analysis methods.

Results

Results presented indicate that 10 mM nicotinamide, when added at the initial stages of differentiation, promoted accelerated progression of ESCs to a neural lineage in adherent monolayer cultures. By 14 days in vitro (DIV), early exposure to nicotinamide was shown to increase the numbers of differentiated βIII-tubulin-positive neurons. Nicotinamide decreased the proportion of pluripotent stem cells, concomitantly increasing numbers of neural progenitors at 4 DIV. These progenitors then underwent rapid conversion to neurons, observed by a reduction in Sox 1 expression and decreased numbers of neural progenitors in the cultures at 14 DIV. Furthermore, GABAergic neurons generated in the presence of nicotinamide showed increased maturity and complexity of neurites at 14 DIV. Therefore, addition of nicotinamide alone caused an accelerated passage of pluripotent cells through lineage specification and further to non-dividing mature neurons.

Conclusions

Our results show that, within an optimal dose range, nicotinamide is able to singly and selectively direct the conversion of embryonic stem cells to mature neurons, and therefore may be a critical factor for normal brain development, thus supporting previous evidence of the fundamental role of vitamins and their metabolites during early CNS development. In addition, nicotinamide may offer a simple effective supplement to enhance the conversion of stem cells to clinically relevant neurons.

The unidimensional self-efficacy scale for MS (USE-MS): developing a patient based and patient reported outcome

Background:

Self-efficacy concerns the individual’s belief that he or she is capable of performing a certain task and producing a desired effect, i.e. it reflects the person’s perceptions of their capability for specific tasks, as distinct from their actual ability. Self-efficacy has been shown to influence motivation, psychological well-being, adherence with treatment regimes and quality of life in multiple sclerosis and other conditions.

Objective:

To develop a unidimensional scale of MS self-efficacy with robust psychometric properties, suitable for patient self report.

Methods:

A questionnaire pack covering three MS self-efficacy scales, the Dispositional Resilience Scale and demographic data was posted to MS patients from two MS databases. Data underwent Rasch analysis.

Results:

Response rate was 309/600 (51.5%). None of the existing MS self-efficacy scales were unidimensional. A new 12-item scale, created by combining items from our two scales, was shown to fit the Rasch model, was unidimensional, and invariant for gender, education and disease duration.

Conclusion:

The Unidimensional Self-Efficacy scale for MS (USE-MS) provides a simple summated scale for an ordinal estimate of a persons’ self efficacy. A transformation to interval scaling is available for use in the calculation of change scores and effect sizes.

The Multiple Sclerosis Severity Score: associations with MC1R single nucleotide polymorphisms and host response to ultraviolet radiation

BACKGROUND

Multiple sclerosis outcome may be influenced by ultraviolet radiation and vitamin D synthesis, suggesting skin type and genes determining this phenotype are candidates for disability. However, though associations between melanocortin 1 receptor (MC1R) single nucleotide polymorphisms and disability are reported, some data are incompatible with their expected influence on skin type.

OBJECTIVE

Determine which MC1R single nucleotide polymorphisms affect disability and establish if ultraviolet radiation modifies such associations.

METHODS

We studied using linear regression in 525 cases, associations of the Multiple Sclerosis Severity Score (MSSS) with skin type, gender, ultraviolet radiation exposure and six MC1R single nucleotide polymorphisms (rs1805005, rs1805006, rs2228479, rs1805007, rs1805008, rs1805009).

RESULTS

CG(294) with GG(294) genotypes (rs1805009) (coefficient = -1.44, 95% CI -2.30, -0.59, mean MSSS +/- SD = 4.33 +/- 2.87) and AC(84) (rs1805006) (coefficient = 1.62, 95% CI 0.17, 3.06, mean MSSS = 7.62 +/- 2.43) were associated with MSSS. Associations with Asp294His were found in those with skin types 1/2 and 3/4, and cases stratified by ultraviolet radiation exposure. However, they were seen only in cases with a history of childhood sunburn and not in those without sunburn. We found no significant associations between exposure parameters and MSSS.

CONCLUSIONS

Multiple sclerosis outcome is influenced by interactions between host response to ultraviolet radiation and MC1R single nucleotide polymorphisms. The influence of the single nucleotide polymorphisms appears distinct from their association with skin type.

