Patient-Reported Outcomes in Patients With Advanced Urothelial Cancer Who Are Ineligible for Cisplatin and Treated With First-Line Enfortumab Vedotin Alone or With Pembrolizumab

PURPOSE

Locally advanced/metastatic urothelial cancer (la/mUC) affects patients' quality of life (QOL) and functioning. We describe the impact of first-line (1L) enfortumab vedotin (EV) alone or with pembrolizumab (P) on QOL/functioning/symptoms in patients with la/mUC who were cisplatin-ineligible from EV-103 Cohort K.

METHODS

In this phase Ib/II trial, patients were randomly assigned 1:1 to EV + P or EV monotherapy (mono). Exploratory patient-reported outcomes (PROs) were assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core Questionnaire (EORTC QLQ-C30) and Brief Pain Inventory Short Form (BPI-SF) at baseline, once per week for cycles 1-3, and then in every cycle through the end of treatment. Changes in scores from baseline to week 24, reported as least squares mean (standard error), were assessed by mixed models for repeated measures. There were no formal statistical comparisons between treatment arms.

RESULTS

Of 149 patients treated, 65 (EV + P) and 63 (EV mono) comprised the PRO analysis set. For EV + P, EORTC QLQ-C30 QOL was maintained through week 24 with improvements in emotional functioning, pain, and insomnia. Clinically meaningful improvements were seen in EORTC QLQ-C30 pain after EV + P at weeks 12 (-14.41 [3.14]) and 24 (-14.99 [3.56]) and BPI-SF worst pain at week 24 (-2.07 [0.37]). For EV mono, EORTC QLQ-C30 QOL remained stable with clinically meaningful improvements in EORTC QLQ-C30 pain (-12.55 [4.27]), insomnia (-14.46 [4.69]), and constipation (-10.09 [4.35]) at week 24. There were small-to-moderate improvements in BPI-SF worst pain at week 24.

CONCLUSION

EV + P in patients with la/mUC who were cisplatin-ineligible was associated with preservation or improvement of QOL/functioning/symptoms. Improvement in pain was seen in both PRO instruments and treatment arms. These data complement clinical outcomes of 1L EV + P.

Advanced Systemic Mastocytosis with associated haematological neoplasm: Treatment with avapritinib can facilitate successful bridge to allogeneic haematopoietic cell transplant

Advanced systemic mastocytosis (AdvSM) is a rare, life-limiting mast cell (MC) neoplasm, with approximately 70% patients having an associated haematological neoplasm (AHN). Avapritinib, a selective tyrosine kinase inhibitor targeting KIT D816V, has shown potent activity translating clinically into durable responses in the phase 1 EXPLORER (NCT02561988) and phase 2 PATHFINDER (NCT03580655) studies. We report three patients with AdvSM-AHN on avapritinib who achieved complete remission (CR) of SM and were successfully bridged to allogeneic haematopoietic cell transplant (allo-HCT). Two cases additionally highlight the risk of clonal evolution within the AHN component and requirement for close monitoring while on targeted therapy.

Risk of relapse and readmission among hospitalized adults with carbapenem non-susceptible gram-negative infections

BACKGROUND

Infections caused by carbapenem-nonsusceptible gram-negative (C-NS) pathogens are associated with increased mortality and high treatment costs. Identification of potentially modifiable factors that may improve patient outcomes is important for better management of C-NS GN infections.

METHODS

This was a retrospective study of hospitalized adults with electronic health record evidence of complicated urinary tract infection (cUTI), bacterial pneumonia (BP), complicated intra-abdominal infection (cIAI), or bacteremia (BAC) due to C-NS GN organisms from January 2013 to March 2018. Treatment patterns and clinical characteristics during the index hospitalization were analyzed descriptively and stratified by infection site(s). The effect of patient characteristics on index infection relapse during the postdischarge period and on readmission with 30 days was modeled using logistic regression.

RESULTS

The study included 2,862 hospitalized patients with C-NS GN infections. Index infection sites were 38.4% cUTI ± BAC, 21.5% BP ± BAC, 18.7% cUTI + BP ± BAC, 14.7% any cIAI, and 6.7% BAC only. The majority of patients (83.6%) received an antibiotic during their index hospitalization; among these, the most common classes given were penicillins (52.9%), fluoroquinolones (50.7%), and carbapenems (38.9%). During the postdischarge period, 21.7% of patients had a relapse of the index infection and 63.9% of patients were readmitted to the hospital. Factors associated with increased adjusted odds ratio (OR) for relapse or readmission included Charlson comorbidity score of ≥3 relative to 0 (relapse: OR [95% CI] = 1.34 [1.01-1.76], p = .040; readmission: OR [95% CI] 1.92 [1.50-2.46], p < .001), preindex immunocompromised status (relapse: OR [95% CI] 1.37 [1.05-1.79], p = .019; readmission: OR [95% CI] = 1.60 [1.27-2.02], p < .001), and preindex carbapenem use (relapse: OR [95% CI] = 1.35 [1.07-1.72], p = .013; readmission: OR [95% CI] = 1.25 [1.00-1.57], p = .048).

