Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite.

BACKGROUND: Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo. RESULTS: This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion. CONCLUSIONS: We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen-independent anaerobic process.

Understanding gold toxicity in aerobically-grown Escherichia coli.

BACKGROUND: There is an emerging field to put into practice new strategies for developing molecules with antimicrobial properties. In this line, several metals and metalloids are currently being used for these purposes, although their cellular effect(s) or target(s) in a particular organism are still unknown. Here we aimed to investigate and analyze Au3+ toxicity through a combination of biochemical and molecular approaches. RESULTS: We found that Au3+ triggers a major oxidative unbalance in Escherichia coli, characterized by decreased intracellular thiol levels, increased superoxide concentration, as well as by an augmented production of the antioxidant enzymes superoxide dismutase and catalase. Because ROS production is, in some cases, associated with metal reduction and the concomitant generation of gold-containing nanostructures (AuNS), this possibility was evaluated in vivo and in vitro. CONCLUSIONS: Au3+ is toxic for E. coli because it triggers an unbalance of the bacterium's oxidative status. This was demonstrated by using oxidative stress dyes and antioxidant chemicals as well as gene reporters, RSH concentrations and AuNS generation.

NDM-1 carbapenemase in Acinetobacter baumannii sequence type 32 in Ecuador.

OBJECTIVES: To describe a clinical case of Acinetobacter baumannii sequence type (ST) 32 harbouring a New Delhi metallo-ß-lactamase (NDM) in Ecuador. METHODS: We used multilocus sequence typing (MLST) to confirm the bacterial species and the sequence type of an A. baumannii isolate. We used synergy with the imipenem-EDTA disc method and the carbapenem inactivation method (CIM) to determine carbapenemase production; the presence of a carbapenemase gene was confirmed by PCR amplification and amplicon sequencing. RESULTS: Molecular characterization revealed the presence of A. baumannii ST32 harbouring the bla NDM-1 gene in Ecuador. The bla NDM-1 gene was isolated through PCR and amplified from a purified plasmid. CONCLUSIONS: To the best of our knowledge, this is the first report of A. baumannii ST32 harbouring the bla NDM-1 gene.

Anaerobic RSH-dependent tellurite reduction contributes to Escherichia coli tolerance against tellurite

BACKGROUND: Tellurium is a rare metalloid that exerts high toxicity on cells, especially on bacteria, partly due to reactive oxygen species (ROS) generation. Moreover, it has also been observed that tellurite can target free cell thiols groups (RSH) (i.e. reduced glutathione (GSH)), enhancing the cellular redox imbalance. Additionally, in vitro experiments have suggested that several enzymes can reduce tellurite (IV) to its elemental form (0); where RSH present on their active sites may be responsible for the process. Nevertheless, the mechanisms implemented by bacteria for tellurite reduction and its role in resistance have not been evaluated in vivo. RESULTS: This work shows that tellurite reduction to elemental tellurium is increased under anaerobic conditions in E. coli cells. The in vivo tellurite reduction is related to the intracellular concentration of total RSH, in the presence and absence of oxygen. This metabolization of tellurite directly contributes to the resistance of the bacteria to the oxyanion. CONCLUSIONS: We demonstrated that in vivo tellurite reduction is related to the intracellular thiol concentration, i.e. large availability of cellular RSH groups, results in a more significant reduction of tellurite. Furthermore, we observed that, when the bacterium exhibits less resistance to the oxyanion, a decreased tellurite reduction was seen, affecting the growth fitness. Together, these results let us propose that tellurite reduction and the intracellular RSH content are related to the oxyanion bacterial resistance, this tripartite mechanism in an oxygen independent anaerobic process.

Understanding gold toxicity in aerobically-grown Escherichia coli

BACKGROUND: There Is an emerging field to put Into practice new strategies for developing molecules with antimicrobial properties. In this line, several metals and metalloids are currently being used for these purposes, although their cellular effect(s) or target(s) in a particular organism are still unknown. Here we aimed to investigate and analyze Au3+ toxicity through a combination of biochemical and molecular approaches. RESULTS: We found that Au3+ triggers a major oxidative unbalance in Escherichia coli, characterized by decreased intracellular thiol levels, increased superoxide concentration, as well as by an augmented production of the antioxidant enzymes superoxide dismutase and catalase. Because ROS production is, in some cases, associated with metal reduction and the concomitant generation of gold-containing nanostructures (AuNS), this possibility was evaluated in vivo and in vitro. CONCLUSIONS: Au3+ is toxic for E. coli because it triggers an unbalance of the bacterium's oxidative status. This was demonstrated by using oxidative stress dyes and antioxidant chemicals as well as gene reporters, RSH concentrations and AuNS generation.

