TNF receptors regulate vascular homeostasis in zebrafish through a caspase-8, caspase-2 and P53 apoptotic program that bypasses caspase-3

Although it is known that tumor necrosis factor receptor (TNFR) signaling plays a crucial role in vascular integrity and homeostasis, the contribution of each receptor to these processes and the signaling pathway involved are still largely unknown. Here, we show that targeted gene knockdown of TNFRSF1B in zebrafish embryos results in the induction of a caspase-8, caspase-2 and P53-dependent apoptotic program in endothelial cells that bypasses caspase-3. Furthermore, the simultaneous depletion of TNFRSF1A or the activation of NF-κB rescue endothelial cell apoptosis, indicating that a signaling balance between both TNFRs is required for endothelial cell integrity. In endothelial cells, TNFRSF1A signals apoptosis through caspase-8, whereas TNFRSF1B signals survival via NF-κB. Similarly, TNFα promotes the apoptosis of human endothelial cells through TNFRSF1A and triggers caspase-2 and P53 activation. We have identified an evolutionarily conserved apoptotic pathway involved in vascular homeostasis that provides new therapeutic targets for the control of inflammation- and tumor-driven angiogenesis.

Development of a Novel Rabies Simulation Model for Application in a Non-endemic Environment.

Domestic dog rabies is an endemic disease in large parts of the developing world and also epidemic in previously free regions. For example, it continues to spread in eastern Indonesia and currently threatens adjacent rabies-free regions with high densities of free-roaming dogs, including remote northern Australia. Mathematical and simulation disease models are useful tools to provide insights on the most effective control strategies and to inform policy decisions. Existing rabies models typically focus on long-term control programs in endemic countries. However, simulation models describing the dog rabies incursion scenario in regions where rabies is still exotic are lacking. We here describe such a stochastic, spatially explicit rabies simulation model that is based on individual dog information collected in two remote regions in northern Australia. Illustrative simulations produced plausible results with epidemic characteristics expected for rabies outbreaks in disease free regions (mean R0 1.7, epidemic peak 97 days post-incursion, vaccination as the most effective response strategy). Systematic sensitivity analysis identified that model outcomes were most sensitive to seven of the 30 model parameters tested. This model is suitable for exploring rabies spread and control before an incursion in populations of largely free-roaming dogs that live close together with their owners. It can be used for ad-hoc contingency or response planning prior to and shortly after incursion of dog rabies in previously free regions. One challenge that remains is model parameterisation, particularly how dogs' roaming and contacts and biting behaviours change following a rabies incursion in a previously rabies free population.

Cell Competition During Growth and Regeneration

Tissue growth and regeneration are autonomous, stem-cell-mediated processes in which stem cells within the organ self-renew and differentiate to create new cells, leading to new tissue. The processes of growth and regeneration require communication and interplay between neighboring cells. In particular, cell competition, which is a process in which viable cells are actively eliminated by more competitive cells, has been increasingly implicated to play an important role. Here, we discuss the existing literature regarding the current landscape of cell competition, including classical pathways and models, fitness fingerprint mechanisms, and immune system mechanisms of cell competition. We further discuss the clinical relevance of cell competition in the physiological processes of tissue growth and regeneration, highlighting studies in clinically important disease models, including oncological, neurological, and cardiovascular diseases.

Use of echocardiography reveals reestablishment of ventricular pumping efficiency and partial ventricular wall motion recovery upon ventricular cryoinjury in the zebrafish

AIMS While zebrafish embryos are amenable to in vivo imaging, allowing the study of morphogenetic processes during development, intravital imaging of adults is hampered by their small size and loss of transparency. The use of adult zebrafish as a vertebrate model of cardiac disease and regeneration is increasing at high speed. It is therefore of great importance to establish appropriate and robust methods to measure cardiac function parameters. METHODS AND RESULTS Here we describe the use of 2D-echocardiography to study the fractional volume shortening and segmental wall motion of the ventricle. Our data show that 2D-echocardiography can be used to evaluate cardiac injury and also to study recovery of cardiac function. Interestingly, our results show that while global systolic function recovered following cardiac cryoinjury, ventricular wall motion was only partially restored. CONCLUSION Cryoinjury leads to long-lasting impairment of cardiac contraction, partially mimicking the consequences of myocardial infarction in humans. Functional assessment of heart regeneration by echocardiography allows a deeper understanding of the mechanisms of cardiac regeneration and has the advantage of being easily transferable to other cardiovascular zebrafish disease models.

