International evaluation of an artificial intelligence-powered electrocardiogram model detecting acute coronary occlusion myocardial infarction

Aims

A majority of acute coronary syndromes (ACS) present without typical ST elevation. One-third of non-ST-elevation myocardial infarction (NSTEMI) patients have an acutely occluded culprit coronary artery [occlusion myocardial infarction (OMI)], leading to poor outcomes due to delayed identification and invasive management. In this study, we sought to develop a versatile artificial intelligence (AI) model detecting acute OMI on single-standard 12-lead electrocardiograms (ECGs) and compare its performance with existing state-of-the-art diagnostic criteria.

Methods and results

An AI model was developed using 18 616 ECGs from 10 543 patients with suspected ACS from an international database with clinically validated outcomes. The model was evaluated in an international cohort and compared with STEMI criteria and ECG experts in detecting OMI. The primary outcome of OMI was an acutely occluded or flow-limiting culprit artery requiring emergent revascularization. In the overall test set of 3254 ECGs from 2222 patients (age 62 ± 14 years, 67% males, 21.6% OMI), the AI model achieved an area under the curve of 0.938 [95% confidence interval (CI): 0.924-0.951] in identifying the primary OMI outcome, with superior performance [accuracy 90.9% (95% CI: 89.7-92.0), sensitivity 80.6% (95% CI: 76.8-84.0), and specificity 93.7 (95% CI: 92.6-94.8)] compared with STEMI criteria [accuracy 83.6% (95% CI: 82.1-85.1), sensitivity 32.5% (95% CI: 28.4-36.6), and specificity 97.7% (95% CI: 97.0-98.3)] and with similar performance compared with ECG experts [accuracy 90.8% (95% CI: 89.5-91.9), sensitivity 73.0% (95% CI: 68.7-77.0), and specificity 95.7% (95% CI: 94.7-96.6)].

Conclusion

The present novel ECG AI model demonstrates superior accuracy to detect acute OMI when compared with STEMI criteria. This suggests its potential to improve ACS triage, ensuring appropriate and timely referral for immediate revascularization.

Growth Hormone, Atherosclerosis and Peripheral Arterial Disease: Exploring the Spectrum from Acromegaly to Growth Hormone Deficiency

Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are increasingly recognised for their role in cardiovascular (CV) physiology. The GH-IGF-1 axis plays an essential role in the development of the CV system as well as in the complex molecular network that regulates cardiac and endothelial structure and function. A considerable correlation between GH levels and CV mortality exists even among individuals in the general population without a notable deviation in the GHIGF- 1 axis functioning. In addition, over the last decades, evidence has demonstrated that pathologic conditions involving the GH-IGF-1 axis, as seen in GH excess to GH deficiency, are associated with an increased risk for CV morbidity and mortality. A significant part of that risk can be attributed to several accompanying comorbidities. In both conditions, disease control is associated with a consistent improvement of CV risk factors, reduction of CV mortality, and achievement of standardised mortality ratio similar to that of the general population. Data on the prevalence of peripheral arterial disease in patients with acromegaly or growth hormone deficiency and the effects of GH and IGF-1 levels on the disease progression is limited. In this review, we will consider the pivotal role of the GH-IGF-1 axis on CV system function, as well as the far-reaching consequences that arise when disorders within this axis occur, particularly in relation to the atherosclerosis process.

Validation of an automated artificial intelligence system for 12‑lead ECG interpretation

BACKGROUND

The electrocardiogram (ECG) is one of the most accessible and comprehensive diagnostic tools used to assess cardiac patients at the first point of contact. Despite advances in computerized interpretation of the electrocardiogram (CIE), its accuracy remains inferior to physicians. This study evaluated the diagnostic performance of an artificial intelligence (AI)-powered ECG system and compared its performance to current state-of-the-art CIE.

METHODS

An AI-powered system consisting of 6 deep neural networks (DNN) was trained on standard 12‑lead ECGs to detect 20 essential diagnostic patterns (grouped into 6 categories: rhythm, acute coronary syndrome (ACS), conduction abnormalities, ectopy, chamber enlargement and axis). An independent test set of ECGs with diagnostic consensus of two expert cardiologists was used as a reference standard. AI system performance was compared to current state-of-the-art CIE. The key metrics used to compare performances were sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and F1 score.

RESULTS

A total of 932,711 standard 12‑lead ECGs from 173,949 patients were used for AI system development. The independent test set pooled 11,932 annotated ECG labels. In all 6 diagnostic categories, the DNNs achieved high F1 scores: Rhythm 0.957, ACS 0.925, Conduction abnormalities 0.893, Ectopy 0.966, Chamber enlargement 0.972, and Axis 0.897. The diagnostic performance of DNNs surpassed state-of-the-art CIE for the 13 out of 20 essential diagnostic patterns and was non-inferior for the remaining individual diagnoses.

CONCLUSIONS

Our results demonstrate the AI-powered ECG model's ability to accurately identify electrocardiographic abnormalities from the 12‑lead ECG, highlighting its potential as a clinical tool for healthcare professionals.