[The bone bank of the University Clinic in Navarra]. / Banco de hueso de la Clínica Universitaria de Navarra.

The Bone bank at the University Clinic is described along with its three units: Electrical freezer (-40 degrees). Liquid nitrogen freezer (-197 degrees). Temperature programmer descend. The first unit is used for the preservation of cancellous bone, for a limited lapse of time; the second unit is employed for preserving cortical grafts for an unlimited period. The third unit allows to control the temperature descend rate, in order to preserve the viability of chondrocytes in grafts including epiphyseal ends. Clinical applications of bone grafts are currently enlarging in areas such as tumour surgery, spine surgery and arthrodesis and reconstructive procedures of the hip joint.

SR-A regulates the inflammatory activation of astrocytes.

Scavenger receptor Class A (SR-A) participates in the regulation of inflammatory processes against pathogens and in inflammatory stimulation. We have recently demonstrated the presence of SR-A in astrocytes, but its participation in their inflammatory response is unknown. Astrocytes regulate neuroinflammation through the regulation of microglial cell activation and the production of cytokines, neurotrophic factors, and reactive species. Using astrocytes from SR-A(-/-) mice in culture, we assessed the participation of SR-A in their inflammatory activation, evaluating the activation of IκB/NF-κB and MAPK signaling pathways and the production of nitric oxide (NO) and IL-1ß in response to SR-A ligands. In SR-A(-/-) astrocytes, lipopolysaccharide (LPS) induced higher levels of NO and reduced levels of IL-1ß compared to SR-A(+/+) cells. In addition, SR-A(-/-) astrocytes had a reduced basal and LPS-stimulated JNK phosphorylation, and a delayed activation on IκB/NF-κB signaling pathway in response to LPS. Moreover, inhibition of the ERK pathway reduced NO production by SR-A(-/-) cells, suggesting that this signaling pathway modulated LPS-induced NO production, an effect that depended on the presence of SR-A. Our results suggest that SR-A participates in the modulation of signaling pathways involved in the production of soluble molecules implicated in the neuroinflammatory response.

On the mechanism underlying tellurite reduction by Aeromonas caviae ST dihydrolipoamide dehydrogenase.

The dihydrolipoamide dehydrogenase (LpdA) from the tellurite-resistant bacterium Aeromonas caviae ST reduces tellurite to elemental tellurium. To characterize this NADH-dependent activity, the A. caviae lpdA gene was subjected to site-directed mutagenesis and genes containing C45A, H322Y and E354K substitutions were individually transformed into Escherichia coli Δlpd. Cells expressing the modified genes exhibited decreased pyruvate dehydrogenase, dihydrolipoamide dehydrogenase and TR activity regarding that observed with the wild type A. caviae lpdA gene. In addition, cells expressing the altered lpdA genes showed increased oxidative stress levels and tellurite sensitivity than those carrying the wild type counterpart. The involvement of Cys residues in LpdA's TR activity was analyzed using specific inhibitors that interact with catalytic cysteines and/or disulfide bridges such as aurothiomalate, zinc or nickel. TR activity of purified LpdA was drastically affected by these compounds. Since LpdA belongs to the flavoprotein family, the involvement of the FAD/NAD(P)(+)-binding domain in TR activity was determined. FAD removal from purified LpdA results in loss of TR activity, which was restored with exogenously added FAD. Substitutions in E354, involved in FAD/NADH binding, resulted in low TR activity because of flavin loss. Finally, changing H322 (involved in NAD(+)/NADH binding) by tyrosine also resulted in altered TR activity.

