Os autores gostariam de agradecer ao Canadian Institutes of Health Research (MOP53116) e Alberta Heritage Foundation for Medical Research para a concessão operacional e fundo de estabelecimento, respectivamente, para apoiar o desenvolvimento deste modelo experimental.

1. Anestesia <ol><li> Definir a velocidade de fluxo da máquina de anestesia em 2L/min. Ligue o escape de sucção a vácuo. </li><li> Máscara de carga cara com gás anestésico (isoflurano) a 5% (~ 3 min). </li><li> Leitões recém-nascidos serão induzidos com isoflurano inalado 5% em 100% de oxigénio (~ 3 min). </li><li> Manter a anestesia em 2-3% de isoflurano. Ajuste fino de isoflurano 0,5% consoante o caso, no entanto, pode variar de 0,5 a 5%, dependendo da condição de leitões. </li><li> Uma vez que o acesso vascular foi estabelecida, a anestesia por inalação pode ser comutada para a anestesia intravenosa utilizando fentanil (5-50 mcg / kg / h) e midazolam (200-500 mcg / kg / h) infusões. Pancurónio (50-100 mcg / kg / h) pode ser obrigado a controlar os movimentos musculares excessivas durante a cirurgia, enquanto que a capacidade de observar estado animal é preservado para o ajustamento de drogas anestésicas. </li><li> O leitão é monitorada por oximetria de pulso (percutânea de oxigênio saturation a 95-100%) e ECG (ritmo cardíaco em 130-170 batimentos / min). </li><li> Temperatura retal do leitão é mantido a 38-40 ° C com manta de aquecimento e aquecedor radiante. </li><li> O estado anestésico do leitão está sendo avaliado regularmente durante todo o período experimental com neurológicos (tamanho da pupila, lacrimejamento, movimentos do corpo), comportamentais (agitação), cardiovascular (taquicardia e hipertensão) e respiratória (taquipneia) parâmetros como apropriado. Paralisia mínimo é dado. Experiência anterior de anestesia em leitões com e sem paralisia seria útil para a avaliação. </li><li> O protocolo é um procedimento não-sobrevivência com a eutanásia dos animais no final do experimento com uma overdose de pentobarbital (100 mg / kg) por via intravenosa. </li></ol> 2. Cirurgia de colocação de cateteres vasculares na virilha (Figura 1) <ol><li> Faça uma incisão 2-3cm de comprimento na virilha direita. </li><li> Dissecar um centímetro da veia femoral direita e retidão 1 centímetrot artéria femoral. Coloque duas cordas 3-0 em torno de cada navio. </li><li> Cateterização venosa femoral direita: Ligar o distal da veia. Inserir um cateter Argyle (3,5 ou 5 French, duplo-lúmen) (Covidien, Mansfield, MA) a 15cm e isso vai colocar no átrio direito. Amarre as duas cordas para fixar o cateter. O cateter pode ser usado para fluido de manutenção e de infusão de medicamentos (porta secundária) e venosa central / medição da pressão atrial direita (porta principal). </li><li> Cateterismo femoral direito arterial: Ligar o distal da artéria. Levante-se a cadeia de proximal para parar o fluxo de sangue. Inserir um cateter Argyle (3,5 ou 5 francês, único lúmen) a 5cm. Isto irá colocar o cateter arterial na aorta infra-renal para a medição contínua da pressão arterial média e a amostragem de sangue. Amarre as duas cordas para fixar o cateter. </li><li> Fechar a pele. </li></ol> 3. Estabelecer ventilação mecânica (Figura 2) <ol><li> Fazer uma horizontal 2-3cm de comprimentoincisão no pescoço. </li><li> Dissecar e expor um centímetro da traquéia. Coloque duas cordas 1-0 ao redor da traquéia. </li><li> Insira um tubo endotraqueal (3.0 ou 3.5) a um centímetro na traquéia. Conectar a um ventilador e iniciar ventilação mecânica. Fixe o tubo endotraqueal. </li><li> Dissecar e expor a artéria carótida comum. Cercar o navio com um fluxo de tempo de trânsito sonda de ultra-som (2SB ou 2RB, Transonic