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W Shepherd

Publications and source records attributed to W Shepherd.

9 recordsLinked to original sources
PubMed2004

Fast-tracking revisited: routine cardiac surgical patients need minimal intensive care.

OBJECTIVE: Following cardiac surgery, patients are transferred from the operating theatre to intensive care. This clinical environment has one nurse per patient and facilities for mechanical ventilation. Patients are kept in this setting until the following day. This practice has been challenged with early extubation of patients. At our institution we have established a fast-track policy including the following features: (1) patient selection; (2) operating list scheduling with fast-track patients first; (3) anaesthetic tailored to early extubation; (4) methodical procedure with warm cardiopulmonary bypass; (5) removal of the arterial line; (6) transfer from intensive care to a separate high dependency unit ('step-down') on the day of operation, where the ratio of nurse to patient is one to three and there are no ventilatory facilities and no invasive monitoring; or (7) to keep these patients on ICU but decrease the nurse to patient ratio. METHOD: The case notes of 572 patients who predominantly had myocardial revascularisation, undergoing this process from July 1996 to July 2000 at our institution were reviewed. RESULTS: Mean EUROSCORE for the study group was 1.42. The 30-day mortality rate for the study group was 0.34%, mean intensive care time was 5 h 52 min, mean time to extubation was 3 h 10 min, mean readmission rate to intensive care was 0.34% and mean hospital stay from day of operation (inclusive) was 5.65 days. This process increased our throughput by 14.6% (compared to standard practices). COMMENT: This study demonstrates that transfer of appropriate patients to a high dependency area from intensive care following cardiac surgery is safe. It allows intensive care beds to be used by more than one patient each day and allows significant cost savings by reducing the nursing ratio per patient.

Adult↗
PubMed2003

Changes in water quality parameters due to in-sewer processes.

Combined sewer systems contain a large number of organic and inorganic pollutants from both domestic and industrial sources. These pollutants are often retained within the combined sewer system for significant lengths of time before entering sewage treatment works, or being spilt to a watercourse via a combined sewer overflow (CSO) during storm conditions. Currently little knowledge exists concerning the effects of in sewer processes on pollutants. Understanding of in-sewer processes is important for the effective and efficient design of treatment works and CSO chambers and for impact assessments on receiving waters. A series of studies covering storm and dry weather flow conditions were undertaken with the aim of investigating the nature of in-sewer processes. These studies consisted of marking a body of water with a fluorescent tracer. The tracer was then monitored at a series of downstream sites, and discrete samples collected from the body of water as it progressed through the sewer. The samples were analysed for water quality parameters and these results investigated in tandem with the detailed hydraulic information gained through the tracer studies. The results highlight the hydraulic differences between storm and dry weather conditions such as increased travel times and mixing under storm conditions. The Advection Dispersion Equation (ADE) and Aggregated Dead Zone (ADZ) model parameters have been quantified for the tracer data. The ADE mixing coefficient is shown to increase by an order of magnitude for storm conditions. The ADZ dispersive fraction parameter is shown to be approximately constant with flow. Chemical reactions and decay within the sewer system were found to be consistent with oxygen limitation.

Environmental Monitoring↗
PubMed1999

Distributing digital imaging and communications in medicine data and optimizing access over satellite networks.

To improve radiology access to full uncompressed Digital Imaging and Communications in Medicine (DICOM) data sets, we evaluated satellite access to a DICOM server. Radiologists' home computers were connected by satellite to a Medweb DICOM server (Medweb, San Francisco, CA). A 10.2-kb data set containing a 19-image head computed tomography (CT) scan was transferred using DirecPC (Hughes Electronics Corp, Arlington, VA) at three different times of the day; 6 AM, 3 PM, and 8 PM. The average transfer time for all 19 images from the DICOM server was 4 minutes and 17 seconds (257 seconds). The slowest transfer rate of 670 seconds (121 kbps) was obtained at 8 PM. The best transfer rate of 2 minutes, 54 seconds (467 kbps) was obtained at 6 AM. The full 16-bit DICOM images were viewed with bone, brain, and soft tissue windows. The Medweb plug-in viewer loaded the first image within 30 seconds of selecting the case for satellite transfer. In conclusion, satellite internet transfer of radiology studies is suitable for timely review of full DICOM data sets and can expand the range of teleradiology consultation.

Brain↗
PubMed1991

Responses of the L5178Y mouse lymphoma forward mutation assay: V. Gases and vapors.

