RESUMEN

Contact dermatitis is a major problem in the healthcare environment and in other sectors. Healthcare professionals may be exposed to a large number of chemical agents, including the accelerators for rubber vulcanization process. The prevalence of allergic contact dermatitis among operators in the sector ranges 13­30%. This paper describes the case of a 46-year-old male cardiac surgeon affected by a severe skin reaction localized on the face in the absence of hand dermatitis, presumably resulting from the use of a surgical patch applied to the face. Patch tests were performed and the result was negative for latex and positive (+++) for thiuram mix. A thiuram-free tape was prescribed and the operator's dermatitis improved significantly. Thus, it would be very important to pay attention to skin disorders in health workers and thiuram as an occupational allergen. Med Pr. 2019;70(1):121­4

RESUMEN

Many bacterial toxins utilize cell surface glycoconjugate receptors for attachment to target cells. In the present study the potential carbohydrate binding of Helicobacter pylori vacuolating cytotoxin VacA was investigated by binding to human gastric glycosphingolipids on thin-layer chromatograms. Thereby a distinct binding of the toxin to two compounds in the non-acid glycosphingolipid fraction was detected. The VacA-binding glycosphingolipids were isolated and characterized by mass spectrometry and proton NMR as galactosylceramide (Galbeta1Cer) and galabiosylceramide (Galalpha4Galbeta1Cer). Comparison of the binding preferences of the protein to reference glycosphingolipids from other sources showed an additional recognition of glucosylceramide (Glcbeta1Cer), lactosylceramide (Galbeta4Glcbeta1Cer) and globotriaosylceramide (Galalpha4Galbeta4Glcbeta1Cer). No binding to the glycosphingolipids recognized by the VacA holotoxin was obtained with a mutant toxin with deletion of the 37 kDa fragment of VacA (P58 molecule). Collectively our data show that the VacA cytotoxin is a glycosphingolipid binding protein, where the 37 kDa moiety is required for carbohydrate recognition. The ability to bind to short chain glycosphingolipids will position the toxin close to the cell membrane, which may facilitate toxin internalization.

Asunto(s)

Proteínas Bacterianas/metabolismo , Glicoesfingolípidos/metabolismo , Helicobacter pylori/química , Estómago/química , Sitios de Unión , Epitelio/metabolismo , Infecciones por Helicobacter/inmunología , Humanos

RESUMEN

Most Helicobacter pylori strains secrete a toxin (VacA) that causes massive vacuolization of target cells and which is a major virulence factor of H. pylori. The VacA amino-terminal region is required for the induction of vacuolization. The aim of the present study was a deeper understanding of the critical role of the N-terminal regions that are protected from proteolysis when VacA interacts with artificial membranes. Using a counterselection system, we constructed an H. pylori strain, SPM 326-Delta49-57, that produces a mutant toxin with a deletion of eight amino acids in one of these protected regions. VacA Delta49-57 was correctly secreted by H. pylori but failed to oligomerize and did not have any detectable vacuolating cytotoxic activity. However, the mutant toxin was internalized normally and stained the perinuclear region of HeLa cells. Moreover, the mutant toxin exhibited a dominant negative effect, completely inhibiting the vacuolating activity of wild-type VacA. This loss of activity was correlated with the disappearance of oligomers in electron microscopy. These findings indicate that the deletion in VacA Delta49-57 disrupts the intermolecular interactions required for the oligomerization of the toxin.

Asunto(s)

Proteínas Bacterianas/metabolismo , Helicobacter pylori/metabolismo , Vacuolas/metabolismo , Proteínas Bacterianas/genética , Células HeLa , Helicobacter pylori/fisiología , Humanos , Microscopía Electrónica , Mutación , Fenotipo , Técnicas del Sistema de Dos Híbridos

