Performance of Nellore young bulls on Marandu grass pasture with protein supplementation

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

Effects of lisinopril on experimental ischemia in rats. Influence of infarct size

OBJECTIVE - Angiotensin-converting enzyme inhibitors (ACEIs) have gained importance in preventing or attenuating the process of ventricular remodeling after myocardial infarction. The significance of infarct size in regard to the response to ACEIs, however, is controversial. This study aimed to analyze the effects of lisinopril on mortality rate, cardiac function, degree of cardiac hypertrophy and fibrosis in rats with different infarct sizes. METHODS - Lisinopril (20 mg/kg/day) dissolved in drinking water was administered to rats immediately after coronary artery occlusion. After being sacrificed, the infarcted animals were divided into two groups: one group of animals with small infarcts (< 40% of the left ventricle) and another group of animals with large infarcts (> 40% of the left ventricle). RESULTS - The mortality rate was 31.7% in treated rats and 47% in the untreated rats. There was no statistical difference between the groups with small and large infarcts in regard to myocardial concentration of hydroxyproline. In small infarcts, the treatment attenuated the heart dysfunction characterized by lower levels of blood pressure and lower values of the first derivative of pressure and of the negative derivative of pressure. The degree of hypertrophy was also attenuated in small infarcts. In regard to large infarcts, no differences between the groups were observed. CONCLUSION - Treatment with the ACEIs had no effect on mortality rate and on the amount of fibrosis. The protective effect of lisinopril on heart function and on the degree of hypertrophy could only be detected in small infarcts

EFFECT OF APIS-MELLIFERA BEE VENOM AND GAMMA-RADIATION ON BONE-MARROW CELLS OF WISTAR RATS TREATED INVIVO

To determine whether the venom of Apis mellifera can exert a radioprotective effect, by reducing the frequency of chromosome aberrations induced by radiation, five different experiments were performed on bone marrow cells of Wistar rats.Animals weighing about 100 g were injected intraperitoneally with different venom concentrations (1.0 or 0.5 mul) 1 or 24 h before, or 30 min after being submitted to 3 or 4 Gy of gamma radiation, and sacrificed 24 h after the last treatment. For each experiment in addition to the group of animals submitted to combined treatment (venom + radiation) and to their control, there was also one group treated with radiation only and another treated with venom only. A decrease in the frequency of chromosome aberrations, and fragments in particular, as well as in the number of cells with aberrations was observed in the experiments in which venom was administered 24 h before irradiation, and the effect was more marked at the higher venom concentration (1 mul/100 g weight).

Transfer coefficient measurements of uranium to the organs of Wistar rats, as a function of the uranium content in the food

Groups of animals (Wistar rats) were fed with rations doped with uranyl nitrate at concentrations ranging from 0.5 to 100 ppm. The uranium content in the ashes of the organs was measured by the neutron-fission track counting technique. The most striking result is that the transfer coefficients, as a function of the uranium concentration, exhibit a concave shape with a minimum around 20ppm-U for all organs. Explanations to interpret this finding are tentatively given. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Metabolism of stevioside by chickens

In intubation experiments (643-1168 mg per animal), most of the stevioside administered to chickens was recovered unchanged in the excreta, and only about 2% was converted into steviol. Neither stevioside nor steviol could be found in the blood. In chronic studies (667 mg of stevioside/kg of feed) with laying hens and meat-type chickens, no significant differences were found in feed uptake, weight gain, and feed conversion as the result of stevioside administration. The egg production and egg composition of laying hens were not influenced. Most of the stevioside taken up was found untransformed in the excreta, and about 21.5% or 7.3% was converted to steviol by meat-type chickens or laying hens, respectively. No stevioside or steviol could be detected in the blood or in the eggs of the different groups of animals. In anaerobic incubation experiments with chicken excreta, only a 20% conversion of stevioside into steviol was found. No harmful effects were observed in the chronic stevioside supplementation experiments nor in the intubation experiments in which very high stevioside doses were given.

