RESUMO

The crisis caused by the COVID-19 outbreak around the globe raised an increasing concern about the ongoing emergence of variants of the virus that may evade the immune response provided by vaccines. New variants appear due to mutation, and as the cases accumulate, the probability of the emergence of a variant of concern increases. In this article, we propose a modified susceptible, infected, and recovered (SIR) model with waning immunity that captures the competition of two strain classes of an infectious disease under the effect of vaccination with a highly contagious and deadlier strain class emerging from a prior strain due to mutation. When these strains compete for a limited supply of susceptible individuals, changes in the efficiency of vaccines may affect the behaviour of the disease in a non-trivial way, resulting in complex outcomes. We characterise the parameter space including intrinsic parameters of the disease, and using the vaccine efficiencies as control variables. We find different types of transcritical bifurcations between endemic fixed points and a disease-free equilibrium and identify a region of strain competition where the two strain classes coexist during a transient period. We show that a strain can be extinguished either due to strain competition or vaccination, and we obtain the critical values of the efficiency of vaccines to eradicate the disease. Numerical studies using parameters estimated from publicly reported data agree with our theoretical results. Our mathematical model could be a tool to assess quantitatively the vaccination policies of competing and emerging strains using the dynamics in epidemics of infectious diseases.

RESUMO

The brachiocephalic trunk and the left subclavian artery originate from the aortic arch, and both supply blood to the head, neck, and thoracic limbs. Anatomical variations, such as an aberrant right subclavian artery, are congenital conditions rarely observed in dogs, Thus, the objective of the present report was to describe a case of aberrant right subclavian artery in a 9-year-old Dalmatian. However, this anomaly was a finding in which the patient was asymptomatic during its 9 years of life and only at this age did he exhibit signs including sialorrhea, vomiting, hyporexia, and noisy deglutition. Blood count, biochemical profile, and thoracic radiography led to a diagnosis of megaesophagus and aspiration pneumonia. Despite the recommended treatment, the patient did not respond well; as such, the owner elected to euthanize the animal. On necropsy, the right subclavian artery originated directly from the aortic arch, followed a route from left to right dorsally to the esophagus, and then formed an impression of the vascular path over the muscular wall of the esophagus. The esophagus, in turn, exhibited a flaccid wall and dilation in the caudal portion to the vascular path made by the ectopic position of the right subclavian artery.(AU)

O tronco braquiocefálico e a artéria subclávia esquerda emergem do arco aórtico e são responsáveis por fazerem o suprimento sanguíneo para cabeça, pescoço e membros torácicos. Variações anatômicas, como a ectopia da artéria subclávia direita, são alterações congênitas raramente encontradas em cães, cujas alterações do sistema digestivo acontecem em pacientes recém-desmamados e não em adultos. Assim, o objetivo deste relato é descrever um caso de ectopia da artéria subclávia direita em uma cadela, Dálmata, de nove anos de idade. No entanto, essa anomalia foi um achado do qual o paciente foi assintomático durante os nove anos de vida e somente com essa idade apresentou sinais como sialorreia, vômito, hiporexia e deglutição ruidosa. O hemograma e os perfis bioquímicos, associados à radiografia torácica, levaram a um diagnóstico de megaesôfago e pneumonia aspirativa. Mesmo seguindo o tratamento recomendado, houve piora clínica do quadro e o animal foi submetido à eutanásia. À macroscopia, a artéria subclávia direita originava-se direto do arco aórtico, fazia um percurso da esquerda para a direita dorsalmente ao esôfago e, então, formava uma impressão do trajeto vascular sobre a parede muscular do esôfago. O esôfago, por sua vez, apresentava parede flácida e dilatação na porção caudal ao trajeto vascular feito pela posição ectópica da artéria subclávia direita.(AU)

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Objetivou-se por meio deste estudo determinar a necessidade nutricional de lisina digestível em rações para juvenis de tilápia-do-nilo (Oreochromis niloticus). Setecentos e vinte peixes masculinizados (7,30±0,11g) foram alimentados durante 30 dias com oito rações (26,81% de proteína digestível e 3090kcal/kg de energia digestível da ração) contendo teores crescentes de lisina digestível (1,24; 1,36; 1,48; 1,60; 1,72; 1,84; 1,96 e 2,08%). As tilápias foram distribuídas em delineamento inteiramente ao acaso, com oito tratamentos, seis repetições e 15 peixes por unidade experimental. Foram avaliadas variáveis de desempenho (ganho de peso, taxa de crescimento específico, taxa de sobrevivência, consumo de ração, consumo de lisina digestível, conversão alimentar aparente, eficiência proteica para ganho, eficiência de lisina para ganho e eficiência de retenção de nitrogênio) e de composição corporal (teores de umidade, gordura, proteína, matéria mineral corporal e as taxas de deposição diária de proteína e gordura corporais). A elevação do teor de lisina digestível na ração não influenciou (P>0,05) o consumo de ração, a taxa de sobrevivência e os teores de umidade e de matéria mineral corporal, mas melhorou de forma quadrática (P<0,05) os demais parâmetros avaliados, com exceção do consumo de lisina e da eficiência de lisina para ganho, que aumentou e reduziu, respectivamente, de forma linear (P<0,05). Recomenda-se que rações para juvenis de tilápia-do-nilo devam conter 1,84% de lisina digestível para máximo ganho de peso...

