Computed tomographic angiography measures of coronary plaque in clinical trials: opportunities and considerations to accelerate drug translation

Atherosclerotic coronary artery disease (CAD) is the causal pathological process driving most major adverse cardiovascular events (MACE) worldwide. The complex development of atherosclerosis manifests as intimal plaque which occurs in the presence or absence of traditional risk factors. There are numerous effective medications for modifying CAD but new pharmacologic therapies require increasingly large and expensive cardiovascular outcome trials to assess their potential impact on MACE and to obtain regulatory approval. For many disease areas, nearly a half of drugs are approved by the U.S. Food & Drug Administration based on beneficial effects on surrogate endpoints. For cardiovascular disease, only low-density lipoprotein cholesterol and blood pressure are approved as surrogates for cardiovascular disease. Valid surrogates of CAD are urgently needed to facilitate robust evaluation of novel, beneficial treatments and inspire investment. Fortunately, advances in non-invasive imaging offer new opportunity for accelerating CAD drug development. Coronary computed tomography angiography (CCTA) is the most advanced candidate, with the ability to measure accurately and reproducibly characterize the underlying causal disease itself. Indeed, favourable changes in plaque burden have been shown to be associated with improved outcomes, and CCTA may have a unique role as an effective surrogate endpoint for therapies that are designed to improve CAD outcomes. CCTA also has the potential to de-risk clinical endpoint-based trials both financially and by enrichment of participants at higher likelihood of MACE. Furthermore, total non-calcified, and high-risk plaque volume, and their change over time, provide a causally linked measure of coronary artery disease which is inextricably linked to MACE, and represents a robust surrogate imaging biomarker with potential to be endorsed by regulatory authorities. Global consensus on specific imaging endpoints and protocols for optimal clinical trial design is essential as we work towards a rigorous, sustainable and staged pathway for new CAD therapies.

Anatomic and functional discordance among patients with non-obstructive coronary disease

Background

Non-obstructive coronary artery disease (CAD) is associated with increased adverse cardiovascular (CV) events. However, it is unclear if functional stenosis, as assessed by FFRCT <0.80, further stratifies risk among patients with non-obstructive CAD and which factors contribute to this anatomic-functional discordance (stenosis <50% and FFRCT <0.80).

Purpose

We hypothesized that patients with anatomically non-obstructive CAD by CTA and an abnormal FFRCT value of ≤0.80 have a phenomenon termed anatomic-functional discordance, and this discordance would be associated with increased adverse outcomes.

Methods

Patients in the ADVANCE (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care) Registry who had exclusively non-obstructive CAD (anatomic stenosis <50%) were stratified by FFRCT >0.80 in all coronary vessels (concordant) vs. FFRCT <0.80 in at least one vessel (discordant). Baseline patient demographics, coronary computed tomography angiography findings, downstream testing and clinical outcomes were compared between groups. The primary composite endpoint included revascularization, CV hospitalization, heart failure, arrhythmia, non-fatal myocardial infarction, unplanned hospitalization for an acute coronary syndrome leading to urgent revascularization, and all-cause death.

Results

Among 1,261 patients with non-obstructive CAD, 543 (43.1%) had functional stenosis with FFRCT <0.80. Patients in the discordant group were older, more likely to have hypertension, hyperlipidemia, and had significantly higher indexed left ventricular (LV) mass and significantly lower coronary volume-to-mass ratios when compared with patients in the concordant group. Downstream non-invasive testing was more common among patients with discordance (35.9% vs 20.2%, p<0.0001) and more frequently resulted in a positive downstream test (10.3% vs. 3.3%, p<0.0001). Invasive angiography was also more common among patients with discordance (25.2% vs. 11.6%, p<0.0001). Anatomic-functional discordance was associated with higher rates of CV hospitalization and percutaneous coronary intervention (both p<0.0001), but no significant difference in all-cause death. After adjustment, anatomic-functional discordance was associated with a significantly higher risk of the composite endpoint (adjusted HR 2.79, 95% CI 1.67–4.65), Figure 1. As shown in Figure 2, the more vessels with anatomic-functional discordance, the higher the rate of adverse cardiac events.