Vitamin D receptor gene polymorphism is associated with reduced disability in multiple sclerosis

Ultraviolet radiation (UVR) may contribute to multiple sclerosis (MS) outcome by a mechanism involving vitamin D and the vitamin D receptor (VDR). In 512 patients with MS duration of 10 or more years, we studied the association of VDR single nucleotide polymorphisms (A/G1229, C/G3444, G/A3944, CC20965, CC30056, F/f30875, C/T48200, T/t65013) with outcome or disability. ff30875 frequency was lower in cases with EDSS ≥ 6.0 than with scores < 6.0 (odds ratio = 0.38, 95% CI = 0.20–0.70). The association of ff30875 with outcome was not mediated by cumulative exposure to UVR as assessed by questionnaire; low exposure (odds ratio = 0.42, 95% CI = 0.14–1.34) and high exposure (odds ratio = 0.34, 95% CI = 0.16–0.73).

Polymorphisms of the cannabinoid 1 receptor gene and cognitive impairment in multiple sclerosis

Cognitive impairment occurs in 45—65% of multiple sclerosis (MS) patients. The cannabinoid system may potentially be neuroprotective in MS. We examined the relationship between polymorphisms of the CNR1 gene and neuropsychological outcome in MS using a test and confirmatory sample of patients. One hundred and ninety-four MS patients were assessed over five key areas of neuropsychological function, which are most commonly impaired in MS. The first 97 patients formed the test sample. A further confirmatory sample of 97 patients was used to test association found in the test sample. The schedule included: Wisconsin card sorting test 64 version, Rey auditory verbal learning task immediate and delayed scores, controlled oral word association task, judgement of line orientation and symbol digit modalities task. Three single nucleotide polymorphisms (SNPs) were typed within the CNR1 gene.

For the overall neuropsychological assessment score we used a multiple linear regression model with selected covariates to show that subjects with the AA genotype of the SNP RS1049353 were more impaired (mean -2.47, SD 5.75, P = 0.008, Bonferroni corrected P = 0.024) than the other subjects (mean 0.24, SD 4.24). This was not confirmed when the association was retested in the confirmatory sample.

No associations were identified between these CNR1 variants and cognitive impairment in MS. Multiple Sclerosis 2008; 14: 177—182. http://msj.sagepub.com

A medical overview of encephalitis

Encephalitis is uncommon but is a neurological emergency which must be considered in a patient presenting with altered consciousness. Encephalitis is a diffuse inflammatory process of the brain parenchyma associated with evidence of brain dysfunction. The presentation of encephalitis can be acute or chronic. The aetiology of encephalitis can be broadly divided into two major subtypes. (1) Infection-related encephalitis which is a direct consequence of pathogenic viral, bacterial or parasitic agents. Herpes simplex virus (HSV) and varicella-zoster virus (VZV) are the most common cause of acute infectious encephalitis. (2) Autoimmune-mediated encephalitis which is mediated by an aberrant immune response. This can be triggered by a recent viral infection or vaccination. An example of this would be acute disseminated encephalitis (ADEM). This article will focus on the medical management of acute encephalitis. This will involve an extensive overview of the literature reviewing the diagnosis, investigation and treatment of acute viral encephalitis, ADEM and acute haemorrhagic leukoencephalopathy (AHLE). Encephalitis can also present chronically, and some of the different types of chronic encephalitis will be discussed.

Studies of associations between disability in multiple sclerosis, skin type, gender and ultraviolet radiation

Recent studies suggest ultraviolet radiation (UVR)/vitamin D is protective against the development of multiple sclerosis (MS). We determined if outcome in MS is associated with the surrogate for host pigmentation, skin type, and parameters of UVR exposure. We used a validated questionnaire to determine skin type and UVR exposure during childhood (0-16 years), and early adult life (17-40 years), in 448 Caucasians with MS. Outcome was assessed using the Kurtzke Expanded Disability Status Score (EDSS) and Multiple Sclerosis Severity Scale (MSSS). We studied the association of skin type and exposure with dichotomized values of EDSS (< and ≥6) and MSSS (continuous variable) using logistic and linear regression analyses, respectively. Sex, onset age and MS duration were significantly associated with outcome in all patients. In 169 females with established disease (≥10 years), sun sensitive skin types 1 and 2 were associated with reduced risk of EDSS ≥6 (odds ratio =0.50; 95% CI = 0.26-0.97), and higher MSSS values (coefficient = -0.86; 95% CI = -1.67 to -0.05). Parameters of UVR exposure were not significantly associated with outcome. These preliminary data show an association between skin type and disability in female MS patients. They are compatible with independent studies suggesting that exposure mediates MS pathogenesis via vitamin D. Further studies are required to properly assess these potentially important findings. Multiple Sclerosis 2007; 13: 369-375. http://msj.sagepub.com

APOE epsilon variation in multiple sclerosis susceptibility and disease severity: some answers

BACKGROUND

Previous studies have examined the role of APOE variation in multiple sclerosis (MS), but have lacked the statistical power to detect modest genetic influences on risk and disease severity. The meta- and pooled analyses presented here utilize the largest collection, to date, of MS cases, controls, and families genotyped for the APOE epsilon polymorphism.

