Development and validation of a High Performance Liquid Chromatographic method for determination of etoposide in biodegradable polymeric implants

A method using HPLC-UV was developed and validated for the determination of etoposide incorporated into polycaprolactone implants. The method was carried out in isocratic mode using a C18 column (250 x 4.6 mm; 5 µm), at 25 ºC, with acetonitrile and acetic acid 4% (70:30) as mobile phase, a flow rate of 2 mL/min, and UV detection at 285 nm. The method was linear (r² > 0.99) over the range of 5 to 65 µg/mL, precise (RSD < 5%), accurate (recovery of 98.7%), robust, selective regarding excipient of the sample, and had a quantitation limit equal to 1.76 µg/mL. The validated method can be successfully employed for routine quality control analyses.

BIOMATERIAIS: TIPOS, APLICAÇÕES E MERCADO

AbstractThe types of compounds used in the production of biomaterials, namely metals, ceramics, synthetic and natural polymers, as well as composite materials, are discussed in the present work, together with details of their application and evolution from biocompatible to bioactive, biodegradable, and biomimetic clinical products. The chemical structure, the three-dimensional structure, and the molecular organization of compounds frequently used in the manufacture of relevant classes of biomaterials are discussed, along with their advantages and some of their major limitations in specific clinical applications. The main chemical, physical, mechanical, and biological requirements of biomaterials categories are presented, as well as typical tissular responses to implanted biomaterials. Reasons for the recent economic growth of the biomaterials market segment are addressed, and the most successful biomaterial categories are discussed, emphasizing areas such as orthopedic and cardiovascular implants, regenerative medicine, tissue engineering, and controlled drug release devices. Finally, the need for the development of innovative and more accessible biomaterials, due to the expected increase in the number of elderly people and the growing trend of personalized medical procedures, is pointed out.

Implementation of a perioperative management protocol for patients undergoing orthopedic surgery

OBJECTIVE: To evaluate the initial results after the implementation of perioperative protocol in patients over 60 years of age undergoing surgical treatment for femur fractures.METHODS: We conducted a prospective study of patients older than 60 years who were hospitalized with femur fracture. They were operated under spinal anesthesia and analgesia by lumbar plexus blockade. Data evaluation was performed before arrival in the operating room during surgery, in the post-anesthesia recovery room and in the ward the next morning of the operation.RESULTS: 105 patients underwent various types of surgical corrections of the femur. The hospital stay ranged from three to 86 days. Fasting ranged from 9h15min to 19h30mn. Hypotension occurred in 5.7%. The duration of motor blockade ranged from 1h45min to 5h30imn. Maltodextrin feeding ranged from 50min to 3h45min and the time spent in the post-anesthetic care unit ranged from 50 minutes to 4 hours. Onset of oral intake in the ward ranged from 4hto 8h15min. The duration of anesthesia ranged from 14 to 33 hours. No patient required a urinary catheter, nor was transferred to the ICU. All patients were able to be discharged on the first postoperative day.CONCLUSION: The use of a protocol to accelerate the postoperative period may reduce the fasting time, length of hospital stay and provide faster i discharge n elderly patients with femur fractures.

Development of porous glass-fiber reinforced composite for bone implants. Evaluation of antimicrobial effect and implant fixation