Conclusion

Anatomic-functional discordance was present in nearly half of patients with exclusively non-obstructive CAD. The lower coronary volume: LV mass ratio may reflect abnormal coronary physiology at lower thresholds of anatomical stenosis among those with discordance. Compared to patients with concordance, patients with discordance had worse clinical outcomes suggesting that anatomic-functional discordance may stratify risk for adverse CV events among patients with non-obstructive CAD.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): The analysis was an investigator-initiated analysis sponsored by Heart Flow.

Invasive mammary carcinoma in a black-handed spider monkey (Ateles geoffroyi)

Mammary neoplasia is rare in nonhuman primates other than macaques; records in New World primates are exceedingly rare. We report the pathologic and immunohistochemical features of an invasive carcinoma no special type with neuroendocrine differentiation in a captive, black-handed spider monkey (Ateles geoffroyi).

Fractional flow reserve derived from computed tomography coronary angiography in the assessment and management of stable chest pain: the FORECAST randomized trial

Aims 

Fractional flow reserve (FFR_CT) using computed tomography coronary angiography (CTCA) determines both the presence of coronary artery disease and vessel-specific ischaemia. We tested whether an evaluation strategy based on FFR_CT would improve economic and clinical outcomes compared with standard care.

Methods and results 

Overall, 1400 patients with stable chest pain in 11 centres were randomized to initial testing with CTCA with selective FFR_CT (experimental group) or standard clinical care pathways (standard group). The primary endpoint was total cardiac costs at 9 months. Secondary endpoints were angina status, quality of life, major adverse cardiac and cerebrovascular events, and use of invasive coronary angiography. Randomized groups were similar at baseline. Most patients had an initial CTCA: 439 (63%) in the standard group vs. 674 (96%) in the experimental group, 254 of whom (38%) underwent FFR_CT. Mean total cardiac costs were higher by £114 (+8%) in the experimental group, with a 95% confidence interval from −£112 (−8%) to +£337 (+23%), though the difference was not significant (P = 0.10). Major adverse cardiac and cerebrovascular events did not differ significantly (10.2% in the experimental group vs. 10.6% in the standard group) and angina and quality of life improved to a similar degree over follow-up in both randomized groups. Invasive angiography was reduced significantly in the experimental group (19% vs. 25%, P = 0.01).

Conclusion 

A strategy of CTCA with selective FFR_CT in patients with stable angina did not differ significantly from standard clinical care pathways in cost or clinical outcomes, but did reduce the use of invasive coronary angiography.

Pre-migration TB screening-the first step is always the hardest

As the proportion of foreign-born persons among TB notifications continues to rise, Japan is preparing to introduce pre-migration TB screening for those coming from selected countries, who are intending to stay for more than 90 days. It has announced that the programme will commence in 2020. In this review, the authors examine the experiences from two countries which already have years of experience in operating pre-migration TB screening, namely the United Kingdom and Australia. The authors point out that both countries have developed strong health information system not only to collect and analyse screening results, but also to use the data to effectively monitor and evaluate the screening programme itself. The critical role which health information system plays within pre-migration screening is often overlooked. Here we argue that Japan, as with any other countries planning to introduce pre-migration screening for TB, must also plan for data management.

Estimating Aspergillus fumigatus exposure from outdoor composting activities in England between 2005 and 14

Bioaerosols, ubiquitous in ambient air, are released in elevated concentrations from composting facilities with open-air processing areas. However, spatial and temporal variability of bioaerosols, particularly in relation to meteorology, is not well understood. Here we model relative concentrations of Aspergillus fumigatus at each postcode-weighted centroid within 4 km of 217 composting facilities in England between 2005 and 2014. Facilities were geocoded with the aid of satellite imagery. Data from existing bioaerosol modelling literature were used to build emission profiles in ADMS. Variation in input parameters between each modelled facility was reduced to a minimum. Meteorological data for each composting facility was derived from the nearest SCAIL-Agriculture validated meteorological station. According to our results, modelled exposure risk was driven primarily by wind speed, direction and time-varying emissions factors incorporating seasonal fluctuations in compostable waste. Modelled A.fumigatus concentrations decreased rapidly from the facility boundary and plateaued beyond 1.5-2.0 km. Where multiple composting facilities were within 4 km of each other, complex exposure risk patterns were evident. More long-term bioaerosol monitoring near facilities is needed to help improve exposure estimation and therefore assessment of any health risks to local populations.