METHODS

Studies of MS and APOE were identified by searches of PubMed, Biosis, Web of Science, Cochrane Review, and Embase. When possible, authors were contacted for individual genotype data. Meta-analyses of MS case-control data and family-based analyses were performed to assess the association of APOE epsilon genotype with disease risk. Pooled analyses of MS cases were also performed to assess the influence of APOE epsilon genotype on disease severity.

RESULTS

A total of 22 studies (3,299 MS cases and 2,532 controls) were available for meta-analysis. No effect of epsilon2 or epsilon4 status on MS risk was observed (summary OR 1.14, 95% CI 0.96-1.34 and OR 0.89, 95% CI 0.78-1.01). Results obtained from analyses of APOE genotypes in 1,279 MS families were also negative (p = 0.61). Finally, results from pooled analyses of 4,048 MS cases also argue strongly that APOE epsilon status does not distinguish a relapsing-remitting from primary progressive disease course, or influence disease severity, as measured by the Expanded Disability Status Scale and disease duration.

CONCLUSION

Overall, these findings do not support a role for APOE in multiple sclerosis, and underscore the importance of using large sample sizes to detect modest genetic effects, particularly in studies of genotype-phenotype relationships.

Novel polymorphism in the promoter region of the human nerve growth-factor gene

We describe a novel T to C transition at position -198 from the transcription start of the human nerve growth-factor (NGF) gene. In British Caucasoid healthy control group that we have genotyped, T and C allele frequencies are 0.633 and 0.367, respectively. This polymorphism affects vitamin D receptor (VDR) binding to its motif in the NGF promoter.

Susceptibility and outcome in MS: Associations with polymorphisms in pigmentation-related genes

Multiple sclerosis (MS) risk is determined by environment and genes. The authors investigated in 419 cases and 422 controls if polymorphism in the vitamin D receptor (VDR), melanocortin-1 receptor (MC1R), and tyrosinase (TYR) genes is linked with MS risk and outcome. VDR ff was associated with reduced (odds ratio [OR] = 0.59) and MC1R His294-encoding alleles with increased (OR = 2.21) risk. MC1R Glu84/Glu84 was linked with disability (OR = 5.65). These preliminary data suggest a role for these genes in MS pathogenesis.

Association of protein kinase C alpha (PRKCA) gene with multiple sclerosis in a UK population

Twin, family and adoption studies suggest that susceptibility to multiple sclerosis is substantially mediated by genetic factors. Linkage to human chromosome 17q, homologous to a locus linked to experimental animal models of multiple sclerosis, has been widely replicated and the region likely to harbour a multiple sclerosis susceptibility gene has recently been refined to a 2.5 Mb region of 17q22-24. The candidate multiple sclerosis susceptibility gene, protein kinase C alpha (PRKCA), maps within this interval and association with 35 single-nucleotide polymorphism (SNP) markers, spanning the gene with a median spacing of 7.8 kb, was tested using a case-control approach. Single-marker genotype and estimated haplotype frequencies were compared in UK unrelated cases with multiple sclerosis (n = 184) and healthy controls (n = 340) in order to investigate association with susceptibility to disease. A haplotype of two SNPs mapping to the proximal region of the gene showed evidence for association with susceptibility (Bonferroni-corrected P value = 1.1 x 10(-5)). These findings suggest that further investigation of the PRKCA gene is warranted, particularly in cohorts with evidence of linkage to 17q22. Most of the SNPs investigated in this study were intronic and screening to identify disease-associated functional mutations is now required. Our results suggest that the promoter and proximal gene region should be not only included but prioritized in any screening strategy.

Does trauma trigger multiple sclerosis? 2: A medicolegal view

Set against the scientific debate in multiple sclerosis are a number of medicolegal cases in which the scientific evidence has been examined in the context of specific events. It is instructive to understand something of the legal approach to cause and association, and to consider this in relation to individual cases.

Does trauma trigger multiple sclerosis? 1: A controversy

The potential role of trauma in the development of multiple sclerosis is important but controversial. Patients commonly ask about this and it has important medicolegal ramifications. In addressing such issues this article will consider both physical and psychological trauma, examine pathogenic mechanisms, and discuss the evidence for and against a relationship.

