T- and B-cell responses to myelin oligodendrocyte glycoprotein in experimental autoimmune encephalomyelitis and multiple sclerosis

The identification of myelin oligodendrocyte glycoprotein (MOG) as a target for autoantibody-mediated demyelination in experimental autoimmune encephalomyelitis (EAE) resulted in the re-evaluation of the role of B cell responses to myelin autoantigens in the immunopathogenesis of multiple sclerosis. MOG is a central nervous system specific myelin glycoprotein that is expressed preferentially on the outermost surface of the myelin sheath. Although MOG is only a minor component of CNS myelin it is highly immunogenic, inducing severe EAE in both rodents and primates. In rat and marmoset models of MOG-induced EAE demyelination is antibody-dependent and reproduces the immunopathology seen in many cases of MS. In contrast, in mice inflammation in the CNS can result in demyelination in the absence of a MOG-specific B cell response, although if present this will enhance disease severity and demyelination. Clinical studies indicate that autoimmune responses to MOG are enhanced in many CNS diseases and implicate MOG-specific B cell responses in the immunopathogenesis of multiple sclerosis. This review provides a summary of our current understanding of MOG as a target autoantigen in EAE and MS, and addresses the crucial question as to how immune tolerance to MOG may be maintained in the healthy individual.

MR imaging findings in granular cell tumor of the neurohypophysis: a difficult preoperative diagnosis

Granular cell tumor is a rare neoplasm arising within the neurohypophysis. We describe the MR imaging findings in two symptomatic patients. In one patient with history of panhypopituitarism, MR images showed a large sellar and suprasellar mass. The other patient presented with acute loss of vision in her left eye, and MR images showed a suprasellar mass with compression of the optic chiasm.

Myoclonus of peripheral origin: case secondary to a digital nerve lesion

We present a patient with myoclonus of the left hand appearing 1 month after surgical correction of a stenosing tenosynovitis of the thumb. An extensive fibrosis of the external palmar digital nerve was shown, and the successful liberation of this median nerve terminal branch completely and rapidly eliminated the movement disorder.

What test should I use?

Appropriate assessment of Hispanic children requires clinicians to have knowledge of the cultural and linguistic factors that influence the communication skills of these children. This knowledge base includes an understanding of variations in the social and linguistic characteristics of Hispanic subgroups. Knowledge of these characteristics provides clinicians with the framework necessary to conduct less biased assessments. Clinicians possessing this framework would be able to conduct assessments that take into consideration the child's social ecology and the impact of dialect, first and second language acquisition, and language loss on the child's communication skills.

Directed proteomics identifies a plant-specific protein rapidly phosphorylated in response to bacterial and fungal elicitors

The perception of microbial signal molecules is part of the strategy evolved by plants to survive attacks by potential pathogens. To gain a more complete understanding of the early signaling events involved in these responses, we used radioactive orthophosphate to pulse-label suspension-cultured cells of Arabidopsis in conjunction with two-dimensional gel electrophoresis and mass spectrometry to identify proteins that are phosphorylated rapidly in response to bacterial and fungal elicitors. One of these proteins, AtPhos43, and related proteins in tomato and rice, are phosphorylated within minutes after treatment with flagellin or chitin fragments. By measuring (32)P incorporation into AtPhos43 immunoprecipitated from extracts of elicitor-treated hormone and defense-response mutants, we found that phosphorylation of AtPhos43 after flagellin treatment but not chitin treatment is dependent on FLS2, a receptor-like kinase involved in flagellin perception. Induction by both elicitors is not dependent on salicylic acid or EDS1, a putative lipase involved in defense signaling.