Cross-border collaboration for improved tuberculosis prevention and care: policies, tools and experiences

As tuberculosis (TB) spreads beyond borders with people movements, several interventions ensuring the continuity of care are essential, although difficult to put in place in the absence of well-defined agreements allowing data sharing and easy referral of patients to appropriate health facilities. This article first sets out general principles for cross-border collaboration and continuity of care. It then presents a series of case studies. Policies and practices on cross-border collaboration in selected low-incidence countries (Australia, Italy, Norway, The Netherlands, the United Kingdom and the United States) are described and critically appraised. Details of the World Health Organization's (WHO's) European Respiratory Society TB Consilium for transborder migration and those of the Health Network's TBNet activities are described. With increasing population movement, including migrants and travellers, it is time to build on good practices and existing tools and to remove legal, financial and social barriers to ensure early diagnosis, full treatment and continuity of care across our world. Data sharing between the sending and the receiving countries is of utmost importance and must be conducted in line with privacy protection rules. Successful implementation of these interventions is key to being on track with the WHO's End TB strategy targets for 2030.

Radiotherapy for anal squamous cell carcinoma: must the upper pelvic nodes and the inguinal nodes be treated?

BACKGROUND

Loco-regional failure is the predominant cause of death in anal squamous cell carcinoma. We assessed patterns of loco-regional recurrence to determine the impact of radiotherapy (RT) volumes on patient outcome.

METHODS

Retrospective clinical study, including patients treated curatively with RT or chemo-radiotherapy between 1994 and 2007. RT fields/volumes were reviewed and compared with patterns of failure. Patients were classified as having whole pelvic radiotherapy (WPRT) if RT extended to L5/S1 or lower pelvic radiotherapy (LPRT) if it extended to the lower sacroiliac joints or below. Patients with negative inguinal nodes either underwent prophylactic inguinal radiotherapy (PIRT) or had inguinal observation (IO). Patterns of failure were compared.

RESULTS

Twenty-seven patients (53%) had WPRT and 24 (47%) had LPRT. Forty-two patients had negative inguinal nodes: 29 (69%) had PIRT and 13 (31%) had IO. Median follow-up was 5.8 years. Twelve regional failures occurred in eight patients: three pelvic, one inguinal and four pelvic and inguinal. All patients with regional failure died of disease. Pelvic nodal failure was 7.7% in N0 and 33% in N1-3 patients (P = 0.012). There was no difference in pelvic regional failure between WPRT and LPRT (11% versus 16%, P = 0.64). There was only one possible regional failure above LPRT in this group (4%). Inguinal failure was 0% in the PIRT group compared with 23% in IO group (P = 0.009).

CONCLUSION

There was no difference in pelvic regional failure between WPRT and LPRT. LPRT is likely to be safe in N0 patients. Inguinal nodes should be treated in all patients.

Use of dispersion modelling for Environmental Impact Assessment of biological air pollution from composting: Progress, problems and prospects

With the increase in composting asa sustainable waste management option, biological air pollution (bioaerosols) from composting facilities have become a cause of increasing concern due to their potential health impacts. Estimating community exposure to bioaerosols is problematic due to limitations in current monitoring methods. Atmospheric dispersion modelling can be used to estimate exposure concentrations, however several issues arise from the lack of appropriate bioaerosol data to use as inputs into models, and the complexity of the emission sources at composting facilities. This paper analyses current progress in using dispersion models for bioaerosols, examines the remaining problems and provides recommendations for future prospects in this area. A key finding is the urgent need for guidance for model users to ensure consistent bioaerosol modelling practices.

