Porous Melt Blown Poly(butylene terephthalate) Fibers with High Ductility and High-Temperature Structural Stability.

In this study, porous poly(butylene terephthalate) (PBT) fibers were produced by melt blowing cocontinuous blends of PBT and polystyrene (PS) and selectively extracting the interconnected PS domains. Small amounts of hydroxyl terminated PS additives that can undergo transesterification with the ester units in PBT were added to stabilize the cocontinuous structure during melt processing. The resulting fibers are highly ductile and display fine porous structural features, which persist at temperatures over 150 °C. Single fiber tensile testing and electron microscopy are presented to demonstrate the role of rapid quenching and drawing of the melt blowing process in defining the fiber properties. The templated highly aligned pore structure, which is not easily produced in solvent-based fiber spinning methods, leads to remarkable mechanical properties of the porous fibers and overcomes the notoriously poor tensile properties common to other cellular materials like foams.

Removal of Chromium (III) and Reduction in Toxicity in a Primary Tannery Effluent Using Two Floating Macrophytes.

Trivalent chromium (Cr(III)) is a contaminant with toxic activity. Its presence in waters and soils is usually related to industrial activities such as tanneries. The aim of this study was to compare the removal of Cr(III) in hydroponic solutions and tannery effluents using two floating macrophytes: Salvinia auriculata and Eichhornia crassipes. First, to determine the chromium removal capacity in solution and the bioaccumulation factor (BAF) in tissues of each plant, experiments were set up with contaminated solutions with Cr(III) concentrations of 2, 5, 10, 20, and 40 mg/L. Subsequently, both plant species were exposed to a primary tannery effluent contaminated with 12 mg/L of Cr(III) in order to study the removal capacity of organic and inorganic matter, as well as the acute toxicity in the water flea (Daphnia magna) and genotoxicity in zebrafish (Danio rerio). Tests carried out on nutrient solutions revealed that both plants have a high capacity for removing Cr(III) in solution. The BAF in tissues was higher in E. crassipes compared to S. auriculata. In the experiments with a tannery effluent, both species presented low nutrient and organic matter removal efficiency, but they showed good Cr(III) removal capacity, with average reduction values of 57% for S. auriculata and 54% for E. crassipes after 72 h of exposure. E. crassipes contributed most to the reduction in acute toxicity in D. magna, while S. auriculata did not show a similar effect. However, both plant species managed to reduce the genotoxicity marker in D. rerio when compared with the initial effluent and the control.

Chagas Disease in Pregnant Women from Endemic Regions Attending the Hospital General de Mexico, Mexico City.

Trypanosoma cruzi infection leads to Chagas disease (CD), a neglected tropical infection of significant public health importance in South and Central America and other, non-endemic, countries. Pregnant women and their children are of particular importance to screen as T. cruzi can be transmitted vertically. The objective of this study was to screen for T. cruzi infection among pregnant women from endemic areas seen at the Hospital General de Mexico for prenatal care, so that they and their children may be quickly connected to CD treatment. Pregnant women were recruited through the hospital prenatal clinic and screened for T. cruzi infection using a series of serological and molecular tests. Of 150 screened patients, mean age 26.8 (SD 6.4), 30 (20.0%) were positive by at least one diagnostic test. Of these, only nine (6%) were positive as determined by PCR. Diagnosis of chronic CD is difficult in endemic places like Mexico due to the limitations of current commercially available diagnostic tests. Further evaluation of diagnostic performance of various assays could improve current CD diagnostic algorithms and proper care management in these regions. Genetic variability in the parasite may also play a role in the differing assay performances seen in this study, and this may be a valuable avenue of further research.

PathMolD-AB: Spatiotemporal pathways of protein folding using parallel molecular dynamics with a coarse-grained model.