Systems Inc., Ithica, NY) para medir continuamente o fluxo de sangue. </li></ol> 4. Colocação de sondas de fluxo em mesentérica superior (Figura 3) e renal esquerda (Figura 4) artérias <ol><li> Doses adicionais de fentanil (5-10 mcg / kg) e acepromazina (0,01-0,02 mg / kg) são necessárias antes da incisão da pele. </li><li> Fazer uma incisão lateral-subcostal longa e dissecar cuidadosamente camadas musculares. </li><li> Exposição da aorta abdominal. </li><li> Minimizar manuseamento vascular (vasospasmo) e lesão linfática. </li><li> Dissecar 0,5 a 1 cm ea artéria mesentérica superiorcolocar uma sonda de fluxo Transonic (3SB) em torno dele. </li><li> Dissecar 0,5 a 1 cm da artéria renal esquerda e colocar uma sonda de fluxo Transonic (2SB) em torno dele. </li><li> Fechar a pele e fixar a sonda de fluxo. </li></ol> 5. A colocação de cateter na artéria pulmonar (Figura 5) e o fluxo de sonda (Figura 6) <ol><li> Doses adicionais de fentanil (5-10 mcg / kg) e acepromazina (0,01-0,02 mg / kg) são necessárias antes da incisão da pele. </li><li> Deite o animal na posição de lateral direito. </li><li> Toracotomia no 4 º espaço intercostal esquerdo. </li><li> Cuidado com a artéria mamária interna e veia, ligadura se necessário. </li><li> Utilize um cotonete dental para pressionar para baixo o pulmão esquerdo e aumentar o oxigênio, se necessário. </li><li> Abra o pericárdio. </li><li> Identificar o canal arterial, que vai da artéria pulmonar à aorta. </li><li> Canal arterial pode ser ligado pela colocação de um clipe ou por um grosso &quot;3-O seda&quot; gravata em sua origem. </li><li> A artéria pulmonar principal e livre passagem avestilingue ascular usando uma espessa &quot;0&quot; gravata. </li><li> Realizar um fio de bolsa (5-0 prolene) sutura na base para a colocação do cateter de artéria pulmonar. </li><li> Inserir um angiocath de calibre 20G (com 3 orifícios laterais em menos de 1 cm da ponta do cateter), através do fio de bolsa até um máximo de 1 cm. </li><li> Verifique se há livre fluxo de sangue venoso. </li><li> Conecte-se transdutor de pressão, verificar pressão arterial pulmonar e forma de onda. </li><li> Aperte o fio de bolsa e prenda o cateter pulmonar. </li><li> Colocar uma sonda de fluxo Transonic (6SB) em torno da artéria pulmonar principal. </li><li> Coloque gel de ultra-sons entre a sonda de fluxo e de artéria para permitir a transdução de sinal óptima. </li><li> Cobrir a ferida com gaze salina úmida. </li></ol> 6. Hipóxia e reoxigenação protocolo <ol><li> Reduzir a concentração de oxigénio inspirado para 10% por aumento da concentração de gás de azoto para induzir a hipoxemia inalado. </li><li> Ajuste o oxigênio inspiradoconcentração entre 10% e 15% para se obter uma PaO 2 de 20-40 mmHg ou SaO 2 de 30-40%, durante 2 h. </li><li> Realizar análise de sangue arterial para avaliar PaCO 2 e ajustar a taxa de ventilação de acordo. </li><li> Com a indução de hipoxemia, a primeira hora é dedicada a indução de uma resposta constante (e o débito cardíaco) taquicardia. </li><li> Continue a acompanhar as mudanças no fluxo de sangue no comum mesentérica, carótida superior e esquerda artérias renais. </li><li> Durante a segunda hora de hipóxia, o stress hipóxico é aumentada para saída constante inferior cardíaca a 30-40% da linha de base, a pressão arterial média de 30-35 mmHg e pH arterial 6,95-7,05. </li><li> Estresse hipóxico pode ser encerrado prematuramente ou prorrogado por 15 min, conforme apropriado. </li><li> Aumentar a concentração de oxigênio inspirado abruptamente para 100% abruptamente interrompendo gás nitrogênio, continuando oxigênio puro. </li><li> Monitorar o débito cardíaco, pressão arterial média e outros hemodinâmica parágrafometros