Association of Mild-to-Moderate Aortic Regurgitation With Outcomes in Heart Failure With Preserved Ejection Fraction

OBJECTIVE

To assess aortic regurgitation (AR) prevalence, its hemodynamic effect, and long-term prognostic implications in patients admitted with de novo or worsened heart failure with preserved ejection fraction (HFpEF).

METHODS

Consecutive patients hospitalized with de novo or worsened HFpEF between 2014 and 2020 were enrolled. Patients with more than moderate aortic and/or mitral valve disease were excluded. Based on the presence and degree of AR, patients were divided into those without AR, those with mild, and those with moderate AR. Data on cardiovascular death, heart failure (HF) rehospitalization, and their composite (major adverse cardiovascular events) were collected.

RESULTS

The final study population consisted of 458 HFpEF patients: 156 (34.1%) with mild-AR, 153 (33.4%) with moderate-AR, and the remaining 149 (32.5%) with no AR. Mild-to-moderate AR patients were older, with larger left atrium-left ventricle (LV) volumes, greater LV mass index, higher filling pressure, and prevalence of diastolic dysfunction compared with the no-AR group (all P<.05). During 5-year follow-up, 113 patients died of cardiovascular causes, 124 patients were rehospitalized for HF, whereas 196 experienced the composite endpoint. Mild-to-moderate AR was identified as an independent predictor of all-cause death (HR, 1.62; 95% CI, 1.14 to 1.58; P=.04) and major adverse cardiovascular event occurrence (HR, 1.48; 95% CI, 1.05 to 2.09; P=.02). A total of 126 (35.5%) of 355 patients showed progression of AR at follow-up echocardiography.

CONCLUSION

Mild-to-moderate AR is common among patients hospitalized for HFpEF. It is associated with adverse LV remodeling and worse long-term outcomes. These findings warrant further prospective studies addressing the importance of AR in prognostic stratification and exploring therapeutic strategies to mitigate its hemodynamic effect on HF.

Predictors of long-term atrial fibrillation recurrence after catheter ablation: non-linear analytical approach for individualized prognostic stratification

Background

Recurrences are common in patients with atrial fibrillation (AF) during long-term follow-up after catheter ablation (CA) for pulmonary vein isolation (PVI). Recently, machine learning (ML) models identifying non-linear relationships among various patient parameters have been applied for prognostic stratification in different cardiac diseases.

Aim

This is a retrospective study aimed to determine whether ML-based models can identify non-linear relationships in individual clinical baseline characteristics and CT-quantified volumetric parameters of epicardial fat tissue (EFT) to aid in prognosing outcome of catheter ablation for PVI in patients with paroxysmal AF.

Methods

A cohort of 92 patients (median age 60.2 [51.9–64.0]; 74% male) with paroxysmal AF (a single persistent AF episode was accepted) undergoing catheter ablation targeting PVI was analysed. All patients underwent cardiac CT imaging and were fitted with implantable loop recorder (ILR) prior to CA. For PVI, radiofrequency CA with electro-anatomical mapping was used in 79 patients, cryoballoon ablation in 13 patients. AF recurrence, defined as AF burden &gt;0.1% after the blanking period (90 days), was continuously assessed by ILR. Feature selection on 23 baseline parameters was performed using random forest models (XGBoostRegressor). Mean absolute Shapley values (|mSHAP| – Shapley Additive expLanations) were used to quantify the relative discriminative power of analysed parameters.

Results

During a follow-up of 3-years, AF recurrence was detected in 58 (63%) patients, 29 (50%) of them underwent a repeat ablation. Five most important predictors of AF recurrence during 3-year follow-up were upper epicardial fat volume, BMI, baseline AF burden, age and pericardial volume (lower segment) (Fig. 1). Upper EFT volume was twice as important for males than females (0.44 and 0.21 |mSHAP| respectively). For a patient with no AF recurrence, low age (41 years) and low upper EFT volume (13.2 ml) were the most important drivers predicting positive ablation outcome (Fig. 2A). In contrast, in a patient with AF recurrence post CA, an above-average EFT volume of 55.5 ml and a high BMI had the most significant net contribution for predicting his failed CA outcome (Fig. 2B).

Conclusion

Non-linear ML analysis applied to our limited cohort of patients with paroxysmal AF undergoing CA suggests: i) a significant association of high EFT volume with ILR determined AF recurrence during a 3-year follow-up; ii) potential role of such analyses for a more granular and highly individualized prediction of outcome of planned CA. However, these results need further testing, and validation in prospective trials.

Funding Acknowledgement

Type of funding sources: None.

High epicardial fat volume is associated with atrial fibrillation recurrences after catheter ablation

Background

Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation therapy for atrial fibrillation (AF). However, even with important technological improvements, AF recurrences are common in long-term follow-up. Recently, epicardial fat tissue (EFT) has been proposed as a potential AF modulator promoting and sustaining atrial arrhythmogenic milieu.

Aim

In this retrospective single-centre study, we sought to evaluate the association between CT-quantified EFT volume and long-term primary PVI outcome assed by means of continuous ECG monitoring with implantable loop recorders (ILR) in paroxysmal AF patients.

