A comprehensive evaluation of microchips to measure temperature in dairy calves.

Elevated temperature is often an indicator of an immune response and used in the diagnosis of illness in dairy calves; however, measuring rectal temperature is labor intensive and often not measured daily on the farm. The objective of this study was to measure body temperature using a microchip and determine an appropriate implant site that would passively read body temperature in dairy calves. First, the precision of the temperature microchips and the rectal thermometer were tested ex vivo. Then, Holstein bull calves (n = 12) at 14 ± 12 d (mean ± SD) of age were implanted with microchips subcutaneously by the scutulum of the ear, subcutaneously in the upper scapula (SCAP), and intramuscularly in the trapezius muscle of the neck. One week after implantation, a temperature reading was taken for every microchip implant site using a radiofrequency ID (RFID) reader, as well as rectally and in the tympanic membrane using a digital thermometer every 60 min for 24 h in each calf (hereafter, the hourly study). Additionally, microchip readings and rectal temperatures were taken daily at 0800 h from 8 wk of age (n = 9; 57 ± 12 d of age) until 2 wk postweaning for a subset of the bull calves used in the hourly study (hereafter, the daily study). In the ex vivo trial, the microchip readings were very highly correlated with the rectal thermometer (r = 0.96), and the average coefficient of variation between microchip readings was very low (0.12 ± 0.03%). The relationships between the microchip readings within ear, SCAP, and neck and rectal and tympanic temperatures were analyzed using Pearson correlations and Bland-Altman plots. The ear and neck readings were strongly correlated for the hourly study [individual animal correlation; median (Q1, Q3), r = 0.78 (0.73, 0.84)] and for the daily study [r = 0.79 (0.73, 0.89)] across calves. However, rectal temperature was not significantly correlated with ear, SCAP, neck, or tympanic temperature for the daily and hourly studies. Results suggest that temperature microchips measure temperature appropriately, but temperature is dependent upon the implant site in calves, and temperature measured at ear, SCAP, and neck implant sites cannot be used to estimate rectal temperature. Future research should determine thresholds for fever that are specific to implant sites in calves.

Biological response to an experimental implant for tibial tuberosity advancement in dogs: A pre-clinical study.

In this study, we propose a novel bioresorbable bioactive implant for tibial tuberosity advancement (TTA). The implant consists of a gradually resorbing load-bearing shell which encompasses rapidly resorbing small casings loaded with silica-based bioactive glass (BG) particulates which promote bone formation and reduce the risk of infection. The shell and the casings are manufactured by 3D printing from two medical grade bioresorbable polymers (a polyglycolide/lactide based and a polydioxanone based) that have different degradation rates. The casings are expected to resorb within days after surgery to expose the BG particulates while the shell would retain the load-bearing properties of the implant for the time required by bone healing. Unlike the currently used metallic devices, the novel implant is resorbed and excreted from the body once its purpose is fulfilled. This study presents a logical progression from the in vitro characterisation of the materials and implants to the in vivo investigation of the experimental implants. This included mechanical testing of the materials, finite element analysis of a preliminary design of the novel TTA implant, assessment of the degradation behaviour of the polymers and the ion exchange of BG in simulated body fluid, and investigation of the biological response to the novel implants after implantation in rabbits. The osteointegration of the novel implants was comparable to the osteointegration of Ti6Al4V implants in the control group; the biological efficacy and safety were confirmed. The biological response was in line with the expectations. The proof of concept for the novel TTA implants was demonstrated.

Comparación de la reacción inflamatoria inducida por implantes faciales de silicona y politetrafluoroetileno. Estudio en conejos / Comparison of the inflammatory reaction induced by facial implants os silicone and polytetrafluoroethylene. Study in rabbits

Introducción y Objetivo: Existen diferentes tipos de injertos autólogos y materiales aloplásticos para el tratamiento de las diversas deformidades faciales. El politetrafluoroetileno (PTFE) tiene varias ventajas debido a su propiedad hidrofóbica, que induce menor reacción inflamatoria. Presentamos un estudio que evalúa y compara la reacción inflamatoria inducida por los implantes faciales de silicona y de PTFE. Material y Método: Colocamos fragmentos de implantes de silicona y de PTFE en orejas de conejos mediante incisión y disección de un bolsillo subcutáneo. Realizamos análisis histológico a las 8 semanas: tinción de las muestras con hematoxilina / eosina y calificación del grado de reacción inflamatoria crónica, presencia de neutrófilos, linfocitos, eosinófilos, neoangiogénesis, fibroblastos y edema, presencia o no de hemorragia y valoración de la cicatriz. Hicimos la recolección de muestras para análisis microbiológico y evaluación de la presencia de hematoma y absceso en el momento del sacrificio. Resultados: La prevalencia de abscesos en el sacrificio, el hematoma y el edema durante las primeras semanas, fueron significativamente menores (p <0.05) en el grupo de PTFE. Conclusiones: El PTFE indujo reacción inflamatoria crónica al igual que la silicona, pero con menos absceso, edema y formación de hematomas

