Browsing by Author "Gallegos, Marcela"
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Publication Angiomiolipoma hepático epitelioide: reporte de un caso(2022) Ahumada, Oscar; Hepp, Juan; Gallegos, Marcela; Schiappacasse, GiancarloAngiomyolipomas (AML) are mesenchymal tumors belonging to the group of perivascular epithelioid cell tumors, which, rarely, can display a malignant behavior. They are composed of adipose tissue, vessels, and muscle tissue in different proportions, and constitute a differential diagnosis for other focal liver lesions. We report a 34-year-old woman in whom a focal hepatic lesion was discovered incidentally. The pathology report of an ultrasound guided biopsy informed an epithelioid angiomyolipoma, a rare variant of these lesions. During ten years of imaging follow, the size and features of the lesion has not changed. The patient rejected a surgical excision.Item Anterior cruciate ligament regeneration using mesenchymal stem cells and collagen type I scaffold in a rabbit model(Springer, 2014) Figueroa, David; Espinosa, Maximiliano; Calvo, Rafael; Scheu, Maximiliano; Vaisman, Alex; Gallegos, Marcela; Conget, PaulettePurpose: The objective of this study was to determine whether using mesenchymal stem cells (MSC) seeded in a collagen type I scaffold would be sufficient to regenerate the torn anterior cruciate ligament (ACL). Methods: Anterior cruciate ligament transection was performed on both knees in 10 New Zealand rabbits and then repaired with as follows: suture alone (suture-treated group, n = 6), suture associated with collagen type I scaffold (collagen type I scaffold-treated group, n = 8) or suture associated with autologous MSC seeded on collagen type I scaffold (MSC/collagen type I scaffold-treated group, n = 6). At 12-week post-intervention, the animals were killed and the ACLs were characterised macroscopically and histologically. Data of the 3 groups were against normal ACL (normal group, n = 10). Results: Macroscopic observation found that in MSC/collagen type I scaffold group, 33 % of specimens showed a complete ACL regeneration, with a tissue similar to the normal ACL. Regeneration was not observed in the group treated with suture alone or associated with collagen type I scaffold without cells. In the latter, only a reparative attempt at the ends was observed. Histological analysis of the regenerated ACL showed a tissue with organised collagen and peripheric vessels. Conclusions: These results provide evidence that the use of MSC seeded in a collagen type I scaffold in the treatment of ACL injuries is associated with an enhancement of ligament regeneration. This MSC-based technique is a potentially attractive tool for improving the treatment of ACL ruptures.Item Cáncer mamario triple negativo ¿Cómo se ve en imágenes?(2012) Horvath, Eleonora; Bañuelos, Oscar; Silva F., Claudio; Mondaca, Jorge; González, Paulina; Gallegos, Marcela; Galleguillos, María Cecilia; Pinochet, Miguel Angel; Fernandez, Montserrat; Junemann, Karen; Camacho, JamileIntroducción. Los cánceres triple negativo (CTN) son aquellos que no presentan receptores de estrógeno, progesterona ni human epidermal grow factor, receptor type 2. Herceptin (HER2). Tienden a ser más agresivos; a menudo se diagnostican en pacientes jóvenes, a veces como cánceres de intervalo, llegan a ser de gran tamaño y más frecuentemente presentan metástasis axilares al momento del diagnóstico. Su pronóstico es peor que otros cánceres mamarios, existiendo una mayor probabilidad de recurrencia a distancia y de muerte, especialmente en los primeros 5 años. Pacientes y métodos. Se efectuó una revisión retrospectiva descriptiva de los casos de CTN diagnosticados en nuestra institución (periodo entre marzo de 2005 y junio de 2012) con el fin de identificar sus características imaginológicas. Resultados. Los CTN pueden quedar ocultos en mamografía (Mx) si el parénquima es denso (tipo ACR 3 y 4), puesto que aparecen principalmente como masas o asimetrías focales, sin microcalcificaciones. Tanto en Mx como en ultrasonido (US) pueden evocar una lesión de morfología benigna. En US se manifiestan frecuentemente como un nódulo sólido único, marcadamente