para a rápida recuperação. </li><li> Ressuscitação com oxigênio a 100% pode ser continuado por 0,5 h. Após este período de tempo, reduzir a concentração de oxigénio inspirado para 21% rapidamente. </li><li> Continuar reoxigenação com 21% de oxigênio para o restante período de experiência. A concentração de oxigénio inspirado pode ser titulada para 25%, se necessário. </li><li> Bolus de fluido de uma solução a 10 ml / kg de Ringer de lactato pode ser necessária, conforme apropriado, durante o período experimental. Seu uso deve ser protocolizado. </li></ol> 7. Resultados representativos: A indução de hipoxemia no leitão recém-nascido durante a primeira hora de hipóxia deve aumentar o débito cardíaco (fluxo arterial pulmonar) e 120% -130% dos valores iniciais (Figura 7A) e a frequência cardíaca (Figura 7B). Normalmente, o débito cardíaco deve atingir o seu pico de compensação entre o primeiro e 0,5 h 1h de hipóxia. Além disso, o fluxo de sangue deve ser centralizada, resultando em diminuição mimperfusão senteric e renal, mas um aumento do fluxo ou preservado carótida comum arterial (Figura 8). Durante a segunda hora de hipóxia, há uma diminuição contínua do débito cardíaco, o desenvolvimento de hipotensão (Figura 9A), diminuição da frequência cardíaca, com ou sem arritmia ocorreu. Hipóxia deve induzir hipertensão pulmonar, com a pressão da artéria pulmonar aumentado (Figura 9B), a qual pode por vezes reduzir no min 30 final de hipóxia como a diminuição do débito cardíaco. Após a reanimação, todos os parâmetros hemodinâmicos vai recuperar imediatamente a linha de base normóxica, exceto para o fluxo de sangue renal, que se recupera gradualmente durante a primeira hora de reoxigenação. No entanto, os parâmetros hemodinâmicos, especialmente para o débito cardíaco e da pressão arterial média deteriora-se gradualmente ao longo de 2 horas, antes de a reoxigenação e cerca de 70-75% da linha de base normóxicas e 35-45 mm Hg, respectivamente. Este dysfuncti cardiovascularem, pelo menos, em parte, para o atordoamento do miocárdio e garante cardiovasculares terapias de apoio, tais como agentes vasoativos e inotrópicos. <img alt="Figura 1" src="/files/ftp_upload/3166/3166fig1.jpg" /> Figura 1: incisão na virilha com a colocação de cateteres femorais arteriais e venosos <img alt="Figura 2" src="/files/ftp_upload/3166/3166fig2.jpg" /> Figura 2: incisão do pescoço com a colocação de um tubo endotraqueal e uma sonda de fluxo em torno da artéria carótida comum <img alt="Figura 3" src="/files/ftp_upload/3166/3166fig3.jpg" /> Figura 3: incisão de flanco com o isolamento da artéria mesentérica superior <img alt="Figura 4" src="/files/ftp_upload/3166/3166fig4.jpg" /> Figura 4: incisão de flanco com o isolamento da artéria renal esquerda <img alt="Figura 5" src = &quot;files/ftp_upload/3166/3166fig5.jpg /&quot; /&gt; Figura 5: A toracotomia com a colocação de cateter na artéria pulmonar <img alt="Figura 6" src="/files/ftp_upload/3166/3166fig6.jpg" /> Figura 6: A toracotomia com a colocação de uma sonda de fluxo em torno Transonic artéria pulmonar principal <img alt="Figura 7" src="/files/ftp_upload/3166/3166fig7.jpg" /> Figura 7: mudanças temporais no (A) o débito cardíaco (fluxo arterial pulmonar) e (B) a freqüência cardíaca durante a hipóxia e reoxigenação <img alt="Figura 8" src="/files/ftp_upload/3166/3166fig8.jpg" /> Figura 8: Mudanças temporais no fluxo sanguíneo em (A), carótida comum (B) mesentérica superior e (C) artérias renais esquerdas durante hipóxia e reoxigenação <img alt="Figura 9" src="/files/ftp_upload/3166/3166fig9.jpg" /> Figura 9: Temporalmudanças no (A) e pressão arterial média (B) a pressão da artéria pulmonar durante hipóxia e reoxigenação