Interleukin 1 genotypes in multiple sclerosis and relationship to disease severity

We studied the association between clinical outcome in MS and allelic variants single nucleotide polymorphisms (SNPs) of interleukin-1alpha (IL-1alpha), IL-1beta and a variable number tandem repeat (VNTR) in IL-1 receptor antagonist (IL-1RN). A total of 377 patients with MS were studied. Significant associations between IL-1 genotypes and clinical outcome were found using logistic regression after correction for gender, onset age and disease duration. The same trends were subsequently demonstrated in a second independent group of 67 primary progressive patients. Our results suggest that genetically determined immunomodulation mediated by IL-1 influences long-term prognosis in multiple sclerosis (MS).

HLA-DRB1 and disease outcome in multiple sclerosis

The association between susceptibility to multiple sclerosis (MS) and the class II MHC allele HLA-DRB1*15 is well established although a possible relationship between this allele and outcome in MS is less clear. HLA-DRB1 typing was performed on 375 unrelated white patients with clinically definite MS and on 367 healthy controls. Putative associations of the gene with outcome were examined by dividing patients into two groups: those with an EDSS of 0-5.5 (mild/moderate disease) and those with an EDSS of 6-10 (severe disease). In order to minimise the effects of disease variability patients with a disease duration of at least 10 years or 15 years were examined. As subsidiary HLA-DRB1*03 and HLA-DRB1*04 associations have been previously reported, the effect of these alleles was also examined. As expected, HLA-DRB1*15 was found more frequently in patients than in controls (P < 0.000001). HLA-DRB1*15 positive patients had a significantly earlier age at onset than HLA-DRB1*15 negative patients. No significant associations were noted between HLA-DRB1*15 and outcome in the total patient group or in patients with a disease duration of 10 years or longer. In patients with a disease duration of at least 15 years HLA-DRB1*15 negative status was associated with a worse prognosis, although this did not remain significant after correction for multiple testing. It is thus likely that the contribution of HLA in MS is primarily towards onset and initial triggering mechanisms rather than influencing disease progression, chronicity and severity.

Correlation of MRI lesions with visual psychophysical deficit in secondary progressive multiple sclerosis

The aim of this work was, first, to clarify the nature of the relationship between the sensory deficit in the demyelinated visual pathway and morphological changes revealed by MRI and, secondly, to test whether there was a preferential effect of demyelination for either the magnocellular or parvocellular pathway in established multiple sclerosis. Twenty-four patients with secondary progressive multiple sclerosis were studied psychophysically and by MRI of the optic nerve and brain. MRI was performed with a Phillips (0.5T) scanner. Visual pathway MRI lesion load was evaluated independently using the total optic nerve lesion length and lesion area seen on STIR (short inversion time inversion recovery) images of the optic nerve and the total post-chiasmal lesion area on T(1)-, T(2)- and proton-density-weighted images of the brain. Psychophysical tests determined 75%-seeing thresholds for horizontal gratings consisting of isoluminant red and green sinusoids of the same spatial frequency combined out-of-phase for preferential stimulation of the parvocellular system and in-phase for preferential stimulation of the magnocellular system. It was found that, in this group of patients, visual psychophysical loss was significantly correlated with lesion area seen on proton density MRI sequences of the post-chiasmal visual pathway, and that the parvocellular pathway was more affected than the magnocellular pathway, especially at lower spatial frequencies.

Glutathione S-transferase polymorphisms in MS: their relationship to disability

BACKGROUND

Oxidative stress has been implicated in inflammatory demyelination. The glutathione S-transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress. Certain GST loci are polymorphic, demonstrating alleles that are null (GSTM1/GSTT1), encode low activity variants (GSTP1), or are associated with variable inducibility (GSTM3).

OBJECTIVES

To investigate the association between clinical outcome in MS and allelic variants of GSTM1, GSTM3, GSTT1, and GSTP1.

METHODS

Four hundred patients with clinically definite MS were studied. Disability was measured using the Kurtzke Expanded Disability Status Scale (EDSS). Disability was graded as mild (EDSS 0-4), moderate (4.5-5.5), or severe (EDSS 6-10). PCR-based genotyping was performed using DNA extracted from lymphocytes. Significant associations between GST genotypes and clinical outcome were corrected for gender, onset age, and disease duration using logistic regression.