Background and Objective: The treatment for many facial deformities uses many kinds of autologous grafts or alloplastic materials. Polytetrafluoroethylene (PTFE) has several advantages due to its hydrophobic properties, inducing less inflammatory reaction. Our study evaluates and compares the inflammatory reaction induced by silicone and PTFE stripes. Methods: Fragments of silicone and PTFE implants were placed in rabbits ears using an incision and a subcutaneous gap. The histological analysis was made 8 weeks later. The samples were stained with hematoxylin/eosin and classified as chronic inflammatory reaction graduation, the presence of neutrophils, lymphocytes, eosinophils, neoangiogenesis, fibroblasts, edema and presence of bleeding and scar. Samples to microbiological analysis and evaluation of bruise and abs- cess were collected at the moment of sacrifice. Results: Prevalence of abscess at sacrifice and hematoma during the first weeks were significantly higher (p>0.05) in the silicon group. Conclusions: PTFE induced as much inflammatory reaction as the silicon but with less abscess and hematoma formation

Characterization of the torsional structural properties of feline femurs and surrogate bone models for mechanical testing of orthopedic implants.

OBJECTIVE: To characterize the torsional structural properties of the feline femur and design a bone model surrogate for mechanical testing of feline orthopedic implants. STUDY DESIGN: Experimental. SAMPLE POPULATION: Paired feline femurs (n = 30) and bone models (8 materials, n = 4/group). METHODS: Femurs were cyclically tested nondestructively in torsion and then loaded to failure. A generic femoral model was then designed from native femur dimensions and tested similarly by using 1 of 8 materials that were 3-dimensionally printed or machined. Outcome measures consisting of torsional compliance, angular deformation (AD), and torque to failure were compared by using Student's t test (P < .05). Failure modes are reported as descriptive statistics. RESULTS: Torsional compliance (1.6 ± 0.3°/Nm, 2.0 ± 0.1°/Nm), AD (3.1 ± 0.6°, 3.8 ± 0.2°) and torque to failure (7.8 ±1.2 Nm, 8.1 ± 1.3 Nm) did not differ between feline femurs and short-fiber epoxy (SFE) models. Conversely, most printed materials displayed excessive TC and failed by plastic deformation (AD > 15-fold that of native femurs) rather than by fracture. Feline bone and SFE both failed by spiral fractures. CONCLUSION: None of the outcome measures differed between the 4th generation SFE model and cadaveric femurs, but differences were identified between feline bone and printed materials. CLINICAL IMPACT: Machined SFE can be used to create a surrogate bone model with torsional structural properties similar to those of feline femurs. In contrast, common printable materials appear unsuitable to produce a realistic feline bone surrogate.

Effect of implant placement depth on the peri-implant bone defect configura-tions in ligature-induced peri-implantitis: An experimental study in dogs

Background: The subcrestal placement of implant platform has been considered a key factor in the preservation of crestal bone, but the influence of implant placement depth on bone remodeling combined with peri-implantitis is not fully understood. The aim of this study was to assess the effect of the crestal or subcrestal placement of implants on peri-implant bone defects of ligature-induced peri-implantitis in dogs. Material and Methods: Eight weeks after tooth extraction in six beagle dogs, two different types of implants (A: OsseoSpeed(TM), Astra, Mölndal, Sweden; B: Integra-CP(TM), Bicon, Boston, USA) were placed at either crestal or subcrestal (-1.5 mm) positions on one side of the mandible. Ligature-induced peri-implantitis was initiated four weeks after the installation of the healing abutment connections. After 12 weeks, tissue biopsies were processed for histological analyses. Results: Supra-alveolar bone loss combined with a shallow infrabony defect was observed in crestal level implants while deep and wide infrabony defects were present in subcrestal level groups. Subcrestal groups showed significantly greater ridge loss, depths and widths of infrabony defects when compared to crestal groups (P <0.001). Conclusions: Within the limitations of the animal study, it can be stated that the implants at subcrestal position displayed greater infra-osseous defect than implants at crestal position under an experimental ligature-induced peri-implantitis (AU)

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Surgical implantation of temperature-sensitive transmitters and data-loggers to record body temperature in koalas (Phascolarctos cinereus).

BACKGROUND: Under predicted climate change scenarios, koala distribution in Australia is expected to be adversely affected. Recent studies have attempted to identify suitable habitat, based on models of bioclimatic regions, but to more accurately reflect the thermal tolerance and behavioural adaptations of the various regional populations, the koala's response to periods of heat stress will need to be investigated at the individual animal level. OBJECTIVE: To explore the safety and suitability of temperature-sensitive intra-abdominal implants for monitoring core body temperature in the koala. METHODS: A temperature-sensitive radio transmitter and thermal iButton data-logger, waxed together as a package, were surgically implanted into the abdominal cavity of four captive koalas. In one animal the implant was tethered and in the other three, it was left free-floating. RESULTS: After 3 months, the implants were removed and all four koalas recovered without complications. The tethering of the package in the one koala resulted in minor inflammation and adhesion, so this practice was subsequently abandoned. The free-floating deployments were complication-free and revealed a diurnal body temperature rhythm, with daily ranges of 0.4-2.8°C. The minimum recorded body temperature was 34.2°C and the maximum was 37.7°C. The difference in the readings obtained from the transmitters and iButtons never exceeded 0.3°C. CONCLUSIONS: The suitability of the surgical approach was confirmed, from both the animal welfare and data collection points of view.

