RESUMEN
O artigo foca nos resultados do último estágio de uma pesquisa sobre as estratégias climáticas de empresas nos setores automotivo e de papel e celulose no Brasil, um país que está se tornando mais e mais importante também em termos de questões relacionadas às mudanças climáticas. No primeiro estágio, um modelo - o Climate Strategy Model (CSM) - foi desenvolvido para verificar se as empresas estavam adotando práticas-chave para assegurar a implementação bem-sucedida de suas estratégias climáticas. No segundo, o CSM foi aplicado em empresas nas indústrias acima mencionadas, escolhidas por causa de seu papel importante na economia do país. No estágio final, entrevistas com executivos destas empresas foram realizadas para identificar as causas raiz das dificuldades na implementação das estratégias climáticas e para capturar informações relevantes na perspectiva internacional.
Asunto(s)
Cambio Climático , Salud Ambiental , Desarrollo Industrial , Estrategias de Salud , Desarrollo Sostenible , Responsabilidad SocialRESUMEN
Papaya ringspot virus (PRSV) is the most important virus affecting papaya and cucurbit plants in tropical and subtropical areas. PRSV isolates are divided into biotypes P and W: both the P and W types naturally infect plants in the family Cucurbitaceae, whereas the P type naturally infects papaya (Carica papaya). Understanding the origin and nature of the PRSV genetic diversity and evolution is critical for the implementation of control strategies based on cross-protection and the deployment of transgenic plants that show resistance to virus isolates highly similar to the transgene. The molecular epidemiology of PRSV was evaluated by analyzing the nucleotide sequence of the capsid protein (CP) and helper component-proteinase (HC-Pro) genes of isolates from around the world, including newly characterized ones from Colombia and Venezuela, using a relaxed molecular clock-based approach and a phylogeographic study. Our results confirm previous estimates on the origin of PRSV around 400 years ago and suggest distinct dispersion events from the Indian Peninsula to the rest of Asia, via Thailand, and subsequently to the Americas. A historical reconstruction of the P- and W-type characters in the phylogenetic study supports the need to revise the hypothesis that PRSV-P derives from PRSV-W since our results suggest that the ancestral state could be either of the two biotypes. Moreover, estimates of epidemic growth predict an increasing genetic diversity of the virus over time that has direct implications for control strategies of PRSV based on cross-protection and the use of transgenic plants.
Asunto(s)
Carica/virología , Cucurbitaceae/virología , Filogeografía , Enfermedades de las Plantas/virología , Potyvirus/clasificación , Potyvirus/genética , Américas/epidemiología , Asia/epidemiología , Proteínas de la Cápside/genética , Cisteína Endopeptidasas/genética , Epidemiología Molecular , Datos de Secuencia Molecular , Potyvirus/aislamiento & purificación , Análisis de Secuencia de ADN , Proteínas Virales/genéticaRESUMEN
Leishmania are protozoan parasites which invade mammalian macrophages and multiply as amastigotes in phagolysosomes (parasitophorous vacuoles). Using L. mexicana and bone marrow-derived macrophages (BMM), the question is addressed whether infected BMM induced to express major histocompatibility complex class II molecules can present defined antigens to specific T helper type 1 cells. As a model antigen, a membrane-bound acid phosphatase (MAP), a minor protein associated with intracellular vesicles in amastigotes, was either overexpressed at the surface of the parasites or overexpressed in a soluble form leading to antigen secretion into the parasitophorous vacuole. Presentation of MAP epitopes by these three types of amastigotes was then compared for macrophages containing live parasites or amastigotes inactivated by drug treatment. It is shown that surface-exposed and secreted MAP can be efficiently presented to T cells by macrophages harboring live amastigotes. Therefore, the parasitophorous vacuole communicates by vesicular membrane traffic with the plasmalemma of the host cell. The intracellular MAP of wild-type cells or the abundant lysosomal cysteine proteinases are not or only inefficiently presented, respectively. After killing of the parasites, abundant proteins such as overexpressed MAP and the cysteine proteinases efficiently stimulate T cells, while wild-type MAP levels are not effective. We conclude that intracellular proteins of intact amastigotes are not available for presentation, while after parasite inactivation, presentation depends on antigen abundance and possibly stability. The cell biological and possible immunological consequences of these results are discussed.