Capacity strengthening through pre-migration tuberculosis screening programmes: IRHWG experiences

Effective tuberculosis (TB) prevention and care for migrants requires population health-based approaches that treat the relationship between migration and health as a progressive, interactive process influenced by many variables and addressed as far upstream in the process as possible. By including capacity building in source countries, pre-migration medical screening has the potential to become an integral component of public health promotion, as well as infection and disease prevention, in migrant-receiving nations, while simultaneously increasing capabilities in countries of origin. This article describes the collaborative experiences of five countries (Australia, Canada, New Zealand, United Kingdom and the United States of America, members of the Immigration and Refugee Health Working Group [IRHWG]), with similar pre-migration screening programmes for TB that are mandated. Qualitative examples of capacity building through IRHWG programmes are provided. Combined, the IRHWG member countries screen approximately 2 million persons overseas every year. Large-scale pre-entry screening programmes undertaken by IRHWG countries require building additional capacity for health care providers, radiology facilities and laboratories. This has resulted in significant improvements in laboratory and treatment capacity, providing availability of these facilities for national public health programmes. As long as global health disparities and disease prevalence differentials exist, national public health programmes and policies in migrant-receiving nations will continue to be challenged to manage the diseases prevalent in these migrating populations. National TB programmes and regulatory systems alone will not be able to achieve TB elimination. The management of health issues resulting from population mobility will require integration of national and global health initiatives which, as demonstrated here, can be supported through the capacity-building endeavours of pre-migration screening programmes.

Sensitivity of predicted bioaerosol exposure from open windrow composting facilities to ADMS dispersion model parameters

Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are not well understood, and require improved exposure classification. Dispersion modelling has great potential to improve exposure classification, but has not yet been extensively used or validated in this context. We present a sensitivity analysis of the ADMS dispersion model specific to input parameter ranges relevant to bioaerosol emissions from open windrow composting. This analysis provides an aid for model calibration by prioritising parameter adjustment and targeting independent parameter estimation. Results showed that predicted exposure was most sensitive to the wet and dry deposition modules and the majority of parameters relating to emission source characteristics, including pollutant emission velocity, source geometry and source height. This research improves understanding of the accuracy of model input data required to provide more reliable exposure predictions.

Hydration education: developing, piloting and evaluating a hydration education package for general practitioners

OBJECTIVES

To (1) assess the hydration knowledge, attitudes and practices (KAP) of doctors; (2) develop an evidence-based training package; and (3) evaluate the impact of the training package.

DESIGN

Educational intervention with impact evaluation.

SETTING

Cambridgeshire, UK.

PARTICIPANTS

General practitioners (GPs (primary care physicians)).

INTERVENTIONS

Hydration and healthcare training.

MAIN OUTCOME MEASURES

Hydration KAP score before and immediately after the training session.

RESULTS

Knowledge gaps of doctors identified before the teaching were the definition of dehydration, European Food Safety Authority water intake recommendations, water content of the human body and proportion of water from food and drink. A face-to-face teaching package was developed on findings from the KAP survey and literature search. 54 questionnaires were completed before and immediately after two training sessions with GPs. Following the training, total hydration KAP scores increased significantly (p<0.001; median (25th, 75th centiles); 32 (29, 34)). Attendees rated the session as excellent or good (90%) and reported the training was likely to influence their professional practice (100%).

CONCLUSIONS

The training package will continue to be developed and adapted, with increased focus on follow-up strategies as well as integration into medical curricula and standards of practice. However, further research is required in the area of hydration care to allow policymakers to incorporate hydration awareness and care with greater precision in local and national policies.

Proceedings of the inaugural International Summit for Medical Nutrition Education and Research

Medical Nutrition Education (MNE) has been identified as an area with potential public health impact. Despite countries having distinctive education systems, barriers and facilitators to effective MNE are consistent across borders, demanding a common platform to initiate global programmes. A shared approach to supporting greater MNE is ideal to support countries to work together. In an effort to initiate this process, the Need for Nutrition Education/Innovation Programme group, in association with their strategic partners, hosted the inaugural International Summit on Medical Nutrition Education and Research on August 8, 2015 in Cambridge, UK. Speakers from the UK, the USA, Canada, Australia, New Zealand, Italy, and India provided insights into their respective countries including their education systems, inherent challenges, and potential solutions across two main themes: (1) Medical Nutrition Education, focused on best practice examples in competencies and assessment; and (2) Medical Nutrition Research, discussing how to translate nutrition research into education opportunities. The Summit identified shared needs across regions, showcased examples of transferrable strategies and identified opportunities for collaboration in nutrition education for healthcare (including medical) professionals. These proceedings highlight the key messages presented at the Summit and showcase opportunities for working together towards a common goal of improvement in MNE to improve public health at large.

