Stable-isotope analysis: a neglected tool for placing parasites in food webs.

Parasites are often overlooked in the construction of food webs, despite their ubiquitous presence in almost every type of ecosystem. Researchers who do recognize their importance often struggle to include parasites using classical food-web theory, mainly due to the parasites' multiple hosts and life stages. A novel approach using compound-specific stable-isotope analysis promises to provide considerable insight into the energetic exchanges of parasite and host, which may solve some of the issues inherent in incorporating parasites using a classical approach. Understanding the role of parasites within food webs, and tracing the associated biomass transfers, are crucial to constructing new models that will expand our knowledge of food webs. This mini-review focuses on stable-isotope studies published in the past decade, and introduces compound-specific stable-isotope analysis as a powerful, but underutilized, newly developed tool that may answer many unresolved questions regarding the role of parasites in food webs.

CSV-ARG, Estudio multi-céntrico de validación de una escala de detección temprana de deterioro en pacientes internados / CSV-ARG, multicenter study of validation of an early detection scale of deterioration in hospitalized patients

Introducción: La detección precoz de un paciente con riesgo de deterioro, y la intervención temprana por un equipo de salud competente en el manejo de la vía aérea ha demostrado reducir la mortalidad intrahospitalaria. El NEWS (National Early Warning Score, Reino Unido) clasifica a los pacientes según su probabilidad de deterioro dentro de las siguientes doce horas; en baja (0-1), moderada (2-4) y alta posibilidad de deterioro (5-13), a partir de cuatro signos vitales: frecuencias cardíaca y respiratoria, temperatura y presión arterial sistólica sumados a la saturación de oxígeno y el estado de conciencia. Fue generada a partir de una gran base de datos de signos vitales obtenidos de manera electrónica en pacientes internados en Inglaterra. En las instituciones de nuestro país, los signos vitales son tomados manualmente y hay una percepción generalizada de que estos o "están mal tomados" o no se los ubica dentro del centro de la toma de decisiones. Objetivos: El objetivo de este estudio fue, a partir de signos vitales tal como se toman en nuestro medio, realizar una validación de la capacidad de discriminación de la escala NEWS de eventos severos durante la internación. Diseño, materiales y métodos: Ocho instituciones de la ciudad de Buenos Aires y del área metropolitana participaron recolectando de manera consecutiva los seis parámetros vitales que componen la escala NEWS en los pacientes internados, tal como se toman en las salas de internación, además de datos demográficos, presencia de comorbilidades, eventos de gravedad durante la internación como sepsis, trombo embolismo de pulmón, shock hipovolémico, distrés respiratorio, insuficiencia respiratoria, trastorno de la conciencia y muerte sin evento previo. Los datos se ingresaron a una base de datos virtual calculándose el puntaje de la escala NEWS. Se analiza en este primer trabajo las características de la población con medidas de tendencia central y de dispersión estándares según la distribución de los valores. Mediante regresión logística se analizó la capacidad del primer NEWS al ingreso de predecir un evento independientemente de la edad, el sexo y la presencia de comorbilidades. Resultados: Entre el 1 de enero de 2015 hasta el 31 de julio ingresaron en el estudio 1705 pacientes de nueve Instituciones del área metropolitana, 869 eran mujeres (51%), rango de edad 18 a 100. Un 10% de los pacientes presentó algún evento grave, y la mortalidad global fue de 3,5%. El 90% de los pacientes fue clasificado al ingreso como NEWS de bajo grado de deterioro (0-4), el 5% riesgo moderado (5-6) y el 5% de riesgo alto (mayor a 7). El valor de NEWS, al ingreso de la internación y tal como se toman los signos vitales en nuestro medio, predice el riesgo de presentar un evento severo durante la internación, independientemente de la edad, sexo y la presencia de comorbilidades. Discusión: En este estudio pudimos demostrar que los signos vitales, tomados de manera manual calculando la escala NEWS, es un excelente predictor de la ocurrencia de eventos durante la internación. En próximos análisis evaluaremos la capacidad de discriminación y la capacidad de predecir eventos entre 12 y 24 horas posteriores a la toma. (AU)

