Socio-environmental assessment of a landfill using a mixed study design: A case study from México.

Municipal solid waste management is a challenge for local authorities since mismanagement leads to environmental damage and social discontent. The objective of this study was to assess in an integrated manner the socio-environmental situation of a municipal landfill from México, using a design of mixed methods, which considered a quantitative evaluation of physicochemical and microbiological variables measured in leachates, surface and groundwater samples, soil and air, and a qualitative evaluation by in-depth interviews with the near-by inhabitants about their perception of the impacts of the landfill. The results show that leachates polluted the soil and surface water in a radius of up to 500 m from the landfill, but did not reach the groundwater, while the mean concentrations of PM10, Mn, and Ni measured in air samples at the landfill of 146 µg m-3, 0.12 µg m-3, 0.10 µg m-3, respectively, in the dry season and of Mn and Ni of 0.13 µg m-3 and 0.11 µg m-3, respectively, in the rainy season, surpassed permissible limits. From the residents perspective the landfill pollutes soil, water and air and it contributes to vehicle traffic and noise, promotes harmful fauna and disturbs the esthetic view. Air measurements coincide with social perception and in general, the applied mixed study design helped to assess in an integrated manner the socio-environmental concerns and to give advice to improve the current management of the landfill.

Conocimientos, actitudes y factores asociados al consumo de tabaco en estudiantes universitarios de enfermería / Knowledge, attitudes, and factors associated with tobacco use among university nursing students / Conhecimentos, atitudes e fatores associados ao consumo de tabaco em estudantes universitários de enfermagem

Objetivo: Determinar los factores asociados al consumo de tabaco en los estudiantes de la Licenciatura en Enfermería de la Universidad Autónoma del Estado de Morelos. Métodos: Estudio transversal realizado en 481 estudiantes que completaron un cuestionario autoaplicado con características sociodemográficas, consumo de tabaco, actitudes y conocimientos acerca del tabaquismo. Los factores asociados se analizaron con un modelo de regresión logística múltiple. Resultados: La prevalencia de fumadores activos fue de 42.4%. Se presenta mayor prevalencia en estudiantes del primer año (44.3%), que en los de cuarto año (13.9%) de la carrera. Los factores asociados al consumo de tabaco fueron el ser hombre (OR = 1.7; IC 95% (1.0 - 3.0)), ver cigarros sueltos a la venta (OR = 9.4; IC 95% (3.8 - 23.0)), que todos los amigos fumen (OR = 6.0; IC 95% (1.3-27.7)), no estar de acuerdo con prohibiciones de publicidad, así como con lugares para no fumar (OR = 3.2; IC 95% (3.0-5.2)) y cuyos padres no saben si ellos fuman (OR = 6.9; IC 95% (3.2 - 14.6)). Conclusiones: Al avanzar el estudiante en su formación académica se disminuye el consumo de tabaco. Se recomienda la incorporación de temas específicos sobre los efectos del consumo de tabaco en la salud en los contenidos de las asignaturas del programa de Licenciatura en Enfermería, así como la capacitación de los estudiantes en programas de prevención, control y cesación del tabaquismo.

Objective: To determine factors associated with tobacco use among students in the baccalaureate nursing program of the State of Morelos Autonomous University. Methods: This a transversal study with 481 students who answered a self-administered questionnaire on issues of social and demographical characteristics and attitudes and knowledge towards tobacco use. Associated factors were analyzed through a multiple logistic regression model. Results: The overall active smoking prevalence was 42.2%. A higher figure was found in the first year students in comparison to senior students (44.3% vs 13.9%). Some associated factors were: being male (OR = 1.7; CI 95% (1.0 - 3.0)); watching cigarettes being sold (OR = 9.3; CI 95% (3.8 - 23.0)); having all friends being smokers (OR = 6.0; CI 95% (1.3 - 27.7)); being in disagreement with prohibition publicity and smoking-banned places (OR = 3.2; CI 95% (3.0 - 5.2)); and having parents unaware of their sons' smoking habits (OR = 6.9; CI 95% (3.3 - 14.6)). Conclusions: Although students tend to decrease their tobacco use while they progress along their careers, it is recommended to incorporate into nursing baccalaureate programs diverse topic discussions on the health impacts from tobacco smoking in order to train the students in its prevention, control, and withdrawal.

