Stress-Responsive Alternative Sigma Factor SigB Plays a Positive Role in the Antifungal Proficiency of Bacillus subtilis.

Different Bacillus species with PGPR (plant growth-promoting rhizobacterium) activity produce potent biofungicides and stimulate plant defense responses against phytopathogenic fungi. However, very little is known about how these PGPRs recognize phytopathogens and exhibit the antifungal response. Here, we report the antagonistic interaction between Bacillus subtilis and the phytopathogenic fungus Fusarium verticillioides We demonstrate that this bacterial-fungal interaction triggers the induction of the SigB transcription factor, the master regulator of B. subtilis stress adaptation. Dual-growth experiments performed with live or dead mycelia or culture supernatants of F. verticillioides showed that SigB was activated and required for the biocontrol of fungal growth. Mutations in the different regulatory pathways of SigB activation in the isogenic background revealed that only the energy-related RsbP-dependent arm of SigB activation was responsible for specific fungal detection and triggering the antagonistic response. The activation of SigB increased the expression of the operon responsible for the production of the antimicrobial cyclic lipopeptide surfactin (the srfA operon). SigB-deficient B. subtilis cultures produced decreased amounts of surfactin, and B. subtilis cultures defective in surfactin production (ΔsrfA) were unable to control the growth of F. verticillioidesIn vivo experiments of seed germination efficiency and early plant growth inhibition in the presence of F. verticillioides confirmed the physiological importance of SigB activity for plant bioprotection.IMPORTANCE Biological control using beneficial bacteria (PGPRs) represents an attractive and environment-friendly alternative to pesticides for controlling plant diseases. Different PGPR Bacillus species produce potent biofungicides and stimulate plant defense responses against phytopathogenic fungi. However, very little is known about how PGPRs recognize phytopathogens and process the antifungal response. Here, we report how B. subtilis triggers the induction of the stress-responsive sigma B transcription factor and the synthesis of the lipopeptide surfactin to fight the phytopathogen. Our findings show the participation of the stress-responsive regulon of PGPR Bacillus in the detection and biocontrol of a phytopathogenic fungus of agronomic impact.

Sugar inhibits the production of the toxins that trigger clostridial gas gangrene.

Histotoxic strains of Clostridium perfringens cause human gas gangrene, a devastating infection during which potent tissue-degrading toxins are produced and secreted. Although this pathogen only grows in anaerobic-nutrient-rich habitats such as deep wounds, very little is known regarding how nutritional signals influence gas gangrene-related toxin production. We hypothesize that sugars, which have been used throughout history to prevent wound infection, may represent a nutritional signal against gas gangrene development. Here we demonstrate, for the first time, that sugars (sucrose, glucose) inhibited the production of the main protein toxins, PLC (alpha-toxin) and PFO (theta-toxin), responsible for the onset and progression of gas gangrene. Transcription analysis experiments using plc-gusA and pfoA-gusA reporter fusions as well as RT-PCR analysis of mRNA transcripts confirmed that sugar represses plc and pfoA expression. In contrast an isogenic C. perfringens strain that is defective in CcpA, the master transcription factor involved in carbon catabolite response, was completely resistant to the sugar-mediated inhibition of PLC and PFO toxin production. Furthermore, the production of PLC and PFO toxins in the ccpA mutant strain was several-fold higher than the toxin production found in the wild type strain. Therefore, CcpA is the primary or unique regulatory protein responsible for the carbon catabolite (sugar) repression of toxin production of this pathogen. The present results are analyzed in the context of the role of CcpA for the development and aggressiveness of clostridial gas gangrene and the well-known, although poorly understood, anti-infective and wound healing effects of sugars and related substances.

Transient Broca's aphasia as feature of an extradural abscess.

