Respostas fisiológicas e comportamentais de vacas Holandesas mantidas em sistema adiabático evaporativo

Este estudo teve como objetivo avaliar a influência de recursos de climatização, ventilação e nebulização, sobre a fisiologia e o comportamento de vacas Holandesas alojadas em free-stall, durante o verão do sudeste brasileiro. Foram utilizadas 20 vacas Holandesas submetidas a dois tratamentos com e sem climatização. Os parâmetros ambientais registrados foram temperatura de bulbo seco, umidade relativa do ar e temperatura de globo negro. As variáveis fisiológicas avaliadas foram temperatura retal e frequência respiratória. As variáveis comportamentais registradas foram postura e suas atividades dentro da instalação. Para análise estatística utilizou-se a metodologia de quadrados mínimos por meio do procedimento PROC MIXED e PROC GLM. Apesar das diferenças estatísticas obtidas para as variáveis fisiológicas, as mesmas não foram biologicamente efetivas e indicaram que os animais se encontravam em conforto térmico. Os animais que dispunham de ventilação e nebulização alimentaram-se mesmo nas horas mais quentes do dia. A climatização é uma estratégia que permite maior conforto térmico aos animais e por consequência pode aperfeiçoar a produção leiteira através do aumento no consumo alimentar.

QT interval in healthy dogs: which method of correcting the QT interval in dogs is appropriate for use in small animal clinics?

The electrocardiography (ECG) QT interval is influenced by fluctuations in heart rate (HR) what may lead to misinterpretation of its length. Considering that alterations in QT interval length reflect abnormalities of the ventricular repolarisation which predispose to occurrence of arrhythmias, this variable must be properly evaluated. The aim of this work is to determine which method of correcting the QT interval is the most appropriate for dogs regarding different ranges of normal HR (different breeds). Healthy adult dogs (n=130; German Shepherd, Boxer, Pit Bull Terrier, and Poodle) were submitted to ECG examination and QT intervals were determined in triplicates from the bipolar limb II lead and corrected for the effects of HR through the application of three published formulae involving quadratic, cubic or linear regression. The mean corrected QT values (QTc) obtained using the diverse formulae were significantly different (ρ<0.05), while those derived according to the equation QTcV = QT + 0.087(1- RR) were the most consistent (linear regression). QTcV values were strongly correlated (r=0.83) with the QT interval and showed a coefficient of variation of 8.37% and a 95% confidence interval of 0.22-0.23 s. Owing to its simplicity and reliability, the QTcV was considered the most appropriate to be used for the correction of QT interval in dogs.

Efeito da suplementação de cloreto de amônio sobre os equilíbrios eletrolítico e ácido-básico e o pH urinário de ovinos confinados

A incidência da urolitíase obstrutiva em ovinos é elevada, principalmente em machos confinados, tanto para produção de carne, quanto reprodutores de alto valor genético. A acidificação urinária é um dos métodos para prevenção desta enfermidade e pode ser realizada de forma eficaz com a suplementação de cloreto de amônio na dieta, que pode propiciar a instalação de acidose metabólica. A hemogasometria avalia o equilíbrio ácido-básico sanguíneo de forma prática e fácil. Neste trabalho, avaliou-se o efeito do cloreto de amônio sobre o equilíbrio ácido-básico e eletrolítico de ovinos em confinamento para quantificar a acidose metabólica desenvolvida. Utilizaram-se 100 ovinos, machos, confinados, com idade aproximada de três meses. Constituíram-se três grupos experimentais: Grupo I (n=40), recebeu 400mg/kg/PV de cloreto de amônio/animal/dia por 21 dias consecutivos, momento da interrupção da administração do acidificante urinário (M3) e continuidade do acompanhamento clinico até o final do experimento (M6); Grupo II (n=40), 400mg/kg/PV de cloreto de amônio/animal/dia por 42 dias consecutivos; Grupo III (n=20), não recebeu cloreto de amônio durante todo o período do experimento. Os Momentos (M) de colheita de amostras e avaliação clínica foram estabelecidos com intervalo de sete dias, sendo M0 (imediatamente antes do início do tratamento com cloreto de amônio), M1 (sete dias após), M2, M3, M4, M5 e M6, totalizando 56 dias de confinamento. A alimentação consistiu de ração total, composta por 15% de feno triturado e 85% de concentrado, água e sal mineral ad libitum. Após adaptação de 15 dias à dieta de confinamento, colheram-se de todos os animais amostras de urina para mensuração do pH, e sangue venoso para hemogasometria, nos diferentes momentos. A acidificação urinária foi mantida enquanto houve a administração de cloreto de amônio nos grupos GI e GII. Os valores de Na+ e K+ permaneceram dentro da normalidade para a espécie. O cloreto de amônio provocou acidose metabólica hiperclorêmica compensada nos grupos GI e GII, comprovada pelos valores reduzidos de HCO3-, EB e SID, pelos valores elevados de Cl- e pelo pH normal. Concluiu-se que o cloreto de amônio apesar de provocar diminuição da reserva alcalina no organismo, não interferiu com o desenvolvimento dos animais, podendo ser empregado como agente preventivo da urolitíase obstrutiva em ovinos.

Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de ovinos naturalmente intoxicados por Amaranthus spinosus (Amaranthaceae)

Resumo: Amaranthus spp. são plantas nefrotóxicas popularmente conhecidas como "caruru". Em casos de intoxicação por estas plantas, a principal alteração histopatológica está presente no rim, sob forma de nefrose tubular tóxica, porém em alguns casos pode haver alterações cardíacas. Alterações no eletrocardiograma, compatíveis com quadros de hipercalemia, foram descritas em suínos intoxicados por Amaranthus retroflexus e lesões como degeneração e necrose de miócitos cardíacos descritas em suínos intoxicados por A. caudatus e ovinos intoxicados por A. spinosus. Há dúvidas com relação às alterações cardíacas, que, na maioria dos casos, são incipientes, o que pode levar a erros de interpretação. Para a realização do trabalho foram utilizados blocos parafinados oriundos de um surto natural de intoxicação por A. spinosus no sudeste do Brasil. Esse estudo teve como objetivo detectar a presença de alterações regressivas incipientes no miocárdio de ovinos intoxicados por A. spinosus, através da utilização imuno-histoquímica do anticorpo anti-troponina C. Foram utilizados fragmentos de coração de 8 ovinos adultos e 2 fetos, intoxicados naturalmente por A. spinosus. Estes fragmentos foram submetidos à técnica de imuno-histoquímica com a utilização do anticorpo anti-troponina C. Pela avaliação imuno-histoquímica do coração dos oito ovinos adultos observaram-se diversos grupos de miócitos com diminuição significativa ou ausência de imunorreatividade para o anticorpo anti-troponina C; essas áreas correspondiam, em grande parte, aos mesmos grupos de miócitos que apresentavam, pela coloração de Hematoxilina e Eosina (H.E.) alterações que variavam de leve tumefação celular a aumento da eosinofilia, perda de estriação, lise celular e cariólise, ou mais raramente, acompanhadas de infiltrado inflamatório. Em quatro casos foi possível notar que diversos pequenos grupos de miócitos que tinham marcada diminuição de imunorreatividade, correspondiam a células com alterações imperceptíveis ou muito discretas no H.E. Nos corações dos dois fetos não houve áreas com perda ou diminuição de imunorreatividade para o anticorpo anti-troponina C. Os resultados da avaliação imuno-histoquímica confirmaram a presença tanto de alterações regressivas incipientes, quanto ratificaram a ocorrência de lesões necróticas já bem instaladas no miocárdio de ovinos intoxicados por Amaranthus spinosus. Verificou-se correspondência entre as áreas com ausência de imunorreatividade à troponina com as áreas de lesões mais marcadas no H.E.. Adicionalmente, a técnica foi capaz de detectar lesões muito precoces (locais do miocárdio sem sinais morfológicos de agressão), e demonstrou que as áreas agredidas/lesadas eram maiores que o evidenciado no HE. Esse estudo demonstra a necessidade de melhor se investigar a possível participação da hipercalemia e de outras alterações metabólicas presentes na lesão renal aguda, na gênese das lesões cardíacas de rápida instalação, ou seja, aquelas não correlacionadas às lesões vasculares determinadas pela uremia de longa duração.

Reprodução sexuada de Dyckia tuberosa (Vell.) Beer (Bromeliaceae, Pitcairnioideae) e interação planta-animal

