Evolution of Drug Resistance: Insight on TEM β-Lactamases Structure and Activity and β-Lactam Antibiotics

Since the discovery of the first penicillin bacterial resistance to β-lactam antibiotics has spread and evolved promoting new resistances to pathogens. The most common mechanism of resistance is the production of β-lactamases that have spread thorough nature and evolve to complex phenotypes like CMT type enzymes. New antibiotics have been introduced in clinical practice, and therefore it becomes necessary a concise summary about their molecular targets, specific use and other properties. β-lactamases are still a major medical concern and they have been extensively studied and described in the scientific literature. Several authors agree that Glu166 should be the general base and Ser70 should perform the nucleophilic attack to the carbon of the carbonyl group of the β-lactam ring. Nevertheless there still is controversy on their catalytic mechanism. TEMs evolve at incredible pace presenting more complex phenotypes due to their tolerance to mutations. These mutations lead to an increasing need of novel, stronger and more specific and stable antibiotics. The present review summarizes key structural, molecular and functional aspects of ESBL, IRT and CMT TEM β-lactamases properties and up to date diagrams of the TEM variants with defined phenotype. The activity and structural characteristics of several available TEMs in the NCBI-PDB are presented, as well as the relation of the various mutated residues and their specific properties and some previously proposed catalytic mechanisms.

Relationship between galactomannan structure and physicochemical properties of films produced thereof

In this work five sources of galactomannans, Adenanthera pavonina, Cyamopsis tetragonolobus, Caesalpinia pulcherrima, Ceratonia siliqua and Sophora japonica, presenting mannose/galactose ratios of 1.3, 1.7, 2.9, 3.4 and 5.6, respectively, were used to produce galactomannan-based films. These films were characterized in terms of: water vapour, oxygen and carbon dioxide permeabilities (WVP, O 2 P and CO 2 P); moisture content, water solubility, contact angle, elongation-at-break (EB), tensile strength (TS) and glass transition temperature (T g ). Results showed that films properties vary according to the galactomannan source (different galactose distribution) and their mannose/galactose ratio. Water affinity of mannan and galactose chains and the intermolecular interactions of mannose backbone should also be considered being factors that affect films properties. This work has shown that knowing mannose/galactose ratio of galactomannans is possible to foresee galactomannan-based edible films properties.

Body image dissatisfaction and its relationship with physical activity and body mass index in Brazilian adolescents

Objective: To evaluate body image dissatisfaction and its relationship with physical activity and body mass index in a Brazilian sample of adolescents. Methods: A total of 275 adolescents (139 boys and 136 girls) between the ages of 14 and 18 years completed measures of body image dissatisfaction through the Contour Drawing Scale and current physical activity by the International Physical Activity Questionnaire. Weight and height were also measured for subsequent calculation of body mass index. Results: Boys and girls differed significantly regarding body image dissatisfaction, with girls reporting higher levels of dissatisfaction. Underweight and eutrophic boys preferred to be heavier, while those overweight preferred be thinner and, in contrast, girls desired to be thinner even when they are of normal weight. Conclusion: Body image dissatisfaction was strictly related to body mass index, but not to physical activity.

Poly(ester-urethane) scaffolds: effect of structure on properties and osteogenic activity of stem cells

The present study aimed to investigate the effect of structure (design and porosity) on the matrix stiffness and osteogenic activity of stem cells cultured on poly(ester-urethane) (PEU) scaffolds. Different three-dimensional (3D) forms of scaffold were prepared from lysine-based PEU using traditional salt-leaching and advanced bioplotting techniques. The resulting scaffolds were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), mercury porosimetry and mechanical testing. The scaffolds had various pore sizes with different designs, and all were thermally stable up to 300â °C. In vitrotests, carried out using rat bone marrow stem cells (BMSCs) for bone tissue engineering, demonstrated better viability and higher cell proliferation on bioplotted scaffolds compared to salt-leached ones, most probably due to their larger and interconnected pores and stiffer nature, as shown by higher compressive moduli, which were measured by compression testing. Similarly, SEM, von Kossa staining and EDX analyses indicated higher amounts of calcium deposition on bioplotted scaffolds during cell culture. It was concluded that the design with larger interconnected porosity and stiffness has an effect on the osteogenic activity of the stem cells.

