Percolation of straight slots on a square grid.

This work is devoted to the emergence of a connected network of slots (cracks) on a square grid. Accordingly, extensive Monte Carlo simulations and finite-size scaling analysis have been conducted to study the site percolation of straight slots with length l measured in the number of elementary cells of the grid with the edge size L. A special focus was made on the dependence of the percolation threshold p_{C}(l,L) on the slot length l varying in the range 1≤l≤L-2 for the square grids with edge size in the range 50≤L≤1000. In this way, we found that p_{C}(l,L) strongly decreases with increase of l, whereas the variations of p_{C}(l=const,L) with the variation of ratio l/L are very small. Consequently, we acquire the functional dependencies of the critical filling factor and percolation strength on the slot length. Furthermore, we established that the slot percolation model interpolates between the site percolation on square lattice (l=1) and the continuous percolation of widthless sticks (l→∞) aligned in two orthogonal directions. In this regard, we note that the critical number of widthless sticks per unit area is larger than in the case of randomly oriented sticks. Our estimates for the critical exponents indicate that the slot percolation belongs to the same universality class as standard Bernoulli percolation.

Unraveling the effects on lithium-ion cathode performance by cation doping M-Li2CuO2 solid solution samples (M = Mn, Fe and Ni).

Cation doping is one of the most dynamic strategies to enhance the electrochemical properties of cathode materials for lithium-ion batteries. Nevertheless, the maximum partial substitution capacity depends on the solubility of each metal ion, and so the formation of impurities is a very common consequence. Thus, the correlation between electrochemical performance and the doping effect is frequently unknown. In this study, the effect of the partial substitution of copper by manganese, iron or nickel in Li2CuO2 is evaluated, as well as the effect on the electrochemical performance of the modified Li2CuO2 samples as lithium ion battery cathode materials. XRD characterization confirmed single phase formation for all samples, and the incorporation of the transition metal in the Li2CuO2 structure was evaluated by XRD profile fitting, EPR and 7Li-NMR. The results showed modifications in intra- and inter-chain interactions, associated with the variations in the Cu-O-Cu bond angle and changes in magnetic order, due to the presence of the doping transition metal. Among all samples, only manganese partial substitution reveals a drastic improvement in the electrochemical stability during the charge/discharge processes even at potentials higher than 3.9 V. It was corroborated that the higher stability is attributed to (i) the increase in the superexchange interactions between the copper sites and manganese, directly modifying lithium diffusivity and electronic conductivity, both inferred from dynamic thermogravimetric analysis for CO2 sorption and conductivity tests, respectively and (ii) the lower propensity to enable O2 evolution during several charge cycles. These results are totally attributed to manganese cation partial substitution, which has a huge impact on the utilization of copper-based materials in real applications.

Apoptosis of peritoneal leucocytes during early stages of Fasciola hepatica infections in sheep.

Several immunomodulatory properties have been described in Fasciola hepatica infections. Apoptosis has been shown to be an effective mechanism to avoid the immune response in helminth infections. The aim of the present work was to study apoptosis in peritoneal leucocytes of sheep experimentally infected with F. hepatica during the early stages of infection. Five groups (n=5) of sheep were used. Groups 2-5 were orally infected with 200 metacercariae (mc) and sacrificed at 1, 3, 9 and 18days post-infection (dpi), respectively. Group 1 was used as the uninfected control (UC). Apoptosis was detected using three different methods 1) immunocytochemistry (ICC) with a polyclonal antibody anti-active caspase-3; 2) an annexin V flow cytometry assay using the Annexin V-FITC/propidium iodide (PI); and 3) transmission electron microscopy (TEM). The differential leucocyte count revealed that the majority of peritoneal granulocytes were eosinophils, which increased significantly at 9 and 18 dpi with respect to the uninfected controls. The ICC study revealed that the percentage of caspase-3+ apoptotic peritoneal leucocytes increased significantly from 3 dpi onwards with respect to the uninfected controls. The flow cytometry annexin V assay detected a very significant (P<0.001) increase of apoptotic peritoneal macrophages, lymphocytes and granulocytes, which remained higher than in the UC until 18 dpi. Transmission electron microscopy studies also confirmed the presence of apoptosis in peritoneal eosinophils at 18 dpi. This is the first report of apoptosis induced by F. hepatica in the peritoneal leucocytes of sheep in vivo. The results of this work suggest the importance of apoptosis induction for the survival of the juvenile parasites in the peritoneal migratory stages of infection.