RESUMEN

There are two alleles, m1 and m2, of the midregion of the vacuolating cytotoxin gene (vacA) of Helicobacter pylori which code for toxins with different cell specificities. Here we describe the construction of five chimeric strains in which regions of vacA were exchanged between the two genotypes. By analyzing the toxicity of these strains for HeLa and RK13 cells we have confirmed that a 148-amino-acid region determines the phenotypic differences between the two forms of the protein and that this entire region is important for cytotoxicity. Furthermore, we have used our chimeric strains to investigate whether variations in the midregion of VacA have an effect on phorbol 12-myristate 13-acetate (PMA)-induced VacA sensitivity in HL-60 cells. The PMA-induced VacA sensitivity of HL-60 cells has been previously associated with the appearance of the cell surface receptor protein tyrosine phosphatase beta (RPTPbeta). Our data indicate that both the m1 and m2 forms of VacA are able to utilize RPTPbeta, and the cell-specific phenotype of the midregion is independent of the presence of RPTPbeta. It appears that another as-yet-unidentified receptor exists in HL-60 cells that accounts for the m2 phenotype in this cell line. Also, by studying the effect of PMA on levels of RPTPbeta in other cell lines and toxicity of VacA in these cell lines we have shown that RPTPbeta does not play a major role in the vacuolation of HeLa cells.

Asunto(s)

Proteínas Bacterianas/genética , Helicobacter pylori/enzimología , Helicobacter pylori/genética , Proteínas del Tejido Nervioso/fisiología , Proteínas Tirosina Fosfatasas/fisiología , Secuencia de Aminoácidos , Proteínas Bacterianas/metabolismo , Células HeLa , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/patogenicidad , Humanos , Datos de Secuencia Molecular , Fenotipo , Polimorfismo Genético , Proteínas Tirosina Fosfatasas Clase 5 Similares a Receptores , Acetato de Tetradecanoilforbol/farmacología

RESUMEN

An extensive analysis of organ and cell size was performed in three different Arabidopsis lines transformed with the early nodulin gene enod40 under control of the CaMV35S promoter. All three transgenic lines presented a significant decrease in the mean size of both epidermal internode and leaf mesophyll cells. Flow cytometric and image analysis of enod40-transfected protoplasts prepared from wild-type Arabidopsis cell suspensions showed that transient expression of the gene resulted in reduced forward light scattering (a factor correlated with particle size) and cell size. The direct administration of ENOD40 peptide to fresh protoplasts also resulted in reduced forward scattering with respect to the control and to the administration of unrelated peptides. As far as is known this is the first report documenting a biological effect of enod40 at the cellular level in non-legume plants.

Asunto(s)

Arabidopsis/citología , Arabidopsis/genética , Tamaño de la Célula , Proteínas de Plantas/fisiología , Expresión Génica , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas , Protoplastos/metabolismo

RESUMEN

Helicobacter pylori is the causative agent of peptic ulcer disease. A major virulence factor of H. pylori is VacA, a toxin that causes massive vacuolization of epithelial cell lines in vitro and gastric epithelial erosion in vivo. Although VacA is exported over the outer membrane and is released from the bacteria, a portion of the toxin remains associated with the bacterial surface. We have found surface-associated toxin to be biologically active and spatially organized into distinct toxin-rich domains on the bacterial surface. Upon bacterial contact with host cells, toxin clusters are transferred directly from the bacterial surface to the host cell surface at the bacteria-cell interface, followed by uptake and intoxication. This contact-dependent transfer of VacA represents a cost-efficient route for delivery of VacA and potentially other bacterial effector molecules to target cells.

Asunto(s)

Adhesión Bacteriana , Proteínas Bacterianas/metabolismo , Helicobacter pylori/patogenicidad , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Línea Celular Tumoral , Eliminación de Gen , Helicobacter pylori/metabolismo , Humanos , Microscopía Confocal , Vacuolas

RESUMEN

Helicobacter pylori toxin, VacA, damages the gastric epithelium by erosion and loosening of tight junctions. Here we report that VacA also interferes with T cell activation by two different mechanisms. Formation of anion-specific channels by VacA prevents calcium influx from the extracellular milieu. The transcription factor NF-AT thus fails to translocate to the nucleus and activate key cytokine genes. A second, channel-independent mechanism involves activation of intracellular signaling through the mitogen-activated protein kinases MKK3/6 and p38 and the Rac-specific nucleotide exchange factor, Vav. As a consequence of aberrant Rac activation, disordered actin polymerization is stimulated. The resulting defects in T cell activation may help H. pylori to prevent an effective immune response leading to chronic colonization of its gastric niche.