RESULTS

We found that the GSTM3 AA genotype was associated with severe disability in patients with a disease duration of more than 10 years (p = 0.027, n = 177, OR = 2.4, 95% CI = 1.1-5.0). Homozygosity for both GSTM1*0 and GSTP1*Ile105 containing allele was associated with severe disability in patients with a disease duration greater than 10 years (p = 0.022, n = 179, OR = 5.0, 95% CI = 1.3-19.8).

CONCLUSIONS

Our results suggest that long-term prognosis in MS is influenced by a genetically determined ability to remove the toxic products of oxidative stress.

Polymorphisms of apolipoprotein E; outcome and susceptibility in multiple sclerosis

Allelic variants of the apolipoprotein E (APOE) gene influence the course of several neurological diseases. In multiple sclerosis the concentration of APOE in cerebrospinal fluid and its intrathecal synthesis is reduced. Specific isoforms of APOE may also be important and it has been suggested that possession of the epsilon4 allele may be associated with a more aggressive disease process. These data prompted us to re-examine, in a large group of patients with multiple sclerosis, the proposal that allelism in the apolipoprotein gene influences disease course. Genotypes were determined in a well-defined group of 370 unrelated Caucasians with clinically definite multiple sclerosis and in 159 healthy controls. Age at onset, sex, disease duration, disease subtype were recorded. Disability was measured using the Kurtzke expanded disability status score in patients with a disease duration of 10 years or greater. There was no significant difference in APOE allele or genotype frequencies between patients and controls, between disease subtypes or between genders. APOE genotype did not significantly influence age of onset, and no significant relationship between genotype, allele frequency and disease severity was found. This study suggests that individual APOE alleles or genotypes do not determine disease susceptibility or the clinical course of multiple sclerosis.

The effect of anti-alpha4 integrin antibody on brain lesion activity in MS. The UK Antegren Study Group

OBJECTIVE

To determine the effect of humanized monoclonal antibody against alpha4 integrin (reactive with alpha4beta1 integrin or very-late antigen-4) on MRI lesion activity in MS.

METHODS

A randomized, double-blind, placebo-controlled trial in 72 patients with active relapsing-remitting and secondary progressive MS was performed. Each patient received two IV infusions of anti-alpha4 integrin antibody (natalizumab; Antegren) or placebo 4 weeks apart and was followed up for 24 weeks with serial MRI and clinical assessment.

RESULTS

The treated group exhibited significantly fewer new active lesions (mean 1.8 versus 3.6 per patient) and new enhancing lesions (mean 1.6 versus 3.3 per patient) than the placebo group over the first 12 weeks. There was no significant difference in the number of new active or new enhancing lesions in the second 12 weeks of the study. The number of baseline-enhancing lesions (i.e., lesions that enhanced on the baseline scan) that continued to enhance 4 weeks following the first treatment was not significantly different between the two groups. The number of patients with acute MS exacerbations was not significantly different in the two groups during the first 12 weeks (9 in the treated group versus 10 in placebo) but was higher in the treatment group in the second 12 weeks (14 versus 3; p = 0.005). The study was not, however, designed to look definitively at the effect of treatment on relapse rate. Treatment was well tolerated.

CONCLUSIONS

Short-term treatment with monoclonal antibody against alpha4 integrin results in a significant reduction in the number of new active lesions on MRI. Further studies will be required to determine the longer term effect of this treatment on MRI and clinical outcomes.

MRI of optic nerve and postchiasmal visual pathways and visual evoked potentials in secondary progressive multiple sclerosis

We studied the relationship between abnormalities shown by MRI and functional disturbances in the visual pathway as assessed by the visual evoked potential (VEP) in 25 patients with established multiple sclerosis (MS); only 4 of whom had a history of acute optic neuritis. Optic nerve MRI was abnormal in 19 (76%) and is thus useful in detecting subclinical disease. Optic nerve total lesion length and area on the STIR sequence was found to correlate significantly with prolongation of the VEP latency. This may reflect a predominantly demyelinating rather than inflammatory origin for the signal change in the optic nerve.

