Biomechanics of biomaterials used in soft tissue regenerative

Biodegradable polymers have been used in implantable medical devices, such as suture fibers, fixation screws and soft tissue engineering devices. Apart from biological compatibility, these devices shall also be functional compatible and perform adequate mechanical temporary support during the healing process. In regenerative medicine, the scaffold that will provide this temporary support should simultaneously enhance cellular adhesion, proliferation and remodeling of new tissue. In soft tissue applications, biodegradable polymers are the materials of election. These materials undergo through a process of degradation, mainly controlled by hydrolysis, leading to a reduction of molecular weight, followed by reduction of strength and finally a reduction of mass until it is totally absorbed and assimilated by the host. Fatigue/creep damage also contribute to the progressive decrease of mechanical properties. Meanwhile, cells cultured over the scaffold will produce the new tissue that will gradually replace the material biomechanical functions.Os polímeros biodegradáveis têm sido utilizados em dispositivos médicos implantáveis, como fios de sutura, parafusos e dispositivos para engenharia de tecidos moles. Além da compatibilidade biológica, tais dispositivos devem apresentar compatibilidade funcional e desempenhar funções temporárias de suporte mecânico durante o processo de cura. Em medicina regenerativa, este suporte temporário deve favorecer a adesão celular, a sua proliferação e a remodelação de novo tecido. Em engenharia de tecidos moles os polímeros biodegradáveis são os materiais de eleição. Estes materiais sofrem um processo de degradação, controlado sobretudo hidrólise, e que resulta numa redução do peso molecular, seguida de uma redução da resistência mecânica e finalmente uma redução da massa até a completa absorção e assimilação pelo organismo. O dano por fadiga/fluência também contribui para a progressiva diminuição das propriedades mecânicas. Entretanto, as células cultivadas sobre o suporte vão produzir o novo tecido que vai gradualmente substituir as funções biomecânicas do material.Peer ReviewedAward-winnin

Spectra of weighted algebras of holomorphic functions

We consider weighted algebras of holomorphic functions on a Banach space. We determine conditions on a family of weights that assure that the corresponding weighted space is an algebra or has polynomial Schauder decompositions. We study the spectra of weighted algebras and endow them with an analytic structure. We also deal with composition operators and algebra homomorphisms, in particular to investigate how their induced mappings act on the analytic structure of the spectrum. Moreover, a Banach-Stone type question is addressed.Comment: 25 pages Corrected typo

Beneficial effects of the activation of the Angiotensin-(1-7) MAS receptor in a murine model of adriamycin-induced nephropathy

Angiotensin-(1-7) [Ang-(1-7)] is a biologically active heptapeptide that may counterbalance the physiological actions of angiotensin II (Ang II) within the renin-angiotensin system (RAS). Here, we evaluated whether activation of the Mas receptor with the oral agonist, AVE 0991, would have renoprotective effects in a model of adriamycin (ADR)-induced nephropathy. We also evaluated whether the Mas receptor contributed for the protective effects of treatment with AT1 receptor blockers. ADR (10 mg/kg) induced significant renal injury and dysfunction that was maximal at day 14 after injection. Treatment with the Mas receptor agonist AVE 0991 improved renal function parameters, reduced urinary protein loss and attenuated histological changes. Renoprotection was associated with reduction in urinary levels of TGF-{beta}. Similar renoprotection was observed after treatment with the AT1 receptor antagonist, Losartan. AT1 and Mas receptor mRNA levels dropped after ADR administration and treatment with losartan reestablished the expression of Mas receptor and increased the expression of ACE2. ADR-induced nephropathy was similar in wild type (Mas(+/+)) and Mas knockout (Mas (-/-)) mice, suggesting there was no endogenous role for Mas receptor activation. However, treatment with Losartan was able to reduce renal injury only in Mas(+/+) , but not in Mas (-/-) mice. Therefore, these findings suggest that exogenous activation of the Mas receptor protects from ADR-induced nephropathy and contributes to the beneficial effects of AT1 receptor blockade. Medications which target specifically the ACE2/Ang-(1-7)/Mas axis may offer new therapeutic opportunities to treat human nephropathies

Chromosome studies on the silky anteater Cyclopes Didactylus L. (Myrmecophagidae: Xenarthra, Edentata)

The karyotype of the silky anteater Cyclopes didactylus, the smallest of the anteaters is described. A notable difference in karyotypes exists between C. didactylus (2n = 64) and the other species of the family Myrmecophagidae. Both fusion/fission as well as other mechanisms are probably involved in the reduction of the chromosome number of 64 chromosome in Cyclopes to 60 and 54 in Tamandua and Myrmecophaga, respectively. © 1985 Taylor & Francis Group, LLC

V Seminario Ibérico / I Seminario Iberoamericano Ciencia-Tecnología-Sociedad en la enseñanza de las ciencias

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