Saponins, IL12 and BCG adjuvant in the FML-vaccine formulation against murine visceral leishmaniasis

The FML antigen of Leishmania donovani, in combination with either Riedel de Haen (R), QuilA, QS21 saponins, IL12 or BCG, was used in vaccination of an outbred murine model against visceral leishmaniasis (VL). Significant and specific increases in anti-FML IgG and IgM responses were detected for all adjuvants, and in anti-FML IgG1, IgG2a and IgG2b and delayed type of hypersensitivity to L. donovani lysate (DTH), only for all saponins and IL12. The QS21-FML and QuilA-FML groups achieved the highest IgG2a response. QuilA-FML developed the strongest DTH and QS21-FML animals showed the highest serum IFN-gamma concentrations. The reduction of parasitic load in the liver in response to each FML-vaccine formulation was: 52% (P < 0.025) for BCG-FML, 73% (P < 0.005) for R-FML, 93% (P < 0.005) for QuilA-FML and 79.2% (P < 0.025) for QS21-FML treated animals, respectively. Protection was specific for R-FML and QS21-FML while the QuilA saponin treatment itself induced 69% of LDU reduction. The FML-saponin vaccines promote significant, specific and strong protective effects against murine visceral leishmaniasis. BCG-FML induced minor and non-specific protection while IL 12-FML, although enhancing the specific antibody and IDR response, failed to reduce the parasitic load of infected animals. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Correlation among immune response, morphogenesis of the granulomatous reaction and spleen lymphoid structure in murine experimental paracoccidioidomycosis

We studied the correlation among cellular immune response, the pattern of lung granulomatous lesions and alterations in spleen lymphoid structure in Swiss mice inoculated intravenously with Paracoccidioides brasiliensis strain 18. The animals were evaluated at 24, 48 and 96 h after infection and further studied weekly for 18 weeks by: (i) the macrophage migration inhibition test with phytohemagglutinin (PHA) and P. brasiliensis antigen (PbAg); and (ii) histopathology of the lung and spleen lesions. One group of animals was gamma -irradiated (8 Gy), infected under the same conditions and evaluated for the pattern of lung granulomatous lesions and spleen lymphoid structure at 24, 48 and 96 h after infection. During the first week of infection, the non-irradiated animals presented a positive response to PHA and PbAg, compact granulomas in the lungs and a typical hyperplasia of the spleen white pulp. However, from weeks 2 to 5, a depression of the cell-mediated immunity (CMI) response to PHA and PbAg was observed in association with granulomas presenting only large mononuclear cells and lacking both giant cells and a peripheral halo of small mononuclear cells. This pattern of granuloma formation was similar to that seen in gamma -irradiated animals, whose cells involved in CMI were absent. After week 7, the non-irradiated animals showed granulomas characterized by the presence of giant cells and a peripheral halo of small mononuclear cells. This type of granuloma was formed concomitantly with recovery of the CMI and of the lymphoid structure of the spleen. The results showed a correlation among granulomas composed of large mononuclear cells, hypoplasia of the splenic tissue and impaired CMI. This correlation indicated that although granuloma morphogenesis per se does not depend on the activation of CMI, this response is important at later stages during modulation of the cellular composition of the granulomas.

Antagonism of clonidine injected intracerebroventricularly in different models of salt intake

Clonidine, an alpha 2-adrenergic agonist, injected into the brain inhibits salt intake of animals treated by the diuretic model of sodium depletion. In the present study, we address the question of whether central injection of clonidine also inhibits salt intake in animals deprived of water or in the need-free state. Saline or clonidine (30 nmol) was injected into the anterior third ventricle of 24-h sodium-depleted (furosemide + removal of ambient sodium), of 24-h water-deprived and of normovolemic (need-free state) adult male rats, Clonidine injected intracerebroventricularly (icv) inhibited the 1.5% NaCl intake for 120 min by 50 to 90% in every model tested. Therefore, different models of salt intake are inhibited by icv injection of clonidine, Idazoxan, an alpha 2-adrenergic antagonist, injected icy at a dose of 160 nmol, inhibited the effect of clonidine only in the furosemide + removal of ambient sodium model of salt intake. This indicates that the antagonism of this effect by idazoxan is dependent on the body fluid/sodium status of the animal.

