Feasibility of subcutaneous ECG leads for synchronized timing of a counterpulsation device.

Background: Emerging circulatory support devices that operate in counterpulsation to the native heart require synchronized timing of device ejection and filling on a beat-to-beat basis with the native heart using a patient\u27s ECG. Surface leads are commonly used for short-term patient monitoring but not appropriate for long-term use, and epicardial and non-thoracotomy leads increase the complexity of the device implant/explant procedures. Subcutaneous leads have been shown to be less susceptible to artifacts than surface leads, require less invasive surgery, and have recently been used successfully with a long-term subcutaneous implantable cardioverter-defibrillator. The objective of this study was to develop subcutaneous ECG leads for synchronized timing (filling and ejection cycles) of the Symphony device and wearable pneumatic driver for chronic counterpulsation therapy. To demonstrate feasibility, we tested the hypothesis that subcutaneous ECG leads provide equivalent QRS detection, lead migration, and durability as clinical-standard epicardial leads. Methods: Two epicardial and six subcutaneous leads were implanted in bovine (7 days, n=4 and 14 days, n=2). Epicardial and subcutaneous ECGs were recorded simultaneously in 30 second epochs every hour and in 20 minute epochs during daily treadmill exercise. Landmark features and R-wave triggering detection rates for each lead configuration were calculated and compared. Lead placement, migration, and durability were quantified using fluoroscopy and evaluated at necropsy. Results: There were 2,818 data epochs recorded at rest and 24 data epochs recorded during treadmill exercise. Using a simple adaptive-thresholding R-wave detection algorithm with the epicardial signal as the control, the triggering rate for the subcutaneous ECG leads demonstrated 99.1±0.4% positive predictive value and 96.8±1.5% sensitivity during normal daily activity, and 98.0±10.2% positive predictive value and 93.3±5.6% sensitivity during treadmill exercise. The average QRS voltage was 818±99 µV with a T/R ratio of 0.44±0.05. There was no significant waveform distortion or artifacts observed in ECG waveforms measured with the subcutaneous leads. Upon study endpoint, all subcutaneous leads (36/36) were within 1.4 cm of initial placement with an average migration distance of 0.52±0.10 cm. There was no lead fracture or permanent signal loss for all leads (36/36). Conclusion: In this study, the subcutaneous leads provided equivalent performance to epicardial leads in bovine during normal daily activity and treadmill exercise. The leads were easily implantable using standard surgical instruments, provided high reliability of QRS detection, and showed no significant migration from the initial placement site. These findings demonstrate the feasibility of using subcutaneous leads for synchronized timing of mechanical circulatory support while offering the advantage of less invasive surgery and associated risk factors

An investigation into the status of porcine circovirus in Australia

This thesis reports for the first time the detection of porcine circovirus virus (PCV) in the Australian pig herd. PCV DNA was detected in the tissues of pigs from several Australian states using a multiplex polymerase chain reaction (PCR) assay, the primers for which were based on the sequence of PCV1 and PCV2 strains detected in North America and Europe. PCV type 1 or 2 was detected in 80 of 367 (21.7%) pigs tested. In the 80 positives, both PCV1 and PCV2 were detected in 14 samples. Virus was detected in pigs from all states from which samples were obtained: Western Australia, South Australia, New South Wales and Queensland. The complete genomes of 13 strains of Australian PCV were sequenced. Analysis of the data indicated there was extremely high homology between the Australian strains of PCV1 and PCV2 and previously published sequences of PCV1 and PCV2 strains from North America and Europe.There were no consistent differences between the genome of the Australian strains and strains in North America and Europe. The widespread occurrence of PCV in the tissues of pigs was confirmed by a small scale serological study of the Western Australian pig herd using an immunofluorescence assay, which did not discriminate antibody to PCV1 and PCV2. This assay detected PCV antibody in 11 of 14 pig herds in Western Australia, with a prevalence rate in positive herds varying from 25 to 47%, but it was unable to differentiate antibody to PCV1 and PCV2. A PCV2-specific recombinant viral capsid protein was produced in insect cells with a baculovirus expression system and this was used to develop a PCV2-specific ELISA and a Western immunoblotting assay. These assays were applied to samples from a national pig serum bank and detected PCV2 antibody in 33% of 3933 serum samples. The highest seroprevalence to the recombinant PCV2 capsid antigen was detected in the samples from Victoria where there was a 51.3% seroprevalence rate, and the lowest in Western Australia where there was an 11.4% seroprevalence rate. An in situ hybridisation (ISH) technique was developed for the detection of PCV in tissues of infected pigs and infected cell cultures. A monoclonal antibody specific for the capsid protein of PCV2 was also produced and has application for the development of immunocytochemical procedures for the detection of PCV2 in tissues and cell cultures. The high prevalence of PCV in the Australian pig herd and the absence of reports of PMWS suggested that the Australian strains of PMWS detected may have been of low virulence. To examine the pathogenicity of Australian strains, two animal experiments were conducted where the type species of PCV1 present in persistently-infected PK15 pig kidney cells and an Australian PCV2 strain were cultured in vitro in cell cultures and inoculated into weaner pigs. As expected, the PCV1 replicated well in pigs but did not result in the induction of clinical signs or lesions in the inoculated pigs. The inoculation into weaner pigs of cell culture replicated PCV2 with an apparent virus titre of 103 virus particles/mL resulted in infection of only some of the inoculated pigs and it was concluded that the PCV2 inoculum contained insufficient virus to infect all pigs into which it was inoculated. The PCV2 did not induce any disease syndrome and could not be visualised in tissue sections of infected pigs using immunohistochemical techniques. In conclusion, techniques were developed for the detection of PCV in the Australian pig herd. PCV of both genetic types were detected at prevalence rates similar to those reported in other countries where PMWS has occurred, and the widespread occurrence of PCV was confirmed by serological assays. The PCV strains present were genetically indistinguishable from those present in North America and Europe. The reason for the absence of PMWS in Australia is most likely not due to differences in the characteristics of the PCV strains present

