Effects of mesenchymal stem cell culture on radio sterilized human amnion or radio sterilized pig skin in burn wound healing.

Deep second and third degree burns treatment requires fibroblasts, keratinocytes and other skin cells in order to grow new dermis and epidermis. Cells can proliferate, secrete growth factors and extracellular matrix required to repair the damaged tissue. Radiosterilized human amnion and radiosterilized pig skin have been used as natural origin skin dressings for burned patients. Adipose-derived mesenchymal stem cells can differentiate into fibroblasts and keratinocytes and improve wound-healing progress. These cells can stimulate vascular tissue formation, release growth factors, synthetize new extracellular matrix and immunoregulate other cells. In this study, we developed mesenchymal stem cells-cellularized skin substitutes based from radiosterilized human amnion or pig skin. Third-degree burns were induced in mice animal models to evaluate the effect of cellularized skin substitutes on burn wound healing. Mesenchymal phenotype was immunophenotypically confirmed by flow cytometry and cell viability was close to 100%. Skin recovery was evaluated in burned mice after seven and fourteen days post-coverage with cellularized and non-cellularized sustitutes. Histological techniques and immunofluorescence were used to evaluate re-epithelization and type I collagen deposition. We determined that cellularized-human amnion or cellularized-pig skin in combination with mesenchymal stem cells improve extracellular matrix deposition. Both cellularized constructs increase detection of type I collagen in newly formed mouse skin and can be potentially used as skin coverage for further clinical treatment of burned patients.

Obtención de plasma rico en plaquetas (PRP) en el Laboratorio de Terapia Celular para uso como herramienta terapéutica en medicina regenerativa / Obtaining platelet rich plasma (PRP) in the Cell Therapy Laboratory for use as a therapeutic tool in regenerative medicine

Platelet rich plasma (PRP) is used to speed up tissue repair. Despite its widespread use, the therapeutic application of PRP generates controversies in clinical results due to the variability in methods of obtaining the different preparations and differences between the components of different types of PRP, so it's recommended to mention the type of platelet preparation used. In this article, we describe technical and biologics characteristics of our platelet product, and we compare them to different commercial preparations described in order to validate their clinical use. Our results determine that the preparation can be considered a platelet rich plasma with biological activity in vivo and in vitro, which supports its use as a valid therapeutic tool, alternative to products currently available in Regenerative Medicine. (AU)

Characterization of pediatric microtia cartilage: a reservoir of chondrocytes for auricular reconstruction using tissue engineering strategies.

The external ear is composed of elastic cartilage. Microtia is a congenital malformation of the external ear that involves a small reduction in size or a complete absence. The aim of tissue engineering is to regenerate tissues and organs clinically implantable based on the utilization of cells and biomaterials. Remnants from microtia represent a source of cells for auricular reconstruction using tissue engineering. To examine the macromolecular architecture of microtia cartilage and behavior of chondrocytes, in order to enrich the knowledge of this type of cartilage as a cell reservoir. Auricular cartilage remnants were obtained from pediatric patients with microtia undergoing reconstructive procedures. Extracellular matrix composition was characterized using immunofluorescence and histological staining methods. Chondrocytes were isolated and expanded in vitro using a mechanical-enzymatic protocol. Chondrocyte phenotype was analyzed using qualitative PCR. Microtia cartilage preserves structural organization similar to healthy elastic cartilage. Extracellular matrix is composed of typical cartilage proteins such as type II collagen, elastin and proteoglycans. Chondrocytes displayed morphological features similar to chondrocytes derived from healthy cartilage, expressing SOX9, COL2 and ELN, thus preserving chondral phenotype. Cell viability was 94.6 % during in vitro expansion. Elastic cartilage from microtia has similar characteristics, both architectural and biochemical to healthy cartilage. We confirmed the suitability of microtia remnant as a reservoir of chondrocytes with potential to be expanded in vitro, maintaining phenotypical features and viability. Microtia remnants are an accessible source of autologous cells for auricular reconstruction using tissue engineering strategies.

Osteogenic potential of murine periosteum for critical-size cranial defects.