Methods

A cohort of 92 patients (median age 60.2 [IQR 51.9–64.0]; 74% male) with paroxysmal AF (a single persistent AF episode was accepted) undergoing catheter ablation targeted at PVI was analysed. Prior to CA all patients underwent cardiac CT imaging with subsequent implantation of implantable loop recorder (ILR). Radiofrequency CA ablation with electro-anatomical mapping for PVI was used in 79 patients, balloon cryoablation was used in 13 patients. Verified complete PVI was defined as procedural endpoint. EFT volume was semi-automatically segmented and quantified on contrast enhanced CT studies. AF recurrence, defined as AF burden &gt;0.1% after the blanking period (90 days), was continuously assessed by ILR. Kaplan-Meier analysis of AF recurrence-free survival at 1-year, 2-year and 3-year follow-up periods compared patients stratified into EFT volume tertiles.

Results

During a median follow-up of 52.6 months [IQR 43–64], AF recurrence was detected in 58 (63%) patients, 29 (50%) of them underwent a repeat ablation. Patients in high, mid, and low total EFT volume tertiles had a median time to late AF recurrence of 154, 373, and 284 days (Fig. 1A). At a 1-year follow-up, patients in the high EFT volume tertile had the worst AF ablation outcome (p=0.023). However, this difference gradually faded-out and became non-significant at 2 and 3 years. ROC analysis revealed an EFT of 95 ml as an optimal cut-off (p=0.002) for expected arrhythmia recurrence post acutely successful PVI (Fig. 1B).

Conclusion

EFT volume quantification in a relatively homogenous, continuously monitored cohort of patients undergoing catheter ablation for paroxysmal AF revealed a significant association between AF recurrence at 1 year post ablation and volume of epicardial fat. These results suggest a possible role of epicardial adipose tissue as an adverse pro-fibrillatory factor. Identified EFT volume cut-offs have to be validated prospectively on a larger and balanced patient population.

Funding Acknowledgement

Type of funding sources: None.

Utilizing longitudinal data in assessing all-cause mortality in patients hospitalized with heart failure

AIMS

Risk stratification in patients with a new onset or worsened heart failure (HF) is essential for clinical decision making. We have utilized a novel approach to enrich patient level prognostication using longitudinally gathered data to develop ML-based algorithms predicting all-cause 30, 90, 180, 360, and 720 day mortality.

METHODS AND RESULTS

In a cohort of 2449 HF patients hospitalized between 1 January 2011 and 31 December 2017, we utilized 422 parameters derived from 151 451 patient exams. They included clinical phenotyping, ECG, laboratory, echocardiography, catheterization data or percutaneous and surgical interventions reflecting the standard of care as captured in individual electronic records. The development of predictive models consisted of 101 iterations of repeated random subsampling splits into balanced training and validation sets. ML models yielded area under the receiver operating characteristic curve (AUC-ROC) performance ranging from 0.83 to 0.89 on the outcome-balanced validation set in predicting all-cause mortality at aforementioned time-limits. The 1 year mortality prediction model recorded an AUC of 0.85. We observed stable model performance across all HF phenotypes: HFpEF 0.83 AUC, HFmrEF 0.85 AUC, and HFrEF 0.86 AUC, respectively. Model performance improved when utilizing data from more hospital contacts compared with only data collected at baseline.

CONCLUSIONS

Our findings present a novel, patient-level, comprehensive ML-based algorithm for predicting all-cause mortality in new or worsened heart failure. Its robust performance across phenotypes throughout the longitudinal patient follow-up suggests its potential in point-of-care clinical risk stratification.

Amazonian terrestrial water balance inferred from satellite-observed water vapor isotopes

Atmospheric humidity and soil moisture in the Amazon forest are tightly coupled to the region’s water balance, or the difference between two moisture fluxes, evapotranspiration minus precipitation (ET-P). However, large and poorly characterized uncertainties in both fluxes, and in their difference, make it challenging to evaluate spatiotemporal variations of water balance and its dependence on ET or P. Here, we show that satellite observations of the HDO/H₂O ratio of water vapor are sensitive to spatiotemporal variations of ET-P over the Amazon. When calibrated by basin-scale and mass-balance estimates of ET-P derived from terrestrial water storage and river discharge measurements, the isotopic data demonstrate that rainfall controls wet Amazon water balance variability, but ET becomes important in regulating water balance and its variability in the dry Amazon. Changes in the drivers of ET, such as above ground biomass, could therefore have a larger impact on soil moisture and humidity in the dry (southern and eastern) Amazon relative to the wet Amazon.

The evolution of the Amazon forest is tightly coupled to its terrestrial water balance. Here, the authors show that forest biomass changes in the Amazon are a driver of the spatiotemporal variation of evapotranspiration, and such changes could have a larger impact on water availability in the dry regions (southern, eastern) of the Amazon.

Deep learning for mortality prediction in patients with a de-novo or worsened heart failure

Background

Heart failure (HF) is a heterogenous syndrome with complex pathophysiology. Biomarkers and clinical risk scores often fail to provide optimal patient-level precision in the prognostic stratification. As utilizing single observational timepoint, they do not capture the entire care pathway with variations in individual patient management. Electronic patient records provide an opportunity to develop new artificial intelligence (AI) strategies for comprehensive prognostic re-stratification reflecting diagnostic and therapeutic management.