CONCLUSIONS

Adverse postdischarge outcomes were common among hospitalized patients with C-NS GN infections and were significantly associated with previous carbapenem use and patient clinical characteristics such as higher comorbidity burden and immunocompromised status. Adoption of antimicrobial stewardship and consideration of individual patient risk factors in making treatment decisions may help improve clinical outcomes.

Cost-effectiveness of imipenem/cilastatin/relebactam for hospital-acquired and ventilator-associated bacterial pneumonia

Aim: This study evaluates the cost-effectiveness of imipenem/cilastatin/relebactam (IMI/REL) for treating hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia (HABP/VABP) in an 'early adjustment prescribing scenario'. Methods: An economic model was constructed to compare two strategies: continuation of empiric piperacillin/tazobactam (PIP/TAZ) versus early adjustment to IMI/REL. A decision tree was used to depict the hospitalization period, and a Markov model used to capture long-term outcomes. Results: IMI/REL generated more quality-adjusted life years than PIP/TAZ, at an increased cost per patient. The incremental cost-effectiveness ratio of $17,529 per QALY is below the typical US willingness-to-pay threshold. Conclusion: IMI/REL may represent a cost-effective treatment for payers and a valuable option for clinicians, when considered alongside patient risk factors, local epidemiology, and susceptibility data.

Patterns, Predictors, and Intercenter Variability in Empiric Gram-Negative Antibiotic Use Across 928 United States Hospitals

BACKGROUND

Empiric antibiotic use among hospitalized adults in the United States (US) is largely undescribed. Identifying factors associated with broad-spectrum empiric therapy may inform antibiotic stewardship interventions and facilitate benchmarking.

METHODS

We performed a retrospective cohort study of adults discharged in 2019 from 928 hospitals in the Premier Healthcare Database. "Empiric" gram-negative antibiotics were defined by administration before day 3 of hospitalization. Multivariable logistic regression models with random effects by hospital were used to evaluate associations between patient and hospital characteristics and empiric receipt of broad-spectrum, compared to narrow-spectrum, gram-negative antibiotics.

RESULTS

Of 8 017 740 hospitalized adults, 2 928 657 (37%) received empiric gram-negative antibiotics. Among 1 781 306 who received broad-spectrum therapy, 30% did not have a common infectious syndrome present on admission (pneumonia, urinary tract infection, sepsis, or bacteremia), surgery, or an intensive care unit stay in the empiric window. Holding other factors constant, males were 22% more likely (adjusted odds ratio [aOR], 1.22 [95% confidence interval, 1.22-1.23]), and all non-White racial groups 6%-13% less likely (aOR range, 0.87-0.94), to receive broad-spectrum therapy. There were significant prescribing differences by region, with the highest adjusted odds of broad-spectrum therapy in the US West South Central division. Even after model adjustment, there remained substantial interhospital variability: Among patients receiving empiric therapy, the probability of receiving broad-spectrum antibiotics varied as much as 34+ percentage points due solely to the admitting hospital (95% interval of probabilities: 43%-77%).

CONCLUSIONS

Empiric gram-negative antibiotic use is highly variable across US regions, and there is high, unexplained interhospital variability. Sex and racial disparities in the receipt of broad-spectrum therapy warrant further investigation.

Clinical characteristics, microbiology and outcomes of a cohort of patients treated with ceftolozane/tazobactam in acute care inpatient facilities, Houston, Texas, USA

Background

Ceftolozane/tazobactam is a β-lactam/β-lactamase inhibitor combination with activity against a variety of Gram-negative bacteria, including MDR Pseudomonas aeruginosa. This agent is approved for hospital-acquired and ventilator-associated bacterial pneumonia. However, most real-world outcome data come from small observational cohorts. Thus, we sought to evaluate the utilization of ceftolozane/tazobactam at multiple tertiary hospitals in Houston, TX, USA.

Methods

We conducted a multicentre retrospective study of patients receiving at least 48 h of ceftolozane/tazobactam therapy from January 2016 through to September 2019 at two hospital systems in Houston. Demographic, clinical and microbiological data were collected, including the infecting bacterial isolate, when available. The primary outcome was composite clinical success at hospital discharge. Secondary outcomes included in-hospital mortality and clinical disposition at 14 and 30 days post ceftolozane/tazobactam initiation. Multivariable logistic regression analysis was used to identify predictors of the primary outcome and mortality. Recovered isolates were tested for susceptibility to ceftolozane/tazobactam and underwent WGS.

Results

A total of 263 patients were enrolled, and composite clinical success was achieved in 185 patients (70.3%). Severity of illness was the most consistent predictor of clinical success. Combination therapy with ceftolozane/tazobactam and another Gram-negative-active agent was associated with reduced odds of clinical success (OR 0.32, 95% CI 0.16-0.63). Resistance to ceftolozane/tazobactam was noted in 15.4% of isolates available for WGS; mutations in ampC and ftsI were common but did not cluster with a particular ST.