Diagnosis of extradural abscesses can be difficult and is often delayed. The case is presented of a 13-year-old girl who was afebrile and had episodes of expressive aphasia, with maintenance of awareness and understanding, lasting for 2-3 minutes and with normal neurologic examination in between. She was found to have a left frontal extradural abscess overlying the region of Broca's area (Brodmann area 44/45) on magnetic resonance imaging. An electroencephalogram showed continuous delta activity in the left frontotemporal region. She made a full recovery after surgical evacuation of pus, which upon culture grew Streptococcus milleri. The possible cause of transient aphasia in this condition is pressure-induced or inflammatory mediator-induced ischemia, with or without associated focal seizures.

Toxic effects of digested, composted and thermally-dried sewage sludge on three plants.

In order to evaluate potential toxic effects of stabilized sewage sludge that are currently applied to agricultural soils, three types of municipal sewage sludge and one pig slurry were subjected to phytotoxicity assays using three plants (Brassica rapa, Lolium perenne and Trifolium pratense). Equivalent batches of aerobically and anaerobically-digested sludge (F) from two municipal wastewater treatment plants, were composted (C) or thermally dried (T). In addition, one anaerobically-digested and thermally-dried pig slurry (P) was tested. A seedling growth test was performed in accordance with the OECD Guideline 208A, using seed emergence and shoot length as endpoints to identify the inhibition of plants growing in increasing doses of sludge. A correlation analysis between EC50 and physico-chemical parameters or the pollutant burden of the biosolids was also calculated. In all tests, lower germination rates were observed for T. pratense than for L. perenne and B. rapa. A moderate stimulatory effect on shoot length at low doses was observed for the three plants. In these wastes, a strong positive correlation was found between higher values of EC50 (less toxicity) and the stability degree of their organic matter, and a negative correlation between EC50 and total N, hydrolysable N or NH4-N content. No correlations were found with heavy metal or organic pollutant content in those wastes. Results indicate that digested sludge, thermally-dried sludge and thermally-dried pig slurry have non-negligible short term phytotoxic effects, and confirm that composting is an effective sludge treatment for the reduction of phytotoxicity.

Colecistectomía laparoscópica: experiencia de 10 años en la Pontificia Universidad Católica de Chile / Laparoscopic cholecystectomy: 10 years at the Hospital Clínico Pontificia Universidad Católica de Chile

La colecistectomía laparoscópica es actualmente el tratamiento de elección de la colelitiasis. Nuestro hospital es un centro docente donde cirujanos en formación junto a sus docentes han participado activamente en el desarrollo de esta técnica desde su inicio en mayo de 1991. El objetivo de este estudio es comunicar la experiencia de 10 años con esta técnica en el Hospital Clínico de la Pontificia Universidad Católica de Chile. Se revisaron las fichas clínicas de los pacientes sometidos a colecistectomía laparoscópica desde mayo de 1991 a mayo de 2001. Se registraron los datos demográficos de cada paciente, presentación clínica, exámenes de laboratorio y radiológicos. Se analizó la información técnica del procedimiento a estudiar y la evolución postoperatoria precoz. La serie se compone de 5063 pacientes. La edad promedio fue de 46 años (7 a 88 años), 3392 de ellos mujeres (67 por ciento). El 75 por ciento de los pacientes ingresó en forma electiva y el 25 por ciento de urgencia. El tiempo operatorio promedio fue de 73 min. Se realizó conversión a cirugía abierta en 7 por ciento de los pacientes siendo los factores de conversión más importantes la edad avanzada y la presencia de colecistitis aguda. La estadía postoperatoria promedio fue de 2,9 días. Complicaciones post operatorias se observaron en el 2 por ciento. 0,2 por ciento de los pacientes de esta serie necesitaron ser reintervenidos. La mortalidad operatoria fue de 0,02 por ciento. La colecistectomía laparoscópica demuestra en este estudio ser una forma de tratamiento seguro y efectivo en pacientes con colelitiasis.