Toxoplasma gondii in ruminant species (cattle, sheep, and goats) from southern Spain.

Seroprevalences of Toxoplasma gondii antibodies were assessed with the use of a commercial indirect ELISA in 1,501 domestic ruminants in southern Spain. Antibodies against T. gondii were detected in 420 (83.3%) of 504 cattle, 248 (49.3%) of 503 sheep, and 124 (25.1%) of 494 goats. The herd seroprevalence was 100% (72/72), 84.7% (61/72), and 72.2% (52/72) for cattle, sheep, and goats, respectively. Seropositivity was significantly higher in herds with a low density of animals (P < 0.001). Significant differences (P < 0.05) among municipalities were also found. The seroprevalence observed in the present study indicates a widespread exposure to T. gondii in livestock in southern Spain.

Purification and characterization of a galactose-specific lectin from corn (Zea mays) coleoptile.

We purified and characterized a lectin from the corn coleoptyle (Zea mays). The lectin (CCL) was purified by affinity chromatography on a Lactosyl-Sepharose 4B column. It is a glycoprotein of 88.7 kDa, composed mainly by glutamic, aspartic, glycine, and Ser residues; in a minor proportion, it contained methionine and cysteine residues. Carbohydrates that constituted 12% of the total weight comprised galactose, mannose, and N-acetyl-D-glucosamine. The lectin contained the blocked amino-terminus. Analysis of the lectin, determined from peptides obtained after trypsin digestion by MALDI-TOF (matrix-assisted laser desorption ionization-time of flight), indicated that CCL has 18% homology with a putative calcium-dependent Ser/Thr protein kinase, from Arabidopsis thaliana, and 39% homology with a NADPH-dependent reductase from Z. mays. The lectin showed hemagglutinating activity toward several erythrocytes, including human A, B, and O. Hapten inhibition assays indicated that the lectin interacts specifically with the OH on C4 from galactose residues. OH- on C1 plays a relevant role in the interaction with CCL, since beta-galactose residues are better recognized than those from the anomeric alpha-galactose. Lack of lectin activity was observed in corn extracts; the highest specific activity was obtained from coleoptyle obtained at the 7th day after seeding.

Pathological and immunohistochemical study of the liver and hepatic lymph nodes in goats infected with one or more doses of Fasciola hepatica.

Lesions produced by Fasciola hepatica in the liver, gall-bladder and hepatic lymph nodes (HLNs) of four groups of five goats are described; in addition, the distribution of CD3+ T lymphocytes and IgG-lambda light chain-bearing cells was analysed in the hepatic lesions and HLNs. One group of goats received a single oral dose of metacercariae, but the other four groups received four or five doses at different intervals over a period of 11 weeks. Animals that survived were killed 53-55 weeks after the first infective dose. Goats were more susceptible to multiple doses than to a single dose, even when the total number of metacercariae was the same. This greater susceptibility was manifested by the occurrence of deaths and the severity of hepatic lesions. CD3+ lymphocytes were sparse in the infiltrate surrounding the acute migratory tracts, suggesting inhibition of the local cell-mediated immune response. Goats with numerous hepatic calcareous granulomas showed the most severe hepatic damage, including marked cirrhosis, with a striking infiltrate of CD3+ T lymphocytes and lambda IgG- plasma cells, replacing extensive areas of hepatic parenchyma, in which hypertrophy of the smooth endoplasmic reticulum of hepatocytes was evident. These findings were observed mainly in the goats given more than one infective dose.