Asunto(s)

Proteínas Bacterianas/toxicidad , Helicobacter pylori/patogenicidad , Inmunosupresores/toxicidad , Activación de Linfocitos/efectos de los fármacos , Proteínas Nucleares , Linfocitos T/efectos de los fármacos , Transporte Activo de Núcleo Celular , Calcio/metabolismo , Proteínas Quinasas Dependientes de Calcio-Calmodulina/fisiología , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/metabolismo , Humanos , Células Jurkat , MAP Quinasa Quinasa 3 , MAP Quinasa Quinasa 6 , Macrófagos/efectos de los fármacos , Macrófagos/enzimología , Quinasas de Proteína Quinasa Activadas por Mitógenos/fisiología , Proteínas Quinasas Activadas por Mitógenos/fisiología , Factores de Transcripción NFATC , Neutrófilos/efectos de los fármacos , Neutrófilos/enzimología , Proteínas Tirosina Quinasas/fisiología , Transducción de Señal , Linfocitos T/inmunología , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos

RESUMEN

There are two functionally different alleles of the Helicobacter pylori vacA gene, which code for proteins with different in target cell specificity. The alleles (m1 and m2) differ by approximately 50% in amino acid sequence in a 300 amino acid region, the m-region, which determines specificity. An analysis of partial likelihood anomalies in a set of eight Chinese and six Western vacA genes revealed highly significant phylogenetic deviation of a region of the gene including the m-region. Phylogenetic analysis of the conserved regions of these genes failed to reveal any distinction between m1 alleles and m2 alleles, however clear cut geographic variation was observed. In the m-region, the m1 alleles also show separate clustering of Chinese and Western isolates, however the m-region of the m2 alleles has a phylogenetic structure markedly different from the rest of the gene. The data indicate that the m2 m-region was acquired and spread through the population by horizontal transfer of DNA.

Asunto(s)

Proteínas Bacterianas/genética , Toxinas Bacterianas/genética , Citotoxinas/genética , Evolución Molecular , Helicobacter pylori/genética , China/epidemiología , Dispepsia/epidemiología , Dispepsia/microbiología , Genes Bacterianos , Infecciones por Helicobacter/epidemiología , Infecciones por Helicobacter/microbiología , Helicobacter pylori/clasificación , Humanos , Epidemiología Molecular , Datos de Secuencia Molecular , Polimorfismo Genético

RESUMEN

Se realizaron estudios de ultraestructura con microscopía convencional y electrónica en 7 válvulas de porcino. Cinco de las prótesis habían sido sometidas a más de 24 meses de conservación en glutaraldehído. Las dos restantes habían sido descartadas en la evaluación final por presentar áreas de diferente tinción en el examen de control final. El examen microscópico reveló en las cinco primeras válvulas las alteraciones típicas secundarias al manipuleo durante la elaboración de las mismas (pérdida parcial del endotelio), con preservación de la estructura en las restantes capas. Las dos válvulas restantes presentaban degeneración fibrosa y lipomatosa por patología propia del cerdo. Se concluye que tiempos prolongados de preservación en glutaral dehído no ocasiona modificaciones ulteriores a las ya observadas en una válvula recientemente confeccionada. Se destaca la importancia de los procesos de elaboración y controles de las prótesis, particularmente el examen con magnificación óptica para detectar alteraciones degenerativas propias del animal

Asunto(s)

Bioprótesis , Glutaral , Preservación de Órganos/métodos , Válvulas Cardíacas/ultraestructura , Prótesis Valvulares Cardíacas/rehabilitación , Trasplante Heterólogo , Válvula Aórtica/patología , Válvulas Cardíacas/patología