Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress.

BACKGROUND: Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.

Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress

BACKGROUND: Salmonella Typhimurium is a Gram negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S . Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild type strain, suggesting that ompX mRNA is also regulated at a post transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2 induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.

Análisis de supervivencia de carcinoma escamoso de laringe en una cohorte retrospectiva chilena del Hospital Carlos Van Buren de Valparaíso / Survival analysis of laryngeal squamous cell carcinoma in a chilean retrospective cohort at the Carlos Van Buren Hospital of Valparaíso

Resumen Introducción: El cáncer laríngeo es una de las neoplasias de cabeza y cuello más frecuentes, asociado al envejecimiento y a los hábitos de vida. Los análisis de supervivencia de cáncer laríngeo en Chile son escasos. Objetivo: Calcular y analizar la supervivencia y las características clínicas del cáncer laríngeo en pacientes del Servicio de Otorrinolaringología del Hospital Carlos Van Buren, Valparaíso, Chile. Material y Método: Se realizó un estudio retrospectivo de cohorte, incluyendo pacientes diagnosticados con carcinoma escamoso de laringe entre 2007 y 2018. Se calculó la supervivencia con el método de Kaplan-Meier. Se aplicaron las pruebas de log rank, t de Student y exacta de Fisher. Resultados: Se incluyeron 211 pacientes, 90,52% hombres, con un promedio de edad de 68 años. El factor de riesgo más frecuente fue el tabaquismo. La ubicación tumoral más frecuente fue la glotis (59,44%) y el motivo de consulta más común la disfonía (52,66%). Un 70,48% presentó estadios avanzados. En 23,92% se realizó laringectomía total como tratamiento primario. La supervivencia global a 2 años fue de 86,6% en estadio precoz y 45,2% en estadio avanzado, mientras que a 5 años fue de 77,4% y 33%, respectivamente. Conclusión: La supervivencia estimada fue menor que en otros estudios nacionales, lo que puede asociarse al tamaño de la muestra analizada, a factores etarios y/o a mayor latencia de inicio de tratamiento. Se enfatiza el mejoramiento de los registros clínicos y la gestión sanitaria para un manejo oportuno.

Abstract Introduction: Laryngeal carcinoma is one of the most frequent head and neck neoplasms, being associated with ageing and lifestyles. In Chile, survival analyses of laryngeal carcinoma are scarce. Aim: To estimate and analyze the survival and clinical characteristics of laryngeal carcinoma in patients attended at the Otorhinolaryngology Department of the Carlos Van Buren Hospital, Valparaíso, Chile. Material and Method: We conducted a retrospective cohort study, including patients diagnosed with laryngeal squamous cell carcinoma between 2007 and 2018. Kaplan-Meier estimator was applied for survival analysis. Log rank test, Student's t-test and Fisher's exact test were applied. Results: 211 patients were included, 90,52% were men, with an average age of 68 years. The main risk factor was smoking (80%). The most frequent tumor location was in the glottis (59,44%) and the most frequent reason for consultation was dysphonia (52,66%). Most cases (70,48%) presented at advanced stages. Laryngectomy was performed as a primary treatment in 23,92%. The 2-year overall survival rate was 86,6% for early stages and 45,2% for advanced stages; the 5-year overall survival rate was 77,4% and 33%, respectively. Conclusion: The estimated survival rate was lower than those referred by other national studies, which may be associated with the analyzed sample size, age-related factors and/or period of latency until the beginning of treatment. We emphasize the necessity of an improvement in clinical records and the health management to the timely treatment.

