Circulating extracellular miR-22, miR-155, and miR-365 as candidate biomarkers to assess transport-related stress in turkeys.

MicroRNA (miRNA) have been identified in circulating blood and might have the potential to be used as biomarkers for several pathophysiological conditions. To identify miRNA that are altered following stress events, turkeys (Meleagris gallopavo) were subjected to 2 h of road transportation. The expression levels of five circulating miRNA, namely miR-22, miR-155-5p, miR-181a-3p, miR-204 and miR-365-3p, were detected and assessed by quantitative polymerase chain reaction using TaqMan® probes, as potential biomarkers of stress. The areas under the receiver operating characteristic curves were then used to evaluate the diagnostic performance of miRNA. A panel of three stress-responsive miRNA, miR-22, miR-155 and miR-365 were identified; their expression levels were significantly higher after road transportation and the area under the curve (AUC) were 0.763, 0.71 and 0.704, respectively. Combining the three miRNA a specificity similar to the one found for the three miRNA separately was found. The AUC of the weighted average of the three miRNA was 0.763. This preliminary study suggests that the expression levels of circulating miR-22, miR-155 and miR-365 are increased during transport-related stress and that they may have diagnostic value to discriminate between stressed- and unstressed animals.

Tomografia computadorizada da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato na reparação de falhas ósseas segmentares produzidas em tíbia de coelhos / Computed tomography to evaluate the association of fragmented heterolog cortical bone and methylmethacrylate to repare segmental bone defect produced in tibia of rabbits

Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia de 12 coelhos, seguida de preenchimento desta por matriz óssea mineralizada heteróloga fragmentada conservada em glicerina (98%) e metilmetacrilato autoclavado, bem como avaliação por meio da tomografia computadorizada de feixe cônico (cone beam) aos 30, 60 e 90 dias. Houve incorporação gradativa do implante no leito receptor em relação ao tempo em 100% dos casos, o que mostra ser este biologicamente compatível, ao promover reparação da falha óssea, sem sinais de infecção, migração e/ou rejeição, caracterizando-se, assim, como nova opção de substituto ósseo para preenchimento de falhas ósseas.

A 6mm segmental defect was performed on the metaphyseal region of the tibia of 12 rabbits and the autoclaved fragmented heterolog cortical bone conserved in glycerin (98%) and methylmethacrylate was used as a bone graft for the reconstruction. The graft was placed in the receptor bed and its integration was evaluated by computed tomography after 30, 60 and 90 days. There was gradual bone graft incorporation in the receptor bed during the time in 100% of the cases. Fragmented cortical bone heterograft and methylmethacrylate was biologically compatible and promotes bone defect reparation without signs of infection, migration and or rejection, featuring a new option of osseous substitute to fill in bone defects.

Mechanical study of PLA-PCL fibers during in vitro degradation.

The aliphatic polyesters are widely used in biomedical applications since they are susceptible to hydrolytic and/or enzymatic chain cleavage, leading to α-hydroxyacids, generally metabolized in the human body. This is particularly useful for many biomedical applications, especially, for temporary mechanical supports in regenerative medical devices. Ideally, the degradation should be compatible with the tissue recovering. In this work, the evolution of mechanical properties during degradation is discussed based on experimental data. The decrease of tensile strength of PLA-PCL fibers follows the same trend as the decrease of molecular weight, and so it can also be modeled using a first order equation. For each degradation stage, hyperelastic models such as Neo-Hookean, Mooney-Rivlin and second reduced order, allow a reasonable approximation of the material behavior. Based on this knowledge, constitutive models that describe the mechanical behavior during degradation are proposed and experimentally validated. The proposed theoretical models and methods may be adapted and used in other biodegradable materials, and can be considered fundamental tools in the design of regenerative medical devices where strain energy is an important requirement, such as, for example, ligaments, cartilage and stents.

Polymeric piezoelectric actuator substrate for osteoblast mechanical stimulation.

Bone mass distribution and structure are dependent on mechanical stress and adaptive response at cellular and tissue levels. Mechanical stimulation of bone induces new bone formation in vivo and increases the metabolic activity and gene expression of osteoblasts in culture. A wide variety of devices have been tested for mechanical stimulation of cells and tissues in vitro. The aim of this work was to experimentally validate the possibility to use piezoelectric materials as a mean of mechanical stimulation of bone cells, by converse piezoelectric effect. To estimate the magnitude and the distribution of strain, finite numerical models were applied and the results were complemented with the optical tests (Electronic Speckle Pattern Interferometric Process). In this work, osteoblasts were grown on the surface of a piezoelectric material, both in static and dynamic conditions at low frequencies, and total protein, cell viability and nitric oxide measurement comparisons are presented.