hipoecogénico con refuerzo posterior, de contornos bastante circunscritos y que aparece hipo/avascular al Doppler color (o vascularizado en la periferia sin vasos centrales) y varios pedículos aferentes. La resonancia magnética (RM) identifica hallazgos claramente sospechosos con algunos elementos característicos: masa cuya localización es preferentemente posterior, pre-pectoral, marcadamente hiperintensa en T2 que capta el contraste en anillo y presenta curva de lavado, a veces con septos hipercaptantes en el centro de la lesión. Conclusión. Los CTN presentan a menudo características en imágenes que los diferencian de otros tipos de tumores.Item Clinical Outcome and Histological Findings After Induced Leakage of PMMA Loaded With Methotrexate and Cisplatin During Vertebroplasty: Experimental Model in Pigs(2021) Silva, Álvaro; Llombart, Rafael; Gallegos, Marcela; Villas, Carlos; Olmos, MatíasStudy design: Animal experimental model. Objective: To study the clinical behavior and histological changes in the spinal cord, nerve roots and perivertebral muscles of the spine after induced leakage of polymethylmethacrylate (PMMA) loaded with antiblastic drugs during vertebroplasty in an animal model of pigs. Methods: We performed vertebroplasty on 25 pigs. The animals were divided into 3 groups: vertebroplasty with PMMA alone (control group), vertebroplasty with PMMA loaded with methotrexate (MTX) and vertebroplasty with PMMA loaded with cisplatin (CYS). At 2 vertebral levels, epidural and prevertebral, massive cement leaks were induced. Animals were evaluated daily. Two weeks later, the pigs were sacrificed, and the tissues that came in contact with the cement were analyzed. Results: The clinical results for each of the groups were reported. The control group had no clinical alterations. In the MTX group, 2 pigs died before 1 week due to pneumonitis. In the CYS group, 4 animals had motor impairment, and 3 of the 4 had paraplegia. The histological results were as follows: the control and MTX groups showed synovial metaplasia, inflammatory reaction, crystal deposits, and giant cell reaction in the dura mater and muscle and all the animals in the CYS group had spinal cord and muscular necrosis. Conclusions: Massive cement leak after vertebroplasty with PMMA loaded with cisplatin is extremely toxic to the spinal cord and muscles around the spine. Therefore, its use cannot be recommended for the treatment of vertebral metastases. Using PMMA loaded with methotrexate seems to be a safe procedure, but further research is needed.Item Hamartoma mioide, serie de casos y revisión de la literatura(Sociedad Chilena de Radiologia, 2016) Uchida, Marcela; Altamirano, Aleen; Horvath, Eleonora; Pinochet, Miguel; Galleguillos, Maria; Wenzel, Heriberto; Gallegos, MarcelaMyoid hamartoma is a rare entity, and was first described by Davies and Riddell in 1973. It is pathologically defined as the mixture of fatty glandular tissue and fibrous connective tissue, associated with a widespread focus of fusiform muscle cells. Six cases of HM diagnosed in seven patients are presented, with emphasis on imaging findings and characteristics of their respective core biopsies. The importance of biopsy in these lesions is required to differentiate malignant diseases. There is no need for excisional biopsy, because this is not associated with high-risk lesions or carcinomas.Item Intraarticular administration of dexamethasone after mesenchymal stem cells implantation does not improve significantly the treatment of preestablished full-thickness chondral defect in a rabbit model(Sage Publications, 2013) Espinosa, Maximiliano; Vaisman, Alex; Nazal, Nicolas; Figueroa, David; Gallegos, Marcela; Conget, PauletteObjective: The aim of this study was to evaluate the contribution to hyaline cartilage regeneration of dexamethasone intraarticular administration after autologous mesenchymal stem cells (MSCs) implantation into a preestablished knee full-thickness chondral defect. Design: Full-thickness chondral defects of 4.5 × 4.5 mm2 were surgically made in both medial femoral condyles of adult male New Zealand rabbits. Two weeks later, autologous ex vivo expanded bone marrow–derived