Resolution enhancement with a task-assisted GAN to guide optical nanoscopy image analysis and acquisition

Super-resolution fluorescence microscopy methods enable the characterization of nanostructures in living and fixed biological tissues. However, they require the adjustment of multiple imaging parameters while attempting to satisfy conflicting objectives, such as maximizing spatial and temporal resolution while minimizing light exposure. To overcome the limitations imposed by these trade-offs, post-acquisition algorithmic approaches have been proposed for resolution enhancement and image-quality improvement. Here we introduce the task-assisted generative adversarial network (TA-GAN), which incorporates an auxiliary task (for example, segmentation, localization) closely related to the observed biological nanostructure characterization. We evaluate how the TA-GAN improves generative accuracy over unassisted methods, using images acquired with different modalities such as confocal, bright-field, stimulated emission depletion and structured illumination microscopy. The TA-GAN is incorporated directly into the acquisition pipeline of the microscope to predict the nanometric content of the field of view without requiring the acquisition of a super-resolved image. This information is used to automatically select the imaging modality and regions of interest, optimizing the acquisition sequence by reducing light exposure. Data-driven microscopy methods like the TA-GAN will enable the observation of dynamic molecular processes with spatial and temporal resolutions that surpass the limits currently imposed by the trade-offs constraining super-resolution microscopy.

A case-control study on predicting population risk of suicide using health administrative data: a research protocol

INTRODUCTION

Suicide has a complex aetiology and is a result of the interaction among the risk and protective factors at the individual, healthcare system and population levels. Therefore, policy and decision makers and mental health service planners can play an important role in suicide prevention. Although a number of suicide risk predictive tools have been developed, these tools were designed to be used by clinicians for assessing individual risk of suicide. There have been no risk predictive models to be used by policy and decision makers for predicting population risk of suicide at the national, provincial and regional levels. This paper aimed to describe the rationale and methodology for developing risk predictive models for population risk of suicide.

METHODS AND ANALYSIS

A case-control study design will be used to develop sex-specific risk predictive models for population risk of suicide, using statistical regression and machine learning techniques. Routinely collected health administrative data in Quebec, Canada, and community-level social deprivation and marginalisation data will be used. The developed models will be transformed into the models that can be readily used by policy and decision makers. Two rounds of qualitative interviews with end-users and other stakeholders were proposed to understand their views about the developed models and potential systematic, social and ethical issues for implementation; the first round of qualitative interviews has been completed. We included 9440 suicide cases (7234 males and 2206 females) and 661 780 controls for model development. Three hundred and forty-seven variables at individual, healthcare system and community levels have been identified and will be included in least absolute shrinkage and selection operator regression for feature selection.

ETHICS AND DISSEMINATION

This study is approved by the Health Research Ethnics Committee of Dalhousie University, Canada. This study takes an integrated knowledge translation approach, involving knowledge users from the beginning of the process.

The 5-year longitudinal diagnostic profile and health services utilization of patients treated with electroconvulsive therapy in Quebec: a population-based study

PURPOSE

Electroconvulsive therapy (ECT) is effective for treating several psychiatric disorders. However, only a minority of patients are treated with ECT. It is of primary importance to characterize their profile for epidemiological purposes and to inform clinical practice. We aimed to characterize the longitudinal profile of psychopathology and services utilization of patients first treated with ECT.

METHODS

We conducted a population-based comparative study using data from a national administrative database in Quebec. Patients who received a first ECT between 2002 and 2016 were compared to controls who were hospitalized in psychiatry but did not receive ECT. We performed descriptive analyses to compare psychiatric diagnoses, domains of psychopathology (internalizing, externalizing and thought/psychotic disorders), medical services and medication use in the 5 years prior to the ECT or hospitalization.

RESULTS

5 080 ECT patients were compared with 179 594 controls. Depressive, anxiety, bipolar and psychotic disorders were more frequent in the ECT group. 96.2% of ECT patients had been diagnosed with depression and 53.8% with a primary psychotic disorder. In the ECT group, 1.0% had been diagnosed exclusively with depression and 47.0% had disorders from that belong to all three domains of psychopathology. Having both internalizing and thought/psychotic disorders was associated with an increased likelihood of receiving ECT vs having internalizing disorders alone (unadjusted OR = 2.93; 95% CI = 2.63, 3.26). All indicators of mental health services utilization showed higher use among ECT patients.

CONCLUSION

Our results provide robust evidence of complex longitudinal psychopathology and extensive services utilization among ECT patients.