Development of ligament tissue biodegradable devices: a review.

This bibliographic review is focused on ligament tissue rehabilitation, its anatomy-physiology, and, mainly, on the dimensioning considerations of a composite material solution. The suture strength is problematic during the tissue recovering, implying reduction of mobility for several months. However, early postoperative active mobilization may enable a faster and more effective recovering of tissue biomechanical functions. As the risk of tendon rupture becomes a significant concern, a repair technique must be used to withstand the tensile forces generated by active mobilization. However, to avoid stress shielding effect on ligament tissue, an augmentation device must be designed on stiffness basis, that preferably will decrease. Absorbable biocomposite reinforcements have been used to allow early postoperative active mobilization and avoid the shortcomings of current repair solutions. Tensile strength decrease of the repair, during the initial inflammatory phase, is expected, derived from oedema and tendon degradation. In the fibroblastic phase, stiffness and strength will increase, which will stabilize during the remodeling phase. The reinforcement should be able to carry the dynamic load due to locomotion with a mechanical behavior similar to the undamaged natural tissue, during all rehabilitation process. Moreover, the degradation rate must also be compatible with the ligament tissue recovering. The selection and combination of different biodegradable materials, in order to make the biocomposite reinforcement functionally compatible to the damaged sutured tissue, in terms of mechanical properties and degradation rate, is a major step on the design process. Modelling techniques allow pre-clinical evaluation of the reinforcement functional compatibility, and the optimization by comparison of different composite solutions in terms of biomechanical behavior.

ABAD: a potential therapeutic target for Abeta-induced mitochondrial dysfunction in Alzheimer's disease.

Amyloid-beta-peptide (Abetabinding to mitochondrial Abeta-binding alcohol dehydrogenase (ABAD) enzyme triggers a series of events leading to mitochondrial dysfunction characteristic of Alzheimer's disease (AD). Thus this interaction may represent a novel target for treatment strategy against AD. In this review we summarize current findings regarding the ABAD-Abeta interaction, namely structural and biophysical data, available inhibitors and more recent data from proteomic studies.

Somatic growth of a school-aged population from Mozambique: trend and biosocial meaning.

A cross-sectional study of children and adolescents from Maputo, Mozambique, was carried out in order to (1) describe the current growth status of children and adolescents from Maputo, (2) evaluate the relative status of the growth and development of youth from Maputo compared to WHO international standards, (3) assess the relationship between socioeconomic status and growth and development, and (4) assess the impact that the civil war (1980-1992) had on the health status of children and adolescents living in Maputo. The sample is composed of 2,271 subjects (1,098 boys and 1,173 girls), age 6 to 17 years. Somatic measures included height, weight, and skinfold thicknesses from which nutritional indicators were calculated and plotted against WHO norms. Subjects were divided into three groups according to their socioeconomic status. Data from a cross-sectional study done in the same areas in 1992 was used to analyze the impact of war. Beginning at 11 years, Maputo students are always shorter and weigh less than the WHO standards. BMI in boys from 11 years and in girls from 12 years is somewhat lower than the WHO norms. A social gradient is evident, favoring those students with higher socioeconomic status. Height, weight, BMI, fat mass, and lean body mass are always higher in the 1999 sample than in the 1992 study. We conclude that (1) there is a substantial difference in height and weight values of Maputo children and adolescents compared to WHO standards; (2) there is a clear advantage of being of higher socioeconomic status; (3) socioeconomic status, hygiene, and sanitation are the main factors responsible for the greater values of the 1999 sample; and (4) differences between the stature of students with higher socioeconomic status and the WHO norms are almost irrelevant. This last aspect reveals the importance of socioeconomic factors in determining the growth process, implying its importance in facilitating the "expression" of the genotypes available in the population.

New designs for MRI contrast agents.