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Não há conflitos de interesse declarados.

O actual protocolo experimental tem uma vantagem para examinar as alterações sistêmicas e regionais hemodinâmicos em indivíduos recém-nascidos durante o processo de hipóxia e reoxigenação. Nós podemos também examinar o respectivo efeito das intervenções utilizadas para melhorar a função cardiovascular durante a recuperação. Nós e outros relatam a experiência e os resultados do estudo de asfixia neonatal em relação aos efeitos cardiovasculares em 1, 2 pulmonar, neurológica 3, 4...

a swine model of neonatal asphyxia

Anualmente mais de 1 milhão de recém-nascidos morrem no mundo como relacionado à asfixia. Neonatos asfixiados comumente têm falência de múltiplos órgãos, incluindo hipotensão déficit de perfusão, encefalopatia hipóxico-isquêmica, hipertensão pulmonar, enterocolite vasculopathic, insuficiência renal e complicações tromboembólicas. Os modelos animais são desenvolvidos para nos ajudar a entender a fisiopatologia e farmacologia de asfixia neonatal. Em comparação com os roedores e os cordeiros recém-nascido, o leitão recém-nascido foi provado ser um modelo válido. O leitão recém-nascido tem várias vantagens, incluindo desenvolvimento semelhante à de 36-38 semanas feto humano com sistemas do corpo comparáveis, tamanho grande massa (~ 1,5-2 kg no nascimento), que permite a instrumentação e monitoramento do animal e controla as variáveis ​​de confusão de desarranjos hipóxia e hemodinâmica. Nós aqui descrever um protocolo experimental para simular a asfixia neonatal e nos permite examinar a systemic e regionais alterações hemodinâmicas durante o processo asfixiantes e reoxigenação assim como os respectivos efeitos de intervenções. Além disso, o modelo tem a vantagem de se estudar falha de múltiplos órgãos ou disfunção em simultâneo e a interacção com vários sistemas do corpo. O modelo experimental é um procedimento não-sobrevivência que envolve a instrumentação cirúrgica de leitões recém-nascidos (raça dias de idade e 1,5-2,5 kg de peso, 1-3 misto) para permitir o estabelecimento de ventilação mecânica, de acesso (arterial e venoso central) vascular ea colocação de cateteres e sondas de fluxo (Transonic Inc.) para a monitorização contínua da pressão intra-vascular e fluxo de sangue através das artérias diferentes, incluindo principal carótida, pulmonar comum, mesentérica superior e esquerda artérias renais. Usando estes leitões cirurgicamente instrumentados, após estabilização durante 30-60 minutos, tal como definidos pela variação Z &lt;10% nos parâmetros hemodinâmicos e gases sanguíneos normais, iniciar um protocolo experimentalde hipoxemia grave que é induzida através de hipóxia alveolar normocápnica. O porquinho é ventilada com oxigénio de 10-15% por aumento da concentração de gás inalado azoto durante 2 h, com o objectivo de saturações de oxigénio arterial de 30-40%. Este grau de hipoxemia vai produzir asfixia clínica com acidose metabólica grave, hipotensão e choque cardiogênico com hipoperfusão de órgãos vitais. A hipoxia é seguida por reoxigenação com oxigénio a 100% durante 0,5 horas e, em seguida, 21% de oxigénio durante 3,5 h. Intervenções farmacológicas podem ser introduzidas em devido tempo e os seus efeitos investigada em ocultação, moda em blocos ao acaso.

Watch this Scientific Journal Video about A Swine Model of Neonatal Asphyxia at JoVE.com

A Swine Model of Neonatal Asphyxia

Modelos animais de grande porte têm bons valores de translação no exame de fisiologia e farmacologia da asfixia neonatal. Usando leitões recém-nascidos, desenvolvemos um protocolo experimental para simular a asfixia neonatal, que tem as vantagens de estudar a hemodinâmica sistêmica e regional, o transporte de oxigênio com vias bioquímicas e patológicas e correlações.

Um Modelo de Suínos de asfixia neonatal

Annually more than 1 million neonates die worldwide as related to asphyxia. Asphyxiated neonates commonly have multi-organ failure including hypotension, ...