Cranial bone reconstructions are necessary for correcting large skull bone defects due to trauma, tumors, infections and craniotomies. Traditional synthetic implant materials include solid or mesh titanium, various plastics and ceramics. Recently, biostable glass-fiber reinforced composites (FRC), which are based on bifunctional methacrylate resin, were introduced as novel implant solution. FRCs were originally developed and clinically used in dental applications. As a result of further in vitro and in vivo testing, these composites were also approved for clinical use in cranial surgery. To date, reconstructions of large bone defects were performed in 35 patients. This thesis is dedicated to the development of a novel FRC-based implant for cranial reconstructions. The proposed multi-component implant consists of three main parts: (i) porous FRC structure; (ii) bioactive glass granules embedded between FRC layers and (iii) a silver-polysaccharide nanocomposite coating. The porosity of the FRC structure should allow bone ingrowth. Bioactive glass as an osteopromotive material is expected to stimulate the formation of new bone. The polysaccharide coating is expected to prevent bacterial colonization of the implant. The FRC implants developed in this study are based on the porous network of randomly-oriented E-glass fibers bound together by non-resorbable photopolymerizable methacrylate resin. These structures had a total porosity of 10–70 volume %, of which > 70% were open pores. The pore sizes > 100 μm were in the biologically-relevant range (50-400 μm), which is essential for vascularization and bone ingrowth. Bone ingrowth into these structures was simulated by imbedding of porous FRC specimens in gypsum. Results of push-out tests indicated the increase in the shear strength and fracture toughness of the interface with the increase in the total porosity of FRC specimens. The osteopromotive effect of bioactive glass is based on its dissolution in the physiological environment. Here, calcium and phosphate ions, released from the glass, precipitated on the glass surface and its proximity (the FRC) and formed bone-like apatite. The biomineralization of the FRC structure, due to the bioactive glass reactions, was studied in Simulated Body Fluid (SBF) in static and dynamic conditions. An antimicrobial, non-cytotoxic polysaccharide coating, containing silver nanoparticles, was obtained through strong electrostatic interactions with the surface of FRC. In in vitro conditions the lactose-modified chitosan (chitlac) coating showed no signs of degradation within seven days of exposure to lysozyme or one day to hydrogen peroxide (H2O2). The antimicrobial efficacy of the coating was tested against Staphylococcus aureus and Pseudomonas aeruginosa. The contact-active coating had an excellent short time antimicrobial effect. The coating neither affected the initial adhesion of microorganisms to the implant surface nor the biofilm formation after 24 h and 72 h of incubation. Silver ions released to the aqueous environment led to a reduction of bacterial growth in the culture medium.

Immunization by subcutaneous implants of polyester-polyurethane sponges coupled with antigen

A new protocol is described for immunization of outbred Swiss mice. The procedure is based on subcutaneous implantation of antigen-coupled polyester-polyurethane sponges cut into disks of 10 mm in diameter vs 2 mm in thickness. Antigen coupling was performed by overnight incubation of the sponge with a solution of ovalbumin (Ova) (2 mg/ml) diluted in sodium carbonate buffer, pH 9.6. The amount of ovalbumin that was taken up by the sponge was between 71.4 to 82.5 µg. This was estimated by comparing the Ova absorbance at 280 nm in coating buffer solutions before and after incubation. To compare the efficiency of the proposed method, experimental groups immunized with the antigen in the presence of adjuvants (10 µg in Al(OH)3 or 100 µg in complete Freund's adjuvant (CFA)) were run in parallel. The data obtained after the 3rd week of immunization indicate that both cellular and humoral immune responses were achieved. These were assayed by antigen-induced footpad swelling and ELISA (specific antibodies), respectively. The levels of both immune responses elicited were similar to the responses observed in mice immunized with ovalbumin in the presence of Al(OH)3. The method might represent an advantage when immunizing with pathogenic antigens. Preliminary experiments have suggested that the antigen remains immobilized or bound to the sponge for a long period of time, since there is an increment on the cell population inside the sponges after boosting the animals. If so, the undesirable effects of immunization would be reduced.

Biomechanical and histological evaluation of hydrogel implants in articular cartilage