Background: Early warning scores at hospital settings have shown to reduce hospital mortality. The NEWS (National Early Warning Score, UK), classifies patients as per their risk to deteriorate in three categories, low risk (0-2), moderate risk (3-4) and high risk (5-13). The scale uses four vital signs, heart rate, respiratory rate, temperature and systolic arterial pressure, plus oxygen saturation and conscious state. It was developed and validated using a large database of electronic captured vital signs in England. In Argentina, most of the vital signs are taken manually. (AU)

Parasite-induced oxidative stress in liver tissue of fathead minnows exposed to trematode cercariae.

Although results from field surveys have linked parasites to oxidative stress in their fish hosts, direct evidence involving experimentally infected hosts is lacking. We evaluated the effects of experimental infections with larval trematodes on induction of oxidative stress in fathead minnows, Pimephales promelas. Juvenile fish were exposed in the laboratory to the larvae (cercariae) of 2 species of trematode: Ornithodiplostomum sp. that develops in the liver, and O. ptychocheilus that develops in the brain. For Ornithodiplostomum sp., lipid peroxidation concentration in liver tissue increased 5 days after exposure and remained higher than controls until the end of the experiment at 28 days. For O. ptychocheilus, liver lipid peroxidation concentration was higher than controls at 5 days, but not thereafter. Sustained elevation in lipid peroxidation concentration for the liver trematode may be explained by direct tissue damage caused by developing larvae in the liver, or by an immune response. These experimental results support those from field studies, indicating that the lipid peroxidation assay may be an effective biomonitor for parasite-induced oxidative stress in fish, and that the nature of the oxidative stress response is species and/or tissue specific.

Progenitor cells and TNF-alpha involvement during morphological changes in pancreatic islets of obese mice.

Overnutrition during pregnancy and lactation lend increasing support to the development of obesity and several chronic diseases in adulthood such as type 2 diabetes mellitus, which leads to beta-cell dysfunction and insulin resistance. In this work, we aimed to study the effects of early life overnutrition on the development of obesity, analyzing the morphological changes, expression of TNF-α, and also the stem cell marker CD133 in the pancreatic islets of young and adult mice. Overnutrition during lactation phase was used as an experimental model to induce obesity. The animals were analyzed at 28 and 150 days of age, when pancreata were collected for histological, ultrastructural and western blotting analysis. The results showed that islet hypertrophy is established in obese groups at day 28 and remained until adulthood. CD133+ cells were observed as small cells within pancreatic islets in both control and obese young mice. However, at day 150, these cells were observed only in the islet peripheries and near ducts of the obese group. Furthermore, TNF-α expression in pancreatic islets was increased in both young and adult obese groups when compared to control groups. This work shows interesting data about CD133 receptor and TNF-α roles in the pancreas during obesity development.

Decreased collagen types I and IV, laminin, CK-19 and α-SMA expression after bone marrow cell transplantation in rats with liver fibrosis.

Bone marrow cells have frequently been tested in animal models of liver fibrosis to assess their role in hepatic regeneration. The mononuclear fraction of bone marrow cells is of particular interest, as many studies show that these cells may be beneficial to treat hepatic fibrosis. In this study, we used the bile duct ligation model to induce hepatic fibrosis in an irreversible manner, and rats were treated with bone marrow mononuclear (BMMN) cells after fibrosis was established. Analysis of collagen types I and IV, laminin and α-SMA showed a decreased expression of these proteins in fibrotic livers after 7 days of BMMN cell injection. Moreover, cytokeratin-19 analysis showed a reduction in bile ducts in the BMMN cell-treated group. These results were accompanied by ameliorated levels of hepatic enzymes GPT (Glutamic-pyruvic transaminase), GOT (glutamic-oxaloacetic transaminase) and alkaline phosphatase (AP). Therefore, we showed that BMMN cells decrease hepatic fibrosis by significantly reducing myofibroblast numbers and through reduction of the collagen and laminin-rich extracellular matrix of fibrotic septa and hepatic sinusoids.

