Effects of mercury intoxication on the response of horizontal cells of the retina of thraira fish (Hoplias malabaricus)

Methyl mercury (MeHg) is highly neurotoxic, affecting visual function in addition to other central nervous system functions. The effect of mercury intoxication on the amplitude of horizontal cell responses to light was studied in the retina of the fish Hoplias malabaricus. Intracellular responses were recorded from horizontal cells of fish previously intoxicated with MeHg by intraperitoneal injection (IP group) or by trophic exposure (T group). Only one retina per fish was used. The doses of MeHg chloride administered to the IP group were 0.01, 0.05, 0.1, 1.0, 2.0, and 6.0 mg/kg. The amplitudes of the horizontal cell responses were lower than control in individuals exposed to 0.01 (N = 4 retinas), 0.05 (N = 2 retinas) and 0.1 mg/kg (N = 1 retina), whereas no responses were recorded in the 1.0, 2.0, and 6.0 mg/kg groups. T group individuals were fed young specimens of Astyanax sp previously injected with MeHg corresponding to 0.75 (N = 1 retina), 0.075 (N = 8 retinas) or 0.0075 (N = 4 retinas) mg/kg fish body weight. After 14 doses, one every 5 days, the amplitude of the horizontal cell response was higher than control in individuals exposed to 0.075 and 0.0075 mg/kg, and lower in individuals exposed to 0.75 mg/kg. We conclude that intoxication with MeHg affects the electrophysiological response of the horizontal cells in the retina, either reducing or increasing its amplitude compared to control, and that these effects are related to the dose and/or to the mode of administration.

Immunohistochemical characterization of the chick marginal retina

The retina is a highly differentiated tissue with a complex layered structure that has been extensively characterized. However, most of the previous studies focused on the histology of the central retina while little is known about the cellular composition, organization and function of the marginal retina. Recent research has identified a subpopulation of multipotential progenitor cells in the marginal regions of the retina, closest to the ciliary body ("ciliary marginal zone"). These cells are capable of differentiation in response to an appropriate stimulus. Thus, it is possible that the structure and composition of the marginal retina are distinct from those of the central retina to accommodate the potential addition of newly formed neurons. To characterize the cellular profile of the chick marginal retina, we labeled it immunohistochemically for markers whose staining pattern is well established in the central retina: calbindin, calretinin, protein kinase C, and choline acetyltransferase. Calbindin was present at very low levels in the marginal retina putative photoreceptor layer. Calretinin-positive horizontal cells were also sparse close to the ciliary marginal zone. The bipolar cells in the marginal outer plexiform layer were positive for anti-protein kinase C antibodies, but the density of labeling was also decreased in relation to the central retina. In contrast, the marginal starburst cholinergic amacrine cell pattern was very similar to the central retina. From these data we conclude that the structure of the marginal retina is significantly different from that of the central retina. In particular, the expression of late retina markers in the marginal retina decreased in comparison to the central retina.

Hitchhiking Trypanosoma cruzi minicircle DNA affects gene expression in human host cells via LINE-1 retrotransposon

The horizontal transfer of Trypanosoma cruzi mitochondrial minicircle DNA to the genomes of naturally infected humans may play an important role in the pathogenesis of Chagas disease. Minicircle integrations within LINE-1 elements create the potential for foreign DNA mobility within the host genome via the machinery associated with this retrotransposon. Here we document integration of minicircle DNA fragments in clonal human macrophage cell lines and their mobilization over time. The movement of an integration event in a clonal transfected cell line was tracked at three months and three years post-infection. The minicircle sequence integrated into a LINE-1 retrotransposon; one such foreign fragment subsequently relocated to another genomic location in association with associated LINE-1 elements. The p15 locus was altered at three years as a direct effect of minicircle/LINE-1 acquisition, resulting in elimination of p15 mRNA. Here we show for the first time a molecular pathology stemming from mobilization of a kDNA/LINE-1 mutation. These genomic changes and detected transcript variations are consistent with our hypothesis that minicircle integration is a causal component of parasite-independent, autoimmune-driven lesions seen in the heart and other target tissues associated with Chagas disease.

