RESUMEN

Myocardial infarction (MI) leads to a severe loss of cardiomyocytes, which in mammals are replaced by scar tissue. Epicardial derived cells (EPDCs) have been reported to differentiate into cardiomyocytes during development, and proposed to have cardiomyogenic potential in the adult heart. However, mouse MI models reveal little if any contribution of EPDCs to myocardium. In contrast to adult mammals, teleosts possess a high myocardial regenerative capacity. To test if this advantage relates to the properties of their epicardium, we studied the fate of EPDCs in cryoinjured zebrafish hearts. To avoid the limitations of genetic labelling, which might trace only a subpopulation of EPDCs, we used cell transplantation to track all EPDCs during regeneration. EPDCs migrated to the injured myocardium, where they differentiated into myofibroblasts and perivascular fibroblasts. However, we did not detect any differentiation of EPDCs nor any other non-cardiomyocyte population into cardiomyocytes, even in a context of impaired cardiomyocyte proliferation. Our results support a model in which the epicardium promotes myocardial regeneration by forming a cellular scaffold, and suggests that it might induce cardiomyocyte proliferation and contribute to neoangiogenesis in a paracrine manner.

Asunto(s)

RESUMEN

Although there are almost thirty-thousand species of fish living in a great variety of habitats and utilizing vast reproductive strategies, our knowledge of morphofunctional and quantitative aspects of testis structure and spermatogenesis is still incipient for this group of vertebrates. In this review, we discuss aspects that are important to better understanding of testis structure and function, and of the development of germ cells (GC) during spermatogenesis. To achieve this, we have recently completed a number of studies presenting morphometric and functional data related to the numbers of GC and Sertoli cells (SC) per each type of spermatogenic cyst, the number of spermatogonial generations, the SC efficiency, and the magnitude of GC loss that normally occurs during spermatogenesis. We also investigated SC proliferation and the relationship of this important event to early spermatogenic cysts. The available data strongly suggest that SC proliferation in sexually mature tilapia is the primary factor responsible for the increase in testis size and for determination of the magnitude of sperm production. The influence of temperature on the duration of spermatogenesis in tilapia was also evaluated and we have used this knowledge to deplete endogenous spermatogenesis in this teleost, in order to develop an experimental system for GC transplantation. This exciting technique results in new possibilities for investigation of spermatogenesis and spermatogonial stem cell biology, creating also an entirely new and promising scenario in biotechnology-transgenic animal production and the preservation of the genetic stocks of valuable animals or endangered species.

Asunto(s)

RESUMEN

Testou-se a hipótese de o alo-transplante de bexiga devolver a capacidade estrutural e funcional desse órgão, usando-se 10 cães machos, saudáveis, submetidos à cistectomia parcial com preservação do trígono vesical. Utilizou-se o alo-transplante na reconstrução da vesícula urinária com acompanhamento dos animais durante 60 dias. Aos oito dias de pós-operatório, os cães apresentavam capacidade de contenção urinária e micção espontânea. Houve aumento gradativo do volume da vesícula urinária, alcançando, aos 60 dias, valores significativamente mais altos que os observados antes da cirurgia. Verificou-se integração tecidual com regeneração parcial na interface do transplante, caracterizada por reconstituição epitelial, proliferação fibroblástica, neoangiogênese e surgimento de fibras musculares lisas, aos 60 dias. Problemas como rejeição e obstrução uretral ocorreram em três cães. Conclui-se que o alo-transplante de bexiga em cães é viável e devolve a capacidade de repleção e as demais funções fisiológicas da vesícula urinária, ocorrendo regeneração parcial dos tecidos aos 60 dias de pós-operatório.