A new protocol for testing vapors and gases in the L5178Y mouse lymphoma assay is presented. Four chemicals, propylene, 1,2-propylene oxide, 1,3-butadiene, and vinylidene chloride, were tested for their mutagenic potential. Cultures were exposed to the chemicals, which were delivered as vapors or gases, for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 microgram/ml. Each chemical was tested at least twice. Significant responses were obtained with 1,2-propylene oxide and vinylidene chloride, but neither cytotoxicity nor mutagenicity was induced by 1,3-butadiene; propylene could not be classified as either mutagenic or non-mutagenic in the assay. Rat liver S9 mix was not a requirement for the mutagenic activity of 1,2-propylene oxide, whereas the liver preparation markedly enhanced both the cytotoxicity and mutagenicity of vinylidene chloride.

Air Pollutants↗
PubMed1990

Studies on the activities of benzo[a]pyrene, benzidine and ethyl methanesulphonate in the L5178Y TK +/- mouse lymphoma mutagenicity assay using standardized and non-standardized protocols.

As part of the third UKEMS collaborative trial, ethylmethane sulphonate (EMS), benzo[a]pyrene (B[a]P) and benzidine (BZD) were assayed for mutagenicity using the L5178Y mouse lymphoma TK +/- forward mutation system. Exogenous metabolic activation was achieved with two different sources of rat liver S9 which were used under optimized conditions for B[a]P and BZD, the latter being tested also without S9. EMS was assayed in the absence of S9 only. Mutants were selected for trifluorothymidine (TFT) resistance after 48 and 72 h expression time. Mutant frequency (MF) data were subjected to ANOVA analysis and t-tests for differences between replicate cultures, linear trend and differences from solvent controls. Large TFT resistant colonies are believed to be due to induction of small amounts of genetic damage (point mutations, small deletions) at the tk locus, whilst small colonies are thought to be a result of larger effects. The relative proportions of the two colony types were determined in some experiments. All three compounds induced dose-related increases in MF under all conditions. B[a]P induced equal proportions of large and small colonies at all doses. EMS induced predominantly large colonies at all doses. The effect of BZD on colony size was variable. The source of S9 did not exert any consistent effect on toxicity, mutagenicity or mutant colony size. Maximum MF values occurred at 72 h for B[a]P and BZD but the results with EMS were variable. No consistent differences were apparent between estimates of toxicities made either by cloning immediately after treatment (day 0 cloning) or by estimating the relative total growth (RTG) at expression time.

Animals↗
PubMed1989

TFT and 6TG resistance of mouse lymphoma cells to analogs of azacytidine.

5-Azacytidine (5-aza-CR) and six of its analogs were examined for their ability to induce trifluorothymidine (TFT) and/or 6-thioguanine (6TG) resistance in L5178Y mouse lymphoma cells. These analogs were 5-aza-2'-deoxycytidine (5-aza-CdR), 5-fluoro-2'-deoxycytidine (5-FCdR), 5,6-dihydro-5-azacytidine (dH-aza-CR), 6-azacytidine (6-aza-CR), cytidine (CR) and 1-b-D-arabinofuranosylcytosine (ara-C). 5-Aza-CR and 6-aza-CR were examined for their ability to induce 6TG-resistant colonies and results demonstrated no effect. At least a 5-fold increase in TFT resistance was observed for 5-aza-CR, 5-aza-CdR, 5-FCdR, dH-aza-CR and ara-C. The concentration at which these compounds induced TFT resistance correlated well with the potential of the nucleoside analogs to induce differentiation in C3H10T1/2 cells as determined by Constantinides et al. (Nature, 267, 364-366, 1977). In L5178Y mouse lymphoma (MOLY) cells, 5-aza-CR induced TFT resistance and produced both small and large colonies. Previous studies using mammalian cells showed the absence of mutagenic activity with 5-aza-CR and some of its analogs at the ATPase and hgprt loci. However, the different spectrum of DNA lesions detected at the tk locus may be responsible for the response of MOLY cells to 5-aza-CR.

Animals↗
PubMed1988

First recognized community outbreak of haemorrhagic colitis due to verotoxin-producing Escherichia coli O 157.H7 in the UK.

The first recognized outbreak of haemorrhagic colitis due to Escherichia coli O 157.H7 in the United Kingdom affected at least 24 persons living in East Anglia over a 2-week period. The illnesses were characterized by severe abdominal pain and bloody diarrhoea of short duration. Eleven patients were admitted to hospital and there was one death. Patients were mainly adult women who had not eaten out of the home in the 2 weeks before onset. Unlike previously reported outbreaks hamburgers were not the vehicle of infection, and a case-control study suggested that handling vegetables, and particularly potatoes, was the important risk factor.

Adult↗