Conclusions

Clinical success rate among this patient cohort treated with ceftolozane/tazobactam was similar compared with previous experiences. Ceftolozane/tazobactam remains an alternative agent for treatment of susceptible isolates of P. aeruginosa.

Risk Factors Associated with Severe Clostridioides difficile Infection in Patients with Cancer

INTRODUCTION

Antibiotic use is a risk factor for Clostridioides difficile infection (CDI). Few studies have correlated use of prior antibiotic classes with CDI, microbiome composition, and disease severity in patients with cancer. We hypothesized that previous antibiotic exposure and fecal microbiome composition at time of presentation are risk factors for severe CDI in patients with cancer.

METHODS

This non-interventional, prospective, cohort study examined 200 patients with cancer who had their first episode or first recurrence of CDI. C. difficile was identified using nucleic acid amplification testing. Univariate analysis was used to determine significant risk factors for severe CDI. Fecal microbiome composition was determined by sequencing the V3/V4 region of 16 s rDNA encoding gene. Differential abundance analyses were used to single out significant microbial features which differed across severity levels.

RESULTS

On univariate analysis, factors associated with severe CDI included the presence of toxin A/B in stools (odds ratio [OR] 2.14 [1.05-4.36] p = 0.04 and prior 90-day metronidazole use (OR 2.66 [1.09-6.50] p = 0.03). Although alpha and beta diversity was similar between disease severity groups and toxin A/B in stools, increased abundance of Bacteroides uniformis, Ruminococcaceae, and Citrobacter koseri were associated with protection from severe CDI (p < 0.05) and depletion of anaerobes was higher in patients with prior metronidazole exposure.

CONCLUSION

Use of metronidazole for non-CDI indications within 90 days prior to diagnosis and presence of toxin A/B in stools were associated with severe CDI. Findings provide valuable insights into risk factors for severe CDI in an underserved population with cancer that warrants further exploration.

Antibacterial data synthesis challenges: a systematic review of treatments for complicated gram-negative urinary tract infections

Aim: To determine the suitability of network meta-analysis (NMA) using antibacterial treatment evidence in complicated urinary tract infection. Materials & methods: We conducted a systematic literature review to identify published clinical trial data for complicated urinary tract infection treatments. We performed a feasibility assessment to determine whether the available evidence would support the creation of a robust NMA, considering key assumptions of homogeneity, similarity and consistency. Results: Twenty-five trials met eligibility criteria. Risk of bias was low, and individual studies met their primary end point(s). Assumptions central to the conduct of a robust NMA were not met. Heterogeneity was ubiquitous, including baseline pathogen, treatment and patient characteristics. Conclusion: Limited and heterogeneous data identified make the use of NMA to compare novel antibacterial agents impractical and likely unreliable.

Systematic Literature Review of Real-world Evidence of Ceftolozane/Tazobactam for the Treatment of Respiratory Infections

Introduction

Gram-negative nosocomial pneumonia (NP), including hospital-acquired bacterial pneumonia (HABP), ventilated HABP (vHABP), and ventilator-associated bacterial pneumonia (VABP), is a significant cause of morbidity and mortality. Common pathogens, including Enterobacterales and Pseudomonas aeruginosa, are prevalent in healthcare settings and have few effective treatment options due to high rates of antibacterial resistance. Resistant pathogens are associated with significantly worse outcomes, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials of patients with NP. This review aims to collate data on C/T use for HABP/vHABP/VABP infections in real-world clinical practice.

Methods

This systematic literature review searched online biomedical databases for real-world studies of C/T used to treat Gram-negative respiratory tract infections (RTIs) between January 2009 and June 2020.

Results

Thirty-three studies comprising 658 patients were identified. Pneumonia was the most common infection treated with C/T (85%), with a smaller number of unspecified RTIs (9%) and tracheobronchitis (5%) reported. The majority of patients had respiratory infections caused by P. aeruginosa (92.8%), of which 88.1% were multidrug-resistant. Examination of these studies demonstrated an increase in the percentage of patients receiving the recommended dose of C/T for respiratory infections (3 g q8h or renal impairment-adjusted) over time (36.8% of patients in 2017 to 71.5% in 2020). Clinical success rates ranged from 51.4 to 100%, with 10 studies (55.6% of studies reporting clinical success) reporting clinical success rates of > 70%; microbiological success rates ranged from 57.0 to 100.0%, with three studies (60.0% of studies reporting microbiological success) reporting microbiological success rates of > 70%. Thirty-day mortality ranged from 0.0 to 33.0%, with nine studies (90% of studies reporting mortality) reporting 30-day mortality of < 30%.