Thromboembolic and neurologic sequelae of discontinuation of an antihyperlipidemic drug during ongoing warfarin therapy

Warfarin and antihyperlipidemics are commonly co-prescribed. Some antihyperlipidemics may inhibit warfarin deactivation via the hepatic cytochrome P450 system. Therefore, antihyperlipidemic discontinuation has been hypothesized to result in underanticoagulation, as warfarin metabolism is no longer inhibited. We quantified the risk of venous thromboembolism (VTE) and ischemic stroke (IS) due to statin and fibrate discontinuation in warfarin users, in which warfarin was initially dose-titrated during ongoing antihyperlipidemic therapy. Using 1999-2011 United States Medicaid claims among 69 million beneficiaries, we conducted a set of bidirectional self-controlled case series studies-one for each antihyperlipidemic. Outcomes were hospital admissions for VTE/IS. The risk segment was a maximum of 90 days immediately following antihyperlipidemic discontinuation, the exposure of interest. Time-varying confounders were included in conditional Poisson models. We identified 629 study eligible-persons with at least one outcome. Adjusted incidence rate ratios (IRRs) for all antihyperlipidemics studied were consistent with the null, and ranged from 0.21 (0.02, 2.82) for rosuvastatin to 2.16 (0.06, 75.0) for gemfibrozil. Despite using an underlying dataset of millions of persons, we had little precision in estimating IRRs for VTE/IS among warfarin-treated persons discontinuing individual antihyperlipidemics. Further research should investigate whether discontinuation of gemfibrozil in warfarin users results in serious underanticoagulation

A CPTED bibliography: Publications related to urban space, planning, architecture, and crime prevention through environmental design, 1975-2010

This compendium is the result of two different bibliographies. The first was completed by Sean Michael, Professor and Department Head of the Department of Landscape Architecture and Environmental Planing at Utah State University. The second was completed by Gregory Saville, urban planner and Principal of AlterNation Consulting, started during graduate work at the Faculty of Environmental Studies at York University. Consolidation and expansion of the two works was overseen by Joel Warren, during his Masters of Landscape Architecture at Utah State University. Our thanks go to the many students, colleagues, and friends who contributed to this work over the years. They include: Anna Brassard, Paul Cozens, Misty Fitch, Chuck Genre, and Diane Zahm. Earlier versions have appeared in different venues through the years such as the 2003 ICA CPTED Bibliography available on CD through the International CPTED Association and the Latin America CPTED Region Corporation. In addition, Emerald Press has published a detailed literature review of basic 1st Generation CPTED studies (P. Cozens, G. Saville and D. Hillier, “Crime prevention through environmental design: A review and modern bibliography”, Property Management. 23(5), 2005). Finally, an early version was available via The CPTED Page (www.thecptedpage.wsu.edu). Today, the resource is jointly hosted through the web site of Safe Cascadia (www.safecascadia.org

Hydrolysis of p-Nitrophenyl Esters Promoted by Semi-fluorinated Quaternary Ammonium Polymer Latexes and Films

Semifluorinated polymer latexes were prepared by emulsion polymerization of 2.5-25% of a fluoroalkyl methacrylate, 25% chloromethylstyrene, 1% styrylmethyl(trimethyl)ammonium chloride, and the remainder 2-ethylhexyl methacrylate under surfactant-free conditions. The chloromethylstyrene units were converted to quaternary ammonium ions with trimethylamine. In aqueous dispersions at particle concentrations of less than 1 mg mL-1 the quaternary ammonium ion latexes promoted hydrolyses of p-nitrophenyl hexanoate (PNPH) in pH 9.4 borate buffer and of diethyl p-nitrophenyl phosphate (Paraoxon) in 0.1 M NaOH at 30 oC with half-lives of less than 10 minutes. Thin 0.7-2 μm films of the latexes on glass promoted fast hydrolysis of Paraoxon but not of PNPH under the same conditions. Even after annealing the quaternary ammonium ion polymer films at temperatures well above their glass transition temperatures, AFM images of the film surfaces had textures of particles. Contact angle measurements of the annealed films against water and against hexadecane showed that the surfaces were not highly fluorinated

Invertebrate Abundance at Northern Bobwhite Brood Locations in the Rolling Plains of Texas

Northern bobwhite (Colinus virginianus), a bird of significant ecological and economic importance throughout the Rolling Plains region of Texas, has experienced significant population declines. Bobwhites have been the focus of extensive research for decades but little is known about foraging ecology of adults and chicks during post-hatch. Invertebrates are a key summer diet component for chicks, and supply the necessary proteins and minerals needed to fuel rapid body development. We examined brood-foraging sites to investigate invertebrate abundance. We radiomarked 121 bobwhite hens during winter-spring 2008 and 2009 and subsequently monitored 14 broods post-hatch. We collected invertebrate samples from 34 brood points and random paired-locations using sweep nets. Samples were sorted by Order to ascertain abundance and diversity. There was no difference in total abundance, abundance of Coleoptera, Hemiptera, Orthoptera, and Order diversity between brood and random locations. Northern bobwhite hens do not appear to select foraging sites based upon invertebrate abundance in the Rolling Plains of Texas