Tissue engineering of bone has combined bespoke scaffolds and osteoinductive factors to maintain functional osteoprogenitor cells, and the periosteum has been confirmed as a satisfactory source of osteoblasts. Suitable matrices have been identified that support cell proliferation and differentiation, including demineralised bone matrix (both compatible and osteoinductive) and acellular human dermis. We have evaluated the osteogenic potential of an osteogenic unit, developed by combining periosteum, demineralised bone matrix, and acellular human dermis, in rodents with critical-size cranial defects. Briefly, remnants from the superior maxillary periosteum were used to harvest cells, which were characterised by flow cytometry and reverse retrotranscriptase-polymerase chain reaction (RT-PCR). Cells were cultured into the osteogenic unit and assessed for viability before being implanted into 3 rodents, These were compared with the control group (n=3) after three months. Histological analyses were made after staining with haematoxylin and eosin and Von Kossa, and immunostaining, and confirmed viable cells that stained for CD90, CD73, CD166, runt-related transcription factor, osteopontin, and collagen type I in the experimental group, while in the control group there was only connective tissue on the edges of the bone in the injury zone. We conclude that osteogenic unit constructs have the osteogenic and regenerative potential for use in engineering bone tissue.

Involvement of hypoxia and inflammation in early pregnancy loss mediated by Shiga toxin type 2.

INTRODUCTION: Symptomatic or asymptomatic Shiga toxin producing Escherichia coli (STEC) infections during early pregnancy may cause maternal or fetal damage mediated by Shiga toxin type 2 (Stx2). The aim of this study is to elucidate the mechanisms responsible for early pregnancy loss in rats treated with Stx2. METHODS: Sprague Dawley pregnant rats were intraperitoneally injected at day 8 of gestation with a sublethal dose (0.5 ng of Stx2/g of total body weight, 250 µl) of purified Stx2. Control rats were injected with the same volume of PBS. The expression of globotriaosylceramide (Gb3) glycosphingolipid receptor for Stx2 was evaluated by thin-layer chromatography (TLC). Regions of hypoxia in decidual tissue were determined by pimonidazole immunohistochemistry and vascular endothelial growth factor (VEGF) expression by Western blot and immunohistochemistry. Tumor necrosis factor-alpha (TNF-α) levels in serum and decidual tissue were evaluated by ELISA. Serum progesterone levels were determined by RIA. RESULTS: Decidual tissue from both, control and Stx2-treated rats showed similar expression of Gb3 receptor. Intrauterine growth restriction was observed in Stx2-treated rats, associated with hypoxia and an increase of decidual TNF-α levels. Decrease of serum progesterone levels and decidual VEGF expression were also demonstrated. DISCUSSION: Our findings indicate that Stx2 reaches the uteroplacental unit, binds Gb3 and triggers damage in decidual tissue. Poor oxygen supply accompanied with damage in the uteroplacental unit and inflammation could be responsible for the early pregnancy loss. Decrease in the pregnancy protective factors, serum progesterone and local VEGF, may contribute to the pregnancy loss.

Compromiso neurológico y hematológico por déficit de vitamina B12 en lactante hijo de madre vegetariana: caso clínico / Hematological and neurological compromise due to vitamin B12 deficit in infant of a vegetarian mother: case report

Introducción: La deficiencia de vitamina B12 es una de las complicaciones del vegetarianismo y sus variantes. Los lactantes de madres vegetarianas tienen mayor riesgo de deficiencia y son más lábiles a sus efectos. Objetivo: Relatar un caso para alertar sobre la importancia de la sospecha de deficiencia de vitamina B12 en hijos de madres con hábito vegetariano. Caso clínico: Se presenta una lactante de 12 meses, hija de una mujer vegetariana de larga data, que se presenta con compromiso neurológico y hematológico por déficit de vitamina B12. Luego de un corto período de administración de cianocobalamina parenteral y apoyo enteral nutricional, evoluciona con una notoria mejoría clínica y de laboratorio, aunque aún presenta retraso del desarrollo residual. Conclusiones: La deficiencia de vitamina B12 no es frecuentemente sospechada por el pediatra en lactantes sanos. Sus manifestaciones clínicas pueden ser tan inespecíficas, como la apatía, el rechazo alimentario y el deterioro progresivo del desarrollo psicomotor. Una anamnesis nutricional breve realizada a la madre (con mayor énfasis en aquellas vegetarianas) para estimar sus reservas en el periodo previo, durante y después del parto pueden ser fundamentales para detectar el riesgo déficit de esta vitamina en el niño pequeño.

