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Biomedical subjects

S M Ellis

Publications and source records attributed to S M Ellis.

At least 19 recordsLinked to original sources
PubMed2006

Thin-section CT of the lungs: eye-tracking analysis of the visual approach to reading tiled and stacked display formats.

OBJECTIVE: To use eye-tracking analysis to identify the differences in approach to and efficiency of reading thin-section CT of the lungs presented tiled and stacked soft-copy displays. MATERIALS AND METHODS: Four chest radiologists read 16 thin-section CT examinations displayed in either a tiled (four images at once) or stacked (full screen cine) format. Eye-movements were recorded and analysed in terms of movement type; saccade distance (classified by the calculated range of useful peripheral vision), number of fixations, duration and direction of gaze-comparison of the areas of the images viewed. RESULTS: Cases presented in stacked format were read quicker than when presented in tiled format with a greater fixation frequency (5 fixations versus 4.5 fixations points per 100 data points; p<0.001) and a greater proportion of short saccades (97% versus 94%; p<0.005). The consistency with which the observers viewed equivalent areas of the scan images in different cases was greater when viewing in stacked format (mean kappa 0.45 versus 0.36; p<0.05) suggesting a more systematic approach to reading. CONCLUSION: Eye-tracking data demonstrates why thin-section CT examinations of the lungs are read more efficiently when displayed in a stack as opposed to a tiled format.

Data Display↗
PubMed2004

The spectrum of tuberculosis and non-tuberculous mycobacterial infection.

The spectrum of radiographic findings in pulmonary infections due to M. tuberculosis (TB) and non-tuberculous mycobacteria (NTM) are being increasingly discussed, primarily as a result of the increasing prevalence of these infections. The NTM organisms are often overlooked as potential infecting organisms, diagnosis is often delayed and radiologists tend not to include NTM in their differential diagnosis. The literature on the imaging appearances of NTM pulmonary infections is now sufficiently large as to identify some features that would help to distinguish an NTM infection from conventional pulmonary tuberculosis, allowing the radiologist at least to raise the possibility of NTM infection. This review article is intended to describe the radiological features, in the immunocompetent host, that accompany TB and NTM pulmonary infections and highlight the imaging features that would favour an NTM as the causative organism.

Bronchitis↗
PubMed2004

HRCT diagnosis of diffuse parenchymal lung disease: inter-observer variation.

BACKGROUND: This study was designed to measure inter-observer variation between thoracic radiologists in the diagnosis of diffuse parenchymal lung disease (DPLD) using high resolution computed tomography (HRCT) and to identify areas of difficulty where expertise, in the form of national panels, would be of particular value. METHODS: HRCT images of 131 patients with DPLD (from a tertiary referral hospital (n = 66) and regional teaching centres (n = 65)) were reviewed by 11 thoracic radiologists. Inter-observer variation for the first choice diagnosis was quantified using the unadjusted kappa coefficient of agreement. Observers stated differential diagnoses and assigned a percentage likelihood to each. A weighted kappa was calculated for the likelihood of each of the six most frequently diagnosed disease entities. RESULTS: Observer agreement on the first choice diagnosis was moderate for the entire cohort (kappa = 0.48) and was higher for cases from regional centres (kappa = 0.60) than for cases from the tertiary referral centre (kappa = 0.34). 62% of cases from regional teaching centres were diagnosed with high confidence and good observer agreement (kappa = 0.77). Non-specific interstitial pneumonia (NSIP) was in the differential diagnosis in most disagreements (55%). Weighted kappa values quantifying the likelihood of specific diseases were moderate to good (mean 0.57, range 0.49-0.70). CONCLUSION: There is good agreement between thoracic radiologists for the HRCT diagnosis of DPLD encountered in regional teaching centres. However, cases diagnosed with low confidence, particularly where NSIP is considered as a differential diagnosis, may benefit from the expertise of a reference panel.

Adult↗
PubMed2003

Pancreatic polypeptide reduces appetite and food intake in humans.

Pancreatic polypeptide (PP) is a gut hormone released from the pancreas in response to ingestion of food. Plasma PP has been shown to be reduced in conditions associated with increased food intake and elevated in anorexia nervosa. In addition peripheral administration of PP has been shown to decrease food intake in rodents. These findings suggest that PP may act as a circulating factor that regulates food intake. Therefore we investigated the effect of intravenous infusion of PP (10 pmol/kg/min) on appetite and food intake in a randomised double-blind placebo-controlled crossover study in ten healthy volunteers. Infusion of PP reduced appetite and decreased the energy intake at a buffet lunch two hours post-infusion by 21.8 +/- 5.7% (P < 0.01). More importantly the inhibition of food intake was sustained, such that energy intake, as assessed by food diaries, was significantly reduced both the evening of the study and the following morning. Overall PP infusion reduced cumulative 24-hour energy intake by 25.3 +/- 5.8%. In conclusion our data demonstrates that PP causes a sustained decrease in both appetite and food intake.