Purpose

We sought to use deep artificial intelligence (AI) and develop an unbiased predictive algorithm for all-cause mortality in a cohort of patients hospitalized with a de novo or worsened HF.

Methods

In a cohort of 2449 HF patients hospitalized between 2011–2017, we utilized 151 451 patient exams from 422 parameters. They included clinical phenotyping, medication, ECG, laboratory, echocardiography, catheterization data or percutaneous and surgical interventions gathered on a routine clinical basis reflecting standard of care as captured in individual electronic records. The AI model development consisted of 101 iterations of repeated random subsampling splits into balanced training and validation sets.

Results

AI models yielded performance ranging from 0.83 to 0.89 AUC on the outcome-balanced validation set in predicting all-cause mortality at 30-, 90-, 180-, 360- and 720-day time-limits (Figure 1). The primary endpoint, 1-year mortality prediction model, recorded an 0.85 AUC accuracy. We observed stable model performance across all HF phenotypes: HFpEF 0.83 AUC, HFmrEF 0.85 AUC and HFrEF 0.86 AUC, respectively).

Conclusion

Our findings present a novel, patient-level, AI-based risk prediction of all-cause mortality in heart failure with a robust accuracy across its phenotypes. This suggests the potential of AI based predictive models in a point-of-care approach to guide clinical risk stratification.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): VZW Cardiovascular Research Center Aalst

Substrate Supporting Disc Method for Confirmed Detection of Total Coliforms and E. coli in all Foods: Collaborative Study

The Coli Complete® substrate supporting disc (SSD) method for simultaneous confirmed total coliform count and Escherichia coli determination in all foods was compared with AOAC most probable number (MPN) methods, 966.23 and 966.24. Twenty-nine laboratories participated in this collaborative study in which 6 food types were analyzed. Four food types, raw ground beef, pork sausage, raw liquid milk, and nut meats, were naturally contaminated with coliform bacteria. Two foods, dry egg and fresh frozen vegetables, were seeded with coliforms. Three food types, ground beef, raw liquid milk, and pork sausage, were naturally contaminated with E. coli. Although pork sausage was naturally contaminated, the level was very low (&lt;10/50 g); therefore, additional E. coli were inoculated into 1 lot of this food type. Three food types, nut meats, dry egg, and fresh frozen vegetables, were inoculated with E. coli. For naturally contaminated samples, duplicate determinations were made on 3 separate lots for each food type. For inoculated samples, low, medium, and high contamination levels plus uninoculated control samples were examined in duplicate. Data were analyzed separately for total coliform bacteria and for E. coli. Mean log MPN counts were determined by the SSD method and the appropriate AOAC MPN method. Results were then analyzed for repeatability, reproducibility, and mean log MPN statistical equivalence. Results were statistically equivalent for all total coliform levels in all food types except frozen vegetable and raw nut meat uninoculated control samples and 1 lot of pork sausage where the SSD method produced statistically significant greater numbers. For the E. coli determinations, results were statistically equivalent across all samples and all levels for each food type. The SSD method has been adopted first action by AOAC International for confirmed detection of total coliforms and E. coli in all foods.

Uric acid is associated with long-term adverse cardiovascular outcomes in patients with acute coronary syndrome undergoing percutaneous coronary intervention

BACKGROUND AND AIMS

Evidence links uric acid (UA) with the promotion of cardiovascular disease. We assessed the prognostic value of UA on long-term major adverse outcomes (MACE) in patients with acute coronary syndrome (ACS), undergoing percutaneous coronary intervention (PCI).

METHODS

As primary endpoint, we assessed the association of UA (continuous and dichotomized) with MACE, including cardiovascular death, myocardial infarction (MI) and stroke, using Cox regression and propensity matching. As secondary endpoints, the influence of hyperuricemia (defined as UA levels > 6.0 mg/dl in women, and >7.0 mg/dl in men) was analysed separately for cardiovascular death, MI, and stroke. The incremental prognostic value of UA was tested using the net reclassification improvement (NRI), and the integrated discrimination improvement (IDI).

RESULTS

We included 1215 patients. Hyperuricemia was present in 356 (29.3%) patients. Mean follow-up was 5.5 years. UA (HR 1.091 [1.035-1.150]; p = 0.001) and hyperuricemia (HR 1.750 [1.388-2.207]; p < 0.001) were significantly associated with MACE. Results were consistent between Cox regression and propensity matched analysis. Patients with hyperuricemia had a 1.6-fold increased relative risk for cardiovascular death (p = 0.005) and a 1.5-fold increased risk for MI (p = 0.032). For stroke, hyperuricemia only constituted a confounder (HR 1.104; p = 0.970). The prognostic accuracy of an established risk prediction model was significantly increased by adding UA (continuous NRI p = 0.004; categorical NRI p = 0.029; IDI p = 0.002).

CONCLUSIONS

Our data suggest an independent association of elevated UA with long-term MACE in ACS patients undergoing PCI. Whether lowering UA might be beneficial remains to be elucidated in large clinical trials.

