Publications by authors named "Silvia Gonzalez Monteiro"

29 Publications

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Involvement of ectonucleotidases and purinergic receptor expression during acute Chagas disease in the cortex of mice treated with resveratrol and benznidazole.

Purinergic Signal 2021 Jul 24. Epub 2021 Jul 24.

Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil.

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi. CD affects people worldwide, primarily in tropical areas. The central nervous system (CNS) is an essential site for T. cruzi persistence during infection. The protozoan may pass through the blood-brain barrier and may cause motor and cognitive neuronal damage. Once in the CNS, T. cruzi triggers immune responses that the purinergic system can regulate. Treatment for CD is based on benznidazole (BNZ); however, this agent has negative side-effects and is toxic to the host. For this reason, we investigated whether resveratrol (RSV), a potent antioxidant and neuroprotective molecule, would modulate purinergic signaling and RSV alone or in combination with BNZ would prevent changes in purinergic signaling and oxidative damage caused by T. cruzi. We infected mice with T. cruzi and treated them with RSV or BNZ for 8 days. Increases in ATP and ADP hydrolysis by NTPDase in the total cortex of infected animals were observed. The treatment with RSV in infected group diminished ATP, ADP, and AMP hydrolysis compared to infected group. The combination of RSV + BNZ decreased AMP hydrolysis in infected animals compared to the INF group, exerting an anti-inflammatory effect. RSV acted as a neuroprotector, decreasing adenosine levels. Infected animals presented an increase of P2X and A density of purine receptors. RSV reduced P2X and A and increased A1 density receptors in infected animals. In addition, infected animals showed higher TBARS and reactive oxygen species (ROS) levels than control. RSV diminished ROS levels in infected mice, possibly due to antioxidant properties. In short, we conclude that resveratrol could act as a neuroprotective molecule, probably preventing inflammatory changes caused by infection by T. cruzi, even though the mice experienced high levels of parasitemia.
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http://dx.doi.org/10.1007/s11302-021-09803-9DOI Listing
July 2021

In vitro and in vivo trypanocidal activity of a benzofuroxan derivative against Trypanosoma cruzi.

Exp Parasitol 2021 Jun 12:108125. Epub 2021 Jun 12.

Department of Microbiology and Parasitology, Federal University of Santa Maria, Santa Maria, RS, Brazil.

Chagas disease, caused by Trypanosoma cruzi, is a major public health problem and is described as one of the most neglected diseases worldwide. It affects about 6-7 million people. Currently, only two drugs are available for the treatment of this disease: nifurtimox and benznidazole. However, both drugs are highly toxic and have several side effects, which lead many patients to discontinue treatment. Moreover, these compounds show a significant curative efficacy only in the acute phase of the disease. Therefore, searching for new drugs is necessary. The objective of this study was to evaluate the in vitro and in vivo activity of a benzofuroxan derivative (EA2) against T. cruzi, and to evaluate the hematological and biochemical changes induced by its treatment in animals infected with T. cruzi. The results were then compared with those of healthy controls. In vitro testing was first performed with T. cruzi epimastigote forms. In this experiment, EA2 was diluted at three different concentrations (0.25, 0.50, and 1%). In vitro evaluation of the trypanocidal activity was performed 24, 48, and 72 h after incubation. In vivo assays were performed using three different doses (10, 5, and 2,5 mg/kg). Mice were divided into 10 groups (five animals/group), wherein four groups comprised non-infected animals (A, G, H, I) and six groups comprised infected animals (B, C, D E, F, J). Groups B and J represented the negative and positive controls, respectively. Groups G, H, and I were used to confirm that EA2 was not toxic to non-infected animals. Parasitemia was measured in infected animals and the hematological and biochemical profiles (urea, creatinine, albumin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) were evaluated in all animals. EA2 demonstrated in vitro trypanocidal activity at all concentrations tested. Although it did not demonstrate a curative effect in vivo, EA2 was able to retard the onset of parasitemia, and significantly reduced the parasite count in groups D and E (treated with 5 and 2.5 mg/kg, respectively). EA2 did not induce changes in hematological and biochemical parameters in non-infected animals, demonstrating that it is not toxic. However, further assessments should aim to confirm the safety of EA2 since this was the first in vitro and in vivo study conducted with this molecule.
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http://dx.doi.org/10.1016/j.exppara.2021.108125DOI Listing
June 2021

Resveratrol impacts in oxidative stress in liver during Trypanosoma cruzi infection.

Microb Pathog 2021 Apr 18;153:104800. Epub 2021 Feb 18.

Department of Biochemistry and Molecular Biology, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil; Department in Animal Science, Universidade do Estado de Santa Catarina (UDESC), Chapecó, SC, Brazil. Electronic address:

Trypanosoma cruzi is the causative agent of Chagas disease, infecting the heart, intestines and liver tissues. There is growing evidence that oxidative stress, defined as a persistent imbalance between highly oxidative compounds and antioxidant defenses, is a marker of tissue inflammation; it is related to immune responses such as damage, as well as to strand breaks in DNA contributing to disease progression. Antioxidant agents help mitigate the damage caused by inflammation, preventing or slowing damage to cells caused by free radicals. In this sense, resveratrol (RSV) is an important polyphenol that demonstrates antioxidant effects. It reverses damage caused by several infectious diseases. The aim of the present study was to determine whether treatment with RSV would prevent or minimize oxidative damage caused by T. cruzi. The animals were divided into four groups (n = 5): A) control; B) control + RSV; C) infected and D) infected + RSV. The infected groups received 1 x 10 Y strain trypomastigotes via intraperitoneal injection; after confirmation of infection, the mice received RSV 100 mg/kg for seven days orally. On the 8th day post-infection, we collected liver tissue for analysis of oxidant/antioxidant status: superoxide dismutase (SOD), catalase (CAT), and glutathione s-transferase (GST) activities, as well as reactive oxygen species (ROS), non-protein thiols (NPSH), thiols, carbonyl protein, thiobarbituric acid reactive substance (TBARS), and finally, the nitrite/nitrate ratio (NOx) levels were determined. The administration of RSV did not exert direct effect on parasitemia. The infection produced high levels of TBARS, NOx, and ROS levels in liver tissue, suggesting cellular injury with production of free radicals in animals infected by T. cruzi. RSV positively modulated SOD and aumenting GST activities enzymes in infected animals. Protein thiols levels in infected animals were lower than those of control. Taken together, the data suggest T. cruzi causes hepatic oxidative stress, and RSV 100 mg/kg for seven days it's dosen't seem minimized these negative effects in the acute phase of disease.
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http://dx.doi.org/10.1016/j.micpath.2021.104800DOI Listing
April 2021

Nematocidal Effect of Oyster Culinary-Medicinal Mushroom Pleurotus ostreatus (Agaricomycetes) against Haemonchus contortus.

Int J Med Mushrooms 2020 ;22(11):1089-1098

Universidade Federal de Santa Maria, Programa de Pós-graduação em Medicina Veterinária, Santa Maria, Rio Grande do Sul, Brasil.

The nematocidal effect of Pleurotus ostreatus (white variety of oyster mushroom) aqueous extract (AE) was evaluated against Haemonchus contortus eggs and infective larvae (L3) in vitro and in artificially infected gerbils (Meriones unguiculatus). The chemical analyses indicated that constituents of AE are tridecanoic, tetradecanoic, linolelaidic, 9,15-octadecadienoic, and oxalic acids. P. ostreatus extract inhibited larval hatching by 100% at the concentration of 2.24 mg/mL and (50% effective concentration) EC50 of 0.73 mg/mL. In the larval development test, AE induced a larvicidal effect at the concentration of 50 mg/mL and EC50 of 17.24 mg/mL. The larval migration test revealed a reduction of 94.7% at a concentration of as low as 4 mg/mL and EC50 of 1.25 mg/mL. No significant effects of treatment with P. ostreatus AE were seen on H. contortus in the gerbil model. Thus, our results demonstrate an important nematocidal in vitro effect of P. ostreatus AE against the parasite H. contortus. However, further investigations are necessary to confirm the anthelmintic potential of P. ostreatus extract in small ruminants.
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http://dx.doi.org/10.1615/IntJMedMushrooms.2020036364DOI Listing
July 2021

Nanobiopesticides: development and inseticidal activity of nanoemulsions containing lemongrass or eucalyptus oils.

Nat Prod Res 2020 Dec 12:1-6. Epub 2020 Dec 12.

Laboratory of Nanotechnology, Universidade Franciscana, Santa Maria, Brazil.

The bioinsecticides, like essential oils, are a promising alternative in pest control. However, these oils have some limitations, such as instability and low solubility. These limitations can be circumvented through nanotechnology, with the nanoemulsification of these compounds. Therefore, the objective of this study was to prepare, characterize and explore the insecticidal activity against adult flies of nanoemulsions containing essential oil of lemongrass or eucalyptus. The nanoemulsions were prepared by the high-energy method and presented droplet size smaller than 125 nm, with polydispersity index of 0.2, pH acid and spherical morphology. The insecticidal activity was evaluated by the Topical Application Method and Exposure Impregnated Paper Exposure, where it was possible to demonstrate a potential insecticidal effect of lemongrass oil in the concentrations of 10, 30 and 50 µL/mL against and and the potentiation of this effect when nanoemulsified this oil against .
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http://dx.doi.org/10.1080/14786419.2020.1837809DOI Listing
December 2020

Adulticidal Activity of Melaleuca alternifolia (Myrtales: Myrtaceae) Essential Oil With High 1,8-Cineole Content Against Stable Flies (Diptera: Muscidae).

J Econ Entomol 2020 08;113(4):1810-1815

Department of Microbiology and Parasitology, Federal University of Santa Maria-UFSM, Santa Maria, RS, Brazil.

The stable fly, Stomoxys calcitrans (Linnaeus 1758), is a hematophagous fly responsible for causing loss of performance in horses, causing losses in cattle productivity, and impacting the animals' health through the spread of pathogenic microorganisms. The objective of this work was to investigate the insecticidal activity of essential oil obtained from Melaleuca alternifolia (Cheel), presenting high 1,8-cineole content, against S. calcitrans adults. Insecticidal activity was determined using surface application methods and exposure to oil impregnated paper. It was observed that treatments at 25 and 50 μg/cm2 (P < 0.05) present fumigant activity through exposure to the impregnated paper, and in the first 15 min of exposure, the mortality rates obtained for these treatments were, respectively (96.6 ± 3.3% and 100%), equivalent to the positive control. Using the superficial application method, the only treatment concentration presenting adulticidal action was 5% (w/v) (P < 0.05). Respective toxicities LC50 (%, w/v) and LC80 for the impregnated paper method were 1.06 ± 0.02 and 1.47 ± 0.17; for the superficial application method, they were 3.82 ± 0.65 and 5.53 ± 0.74. As demonstrated, M. alternifolia essential oil presents adulticidal potential against S. calcitrans.
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http://dx.doi.org/10.1093/jee/toaa117DOI Listing
August 2020

Litomosoides silvai (Nematoda: Onchocercidae) parasitizing Akodon montensis (Rodentia: Cricetidae) in the southern region of Brazil.

