Loss of function of metabolic traits in typhoidal Salmonella without apparent genome degradation.

Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars are exclusively adapted to the human host, where they can cause life-long persistent infection. A distinct feature of these serovars is the presence of a relatively high number of degraded coding sequences coding for metabolic pathways, most likely a consequence of their adaptation to a single host. As a result of convergent evolution, these serovars shared many of the degraded coding sequences although often affecting different genes in the same metabolic pathway. However, there are several coding sequences that appear intact in one serovar while clearly degraded in the other, suggesting differences in their metabolic capabilities. Here, we examined the functionality of metabolic pathways that appear intact in S. Typhi but that show clear signs of degradation in S. Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. Thus, the inability of S. Typhi to metabolize Glucose-6-Phosphate or 3-phosphoglyceric acid is due to the silencing of the expression of the genes encoding the transporters for these compounds due to point mutations in the transcriptional regulatory proteins. In contrast, its inability to utilize glucarate or galactarate is due to the presence of point mutations in the transporter and enzymes necessary for the metabolism of these sugars. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted S. enterica serovars and highlight a limitation of bioinformatic approaches to predict metabolic capabilities. IMPORTANCE: Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars can only infect the human host, where they can cause life-long persistent infection. Because of their adaptation to the human host, these bacterial pathogens have changed their metabolism, leading to the loss of their ability to utilize certain nutrients. In this study we examined the functionality of metabolic pathways that appear intact in S. Typhi but that show clear signs of degradation in S. Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted S. enterica serovars.

Loss of function of metabolic traits in typhoidal Salmonella without apparent genome degradation.

Salmonella enterica serovar Typhi and Paratyphi A are the cause of typhoid and paratyphoid fever in humans, which are systemic life-threatening illnesses. Both serovars are exclusively adapted to the human host, where they can cause life-long persistent infection. A distinct feature of these serovars is the presence of a relatively high number of degraded coding sequences coding for metabolic pathways, most likely a consequence of their adaptation to a single host. As a result of convergent evolution, these serovars shared many of the degraded coding sequences although often affecting different genes in the same metabolic pathway. However, there are several coding sequences that appear intact in one serovar while clearly degraded in the other, suggesting differences in their metabolic capabilities. Here, we examined the functionality of metabolic pathways that appear intact in S . Typhi but that show clear signs of degradation in S . Paratyphi A. We found that, in all cases, the existence of single amino acid substitutions in S. Typhi metabolic enzymes, transporters, or transcription regulators resulted in the inactivation of these metabolic pathways. Thus, the inability of S . Typhi to metabolize Glucose-6-Phosphate or 3-phosphoglyceric acid is due to the silencing of the expression of the genes encoding the transporters for these compounds due to point mutations in the transcriptional regulatory proteins. In contrast, its inability to utilize glucarate or galactarate is due to the presence of point mutations in the transporter and enzymes necessary for the metabolism of these sugars. These studies provide additional support for the concept of adaptive convergent evolution of these two human-adapted Salmonella enterica serovars and highlight a limitation of bioinformatic approaches to predict metabolic capabilities.

Cryo-EM structure of the bacterial effector protein SipA bound to F-actin reveals a unique mechanism for filament stabilization.

The bacterial pathogen Salmonella spp. modulates cellular processes by delivering effector proteins through its type III secretion systems. Among these effectors, SipA facilitates bacterial invasion and promotes intestinal inflammation. The mechanisms by which this effector carries out these functions are incompletely understood although SipA's ability to modulate actin dynamics is central to some of these activities. Here we report the cryo-EM structure of SipA bound to filamentous actin. We show that this effector stabilizes actin filaments through unique interactions of its carboxy terminal domain with four actin subunits. Furthermore, our structure-function studies revealed that SipA's actin-binding activity is independent from its ability to stimulate intestinal inflammation. Overall, these studies illuminate critical aspects of Salmonella pathogenesis, and provide unique insight into the mechanisms by which a bacterial effector modulates actin dynamics.

Tratamiento quirúrgico del quiste óseo solitario con el empleo de la hidroxiapatita / Solitary Bone Cyst Surgical Treatment with the Use of Hydroxyapatite

El quiste óseo solitario es una lesión seudotumoral que se presenta predominantemente en la metáfisis de huesos largos de niños y adolescentes. El tratamiento actual estándar es el injerto óseo autólogo, sin embargo, sus tasas de no unión, morbilidad en el sitio de toma del injerto y la limitada cantidad con que se cuenta, así como, la no presencia de un banco de tejidos, fomentan el surgimiento de diferentes alternativas al mismo. Se presentaron dos pacientes en los cuales se utilizó la hidroxiapatita HAP-200 como sostén en la resección de seudotumores óseos benignos, teniendo en cuenta la curación ósea y la reincorporación rápida a la vida social. Se le realizaron exámenes clínicos, radiográficos y posteriormente histopatológicos que permitieron confirmar el diagnóstico, para luego realizar curetaje quirúrgico o exéresis de la lesión y relleno de la cavidad con hidroxiapatita. En todos los casos en los que se realizó este tipo de tratamiento tuvo efectividad máxima la terapéutica utilizada como alternativa de injerto óseo con una respuesta hueso-implantación u osteointegración. Los pacientes tuvieron una excelente resolución ósea, lo que confirmó la alta biocompatibilidad y poder osteoconductor de la hidroxiapatita porosa coralina HAP-200.

