The efficacy of immediate implantation of macroporous poly(N-[2-hydroxypropyl]-methacrylamide) hydrogel after laceration spinal cord injury in young rats / Eficacia de la implantación inmediata de hidrogel macroporoso de poli (N- [2-hidroxipropil] - metacrilamida) después de una lesión de la médula espinal en ratas jóvenes

SUMMARY: Spinal cord regeneration after mechanical injury is one of the most difficult biomedical problems. This article evaluates the effect of poly(N-[2-hydroxypropyl]-methacrylamide) hydrogel (PHPMA-hydrogel) on spinal cord regeneration in young rats after lateral spinal cord hemi-excision (laceration) at the level of segments T12-T13 (TrGel group). The locomotor function score (FS) and the paretic hindlimb spasticity score (SS) were assessed according to Basso-Beattie-Bresnahan (BBB) and Ashworth scales, respectively, and compared to a group of animals with no matrix implanted (Tr group). Regeneration of nerve fibers at the level of injury was evaluated at ~5 months after spinal cord injury (SCI). One week after the SCI induction, the FS on the BBB scale was 0.9±0.5 points in the Tr group and 3.6±1.2 points in the TrGel group. In the Tr group, the FS in 5 months was significantly lower than in 2 weeks after SCI, while no significant changes in FS were detected in the TrGel group over the entire observation period. The final FS was 0.8±0.3 points in the Tr group and 4.5±1.8 points in the TrGel group. No significant changes in SS have been observed in the TrGel group throughout the experiment, while the Tr group showed significant increases in SS at 2nd week, 6th week, 3th month and 5th month. The SS in 5 months was 3.6±0.3 points on the Ashworth scale in the Tr group and 1.8±0.7 points in the TrGel group. Throughout the observation period, significant differences in FS between groups were observed only in 5 weeks after SCI, whereas significant differences in SS were observed in 2, 3 and 6-8 weeks post-injury. Glial fibrous tissue containing newly formed nerve fibers, isolated or grouped in small clusters, that originated from the surrounding spinal cord matter have been found between the implanted hydrogel fragments. In conclusion, PHPMA-hydrogel improves recovery of the hindlimb locomotor function and promotes regenerative growth of nerve fibers. Further research is needed to clarify the mechanism of this PHPMA-hydrogel effect.

RESUMEN: La regeneración de la médula espinal después de una lesión mecánica es uno de los problemas biomédicos más difíciles. Este artículo evalúa el efecto del hidrogel de poli (N- [2-hidroxipropil] -metacrilamida) (PHPMA-hidrogel) sobre la regeneración de la médula espinal en ratas jóvenes después de la hemiescisión lateral de la médula espinal (lesión) a nivel de los segmentos T12 - T13 (Grupo TrGel). La puntuación de la función locomotora (FS) y la puntuación de espasticidad parética de las patas traseras (SS) se evaluaron de acuerdo con las escalas de Basso- Beattie-Bresnahan (BBB) y Ashworth, respectivamente, y se compararon con un grupo de animales sin matriz implantada (grupo Tr). Se evaluó la regeneración de las fibras nerviosas al nivel de la lesión ~ 5 meses después de la lesión de la médula espinal (LME). Una semana después de la inducción de SCI, el FS en la escala BBB fue 0,9 ± 0,5 puntos en el grupo Tr y 3,6 ± 1,2 puntos en el grupo TrGel. En el grupo Tr, el FS en 5 meses fue significativamente menor que en 2 semanas después de SCI, mientras que no se detectaron cambios significativos en FS en el grupo TrGel durante el período de observación. El FS final fue de 0,8 ± 0,3 puntos en el grupo Tr y de 4,5 ± 1,8 puntos en el grupo TrGel. No se han obser- vado cambios significativos en SS en el grupo TrGel durante el experimento, mientras que el grupo Tr mostró aumentos significativos en SS en la 2ª semana, 6ª semana, 3º mes y 5º mes. La SS en 5 meses fue de 3,6 ± 0,3 puntos en la escala de Ashworth en el grupo Tr y de 1,8 ± 0,7 puntos en el grupo TrGel. A lo largo del período de observación, se observaron diferencias significativas en FS entre los grupos solo en 5 semanas después de la LME, mientras que se observaron diferencias significativas en SS en 2, 3 y 6-8 semanas después de la lesión. Entre los fragmentos de hidrogel implantados se observó tejido fibroso glial que contenía fibras nerviosas recién formadas, aisladas o agrupadas en pequeños grupos, que se originaban a partir de la materia de la médula espinal circundante. En conclusión, PHPMA-hydrogel mejora la recuperación de la función locomotora de las patas traseras y promueve el crecimiento regenerativo de las fibras nerviosas. Se requieren más estudios para aclarar el mecanismo del efecto de hidrogel PHPMA.