Cocaine-induced transmural myocardial infarction in a Yorkshire swine with normal coronary arteries: Evidence for microvascular and/or epicardial coronary artery spasm

Cocaine-induced myocardial infarction with normal coronary arteries is well documented in humans. The exact mechanism of action remains speculative. We report one case of cocaine-induced myocardial infarction with normal coronaries in one swine. Systemic hemodynamics and angiographic, electrocardiographic, echocardiographic, and histopathologic data are presented. Intravenous cocaine (1, 3, 10 mg/kg) produced significant decreases in mean arterial pressure, heart rate, stroke volume, coronary blood flow, and coronary reserve, whereas pulmonary artery diastolic pressure and coronary vascular resistances increased. Left anterior descending and left circumflex coronary artery cross-sectional area decreased by 31% and 64%, respectively, without localized vasospasm. Electrocardiographic changes occurred (3 mm ST elevation in leads II, III, AVF). Peak creatine phosphokinase was 17,220 IU/L. The echocardiogram revealed severe hypokinesis of the inferior wall and normal ventricular function. The animal survived the acute phase of the infarction and the swine was restudied 12 weeks later. Upon rechallenge, systemic and coronary hemodynamics shoved changes similar to those in the previous study. The swine developed ventricular fibrillation and expired after the 10 mg/kg cocaine dose. Macroscopic examination of the external surface of the heart revealed marked diffuse fibrosis in the posteroinferior and lateral left ventricular wall. Our data suggest that the infarct induced by cocaine may have resulted from severe vasoconstriction or spasm at the level of the microcirculation, and/or the epicardial coronary arteries, which shoved slight but significant narrowing throughout their lengths.

Frequency stabilization of an external-cavity diode laser to metastable argon atoms in a discharge

A laser stabilization scheme using magnetic dichroism in a RF plasma discharge is presented. This method has been used to provide a frequency stable external-cavity diode laser that is locked to the 4s[3/2](2) → 4p[5/2](3) argon laser cooling transition at 811.53 nm. Using saturated absorption spectroscopy, we lock the laser to a Doppler free peak which gave a locking range of 20 MHz when the slope of the error signal was maximized. The stability of the laser was characterized by determining the square root Allan variance of laser frequency fluctuations when the laser was locked. A stability of 129 kHz was measured at 1 s averaging time for data acquired over 6000 s.

Pediatric tuberculosis immigration screening in high-immigration, low-incidence countries

BACKGROUND

Tuberculosis (TB) screening in migrant children, including immigrants, refugees and asylum seekers, is an ongoing challenge in low TB incidence countries. Many children from high TB incidence countries harbor latent TB infection (LTBI), and some have active TB disease at the point of immigration into host nations. Young children who harbor LTBI have a high risk of progression to TB disease and are at a higher risk than adults of developing disseminated severe forms of TB with significant morbidity and mortality. Many countries have developed immigration TB screening programs to suit the needs of adults, but have not focused much attention on migrant children.

OBJECTIVE

To compare the TB immigration medical examination requirements in children in selected countries with high immigration and low TB incidence rates.

DESIGN

Descriptive study of TB immigration screening programs for systematically selected countries.

RESULTS

Of 18 eligible countries, 16 responded to the written survey and telephone interview.

CONCLUSION

No two countries had the same approach to TB screening among migrant children. The optimal evidenced-based manner in which to screen migrant children requires further research.

Patient out-of-pocket and insurer payment decisions for bevacizumab for metastatic colorectal cancer: A Canadian analysis