Solving the protein folding problem (PFP) is one of the grand challenges still open in computational biophysics. Globular proteins are believed to evolve from initial configurations through folding pathways connecting several thermodynamically accessible states in a free energy landscape until reaching its minimum, inhabited by the stable native structures. Despite its huge computational burden, molecular dynamics (MD) is the leading approach in the PFP studies by preserving the Newtonian temporal evolution in the canonical ensemble. Non-trivial improvements are provided by highly parallel implementations of MD in cost-effective GPUs, concomitant to multiscale descriptions of proteins by coarse-grained minimalist models. In this vein, we present the PathMolD-AB framework, a comprehensive software package for massively parallel MD simulations using the canonical ensemble, structural analysis, and visualization of the folding pathways using the minimalist AB-model. It has, also, a tool to compare the results with proteins re-scaled from the PDB. We simulate and analyze, as case studies, the folding of four proteins: 13FIBO, 2GB1, 1PLC and 5ANZ, with 13, 55, 99 and 223 amino acids, respectively. The datasets generated from simulations correspond to the MD evolution of 3500 folding pathways, encompassing 35×106 states, which contains the spatial amino acid positions, the protein free energies and radii of gyration at each time step. Results indicate that the speedup of our approach grows logarithmically with the protein length and, therefore, it is suited for most of the proteins in the PDB. The predicted structures simulated by PathMolD-AB were similar to the re-scaled biological structures, indicating that it is promising for the study of the PFP study.

A benchmark of optimally folded protein structures using integer programming and the 3D-HP-SC model.

The Protein Structure Prediction (PSP) problem comprises, among other issues, forecasting the three-dimensional native structure of proteins using only their primary structure information. Most computational studies in this area use synthetic data instead of real biological data. However, the closer to the real-world, the more the impact of results and their applicability. This work presents 17 real protein sequences extracted from the Protein Data Bank for a benchmark to the PSP problem using the tri-dimensional Hydrophobic-Polar with Side-Chains model (3D-HP-SC). The native structure of these proteins was found by maximizing the number of hydrophobic contacts between the side-chains of amino acids. The problem was treated as an optimization problem and solved by means of an Integer Programming approach. Although the method optimally solves the problem, the processing time has an exponential trend. Therefore, due to computational limitations, the method is a proof-of-concept and it is not applicable to large sequences. For unknown sequences, an upper bound of the number of hydrophobic contacts (using this model) can be found, due to a linear relationship with the number of hydrophobic residues. The comparison between the predicted and the biological structures showed that the highest similarity between them was found with distance thresholds around 5.2-8.2 Å. Both the dataset and the programs developed will be freely available to foster further research in the area.

Murine typhus in Mexico City: report of an imported case.

Murine typhus is endemic in several countries. We herein report an imported case of murine typhus caused by Rickettsia typhi in Mexico City. This is the first report of a case after almost 20 years since the last report. The species was confirmed by DNA sequencing and phylogenetic reconstruction.

Virulence profiles and innate immune responses against highly lethal, multidrug-resistant nosocomial isolates of Acinetobacter baumannii from a tertiary care hospital in Mexico.

Virulence profiles and innate immune responses were studied in Acinetobacter baumannii from nosocomial infections collected over one year in a tertiary care hospital in Mexico. A. baumannii were identified by VITEK 2 System followed by susceptibility tests. Carbapenemase genes, active efflux mechanism to imipenem and meropenem and outer membrane proteins profile were analyzed to evaluate their role on the activity of carbapenem resistance. All isolates were genotyped by pulsed field gel electrophoresis. The ability to form biofilm was determined on a polystyrene surface. The resistance to complement was determined with a pooled human normal serum and TNFα release by infected macrophages was determined by ELISA. The 112 isolates from this study were associated with a 52% of mortality. All were resistance to ß-lactams, fluoroquinolones, and trimethroprim-sulfamethoxal, 96 and 90% were resistant to meropenem and imipenem, respectively, but with high susceptibility to polymyxin B, colistin and tigecyclin. Isolates were classified in 11 different clones. Most isolates, 88% (99/112), were metallo-ß-lactamases and carbapenemases producers, associated in 95% with the presence of blaOXA-72 gene. Only 4/99 and 1/99 of the carbapenem-resistant isolates were related to efflux mechanism to meropenem or imipenem resistance, respectively. The loss of expression of 22, 29, and/or 33-36-kDa proteins was detected in 8/11 of the clinical isolates with resistance to carbapenem. More than 96% (108/112) of the isolates were high producers of biofilms on biotic surfaces. Finally, all isolates showed variable resistance to normal human serum activity and were high inductors of TNFα release by macrophages. In summary, these results suggest that multidrug-resistant A. baumannii can persist in the hospital environment through its ability to form biofilms. The high mortality observed was due to their ability to survive normal human serum activity and capability to induce potent inflammatory immune response making this nosocomial pathogen a serious threat to hospitalized patients.

