A new approach for initial callus growth during fracture healing in long bones

The incidence of bone fracture has become a major clinical problem on a worldwide scale. In the past two decades there has been an increase in the use of computational tools to analyse the bone fracture problem. In several works, various study cases have been analysed to compare human and animal bone fracture healing. Unfortunately, there are not many publications about computational advances in this field and the existing approaches to the problem are usually similar. In this context, the objective of this work is the application of a diffusion problem in the model of the bone fragments resulting from fracture, working together with a mesh-growing algorithm that allows free growth of the callus depending on the established conditions, without a pre-meshed domain. The diffusion problem concerns the different biological magnitudes controlling the callus growth, among which Mesenchymal Stem Cells and chondrocytes concentrations were chosen, together with Tumour Necrosis Factor α and Bone Morphogenetic Protein as the factors influencing the velocity in the callus formation. A Finite Element approach was used to solve the corresponding diffusion problems, obtaining the concentration values along the entire domain and allowing detecting the zones in which biological magnitudes reach the necessary thresholds for callus growth. The callus growth is guided by a geometrical algorithm which performs an additional mesh generation process (self-added mesh) at each step of the iterative procedure until complete callus formation. The proposed approach was applied to different types of diaphyseal femoral fractures treated by means of intramedullary nailing. Axisymmetric models based on triangular quadratic elements were used, obtaining results in good agreement with clinical evidence of these kinds of fractures. The algorithm proposed has the advantage of a natural callus growth, without the existence of a previous mesh that may affect the conditions and direction of growth. The approach is intended for the initial phase of callus growth. Future work will address the implementation of the corresponding formulations for tissue transformation and bone remodelling in order to achieve complete fracture healing

Study of urgent visits to commercial rabbit farms in Spain and Portugal during 1997-2007

[EN] This is a report on work carried out on 4307 visits to 868 commercial farms with domestic rabbits in Spain and Portugal from January 1997 to December 2007. Of the total visits, 2237 (52%) were emergencies on 660 farms. The median size of the farms ranged between 450 does in 1997 and 750 in 2007. This retrospective study measures the clinical disease occurrence using the Monthly Risk of urgent visits (MR), i.e. the percentage of visits made as a result of each clinical disease in comparison with the total number of urgent visits made each month. The main reasons for the emergencies were mucoid enteropathy (similar to Epizootic Rabbit Enteropathy), with a MR: 25.0%, enteritis-diarrhoea (24.1%), myxomatosis, (11.1%), reproductive troubles (8.6%), respiratory diseases (7.2%) and staphylococcosis (4.2%). Fifty-four percent of the urgent visits were due to diseases of the digestive system. Mucoid enteropathy was still one of the main diseases faced by the commercial rabbit industry during the study period. No significant yearly or monthly variations were observed in the analysis of the MR. A seasonal effect was only found in respiratory diseases during the summer (MR: 11.06±0.01) and myxomatosis in autumn (MR: 14.60±0.02), in comparison with spring (MR: 7.44±0.02). It is therefore concluded that farms should be permanently protected as they might be affected by any of these diseases at any time during the year.Rosell, J.; Fuente, LDL.; Badiola, J.; Fernández De Luco, D.; Casal, J.; Saco, M. (2009). Study of urgent visits to commercial rabbit farms in Spain and Portugal during 1997-2007. World Rabbit Science. 17(3):127-136. doi:10.4995/wrs.2009.65212713617

UV-C irradiation is able to inactivate pathogens found in commercially collected porcine plasma as demonstrated by swine bioassay

Liquid porcine plasma is an animal origin raw material for the manufacturing process of spray-dried porcine plasma that is used in pig nutrition worldwide. In previous studies we found that the application of ultraviolet light C (UV-C) in liquid plasma that was inoculated with a variety of bacteria or viruses of importance in the swine industry can be considered as redundant safety steps because in general achieve around 4 logs reduction for most of these pathogens. However, the final validation of the UV-C light as safety feature should be conducted with commercial liquid plasma and using the pig bioassay model. As a first objective, the potential infectivity of a raw liquid plasma product collected from an abattoir was tested by means of a swine bioassay. We used Porcine circovirus 2 (PCV-2), a ubiquitous virus that has been systematically detected by PCR in porcine plasma at abattoirs as selection criteria for commercial liquid plasma lot. As a second aim of the study, the effects of different doses of UV-C irradiation on the selected raw liquid plasma were assayed in the animal bioassay. Moreover, other swine infecting agents, including Porcine reproductive and respiratory syndrome virus (PRRSV), were also determined in the original plasma and monitored in the inoculated animals. Pigs negative for PCV-2 and PRRSV genome and antibodies were allotted to one of five groups (6 to 8 pigs/ group) and injected intra-peritoneally with 10 mL of their assigned inoculum at 50 d of age. Negative control pigs (group 1) were injected with PBS. Positive control pigs (group 5) were injected with a PCV-2 inoculum. Groups 2, 3 and 4 were injected with liquid porcine plasma that had been subjected to 0 (raw plasma), 3000 or 9000 J/L UV-C irradiation, respectively. Group 2 pigs (0 J/L UV-C) got infection by PRRSV but no PCV-2 infection or seroconversion. However, one pig from group 2 seroconverted to Rotavirus A (RVA) and Hepatitis E virus (HEV) and three group 2 pigs seroconverted to Porcine parvovirus (PPV). Groups 1, 3 and 4 pigs showed no evidence of infection or seroconversion associated with the tested viruses or any other pathogens found in the liquid plasma before UV-C irradiation. Group 5 pigs developed PCV-2 infectivity as expected. UV-C irradiation of liquid plasma at 3000 and 9000 J/L was effective in preventing PRRSV and other pathogens transmission. Moreover, raw liquid plasma was non-infectious for PCV-2 in naïve pigs.info:eu-repo/semantics/publishedVersio