Asunto(s)
Presentación de Antígeno , Antígenos de Protozoos/inmunología , Leishmania mexicana/inmunología , Macrófagos/inmunología , Proteínas de la Membrana/biosíntesis , Linfocitos T/inmunología , Vacuolas/parasitología , Animales , Antígenos de Protozoos/biosíntesis , Femenino , Leishmania mexicana/crecimiento & desarrollo , Activación de Linfocitos , Macrófagos/parasitología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Linfocitos T/parasitología , Vacuolas/inmunologíaRESUMEN
In a previous publication, we described the purification of a membrane-bound acid phosphatase of Leishmania mexicana as a heterogeneously N-glycosylated protein of an apparent molecular mass of 70000-72000 expressed in both the promastigote and the amastigote stage of the parasite [19]. Screening of a genomic DNA library of L. mexicana with degenerate oligonucleotides designed according to the NH2-terminus of the protein led to the cloning of the lmmbap gene, which is present in one copy per haploid genome. The open reading frame predicts a protein of 516 amino acids composed of a signal sequence, a large hydrophilic region, a trans-membrane alpha-helix and a short cytoplasmic tail. The sequence of the hydrophilic region is homologous to acid phosphatases from other organisms. While in wild-type promastigotes, the acid phosphatase is located in the endosomal/lysosomal compartment between the flagellar pocket and the nucleus, overexpression leads to its abundant exposure on the cell surface. In cells transfected with a construct lacking the region corresponding to the trans-membrane and the cytoplasmic parts, the resulting altered acid phosphatase is efficiently secreted into the culture medium. The potential of this system for studies on membrane trafficking in kinetoplastid organisms is discussed.
Asunto(s)
Fosfatasa Ácida/genética , Genes Protozoarios , Leishmania mexicana/genética , Glicoproteínas de Membrana/genética , Orgánulos/enzimología , Fosfatasa Ácida/biosíntesis , Fosfatasa Ácida/aislamiento & purificación , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Secuencia Conservada , Endosomas/enzimología , Técnica del Anticuerpo Fluorescente , Leishmania mexicana/enzimología , Leishmania mexicana/ultraestructura , Lisosomas/enzimología , Glicoproteínas de Membrana/biosíntesis , Glicoproteínas de Membrana/aislamiento & purificación , Microscopía Inmunoelectrónica , Datos de Secuencia Molecular , Pruebas de Precipitina , Proteínas Recombinantes/biosíntesis , Mapeo Restrictivo , Análisis de Secuencia de ADN , Homología de Secuencia de AminoácidoRESUMEN
Amastigotes of the protozoan parasite Leishmania proliferate in phagolysosomes of mammalian macrophages. Propagation of the infection is considered to occur by host-cell rupture and uptake of released parasites by uninfected macrophages. In this study, the kinetics of binding of L mexicana mexicana amastigotes to COS cells and to COS cells transfected with three different macrophage receptors (FcRII-B2, receptor for the Fc-domain of immunoglobulins; CR3, complement type 3 receptor and the mannose receptor) is compared to the rate of adhesion to peritoneal macrophages. Amastigotes isolated from macrophages cultivated in vitro bind with slow, sigmoid kinetics to COS cells expressing either of the three receptors, or to peritoneal macrophages. In contrast, amastigotes isolated from mouse lesions bind with rapid, hyperbolic kinetics to COS cells expressing the Fc receptor or to peritoneal macrophages but with slow, sigmoid kinetics to COS cells expressing the CR3 or the mannose receptor. As shown by immunofluorescence experiments, lesion-derived amastigotes contain host-derived immunoglobulins (Ig) but no complement component 3 at their surface. It is concluded that amastigotes contain no intrinsic ligand at their surface, which enables high-affinity interactions with macrophages. Opsonization by specific Ig may be of relevance in vivo because firstly, in cryosections of mouse lesions extracellular amastigotes containing surface Ig can be detected and, secondly, B cell-deficient mice reconstituted with parasite-specific Ig show a modest increase in the rate of lesion development. In addition, it is shown that amastigotes are internalized by COS cells and grow in large parasitophorous vacuoles similar to those observed in macrophages.