Horizontal pressures in cylindrical metal silos and comparison with different international standards

The focus of this research was to evaluate the horizontal pressures on a cylindrical metal silo of corrugated walls and flat bottom with 1.82m diameter and 5.4m high, and to compare the values with those obtained theoretically by the ISO 11697, EP 433 and AS 3774 standards. The silo was symmetrically filled and constant speed with wheat cv. soft red for two different height/diameter ratios (H/D) and was unloaded through three orifices with a diameter of 71.6mm, one concentric and two eccentrics. Horizontal pressures were measured on the walls of the silo at three positions using hydraulic type pressure cells. The results showed that shortly after the start of the unloading, there was a mass flow above the quota of H/D = 1.2, whereas below this quota funnel flow occurred. It can be said that the EP 433 standard was more appropriate to predict horizontal pressures in silos in H/D ratio = 1.0, with eccentric unloading. For the H/D ratio = 1.5, AS 3774 standard was the one that produced values closer to the experimental.

Horizontal projections of area 17 in Cebus monkeys: metric features, and modular and laminar distribution

Metric features and modular and laminar distributions of intrinsic projections of area 17 were studied in Cebus apella. Anterogradely and retrogradely labeled cell appendages were obtained using both saturated pellets and iontophoretic injections of biocytin into the operculum. Laminar and modular distributions of the labeled processes were analyzed using Nissl counterstaining, and/or cytochrome oxidase and/or NADPH-diaphorase histochemistry. We distinguished three labeled cell types: pyramidal, star pyramidal and stellate cells located in supragranular cortical layers (principally in layers IIIa, IIIb a, IIIb ß and IIIc). Three distinct axon terminal morphologies were found, i.e., Ia, Ib and II located in granular and supragranular layers. Both complete and partial segregation of group I axon terminals relative to the limits of the blobs of V1 were found. The results are compatible with recent evidence of incomplete segregation of visual information flow in V1 of Old and New World primates

A política externa do Brasil no século XXI: os eixos combinados de cooperação horizontal e vertical

Avaliando a primeira década do século XXI, a política externa do Brasil tem passado por uma evolução significativa caracterizada por uma posição internacional e projeção de poder assertiva, dinamizando parcerias estratégicas com países desenvolvidos e emergentes. O objetivo deste artigo é analisar as prioridades desta agenda e os potenciais relacionados a estes esforços de cooperação bi e multilateral horizontal e vertical.

Cooperação horizontal Sul-Sul: arranjos de concertação política entre a Índia, o Brasil e a África do Sul

Este trabalho busca examinar o desempenho político da concertação internacional entre a Índia, o Brasil e a África do Sul a partir do comportamento das políticas externas dos países concertados. A hipótese é de que o desempenho político eficiente de uma concertação internacional entre Estados Intermediários depende de políticas externas assertivas e alinhadas na busca por atingir as preferências (metas institucionais) de sua concertação, dimensionadas aqui para avaliação no âmbito de instituições internacionais como a Organização das Nações Unidas e a Organização Mundial do Comércio.

Study on the growth promoting capacity of calf and fetal bovine serum for animal cells "in vitro" II: electrophoretic study and survey on the antiproteolytic activity of pools of calf and fetal bovine serum

Calf serum and fetal bovine serum present great variability as to its growth promoting efficiency (GPE). As supplement of culture media to cultivate cells of animal origin they stimulate the "in vitro" multiplication and maintain cell viability. When fourteen lots of calf sera of variable GPE had the total protein contents as well as the percentages of serum fractions determined, no significant differences that could possibly explain the variability of the GPE were observed. Evaluation of the antiproteolytic activity of nineteen lots of calf serum and eighteen serum lots of younger calves showed that the former exhibited lower antiproteolytic titers (1:40 to 1:80) than the latter (1:80 to 1:160). Twelve lots of fetal bovine serum studied in parallel, showed the highest concentration of antiproteolytic factors, with titers equal to 1:320. Sera of bovine origin, but not fetal sera, are usually heat-inactivated, what was demonstrated to be responsible for the decrease of the antiproteolytic activity of 75% of the lots tested. This could explain the inability of certain heat-inactivated sera in promoting multiplication of some cells "in vitro", as verified with primary monkey kidney cells. The results obtained in this study indicated the convenience of submiting each lot of serum to be introduced in cell culture to previous determination of its characteristics, such as growth promoting efficiency, antiproteolytic activity and also toxicity, absence of extraneous agents, etc., in order to minimize the possibility of using serum lots of questionable quality, thus preventing not only the loss of cell lines, but also undesirable and sometimes expensive delays.

