Raqueli T. França

Experimental infection with Rangelia vitalii in dogs: Acute phase, parasitemia, biological cycle, clinical-pathological aspects and treatment

Recently we conducted the molecular characterization of Rangelia vitalii, a protozoan with high pathogenicity for young dogs in southern Brazil. To date, the descriptions of the disease have been restricted to natural infection cases. Therefore, this study aimed to evaluate the parasitemia, biological cycles and clinical-pathological findings in dogs experimentally infected with R. vitalii in the acute phase of disease, and also aimed to test a therapeutic protocol based on the diminazene aceturate. For this study, we used 12 young dogs (females), separated into two groups. Group A was composed of healthy dogs, not-infected (n=5), and Group B consisted of animals infected with R. vitalii (n=7). After infection, the animals were monitored by blood smear examinations, which showed intra-erythrocytic forms of the parasite 5 days post-infection (PI). Parasitemia increased progressively in these animals and had the highest peak of circulating parasites between 9 and 11 days PI. Subsequently, the parasitemia reduced and the protozoan was seen inside the leukocytes in days 17, 19 and 21 PI. The most prominent clinical signs observed at the 20 day PI of experiment were lethargy, fever and anorexia. We observed a decrease of hematocrit of infected animals compared with not-infected dogs, featuring a moderate anemia. Pathological evaluation of one dog in Group B at day 21 PI revealed splenomegaly, hepatomegaly, lymphadenopathy, and hemorrhages at necropsy. Histological examination showed only follicular hyperplasia in the spleen and lymph nodes, and the etiologic agent in the vascular endothelium. At 21 days PI, it was performed the treatment of dogs in Group B (n=6) with a single dose of diminazene aceturate, which showed a curative efficacy of 100% in cleaning R. vitalii from blood of infected dogs.

Cytokines in rats experimentally infected with Trypanosoma evansi

The aim of this study was to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1) and interleukin 6 (IL-6) in the serum of rats experimentally infected with Trypanosoma evansi and to correlate these levels with hematological parameters. Initially, 48 rats (group T) were intraperitoneally inoculated with cryopreserved blood containing 1×10(6) trypomastigotes per animal. Twenty-eight animals (group C) were used as negative controls and received 0.2 mL of saline by the same route. The experimental groups were formed according to the time after infection and the degree of parasitemia as follows: four control subgroups (C3, C5, C10 and C20) with seven non-inoculated animals each and four test subgroups (T3, T5, T10 and T20) with 10 animals each inoculated with T. evansi. The blood samples were collected by cardiac puncture at days 3 (C3, T3), 5 (C5, T5), 10 (C10, T10) and 20 (C20, T20) post-infection (PI) to perform the complete blood count and the determination of IFN-γ, TNF-α, IL-1 and IL-6 levels using an ELISA quantitative sandwich. Infected rats showed normocytic normochromic anemia during the experimental period. T. evansi infection in rats caused a serum increase (P<0.01) of IFN-γ, TNF-α, IL-1 and IL-6 levels at days 3, 5, 10 and 20 PI compared to the controls. The multiple linear regressions showed a reduction of 24% in the hematocrit as a consequence of the increased IFN-γ, TNF-α and IL-1. Therefore, we conclude that the infection caused by T. evansi causes an increase in the pro-inflammatory cytokines. These results suggest a synergism among IL-1, TNF-α and IFN-γ contributing to the development of anemia. This increase is associated with the regulation of immune responses against the parasite.

Rangelia vitalli in dogs in southern Brazil

This article aims to describe seven cases of dogs naturally infected with Rangelia vitalli. Clinical findings, hematological parameters, parasitological diagnosis, and treatments were evaluated. On physical examination, these animals showed pale mucous membranes, hyperthermia, apathy, and blood dribbling down from the ear margins. R. vitalli merozoites were observed inside of erythrocytes, neutrophils, and macrophages in blood smear. Important hematological findings observed in these cases were severe anemia and thrombocytopenia. The animals were treated with therapeutic protocol based on prednisone, doxycycline, and dipropionate which had great curative efficacy to rangeliosis.

