Introduction: In recent decades, hydrogels have gained increasing interest as potential cartilage replacement materials. Among these, polyvinyl alcohol (PVA) hydrogels have shown to be very promising candidates due to their biocompatibility, high degree of swelling, and elastic and rubbery nature, which allows them to mimic the natural tissues [1]. The properties of PVA-based hydrogels can be tailored by adding different compounds. The main objective of this study is to investigate the effect of adding two distinct crosslinking agents to the polymeric mixture, on the microstructure, water content, hydrophilicity, and mechanical behaviour of PVA hydrogels. Materials and Methods: Four types of materials were prepared using a PVA aqueous solution (7.75% w/w) containing two different crosslinking agents: glyoxal at 0.2% and 1%, and glutaraldehyde at 5.95% and 11.9% (where the percentages indicated refer to the mass of the crosslinker relative to that of the PVA). The mixtures were poured into Petri dishes and dried at 37 C (4 days) and then at 60 C (2 days). The surface morphology of the samples was analysed by scanning electron microscopy (SEM) after they had been lyophilised for 48 h and coated with an Au/Pd layer. To determine the equilibrium water content (EWC), samples hydrated in pure water were weighed, dried at 60 C until reached a constant weight, and weighed again. The water contact angles were determined in hydrated samples by the captive bubble method. To evaluate the mechanical properties, compression tests were performed with a texturometer on samples placed in an aqueous medium, using a test speed of 0.1 mm/s until a force of 5 kg was reached. Results: The results showed that all materials are non-porous and have a similar surface morphology. The hydrogels crosslinked with glyoxal present higher EWC values (69.1% and 69.7% for 0.2% and 1% of glyoxal, respectively), while those with glutaraldehyde have an EWC of 52.8% and 41.5% for 5.95% and 11.9% of glutaraldehyde, correspondingly. Concerning wettability, all samples are hydrophilic and exhibit a water contact angle <55 . The modulus of elasticity of materials prepared with glyoxal is lower (1.1 À 1.4 MPa) than that of those done with glutaraldehyde (6.2 À 9.3 MPa), but their toughness is higher (0.67 À 0.45 MJ/m 3 vs 0.22 À 0.27 MJ/m 3 ). For gels crosslinked with glyoxal, the dissipated energy assumes values between 17 À 22% and for samples prepared with glutaraldehyde, it is negligible. Discussion and conclusions: In conclusion, the nature and amount of crosslinking can determine the properties of PVA hydrogels. Glyoxal-containing materials have a greater water absorption capacity, are less stiff, absorb more energy, and exhibit a lower elastic recovery than glutaraldehyde-containing gels. Overall, glyoxal-crosslinked hydrogels have EWC values and mechanical properties closer to those of the natural cartilage, and therefore should be preferred as potential substitutes of this tissue.
Introduction: Bone is a regulator of numerous metabolic processes that are independent of mineral metabolism [1]. The relationship between osteocalcin (OC), a bone-specific protein, and metabolic parameters, as glycaemia, insulin secretion and b-cell proliferation have been studied and implied the potential impact of the skeleton on energy regulation and glucose metabolism. Also, intermittent injections of OC have proven to improve glucose metabolism and prevent type 2 diabetes in mice [2]. Moreover, electrolyte disorders are observed in metabolic pathways involved in impaired energy metabolism and glycaemic regulation. Recent data associate the use of calcium and vitamin D supplementation to reduce the risk of Diabetes Mellitus (DM) [3]. The aim of the study was to investigate the long-term effects of altered bone turnover on glucose metabolism, using an animal model for osteopenia. Materials and methods: Animal experiments were conducted at FMV/UTL, according to its ethics committee, Portuguese law and EU Directive 2010/63/EU. At baseline, two groups of 25 adult female Wistar rats were gathered: control and ovariectomized (OVX). The surgery to induce osteopenia [4] was performed 1 month prior to baseline. At all timepoints, for 12 months, biomarker s levels of bone turnover and diabetes control were determined by ELISA protocols. Additionally, after sample preparation, system calibration and validation, bone and liver tissues were analysed for their elemental composition by wavelength dispersive X-ray fluorescence (WDXRF) spectroscopy, using a 4 kW commercial system (Bruker S4 Pioneer).Results: Here we report data of the 12 months of the protocol. OVX animals showed increased bone resorption and lower concentration of elements involved in the calcium metabolism (calcium, phosphorus and magnesium) in femurs, which are important features of bone strength. Although there is amplified bone resorption in OVX group, calcium does not accumulate in its hepatic parenchyma, as liver of OVX animals present Ca concentrations significantly lower than those of controls. These differences between OVX and control animals in bone metabolism and composition are concomitant with clear increases of serum glucose levels in the OVX group, following a time-dependent pattern for the observed differences. By contrast, much less marked differences between the groups were observed for serum insulin levels. Discussion and conclusions: Increased bone resorption and lower bone mineral content leads to hyperglycaemia manifesting in a time dependent manner. Since these effects were observed almost from the onset of the protocol, the data suggest that the relationships between diseases characterized by increased bone turnover, such as osteoporosis, and by disrupted glucose metabolism, such as diabetes, can occur in early adulthood.