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Background: Like many health care services in Canada, intravenous (IV) cancer therapies are typically funded publicly through hospitals and provincial cancer agencies. Delays may be encountered between regulatory approval and public funding of new drugs. IV drugs are not routinely covered through private insurance (PRI) plans, requiring patients to appeal for special consideration, including employer exceptions or pay cash. Uncertainty of drug funding may create challenges for physicians and patients when discussing treatment options. The Roche Patient Assistance Program (RPAP) provides reimbursement navigation, copay/financial assistance and access to infusion clinics. This observational study examines patient access to bevacizumab (B) in the absence of public funding. Methods: An analysis of the RPAP database for the period of July 2006 to August 2008 was conducted assessing patients enrolled, insurance status, approval rates, and access to B. Receipt of treatment with B was evaluated according to insurance coverage. Results: A total of 877 patients accessed the RPAP for treatment with B. 647 (74%) had PRI and 230 (26%) were uninsured. Of PRI patients, 310 (48%) were approved coverage and 337 (52%) were denied. 204 patients (65%) with approved PRI coverage received B therapy. Of patients with PRI but denied coverage for B, 135 (40%) elected to pay for B. Of patients with no PRI, 120 (52%) paid for B. Of all patients with no coverage for B (no PRI or denied PRI), 255 patients (45%) elected to pay for B. Conclusions: In a public healthcare environment, when B was not publicly funded, approximately half of patients without any PRI coverage who accessed the RPAP were willing to pay for B. Although private insurers state IV drugs are not plan benefits, almost half of patients were able to obtain B coverage. A conventional analysis of willingness-to-pay should be conducted to better understand reasons behind patient and private insurer decisions observed in this study. Further research should also be conducted to determine whether results can be generalized to other unfunded anticancer agents within the Canadian health care system.

[Table: see text]

Cost-effectiveness of capecitabine in combination with oxaliplatin (XELOX) compared with FOLFOX for the treatment of metastatic colorectal cancer: A Canadian evaluation

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Background: Capecitabine is an oral fluoropyrimidine used to treat patients with metastatic colorectal cancer (mCRC). Recent trials in 1st- and 2nd-line treatment have shown that capecitabine in combination with oxaliplatin (XELOX) is non-inferior to FOLFOX4 in terms of progression-free survival, overall survival and response rates. XELOX offers patients the advantage of treatment every 3 weeks rather than every 2 weeks without the need for lengthy infusions. This analysis evaluated the cost- effectiveness of replacing FOLFOX4 with XELOX for 1st- and 2nd-line treatment of mCRC from both Canadian healthcare system payor and societal perspectives. Methods: Based on evidence of non-inferiority of XELOX vs. FOLFOX4, cost-minimization analyses (CMA) were conducted using phase III clinical trial data. The CMA compared total cost associated with chemotherapy medications, administration of chemotherapy, and treatment related toxicities. For the societal perspective, patients’ costs and time were also included. The costs (or savings) were compared for 1st-line XELOX vs. FOLFOX4 and 2nd-line XELOX vs. FOLFOX4. Due to variation in Canadian clinical practice, sensitivity analyses using the FOLFOX6 regimen as a comparator were performed. Results: Cost savings per patient for XELOX vs. FOLFOX4 from a healthcare system payor perspective and a societal perspective are shown in the Table . XELOX was also associated with cost savings when compared with the simplified administration regimen of FOLFOX6. Reduced costs for chemotherapy administration and costs for patients’ time and travel primarily related to fewer clinic visits offset the increased drug acquisition cost of the XELOX regimen. Conclusions: Replacing FOLFOX with XELOX is associated with cost savings from the healthcare system payor and societal perspectives while preserving clinical efficacy.

[Table: see text]

[Table: see text]

Characterization of active site structure in CYP121. A cytochrome P450 essential for viability of Mycobacterium tuberculosis H37Rv

Mycobacterium tuberculosis (Mtb) cytochrome P450 gene CYP121 is shown to be essential for viability of the bacterium in vitro by gene knock-out with complementation. Production of CYP121 protein in Mtb cells is demonstrated. Minimum inhibitory concentration values for azole drugs against Mtb H37Rv were determined, the rank order of which correlated well with Kd values for their binding to CYP121. Solution-state spectroscopic, kinetic, and thermodynamic studies and crystal structure determination for a series of CYP121 active site mutants provide further insights into structure and biophysical features of the enzyme. Pro346 was shown to control heme cofactor conformation, whereas Arg386 is a critical determinant of heme potential, with an unprecedented 280-mV increase in heme iron redox potential in a R386L mutant. A homologous Mtb redox partner system was reconstituted and transported electrons faster to CYP121 R386L than to wild type CYP121. Heme potential was not perturbed in a F338H mutant, suggesting that a proposed P450 superfamily-wide role for the phylogenetically conserved phenylalanine in heme thermodynamic regulation is unlikely. Collectively, data point to an important cellular role for CYP121 and highlight its potential as a novel Mtb drug target.

