3D Printing of a Graphene-Modified Photopolymer Using Stereolithography for Biomedical Applications: A Study of the Polymerization Reaction.

Additive manufacturing is gaining importance thanks to its multiple advantages. Stereolithography (SLA) shows the highest accuracy and the lowest anisotropy, which has facilitated the emergence of new applications as dentistry or tissue engineering. However, the availability of commercial photopolymers is still limited, and there is an increasing interest in developing resins with properties adapted for these new applications. The addition of graphene-based nanomaterials (GBN) may provide interesting advantages, such as improved mechanical properties and bioactivity. However, there is a lack of knowledge regarding the effect of GBNs on the polymerization reaction. A photopolymerizable acrylic resin has been used, and the effect of the addition of 0.1wt% of graphene (G); graphene oxide (GO) and graphite nanoplatelets (GoxNP) on printability and polymerization have been investigated. It was observed that the effect depended on GBN type, functionalization and structure (e.g., number of layers, size, and morphology) due to differences in the extent of dispersion and light absorbance. The obtained results showed that GO and GoxNP did not significantly affect the printability and quality of the final structure, whilst the application of G exhibited a negative effect in terms of printability due to a reduction in the polymerization degree. GO and GoxNP-loaded resins showed a great potential to be used for manufacturing structures by SLA.

Lipid Composition Analysis Reveals Mechanisms of Ethanol Tolerance in the Model Yeast Saccharomyces cerevisiae.

Saccharomyces cerevisiae is an important unicellular yeast species within the biotechnological and the food and beverage industries. A significant application of this species is the production of ethanol, where concentrations are limited by cellular toxicity, often at the level of the cell membrane. Here, we characterize 61 S. cerevisiae strains for ethanol tolerance and further analyze five representatives with various ethanol tolerances. The most tolerant strain, AJ4, was dominant in coculture at 0 and 10% ethanol. Unexpectedly, although it does not have the highest noninhibitory concentration or MIC, MY29 was the dominant strain in coculture at 6% ethanol, which may be linked to differences in its basal lipidome. Although relatively few lipidomic differences were observed between strains, a significantly higher phosphatidylethanolamine concentration was observed in the least tolerant strain, MY26, at 0 and 6% ethanol compared to the other strains that became more similar at 10%, indicating potential involvement of this lipid with ethanol sensitivity. Our findings reveal that AJ4 is best able to adapt its membrane to become more fluid in the presence of ethanol and that lipid extracts from AJ4 also form the most permeable membranes. Furthermore, MY26 is least able to modulate fluidity in response to ethanol, and membranes formed from extracted lipids are least leaky at physiological ethanol concentrations. Overall, these results reveal a potential mechanism of ethanol tolerance and suggest a limited set of membrane compositions that diverse yeast species use to achieve this. IMPORTANCE Many microbial processes are not implemented at the industrial level because the product yield is poorer and more expensive than can be achieved by chemical synthesis. It is well established that microbes show stress responses during bioprocessing, and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells. During fermentative processes, yeast cells encounter culture media with a high sugar content, which is later transformed into high ethanol concentrations. Thus, ethanol toxicity is one of the major stresses in traditional and more recent biotechnological processes. We have performed a multilayer phenotypic and lipidomic characterization of a large number of industrial and environmental strains of Saccharomyces to identify key resistant and nonresistant isolates for future applications.

Effect of transient thermal shocks on alcoholic fermentation performance.

Stuck and sluggish fermentations are among the main problems in winemaking industry leading to important economic losses. Several factors have been described as causes of stuck and sluggish fermentations, being exposure to extreme temperatures barely studied. The objective of this study was to identify thermal conditions leading to stuck and sluggish fermentations, focusing on the impact of an abrupt and transient decrease/increase of temperature on fermentation performance and yeast viability/vitality. Different strains of Saccharomyces cerevisiae, SBB11, T73, and PDM were evaluated in synthetic grape must fermentations. Cold shocks (9 °C and 1.5 °C for 16 h) carried out on different days during the fermentation process were unable to alter fermentation performance. Conversely, shock temperatures higher than 32 °C, applied in early stages of the process, lead to sluggish fermentation showing a delay directly related to the temperature increase. Fermentation delay was associated with a decrease in cell vitality. The impact of the heat shock on fermentation performance was different depending on the strain evaluated and nitrogen supplementation (with or without diammonium phosphate addition). None of the conditions evaluated produced a stuck fermentation and importantly, in all cases must nutrition improved fermentation performance after a heat shock.

Graphene Oxide and Graphene Reinforced PMMA Bone Cements: Evaluation of Thermal Properties and Biocompatibility.