Alternativas reconstructivas post maxilectomía por enfermedad neoplásica / Reconstructive alternatives post maxillectomy for oncologic disease

Introducción: La reconstrucción de defectos mediofaciales representa un gran desafío. Los maxilares son los huesos más importantes del esqueleto facial, proveen soporte entre base del cráneo y arcos maxilares, separan cavidades, participan en la deglución, fonación, masticación, visión y apariencia. La maxilectomía conlleva diferentes grados de alteración funcional. La reconstrucción maxilar va desde el uso de prótesis obturadoras, colgajos locales hasta colgajos libres. Objetivo: Presentar las alternativas reconstructivas post maxilectomía por enfermedad neoplásica utilizadas en nuestro centro. Pacientes y Métodos: Análisis retrospectivo de todos los pacientes sometidos a maxilectomía por causa oncológica entre los años 2008 y 2011. Resultados: La serie estuvo compuesta por 12 pacientes, 8 mujeres, mediana de edad 57 años (rango 25-84). Se realizó maxilectomía Tipo IIA a cinco pacientes, Tipo IIB a dos pacientes, Tipo IIIA a cuatro pacientes y IIIB a un paciente. Se logró R0 en todos los casos. La reconstrucción se realizó con prótesis obturadora en cuatro pacientes, tres pacientes con colgajos pediculados y cinco pacientes con colgajos microquirúrgicos. En todos los pacientes se logró un resultado funcional adecuado. En un paciente hubo pérdida parcial del colgajo. Discusión: Es recomendable ajustar la alternativa reconstructiva según el pronóstico del paciente. Prótesis obturadoras son una opción para pacientes seleccionados. El colgajo de músculo temporal presenta un buen resultado funcional, recomendado en pacientes con enfermedad avanzada y mal pronóstico. La reconstrucción microquirúrgica es la alternativa de elección con los mejores resultados funcionales y estéticos en pacientes con maxilectomías Tipo II, III y IV.

The reconstruction of midfacial defects is a major challenge. The maxillary bones are the more important of the facial skeleton, provide support between skull base and maxillary arches, separate cavities and are involved in swallowing, phonation, mastication, vision and appearance. The maxillectomy involves varying degrees of functional impairment. The maxillary reconstruction ranges from the use of obturator prosthesis, local flaps to free flaps. Aim: To present the different reconstructive alternatives used after a maxillectomy for oncologic disease in our hospital. Patients and Methods: Retrospective analysis of all patients that was submitted to a maxillectomy for oncologic disease between 2008 and 2011 in our center. Results: The series consisted of 12 patients, 8 women and median age 57 years (range, 25-84). We realized Type IIA maxillectomy in five patients, IIB to two patients, IIIA to four patients and IIIB to one patient. We achieved R0 in all cases. The reconstruction was realized with obturator prosthesis in four patients, three patients with pedicled flaps and five patients were reconstructed with free flaps. All patients obtain an adequate functional status. One patient has partial flap loss. Discussion: Is recommended adjust the surgical choice to the patient prognosis. The obturator prosthesis is a good choice for selected group. The temporal muscle flap presents adequate functional results and is recommended in advanced disease and poor prognosis. The microsurgical reconstruction is the best choice with better functional and aesthetics outcomes in type II, III and IV maxillectomy.

Tratamiento quirúrgico de los tumores de parótida: experiencia de 10 años / Surgical treatment of parotid neoplasms: a 10 years experience

Background: Parotid neoplasms correspond to 3 percent of head and neck tumors. Most are benign, treatment is parotidectomy. Aims: To analyze the results of treatment, histology, complications and recurrence. Patients and Methods: Retrospective analysis of patients with parotid tumors treated in our center among 2001-2010. Results: The series consisted of 82 patients, 52 (63 percent) women. Average age: 46 years (range, 17-77), 73 (89 percent) had benign tumors, 7 (8.5 percent) were malignant and 2 (2.4 percent) had chronic inflammatory disease. The most common benign tumors were pleomorphic adenoma (55 percent) and Warthin's tumor (20 percent). The most common malignant tumors were mucoepidermoid carcinoma (5 percent) and acinar cell carcinoma (4 percent). The technique was total parotidectomy in 10 patients (12 percent), total suprafacial 53 (64.6 percent) and partial in 19 (23 percent). The most common complication was transient facial nerve dysfunction in the immediate postoperative period in 38 cases (46.3 percent), 14 (17 percent) had surgical bed depression, 15 (18.3 percent), dysesthesia periauricular, 2 (2.4 percent) permanent paralysis of the facial nerve (tumor) and 6 (7.3 percent) Frey Syndrome. No patient had a disagreement with his scar and pain periauricular, there were no recurrences. There was lesser transient facial nerve paralysis with partial suprafacial parotidectomy than with total suprafacial parotidectomy (21 percent and 53 percent), RR 0.4 IC 95 percent (0.16-0.99). Discussion: The application of less invasive surgical techniques such as partial parotidectomy suprafacial allow comparable results in benign conditions, with low morbidity without increasing recurrence.