Seroprevalence of Neospora caninum in dairy cattle in Bahia, Brazil

Sera collected from 447 dairy cattle on 14 dairy farms were tested for Neospora caninum antibodies by use of an immunofluorescent antibody technique. Positive reactions with titres greater than or equal to 1:200 were found in 63 (14.09%) of animals. Neospora positive sera were also tested for Toxoplasma gondii antibodies by using a commercial latex agglutination test. Antibodies to T. gondii were detected in 3 (4.76%) of 63 N. caninum positive sera. These results indicate that N. caninum infection is widespread among dairy cattle in Bahia state. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Genetic and phenotypic trends for growth traits of buffaloes in Brazil

The objectives this paper were to estimate genetic parameters and genetic and phenotypic trends of birth weight (BWT) and weights adjusted to 205 (WT205), 365 (WT365) and 550 (P550) days of age of beef buffaloes born from 1985 to 2003 in Brazil. For BWT and WT205 the model included direct and maternal genetic and maternal environment as random effects and contemporary and genetic groups as fixed effects. For WT365 and WT550 the same model was used except without direct maternal and maternal environmental effects. The genetic and phenotypic trends were estimated by regression of means of dependent variables on birth year of animals Regressions were obtained by using two methodologies: 1) linear regression; and 2) non-parametric splined regression. The direct heritability estimates were 0.09, 0.45, 0.46 and 0.58 for BWT, WT205, WT365 and WT550, respectively. The direct genetic trends from linear regression were 0.01, 0.23, 0.58 and 1.40 kg per year for PN, WT205, VVT365 and WT550, respectively (P<0.001 for all). Phenotypic trends were strongly positive while genetic trends were consistently positive but small. Genetic parameters indicate potential for increased rate of genetic change with full implementation of genetic improvement programs.

PARTICIPATION OF OPIOID RECEPTORS IN THE MODULATION OF THE ANALGESIC RESPONSE BY ADRENAL AND GONADAL GLANDS

The involvement of opioid receptors in the analgesic response was evaluated by the tail-immersion test in simultaneously adrenalectomized and ovariectomized female Wistar rats (210-250 g). The reaction time (mean +/- SEM) for tail withdrawal from hot water decreased significantly 2 weeks after surgery (3.52 +/- 0.20 s) when compared to intact animals (6.09 +/- 0.23 s). Hormonal replacement with dexamethasone (50-mu-g/day) did not affect reaction time (3.38 +/- 0.19 s). However, this response was restored by combined adrenal and gonadal steroid substitution (estradiol 5-mu-g/day and progesterone 1.5-mu-g 6 h before the tests) therapy (5.11 +/- 0.45 s in animals treated with dexamethasone plus estradiol and 5.04 +/- 0.43 s in animals treated with dexamethasone plus estradiol plus progesterone). Naloxone (2 mg/kg) decreased the reaction time of animals treated with adrenal and gonadal steroids (5.11 +/- 0.45 vs 4.15 +/- 0.44 s and 5.04 +/- 0.43 vs 3.87 +/- 0.28 s, respectively, before and after naloxone) but failed to decrease it in rats treated with dexamethasone only (3.88 +/- 0.18 vs 4.34 +/- 0.25 s, before and after naloxone). These observations indicate that gonadal steroids are the most important steroid factors involved in the reaction time to tail immersion in hot water and confirm other reports that the opioid pathways modulating the neuronal circuitry require the presence of these hormones.

Hypnotic, anticonvulsant and muscle relaxant effects of Rubus brasiliensis. Involvement of GABA(A)-system

Rubus brasiliensis hexanic fraction induced anxiolysis in rodents, which was reversed by flumazenil, a specific GABA(A)-benzodiazepine receptor antagonist (Nogueira et al., 1998a,b). Then, we investigated if this hexanic fraction was able to induce hypnotic, anticonvulsant and muscle relaxant effects, and the involvement of GABA(A)-system. The hexanic fraction (50, 100, 150 and 300 mg/kg, vo) was administered to male Swiss mice, 30 min before the tests. Only the dose of 300 mg/kg of this fraction decreased the latency and increased sleeping time in the barbituric-hypnosis test (sodium pentobarbital, 30 mg/kg, ip), prevented the pentylenetetrazol seizures (70 mg/kg, ip) and induced muscle relaxant (inclined plane) in 100% of animals. These effects were reversed by flumazenil (3 mg/kg, ip). In conclusion: (1) R. brasiliensis hexanic fraction induced hypnotic, anticonvulsant and muscle relaxant effects, in mice, and the GABA(A)-benzodiazepine receptor may play an important role in the effects of this fraction; (2) it is strongly suggested that this fraction contains a benzodiazepine-like principle. (C) 2000 Elsevier B.V. Ireland Ltd. All rights reserved.