Well-defined and biocompatible hydrogels with toughening and reversible photoresponsive properties.

In the present study, novel hydrogels with extremely high strength, reversible photoresponsive and excellent biocompatible properties were prepared. The functional hydrogels were synthesized from a well-defined poly (ethylene glycol) polymer with spiropyran groups at a given position (PEG-SP) via a Cu(i)-catalyst Azide-Alkyne Cycloaddition (CuAAC) reaction. The molecular structures of the sequential intermediates for PEG-SP hydrogel preparation were verified by (1)HNMR and FT-IR. The mechanical property, swelling ratio, compression strength, surface hydrophilicity, and biocompatibility of the resulting hydrogel were characterized. Since spiropyran is pivotal to the switch in hydrophilicity on the hydrogel surface, the swelling ratio of PEG-SP hydrogel under Vis irradiation has a major decrease (155%). Before and after UV light irradiation, the contact angle of the hydrogel has a change of 13.8°. The photoresponsive property of this hydrogel was thus demonstrated, and such a property was also shown to be reversible. The well-defined PEG-SP hydrogel can also sustain a compressive stress of 49.8 MPa without any macro- or micro-damage, indicating its outstanding mechanical performance. Furthermore, it possessed excellent biocompatibility as demonstrated by its performance in an in vivo porcine subcutaneous implantation environment. No inflammation was observed and it got along well with the adjacent tissue. The above features indicate that PEG-SP hydrogels are promising as an implantable matrix for potential applications in biomaterial.

Ti nanorod arrays with a medium density significantly promote osteogenesis and osteointegration.

Ti implants are good candidates in bone repair. However, how to promote bone formation on their surface and their consequent perfect integration with the surrounding tissue is still a challenge. To overcome such challenge, we propose to form Ti nanorods on their surface to promote the new bone formation around the implants. Here Ti nanorod arrays (TNrs) with different densities were produced on pure Ti surfaces using an anodizing method. The influence of TNr density on the protein adsorption as well as on the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 pre-osteoblastic cells were assessed. The TNrs were also implanted into the bone defects in rabbits to test their application in promoting bone formation and osteointegration at the implant-bone interface. TNrs with the medium density were found to show the best capability in promoting the protein adsorption from surrounding medium, which in turn efficiently enhanced osteogenic differentiation in vitro and osteointegration in vivo. Our work suggests that growing TNrs with a medium density on the surface of traditional Ti implants is an efficient and facile method for promoting bone formation and osteointegration in bone repair.

Nueva prótesis de maleovestibulopexia. Diseño y análisis experimental en un modelo computarizado 3D basado en elementos finitos / Design and experimental analysis of a new malleovestibulopexy prosthesis using a finite element model of the human middle ear

Introducción: Existen numerosas prótesis diseñadas con el fin de sustituir elementos osiculares en el oído medio. En este trabajo presentamos el diseño de una nueva prótesis de sustitución osicular total anclada en el mango del martillo y analizamos su comportamiento mecanoacústico teórico. Métodos: Para el diseño de la prótesis hemos utilizado el método de los elementos finitos (FEM) basándonos en un modelo computarizado 3D dinámico del oído medio humano, analizando su comportamiento mecánico. Resultados: La prótesis resultante presenta un comportamiento mecanoacústico teórico superponible al del oído humano sano. Posee, además, otras ventajas biológicas como son estabilidad y la facilidad de implantación. Conclusiones: La simulación computarizada puede ser utilizada para diseñar y optimizar las características vibroacústicas de prótesis implantables en el oído medio. Mostramos la eficiencia mecanoacústica de un nuevo diseño de prótesis de maleovestibulopexia útil en la reconstrucción de la cadena osicular (AU)

Introduction and Objective: Many designs of prostheses are available for middle ear surgery. In this study we propose a design for a new prosthesis, which optimises mechanical performance in the human middle ear and improves some deficiencies in the prostheses currently available. Our objective was to design and assess the theoretical acoustic-mechanical behaviour of this new total ossicular replacement prosthesis. Methods: The design of this new prosthesis was based on an animal model (an iguana). For the modelling and mechanical analysis of the new prosthesis, we used a dynamic 3D computer model of the human middle ear, based on the finite elements method (FEM). Results: The new malleovestibulopexy prosthesis design demonstrates an acoustical-mechanical performance similar to that of the healthy human middle ear. This new design also has additional advantages, such as ease of implantation and stability in the middle ear. Conclusions: This study shows that computer simulation can be used to design and optimise the vibroacoustic characteristics of middle ear implants and demonstrates the effectiveness of a new malleovestibulopexy prosthesis in reconstructing the ossicular chain (AU)

Healing and expression of growth factors (TGF-ß and PDGF) in canine radial ostectomy gap containing platelet-rich plasma.