Effects of intravenous methylprednisolone on outcome in MRI-based prognostic subgroups in acute optic neuritis

Treatment of acute optic neuritis with steroids has been shown to hasten visual recovery without affecting the final degree of recovery. However, MRI-clinical studies indicate that patients with long optic nerve lesions, particularly those that involve the nerve within the optic canal, may have a worse prognosis for recovery of vision. Partly because such lesions could lead to swelling and subsequent ischemic optic nerve damage, steroids could have a selective beneficial effect on this subgroup of patients. The present randomized trial was designed to test this possibility. Sixty-six patients with acute optic neuritis received IV saline or IV methylprednisolone. The clinical, psychophysical, electrophysiologic, and MRI outcomes were assessed after 6 months. Patients with short lesions presented earlier than those with long lesions (involving three or more 5-mm-thick slices of any part of the optic nerve, as well as its intracanalicular portion), and lesion length was significantly less in patients presenting within a week of onset of symptoms. Lesions also tended to lengthen during follow-up in individual patients. Treatment did not limit lesion length in either the long or short lesion subgroup and had no significant effect on final visual outcome. We conclude that steroids do not improve visual outcome or lesion length in patients with acute optic neuritis.

Biodiversity of stream insects: variation at local, basin, and regional scales

We review the major conceptual developments that have occurred over the last 50 years concerning the factors that influence insect biodiversity in streams and examine how well empirical descriptions and theory match. Stream insects appear to respond to both spatial and temporal variation in physical heterogeneity. At all spatial scales, the data largely support the idea that physical complexity promotes biological richness, although exceptions to this relationship were found. These exceptions may be related to how we measure habitat complexity at finer spatial scales and to factors that influence regional richness, such as biogeographic history, at broader spatial scales. However, the degree to which local stream insect assemblages are influenced by regional processes is largely unknown.

Anti-ganglioside antibodies in patients with rheumatoid arthritis complicated by peripheral neuropathy

Gangliosides are a diverse class of glycolipids found in the plasma membrane of mammalian cells and are particularly abundant in cells of the nervous system. Serum antibodies to gangliosides have been detected in various neurological disorders with some evidence that they play a pathogenic role. In this study, we have investigated whether anti-ganglioside antibodies were elevated in a group of patients with rheumatoid arthritis (RA) who developed peripheral neuropathy (PN). An ELISA technique was used to test sera from 28 patients with RA and PN. 38 RA patients without PN and 20 normal controls for the presence of IgG and IgM anti-GM1 and sulphatide antibodies. The patients with RA and PN had higher pain scores (P < 0.005), more extra-articular features (P < 0.05), higher erosive scores (P < 0.0001), lower haemoglobin (P < 0.005), higher ESR (P < 0.001) and were more often on disease-modifying drugs (P < 0.05). Twelve RA patients with PN (43%), but only two RA controls (5%), had positive titres against one or more gangliosides (P < 0.001). The neurologic disability score (NDS) correlated with RA duration (P < 0.05), and with levels of IgM anti-GM1 (P < 0.001) and IgM anti-sulphatide (P < 0.05) antibodies. We conclude that PN is more common in patients with severe rheumatoid disease, and a significant proportion have elevated levels of anti-ganglioside antibodies.

Cortical plaques visualised by fluid-attenuated inversion recovery imaging in relapsing multiple sclerosis

Fluid-attenuated inversion recovery (FLAIR) imaging with prolonged inversion times allows generation of highly T2-weighted images of the brain with suppression of cerebrospinal fluid signal. Such sequences result in high lesion contrast and allow visualisation of abnormalities not seen with conventional T2-weighted spin-echo sequences. We used FLAIR sequences, proton density (PD) and standard T2-weighted images to examine lesion number and distribution in ten patients with clinically definite relapsing multiple sclerosis (MS). We also studied the extent and distribution of blood-brain-barrier breakdown by gadolinium-enhanced T1-weighted images. FLAIR sequences proved feasible both in terms of acquisition time and image quality using a 0.5 T imager. FLAIR imaging allowed identification of 45% more high-signal lesions than T2-weighted or PD images in the 10 patients. In particular, 60% more lesions within the cortex and at the grey-white interface were identified. Cortical lesions, none of which enhanced following gadolinium-DTPA injection, were present in seven of the ten patients studied. Of all lesions identified, 8% were cortical. FLAIR sequences are more sensitive to cortical and subcortical lesions in patients with active demyelination.