Smart material based on boron crosslinked polymers with potential applications in cancer radiation therapy.

Organoboron compounds have been playing an increasingly important role in analytical chemistry, material science, health applications, and particularly as functional polymers like boron carriers for cancer therapy. There are two main applications of boron isotopes in radiation cancer therapy, Boron Neutron Capture Therapy and Proton Boron Fusion Therapy. In this study, a novel and original material consisting of a three-dimensional polymer network crosslinked with [Formula: see text]B enriched boric acid molecules is proposed and synthesized. The effects of the exposition to thermal neutrons were studied analyzing changes in the mechanical properties of the proposed material. Dedicated Monte Carlo simulations, based on MCNP and FLUKA main codes, were performed to characterize interactions of the proposed material with neutrons, photons, and charged particles typically present in mixed fields in nuclear reactor irradiations. Experimental results and Monte Carlo simulations were in agreement, thus justifying further studies of this promising material.

Adhesión a tejidos dentarios / Bonding to dental tissues

En las últimas décadas, la odontología restauradora ha logrado un avance significativo que permite preservar tejido dentario mediante la realización de restauraciones adheridas, directas e indirectas. Este enfoque moderno de “Odontología Mínimamente Invasiva”, se centra en obtener preparaciones dentarias con un diseño más conservador, basándose en la eficacia de la adhesión al tejido remanente de los biomateriales utilizados. El conocimiento de las características de los sustratos y de los materiales adhesivos, y la comprensión del mecanismo de adhesión es un factor fundamental para alcanzar el éxito clínico...

Poly(HEMA) brushes emerging as a new platform for direct detection of food pathogen in milk samples.

Surface plasmon resonance (SPR) biosensors capable of in real time detection of Cronobacter at concentrations down to 106 cells mL⁻¹ in samples of consumer fresh-whole fat milk, powder whole-fat milk preparation, and powder infant formulation were developed for the first time. Antibodies against Cronobacter were covalently attached onto polymer brushes of poly(2-hydroxyethyl methacrylate) (poly(HEMA)) grafted from the SPR chip surface. The lowest detection limit, 104 cells mL⁻¹, was achieved in phosphate buffered saline (pH 7.4) with sensors prepared by covalent immobilization of the same antibodies onto a self assembled monolayer (SAM) of hexa(ethylene glycol) undecanethiol (EG6). However, when the EG6 based sensors were challenged with milk samples the non-specific response due to the deposition of non-targeted compounds from the milk samples was much higher than the specific response to Cronobacter hampering the detection in milk. Similar interfering fouling was observed on antifouling polymer brushes of hydroxy-capped oligoethylene glycol methacrylate and even a 10 times higher fouling was observed on the widely used SAM of mixed hydroxy- and carboxy-terminated alkanethiols. Only poly(HEMA) brushes totally suppressed the fouling from milk samples. The robust well-controlled surface initiated atom transfer radical polymerization of HEMA allowed the preparation of highly dense brushes with a minimal thickness so that the capture of antigens by the antibodies immobilized on the brush layer could take place close to the gold SPR surface to provide a stronger optical response while the fouling was still suppressed. A minimum thickness of 19 nm of poly(HEMA) brush layer was necessary to suppress completely non-specific sensor response to fouling from milk.

Evaluation of peritoneal adhesions formation and tissue response to polypropylene - poli (2-hydroxyethyl methacrylate)-(polyHEMA) implant on rats' abdominal wall.