Surgical Orthodontic Approach for the Retreatment of a High Angle Skeletal Class III Patient: Case Report.

The aim of this article is to describe the retreatment ofa high angle skeletal Class II patient with a moderate anterior crossbite who had previous mandibular orthognathic surgery. A traditional orthodontics/orthognathic surgery approach was selected for treatment. Facial balance was improved, and the final occlusal relationships were good.

A Randomized, Double-Blind, Placebo-Controlled Clinical Trial of a Chemokine Receptor 5 (CCR5) Antagonist to Decrease the Occurrence of Immune Reconstitution Inflammatory Syndrome in HIV-Infection: The CADIRIS Study.

BACKGROUND: Immune Reconstitution Inflammatory Syndrome (IRIS) is a common complication of antiretroviral therapy (ART) in HIV-infected patients. IRIS is associated with an increased risk of hospitalization and death. We ascertained whether CCR5 blockade using maraviroc reduces the risk of IRIS. METHODS: The CADIRIS study was a randomized, double-blind, placebo-controlled, clinical trial that accrued subjects from five clinical sites in Mexico and one in South Africa between November 2009 and January 2012, and followed them for one year. The primary outcome was occurrence of IRIS by 24 weeks. HIV-infected adults, naïve to ART, with CD4 cells <100/µL, and HIVRNA >1,000 copies/mL were eligible. We screened 362 subjects; 279 met inclusion criteria, 3 refused participation, and 276 were randomized. Participants received maraviroc 600 mg twice daily or placebo added to an ART regimen that included tenofovir, emtricitabine, and efavirenz for 48 weeks. FINDINGS: There were 276 patients randomized (140 received maraviroc and 136 placebo). There was no difference in the time to IRIS events between treatment arms (HR 1·08, 95% CI (0·66, 1·77), log-rank test p=0·743). In total, 64 (23%) patients had IRIS events, 33 (24%) in the maraviroc arm and 31 (23%) in the placebo arm (p=0·88). INTERPRETATION: Maraviroc had no significant effect on frequency, time or severity of IRIS events after ART initiation. Including a CCR5 inhibitor in an initial treatment regimen does not confer a meaningful protection from the occurrence of IRIS in persons with advanced HIV infection. FUNDING: The trial was funded as investigator initiated research by Pfizer Inc, New York, NY, USA. TRIAL REGISTRATION: ClinicalTrials.gov. ID: NCT00988780 (http://clinicaltrials.gov/ct2/show/NCT00988780).

Effect of the CCR5 antagonist maraviroc on the occurrence of immune reconstitution inflammatory syndrome in HIV (CADIRIS): a double-blind, randomised, placebo-controlled trial.