Adolescent↗
PubMed2002

Imaging of Non-tuberculous (Atypical) Mycobacterial Pulmonary Infection.

Pulmonary infections due to mycobacterial organisms are increasing in incidence. Non-tuberculous (atypical) mycobacteria (NTM) represent a significant proportion of mycobacterial infections and may prove difficult to diagnose due to their non-specific clinical and radiographic presentations. An increasing volume of radiological data is now available for the more common non-tuberculous mycobacterial infections, and we have summarized the imaging features found in such cases, identifying radiographic features that would favour the diagnosis of a non-tuberculous mycobacterium and that, in some cases, suggest a specific organism.

Humans↗
PubMed2002

Hepatic artery stenosis following liver transplantation: significance of the tardus parvus waveform and the role of microbubble contrast media in the detection of a focal stenosis.

PURPOSE: To evaluate the role of microbubble ultrasound contrast media in detecting stenosis of the post-liver transplant extrahepatic hepatic artery (HA) in the presence of the tardus parvus spectral Doppler waveform of the intrahepatic HA. MATERIALS AND METHODS: All post-liver transplant patients with a prolonged systolic acceleration time (SAT>0.08s) and/or a reduced resistant index (RI<0.50) of the HA (the tardus parvus waveform) on colour Doppler ultrasound (CDUS), were assessed with microbubble contrast medium for a focal arterial stenosis. Following microbubble contrast-enhanced CDUS, patients underwent arteriography or follow-up CDUS. RESULTS: A total of 2038 examinations were performed in 529 liver transplant recipients; 16 (3.02%) tardus parvus waveforms were identified. The median SAT of the intrahepatic HA was 0.18s (range 0.11-0.38s) and the RI 0.47 (range 0.22-0.58). No extrahepatic elevated peak systolic velocity (PSV), defined as above 1.00m/s, was detected on the baseline examinations. Following the administration of microbubble contrast, medium, PSV in the extrahepatic HA was elevated in 14 of 16 patients, (median=2.15m/s, range=1.44-3.10m/s); flow was not identified in two patients. Arteriography was performed in 10 patients and confirmed stenosis in eight (median grade of stenosis 93%, range 60-99%) and occlusion in two. The measured median PSV at contrast-enhanced CDUS in the stenosis group was 2.03m/sec (range 1.44-2.71m/sec). Repeat CDUS in six patients not undergoing arteriography showed resolution in four; one underwent re-transplantation before arteriography and one patient maintains a tardus parvus waveform. In transplant recipients undergoing arteriography during the study period (n=55), no hepatic artery stenosis without a tardus parvus waveform was seen. CONCLUSION: The tardus parvus waveform pattern is an excellent screening test for the presence of post-liver transplantation hepatic artery stenosis. There is only a limited role for microbubble ultrasound contrast agent in the presence of a tardus parvus waveform. It could be used following equivocal colour Doppler ultrasound, but arteriography will still be necessary.

Adolescent↗
PubMed2001

Computed tomography screening for lung cancer: back to basics.

After some years in the doldrums, interest in screening for lung cancer is resurging. Conflicting evidence from previous lung cancer screening trials, based on plain chest radiography, has been the subject of much debate: the failure to demonstrate a reduction in mortality has led to the widely held conclusion that screening for lung cancer is ineffective. The validity of this assumption has been questioned sporadically and a large study currently under way in the U.S.A. should help settle the issue. Recently, there has been interest in the use of computed tomography to screen for lung cancer; radiation doses have been reduced to 'acceptable' levels and the superiority of computed tomography (CT) over chest radiography for the identification of pulmonary nodules is unquestioned. However, whether improved nodule detection will result in a reduction in mortality has not yet been demonstrated. The present review provides a historical background to the current interest in low-dose CT screening, explains the arguments that previous studies have provoked, and discusses the recent and evolving status of lung cancer screening with CT. Ellis, S. M. et al. (2001).

Bias↗
PubMed2000

Clinical use of Levovist, an ultrasound contrast agent, in the imaging of liver transplantation: assessment of the pre- and post-transplant patient.

Colour Doppler US is well established for imaging of hepatic vessels in the assessment of pre- and post-liver transplant patients. Unfortunately, a full colour Doppler US examination of the portal or hepatic venous and hepatic arterial systems is frequently precluded by technical factors. Ultrasound contrast agents are useful in enhancing vascular Doppler signal and play an important role in liver transplantation assessment. A series of patients with vascular problems illustrates the role of US contrast in the pre-transplant candidate, where portal vein patency and direction of flow is assessed, presence of portal vein thrombus is confirmed and cavernous transformation demonstrated. Occlusion of hepatic veins in Budd-Chiari syndrome is confidently confirmed. Following liver transplantation, US contrast allows a comprehensive assessment of hepatic artery thrombosis, hepatic artery stenosis and pseudoaneurysm formation. The need for further imaging is reduced or confidently deferred in many instances. Ultrasound contrast agents play an important role in the liver transplant candidate.