Spelling in oral deaf and hearing dyslexic children: A comparison of phonologically plausible errors

A written single word spelling to dictation test and a single word reading test were given to 68 severe-profoundly oral deaf 10-11-year-old children and 20 hearing children with a diagnosis of dyslexia. The literacy scores of the deaf children and the hearing children with dyslexia were lower than expected for children of their age and did not differ from each other. Three quarters of the spelling errors of hearing children with dyslexia compared with just over half the errors of the oral deaf group were phonologically plausible. Expressive vocabulary and speech intelligibility predicted the percentage of phonologically plausible errors in the deaf group only. Implications of findings for the phonological decoding self-teaching model and for supporting literacy development are discussed.

Feasibility of scenario-based simulation training versus traditional workshops in continuing medical education: a randomized controlled trial

INTRODUCTION

Although simulation-based training is increasingly used for medical education, its benefits in continuing medical education (CME) are less established. This study seeks to evaluate the feasibility of incorporating simulation-based training into a CME conference and compare its effectiveness with the traditional workshop in improving knowledge and self-reported confidence.

METHODS

Participants (N=27) were group randomized to either a simulation-based workshop or a traditional case-based workshop.

RESULTS

Post-training, knowledge assessment score neither did increase significantly in the traditional group (d=0.13; p=0.76) nor did significantly decrease in the simulation group (d= - 0.44; p=0.19). Self-reported comfort in patient assessment parameters increased in both groups (p<0.05 in all). However, only the simulation group reported an increase in comfort in patient management (d=1.1, p=0.051 for the traditional group and d=1.3; p= 0.0003 for the simulation group). At 1 month, comfort measures in the traditional group increased consistently over time while these measures in the simulation group increased post-workshop but decreased by 1 month, suggesting that some of the effects of training with simulation may be short lived.

DISCUSSION

The use of simulation-based training was not associated with benefits in knowledge acquisition, knowledge retention, or comfort in patient assessment. It was associated with superior outcomes in comfort in patient management, but this benefit may be short-lived. Further studies are required to better define the conditions under which simulation-based training is beneficial.

RUPERT: a Device for Robotic Upper Extremity Repetitive Therapy

We report the development and initial evaluation of a device for robotic assisted upper extremity repetitive therapy (RUPERT). Intense repetitive physical therapies provided by individualized interaction between the patient and a rehabilitation specialist to overcome upper extremity impairment after stroke are beneficial, however, they are expensive and difficult to evaluate quantitatively and objectively. The need is urgent and growing for a low cost, safe and easy to use robotic device to assist the patient and the therapist to fully achieve the potential benefit of task-based repetitive physical therapies. We designed a pneumatic muscle (PM) driven therapeutic device, the RUPERT, that is wearable and provides assistive forces required to move the arm during performance of several critical tasks of daily living. The robot has four degrees of freedom at shoulder, elbow and wrist. The sensors feedback position and force information for quantitative evaluation of task performance. It has the potential of providing a take-home method of supplementing therapy. The device can also provide real-time, objective assessment of functional improvement of therapy.

A manner of characterizing the development of countries

An attempt is made to characterize the socio-economic state and the temporal evolution of countries by the use of labor force distribution data on a multidimensional phase plot so that the development of a country is represented by an evolutionary track of a phase point. The evolutionary tracks of several countries are examined, and the phase points of many countries are compared. Snowflake diagrams, which make easy comparison of the socio-economic character of various countries, have also been developed.

Initial diagnostic hypotheses bias analytic information processing in non-visual domains

CONTEXT

Previous studies have shown that an initial diagnostic hypothesis biases automatic information processing. It is unclear if an initial hypothesis has a similar effect on analytic information processing. Our first objective was to study the effect of an initial diagnostic hypothesis on analytic processing. Our second objective was to assess the effect of clinical experience on analytic processing by evaluating the effect of clinical frequency and urgency of an alternative diagnosis on diagnosis selection.

METHODS

During a 12-minute objective structured clinical examination station, 19 subspecialty medical residents diagnosed the cause of 3 clinical presentations: dyspnoea; headache, and chest pain. Subjects were randomly allocated cases for which the suggested initial hypothesis was either correct or incorrect. For cases with an incorrect initial hypothesis, the alternative diagnoses varied in the frequency with which they are encountered in clinical practice, and their clinical urgency, relative to the initial diagnostic hypothesis.

RESULTS

All correct initial hypotheses were retained, compared with 10.9% of incorrect hypotheses. All cases with a correct initial hypothesis were diagnosed correctly, compared with 65.2% of cases with an incorrect hypothesis (risk ratio 1.5 [95% confidence interval 1.2-1.9], P = 0.02). Clinical frequency and urgency were not associated with alternative diagnosis selection.

DISCUSSION

Our results suggest that an initial diagnostic hypothesis biases analytic processing. The data used to reject an initial hypothesis appear to drive selection of an alternative hypothesis. Further studies aimed at finding strategies for increasing the likelihood of generating a correct initial hypothesis or debiasing an initial hypothesis are needed.