Introduction: Vitamin B12 deficiency is extremely common in strict vegetarians and their variants. Infants of vegetarian mothers have a higher risk of deficiency and are more prone to its effects. Objective: To report a case in order to warn people about the importance of suspected vitamin B12 deficiency in children of vegetarian mothers. Case report: A 12-month old infant, daughter of a longtime vegetarian woman, who presented neurological and hematological compromise due to vitamin B12 deficiency, is discussed. After a short period of parenteral administration of cyanocobalamin and enteral nutrition, the patient evolved with clinical and laboratory improvement, although she still had residual development delay. Conclusions: Vitamin B12 deficiency is often not suspected by the pediatrician in healthy infants. Clinical manifestations can be nonspecific, such as apathy, food refusal and progressive impairment of psychomotor development. A nutritional anamnesis performed on the mother (with great emphasis on those strict vegetarians) to estimate her reserves in the period prior to, during and after delivery can be critical to detect the risk of this vitamin deficiency in young children.

[Hematological and neurological compromise due to vitamin B12 deficit in infant of a vegetarian mother: case report]. / Compromiso neurológico y hematológico por déficit de vitamina B12 en lactante hijo de madre vegetariana: caso clínico.

INTRODUCTION: Vitamin B12 deficiency is extremely common in strict vegetarians and their variants. Infants of vegetarian mothers have a higher risk of deficiency and are more prone to its effects. OBJECTIVE: To report a case in order to warn people about the importance of suspected vitamin B12 deficiency in children of vegetarian mothers. CASE REPORT: A 12-month old infant, daughter of a longtime vegetarian woman, who presented neurological and hematological compromise due to vitamin B12 deficiency, is discussed. After a short period of parenteral administration of cyanocobalamin and enteral nutrition, the patient evolved with clinical and laboratory improvement, although she still had residual development delay. CONCLUSIONS: Vitamin B12 deficiency is often not suspected by the pediatrician in healthy infants. Clinical manifestations can be nonspecific, such as apathy, food refusal and progressive impairment of psychomotor development. A nutritional anamnesis performed on the mother (with great emphasis on those strict vegetarians) to estimate her reserves in the period prior to, during and after delivery can be critical to detect the risk of this vitamin deficiency in young children.

Characterization of stx2 tubular response in a rat experimental model of hemolytic uremic syndrome.

BACKGROUND/AIMS: In Argentina, hemolytic uremic syndrome (HUS) constitutes the most frequent cause of acute renal failure in children. The aim of our study was to analyze the early tubular response under the effect of Shiga toxin type 2 (Stx2) in a rat experimental model of HUS. METHODS: Adult male Sprague-Dawley rats were injected intraperitoneally with culture supernatant from recombinant Escherichia coli expressing Stx2. Functional, histological, immunohistochemical and Western blot studies were performed at 48 h postinoculation. RESULTS: Renal tubules showed the loss of the epithelial markers E-cadherin and ß-catenin, and an increase in transforming growth factor-ß1 expression. We detected the expression of α-smooth muscle actin in the interstitium and fibrosis in the periglomerular areas. CONCLUSION: Our results indicate that the early tubular response to the effects of Stx2 is related to an immunophenotype change of tubular cells and the presence of mild fibrosis in the interstitium.

[Tracheal intubation quality under remifentanil-propofol with sevoflurane compared with remifentanil-propofol with rocuronium: a randomized double-blind clinical trial]. / Evaluación clínica de la calidad de la intubación endotraqueal con remifentanilo-propofol-sevoflurano comparada con remifentanilo-propofol-rocuronio: ensayo clínico aleatorizado, doble ciego.