BACKGROUND: Immune reconstitution inflammatory syndrome (IRIS) is a common complication of antiretroviral therapy (ART) in patients with HIV. IRIS is associated with an increased risk of admission to hospital and death. We assessed whether CCR5 blockade with maraviroc reduces the risk of IRIS. METHODS: The CADIRIS study was a double-blind, randomised, placebo-controlled trial that recruited participants from five clinical sites in Mexico and one in South Africa and followed them for 1 year. Patients were eligible if they were adults with HIV, who were naive to ART, had CD4 count lower than 100 cells per µL and HIV RNA greater than 1000 copies per mL. Participants were randomly assigned (1:1) by permuted block randomisation to receive either maraviroc (600 mg twice daily) or placebo in addition to an ART regimen that included tenofovir, emtricitabine, and efavirenz for 48 weeks. Patients, care providers, and members of the research team were masked to treatment allocation. Clinical and laboratory evaluations were done at baseline, and weeks 2, 4, 8, 12, 16, 24, 48, and 60. The primary outcome was time to an IRIS event by 24 weeks. All patients who were randomly assigned contributed to the primary time-to-event analysis from the date of ART initiation until week 24, the time of an IRIS event or death. This trial is registered with ClinicalTrials.gov, number NCT00988780. FINDINGS: Between Dec 10, 2009, and Jan 17, 2012, we screened 362 patients; of whom 279 met the inclusion criteria and three refused to participate; thus 276 participants were randomly assigned (140 to receive maraviroc and 136 to receive placebo). 64 (23%) patients had IRIS events, 33 (24%) in the maraviroc group and 31 (23%) in the placebo group (p=0·74). No difference in the time to IRIS events was noted between the treatment groups (HR 1·08, 95% CI 0·66-1·77; log-rank test p=0·74). 37 participants (26%) in the maraviroc group had grade 3 or 4 adverse events compared with 24 (18%) in placebo group; p=0·072); 25 (18%) in the maraviroc group and 21 (15%) in the placebo group had serious treatment emergent adverse events (p=0·63). INTERPRETATION: Maraviroc had no significant effect on development of IRIS after ART initiation. Inclusion of this CCR5 inhibitor in an initial treatment regimen does not confer a meaningful protection from the occurrence of IRIS in people with advanced HIV infection. FUNDING: Pfizer.

Translocation of a tRNA with an extended anticodon through the ribosome.

Coordinated translocation of the tRNA-mRNA complex by the ribosome occurs in a precise, stepwise movement corresponding to a distance of three nucleotides along the mRNA. Frameshift suppressor tRNAs generally contain an extra nucleotide in the anticodon loop and they subvert the normal mechanisms used by the ribosome for frame maintenance. The mechanism by which suppressor tRNAs traverse the ribosome during translocation is poorly understood. Here, we demonstrate translocation of a tRNA by four nucleotides from the A site to the P site, and from the P site to the E site. We show that translocation of a punctuated mRNA is possible with an extra, unpaired nucleotide between codons. Interestingly, the NMR structure of the four nucleotide anticodon stem-loop reveals a conformation different from the canonical tRNA structure. Flexibility within the loop may allow conformational adjustment upon A site binding and for interacting with the four nucleotide codon in order to shift the mRNA reading frame.

Etiology of liver cirrhosis in Mexico.

BACKGROUND: In the last decades it has been suggested that the main cause of liver cirrhosis in Mexico is alcohol. Currently in Western countries hepatitis C virus stage liver disease and liver transplantation. In Mexico, we have no data relative to the etiology of liver cirrhosis. The aim of this study was to investigate the main causes of liver cirrhosis in Mexico. METHODS: Eight hospitals located in different areas of the country were invited to participate in this study. Those hospitals provide health care to different social classes of the country. The inclusion criteria were the presence of either an histological or a clinical and biochemical diagnosis of liver cirrhosis. RESULTS: A total 1,486 cases were included in this study. The etiology of liver cirrhosis was alcohol in 587 (39.5%), HCV 544 (36.6%), cryptogenic 154 (10.4%), PBC 84 (5.7%), HBV 75 (5.0%) and other 42 (2.8%). There was no statistical difference between alcohol and HCV. CONCLUSIONS: We conclude that the main causes of liver cirrhosis in Mexico are alcohol and HCV.

Cirugía biliar en Venezuela: la primera colecistectomía: parte I / Surgery biliary in Venezuela: the primary cholecistectomy: part I

Se presenta como un recuento histórico quirúrgico la realización de la primera Colecistectomia Abierta en Venezuela, realizada por el Dr. Salvador Córdova.

Tumor funcional del órgano de Zuckerkandl: a propósito de un caso / Functional tumor of the organ of Zuckerkandl: to purpose of a case

Describir un caso clínico de tumor funcional del órgano de Zuckerkandl y revisión de la literatura. Descripción de una paciente de 14 años de edad con hipertención juvenil y un paraganglioma funcional del órgano de Zuckerkandl. Se presenta el caso y se revisa la literatura acerca del diagnóstico, terapéutica y pronóstico del tumor funcional del órgano Zuckerkandl. La presencia de hipertensión juvenil severa justifica la exhaustiva búsqueda de un tumor productor de catecolaminas. El tratamiento de los tumores productores de catecolaminas es quirúrgico. La diferenciación entre un paraganglioma benigno o maligno se evidencia por la presencia de metástasis o invasión a órganos adyacentes. El seguimiento de estos pacientes es indispensable por la probable aparición de metástasis o recurrencia muchos años después

