Enucleated L929 mouse fibroblasts support invasion and multiplication of Shigella flexneri 5a

Invasive bacteria can induce their own uptake and specify their intracellular localization; hence it is commonly assumed that proximate modulation of host cell transcription is not required for infection. However, bacteria can also modulate, directly or indirectly, the transcription of many host cell genes, whose role in the infection may be difficult to determine by global gene expression. Is the host cell nucleus proximately required for intracellular infection and, if so, for which pathogens and at what stages of infection? Enucleated cells were previously infected with Toxoplasma gondii, Chlamydia psittaci, C. trachomatis, or Rickettsia prowazekii. We enucleated L929 mouse fibroblasts by centrifugation in the presence of cytochalasin B, and compared the infection with Shigella flexneri M90T 5a of nucleated and enucleated cells. Percent infection and bacterial loads were estimated with a gentamicin suppression assay in cultures fixed and stained at different times after infection. Enucleation reduced by about half the percent of infected cells, a finding that may reflect the reduced endocytic ability of L929 cytoplasts. However, average numbers of bacteria and frequency distributions of bacterial numbers per cell at different times were similar in enucleated and nucleated cells. Bacteria with actin-rich tails were detected in both cytoplasts and nucleated cells. Lastly, cytoplasts were similarly infected 2 and 24 h after enucleation, suggesting that short-lived mRNAs were not involved in the infection. Productive S. flexneri infection could thus take place in cells unable to modulate gene transcription, RNA processing, or nucleus-dependent signaling cascades.

From lysosomes to cells, from cells to Leishmania: amino acid esters as potential chemotherapeutic agents

Amino acid esters can disrupt lysosomes and damage monocytes and certain lymphocyte populations. Lysosomal disruption involves pH trapping of the esters, followed by their hydrolyssis by as yet unidentified enzymes. Accumulation of the more polar amino acids is assumed to cause osmotic lysis of the organelles. we have discovered that certain amino acid esters and amides destroy Leishmania mexicana amazonensis amastigores lodged within macrophages in culture, as well as parasites isolated from mouse lesions. This paper reviews the amino acid specificity of parasite killing, the resistance of amastigotes derived from infection of macrophages with promastigotes, the involvement of an acidified compartment within the parasites, and the protection conferred by other amino acid esters, and the protease inhibitors antipain and chymostatin, aginst the destruction of amastigotes by Leucine-methyl ester. Studies with tritiated esters confirm the critical role of ester hydrolysis for leishmanicidal activity and strengthen the view that similar mechanisms underlie disruption of lysosomes and destruction of Leismania. Characterization of the parasite organelles and of the enzymes involved in the leishmanicidal activity as well as structure-activity studies may permit the design of compounds mor selective for the parasites

Cirurgia da catarata mole pelo S.I.T.E Federman. / Surgery of soft cataract with S.I.T.E - Federman

Os AA. propoe a cirurgia das cataratas moles (congenita, complicada e traumatica) empregando-se o vitreofago S.I.T.E - Federman.Discutem as vantagens do metodo e suas vias de abordagem, dando preferencia pela via pars plana, pelas vantagens e menores complicacoes que ela apresenta

Levantamento do relacionamento casa de optica oftalmologista na cidade de Säo Paulo. / Survey on the relationship between opticians and ophtalmologists at the city of Säo Paulo.

Os autores fizeram um levantamento do relacionamento existente entre opticas e oftalmologistas em 12 bairros da cidade de Sao Paulo percorrendo 150 opticas escolhidas aleatoriamente. Encontraram 92,67% indicando medico, sendo que 7,33% indicavam consulta gratuita, 42,67% indicavam medico com direito a desconto na consulta e 42,67% sem direito a desconto. Das indicacoes de medico sem desconto encontraram 36,67% indicando um medico especificamente e 8,1% indicando varios medicos.Encontraram tambem um optico (0,67%) que efetuou o exame. Academicos emetropes se submeteram a 5 exames gratuitos, tendo sido receitados oculos em 4 casos. Os autores concluem ressaltando a necessidade de se haver maior discussao a respeito do assunto e da necessidade de se reestudar qualitativa e quantitativamente a formacao de medicos no nosso pais.}