Controlling the color space response of colorimetric luminescent oxygen sensors

The color space response of colorimetric luminescent oxygen sensors is described in terms of the Commission Internationale de l'Eclairage (CIE) x,y color coordinates. We show how the color change response to oxygen can be obtained, provided the quenching kinetics for all lumophores involved can be represented mathematically. The theory is illustrated by analysis of examples of theoretical sensors in which lumophores are quenched by Stern-Volmer kinetics to give red to green, green to red, and red to green to blue color responses as the partial pressure of oxygen is increased. The effects of lumophore emission lifetime and the permeability of the polymer matrix to oxygen are discussed in terms of the control of sensor response, which variations in these parameters offer.

Computation within cultured neural networks

In this paper we present three related areas of research we are pursuing to study neural computation in vitro. Rat cortical neurons cultured on 60 channel multielectrode array (MEA) allow the researcher to measure from and stimulate sixty different sites across a small population of neurons grown in vitro. Using this system we can send stimulation patterns into the network and study how these living neural networks compute by measuring its outputs. Our first series of studies uses chaotic control techniques to study the dynamics and potentially control the behavior of cortical network. At the same time, we are beginning to apply a model of computation called the liquid state machine or LSM model developed by Wolfgang Maass to provide a firm mathematical framework from which to proceed with our investigations. Each of these components is integrated into a third area investigating the role of computation and feedback using a real-time sensory-motor feedback robotic flight system.

Tunable Tsallis distributions in dissipative optical lattices

We demonstrated experimentally that the momentum distribution of cold atoms in dissipative optical lattices is a Tsallis distribution. The parameters of the distribution can be continuously varied by changing the parameters of the optical potential. In particular, by changing the depth of the optical lattice, it is possible to change the momentum distribution from Gaussian, at deep potentials, to a power-law tail distribution at shallow optical potentials.

Filtration, haze and foam characteristics of fermented wort mediated by yeast strain

AIMS

To investigate the influence of the choice of yeast strain on the haze, shelf life, filterability and foam quality characteristics of fermented products.

METHODS AND RESULTS

Twelve strains were used to ferment a chemically defined wort and hopped ale or stout wort. Fermented products were assessed for foam using the Rudin apparatus, and filterability and haze characteristics using the European Brewing Convention methods, to reveal differences in these parameters as a consequence of the choice of yeast strain and growth medium.

CONCLUSIONS

Under the conditions used, the choice of strain of Saccharomyces cerevisiae effecting the primary fermentation has an impact on all of the parameters investigated, most notably when the fermentation medium is devoid of macromolecular material.

SIGNIFICANCE AND IMPACT OF THE STUDY

The filtration of fermented products has a large cost implication for many brewers and wine makers, and the haze of the resulting filtrate is a key quality criterion. Also of importance to the quality of beer and some wines is the foaming and head retention of these beverages. The foam characteristics, filterability and potential for haze formation in a fermented product have long been known to be dependant on the raw materials used, as well as other production parameters. The choice of Saccharomyces cerevisiae strain used to ferment has itself been shown here to influence these parameters.

Resonant activation in a nonadiabatically driven optical lattice

We demonstrate the phenomenon of resonant activation in a nonadiabatically driven dissipative optical lattice with broken time symmetry. The resonant activation results in a resonance as a function of the driving frequency in the current of atoms through the periodic potential. We demonstrate that the resonance is produced by the interplay between deterministic driving and fluctuations, and we also show that by changing the frequency of the driving it is possible to control the direction of the diffusion.

Invasive bladder carcinoma: a pilot study of conservative treatment with accelerated radiotherapy and concomitant cisplatin