The hypothesis that urinary bladder allotransplant in dogs repairs the functional and structural capacity of this organ. Ten healthy male dogs were submitted to partial cystectomy, preserving the vesicle trigon. Allotransplant was used on the reconstruction of the urinary bladder and the animals were kept under observation for 60 days. On day seven after surgery, the dogs presented spontaneous capacity of contention and micturition. There was a gradual increase of the volume of the urinary bladder reaching to significantly higher values on day 60. Tissue integration with partial regeneration on the interface of the transplant, characterized by epithelial reconstitution, fibroblastic proliferation, neoangiogenesis and smooth muscular fibers appearance were observed on day 60. Problems as rejection and urethral obstruction occurred in three dogs. It is concluded that the allotransplant in dogs is viable, repairing the bladder capacity and other physiologic functions of the urinary bladder, although partial tissue regeneration is observed 60 days after operation.

Asunto(s)

RESUMEN

CASE DESCRIPTION: A 2.5-year-old spayed female Persian cat was evaluated for acute inability to close its mouth. CLINICAL FINDINGS: A wry-mouth malocclusion was evident, and the right side of the mandible was longer than the left side. The right mandibular tooth row appeared to be lowered. The lower jaw was persistently maintained in an open position. The presumptive diagnosis was open-mouth jaw locking. Diagnostic imaging with computed tomography and 3-dimensional reconstruction was performed for definitive diagnosis and to achieve a better understanding of the lesions. Imaging revealed locking of the right ramus of the mandible, which was displaced ventrolaterally, causing the coronoid process to impinge on the right zygomatic arch. TREATMENT AND OUTCOME: A bilateral partial ostectomy of the rostroventral margins of the zygomatic arches with an autogenous fat graft implantation was performed. The cat recovered without complications and by the following morning was bright, alert, and responsive and eating canned cat food comfortably. One year after surgery, the owner reported that the cat had continued to function well, was eating normally, and had not had any observed locking episodes since surgery. CLINICAL RELEVANCE: Unlike radiographic imaging, computed tomography may be used to create 3-dimensional reconstructions of structures in cases of suspected open-mouth jaw locking; improve evaluation of the lesions; and improve decision-making and client education for diagnosis, treatment options, and prognosis.

Asunto(s)

RESUMEN

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of postoperative beta-irradiation with strontium-90 as an adjunctive treatment to superficial keratectomy and permanent bulbar conjunctival graft for removal of equine corneolimbal squamous cell carcinoma (SCC), in decreasing recurrence rate. STUDY: The retrospective case study included 38 horses diagnosed and treated for SCC of the eye that involved the limbus and/or cornea. The patients were treated between 1990 and 2002, with strontium-90 irradiation immediately after corneal and conjunctival graft surgery. Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe that was previously treated. RESULTS: The Appaloosa was the most commonly represented breed and horses that had more than one base coat color represented the majority of the cases (53%). The coat colors of white, chestnut/sorrel and gray were the most commonly represented colors of the horses treated. Eight horses (21%) could not be assessed for tumor recurrence due to lack of two or more post-treatment examinations, and another horse was enucleated 6 days postoperatively due to progressive corneal ulceration. Twenty-four horses (63% of the entire study population; 83% of the followed cases) had a mean +/- SD of 1754 +/- 1319 days without tumor recurrence, ranging from 14 days to 5110 days. Five horses (13% of the entire study population; 17% of the assessed horses) had tumor recurrence at a mean +/- SD of 449 +/- 339 days with a range of 29 days to 900 days. For the five recurrences, treatment included local excision (n = 1), enucleation (n = 2), and additional strontium-90 therapy (n = 3). CONCLUSIONS: The combination of superficial keratectomy, beta-irradiation and permanent bulbar conjunctival grafts for limbal, corneal or corneolimbal SCC in horses is effective in at least 83% of the horses. Recurrence occurred in about 17% of the horses. Multiple biannual re-examinations are recommended to observe for tumor recurrence.