MSCs were embedded in hyaluronic acid and implanted into the chondral defects. Immediately and every week after the intervention, dexamethasone 0.25 mg/kg was intraarticularly administered (MSC/dexa-treated group). Six weeks after MSC transplantation, the animals were euthanized and condyles were characterized molecularly according to aggrecan, collagen type II, and collagen type I gene expression (quantitative reverse transcriptase-polymerase chain reaction) and histologically (hematoxylin–eosin staining). Data of MSC/dexa-treated condyles were compared with untreated, dexa-treated, MSCtreated, or normal unlesioned condyles. Results: The ratio between collagen type II expression versus collagen type I expression in MSC/dexa-treated condyles was higher than one, even though the group mean value was not statistically different from that of untreated defects. Histological changes were observed between MSC/dexa-treated and untreated defects mainly in surface regularity and in hyaline matrix abundance. However, International Cartilage Repair Society score analysis did not support robust differences between those groups. Conclusion: Intraarticular administration of dexamethasone after autologous MSC implantation into a preestablished full-thickness chondral defect does not contribute significantly to the regeneration of a tissue with molecular and histological characteristics identical to hyaline cartilage.Item Pólipo fibrovascular esofágico. Estudio por imágenes multimodalidad(2010) Gallegos, Marcela; Cortés, Claudio; Díaz, Juan Carlos; Navarrete, Claudio; Castillo, Cecilia; Silva F., ClaudioPresentamos una mujer de 47 años que presenta disfagia. Una tomografía computarizada de tórax y una deglución de bario mostraron una masa endoluminal que se extendía a cuatro vértebras. Una ecografía endoluminal localizó el pedículo de la masa, que fue extirpado endoscópicamente. El estudio anatomopatológico reveló un pólipo fibrovascular. Tras 18 meses de seguimiento, el paciente se encuentra asintomático.Item Steroids and Platelet-Rich Plasma as Coadjuvants to Microfracture for the Treatment of Chondral Lesions in an Animal Model: Can the Healing Be Enhanced?(Sage Publications, 2012) Vaisman, Alex; Figueroa, David; Calvo, Rafael; Espinosa, Maximiliano; Melean, Patricio; Gallegos, Marcela; Conget, PauletteObjective: The aim of this study was to evaluate the contribution to hyaline cartilage regeneration of the microfracture (MFx) technique plus intraarticular betamethasone (BMS) or platelet-rich plasma (PRP). Design: Full-thickness chondral defects of 3 × 6 mm2 were surgically performed in both femoral condyles of each knee in 13 New Zealand rabbits and then treated with MFx associated with intraarticular BMS or PRP. At 12 weeks postimplantation, the animals were killed and the condyles were characterized macroscopically, molecularly according to collagen type II and I gene expression (quantitative reverse transcriptase–polymerase chain reaction), and histologically (hematoxylin–eosin staining). For the latter, samples were scored using the International Cartilage Repair Society visual histological scale. Data of MFx/BMS-treated and MFx/PRP-treated condyles were compared against untreated, MFx-treated, or normal condyles without lesions. Results: Our macroscopic findings showed that in MFx/BMS-treated and MFx/PRP-treated groups, the defects were filled with an irregular, partially rough tissue similar to the MFx-treated group. No differences in the ratio between collagen type II versus collagen type I expression were observed among groups. Histological changes were observed between MFx/BMS-treated and MFx/PRP-treated groups versus untreated defects mainly in surface regularity and cell distribution. However, International Cartilage Repair Society score analysis did not support statistical differences between MFx/BMS-treated and MFx/PRP-treated groups versus MFx-treated group. Conclusions: These results provide evidence that the use of intraarticular BMS or PRP as coadjuvants to the microfracture technique in the treatment of acute chondral lesions is not associated with a significant improvement of hyaline cartilage regeneration.