Serial proton magnetic resonance spectroscopy in acute multiple sclerosis lesions

Serial proton magnetic resonance spectroscopy (MRS), was carried out at 1-2 monthly intervals on eight patients with multiple sclerosis who presented with evidence of a large acute cerebral white matter lesion. An MRS was obtained from acute lesions (volumes of interest 4-12 ml), which at presentation showed gadolinium-diethylenetriamine penta-acetic acid enhancement, and from similar volumes of normal appearing white matter lateral to the lesion and nearer the scalp. Follow-up ranged from 4 to 9 months (mean 6 months). Short echo spectra from acute enhancing lesions invariably showed the presence of large resonances at 0.9 and 1.3 p.p.m. compared with normal appearing white matter and healthy age matched controls, indicating that these peaks were not the result of voxel contamination from scalp fat. These resonances, which probably represent lipid products of myelin breakdown, were detected in lesions which had been enhancing for < 1 month and remained elevated for a mean of 5 months (range 4-8 months). The results provide evidence that short echo proton MRS can detect myelin breakdown products and that myelin breakdown occurs during the initial inflammatory stage of lesion development. The ratio of N-acetylaspartate (NAA) (a neuronal marker) relative to creatine was reduced in acute lesions and in normal appearing white matter. In six of the lesions studied there was, however, a subsequent rise in the NAA/creatine ratio indicating that axonal loss is not the only mechanism of reduction in the NAA/creatine ratio.

The proton NMR spectrum in acute EAE: the significance of the change in the Cho:Cr ratio

We have studied by nuclear magnetic resonance spectroscopy the evolution of the proton spectral changes in acute experimental allergic encephalomyelitis. We found an in vivo elevation in the ratio between the peaks assigned to "choline containing compounds" (Cho) and creatine plus phosphocreatine (Cr). This was associated with an increase in choline, betaine, and phosphorylcholine (PC) as well as a reduction in N-acetylaspartate (NAA), aspartate, N-acetylaspartatylglutamate and inositol in vitro. Histological examination revealed inflammation with no evidence of demyelination or neuronal loss. We conclude that the increase in the ratio of Cho:Cr was due to an increase in the concentrations of PC, betaine, and choline in association with inflammation, and not as others have suggested, with demyelination. The reported reduction in NAA may be due to dysfunction of neurones rather than their loss.

Pathological findings correlated with MRI in HIV infection

MRI forms an important part of the assessment of patients with HIV-related disease presenting with cerebral symptoms. Eleven formalin-fixed brains were studied at 0.5 T using T2- and T1-weighted sequences. In two cases of progressive multifocal leucoencephalopathy and one case each of toxoplasmosis and lymphoma, the extent of white matter abnormality seen on MRI corresponded broadly with that on pathological examination. In general, however, histological changes were more frequent than lesions on MRI. Cases in which abnormalities were not seen with standard MRI included those with multiple tuberculous granulomata, multinucleate giant cells, microglial nodules, perivascular cuffing and cytomegalovirus inclusions. A common finding on MRI was punctate or patchy high signal in the basal ganglia on T2-weighted scans, seen in six cases. Corresponding histological changes included calcification of vessels with widened perivascular spaces, and mineralised neurones.

Metabolically dependent blood-brain barrier breakdown in chronic relapsing experimental allergic encephalomyelitis

We have studied chronic relapsing experimental allergic encephalomyelitis (CREAE), a model of immune-mediated demyelination, using gadolinium (Gd)-enhanced magnetic resonance imaging in vivo and the blood-brain barrier (BBB) markers, lanthanum nitrate and Gd nitrate, histologically. In regions of the spinal cord showing Gd enhancement, there was evidence for vesicular transport as a mechanism of BBB breakdown in CREAE, shown by an increased number of endothelial vesicles containing lanthanide (lanthanum or Gd, whichever had been perfused) and deposition of tracer in the perivascular space; tight interendothelial junctions remained intact. Prior perfusion with 2,4-dinitrophenol, a metabolic inhibitor, suppressed the appearance of endothelial vesicles containing lanthanide and tracer in the perivascular space. We conclude that an important contribution to BBB breakdown in CREAE is mediated by a metabolic change in the endothelial cells associated with increased vesicular transport.

In vivo T1 values from guinea pig brain depend on body temperature

T1 and T2 values were calculated from guinea pig brain in vivo at 0.5 T. T1 values showed significant dependence on body temperature, but the effect varied significantly from animal to animal and from one tissue type to another. Mean dependencies were 8.2 ms/degrees C for corpus callosum, 14.7 ms/degrees C for gray matter, and 21.5 ms/degrees C for hemispheric white matter (1.7, 2.6, and 4.5%/degrees C, respectively), all with respect to core temperature. These findings suggest that body temperature monitoring and control may be needed when sensitive measurements of T1 are being made. There was evidence for regulation of brain temperature within the hyperthermic range of body temperature.

A resistant case of neurocystercercosis

A case of neurocystercercosis resistant to treatment with repeated courses of albendazole and praziquantel (even in combination), leading to deterioration in clinical condition is described.