Characterization and Inheritance of a New Source of Resistance to Fusarium oxysporum f. sp. melonis Race 1.2 in Cucumis melo

Four physiological races (0, 1, 2, and 1.2) of Fusarium oxysporum f. sp. melonis, causal agent of Fusarium wilt in melons, have been described. Whereas resistance against each of the races 0, 1, and 2 is encoded by a single dominant R-gene, resistance against the fourth race, FOM 1.2, is polygenically inherited and was recently characterized in the cultivar Isabelle. In the present study, we report on an independently derived source of resistance to race 1.2, the Israeli breeding line BIZ. The disease response of BIZ seedlings was compared with two susceptible genotypes, Line 33 and PI 414723, and the partially resistant genotype, Isabelle, at increasing concentrations of inoculum. BIZ exhibited near-complete resistance to race 1.2, even at inoculum levels of 10⁶ spores per ml and root wounding, indicating that such resistance is stronger than that in Isabelle. Although in previous studies the F₁ hybrids between BIZ and the sensitive lines displayed full resistance in the field, in the present study they were susceptible under artificial inoculation conditions that involve high inoculum concentrations of 10⁶ spores per ml and root wounding; under intermediate inoculum levels (10⁵ and 5 × 10⁵ spores per ml) they were partially resistant. Segregation of the resistance response in the F₂ and back-cross-1 progeny from a cross between BIZ and PI 414723 supported a model in which two complementary, recessive genes are required to obtain full resistance. While the fungus was shown to colonize root tissue of both resistant and susceptible lines, colonization was markedly lower in the resistant plants, and the fungus was nearly absent from upper stem segments.

Temporal trends in antihypertensive drug prescriptions in Canada before and after introduction of the Canadian Hypertension Education Program

OBJECTIVE

Poor control of hypertension is a world-wide health issue. In 1999, the Canadian Hypertension Education Program (CHEP) was launched to annually develop and implement evidence-based hypertension guidelines in an effort to improve hypertension control rates. This study was designed to examine temporal trends in antihypertensive drug prescribing and to explore whether drug prescriptions changed after initiation of the new CHEP guideline process.

DESIGN AND METHODS

We used longitudinal Canadian dispensing data (from the IMS CompuScript database; IMS Health, Pointe-Claire, Quebec) to examine antihypertensive prescriptions in the 3 years prior to and the 3 years following introduction of the new CHEP process. To control for temporal changes in the incidence of other cardiovascular conditions for which antihypertensive agents may be prescribed for their non-blood pressure-lowering effects (for example, angiotensin-converting enzyme (ACE) inhibitors for heart failure or coronary artery disease), prescription rates for digoxin, loop diuretics, and nitrates were also examined.

RESULTS

Prescriptions for all antihypertensive agents increased significantly between 1996 and 2001 [11% for thiazides, 45% for beta-blockers, 68% for ACE inhibitors, 19% for calcium channel blockers, and 4332% for angiotensin receptor blockers (ARBs)]. Loop diuretic prescriptions increased 27%, but prescriptions for digoxin (-19%) and nitrates (-8%) declined over this time frame. Time series analyses demonstrated increases in the prescription growth rate for all four antihypertensive drug classes recommended in CHEP for the period 1999-2001 compared with 1996-1998, which were statistically significantly and of substantial magnitude (absolute annual increase in prescription growth rate of 4.6% (95% confidence interval 3.5-5.9%) for thiazides, 3.0% (1.8-4.2%) for beta-blockers, 8.2% (6.7-9.7%) for ACE inhibitors, and 6.1% (4.4-7.8%) for calcium channel blockers). The growth rate in nitrate prescriptions did not significantly change [1.1% (-0.6 to +3.0%)] and, although the changes in growth rate for loop diuretics [4.7% (3.2-6.3%)] and digoxin [2.1% (0.6-3.5%)] were statistically significant, they were of smaller magnitude than the changes in the four recommended antihypertensive agents. Similar results were observed when analysis was restricted to new prescriptions only.

CONCLUSIONS

Prescriptions for all antihypertensive drugs increased substantially in Canada between 1996 and 2001; the rate of increase was significantly greater after 1999 for all four drugs recommended as first-line therapy in the annual CHEP guidelines. This preliminary data is encouraging, but a national survey of blood pressure control is needed to fully evaluate the impact of the new Canadian guideline process.

Evaluation of sporadic cases of odontogenic keratocysts in multicentric study

The aim of this retrospective study was to report frequency of sporadic odontogenic keratocysts (sOKC) according to the age and gender, as well as location (mandible, maxilla, soft tissues, and maxillary sinus). Four hundred and twenty nine sOKC confirmed pathohistologically in a period from 1965-1998 were included in this study. The average age of patients with sOKC was 43.11 (age range 10-91), in males 42.06 and in females 44.72 years. More frequently sOKC were found in males (60.61%) in comparison to the females (39.39%). Therefore, ratio between males and females was 1.5:1. Diagnosis of sOKC is usually established in patients aged 21-30 (18.88%), in males usually aged between 21-30 (23.46%), and in females aged between 11-20 (18.93%). sOKC are more frequent in males according to the age groups, except between age 61-70 where sOKC were more frequent in females. Most frequently, sOKC occurred in the mandible 70.16%, 12.35% of sOKC were found in the maxilla, 12.82% in soft tissues and 4.66% in the maxillary sinuses.