On the benefits of representation regularization in invariance based domain generalization

A crucial aspect of reliable machine learning is to design a deployable system for generalizing new related but unobserved environments. Domain generalization aims to alleviate such a prediction gap between the observed and unseen environments. Previous approaches commonly incorporated learning the invariant representation for achieving good empirical performance. In this paper, we reveal that merely learning the invariant representation is vulnerable to the related unseen environment. To this end, we derive a novel theoretical analysis to control the unseen test environment error in the representation learning, which highlights the importance of controlling the smoothness of representation. In practice, our analysis further inspires an efficient regularization method to improve the robustness in domain generalization. The proposed regularization is orthogonal to and can be straightforwardly adopted in existing domain generalization algorithms that ensure invariant representation learning. Empirical results show that our algorithm outperforms the base versions in various datasets and invariance criteria.

Exploring polypharmacy with artificial intelligence: data analysis protocol

BACKGROUND

Polypharmacy is common among older adults and it represents a public health concern, due to the negative health impacts potentially associated with the use of several medications. However, the large number of medication combinations and sequences of use makes it complicated for traditional statistical methods to predict which therapy is genuinely associated with health outcomes. The project aims to use artificial intelligence (AI) to determine the quality of polypharmacy among older adults with chronic diseases in the province of Québec, Canada.

METHODS

We will use data from the Quebec Integrated Chronic Disease Surveillance System (QICDSS). QICDSS contains information about prescribed medications in older adults in Quebec collected over 20 years. It also includes diagnostic codes and procedures, and sociodemographic data linked through a unique identification number for each individual. Our research will be structured around three interconnected research axes: AI, Health, and Law&Ethics. The AI research axis will develop algorithms for finding frequent patterns of medication use that correlate with health events, considering data locality and temporality (explainable AI or XAI). The Health research axis will translate these patterns into polypharmacy indicators relevant to public health surveillance and clinicians. The Law&Ethics axis will assess the social acceptability of the algorithms developed using AI tools and the indicators developed by the Heath axis and will ensure that the developed indicators neither discriminate against any population group nor increase the disparities already present in the use of medications.

DISCUSSION

The multi-disciplinary research team consists of specialists in AI, health data, statistics, pharmacy, public health, law, and ethics, which will allow investigation of polypharmacy from different points of view and will contribute to a deeper understanding of the clinical, social, and ethical issues surrounding polypharmacy and its surveillance, as well as the use of AI for health record data. The project results will be disseminated to the scientific community, healthcare professionals, and public health decision-makers in peer-reviewed publications, scientific meetings, and reports. The diffusion of the results will ensure the confidentiality of individual data.

Recurrent neural networks achieving MLSE performance for optical channel equalization

We explore recurrent and feedforward neural networks to mitigate severe inter-symbol interference (ISI) caused by bandlimited channels, such as high speed optical communications systems pushing the frequency response of transmitter components. We propose a novel deep bidirectional long short-term memory (BiLSTM) architecture that strongly emphasizes dependencies in data sequences. For the first time, we demonstrate via simulation that for QPSK transmission the deep BiLSTM achieves the optimal bit error rate performance of a maximum likelihood sequence estimator (MLSE) with perfect channel knowledge. We assess performance for a variety of channels exhibiting ISI, including an optical channel at 100 Gbaud operation using a 35 GHz silicon photonic (SiP) modulator. We show how the neural network performance deteriorates with increasing modulation order and ISI severity. While no longer achieving MLSE performance, the deep BiLSTM greatly outperforms linear equalization in these cases. More importantly, the neural network requires no channel state information, while its performance is comparable to conventional equalizers with perfect channel knowledge.

A machine learning approach for online automated optimization of super-resolution optical microscopy

Traditional approaches for finding well-performing parameterizations of complex imaging systems, such as super-resolution microscopes rely on an extensive exploration phase over the illumination and acquisition settings, prior to the imaging task. This strategy suffers from several issues: it requires a large amount of parameter configurations to be evaluated, it leads to discrepancies between well-performing parameters in the exploration phase and imaging task, and it results in a waste of time and resources given that optimization and final imaging tasks are conducted separately. Here we show that a fully automated, machine learning-based system can conduct imaging parameter optimization toward a trade-off between several objectives, simultaneously to the imaging task. Its potential is highlighted on various imaging tasks, such as live-cell and multicolor imaging and multimodal optimization. This online optimization routine can be integrated to various imaging systems to increase accessibility, optimize performance and improve overall imaging quality.