Carcinoma sebáceo extraocular, reporte de un caso / Extraocular sebaceous carcinoma, case report

RESUMEN El carcinoma sebáceo es una neoplasia anexial poco común que puede originarse en cualquier lugar del cuerpo donde existan glándulas sebáceas, siendo la principal ubicación la cabeza y el cuello, existiendo la presentación ocular y extraocular. Alcanza entre 0,2% a 4,6% de todas las neoplasias cutáneas malignas, con mayor incidencia en los adultos mayores caucásicos. La presentación clínica habitual corresponde a un nódulo duro o quístico subcutáneo eritematoso o amarillento, indoloro, de crecimiento acelerado. Sin embargo, puede manifestarse como una amplia gama de lesiones cutáneas, lo que, agregado a su baja incidencia, sea altamente subdiagnosticado. Se presenta el caso de un paciente de 64 años con tumor exofítico malar izquierdo con ulceraciones y áreas de necrosis en la superficie, sin compromiso de párpado inferior, de agudeza visual ni motilidad ocular. Se realiza resección del tumor, cuya biopsia definitiva confirma diagnóstico de carcinoma sebáceo extraocular.

ABSTRACT Sebaceous carcinoma is a rare anexal neoplasm that can develop on any part of the body containing sebaceous glands, but nearly the 70% of sebaceous carcinoma occur on the head and neck, being two ways of presentation, ocular and extraocular. It represents 0.2-4.6 % of all malignant neoplastic cutaneous lesions, whit a peak incidence in the eighth decades of life, in caucasian people. Typical clinical presentation of sebaceous carcinoma is a painless, firm or cystic subcutaneous nodule described as pink to red-yellow, however clinical features can be quite varied, which added to its low incidence leads to the diagnosis is often delayed for months to years. We present the case of a 64 years old patient whit an exofitic malar tumor ulcerated and necrotic in the surface, without compromising the lower eyelid, vision or ocular mobility. The biopsy of the tumor resection shows an extraocular sebaceous carcinoma.

Tumor triquilemal proliferante: reporte de un caso y revisión de la literatura / Trichilemmal proliferating tumor: case report and literature review

RESUMEN El tumor triquilemal proliferante es una neoplasia poco frecuente, usualmente sólida o parcialmente quística que se origina de la vaina externa de la raíz de un folículo piloso. Ocurre principalmente como una lesión solitaria en el cuero cabelludo de mujeres mayores. Presentamos el caso de una mujer de 56 años con un tumor cervical de nueve años de evolución. El estudio de la pieza de resección confirmó el diagnóstico.

ABSTRACT Trichilemmal proliferating tumor is an infrequent neoplasia, usually solid or partially cystic, originating in the external root sheath of hair follicle. It occurs mainly as a solitary lesion in the scalp in older women. We report the case of a 56 years old woman with a cervical tumor of nine years of growth. Histology of the resection specimen confirmed the diagnosis.

Carcinoma adenoide quístico de cavidad nasal y senos paranasales: experiencia de 5 años en Clínica Las Condes de Santiago de Chile / Adenoid cystic carcinoma of nasal cavity and paranasal sinuses: 5 years experience in las Condes Clinic of Santiago of Chile

RESUMEN Introducción: El carcinoma adenoide quístico es una neoplasia originada en glándulas exocrinas de todo el cuerpo, principalmente en glándulas salivales mayores. En cavidad nasal y senos paranasales es poco frecuente y se caracteriza por presentar una alta frecuencia de recurrencia y de metástasis a distancia posterior a su remisión y a pesar de su tratamiento. Objetivo: Describir características de una serie de casos de pacientes con carcinoma adenoide quístico de cavidad nasal y senos paranasales operados. Material y método: Estudio descriptivo-retrospectivo. Período enero de 2012 y enero de 2017. La información se obtuvo a partir de las fichas electrónicas de la Clínica Las Condes. Se describen procedencia, edad y sexo, características clínicas, hallazgos anatomopatológicos, métodos diagnósticos, tratamiento, evolución. Resultados: Total de 5 pacientes operados, 3 mujeres y 2 hombres. La edad promedio fue de 63 años, con rango de 33 años a 90 años de edad. 100% de los casos sin factores asociados. La presentación clínica más frecuente fue la obstrucción nasal unilateral, seguida por el dolor facial. Dos pacientes se presentaron con diagnóstico inicial, dos por recurrencia y uno por persistencia. En tres casos el tumor se origina de seno maxilar y en dos en seno etmoidal. Todos presentaron enfermedad avanzada, etapa IV y III. Tres pacientes histológicamente fueron de bajo grado y dos de alto grado. En los cinco casos el tratamiento primario fue quirúrgico, en el 60% endoscópico, 20% abierto y 20% combinado. En cuatro casos se usó radioterapia posoperatoria y en tres de éstos, quimioterapia concomitante. Todos se encuentran sin signos de recidiva tumoral en último control. Conclusiones: El carcinoma adenoide quístico de cavidad nasal y senos paranasales es bastante infrecuente, su incidencia es menor a 1/100.000 casos por año. Es más frecuente en mujeres entre 40 y 50 años. Se identifica más con su origen en el seno maxilar (50%) y de patrón cribiforme. Clínicamente se presenta en estadíos avanzados ya que en etapa precoz es asintomático o presenta clínica inespecífica inflamatoria. El diagnóstico se realiza con biopsia complementada con imagenología. El tratamiento más utilizado es la cirugía endoscópica o abierta asociado a radioterapia posoperatoria, a pesar de la cual, se presentan con alta recurrencia a largo plazo.