Objetivo: Determinar os fatores associados ao consumo de tabaco nos estudantes da Licenciatura de Enfermagem da Universidad Autónoma del Estado de Morelos. Métodos: Estudo transversal realizado em 481 estudantes que completaram um questionário auto-aplicado com caraterísticas sociodemográficas, consumo de tabaco, atitudes e conhecimentos acerca do tabagismo. Os fatores associados analisaram-se com um modelo de regressão logística múltipla. Resultados: A prevalência de fumadores ativos foi de 42.4%. Apresenta-se maior prevalência em estudantes do primeiro ano (44.3%), quanto nos de quarto ano (13.9%) da carreira. Os fatores associados ao consumo de tabaco foram: o ser homem (OR = 1.7; IC 95% (1.0-3.0)), ver cigarros fracionados à venda (OR = 9.3; IC 95% (3.8 - 23.0)), que todos os amigos fumem, (OR = 6.0; IC 95% (1.3-27.7)), não concordar com proibições de publicidade, assim como com lugares para não fumantes (OR = 3.2; IC 95% (3.0 - 5.2)) e cujos pais não sabem que eles fumam (OR = 6.9; IC 95% (3.3 - 14.6)). Conclusões: Ao avançar o estudante em sua formação académica diminui o consumo de tabaco. Recomenda-se a incorporação de temas específicos sobre os efeitos do consumo de tabaco na saúde dentro dos conteúdos das disciplinas do programa de Licenciatura em Enfermagem, assim como o treinamento dos estudantes em programas de prevenção, controle e suspensão de tabagismo.

High-level expression of NRAMP1 in peripheral blood cells and tuberculous granulomas from Mycobacterium bovis-infected bovines.

By Western blotting, we demonstrate high-level expression of NRAMP1 proteins in peripheral blood cells and granulomas of Mycobacterium bovis-infected bovines. Immunohistochemistry of granulomatous lesions showed heavily labeled epithelioid macrophages and Langhans cells. These data suggest that M. bovis infection enhances NRAMP1 expression and that active tuberculosis can occur despite this response.

Neurotensin-SPDP-poly-L-lysine conjugate: a nonviral vector for targeted gene delivery to neural cells.

We report herein the synthesis of a novel DNA delivery system and in vitro evidence of its ability to transfect cell lines by binding to the high-affinity neurotensin receptor and subsequent internalization of ligand-receptor complexes. The targeting vehicle consisted of neurotensin crosslinked with poly-L-lysine via N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP). The SPDP-derivatives with either neurotensin or poly-L-lysine were purified by gel filtration. The conjugate resulting of the reaction of neurotensin-SPDP with HS-SPDP-poly-L-lysine was purified through Biogel A 1.5. The neurotensin-SPDP-poly-L-lysine conjugate was able to bind plasmidic DNAs (pSV2cat and pGreen Lantern-1) at optimal molar ratios of 1:5 and 1:6 (DNA: conjugate), respectively. The conjugate internalized those plasmids in the cell lines (N1E-115 and HT-29) bearing the high-affinity neurotensin receptor. Expression of the plasmid products, chloramphenicol acetyltransferase and green fluorescent protein, was observed in such cell lines. Both internalization and expression of the plasmids transferred by the neurotensin-SPDP-poly-L-lysine conjugate were prevented by neurotensin (1 microM) and SR-48692 (100 nM), a specific antagonist of the high-affinity neurotensin receptor. The neurotensin-SPDP-poly-L-lysine conjugate was unable to transfect cell lines lacking the neurotensin receptor (COS-7 and L-929). In rat brain, the high-affinity neurotensin receptor is expressed by specific neurons such as those of the nigrostriatal and mesolimbic dopaminergic systems. Therefore, the neurotensin-SPDP-poly-L-lysine conjugate could be a useful tool for gene delivery to those neuronal systems.