OBJECTIVES: To evaluate bone healing in an experimental radial ostectomy in dogs treated with autologous platelet-rich plasma (PRP), through histological, densitometric, radiographic studies, as well as expression of growth factors in the ostectomy gap. METHODS: Twenty-one dogs were randomly divided into either a control or a PRP group. All underwent unilateral ostectomy of the radius to generate a gap of 2.0 mm, that was stabilized with external skeletal fixation. The ostectomy gap was either filled with PRP or left empty as a control. The radiographic and densitometric studies were performed after surgery, then at intervals until 60 days during the post-surgery period. Histological and immunohistochemical evaluations were performed at seven or 60 days post-surgery. Analyses were performed using a statistical analysis system, and the level of significance was set at p <0.05. RESULTS: The median radiographic healing score in the PRP group increased significantly between day 0 and day 60. Furthermore, at 60 days, the median healing score and the proportion of healed ostectomies in the control group (score 1; 1/6 healed) and the PRP group (score 5; 4/5 healed) were significantly different. There were differences between groups in radiographic and densitometric values at days 45 and 60. The histological evaluation showed advanced bone healing at 60 days in the PRP group and signs of delayed union in the control group. CLINICAL RELEVANCE: Platelet-rich plasma can be used as an adjuvant therapy because it may promote better bone healing of a radial ostectomy treated with external skeletal fixation in dogs.

Integración tendinosa de plastias autólogas en túneles de diferente calibre. Estudio experimental en ovejas / Bone-tendon integration of autologous grafts using different diameter tunnels. An experimental study on sheep

Objetivo. Estudiar la integración de una plastia tendinosa en la reparación de un ligamento cruzado anterior (LCA) y el proceso de «ligamentización» con túneles de diferente calibre. Material y métodos. Estudiamos la integración del LCA en 41 ovejas adultas, según los siguientes grupos: grupo A: plastia tendinosa autóloga del tendón flexor superficial de la pezuña en túnel femoral y tibial de 5mm de diámetro; grupo B: en túneles de 7mm de diámetro. Sacrificio a los 3, 6 y 12 meses. Efectuamos un estudio histológico de la plastia en el túnel femoral, en el túnel tibial e intraarticular. También analizamos biomecánicamente el complejo fémur-plastia-tibia, con túneles de diferente diámetro y distintos tiempos de evolución. Resultados. En los túneles de 5mm no vimos integración directa de la plastia con el hueso. Observamos un tejido fibroso celular y vascularizado. En los túneles de 7mm tampoco observamos unión directa de la plastia con el hueso. El tejido de interfaz era un tejido fibroso con una estructura fascicular desarrollando la formación de septos y penetración de vasos. Macroscópicamente la plastia seguía recordando al tendón original. Las plastias de túnel de 7mm y con mayor tiempo de evolución necesitaban más fuerza de rotura y presentaban mayor elongación que las plastias de túneles de 5mm. Conclusión. Histológicamente, al año de evolución, el tendón no se transformó en un ligamento y no había integración de la plastia con el hueso de los túneles, independientemente del diámetro de éstos (AU)

Objective. To analyse the bone-ligament integration «ligamentization» of the tendon graft in the reconstruction of anterior cruciate ligament (ACL) performing tunnels of different diameter. Material and methods. We performed the same reconstruction procedure using an autologous tendon graft taken from the superficial tendon of the hoof in 41 adult sheep. In Group A the tibial and femoral tunnels were 5mm in diameter and in Group B they were 7mm in diameter. The sheep were sacrificed at 3, 6 and 12 months after the surgery. Histological studies were performed on the graft and the tunnels, as well as a biomechanical analysis of the tibial-femoral complex. Results. In group A we did not observe direct integration of the bone and the tendon graft or any fibres joining both structures, although there was vascularized fibrous tissue. In group B we did not observe any direct binding of the bone and the tendon graft either, although there was abundant fibrous tissue. The tendon graft showed a fascicular structure that increased over time in order to create septa for vascular penetration. Macroscopically the ACL graft had a dense appearance, which was very similar to the original tendon graft. The tendon grafts from group B and with a longer follow up period required a higher strength to produce maximum breakage than the tendon grafts from group A. Conclusion. After one year follow up, the histological study shows that the tendon graft is not transformed into a ligament, and there is no integration of the tendon graft in tunnels regardless of their diameter. Therefore, fixation techniques are essential to maintain the orientation and tension of the tendon graft (AU)

Resposta tecidual a implantes de discos de poliuretana de mamona nas formas pré-moldada ou biomassa moldada / Tissue reaction to premolded or molded biomass disks of polyurethanes containing castor oil