Bromeliaceae é um componente importante em vários Biomas, sendo notável a variedade de contextos ecológicos em que pode ser encontrada. Ocorre no grupo a combinação entre dois modos de reprodução: sexuada e propagação clonal. Neste estudo descrevemos vários atributos relacionados à reprodução sexuada de Dyckia tuberosa, bem como interações planta-animal que se estabelecem em suas estruturas reprodutivas. Ao longo de 11 meses, 55 % dos indivíduos na população estudada floresceram e frutificaram. As flores se desenvolvem da base para o ápice e apresentam diferenças morfométricas quanto à posição na inflorescência que acarretam diferenças na produção de sementes. A concentração de açúcares no néctar foi de 20% e a produção total de néctar foi de c. de 24 µL flor-1 dia-1, sendo esta última maior no período da manhã entre 8h00 e 9h00. Dyckia tuberosa é auto-incompatível e o índice de auto-incompatibilidade (ISI) foi de 0,08. Somente beija-flores exploraram as flores de modo legítimo, contatando anteras e estigma, sendo 3,9 flores visitadas por hora. Chlorostilbon aureoventris, Colibri serrirostris e Phaethornis eurynome foram as espécies registradas. Em D. tuberosa a reprodução sexuada depende das visitas dos beijaflores. Houve patrulhamento das inflorescências de D. tuberosa pelas formigas Camponotus rufipes, Camponotus cf. mus e Cephalotes sp. Como há ausência de reprodução sexuada em muitos indivíduos, e esta espécie é dominante no afloramento rochoso estudado, consideramos que a propagação clonal seja uma estratégia importante para a disseminação de D. tuberosa na área. A presença de animais, polinizadores ou não, na inflorescência de D. tuberosa torna esta espécie adequada para avaliar como variações na disponibilidade de recursos florais alteram o resultado das interações planta-animal e o sucesso reprodutivo de D. tuberosa.

Production of recombinant antigens in plants for animal and human immunization - a review

Plants present a cost effective production system for high value proteins. There is an increasing world demand for cheap vaccines that can be readily administered to the population, especially in economically less developed regions. A promising concept is the production of vaccines in plants that could be grown locally. Expression of antigenic peptides in the palatable parts of plants can lead to the production of edible active vaccines. Two major strategies are: i) to express antigens in transgenic plants, and ii) to produce antigenic peptides on the surface of plant viruses that could be used to infect host plants. This review considers the experimental data and early results for both strategies, and discusses the potential and problems of this new technology

Animal models of anxiety: an ethological perspective

In the field of anxiety research, animal models are used as screening tools in the search for compounds with therapeutic potential and as simulations for research on mechanisms underlying emotional behaviour. However, a solely pharmacological approach to the validation of such tests has resulted in distinct problems with their applicability to systems other than those involving the benzodiazepine/GABAA receptor complex. In this context, recent developments in our understanding of mammalian defensive behaviour have not only prompted the development of new models but also attempts to refine existing ones. The present review focuses on the application of ethological techniques to one of the most widely used animal models of anxiety, the elevated plus-maze paradigm. This fresh approach to an established test has revealed a hitherto unrecognized multidimensionality to plus-maze behaviour and, as it yields comprehensive behavioural profiles, has many advantages over conventional methodology. This assertion is supported by reference to recent work on the effects of diverse manipulations including psychosocial stress, benzodiazepines, GABA receptor ligands, neurosteroids, 5-HT1A receptor ligands, and panicolytic/panicogenic agents. On the basis of this review, it is suggested that other models of anxiety may well benefit from greater attention to behavioural detail

The use of non-human primates as animal models for the study of hepatitis viruses

Hepatitis viruses belong to different families and have in common a striking hepatotropism and restrictions for propagation in cell culture. The transmissibility of hepatitis is in great part limited to non-human primates. Enterically transmitted hepatitis viruses (hepatitis A virus and hepatitis E virus) can induce hepatitis in a number of Old World and New World monkey species, while the host range of non-human primates susceptible to hepatitis viruses transmitted by the parenteral route (hepatitis B virus, hepatitis C virus and hepatitis delta virus) is restricted to few species of Old World monkeys, especially the chimpanzee. Experimental studies on non-human primates have provided an invaluable source of information regarding the biology and pathogenesis of these viruses, and represent a still indispensable tool for vaccine and drug testing.

Transgenic animal models for the functional analysis of vasoactive peptides

The interplay of vasoactive peptide systems is an essential determinant of blood pressure regulation in mammals. While the endothelin and the renin-angiotensin systems raise blood pressure by inducing vasoconstriction and sodium retention, the kallikrein-kinin and the natriuretic-peptide systems reduce arterial pressure by eliciting vasodilatation and natriuresis. Transgenic technology has proven to be very useful for the functional analysis of vasoactive peptide systems. As an outstanding example, transgenic rats overexpressing the mouse Ren-2 renin gene in several tissues become extremely hypertensive. Several other transgenic rat and mouse strains with genetic modifications of components of the renin-angiotensin system have been developed in the past decade. Moreover, in recent years gene-targeting technology was employed to produce mouse strains lacking these proteins. The established animal models as well as the main insights gained by their analysis are summarized in this review.