OBJECTIVE: To determine whether intubation conditions under remifentanil-propofol plus sevoflurane rather than a nondepolarizing neuromuscular blocker are similar to those obtained when a neuromuscular blocker is used. MATERIAL AND METHODS: In this double-blind controlled trial, 100 patients undergoing outpatient surgery were randomized to 2 groups. Intubation in one group was performed under remifentanil, propofol and sevoflurane. In the other, intubation was performed under remifentanil, propofol, and the nondepolarizing neuromuscular blocker rocuronium. We recorded dysphonia at 24 hours, Cormack-Lehane classification at laryngoscopy, mandibular relaxation, vocal cord position and mobility, and cough or movement during laryngoscopy, on intubation and on cuff inflation. Blood pressure and heart rate before and after tracheal intubation were also recorded. RESULTS: No significant between-group differences were observed in dysphonia 24 hours after surgery, Cormack-Lehane classification at laryngoscopy, mandibular relaxation, the position or mobility of vocal cords, or cough or movement during laryngoscopy, intubation or cuff inflation. After intubation the mean (SD) systolic blood pressure was 119.7 (75.4) mm Hg in the rocuronium group and 97.5 (54.5) mm Hg in the sevoflurane group. Mean heart rate was 80.7 beats/min in the rocuronium group and 66.7 beats/min in the sevoflurane group. The differences were significant (P < .05). CONCLUSIONS: Adequate doses of remifentanil, propofol, and sevoflurane provide intubation conditions that are similar to those achieved by using a nondepolarizing neuromuscular blocker, without exposing patients to additional risk. Avoiding use of a neuromuscular blocker would circumvent the development of complications associated with use of these agents or their antagonists and costs would be lower.

Parallel activation of Ca(2+)-induced survival and death pathways in cardiomyocytes by sorbitol-induced hyperosmotic stress.

Hyperosmotic stress promotes rapid and pronounced apoptosis in cultured cardiomyocytes. Here, we investigated if Ca(2+) signals contribute to this response. Exposure of cardiomyocytes to sorbitol [600 mosmol (kg water)(-1)] elicited large and oscillatory intracellular Ca(2+) concentration increases. These Ca(2+) signals were inhibited by nifedipine, Cd(2+), U73122, xestospongin C and ryanodine, suggesting contributions from both Ca(2+) influx through voltage dependent L-type Ca(2+) channels plus Ca(2+) release from intracellular stores mediated by IP(3) receptors and ryanodine receptors. Hyperosmotic stress also increased mitochondrial Ca(2+) levels, promoted mitochondrial depolarization, reduced intracellular ATP content, and activated the transcriptional factor cyclic AMP responsive element binding protein (CREB), determined by increased CREB phosphorylation and electrophoretic mobility shift assays. Incubation with 1 mM EGTA to decrease extracellular [Ca(2+)] prevented cardiomyocyte apoptosis induced by hyperosmotic stress, while overexpression of an adenoviral dominant negative form of CREB abolished the cardioprotection provided by 1 mM EGTA. These results suggest that hyperosmotic stress induced by sorbitol, by increasing Ca(2+) influx and raising intracellular Ca(2+) concentration, activates Ca(2+) release from stores and causes cell death through mitochondrial function collapse. In addition, the present results suggest that the Ca(2+) increase induced by hyperosmotic stress promotes cell survival by recruiting CREB-mediated signaling. Thus, the fate of cardiomyocytes under hyperosmotic stress will depend on the balance between Ca(2+)-induced survival and death pathways.

Caracterización de los estudiantes de las especializaciones clinicas de la facultad de odontología de la Universidad de Antioquia, Semestre 2004-1 / Student characterization of the clinical specializations at the school of dentistry, University of Antioquia, semester 2004-1

Introducción: la caracterización estudiantil es un proceso útil en la generación de información, pues permite diagnosticar, evaluar y retroalimentar la planeación y organización curricular. Métodos: el objetivo de esta investigación de corte descriptivo transversal fue identificar las características demográficas, socioeconómicas, académicas y profesionales, al igual que otras actividades extracurriculares de los estudiantes de los posgrados matriculados durante el semestre 2004-1. La población estuvo conformada por 48 estudiantes a quienes se les aplicó una encuesta con preguntas abiertas y cerradas. Los datos fueron procesados en el programa EPI-INFO. Resultados y conclusiones: muestran que el grupo de estudiantes son en su mayoría mujeres, solteras y con edades que oscilan entre los 28 y 30 años; un poco más de la mitad labora para su sostenimiento entre 6 y 10 horas semanales y ganan entre 1 y 2 SMLV mensuales, desempeñándose en el área clínica odontológica, sin presentar dificultades académicas por su actividad laboral, ni dificultades laborales por su labor académica. La información aquí presentada puede servir como insumo para el rediseño curricular y planeaciones futuras, así como de sustento para los procesos de acreditación que los posgrados ya han iniciado.

