Lesão oxidativa eritrocitária e mecanismos antioxidantes de interesse na Medicina Veterinária

Free radicals are produced continuously in normal cell metabolism and in various pathological events. When in excess, they may cause oxidation of biologic molecules. As a protection mechanism, the body has a complex system of antioxidant defense. The imbalance between oxidative challenge and antioxidant defense capacity is called oxidative stress. Erythrocytes play vital functions in the body which can be compromised due to oxidative stress. Red blood cells become vulnerable to oxidative injury due to their constitution. Membrane unsaturated lipids are highly susceptible to oxidation, and the presence of oxygen and iron enhances free radicals formation. Furthermore, red blood cells are unable to synthesize new lipids and proteins to replace those that have been oxidized. Therefore, the maintenance of antioxidant mechanisms, such as vitamins E and C, and enzymes superoxide dismutase, catalase, glutathione system, and metahemoglobin reductase is important to prevent and repair damages. This paper reviews information about the mechanisms of erythrocyte oxidative damage and antioxidant defense system, aiming to help veterinary professionals in diagnosis and treatment of erythrocyte oxidative stress related diseases.Os radicais livres são formados constantemente no metabolismo celular normal e em vários eventos patológicos. Quando em excesso, eles podem causar a oxidação de moléculas biológicas. Como mecanismo de defesa, o organismo possui um complexo sistema de proteção antioxidante. O desequilíbrio entre o desafio oxidativo e a capacidade de defesa antioxidante denomina-se estresse oxidativo. Os eritrócitos desempenham funções vitais ao organismo que podem ser comprometidas devido ao estresse oxidativo. Por sua constituição, os eritrócitos tornamse vulneráveis à lesão oxidativa. Os lipídios insaturados da membrana são altamente susceptíveis à oxidação e a presença do oxigênio e do ferro, propiciando a formação de radicais livres. Além disso, são células incapazes de sintetizar novos lipídios e proteínas para substituir os que foram oxidados. Desta forma, a manutenção dos mecanismos antioxidantes como as vitaminas E e C, enzimas superóxido dismutase e catalase, sistema glutationa e metahemoglobina redutase é importante para evitar e reparar as lesões. Este trabalho revisa informações sobre os mecanismos da lesão oxidativa e do sistema de defesa antioxidante eritrocitários, com o intuito de auxiliar os profissionais de medicina veterinária no diagnóstico e tratamento de doenças relacionadas ao estresse oxidativo eritrocitário

Application of spirometry during standard incremental exercise test on treadmill for respiratory gas exchange evaluation of Arabian horses

The current study evaluated equine gas exchange responses through spirometry, by measuring oxygenuptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (R) and maximum oxygenuptake (VO2max) of Arabian horses during a standard incremental exercise test performed on a high-speedtreadmill. Six clinically healthy Arabian horses were submitted to a standard incremental exercise test,performed on a high-speed treadmill at a 6% slope, and initial speed of 1,8 m.s-1 for 5 minutes, then 4,0m.s-1 for 3 minutes, 6,0 m.s-1 for 2 minutes and 8,0 m.s-1, 9,0 m.s-1, 10,0 m.s-1 and 11,0 m.s-1 for oneminute for each of these speed. The end of the exercise test was defined as the point in which the horse wasno longer able to keep pace with the treadmill. Gas exchange was measured through respiratory analyseshorse mask on the last 10 seconds at the end of each speed transition and at 1, 2 and 3 minutes after theend of the exercise, defined as experiment moments. During exercise, it was noticed an increase on bothVO2 and VCO2 with linear relationship between exercise and speed. Arabian horses VO2max was 114,9mL.kg-1.min-1. The respiratory exchange ratio increased over 1,0 by the speed of 9,0 m.s-1, indicating thepreponderance of the anaerobic metabolism, and remains at a high level on the post-exercise period.No presente estudo avaliou-se a troca gasosa respiratória pela mensuração do consumo de oxigênio (VO2),dióxido de carbono produzido (VCO2) e quociente respiratório (R), e determinou-se o consumo máximo deoxigênio (VO2max) de cavalos da raça Árabe durante o teste padrão de exercício progressivo em esteira dealta velocidade. Seis equinos adultos da raça Árabe, clinicamente hígidos foram submetidos ao teste emesteira com inclinação de 6%, o qual consistiu da velocidade inicial de 1,8 m/s por 5 minutos, a 4 m/s por 3minutos, a 6 m/s por 2 minutos e fases a 8 m/s, 9 m/s, 10 m/s e 11 m/s por 1 minuto cada, de modo que amanta da esteira foi parada quando os cavalos não conseguiram acompanhar a velocidade da mesma. Atroca gasosa foi monitorada por meio da máscara de análise de gases respiratórios para equinos, nosúltimos 10 segundos finais de cada mudança de velocidade e a 1, 2 e 3 minutos após o término doexercício. Durante o exercício há elevação do VO2 e VCO2 com relação linear conforme a intensidade deexercício. O VO2max dos cavalos da raça Árabe é de 114,9 mL/kg/min. O quociente respiratório eleva-separa valores maiores que 1,0 a partir da velocidade de 9,0 m/s, indicando o predomínio do metabolismoanaeróbico, e mantêm-se ainda elevado no período pós-exercício

