Mechanisms of insulin secretion in malnutrition: modulation by amino acids in rodent models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acute exercise reverses aged-induced impairments in insulin signaling in rodent skeletal muscle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Regulation of breathing and body temperature of a burrowing rodent during hypoxic-hypercapnia

Burrowing mammals usually have low respiratory sensitivity to hypoxia and hypercapnia. However, the interaction between ventilation (V), metabolism and body temperature (Tb) during hypoxic-hypercapnia has never been addressed. We tested the hypothesis that Clyomys bishopi, a burrowing rodent of the Brazilian cerrado, shows a small ventilatory response to hypoxic-hypercapnia, accompanied by a marked drop in Tb and metabolism. V, Tb and O-2 consumption (VO2) of C. bishopi were measured during exposure to air, hypoxia (10% and 7% O-2), hypercapnia (3% and 5% CO2) and hypoxic-hypercapnia (10% O-2 + 3% CO2). Hypoxia of 7% but not 10%, caused a significant increase in V, and a significant drop in Tb. Both hypoxic levels decreased VO2 and 7% O-2 significantly increased V/VO2. Hypercapnia of 5%, but not 3%, elicited a significant increase in V, although no significant change in Tb, VO2 or V/VO2 was detected. A combination of 10% O-2 and 3% CO2 had minor effects on V and Tb, while VO2 decreased and V/VO2 tended to increase. We conclude that C. bishopi has a low sensitivity not only to hypoxia and hypercapnia, but also to hypoxic-hypercapnia, manifested by a biphasic ventilatory response, a drop in metabolism and a tendency to increase V/VO2. The effect of hypoxic-hypercapnia was the summation of the hypoxia and hypercapnia effects, with respiratory responses tending to have hypercapnic patterns while metabolic responses, hypoxic patterns. (C) 2004 Elsevier B.V. All rights reserved.

Thermoregulation by an Australian murine rodent, the ash-grey mouse (Pseudomys albocinereus)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lobe identity in the Mongolian gerbil prostatic complex: A new rodent model for prostate study

Knowledge of structural and physiological differences among the prostatic lobes (PL) is the basis for development of experimental studies in traditional laboratory rodents. Although Mongolian gerbil reproductive organs have been increasingly investigated, its prostate structure is far from being properly known, and investigations of this organ focused on the ventral lobe (VL). Thus, the present study provides a thorough morphological description of prostatic complex in the male adult gerbil on the basis of topographic, histological, and ultrastructural analysis and ductal branching. Like other rodents, four pairs of PL were observed. However, in contrast to the rat and mouse, the VL is the least voluminous component and the dorsolateral lobe (DLL) is the most prominent and spatially isolated from remaining PL. The occurrence of a dorsal lobe (DL), hidden between bladder and insertion of seminal vesicles, has not been mentioned in previous reports with Mongolian gerbil. Collagenase digestion followed by microdissection revealed that, except for DL, which has a tubularacinar organization, all PL exhibit tubular organization and variable ductal branching. Distinct histological and ultrastructural features such as secretory epithelium, aspect of luminal secretion and stromal organization are reported for each PL and are confirmed by morphometric and stereological methods. Histological sections showed at least three intralobar segments in VL and DL. Ultrastructural analysis evidenced that, although luminal epithelial cells of PL share typical features of exocrine secretory cells, there are striking lobe phenotypical variations. Both merocrine and apocrine pathways are observed in variable rates in all PL, with the predominance of the former in the DLL and the latter in the CG. The morphological observations presented herein point to distinct structural identities for each PL, which probably reflects,specific functional compromise of seminal fluid secretion. These data also point to the gerbil as a good model for investigations concerning the regulation of prostate development and homeostasis, mainly with regard to the dorsal and dorsolateral PL.