Triclabendazole treatment in experimental goat fasciolosis: anthelmintic efficacy and influence in antibody response and pathophysiology of the disease.

A controlled test of the efficacy of triclabendazole against all stages (early immature, late immature and mature) of Fasciola hepatica has been performed in experimentally infected goats. The influence of triclabendazole treatment on the pathophysiology of the disease, in terms of haematological parameters and serum enzyme levels, and in the dynamics of production of specific antibodies to excretory/secretory products (ESP) of F. hepatica were also examined. Goats were orally infected with 200 viable metacercarie and treated at 4, 8 and 16 weeks postinfection (PI) with triclabendazole at the dose rate of 10 mg kg-1 body weight. The drug can be regarded as highly effective against mature (100%) and late immature (99.2%) flukes and effective against early immature flukes (94.9%). A moderate anaemia was found associated with the presence of late immature and mature flukes in bile ducts. Treatment with triclabendazole, by eliminating most of these flukes, largely reduced haematological alterations. Serum levels of the enzymes aspartate aminotransferase, lactate dehydrogenase and gamma-glutathione transferase reflected hepatic damage during goat fasciolosis. Early treatment (at 4 weeks PI) prevents the development of both parenchyma and bile ducts lesions; treatment at 8 weeks PI only prevents bile ducts lesions and treatment at 16 weeks PI has no appreciable effect on the development of the main hepatic lesions. The antibody response to F. hepatica ESP, as measured by enzyme-linked immunosorbent assay, was also affected by treatment with triclabendazole. In all treated animals a peak in antibody levels was observed between weeks 9 and 13, followed by a drop whose magnitude depended on the efficacy of treatment. In those animals in which triclabendazole was highly effective, antibody levels fell back to negative values similar to those recorded preinoculation at 18-21 weeks PI.

Lectin activity from the cattle tick (Boophilus microplus) saliva.

The capability of Boophilus microplus saliva (BmS) and lectins to induce immunosuppression in mice and to agglutinate erythrocytes from distinct animal species were compared. CD-1 mice were distributed into groups (two for each substance) of 4-5 animals/group and treated intraperitoneally (i.p.) with 50 mg and 150 mg of BmS; concanavalin A (Con A); potato's lectin (PL), striped bean lectin (SBL) or 0.1 ml of phosphate buffered saline (PBS). All mice were immunized i.p. with 2 x 108 sheep erythrocytes (SE) 48 hours after treatment. Five days after immunization sera was obtained from mice to determine anti-SE antibody titer by direct hemagglutination. The mean antibody titers (Log2) obtained was 5.5 and 4.2 for BmS, 4.4 and 0 for Con A, 5.2 and 4.8 for PL, 4.6 and 0 for SBL and 7.4 for PBS. BmS and lectins were tested to agglutinate mouse (M), rat (Rt), rabbit (Rb), sheep (S) and human A (HA), human B (HB) and human O (HO) erythrocytes. BmS agglutinated Rb, S, HA, HB and HO erythrocytes at titer (Log2) of 1, 1, 6, 1 and 2 respectively. Con A and PL agglutinated erythrocytes from all species tested, while SBL agglutinated M, S and HA erythrocytes. A 50% inhibition of agglutination of HA erythrocytes by BmS was observed when D(+) Galactosamine and D(+) Glucosamine, at 0.2 M, were used. The results obtained indicate that BmS contains a weak nonspecific lectin which is inhibited by aminated sugars, and that induces immunosuppression in mice as other lectins.

Detection of antibodies of Fasciola hepatica excretory--secretory antigens in experimentally infected goats by enzyme immunosorbent assay.