Interferon regulatory factor-1 regulates reconstituted extracellular matrix (rECM)-mediated apoptosis in human mammary epithelial cells.

Interactions between extracellular matrix (ECM) and mammary epithelial cells are critical for mammary gland homeostasis and apoptotic signaling. Interferon regulatory factor-1 (IRF-1) is a transcriptional regulator that promotes apoptosis during mammary gland involution and p53-independent apoptosis. We have recently shown that rapid cell surface tamoxifen (Tam) signaling promotes apoptosis in normal human mammary epithelial cells that were acutely damaged by expression of human papillomavirus type-16 E6 protein (*HMEC-E6). Apoptosis was mediated by recruitment of CREB-binding protein (CBP) to the gamma-activating sequence (GAS) element of the IRF-1 promoter, induction of IRF-1 and caspase-1/-3 activation. Here, we show that growth factor-depleted, reconstituted ECM (rECM), similar to Tam, promotes apoptosis in *HMEC-E6 cells through induction of IRF-1. Apoptosis was temporally associated with recruitment of CBP to the GAS element of the IRF-1 promoter, induction of IRF-1 expression and caspase-1/-3 activation. Small interfering RNA-mediated suppression of IRF-1 protein expression in *HMEC-E6 cells blocked (1) induction of IRF-1, (2) caspase-1/-3 activation and (3) apoptosis. These observations demonstrate that IRF-1 promotes rECM-mediated apoptosis and provide evidence that both rECM and rapid Tam signaling transcriptionally activate IRF-1 through recruitment of CBP to the IRF-1 GAS promoter complex.

Reoperaciones por fracaso tardío de la cirugía bariátrica: reporte de 5 casos clínicos / Reoperation due to late failure or complications of bariatric surgery: report of five cases

En el presente trabajo hacemos una revisión y análisis descriptivo de 5 casos clínicos de pacientes operados por obesidad mórbida, que se presentaron en el Hospital Clínico de la Universidad de Chile en el período de junio del 2003 a septiembre del 2005 en los que se detectó fallas de algunos de estos procedimientos manifestadas por síntomas y reganancia de su peso.

[Cytotoxic effect in human colon of enterohemorrhagic Escherichia coli isolated from calves with bloody diarrhea]. / Efecto citotóxico en colon humano de Escherichia coli enterohemorrágico aislado de terneros con diarrea sanguinolenta.

Shiga toxin-producing E. coli (STEC) is one of the most important emergent pathogen in foods, being its main reservoir bovine cattle. STEC can cause diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. The present work have studied the cytotoxic action in human colon of cultures of two STEC strains isolated from faeces of calves with bloody diarrhea. Colonic mucosa was mounted as a diaphragm in a Ussing chamber and incubated with the cultures of pathogenic strains. Net water flow (Jw) decreased and the short-circuit current (Isc) increased significantly (p < 0.01) compared to negative control. Tissues showed an erosion of the mucose, epithelial exfoliation, and presence of pseudo-membranes in the lumen. Mild circulatory lesions were observed in the lamina propia. A moderate neutrophils infiltration was observed in the lumen and into the epithelial cells. Colonic crypts were not disrupted. Both experimental strains caused a similar lesion on colon tissues. This is the first study that shows that cultures of STEC strains isolated from bovine cattle produce cytotoxic effects in vitro in human colon.