Rev Bras Parasitol Vet 2017 Oct-Dec;26(4):433-438. Epub 2017 Oct 23.

Instituto de Biología Subtropical - IBS, Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Puerto Iguazú, Misiones, Argentina.

In the present study, Litomosoides silvai parasitizing Akodon montensis in the southern region of Brazil is reported for the first time. New morphological information is provided for some structures of this nematode species, such as a flattened cephalic extremity, presence of two dorsal cephalic papillae, female tail with a constriction at its tip, "s" shaped vagina, spicules characteristic of the carinii species group and microfilaria tail constricted at the tip. This nematode was found parasitizing the thoracic cavity with a prevalence of 10% (2/20), mean intensity of 4 (6/2), mean abundance of 0.4 (8/20) and range of infection of 2-6 specimens per host, in southern Brazil. This occurrence of L. silvai in A. montensis is a new geographical record for southern Brazil, in the Upper Paraná Atlantic Forest ecoregion of the northwestern region of Rio Grande do Sul, which is part of the Atlantic Forest biome.
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http://dx.doi.org/10.1590/S1984-29612017060DOI Listing
September 2018

Dermatitis by Cheyletus eruditus in man.

Vet Parasitol Reg Stud Reports 2017 Aug 20;9:63-64. Epub 2017 Apr 20.

Department of Microbiology and Parasitology, Universidade Federal Santa Maria, Brazil.

The Cheyletidae mites are known to cause injuries in animals, but their presence causing skin diseases in humans is not often reported. These diagnoses can be difficult because of the small size of the mites (0.2 to 1.6mm) and the lack of an investigation of the environment, often resulting in misdiagnosis. This paper aims to describe the presence of a Prostigmata mite, of the Cheyletidae family, Cheyletus eruditus parasitizing humans in a residence in the central region of the state of Rio Grande do Sul, Brazil.
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http://dx.doi.org/10.1016/j.vprsr.2017.04.001DOI Listing
August 2017

Avian antibodies (IgY) against Trypanosoma cruzi: Purification and characterization studies.

J Immunol Methods 2017 10 8;449:56-61. Epub 2017 Jul 8.

Department of Microbiology and Parasitology, Universidade Federal Santa Maria - UFSM, Santa Maria, Rio Grande do Sul, Brazil. Electronic address:

Trypanosoma cruzi is a flagellated protozoan belonging to the Trypanosomatidae family, the etiologic agent of Chagas disease. Currently, there is neither a licensed vaccine nor effective treatment, characterizing an unmet clinical need. The IgY refers to the egg yolk immunoglobulin (Y=yolk) and its production and use are subjects of many studies due to the diversity of its diagnostic and therapeutic applications. Several researchers have shown that the use of specific IgY may prevent and/or control infectious and parasitic diseases. Based on these evidences, the aim of this study was to immunize chickens with trypomastigotes of T. cruzi in order to produce highly effective and pure antibodies (IgY), as well as extract, characterize, quantify, and verify cytotoxic effects of IgY anti-T. cruzi. After the induction of IgY production by chickens, the eggs were collected and the IgY was extracted by method of precipitation of polyethylene glycol 6000. The IgY anti-T. cruzi characterization was performed using polyacrylamide gel electrophoresis (SDS-PAGE), western-blot and enzyme-linked immunosorbent assay (ELISA). Moreover, the cytotoxic or proliferative effects of IgY anti-T. cruzi was verified by MTT assay. The concentration of IgY in yolk was 8.41±1.47mg/mL. The characterization of IgY reveled bands of stained peptides with molecular weight between 75 and 50kDa and 37 and 25kDa. In the ELISA test was observed that there was antigen-antibody reaction throughout the sample period. The concentrations of 1, 5 and 10mg/mL of IgY anti-T. cruzi presented no cytotoxic of proliferative effects in mononuclear and VERO cells in vitro. The results indicated that T. cruzi is able to generate a high production of specific immunoglobulins in chickens, it did not cause damage to the cell membrane and no proliferative effect.
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http://dx.doi.org/10.1016/j.jim.2017.07.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7126890PMC
October 2017

Antimicrobial, antitrypanosomal and antibiofilm activity of Equisetum hyemale.

Microb Pathog 2016 Dec 14;101:119-125. Epub 2016 Nov 14.

Oral Microbiology Research Laboratory, Microbiology and Parasitology Department, Universidade Federal de Santa Maria (UFSM), Santa Maria, Brazil.

This study evaluates, for the first time, the antibiofilm, antimicrobial and antiparasitic potential of crude extract and fractions of stems of Equisetum hyemale against several infectious agents (bacteria, fungi, Mycobacterium and Trypanosomes) by broth microdilution technique and investigates the phenolic composition of the plant by high performance liquid chromatography. The crude extract and fractions showed antimicrobial activity, as they were capable of inhibiting the growth of bacteria in minimal inhibitory concentrations (MICs) ranging from 52.4 mg/mL to 3.27 mg/mL. For Candida species, the MICs ranged from 52.4 mg/mL to 6.5 mg/mL, and for Mycobacterium species from 2.5 mg/mL to 0.625 mg/mL. The dichloromethane fraction was able to reduce 83% of Pseudomonas aeruginosa biofilm formation and 51% of Candida albicans biofilms. The n-butanol fraction presents an important protozoal effect, reducing 100% of Trypanosoma evansi trypomastigotes after 9 h of exposure. The HPLC analysis revealed that the major substances are rosmarinic acid in dichloromethane fraction (7.38 ± 0.08 mg/g FS) and chlorogenic acid in ethyl acetate fraction (8.4 ± 0.26 mg/g FS). The crude extract and fractions of E. hyemale can be both useful and effective agents as a sustainable alternative for the treatment and prevention of several infectious agents.
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http://dx.doi.org/10.1016/j.micpath.2016.11.008DOI Listing
December 2016

Multiparasitism in a wild cat (Leopardus colocolo) (Carnivora: Felidae) in southern Brazil.