Laparoscopic cholecystectomy is at present the gold standard for the treatment of gallstones disease. Since May 1991 this technique has been developed at the Hospital Clínico Pontificia Universidad Católica de Chile in patients under the care of staff surgeons of the Digestive Surgery Department who have been actively involved in post graduate surgical training. The purpose of this study is to communicate the experience in 10 years with this technique in our institution. Clinical charts were reviewed of those patients who underwent laparoscopic cholecystectomy since May 1991 until May 2001. Patient's demographic data were included in the analysis, together with their clinical presentation, laboratory exams and radiological information. The technical information of this procedure and the early course of these patients was also analyzed. Our study includes 5063 patients. The age average was 46 years (7 to 88 years old), 3392 of them female (67 percent). 75 percent of these patients underwent elective surgery, while the other 25 percent emergency surgery. The average operative time was of 73 min. Laparoscopic surgery was converted to open laparotomy in 7 percent of these cases. Advanced age and the presence of acute cholecystitis were the main significant associated conversion factors. The average postoperative recovery time in hospital was 2,9 days. Post operative complications were observed in 2 percent. 0,2 percent of patients of this serie had to be reoperated. The mortality rate was 0,02 percent. Laparoscopic cholecystectomy proves to be a safe and effective treatment in patients with gallstones disease.

Correlación clínica, quirúrgica y anatomopatológica en pacientes con diagnóstico de apendicitis aguda: Hospital Patrocinio Peñuela Ruíz 2000-2005 / Clinical correlation, surgical and anatomopathologic in patients hospitalized with diagnosis of acute appendicitis: Hospital Dr. Patrocinio Peñuela Ruíz 2000-2005

La apendicitis constituye una de las causas más frecuentes de abdomen agudo y la indicación más común para laparotomía de urgencia. En el Hospital Dr. Patrocinio Peñuela Ruíz, entre los años 2000 y 2005, se practicaron 760 apendicectomías. Debido al elevado número de cirugías y con la finalidad de mejorar su manejo hospitalario, se plantea realizar esta investigación de tipo retrospectivo, transversal descriptivo y observacional; que tiene como objetivo determinar la correlación entre manifestaciones clínicas, hallazgos operatorios y descripción anatomopatológica de los apéndices cecales de pacientes hospitalizados con diagnóstico de abdomen agudo quirúrgico infeccioso: apendicitis aguda, a quienes se les realizó apendicectomía. El grupo etáreo mas frecuente fue entre 11 y 15 años, predominó el sexo masculino con 54 por ciento, el motivo de consulta más frecuente fue dolor abdominal (90 por ciento); los principales síntomas: dolor abdominal 100 por ciento, vómito 56 por ciento y fiebre 31 por ciento. Entre la aparición de los síntomas y el momento de la cirugía, transcurrieron entre 25 y 30 horas en 25 por ciento de los pacientes. Se reportaron la mayor cantidad de apendicitis en fase flegmonosa entre las 12-24 horas. Como hallazgos operatorios se evidenció: 53 por ciento apédices en fase flegmonosa, la localización más frecuente: retrocecal (23 por ciento), con 52 por ciento sin líquido en cavidad abdominal. En los hallazgos anatomopatológicos: fase flegmonosa en 35 por ciento, congestiva 29 por ciento y gangrenosa 2 por ciento, la correlación entre el diagnóstico quirúrgico y el anatomopatológico se presentó en la fase congestiva en el 89 por ciento, en la flegmonosa en el 72 por ciento también hubo correlación; y en la gangrenosa y perforada, en el 100 por ciento no hubo correlación.

Aislamientos microbiológicos en el Hospital Patrocinio Peñuela Ruíz: Estado Táchira 2005 / Microbiological isolation in the Hospital Patrocinio Peñuela Ruíz: Tachira State 2005