Introducción: Las neoplasias parotídeas corresponden al 3 por ciento de los tumores de cabeza y cuello. La mayoría son benignas, el tratamiento es la parotidectomía. Objetivo: Analizar los resultados del tratamiento, histología, complicaciones y recurrencia. Pacientes y Métodos: Análisis retrospectivo de los pacientes con tumores parotídeas intervenidos en nuestro centro entre 2001-2010. Resultados: La serie estuvo compuesta por 82 pacientes, 52 (63 por ciento) mujeres. La edad promedio: 46 años (rango, 17-77); 73 (89 por ciento) tuvieron tumores benignos, 7 (8,5 por ciento) malignos y 2 (2,4 por ciento) presentaron enfermedad inflamatoria crónica. Los tumores benignos más frecuentes fueron el adenoma pleomorfo (55 por ciento) y el tumor de Warthin (20 por ciento). Los tumores malignos más frecuentes fueron el carcinoma mucoepidermoide (5 por ciento) y el carcinoma de células acinares (4 por ciento). La técnica fue parotidectomía total en 10 pacientes (12 por ciento), suprafacial total en 53 (64,6 por ciento) y parcial en 19 (23 por ciento). La complicación más frecuente fue la disfunción transitoria del nervio facial en el postoperatorio inmediato en 38 casos (46,3 por ciento); 14 (17 por ciento) presentaron depresión del lecho operatorio, 15 (18,3 por ciento) disestesia periauricular, 2 (2,4 por ciento) parálisis permanente del nervio facial (tumor maligno) y 6 (7,3 por ciento) Síndrome de Frey. Ningún paciente presentó disconformidad con su cicatriz ni dolor periauricular; no hubo recidivas. Se observó menos parálisis transitoria del nervio facial con la parotidectomía suprafacial parcial que con la parotidectomía suprafacial total (21 por ciento y 53 por ciento, respectivamente), RR 0,4 IC 95 por ciento (0,16-0,99). Discusión: La aplicación de técnicas quirúrgicas menos agresivas como la parotidectomía suprafacial parcial permite obtener resultados comparables en patologías benignas, con bajas tasas de morbilidad, sin aumentar la recurrencia.

Laringectomía total ampliada en carcinoma laríngeo avanzado T4a / Total laryngectomy in advanced laryngeal neoplasma T4a

Background: In Chile a significant number of patients is presented with advanced laryngeal cancer at diagnosis with poor prognosis and less than 50% survival at 5 years. Nowadays choosing the organ sparing treatment, but in selected cases total laryngectomy is a valid treatment option. Aim: To present the results obtained with the extended total laryngectomy in patients with advanced laryngeal carcinoma. Patients and Methods: Retrospective analysis of all patients with advanced laryngeal carcinoma T4a underwent total extended laryngectomy at our center between 2007-2010. Results: 18 patients, a woman, a median age 64 years (range, 50-82), they were studied and etapified with Rhino-Laryngo-Fibrescope Olympus© and CT. Seven patients underwent emergency tracheostomy. All patients underwent total extended laryngectomy with primary pharyngeal closure. The median tumor size was 4.3cm. In 17 patients R0 was achieved. Postoperative complication was presented in one patient with a pharyngocutaneous fistula. Thirteen patients were sent to radiotherapy. After a follow-up of 17 months (range, 2-55): one, two and three years of survival was 88.8 percent, 50 percent and 50 percent respectively. Conclusion: In the serie, extended total laryngectomy is a good therapeutic alternative in patients with advanced laryngeal carcinoma, with low surgical morbidity, short hospital stay and favorable survival.

Introducción: En Chile se presenta un importante número de pacientes con cáncer laríngeo avanzado al momento del diagnóstico, con mal pronóstico y una supervivencia menor al 50 por ciento a 5 años. Actualmente, se opta por el tratamiento conservador de órganos, en casos seleccionados la laringectomía total es una alternativa. Objetivo: Presentar los resultados de la laringectomía total ampliada en carcinoma laríngeo avanzado. Pacientes y Método: Análisis retrospectivo de los pacientes con carcinoma laríngeo avanzado T4a sometidos a laringectomía total ampliada en nuestro centro entre 2007-2010. Resultados: La serie estuvo constituida por 18 pacientes, una mujer, mediana de 64 años (rango, 50-82), estudio y etapificación con nasofibroscopia y TC. En siete pacientes se realizó traqueostomía de urgencia. En todos los pacientes se realizó laringectomía total ampliada. El tamaño tumoral fue 4,3 cm como mediana. En 17 pacientes se logró R0. Como complicación un paciente presentó una fístula faringocutánea. Fueron enviados a radioterapia 13 pacientes. Tras un seguimiento de 17 meses (rango, 2-55): la supervivencia a uno, a dos y a tres años fue de 88,8 por ciento, 50 por ciento y 50 por ciento respectivamente. Conclusión: En esta serie, la laringectomía total ampliada es una buena alternativa para los pacientes con carcinoma laríngeo avanzado T4a por su baja morbilidad quirúrgica, corta estadía hospitalaria y supervivencia favorable.