Effect of scorpion toxin on the enterochromaffin-like cells in normal and Trypanosoma cruzi-infected rats: a morphological study

Intravenous injection of scorpion toxin (Tityus serrulatus) in normal and Trypanosoma cruzi infected rats did not cause ultrastructural morphologic changes on enterochromaffin-like (ECL) cells of the stomach, although it induced a significant increase of the gastric secretion. Our data seem to indicate that gastric ECL cells structure is not affected by stimulation with scorpion toxin or by acute infection with T. cruzi in the rat.

OBTENTION OF RABIES ANTIGEN THROUGH BHK21 CELLS ADHERED TO MICROCARRIERS

Four rabies antigen batches were produced from virus suspensions resulting from BHK21 cells adhered to microcarriers (Cytodex 1), inoculated and cultured in a bioreactor. In parallel the methodology of production of rabies virus through cultures of BHK21 cells in monolayers in bottles was used. The results obtained showed that infecting titles were 106.69 DL50/mL and 107.28 DL50/mL for suspensions cultured in bottles and in the bioreactor, respectively. The viral suspension volumes collected were on average 11,900 per batch from the bioreactor and 800mL per bottle. Ten horses were immunized with the antigen produced in the bioreactor. The means of antirabies antibody titers found were 240 and 212 IU/mL after the initial and the first booster doses, respectively. Rabies antigen with satisfactory infecting titers can be obtained on a large scale by culturing in a bioreactor inoculated BHK21 cells adhered to microcarriers.

IL-2 AND IFN-g, BUT NOT IL-4 SECRETION BY PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMC) ARE RELATED TO CD4+ T CELLS AND CLINICAL STATUS IN BRAZILIAN HIV-1-INFECTED SUBJECTS

It has been reported that production of IL-2 and IFN-g, known as T-helper type 1 cytokines, by peripheral mononuclear cells (PBMC) decreases with progression of HIV infection. In contrast, IL-4 and IL-10 production, Th2 cytokine profile, increases with HIV disease progression. PBMC were evaluated from 55 HIV-infected subjects from Divisão de Imunologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, to "in vitro" cytokines production after 24 hours of stimulation with PHA. Low levels of IL-4 production in both HIV- infected patients and normal subjects, were detected. The patients with CD4+ T cell counts <200 showed a significant decrease of IL-2 and IFN-g production compared to controls. Patients with higher counts of CD4+ T cells (either between 200-500 or >500 cells/mm3) also showed decreased production of IL-2 that was not statistically significant. There was a correlation between IL-2 and IFN-g release with CD4+ T cells counts. HIV-1-infected individuals with CD4+ T cells >500 cells/mm3 showed increased levels of IL-2 and IFN-g, than individuals with CD4+ T cells <500 cells/mm3. In conclusion, we observed a decline of IL-2 and IFN-g production at advanced HIV disease. IL-4 production was not affected during HIV infection. Taken together, these findings suggest that the cytokine profile might be influenced by the HIV infection rather than the cause of disease progression.

Experimental infection and horizontal transmission of Bartonella henselae in domestic cats

In order to study B. henselae transmission among cats, five young cats were kept in confinement for two years, one of them being inoculated by SC route with B. henselae (10(5) UFC). Only occasional contact among cats occurred but the presence of fleas was observed in all animals throughout the period. Blood culture for isolation of bacteria, PCR-HSP and FTSZ (gender specific), and BH-PCR (species-specific), as well as indirect immunofluorescence method for anti-B. henselae antibodies were performed to confirm the infection of the inoculated cat as well as the other naive cats. Considering the inoculated animal, B. henselae was first isolated by blood culture two months after inoculation, bacteremia last for four months, the specific antibodies being detected by IFI during the entire period. All contacting animals presented with bacteremia 6 months after experimental inoculation but IFI did not detect seroconversion in these animals. All the isolates from these cats were characterized as Bartonella (HSP and FTSZ-PCR), henselae (BH-PCR). However, DNA of B. henselae could not be amplified directly from peripheral blood by the PCR protocols used. Isolation of bacteria by blood culture was the most efficient method to diagnose infection compared to PCR or IFI. The role of fleas in the epidemiology of B. henselae infection in cats is discussed.