El cultivo de microorganismos es un proceso que permite el aislamiento de los gérmenes causantes o asociados a una infección. Con el aislamiento del germen no solamente se documenta el agente etiológico, sino que éste se tiene disponible para realizar pruebas de tipificación, determinación de sensibilidad a antibióticos y capacidad bactericida de líquidos corporales. En el Hospital Patrocinio Peñuela Ruíz, durante el año 2005, se realizaron 850 aislamientos microbiológicos, por lo que se plantea realizar una investigación de tipo transversal, retrospectivo, descriptivo y observacional, que tiene como objetivo determinar la prevalencia de los microorganismos aislados, a través de los cultivos secreciones, durante enero-diciembre 2005. Los principales resultados son que el mayor porcentaje (50,42) fue realizado en mujeres. La tendencia a realizar toma de muestra para aislamiento microbiológico es en los extremos de la vida, con un 23,05 por ciento en las personas mayores de 60 años y un 11,16 por ciento en los menores de 12 años. El 43,17 por ciento resultaron positivos para algún microorganismo aislado. El principal microorganismo aislado por servicio y otros departamentos fue: en pediatría Staphylococcus aureus (8.03 por ciento), en la Emergencia pediátrica Staphylococcus aureus (8.33 por ciento). En Medicina Interna Staphylococcus aureus 11,73 por ciento, en la Emergencia de Adultos staphylococcus aureus 18,07 por ciento, en Traumatología pseudomona aeurinosa y el staphylococcus aureos con 7,69 por ciento cada una. En Cirugía pseudomona aeruginosa (17,05 por ciento), en gineco-obstetricia e.coli (23,53 por ciento), y para terminar, en la Unidad de Cuidados Intensivos, Pseudomona aeruginosa 15,97 por ciento. También gracias a esta investigación, se pudo determinar la sensibilidad o resistencia antibiótica de los principales microorganismos aislados.

Conductas expresadas por madres cuidadoras ante afecciones clínicas básicas: Municipio Rivas Davila del estado Mérida: agosto-octubre 2005 / Behaviors expressed by caregivers to mothers basic conditions: Municipality Rivas Davila of the State Merida: august-october 2005

En Venezuela gran parte de la población infantil menor de 6 años son dejadas al cuidado de Madres Cuidadoras en Hogares y Multihogares de Cuidado Diario, cuya cobertura para el 2003 alcanzó 300 mil infantes inscritos. Con el objetivo de evaluar las conductas que siguen las madres cuidadoras ante afecciones clínicas presentadas en los niños a su cargo, se diseño una investigación transversal, descriptivo y observacional, basada en un modelo de serie clínica prospectivo mediante la aplicación de encuestas, realizada en Multihogares y Hogares de Cuidados Diario del Municipio Rivas Dávila (Tovar, Estado Mérida), evaluando sus procedimientos ante la fiebre, conocimiento sobre signos o síntomas de alarma ante cuadro febril, actuación en caso de Enfermedad Respiratoria Aguda y Enfermedad Diarreica Aguda, finalmente, su actuación frente a caídas y golpes en la cabeza. En cuanto a fiebre, el 64,1 por ciento demostró tener una conducta inadecuada; en relación a conocimientos sobre signos de alarma, el 82 por ciento demostró tener información correcta acerca de esta situación; frente a la identificación y manejo de la infección respiratoria aguda y de diarrea, el 66,6 por ciento realizarían un manejo inadecuado en ambas patología; por último, en casos de caídas y golpes en la cabeza, el 58,9 por ciento actuaría de manera inadecuada. Se impone re-evaluar las técnicas de enseñanza empleada para la capacitación de este personal pues se evidenciaron graves deficiencias en los conocimientos exhibidos por las Madres Cuidadoras.

Exploración laparoscópica de la vía biliar en coledocolitiasis residual / Laparoscopic exploration of the biliary tract in residual choledocolitiasis

Actualmente el tratamiento de primera elección de la coledocolitiasis en pacientes colecistectomizados es la extracción de éstos a través de una colangiopancreatografía retrógrada endoscópica (CPRE). En los casos en que esto no es posible realizar la alternativa es la exploración de la vía biliar (VB) por cirugía abierta. Durante una colecistectomía laparoscópica (CL) es posible explorar la VB por vía trascística o a través de una coledocotomía. En el presente trabajo se presenta la experiencia en el tratamiento laparoscópico de la coledocolitiasis en un paciente colecistectomizado. Se le extrajo un cálculo de la VB distal a través de una coledocotomía laparoscópica y se instaló una endoprótesis biliar. Es dada de alta en buenas condiciones, se retira la endoprótesis a través de una endoscopia sin incidentes. En pacientes colecistectomizados, es posible realizar una exploración de la VB por vía laparoscópica como alternativa a la CPRE

Polychlorinated biphenyls in nonaccumulating, century-old sediments: sources, signatures, and mechanism of introduction.