The relationship between anxiety and depression in animal models: a study using the forced swimming test and elevated plus-maze

The present study evaluated the correlation between the behavior of mice in the forced swimming test (FST) and in the elevated plus-maze (PM). The effect of the order of the experiments, i.e., the influence of the first test (FST or PM) on mouse behavior in the second test (PM or FST, respectively) was compared to handled animals (HAND). The execution of FST one week before the plus-maze (FST-PM, N = 10), in comparison to mice that were only handled (HAND-PM, N = 10) in week 1, decreased % open entries (HAND-PM: 33.6 ± 2.9; FST-PM: 20.0 ± 3.9; mean ± SEM; P<0.02) and % open time (HAND-PM: 18.9 ± 3.3; FST-PM: 9.0 ± 1.9; P<0.03), suggesting an anxiogenic effect. No significant effect was seen in the number of closed arm entries (FST-PM: 9.5 (7.0-11.0); HAND-PM: 10.0 (4.0-14.5), median (interquartile range); U = 46.5; P>0.10). A prior test in the plus-maze (PM-FST) did not change % immobility time in the FST when compared to the HAND-FST group (HAND-FST: 57.7 ± 3.9; PM-FST: 65.7 ± 3.2; mean ± SEM; P>0.10). Since these data suggest that there is an order effect, the correlation was evaluated separately with each test sequence: FST-PM (N = 20) and PM-FST (N = 18). There was no significant correlation between % immobility time in the FST and plus-maze indexes (% time and entries in open arms) in any test sequence (r: -0.07 to 0.18). These data suggest that mouse behavior in the elevated plus-maze is not related to behavior in the forced swimming test and that a forced swimming test before the plus-maze has an anxiogenic effect even after a one-week interval.

The brain decade in debate: II. Panic or anxiety? From animal models to a neurobiological basis

This article is a transcription of an electronic symposium sponsored by the Brazilian Society of Neuroscience and Behavior (SBNeC). Invited researchers from the European Union, North America and Brazil discussed two issues on anxiety, namely whether panic is a very intense anxiety or something else, and what aspects of clinical anxiety are reproduced by animal models. Concerning the first issue, most participants agreed that generalized anxiety and panic disorder are different on the basis of clinical manifestations, drug response and animal models. Also, underlying brain structures, neurotransmitter modulation and hormonal changes seem to involve important differences. It is also common knowledge that existing animal models generate different types of fear/anxiety. A challenge for future research is to establish a good correlation between animal models and nosological classification.

Head-to-head comparison of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia in an animal model of coronary artery stenosis

To compare the sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia we produced a physiologically significant stenosis in the left circumflex artery of 14 open-chest dogs (range: 50 to 89% reduction in luminal diameter). In each study, dobutamine (5 to 40 µg kg-1 min-1 in 3-min stages) and pacing (20 bpm increments, each 2 min, up to 260 bpm) were performed randomly, and then followed by dipyridamole (up to 0.84 mg/kg over 10 min). The positivity of stress echocardiography tests was quantitatively determined by a significant (P<0.05) reduction of or failure to increase absolute and percent systolic wall thickening in the stenotic artery supplied wall, as compared to the opposite wall (areas related to the left anterior descending artery). Systolic and diastolic frozen images were analyzed off-line by two blinded observers in the control and stress conditions. The results showed that 1) the sensitivity of dobutamine, dipyridamole and pacing stress tests was 57, 57 and 36%, respectively; 2) in animals with positive tests, the mean percent change of wall thickening in left ventricular ischemic segments was larger in the pacing (-19 ± 11%) and dipyridamole (-18 ± 16%) tests as compared to dobutamine (-9 ± 6%) (P = 0.05), but a similar mean reduction of wall thickening was observed when this variable was normalized to a control left ventricular segment (area related to the left anterior descending artery) (pacing: -16 ± 7%; dipyridamole: -25 ± 16%; dobutamine: -26 ± 10%; not significant), and 3) a significant correlation was observed between magnitude of coronary stenosis and left ventricular segmental dysfunction induced by ischemia in dogs submitted to positive stress tests. We conclude that the dobutamine and dipyridamole stress tests showed identical sensitivities for the detection of myocardial ischemia in this one-vessel disease animal model with a wide range of left circumflex artery stenosis. The pacing stress test was less sensitive, but the difference was not statistically significant. The magnitude of segmental left ventricular dysfunction induced by ischemia was similar in all stress tests evaluated.

Can organic and transgenic soy be used as a substitute for animal protein by rats?