The solitary bone cyst is a tumor lesion that occurs predominantly in the metaphyses of long bones in children and adolescents. The current standard treatment is autologous bone graft, however, their rates of nonunion, morbidity site takes the graft and the limited amount that is counted and the non-presence of a tissue bank, encourage emergence of alternatives. Two patients, in whom hydroxyapatite HAP-200 was used as a support in the resection of benign bone pseudotumors, considering bone healing and rapid return to social life were presented. Clinical, radiographic and histopathological examinations were performed subsequently that allowed to confirm the diagnosis, and then make surgical performance or excision of the lesion and filling the cavity with hydroxyapatite. In all cases in which this type of therapy was performed a great effectiveness of the treatment was observed as an alternative therapy for bone graft with a bone-implantation or osseointegration response. Patients had excellent bone resolution, which confirmed the high biocompatibility and osteoconductive power of coral porous hydroxyapatite HAP-200.

Fractura de la eminencia intercondílea / Intercondylar Eminence Fracture

La eminencia intercondílea o espina tibial, está entre las carillas articulares interna y externa de la superficie superior del extremo proximal de la tibia. Las fracturas a este nivel aparecen con mayor frecuencia en niños de 8 a 13 años y por lo común no se las detecta en menores de 7 años, son esencialmente avulsiones de los ligamentos cruzados con un fragmento de hueso unido. Se presentó una paciente de 13 años de edad que sufrió un accidente del tránsito, en el cual recibe trauma de rodilla izquierda, diagnosticándole una fractura de la eminencia intercondilea. Se le realizó reducción y osteosíntesis con micro tornillo AO a través de una vía de acceso anteromedial. La evolución fue satisfactoria, alcanzando una adecuada fijación de la fractura, así como, una recuperación funcional total. Este tipo de fractura requiere un diagnóstico preciso, puede ser tratada conservadoramente, pero con el tratamiento quirúrgico se obtienen excelentes resultados.

The intercondylar eminence or tibia spine is between the inner and outer of the upper surface of the proximal end of the tibia. Fractures at this level appear more frequently in children aged 8-13 years, and usually they are not detected under seven years old. These fractures are essentially avulsions of the crossed ligaments with joint bone fragment. A 13- year-old patient was presented, who suffered a traffic accident, and as a result of this she got a left knee trauma. A fracture of the intercondylar eminence was diagnosed. The patient underwent reduction and internal fixation with AO micro screw through an anteromedial access. The evolution was satisfactory, achieving adequate fracture fixation, as well as full functional recovery. This is a type of fracture that requires an accurate diagnosis and can be treated conservatively, but with surgery excellent results can be achieved.

PARÁMETROS FISICOQUÍMICOS PARA LA SÍNTESIS DE ÁCIDO LÁCTICO O ETANOL DE LA BACTERIA (Corynebacterium glutamicum) / Physico-Chemical Parameter for Production of Lactic Acid or Ethanol of (Corynebacterium glutamicum) Bacteria

El interés por obtener productos para la industria de biocombustibles a partir de desechos agrícolas, conduce a la búsqueda de nuevos sistemas biotecnológicos resistentes y costo-efectivos. Corynebacterium glutamicum, es un microorganismo usado para producir amino-ácidos que crece en gran variedad de sustratos y es resistente durante la fermentación, a variaciones de pH, temperatura, presión osmótica y acumulación de alcohol, características que lo hacen candidato a ser mejorado para la síntesis de ácido láctico y etanol. Aún se desconocen aspectos de su fisiología que aumenten su eficiencia en convertir azúcares (C5 y C6) en estos dos metabolitos. Por tanto, este trabajo buscó identificar los parámetros fisicoquímicos que tuvieron un mayor efecto sobre crecimiento bacteriano y síntesis de ácido láctico o etanol en un sistema por lotes. Para lograr este objetivo, ocho variables fueron evaluadas en un modelo estadístico producido en erlenmeyer; con los resultados obtenidos, se hallaron las mejores condiciones que fueron puestas a prueba en un cultivo en biorreactor. La temperatura, concentración de biotina y azúcar fueron las variables de mayor impacto (p< 0,05). Usando las mejores condiciones, 36 °C; 6,1 mg/L de biotina y 50 g/L de glucosa, se obtiene una µmax de 0,394 h-1, 16 g/L de ácido láctico a las 15 h del proceso con un rendimiento del 32%; observándose un mayor consumo de sustrato durante el crecimiento y poca disponibilidad para la fermentación, sugiriendo una alimentación del cultivo al final de la fase exponencial que aumente los rendimientos de producción.

The interest to obtain products for the bio-fuel industry from renewable resources has directed research to find resistant and costs-effective biotechnological systems. Corynebacterium glutamicum, is a microorganism used to produce amino acids, that grows in wide variety of substrates and its resistance during fermentation to pH, temperature, osmotic pressure variations and alcohol aggregate, renders this organism a suitable candidate to improve by genetic modifications lactic acid and ethanol synthesis. However, some aspects of its physiology remain unknown, such us increase lactic acid and ethanol production from C5 and C6 sugars. For this reason, the main aim in our work was to identify the most important variables with impact on culture and the best culture conditions to produce lactic acid or ethanol in batch culture. To achieve this objective, eight variables were tested in culture using a statistical model. The best culture conditions were obtained and tested in a bacth biorreactor system. Temperature, biotin and glucose concentration were the variables with most impact (p< 0.05) in culture. Using optimal conditions, 36 °C; 6.1 mg/L of biotin and 50 g/L of glucose; a µmax of 0.394 h-1, 16 g/L of lactic acid was obtained after 15 h of culture with an efficiency of 32%. High glucose consumption was observed during bacterial growth, which leads to low concentration of substrate for the production process; this suggests a culture feeding at the end of exponential growth phase, which can increase the production yield.