Electrochemical genosensors for the detection of Bonamia parasite. Selection of single strand-DNA (ssDNA) probes by simulation of the secondary structure folding

A post-PCR nucleic acid work by comparing experimental data, from electrochemical genosensors, and bioinformatics data, derived from the simulation of the secondary structure folding and prediction of hybridisation reaction, was carried out in order to rationalize the selection of ssDNA probes for the detection of two Bonamia species, B. exitiosa and B. ostreae, parasites of Ostrea edulis.Six ssDNA probes (from 11 to 25 bases in length, 2 thiolated and 4 biotinylated) were selected within different regions of B. ostreae and B. exitiosa PCR amplicons (300 and 304 bases, respectively) with the aim to discriminate between these parasite species. ssDNA amplicons and probes were analyzed separately using the "Mfold Web Server" simulating the secondary structure folding behaviour. The hybridisation of amplicon-probe was predicted by means of "Dinamelt Web Server". The results were evaluated considering the number of hydrogen bonds broken and formed in the simulated folding and hybridisation process, variance in gaps for each sequence and number of available bases. In the experimental part, thermally denatured PCR products were captured at the sensor interface via sandwich hybridisation with surface-tethered probes (thiolated probes) and biotinylated signalling probes. A convergence between analytical signals and simulated results was observed, indicating the possibility to use bioinformatic data for ssDNA probes selection to be incorporated in genosensors. (C) 2011 Elsevier B.V. All rights reserved.

Prevalence and risk factors for Toxoplasma gondii infection in certified and non-certified pig breeding farms in the Toledo microregion, PR, Brazil

A infecção pelo Toxoplasma gondii tem sido diagnosticada em suínos em todo o mundo. Perdas econômicas geralmente estão relacionadas a distúrbios reprodutivos. A infecção pelo Toxoplasma tem também importância em saúde pública, já que cistos teciduais do parasito podem persistir na carne e subprodutos oriundos de suínos, que servirão de fontes de infecção para o ser humano. O objetivo deste trabalho foi verificar a frequência e os fatores de risco associados à infecção pelo Toxoplasma em granjas de reprodutores suídeos certificados ou não da microrregião de Toledo, no Paraná, que inclui os municípios de Toledo, Nova Santa Rosa, São José das Palmeiras e São Pedro do Iguaçú. A frequência relativa de infecção foi 13,4%, sem diferença com o tipo de granja. A análise de regressão logística demonstrou os seguintes fatores associados à infecção: não utilização de funcionários separados por área da granja, o acesso de animais ao cocho de ração e ao reservatório de água, a não utilização de tampa neste reservatório, a não prevenção de roedores, o número e peso médio de leitões ao desmame por porca.

Characterization of an unidentified Sarcocystis falcatula-like parasite from the South American opossum, Didelphis albiventris from Brazil

An unidentified isolate of a Sarcocystis falcatula-like parasite was obtained from the lungs of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally-infected South American opossum, Didelphis albiventris from Brazil. Four captive budgerigars fed sporocysts from the opossum intestine died of acute sarcocystosis 8, 10, and 12 days after oral inoculation (DAI); one budgerigar was killed 12 DAI when it was lethargic. Schizonts and merozoites found in the lungs of the budgerigars reacted mildly with polyclonal S. falcatula antibody. The parasite was isolated in equine kidney cell cultures inoculated with lung tissue from a budgerigar that was killed 12 DAI. Two budgerigars inoculated subcutaneously with 100,000 culture-derived S. falcatula merozoites developed acute sarcocystosis and S. falcatula-like schizonts were found in their lungs 15 and 16 DAI. Four budgerigars kept as unfed controls in the same environment remained free of Sarcocystis infection. The parasite underwent schizogony in African green monkey kidney cells and bovine turbinate cells. Merozoites divided by endopolygeny, often leaving a residual body. Polymerase chain reaction studies using primers JNB33/JNB54 and Hinf I and Dra I digestion indicated that the isolate was not S. falcatula. Results of this study indicated that the South American opossum, D. albiventris, is a definitive host for yet another S. falcatula-like parasite.

Prevalence of Sarcocystis neurona and Neospora spp. infection in horses from Brazil based on presence of serum antibodies to parasite surface antigen

Sera from 961 horses from Brazil were tested for antibodies against the major surface antigens SnSAG4 and NhSAG1 to determine the seroprevalence of Sarcocystis neurona and Neospora hughesi, respectively. Antibodies against SnSAG4 were detected in 669 (69.6%) of the horses, while antibodies against NhSAG1 were detected in only 24 (2.5%) of the horses. These serologic results suggest that there is a high concentration of S. neurona in the environment of Brazil, which results in marked exposure of horses to this parasite. Additionally, the data further confirm that infection with Neospora spp. is relatively uncommon in horses. (c) 2005 Elsevier B.V. All tights reserved.