Sense- and antisense-mediated gene silencing in tobacco is inhibited by the same viral suppressors and is associated with accumulation of small RNAs

Antisense-mediated gene silencing (ASGS) and posttranscriptional gene silencing (PTGS) with sense transgenes markedly reduce the steady-state mRNA levels of endogenous genes similar in transcribed sequence. RNase protection assays established that silencing in tobacco plants transformed with plant-defense-related class I sense and antisense chitinase (CHN) transgenes is at the posttranscriptional level. Infection of tobacco plants with cucumber mosaic virus strain FN and a necrotizing strain of potato virus Y, but not with potato virus X, effectively suppressed PTGS and ASGS of both the transgenes and homologous endogenes. This suggests that ASGS and PTGS share components associated with initiation and maintenance of the silent state. Small, ca. 25-nt RNAs (smRNA) of both polarities were associated with PTGS and ASGS in CHN transformants as reported for PTGS in other transgenic plants and for RNA interference in Drosophila. Similar results were obtained with an antisense class I beta-1,3-glucanase transformant showing that viral suppression and smRNAs are a more general feature of ASGS. Several current models hold that diverse signals lead to production of double-stranded RNAs, which are processed to smRNAs that then trigger PTGS. Our results provide direct evidence for mechanistic links between ASGS and PTGS and suggest that ASGS could join a common PTGS pathway at the double-stranded RNA step.

Prevalence and nature of nail alterations in pediatric patients

The purpose of this investigation was to explore the frequency and nature of ungual alterations in patients of a pediatric dermatology department at a third-level pediatric hospital. The first 20 patients with nail alterations seen each year during a 5-year period from 1992 through 1996 were included, totaling 100 patients. The rate of nail alterations was 11% (1/9) in pediatric dermatology patients. There were 5 infants, 19 preschoolers (2- to 5-year-olds), 38 school children (6- to 11-year-olds), and 38 adolescents (12- to 17-year-olds). The most frequent diagnoses were onychomycosis (23), nail alterations in a genodermatosis (23), nail alterations associated with dermatoses (16), onychocryptosis (11), and paronychia (10). Toenails were involved in 54 patients, fingernails in 25, and both in 21 patients. Twenty nails were involved in 21 patients. A high prevalence of nail alterations was found in pediatric dermatology patients, some of which were nonspecific, while others provided important diagnostic clues.

CD1 expression is differentially regulated by microglia, macrophages and T cells in the central nervous system upon inflammation and demyelination

Expression of CD1 by microglia, macrophages and T cells was investigated ex vivo. In the healthy central nervous system (CNS), resident microglia, macrophages and T cells express levels of CD1 significantly lower than that expressed by splenic macrophages and T cells. During experimental autoimmune encephalomyelitis (EAE), CD1 expression by microglia and the number of CD1+ microglia increase. Macrophages and T cells strongly upregulate CD1 expression in the CNS, but not in the spleen. Whereas the function of CD1 expressed by T cells remains unclear, the expression by microglia and macrophages provides the CNS with a (glyco)lipidic-presenting molecule in an inflammatory and demyelinating environment.

Myelin oligodendrocyte glycoprotein-DNA vaccination induces antibody-mediated autoaggression in experimental autoimmune encephalomyelitis

One strategy to reestablish self tolerance in autoimmune diseases is based on the use of DNA vaccination to induce ectopic expression of the target autoantigen. We assessed the potential of vaccination with a DNA construct encoding the myelin oligodendrocyte glycoprotein (MOG), an important candidate autoantigen in multiple sclerosis, to induce tolerance and protect against experimental autoimmune encephalomyelitis (EAE). Unexpectedly, mice vaccinated with MOG-DNA developed an exacerbated form of EAE when challenged with either MOG or an unrelated encephalitogen, myelin proteolipid protein. We demonstrate that this is due to the inability of DNA vaccination to tolerize the MOG-specific T cell response and to the concomitant induction of a cytopathic MOG-specific autoantibody response, which is pathogenic, enhancing demyelination, inflammation and disease severity. Our data suggest that tolerogenic strategies for autoimmune diseases based on DNA vaccination should be approached with caution, as the outcome is unpredictable.