Conclusions

The studies identified in this review demonstrate that C/T shows similar outcomes as those seen in clinical trials, despite the higher frequency of multidrug-resistant pathogens, and comorbidities that may have been excluded from the trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00491-x.

Real-world use of ceftolozane/tazobactam: a systematic literature review

Background

Antibacterial-resistant gram-negative infections are a serious risk to global public health. Resistant Enterobacterales and Pseudomonas aeruginosa are highly prevalent, particularly in healthcare settings, and there are limited effective treatment options. Patients with infections caused by resistant pathogens have considerably worse outcomes, and incur significantly higher costs, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials. This review aimed to collate data on C/T use in clinical practice.

Methods

This systematic literature review searched online biomedical databases for real-world studies of C/T for gram-negative infections up to June 2020. Relevant study, patient, and treatment characteristics, microbiology, and efficacy outcomes were captured.

Results

There were 83 studies comprising 3,701 patients were identified. The most common infections were respiratory infections (52.9% of reported infections), urinary tract infections (UTIs; 14.9%), and intra-abdominal infections (IAIs; 10.1%). Most patients included were seriously ill and had multiple comorbidities. The majority of patients had infections caused by P.aeruginosa (90.7%), of which 86.0% were antimicrobial-resistant. C/T was used as both a 1.5 g q8h and 3 g q8h dose, for a median duration of 7–56 days (varying between studies). Outcome rates were comparable between studies: clinical success rates ranged from 45.7 to 100.0%, with 27 studies (69%) reporting clinical success rates of > 70%; microbiological success rates ranged from 31 to 100%, with 14 studies (74%) reporting microbiological success rates of > 70%. Mortality rates ranged from 0 to 50%, with 31 studies (69%) reporting mortality rates of ≤ 20%. In comparative studies, C/T was as effective as aminoglycoside- or polymyxin-based regimens, and in some instances, significantly more effective.

Conclusions

The studies identified in this review demonstrate that C/T is effective in clinical practice, despite the diverse group of seriously ill patients, different levels of resistance of the pathogens treated, and varying dosing regimens used. Furthermore, comparative studies suggest that C/T offers a successful alternative to standard of care (SoC).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00933-8.

Healthcare Resource Utilization of Ceftolozane/Tazobactam Versus Meropenem for Ventilated Nosocomial Pneumonia from the Randomized, Controlled, Double-Blind ASPECT-NP Trial

Introduction

Hospital-acquired and ventilator-associated bacterial pneumonia (HABP and VABP) are associated with significant healthcare resource utilization (HCRU). This a priori, exploratory, secondary analysis from the ASPECT-NP clinical trial evaluated resource utilization among patients with ventilated HABP (vHABP)/VABP treated with ceftolozane/tazobactam or meropenem.

Methods

This analysis used data from the randomized, double-blind, noninferiority phase 3 ASPECT-NP trial of patients with vHABP/VABP randomized to receive ceftolozane/tazobactam 3 g (ceftolozane 2 g/tazobactam 1 g) or meropenem 1 g for 8–14 days. Day 28 outcomes included hospital length of stay (LOS), intensive care unit (ICU) LOS, and time to mechanical ventilation extubation in the microbiological intention-to-treat (mITT) population and in an HCRU population. The HCRU population, a subset of patients from the mITT population that were alive at day 28, was used to remove resource use bias influenced by mortality rates.

Results

Ceftolozane/tazobactam-treated versus meropenem-treated patients, respectively, had fewer deaths (20.1% vs. 25.5%), fewer hospital discharges (30.7% vs. 32.4%), and higher ICU discharges (60.0% vs. 58.3%) and extubations (51.9% vs. 48.2%) by day 28. In the HCRU population, adjusted LOS differences (95% confidence intervals) for ceftolozane/tazobactam compared with meropenem were 0.1 (− 1.4 to 1.6) hospitalization days, − 1.4 (− 2.9 to 0.2) ICU days, and − 0.9 (− 2.4 to 0.7) mechanical ventilation days. Patterns were similar among the VABP and Pseudomonas aeruginosa subgroups.

Conclusion

Similar 28-day resource utilization outcomes were observed between ceftolozane/tazobactam and meropenem in the mITT population of patients from ASPECT-NP with vHABP/VABP due to gram-negative pathogens. ASPECT-NP was not powered to detect differences in resource utilization outcomes between treatment groups; however, numerical differences in ICU LOS and duration of mechanical ventilation were noted. Further study is needed to assess resource utilization in the real-world practice setting, especially among patients excluded from ASPECT-NP, including those with resistant P. aeruginosa infections.

Trial Registrations

ClinicalTrials.gov: NCT02070757, registered February 25, 2014; EudraCT: 2012-002862-11.

Electronic supplementary material

The online version of this article (10.1007/s40121-020-00343-0) contains supplementary material, which is available to authorized users.