An ELISA with excretory-secretory (ES) antigens has been evaluated as a technique for the early detection of specific antibodies in Fasciola hepatica infections in goats. Goats were experimentally infected with 100 or 200 metacercariae of bovine origin and serum samples were taken periodically over 365 days. The ELISA test was performed with ES antigens (10 micrograms mL-1), a single dilution of sera (1:800) and anti-goat IgG conjugate (1:1000). ES specific antigens were detected in all infected goats between 15 and 30 days postinfection (PI) and maximum antibody levels were reached at 90 days PI. Positive antibody levels (significantly different from those of controls) were still found at 365 days PI. No significant differences were observed between goats infected with 100 or 200 metacercariae. In all infected goats, eggs appeared in faeces between 60 and 90 days PI. ELISA with ES antigens could be a feasible method for the early diagnosis of goat fasciolosis.

Comparison of neonatal nurse practitioners, physician assistants, and residents in the neonatal intensive care unit.

OBJECTIVE: To compare patient care delivery by neonatal nurse practitioners and physician assistants with that of pediatric residents in the intensive care setting. DESIGN: Retrospective chart review after developing specific performance criteria, namely, patient management, outcome, and charges. METHODS/MATERIALS: Charts for 244 consecutive admissions to a neonatal intensive care unit in Jacksonville, Fla, were reviewed. Patients were cared for by one of two teams, one staffed by residents and the other by neonatal nurse practitioners and physician assistants. Similar patients were cared for by the two teams, as determined by patient background characteristics and diagnostic variables. Performance of the two teams was assessed by comparison of patient management, outcome, and charges. Management variables included data on length of critical care and hospital stay, ventilator and oxygen use, total parenteral nutritional use, number of transfusions, and the performance of various procedures. Outcome variables included the incidence of air leaks, bronchopulmonary dysplasia, intraventricular hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, retinopathy of prematurity, and number of infants who died. Charge variables included hospital and physician charges. MAIN RESULTS: Results demonstrated no significant differences in management, outcome, or charge variables between patients cared for by the two teams. CONCLUSION: Neonatal nurse practitioners and physician assistants are an effective alternative to residents for patient care in the neonatal intensive care unit.

Immunological and histological study of T- and B-lymphocyte activity in canine visceral leishmaniosis.

Lymphocyte activity during canine leishmaniosis was studied by histological and immunological methods in experimental and natural infections. Eight dogs were inoculated with 5 x 10(7) promastigotes of Leishmania infantum, LEM 75, zimodeme MON-1, and maintained for 110 days post-infection. Another eight dogs with advanced natural infection were identified by parasitological and serological methods. Three techniques were used: the lymphocyte transformation test (LTT) to study T-cell activity, immunofluorescence assay and enzyme-linked immunosorbent assay to measure antibody production (B-cell activity), and methyl green-pyronin staining to assess tissue responses of lymphocytes. There was a noticeable B-cell response, reflected both histologically and immunologically. High percentages of activated lymphocytes and plasma cells were evident in lymphoid organs and production of specific antibodies was seen throughout the infection. LTT results showed a T-cell unresponsiveness during canine leishmaniosis. These same immunohistological features were observed, although to different degrees, in both experimental and natural infections.

[The seroprevalence of human toxoplasmosis in Córdoba]. / Seroprevalencia de la toxoplasmosis humana en Córdoba.

A seroprevalency study of human toxoplasmosis was carried out in Córdoba, using indirect immunofluorescence and indirect hemagglutination. The sample of people interviewed was made up of 443 serums, 356 supposedly healthy people (mainly students) and 87, considered "high risk" (patients from the "Reina Sofia" Hospital). The positiveness obtained for the total of the sample was 43.79% with IFI and 53.59% for HAI. As regards sex of the person tested, prevalence is higher in women, with 54.36% and 70.47% with IFI and HAI respectively, in men the scores were 38.43% and 44.90% for the same tests. As far as the origin of the sample was concerned, there were 31.18% with IFI and 43.25% for HAI of the normal population, in the "high risk" sample, for both tests it was 95.40%. With both tests there are significative differences in low amounts, but not in high dilutions. We conclude that human toxoplasmosis is present and widespread in the studied population.