Efecto citotóxico en colon humano de Escherichia coli enterohemorrágico aislado de terneros con diarrea sanguinolenta / Cytotoxic effect in human colon of enterohemorrhagic Escherichia coli isolated from calves with bloody diarrhea

Escherichia coli productor de toxina Shiga (STEC) es el patógeno emergente en alimentos de mayor impacto, siendo su principal reservorio el ganado bovino. STEC puede causar diarrea, colitis hemorrágica y síndrome urémico hemolítico. El presente trabajo estudió la acción citotóxica de dos cepas de STEC aisladas de heces de terneros diarreicos en colon humano in vitro. Los fragmentos se montaron como un diafragma en una cámara de Ussing y se incubaron con las cepas patógenas. El flujo neto absortivo de agua (Jw) disminuyó y la corriente de cortocircuito (Isc) aumentó significativamente (P < 0,01) con respecto al control negativo. Los tejidos presentaron erosión de la mucosa, exfoliación del epitelio, y presencia de pseudomembranas en el lumen. A nivel de la lámina propia se observaron lesiones circulatorias leves. Una moderada infiltración de neutrófilos se observó en el lumen y en las células epiteliales. Las criptas colónicas no se vieron afectadas. El grado de lesión fue similar en ambas cepas experimentales. Este es el primer estudio que demuestra que cultivos de cepas de STEC aisladas de ganado bovino producen efectos citotóxicos en colon humano in vitro.

Shiga toxin-producing E. coli (STEC) is one of the most important emergent pathogen in foods, being its main reservoir bovine cattle. STEC can cause diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. The present work have studied the cytotoxic action in human colon of cultures of two STEC strains isolated from faeces of calves with bloody diarrhea. Colonic mucosa was mounted as a diaphragm in a Ussing chamber and incubated with the cultures of pathogenic strains. Net water flow (Jw) decreased and the short-circuit current (Isc) increased significantly (p < 0,01) compared to negative control. Tissues showed an erosion of the mucose, epithelial exfoliation, and presence of pseudo-membranes in the lumen. Mild circulatory lesions were observed in the lamina propia. A moderate neutrophils infiltration was observed in the lumen and into the epithelial cells. Colonic crypts were not disrupted. Both experimental strains caused a similar lesion on colon tissues. This is the first study that shows that cultures of STEC strains isolated from bovine cattle produce cytotoxic effects in vitro in human colon.

Efecto citotóxico de la toxina Shiga tipo 2 y su subunidad B en células epiteliales tubulares renales humanas en cultivo / Cytotoxic effect of Shiga toxin type 2 and its B subunit on human renal tubular epithelial cell cultures

Escherichia coli enterohemorrágica productora de toxina Shiga (Stx) causa diarrea acuosa, colitis hemorrágica y síndrome urémico hemolítico (SUH). En Argentina, el SUH es la principal causa de insuficiencia renal en niños. El objetivo de este trabajo fue estudiar la toxicidad de Stx tipo 2 (Stx2) y su subunidad B (Stx2B) en células epiteliales tubulares renales humanas (CERH), en presencia y ausencia de factores inflamatorios. Los efectos citotóxicos se evaluaron como alteración de la funcionalidad del epitelio; daños histológicos; viabilidad celular; síntesis de proteínas y apoptosis celular. Los resultados muestran que Stx2 regula el pasaje de agua a través de CERH a tiempos menores de 1h de incubación. A tiempos mayores, hasta 72 hs, el estudio de la morfología, la viabilidad, la síntesis de proteínas y la apoptosis demostró que las CERH fueron sensibles a la acción citotóxica de Stx2 y Stx2B de una manera dosis y tiempo dependiente. Estos efectos fueron potenciados por lipopolisacáridos bacterianos (LPS), IL-1, y butirato.

The Shiga toxin 2 B subunit inhibits net fluid absorption in human colon and elicits fluid accumulation in rat colon loops.

Shiga toxin (Stx)-producing Escherichia coli (STEC) colonizes the large intestine causing a spectrum of disorders, including watery diarrhea, bloody diarrhea (hemorrhagic colitis), and hemolytic-uremic syndrome. It is estimated that hemolytic-uremic syndrome is the most common cause of acute renal failure in infants in Argentina. Stx is a multimeric toxin composed of one A subunit and five B subunits. In this study we demonstrate that the Stx2 B subunit inhibits the water absorption (Jw) across the human and rat colonic mucosa without altering the electrical parameters measured as transepithelial potential difference and short circuit current. The time-course Jw inhibition by 400 ng/ml purified Stx2 B subunit was similar to that obtained using 12 ng/ml Stx2 holotoxin suggesting that both, A and B subunits of Stx2 contributed to inhibit the Jw. Moreover, non-hemorrhagic fluid accumulation was observed in rat colon loops after 16 h of treatment with 3 and 30 ng/ml Stx2 B subunit. These changes indicate that Stx2 B subunit induces fluid accumulation independently of A subunit activity by altering the usual balance of intestinal absorption and secretion toward net secretion. In conclusion, our results suggest that the Stx2 B subunit, which is non-toxic for Vero cells, may contribute to the watery diarrhea observed in STEC infection. Further studies will be necessary to determine whether the toxicity of Stx2 B subunit may have pathogenic consequences when it is used as a component in an acellular STEC vaccine or as a vector in cancer vaccines.