Opportunities for antimicrobial stewardship in patients with acute bacterial skin and skin structure infections who are unsuitable for beta-lactam antibiotics: a multicenter prospective observational study

Purpose:

The objective of this prospective, observational study was to describe the treatment, severity assessment and healthcare resources required for management of patients with acute bacterial skin and skin structure infections who were unsuitable for beta-lactam antibiotic treatments.

Methods:

Patients were enrolled across five secondary care National Health Service hospitals. Eligible patients had a diagnosis of acute bacterial skin and skin structure infection and were considered unsuitable for beta-lactam antibiotics (e.g. confirmed/suspected methicillin-resistant Staphylococcus aureus, beta-lactam allergy). Data regarding diagnosis, severity of the infection, antibiotic treatment and patient management were collected.

Results:

145 patients with acute bacterial skin and skin structure infection were included; 79% (n = 115) patients received greater than two antibiotic regimens; median length of the first antibiotic regimen was 2 days (interquartile range of 1–5); median time to switch from intravenous to oral antibiotics was 4 days (interquartile range of 3–8, n = 72/107); 25% (n = 10/40) patients with Eron class 1 infection had systemic inflammatory response syndrome, suggesting they were misclassified. A higher proportion of patients with systemic inflammatory response syndrome received treatment in an inpatient setting, and their length of stay was prolonged in comparison with patients without systemic inflammatory response syndrome.

Conclusion:

There exists an urgent need for more focused antimicrobial stewardship strategies and tools for standardised clinical assessment of acute bacterial skin and skin structure infection severity in patients who are unsuitable for beta-lactam antibiotics. This will lead to optimised antimicrobial treatment strategies and ensure effective healthcare resource utilisation.

Effectiveness of a low support, remotely accessible, cognitive remediation training programme for chronic psychosis: cognitive, functional and cortical outcomes from a single blind randomised controlled trial

BACKGROUND

Cognitive remediation (CR) training has emerged as a promising approach to improving cognitive deficits in schizophrenia and related psychosis. The limited availability of psychological services for psychosis is a major barrier to accessing this intervention however. This study investigated the effectiveness of a low support, remotely accessible, computerised working memory (WM) training programme in patients with psychosis.

METHODS

Ninety patients were enrolled into a single blind randomised controlled trial of CR. Effectiveness of the intervention was assessed in terms of neuropsychological performance, social and occupational function, and functional MRI 2 weeks post-intervention, with neuropsychological and social function again assessed 3-6 months post-treatment.

RESULTS

Patients who completed the intervention showed significant gains in both neuropsychological function (measured using both untrained WM and episodic task performance, and a measure of performance IQ), and social function at both 2-week follow-up and 3-6-month follow-up timepoints. Furthermore, patients who completed MRI scanning showed improved resting state functional connectivity relative to patients in the placebo condition.

CONCLUSIONS

CR training has already been shown to improve cognitive and social function in patient with psychosis. This study demonstrates that, at least for some chronic but stable outpatients, a low support treatment was associated with gains that were comparable with those reported for CR delivered entirely on a 1:1 basis. We conclude that CR has potential to be delivered even in services in which psychological supports for patients with psychosis are limited.

Computerised working-memory focused cognitive remediation therapy for psychosis--A preliminary study

BACKGROUND

Cognitive deficits are a core feature of schizophrenia and related psychotic disorders and are associated with decreased levels of functioning. Behavioural interventions have shown success in remediating these deficits; determining how best to maximise this benefit while minimising the cost is an important next step in optimising this intervention for clinical use.

AIMS

To examine the effects of a novel working-memory focused cognitive remediation (CR) training on cognitive difficulties based on internet delivery of training and weekly telephone support.

METHOD

Participants with a diagnosis of psychosis (n=56) underwent either 8 weeks of CR (approximately 20 h) or 8 weeks of treatment as usual (TAU). General cognitive ability, working memory and episodic memory were measured both pre and post intervention for all participants.

RESULTS

In addition to improvements on trained working memory tasks, CR training was associated with significant improvements in two tests of verbal episodic memory. No association between CR and changes in general cognitive ability was observed. Effect sizes for statistically significant changes in memory were comparable to those reported in the literature based primarily on 1:1 training.

CONCLUSIONS

The cognitive benefits observed in this non-randomised preliminary study indicate that internet-based working memory training can be an effective cognitive remediation therapy. The successes and challenges of an internet-based treatment are discussed.

Mitral regurgitation - Unmet need for improved management strategies

Background

The management of mitral regurgitation (MR) is challenging — patients may be asymptomatic, oligosymptomatic, older with comorbidities, or clinically symptomatic and not appropriate for surgery. The current review assesses morbidity, mortality, and risk factors associated with functional and organic MR, with a focus on severe MR.

Methods

A structured literature review was conducted in MEDLINE, Embase, the Cochrane Library, and via hand-searching of conference proceedings. Prospective randomised controlled trials and observational studies including adult patients with MR reporting on treatment response rates, survival, time-to-treatment failure, quality of life, and adverse events were eligible for inclusion.

