DRhoGEF2 regulates cellular tension and cell pulsations in the Amnioserosa during Drosophila dorsal closure.

Coordination of apical constriction in epithelial sheets is a fundamental process during embryogenesis. Here, we show that DRhoGEF2 is a key regulator of apical pulsation and constriction of amnioserosal cells during Drosophila dorsal closure. Amnioserosal cells mutant for DRhoGEF2 exhibit a consistent decrease in amnioserosa pulsations whereas overexpression of DRhoGEF2 in this tissue leads to an increase in the contraction time of pulsations. We probed the physical properties of the amnioserosa to show that the average tension in DRhoGEF2 mutant cells is lower than wild-type and that overexpression of DRhoGEF2 results in a tissue that is more solid-like than wild-type. We also observe that in the DRhoGEF2 overexpressing cells there is a dramatic increase of apical actomyosin coalescence that can contribute to the generation of more contractile forces, leading to amnioserosal cells with smaller apical surface than wild-type. Conversely, in DRhoGEF2 mutants, the apical actomyosin coalescence is impaired. These results identify DRhoGEF2 as an upstream regulator of the actomyosin contractile machinery that drives amnioserosa cells pulsations and apical constriction.

The S. cerevisiae Yap1 and Yap2 transcription factors share a common cadmium-sensing domain.

Towards elucidating the function of Yap2, which remains unclear, we have taken advantage of the C-terminal homology between Yap1 and Yap2. Swapping domains experiments show that the Yap2 C-terminal domain functionally substitutes for the homologous Yap1 domain in the response to Cd, but not to H2O2. We conclude that specificity determinants of the Cd response are encoded within both Yap1 and Yap2 C-terminus, whereas those required for H2O2 response are only present in the Yap1 C-terminus. Furthermore, our results identify FRM2 as Cd-responsive Yap2 target and indicate a possible role of this protein in regulating a metal stress response.

Compartmentalisation of Rho regulators directs cell invagination during tissue morphogenesis.

During development, small RhoGTPases control the precise cell shape changes and movements that underlie morphogenesis. Their activity must be tightly regulated in time and space, but little is known about how Rho regulators (RhoGEFs and RhoGAPs) perform this function in the embryo. Taking advantage of a new probe that allows the visualisation of small RhoGTPase activity in Drosophila, we present evidence that Rho1 is apically activated and essential for epithelial cell invagination, a common morphogenetic movement during embryogenesis. In the posterior spiracles of the fly embryo, this asymmetric activation is achieved by at least two mechanisms: the apical enrichment of Rho1; and the opposing distribution of Rho activators and inhibitors to distinct compartments of the cell membrane. At least two Rho1 activators, RhoGEF2 and RhoGEF64C are localised apically, whereas the Rho inhibitor RhoGAP Cv-c localises at the basolateral membrane. Furthermore, the mRNA of RhoGEF64C is also apically enriched, depending on signals present within its open reading frame, suggesting that apical transport of RhoGEF mRNA followed by local translation is a mechanism to spatially restrict Rho1 activity during epithelial cell invagination.

Yeast activator proteins and stress response: an overview.

Yeast, and especially Saccharomyces cerevisiae, are continuously exposed to rapid and drastic changes in their external milieu. Therefore, cells must maintain their homeostasis, which is achieved through a highly coordinated gene expression involving a plethora of transcription factors, each of them performing specific functions. Here, we discuss recent advances in our understanding of the function of the yeast activator protein family of eight basic-leucine zipper trans-activators that have been implicated in various forms of stress response.

Expression of YAP4 in Saccharomyces cerevisiae under osmotic stress.

YAP4, a member of the yeast activator protein ( YAP ) gene family, is induced in response to osmotic shock in the yeast Saccharomyces cerevisiae. The null mutant displays mild and moderate growth sensitivity at 0.4 M and 0.8 M NaCl respectively, a fact that led us to analyse YAP4 mRNA levels in the hog1 (high osmolarity glycerol) mutant. The data obtained show a complete abolition of YAP4 gene expression in this mutant, placing YAP4 under the HOG response pathway. YAP4 overexpression not only suppresses the osmosensitivity phenotype of the yap4 mutant but also relieves that of the hog1 mutant. Induction, under the conditions tested so far, requires the presence of the transcription factor Msn2p, but not of Msn4p, as YAP4 mRNA levels are depleted by at least 75% in the msn2 mutant. This result was further substantiated by the fact that full YAP4 induction requires the two more proximal stress response elements. Furthermore we find that GCY1, encoding a putative glycerol dehydrogenase, GPP2, encoding a NAD-dependent glycerol-3-phosphate phosphatase, and DCS2, a homologue to a decapping enzyme, have decreased mRNA levels in the yap4 -deleted strain. Our data point to a possible, as yet not entirely understood, role of the YAP4 in osmotic stress response.

Two redox centers within Yap1 for H2O2 and thiol-reactive chemicals signaling.

The Yap1 transcription factor regulates yeast responses to H2O2 and to several unrelated chemicals and metals. Activation by H2O2 involves Yap1 Cys303-Cys598 intra-molecular disulfide bond formation directed by the H2O2 sensor Orp1/Gpx3. We show here that the electrophile N-ethylmaleimide activates Yap1 by covalent modification of Yap1 C-terminal Cys598, Cys620, and Cys629, in an Orp1 and Yap1-oxidation-independent way, thus establishing an alternate and distinct mode of Yap1 activation. We also show that menadione, a superoxide anion generator and a highly reactive electrophile, operates both modes of Yap1 activation. Further, the Yap1 C-terminal domain reactivity towards other electrophiles (4-hydroxynonenal, iodoacetamide) and metals (cadmium, selenium) suggests a common mechanism for sensing thiol reactive chemicals, involving thiol chemical modification. We propose that Yap1 has two distinct molecular redox centers, one triggered by ROS (hydroperoxides and the superoxide anion) and the other by chemicals with thiol reactivity (electrophiles and divalent heavy metals cations). These data indicate that yeast cells cannot sense these compounds through the same molecular devices, albeit they are all electrophilic.