Detection and localization of non-HLA-ABC antigenic sites relevant to kidney rejection on endothelial cells.

Immunological rejection of kidney allografts is usually attributed to presensitization to HLA antigens. However, data on HLA identical transplant rejections indicate that non-HLA antigens may also be involved, and it has been suggested that vascular endothelium represents the main target cell. The purpose of the present study is to describe a method of detecting non-HLA antibodies immunocytochemically. We showed the molecular independence between HLA-ABC molecules identified by the monoclonal antibody w6/32, and antigenic sites identified by a kidney rejection patient serum, previously characterized, on cultured endothelial cells isolated from human umbilical cords by collagenase digestion. Single immunofluorescence staining indicated the molecular independence between these antigenic sites, as the first serum showed a granular pattern, diffused throughout the cytoplasm and the other a reticular pattern restricted to the same cytoplasmic region. This result was confirmed by double labeling. Immunoelectronmicroscopy study also confirmed site independence, showing labeling patterns with different intensities and distinct localizations, using 10- and 20-nm colloidal gold particles to reveal HLA-ABC and non-HLA-ABC determinants, respectively. In conclusion, cultured endothelial cells may be used immunocytochemically to detect non-HLA-ABC determinants of antibody reactivity in renal graft recipients, and the indirect immunofluorescence may be the methodology of choice, since it is easy, reliable and low cost.

Do microtubules around the Toxoplasma gondii-containing parasitophorous vacuole in skeletal muscle cells form a barrier for the phagolysosomal fusion?

The intracellular fate of Toxoplasma gondii was studied in primary cultures of skeletal muscle cells (SMC). The labelling of secondary lysosomes with BSA-Au particles showed no phagolysosomal fusion with the vacuole containing the parasite. After internalization of the parasites, the parasitophorous vacuole became involved by closely apposed endoplasmic reticulum (ER) and mitochondria; within 18 h of interaction, microtubules were visualized in association with the parasitophorous vacuole, suggesting that they could form a barrier for the phagolysosomal fusion.

Ultrastructural localization of anionic sites and lectin-binding sites in sarcoid human alveolar macrophages during interaction with T-lymphocytes.

Sarcoidosis alveolitis is caused by an unknown stimulus activating alveolar macrophages (AM) and T-lymphocytes. During antigen presentation, the complex HLA class II molecule/processed peptide, on the surface of sarcoid AM, induces the T-lymphocyte to proliferate. Altered glycosylation patterns of cell surface glycoproteins such as class II molecules in inflammatory states, may enhance the antigen-presenting capability of AM. In order to know if anionic sites and lectin-binding sites take part in the process of antigen presentation by alveolar macrophages, cells obtained from bronchoalveolar lavage of patients with pulmonary sarcoidosis were incubated with cationized ferritin (CF) and colloidal gold complexed lectins (BSL-I-A4; RCA-I; RCA-II; WGA) for 30 min at 4 degrees C. After incubation, the cells were fixed with 4% paraformaldehyde, 2% glutaraldehyde, postfixed, and Epon embedded. The CF particles were uniformly distributed over the entire cell surface of the lymphocyte, and formed clusters on the surface of the macrophage mainly at the adhesion region between the AM and the lymphocytes. We found enhanced binding of BSL-I-A4 by AM, while WGA and RCA were poorly taken up by these cells. Gold-BSL-I-A4 was distributed randomly on the plasma membrane of the AM, and clustered in the adhesion region with lymphocytes. These results suggest that anionic sites and alpha-D-N-acetyl-galactosamine residues labeled with gold-BSL-I-A4 may be involved in the process of antigen presentation by sarcoid alveolar macrophages.