Results

In total, 32 publications met the inclusion criteria (9 in functional, 18 in organic, and 5 in functional/organic). Despite study heterogeneity, an increased risk of mortality and morbidity was observed which increased with MR severity. Risk factors associated with mortality and morbidity included advancing age, presence of atrial fibrillation, increasing effective regurgitant orifice, ejection fraction, left ventricle end systolic diameter, diabetes, and increasing New York Heart Association class.

Conclusions

The current review represents one of the most comprehensive conducted in the medical/conservative management of MR. An increased risk of mortality and morbidity, which appeared to rise with greater severity, was associated with MR (versus no MR). An unmet need exists in the management of patients with severe symptomatic MR and a high surgical risk as they have a poor prognosis and limited treatment options. Further research into alternative medical strategies and patient management is needed to improve prognoses and reduce mortality and morbidity.

Marketing by hospitals: myths and realities

Is marketing by hospitals myth or reality? This article explores five myths of marketing as well as examines the perceptions of hospital administrators concerning the appropriateness of a number of marketing techniques. The opinions of these administrators indicate several opportunities for expanding the usefulness of marketing by hospitals.

A microscale model of bacterial and biofilm dynamics in porous media

A microscale model for the transport and coupled reaction of microbes and chemicals in an idealized two-dimensional porous media has been developed. This model includes the flow, transport, and bioreaction of nutrients, electron acceptors, and microbial cells in a saturated granular porous media. The fluid and chemicals are represented as a continuum, but the bacterial cells and solid granular particles are represented discretely. Bacterial cells can attach to the particle surfaces or be advected in the bulk fluid. The bacterial cells can also be motile and move preferentially via a run and tumble mechanism toward a chemoattractant. The bacteria consume oxygen and nutrients and alter the profiles of these chemicals. Attachment of bacterial cells to the soil matrix and growth of bacteria can change the local permeability. The coupling of mass transport and bioreaction can produce spatial gradients of nutrients and electron acceptor concentrations. We describe a numerical method for the microscale model, show results of a convergence study, and present example simulations of the model system.

An analysis of the implications of a magnetic field threshold limit value on utility work practices

This article examines the implications of a 10 gauss (G) occupational threshold limit value (TLV) on the work practices of a utility that must maintain and repair 500 and 230 kV transmission lines. Three work practices are compared: bare-handed work with live lines (the current practice at the example utility), use of hot sticks, and de-energizing lines prior to work. Bare-handed work with live lines leads to occasional exceedances of the 10 G TLV. Use of hot sticks and de-energizing lines eliminate these exceedances, but they do so at a price. Both practices increase the job duration and, as a result, may increase occupational injury risks. The annual costs for the current live-line, bare-handed practice is approximately $175,000. Use of hot sticks increases this annual cost of maintenance and repair by 30 to 55%. De-energizing lines can increase annual costs by $4 million to $14 million, due to the need for adding additional electricity generation during the planned outages. De-energizing lines also increases the risk to service reliability slightly.

A mathematical model for outgrowth and spatial patterning of the vertebrate limb bud

A new model for limb development which incorporates both outgrowth due to cell growth and division, and interactions between morphogens produced in the zone of polarizing activity (ZPA) and the apical epidermal ridge (AER) is developed and analysed. The numerically-computed spatio-temporal distributions of these morphogens demonstrate the importance of interaction between the organizing regions in establishing the morphogenetic terrain on which cells reside, and because growth is explicitly incorporated, it is found that the history of a cell's exposure to the morphogens depends heavily on where the cell originates in the early limb bud. Because the biochemical steps between morphogen(s) and gene activation have not been elucidated, there is no biologically-based mechanism for translating the spatio-temporal distributions of morphogens into patterns of gene expression, but several theoretically plausible functions that bridge the gap are suggested. For example it is shown that interpretation functions based on the history of a cell's exposure to the morphogens can qualitatively account for observed patterns of gene expression. The mathematical model and the associated computational algorithms are sufficiently flexible that other schemes for the interactions between morphogens, and their effect on the spatio-temporal pattern of growth and gene expression, can easily be tested. Thus an additional result of this work is a computational tool that can be used to explore the effects of various mutations and experimental interventions on the growth of the limb and the pattern of gene expression. In future work we will extend the model to a three-dimensional representation of the limb and will incorporate a more realistic description of the rheological properties of the tissue mass, which here is treated as a Newtonian fluid.

Clinical significance of feline heartworm disease

The clinical signs and diagnostic approach are different in the cat as compared with the dog, which has impaired the veterinarian's ability to detect this parasite in the cat. New techniques and methodologies have enabled the cat owner and veterinarian to recognize this potentially severe disease. Although much is now known about the pathophysiology and biology of this parasite in the cat, the practical application and rapid development of this information to daily practice has led to confusion.