O trabalho teve por objetivo avaliar a resposta tecidual à implantação de discos de poliuretana derivada do óleo de mamona confeccionados de duas formas distintas, na forma pré-moldada fornecida pela indústria e em biomassa moldada no momento da aplicação, de forma a observar se haveria algum tipo de reação local tardia associada à possível continuidade do processo de endurecimento final do biomaterial. Foram utilizados 20 ratos, linhagem Wistar, fêmeas, com peso de 300-350g, nos quais foi inserido o disco pré-moldado no tecido subcutâneo do flanco direito e o de biomassa moldada no flanco esquerdo. Ambos os discos tinham 0,8cm de diâmetro por 0,5cm de espessura. Para o procedimento histológico, cinco ratos foram submetidos à eutanásia aos 3, 7, 15 e 30 dias de pós-cirúrgico. Os implantes e tecidos circundantes foram colhidos, processados e corados pela técnica de hematoxilina-eosina. Foi observada inicialmente uma reação inflamatória moderada, composta especialmente por células polimorfonucleares e macrófagos. Os linfócitos variaram de ausentes a discretos. A reação inflamatória diminui de intensidade à medida que se intensificou a formação de tecido conjuntivo fibroso ao redor dos implantes, porém sem modificação dos números de macrófagos. Sendo assim, conclui-se que ambos os discos de poliuretana induzem uma reação inflamatória similar, que varia de moderada a discreta na dependência do momento de avaliação.

The aim of this study was to histologically evaluate the tissue reaction to implantation of polyurethane disks containing castor oil produced in premolded form, supplied commercially, and biomass molded at the moment of application; since a late tissue reaction may occur during the total hardening process of the biomaterial. Twenty female Wistar rats, about 3 months of age, weighing 300-350g, and polyurethane disks 0.8cm in diameter and 0.5cm in thickness were used. The premolded disk was implanted into the subcutaneous tissue at the right flank and the molded biomass disk at the left flank. Five rats each were submitted to euthanasia at 3, 7, 15 and 30 days after surgery, and the polyurethane disks and surrounding tissue were collected. The specimens were processed for HE staining and examined microscopically. A moderate inflammatory reaction was primarily composed of polymorphonuclear cells and macrophages. The lymphocytes varied from absent to discreet. The intensity of the inflammatory reaction decreased at the same time the formation of fibrous conjunctive tissue increased around the implants. However, the numbers of macrophages remained the same. In conclusion, both polyurethane disks induce the same type of inflammatory reaction that varies from slight to moderate according to evaluation time.

Evaluation of blood pressure measurement using a miniature blood pressure transmitter with jacketed external telemetry in cynomolgus monkeys.

INTRODUCTION: Current techniques used to accurately determine arterial blood pressure (BP) in conscious, unrestrained monkeys require invasive telemetry. This study evaluated the functionality of an implanted miniature telemetry blood pressure transmitter for the collection of BP measurements in conjunction with electrocardiographic measurements using a jacketed external telemetry (JET) system in conscious, unrestrained cynomolgus monkeys. METHODS: Twenty-four animals were surgically implanted with the transmitter in the right femoral artery. Local tolerability to the implant, signal quality, and variability in hemodynamic values were evaluated. On alternate weeks, animals were given single doses of positive control agents to produce hypotensive (clonidine hydrochloride) or hypertensive (L-NAME) effects. Undisturbed telemetry BP data were continuously collected for at least 24h following dosing and analyzed. RESULTS: While exhibiting remarkably high signal quality ( approximately 95% data points retained over 24h of data collection) and moderate variability across study weeks in baseline pulse height measurements (changes as small as < 0 mmHg), nine of 18 transmitters were nonfunctional by 19 weeks post-surgery, most likely due to migration of the catheter out of the artery. In animals given positive control agents, L-NAME induced a statistically significant increase (> or = + 8 mmHg) and clonidine hydrochloride induced a statistically significant decrease (-11 mmHg) in mean arterial pressures. Histological analysis revealed femoral arterial thickening near the sites of implantation. DISCUSSION: These results demonstrate the ability of the miniature BP transmitter, in conjunction with the JET system, to detect small changes in hemodynamic data continuously collected in conscious unrestrained monkeys. Future optimization of the transmitter includes the addition of a suture rib to the transmitter body and increased catheter size to prevent catheter migration out of the artery, the root cause of failed transmitters. The miniature blood pressure transmitter evaluated provides a minimally invasive technique for continuous collection of hemodynamic data in a toxicology study environment.

Análise morfométrica da carótida de suínos submetidos a angioplastia com ou sem implante de stent de cromo-cobalto / Morphometric analysis of swine carotid artery angioplasty with or without cobalt-chromium stent implantation

Contexto: A hiperplasia intimal é a reação tardia mais comum decorrente da angioplastia. O uso de stents de cromo-cobalto é bem estudado na circulação coronariana, porém não há muitos estudos que abordem o uso desses stents nas circulações carotídea e periférica. Objetivo: Analisar mediante morfometria a reação intimal presente na artéria carótida de suínos submetidos a angioplastia isoladamente e a angioplastia seguida de implante de stent de cromo-cobalto. Materiais e métodos: Em oito suínos, foi realizada angioplastia da artéria carótida comum direita e angioplastia seguida de implante de um stent de cromo-cobalto na artéria carótida comum esquerda. Após 4 semanas, os animais foram submetidos a eutanásia para a retirada de amostras de tecido arterial e preparo de lâminas histológicas. As imagens das lâminas foram digitalizadas e analisadas por programa de morfometria digital. A análise estatística foi realizada através da média e desvio padrão das áreas em cada grupo, utilizando-se o Teste t de Student. O valor de p < 0,05 foi considerado significativo. Resultados: O implante do stent provocou maior grau de hiperplasia comparado à angioplastia isolada. A diferença em resposta ao implante de stent foi estatisticamente significativa quando as áreas do lúmen, da lâmina elástica interna e da lâmina elástica externa foram comparadas entre os dois grupos. Não se observou diferença significativa quando se realizou a comparação entre as camadas médias dos dois grupos. Conclusão: O implante de stent de cromo-cobalto gerou um espessamento intimal maior do que o produzido apenas pela angioplastia, porém ele não foi suficiente para reduzir o lúmen arterial.