Complex imaging systems like super-resolution microscopes currently require laborious parameter optimization before imaging. Here, the authors present an imaging optimization framework based on machine learning that performs simultaneous parameter optimization to simplify this procedure for a wide range of imaging tasks.

A two-step approach for mining patient treatment pathways in administrative healthcare databases

Clustering electronic medical records allows the discovery of information on healthcare practices. Entries in such medical records are usually composed of a succession of diagnostics or therapeutic steps. The corresponding processes are complex and heterogeneous since they depend on medical knowledge integrating clinical guidelines, the physician's individual experience, and patient data and conditions. To analyze such data, we are first proposing to cluster medical visits, consultations, and hospital stays into homogeneous groups, and then to construct higher-level patient treatment pathways over these different groups. These pathways are then also clustered to distill typical pathways, enabling interpretation of clusters by experts. This approach is evaluated on a real-world administrative database of elderly people in Québec suffering from heart failures.

Cell-Free DNA-Based Non-invasive Prenatal Screening for Common Aneuploidies in a Canadian Province: A Cost-Effectiveness Analysis

OBJECTIVE

Yearly, 450 000 pregnant Canadians are eligible for voluntary prenatal screening for trisomy 21. Different screening strategies select approximately 4% of women for invasive fetal chromosome testing. Non-invasive prenatal testing (NIPT) using maternal blood cell-free DNA could reduce those invasive procedures but is expensive. This study evaluated the cost-effectiveness of NIPT strategies compared with conventional strategies.

METHODS

This study used a decision analytic model to estimate the cost-effectiveness of 13 prenatal screening strategies for fetal aneuploidies: six frequently used strategies, universal NIPT, and six strategies incorporating NIPT as a second-tier test. The study considered a virtual cohort of pregnant women of similar size and age as women in Quebec. Model data were obtained from published sources and government databases. The study predicted the number of chromosomal anomalies detected (trisomies 21, 13, and 18), invasive procedures and euploid fetal losses, direct costs, and incremental cost-effectiveness ratios.

RESULTS

Of the 13 strategies compared, eight identified fewer cases at a higher cost than at least one of the remaining five strategies. Integrated serum screening with conditional NIPT had the lowest cost, and the cost per case detected was $63 139, with a 90% reduction of invasive procedures. The number of cases identified was improved with four other screening strategies, but with increasing of incremental costs per case (from $61 623 to $1 553 615). Results remained robust, except when NIPT costs and risk cut-offs varied.

CONCLUSION

NIPT as a second-tier test for high-risk women is likely to be cost-effective as compared with screening algorithms not involving NIPT.

Cost-effectiveness analysis of antiviral treatment in the management of seasonal influenza A: point-of-care rapid test versus clinical judgment

Background

A point‐of‐care rapid test (POCRT) may help early and targeted use of antiviral drugs for the management of influenza A infection.

Objective

(i) To determine whether antiviral treatment based on a POCRT for influenza A is cost‐effective and, (ii) to determine the thresholds of key test parameters (sensitivity, specificity and cost) at which a POCRT based‐strategy appears to be cost effective.

Methods

An hybrid « susceptible, infected, recovered (SIR) » compartmental transmission and Markov decision analytic model was used to simulate the cost‐effectiveness of antiviral treatment based on a POCRT for influenza A in the social perspective. Data input parameters used were retrieved from peer‐review published studies and government databases. The outcome considered was the incremental cost per life‐year saved for one seasonal influenza season.

Results

In the base‐case analysis, the antiviral treatment based on POCRT saves 2 lives/100 000 person‐years and costs $7600 less than the empirical antiviral treatment based on clinical judgment alone, which demonstrates that the POCRT‐based strategy is dominant. In one and two way‐sensitivity analyses, results were sensitive to the POCRT accuracy and cost, to the vaccination coverage as well as to the prevalence of influenza A. In probabilistic sensitivity analyses, the POCRT strategy is cost‐effective in 66% of cases, for a commonly accepted threshold of $50 000 per life‐year saved.

Conclusion

The influenza antiviral treatment based on POCRT could be cost‐effective in specific conditions of performance, price and disease prevalence.

Efficient sensor placement optimization using gradient descent and probabilistic coverage

We are proposing an adaptation of the gradient descent method to optimize the position and orientation of sensors for the sensor placement problem. The novelty of the proposed method lies in the combination of gradient descent optimization with a realistic model, which considers both the topography of the environment and a set of sensors with directional probabilistic sensing. The performance of this approach is compared with two other black box optimization methods over area coverage and processing time. Results show that our proposed method produces competitive results on smaller maps and superior results on larger maps, while requiring much less computation than the other optimization methods to which it has been compared.