PURPOSE: To verify if the composit poli (2-hydroxyethyl methacrylate)-PolyHEMA/polypropylene mesh implanted in the female rat's abdominal wall could be suitable for the prevention of peritoneal adhesions, and for the evaluation of the tecidual response produced by this biomaterial. METHODS: Polypropylene meshes (Group PP, n=20) and polypropylene meshes coated with a layer of poli (2-hydroxyethyl methacrylate)-PolyHEMA (Group PH, n=20) were implanted on the abdominal wall of Wistar female rats. Ten animals from each group were submitted to euthanasia at 15 and 30 days of the postoperative period. RESULTS: The animals from the group PP presented visceral adhesions on the mesh surface, which was not observed in the ones from group PH. At the histopathological examination foreign body response was observed in both groups, whilst there was a greater intensity of inflammatory response in group PH on both moments. CONCLUSION: The poli (2-hydroxyethyl methacrylate) polyHEMA hydrogel associated to polypropylene mesh reduces visceral adhesion formation in rats, although it may be associated to greater inflammatory reaction.

Evaluation of peritoneal adhesions formation and tissue response to polypropylene - poli (2-hydroxyethyl methacrylate)-(polyHEMA) implant on rats' abdominal wall / Avaliação da formação de aderências peritoneais e da resposta tecidual ao implante de poli (2-hidroxietil dimetacrilato)-(poliHEMA) na parede abdominal de ratos

PURPOSE: To verify if the composit poli (2-hydroxyethyl methacrylate)-PolyHEMA/polypropylene mesh implanted in the female rat's abdominal wall could be suitable for the prevention of peritoneal adhesions, and for the evaluation of the tecidual response produced by this biomaterial. METHODS: Polypropylene meshes (Group PP, n=20) and polypropylene meshes coated with a layer of poli (2-hydroxyethyl methacrylate)-PolyHEMA (Group PH, n=20) were implanted on the abdominal wall of Wistar female rats. Ten animals from each group were submitted to euthanasia at 15 and 30 days of the postoperative period. RESULTS: The animals from the group PP presented visceral adhesions on the mesh surface, which was not observed in the ones from group PH. At the histopathological examination foreign body response was observed in both groups, whilst there was a greater intensity of inflammatory response in group PH on both moments. CONCLUSION: The poli (2-hydroxyethyl methacrylate) polyHEMA hydrogel associated to polypropylene mesh reduces visceral adhesion formation in rats, although it may be associated to greater inflammatory reaction.

OBJETIVO: Verificar se compósito poli 2-hidroxietil dimetacrilato (PoliHEMA) / tela de polipropileno implantado na parede abdominal de ratas seria adequado para prevenção de aderências peritoneais e avaliar a resposta tecidual desencadeada por este biomaterial. MÉTODOS: Foram implantadas telas de polipropileno - Grupo PP (n=20) e telas de polipropileno revestidas por uma camada de poli 2 (hidroxietil dimetacrilato)-PolyHEMA - Grupo PH (n=20) na parede abdominal de ratas da linhagem Wistar. Dez animais de cada grupo foram submetidos à eutanásia aos 15 e 30 dias de pós-operatório. RESULTADOS: Os animais do grupo PP apresentaram aderências viscerais na superfície da tela, o que não foi observado nos do grupo PH. Observou-se no exame histopatológico resposta tipo corpo estranho nos dois grupos sendo que no grupo PH houve maior intensidade de resposta inflamatória nos dois momentos. CONCLUSÃO: O hidrogel de poliHEMA quando associado à tela de polipropileno reduz a formação de aderências viscerais em ratos, embora possa estar associado à reação inflamatória mais intensa.

Mechanical and morphological evaluation of osteochondral implants in dogs.

The mechanical behavior of osteochondral defects was evaluated in this study with the intention of developing alternative procedures. Cylindrical pins (5.00 mm in diameter and in height) made of pHEMA hydrogel covered ultra-high molecular weight polyethylene (UHMWPE) or beta-tricalcium phosphate (beta-TCP) matrix were used. Ostoechondral defects were caused in the knees of adult dogs and the evaluation was carried out after a 9-month follow-up period. The mechanical behavior of the implants was evaluated by means of an indentation creep test that showed that the UHMWPE matrix maintained its viscoelastic behavior even after follow-up time, while the beta-TCP matrix osteochondral implants presented significant alterations. It is believed that the beta-TCP osteochondral implants were unable to withstand the load applied, causing an increase of complacency when compared to the UHMWPE osteochondral implants. Based on micro and macroscopic analysis, no significant wear was observed in either of the osteochondral implants when compared to the controls. However, morphological alterations, with fragmentation indices in the patella, were observed either due to friction with the hydrogel in the first postoperative months or due to forming of a dense conjunctive tissue. This wear mechanism caused on the counterface of the implant (patella) was observed, notwithstanding the osteochondral implant studied.