Asunto(s)

RESUMEN

As lesões nervosas periféricas sempre ocasionam comprometimento dasensibilidade ou da motricidade, de partes ou segmentos do organismo. Algumas lesões leves podem evoluir para a cura completa em poucas semanas, se a integridade morfológica do axônio estiver preservada. Entretanto, as lesões com perda tecidual, se não foram tratadas adequadamente, podem evoluir com prejuízos na função muscular ou na sensibilidade cutânea. Assim sendo, este trabalho teve por objetivo estudara possível regeneração axonal do nervo ciático de rato albino (Rattus norvegicus albinus) lesado experimentalmente, através do uso de enxerto venoso ao avesso e de enxerto venoso preenchido com plasma rico em plaquetas, sob o ponto de vista histomorfológico. Os animais foram divididos em quatro grupos experimentais (G2, G3, G4 e G5) contendo 15 animais em cada grupo e um grupo com dez animais serviu como controle (G1). Em todos os grupos o nervo ciático direito foi utilizado para estudo experimental. Os Grupos G 2, G 3, G 4 e G 5 receberam enxerto venoso da veia jugular externa, do lado esquerdo, do mesmo animal. Em todas as técnicas utilizadas, os valores médios de morfometria foram maiores no enxerto do que no coto distal. As técnicas com veias preenchidas apresentaram melhores médias aritméticas quando comparadas com as veias não preenchidas.

Asunto(s)

RESUMEN

En el ámbito mundial, las investigaciones sobre la patología valvular porcina se limitan casi enteramente a la válvula mitral y existe muy poca información sobre alteraciones   de la válvula aórtica. Las válvulas aórticas porcinas son utilizadas comúnmente como bioimplantes en humanos. Por esta razón en este estudio se propusieron los siguientes objetivos: caracterizar la patología valvular aórtica en cerdos seleccionados para la elaboración de bioprótesis valvulares cardíacas, discutir los mecanismos involucrados en el desarrollo de dichas lesiones y analizar los criterios de selección para determinar la confiabilidad del implante. Para esto se recolectaron al azar 50 corazones con lesiones evidentes de la válvula aórtica y 50 sin lesiones evidentes. Las válvulas se procesaron por el método histopatológico de rutina y se realizaron las tinciones de Hematoxilina-Eosina y azul alciano-PAS. Los resultados se evaluaron mediante estadística descriptiva e inferencia estadística; además, se realizó un análisis mediante la prueba de Chi-cuadrado utilizando el programa SPSS versión 1.0 para determinar asociaciones entre las variables macroscópicas y microscópicas. Las lesiones microscópicas y su frecuencia en los dos grupos estudiados fueron, respectivamente, las siguientes: trastornos vasculares 84 por ciento y 38 por ciento; endocardiosis 80 por ciento y 4 por ciento; fenestraciones 48 por ciento, únicamente en las que tenían lesiones obvias; valvulitis 42 por ciento y 24 por ciento. Se presentan y se correlacionan las principales alteraciones macro y microscópicas; así como los posibles mecanismos implicados en su desarrollo. Este estudio es el primero, en Colombia, que caracteriza las alteraciones patológicas de la válvula aórtica porcina.

Asunto(s)

RESUMEN

OBJECTIVE: To determine whether autologous jugular veins provide functional grafts with high 30-day patency rates in an experimental model of systemic-to-pulmonary shunting performed with a modified Blalock-Taussig procedure. ANIMALS: 15 healthy Beagles. PROCEDURE: A segment of the left jugular vein was implanted between the left subclavian and pulmonary arteries. Echocardiograms were obtained prior to surgery, at day 4 to 7, and at day 30 after surgery. Selective angiograms were performed immediately after surgery and on day 30. Oximetric shunt calculations were made via terminal angiography prior to euthanasia. Gross and histologic evaluations of the grafts were conducted. RESULTS: Grafts were patent in 12 of 15 dogs 30 days after surgery as assessed via auscultation, color Doppler ultrasonography, angiography, and histologic examination. Echocardiographic analysis revealed compensatory eccentric left ventricular hypertrophy. Mean pulmonary-to-systemic flow ratio was 1.5:1. Histologic evidence of endothelialization of the anastomotic sites and vein graft arterialization was detectable at 30 days. CONCLUSIONS AND CLINICAL RELEVANCE: Autologous jugular vein grafts were effectively used to create a systemic-to-pulmonary shunt by use of a modified Blalock-Taussig procedure. High patency, ready accessibility, low cost, and theoretical adaptative remodeling during patient growth make autologous jugular vein grafts a valuable alternative to synthetic materials.