The 2.4-A crystal structure of the penicillin-resistant penicillin-binding protein PBP5fm from Enterococcus faecium in complex with benzylpenicillin

Penicillin-binding proteins (PBPs) are membrane proteins involved in the final stages of peptidoglycan synthesis and represent the targets of beta-lactam antibiotics. Enterococci are naturally resistant to these antibiotics because they produce a PBP, named PBP5fm in Enterococcus faecium, with low-level affinity for beta-lactams. We report here the crystal structure of the acyl-enzyme complex of PBP5fm with benzylpenicillin at a resolution of 2.4 A. A characteristic of the active site, which distinguishes PBP5fm from other PBPs of known structure, is the topology of the loop 451-465 defining the left edge of the cavity. The residue Arg464, involved in a salt bridge with the residue Asp481, confers a greater rigidity to the PBP5fm active site. In addition, the presence of the Val465 residue, which points into the active site, reducing its accessibility, could account for the low affinity of PBP5fm for beta-lactam. This loop is common to PBPs of low affinity, such as PBP2a from Staphylococcus aureus and PBP3 from Bacillus subtilis. Moreover, the insertion of a serine after residue 466 in the most resistant strains underlines even more the determining role of this loop in the recognition of the substrates.

The 2001 Canadian recommendations for the management of hypertension: Part two--Therapy

OBJECTIVE

To provide updated, evidence-based recommendations for the therapy of hypertension in adults.

OPTIONS

For patients with hypertension, a number of antihypertensive agents may control blood pressure. Randomized trials evaluating first-line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed.

OUTCOMES

The health outcomes that were considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence.

EVIDENCE

MEDLINE was searched for the period March 1999 to October 2001 to identify studies not included in the 2000 revision of the Canadian Recommendations for the Management of Hypertension. Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other published studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and mortality.

BENEFITS, HARMS AND COSTS

Various antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood-pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality.

RECOMMENDATIONS

The present document contains detailed recommendations pertaining to treatment thresholds, target blood pressures, and choice of agents in various settings in patients with hypertension. The main changes from the 2000 Recommendations are the addition of a section on the treatment of hypertension in patients with diabetes mellitus, the amalgamation of the previous sections on treatment of hypertension in the young and old into one section, increased emphasis on the role of combination therapies over repeated trials of single agents and expansion of the section on the treatment of hypertension after stroke. Implicit in the recommendations for therapy is the principle that treatment for an individual patient should take into consideration global cardiovascular risk, the presence and/or absence of target organ damage, and comorbidities.

VALIDATION

All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Individuals with potential conflicts of interest relative to any specific recommendation were excluded from voting on that recommendation. Only those recommendations achieving high levels of consensus are reported here. These guidelines will continue to be updated annually.

Spinal cord stimulation facilitates functional walking in a chronic, incomplete spinal cord injured

DESIGN

This paper describes a treatment paradigm to facilitate functional gait in a quadriplegic, ASIA C spinal cord injured (SCI), wheelchair-dependent subject who presented with some large fiber sensation, sub-functional motor strength in all lower limb muscles, and moderate spasticity. The study utilizes partial weight bearing therapy (PWBT) followed by epidural spinal cord stimulation (ESCS) with the assumption that both treatments would be necessary to elicit a well organized, near effortless functional gait with a walker. Function is defined in terms of accomplishing task-specific activities in the home and community.

OBJECTIVES

To demonstrate the feasibility and benefits of combined PWBT and ESCS therapies aimed at promoting functional gait in a wheelchair-dependent ASIA C SCI subject.

SETTING

The Clinical Neurobiology and Bioengineering Research Laboratories at Good Samaritan Regional Medical Center, Phoenix, Arizona, USA, and the Department of Bioengineering, Arizona State University, Tempe, Arizona, USA.

METHODS

The study began with the application of PWBT. The subject walked on the treadmill until a plateau in gait rhythm generation was reached. Subsequently, ESCS, applied to the lumbar enlargement, was utilized to facilitate PWBT and, later, over-ground walking for a standard distance of 15 m. Gait performance was analyzed by measuring average speed, stepping symmetry, sense of effort, physical work capacity, and whole body metabolic activity.

RESULTS

PWBT led to improved stereotypic stepping patterns associated with markedly reduced spasticity, but was insufficient for over-ground walking in terms of safety, energy cost, and fatigue. ESCS with PWBT generated immediate improvement in the subject's gait rhythm when appropriate stimulation parameters were used. When compared to the non-stimulated condition, over-ground walking with ESCS across a 15 m distance was featured by a reduction in time and energy cost of walking, sense of effort, and a feeling of 'lightness' in the legs. After a few months of training, performance in speed, endurance, and metabolic responses gradually converged with/without ESCS at this short distance, suggesting a learned response to these conditions. However, at longer distances (eg, 50-250 m), performance with ESCS was considerably superior. The subject was able to perform multiple functional tasks within the home and community with ESCS.