This study documents the occurrence of highly chlorinated PCB congeners in stream sediment deposited over 100 years ago. Penta- to heptachlorinated congeners (> 80%) have been found at concentrations up to 78.8 ng/g (dw) in core samples of a small, rural tributary of Lake Ontario. Lower chlorinated congeners and other organochlorine compounds occur sporadically; 210Pb and 137Cs are lacking. The most plausible mechanism is accumulation of dissolved-phase PCBs in permeable sediments adjacent to the creek channel. The similarity between core and air samples collected in the drainage basin suggests derivation from a residual fraction of atmospherically derived PCB congeners.

Photopolymerized, multilaminated matrix devices with optimized nonuniform initial concentration profiles to control drug release.

This paper describes a novel approach to obtain desired release profiles from diffusion-controlled matrix devices by employing nonuniform initial concentration profiles theoretically and experimentally. Theoretically, a model was developed to examine the effect of nonuniform initial concentration profiles on matrix release behavior, and an optimization technique was investigated to determine suitable nonuniform initial concentration profiles which provide desired release patterns. Experimentally, release rates of an organic dye from photopolymerized matrix devices were measured to test the application of these mathematical techniques and the efficacy of photolaminated matrices in approximating the optimized release behavior. All system parameters were measured by independent experiments, and the experimental release data agree very well with the computed results.

Mathematical modeling and optimization of cellulase protein production using Trichoderma reesei RL-P37.

The enzyme cellulase, a multienzyme complex made up of several proteins, catalyzes the conversion of cellulose to glucose in an enzymatic hydrolysis-based biomass-to-ethanol process. Production of cellulase enzyme proteins in large quantities using the fungus Trichoderma reesei requires understanding the dynamics of growth and enzyme production. The method of neural network parameter function modeling, which combines the approximation capabilities of neural networks with fundamental process knowledge, is utilized to develop a mathematical model of this dynamic system. In addition, kinetic models are also developed. Laboratory data from bench-scale fermentations involving growth and protein production by T. reesei on lactose and xylose are used to estimate the parameters in these models. The relative performances of the various models and the results of optimizing these models on two different performance measures are presented. An approximately 33% lower root-mean-squared error (RMSE) in protein predictions and about 40% lower total RMSE is obtained with the neural network-based model as opposed to kinetic models. Using the neural network-based model, the RMSE in predicting optimal conditions for two performance indices, is about 67% and 40% lower, respectively, when compared with the kinetic models. Thus, both model predictions and optimization results from the neural network-based model are found to be closer to the experimental data than the kinetic models developed in this work. It is shown that the neural network parameter function modeling method can be useful as a "macromodeling" technique to rapidly develop dynamic models of a process.

Three-dimensional modeling, estimation, and fault diagnosis of spacecraft air contaminants.

A description is given of the design and implementation of a method to track the presence of air contaminants aboard a spacecraft using an accurate physical model and of a procedure that would raise alarms when certain tolerance levels are exceeded. Because our objective is to monitor the contaminants in real time, we make use of a state estimation procedure that filters measurements from a sensor system and arrives at an optimal estimate of the state of the system. The model essentially consists of a convection-diffusion equation in three dimensions, solved implicitly using the principle of operator splitting, and uses a flowfield obtained by the solution of the Navier-Stokes equations for the cabin geometry, assuming steady-state conditions. A novel implicit Kalman filter has been used for fault detection, a procedure that is an efficient way to track the state of the system and that uses the sparse nature of the state transition matrices.

Application of ultrasonic backscattering for level measurement and process monitoring of expanded-bed adsorption columns.