ABSTRACT Introduction: Adenoid Cystic Carcinoma is a neoplasm originating in exocrine glands throughout the body, mainly in the major salivary glands. In the nasal cavity and paranasal sinuses is rare and characterized by a high frequency of recurrence and distant metastasis after remission and despite its treatment. Aim: To describe characteristics of a series of patients with operated adenoid cystic carcinoma of the nasal cavity and paranasal sinuses. Material and method: Descriptive-retrospective study. Period January 2012 and January 2017. The information was obtained from the electronic tabs of the Las Condes Clinic. It describes origin, age and sex, clinical characteristics, anatomopathological findings, diagnostic methods, treatment, evolution. Results: Total 5 patients operated, 3 women and 2 men. The average age was 63 years, ranging from 33 years to 90 years of age. 100% of the cases without associated factors. The most frequent clinical presentation was unilateral nasal obstruction, followed by facial pain. 2 patients presented with initial diagnosis, 2 due to recurrence and 1 due to persistence. In 3 cases the tumor originates from the maxillary sinus and in 2 in the ethmoidal sinus. All had advanced disease, stage IV and III. 3 patients were histologically low grade and 2 high grade. In all 5 cases, the primary treatment was surgical, 60% endoscopic, 20% open and 20% combined. In 4 cases, postoperative radiotherapy was used and in 3 of this concomitant chemotherapy. All are without signs of tumor recurrence in the last control. Conclusion: Adenoid Cystic Carcinoma of the nasal cavity and paranasal sinuses is quite infrequent; its incidence is less than 1/100,000 cases per year. It is more common in women between 40 and 50 years. It is identified more with its origin in the maxillary sinus (50%) and cribriform pattern. Clinically it presents in advanced stages since at an early stage, it is asymptomatic or it presents nonspecific inflammatory clinic. Diagnosis is performed with biopsy supplemented with imaging. The most commonly used treatment is endoscopic or open surgery associated with postoperative radiotherapy, despite which, they present with high recurrence in the long term.

Telangiectasia hemorrágica hereditaria: a propósito de un caso clínico / Hereditary hemorrhagic telangiectasia: on the subject of a clinical case

La epistaxis, es un síntoma frecuente en la consulta de otorrinolaringología. Dentro de las causas posibles encontramos la telangiectasia hemorrágica hereditaria (síndrome de Rendu Osler Weber), que corresponde a un desorden autosómico dominante caracterizado por sangrados nasales y gastrointestinales asociados a malformaciones arteriovenosas sistémicas. Su manifestación más frecuente es la epistaxis, presentándose más frecuentemente en personas mayores de 40 años, sin predilección por género. Se presenta el caso de un paciente de sexo masculino de 46 años quien consulta por epistaxis a repetición y severa. Durante la hospitalización se efectúa el tratamiento convencional de la epistaxis, diagnóstico retroactivo del síndrome de Rendu Osler Weber y manejo multidisciplinario de la patología. Se realiza revisión de la literatura y discusión del manejo del paciente que cursa con esta enfermedad.