CONCLUSION

We propose that ESCS augments the use-dependent plasticity created by PWBT and may be a valuable adjunct to post-SCI treadmill training in ASIA C subjects. We also conclude that ESCS elicits greater activation of an oxidative motor unit pool, thereby reducing the subject's sense of effort and energetic cost of walking.

Characterization of OXA-29 from Legionella (Fluoribacter) gormanii: molecular class D beta-lactamase with unusual properties

A class D beta-lactamase determinant was isolated from the genome of Legionella (Fluoribacter) gormanii ATCC 33297(T). The enzyme, named OXA-29, is quite divergent from other class D beta-lactamases, being more similar (33 to 43% amino acid identity) to those of groups III (OXA-1) and IV (OXA-9, OXA-12, OXA-18, and OXA-22) than to other class D enzymes (21 to 24% sequence identity). Phylogenetic analysis confirmed the closer ancestry of OXA-29 with members of the former groups. The OXA-29 enzyme was purified from an Escherichia coli strain overexpressing the gene via a T7-based expression system by a single ion-exchange chromatography step on S-Sepharose. The mature enzyme consists of a 28.5-kDa polypeptide and exhibits an isoelectric pH of >9. Analysis of the kinetic parameters of OXA-29 revealed efficient activity (k(cat)/K(m) ratios of >10(5) M(-1) x s(-1)) for several penam compounds (oxacillin, methicillin, penicillin G, ampicillin, carbenicillin, and piperacillin) and also for cefazolin and nitrocefin. Oxyimino cephalosporins and aztreonam were also hydrolyzed, although less efficiently (k(cat)/K(m) ratios of around 10(3) M(-1) x s(-1)). Carbapenems were neither hydrolyzed nor inhibitory. OXA-29 was inhibited by BRL 42715 (50% inhibitory concentration [IC(50)], 0.44 microM) and by tazobactam (IC(50), 3.2 microM), but not by clavulanate. It was also unusually resistant to chloride ions (IC(50), >100 mM). Unlike OXA-10, OXA-29 was apparently found as a dimer both in diluted solutions and in the presence of EDTA. Its activity was either unaffected or inhibited by divalent cations. OXA-29 is a new class D beta-lactamase that exhibits some unusual properties likely reflecting original structural and mechanistic features.

How government policy decisions affect seniors' quality of life: findings from a participatory policy study carried out in Toronto, Canada

Toronto seniors explored how government policy decisions were influencing their health and well-being. In this participatory policy study, emphasis was upon the lay and critical knowledge of highly informed seniors. Focus groups and interviews revealed that all three levels of governments were seen as not listening to seniors' voices. In nine key policy areas identified as influencing seniors' quality of life--hearing seniors' voices, housing, acute illness care, long-term care, income supports, transportation and mobility, promoting healthy lifestyles, access to information, and hearing voices from cultural communities--many concerns were raised. The gap between government rhetoric and government action on seniors' issues merits public health attention.

Modified fetal biophysical profile in the assessment of perinatal outcome

The aim of the study is the evaluation of variables of the biophysical profile in the assessment of perinatal outcome. The prospective study included 87 pregnant women with singleton pregnancy in the 28th to 42nd week of gestation with clinically and ultrasonically verified fetal growth retardation, where the fetal biophysical profile was assessed antenatally. Through the factor analysis of biophysical profile variables we obtained values indicating the contribution of individual variables to the predictability of perinatal outcome. 70% of the patients were examined in 15 minutes according to the principles of modified biophysical profile. The most sensitive variable of the biophysical profile in the prediction of perinatal outcome was the amniotic fluid volume, followed by fetal breathing movements, non-stress test and fetal movements, while the lowest prediction value was assigned to the fetal tone. The modified biophysical profiles need to be perfected on a larger number of pregnant women, which would advance the predictability of this method in detection of hypoxically endangered fetuses.

The 2000 Canadian recommendations for the management of hypertension: Part one--therapy

OBJECTIVE

To provide updated, evidence-based recommendations for the therapy of hypertension in adults.

OPTIONS

For patients with hypertension, there are a number of lifestyle manoeuvres and antihypertensive agents that may control blood pressure. Randomized trials evaluating first- line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed.

OUTCOMES

The health outcomes considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence.

EVIDENCE

Medline searches were conducted from the period of the last revision of the Canadian Recommendations for the Management of Hypertension (May 1998 to October 2000). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and mortality.

BENEFITS, HARMS, AND COSTS

Various lifestyle manoeuvres and antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality.

RECOMMENDATIONS

The present document contains detailed recommendations pertaining to all aspects of the therapy of patients with hypertension, including lifestyle modifications proven to lower blood pressure, treatment thresholds, target blood pressures, choice of agents in various settings and strategies to enhance adherence. Lower thresholds for blood pressure treatment are advocated for people with other cardiovascular risk factors or established hypertensive target organ damage. Implicit in the recommendations for therapy is the principle that treatment should be individualized for each patient and the choice of agent should be dictated by coexistent conditions. For the treatment of uncomplicated essential hypertension, thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors or calcium channel blockers may be appropriate, depending on individual circumstances.

VALIDATION

All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported here. These guidelines will be updated annually.