5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats

Funding The research reported in this publication was supported by the Biotechnology and Biological Sciences Research Council (E007821/1 to M.S.M-G, R.L.C and E00797X/1; BB/K001418 /1 to L.K.H), the British Heart Foundation (FS/09/029/27902 to S.E.O.), the UK Medical Research Council Metabolic Diseases Unit (MC_UU_12012/4 to S.E.O and MC_UU_12012/1 to G.S.H.Y), the Wellcome Trust (WT081713 and WT098012 to L.K.H), the European Union (FP7-HEALTH-266408 Full4Health to G.S.H.Y) and the Helmholtz Alliance ICEMED to G.S.H.Y.

Sobrecarga e restrição de cloreto de sódio durante a gestação: repercussão sobre a estrutura cardíaca e renal no neonato

Introdução: Diversos estudos indicaram consequências de alterações na nutrição materna durante a gestação sobre a saúde da prole adulta, tais como: hipertensão, doenças cardiovasculares, resistência à insulina, diabete melito e doença renal. No entanto, a literatura é pobre em avaliações decorrentes de modificações nutricionais maternas sobre a prole logo após o nascimento. Métodos: Ratas Wistar durante o período gestacional foram alimentadas com dieta hipossódica (HO - 0,15% de NaCl), normossódica (NR - 1,3% de NaCl) ou hipersódica (HR - 8% de Na Cl). Após o nascimento, nas primeiras vinte e quatro horas foram coletados rins e coração dos neonatos machos e fêmeas (n=6- 8/grupo) para verificar as possíveis alterações na estrutura cardíaca e renal pelo método de estereologia. Também foi avaliada a expressão proteica e gênica dos componentes do sistema renina angiotensina (SRA) no coração e rins através do método ELISA indireto e RT-qPCR. Resultados: O peso ao nascimento foi menor em machos e fêmeas da prole de mães alimentadas com dieta hipossódica durante a gestação quando comparado NR e HR. Não houve diferença no volume renal, volume de seus compartimentos (córtex, medula e pelve) e número de glomérulos entre os grupos experimentais (HO, NR e HR). No entanto, o número de glomérulos foi maior em fêmeas comparado aos machos nos três grupos experimentais. O diâmetro transverso do núcleo dos cardiomiócitos no ventrículo esquerdo e no ventrículo direito de machos da prole HR foi maior do que na prole NR. A expressão proteica do receptor AT1 no rim de machos da prole foi menor no grupo HO do que no grupo NR e HR. A expressão proteica do receptor AT2 também foi menor em machos do grupo HO do que no grupo NR. Não houve diferença entre os grupos na expressão proteica dos receptores AT1 e AT2 no rim das fêmeas. Conclusão: O presente estudo detectou alterações na estrutura cardíaca de neonatos machos, mas não em neonatos fêmeas decorrentes de sobrecarga de sal durante a gravidez. As alterações observadas na expressão dos receptores AT1 e AT2 no rim de neonatos machos podem ser responsáveis por alterações na função renal

Regeneração hepática em animais jovens com estenose da veia porta ou ligadura da artéria hepática: estudos histológicos, moleculares e avaliação dos efeitos da insulina e do tacrolimus como agentes regenerativos