The incorporation of well-dispersed graphene oxide (GO) and graphene (G) has been demonstrated as a promising solution to improve the mechanical performance of polymethyl methacrylate (PMMA) bone cements in an attempt to enhance the long-term survival of the cemented orthopaedic implants. However, to move forward with the clinical application of graphene-based PMMA bone cements, it is necessary to ensure the incorporation of graphene-based powders do not negatively affect other fundamental properties (e.g., thermal properties and biocompatibility), which may compromise the clinical success of the implant. In this study, the effect of incorporating GO and G on thermal properties, biocompatibility, and antimicrobial activity of PMMA bone cement was investigated. Differential scanning calorimetry studies demonstrated that the extent of the polymerisation reaction, heat generation, thermal conductivity, or glass transition temperature were not significantly (p > 0.05) affected by the addition of the GO or G powders. The cell viability showed no significant difference (p > 0.05) in viability when MC3-T3 cells were exposed to the surface of G- or GO-PMMA bone cements in comparison to the control. In conclusion, this study demonstrated the incorporation of GO or G powder did not significantly influence the thermal properties or biocompatibility of PMMA bone cements, potentially allowing its clinical progression.

Graphene and graphene oxide functionalisation with silanes for advanced dispersion and reinforcement of PMMA-based bone cements.

The reinforcement of PMMA bone cements using carbon based nanomaterials has demonstrated to be a potential solution to their poor mechanical properties. The achievement of an optimal dispersion of the nanoparticles within the polymeric matrix is a crucial but not easy stage in the production of high-quality reinforced materials. In this work, a useful route for the graphene (G) functionalisation, via silanisation with (3-methacryloxypropyl) trimethoxy silane (MPS), has been developed, providing a remarkable enhancement in dispersibility and mechanical properties. With the purpose to define the critical graphene surface oxidation parameters for an optimal silanisation, different routes were thoroughly analysed using infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the silanisation significantly improved the G dispersibility: whereas the pristine G dispersion fell down within the first 24 h, the silanised G showed an adequate stability after 5 days. Additionally, this improved dispersibility produced a notable increase in the mechanical properties of the G-reinforced bone cements: in comparison with the pristine G, the compression and bending strength of silanised G increased by 12% and by 13.7% respectively and the fracture toughness by 28%. These results provide very useful information on the relevance that the characteristics of the superficial oxidation of graphene have on the effectiveness of the silanisation process, besides an interesting functionalisation procedure for advanced dispersion and reinforcement of G-PMMA bone cements.

Graphene oxide versus graphene for optimisation of PMMA bone cement for orthopaedic applications.

Graphene (G) and graphene oxide (GO) nano-sized powders with loadings ranging from 0.1 to 1.0wt% were investigated as reinforced agents for polymethyl methacrylate (PMMA) bone cements. The mechanical properties (i.e. bend strength, bend modulus, compression strength, fracture toughness and fatigue performance) and the thermal properties (i.e. maximum temperature, setting time, curing heat and residual monomer) of the resultant nanocomposites were characterised. The mechanical performance of G-PMMA and GO-PMMA bone cements has been improved at low loadings (≤0.25wt%), especially the fracture toughness and fatigue performance. These improvements were attributed to the fact that the G and GO induced deviations in the crack fronts and hampered crack propagation. The high functionalisation of GO compared with G resulted in greater enhancements because it facilitated the creation of a stronger interfacial adhesion between the GO and PMMA. The use of loadings ≥0.25wt% showed a detriment in the mechanical performance as consequence of the formation of agglomerates as well as to an increase in the porosity. The increase in the residual monomer and the decrease in the curing heat, observed with the increase in the level of G and GO added, suggests that such materials retard and inhibit the curing reaction at high levels of loading by interfering in the radical reaction.

Mechanical and thermal behaviour of an acrylic bone cement modified with a triblock copolymer.

The basic formulation of an acrylic bone cement has been modified by the addition of a block copolymer, Nanostrength(®) (NS), in order to augment the mechanical properties and particularly the fracture toughness of the bone cement. Two grades of NS at different levels of loading, between 1 and 10 wt.%, have been used. Mechanical tests were conducted to study the behaviour of the modified cements; specific tests measured the bend, compression and fracture toughness properties. The failure mode of the fracture test specimens was analysed using scanning electron microscopy (SEM). The effect of NS addition on the thermal properties was also determined, and the polymerisation reaction using differential scanning calorimetry. It was observed that the addition of NS produced an improvement in the fracture toughness and ductility of the cement, which could have a positive contribution by reducing the premature fracture of the cement mantle. The residual monomer content was reduced when the NS was added. However this also produced an increase in the maximum temperature and the heat delivered during the polymerisation of the cement.

[Influence of the physiological medium on the mechanical properties of bone cement: can current studies be extrapolated?]. / Influencia del medio fisiológico sobre las propiedades mecánicas del cemento óseo. ¿Son los estudios actuales extrapolables?