Background: Intimal hyperplasia is the most common delayed response to angioplasty. The use of cobalt-chromium stents is well studied in the coronary circulation; however, there are few studies on their use in the carotid and peripheral circulation. Objective: To analyze the intimal reaction in a swine carotid artery undergoing simple angioplasty and angioplasty followed by implantation of cobalt-chromium stent. Materials and methods: We carried out angioplasty in the right common carotid artery and angioplasty with cobalt-chromium stent in the left common carotid artery in eight swine. Four weeks later, all animals were sacrificed for arterial tissue sampling and preparation of histological slides. Slide images were scanned and analyzed using a digital morphometry program. Statistical analysis was performed by mean values and standard deviations of the areas in each group, using the Student's t test. A p value of < 0.05 was considered significant. Results: Angioplasty with cobalt-chromium stent implantation resulted in a higher degree of hyperplasia compared with simple angioplasty. The difference was statistically significant when the lumen area, the internal elastic lamina area, and the external elastic lamina area were compared between the two groups. No statistically significant difference was found when the media layers of both groups were compared. Conclusion: Cobalt-chromium stent implantation resulted in more intimal hyperplasia than simple angioplasty, however the stent was not enough to reduce the arterial lumen.

Comparison of two methods (left carotid artery and abdominal aorta) for surgical implantation of radiotelemetry devices in CD-1 mice.

The goal of this study was to compare two surgical methods, the left carotid (LC) and the abdominal aorta (AA), for mouse instrumentation with telemetry devices, to determine the best method for measuring cardiovascular (CV) parameters by radiotelemetry in freely moving mice. Surgery success rate, postsurgical recovery rate, clinical parameters, CV data (baseline and response to nicotine) and circadian rhythm measurements were compared between these techniques. Brains of LC-implanted mice were evaluated for potential ischaemia by direct observation of the Circle of Willis anatomy and histopathology. For this purpose, a total of 31 CD-1 male mice were instrumented with PA C20 devices (10 with LC and 21 with AA). Mortality, morbidity, physical examination, body weight (BW), water and food consumption (W/FC), mean blood pressure (MBP) and heart rate (HR) were monitored daily during the recovery period (10 days). CV baseline data were recorded continuously during two periods of four days, and finally, both LC- and AA-implanted mice received an acute subcutaneous administration of 1 mg/kg nicotine; BP and HR were recorded during 5 h after nicotine administration. Results showed that, in LC-implanted mice, 80% survived surgery and recovered well. In contrast, only 57% of mice implanted with the AA technique survived surgery and some presented lethal complications. Both techniques had similar recovery times for BW and W/FC, comparable return to normal circadian rhythm (day 6 post-surgery) and similar CV baseline values. No significant differences were observed in CV response to nicotine between both groups of implanted CD-1 mice. No histopathological changes suggestive of ischaemia were noted in the brain of mice implanted in the LC. Six out of the eight LC-implanted mice remained in good health and had good pressure signal for at least 100 days post-surgery, while most of the AA-implanted mice lost the signal pressure within 14-49 days post-surgery. In conclusion, we believe that LC implantation in mice is superior to the AA technique and is more appropriate for long-term telemetry studies, especially for smaller (transgenic) animals.

Evaluation of the efficacy of a novel electronic pain assessment device, the Pain Gauge, for measuring postoperative pain in rats.

One of the major challenges for individuals working with laboratory animals is the recognition and alleviation of pain. The Pain Gauge is marketed as a pain assessment device that measures electrodermal activity. To establish whether the Pain Gauge is effective in assessing postoperative pain in laboratory rats, preoperative and postoperative pain gauge scores ('pain scores') were obtained from 67 rats. Rats were randomly assigned to one of three experimental groups (laparotomy, craniotomy or control) and to one of four analgesic groups (meloxicam [2 mg/kg s.c.] or parecoxib [1, 5 or 20 mg/kg i.v.]). Five consecutive 'pain scores' were obtained from each animal at each of five time points (preprocedure, and at 1, 2, 3 and 4 h postoperatively). Overall there was a significant difference between 'pain scores' at different time points; mainly a decrease at 1 h postoperatively compared with the preoperative scores. There was no overall increase in postoperative 'pain scores' in the rats that were most likely to suffer from postoperative pain (rats given a lower dose of analgesic that underwent a surgical procedure) compared with rats that did not undergo a potentially painful procedure (rats in anaesthesia-only/control group). Therefore it was concluded that the Pain Gauge is ineffective in assessing postoperative pain in rats in this study.