We evaluated the protein quality of organic and transgenic soy fed to rats throughout life. Thirty female Wistar rats were divided into three groups (N = 10): organic soy group (OSG) receiving organic soy-based diet, genetically modified soy group (GMSG) receiving transgenic soy-based diet, and a control group (CG) receiving casein-based diet. All animals received water and isocaloric diet (10% protein), ad libitum for 291 days. After this, the weight of GMSG animals (290.9 ± 9.1 g) was significantly lower (P <= 0.04) than CG (323.2 ± 7.9 g). The weight of OSG (302.2 ± 8.7 g) was between that of the GMSG and the CG. Protein intake was similar for OSG (308.4 ± 6.8 g) and GMSG (301.5 ± 2.5 g), and significantly lower (P <= 0.0005) than the CG (358.4 ± 8.1 g). Growth rate was similar for all groups: OSG (0.80 ± 0.02 g), GMSG (0.81 ± 0.03 g) and CG (0.75 ± 0.02 g). In addition to providing a good protein intake and inducing less weight gain, both types of soy were utilized in a manner similar to that of casein, suggesting that the protein quality of soy is similar to that of the standard protein casein. The groups fed soy-based diet gained less weight, which may be considered to be beneficial for health. We conclude that organic and transgenic soy can be fed throughout life to rats in place of animal protein, because contain high quality protein and do not cause a marked increase in body weight.

Effect of Erythrina velutina and Erythrina mulungu in rats submitted to animal models of anxiety and depression

Erythrina velutina (EV) and Erythrina mulungu (EM), popularly used in Brazil as tranquilizing agents, were studied. The effects of acute and chronic oral treatment with a water:alcohol extract of EV (7:3, plant grounded stem bark; acute = 100, 200, 400 mg/kg; chronic = 50, 100, 200 mg/kg) were evaluated in rats (N = 11-12) submitted to the elevated T-maze (for avoidance and escape measurements) model of anxiety. This model was selected for its presumed capacity to elicit specific subtypes of anxiety disorders recognized in clinical practice: avoidance has been related to generalized anxiety and escape to panic. Additionally, animals were treated with the same doses of EV and EM (water:alcohol 7:3, inflorescence extract) and submitted to the forced swim test for the evaluation of antidepressant activity (N = 7-10). Both treatment regimens with EV impaired elevated T-maze avoidance latencies, without altering escape, in a way similar to the reference drug diazepam (avoidance 1, mean ± SEM, acute study: 131.1 ± 45.5 (control), 9.0 ± 3.3 (diazepam), 12.7 ± 2.9 (200 mg/kg), 28.8 ± 15.3 (400 mg/kg); chronic study: 131.7 ± 46.9 (control), 35.8 ± 29.7 (diazepam), 24.4 ± 10.4 (50 mg/kg), 29.7 ± 11.5 (200 mg/kg)). Neither EV nor EM altered measurements performed in the forced swim test, in contrast to the reference drug imipramine that significantly decreased immobility time after chronic treatment. These results were not due to motor alterations since no significant effects were detected in an open field. These observations suggest that EV exerts anxiolytic-like effects on a specific subset of defensive behaviors which have been associated with generalized anxiety disorder.

The immunomodulator glatiramer acetate influences spinal motoneuron plasticity during the course of multiple sclerosis in an animal model

The immunomodulador glatiramer acetate (GA) has been shown to significantly reduce the severity of symptoms during the course of multiple sclerosis and in its animal model - experimental autoimmune encephalomyelitis (EAE). Since GA may influence the response of non-neuronal cells in the spinal cord, it is possible that, to some extent, this drug affects the synaptic changes induced during the exacerbation of EAE. In the present study, we investigated whether GA has a positive influence on the loss of inputs to the motoneurons during the course of EAE in rats. Lewis rats were subjected to EAE associated with GA or placebo treatment. The animals were sacrificed after 15 days of treatment and the spinal cords processed for immunohistochemical analysis and transmission electron microscopy. A correlation between the synaptic changes and glial activation was obtained by performing labeling of synaptophysin and glial fibrillary acidic protein using immunohistochemical analysis. Ultrastructural analysis of the terminals apposed to alpha motoneurons was also performed by electron transmission microscopy. Interestingly, although the GA treatment preserved synaptophysin labeling, it did not significantly reduce the glial reaction, indicating that inflammatory activity was still present. Also, ultrastructural analysis showed that GA treatment significantly prevented retraction of both F and S type terminals compared to placebo. The present results indicate that the immunomodulator GA has an influence on the stability of nerve terminals in the spinal cord, which in turn may contribute to its neuroprotective effects during the course of multiple sclerosis.