INTRODUÇÃO: O transplante hepático é o único tratamento efetivo para uma variedade de doenças hepáticas irreversíveis. No entanto, o número limitado de doadores pediátricos leva ao uso de enxertos hepáticos de doadores adultos, com necessidade de anastomoses vasculares mais complexas. Essas anastomoses tornam-se complicadas pela diferença no calibre dos vasos entre o doador e o receptor, resultando em alterações do fluxo sanguíneo, estenose da anastomose venosa ou arterial e trombose. Os efeitos para regeneração hepática decorrentes da privação do fluxo sanguíneo pela veia porta ou pela artéria hepática não estão completamente elucidados. Experimentalmente, quando um lobo do fígado não recebe o fluxo venoso portal, é observada atrofia deste segmento e hipertrofia do restante do órgão perfundido. Embora existam vários modelos experimentais para estudo da regeneração hepática, poucos são focados em animais em crescimento. Além disso, os efeitos regenerativos de drogas como o tacrolimus e a insulina precisam ser pesquisados, com o objetivo de encontrar um tratamento ideal para a insuficiência hepática ou um método de estimular a regeneração do fígado após ressecções ou transplantes parciais. O objetivo do presente estudo é descrever modelos de regeneração hepática em ratos em crescimento com: 1) ausência de fluxo hepático arterial e 2) redução do fluxo portal. Adicionalmente, o estudo avalia o efeito pró-regenerativo do tacrolimus e da insulina nesses modelos descritos. MÉTODOS: cento e vinte ratos (entre 50 e 100g de peso) foram divididos em 6 grupos, de acordo com o tipo de intervenção cirúrgica: Grupo 1, incisão abdominal sem intervenção hepática; Grupo 2, hepatectomia a 70%; Grupo 3, hepatectomia a 70% + estenose de veia porta; Grupo 4, hepatectomia a 70% + ligadura da artéria hepática; Grupo 5, hepatectomia a 70% + estenose de veia porta + insulina; Grupo 6, hepatectomia a 70% + estenose de veia porta + tacrolimus. Os animais dos grupos 1 ao 4 foram subdivididos em 5 subgrupos de acordo com o momento da morte: 1, 2, 3, 5 e 10 dias após a intervenção cirúrgica. Os animais dos grupos 5 e 6 foram subdividos em 2 subgrupos de acordo com o momento da morte: 2 e 10 dias após a intervenção cirúrgica. Os lobos hepáticos remanescentes foram submetidos à análise histomorfométrica, imuno-histoquímica e molecular. RESULTADOS: Verificou-se que no grupo com hepatectomia a 70% houve recuperação do peso do fígado no terceiro dia com aumento da atividade mitótica, enquanto que no grupo com estenose portal não se observou esse fenômeno (p < 0,001). A insulina e o tacrolimus promoveram aumento do peso do fígado e do índice mitótico. A atividade mitótica foi considerada aumentada nos animais dos grupos hepatectomia, hepatectomia + ligadura da artéria, insulina e tacrolimus; e esse parâmetro estava reduzido no grupo submetido à hepatectomia + estenose portal (p < 0,001). A expressão de interleucina 6 estava presente em todos os animais, sendo significativamente maior nos grupos hepatectomia, hepatectomia + ligadura da artéria e significativamente menor no grupo hepatectomia + estenose portal. Entretanto, a administração de tacrolimus ou insulina recuperou os níveis teciduais de interleucina 6 no grupo com estenose portal. CONCLUSÕES: No presente estudo foi padronizado um modelo simples e facilmente reprodutível para estudar a regeneração hepática em ratos em crescimento com redução do fluxo arterial ou venoso para o fígado. Foi demonstrado que a administração de insulina ou tacrolimus é capaz de reverter os efeitos deletérios da estenose portal na regeneração hepática. A obstrução do fluxo arterial não afetou a capacidade regenerativa hepática

Minutes of meeting, January 6, 1969.

Includes subcommittee reports and recommendations to the Committee.

Using identity-by-de scent information in affected sib pairs to increase the efficiency of genetic association studies

T he aim of this study was to determine whether identity-by-descent (IBD) information for affected sib pairs (ASPs) can be used to select a sample of cases for a genetic case-control study which will provide more power for detecting association with loci in a known linkage region. By modeling the expected frequency of the disease allele in ASPs showing IBD sharing of 0, 1, or 2 alleles, and considering additive, recessive, and dominant disease models, we show that cases selected from IBD 2 families are best for this purpose, followed by those selected from IBD 1 families; least useful are cases selected from IBD 0 families.