Antioxidant and anti-inflammatory effects of quercetin in functional and morphological alterations in streptozotocin-induced diabetic rats

The aim of this study was to investigate functional and morphological alterations caused by oxidative stress in streptozotocin (STZ)-induced diabetic rats and to evaluate the antioxidant effect of quercetin (QUE) in this disease. One hundred and thirty male Wistar rats, it were randomly distributed in 10 different experimental groups, with ten animals per group: Control Saline (CS), Control Ethanol (CE), Control QUE 5mg/kg (CQ5), Control QUE 25mg/kg (CQ25), Control QUE 50mg/kg (CQ50), Diabetic Saline (DS), Diabetic Ethanol (DE), Diabetic QUE 5mg/kg (DQ5), Diabetic QUE25 mg/kg (DQ25), Diabetic QUE 50mg/kg (DQ50). Therefore, hyperglycemia is directly involved in oxidative stress production, as well as in functional and morphological alterations caused by the excess of free radicals. QUE, specially at the dosage of 50mg/kg, can act as an antioxidant and anti-inflammatory agent, becoming a promising adjuvant in the treatment of diabetes mellitus.

Horses naturally infected by Trypanosoma vivax in southern Brazil

In this study, we reported the first outbreak of the infection by Trypanosoma vivax in horses in southern Brazil, a non-endemic region where bovines have only recently been found infected by this trypanosome species. We evaluated 12 horses from a farm in southern Brazil, where four horses displayed pale mucous membranes, fever, weight loss, and swelling of abdomen, prepuce, or vulva. The diagnosis of T. vivax was confirmed in four horses by morphological parameters of trypomastigotes in blood smears and species-specific PCR. All T. vivax-infected animals showed anemia, and most showed increased levels of beta-1, beta-2, and gamma globulins. Horses were treated with diminazene aceturate, but cure was not achieved, and the disease relapsed after therapy. These findings demonstrated that Brazilian T. vivax isolates, which were already reported infecting cattle, buffaloes, goats, and sheep, can be highly pathogenic for horses, causing severe disease and even death of the animals due to the recurrence of the infection.

Increased Cytokine and Nitric Oxide Levels in Serum of Dogs Experimentally Infected with Rangelia vitalii

This study aimed to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NO x ) in serum of dogs experimentally infected with Rangelia vitalii. Twelve female mongrel dogs were divided into 2 groups; group A (uninfected controls) composed by healthy dogs (n=5) and group B consisting of dogs inoculated with R. vitalii (n=7). Animals were monitored by blood smear examinations, which showed intraerythrocytic forms of the parasite on day 5 post-infection (PI). Blood samples were collected through the jugular vein on days 0, 10, and 20 PI to determine the serum levels of IFN-γ, TNF-α, IL-1, IL-6, and NO x . Cytokines were assessed by ELISA quantitative sandwich technique, and NO x was measured by the modified Griess method. Cytokine levels (IFN-γ, TNF-α, IL-1, and IL-6) were increased (P<0.01) in serum of infected animals. Serum levels of NO x were also increased on days 10 PI (P<0.01) and 20 PI (P<0.05) in infected animals. Therefore, the infection with R. vitalii causes an increase in proinflammatory cytokines and nitric oxide content. These alterations may be associated with host immune protection against the parasite.

17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized adult and middle-aged rats