Reconstrucción mandibular a medida con prótesis HTR-PMI con esqueleto de titanio / Patient matched mandibular reconstruction with HTR-PMI prosthesis with titanium framework

La prótesis HTR-PMI (hard tissue replacement - patient matched implant) es una prótesis reconstructiva compuesta por una combinación de materiales: un polímero de polimetilmetacrilato y polihidroxietilmetacrilato, no reabsorbible, biocompatible, aloplástico, indicado para la reparación de defectos esqueletales. El objetivo de este trabajo es presentar un caso clínico de reconstrucción mandibular post-osteomielitis de injerto libre de cresta ilíaca, por resección de un ameloblastoma invasivo, con un seguimiento de 7 años. El uso de este tipo de prótesis ofrece una alternativa más para la reconstrucción de grandes defectos.(AU)

Reconstrucción mandibular a medida con prótesis HTR-PMI con esqueleto de titanio / Patient matched mandibular reconstruction with HTR-PMI prosthesis with titanium framework

La prótesis HTR-PMI (hard tissue replacement - patient matched implant) es una prótesis reconstructiva compuesta por una combinación de materiales: un polímero de polimetilmetacrilato y polihidroxietilmetacrilato, no reabsorbible, biocompatible, aloplástico, indicado para la reparación de defectos esqueletales. El objetivo de este trabajo es presentar un caso clínico de reconstrucción mandibular post-osteomielitis de injerto libre de cresta ilíaca, por resección de un ameloblastoma invasivo, con un seguimiento de 7 años. El uso de este tipo de prótesis ofrece una alternativa más para la reconstrucción de grandes defectos.

Histological approaches for high-quality imaging of zooplanktonic organisms.

The investigation of the internal organization of zooplankton communities provides important information on the plankton biology with special interest for the study of ecological processes. Zooplanktoners can play a structural function as indicators for ecosystem health or stress, but their study using histological techniques is still limited. Here we report that the internal structure of zooplanktonic organisms can be facilely observed by a histological approach that combines optimal fixation and processing with a plastic resin (glycol methacrylate) embedding, resulting in increased tissue resolution. Using copepods, organisms that can dominate zooplankton assemblages, as models, collected from a tropical ecosystem (Paraibuna river, Brazil), we showed fine histological details of their muscular, nervous and digestive systems, structure of appendages and cell features. Critical advantages of this approach are that it permits optimal preservation and adequate handling of the organisms (embedded in agar after fixation) for further histological processing and investigation. This is important because it prevents both mechanically induced artifacts and loss of these diminutive organisms during the different steps of processing. Moreover, embedding in plastic resin showed a superior imaging of copepod internal structures compared to paraffin embedding. The use of glycol methacrylate is advantageous over paraffin/paraplast embedding by avoiding heat damage, tissue retraction and allowing faster embedding procedure and better tissue resolution. The value of histological approaches in enabling high-quality imaging of the internal structure of copepods is particularly important because these organisms can be used as indicators of environmental changes.

Mechanical behaviour and biocompatibility of poly(1-vinyl-2-pyrrolidinone)-gelatin IPN hydrogels.

IPN hydrogels based on poly(1-vinyl-2-pyrrolidinone) and gelatin were obtained by casting of aqueous solution using potassium persulphate and glutaraldehyde as respective crosslinking agents. Studies of swelling and mechanical behaviour showed that the samples of different composition can incorporate high content of water and still exhibit high compression strength. The composition has influence at the global crosslinking density what affects the mechanical performance. In vitro biocompatibility and hemocompatibility were also investigated. The materials do not interfere on the cellular functions and neither induce platelet adhesion. From this preliminary evaluation, it is possible to conclude that these hydrogels have potential for applications in the biomedical field.

