Hind limb ischemia in type 1 diabetic mice as useful tool to evaluate the neovascularization of tissue engineering constructs

Hind-limb ischemia has been used in type 1 diabetic mice to evaluate treatments for peripheral arterial disease or mechanisms of vascular impairment in diabetes [1]. Vascular deficiency is not only a pathophysiological condition, but also an obvious circumstance in tissue regeneration and in tissue engineering and regenerative medicine (TERM) strategies. We performed a pilot experiment of hind-limb ischemia in streptozotocin(STZ)-induced type 1 diabetic mice to hypothesise whether diabetes influences neovascularization induced by biomaterials. The dependent variables included blood flow and markers of arteriogenesis and angiogenesis. Type 1 diabetes was induced in 8-week-old C57BL/6 mice by an i.p. injection of STZ (50 mg/kg daily for 5 days). Hind-limb ischemia was created under deep anaesthesia and the left femoral artery and vein were isolated, ligated, and excised. The contralateral hind limb served as an internal control within each mouse. Non-diabetic ischaemic mice were used as experiment controls. At the hind-limb ischemia surgical procedure, different types of biomaterials were placed in the blood vessels gap. Blood flow was estimated by Laser Doppler perfusion imager, right after surgery and then weekly. After 28 days of implantation, surrounding muscle was excised and evaluated by histological analysis for arteriogenesis and angiogenesis. The results showed that implanted biomaterials were promote faster restoration of blood flow in the ischemic limbs and improved neovascularization in the diabetic mice. Therefore, we herein demonstrate that the combined model of hind-limb ischemia in type 1 diabetes mice is suitable to evaluate the neovascularization potential of biomaterials and eventually tissue engineering constructs.  

Reflow soldering in an oxidant atmosphere

Dissertação de mestrado integrado em Materials Engineering

Biomaterials for cartilage tissue engineering under mechanical stimulus

Tese de Doutoramento em Ciências (Especialidade de Física)

Development of advanced cell/tissue culture systems, based on enhanced polymeric scaffolds and sophisticated bioreactors, for tissue engineering applications

Programa Doutoral em Engenharia Biomédica

A bio-inspired computational model for motion detection

Tese de Doutoramento (Programa Doutoral em Engenharia Biomédica)

Eating habits and psychopathology: translation, adaptation, reliability of the Nutrition Behavior Inventory to Portuguese and relation to psychopathology

Objective: The Nutrition-Behavior Inventory (NBI) is a self-administered instrument that allows eating habits to be correlated with psychopathological symptoms. The objective was to translate and adapt the NBI to Portuguese, and test the Portuguese NBI’s reliability. The second aim was to verify its sensitivity for identification of risk factors in terms of behavior/eating habits in children and adolescents. Methods: The NBI was translated, adapted, and back-translated. The Portuguese version of the NBI was then applied (N = 96; 9-12 years). In order to verify the internal consistency, Cronbach’s alpha was used. The psychopathological indicators of the participants were accessed using the Child Behavior Checklist (CBCL). The mean CBCL scores were analyzed in relation to the NBI data (cutoff point: ≥ 30 with indicators, and < 30 without). Results: Internal consistency was high (Cronbach’s alpha = 0.89) for the NBI. The CBCL scores correlated significantly with NBI (> 30) on the following: anxiety and depression (p = 0.041), social difficulties (p = 0.028), attention problems (p = 0.001), aggressive behavior (p = 0.015); ADHD (p < 0.001), and conduct problems (p = 0.032). Conclusion: The present results indicate that the NBI is a reliable instrument. The NBI can be useful for evaluating psychopathological symptoms related to the eating habits and behaviors of children and adolescents.