Regulación transcripcional y relación entre estructura y función de proteínas relacionadas con el metabolismo de colina en Pseudomonas aeruginosa. Transcriptional regulation and relationship between structure and function of proteins related with the choline metabolism in Pseudomonas aeruginosa.

El objetivo general de este proyecto es dilucidar los mecanismos de acción a nivel molecular de enzimas y proteínas involucradas en el metabolismo de colina en Pseudomonas aeruginosa, con énfasis en la identificación de residuos aminoacídicos críticos y regulación de la expresión de los genes en estudio. Los objetivos específicos que se palntean involucran abordajes bioquímicos y moleculares y serán llevados a cabo mediante técnicas de biología molecular y bioquímica (mutación sitio-dirigida, deleción génica, expresión y purificación de proteínas, fusión transcripcional a genes reporteros, etc). Planteo de hipótesis: las proteínas que se inducen por colina (fosforilcolina fosfatasa (PchP), fosfolipasa C (PlcH), acetilcolinestera (AchE), proteínas periplásmicas unidoras de colina (PUch) podrían compartir: a) una organización génica y responder a la regulación por proteínas regulatorias o a factores ambientales de manera similar; b) residuos aminoacídicos conservados que intervengan en la unión o interacción con diferentes ligandos, principalmente, colina. Para ello, se plantean los siguientes Objetivos Específicos: 1) identificar las zonas promotoras de los genes que codifican para PchP, PlcH, AchE y PUch, a fin de localizar posibles sitios de unión a proteínas reguladoras y los factores ambientales que afectan la actividad promotora. 2) determinar en las proteínas mencionadas los residuos aminoacídicos de importancia involucrados en la catálisis y en la interacción con ligandos, principalmente en la unión a compuestos de alquilamonio; 3) Se iniciarán estudios que demuestren la relación entre la inducción por colina de varios factores de patogenicidad la virulencia del microorganismo, empleando mutantes simples o múltiples en estos factores y como modelo de patogenicidad el nematodo C. elegans. A partir de los resultados obtenidos se pretende tener un conocimiento profundo sobre la regulación molecular y bioquímica de varias enzimas comprometidas en la patología que produce P. aeruginosa. Esto más el conocimiento de la fisiología de este microorganismo abre el camino para la búsqueda de posibles blancos de acción de drogas. Por otro lado, se espera tener un conocimiento integral sobre la regulación de la expresión de las actividades enzimáticas relacionadas con el metabolismo de colina y la respuesta de P. aeruginosa ante la presencia de compuestos de alquilamonio utilizados como nutrientes. Se espera conocer el papel que desempeña cada uno de los sitios de unión a los diferentes ligandos para el funcionamiento y control de las enzimas mencionadas y explicar el comportamiento diferencial de las enzimas frente a distintos sustratos y otros ligandos. El conocimiento de los sitios de unión a compuestos de alquilamonio permitirá encontrar esos dominios en diferentes proteínas del género Pseudomonas y otras bacterias Gram negativas. Desde el punto de vista evolutivo, se podrá comparar la similitud de los sitios de unión a colina entre proteínas de organismos eucariotas con procariotas (ej. PUch de bacterias Gram positivas, transportadores de colina, proteína C reactiva, AchE de eucariotas contra las encontradas en bacterias del género Pseudomonas, fosfolipasas A, C o D, etc.). Este proyecto permitirá concretar al menos dos tesis doctorales (Sanchez, Otero) más varios trabajos finales de grado (tesinas) que son y serán realizados por alumnos de la carrera de Microbiología en la UNRC. Les permitirá a los doctorandos y a los alumnos de grado adquirir una formación bastante integral ya que utilizarán herramientas de la fisiología general bacteriana, de la bioquímica clásica, de la biología molecular y de la bioinformática.