Asunto(s)
Leishmania mexicana/crecimiento & desarrollo , Macrófagos/parasitología , Receptores de Superficie Celular/fisiología , Adhesividad , Animales , Linfocitos B/citología , Línea Celular , Leishmania mexicana/patogenicidad , Recuento de Linfocitos , Ratones , Ratones Endogámicos CBARESUMEN
It is well established that Leishmania mexicana amastigotes contain large amounts of cysteine proteinases in their extended lysosomes. In this study it is shown that the cell-free supernatant of homogenized lesion tissue from infected mice contains large amounts of acid proteinases. The majority of this enzymatic activity also corresponds to cysteine proteinases from L. mexicana amastigotes. Immunoelectron microscopy of mouse lesion sections suggests, that frequently amastigotes lyse and release lysosomal cysteine proteinases into the parasitophorous vacuole of infected macrophages. The cysteine proteinases are also found extracellularly in the tissue presumably as a result of macrophage rupture and appear to persist in the lesion tissue, where they may damage host cells and the extracellular matrix.
Asunto(s)
Cisteína Endopeptidasas/análisis , Leishmania mexicana/enzimología , Leishmaniasis Cutánea/enzimología , Secuencia de Aminoácidos , Animales , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/análisis , Sistema Libre de Células/enzimología , Cisteína Endopeptidasas/inmunología , Cisteína Endopeptidasas/aislamiento & purificación , Electroforesis en Gel de Poliacrilamida , Leishmania mexicana/ultraestructura , Leishmaniasis Cutánea/patología , Lisosomas/parasitología , Lisosomas/ultraestructura , Macrófagos/parasitología , Macrófagos/ultraestructura , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Microscopía Inmunoelectrónica , Datos de Secuencia MolecularRESUMEN
Amastigotes of the protozoan parasite Leishmania proliferate in phagolysosomes of macrophages. They abundantly express glycoinositol phospholipids (GIPLs), which are considered necessary for parasite survival by providing a shield at the surface against lysosomal hydrolases and by serving as receptors for the interaction with host cells. The structures of four GIPLs of L. mexicana amastigotes were characterized by a combination of gas-liquid chromatography-mass spectrometry, methylation linkage analysis and enzymatic treatments. They contain the glycan structures Man alpha 1-3Man alpha 1-4GlcN (iM2), Man alpha 1-6(Man alpha 1-3)Man alpha 1-4GlcN (iM3), Man alpha 1-2Man alpha 1-6(Man alpha 1-3)-Man alpha 1-4GlcN (iM4) and (NH2-CH2CH2-PO4)Man alpha 1-6(Man alpha 1-3)Man alpha 1-4GlcN (EPiM3), which are linked to alkylacyl-phosphatidylinositol. The predominant amastigote GIPL, EPiM3 (approximately 2 x 10(7) molecules/cell), is located at the parasite cell surface, in the flagellar pocket and in lysosomal membranes, but not on host cell structures as shown by immunofluorescence and immunoelectron microscopy. In addition, amastigotes in infected Balb/c mice contain a glycolipid with similar distribution as EPiM3, which has the same characteristics as the Forssman antigen of mammalian cells. In contrast to EPiM3, there is strong evidence that this glycosphingolipid is not synthesized by amastigotes but by macrophages in the lesion. This suggests a mechanism of lipid transfer from the macrophage to the parasite.