Rev Bras Parasitol Vet 2016 Jul-Sep;25(3):374-7. Epub 2016 Aug 25.

Laboratório de Parasitologia Veterinária, Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brasil.

Parasitic diseases reflect the health and balance of ecosystems, affecting not only individuals but also entire populations or communities. The aim of this study was to report on the diversity of parasitic helminths detected in the feces of a wild feline in southern Brazil. Parasites were obtained from fecal samples, and four techniques were used for parasitological examination: direct examination, centrifugal flotation with zinc sulfate (Faust technique), simple sedimentation (Hoffman technique) and Baermann-Moraes. The parasites were identified through micrometry and morphology, as follows: Ancylostoma sp., Toxocara sp., Trichuridae, Aelurostrongylus abstrusus, Alaria sp., and Spirometra sp. We recorded the genus Ancylostoma parasitizing L. colocolo for the first time.
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http://dx.doi.org/10.1590/S1984-29612016047DOI Listing
May 2018

Production, purification and therapeutic potential of egg yolk antibodies for treating Trypanosoma evansi infection.

Vet Parasitol 2014 Aug 28;204(3-4):96-103. Epub 2014 May 28.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria (UFSM), Brazil. Electronic address:

The use of avian antibodies has aroused interest in biomedical research due to the numerous advantages compared to mammal's antibodies. Our study aimed to produce and purify IgY immunoglobulins in order to use as an alternative therapy against Trypanosoma evansi. Every 14 days, four New Hampshire chickens were immunized with trypomastigotes of T. evansi, totaling five inoculations. Eggs were collected during 70 days and the extraction of IgY was performed by precipitation through the PEG-6000 method. Characterization and purification of IgY anti-T. evansi were carried out by SDS-PAGE and Western blot, where heavy and light chains were detected. The production of IgY was noted during the whole period, and the average production was 2.87 ± 0.14 at the end of this study. Sample's titration allowed the quantification of specific IgY anti-T. evansi, with antibodies produced showing high avidity indexes. The results indicated that T. evansi is able to generate an immune response in poultry, resulting in a production of specific antibodies. In vivo test showed that IgY treatment resulted in increase of prepatent period, longevity and survival of infected animals, when compared with the positive control, demonstrating an initial, but no curative, trypanocidal activity.
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http://dx.doi.org/10.1016/j.vetpar.2014.05.032DOI Listing
August 2014

Liposomes produced by reverse phase evaporation: in vitro and in vivo efficacy of diminazene aceturate against Trypanosoma evansi.

Parasitology 2014 May 28;141(6):761-9. Epub 2014 Jan 28.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria (UFSM), Brazil.

This study aimed to develop and test the in vitro and in vivo effectiveness of diminazene aceturate encapsulated into liposomes (L-DMZ) on Trypanosoma evansi. To validate the in vitro tests with L-DMZ, the efficacy of a commercial formulation of diminazene aceturate (C-DMZ) was also assessed. The tests were carried out in culture medium for T. evansi, at concentrations of 0.25, 0.5, 1, 2 and 3 μg mL(-1) of L-DMZ and C-DMZ. A dose-dependent effect was observed for both formulations (L-DMZ and C-DMZ), with the highest dose-dependent mortality of trypomastigotes being observed at 1 and 3 h after the onset of tests with L-DMZ. The results of in vivo tests showed the same effects in the animals treated with L-DMZ and C-DMZ in single doses of 3.5 mg kg(-1) and for 5 consecutive days (3.5 mg kg(-1) day(-1)). It was possible to conclude that T. evansi showed greater in vitro susceptibility to L-DMZ when compared with C-DMZ. In vivo tests suggest that treatment with the L-DMZ and C-DMZ showed similar efficacy in vivo. The potential of the formulation developed in this study was clearly demonstrated, as it increased the efficacy of the treatment against trypanosomosis, but more studies are needed to increase the effectiveness in vivo.
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http://dx.doi.org/10.1017/S0031182013002114DOI Listing
May 2014

Role of acute phase proteins in the immune response of rabbits infected with Trypanosoma evansi.

Res Vet Sci 2013 Aug 22;95(1):182-8. Epub 2013 Feb 22.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Santa Maria - RS, Brazil.

The aim of this study was to characterize the response of acute phase proteins (APP) in rabbits experimentally infected with Trypanosoma evansi (T. evansi), and to relate the findings with serum immunoglobulins levels, in order to verify the relation between APP and the immune response of rabbits. A total of 12 animals were used in this experiment and divided into 2 groups, control and infected, of six rabbits each. The experimental period was 118 days, and blood was collected on days 0, 5, 20, 35, 65, 95 and 118 post-infection (PI). The infection with T. evansi stimulated APP and immunoglobulins production, once the infected animals showed an increase in C-reactive protein, haptoglobin, alpha 2-macroglobulin and IgM levels. The elevation in IgM levels observed in this study, when related to the increase in C-reactive protein and haptoglobin levels, suggests the involvement of these proteins in host defense against flagellated protozoa, with possible participation in the control of the parasitemia in rabbits infected with T. evansi.
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http://dx.doi.org/10.1016/j.rvsc.2013.01.029DOI Listing
August 2013

Meta-analysis of the performance variation in broilers experimentally challenged by Eimeria spp.