Synthesis, structure and catalytic activity of new lanthanide alkynylamidinates

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2015

Thermal biology, activity, and population parameters of Cnemidophorus vacariensis (Squamata, Teiidae), a lizard endemic to southern Brazil

We investigated the following aspects of the biology of a population of Cnemidophorus vacariensis Feltrim & Lema, 2000 during the four seasons: thermal biology, relationship with the thermal environment, daily and seasonal activity, population structure and growth rate. Cnemidophorus vacariensis is restricted to rocky outcrops of the "campos de cima da serra" grasslands on the Araucaria Plateau, southern Brazil, and is currently listed as regionally and nationally threatened with extinction. Data were collected from October 2004 through September 2007 in the state of Rio Grande do Sul. Sampling was conducted randomly from 08:00 a.m. to 6:00 p.m. The capture-mark-recapture method was employed. The lizards were captured by hand, and their cloacal temperature, sex, snout-ventral length (SVL), mass, and the temperature of their microhabitat (substrate temperature and air temperature) were recorded. Individuals were then marked by toe-clipping and released at the site of capture. Body temperatures were obtained for 175 individuals, activity data for 96 individuals, and data on population structure and growth for 59 individuals. All data were obtained monthly, at different times of the day. Cnemidophorus vacariensis average body temperature was 23.84ºC, ranging between 9.6 and 38.2ºC. Temperatures ranged between 21 and 29ºC. The correlation between external heat sources, substrate and air were positive and significant and there was a greater correlation between lizard's temperature and the temperature of the substrate (tigmothermic species). The relatively low body temperatures of individuals are associated with the climate of their environment (altitude up to 1,400 m), with large variations in temperature throughout the day and the year, and low temperatures in winter. The average body temperature observed for C. vacariensis was low when compared with that of phylogenetically related species, suggesting that the thermal biology of this species reflects adaptations to the temperate region where it lives. The monthly rates of activity of lizards were related to monthly variations in the ambient temperatures. Our data suggest that the daily and seasonal activity of C. vacariensis result from the interaction between two factors: changes in the environment temperature and the relationship between individuals and their thermal environment. The population structure of C. vacariensis varied throughout the study period, with maximum biomass in January and maximum density in February (recruitment period). The sex ratio diverged from the expected 1:1. The growth analysis showed a negative relationship between the growth rate of individuals and the SVL, revealing that young individuals grow faster than adults, a typical pattern for short-lived species. The population studied showed a seasonal and cyclical variation associated with the reproductive cycle. The life strategy of C. vacariensis seems to include adaptations to the seasonal variations in temperature, typical of its environment.

Relationship of physical activity with motor skills, aerobic fitness and body fat in preschool children: a cross-sectional and longitudinal study (Ballabeina).

Adiposity, low aerobic fitness and low levels of activity are all associated with clustered cardiovascular disease risk in children and their high prevalence represents a major public health concern. The aim of this study is to investigate the relationship of objectively measured physical activity (PA) with motor skills (agility and balance), aerobic fitness and %body fat in young children. This study is a cross-sectional and longitudinal analyses using mixed linear models. Longitudinal data were adjusted for baseline outcome parameters. In all, 217 healthy preschool children (age 4-6 years, 48% boys) participated in this study. PA (accelerometers), agility (obstacle course), dynamic balance (balance beam), aerobic fitness (20-m shuttle run) and %body fat (bioelectric impedance) at baseline and 9 months later. PA was positively associated with both motor skills and aerobic fitness at baseline as well as with their longitudinal changes. Specifically, only vigorous, but not total or moderate PA, was related to changes in aerobic fitness. Higher PA was associated with less %body fat at baseline, but not with its change. Conversely, baseline motor skills, aerobic fitness or %body fat were not related to changes in PA. In young children, baseline PA was associated with improvements in motor skills and in aerobic fitness, an important determinant of cardiovascular risk.

Cysteine 230 is essential for the structure and activity of the cytotoxic ligand TRAIL.

Unlike other tumor necrosis factor family members, the cytotoxic ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/Apo-2L contains an unpaired cysteine residue (Cys(230)) in its receptor-binding domain. Here we show that the biological activity of both soluble recombinant TRAIL and cell-associated, full-length TRAIL is critically dependent on the presence of Cys(230). Mutation of Cys(230) to alanine or serine strongly affected its ability to kill target cells. Binding to its receptors was decreased by at least 200-fold, and the stability of its trimeric structure was reduced. In recombinant TRAIL, Cys(230) was found engaged either in interchain disulfide bridge formation, resulting in poorly active TRAIL, or in the chelation of one zinc atom per TRAIL trimer in the active, pro-apoptotic form of TRAIL.