Research

JoVE Journal

Medicine

14.2K visualizações.  University of Alberta. Modelos animais de grande porte têm bons valores de translação no exame de fisiologia e farmacologia da asfixia neonatal. Usando leitões recém-nascidos, desenvolvemos um protocolo experimental para simular a asfixia neonatal, que tem as vantagens de estudar a hemodinâmica sistêmica e regional, o transporte de oxigênio com vias bioquímicas e patológicas e correlações.

Vídeo: A Swine Model of Neonatal Asphyxia

A Piglet Model of Neonatal Hypoxic-Ischemic Encephalopathy

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the world&#8217;s 2.9 million neonatal deaths. Animal models of HIE have contributed to the understanding of the pathophysiology in HIE, and have highlighted the dynamic process that occur in brain injury due to perinatal asphyxia. Thus, animal studies have suggested a time-window for post-insult treatment strategies. Hypothermia has been tested as a treatment for HIE in pdiglet models and subsequently proven effective in clinical trials. Variations of the model have been applied in the study of adjunctive neuroprotective methods and piglet studies of xenon and melatonin have led to clinical phase I and II trials1,2. The piglet HIE model is further used for neonatal resuscitation- and hemodynamic studies as well as in investigations of cerebral hypoxia on a cellular level. However, it is a technically challenging model and variations in the protocol may result in either too mild or too severe brain injury. In this article, we demonstrate the technical procedures necessary for establishing a stable piglet model of neonatal HIE. First, the newborn piglet (&#60; 24 hr old, median weight 1500 g) is anesthetized, intubated, and monitored in a setup comparable to that found in a neonatal intensive care unit. Global hypoxia-ischemia is induced by lowering the inspiratory oxygen fraction to achieve global hypoxia, ischemia through hypotension and a flat trace amplitude integrated EEG (aEEG) indicative of cerebral hypoxia. Survival is promoted by adjusting oxygenation according to the aEEG response and blood pressure. Brain injury is quantified by histopathology and magnetic resonance imaging after 72 hr.

Hypoxic-ischemic encephalopathy following perinatal asphyxia can be studied using animal models. We demonstrate the procedures necessary for establishing a piglet model of neonatal hypoxic-ischemic encephalopathy.

Um Modelo de Leitão Neonatal encefalopatia hipóxico-isquêmica

Birth asphyxia, which causes hypoxic-ischemic encephalopathy (HIE), accounts for 0.66 million deaths worldwide each year, about a quarter of the ...

Medicina

A Neonatal Mouse Spinal Cord Compression Injury Model

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal cord. A major current area of research is focused on the mechanisms of adaptive plasticity that underlie spontaneous or induced functional recovery following SCI. Spontaneous functional recovery is reported to be greater early in life, raising interesting questions about how adaptive plasticity changes as the spinal cord develops. To facilitate investigation of this dynamic, we have developed a SCI model in the neonatal mouse. The model has relevance for pediatric SCI, which is too little studied. Because neural plasticity in the adult involves some of the same mechanisms as neural plasticity in early life1, this model may potentially have some relevance also for adult SCI. Here we describe the entire procedure for generating a reproducible spinal cord compression (SCC) injury in the neonatal mouse as early as postnatal (P) day 1. SCC is achieved by performing a laminectomy at a given spinal level (here described at thoracic levels 9-11) and then using a modified Yasargil aneurysm mini-clip to rapidly compress and decompress the spinal cord. As previously described, the injured neonatal mice can be tested for behavioral deficits or sacrificed for ex vivo physiological analysis of synaptic connectivity using electrophysiological and high-throughput optical recording techniques1. Earlier and ongoing studies using behavioral and physiological assessment have demonstrated a dramatic, acute impairment of hindlimb motility followed by a complete functional recovery within 2 weeks, and the first evidence of changes in functional circuitry at the level of identified descending synaptic connections1.

This article describes a method for generating a reproducible spinal cord compression injury (SCI) in the neonatal mouse. The model provides an advantageous platform for studying mechanisms of adaptive plasticity that underlie spontaneous functional recovery.

A Neonatal do rato Spinal Cord Injury Compression Modelo

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal ...