Interpolating between low and high energy QCD via a 5D Yang-Mills model

We describe the Goldstone bosons of massless QCD together with an infinite number of spin-1 mesons. The field content of the model is SU(Nf)xSU(Nf) Yang-Mills in a compact extra-dimension. Electroweak interactions reside on one brane. Breaking of chiral symmetry occurs due to the boundary conditions on the other brane, away from our world, and is therefore spontaneous. Our implementation of the holographic recipe maintains chiral symmetry explicit throughout. For intermediate energies, we extract resonance couplings. These satisfy sum rules due to the 5D nature of the model. These sum rules imply, when taking the high energy limit, that perturbative QCD constraints are satisfied. We also illustrate how the 5D model implies a definite prescription for handling infinite sums over 4D resonances. Taking the low energy limit, we recover the chiral expansion and the corresponding non-local order parameters. All local order parameters are introduced separately.Comment: Corresponds to published version, with some typos correcte

¿Existe un intervalo de tiempo de isquemia fría seguro para el injerto renal?

Objective: It is aimed to characterize the true relationship of the cold ischemia time (CIT) with graft survival and with the principal post-transplantation events.aterial and methods: We analyzed 378 kidney transplants, studying the relationship of the CIT with graft survival using a univariate analysis according to the COX model and seeking the optimum cutoff according to the Kaplan-Meier method and log-rank test. The relationship between CIT and the principal events of the post-transplant was studied using the binary logistic regression. Results: The mean follow-up of all the group was 77.8 months (± 51 SD) and the mean CIT was 14.8 hours (± 5.1 SD). The univariate analysis revealed that the CIT was not related with the graft survival as a continuous variable (OR = 1.04; 95% CI: 0.9-1.08; p > 0.05). On establishing the cutoff at 18 hours, we found differences in the actuarial survival. Survival at 5 years was 91% with CIT 18 h. Each hour of cold ischemia increased risk of delay in the graft function by 10% (OR = 1.1; 95% CI: 1.05-1.15; p < 0.001) and also conditioned a greater incidence of acute rejection (41.5% vs. 55.3%; p = 0.02) and less time to the first rejection episode (72.6 days ± 137 vs. 272.2 days ± 614.8; p = 0.023) after 18 hours. The CIT did not seem to be related (p < 0.05) with the rest of the post-transplantation events, such as surgical complications or hospital admissions. Conclusions: In our experience, cold ischemia under 18 hours does not seem to negatively affect graft survival

Edad del donante y su influencia en la supervivencia del injerto

INTRODUCTION: In 2007 in Spain 43% of donors were older than 60 years. This produces a worse graft quality and probably a worse survival. OBJECTIVE: Our objective is to analyze the influence of donor age on graft survival. MATERIAL AND METHODS: We analyze retrospectively 216 renal consecutive transplants realized between 2000 and 2008. A univaried and multivaried study (Cox regression) was performed and Kaplan-Meyer test with log rank for graft survival. RESULTS: Follow-up mean of 40 months (+/-33,4 SD). The univaried analysis of graft survival showed that donor age had a significative influence on graft survival. (OR=1,03; 95% CI 1,01-1,05) (p: 0,009). Studying the relation between donor and recipient age we find an inverse correlation (Pearson's Correlation: 0,55. p<0,0001), but there are significative differences after the adjustment for recipient age. (OR: 1,02; 95% CI 1,01-1,04) (p: 0,04). Optimal cut-point value determined by the ROC analysis was 60 years. The graft survival of donors over 60 years is 79% (95% CI; 74-84%) and 71% (95% CI; 65-77%) at 3 and 5 years in contrast with 94% (95% CI; 94-96%) and 90% (95% CI; 88-92 in donors under 60. (p: 0,002). The multivaried study of the influential factors on graft survival reveals that donor age dichotomized in older or younger than 60, the presence of a surgical immediate reintervention and a delayed graft function were independent influence factors. CONCLUSIONS: Donor age over 60 years has a negative and independent prognostic influence on graft survival