Striatal monoamine neurotransmitters and metabolites in dominantly inherited olivopontocerebellar atrophy.

We measured the levels of the monoamine neurotransmitters and metabolites in striatum of 14 patients with end-stage dominantly inherited olivopontocerebellar atrophy (OPCA). On average, dopamine levels were reduced in putamen (-53%), caudate (-35%), and nucleus accumbens (-31%). However, individual patient values showed a wide variation, indicating that mild to moderate striatal dopamine loss is a common but not constant feature of OPCA. Seven patients had marked putamen dopamine loss (-62% to -81%) but without evidence of correspondingly severe substantia nigra cell damage; this suggests the possibility of a "dying-back" phenomenon in which nerve terminal loss precedes cell body degeneration. Severe substantia nigra cell loss with almost total (-95% to -99%) putamen and caudate dopamine depletion was present in two patients; however, none of the 14 patients had had a clinical diagnosis of parkinsonism or was receiving antiparkinsonian medication. Mean striatal serotonin levels were normal, whereas concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid were elevated by 47% to 63%; this suggests increased activity of raphe dorsalis serotonin neurons innervating the striatum, which might aggravate the functional consequences of the dopamine deficit.     

2F3 Monoclonal Antibody Recognizes the O26 O-Antigen Moiety of the Lipopolysaccharide of Enterohemorrhagic Escherichia coli Strain 4276

Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) organisms are groups of pathogenic strains whose infections are characterized by a typical lesion of enterocyte attachment and effacement. They are involved in enteric diseases both in humans and in animals, and EHEC strains can be responsible for hemolytic uremic syndrome in humans. Previously, it was shown that the 2F3 monoclonal antibody (MAb) is specific for the O26 EHEC and EPEC strains (P. Kerr, H. Ball, B. China, J. Mainil, D. Finlay, D. Pollock, I. Wilson, and D. Mackie, Clin. Diagn. Lab. Immunol. 6:610-614, 1999). As these groups of bacteria play an important role in pathology, the aim of this paper was to characterize the antigen recognized by the 2F3 MAb and its genetic determinant. A genomic locus containing the entire O-antigen gene cluster and half of the colanic acid gene cluster from an O26 EHEC strain was shown to be sufficient for the production of the antigen recognized by the 2F3 MAb in an E. coli DH5α strain. By transposon mutagenesis performed on the recombinant plasmid, all 2F3 enzyme-linked immunosorbent assay-negative mutants had their transposons inserted into the O-antigen gene cluster. The O-antigen gene cluster was also cloned from an O26 EHEC strain into the E. coli DH5α strain, which then produced a positive result with the 2F3 MAb. Further analysis of the type of lipopolysaccharides (smooth or rough) produced by the clones and mutants and of the O antigen of the 2F3-positive clones confirmed that the epitope recognized by the 2F3 MAb is located on the O antigen in the O26 EHEC and EPEC strains and that its genetic determinant is located inside the O-antigen gene cluster.     

An analysis of myeloma plasma cell phenotype using antibodies defined at the IIIrd International Workshop on Human Leucocyte Differentiation Antigens.

Fresh bone marrow from 43 cases of myeloma and three cases of plasma cell leukaemia has been phenotyped both by indirect immune-rosetting and, on fixed cytospin preparations, by indirect immunofluorescence. Both clustered and unclustered B cell associated antibodies from the IIIrd International Workshop on Human Leucocyte Differentiation Antigens were used. The results confirm the lack of many pan-B antigens on the surface of myeloma plasma cells, i.e. CD19-23, 37, 39, w40. Strong surface reactivity is seen with CD38 antibodies and with one CD24 antibody (HB8). Weak reactions are sometimes obtained with CD9, 10 and 45R. On cytospin preparations CD37, 39 and w40 are sometimes weakly positive, and anti-rough endoplasmic reticulum antibodies are always strongly positive. Specific and surface-reacting antiplasma cell antibodies are still lacking.     