Disruption of the Jak1 gene demonstrates obligatory and nonredundant roles of the Jaks in cytokine-induced biologic responses.

Herein we report the generation of mice lacking the ubiquitously expressed Janus kinase, Jak1. Jak1-/- mice are runted at birth, fail to nurse, and die perinatally. Although Jak1-/- cells are responsive to many cytokines, they fail to manifest biologic responses to cytokines that bind to three distinct families of cytokine receptors. These include all class II cytokine receptors, cytokine receptors that utilize the gamma(c) subunit for signaling, and the family of cytokine receptors that depend on the gp130 subunit for signaling. Our results thus demonstrate that Jak1 plays an essential and nonredundant role in promoting biologic responses induced by a select subset of cytokine receptors, including those in which Jak utilization was thought to be nonspecific.

Targeted disruption of the Stat1 gene in mice reveals unexpected physiologic specificity in the JAK-STAT signaling pathway.

The JAK-STAT signaling pathway has been implicated in mediating biological responses induced by many cytokines. However, cytokines that promote distinct cellular responses often activate identical STAT proteins, thereby raising the question of how specificity is manifest within this signaling pathway. Here we report the generation and characterization of mice deficient in STAT1. STAT1-deficient mice show no overt developmental abnormalities, but display a complete lack of responsiveness to either IFN alpha or IFN gamma and are highly sensitive to infection by microbial pathogens and viruses. In contrast, these mice respond normally to several other cytokines that activate STAT1 in vitro. These observations document that STAT1 plays an obligate and dedicated role in mediating IFN-dependent biologic responses and reveal an unexpected level of physiologic specificity for STAT1 action.

Lipopolysaccharide-dependent induction of IL-10 receptor expression on murine fibroblasts.

Although various biologic activities of IL-10 have been identified, little is known about IL-10's molecular mechanism of action. Herein we report the characterization of IL-10R on different murine cell lines and demonstrate the LPS inducibility of this protein. With the use of purified recombinant murine IL-10 and labeled IL-10-specific mAb, IL-10Rs were detected by flow cytometry. Radioligand binding analyses showed that RAW264.7 cells expressed 238 +/- 87 receptors per cell and bound ligand with a single affinity of 8.3 +/- 2.4 x 10(9) M-1. Similar studies documented IL-10R expression on murine B cells (CH27) and CD4+ Th1 cells but not murine Th2 cells, L929 or WA-17 fibroblasts, or fibrosarcoma cells. Exposure of fibroblasts to LPS-induced cellular IL-10 binding activity in a dose- and time-dependent manner. Radioligand binding analyses performed on LPS-treated fibroblasts showed cellular expression of 325 +/- 59 IL-10 binding sites and a binding affinity of Ka = 7.5 +/- 2.5 x 10(8) M-1. RT-PCR analysis confirmed the induction of the IL-10R. Functional analyses of IL-10R-expressing cells revealed that IL-10 activated a cellular transcription factor in RAW264.7 cells that bound a DNA probe containing the IFN-gamma response region from the Fc gamma RI gene. In contrast, IL-10 did not induce gamma response region binding activity in L929 fibroblasts either treated with LPS or transfected with the murine IL-10R cDNA. These results thus indicate that cellular responses to IL-10 may be influenced by both the external environment and the presence of additional signaling components within the cell.

Actin mRNA levels and actin synthesis during the encystation of Entamoeba invadens.

Parasitic amebas propagate among hosts through cysts, the resistant forms in their life cycle. In spite of their key role in infection, little is known about the encystation process and the mechanisms involved in reaching this stage. Two features drastically affected by encystation are motility and cell shape, both of which are determined by the cytoskeleton, composed mainly of actin in these organisms. Therefore, we studied the occurrence and relative levels of actin and actin synthesis during encystation of Entamoeba invadens. Using a cDNA actin probe obtained from a library of E. histolytica and a monoclonal antibody against actin, we found that, while the total actin levels sharply decrease as encystation proceeds, the levels of actin mRNA are reduced only in mature cysts. Moreover, actin synthesis does not take place in precysts and the later stages of cyst formation. In contrast, the levels of other proteins remain stable in trophozoites, precysts and cysts, and stage specific peptides are actively synthesized in precysts. The results indicate the encystation is accompanied by a preferential down-regulation of actin synthesis and a decrease in actin levels. The reorganization of the cytoskeletion occurring as trophozoites transform into round, quiescent cells, could be a regulatory factor in the observed changes.