We evaluated the mechanical behavior of the repaired surfaces of defective articular cartilage in the intercondylar region of the rat femur after a hydrogel graft implant. The results were compared to those for the adjacent normal articular cartilage and for control surfaces where the defects remained empty. Hydrogel synthesized by blending poly(2-hydroxyethyl methacrylate) and poly(methyl methacrylate-co-acrylic acid) was implanted in male Wistar rats. The animals were divided into five groups with postoperative follow-up periods of 3, 5, 8, 12 and 16 weeks. Indentation tests were performed on the neoformed surfaces in the knee joint (with or without a hydrogel implant) and on adjacent articular cartilage in order to assess the mechanical properties of the newly formed surface. Kruskal-Wallis analysis indicated that the mechanical behavior of the neoformed surfaces was significantly different from that of normal cartilage. Histological analysis of the repaired defects showed that the hydrogel implant filled the defect with no signs of inflammation as it was well anchored to the surrounding tissues, resulting in a newly formed articular surface. In the case of empty control defects, osseous tissue grew inside the defects and fibrous tissue formed on the articular surface of the defects. The repaired surface of the hydrogel implant was more compliant than normal articular cartilage throughout the 16 weeks following the operation, whereas the fibrous tissue that formed postoperatively over the empty defect was stiffer than normal articular cartilage after 5 weeks. This stiffness started to decrease 16 weeks after the operation, probably due to tissue degeneration. Thus, from the biomechanical and histological point of view, the hydrogel implant improved the articular surface repair.

Experimental Studies on Non-Metallic Composite Bone Implants With a Special Reference to Staphylococcal Biofilm Infection

Non-metallic implants made of bioresorbable or biostable synthetic polymers are attractive options in many surgical procedures, ranging from bioresorbable suture anchors of arthroscopic surgery to reconstructive skull implants made of biostable fiber-reinforced composites. Among other benefits, non-metallic implants produce less interference in imaging. Bioresorbable polymer implants may be true multifunctional, serving as osteoconductive scaffolds and as matrices for simultaneous delivery of bone enhancement agents. As a major advantage for loading conditions, mechanical properties of biostable fiber-reinforced composites can be matched with those of the bone. Unsolved problems of these biomaterials are related to the risk of staphylococcal biofilm infections and to the low osteoconductivity of contemporary bioresorbable composite implants. This thesis was focused on the research and development of a multifunctional implant model with enhanced osteoconductivity and low susceptibility to infection. In addition, the experimental models for assessment, diagnostics and prophylaxis of biomaterial-related infections were established. The first experiment (Study I) established an in vitro method for simultaneous evaluation of calcium phosphate and biofilm formation on bisphenol-Aglycidyldimethacrylate and triethylenglycoldimethacrylate (BisGMA-TEGDMA) thermosets with different content of bioactive glass 45S5. The second experiment (Study II) showed no significant difference in osteointegration of nanostructured and microsized polylactide-co-glycolide/β-tricalcium phosphate (PLGA /β-TCP) composites in a minipig model. The third experiment (Study III) demonstrated that positron emission tomography (PET) imaging with the novel 68Ga labelled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) CD33 related sialic-acid immunoglobulin like lectins (Siglec-9) tracer was able to detect inflammatory response to S. epidermidis and S. aureus peri-implant infections in an intraosseous polytetrafluoroethylene catheter model. In the fourth experiment (Study IV), BisGMATEGDMA thermosets coated with lactose-modified chitosan (Chitlac) and silver nanoparticles exhibited antibacterial activity against S. aureus and P. aeruginosa strains in an in vitro biofilm model and showed in vivo biocompatibility in a minipig model. In the last experiment (Study V), a selective androgen modulator (SARM) released from a poly(lactide)-co-ε-caprolactone (PLCL) polymer matrix failed to produce a dose-dependent enhancement of peri-implant osteogenesis in a bone marrow ablation model.

Evaluation of hemostatic changes using thromboelastography after crystalloid or colloid fluid administration during major orthopedic surgery