Volume-overload cardiac hypertrophy is unaffected by ACE inhibitor treatment in dogs

We tested the hypothesis that angiotensin-converting enzyme (ACE) inhibitor therapy prevents volume-overload hypertrophy in dogs with chronic mitral regurgitation (MR). Seven adult mongrel dogs receiving ramipril (R; 10 mg orally, twice/day) for 4 mo were compared with 11 dogs receiving no R (N) for 4 mo after induction of MR. Cine-magnetic resonance imaging demonstrated that left ventricular (LV) mass increased in the R-MR dogs [80 +/- 4 (SE) to 108 +/- 7 g, P < 0.01] and in the N-MR dogs (92 +/- 7 to 112 +/- 8 g, P < 0.001). LV myocyte cell length was greater in the R-MR and N-MR dogs (203 +/- 6 and 177 +/- 10 microns, respectively) than in normal (144 +/- 4 microns, P < 0.05) dogs. There was significant loss of the collagen weave pattern by scanning electron microscopy in both R-MR and N-MR dogs. LV ACE and chymase activities were significantly elevated in R-MR and N-MR compared with normal dogs. LV angiotensin II (ANG II) levels in the R-MR dogs (28 +/- 12 pg/g) were reduced to levels seen in normal dogs (28 +/- 4 pg/g) compared with N-MR dogs (72 +/- 11 pg/g, P < 0.05). Steady-state AT1-receptor mRNA levels decreased 66% in N-MR compared with normal dogs (P < 0.001) and increased 1.5-fold in R-MR compared with normal dogs (P < 0.01). Thus upregulation of the AT1 receptor in the R-MR hearts may provide a mechanism by which normal intracardiac ANG II levels could continue to mediate LV hypertrophy. However, the mechanism of dissolution collagen weave in both N-MR and R-MR hearts may be related to the stretch of volume overload.

A microscale model of bacterial swimming, chemotaxis and substrate transport

In this paper, we introduce a mathematical and computational model at the microscale level of bacterial motility and chemotaxis coupled with the advection and diffusion of a biologically reacting substrate. The hydrodynamic interaction of a small bacterial population is explicitly modelled through the use of discrete representations of individual microbes. We use the immersed boundary method to couple microbial motion and the advection-diffusion of substrate with the full incompressible Navier-Stokes equations. Simulations using a preliminary two-dimensional model are presented, demonstrating the mutual dependence through the fluid media of several swimming bacteria. A run and tumble mechanism is introduced for simulating the chemotaxis of swimming bacteria.

Increased ACE and chymase-like activity in cardiac tissue of dogs with chronic mitral regurgitation

The current study was designed to test the hypothesis that intracardiac angiotensin-converting enzyme (ACE) activity, chymase-like activity, and angiotensin (ANG) peptide levels are increased and are positively related to wall stress estimates in response to the chronic low pressure volume overload of mitral regurgitation produced by percutaneous chordal rupture in the dog. Chronic mitral regurgitation (MR) resulted in an increase in left ventricular (LV) end-diastolic volume [59 +/- 11 (SD) to 103 +/- 32 ml, P < 0.001], LV mass (96 +/- 17 to 114 +/- 23 g, P < 0.001), and a decrease in the LV mass-to-end-diastolic volume ratio (1.64 +/- 0.22 to 1.16 +/- 0.23 g/ml, P < 0.001) measured by magnetic resonance imaging. In vitro studies of heart tissue extracts demonstrated that the majority of ANG II-forming activity was from chymase-like activity rather than from ACE activity in five normal (83.5 +/- 7.5 vs. 6.04 +/- 5.2%) and seven MR hearts (86 +/- 3.9 vs. 2.6 +/- 1.7%). ACE activity (1.22 +/- 0.22 vs. 3.55 +/- 0.62 mU/g, P < 0.05) and chymase-like activity (9.42 +/- 4.64 vs. 20.60 +/- 8.41 nmol.g-1.min-1, P < 0.05) were increased in MR compared with normal hearts. ACE activity correlated with the LV mass-to-volume ratio (r = -0.93, P < 0.001) and LV diastolic wall stress ( r = 0.71, P < 0.05); however, chymase-like activity did not correlate with any hemodynamic parameter. ANG II levels were significantly higher in the midwall of the left ventricle in MR hearts than in normal controls (85 +/- 39 vs. 27 +/- 16 pg/g, P < 0.01). Our results demonstrate a positive correlation between LV diastolic wall stress and increased ACE activity with increased ANG II stores, suggesting that mechanical wall stress activated intracardiac ACE. Although chymase accounted for most ANG II formation in vitro in extracts of both normal and MR dog hearts, the significance of this enzyme in vivo remains unclear.