Epistaxis is a common symptom in the otorhinolaryngology consultation. Among the possible causes are hereditary hemorrhagic telangiectasia (Rendu Osler Weber syndrome), which corresponds to an autosomal dominant disorder characterized by nasal and gastrointestinal bleeding associated with systemic arteriovenous malformations. Its most frequent manifestation is epistaxis, presenting more frequently in people over 40 years of age, without gender preference. We present the case of a male patient of 46 years old who consults for recurrence and severe epistaxis. During hospitalization, conventional treatment of epistaxis, retroactive diagnosis of Rendu Osler Weber syndrome and multidisciplinary management of pathology are performed. We review the literature and discuss the management of patients with this disease.

Mecanismos de comunicación en pacientes laringectomizados / Communication mechanisms in laringectomized patients

RESUMEN El cáncer laríngeo representa el 25% de las neoplasias de cabeza y cuello. Para los carcinomas laríngeos T1 tratados con radioterapia o cirugía láser, no existe diferencia significativa en cuanto a la calidad de voz percibida por el paciente entre ambas formas terapéuticas. La laringectomía total sigue siendo utilizada como la alternativa terapéutica en carcinomas avanzados. La pérdida de la capacidad de fonación es una consecuencia de esta cirugía, por lo que existe un variado abanico de mecanismos de comunicación que ofrecerle al paciente. Las alternativas clásicas comprenden: erigmofonación, laringe electrónica y válvula traqueoesofágica. Dentro de este escenario, han surgido nuevas alternativas en los últimos años como son conversión estadística de voz GMM (Gaussian Mixture Model), proyecto SWARA y el proyecto "Mi propia voz".

ABSTRACT Laryngeal cancer accounts for 25% of head and neck cancers. For T1 laryngeal carcinomas treated with radiotherapy or laser surgery, there is no significant difference in terms of quality of voice perceived by the patient between both therapeutic forms. The total laryngectomy is still used as the therapeutic alternative in advanced carcinomas. The loss of the phonation ability is a consequence of the surgery, so there is a diverse range of communication mechanisms to offer to the patient. Classical approaches include: esophageal speech, electrolarynx and tracheoesophageal valve. In this scenario, new alternatives have emerged: statistical voice conversion GMM (Gaussian Mixture Model), SWARA project and "Mi propia voz" project.

Importancia de la epidemiología en cáncer laríngeo: incidencia y mortalidad por carcinoma escamoso de laringe / Importance of epidemiology in laryngeal cancer: incidence and mortality due to squamous cell carcinoma of the larynx

Actualmente se realiza un diagnóstico anual de 650.000 nuevos casos de carcinoma escamoso de cabeza y cuello en el mundo, siendo el carcinoma escamoso de laringe una patología neoplásica que compete al otorrinolaringólogo. La incidencia mundial del cáncer escamoso de laringe se estima en 3,9 por cada 100.000 habitantes con una mortalidad general de 2,0 por cada 100.000 habitantes. En Chile el registro de cáncer se realiza en base a los cinco registros poblacionales de cáncer que existen. No se tienen datos exactos respecto a incidencia y mortalidad por carcinoma escamoso de laringe, siendo la estimación de la incidencia de 1,2 casos por cada 100.000 habitantes y la estimación de mortalidad ajustada por edad de 0,7 casos por cada 100.000 habitantes. Se han descrito diversos factores de riesgo ambientales y estilos de vida para este cáncer, por lo tanto, las estrategias de prevención primaria en salud son claves a la hora de generar un impacto en la incidencia del carcinoma escamoso de laringe.

The annual diagnosis of head and neck squamous cell carcinoma is 650,000 new cases. The laryngeal carcinoma is a malignant disease that should include an otolaryngologist in its evaluation. The global incidence of laryngeal carcinoma is estimated at 3.9 per 100,000 inhabitants with an overall mortality rate of 2.0 per 100,000 inhabitants. In Chile the cancer registry is based on the five population cancer registries that exist. There is no accurate data on incidence and mortality from laryngeal carcinoma, being an estimated incidence of 1.2 cases per 100,000 inhabitants and an age-adjusted mortality of 0.7 cases per 100.00 inhabitants. There have been described various environmental risk factors and lifestyles for this cancer, therefore, primary prevention strategies are key to generate an impact on the incidence of larynx carcinoma.