Blockade of the C5a receptor fails to protect against experimental autoimmune encephalomyelitis in rats

Complement activation contributes to inflammation and tissue damage in human demyelinating diseases and in rodent models of demyelination. Inhibitors of complement activation ameliorate disease in the rat model antibody-dependent experimental autoimmune encephalomyelitis and rats unable to generate the membrane attack complex of complement develop inflammation without demyelination. The role of the highly active chemotactic and anaphylactic complement-derived peptide C5a in driving inflammation and pathology in rodent models of demyelination has been little explored. Here we have used a small molecule C5a receptor antagonist, AcF-[OPdChaWR], to examine the effects of C5a receptor blockade in rat models of brain inflammation and demyelination. C5a receptor antagonist therapy completely blocked neutrophil response to C5a in vivo but had no effect on clinical disease or resultant pathology in either inflammatory or demyelinating rat models. We conclude that C5a is not required for disease induction or perpetuation in these strongly complement-dependent disease models.

Proteins accessible to immune surveillance show significant T-cell epitope depletion:implications for vaccine design

T cell activation is the final step in a complex pathway through which pathogen-derived peptide fragments can elicit an immune response. For it to occur, peptides must form stable complexes with Major Histocompatibility Complex (MHC) molecules and be presented on the cell surface. Computational predictors of MHC binding are often used within in silico vaccine design pathways. We have previously shown that, paradoxically, most bacterial proteins known experimentally to elicit an immune response in disease models are depleted in peptides predicted to bind to human MHC alleles. The results presented here, derived using software proven through benchmarking to be the most accurate currently available, show that vaccine antigens contain fewer predicted MHC-binding peptides than control bacterial proteins from almost all subcellular locations with the exception of cell wall and some cytoplasmic proteins. This effect is too large to be explained from the undoubted lack of precision of the software or from the amino acid composition of the antigens. Instead, we propose that pathogens have evolved under the influence of the host immune system so that surface proteins are depleted in potential MHC-binding peptides, and suggest that identification of a protein likely to contain a single immuno-dominant epitope is likely to be a productive strategy for vaccine design.

The role of acute ambient hypoxia in the regulation of myostatin

When exposed to chronic hypoxia by pathophysiological or environmental causes humans show muscle atrophy, challenging homeostasis and increasing mortality rate. Chronic hypoxia also presents with elevated myostatin peptide, a negative regulator of muscle size. This work induced acute hypoxia in healthy individuals; hypothesizing hypoxia would increase myostatin expression in both muscle and plasma in a concentration- and time-dependent manner. Hypoxia (1 % O2) reduced C2C12 myoblast migration and myotube size in vitro. Myotube atrophy was time-dependent, longer exposures showed greater atrophy. Intracellular myostatin peptide was decreased at every time point measured. Myostatin and downstream signalling pathways in muscle showed a high degree of percentage similarity between mouse and human, when amino acid sequences were directly compared. Healthy males (N = 8) were exposed to 20.9 % O2 or 11.9 % O2 for 2 hours. Following hypoxic exposure myostatin peptide was reduced in muscle but not plasma, relative to control conditions. A second cohort (N = 8) was exposed to 12.5 % O2 for 10 hours. Plasma myostatin was decreased following hypoxia, muscle myostatin trended towards increasing. A third cohort (N = 9; n = 8 lowlander, n = 1 Sherpa) was exposed to 10.7 % or 12.3 % O2 for 2 hours. Plasma myostatin was reduced at both concentrations with no difference between concentrations noted. In response to chronic hypoxia, individuals lose muscle mass. Counter to the hypothesis of an increase in myostatin in both muscle and plasma, here a consistent decrease in plasma myostatin following acute hypoxia is seen. Muscle myostatin shows a variable response, with decreasing intracellular expression seen following a 2 hour hypoxic exposure, and trends towards an increase following 10 hours of hypoxia. Decreases in plasma and muscle myostatin may represent myostatin’s movement towards peripheral compartments in these acute timeframes. Hypoxia alone is capable of altering myostatin in healthy individuals; the effects of hypoxia on myostatin appear to differ between the acute timeframes examined here and chronic exposures in environmental or disease models.