Arterial Occlusive Diseases↗
PubMed2000

Granularity of the carotid artery intima-medial layer: reproducibility of quantification by a computer-based program.

Ultrasound of the carotid artery identifies the hypoechoic intima-medial layer (IML). Increased granularity of the IML has been associated with early atherosclerosis. The aim of the study was to assess the reproducibility and observer agreement of a computer-based program measure of IML granularity. Ten healthy adult volunteers (median age 32 years, range 18-34 years) were examined twice, 2 weeks apart, with a 7 MHz linear transducer using standardized imaging settings, by two observers. Images of both common carotid arteries were digitized and analysed on a customized computer program. The ratio (averaged over a 1 cm length of arterial wall) of the lowest pixel brightness in the IML to the maximum pixel brightness in the intima-medial interface was determined. Overall mean intima-medial reflectivity (IMR) indices for the two observers were 0.761 +/- 0.101 and 0.707 +/- 0.103, with single determination standard deviation values of 0.090 and 0.073, respectively. For interobserver calculations, the overall mean IMR index for both sessions was 0.734 +/- 0.107, with a single determination standard deviation of 0.067. Comparison with the intima-medial thickness (IMT) showed an inverse correlation (r = -0.72). This method of quantifying the reflectivity of the IML demonstrates good reproducibility in subjects with normal IMT measurements. The technique may be of value in identifying subjects at high risk of atherosclerosis but with IMT still within the normal range.

Adolescent↗
PubMed1997

Burn management. Rehabilitation.

Rehabilitation of a patient with a burn injury requires multidisciplinary collaboration, especially between the burn therapist and the burn rehabilitation nurse. Each discipline brings unique educational backgrounds and skills to promote the rehabilitation process throughout all phases of burn recovery. This article highlights major aspects of burn rehabilitation and emphasizes the collaboration between the burn therapist and the rehabilitation nurse.

Burn Units↗
PubMed1995

Antiviral screening of British Columbian medicinal plants.

One hundred methanolic plant extracts were screened for antiviral activity against seven viruses. Twelve extracts were found to have antiviral activity at the non-cytotoxic concentrations tested. The extracts of Rosa nutkana and Amelanchier alnifolia, both members of the Rosaceae, were very active against an enteric coronavirus. A root extract of another member of the Rosaceae, Potentilla arguta, completely inhibited respiratory syncytial virus. A Sambucus racemosa branch tip extract was also very active against respiratory syncytial virus while the inner bark extract of Oplopanax horridus partially inhibited this virus. An extract of Ipomopsis aggregata demonstrated very good activity against parainfluenza virus type 3. A Lomatium dissectum root extract completely inhibited the cytopathic effects of rotavirus. In addition to these, extracts prepared from the following plants exhibited antiviral activity against herpesvirus type 1: Cardamine angulata, Conocephalum conicum, Lysichiton americanum, Polypodium glycyrrhiza and Verbascum thapsus.

Animals↗
PubMed1994

Antifungal screening of medicinal plants of British Columbian native peoples.

One hundred methanolic plant extracts were screened for antifungal activity against 9 fungal species. Eighty-one were found to have some antifungal activity and 30 extracts showed activity against 4 or more of the fungi assayed. The extracts with the greatest fungal inhibition were prepared from Alnus rubra catkins, Artemisia ludoviciana aerial parts, Artemisia tridentata aerial parts, Geum macrophyllum roots, Mahonia aquifolium roots and Moneses uniflora aerial parts. In addition to these, extracts prepared from the following plants also exhibited antifungal activity against all 9 fungi: Asarum caudatum whole plant, Balsamorhiza sagittata roots, Empetrum nigrum branches, Fragaria chiloensis leaves, Gilia aggregata aerial parts and roots, Glehnia littoralis roots, Heracleum lanatum roots, Heuchera cylindrica roots and Rhus glabra branches.

Antifungal Agents↗
PubMed1994

Adsorption of 222Rn by open-faced and diffusion-barrier canisters at different conditions of temperature and humidity.