Tumor de cuerpo carotídeo / Carotid body tumor

Carotid body tumors (paragangliomas) are very rare, highly vascularized and usually benign tumors, originated in the carotid body chemoreceptors. We present the cases of two asymptomatic patients referred for left cervical mass; preoperative study was CT and CT angiography, respectively, which are consistent with carotid body tumors. The tumors were completely removed by subadventitial disection without complications; the biopsy was compatible with paraganglioma. No evidence of recurrence could be found.

Los tumores de cuerpo carotídeo (paragangliomas) son neoplasias altamente vascularizadas, muy poco frecuentes y generalmente benignas, originadas en los quimiorreceptores del cuerpo carotídeo. Se presentan los casos de dos pacientes derivados por aumento de volumen cervical izquierdo, asintomáticos, con estudio preoperatorio realizado por TAC y angiografía por TAC, respectivamente, que resultan compatibles con tumores de cuerpo carotídeo. Se resuelven quirúrgicamente, mediante disección subadventicial, informando la biopsia paraganglioma. Los tumores fueron completamente removidos, sin evidencia de recurrencia y sin mayores complicaciones.

Ileal conduit and orthotopic renal transplantation. An alternative in pathology of the nonviable lower urinary tract.

The technique of orthotopic renal transplantation with urinary shunt, using the ileal conduit as an alternative in cases of pathologically nonviable lower urinary tract, is described. Various techniques for heterotopic renal transplantation using the ileal conduit have been used. We feel that orthotopic renal transplantation accompanied by the ileal conduit results in a more anatomical and physiological unit than the previously proposed alternatives.

Tratamiento local en cáncer de recto bajo / Local treatment in low rectal neoplasms

El tratamiento aceptado en el cáncer de recto bajo fue por muchas décadas la amputación abdominoperineal del recto. Posteriormente se propuso, en casos seleccionados, la posibilidad de tratamientos con intención curativa con preservación del aparato esfinteriano. Se presenta nuestra experiencia en una serie de 13 pacientes que fueron sometidos a resección local en disco de tumores malignos de recto bajo. La serie fue intervenida quirúrgicamente entre los años 1981 a 1996. Todos los tumores estaban ubicados en los últimos 7 cm del recto y se ciñeron a criterios estrictos de selección. La técnica quirúrgica utilizada fue la resección de pared total rectal en disco. Todos los pacientes tuvieron límite de sección quirúrgica libre de tumor. No se presentó morbilidad postoperatoria. En cuatro pacientes se presentó recidiva local. Tres de ellos fueron sometidos a operación de Miles. La sobrevida actuarial a 5 años fue de 70 por ciento. Concluimos que la resección local en cáncer de recto bajo es la indicación terapéutica en aquellos pacientes que cumplan rigurosamente los criterios de selección

Reconstitución de tránsito después de la operación de Hartmann con videolaparoscopia asistida / Transit reconstitution after Hartmann operation with assisted videolaparoscopy

Se revisan retrospectivamente los pacientes en quienes se realizó la intervención asistida con laparoscopia en forma consecutiva entre noviembre de 1992 y abril de 1997 y se comparan sus resultados con los de una serie histórica de pacientes intervenidos por los mismos autores con la técnica abierta. Se efectuó el procedimiento en 26 pacientes, 9 mujeres y 17 hombres, con una media de edad de 40 años. En 20 se completó la intervención con asistencia laparoscópica, verificándose la conversión de la cirugía en 6 pacientes (23 por ciento) principalmente por dificultades en el manejo del muñón rectal. No se presentó mortalidad en la serie. Al comparar los resultados con la serie histórica de 26 reconstituciones abiertas se comprobó una disminución significativa de la morbilidad y de la estadía hospitalaria. Se concluye que la asistencia laparoscópica en la reconstitución del tránsito después de la operación de Hartmann se puede considerar como una opción razonablemente segura