RESUMO
In the self-magnetic-pinch diode, the electron beam, produced through explosive field emission, focuses on the anode surface due to its own magnetic field. This process results in dense plasma formation on the anode surface, consisting primarily of hydrocarbons. Direct measurements of the beam's current profile are necessary in order to understand the pinch dynamics and to determine x-ray source sizes, which should be minimized in radiographic applications. In this paper, the analysis of the C IV doublet (580.1 and 581.2 nm) line shapes will be discussed. The technique yields estimates of the electron density and electron temperature profiles, and the method can be highly beneficial in providing the current density distribution in such diodes.
RESUMO
Experimental autoimmune anterior uveitis (EAAU) is an animal model for acute anterior uveitis in humans. Previously, we have shown that EAAU can be induced in Lewis rats by a protein(s) associated with ocular melanin. The present study was designed to further purify the pathogenic antigen. Melanin associated antigen (MAA), isolated from bovine iris and ciliary body, was digested with V8 protease and the soluble protein separated on a cation exchange column. The bound protein was eluted with a salt gradient. Lewis rats were immunised with the resulting fractions to test for pathogenicity. Moderate to severe EAAU, with clinical and histopathological features similar to induction with crude soluble bovine MAA, was observed with the 100-200 mM gradient of NH4Cl. Thus, bovine MAA has been partially purified using cation exchange chromatography. Studies are currently under way to purify bovine MAA to homogeneity.
Assuntos
Antígenos/isolamento & purificação , Corpo Ciliar/imunologia , Iris/imunologia , Melaninas/imunologia , Uveíte Anterior/imunologia , Doença Aguda , Animais , Antígenos/imunologia , Biomarcadores , Bovinos , Cromatografia por Troca Iônica , Modelos Animais de Doenças , Masculino , Ratos , Ratos Endogâmicos Lew , Organismos Livres de Patógenos EspecíficosRESUMO
PURPOSE: This study was designed to investigate an animal model of uveitis that resembles anterior uveitis in humans after immunization with iris-ciliary body antigen. METHODS: Male Lewis rats 6 to 8 weeks of age were immunized with the buffer- and detergent-insoluble bovine iris-ciliary body antigen mixed with complete Freund's adjuvant and pertussis toxin. Antigen was digested with various proteolytic enzymes and tested in different rodent strains for a uveitogenic response. RESULTS: Acute iridocyclitis developed in both eyes of the Lewis rat during the second week after immunization, and the pattern of inflammation was similar to acute anterior uveitis in humans, with sudden onset, localization to the anterior uvea, and spontaneous resolution. Among the strains tested, F344 rats were susceptible to experimental autoimmune anterior uveitis but Long-Evans rats were not. Experimental autoimmune anterior uveitis did not develop in any of the mice studied, nor was it induced by immunization with synthetic melanin, amelanotic bovine tissues, pigmented bovine skin, or pigmented rat and rabbit iris-ciliary body. A soluble fraction derived from bovine melanin-associated antigen (BMAA) after digestion with the proteolytic enzyme V8 protease resulted in a disease similar to that observed with intact BMAA. CONCLUSIONS: A model of anterior uveitis has been induced in the Lewis rat after immunization with bovine uveal antigen, and it resembles the acute iridocyclitis observed in humans. These results suggest that the pathogenic antigen is a melanin-associated protein(s) present within the iris-ciliary body.
Assuntos
Autoantígenos/imunologia , Corpo Ciliar/imunologia , Iris/imunologia , Melaninas/imunologia , Uveíte Anterior/imunologia , Animais , Corpo Ciliar/patologia , Modelos Animais de Doenças , Endopeptidases/farmacologia , Imunização , Iris/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Coelhos , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Especificidade da Espécie , Uveíte Anterior/genética , Uveíte Anterior/patologiaRESUMO
In the absence of antibiotics, carriage of pACYC184 reduces the competitive fitness of an Escherichia coli B genotype that was not previously selected for plasmid carriage, relative to that of an isogenic plasmid-free competitor. However, a host genotype propagated with the plasmid for 500 generations evolved an unexpected competitive advantage from plasmid carriage, relative to its own isogenic plasmid-free segregant. We manipulated the pACYC184 genome in order to identify the plasmid-encoded function that was required for the enhancement of the coevolved host genotype's competitive fitness. Inactivation of the plasmid-encoded tetracycline resistance gene, by deletion of either the promoter region or the entire gene, eliminated the beneficial effect of plasmid carriage for the coevolved host. This beneficial effect for the coevolved host was also manifest with pBR322, which contains a tetracycline resistance gene identical to that of pACYC184 but is otherwise heterologous.
Assuntos
Escherichia coli/fisiologia , Plasmídeos/genética , Seleção Genética , Resistência a Tetraciclina/genética , Evolução Biológica , Cloranfenicol/farmacologia , Resistência ao Cloranfenicol/genética , Escherichia coli/efeitos dos fármacos , Genótipo , Regiões Promotoras Genéticas/genética , Deleção de Sequência , Tetraciclina/farmacologiaRESUMO
The CD4 T-cell surface antigen and the lymphocyte-specific tyrosine-protein kinase p56lck form a stable noncovalent complex in CD4+ T-lymphocytes. In this report, we demonstrate that these two gene products can also associate when co-expressed in NIH3T3 fibroblasts, therefore implying that other lymphoid specific components are not required for the CD4-lck interaction. These results also suggest that co-expression of CD4 and p56lck in non-lymphoid cells may prove to be a useful model system for the analysis of structural and possibly functional CD4-lck interactions.