From November 1992 to December 1997, 25 patients (inoperable or refusing cystectomy) were included in a prospective study to assess the feasibility, tolerance, and curative potential of accelerated radiotherapy (RT) and concomitant cisplatin. Median age was 74 years (range 49-86). Stage distribution was as follows: 1 T1, 10 T2, 8 T3, and 6 T4. Two patients had clinically positive pelvic nodes. The goal was to deliver a total dose of 40 Gy to the whole pelvis and bladder in 4 weeks using a concomitant boost of 20 Gy to the tumor or to the whole bladder during the third and fourth weeks (total dose 60 Gy), with daily cisplatin (6 mg/m(2)) before RT for patients with creatinine clearance > 50 ml/min. All but one patient completed the RT protocol. Daily cisplatin was successfully delivered in 18 patients. One patient presented with grade III ototoxicity. Diarrhea was scored grade III in two and grade IV in two patients. Acute urinary toxicity was scored grade III in one patient. Posttreatment late effects included bladder grade II and grade III in two patients and one patient, respectively; large bowel grade III in one; urethral grade III in one; and femoral head radionecrosis in one. Four-year overall and disease-specific survival rates were 23% and 35%, respectively. The latter was 60% for patients with T2 tumors. The 4-year actuarial locoregional control rate for all patients was 61%. In summary, accelerated RT and concomitant cisplatin is feasible with acceptable tolerance even in relatively old patients. Although outcome was better for patients with low-stage tumors, local control and survival rates appeared similar to those of standard RT schedules for a similar patient population.

Prevention of orthopaedic wound infections: a quality improvement project

Using clinical practice improvement methodology, a project was undertaken to reduce the incidence of surgical wound infections following elective hip and knee replacement surgery. A team was established, key measures for improvement were identified, strategies for change were developed and an action plan was implemented. Outcomes for this project included a reduction in the rate of clean surgical wound infection for joint replacement surgery from 28% to zero. Average length of stay for total hip replacement surgery was reduced from 13.9 to 9.3 days and from 14.6 to 10.4 days for total knee replacement surgery. Guidelines for patient selection were developed along with a protocol for the management of preparation to prevent urinary tract infections. Post-discharge surveillance and a preoperative rehabilitation and exercise programme have been implemented. There is potential for wider uptake and implementation of the quality principles described herein.

Transesophageal echocardiographic evaluation of native aortic valve area: utility of the double-envelope technique

OBJECTIVE

To assess the accuracy of aortic valve area (AVA) calculations using the continuity equation with data obtained from the double envelope (DE) (simultaneously obtained left ventricular outflow tract [V1]) and aortic valve [V2] velocities) during intraoperative transesophageal echocardiography (TEE).

DESIGN

Prospective study; measurements were performed on-line.

SETTING

University hospital.

PARTICIPANTS

Cardiac and noncardiac surgical patients (n = 75) with recent aortic valve assessment (<3 months) undergoing general anesthesia or endotracheal intubation.

INTERVENTIONS

Intraoperative AVA was measured by the continuity equation using the DE technique (DE/TEE) and by planimetry (PL/TEE). Left ventricular outflow tract diameter was obtained from midesophageal views, whereas subvalvular (V1) and valvular (V2) velocities were obtained simultaneously using continuous-wave Doppler from transgastric views. V1 was also obtained using pulsed-wave Doppler. Measurements were compared with AVA obtained preoperatively by the Gorlin equation during cardiac catheterization (G/CATH) or by transthoracic echocardiography using the traditional continuity equation (C/TTE) (nonsimultaneously obtained V1 and V2).

MEASUREMENTS AND MAIN RESULTS

A DE was obtained in 73 of 75 patients (97%). Four patients had atrial fibrillation at the time of the examination, whereas the rest were in sinus rhythm. PL/TEE was performed in 54 of 71 patients with sinus rhythm (76%). Agreement was good between DE/TEE and G/CATH (mean bias, 0.02 cm(2) [SD, 0.24 cm(2)]), and C/TTE (mean bias, -0.05 cm(2) [SD, 0.16 cm(2)]). Agreement was not as good between PL/TEE and G/CATH (mean bias, -0.07 cm(2) [SD, 0.28 cm(2)]) and C/TTE (mean bias, -0.13 cm(2) [SD, 0.30 cm(2)]). V1 obtained by pulsed-wave Doppler and with DE closely agreed (mean bias, 0.01 m/sec [SD, 0.05 m/sec]).

CONCLUSION

TEE evaluation of native AVA using the DE technique is feasible and in good agreement with that obtained by C/TTE and G/CATH. Compared with DE/TEE, PL/TEE did not agree as well. Use of DE/TEE should simplify the continuity equation and may minimize errors resulting from beat-to-beat variability in stroke volume.