Intergenic and external transcribed spacers of ribosomal RNA genes in lizard-infecting Leishmania: molecular structure and phylogenetic relationship to mammal-infecting Leishmania in the subgenus Leishmania (Leishmania)

To establish the relationships of the lizard- and mammal-infecting Leishmania, we characterized the intergenic spacer region of ribosomal RNA genes from L. tarentolae and L. hoogstraali. The organization of these regions is similar to those of other eukaryotes. The intergenic spacer region was approximately 4 kb in L. tarentolae and 5.5 kb in L. hoogstraali. The size difference was due to a greater number of 63-bp repetitive elements in the latter species. This region also contained another element, repeated twice, that had an inverted octanucleotide with the potential to form a stem-loop structure that could be involved in transcription termination or processing events. The ribosomal RNA gene localization showed a distinct pattern with one chromosomal band (2.2 Mb) for L. tarentolae and two (1.5 and 1.3 Mb) for L. hoogstraali. The study also showed sequence differences in the external transcribed region that could be used to distinguish lizard Leishmania from the mammalian Leishmania. The intergenic spacer region structure features found among Leishmania species indicated that lizard and mammalian Leishmania are closely related and support the inclusion of lizard-infecting species into the subgenus Sauroleishmania proposed by Saf'janova in 1982.

Effect of various neutrally adjusted ventilator assist (NAVA) gains on the relationship between diaphragmatic activity (Eadi max) and tidal volume

INTRODUCTION. Neurally Adjusted Ventilatory Assist (NAVA) is an assisted ventilatorymode in which the ventilator is driven by the electrical activity of the diaphragm (Eadi).NAVAimproves patient-ventilator synchrony [1] but little is known about how to set the NAVA gaini.e., how to choose the ratio between Eadi and delivered pressure. The aim of the present studywas to assess the relationship between Eadi and tidal volume (Vt) at various NAVA gainsettings and to evaluate whether modifying the gain influenced this relationship in non-invasivelyventilated (NIV) patients.METHODS. Prospective interventional study comparing 3 values of NAVA gain during NIV(20 min each). NAVA100 was set by the clinician according to the manufacturer's recommendations.In NAVA50 and NAVA150 the gain was set as -50% and +50% of NAVA100gain respectively. Vt and maximal Eadi value (Eadi max) were recorded. The ratio Vt/Eadi wasthen assessed for each breath. 5-95% range (range 90) of Vt/Eadi was calculated for eachpatient at each NAVA gain setting. Vt/Eadi ratio has the advantage to give an objectiveassessment Vt/Eadi max relationship independently from the nature of this relationship. Asmaller Range90 indicates a better matching of Vt to Eadi max.RESULTS. 12 patients were included, 5 had obstructive pulmonary disease and 2 mixedobstructive and restrictive disease. For NAVA100, the median [IQR] Range 90 was 32[19-87]. For NAVA150 Range 90 was 37 [20-95] and for NAVA50 Range 90 was 33 [16-92].That means that globally NAVA100 allowed a better match between Eadi max and Vt thanNAVA50 and 150. However, by patient, NAVA100 had the lowest Range 90 value for only 4patients (33%), NAVA150 for 2 (17%) and NAVA50 for 6 (50%) patients, indicating thatNAVA100 was not the best NAVA gain for minimizing Range 90 in every patients.Comparing the lowest Range 90 value to the next lowest for each patient, showed that 3 patientshad differences of less than 10% (one each for NAVA50, NAVA100 and NAVA150). Theremainder had differences from 17 to 24%, indicating that most patients (9/12 or 75%) had aclear better match between Eadi and Vt for one specific NAVA gain.CONCLUSIONS. Different NAVA gains yielded markedly different ability to match Vt toEadi max. This approach could be a new way to determine optimalNAVAgain for each patientbut require further investigations.REFERENCE. Piquilloud L, et al. Intensive Care Med 2011;37:263-71.

Stock returns, term structure, inflation and real activity: An international perspective

This paper analyses the empirical interdependences among assetreturns, real activity and inflation from a multicountry and internationalpoint of view. We find that nominal stock returns are significantly relatedto inflation only in the US, that the US term structure of interest ratespredicts both domestic and foreign inflation rates while foreign termstructures do not have this predictive power and that innovations in inflationand exchange rates induce insignificant responses of real and financialvariables. An interpretation of the dynamics and some policy implicationsof the results are provided.