Dabigatran versus warfarin under standard or pharmacogenetic-guided management for the prevention of stroke and systemic thromboembolism in patients with atrial fibrillation: a cost/utility analysis using an analytic decision model

BACKGROUND

Atrial fibrillation (AF) is the most common form of heart arrhythmia and a leading cause of stroke and systemic embolism. Chronic anticoagulation is recommended for preventing those complications. Our study aimed to compare the cost/utility (CU) of three main anticoagulation options: 1) standard warfarin dosing (SD-W) 2) warfarin dosage under the guidance of CYP2C9 and VKORC1 genotyping (GT-W) and 3) dabigatran 150 mg twice a day.

METHODS

A Markov state transition model was built to simulate the expected C/U of dabigatran, SD-W and GT-W anticoagulation therapy for the prevention of stroke and systemic thromboembolism in patients with atrial fibrillation over a period of 5 years under the perspective of the public health care system. Model inputs were derived from extensive literature search and government's data bases. Outcomes considered were the number of total major events (thromboembolic and hemorrhagic events), total costs in Canadian dollars (1CAD$ = 1$US), total quality-adjusted life years (QALYs), costs/QALYs and incremental costs/QALYs gained (ICUR).

RESULTS

Raw base case results show that SD-W has the lowest C/U ratio. However, the dabigatran option might be considered as an alternative, as its cost per additional QALY gained compared to SD-W is CAD $ 4 765, i.e. less than 50 000, the ICUR threshold generally accepted to adopt an intervention. At the same threshold, GT-W doesn't appear to be an alternative to SD-W. Our results were robust to one-way and multi-way sensitivity analyses.

CONCLUSION

SD-W has the lowest C/U ratio among the 3 options. However, dabigatran might be considered as an alternative. GT-W is not C/U and should not currently be recommended for the routine anticoagulotherapy management of AF patients.

An economic evaluation: Simulation of the cost-effectiveness and cost-utility of universal prevention strategies against osteoporosis-related fractures

A patient-level Markov decision model was used to simulate a virtual cohort of 500,000 women 40 years old and over, in relation to osteoporosis-related hip, clinical vertebral, and wrist bone fractures events. Sixteen different screening options of three main scenario groups were compared: (1) the status quo (no specific national prevention program); (2) a universal primary prevention program; and (3) a universal screening and treatment program based on the 10-year absolute risk of fracture. The outcomes measured were total directs costs from the perspective of the public health care system, number of fractures, and quality-adjusted life-years (QALYs). Results show that an option consisting of a program promoting physical activity and treatment if a fracture occurs is the most cost-effective (CE) (cost/fracture averted) alternative and also the only cost saving one, especially for women 40 to 64 years old. In women who are 65 years and over, bone mineral density (BMD)-based screening and treatment based on the 10-year absolute fracture risk calculated using a Canadian Association of Radiologists and Osteoporosis Canada (CAROC) tool is the best next alternative. In terms of cost-utility (CU), results were similar. For women less than 65 years old, a program promoting physical activity emerged as cost-saving but BMD-based screening with pharmacological treatment also emerged as an interesting alternative. In conclusion, a program promoting physical activity is the most CE and CU option for women 40 to 64 years old. BMD screening and pharmacological treatment might be considered a reasonable alternative for women 65 years old and over because at a healthcare capacity of $50,000 Canadian dollars ($CAD) for each additional fracture averted or for one QALY gained its probabilities of cost-effectiveness compared to the program promoting physical activity are 63% and 75%, respectively, which could be considered socially acceptable. Consideration of the indirect costs could change these findings.

Open BEAGLE

Numerous Evolutionary Computations (EC) software tools are now publicly available to the community - see for instance [1] and [2] for a listing of the most well known. The majority of these tools are specific to a particular EC flavor, however, only a few are truly generic EC softwares [3]. The highly diverse and adaptable nature of Evolutionary Algorithms (EA) make generic EC software tools a must-have for rapid prototyping of new approaches. As we all know, EC comprises a broad family of techniques where populations of solutions to problems are represented by some appropriate data structures (e.g. bit strings, real-valued vectors, trees, etc.) on which variation operators (e.g. mutation, crossover, etc.) are applied using iterative algorithms inspired from natural evolution. Different fitness measures can also be used, with one or several objectives, and it is possible to coevolve several species of solutions, with different species represented by possibly different data structures.