Electrocardiographic exam in Arabian horses submitted to exercise on high-speed treadmill and vitamin E supplementation

Avaliou-se o efeito do exercício físico, treinamento e suplementação com vitamina E sobre os parâmetros eletrocardiográficos, utilizando oito éguas da raça Puro Sangue Árabe, sem treinamento prévio, distribuídos em dois grupos: controle (n=4) e suplementado com vitamina E (n=4) na dose diária de 1.000 UI. Os animais foram submetidos a uma prova de exercício progressivo (P1) em esteira de alta velocidade inclinada a +7%, em seguida a um período de treinamento de 20 dias e posteriormente uma nova prova de exercício progressivo (P2). Realizou-se a análise e interpretação dos traçados eletrocardiográficos quanto ao ritmo, frequência cardíaca, duração e amplitude das ondas e intervalos, antes, imediatamente após e 30 min após o exercício progressivo. Observou-se uma diminuição da frequência cardíaca de repouso após o treinamento. Não houve efeito da suplementação com vitamina E sobre os parâmetros eletrocardiográficos. Os resultados indicaram que o eletrocardiograma foi eficiente na detecção das alterações cardíacas promovidas pelo exercício físico, mas necessita-se de mais estudos para elucidar o seu significado clínico.The effect of physical exercise, training and vitamin E supplementation on electrocardiographic parameters was evaluated in eight untrained Arabian mares, divided into two groups: control (n=4) and supplemented with vitamin E (n=4) at the daily dose of 1.000 UI. Animals were submitted to an incremental exercise test (P1) on high-speed treadmill inclined +7%, after that to a training period of 20 days and later to a new incremental exercise test (P2). Analysis and interpretation of electrocardiographic tracings were performed regarding the rhythm, heart rate, duration and amplitude of waves and intervals, before, immediately after and 30 min after the incremental exercise. A reduction of the rest heart rate was observed after training. There was no effect of vitamin E supplementation on electrocardiographic parameters. Results indicated that the electrocardiogram was efficient in detention of cardiac alterations promoted by the physical exercise, but more studies are needed to elucidate its clinical meaning

Atividades séricas da aspartato aminotransferase, creatina quinase e lactato desidrogenase de eqüinos submetidos ao teste padrão de exercício progressivo em esteira