Expanded-bed adsorption is a newly commercialized technique for the purification of proteins from cellular debris in downstream processing. An expanded bed presents the possibility of protein recovery in a single step, eliminating the often costly clarification processing steps such as ultrafiltration, centrifugation, and precipitation. A major obstacle to the successful commercialization of this technology is the inability to accurately monitor and control the bed height in these systems. Fluctuations in the feedstock viscosity are common during normal operation and tend to make the operation and control of expanded beds for biological applications complex and difficult. We develop a level measurement technique based upon ultrasonics. It is shown that this technique has great promise for bed-height measurement in expanded-bed adsorption systems. Furthermore, the bed-height measurement can be used in feedback control strategies for bed-height regulation. The proposed ultrasonic sensor is also capable of monitoring for plugging and bubbling in the column.

Air-quality monitoring and detection of air contamination in an enclosed environment.

We report on the development of an air-quality monitoring and early detection system for an enclosed environment with specific emphasis on manned spacecraft. The proposed monitoring approach is based on a distributed parameter model of contaminant dispersion and real-time contaminant concentration measurements. Kalman filtering is identified as a suitable method for generating on-line estimation of the spatial contamination profile, and an implicit Kalman filtering algorithm is shown to be preferable for rear-time implementation. The identification of the contaminant concentration profile allows for a straightforward solution of the early detection of an air contamination event and provides information that enables potential automatic diagnosis of an unknown contamination source.

Implicit Kalman filtering.

For an implicitly defined discrete system, a new algorithm for Kalman filtering is developed and an efficient numerical implementation scheme is proposed. Unlike the traditional explicit approach, the implicit filter can be readily applied to ill-conditioned systems and allows for generalization to descriptor systems. The implementation of the implicit filter depends on the solution of the congruence matrix equation (A1)(Px)(AT1) = Py. We develop a general iterative method for the solution of this equation, and prove necessary and sufficient conditions for convergence. It is shown that when the system matrices of an implicit system are sparse, the implicit Kalman filter requires significantly less computer time and storage to implement as compared to the traditional explicit Kalman filter. Simulation results are presented to illustrate and substantiate the theoretical developments.

Modeling and optimization of a batch process for in vitro RNA production.

RNA molecules are commonly produced in vitro by transcription, utilizing a DNA template, an RNA polymerase enzyme, and nucleoside triphosphate substrates (NTPs). In addition to the full-length RNA molecule coded for by the DNA template, significant amounts of shorter RNA molecules are produced. A simplified model of this complex transcription process is presented, with the shorter RNA molecules lumped into a single pool. The rate equations do not depend on the stoichiometry of the RNA molecule of interest, which facilitates application of the model to other RNA molecules. Optimal initial conditions for batch in vitro RNA transcription to produce a dodecamer RNA containing three different nucleotides have been predicted using the model. The predicted optimal values for equimolar NTPs are 10 to 15 mM initial concentration for each NTP and 50 to 60 mM for magnesium acetate, yielding a maximum final dodecamer concentration of 0.8 +/- 0.1 mM at the 90% confidence interval. Experimental data agree well with the model results. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 210-220, 1997.

Inhalation risk in low-gravity spacecraft.

Inhalation risks on long-duration manned spaced flight include gasses chronically released by outgassing of materials, gasses released during spills, thermodegradation events (including fires) with their attendant particulates, and fire extinguishment. As an example, an event in which electronic insulation consisting of polytetrafluoroethylene undergoes thermodegradation on the Space Station Freedom was modeled experimentally and theoretically from the initial chemistry and convective transport through pulmonary deposition in humans. The low-gravity environment was found to impact various stages of event simulation. Critical unknowns were identified, and these include the extent of production of ultrafine particles and polymeric products at the source in low gravity, the transport of ultrafine particles in the spacecraft air quality control system, and the biological response of the lung, including alveolar macrophages, to this inhalation risk in low gravity.

Trisomy 8 and 11 in refractory anemia with excess blasts in transformation (RAEB-T).

There are no specific chromosomal abnormalities associated with refractory anemia with excess blasts in transformation [RAEB-T]. An 80-year-old white male with RAEB-T was found to have trisomies of chromosomes 8 and 11, i.e., 48,XY,+8,+11. To our knowledge, this chromosomal abnormality in RAEB-T has not been previously reported.