Amibiasis del hígado complicada con drenaje espontáneo al pericardio / Amebiasis of the liver complicated with spontaneous drainage to pericrdic space

El objetivo del presente informe es comunicar cuatro casos de amibiasis invasora del hígado que ingresaron al Servicio de Infectología del Hospital General de México durante los años de 1985 a 1987 y que se complicaron con drenaje espontáneo al espacio pericárdico, lo cual fue corroborado con estudios clínicos, serológicos y de imagen que nos dieron la pauta para establecer el tratamiento adecuado tanto médico como quirúrgico. Los datos clínicos de los pacientes fueron, además de los relacionados a la patología hepática, dolor en epigastrio, aparición súbita de disnea, datos de falla cardiaca aguda con disminución de la intensidad de los ruidos cardiacos, así como frote pericárdico. Se presentan los resultados de laboratorio y gabinete y se realiza una comparación con lo consignado en la literatura

Hiperglucemia en el cólera: ¿algo más que una relación casual? / Hyperglycemia in choleric patients: some relationship casual?

En un estudio comparativo, longitudinal y abierto, evaluamos la presencia de hiperglucemia en un grupo de 37 sujetos no diabéticos con diagnóstico de cólera, y lo comparamos con la presencia de dicho fenómeno en un grupo de 18 sujetos en quienes se descartó el cólera. 25 sujetos con cólera (67.5 por ciento) presentaron hiperglucemia, mientras que en el grupo sin cólera, solamente 6 pacientes (33.3 por ciento) la presentaron (P < 0.025) (RR 3.27). Estos hallazgos sugieren una vía por la cual los gérmenes productores de enterotoxina pueden alterar el metabolismo de los carbohidratos, en el artículo se proponen algunas teorías para ello

Carcinoma digestivo en jovenes

Esta es una revisión retrospectiva de las características, manifestaciones clínicas y curso clínico-quirúrgico de los pacientes menores de 40 años que siendo portadores de un carcinoma digestivo, fueron sometidos a una intervención quirúrgica en el Servicio de Cirugía General del Hospital Andrade Marín, en un período de seis anños, comprendido entre enero de 1987 y diciembre de 1992. Se analiza, pues, la incidencia relativa de tumores digestivos malignos en enfermos jóvenes, el diagnóstico preoperatorio, el estadiaje intraoperatorio, los procedimientos quirúrgicos realizados, la morbilidad y la mortalidad perioperatorias y la sobrevida lograda. Se encuentra que el 11.04 de tumores digestivos malignos han estado presentes en personas jóvenes. Los tumores más frecuentes han sido los de estómago. Todos se han encontrado en estadíos abanzados de la enfermedad. Se han utilizado procedimientos quirúrgicos radicales, aprovechando la juventud de los pacientes, obteniéndose una mortalidad perioperatoria de 30 días de 2.7 por ciento.

Quimiorreceptores y homeopatia / Chemoreceptors and homeopathy

Erlich, Langley y Hahnemann describen por primera vez que todas las celulas del organismo presentan quimiorreceptores, que son estimulados por medicamentos y agentes morbosos, como toxinas, virus y hormonas, que van a ocasionar alteraciones, produciendo diversas enfermedades. El desarrollo de los conocimientos actuales sobre quimiorreceptores, nos permite dilucidar la accion de diversos medicamentos llamados homeopaticos y alopaticos. El conocimiento que actualmente se tiene sobre quimiorreceptores que se detectan y saturan con dosis altas de los farmacos, producen una respuesta en signos y sintomas. Estos mismos farmacos proporcionados en dosis minimas bloquean a los quimiorreceptores anteriormente descritos, impidiendo la accion de los agentes morbidos sobre los quimiorreceptores celulares. En homeopatia, las dosis altas son consideradas como tinturas, ya que conservan alta concentracion del farmaco, y las dosis minimas son las diluciones (dinamizaciones) con determinado grado potencial (numero de la dilucion-dinamizacion)