Repair of tendon defect with dermal fibroblast engineered tendon in a porcine model.

Harvesting autologous tenocytes for tendon engineering may cause secondary tendon defect at the donor site. Dermal fibroblasts are an easily accessible cell source and do not cause major donor site defect. This study aims to explore the possibility of tendon engineering using dermal fibroblasts. A total of 45 hybrid pigs were randomly divided into three groups: experimental group (n = 15)--repair of tendon defect with a dermal fibroblast engineered tendon; control group 1 (n = 15)--repair of defect with a tenocyte engineered tendon; and control group 2 (n = 15)-repair of defect with a scaffold alone. Both autologous dermal fibroblasts and tenocytes were seeded on polyglycolic acid (PGA) unwoven fibers to form a cell-scaffold construct and cultured in vitro for 7 days before in vivo implantation to repair a defect of flexor digital superficial tendon. Specimens were harvested at weeks 6, 14, and 26 for gross, histological, and mechanical analyses. Microscopy revealed good attachment of both dermal fibroblasts and tenocytes on PGA fibers and matrix production. In vivo results showed that fibroblast and tenocyte engineered tendons were similar to each other in their gross view, histology, and tensile strength. At 6 weeks, parallel collagen alignment was observed at both ends, but not in the middle in histology, with more cellular components than natural tendons. At weeks 14 and 26, both engineered tendons exhibited histology similar to that of natural tendon. Collagens became parallel throughout the tendon structure, and PGA fibers were completely degraded. Interestingly, dermal fibroblast and tenocyte engineered tendons did not express type III collagen at 26 weeks, which remained observable in normal pig skin and control group 2 tissue using polarized microscopy, suggesting a possible phenotype change of implanted dermal fibroblasts. Furthermore, both fibroblast and tenocyte engineered tendons shared similar tensile strength, about 75% of natural tendon strength. At 6 weeks in control group 2, neo-tissue was formed only at the peripheral area by host cells. A cord-like tissue was formed at weeks 14 and 26. However, the formed tissue was histologically disorganized and mechanically weaker than both cell-engineered tendons (p < 0.05). These results suggest that dermal fibroblasts may have the potential as seed cells for tendon engineering.

Cortical bone graft and endoprosthesis in the distal radius of dogs: a biomechanical comparison of two different limb-sparing techniques.

OBJECTIVE: To compare the biomechanical properties of cortical bone and surgical steel endoprosthesis for limb-sparing surgery of the distal radius in dogs and evaluate the role of the ulna in providing stability to the reconstructed limb. STUDY DESIGN: Cadaveric biomechanical study. ANIMALS: Twelve pairs of normal canine thoracic limbs. METHODS: Paired limbs were divided into 4 groups: endoprosthesis and cortical bone graft, with and without preservation of the ulna. In each limb pair, the distal segment of the radius resected from the limb to be reconstructed with an endoprosthesis was used as the cortical bone graft in the contralateral limb. The ulna was resected en bloc with the radius and at the same level as the radial osteotomy in limbs where the ulna was not preserved. Limbs were tested in axial loading until failure. The load-deformation curve was used to acquire the biomechanical properties of each construct, which were compared using 2-way ANOVA. Failure modes were compared descriptively. RESULTS: Limbs reconstructed with the endoprosthesis had significantly greater yield load, energy at yield, and ultimate load compared with limbs reconstructed with a cortical bone graft. There were no significant differences in either energy to failure or stiffness between the 2 constructs. Preservation of the ulna did not significantly improve any of the biomechanical properties tested with either endoprosthesis or cortical bone graft constructs. The modes of failure in all 4 groups were variable and inconsistent. CONCLUSIONS: Limbs reconstructed with an endoprosthesis were biomechanically superior to limbs reconstructed with a cortical bone graft in axial loading to failure. Preservation of the ulna is not required to improve the stability in axial compression after limb-sparing surgery of the distal radius. CLINICAL RELEVANCE: The endoprosthesis may provide another option for limb-sparing surgery of the distal radius in dogs. It has potential advantages when compared with cortical bone grafts, including better biomechanical performance and resistance to implant failure in axial compression, immediate availability, and no requirement for bone banking facilities. The ulna can be resected en bloc with the radius without having a negative impact on construct stability. En bloc resection of the ulna and radius may decrease the risk of local tumor recurrence after limb-sparing surgery.

