Pathogenic Escherichia coli strains cause a wide variety of intestinal and extraintestinal infections. The widespread geographical clonal dissemination of intestinal pathogenic E. coli strains, such ...as E. coli O157:H7, is well recognized, and its spread is most often attributed to contaminated food products. On the other hand, the clonal dissemination of extraintestinal pathogenic E. coli (ExPEC) strains is also recognized, but the mechanism of their spread is not well explained. Here, I describe major pandemic clonal lineages of ExPEC based on multilocus sequence typing (MLST), and discuss possible reasons for their global dissemination. These lineages include sequence type (ST) 131, ST393, ST69, ST95, and ST73, which are all associated with both community-onset and healthcare-associated infections, in particular urinary tract infections and bloodstream infections. As with many other types of drug-resistant Gram-negative and Gram-positive bacterial infections, drug-resistant ExPEC infections are recognized to be caused by a limited set of clonal lineages. However, reported observations on these major pandemic lineages suggest that the resistance phenotype is not necessarily the determinant of their clonal dissemination. Both epidemiological factors and their intrinsic biological ‘fitness’ are likely to contribute. An important public health and clinical concern is that pandemicity itself may be a determinant of progressive drug resistance acquisition by clonal lineages. New research is urgently needed to better understand the epidemiological and biological causes of ExPEC pandemicity.
Our primary goal was to determine the effects of 6-mo flight on the International Space Station (ISS) on selected anaerobic and aerobic enzymes, and the content of glycogen and lipids in slow and ...fast fibers of the soleus and gastrocnemius. Following local anesthesia, biopsies were obtained from nine ISS crew members ∼45 days preflight and on landing day (R+0) postflight. We subdivided the crew into those who ran 200 min/wk or more (high treadmill, HT) in-flight from those who ran <100 min/wk (low treadmill, LT). In the LT group, there was a loss of lipid in soleus type I fibers, and muscle glycogen significantly increased in soleus fiber types postflight. Soleus cytochrome oxidase (CO) activity was significantly depressed postflight in the type I fiber. This was attributed to the LT group where CO activity was reduced 59%. Otherwise, there was no change in the crew mean for type I or IIa fiber glycolytic or mitochondrial enzyme activities pre- vs. postflight in either muscle. However, two of the three HT subjects (Subjects E and H) showed significant increases in both β-hydroxyacyl-CoA dehydrogenase and citrate synthase in the soleus type I fibers, and Subject E, exhibiting the largest increase in soleus oxidative enzymes, was the only subject to show a significant decrease in glycolytic enzyme activity. It is apparent that crew members performing adequate treadmill running can maintain calf muscle enzymes, which suggests that increased fatigue with weightlessness cannot be directly caused by a decline in muscle enzyme capacity.
Recent advances using CRISPR-Cas9 approaches have dramatically enhanced the ease for genetic manipulation in rodents. Notwithstanding, the methods to deliver nucleic acids into pre-implantation ...embryos have hardly changed since the original description of mouse transgenesis more than 30 years ago. Here we report a novel strategy to generate genetically modified mice by transduction of CRISPR-Cas9 components into pre-implantation mouse embryos via recombinant adeno-associated viruses (rAAVs). Using this approach, we efficiently generated a variety of targeted mutations in explanted embryos, including indel events produced by non-homologous end joining and tailored mutations using homology-directed repair. We also achieved gene modification in vivo by direct delivery of rAAV particles into the oviduct of pregnant females. Our approach greatly simplifies the generation of genetically modified mice and, more importantly, opens the door for streamlined gene editing in other mammalian species.
An integrated portable genetic analysis microsystem including PCR amplification and capillary electrophoretic (CE) analysis coupled with a compact instrument for electrical control and laser-excited ...fluorescence detection has been developed. The microdevice contains microfabricated heaters, temperature sensors, and membrane valves to provide controlled sample positioning and immobilization in 200-nL PCR chambers. The instrument incorporates a solid-state laser and confocal fluorescence detection optics, electronics for sensing and powering the PCR reactor, and high-voltage power supplies for conducting CE separations. The fluorescein-labeled PCR products are amplified and electrophoretically analyzed in a gel-filled microchannel in <10 min. We demonstrate the utility of this instrument by performing pathogen detection and genotyping directly from whole Escherichia coli and Staphylococcus aureus cells. The E. coli detection assay consists of a triplex PCR amplification targeting genes that encode 16S ribosomal RNA, the fliC flagellar antigen, and the sltI shigatoxin. Serial dilution demonstrates a limit of detection of 2−3 bacterial cells. The S. aureus assay uses a femA marker to identify cells as S. aureus and a mecA marker to probe for methicillin resistance. This integrated portable genomic analysis microsystem demonstrates the feasibility of performing rapid high-quality detection of pathogens and their antimicrobial drug resistance.