Vet Parasitol 2013 Sep 24;196(1-2):77-84. Epub 2013 Jan 24.

Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, Brazil; Departamento de Zootecnia, Universidade Federal de Santa Maria, Brazil.

A meta-analysis was carried out to (1) study the relation of the variation in feed intake and weight gain in broilers infected with Eimeria acervulina, Eimeria maxima, Eimeria tenella, or a Pool of Eimeria species, and (2) to identify and to quantify the effects involved in the infection. A database of articles addressing the experimental infection with Coccidia in broilers was developed. These publications must present results of animal performance (weight gain, feed intake, and feed conversion ratio). The database was composed by 69 publications, totalling around 44 thousand animals. Meta-analysis followed three sequential analyses: graphical, correlation, and variance-covariance. The feed intake of the groups challenged by E. acervulina and E. tenella did not differ (P>0.05) to the control group. However, the feed intake in groups challenged by E. maxima and Pool showed an increase of 8% and 5% (P<0.05) in relation to the control group. Challenged groups presented a decrease (P<0.05) in weight gain compared with control groups. All challenged groups showed a reduction in weight gain, even when there was no reduction (P<0.05) in feed intake (adjustment through variance-covariance analysis). The feed intake variation in broilers infected with E. acervulina, E. maxima, E. tenella, or Pool showed a quadratic (P<0.05) influence over the variation in weight gain. In relation to the isolated effects, the challenges have an impact of less than 1% over the variance in feed intake and weight gain. However, the magnitude of the effects varied with Eimeria species, animal age, sex, and genetic line. In general the age effect is superior to the challenge effect, showing that age at the challenge is important to determine the impact of Eimeria infection.
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http://dx.doi.org/10.1016/j.vetpar.2013.01.013DOI Listing
September 2013

Iron metabolism and its relationship to anemia and immune system in Trypanosoma evansi infected rats.

Exp Parasitol 2013 Mar 25;133(3):357-64. Epub 2012 Dec 25.

Department of Small Animals, Universidade Federal de Santa Maria, Brazil.

The aim of this study was to evaluate biochemical parameters of iron metabolism in rats experimentally infected with Trypanosoma evansi. To this end, 20 rats (Wistar) were intraperitoneally inoculated with blood containing trypomastigotes 10(6) (Group T) and 12 animals were used as negative control (Group C) and received saline (0.2 mL) through same route. Blood samples were collected by cardiac puncture on day 5 (C5, T5) and 30 (C30, T30) post-inoculation (pi) to perform complete blood count and determination of serum iron, transferrin, ferritin, total and latent iron fixation capacity, transferrin saturation and prohepcidin concentration. Also, bone marrow samples were collected, to perform Pearls staining reaction. Levels of iron, total and latent iron binding capacity and prohepcidin concentration were lower (P<0.05) in infected rats (T5 and T30 groups) compared to controls. On the other hand, levels of transferrin and ferritin were higher when compared to controls (P<0.05). The transferrin saturation increased on day 5 pi, but decreased on day 30 pi. The Pearls reaction showed a higher accumulation of iron in the bone marrow of infected animals in day 5 pi (P<0.01). Infection with T. evansi in rats caused anemia and changes in iron metabolism associated to the peaks of parasitemia. These results suggest that changes in iron metabolism may be related to the host immune response to infection and anemic status of infected animals.
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http://dx.doi.org/10.1016/j.exppara.2012.12.010DOI Listing
March 2013

Rangelia vitalii: changes in the enzymes ALT, CK and AST during the acute phase of experimental infection in dogs.

Rev Bras Parasitol Vet 2012 Jul-Sep;21(3):243-8

Department of Small Animals, Federal University of Santa Maria, Santa Maria, RS, Brazil.

Rangelia vitalii is a protozoon that causes diseases in dogs, and anemia is the most common laboratory finding. However, few studies on the biochemical changes in dogs infected with this protozoon exist. Thus, this study aimed to investigate the biochemical changes in dogs experimentally infected with R. vitalii, during the acute phase of the infection. For this study, 12 female dogs (aged 6-12 months and weighing between 4 and 7 kg) were used, divided in two groups. Group A was composed of healthy dogs (n = 5); and group B consisted of infected animals (n = 7). Blood samples were collected on days 0, 10, 20 and 30 after infection, using tubes without anticoagulant to obtain serum and analyze the biochemical parameters. An increase in alanine aminotransferase (ALT) on day 20 (P < 0.05) was observed. Also, increased creatine kinase (CK) and aspartate aminotransferase (AST) levels were observed throughout the experimental period (P < 0.05). No changes in the serum gamma-glutamyltransferase, urea and creatinine levels were observed. Thus, is possible to conclude that experimental infection with R. vitalii in dogs causes changes to the biochemical profile, with increased ALT, AST and CK enzyme levels.
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http://dx.doi.org/10.1590/s1984-29612012000300012DOI Listing
November 2013

Trypanocidal activity of human plasma on Trypanosoma evansi in mice.

Rev Bras Parasitol Vet 2012 Jan-Mar;21(1):55-9

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria-UFSM, Prédio 20, Sala 4232, Campus Universitário, Camobi, CEP 97105-900, Santa Maria, RS, Brasil.