Asunto(s)

RESUMEN

Doze eqüinos foram divididos aleatoriamente em dois grupos de seis animais (grupos I e II), com a finalidade de estudar a compatibilidade tecidual e a propriedade de indução de trombos de dois tecidos biológicos conservados em glicerina a 98 por cento. Esses tecidos foram usados na restauração da jugular externa e se constituíram de artéria carótida comum homóloga (ACCHo), no grupo I, e veia jugular externa heteróloga (VJEHe), no grupo II. Para a restauração, utilizaram-se duas técnicas de anastomose da jugular, sendo, no grupo I, a técnica de bypass e, no grupo II, a substituição de um segmento da jugular esquerda por meio de anastomose vascular término-terminal. Para avaliar a trombogênese local e a histocompatibilidade, foram realizados exames clínicos, hematológicos, ecoDopplercardiográficos e histológicos dos segmentos vasculares enxertados. Os segmentos foram colhidos após 45 dias da avaliação pós-operatória, tendo a jugular direita como testemunha para os exames histológicos. Ambos os tecidos foram compatíveis quando implantados nos eqüinos, sem processo inflamatório acentuado, indicativo de rejeição. A técnica de bypass não foi eficiente na restauração da jugular, ocorrendo trombose obliterante dos enxertos de ACCHo. A substituição completa do segmento da jugular por VJEHe pode ser viável para o restabelecimento do fluxo sangüíneo da jugular de eqüinos, desde que se mantenha a igualdade dos diâmetros entre o enxerto e o vaso receptor.

Asunto(s)

RESUMEN

Naturally occurring biomaterials, such as small intestine submucosa (SIS), are attractive as potential scaffolds for engineering various tissue types. The aim of this study was to determine whether acellular SIS scaffolds can support cell attachment and ingrowth in a diarthroadial joint without significant intraarticular hemorrhage. Disks of porcine SIS were arthoscopically implanted freely within a randomized knee joint of 21 dogs and harvested 1, 2, 3, and 6 weeks postoperatively. Harvested disks were assessed for gross and histologic appearance, cellular infiltration, and immunoreactivity of collagenase and collagen types I and II. Knee synovium and synovial fluid were also evaluated. All disks were thickened and opacified at harvest. Eleven disks (52%) had adhered to intraarticular tissues and cellular infiltration into the disks was positively correlated with tissue adherence. Further, tissue adherence was positively correlated with duration of intraarticular implantation. Five disks (24%) contained focal areas of homogeneous extracellular matrix. A trend toward more collagenase immunoreactivity was noted in the 3-week disks. Collagen type I was present in remaining SIS and extracellular matrix associated with infiltrated cells. Placed freely within a joint, acellular SIS disks underwent cellular and extracellular matrix modification resulting in fibrocartilage-like tissue. Utilization of SIS as a scaffold for intraarticular tissue-engineering applications is supported as cytoconductivity, appropriate residence time, and absence of untoward effects of implantation are desirable criteria for a tissue-engineering biomaterial.

Asunto(s)

RESUMEN

Atrial mass resection is possible in a limited number of dogs with hemangiosarcoma in which only the right atrial appendage or atrial free wall is involved, A pericardial patch graft can be used to reconstruct the right atrium after resection of large atrial tumors. Tumor-free margins can be obtained by use of this technique.

Asunto(s)