Patterns of blood-brain barrier breakdown in inflammatory demyelination

The evolution of the changes in the blood-brain barrier (BBB) in chronic relapsing experimental allergic encephalomyelitis (CREAE), a model of immune-mediated demyelination, has been studied by magnetic resonance imaging (MRI); gadolinium-DTPA (Gd-DTPA) was used to detect BBB breakdown by both quantitative and qualitative techniques. Animals with acute EAE were examined for comparison. In animals with CREAE an approximately linear relationship was found between the mean number of lesions enhancing with Gd-DTPA seen per MRI slice and the severity of clinical disability at relapse. In addition, a direct relationship was seen between the duration of clinical relapse and the duration of enhancement with Gd-DTPA for lesions associated with the relapse. Lesions studied in animals having entered a progressive phase of disease showed the most sustained BBB breakdown. These observations suggest that BBB breakdown is important in the development of clinical signs in inflammatory demyelination. In CREAE, areas of focal enhancement with Gd-DTPA could usually be clearly defined at a time of clinical relapse. In slices free of focal lesions, no abnormal Gd-DTPA leakage could be detected using a quantitative method. In contrast, in acute EAE no focal lesions were visible, but significant leakage was detected by measurement. No change was found in T2 relaxation times in CREAE or acute EAE. The pattern of BBB breakdown in inflammatory demyelination evolves from a diffuse shortlived disturbance in acute EAE to a more focal and prolonged breakdown in animals with chronic relapsing and progressive disease. The broad similarities in the pattern of BBB breakdown seen in CREAE and multiple sclerosis support the hypothesis that the initial vascular changes in the human disease are due to inflammation which could be mediated immunologically.

Histopathology of multiple sclerosis lesions detected by magnetic resonance imaging in unfixed postmortem central nervous system tissue

Postmortem unfixed whole brains from 17 multiple sclerosis and 6 control cases were examined by magnetic resonance imaging (MRI) using a T2-weighted spin echo sequence and histology to determine the relationship between areas of abnormal MRI signal and underlying pathological change. In group 1, small MRI lesions and correspondingly small plaques, most of which were chronic, were detected histologically in 5 brains. In 4 brains there were more extensive areas of both abnormal signal and histological plaques which were more often active (group 2). However, in a further 5 brains extensive MRI abnormalities were observed when only small periventricular plaques were present histologically (group 3). Lesions in the hindbrain and cerebral grey matter were infrequently observed by MRI. The extensive MRI abnormalities seen in areas in which only small histological plaques were found may be the result of vascular permeability changes in the normal-appearing white matter surrounding plaques.

Duration and selectivity of blood-brain barrier breakdown in chronic relapsing experimental allergic encephalomyelitis studied by gadolinium-DTPA and protein markers

Gadolinium-DTPA (Gd-DTPA) enhancement seen with magnetic resonance imaging in chronic relapsing experimental allergic encephalomyelitis (CREAE) corresponded with sites of blood-brain barrier breakdown judged by traditional markers in areas of inflammatory demyelination. Duration of Gd-DTPA leakage for individual lesions in CREAE varied from 5 days to more than 5 wks. By contrast, in acute EAE leakage was of shorter duration (always less than 5 days). Selective enhancement was observed in CREAE lesions using Gd-protein markers. Gd-albumin enhancement was not always seen in areas of leakage of the smaller molecular weight compound Gd-DTPA. The addition of immunoglobulin to the gadolinium complex led to enhancement of lesions not seen with Gd-albumin alone. From the similarities between the histology and the patterns of Gd-enhancement in CREAE and multiple sclerosis, it is probable that Gd-enhancement reflects active inflammation (with or without demyelination) in the human disease.

Pathological findings correlated with magnetic resonance imaging in subcortical arteriosclerotic encephalopathy (Binswanger's disease)

Formalin-fixed brain slices from four cases of subcortical arteriosclerotic encephalopathy in which a firm diagnosis could be made both clinically and pathologically have been studied by magnetic resonance imaging (MRI). The slices were subsequently embedded in paraffin-wax or celloidin and sections were cut in the same plane as the MRI slices. There was a good correlation between the extent and severity of the abnormal MRI signal and the pathological changes. Areas of diffuse MRI abnormality corresponded with areas of axonal and myelin loss with gliosis, and small "lacune"-like lesions corresponded with lacunar infarcts histologically. Sparing of the subcortical U-fibres was seen histologically and on MRI. The abnormal signal probably originates from increased tissue water attributable to gliosis and an expanded extracellular space.

Subarachnoid hemorrhage from spinal tumor (in the absence of spinal symptoms or signs)

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