New designs for Magnetic Resonance Imaging contrast agents are presented. Essentially, they all are host-guest inclusion complexes between y-cyclodextrins and polyazamacrocycles of gadolinium (III) ion. Substitutions have been made to the host to optimise the host-guest association. Molecular mechanics calculations have been performed, using the UFF force field for metals, to decide on the suitability of the substitutions, and to evaluate the host-guest energies of association. Interesting general conclusions have been obtained, concerning the improvement of Magnetic Resonance Imaging contrast agents; namely, a set of rational methodologies have been deduced to improve the association between the gadolinium (III) chelates and the cyclodextrins, and their efficiency is demonstrated with a large set of substituted complexes, opening new doors to increase the diagnostic capabilities of Magnetic Resonance Imaging.

Empirical validation of an instrument to measure habitual physical activity in youth from Maputo, Mozambique.

To develop a questionnaire to assess habitual physical activity in Mozambican children and youth, a study with school youth of Maputo was done. The study included the assessment of usual activities, development of the questionnaire, and testing its validity and reliability. The questionnaire was initially based on anecdotal observations of the usual activities of this population, then a sample of 20 children was observed during 24 h and interviewed the day before with a model that asked the subjects about the time spent in each activity. Fifteen days later the same students were interviewed with the questionnaire in order to test its validity. After another 15 days, the reliability of the questionnaire was tested. To score the questionnaire, estimation of metabolic equivalents (METS) of the socioculturally specific activities was done. This was based on published tables and heart rate monitoring of the children performing the activities listed on the questionnaire. Intraclass correlations between time observed and time reported ranged form 0.06-0.80, demonstrating limited capacity of the children to report time. However, percentage of agreement between the observations and the questionnaire concerning activity levels was 83%. It was concluded that the questionnaire may be a useful instrument for assessing the patterns of physical activity of African youth and for classifying groups according to levels of activity. However, it has limited utility for estimating energy expenditure. Am. J. Hum. Biol. 12:437-446, 2000. Copyright 2000 Wiley-Liss, Inc.

Preliminary investigation of a novel controlled stiffness proximal femoral prosthesis.

Previous studies have suggested that a controlled stiffness prosthesis is required to address the conflicting requirements of minimizing stress shielding and micromotion. The design for a controlled stiffness prosthesis is proposed and a preliminary analytical investigation performed to assess its predicted performance before fabrication of a prototype component. The novel prosthesis consisted of a cobalt-chrome core and a flexible composite outer layer. Varying the composite layer thickness allowed the prosthesis stiffness to be controlled. Three variants of the controlled stiffness prosthesis were critically assessed using the finite element method and their predicted performance compared with those of conventional prosthesis designs. The potential for stress shielding was assessed by examining the periosteal strain energy and the potential for migration assessed by examining the endosteal minimum principal cancellous bone stresses. Both the conventional and controlled stiffness implants performed poorly as press-fit prostheses. All the press-fit prostheses generated high cancellous bone stresses, suggesting that excessive migration of these implants would be likely. The controlled stiffness implants performed better than the conventional implants when bonded to the surrounding bone. Although the controlled stiffness implants did not eliminate stress shielding of the calcar, they produced higher strain energies than the conventional designs. The findings of this study are that osseointegrated controlled stiffness implants may perform better than current osseointegrated cementless prostheses and therefore it is worth while progressing to the next stage, of prototyping an implant.

Relationship between physical activity, socioeconomic status, and physical fitness of 8-15-year-old youth from Mozambique.

A cross-sectional study of 593 students (277 boys, 316 girls) 8-15 years of age was done to evaluate the physical fitness (PF) of children and adolescents from Maputo, Mozambique, relative to socioeconomic status (SES) and physical activity (PA). PF was assessed by a battery of field tests including the sit and reach, sit-ups, hand grip strength, a 10 × 5 meters shuttle run, and two distance runs, 1,600 and 2,400 meters. PA was estimated with a questionnaire designed for this population. Students were divided into three groups according to region of residence, which was used as the criterion of SES. PA was more intense among underprivileged students due to domestic activities and walking time per day. PF significantly differed among SES groups. Poor students exhibited significantly better results on the sit and reach and endurance runs, while privileged children performed better on sit-ups and the shuttle run. There were no differences in grip strength. Comparison with North American reference data suggests that Mozambican youth have greater flexibility and cardiorespiratory endurance, but less absolute strength and power. The results suggest that SES is an important determinant of fitness in Mozambique, especially because of its influence on body size, composition, and on PA. In addition, cultural effects on the performance of the tests were indicated. Am. J. Hum. Biol. 9:449-457, 1997. © 1997 Wiley-Liss, Inc.