The effects of Ringer lactate, 6% hydroxyethyl starch (HES) (130/0.4) or 4% succinylated gelatin solutions on perioperative coagulability were measured by thromboelastography (TEG). Seventy-five patients (ASA I-III) who were to undergo major orthopedic procedures performed under epidural anesthesia were included in the study. Patients were randomly divided into three groups of 25 each for the administration of maintenance fluids: group RL (Ringer lactate), group HES (6% HES 130/0.4), and group JEL (4% gelofusine solution). Blood samples were obtained during the perioperative period before epidural anesthesia (t1, baseline), at the end of the surgery (t2), and 24 h after the operation (t3). TEG data, reaction time (R), coagulation time (K), angle value (α), and maximum amplitude (MA) were recorded. TEG parameters changed from normal values in all patients. In group RL, R and K times decreased compared to perioperative values while the α angle and MA increased (P < 0.05). In group HES, R and K times increased, however, the α angle and MA decreased (P < 0.05). In group JEL, R time increased (P < 0.05), but K time, α angle and MA did not change significantly. In the present study, RL, 6% HES (130/0.4) and 4% JEL solutions caused changes in the coagulation system of all patients as measured by TEG, but these changes remained within normal limits.

Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

Reconstruction of cranial bone defects with fiber-reinforced composite–bioactive glass implants

A cranial bone defect may result after an operative treatment of trauma, infection, vascular insult, or tumor. New biomaterials for cranial bone defect reconstructions are needed for example to mimic the biomechanical properties and structure of cranial bone. A novel glass fiber-reinforced composite implant with bioactive glass particulates (FRC–BG, fiber-reinforced composite–bioactive glass) has osteointegrative potential in a preclinical setting. The aim of the first and second study was to investigate the functionality of a FRC–BG implant in the reconstruction of cranial bone defects. During the years 2007–2014, a prospective clinical trial was conducted in two tertiary level academic institutions (Turku University Hospital and Oulu University Hospital) to evaluate the treatment outcome in 35 patients that underwent a FRC–BG cranioplasty. The treatment outcome was good both in adult and pediatric patients. A number of conventional complications related to cranioplasty were observed. In the third study, a retrospective outcome evaluation of 100 cranioplasty procedures performed in Turku University Hospital between years 2002–2012 was conducted. The experimental fourth study was conducted to test the load-bearing capacity and fracture behavior of FRC–BG implants under static loading. The interconnective bars in the implant structure markedly increased the load-bearing capacity of the implant. A loading test did not demonstrate any protrusions of glass fibers or fiber cut. The fracture type was buckling and delamination. In this study, a postoperative complication requiring a reoperation or removal of the cranioplasty material was observed in one out of five cranioplasty patients. The treatment outcomes of cranioplasty performed with different synthetic materials did not show significant difference when compared with autograft. The FRC–BG implant was demonstrated to be safe and biocompatible biomaterial for large cranial bone defect reconstructions in adult and pediatric patients.

La survie implantaire suite à une réhabilitation par mise en charge immédiate d’une prothèse totale mandibulaire reliée à deux implants non jumelés : une étude pilote expérimentale