Development of myelin oligodendrocyte glycoprotein autoreactive transgenic B lymphocytes: receptor editing in vivo after encounter of a self-antigen distinct from myelin oligodendrocyte glycoprotein

We explored mechanisms involved in B cell self-tolerance against brain autoantigens in a double-transgenic mouse model carrying the Ig H-chain (introduced by gene replacement) and/or the L-chain kappa (conventional transgenic) of the mAb 8.18C5, specific for the myelin oligodendrocyte glycoprotein (MOG). Previously, we demonstrated that B cells expressing solely the MOG-specific Ig H-chain differentiate without tolerogenic censure. We show now that double-transgenic (THkappa(mog)) B cells expressing transgenic Ig H- and L-chains are subjected to receptor editing. We show that in adult mice carrying both MOG-specific Ig H- and L-chains, the frequency of MOG-binding B cells is not higher than in mice expressing solely the transgenic Ig H-chain. In fact, in THkappa(mog) double-transgenic mice, the transgenic kappa(mog) L-chain was commonly replaced by endogenous L-chains, i.e., by receptor editing. In rearrangement-deficient RAG-2(-) mice, differentiation of THkappa(mog) B cells is blocked at an immature stage (defined by the B220(low)IgM(low)IgD(-) phenotype), reflecting interaction of the autoreactive B cells with a local self-determinant. The tolerogenic structure in the bone marrow is not classical MOG, because back-crossing THkappa(mog) mice into a MOG-deficient genetic background does not lead to an increase in the proportion of MOG-binding B cells. We propose that an as yet undefined self-Ag distinct from MOG cross-reacts with the THkappa(mog) B cell receptor and induces editing of the transgenic kappa(mog) L-chain in early immature B cells without affecting the pathogenic potential of the remaining MOG-specific B cells. This phenomenon represents a particular form of chain-specific split tolerance.

Relationship between radiologic morphology of the bone lengthening formation and its complications

The objective was to study the different types of lengthened bone regeneration and their development during the various phases of the process to correlate them with patient factors and the surgical technique used, and to establish a possible relation between the development of the bone lengthening formation and the problems or complications. The authors studied the radiographs of a random group of 55 patients taken at three points during the course of treatment. The callus was classified with regard to its transverse diameter and the presence or absence of hypodense areas. The overall callus type was significantly influenced by the etiology, the osteotomy site, and the percentage lengthened. The percentage by which the limb was lengthened at the beginning of the process influences the overall morphology of the callus. Poor callus had been lengthened the most, atrophic callus the least. There was a correlation between the morphology of the overall callus at the end of treatment and the percentage lengthened, and between the percentage lengthened and the presence of bands at the end of treatment. The authors also found a significant correlation between age and the appearance of bands at the end of distraction. A central band was found among younger patients. The type of osteotomy affected the overall callus at the end of distraction and at the end of treatment and also influenced the transverse diameter. All the elongations with poor bone formation at the end of treatment were found to have undergone a diaphyseal osteotomy. The most common complication at the first follow-up and at the end of distraction was angulation. The diameter of the callus and the presence of bands at the end of treatment were significantly related to the complications. Fracture occurred in the first 2 weeks after removal of the external fixator in 88% of cases and in the third and fourth week in the rest. However, the segment had no significant influence on the appearance of complications. Lengthened callus with incomplete trabecular formations and hypodense areas at the end of the treatment has a high risk of fracture at the end of treatment. Callus with axial deviation, hypodense areas, or an insufficient transverse diameter during the lengthening procedure must be manipulated so that it reaches the maturing phase in better condition.

Multivalent structure of an alphabetaT cell receptor

Whether there is one or multiple alphabetaT cell antigen receptor (TCR) recognition modules in a given TCR/CD3 complex is a long-standing controversy in immunology. We show that T cells from transgenic mice that coexpress comparable amounts of two distinct TCRbeta chains incorporate at least two alphabetaTCRs in a single TCR/CD3 complex. Evidence for bispecific alphabetaTCRs was obtained by immunoprecipitation and immunoblotting and confirmed on the surface of living cells both by fluorescence resonance energy transfer and comodulation assays by using antibodies specific for TCRbeta-variable regions. Such (alphabeta)2TCR/CD3 or higher-order complexes were evident in T cells studied either ex vivo or after expansion in vitro. T cell activation is thought by many, but not all, to require TCR cross-linking by its antigen/major histocompatibility complex ligand. The implications of a multivalent (alphabeta)2TCR/CD3 complex stoichiometry for the ordered docking of specific antigen/major histocompatibility complex, CD4, or CD8 coreceptors and additional TCRs are discussed.