Compómero: ¿vidrio ionomérico modificado con resina o resina modificada con vidrio ionomérico?: revisión de la literatura / Compomer: resin-modified glass ionomer or glass ionomer-modified composite resin?

Quizás ningún otro material ha experimentado tantas modificaciones desde su presentación como el vidrio ionomérico. Este cemento ha presentado modificaciones no sólo en su composición y estructura original, sino también en sus indicaiciones y sus aplicaciones clínicas, lo que ha traído como consecuencia confusión cuando se habla de vidrio ionomérico, compómero o de cualquiera otra modificación realizada a dicho material. El cemento de vidrio ionomérico es un cemento de reacción ácido-base, siendo el ácido un homopolímero o copolímero de ácidos alquenoicos. El componente básico es un aluminio silicato de vidrio que contiene flúor. La introducción de las versiones modificadas con resina representan un intento más reciente de obtener algunas mejoras sobre las desventajas de los vidrios ionoméricos convencionales. La modificación implica grupos acrilatos en la parte poliácida del cemento convencional. La reacción de establecimiento ácido-base del cemento de vidrio ionomérico es suplementada por una reacción de polimerización de la resina de los monómeros como el HEMA y el bis-GMA o de cadenas sobre la molécula de poliácidos iniciada por la luz visible. El primer compómero comercialmente disponible estaba combinado con un imprimador de autograbado, que contenía un promotor de adhesión basado en la acetona con un componente activo PENTA (ácido ésterdipentaericitol pentacrilato fosfórico) y monómeros dimetacrilatos elastoméricos e iniciadores. El contenido restaurativo polimerizable ácido y otros monómeros como UDMA y resina TCB (un biéster de 2 HEMA y ácido tetracarboxílico butano) y vidrio de sodiofluorurosilicato de aluminio estroncio. En consecuencia, los compómeros constituyen un grupo de materiales sin relación con los vidrios ionoméricos; los compómeros no son vidrios ionoméricos, sino resinas reforzadas fotopolimerizables con algunas diferencias respecto a las resinas tradicionales. La terminología de algunas de las combinaciones de vidrio ionomérico/resina más nuevas es muy contradictoria y confusa. En esta revisión se han conseguido términos diferentes para agentes de cementación y materiales restauradores con una combinación de vidrio ionomérico y la química de la resina entre los cuales se incluye al compómero

Devices for use as an artificial articular surface in joint prostheses or in the repair of osteochondral defects.

The covering of ultra high molecular weight polyethylene (UHMWPE) and calcium hydroxyapatite (HA)/tricalcium phosphate (TCP) porous solid substrate with polyHEMA hydrogel has been studied aiming at the development of devices to be used as artificial articular surfaces in joint prosthesis or osteochondral repair grafts. Commercial porous UHMWPE was used. Ceramic porous substrate was prepared by load compaction of an HA and TCP powder mixture obtained by aqueous precipitation technique. Two different compaction loads and grain size distribution was used. Polymer particles were added to the powder mixture in order to increase the substrate porosity after the sintering process. The porous substrate was covered with polyHEMA hydrogel by in situ polymerization. Morphological analysis (SEM) showed that a hydrogel layer formed in the porous solid top surface was fixed to the substrate by mechanical interlocking because the porous surface was filled by the hydrogel. After hydrogel covering, the resultant devices showed a decrease in the compressive elastic modulus that was influenced by the porous substrate material.

[Alloplastic grafts in osseous reconstruction. Clinical experience with HTR]. / Injertos aloplásticos en la reconstitución ósea. Experiencia clínica con HTR.

The present report reviews the clinical experience of the authors, with a new material in haloplastic grafts; the HTR; with the following purposes: Remain and or increase alveolar ridges. Close-up of congenital clefts.

[Maxillofacial surgery for clefts]. / Cirugía maxilofacial en los fisurados.

This paper makes a wide review of the pathology that affects clefts, where maxillofacial surgery plays a very important role in the rehabilitation of these patients. Here we will analyse the alveolar ridge repair orthodontic and orthognathic surgery of sequelae, and the use of halogenic grafts, bone integrated, for the filling of clefts.