Problématique : Les connaissances théoriques et pratiques au sujet de la mise en charge immédiate d’implants non jumelés chez les édentés sont limitées. Objectifs : Cette étude avait pour but de : (1) déterminer le taux de survie implantaire de 2 implants non jumelés supportant une prothèse totale mandibulaire suite à une mise en charge immédiate, (2) évaluer les changements des niveaux osseux et de stabilité implantaire survenus sur ces 2 implants durant une période de 4 mois et les comparer à un implant témoin, et (3) décrire les complications cliniques associées à ce mode de mise en charge. Méthodologie : Chez 18 individus édentés (âge moyen de 62±7 ans), cette étude de phase I avec un design pré/post a évalué les résultats cliniques suivant la mise en charge immédiate (<48 heures) de 2 implants non jumelés par une prothèse totale mandibulaire. À l’aide de radiographies périapicales, de sondages osseux et d’analyses de la fréquence en résonnance, les niveaux osseux péri-implantaires (en mm) et les niveaux de stabilité implantairte (en ISQ) de ces 2 implants insérés dans la région parasymphysaire ont été évalués à la chirurgie (T0) et au suivi de 4 mois (T1). Un implant non submergé et sans mise en charge inséré dans la région de la symphyse mandibulaire a été utilisé comme témoin. Les données ont été analysées avec des modèles mixtes linéaires, la méthode de Tukey ajustée, l’analyse de variance de Friedman et des tests de rang signés de Wilcoxon. Résultats : De T0 à T1, 3 implants mis en charge immédiatement ont échoué chez 2 patients. Le taux de survie implantaire obtenu était donc de 91,7% (33/36) et, par patient, de 88,9% (16/18). Aucun implant témoin n’a échoué. Les changements osseux documentés radiologiquement et par sondage autour des implants mis en charge immédiatement étaient, respectivement, de -0,2 ± 0,3 mm et de -0,5 ± 0,6 mm. Les pertes d’os de support implantaire n’ont pas été démontrées statistiquement différentes entre les implants avec mise en charge immédiate et les témoins. Les niveaux moyens de stabilité implantaire ont augmenté de 5 ISQ indépendamment de la mise en charge. Les niveaux moyens d’ISQ n’ont pas été démontrés statistiquement différents entre les implants avec mise en charge immédiate et les témoins à T0 ou T1. Cinq des 18 patients n’ont expérimenté aucune complication clinique, alors que 9 en ont eu au moins deux. Hormis les échecs implantaires, aucune de ces complications n’a entraîné de changements au protocole. Conclusion : Les résultats à court terme suggèrent que : (1) le taux de survie implantaire suite au protocole immédiat est similaire à ceux rapportés lors d’un protocole de mise en charge conventionnel (2) les changements d’os de support implantaire et de stabilité ne sont pas différents comparativement à ceux d’un implant témoin, (3) un niveau élevé d’expérience clinique et chirurgicale est requis pour effectuer les procédures et pour gérer les complications associées. Ces résultats préliminaires devraient être confirmés dans une étude clinique de phase II.

Les attentes, la satisfaction et la qualité de vie des édentés suite à une réhabilitation par mise en charge immédiate d'une prothèse totale reliée à deux implants non jumelés : une étude pilote expérimentale

Problématique : La majorité des études publiées sur la réhabilitation par mise en charge immédiate de deux implants non jumelés avec une prothèse totale mandibulaire de recouvrement n’ont rapporté que des mesures cliniques objectives et très peu ont évalué les mesures centrées sur le patient, et ce, avec des erreurs de mesure. Aucune étude n’a évalué les attentes des patients vis-à-vis d'un tel protocole. Objectifs : Évaluer les attentes, le niveau de satisfaction ainsi que la qualité de vie reliée à la santé bucco-dentaire des édentés complets suite à un protocole de mise en charge immédiate. Méthodologie : Cet essai clinique de phase 1 utilise un design pré-post afin d’évaluer les mesures centrées sur le patient. Dix-huit individus, complètement édentés et âgés en moyenne de 62,39 ± 7,65 ans, ont reçu une prothèse totale mandibulaire de recouvrement sur deux implants non jumelés suite à un protocole de mise en charge immédiate, conjointement à une prothèse totale conventionnelle maxillaire. Un instrument adapté pour mesurer leurs attentes à l’aide d’échelles visuelles analogues, le questionnaire « McGill Denture Satisfaction Instrument » ainsi que le questionnaire OHIP-20 ont été remis aux patients avant de procéder aux traitements (T0), ainsi qu’aux rendez-vous de suivi à 2 semaines (T1), 1 mois (T2) et 4 mois (T3). De plus, l’inventaire de personnalité révisé (NÉO PI-R) ainsi qu’un questionnaire sociodémographique ont été remplis par les participants. Les « change scores » ont été calculés puis des tests non paramétriques et des analyses de variances en mesures répétées suivies de comparaisons par paires ont été utilisés afin d’analyser les données recueillies. La taille d’effet a été estimée. Résultats : Les participants avaient différentes attentes par rapport à la mise en charge immédiate. Certains s’attendaient à un effet positif à court terme par rapport à leur apparence esthétique (83,3 %) et à leur vie sociale (55,7 %), alors que d’autres avaient des craintes envers leur confort (5,6 %), leur habileté à mastiquer (11,1 %) et à nettoyer leur prothèse inférieure (11,1 %). À 4 mois, le protocole de mise en charge immédiate avait rencontré la majorité des attentes des patients par rapport à l’esthétique (94.4 %), la mastication (83.3 %), la phonétique (61.1 %), le confort (94.4 %), l’hygiène (88.9 %) et leur vie sociale (88.9 %). Une amélioration statistiquement significative de la satisfaction en générale, du confort, de l’esthétique, de la stabilité de la prothèse inférieure et de l’habileté à mastiquer a été notée à 2 semaines (p<0,001). Également, les comparaisons par paires ont révélé une diminution statistiquement significative du score total de l’OHIP-20 (p < 0,001) de même que la majorité des domaines de l’OHIP (p < 0.01), sauf pour l’handicap social qui n’a diminué significativement qu’après 1 mois (p = 0.01). Ces changements (pour la satisfaction et la qualité de vie) sont restés stables au cours des suivis subséquents. Indépendamment des traits de personnalité et des variables sociodémographiques, le protocole immédiat a satisfait 94,4 % des participants et a amélioré leur qualité de vie avec une large magnitude d’effet (d = 1.9; p < 0.001). Bien que deux patients aient perdu des implants au cours du traitement, 100 % des participants étaient d’accord pour recommander cette procédure à leurs pairs. Conclusions: Le protocole de mise en charge immédiate semble satisfaire les patients quelles que soient leurs attentes. Le protocole MCI peut améliorer, à court terme, la qualité de vie des patients totalement édentés. Les résultats prometteurs de la phase 1 devraient être corroborés lors de la 2e phase de cette étude.

