Toxoplasma gondii: comparison of a rhoptry-ELISA with IFAT and MAT for antibody detection in sera of experimentally infected pigs

Indirect ELISA and IFAT have been reported to be more sensitive and specific than agglutination tests. However, MAT is cheaper, easier than the others and does not need special equipment. The purpose of this study was to compare an enzyme linked immunosorbent assay using crude rhoptries of Toxoplasma gondii as coating wells (r-ELISA) with indirect fluorescence antibody test (IFAT) and modified agglutination test (MAT) to detect anti-T. gondii antibodies in sera of experimentally infected pigs. Ten mixed breed pigs between 6.5 and 7.5 weeks old were used. All pigs were negative for the presence of T. gondii antibodies by IFAT (titre < 16), r-ELISA (OD < 0.295) and MAT (titre < 16). Animals received 7x10(7) viable tachyzoites of the RH strain by intramuscular (IM) route at day 0. Serum samples were collected at days -6, 0, 7, 14, 21, 28, 35, 42, 50, and 57. IFAT detected anti-T. gondii antibodies earlier than r-ELISA and MAT. The average of antibody levels was higher at day 35 in IFAT (Log10=2.9) and in MAT (Log10 = 3.5), and at day 42 in r-ELISA (OD = 0.797). The antibody levels remained high through the 57th day after inoculation in MAT, and there was a decrease tendency in r-ELISA and IFAT. IFAT was used as "gold standard" and r-ELISA demonstrated a higher prevalence (73.3%), sensitivity (94.3%), negative predictive value (83.3%), and accuracy (95.6%) than MAT. Kappa agreements among tests were calculated, and the best results were shown by r-ELISAxIFAT (kappa = 0.88, p < 0.001). Cross-reaction with Sarcocystis miescheriana was investigated in r-ELISA and OD mean was 0.163 +/- 0.035 (n = 65). Additionally, none of the animals inoculated with Sarcocystis reacted positively in r-ELISA. Our results indicate that r-ELISA could be a good method for serological detection of T. gondii infection in pigs.     

Neospora caninum in birds: A review

Neospora caninum is an obligate intracellular protozoan parasite that infects domestic and wild animals. Canids are considered to be definitive hosts since they may shed oocysts into the environment through their feces. The disease is recognized as one of the major causes of bovine abortion worldwide, leading to important economic losses in the dairy and beef cattle industries. Previous studies have reported N. caninum infection in different species of birds; infection in birds has been associated with increased seroprevalence and reproductive problems in dairy cattle. Although the role of birds in the epidemiological cycle of neosporosis is unknown, birds are exposed to infection because they feed on the ground and could thus contribute to parasite dissemination. This review is focused on the current state of knowledge of neosporosis in birds.     

Fermentative profile and lactic acid bacterial dynamics in non-wilted and wilted alfalfa silage in tropical conditions

This study was conducted to evaluate the fermentative profile and microbial populations of wilted and non-wilted alfalfa silages ensiled with or without inoculant and the population dynamics of lactic acid bacteria (LAB) of wilted alfalfa plant and theirs silage. A 2?×?2?×?6 factorial arrangement was used, with the absence or presence of wilting (W), with and without bacterial inoculant (I) and six fermentation periods (P) (1, 3, 7, 14, 28 and 56 days), in a completely randomized design, with three replicates. The alfalfa was slightly wilted for 6 h and increased the dry matter content from 133.9 to 233.4 g/kg. It was performed the cultivation, followed by the isolation of LAB from samples of alfalfa forage before ensiling and its silage only in non-inoculated silages, after different fermentation periods. DNA was extracted from the isolated strains of LAB; the 16S rRNA gene sequences were amplified by PCR and the sequences were compared to those available from the GenBank database. Wilting provided silages with lower pH, ammonia nitrogen and acetic acid concentrations. The wilting process did not alter the amount of LAB; however, it affected the LAB diversity of the silages. The Lactobacillus plantarum was the predominant species in non-wilted and wilted silages.

     

Infants' Peripheral Blood Lymphocyte Composition Reflects Both Maternal and Post-Natal Infection with Plasmodium falciparum

Maternal parasitoses modulate fetal immune development, manifesting as altered cellular immunological activity in cord blood that may be linked to enhanced susceptibility to infections in early life. Plasmodium falciparum typifies such infections, with distinct placental infection-related changes in cord blood exemplified by expanded populations of parasite antigen-specific regulatory T cells. Here we addressed whether such early-onset cellular immunological alterations persist through infancy. Specifically, in order to assess the potential impacts of P. falciparum infections either during pregnancy or during infancy, we quantified lymphocyte subsets in cord blood and in infants'' peripheral blood during the first year of life. The principal age-related changes observed, independent of infection status, concerned decreases in the frequencies of CD4⁺, NK^dim and NKT cells, whilst CD8⁺, Treg and Teff cells'' frequencies increased from birth to 12 months of age. P. falciparum infections present at delivery, but not those earlier in gestation, were associated with increased frequencies of Treg and CD8⁺ T cells but fewer CD4⁺ and NKT cells during infancy, thus accentuating the observed age-related patterns. Overall, P. falciparum infections arising during infancy were associated with a reversal of the trends associated with maternal infection i.e. with more CD4⁺ cells, with fewer Treg and CD8⁺ cells. We conclude that maternal P. falciparum infection at delivery has significant and, in some cases, year-long effects on the composition of infants'' peripheral blood lymphocyte populations. Those effects are superimposed on separate and independent age- as well as infant infection-related alterations that, respectively, either match or run counter to them.     