PURPOSE: The use of bone cement is widespread in orthopaedic surgery. Most of the mechanical tests are performed in dry medium, making it difficult to extrapolate the results. The objective of this study is to assess if the mechanical properties of polymethylmethacrylate (PMMA), obtained in previous reports, are still present in a liquid medium. MATERIAL AND METHOD: An experimental study was designed with antibiotic (vancomycin) loaded PMMA. Four groups were defined according to the medium (dry or liquid) and the pre-conditioning in liquid medium (one week or one month). Wear and flexural strength tests were performed according to ASTM and ISO standards. Volumetric wear, friction coefficient, tensile strength, and Young's modulus were analyzed. All samples were examined by scanning electron microscopy. RESULTS: The samples tested in liquid medium showed lower wear and flexural strength values (P<.05). The kind of wear was modified from abrasive to adhesive in those samples studied in liquid medium. The samples with a pre-conditioning time showed lower values of wear (P<.05). CONCLUSIONS: Caution is recommended when extrapolating the results of previous PMMA results. The different mechanical strength of the cement in a liquid medium, observed in saline medium, is much closer to the clinical situation.

Culturable microbiota of ranched southern bluefin tuna (Thunnus maccoyii Castelnau).

AIMS: The Australian tuna industry is based on the ranching of wild southern bluefin tuna (SBT, Thunnus maccoyii). Within this industry, only opportunistic pathogens have been reported infecting external wounds of fish. This study aimed to identify different culturable bacteria present in three cohorts of SBT and to determine normal bacteria and potential pathogens in isolates from harvest fish and moribund/dead fish. Post-mortem changes in the microbiota were also studied. METHODS AND RESULTS: Moribund/dead showed a greater proportion of members from the family Vibrionaceae than harvested fish; the latter presented mainly non-Vibrio species. In harvested fish spleens, Vibrio splendidus I complex was the most commonly identified group among Vibrio isolates, while most groups from the family Vibrionaceae were isolated from gills. For moribund/dead, Vibrio chagasii and Photobacterium damselae subsp. damselae were common in gill, spleen and kidney samples. Non-Vibrio isolates from gills were characterized using 16S rRNA sequencing as Flavobacteriaceae and classes Gammaproteobacteria and Alphaproteobacteria, mainly from the genera Winogradskyella and Tenacibaculum. Post-mortem changes showed dynamic shifts in bacterial dominance in gills, with Vibrionaceae and non-Vibrio spp. found in similar proportions initially and types related to Pseudoalteromonas ruthenica prevailing after 27 h. Spleen samples showed little bacterial growth until 5 h post-mortem, while various Vibrio-associated species were isolated 27 h post-mortem. CONCLUSIONS: Bacterial isolates found include a range of potentially pathogenic bacteria that should be monitored though most of them have yet to be associated with disease in tuna. SIGNIFICANCE AND IMPACT OF THE STUDY: This study forms a foundation for future research into the bacterial population dynamics under different culture conditions of SBT. An understanding of the bacterial compositions in SBT is necessary to evaluate the effects of some bacterial species on their health.

[Prevalence and risk factors for pressure ulcers]. / Prevalencia y factores de riesgo de úlceras por presión.

OBJECTIVES: To study prevalence of pressure ulcers among functionally impaired patients in the community and evaluate risk factors associated with the development of pressure ulcers in these patients.Design. Cross-sectional, observational study. SETTING: Community dwellers served by the Primary Health Care Area of Rincón de la Victoria in Málaga.Participants. All patients included in the <> (n=178). METHODS: A questionnaire was developed to ascertain demographic and health characteristics. Risk factors were evaluated with the Modified Norton Scale. The outcome variable of interest was presence or absence of pressure ulcers, their location and grade. The denominator used for the calculation of the prevalence was the total of evaluated patients. Results. Prevalence of pressure ulcers in our Basic Health Area was 12.9%. The most important sociodemographic characteristic associated with the presence of pressure ulcers in these patients was the educational attainment of the caregiver. Health varaibles of the patient were also associated with the risk of developing ulcers. CONCLUSIONS: Results indicate the need of diagnostic protocols with standardised instruments and prevention plans to reduce pressure ulcers in the community. Longitudinal studies are needed to evaluate interventions in this area.