This study aimed to test an alternative protocol with human plasma to control Trypanosoma evansi infection in mice. Plasma from an apparently 27-year-old healthy male, blood type A+, was used in the study. A concentration of 100 mg.dL(-1) apolipoprotein L1 (APOL1) was detected in the plasma. Forty mice were divided into four groups with 10 animals each. Group A comprised uninfected animals. Mice from groups B, C and D were inoculated with a T. evansi isolate. Group B was used as a positive control. At three days post-infection (DPI), the mice were administered intraperitoneally with human plasma. A single dose of 0.2 mL plasma was given to those in group C. The mice from group D were administered five doses of 0.2 mL plasma with a 24 hours interval between the doses. Group B showed high increasing parasitemia that led to their death within 5 DPI. Both treatments eliminated parasites from the blood and increased the longevity of animals. An efficacy of 50 (group C) and 80% (group D) of human plasma trypanocidal activity was found using PCR. This therapeutic success was likely achieved in the group D due to their higher levels of APOL1 compared with group C.
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http://dx.doi.org/10.1590/s1984-29612012000100011DOI Listing
August 2012

Meta-analysis of the effects of endoparasites on pig performance.

Vet Parasitol 2011 Sep 21;181(2-4):316-20. Epub 2011 Apr 21.

Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, Brazil.

A meta-analysis was carried out in order to study the effects of endoparasites on the performance of growing pigs. Criteria that should be considered for the publication selection were: (1) the health challenge caused by parasites; (2) pig in growing phase; (3) presentation of the nutritional composition of the diets and (4) animal performance. Meta-analysis followed three sequential analysis: graphical, correlation and variance-covariance. The group that were infected with parasites had an average daily feed intake 5% lower than that the control group (2044 vs. 2147 g d(-1); P<0.001), their average daily weight gain was also 31% lower (665 vs. 987 g d(-1); P<0.001) and their feed conversion ratio was 17% superior than that of the control group (3.07 vs. 2.62; P<0.001). The variance decomposition demonstrated that 59% of the reduction in weight gain was explained by the reduction in their feed intake, as well as a 6% reduction being due to parasites.
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http://dx.doi.org/10.1016/j.vetpar.2011.04.029DOI Listing
September 2011

Cryopreservation of Trypanosoma evansi after DEAE-cellulose purification: Evaluation of infective parameters.

Res Vet Sci 2011 Apr 9;90(2):257-9. Epub 2010 Jun 9.

Universidade do Estado de Santa Catarina, Laboratório de Bioquímica de Hemoparasitas e Vetores - LABHEV, Avenida Luiz de Camões, n° 2090, Bairro Conta Dinheiro Lages 88520-000, SC, Brazil.

Cryopreservation is a method of keeping parasites alive in a laboratory. However, this technique may also damage the parasite. Alternatively, parasites may be maintained by in vitro culture. Unfortunately, for Trypanosoma evansi no effective medium that is able to maintain the parasite for more than 4 months has been described. In this study, we examined the effect of purifying trypomastigote through DEAE-cellulose chromatography before and after cryopreservation, by analyzing the pre-patent period, longevity, parasitemia, and count of viable parasites. Our results showed a three-times increase in the concentration of viable trypomastigote in DEAE-purified cryopreserved parasites as compared to non-DEAE-purified cryopreserved parasites. This indicates that DEAE-cellulose chromatography followed by cryopreservation is an effective method for the storage and preservation of T. evansi, with the advantage that the stocked parasites will be ready to use in molecular biology procedures.
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http://dx.doi.org/10.1016/j.rvsc.2010.05.021DOI Listing
April 2011

Serum proteinogram of cats experimentally infected by Trypanosoma evansi.

Prev Vet Med 2010 Jul 4;95(3-4):301-4. Epub 2010 May 4.

Small Animals Department, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.

This study was aimed at evaluating the electrophoretic profile of serum proteins in Trypanosoma evansi-infected cats during different periods of infection. Thirteen adult females non-breeding Felis catus were separated into two groups. Animals from the infected group (n=7) were inoculated intraperitoneally with a strain of T. evansi; whereas, animals from the control group (n=6) received a physiological solution. Blood samples were collected at days 0, 7, 21, and 35 for total protein evaluation and protein fractionation by electrophoresis. Albumin (P<0.01), alpha-2 globulin and gamma globulin (P<0.05) concentrations were statistically different from the seventh day post-inoculation onwards. Beta-globulin levels were increased from day 21 onwards (P<0.05). Alpha-1 globulin fraction did not differ statistically. These results indicate that the infection by T. evansi in cats alters the serum protein electrophoretic profile.
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http://dx.doi.org/10.1016/j.prevetmed.2010.04.002DOI Listing
July 2010

Gastrointestinal parasites of cavy (Cavia aperea aperea) in southern Brazil.

Res Vet Sci 2010 Oct 15;89(2):206-8. Epub 2010 Mar 15.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Faixa de Camobi-Km 9, Campus Universitário, 97105-900 Santa Maria-RS, Brazil.

The aim of this study was to evaluate the gastrointestinal parasitism in Cavia aperea aperea (cavy), captured in the central region of Rio Grande do Sul State. Fecal samples from five free-living cavies were collected for research of parasites. Samples were analyzed by the centrifugal-flotation method with zinc sulfate and parasites were identified microscopically based on (oo)cyst and egg size and morphology. Cysts of Giardia sp. and (oo)cysts of Cryptosporidium sp. and Cystoisospora sp. were observed in one or more cavies. Eggs of Paraspidodera uncinata were observed in three of the five rodents. All infected animals showed mild infection by parasite. This is the first report of Giardia sp., Cryptosporidium sp. and Cystoisospora sp. in Cavia a. aperea.
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http://dx.doi.org/10.1016/j.rvsc.2010.02.012DOI Listing
October 2010

Trypanosoma evansi: cholinesterase activity in acutely infected Wistar rats.