Personal and Social Performance (PSP) scale for patients with schizophrenia: translation to Portuguese, cross-cultural adaptation and interrater reliability

INTRODUCTION: Schizophrenia is a chronic mental disorder associated with impairment in social functioning. The most widely used scale to measure social functioning is the GAF (Global Assessment of Functioning), but it has the disadvantage of measuring at the same time symptoms and functioning, as described in its anchors. OBJECTIVES:Translation and cultural adaptation of the PSP, proposing a final version in Portuguese for use in Brazil. METHODS: We performed five steps: 1) translation; 2) back translation; 3) formal assessment of semantic equivalence; 4) debriefing; 5) analysis by experts. Interrater reliability (Intraclass correlation, ICC) between two raters was also measured. RESULTS: The final version was applied by two independent investigators in 18 adults with schizophrenia (DSM-IV-TR). The interrater reliability (ICC) was 0.812 (p < 0.001). CONCLUSION: The translation and adaptation of the PSP had an adequate level of semantic equivalence between the Portuguese version and the original English version. There were no difficulties related to understanding the content expressed in the translated texts and terms. Its application was easy and it showed a good interrater reliability. The PSP is a valid instrument for the measurement of personal and social functioning in schizophrenia.

A questionnaire to evaluate the impact of chronic diseases: validated translation and Illness Effects Questionnaire (IEQ) reliability study

INTRODUCTION: Patients' perception about their health condition, mainly involving chronic diseases, has been investigated in many studies and it has been associated to depression, compliance with the treatment, quality of life and prognosis. The Illness Effects Questionnaire (IEQ) is a tool which makes the standardized evaluation of patients' perception about their illness possible, so that it is brief and accessible to the different clinical settings. This work aims to begin the transcultural adaptation of the IEQ to Brazil through the validated translation and the reliability study. METHODS: The back-translation method and the test-retest reliability study were used in a sample of 30 adult patients under chronic hemodialysis. The reliability indexes were estimated using the Pearson, Spearman, Weighted Kappa and Cronbach's alpha coefficients. RESULTS: The semantic equivalence was reached through the validated translation. In this study, the reliability indexes obtained were respectively: 0.85 and 0.75 (p < 0.001); 0.68 and 0.92 (p < 0.0001). DISCUSSION: The reliability indexes obtained attest to the stability of responses in both evaluations. Additional procedures are necessary for the transcultural adaptation of the IEQ to be complete. CONCLUSION: The results indicate the translation validity and the reliability of the Brazilian version of the IEQ for the sample studied.

Metabolic engineering with multi-objective optimization of kinetic models

Kinetic models have a great potential for metabolic engineering applications. They can be used for testing which genetic and regulatory modifications can increase the production of metabolites of interest, while simultaneously monitoring other key functions of the host organism. This work presents a methodology for increasing productivity in biotechnological processes exploiting dynamic models. It uses multi-objective dynamic optimization to identify the combination of targets (enzymatic modifications) and the degree of up- or down-regulation that must be performed in order to optimize a set of pre-defined performance metrics subject to process constraints. The capabilities of the approach are demonstrated on a realistic and computationally challenging application: a large-scale metabolic model of Chinese Hamster Ovary cells (CHO), which are used for antibody production in a fed-batch process. The proposed methodology manages to provide a sustained and robust growth in CHO cells, increasing productivity while simultaneously increasing biomass production, product titer, and keeping the concentrations of lactate and ammonia at low values. The approach presented here can be used for optimizing metabolic models by finding the best combination of targets and their optimal level of up/down-regulation. Furthermore, it can accommodate additional trade-offs and constraints with great flexibility.

Reliability and convergent validity of the Childhood Anxiety Sensitivity Index in children and adolescents

OBJECTIVE: The purpose of this study was to examine the reliability and the convergent validity of the Children Anxiety Sensitivity Index (CASI) with DSM-IV anxiety disorder symptoms, by comparison with the Screen for Child Anxiety Related Emotional Disorders (SCARED), in a community sample of Brazilian children and adolescents. METHODS: Children and adolescents from five schools were selected from a larger study that aimed to assess different aspects of childhood anxiety disorders. All participants completed the CASI and the SCARED. RESULTS: This study supported the reliability of the CASI total score. Girls reported higher total anxiety sensitivity scores than boys and there were no differences in total anxiety sensitivity scores between children and adolescents. This study showed moderate to high correlations between the CASI scores with SCARED scores, all correlations coefficients being positive and significant. CONCLUSIONS: Our findings demonstrate an appropriate reliability and evidence of convergent validity in the CASI in a sample of Brazilian children and adolescents.