Open-faced and diffusion-barrier charcoal canisters were individually exposed to a fixed temperature, humidity, and radon concentration in a chamber for a period of 7 d. The radon progeny activity in the canister under study was measured every 3 h. A total of 15 runs were made for the open-faced canisters and nine runs for the barrier canisters with temperatures and absolute humidities ranging from 15-30 degrees C and 0-15 g m-3, respectively. In addition, several runs were made with the radon, temperature, and humidity changing during the 7 d. Results show that open-faced canisters adsorb radon up to 60% more efficiently at 15 degrees C than at 30 degrees C while the barrier canisters show little temperature dependence. The barrier canisters are much less sensitive to humidity effects than the open-faced canister. When used to measure the radon concentration in air, the open-faced canister integrates over a period of only approximately 48 h while the barrier canister integrates over a period of approximately 96 h. The short integration time and the interference of water adsorption by open-faced canisters indicate that the open-faced canisters should be used for exposure times of 48 h and no longer.

Adsorption↗
PubMed1993

The application of new bioavailability parameters in the bioequivalence testing of antimicrobial agents.

Two new bioavailability parameters were recently suggested [Koeleman et al. 1991] to define (i) the time that the concentration in the blood stays above a defined minimum effective concentration, te and (ii) the onset of the effect, to. In addition to conventional bioequivalence parameters, the new bioavailabilty parameters (to and te) were calculated in this study and statistically compared for penicillin, chloroquine, oxytetracycline, amoxycillin and flucloxacillin from available bioequivalence data. For oxytetracycline, flucloxacillin and amoxycillin, the conventional bioavailability parameters indicated partial equivalence whereas using the te and to parameters, more realistic indications of the possible extent of the performance of a drug from dosage forms were obtained than with the conventional bioequivalence parameters. The new parameters gave additional information for a better evaluation of the performance of a drug from a dosage form.

Amoxicillin↗
PubMed1992

Antibiotic screening of medicinal plants of the British Columbian native peoples.

One hundred methanolic plant extracts, 96 of which had documented medicinal uses by British Columbian native peoples, were screened for antibiotic activity against 11 bacterial strains. Eighty-five percent were found to have significant antibiotic activity against at least two of the bacteria tested. Ninety-five percent of the plants categorized as potential antibiotics based on their ethnobotanical usage were found to exhibit significant antibiotic activity. Seventy-five were found to be active against methicillin-resistant Staphylococcus aureus, 46 were active against an antibiotic supersusceptible strain of Pseudomonas aeruginosa and 18 of these were also active against a wild type strain. The extracts with the broadest spectra of activity were prepared from: Alnus rubra bark and catkins, Fragaria chiloensis leaves, Moneses uniflora aerial parts, and Rhus glabra branches.

Anti-Bacterial Agents↗
PubMed1991

New bioavailability parameters to compare the efficacy of antimicrobial drugs in dosage forms.

Pharmacokinetic parameters such as AUC, Cmax and tmax have been used to represent the rate and extent of absorption of drugs from dosage forms in comparative bioequivalence testing. None of these parameters gives a direct indication of how long the drug concentration is maintained above an acceptable level e.g. minimum inhibitory concentration (MIC) or the minimum effective concentration (MEC). This is clinically important in evaluating the onset and duration of a therapeutic effect obtained from a test dosage form in comparison to the reference dosage form. The purpose of this study is to investigate the possibility of a bioavailability parameter which relates the time that the drug concentration in the systemic circulation is maintained above a certain level (te) and the first time that the blood concentration exceeds this level (to). Two methods were used to calculate the time that drug levels are maintained above a certain minimum level. The proposed parameters proved to be valuable when the efficacy of erythromycin was used as an example. Although some problems, such as undefined MIC/MEC may arise, te and to can be used along with the conventional bioequivalence parameters to obtain a better indication of the clinical efficacy.

Biological Availability↗
PubMed1989

Monoclonal antibody preparation and purification of a tumor cell collagenase-stimulatory factor.

Tumor cells from several sources produce a factor(s) which stimulates fibroblast collagenase production. Monoclonal antibodies have been raised against the tumor cell collagenase-stimulatory factor from LX-1 human lung carcinoma cells and have been used for purification of the factor from LX-1 cell membranes. These purified preparations stimulated fibroblast collagenase production, and 80% of these preparations contained a single Mr approximately 58,000 protein detectable by immunoblotting; the other 20% contained an additional minor component with a molecular weight of 35,000. A single protein with a molecular weight of approximately 58,000 was also detected in radiolabeled preparations of the purified factor by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Conditioned media from LX-1 cells contain several species with molecular weights lower than 58,000 which are immunologically cross-reactive with the membrane-derived factor. Immunofluorescence analysis indicates that the tumor cell collagenase-stimulatory factor is distributed on the outer surface of LX-1 cells and is absent from the cell surface of fibroblasts. These and previous results indicate that the factor is present on the tumor cell surface, is released into conditioned media possibly after proteolytic cleavage, and appears to have an important role in inducing collagenolysis of host stroma during tumor invasion.

Animals↗