Gene organization and transcription analysis of the Agrobacterium tumefaciens glycogen (glg) operon: two transcripts for the single phosphoglucomutase gene

The gene organization and transcription of the Agrobacterium glg operon differ from those in other bacteria. Agrobacterium tumefaciens A348 contains a 9.1-kb gene cluster harboring genes for glycogen metabolism. The nucleotide sequence and gene organization of a region containing ADP-glucose pyrophosphorylase (glgC), glycogen synthetase (glgA), and phosphoglucomutase (pgm) genes have been previously described (A. Uttaro and R. A. Ugalde, Gene 150:117-122, 1994). In this work we report that the glycogen phosphorylase (glgP) and branching enzyme (glgB) genes are located immediately upstream of this region. The complete nucleotide sequences of the glgP and glgB genes were obtained, and mutants were constructed by targeted insertional mutagenesis with a kanamycin cassette. Enzymatic assays and reverse transcription PCR carried out with the wild type and with glgP and glgB mutants, as well as primer extension experiments and beta-galactosidase fusions, revealed that this region containing five open reading frames (glgPBCA and pgm) is transcribed unidirectionally as a single operon under the control of a promoter located upstream of the glycogen phosphorylase gene (glgP). An alternative transcript was identified starting 168 bp upstream of an internal ATG start codon of the pgm gene, which is translated as a 71-amino-acid-shorter Pgm protein which complements in vivo a pgm mutant. This alternative transcript has a promoter with the motif TATCAAN5G, identified in octopine Ti plasmid as an autoinducible TraR promoter. This promoter is >200 times more efficient in A. tumefaciens than in Escherichia coli, as judged by the level of enzymatic activity of a lacZ-pgm fusion.

Neuronal expression of fractalkine in the presence and absence of inflammation

Fractalkine is the only as yet known member of a novel class of chemokines. Besides its novel Cys-X-X-X-Cys motif, fractalkine exhibits features which have not been described for any other member of the chemokine family, including its unusual size (397 amino acids human, 395 mouse) and the possession of a transmembrane anchor, from which a soluble form may be released by extracellular cleavage. This report demonstrates the abundant mRNA and fractalkine protein expression in neuronal cells. The neuronal expression of fractalkine mRNA is unaffected by experimentally induced inflammation of central nervous tissue.

Takayasu arteritis in Colombia

Takayasu arteritis has been recognized in Colombia just recently, and so far we do not have any report concerning its presentation here. In this first report, some issues related to the presentation of the disease are indicated and compared with those found in the medical literature. No differences were found in age and sex. Most of the cases were diagnosed during an inactive phase of the disease with advanced manifestations due to vascular lesion which suggests the existence of some genetic factor influencing such a presentation, or may be the consequence of a delay in diagnosing the disease during initial and active stages due to not suspecting it. Comparing the vessels which are affected among other races and countries, we can find both differences and similarities. With the purpose of discovering the demographic, clinical, angiographic and laboratorial characteristics of Takayasu arteritis in Colombia, the present study was carried out by studying 35 clinical cases in different medical centers of the country.

B lymphocytes producing demyelinating autoantibodies: development and function in gene-targeted transgenic mice

We studied the cellular basis of self tolerance of B cells specific for brain autoantigens using transgenic mice engineered to produce high titers of autoantibodies against the myelin oligodendrocyte glycoprotein (MOG), a surface component of central nervous system myelin. We generated "knock-in" mice by replacing the germline JH locus with the rearranged immunoglobulin (Ig) H chain variable (V) gene of a pathogenic MOG-specific monoclonal antibody. In the transgenic mice, conventional B cells reach normal numbers in bone marrow and periphery and express exclusively transgenic H chains, resulting in high titers of MOG-specific serum Igs. Additionally, about one third of transgenic B cells bind MOG, thus demonstrating the absence of active tolerization. Furthermore, peritoneal B-1 lymphocytes are strongly depleted. Upon immunization with MOG, the mature transgenic B cell population undergoes normal differentiation to plasma cells secreting MOG-specific IgG antibodies, during which both Ig isotype switching and somatic mutation occur. In naive transgenic mice, the presence of this substantial autoreactive B cell population is benign, and the mice fail to develop either spontaneous neurological disease or pathological evidence of demyelination. However, the presence of the transgene both accelerates and exacerbates experimental autoimmune encephalitis, irrespective of the identity of the initial autoimmune insult.