AIMS To investigate the 17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized rats of different ages. MAIN METHODS Animals were randomly assigned into three experimental groups of each age (n=6). Control groups consisted of adult (sham-A) and middle-aged (sham-MA) female rats, ovariectomized adult (OVX-A) and middle-aged (OVX-MA) rats without estrogen therapy reposition, and ovariectomized adult (OVX+E2-A) and middle-aged (OVX+E2-MA) rats treated with 17-β estradiol for 30days. After this period, AChE activity and lipid peroxidation were measured in the brain and blood. KEY FINDINGS The AChE activity increased (p<0.05) in striatum (ST) in OVX-A, OVX+E2-A and OVX-MA, and hippocampus (HP) in OVX-MA. The enzyme activity decreased (p<0.05) in ST of OVX+E2-MA, and cerebral cortex (CC) in OVX+E2-A, OVX-MA and OVX+E2-MA. Blood AChE activity increased (p<0.05) in OVX+E2-A and decreased (p<0.05) in OVX-MA. Lymphocyte AChE activity increased (p<0.05) in OVX-A and OVX+E2-A and decreased (p<0.05) in OVX-MA. Lipid peroxidation increased (p<0.05) in ST of OVX-A, CC of OVX-A and OVX-MA, HP of OVX-A, and cerebellum (CE) of OVX-A, OVX-MA, and OVX+E2-MA. Lipid peroxidation decreased (p<0.05) in ST, CC and CE of OVX+E2-A, and ST and HP of OVX+E2-MA. Similar values of lipid peroxidation to control groups were found in ST and HP of OVX-MA, HP of OVX+E2-A and CC of OVX+E2-MA. SIGNIFICANCE 17-β estradiol is able to modulate the AChE activity and non-neuronal cholinergic response as well as to reduce lipid peroxidation. Its response is dependent on the age and brain structure analyzed.

Trypanosoma evansi: Immune response and acetylcholinesterase activity in lymphocytes from infected rats

The existence of cholinergic receptors in the immune system cells is well documented. This study aimed to evaluate the acetylcholinesterase activity (AChE) in lymphocytes from rats infected with Trypanosoma evansi in acute and chronic phase disease. Twenty animals were infected with 10(6) trypomastigotes forms each and 10 were used as negative controls. The two groups of inoculated rats were formed according to the degree of parasitemia and the period post-infection (PI). Group A: rats with 4 days PI and between 24 and 45 parasites/field (1000×); group B: rats with 30 days PI and parasitemia with jagged peaks between 0 and 1 parasites/field; group C: not-infected animals. At 4 days PI (acute phase) and 30 days PI (chronic phase) the rats were anesthetized to collect blood for hemogram and separation of lymphocytes. After separation, the AChE activity was measured in lymphocytes. It was observed that the number of lymphocytes increased significantly in group A compared to group C. The activity of AChE in lymphocytes significantly increased in acute phase and decreased in chronic phase in the infected rats when compared to not-infected (P<0.05). Statistical analysis showed a positive correlation between the number of lymphocytes and AChE activity in lymphocytes in 4 days PI (r(2): 0.59). Therefore, the infection by T. evansi influences AChE activity in lymphocytes of rats indicating changes in the responses of cholinergic system in acute phase, possibly due to immune functions performed by these enzymes.

Serum proteinogram of cats experimentally infected by Trypanosoma evansi.

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.

Pre-treatment with curcumin modulates acetylcholinesterase activity and proinflammatory cytokines in rats infected with Trypanosoma evansi

The potent activity against Trypanosomes and health beneficial effects of curcumin (Cur) has been demonstrated in various experimental models. In this study, we evaluated the in vivo effect of Cur as trypanocide and as potential anti-inflammatory agent, through the evaluation of immunomodulatory mechanisms in rats infected with Trypanosoma evansi. Daily oral Cur was administered at doses of 0, 20 or 60mg/kg as preventive treatment (30 and 15days pre infection) and as treatment (post infection). The treatment of the groups continued until the day of euthanasia. Fifteen days after inoculation, parasitemia, plasma proinflammatory cytokines (IFN-γ, TNF-α, IL-1, IL-6), anti-inflammatory cytokines (IL-10) and blood acetylcholinesterase activity (AChE) were analyzed. Pretreatment with Cur reduced parasitemia and lethality. Cur inhibited AChE activity and improved immunological response by cytokines proinflammatory, fundamental during T. evansi infection. We found that Cur is not so important as an antitrypanosomal activity but as immunomodulator agent. These findings reveal that the preventive use of Cur stimulates anti-inflammatory mechanisms, reducing an excessive inflammatory response.