Characterization of an immuno-dominant variable surface antigen from pathogenic and nonpathogenic Entamoeba histolytica.

A 125-kD surface antigen of Entamoeba histolytica is recognized by 73% of immune sera from patients with amoebic liver abscesses. Using pooled human immune sera a cDNA clone (lambda cM17) encoding this antigen (M17) has been isolated from a lambda gt11 expression library of the virulent stain E. histolytica HM1:IMSS. Monospecific antibodies, purified by binding to phage lysate of lambda cM17, and mAb FA7 reacted exclusively with the 125-kD antigen by Western blot analysis. Surface binding and cap formation are observed with patient sera, purified monospecific antiserum, and mAb FA7. Corresponding genomic clones (pBSgM17-1/2/3) were isolated by hybridization with the cDNA clone. These contained an open-reading frame of 3345 bp, which is in good agreement with the mRNA size of approximately 3.0 kb as revealed by Northern hybridization with lambda cM17. The inferred amino acid sequence predicts a 125,513 dalton protein that contains 17 potential N-linked glycosylation sites and is unusually rich in tyrosine and asparagine residues. A distinctly hydrophobic NH2-terminal region may serve as membrane anchor or signal sequence. In contrast to conservation of an immunodominant epitope recognized in pathogenic and nonpathogenic strains by monoclonal FA7 and human immune sera, amplification and sequence analysis of a 1,4000-bp fragment of this gene from a fresh nonpathogenic isolate by use of the PCR demonstrate regions of significant sequence divergence in this antigen. A 1% sequence variability among different isolates of the pathogenic strain HM1:IMSS and a 12-13% variability between pathogenic and nonpathogenic strains are revealed by comparison to published partial amino acid sequences (Tannich, E., R.D. Horstmann, J. Knobloch, and H.H. Arnold. 1989. Proc. Natl. Acad. Sci. USA. 86:5118). Some restriction enzymes were found that allowed PCR diagnosis of nonpathogenic and pathogenic isolates with the exclusion of E. histolytica-like Laredo, suggesting that a detailed study of nonpathogenic and pathogenic isolates in relation to the M17 antigen sequence will provide a basis of differentiating isolates.

Isoenzyme patterns of Entamoeba histolytica isolates from asymptomatic carriers: use of gradient acrylamide gels.

A vertical polyacrylamide gradient gel (3% to 7%) was designed to facilitate the electrophoretic resolution and classification of isoenzyme patterns of Entamoeba histolytica isolates. The following enzyme systems were used: phosphoglucomutase (PGM), hexokinase (HX), glucosephosphate isomerase (GPI), and malate dehydrogenase (ME). The modifications in the electrophoretic procedure and sample preparation allowed the reproducible comparison of enzyme patterns of axenic, monoxenic, and mixed cultures of E. histolytica isolated from humans. The clear distinction obtained in gradient polyacrylamide gels, between amebic isoenzyme bands and those from bacteria, renders this technique adequate for application to epidemiological studies where mixed cultures are used. The isoenzyme patterns of eight isolates from asymptomatic carriers, rigorously characterized by the absence of clinical, endoscopic, and serological findings were studied and compared with three well characterized pathogenic strains, cultured under axenic conditions. Our observations confirm the existence of distinct isoenzyme patterns for PGM, HX, and GPI in pathogenic and nonpathogenic strains, and reveal the consistent presence of more than one band for GPI. In addition, a previously undescribed band for GPI with an Rf of 0.64 in a carrier strain was found. The results suggest that while carriers usually harbor amebas with nonpathogenic isoenzyme patterns, pathogenic patterns also may be found in carriers.