Asunto(s)
Antígenos de Protozoos/inmunología , Antígenos de Superficie/inmunología , Antígeno de Forssman/inmunología , Glucolípidos/inmunología , Glicoesfingolípidos/inmunología , Glicosilfosfatidilinositoles/inmunología , Leishmania mexicana/inmunología , Macrófagos/inmunología , Fosfolípidos/inmunología , Animales , Antígenos de Protozoos/biosíntesis , Antígenos de Protozoos/química , Antígenos de Superficie/biosíntesis , Antígenos de Superficie/química , Secuencia de Carbohidratos , Antígeno de Forssman/metabolismo , Glucolípidos/biosíntesis , Glucolípidos/química , Glicoesfingolípidos/metabolismo , Glicosilfosfatidilinositoles/química , Leishmania mexicana/crecimiento & desarrollo , Macrófagos/metabolismo , Macrófagos/parasitología , Ratones , Ratones Endogámicos BALB C , Microscopía Fluorescente , Microscopía Inmunoelectrónica , Datos de Secuencia Molecular , Fosfatidilinositol Diacilglicerol-Liasa , Hidrolasas Diéster Fosfóricas/metabolismoRESUMEN
To assess whether the traditional pediatric prohibition against cosleeping in the parental bed requires reconsideration for urban ethnic minorities, cosleeping and sleep problems were studied in a sample of Hispanic-American, east Harlem, New York City, children 6 to 48 months of age. The incidence of frequent all-night cosleeping was found to be 21%, significantly higher than the documented rate of 6% found in a representative sample of white middle-American urban children of the same age and sex. For occasional cosleeping, however, there were no significant ethnic differences, and frequent part-night cosleeping was significantly less common than noted in the white sample. There were greater ethnic differences for sharing the parental bedroom compared with cosleeping in the parental bed, approximately 80% for Hispanic-Americans vs 10% for the white population. Within the Hispanic-American group, frequent all-night cosleeping was significantly more common among single parents and those living in multiple households and less common among infants and later-born children in the family. Frequent all-night cosleeping was also significantly associated with sleep problems.
Asunto(s)
Hispánicos o Latinos , Relaciones Padres-Hijo , Trastornos del Sueño-Vigilia/epidemiología , Sueño , Preescolar , Estudios de Cohortes , Comparación Transcultural , Femenino , Hispánicos o Latinos/psicología , Humanos , Lactante , Masculino , Ciudad de Nueva York , Puerto Rico/etnología , Padres Solteros/psicología , Factores Socioeconómicos , Población Urbana , Población BlancaRESUMEN
To study teratogenicity of cocaine in humans, we studied three groups of pregnant women and their offspring: group 1, 50 women who abused cocaine only; group 2, 110 women who were polydrug abusers; and group 3, 340 who were drug free. All three groups were similar for socioeconomic status, cigarette smoking, and ethnicity. Maternal age of group 1 was similar to that of group 3, but group 2 mothers were significantly older. Gravidity was significantly higher in groups 1 and 2 compared with group 3. No statistical difference was found in spontaneous abortion rate among the three groups, but the stillbirth rate was significantly higher in group 1 (chi 2 = 6.89, P less than or equal to 0.01). All stillbirths were related to abruptio placentae. Birth weight, length, and head circumference were significantly decreased in infants in groups 1 and 2 compared with group 3 (P less than or equal to 0.0001), but no statistical difference was found between groups 1 and 2. The congenital malformation rate was significantly higher in group 1 compared with group 3 (chi 2 = 7.07, P less than or equal to 0.01). We conclude that cocaine abuse in humans significantly reduces weight of the fetus, increases the stillbirth rate related to abruptio placentae, and is associated with a higher malformation rate.