Tumores del espacio parafaríngeo: revisión del tema / Parapharyngeal space tumors: review

Los tumores del espacio parafaríngeo son poco frecuentes, por lo tanto existe experiencia publicada limitada respecto a su diagnóstico y tratamiento. Por este motivo, representan un reto diagnóstico y terapéutico. En la mayoría de los casos se puede llegar a un diagnóstico con una adecuada anamnesis, examen físico, imagenología, y complementando con punción aspirativa con aguja fina. La diferenciación entre un tumor preestiloídeo de uno retroestiloídeo es fundamental para orientar el diagnóstico diferencial. El tratamiento de elección es la escisión quirúrgica, advirtiendo al paciente las posibles vías de abordaje, la comorbilidad asociada a cada una de estas vías, sobre todo a nivel de función de nervios craneanos, y la eventual necesidad de coadyuvancia en caso de requerirse.

Parapharyngeal space tumors are rare, so there is limited published experience regarding their diagnosis and treatment. Therefore, they represent a diagnostic and therapeutic challenge. In most cases, diagnosis can be made with an adequate anamnesis, physical examination, imaging, and the use of fine needle aspiration. Differentiation between prestyloid and poststyloid tumor is a key to guiding the differential diagnosis. The treatment of choice is surgical excision, warning the patient the possible surgical approaches, comorbidity associated with each of these pathways, especially at the level of function of cranial nerves, and the eventual need of coadjuvant treatment if required.

Expresión y actividad de proteínas de multirresistencia a drogas (MDR) en líneas celulares de cáncer de próstata / Expression and activity of multidrug resistance proteins in prostate cancer cell lines

Introducción: Nuestro grupo ha reportado previamente una asociación entre sensibilidad a quimioterapia y la expresión de proteínas MDR (P-Gp y MRP1) en líneas celulares y cultivos primarios de cáncer de próstata, quedando por estudiar la actividad de las mismas. Material y métodos: Se utilizó líneas celulares de cáncer de próstata PC3 y DU145. Se evaluaron los niveles de mARN de P-Gp y MRP1 mediante RT-PCR. La expresión de ambas proteínas se determinó mediante inmunofluorescencia. Se estableció un ensayo funcional en base a la acumulación de sustratos fluorescentes (DiOC2(3) para P-gp y CFDA para MRP1) y al uso de inhibidores específicos para cada proteína (Ciclosporina A para P-Gp y MK571 para MRP1). Las células se incubaron durante 60 minutos a 37ºC con o sin el inhibidor específico, seguido de otra incubación por 60 minutos agregando el sustrato fluorescente. La acumulación del sustrato fluorescente se determinó por citometría de flujo. Resultados: Las líneas celulares utilizadas sólo expresaron MRP1, mientras no se detectó P-Gp (mARN ni proteína). Mediante el ensayo funcional se observó que las células acumulaban más CFDA cuando eran tratadas con MK571. No se observó diferencias en la acumulación de DiOC(2)3 frente al tratamiento con Ciclosporina A. Conclusión: La mayor acumulación intracelular de CFDA frente al tratamiento con MK571 indica que la proteína MRP1 expresada en las líneas celulares utilizadas es funcional. P-Gp no se expresa en las líneas evaluadas. En estudios en curso nos encontramos evaluando la expresión y función de ambas proteínas en cultivos primarios.