Estudio experimental sobre la viabilidad del injerto libre de epitelio urinario autólogo cultivado in vitro / Experimental study about viability of autologous free graft in vitro cultivated urinary epithelium

OBJETIVO: Con el presente trabajo pretendimos aplicar las técnicas de cultivo in vitro de queratinocitos así como los principios de la ingeniería tisular al epitelio urinario, con el fin de conseguir un tejido autólogo tridimensional apto para trasplantar, y confirmar a su vez la viabilidad del injerto libre del mismo en un modelo experimental. MATERIAL Y MÉTODOS: Se procedió a un diseño experimental en el animal de laboratorio donde se aplicaron las técnicas del cultivo celular y de la ingeniería de tejidos. Se obtuvieron muestras de mucosa vesical de conejo, las cuales fueron cultivadas in vitro, implantándose posteriormente el tejido obtenido en cada animal, estableciéndose 3 grupos, con diferentes periodos de seguimiento (7,14 y 30 días), para proceder al estudio histomorfológico de la viabilidad de dichos implantes. RESULTADOS: Se obtuvo un tejido tridimensional compuesto por una submucosa bioartificial a base de un gel de fibrina y fibroblastos, sobre la que descansan las células uroepiteliales, utilizando una malla de ácido poliglicólico, la cual facilitó la manipulación del tejido y el posterior injerto del mismo. Todos los implantes resultaron viables y se pudo comprobar como los injertos con mayor periodo de seguimiento (30 días) se encontraban mejor conformados, con múltiples capas celulares. CONCLUSIONES: Las técnicas de cultivo in vitro de queratinocitos son aplicables a otros epitelios, entre ellos el urinario. En un periodo de tiempo relativamente corto se puede obtener un tejido in vitro tridimensional apto para trasplantar. El estudio histológico puso de manifiesto que el injerto libre de epitelio urinario autólogo cultivado es totalmente viable, apuntando futuras aplicaciones clínicas

OBJETIVE: The purpose of this study is to apply the in vitro keratinocyte culture techniques and the tissue engineering principles to urothelium, to obtain a three-dimensional autologous tissue suitable for grafting. We also showed the viability of free graft cultured urothelium in an experimental model. MATERIAL AND METHODS: An animal experimental model was designed to apply the techniques of cellular culture and tissue engineering. Biopsy specimens of bladder mucosa were obtained, in vitro cultured and posteriorly implanted in each animal. We established three groups based on different follow-up periods (7, 14 and 30 days), and made a final histomorphological study to demonstrate the viability of the graft at the end of its respective follow-up period. RESULTS: A three-dimensional in vitro tissue was obtained, composed of a bio-artificial submucosa (fibrin gel and fibroblast) where the uroepithelial cells were seeding; a biodegradable polyglycolic acid mesh was used to facilitate the tissue manipulation and implantation. In the morphological study all the implants appeared viable, but the grafts with longer implantations periods were better conformed, showing a tisular structure with multiple cellular layers. CONCLUSIONS: In vitro keratinocyte culture techniques could be applied to other epithelial tissues as the urothelium. We obtained a three-dimensional in vitro tissue suitable for grafting in a relatively short time. The histological study demonstrated that free autologous urothelial graft is totally viable, opening future clinics applications

Efectos del ultrasonido externo sobre el adipocito en la liposucción / Effects of external ultrasound on fat tissue in liposuction

Se ha desarrollado un método de liposucción asistida con ultrasonido externo, aplicado directamente sobre la piel, sin embargo no existe en la literatura un estudio formal que describa los cambios provocados en las diferentes estructuras y tejidos con la aplicación de diferentes intensidades de ultrasonido externo por períodos variables. Ante la inexistencia de una guía científica para el uso del ultrasonido externo en la lipoescultura, este estudio se desarrollo para conocer sus efectos, así como los parámetros capaces de producir la destrucción selectiva de las células de grasa, facilitando su extracción por aspiración y que sean seguros para no lesionar los tejidos adyacentes. Se utilizaron diez cerdos machos de raza criolla, en los cuales se aplicó el ultrasonido externo y se observaron los cambios macroscópicos del tejido graso bajo visión directa a través de una fibra óptica; simultáneamente se tomaron biopsias a diferentes intensidades y a diferentes periodos de tiempo, quefueron analizadas histológicamente, con lo que se demostró que el ultrasonido externo no produce los fenómenos de licuefacción grasa y microcavitación. Las quemaduras producidas en la piel se presentan solo cuando el transductor se mantiene en un halo igual a su diámetro durante un minuto o más; mientras se realice un movimiento continúo del transductor que sobrepase el diámetro de éste, la aplicación del ultrasonido externo es segura hasta periodos de 20 minutos (AU)

Liposuction method assisted with external ultrasound has been developed, applied directly on the skin, however it doesn’t exist in the literature a formal report that describes the provoked changes to the different structures and tissues and the application in different intensities of external ultrasound, per variables periods. There is not any scientific guide for the use of the external ultrasound in the liposculpturing. This study tries to know the effects of this energy, as well as the parameters that are able to produce the selective destruction of the cells of fat to facilitate its extraction by aspiration and all that in a so safe way that we don’t injure the adjacent tissues. Ten creole race male pigs were used, in which the external ultrasound was applied and the macroscopic changes of the fatty low direct vision were observed through an optic fiber; we took simultaneously biopsies to different intensities and periods of time. It was demonstrated that the external ultrasound does not produce the phenomenons of fatty liquefaction and acoustic cavitation. The burns on skin are presented when the transducer stays in a halo similar to its diameter for one minute or more; while the transducer is moving on a diameter bigger than its surface, the external ultrasound application is safe until for 20 minutes (AU)