Diagnóstico e ensaio de carga de asnas tradicionais de madeira

Dissertação de mestrado Integrado em Engenharia Civil

Chondrogenic potential of injectable κ-carrageenan hydrogel with encapsulated adipose stem cells for cartilage tissue-engineering applications

Due to the limited self-repair capacity of cartilage, regenerative medicine therapies for the treatment of cartilage defects must use a significant amount of cells, preferably applied using a hydrogel system that can promise their delivery and functionality at the specific site. This paper discusses the potential use of k-carrageenan hydrogels for the delivery of stem cells obt ained from adipose tissue in the treatment of cartilage tissue defects. The developed hydrogels were produced by an ionotropic gelation met hod and human adipose stem cells (hASCs) were encapsulated in 1.5% w/v k-carrageenan solution at a cell density of 5  10 6 cells/ml. The results from the analysis of the cell-encapsulating hydrogels, cultured for up to 21 days, indicated that k-carrageenan hydrogels support the viability, proliferation and chondrogenic differentiation of hASCs. Additionally, the mec hanical analysis demonstrated an increase in stiffness and viscoelastic properties of k-carrageenan gels with their encapsulated cells with increasing time in culture with chondrogenic medium. These results allowed the conclusion that k-carrageenan exhibits properties t hat enable the in vitro functionality of encapsulated hASCs and thus may provide the basis for new successful approaches for the treatment of cartilage defects.

Bioactive ceramics for tissue engineering and regenerative medicine derived from marine sponges

Publicado em "Journal of tissue engineering and regenerative medicine". Vol. 8, suppl. s1 (2014)

Marine Collagen/Apatite scaffolds envisaging tissue engineering applications

Despite the vast investigation and the large amount of products already available in the market to treat the different bone defects there is still a growing need to develop more advanced and complex therapeutic strategies. In this context, a mixture of Marine Hydroxyapatite-Fluorapatite:Collagen (HA-FP:ASC) seems to be a promising solution to overcome these bone defects, specifically, dental defects. HA-FP particles (20–63 μm) were obtained through pyrolysis (950°C, 12 h) of shark teeth (Isurus oxyrinchus, P. glauca), and Type I collagen was isolated from Prionace glauca skin as previously described (1). After the steps of purification, collagen was solubilized in 0.5 M acetic acid and HA-FP added producing three different formulations: were produced, 30:70, 50:50 and 70:30 of HA-FP:ASC, respectively. EDC/NHS and HMDI binding agents were used to stabilize the produced scaffolds. Mechanical properties were evaluated by compression tests. SEM analysis allowed observing the mineral deposition, after immersion in simulated body fluid and also permitted to evaluate how homogenous was the distribution of HA-FP in the different scaffold formulations, also confirmed by μ-CT assay. It was readily visible by Cytotoxicity and life/dead CLSM assays that cells were able to adhere and proliferate in the produced scaffolds. Scaffolds crosslinked with EDC/NHS showed lower cytotoxicity, being the ones chosen for further cellular evaluation.

Introducing biomimetic approaches to materials development and product design for engineering students

In this paper, we present a new course entitled “Biomimicry: from life to nanotechnological innovations” at the Mines Nancy Engineering School, Nancy, France, and explain how we developed a specific curriculum covering biomimicry. We discuss strategies that can be followed by teachers to explain selected contents in the multi-disciplinary field of biomimicry and/or bioinspiration to undergraduate students and how practical classroom activities can be conducted as individual or team work. We hope that sharing our experience will help teachers and senior researchers disseminate useful concepts and real examples of biomimetic principles and tools for the development of new materials, new/improved design and fabrication strategies, and innovation methodologies.