Introduction: We have previously reported an association between sensitivity to chemotherapy and the expression of multidrug resistance proteins (MDR) (P-Gp and MRP1) in cell lines and primary cultures of prostate cancer. Activity remains to be studied. Material and methods: Prostate cancer cell lines PC3 and DU145 were used. Levels of mRNA of P-Gpand MRP1 using RT-PCR, were evaluated. The expression of both proteins was determined using immunofluorescence. A functional assay based on the accumulation of fluorescence substrates (DiOC2(3) for P-Gp and CFDA for MRP1) was established. Cells were incubated for 60 minutes at 37C with/without the specific inhibitor, followed by another 60 minutes incubation adding the fluorescence substrate. Accumulation of fluorescence substrate was determined by flow citometry. Results: Cell lines expressed only MRP1, whereas P-Gp (mRNA/protein) was not detected. Using the functional assay, we found that cells accumulated more CFDA when treated with MK571. No differences were seen in the accumulation of DiOC2(3) after treatment with ciclosporin A. Conclusion: The higher intracellular accumulation of CFDA after treatment with MK571 indicates that the MRP1 protein expressed in these cell lines is functional. P-Gp was not expressed in these cell lines. We are currently evaluating the expression and function of both proteins in primary cultures.

Protective effect of the dental pellicle against erosive challenges in situ.

The acquired dental pellicle helps prevent erosion, but the protection level is unknown. This in situ study tested whether a two-hour pellicle protects against different erosive challenges by orange juice. Subjects wore palatal appliances loaded with either enamel or dentin specimens. Pellicle was allowed to form, or not (control), on the surfaces of the specimens intra-orally for 2 hrs before the erosive challenges of 0 (control), 10, 20, and 30 minutes' duration. Specimens were randomly removed from the appliances after each challenge. Percentage of surface microhardness change (%SMC) was determined for the enamel specimens, and that of mineral loss and lesion depth for the dentin specimens. Enamel specimens with the pellicle showed a significantly lower %SMC, only after the 10-minute challenge. No protection was found for dentin. It was concluded that the acquired pellicle reduced dental erosion, but that this effect was limited to the less severe erosive challenge on enamel surfaces.

Influence of the organic matrix on root dentine erosion by citric acid.

This investigation was conducted in an attempt to clarify the role of the organic matrix in bovine dentine demineralisation by 1% citric acid. Dentine slabs (n = 15) were treated for 2 min with 10% sodium hypochlorite (NaOCl, a strong protein solvent), 2% glutaraldehyde (GDA, a protein fixative) or deionised water (DIW, as negative control) prior to each of 5 demineralisation periods of 30 min. The mineral loss (DeltaZ), lesion depth (LD) and surface loss (SL) were determined after each period of demineralisation, by transverse microradiography. The NaOCl-treated group showed higher DeltaZ and LD than the GDA- and DIW-treated groups. No differences between GDA and DIW groups were found. The DeltaZ and LD profiles were explained by quadratic fits (r(2) >0.80; p = 0.001) in all groups. SL was detected only in the NaOCl-treated group. The data suggested that the maintenance of the organic matrix in the lesion might be important to reduce the erosion progression rate.

Scanning electron microscopy analysis of corrosion degradation on tinplate substrates.

The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanning electron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates.

Aneurismas de M1. Anatomía microquirúrgica. Estrategia quirúrgica / M1 aneurysms. Microsurgical anatomy. Surgical strategy

Los aneurismas de la arteria cerebral media (ACM) comprenden el 20 por ciento de todos los aneurismas intracraneanos; aquellos localizados en el segmento M1, entre el 2 y el 10 por ciento de los casos. La ACM es una de las arterias cerebrales que presentan más variantes, tanto en curso, como en su morfometría, por lo que para el cirujano neurovascular es muy importante el tener un conocimiento importante de los aspectos microquirúrgicos, variantes y tipos de abordajes a estas lesiones. A pesar de los grandes adelantos en las técnicas microquirúrgicas, cirugía de base, neuroanestesiología, la morbi-mortalidad continúa siendo alta en estas lesiones. Palabras claves: arteria cerebral media, aneurisma, microcirugía, estrategia quirúrgica.

[Hepatitis B among health workers]. / Hepatitis B en trabajadores de salud.