Molecular Cloning and Characterization of the Genes Coding for the Highly Immunogenic Cluster of 90-Kilodalton Envelope Proteins from the Chlamydia psittaci Subtype That Causes Abortion in Sheep

Proteins present in the outer membrane of chlamydiae that are involved in mucosal epithelial cell infection must clearly be identified and characterized if we are to understand and modify the pathogenic mechanisms utilized by these organisms. We have identified and isolated a family of four genes encoding putative outer membrane proteins (POMPs), a group of proteins of approximately 90 kDa present in the outer membrane of the subtype of Chlamydia psittaci that causes ovine enzootic abortion (strain S26/3). These proteins, although minor components, are major immunogens, as shown by the immunoblotting of chlamydial outer membrane complexes with postabortion sheep sera, and are therefore potential diagnostic and/or protective antigen candidates. Immunoblotting of the expressed amino- and carboxy-terminal halves of one of the POMPs with postabortion sheep sera showed that the major humoral immune response appeared to be directed solely against the amino-terminal half. This result, in combination with the positive immunofluorescence staining of S26/3-infected cells using POMP-specific (specific to the amino-terminal half of the proteins) monoclonal antibodies, suggests the probable surface localization of the POMPs and, more specifically, the surface exposure of the amino-terminal half of these proteins. The four pomp genes are highly homologous, sharing 82 to 100% similarity with each other (two of the genes are identical). Genes with strong and weak homologies were also detected in C. psittaci avian and feline pneumonitis strains, respectively. No pomp homologs were found in strains of C. trachomatis and C. pneumoniae, but this does not preclude their existence. The absence of homology with various subtypes of C. pecorum, which complicate the diagnosis of the ovine abortion subtype, indicates the possible suitability of the these 90-kDa proteins as serodiagnostic antigens.     

Selecting relevant electrode positions for classification tasks based on the electro-encephalogram

The aim is to describe a general approach to determining important electrode positions when measured electro-encephalogram signals are used for classification. The approach is exemplified in the frame of the brain-computer interface, which crucially depends on the classification of different brain states. To classify two brain states, e.g. planning of movement of right and left index fingers, three different approaches are compared: classification using a physiologically motivated set of four electrodes, a set determined by principal component analysis and electrodes determined by spatial pattern analysis. Spatial pattern analysis enhances the classification rate significantly from 61.3±1.8% (with four electrodes) to 71.8±1.4%, whereas the classification rate using principal component analysis is significantly lower (65.2±1.4%). Most of the 61 electrodes used have no influence on the classification rate, so that, in future experiments, the setup can be simplified drastically to six to eight electrodes without loss of information.     

Expression of the 40 kDa catecholamine regulated protein in the normal and injured rat retina

Catecholamine regulated protein 40 (CRP40) has been shown to be expressed in the central nervous system (CNS) of several mammalian species where it may function in a similar manner to members of the heat shock protein (HSP) family. Immunohistochemical and immunoblotting techniques were utilized to investigate whether CRP40 is expressed in normal rat retinas. In addition, changes in CRP40 expression were studied following optic nerve transection. The immunohistochemical results showed that CRP40 is expressed in the normal rat retina. The protein was found to be highly expressed in the ganglion cell layer (GCL), the inner nuclear layer (INL) and the outer plexiform layer (OPL). In addition, a low level of CRP40 was found in the inner plexiform layer (IPL), and in the inner segment layer (ISL). No expression was found in the outer nuclear layer (ONL) of normal rat retina. The immunoblotting results show that CRP40 expression decreased in a time-dependent fashion after the optic nerve transection. This decrease indicates that the expression of CRP40 is dependent on the neuron's normal physiological state and that it plays an important function in physiological and pathological conditions in the retina.     

Folic acid and vitamin B12 levels in pregnancy and their relation to megaloblastic anaemia

There is a significant fall in the serum folic acid level during pregnancy, reaching its lowest level at term. This is most pronounced in twin pregnancies. A similar but less spectacular fall occurs in the vitamin B₁₂ concentration.     

An Immunohistochemical Study of the Pathology of Fatal Malaria: Evidence for Widespread Endothelial Activation and a Potential Role for Intercellular Adhesion Molecule-1 in Cerebral Sequestration

The sequestration of parasitized erythrocytes in the microvasculature of vital organs is central to the pathogenesis of severe Plasmodium falciparum malaria. This process is mediated by specific interactions between parasite adherence ligands and host receptors on vascular endothelium such as intercellular adhesion molecule-1 (ICAM-1) and CD36. Using immunohistochemistry we have examined the distribution of putative sequestration receptors in different organs from fatal cases of P.falciparum malaria and noninfected controls. Receptor expression and parasite sequestration in the brain were quantified and correlated. Fatal malaria was associated with widespread induction of endothelial activation markers, with significantly higher levels of ICAM-1 and E-selectin expression on vessels in the brain. In contrast, cerebral endothelial CD36 and thrombospondin staining were sparse, with no evidence for increased expression in malaria. There was highly significant co-localization of sequestration with the expression of ICAM-1, CD36, and E-selectin in cerebral vessels but no cellular inflammatory response. These results suggest that these receptors have a role in sequestration in vivo and indicate that systemic endothelial activation is a feature of fatal malaria.