Objetivou-se determinar a atividade sérica das enzimas aspartato aminotransferase (AST), creatina quinase (CK) e lactato desidrogenase (LDH) de cavalos da raça Árabe submetidos a exercício em esteira de alta velocidade. Onze eqüinos adultos da raça Árabe foram condicionados e submetidos ao Teste Padrão de Exercício Progressivo em esteira. Antes, imediatamente após o término do exercício, e nos momentos pós-exercício, 30min, 60min, 3h, 6h, 12h, 24h, 3 dias e 5 dias, foram coletadas amostras de sangue venoso para as determinações séricas das enzimas aspartato aminotransferase (AST), creatina quinase (CK) e lactato desidrogenase (LDH). As concentrações séricas da AST, da CK e da LDH elevam-se imediatamente e retornam a valores semelhantes ao de repouso 30 minutos após o término do Teste Padrão de Exercício Progressivo. A atividade enzimática da aspartato aminotransferase (AST) eleva-se de 12 horas a 24 horas, da creatina quinase (CK) de 3 horas a 6 horas e da lactato desidrogenase (LDH) 24 horas após o término do Teste Padrão de Exercício Progressivo.The aim of this study was to determine the serum activities of enzymes aspartate aminotransferase, creatine kinase and lactate dehydrogenase in Arabian horses submitted to exercise on high-speed equine treadmill. Eleven mature Arabian horse were training and submitted to Standard Incremental Exercise Test on high-speed equine treadmill. Venous blood samples were taken before exercise, immediately and 30 min, 60min, 3h, 6h, 24h, 3 days and 5 days after exercise. The serum activity aspartate aminotransferase, creatine kinase and lactate dehydrogenase were determined. The serum activies of AST, CK and LDH increase immediately and returned to baseline value 30 minutes after exercise. The AST enzyme activity increased at 12 hours and 24 hours, CK at 3 hours and 6 hours, and LDH at 24 hours after Standard Incremental Exercise Test

A high fat diet during adolescence in male rats negatively programs reproductive and metabolic function which is partially ameliorated by exercise

An interaction between obesity, impaired glucose metabolism and sperm function in adults has been observed but it is not known whether exposure to a diet high in fat during the peri-pubertal period can have longstanding programmed effects on reproductive function and gonadal structure. This study examined metabolic and reproductive function in obese rats programmed by exposure to a high fat (HF) diet during adolescence. The effect of physical training (Ex) in ameliorating this phenotype was also assessed. Thirty-day-old male Wistar rats were fed a HF diet (35% lard w/w) for 30 days then subsequently fed a normal fat diet (NF) for a 40-day recovery period. Control animals were fed a NF diet throughout life. At 70 days of life, animals started a low frequency moderate exercise training that lasted 30 days. Control animals remained sedentary (Se). At 100 days of life, biometric, metabolic and reproductive parameters were evaluated. Animals exposed to HF diet showed greater body weight, glucose intolerance, increased fat tissue deposition, reduced VO 2max and reduced energy expenditure. Consumption of the HF diet led to an increase in the number of abnormal seminiferous tubule and a reduction in seminiferous epithelium height and seminiferous tubular diameter, which was reversed by moderate exercise. Compared with the NF-Se group, a high fat diet decreased the number of seminiferous tubules in stages VII-VIII and the NF-Ex group showed an increase in stages XI-XIII. HF-Se and NF-Ex animals showed a decreased number of spermatozoa in the cauda epididymis compared with animals from the NF-Se group. Animals exposed to both treatments (HF and Ex) were similar to all the other groups, thus these alterations induced by HF or Ex alone were partially prevented. Physical training reduced fat pad deposition and restored altered reproductive parameters. HF diet consumption during the peri-pubertal period induces long-term changes on metabolism and the reproductive system, but moderate and low frequency physical training is able to recover adipose tissue deposition and reproductive system alterations induced by high fat diet. This study highlights the importance of a balanced diet and continued physical activity during adolescence, with regard to metabolic and reproductive health

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Marcadores cardíacos na medicina veterinária Cardiac markers in veterinary medicine

Os marcadores cardíacos são utilizados com o intuito de auxiliar no diagnóstico clínico de animais com doença cardíaca com maior acurácia e em menor tempo possível, possibilitando o estabelecimento do prognóstico e a terapia precocemente. Entretanto, em medicina veterinária, no Brasil, sua aplicabilidade ainda é, em geral, restrita a pesquisas. Esta revisão tem como objetivo abordar os principais marcadores cardíacos para que futuramente estes possam se tornar índices essenciais na avaliação cardíaca.<br>Cardiac markers have been used in order to assist clinical diagnosis of animals with heart disease, more accurately, enabling the establishment of earlier prognosis and therapy. However, in Brazilian veterinary medicine, these markers are generally still restricted to researches. This review aims to approach the major cardiac markers, which further may become essential indexes in heart assessment