Myocardial Infarction in Neonatal Mice, A Model of Cardiac Regeneration

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and regeneration, and to define new targets for therapeutics. For decades, models of complete heart regeneration existed in amphibians and fish, but a mammalian counterpart was not available. The recent discovery of a postnatal window during which mice possess regenerative capabilities has led to the establishment of a mammalian model of cardiac regeneration. A surgical model of mammalian cardiac regeneration in the neonatal mouse is presented herein. Briefly, postnatal day 1 (P1) mice are anesthetized by isoflurane and placed on an ice pad to induce hypothermia. After the chest is opened, and the left anterior descending coronary artery (LAD) is visualized, a suture is placed around the LAD to inflict myocardial ischemia in the left ventricle. The surgical procedure takes 10-15 min. Visualizing the coronary artery is crucial for accurate suture placement and reproducibility. Myocardial infarction and cardiac dysfunction are confirmed by triphenyl-tetrazolium chloride (TTC) staining and echocardiography, respectively. Complete regeneration 21 days post myocardial infarction is verified by histology. This protocol can be used to as a tool to elucidate mechanisms of mammalian cardiac regeneration after myocardial infarction.

This protocol describes a highly reproducible model of cardiac regeneration by surgical induction of myocardial infarction in the left ventricle of postnatal day 1 mice. The method involves induction of hypothermic anesthesia and ligation of the left anterior descending coronary artery.

Infarto do miocárdio em ratos neonatais, um modelo de regeneração cardíaca

Myocardial infarction induced by coronary artery ligation has been used in many animal models as a tool to study the mechanisms of cardiac repair and ...

A Chronic Cardiac Ischemia Model in Swine Using an Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but regardless of the approach, an in vivo model is needed to test each treatment. The pig is one of the most used large animal models for cardiovascular disease. Its heart is very similar in anatomy and function to that of a human. The ameroid placement technique creates an ischemic area of the heart, which has many useful applications in studying myocardial infarction. This model has been used for surgical research, pharmaceutical studies, imaging techniques, and cell therapies.
There are several ways of inducing an ischemic area in the heart. Each has its advantages and disadvantages, but the placement of an ameroid constrictor remains the most widely used technique. The main advantages to using the ameroid are its prevalence in existing research, its availability in various sizes to accommodate the anatomy and size of the vessel to be constricted, the surgery is a relatively simple procedure, and the post-operative monitoring is minimal, since there are no external devices to maintain. This paper provides a detailed overview of the proper technique for the placement of the ameroid constrictor.

The purpose of this protocol is to demonstrate the placement of a delayed constricting device (an ameroid constrictor) around a coronary artery in a swine model. This device creates an ischemic area of the heart that is useful for studying new diagnostic imaging techniques and new methods of treatment.

Um modelo de isquemia cardíaca crônica em suínos, usando um Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but ...

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

Cardiomiopatia induzida por taquicardia como um modelo de insuficiência cardíaca crônica em suínos

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

Severe Burn Injury in a Swine Model for Clinical Dressing Assessment

Wound healing is a dynamic repair process and is the most complex biological process in human life. In response to burn injury, alterations in biological pathways impair the inflammation response, resulting in delayed wound healing. Impaired wound healing frequently occurs in patients with diabetes leading to unfavorable outcomes such as amputation. Hence, dressings having beneficial effect in promoting burn wound repair are needed. However, studies on burn wound treatment are limited due to lack of proper animal models. Our previous study demonstrated wound-healing performance in rat and swine models using a minimally invasive surgical technique. This study aimed to demonstrate a swine model of severe burn injury that eliminates wound contraction and more closely approximates the human processes of re-epithelialization and new tissue formation. This protocol provides a detailed procedure for creating consistent burn wounds and examining the wound-healing performance under the treatment of an experimental dressing in a swine model. Six burn wounds were created symmetrically on the dorsum, which were covered with a clinical dressing composed of four layers: an inner contact layer of experimental materials, an inner intermediate layer of waterproof film, an outer intermediate layer of gauze, and an outer layer of adhesive plaster. Upon the completion of experiments, wound closure, wound area, and Vancouver Scar Scale score were examined. The samples of skin resected from each animal post-sacrifice were histologically prepared and stained using hematoxylin and eosin staining. Antibacterial activity of each dressing in the context of wound healing was also examined. The application of the clinical dressing to the wounds in swine model mimics the biological processes of human wound healing with respect to the processes of epithelialization, cellular proliferation, and angiogenesis. Therefore, this swine model provides an easy-to-learn, cost-effective, and robust method to assess the effect of clinical dressings in severe burn injury.