EARLY ACTIVATION OF SPLENIC MACROPHAGES BY TUMOR-NECROSIS-FACTOR-ALPHA IS IMPORTANT IN DETERMINING THE OUTCOME OF EXPERIMENTAL HISTOPLASMOSIS IN MICE

Experimental infection of animals with Histoplasma capsulatum caused a massive macrophage infiltration into the spleen and induced the production of tumor necrosis factor alpha (TNF-alpha) locally. The cytokine was also produced in vitro by peritoneal exudate macrophages exposed to a large inoculum of yeast cells. Depletion of the cytokine by injection of polyclonal sheep anti-TNF-alpha antibody was detrimental to sublethally infected mice. Fungous burdens in the spleens of TNF-alpha-depleted mice were higher than they were in the infected control mice at days 2, 7, and 9 after infection, and the antibody-treated animals succumbed to the infection. Histopathological study of spleen sections revealed that splenic macrophages were not able to control proliferation of intracellular yeasts as a result of TNF-alpha depletion. It seems that TNF-alpha plays a role in early activation of splenic macrophages which is important in controlling the outcome of an infection.

Evaluation of transformation growth factor beta(1), interleukin-10, and interferon-gamma in male symptomatic and asymptomatic dogs naturally infected by Leishmania (Leishmania) chagasi

The aims of this study were to evaluate the immunomodulatory role of TGF-beta(1), 1L-10, and INF-gamma in spleen and liver extracts and supernatant cultures of white spleen cells from male symptomatic and asymptomatic dogs, naturally infected by Leishmania (Leishmania) chagasi. Thirty dogs from Aracatuba, São Paulo, Brazil, an endemic leishmaniosis area, were selected by positive ELISA serological reaction for Leishmania sp. and divided into two groups: asymptomatic (n=15) and symptomatic (n=15) consisting of animals with at least three characteristic signs (fever, dermatitis, lymphoadenopathy, onychogryphosis, weight loss, cachex a, locomotion problems, conjunctivitis, epistaxis, hepatosplenomegaly, edema, and apathy). After euthanasia, spleen and liver fragments were collected for ex vivo quantification of TGF-beta(1), IL-10, and INF-gamma. Naturally active in vitro produced TGF-beta(1) was also evaluated in spleen cell culture supernatant. Spleen and liver extract of asymptomatic dogs had higher mean TGF-beta(1) levels than symptomatic dogs. High concentrations of IL-10 were found in spleen, and mainly in liver extract of both groups. Higher INF-gamma concentrations were found in spleen extracts of symptomatic dogs, and in liver extracts of asymptomatic dogs. Extract of this cytokire was lower in spleen extract. Although INF-gamma is being produced in canine infection, mean levels of TGF-beta(1) and IL-10 from spleen and liver extracts were quantitatively much higher; suggesting that immune response in both asymptomatic and symptomatic dogs A as predominantly type Th2. (c) 2006 Elsevier B.V. All rights reserved.

Study of the embryotoxic effects of an extract of rosemary (Rosmarinus officinalis L)

Extracts of rosemary, Rosmarinus officinalis L., have been used in folk medicine as a diuretic, an emenagogue, an antispasmodic and its aqueous extract does not present toxicity to man, presenting, however, abortive effects. In order to evaluate if this plant induces abortion and/or interferes with the normal development of the concepts, doses of 26 mg of a 30% (w/v) R. officinalis aqueous extract (13 mg solids/ml) made with leaves, flowers and stem were administered daily by gavage during two different periods of Wistar rat pregnancy. One group of animals (N = 12) received the extract from days 1 to 6 of pregnancy (preimplantation period) and another group (N = 14) received the same extract from days 6 to 15 of pregnancy (organogenic period). Control groups (N = 12) received saline in the same volume and during the same periods as their respective experimental groups. The animals were sacrificed at term. The treatment of the darns during either the preimplantation or the organogenic period did not cause significant changes in the postimplantation loss or in the number of anomalies or malformations of the term fetuses, which also showed a similar degree of development when compared with the respective controls. The percent of preimplantation loss in the group treated before embryo implantation increased, although the difference was not significant compared to the control. This result suggests that rosemary extract may present an anti-implantation effect without interfering with the normal development of the concept after implantation.