Staphylococcus aureus / Staphylococcus aureus

De 1.003 materiais analisados, provenientes de pacientes queimados, de funcionários (médicos, enfermeiros e atendentes) e do ambiente/fômites da Unidade de Queimados do Hospital das Clínicas de Ribeiräo Preto - USP, no período de 1985 a 1986, 373 (37,2% ) foram positivos para S. aureus. Dos materiais de pacientes, 51,2% resultaram em cultura positiva, seguidos dos de funcionários com 33,3% e do ambiente/fômites com 20,2% . Considerando diferentes nichos em pacientes e funcionários, encontrou-se, respectivamente: para as fossas nasais, 58,8% e 53,3% ; para as mäos, 50,0% e 27,6% , para a saliva, 47,1% e 19,4% de amostras positivas. Esses dados sugerem a necessidade de observância da cadeia asséptica, objetivando o bloqueio da cadeia epidemiológica da infecçäo hospitalar

Assistência de enfermagem ao cliente queimado no ambulatório e/ou no domicílio após alta da unidade de internaçäo / The nurse assistance to burned people

A investigaçäo realizada por quatro enfermeiras objetiva ressaltar a importäncia desse profissional na assistência ao queimado, após alta hospitalar, para averiguar o aparecimento de possíveis seqüelas e, diagnosticando-as, utilizar meios para minimizá-las. Também foi preocupaçäo do grupo certificar se as orientaçöes dadas a cliente/família sobre higiene, uso de suportes ortopédicos e máscaras haviam sido assimiladas. Os resultados confirmam a ocorrência de problemas relacionados à cicatrizaçäo das lesöes.

Contribuiçäo ao estudo da prevalência de infeçäo por Pseudomonas aeruginosa em pacientes queimados, hospitalizados / Prevalence of P. aeruginosa infection in burned hospitalized patients

No presente estudo, a Autora investiga a prevalência de infecçäo por P. aeruginosa nas lesöes causadas por queimaduras, em pacientes hospitalizados, considerando na abrangência da pesquisa, aspectos bacteriológicos, epidemiológicos e assistenciais, em decorrência das implicaçöes desses fatores no tratamento local daquelas lesöes. Procura estabelecer a cadeia microbiana da bacteria estudada e aprofunda a investigaçäo com o propósito de identificar as espécies e os biotipos presentes nas amostras colhidas, a fim de melhor aquilatar a verdadeira extensäo do problema. Desenvolve o trabalho a partir da colheita de amostras obtidas nas fontes consideradas suspeitas atingindo um total de 1.029 amostras, as quais foram extraídas, de acordo com as respectivas procedências, como segue: 402 do ambiente/fômites; 531 dos pacientes; 90 dos funcionários e 6 de outras pessoas envolvidas. Desta pesquisa, resultaram 379 (36,8%) amostras positivas, das quais 177 de 47 fontes do ambiente/fômites; 194 das lesöes, boca, fossas nasais e outros locais dos pacientes queimados e finalmente, 6 obtidas da boca, mäo e outros locais, de 5 funcionárioss e também 2, de um cônjuge, desses. Das 379 amostras positivas, a Autora obteve 672 cepas, sendo que destas,617 foram identificadas como P. aeruginosa, com percentuais elevados para o ambiente fômites (86,3%) se contaminou com aquela bactéria. Além da P. aeruginosa, outras espécies foram aos biotipos A e G. Além disso, foi ainda possível estabelecer a relaçäo existente entre as cepas das diferentes origens, caracterizando-se 438 delas como endêmicas, distribuídas entre os piocinotipos 611131, 111111 e em cepas NT. Este estudo pode ser feito, graças ao emprego da piocinotipagem e antibiograma. A autora constatou que 75,3% das cepas relativas ao ambiente/fômites e pacientes foram dos modelos RRRRR e SRRRR e que somente 4,8%, pertenciam ao modelo SSSSS...

Proposta de um perfil do enfermeiro / A proposal for a nurse's profile

As autoras apresentam proposta de um perfil do enfermeiro. Abrangem os pressupostos para determinaçäo do perfil; características do enfermeiro; estrutura básica das funçöes do enfermeiro, especificando a competência de cada uma das funçöes

Tratamento local de queimaduras com aplicaçäo de membrana amniótica: intervençäo do enfermeiro, um estudo comparativo

O presente estudo, do tipo exploratório, objetiva comprovar a eficácia da aplicaçäo da membrana amniótica em lesöes por queimaduras e comparar os resultados desse método com os obtidos mediante o uso do Sulfamylon creme e/ou Nitrato de Prata. A amostragem constou de 74 clientes, 50 por cento de cada hospital. No hospital A (Macapá), empregou-se a membrana amniótica e a pesquisadora observou diretamente a amostra. No hospital B (Rio de Janeiro), empregou-se o Sulfamylon creme e/ou Nitrato de Prata, e os clientes foram divididos em dois subgrupos. Os dados referentes a 1978/79 foram colhidos dos prontuários; os dados referentes a 1980 foram coletados pela pesquisadora mediante observaçäo direta. Os resultados apurados demonstram que ambos os métodos säo eficazes, pois favorecem a cicatrizaçäo e impedem a contaminaçäo. Constatou-se, no entanto, que a aplicaçäo da membrana amniótica é mais eficaz porque, além de evitar a contaminaçäo e facilitar a cicatrizaçäo, alivia a dor e contribui para a antecipaçäo da alta hospitalar.