Purine nucleoside phosphorylase: A potential target for the development of drugs to treat T-cell- and apicomplexan parasite-mediated diseases

Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of nucleosides and deoxynucleosides, generating ribose 1-phosphate and the purine base, which is an important step of purine catabolism pathway. The lack of such an activity in humans, owing to a genetic disorder, causes T-cell impairment, and thus drugs that inhibit human PNP activity have the potential of being utilized as modulators of the immunological system to treat leukemia, autoimmune diseases, and rejection in organ transplantation. Besides, the purine salvage pathway is the only possible way for apicomplexan parasites to obtain the building blocks for RNA and DNA synthesis, which makes PNP from these parasites an attractive target for drug development against diseases such as malaria. Hence, a number of research groups have made efforts to elucidate the mechanism of action of PNP based on structural and kinetic studies. It is conceivable that the mechanism may be different for PNPs from diverse sources, and influenced by the oligomeric state of the enzyme in solution. Furthermore, distinct transition state structures can make possible the rational design of specific inhibitors for human and apicomplexan enzymes. Here, we review the current status of these research efforts to elucidate the mechanism of PNP-catalyzed chemical reaction, focusing on the mammalian and Plamodium falciparum enzymes, targets for drug development against, respectively, T-Cell and Apicomplexan parasites-mediated diseases.

Mebendazole treatment against Anacanthoras penilabiatus (Monogenea, Dactylogyridae) gill parasite of cultivated Piaractus mesopotamicus (Osteichthyes, Characidae) in Brazil. Efficacy and hematology

The present work evaluated the efficacy of mebendazole (MBZ) treatment against infections with the monogenean helminths Anacanthorus penilabiatus, gill parasites of young cultivated pacu, Piaractus mesopotamicus. A short-term bath treatment using 100, 200 and 500 mg MBZ/l of water for 10 and 30 min and a long-term-bath using 1, 10 and 100 mg MBZ/l of water for 24 h were utilized. Seven days after, fish were sacrificed and parasites counted. Concentrations of 500 and 200 mg MBZ/l for 10 and 30 min showed reduced efficacy (0.0 and 0.7%) and (14.2 and 11.0%), respectively. Nevertheless, 100 mg MBZ/l (10 min) and 10 nag MBZ/l (24 h) showed better efficacy (79.6 and 8 1.4%, respectively). Treatments for 24 h provoked increases in hematocrit, hemoglobin concentration and leukocyte number when compared to those untreated fish. Mebendazole treatments also provoked alterations in the defense blood cells especially in lymphocyte and thrombocyte numbers, when the fishes were submitted to 10 and 30 min baths.

Similarities among ectoparasite fauna of sigmodontine rodents: phylogenetic and geographical influences

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Host-parasite relationships in paracoccidioidomycosis

A viewpoint of host-parasite relationships in paracoccidioidomycosis is presented. The characteristics of the fungus which are important to the host-parasite interaction are discussed. Aspects of inhibition of mycelium-to-yeast transformation by estrogens acting at receptors on the fungal wall and in the cytoplasm, and the role of polysaccharide components of the cell wall in virulence are reviewed. The natural mechanisms of host defense are also examined, including phagocytosis, complement system, natural-killer cells and genetic control of resistance and susceptibility. Finally, a discussion of granuloma morphogenesis and its relationship to the humoral and cellular anti-P. brasiliensis immune response is presented.

Henneguya piaractus n.sp. (Myxozoa: Myxobolidae), a gill parasite of Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes: characidae), in Brazil

Henneguya piaractus n.sp. was found from the gill filaments of Piaractus mesopotamicus (Characidae). Fishes were collected during a year from the reservoir at Centro de Aquicultura da UNESP, Jaboticabal, SP, Brazil. The prevalence of this parasite was 97.3% in the gills of farmed fish. Observations on spore development into the cysts were done. Studies with scanning electon microscopy were performed to observe the spore and cyst structure.