To closely mimic the mode of burn injuries requires the interplay between clinical observation and studies in animal models. In this study, a swine model of severe burn injury was established to assess an experimental dressing in physiological and pathophysiological settings.

Queimadura grave lesão em um modelo de suíno para avaliação clínica de vestir

Wound healing is a dynamic repair process and is the most complex biological process in human life. In response to burn injury, alterations in biological ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

Medição de contratilidade isométrica da artéria mesentérica Mouse usando fio miografia

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.

We sought to establish a swine model of heart failure induced by left circumflex artery blockage and rapid pacing to test the effect and safety of intramyocardial administration of stem cells for cell-based therapies.

Estabelecendo um modelo suíno de insuficiência cardíaca pós-miocárdio para tratamento de células-tronco

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major ...

Myocardial Infarction by Percutaneous Embolization Coil Deployment in a Swine Model

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization and cardiovascular drugs, a significant proportion of patients develop pathological left-ventricular remodeling and progressive heart failure following MI. Therefore, new therapeutic options, such as cellular and gene therapies, among others, have been developed to repair and regenerate injured myocardium. In this context, animal models of MI are crucial in exploring the safety and efficacy of these experimental therapies before clinical translation. Large animal models such as swine are preferred over smaller ones due to the high similarity of swine and human hearts in terms of coronary artery anatomy, cardiac kinetics, and the post-MI healing process. Here, we aimed to describe an MI model in pig by permanent coil deployment. Briefly, it comprises a percutaneous selective coronary artery cannulation through retrograde femoral access. Following coronary angiography, the coil is deployed at the target branch under fluoroscopic guidance. Finally, complete occlusion is confirmed by repeated coronary angiography. This approach is feasible, highly reproducible, and emulates the pathogenesis of human non-revascularized MI, avoiding the traditional open-chest surgery and the subsequent postoperative inflammation. Depending on the time of follow-up, the technique is suitable for acute, sub-acute, or chronic MI models.

Myocardial infarction (MI) animal models that emulate the natural process of the disease in humans are crucial to understanding pathophysiological mechanisms and testing the safety and efficacy of new emergent therapies. Here, we describe an MI swine model created by deploying a percutaneous embolization coil.

Infarto do Miocárdio por implantação de bobina de embolização percutânea em um modelo de suíno

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization ...

A Neonatal BALB/c Mouse Model of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal (GI) disease that often occurs in premature infants, especially very low birth weight infants, with high mortality and unclear pathogenesis. The cause of NEC may be related to inflammatory immune regulatory system abnormalities. An NEC animal model is an indispensable tool for NEC disease immune research. NEC animal models usually use C57BL/6J neonatal mice; BALB/c neonatal mice are rarely used. Related studies have shown that when mice are infected, Th2 cell differentiation is predominant in BALB/c mice compared to C57BL/6J mice. Studies have suggested that the occurrence and development of NEC are associated with an increase in T helper type 2 (Th2) cells and are generally accompanied by infection. Therefore, this study used neonatal BALB/c mice to induce an NEC model with similar clinical characteristics and intestinal pathological changes as those observed in children with NEC. Further study is warranted to determine whether this animal model could be used to study Th2 cell responses in NEC.

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal (GI) disease that often occurs in premature infants, especially very low birth weight infants, with high mortality and unclear pathogenesis. The cause of NEC may be related to inflammatory immune regulatory system abnormalities. An NEC animal model is an indispensable tool for NEC disease immune research. NEC animal models usually use C57BL/6J neonatal mice; BALB/c neonatal mice are rarely used. Related studies have shown that when mice are infected, Th2 cell differentiation is predominant in BALB/c mice compared to C57BL/6J mice. Studies have suggested that the occurrence and development of NEC are associated with an increase in T helper type 2 (Th2) cells and are generally accompanied by infection. Therefore, this study used neonatal BALB/c mice to induce an NEC model with similar clinical characteristics and intestinal pathological changes as those observed in children with NEC. Further study is warranted to determine whether this animal model could be used to study Th2 cell responses in NEC.

Um modelo de rato BALB/c neonatal de Enterocolite Necrotizante

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal (GI) disease that often occurs in premature infants, especially very low birth weight ...