Exp Parasitol 2010 Jul 6;125(3):251-5. Epub 2010 Feb 6.

Laboratory of Veterinary Clinical Analysis, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil.

The aim of this study was to evaluate cholinesterase activity during the early acute phase of Trypanosoma evansi infection in rats. Fifteen male Wistar rats were randomly distributed into three groups (n=5 animals per group): two trypanosome-infected groups (T3 and T5) and uninfected controls (C). The animals were inoculated intraperitoneally with 10(6) trypanosomes. The blood was collected by cardiac puncture on the 3rd (T3) or 5th day post-infection (T5 and C). Cerebrum and cerebellum were removed for the evaluation of acetylcholinesterase (AChE) activity. AChE activity was also evaluated in whole blood and butyrylcholinesterase activity (BUChE) in plasma samples. Parasitemia were progressive increase and parasites were observed in the peripheral blood of all infected animals one day post-inoculation. AChE activity was not altered in cerebrum and cerebellum tissues. AChE activity in blood significantly decreased in the T3 and T5 groups (26.63 and 25.86mU/lmolHb) compared with the control (37.84mU/lmolHb). In addition BUChE activity in plasma was lower in the T3 (7.01micromol BTC hydrolyzed/h/mL) than the T5 and C groups (9.84 and 12.00micromol BTC hydrolyzed/h/mL). This study therefore, shows that reductions in the activity of cholinesterase occur in acute infection by T. evansi in rats and this demonstrates an important change occurring in animals infected by the protozoan and may indicate a potential role the enzymes play in the mechanism of disease.
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http://dx.doi.org/10.1016/j.exppara.2010.01.024DOI Listing
July 2010

Susceptibility of Trypanosoma evansi to human blood and plasma in infected mice.

Vet Parasitol 2010 Feb 31;168(1-2):1-4. Epub 2009 Oct 31.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Camobi, Prédio 20, Sala 4232, CEP 97105900, Santa Maria, RS, Brazil.

Around 1900 Laveran and Mesnil discovered that African trypanosomes do not survive in the blood of some primates and humans. The nature of the trypanolytic factor present in these sera has been the focus of a long-standing debate between different groups. The aim of this study was to investigate the susceptibility of T. evansi isolates to therapy using human blood and plasma in experimentally infected mice. Forty-eight 2-month-old female mice (Mus musculus) were divided into six groups of eight animals per group (A, B, C, D, E and F). Plasma was obtained after blood collection in order to perform therapy. Animals from group A (positive control) were inoculated with T. evansi and treated with 0.2mL of saline solution. Animals from groups B and C were infected with the flagellate and received a curative treatment with 0.2mL of human blood (group B) and 0.2mL of human plasma (group C), 24h after infection. Animals from groups D and E received a prophylactic treatment with 0.2mL of human blood and 0.2mL of human plasma, respectively, 24h prior to the infection. Animals from group F (negative control) were not infected and received 0.2mL of saline solution. The four treatments (B, C, D and E) increased animals longevity when compared to group A. Prepatency period was longer in groups D (15 days) and E (37.7 days) under prophylactic immunotherapy. Moreover, no parasites were found in most of the animals 60 days post-inoculation (PI). Besides the longer longevity, treatments were capable of curing 50% of mice of group B, 37.5% of group C, 37.5% of group D and 25% of the animals from group E.
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http://dx.doi.org/10.1016/j.vetpar.2009.10.020DOI Listing
February 2010

Lipid peroxidation in cats experimentally infected with Trypanosoma evansi.

Parasitol Res 2009 Dec 30;106(1):157-61. Epub 2009 Sep 30.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Santa Maria, Brazil.

The objective of this study was to evaluate the lipid peroxidation and the susceptibility of erythrocytes to in vitro peroxidation as indicators of oxidative damage in erythrocytes and their roles in the pathogenesis of anemia during experimental Trypanosoma evansi infection in cats. Animals were divided into two groups: control and infected with T. evansi. Seven cats were infected with 10(8) trypomastigotes each, and parasitemia was estimated daily for 49 days by microscopic examination of smears. Hematological and biochemical parameters were evaluated for monitoring of the disease. Plasma lipid peroxidation (Thiobarbituric Acid Reactive Substances (TBARS)) and the susceptibility of erythrocytes to in vitro peroxidation were evaluated. Blood samples for analysis were collected at days 21 and 49 post-inoculation. TBARS level, indicated by MDA concentration, was higher in the infected group than in the control group in both analyzed periods, as well as the in vitro erythrocyte peroxidation (P < 0.001). The infected cats had variable degrees of regenerative anemia, which could be explained by the damage in erythrocyte membrane caused by lipid peroxidation.
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http://dx.doi.org/10.1007/s00436-009-1642-3DOI Listing
December 2009

Lipid peroxidation associated with anemia in rats experimentally infected with Trypanosoma evansi.

Vet Parasitol 2009 Oct 2;165(1-2):41-6. Epub 2009 Jul 2.

Laboratory of Veterinary Clinical Analysis--LACVet, Federal University of Santa Maria, Santa Maria, RS, Brazil.