Prevalencia y factores de riesgo de úlceras por presión / Prevalence and risk factors for pressure ulcers

Objetivo. Conocer la prevalencia de úlceras por presión (UPP) en pacientes incapacitados de una Zona Básica de Salud (ZBS) y caracterizar los factores de riesgo asociados a su aparición. Diseño. Estudio transversal observacional. Emplazamiento. ZBS Rincón de la Victoria (Málaga). Participantes. Pacientes incluidos en el Programa de Incapacitados (n = 178), de la ZBS, residentes en su domicilio o en una residencia geriátrica. Mediciones. Cuestionario específico con variables sociodemográficas y de salud. Para la valoración de factores de riesgo asociados con la formación de UPP, se utilizó la Escala de Norton Modificada (ENM). La variable resultado de interés fue la presencia o ausencia de UPP, localización y grado. El denominador para el cálculo de la prevalencia ha sido el total de pacientes valorados. Resultados. La prevalencia fue del 12,9 per cent. La característica sociodemográfica más significativa asociada con la presencia de úlceras en estos pacientes fue el nivel de instrucción del cuidador. Se constata asociación de determinadas variables del estado de salud del paciente con aparición de UPP. Conclusiones. Los resultados alertan a la necesidad de la realización de protocolos diagnósticos y de intervención comunitaria para reducir la presentación de UPP en pacientes incapacitados que viven en la comunidad (AU)

[Non-venereal sclerosing lymphangitis of the penis. Report of two clinical cases]. / Linfangitis esclerosante no venérea del pene. Presentación de dos casos clínicos.

Nonvenereal sclerosing lymphangitis of the penis is a rare condition that preferably affects men aged between 20 and 40 years, and it is appeared like a hard cord or a nodular lesion in the sulcus coronarius penis. It is believed that it has origin in lymph vessels of the penis. Usually it is resolved in a self-limited way, so the initial treatment is conservative. We report two cases, and some etiopathogenic, diagnosis and therapeutic aspects are discussed.

Linfangitis esclerosante no venérea del pene. Presentación de dos casos clínicos / Non-venereal sclerosing lymphangitis of the penis. Two case reports

La linfangitis esclerosante no venérea del pene se trata de una patología poco frecuente, que afecta preferentemente a varones entre 20 y 40 años, y que se presenta como un nódulo o cordón indurado a nivel del surco coronario. Parece tener su origen en los vasos linfáticos del pene. Evoluciona habitualmente de manera autolimitada, por lo que el tratamiento inicial es conservador. Presentamos dos casos clínicos, comentando algunos aspectos etiopatogénicos, diagnósticos y terapéuticos (AU)

Adenocarcinoma vesical primario de células en anillo de sello. Aportación de un caso clínico / Signet-ring cell's primary bladder adenocarcinoma. A case is reported

El adenocarcinoma de células en anillo de sello primario de vejiga es una neoplasia muy poco frecuente y de alta agresividad. Sus aspectos clínicos y diagnósticos no se diferencian mucho del resto de las neoplasias vesicales, siendo importante el diagnóstico diferencial con un posible origen primario extravesical. Sólo responde a cirugía radical, siendo el pronóstico infausto. Presentamos un caso clínico (AU)

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Fractura de pene. Revisión de la literatura y presentación de dos casos / Fracture of the penis. Literature review and contribution of two cases

Presentamos dos casos de una patología poco frecuente como es la rotura de cuerpo cavernoso de pene, sometidos a tratamiento quirúrgico precoz con buenos resultados. Revisamos así mismo, los aspectos etiológicos, clínicos, diagnósticos y el tratamiento más apropiado (AU)

[Cystic ureteritis: importance of chronic infection-inflammation as etiologic factor. Report of a clinical case]. / Ureteritis quística: importancia de la infección-inflamación crónica como factor etiológico. Aportación de un caso clínico.

Cystic Ureteritis is a very rare disease. It is more commun in elderly patients. This pathology is characterized by the formation of several submucous cystic in ureter, pelvis and/or bladder. We project the importance of the infectious and inflammatory factors as the disease etiology. We report a case of a woman with recurrent urinary tract infection, coral lithiasis and left ureteritis cystica. It is included a literature review and we explain the main clinical, diagnostic and therapeutic aspects.

[Giant inguinoscrotal bladder hernia]. / Hernia vesical inguinoescrotal gigante.

Inguinoscrotal bladder hernia occur in 0.4 to 3% of general poblation, though massive hernia are much rare. We present a new case of a giant inguinoscrotal bladder hernia, which was solved by surgery. It includes a clinical, diagnostic and therapeutic aspects, and a review of the relative literature.

Ureteritis quística: importancia de la infección-inflamación crónica como factor etiológico. Aportación de un caso clínico / Cystiic ureteritis: the importance of the cronic infection-inflammation as an etiologic factor. A case is reported

La Ureteritis Quística es una enfermedad poco frecuente, característica de la edad adulta, en la que se producen múltiples quistes en el interior del uréter, pelvis y/o vejiga, recubiertos por el urotelio. Resaltamos la importancia del factor infeccioso-inflamatorio como causa de la enfermedad. Presentamos un caso clínico de una mujer con infecciones urinarias de repetición, litiasis coraliforme y ureteritis quística izquierdas. Realizamos una revisión de la literatura, comentando los principales aspectos clínicos, diagnósticos y terapéuticos (AU)

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