Leptospirosis in northern Tanzania: exploring the role of rodents and ruminant livestock in a neglected public health problem

Leptospirosis is an important but neglected zoonotic disease that is often overlooked in Africa. Although comprehensive data on the incidence of human disease are lacking, robust evidence of infection has been demonstrated in people and animals from all regions of the continent. However, to date, there are few examples of direct epidemiological linkages between human disease and animal infection. In East Africa, awareness of the importance of human leptospirosis as a cause of non-malarial febrile illness is growing. In northern Tanzania, acute leptospirosis has been diagnosed in 9% of patients with severe febrile illness compared to only 2% with malaria. However, little is known about the relative importance of different potential animal hosts as sources of human infection in this area. This project was established to investigate the roles of rodents and ruminant livestock, important hosts of Leptospira in other settings, in the epidemiology of leptospirosis in northern Tanzania. A cross-sectional survey of rodents living in and around human settlements was performed alongside an abattoir survey of ruminant livestock. Unusual patterns of animal infection were detected by real-time PCR detection. Renal Leptospira infection was absent from rodents but was detected in cattle from several geographic areas. Infection was demonstrated for the first time in small ruminants sub-Saharan Africa. Two major Leptospira species and a novel Leptospira genotype were detected in livestock. L. borgpetersenii was seen only in cattle but L. kirschneri infection was detected in multiple livestock species (cattle, sheep and goats), suggesting that at least two distinct patterns of Leptospira infection occur in livestock in northern Tanzania. Analysis of samples from acute leptospirosis in febrile human patients could not detect Leptospira DNA by real-time PCR but identified social and behavioural factors that may limit the utility of acute-phase diagnostic tests in this community. Analysis of serological data revealed considerable overlap between serogroups detected in cattle and human leptospirosis cases. Human disease was most commonly attributed to the serogroups Mini and Australis, which were also predominant reactive serogroups in cattle. Collectively, the results of this study led to the hypothesis that livestock are an important reservoir of Leptospira infection for people in northern Tanzania. These results also challenge our understanding of the relationship between Leptospira and common invasive rodent species, which do not appear to maintain infection in this setting. Livestock Leptospira infection has substantial potential to affect the well-being of people in East Africa, through direct transmission of infection or through indirect effects on food production and economic security. Further research is needed to quantify the impact of livestock leptospirosis in Africa and to develop effective interventions for the control of human and animal disease.

Modelo de gestión para la atención integral de pacientes con enfermedades huérfanas o raras en Colombia

Las enfermedades raras o huérfanas corresponden a aquellas con baja prevalencia en la población, y en varios países tienen una definición distinta de acuerdo con el número de pacientes que afectan en la población. La Organización Mundial de la Salud (OMS), las define como un trastorno que afecta de 650 a 1.000 personas por millón de habitantes, de las que se han identificado alrededor de 7.000. En Colombia su prevalencia es menor de 1 por cada 5.000 personas y comprenden: las enfermedades raras, las ultra-huérfanas y las olvidadas. Los pacientes con este tipo de enfermedades imponen retos a los sistemas sanitarios, pues si bien afectan a un bajo porcentaje de la población, su atención implica una alta carga económica por los costos que involucra su atención, la complejidad en su diagnóstico, tratamiento, seguimiento y rehabilitación. El abordaje de las enfermedades raras requiere un manejo interdisciplinar e intersectorial, lo que implica la organización de cada actor del sistema sanitario para su manejo a través de un modelo que abraque las dinámicas posibles entre ellos y las competencias de cada uno. Por lo anterior, y teniendo en cuenta la necesidad de formular políticas sanitarias específicas para la gestión de estas enfermedades, el presente trabajo presenta una aproximación a la formulación de un modelo de gestión para la atención integral de pacientes con enfermedades raras en Colombia. Esta investigación describe los distintos elementos y características de los modelos de gestión clínica y de las enfermedades raras a través de una revisión de literatura, en la que se incluye la descripción de los distintos actores del Sistema de Salud Colombiano, relacionados con la atención integral de estos pacientes para la documentación de un modelo de gestión integral.

Implementação de algoritmo para avaliação genética de grandes populações de animais de interesse agropecuário.

Apresentamos uma versão inicial da solução em desenvolvimento para estimação dos efeitos desejados através do modelo animal univariado, utilizando duas abordagens distintas para a obtenção do melhor estimador linear não viesado (BLUP) dos parâmetros do modelo.