The Shiga toxin 2 B subunit inhibits net fluid absorption in human colon and elicits fluid accumulation in rat colon loops

Shiga toxin (Stx)-producing Escherichia coli (STEC) colonizes the large intestine causing a spectrum of disorders, including watery diarrhea, bloody diarrhea (hemorrhagic colitis), and hemolytic-uremic syndrome. It is estimated that hemolytic-uremic syndrome is the most common cause of acute renal failure in infants in Argentina. Stx is a multimeric toxin composed of one A subunit and five B subunits. In this study we demonstrate that the Stx2 B subunit inhibits the water absorption (Jw) across the human and rat colonic mucosa without altering the electrical parameters measured as transepithelial potential difference and short circuit current. The time-course Jw inhibition by 400 ng/ml purified Stx2 B subunit was similar to that obtained using 12 ng/ml Stx2 holotoxin suggesting that both, A and B subunits of Stx2 contributed to inhibit the Jw. Moreover, non-hemorrhagic fluid accumulation was observed in rat colon loops after 16 h of treatment with 3 and 30 ng/ml Stx2 B subunit. These changes indicate that Stx2 B subunit induces fluid accumulation independently of A subunit activity by altering the usual balance of intestinal absorption and secretion toward net secretion. In conclusion, our results suggest that the Stx2 B subunit, which is non-toxic for Vero cells, may contribute to the watery diarrhea observed in STEC infection. Further studies will be necessary to determine whether the toxicity of Stx2 B subunit may have pathogenic consequences when it is used as a component in an acellular STEC vaccine or as a vector in cancer vaccines.

Análisis crítico del manejo quirúrgico en endocarditis infecciosa en Chile / Critical analysis of the surgical managing in infectious endocarditis in Chile

Antecedentes: El tratamiento quirúrgico de la endocarditis infecciosa es un desafío cuya utilidad ha sido demostrada. Esta grave enfermedad, ha motivado numerosos estudios para identificar factores relacionados a morbimortalidad y estrategias para optimizar resultados. Objetivo: Se presenta la experiencia de un servicio nacional de cirugía cardiovascular en el tratamiento quirúrgico de endocarditis, para analizar sus resultados y compararlos con otras experiencias. Pacientes y Método: Se estudian casos operados con diagnóstico de endocarditis, describiendo antecedentes clínicos, tipo de cirugía, complicaciones y mortalidad. Se incluyen 177 eventos en 175 pacientes ingresados entre enero 1988 y diciembre 2003 en el Servicio de Cirugía Cardiovascular del Hospital Dr. Gustavo Fricke. Resultados: Sesenta y nueve por ciento fueron hombres con una edad promedio de 45 ± 13,95 años, y antecedentes cardíacos previos en 42,3 por ciento. La indicación quirúrgica más frecuente correspondió a insuficiencia cardíaca (81,4 por ciento) y sepsis (30,5 por ciento). Veintinueve fallecen (16,3 por ciento), 7 de ellos por endocarditis de prótesis vulvar siendo los factores más significativos asociados con mortalidad la presencia de shock, insuficiencia cardíaca congestiva, sepsis y fracaso de tratamiento médico preoperatorio. Setenta y cuatro pacientes tuvieron complicaciones mayores en postoperatorio y el promedio días estada fue de 24,6. Conclusiones: La cirugía es una terapia eficaz en endocarditis y debe ser precoz, especialmente cuando existe deterioro hemodinámico o sepsis. Nuestros resultados son similares a otras experiencias.