Occurrence of Listeria in hot and cold smoked seafood products

Over a one-year period, 258 samples of smoked fish products were obtained from retail outlets in Newfoundland and processed for Listeria. Of these, 142 were hot smoked and 116 cold smoked, and the samples comprised of nine species of fish. The Canadian FDA listeria isolation protocol consisted of a two-stage enrichment followed by plating on selective isolation media, Oxford, and LPM. An additional selective medium, PALCAM, was also used. Listeria spp. were isolated from 43 of 258 (16.7%) samples processed in all, with hot smoked products yielding 25.4% (36/142) of the isolates, and cold smoked products yielding 6% of the isolates (7/116). Among the nine species tested, cod had the highest rate of Listeria contamination at 46.7%. Of the 43 Listeria spp. isolated, 18 (41.9%) were L. innocua, 13 (30.2%) were L. welshimeri and 12 (27.9%) were L. monocytogenes.

Visceral leishmaniasis in Teresina, n. e. Brazil: towards a DNA probe kit and its adaptation to processing blood-contaminated samples

The Lmet2 chemiluminescent DNA probe is a valuable tool for identifying parasites of the Leishmania donovani -complex in sand flies, dogs and human samples. Recent blood meals in sand flies or blood contamination of tissue samples inhibited probe sensitivity, whether radiolabelled or chemiluminescent detection systems were used. Treatment of membranes with protease before hybridisation restored positive signal. Alternatively samples could be lysed with protease and applied to membranes with a vacuum blotting apparatus. The Lmet2 protocol provides the basis for a DNA probe kit that is adaptable for use with a wide range of other probes.

Charge-transfer-plate spatial light modulators

Charge-transfer-plate spatial light modulators (CTPSLM's) are a class of devices that employ chargetransfer plates as the interface between the charge-generation element and the light-modulation element. Both optically addressed and electrically addressed devices have been built. Chargegenerating elements for the optically addressed devices include photoconductors, photodiode and phototransistor arrays, optoelectronic integrated circuit chips, and photocathode-microchannel-plate assemblies. For electrically addressed devices, electron guns, very large-scale integrated circuits, thin-film transistors, and matrix electrodes are among the possible charge-generation elements. Lightmodulation elements used in CTPSLM's include liquid crystals, electro-optic organic and inorganic crystals, polymers, deformable membrane mirrors, oil films, multilayer dielectric films, and electroluminescent films. In principle, all combinations of charge-generation elements and light-modulating elements are possible. This paper explores the fundamental performance limitations of CTP technology, and describes the design, operation, and applications of five different CTPSLM's (three based on membrane-mirror technology and two on liquid-crystal technology).

A multimedia medical communication link between a radiology department and an emergency department

The most critical aspect of a radiologist's work is communicating his findings to the attending physician responsible for the patient's care. This is also the part of the process that is least well organized and the most subject to failure. At the University of Ottawa Medical Communications Research Centre we are investigating technical means to improving communications between radiologists and attending physicians. We first introduce the radiology communication service problem and show why it is essentially a multimedia communication problem. We then briefly describe a multimedia communication system designed and implemented by our research team. The multimedia system consists of several work stations linked by the Hospital's local area network (LAN). Each physician work station comprises a Compaq 386/20-Mhz microcomputer with 16 Mbytes of RAM, a 500-Mbyte image disk, and an image memory that drives a 1,000-line monochrome monitor. The images are digitized using a Konica laser-based film digitizer (2430 by 2000 10-bit pixels for a standard chest radiograph). The multimedia file server manager station is built around a PC-AT compatible with a Northern Telecom Meridian SL-1ST digital PBX and a Meridian Mail digital voice messaging system. This last device is used to store voice data and is linked via the PBX to the workstations' digital telephones. A Sytek 6,000 LAN links all work stations to the file server. All data, image, and graphic information is transmitted via this network, while the twisted pair connections linking the digital PBX to the telephone sets are used for transmitting voice data.(ABSTRACT TRUNCATED AT 250 WORDS)

Context-dependent enhancements for radiological images

Many techniques have been proposed to enhance radiographic images and each of them may be optimal depending upon the circumstances. However, the problem confronting the radiologist or the physician is which enhancement to use and how to select the parameters when a specific feature is to be emphasized. At the University of Ottawa, our research work is oriented towards automatic context-dependent enhancements. Our approach attempts to match the three phases involved in viewing a radiograph: getting a global impression, analyzing the objects and the local features, and focusing on the image perturbations. In this article, we report on enhancements to support the first two phases in the case of chest radiographs and on the applicability of gray level reversal transformations.

The liver in systemic disease. An innocent bystander

The role of the liver in maintaining the health and function of other organs is frequently described in pathophysiologic terms. A large volume of information has been gleaned on the biochemistry and physiology of the "primary" hepatic diseases. In the dog, there is a paucity of information about the chemical events essential to the viability of normal liver cells and, more specifically, the mechanisms by which diseases of other organs secondarily affect the liver.

Cost-based fee-setting for therapeutic consulting services

A method for developing cost-based dietetic consulting fees is presented which can be applied in hospital in-patient and out-patient departments and in private practice. Limitations and advantages of the method are noted. The advantages outweigh the drawbacks.