BACKGROUND: Hepatitis B virus (HBV) infection is one of the infectious diseases whose elimination or eradication is possible. However, it is still a serious problem among health workers who are an important risk group to acquire this infection. OBJECTIVE: To focus the problem of the HBV infection among health workers in terms of the risks and prevention alternatives, showing effective strategies to this effect. DATA SOURCE: Analysis of related publications through the MEDLINE system and the review of scientific journals, both in English and Spanish. SYNTHESIS OF INFORMATION: An available and effective vaccine against HBV exist more than 10 years ago. Some national hospitals have demonstrated the prevalence of HBV infection in apparently healthy staff, which evidences that it is an occupational problem. The vaccination of this risk group has proved to reduce the HBV infection in several centers in different countries, in addition to the cost-effectiveness of this measure. CONCLUSION: HBV infection constitutes a significant problem in our country considering its intermediate high endemic rate. No effective measures for its control have been taken, despite the availability of effective vaccines and strategies for the control and prevention of this disease, not to mention their economic benefits.

Mengiomas / Mengiomas

Este artículo contempla una revisión de la literatura sobre la patogénesis e histopatología de los meningiomas y su comportamiento radiológico; las clasificaciones en tipos histológicos y de la Organización Mundial de la Salud que permite establecer las características tumorales para conocer su comportamiento y probabilidades de recurrencia. Dentro de los factores predisponentes está el antecedente de tratamientos con radioterapia, enfermedades genéticas como la Neurofibromatosis tipo 2 y defectos del Cromosoma 22. Las características radiológicas tales como lobulaciones, extensión del edema peritumoral, tamaño del tumor, la delimitación tumoral con respecto al parenquima subyacente entre otros son, importantes para tratar de establecer el comportamiento biológico de estos tumores y en algunos casos predecir el tipo histológico. Se presentan los casos ilustrados con su resumen clínico, imagenes radiológicas y su respectiva histopatología como primera etapa de este estudio prospectivo de un año. Palabras clave: Tumores cerebrales, meningioma, comportamiento biológico, edema peritumoral

Prevalence of antibody to human T cell lymphotropic virus types 1/2 among aboriginal groups inhabiting northern Argentina and the Amazon region of Peru.

We carried out a seroepidemiologic survey to define the prevalence of human T cell lymphotropic virus types 1/2 (HTLV-1/2) infections among aboriginal populations from isolated regions of northern Argentina and the Amazon region of Peru. Antibodies against HTLV were measured with agglutination tests and confirmed with by an immunofluorescence assay (IFA) and Western blotting. Five (6.94%) of 72 samples from the Tobas Indians in Argentina were positive by the IFA; two samples were typed as HTLV-1 (2.78%), two as HTLV-2 (2.78%), and one (1.39%) could not be typed because it had similar antibody titers against both viruses. No positive samples were found among 84 Andinos Puneños and 47 Matacos Wichis Indians. Seroprevalences of 2.50% (1 of 40) and 1.43% (1 of 70) for HTLV-1 were observed among Wayku and San Francisco communities in the Amazon region of Peru, and seroprevalences of 4.54% (1 of 22) and 2.38% (1 of 42) for HTLV-2 were observed among Boca Colorada and Galilea communities. No serologic evidence of human immunodeficiency virus (HIV) infection was found among the Indians tested. These results indicated the presence of HTLV-1 and HTLV-2 in the indigenous populations of Argentina and Peru. Moreover, the lack of HIV infection indicates that the virus has probably not yet been introduced into these populations.

Mayaro virus disease: an emerging mosquito-borne zoonosis in tropical South America.

This report describes the clinical, laboratory, and epidemiological findings on 27 cases of Mayaro virus (MV) disease, an emerging mosquito-borne viral illness that is endemic in rural areas of tropical South America. MV disease is a nonfatal, dengue-like illness characterized by fever, chills, headache, eye pain, generalized myalgia, arthralgia, diarrhea, vomiting, and rash of 3-5 days' duration. Severe joint pain is a prominent feature of this illness; the arthralgia sometimes persists for months and can be quite incapacitating. Cases of two visitors from the United States, who developed MV disease during visits to eastern Peru, are reported. MV disease and dengue are difficult to differentiate clinically.