History of Late Holocene vegetation at Quintana Roo,Caribbean coast of Mexico

A pollen record of a Late Holocene sediment core from the Mexican Caribbean coast (Quintana Roo) shows the development and changes of a mangrove system. Humid conditions seem to have persisted for the period approximately 2500–1500 ¹⁴C yr BP (pollen zone I), and mangrove Rhizophora mangle dominated with a good representation of elements from the nearby semi-evergreen tropical forest. During the period approximately 1500–1200 ¹⁴C yr BP (pollen zone II) the mangrove Conocarpus erecta dominated. R. mangle almost disappeared and other taxa appeared, suggesting drier climatic conditions and generally more open vegetation. This dry period coincided with the period of the Maya cultural decline. The following period (pollen zone III, approximately 1200–1000 ¹⁴C yr BP) was characterized by the recovery of R. mangle, indicating more humid conditions than in the preceding pollen zone. Pollen zone IV (approximately 1000 ¹⁴C yr BP till present) suggests a drier period reoccuring with C. erecta; this marks the transition to present day conditions.     

Microsomal metabolism of dibenz[a,c]anthracene, dibenz[a,h]anthracene and dibenz[a,j]anthracene to bis-dihydrodiols and polyhydroxylated products

Polar, ethyl acetate soluble metabolites formed in incubations of dibenz[a,c]-anthracene (DB[a,c]A), dibenz[a,h]anthracene (DB[a,h]A) and the related DB[a,h]A 3,4-diol and dibenz[a,j]anthracene (DB[a,j]A) with 3-methylcholanthrene (3-MC)-induced rat liver microsomal preparations have been separated by HPLC and examined using fluorescence, UV and NMR spectroscopy. Metabolites with spectral properties consistant with their identification as the 3,4:8,9-bis-diol of DB[a,j]A and a 1,2,3,4,12,13-hexol derived from DB[a,c]A were found. DB[a,h]A was metabolized to three polar products identified as the 3,4:10,11-bis-diol and the related 1,2,3,4,8,9- and 1,2,3,4,10,11-hexols, which were also formed, together with the related 1,2,3,4-tetrol, from the DB[a,h]A 3,4-diol. The possible role of bis-diols in the metabolic activation of these three dibenzanthracenes is discussed.     

Genotoxic effects of Tabebuia impetiginosa (Mart. Ex DC.) Standl. (Lamiales, Bignoniaceae) extract in Wistar rats

Tabebuia sp. is native to tropical rain forests throughout Central and South America. Although the biological and pharmacological effects of bark extracts have been intensely studied, little is known on the extract obtained from the flower. Herein, the genotoxic potential of a flower extract from T. impetiginosa ("ipê roxo") on the blood and liver cells of Wistar rats was evaluated. Experimental procedures involved only male animals. Graduated concentrations of the extract, viz., 100, 300 and 500 mg kg(-1) of body weight, were gavage-administered and 24 h latter cells were collected and processed for analysis. With the exception of the 100 mg kg(-1) dose, a significant increase in DNA damage was noted, when compared with a negative control group. Although the genotoxic potential of this extract was higher in liver cells, the response in both tissues was related to dose-dependency. Even though DNA damage can be corrected before conversion into mutations, further study is recommended to arrive at a better understanding of incurred biological effects.     

Microsomal metabolism of dibenz[a,c]anthracene, dibenz[a,h]anthracene and dibenz[a,j]anthracene to bis-dihydrodiols and polyhydroxylated products

Polar, ethyl acetate soluble metabolites formed in incubations of dibenz[a,c]-anthracene (DB[a,c]A), dibenz[a,h]anthracene (DB[a,h]A) and the related DB[a,h]A 3,4-diol and dibenz[a,j]anthracene (DB[a,j]A) with 3-methylcholanthrene (3-MC)-induced rat liver microsomal preparations have been separated by HPLC and examined using fluorescence, UV and NMR spectroscopy. Metabolites with spectral properties consistant with their identification as the 3,4:8,9-bis-diol of DB[a,j]A and a 1,2,3,4,12,13-hexol derived from DB[a,c]A were found. DB[a,h]A was metabolized to three polar products identified as the 3,4:10,11-bis-diol and the related 1,2,3,4,8,9- and 1,2,3,4,10,11-hexols, which were also formed, together with the related 1,2,3,4-tetrol, from the DB[a,h]A 3,4-diol. The possible role of bis-diols in the metabolic activation of these three dibenzanthracenes is discussed.     

On the influence of point defects on the structural and electronic properties of graphene-like sheets: a molecular simulation study

The influence of vacancies and substitutional defects on the structural and electronic properties of graphene, graphene oxide, hexagonal boron nitride, and boron nitride oxide two-dimensional molecular models was studied using density functional theory (DFT) at the level of local density approximation (LDA). Bond length, dipole moment, HOMO–LUMO energy gap, and binding energy were calculated for each system with and without point defects. The results obtained indicate that the formation of a point defect does not necessary lead to structural instability; nevertheless, surface distortions and reconstruction processes were observed, mainly when a vacancy-type defect is generated. For graphene, it was found that incorporation of a point defect results in a semiconductor–semimetal transition and also increases notably its polar character. As with graphene, the formation of a point defect in a hexagonal boron nitride sheet reduces its energy gap, although its influence on the resulting dipole moment is not as dramatic as in graphene. The influence of point defects on the structural and electronic properties of graphene oxide and boron nitride oxide sheets were found to be mediated by the chemisorbed species.