Objetivos: Evaluar la concordancia entre el diagnóstico clínico e histopatológico de lesiones bucales en pacientes sometidos a biopsias. Identificar las lesiones bucales más frecuentes y su correlación con la edad, el sexo y la ubicación anatómica. Métodos: estudio retrospectivo de 368 exámenes patológicos recogidos entre 2008 y 2018, correspondientes a biopsias realizadas en la Clínica Universitária Egas Moniz . Se realizó un análisis detallado de los informes histopatológicos adjuntos a los archivos de los pacientes y se evaluaron las variables sexo, edad, localización anatómica, diagnóstico clínico y diagnóstico histopatológico. Resultados: El género más afectado fue el femenino (55%);el grupo de edad más común fue el de 61 a 70 años; La localización anatómica más biopsiada fue la encía (23,9%); las cinco entidades patológicas más frecuentes fueron fibroma (26,4%), quiste radicular (8,7%), licor plano oral (7,6%), hemangioma (6,3%) y leucoplasia oral (6,0%) . De acuerdo, el 74,5% de los casos fueron concordantes y el 25,5% discordantes. Las lesiones más concordantes fueron Quiste Radicular (90,6%), Traumatismo (87,5%), Hemangioma (82,6%), Fibroma (82,5%) y Mucocele (82,5%). Conclusión: este estudio demuestra un nivel significativo de concordancia entre el diagnóstico clínico e histopatológico en esta área en particular, obtenido de manera consistente en un período de diez años.
Introduction: Polyvinylacohol (PVA)/chitosan hydrogels are ideal candidates for the production of wound dressings as their combination can provide good mechanical and antibacterial properties, alongside the ability to be loaded and release drugs [1,2]. The main goal of this work is to evaluate the possibility of using PVA/chitosan hydrogels as platforms for the release of octenidine dihydrochlorate and 2-phenoxyethanol, a drug combination that has antiseptic, antibacterial and antimycotic properties. Materials and methods: PVA aqueous solutions were prepared by dissolution at 90 C and chitosan was added to get different mass ratios (3:1, 1:1) and a final polymer concentration of 5% w/w. The mixtures were poured in petri dishes and submitted to five cycles of freeze-thawing (18 h at À20 C, 6 h at 23 C in each cycle) to trigger polymerisation. After a washing step, they were lyophilised. Before testing, the samples were hydrated for 72 h. Swelling ratio, water content and degradation experiments in simulated exudate containing lysozyme were performed to assess the stability of the hydrogels. Contact angle was measured using captive bubble method and hydrogels structure was assessed using SEM. Drug loading was carried out by soaking the samples in OctisetV R solution at room temperature. Drug release experiments were performed in simulated exudate using Franz cells. Results: The hydrogels showed swelling ratios between %1300 and 2100% and high water contents of 93-95%. Degradation in the first 2 days in the presence of the protein was less than 37%. The hydrogels showed high hydrophilicity and porosity. Drug loading and release experiments (Figure 1) proved that the hydrogels are able to release both drugs in a controlled way during the first day. Discussion and conclusions: The obtained results suggest that the proposed formulations possess drug retention abilities compatible with their use. They shall be suitable for the production of wound dressings with therapeutic properties. Further research should provide insight into the mechanical properties of the hydrogels, their antibacterial behaviour and the choice of a sterilisation method.
Introduction: The concentrations of some chemical elements may differ between healthy and diseased tissues. The knowledge of these differences is pivotal to understand the metabolic processes involved in both physiological and diseased states. The aim of this study was to evaluate the elemental composition of calcium (Ca) and phosphorus (P) in the bone of rats subjected to glucose intolerance and/or infrasound.Materials and Methods: X-ray fluorescence spectroscopy was applied in the concentration determination of Ca and P in samples of Wistar rat tibiae. Tibiae from glucose intolerant, non-intolerant, exposed and non-exposed to infrasound rats were analysed.Results: There was a significant decrease in bone P concentration in glucose intolerant rats compared to non-intolerant animals. Similarly, the Ca/P ratio was higher in glucose intolerant animals. There were no significant differences for bone Ca concentration in both studied groups, nor between animals exposed and non-exposed to infrasound in either studied element.Discussion and Conclusions: Glucose intolerant rats had lower bone P concentration and unaltered bone Ca concentration compared to non-glucose intolerant rats. Infrasound exposure was not associated to changes of bone Ca or P. The reduction of bone P concentration may be associated with the augmented risk of bone fractures in diabetes.
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