Analysis of pathogenic bacteria using exogenous volatile organic compound metabolites and optical sensor detection

A novel, low-cost and simple method for the detection of pathogenic bacteria is proposed. The approach is based on the generation of an exogenous volatile organic compound (VOC) produced by the addition of an enzyme substrate to the bacterial sample. The generated VOC is then trapped in agarose gel allowing colour development to take place; visual detection is then possible by both the naked eye and by colorimetric analysis. Agarose gel has been evaluated as both a suitable VOC trapping matrix and host for the colour-generating reagents. This proof of concept method allowed for the discrimination between β-glucosidase and β-alanyl aminopeptidase producing bacteria. Enterococcus faecium and Klebsiella pneumoniae are both β-glucosidase producers and generated a yellow colour within agarose gels upon enzymatic hydrolysis of 2-nitrophenyl-β-D-glucoside. Pseudomonas aeruginosa is a known β-alanyl aminopeptidase producer and was shown to hydrolyse the trifluoroacetic acid (TFA) salt of 3-amino-N-phenylpropanamide resulting in the development of an orange colour within agarose gels spiked with the sodium salt of 1,2-naphthoquinone-4-sulfonic acid. 3-Amino-N-phenylpropanamide (as its TFA salt) and 2-nitrophenyl-β-D-glucoside concentrations of 20 μg mL−1 (or 72 μmol L−1) and 100 μg mL−1 (or 332 μmol L−1), respectively were the minimum quantities required for colour production following 18 h of incubation. The use of 3-amino-N-phenylpropanamide, TFA salt indicated that synthesised enzyme substrates can be tailor-made to liberate exogenous VOCs for colour generation

Drawing cartoon faces - a functional imaging study of the cognitive neuroscience of drawing

We report a functional imaging study of drawing cartoon faces. Normal, untrained participants were scanned while viewing simple black and white cartoon line-drawings of human faces, retaining them for a short memory interval, and then drawing them without vision of their hand or the paper. Specific encoding and retention of information about the faces was tested for by contrasting these two stages (with display of cartoon faces) against the exploration and retention of random dot stimuli. Drawing was contrasted between conditions in which only memory of a previously viewed face was available versus a condition in which both memory and simultaneous viewing of the cartoon was possible, and versus drawing of a new, previously unseen, face. We show that the encoding of cartoon faces powerfully activates the face sensitive areas of the lateral occipital cortex and the fusiform gyrus, but there is no significant activation in these areas during the retention interval. Activity in both areas was also high when drawing the displayed cartoons. Drawing from memory activates areas in posterior parietal cortex and frontal areas. This activity is consistent with the encoding and retention of the spatial information about the face to be drawn as a visuo-motor action plan, either representing a series of targets for ocular fixation or as spatial targets for the drawing actio

In vitro determination of hemoglobin A1c for diabetes diagnosis and management: technology update

It is fascinating to consider the analytical improvements that have occurred since glycated hemoglobin was first used in routine clinical laboratories for diabetes monitoring around 1977; at that time methods displayed poor precision, there were no calibrators or material with assayed values for quality control purposes. This review outlines the major improvements in hemoglobin A1c (HbA1c) measurement that have occurred since its introduction, and reflects on the increased importance of this hemoglobin fraction in the monitoring of glycemic control. The use of HbA1c as a diagnostic tool is discussed in addition to its use in monitoring the patient with diabetes; the biochemistry of HbA1c formation is described, and how these changes to the hemoglobin molecule have been used to develop methods to measure this fraction. Standardization of HbA1c is described in detail; the development of the IFCC Reference Measurement Procedure for HbA1c has enabled global standardization to be achieved which has allowed global targets to be set for glycemic control and diagnosis. The importance of factors that may interfere in the measurement of HbA1c are highlighted

Regulated mitochondrial DNA replication during oocyte maturation is essential for successful porcine embryonic development.

Cellular ATP is mainly generated through mitochondrial oxidative phosphorylation, which is dependent on mitochondrial DNA (mtDNA). We have previously demonstrated the importance of oocyte mtDNA for porcine and human fertilization. However, the role of nuclear-encoded mitochondrial replication factors during oocyte and embryo development is not yet understood. We have analyzed two key factors, mitochondrial transcription factor A (TFAM) and polymerase gamma (POLG), to determine their role in oocyte and early embryo development. Competent and incompetent oocytes, as determined by brilliant cresyl blue (BCB) dye, were assessed intermittently during the maturation process for TFAM and POLG mRNA using real-time RT-PCR, for TFAM and POLG protein using immunocytochemistry, and for mtDNA copy number using real-time PCR. Analysis was also carried out following treatment of maturing oocytes with the mtDNA replication inhibitor, 2',3'-dideoxycytidine (ddC). Following in vitro fertilization, preimplantation embryos were also analyzed. Despite increased levels of TFAM and POLG mRNA and protein at the four-cell stage, no increase in mtDNA copy number was observed in early preimplantation development. To compensate for this, mtDNA appeared to be replicated during oocyte maturation. However, significant differences in nuclear-encoded regulatory protein expression were observed between BCB(+) and BCB(-) oocytes and between untreated oocytes and those treated with ddC. These changes resulted in delayed mtDNA replication, which correlated to reduced fertilization and embryonic development. We therefore conclude that adherence to the regulation of the timing of mtDNA replication during oocyte maturation is essential for successful embryonic development

Demonstration of earlier detection of Salmonella species from stool samples by using chromogenic media

Background: Salmonellosis is a worldwide public health issue and non-typhoid species are one of the most common causative agents of gastroenteritis in the western world.1 Typhoidal and Paratyphoidal salmonellae cause systemic syndromes characterised by sustained bacteraemia.2 Although the number of cases is under reported and therefore the incidence rates are underestimated,3 worldwide up to 1.3 billion non-typhoidal and an estimated 20 million typhoidal cases of Salmonella infection are reported annually.4,

Tabulated Data From a Pressure-Distribution Investigation at Mach Number 2.01 of a 45 Deg Sweptback-Wing Airplane Model at Combined Angles of Attack and Sideslip

A pressure-distribution investigation of a wing-body combination has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel at a Mach number of 2.01. The model configuration consisted of an ogive-circular-cylinder body (fineness ratio of approximately ii) and a wing with 45 deg of sweepback at the quarter-chord line, an aspect ratio of 4, and a taper ratio of 0.2. Data were obtained on high-, mid-, and low-wing configurations and for the body and wing alone for a range of angles of attack and yaw from 0 deg to 15 deg. The tabulated pressure coefficients are presented in this report