Like p53, the proliferation-associated protein p120 accumulates in human cancer cells following exposure to anticancer drugs

Accumulation of p53 protein following DNA damage is independent of transcription; in turn, p53 transcriptionally induces other proteins. Herein we demonstrated that p120, a proliferation-associated protein, was induced by DNA-damaging and microtubule-active drugs in human cancer cells. However, induction of p120 was independent of p53; and expression of exogenous wt p53 induced p21WAF1/CIP1 but not p120, excluding p120 as a transcriptional target of p53. Like p53, induction of p120 by anticancer drugs did not require transcription. Induction of p120 by actinomycin-D occurred at concentrations which inhibit RNA synthesis and p120 mRNA levels. Inhibition of proteasomes resulted in accumulation of higher molecular weight proteins, reacting with anti-p120 antibodies. This suggests that the mechanisms of p120 and p53 induction are similar and involve inhibition of degradation. p120 protein stabilization represents an expedient means for accumulation of key response proteins following exposure to cytotoxic agents.

[Expression of DNA topoisomerases (I, II alpha, II beta) mRNA in etoposide- and mAMSA-resistant cell lines]

The efficacy of all chemotherapeutic agents is limited by the occurrence of drug resistance. To further understand resistance to topoisomerase (topo) II inhibitors, 50 sublines were isolated as single clones from parental cells by exposure to etoposide or m-AMSA. Subsequently, a population of cells from each subline was exposed to three-fold higher drug concentrations allowing 16 stable sublines to be established at higher extracellular drug concentration. Quantitative aspects of topo I, II alpha, and II beta were studied by Northern blotting in 66 resistant cell lines. Reduced topo II alpha mRNA was observed in 95.5% of resistant cell lines, and median topo II alpha mRNA was lower (38.0 +/- 28.1%) in resistant cell lines in comparison to parental cell lines, while increased topo I and II beta were observed (145.5 +/- 89.3%, and 165 +/- 105.9% of that of parental cell lines). But the expression of the topo I and II beta gene were not correlated to that of topo II alpha. Our findings suggest that reduced topo II alpha mRNA seems to be the most important mechanism of resistance to topo II inhibitors.

[Expression of ATP binding cassette superfamily (multidrug resistance-1, multidrug resistance-associated protein, human canalicular multispecific organ anion transporter) mRNA in etoposide and m-AMSA resistant cell lines]

The efficacy of all chemotherapeutic agents is limited by the occurrence of drug resistance. To further understand resistance to topoisomerase (topo) II inhibitors, 50 sublines were isolated as single clones from parental cells by exposure to etoposide or m-AMSA. Subsequently, a population of cells from each sublines was exposed to three-fold higher drug concentrations allowing 16 stable sublines to be established at higher extracellular drug concentration. Quantitative aspects of MRP and C-MOAT were studied by Northern blotting in 66 resistant cell lines. Increased MRP mRNA was observed in 48.5% of resistant cell lines (64.7% of etoposide resistant cells and 31.3% of m-AMSA resistant cell lines). Increased C-MOAT mRNA was also observed in 39.4% of resistant cell lines (41.2% in etoposide resistant cell lines and 37.5% in m-AMSA resistant cell lines). To characterize the function of C-MOAT, cellular accumulation assay for 3H-etoposide was performed in three resistant cell lines which overexpress C-MOAT but do not express MRP. Accumulation of etoposide was reduced in the cell lines. Our findings suggest that increased MRP and O-MOAT mRNA seems to be an important mechanism of resistance to topo II inhibitors.

Gliomatosis cerebri mimicking a metastatic breast cancer: fatal outcome

Gliomatosis cerebri (GC) is defined by the World Health Organization as a neoplasm of the glial cells. It is extremely rare, and there exists only 160 documented cases since 1897. There is no known treatment and the median survival rate is one year. The association of extracranial and CNS tumors is unusual, only three cases of breast cancer have been associated with gliomas and meningiomas but none with GC. Below we describe a case of breast cancer associated with GC and review the anatomoclinical and radiological manifestations of Gliomatosis Cerebri.