This study aimed to assess the plasma lipid peroxidation and the susceptibility of erythrocytes to in vitro peroxidation as indicators of oxidative damage in erythrocytes and their roles in the pathogenesis of anemia during the early acute phase of Trypanosoma evansi infection in rats. Fifty male Wistar rats were randomly distributed into seven groups: three trypanosome-infected groups (T(2), T(4) and T(6); n=10 animals per group) and four uninfected controls (C(0), C(2), C(4) and C(6); n=5 animals per group). Animals from trypanosome-infected groups were inoculated intraperitoneally with 10(6) trypanosomes. Blood samples were collected by cardiac puncture before infection (day 0; group C(0)) or on the 2nd (C(2) and T(2)), 4th (C(4) and T(4)) and 6th (C(6) and T(6)) day post-infection (dpi). Samples were analyzed for red blood cell (RBC) count, hemoglobin (Hb) concentration, packed cell volume (PCV), plasma malondialdehyde (MDA) and in vitro peroxidation of erythrocytes. The mean values of the hematological indices gradually decreased in the infected rats compared with the control. MDA was significantly increased (P<0.001) on the 6th dpi in infected versus control animals and was negatively correlated with PCV (P<0.001; R(2)=0.372). The values for erythrocyte in vitro peroxidation were higher for groups T(4) and T(6) than for the control rats (P<0.01). A positive correlation between erythrocyte peroxidation and MDA (P<0.001; R(2)=0.414) was observed. The results of this study indicate that T. evansi infection in rats is associated with oxidative stress, indicated by lipid peroxidation and oxidative damage in erythrocyte membranes, as demonstrated by in vitro peroxidation. This may be one of the causes of anemia in acute trypanosomosis.
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http://dx.doi.org/10.1016/j.vetpar.2009.06.032DOI Listing
October 2009

Trypanosoma evansi: hematologic changes in experimentally infected cats.

Exp Parasitol 2009 Sep 20;123(1):31-4. Epub 2009 May 20.

Veterinary Medicine, Universidade Federal de Santa Maria, 97105-900, Santa Maria - RS, Brazil.

This study aimed at evaluating hemogram and erythropoietic changes in cats experimentally infected with Trypanosoma evansi. Thirteen adult female non-breeding Felix catus were separated into two groups: seven animals were infected with 10(8) trypomastigotes each, and six animals were used as negative controls. Animals were kept in air-conditioned rooms and blood smears were performed daily for 49 days. Blood samples were collected from the jugular vein at days 0, 7, 21, 35 and 49 and stored in blood-collecting tubes containing anticoagulant. Bone marrow was collected from the proximal epiphysis of the right femur at days 14 and 42 post-inoculation (PI). Total erythrocyte count, hematocrit and hemoglobin showed statistical differences among groups from the seventh day PI onwards (P<0.05). The mean corpuscular volume and the mean corpuscular hemoglobin concentration remained normal, characterizing a normocytic-normochromic anemia. Reticulocyte count increased in the infected group from the 21st day onwards, but remained near normal values suggesting a mild regenerative anemia. Moreover, the myeloid:erythroid ratio significantly reduced at day 42 PI, evidencing a bone marrow hematopoietic response. Based on these results we conclude that cats infected with T. evansi have normocytic, normochromic, regenerative anemia.
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http://dx.doi.org/10.1016/j.exppara.2009.05.008DOI Listing
September 2009

Duddingtonia flagrans: centrifugal flotation technique with magnesium sulphate for the quantification and qualification of chlamydospores in sheep faeces.

Exp Parasitol 2009 Feb 17;121(2):187-8. Epub 2008 Oct 17.

Department of Microbiology and Parasitology, Universidade Federal de Santa Maria, Brazil.

Duddingtonia flagrans is a nematode-trapping fungus responsible for attacking larval stages of helminths in pasture, which has potential as a biological control method. The aim of this study was to test the magnesium sulphate centrifugal flotation technique for the quantification of D. flagrans chlamydospores in sheep faeces and to verify their morphological viability. In this experiment one sheep received an oral dose of 4.5 x 10(6) chlamydospores/day during 20 days. Fecal samples were collected between days 15 and 20 and analyzed by the centrifugal flotation technique with magnesium sulphate. Densities of 1.23, 1.27 and 1.31gmL(-1) recovered 1.45 x 10(5), 3.87 x 10(5) and 1.65 x 10(5) chlamydospores from the faeces, respectively. Based upon the results it was concluded that this is an efficient technique for the chlamydospores quantification in ovine faeces. Moreover, it allowed more accurate visualization of chlamydospore morphology.
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http://dx.doi.org/10.1016/j.exppara.2008.10.005DOI Listing
February 2009

[Biology of the Phaenicia sericata fly in different substrata].

Rev Bras Parasitol Vet 2008 Apr-Jun;17(2):63-6

Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, Faixa de Camobi, Campus Universitário, Prédio 20, Sala 4232, Santa Maria, RS 97105-900, Brazil.

Dipterans of the species Phaenicia sericata were captured and placed in cages in order to evaluate their biological cycle and to define the best substratum for posture and development of the larvae in controlled temperature and humidity (27 degrees C e 80% UR). Four decomposing substrata were evaluated: bovine, chicken and fish meat as well as bovine liver. No statistical differences were observed in the three first substrata and no posture occurred in the liver. The same substrata were used for feeding larvae and no interference in the larval cycle was observed. The copula occurred five days after the pupation and the posture six days after the copula. The average longevity of the adult flies was 37 days when they were fed with honey and water. According to these results the biological cycle of P. sericata in laboratory was approximately of 51 days.
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http://dx.doi.org/10.1590/s1984-29612008000200001DOI Listing
January 2009
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