Conventional tests are not always helpful in making a diagnosis of tuberculous meningitis. We did a systematic review and meta-analysis to establish the summary accuracy of nucleic acid amplification ...(NAA) tests for tuberculous meningitis. We searched six electronic databases and contacted authors, experts, and manufacturers. Measures of diagnostic accuracy were pooled using a random effects model. 49 studies met our inclusion criteria. The summary estimates in 14 studies with commercial NAA tests were: sensitivity 0·56 (95% CI 0·46, 0·66), specificity 0·98 (0·97, 0·99), positive likelihood ratio 35·1 (19·0, 64·6), negative likelihood ratio 0·44 (0·33, 0·60), and diagnostic odds ratio 96·4 (42·8, 217·3). In the 35 studies with in-house (“homebrew”) tests, the summary accuracy could not be established with confidence because of wide variability in test accuracy. On current evidence, commercial NAA tests show a potential role in confirming tuberculous meningitis diagnosis, although their overall low sensitivity precludes the use of these tests to rule out tuberculous meningitis with certainty.
Hand‐arm vibration syndrome (HAVS) is an irreversible neurodegenerative, vasospastic, and musculoskeletal occupational disease of workers who use powered hand tools. The etiology is poorly ...understood. Neurological symptoms include numbness, tingling, and pain. This study examines impact hammer vibration‐induced injury and recoverability of hair mechanosensory innervation. Rat tails were vibrated 12 min/d for 5 weeks followed by 5 week recovery with synchronous non‐vibrated controls. Nerve fibers were PGP9.5 immunostained. Lanceolate complex innervation was compared quantitatively in vibrated vs sham. Vibration peak acceleration magnitudes were characterized by frequency power spectral analysis. Average magnitude (2515 m/s2, root mean squared) in kHz frequencies was 109 times that (23 m/s2) in low Hz. Percentage of hairs innervated by lanceolate complexes was 69.1% in 5‐week sham and 53.4% in 5‐week vibration generating a denervation difference of 15.7% higher in vibration. Hair innervation was 76.9% in 5‐weeks recovery sham and 62.0% in 5‐week recovery vibration producing a denervation difference 14.9% higher in recovery vibration. Lanceolate number per complex (18.4 ± 0.2) after vibration remained near sham (19.3 ± 0.3), but 44.9% of lanceolate complexes were abnormal in 5 weeks vibrated compared to 18.8% in sham. The largest vibration energies are peak kHz accelerations (approximately 100 000 m/s2) from shock waves. The existing ISO 5349‐1 standard excludes kHz vibrations, seriously underestimating vibration injury risk. The present study validates the rat tail, impact hammer vibration as a model for investigating irreversible nerve damage. Persistence of higher denervation difference after 5‐week recovery suggests repeated vibration injury destroys the capability of lanceolate nerve endings to regenerate.
► A power consumption measurement method in rotary ultrasonic machining (RUM) is proposed. ► Effects of ultrasonic power, tool rotation speed, feedrate, and type of CFRP on power consumption are ...investigated. ► Power consumption percentages of each component are studied. ► Ultrasonic power supply in RUM system is not the largest power consumer during machining.
Carbon fiber reinforced plastic (CFRP) composites are very difficult to machine. A large number of holes need to be drilled in CFRP for many applications. Therefore, it is important to develop cost-effective drilling processes. CFRP has been drilled by rotary ultrasonic machining (RUM) successfully. The literature has reports about the effects of input variables on output variables (including cutting force, torque, surface roughness, tool wear, and workpiece delamination) in RUM of CFRP. However, there are no reports on power consumption in RUM of CFRP. This paper reports the first study on power consumption in RUM of CFRP. It reports an experimental investigation on effects of input variables (ultrasonic power, tool rotation speed, feedrate, and type of CFRP) on power consumption of each component (including ultrasonic power supply, spindle motor, coolant pump, and air compressor) and the entire RUM system.
Background. The multistate occurrence of cases of urinary tract infection (UTI) caused by trimethoprim-sulfamethoxazole (TMP-SMZ)—resistant Escherichia coli strains belonging to a single clonal group ...(designated as clonal group A CgA) in the United States has raised an intriguing hypothesis that these infections may have been spread by contaminated food products. The present study attempted to determine if CgA strains could be traced to food animals. Methods. A total of 495 animal and environmental E. coli isolates, which belonged to serogroups O11, O17, O73, and O77 and were collected between 1965 and 2002 by the Gastroenteric Disease Center at Pennsylvania State University (University Park, PA), were further subtyped by antimicrobial drug susceptibility, enterobacterial repetitive intergenic consensus (ERIC2) PCR, random amplified polymorphic DNA analysis, pulsed-field gel electrophoresis (PFGE), and virulence profile pattern. Results. Of 495 isolates, 128 (26%) had an ERIC2 PCR electrophoretic pattern indistinguishable from that of the human prototype CgA strain, and 14 CgA isolates were resistant to TMP-SMZ. Cluster analysis of PFGE patterns showed that 1 of these 14 isolates, obtained from a cow in 1988, was 94% similar to a CgA uropathogenic human-associated E. coli strain. The pattern for this isolate was included among a cluster of PFGE patterns for 5 human-associated UTI isolates that were >80% similar to each other. Conclusions. These observations suggest that drug-resistant, uropathogenic human-associated E. coli strains potentially have an animal origin. The possibility that human drug-resistant UTI could be a foodborne illness has serious public health implications.
PDF