Tratamiento quirúrgico de las fracturas intertrocantéricas del fémur con placa tornillo dinámico convencional comparado con tornillo dinámico helicoidal

Introducción: Las fracturas intertrocantéricas han llegado a nuestros días con una mayor incidencia dado el envejecimiento de la población, con fracturas más complejas, menos estables y asociadas a osteoporosis, se estima que representan aproximadamente 1,75 millones de años de vida perdidos ajustados a discapacidad es decir 0,1% de la carga de morbilidad a nivel mundial. Existe consenso en el tratamiento quirúrgico de este tipo de fracturas, presentando una incidencia variable de fallos, principalmente cuando son inestables, entre estos el denominado “cuto ut”. La utilización de un método de fijación con placa y tornillo helicoidal (DHHS) aparentemente disminuye la incidencia de dichos fallos con respecto a otras técnicas. Metodología: Por medio de una muestra calculada en 128 de pacientes con fracturas intertrocantéricas operados con DHS y DHHS entre el 2007 y el 2012 en La Clínica San Rafael de la ciudad de Bogotá, Colombia, se realizó un análisis multivariado para determinar si existe o no diferencias significativas en los índices de fallo entre estas dos técnicas. Resultados: Los pacientes incluidos en el estudio 54 (42,1%) fueron hombres y 74 (57,8%) fueron mujeres. 75 fueron operados con DHHS y 53 con DHS; en cuanto a las comorbilidades las principales fueron Hipertensión con 40 pacientes para DHS y 30 para DHHS, para el caso de Diabetes Mellitus fueron 13 y 9 para DHS y DHHS, respectivamente; en cuanto al tipo de fractura más común la principal fue la clasificación Tronzo II con 9 pacientes para DHS y 13 para DHHS. Conclusión. Para el estudios se evidencia que para los 3 desenlaces principales evaluados, 1. El porcentaje de re intervención (p=0,282), 2. La supervivencia en el primer año (p=0,499) y 3. El desempeño funcional con la escala de Oxford (p=0,06); no hubo diferencias estadísticamente significativas entre los grupos.

The influence of parents' speech on the development of spoken language in German-speaking children with cochlear implants. 'La influencia del habla de los padres en el desarrollo del lenguaje en niños germanohablantes con implante coclear'.

Resumen en español

The influence of cochlear implants on behaviour problems in deaf children

Resumen tomado de la publicaci??n