The aim of this study was to determine the nutritional need of lysine in diets for juvenile Nile tilapia (Oreochromis niloticus). Seven hundred and twenty masculinized fish (7.30±0.11g) were fed for 30 days with eight diets (26.81% of digestible protein and 3090 kcal/kg digestible energy of feed) containing increasing levels of lysine (1.24, 1.36, 1.48, 1.60, 1.72, 1.84, 1.96 and 2.08%). The tilapia were distributed in a completely randomized design with eight treatments and six replicates of 15 fish per experimental unit. We evaluated the performance variables (weight gain, specific growth rate, survival rate, feed intake, digestible lysine intake, feed conversion, protein efficiency for gain, efficiency of lysine for gain and efficiency of retention nitrogen) and body composition (moisture, fat, protein, ash body and deposition rates of daily protein and fat). The high levels of dietary lysine did not affect (P>0.05) feed intake, the survival rate and the moisture and ash body, but improved (P<0.05) other parameters, except for lysine intake and efficiency of lysine for gain, which increased and decreased, respectively, linearly (P<0.05). It is recommended that diets for juvenile Nile tilapia should contain 1.84% digestible lysine for maximum weight gain...

Assuntos

RESUMO

Objetivou-se por meio deste estudo determinar a necessidade nutricional de lisina digestível em rações para juvenis de tilápia-do-nilo (Oreochromis niloticus). Setecentos e vinte peixes masculinizados (7,30±0,11g) foram alimentados durante 30 dias com oito rações (26,81% de proteína digestível e 3090kcal/kg de energia digestível da ração) contendo teores crescentes de lisina digestível (1,24; 1,36; 1,48; 1,60; 1,72; 1,84; 1,96 e 2,08%). As tilápias foram distribuídas em delineamento inteiramente ao acaso, com oito tratamentos, seis repetições e 15 peixes por unidade experimental. Foram avaliadas variáveis de desempenho (ganho de peso, taxa de crescimento específico, taxa de sobrevivência, consumo de ração, consumo de lisina digestível, conversão alimentar aparente, eficiência proteica para ganho, eficiência de lisina para ganho e eficiência de retenção de nitrogênio) e de composição corporal (teores de umidade, gordura, proteína, matéria mineral corporal e as taxas de deposição diária de proteína e gordura corporais). A elevação do teor de lisina digestível na ração não influenciou (P>0,05) o consumo de ração, a taxa de sobrevivência e os teores de umidade e de matéria mineral corporal, mas melhorou de forma quadrática (P<0,05) os demais parâmetros avaliados, com exceção do consumo de lisina e da eficiência de lisina para ganho, que aumentou e reduziu, respectivamente, de forma linear (P<0,05). Recomenda-se que rações para juvenis de tilápia-do-nilo devam conter 1,84% de lisina digestível para máximo ganho de peso.(AU)

The aim of this study was to determine the nutritional need of lysine in diets for juvenile Nile tilapia (Oreochromis niloticus). Seven hundred and twenty masculinized fish (7.30±0.11g) were fed for 30 days with eight diets (26.81% of digestible protein and 3090 kcal/kg digestible energy of feed) containing increasing levels of lysine (1.24, 1.36, 1.48, 1.60, 1.72, 1.84, 1.96 and 2.08%). The tilapia were distributed in a completely randomized design with eight treatments and six replicates of 15 fish per experimental unit. We evaluated the performance variables (weight gain, specific growth rate, survival rate, feed intake, digestible lysine intake, feed conversion, protein efficiency for gain, efficiency of lysine for gain and efficiency of retention nitrogen) and body composition (moisture, fat, protein, ash body and deposition rates of daily protein and fat). The high levels of dietary lysine did not affect (P>0.05) feed intake, the survival rate and the moisture and ash body, but improved (P<0.05) other parameters, except for lysine intake and efficiency of lysine for gain, which increased and decreased, respectively, linearly (P<0.05). It is recommended that diets for juvenile Nile tilapia should contain 1.84% digestible lysine for maximum weight gain.(AU)

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Ruminant infection by Mycobacterium avium subsp. paratuberculosis (MAP) causes a granulomatous inflammatory response in the intestine and associated lymph nodes. Differences either in the affected organs or in the inflammatory infiltrate were observed between species and individuals. Such differences are usually attributed to variations in host immune responses or to inconsistent effects among different MAP strains. To evaluate if different MAP strains induce different immuno-pathological responses in lambs, 28 one-month-old individuals were divided into six groups and inoculated with different MAP strains. Groups 1 and 2 were inoculated with two bovine strains isolated in Argentina that showed different genetic patterns after BstEII-IS900-RFLP (hereafter strains E and A respectively). Group 3 was inoculated with a bovine strain isolated in Spain obtained after a previous step of culture (patterns C1). Group 4 was inoculated with a homogenate of intestinal mucosa of a clinical case affected by the same bovine strain as that of group 3. Group 5 was inoculated with an ovine strain that was directly purified from the intestinal mucosa of a clinical case, and group 6 was kept as control (i.e. no inoculation). Peripheral immune responses were assessed until 150 days post-infection (dpi), when lambs were humanely killed. Pathological studies were performed in tissues from the intestine and lymph nodes. Lesion types and inflammatory infiltrates were examined as indicators of pathogenicity. All the lambs infected with bovine MAP strains showed a common lesion pattern regardless of the strain type. Such pattern was characterized by focal lesions mainly in the mesenteric lymph nodes, the presence of fibrous tissue, and, occasionally, necrosis in the granulomas as well as the presence of numerous giant cells. Differences in lesion severity were observed among groups: lambs from groups 1 and 2 had the highest number of granulomas and the largest lymph node area affected. Lesions in animals from group 5 (infected with an ovine strain) were more severe and occurred mostly in the intestinal lymphoid tissue; necrosis, fibrosis or giant cells were never detected in this group. These results indicate that the MAP strain type induces different pathological responses in lambs.

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