Analysis of a master-slave architecture for distributed evolutionary computations

This paper introduces a new mathematical model of the master-slave architecture for distributed evolutionary computations (EC). This model is validated using a concrete implementation based on the Distributed BEAGLE C++ framework. Results show that contrary to (current) popular belief, master-slave architectures are able to scale well over local area networks of workstations using off-the-shelf networking equipment. The main properties of the master-slave are also compared with those of the more mainstream island-model.

Factors explaining the intention to give blood among the general population

BACKGROUND AND OBJECTIVES

The aim of this study was to identify factors explaining the intention to donate blood.

MATERIALS AND METHODS

A random sample of 4000 respondents drawn from the general population received a questionnaire by mail. This questionnaire assessed variables as defined by the most prominent social cognitive theories.

RESULTS

Overall, the respondents expressed a neutral mean level of intention to give blood in the next 6 months (2.84 on a five-point scale); 56.2% had never given blood in the past. The variables explaining 74% of the variance of intention were: perceived behavioural control (beta = 0.39; P < 0.001); factors facilitating taking action (beta = 0.25; P < 0.001); anticipated regret (beta = 0.16; P < 0.001); moral norm (beta = 0.11; P < 0.001); attitude (beta = 0.08; P < 0.01); level of education (beta = -0.03; P < 0.05); and past experience in giving blood (beta = 0.09; P < 0.001). Nonetheless, the predictive power of perceived behavioural control and moral norm was higher among the ever donors (both at P < 0.01) compared to the never donors, whereas the reverse was observed for attitude (P < 0.05).

CONCLUSIONS

People's intentions are mainly determined by perceived barriers and obstacles regarding blood donations. This suggests that promotional strategies should focus on the elimination of barriers to action as well as the development of a higher perception of control. Also, messages should be adapted to the targeted population, based on their previous blood donation behaviour (i.e. never donors vs. ever donors).

[Concomitant treatment of psychosis and drug addiction.]

The high prevalence of addiction problems of people with psychosis and the lack of resources to respond to their complex reality has lead a multidisciplinary team at the Centre de santé mentale communautaire (CSMC) to establish a group allowing interventions on drug addiction and psychosis in a concomitant way. Following a brief presentation of problems and intervention models proposed in the literature, this article aims at summarizing the experience of the CSMC and their strategy in order to respond to the needs of these patients. Thus, this article presents the reasons for modifications made over the years, the relevance of the motivational approach with these patients who are often unmotivated in changing their behaviour regarding substance abuse and the strengths and limits of this approach. The objectives of the therapeutic group, the framework, content and clientele are then discussed. Finally the authors examine various perspectives.

Contribution of receptor negative versus receptor defective mutations in the LDL-receptor gene to angiographically assessed coronary artery disease among young (25-49 years) versus middle-aged (50-64 years) men

Elevated plasma LDL-cholesterol (LDL-C) levels are associated with an increased risk of coronary artery disease (CAD). Familial hypercholesterolemia (FH), a monogenic trait due to mutations in the LDL-receptor (R) gene is characterized by raised plasma LDL-C levels and premature CAD. The aim of the present investigation, derived from the study of a population of 1465 unrelated men aged 25 to 64 years, was to compare the expression of CAD assessed by coronary angiography in young (aged 25-49 years) versus middle-aged (50-64 years) heterozygous FH patients of French Canadian descent. Furthermore, the relationship of binding-defective versus receptor negative mutations in the LDL-R to premature CAD ( < 50 years) was examined and compared with men displaying a normal plasma lipoprotein-lipid profile. From the original study sample, a total of 100 men met the clinical criteria of heterozygous FH. Among them, 30 were carriers of a receptor negative mutation (deletion > 15 kb or point mutations Y468X or R329X) whereas 64 were carriers of a receptor defective mutation (W66G, E207K or C646Y). As expected, in both age groups (25-49 years vs. 50-64 years), carriers of a receptor negative mutation had higher plasma cholesterol and LDL-C levels than carriers of a defective allele or men with a normal plasma lipoprotein-lipid profile. In addition, the mean number of diseased vessels (with > 50% stenosis) was higher in men aged 50-64 years compared to those aged 25 49 years. In the two age groups, FH patients were characterized by a higher number of stenosed coronary vessels than the normal phenotype group. Within each group (either receptor negative, receptor defective or normal phenotype) plasma cholesterol, LDL-C, HDL-C, triglyceride and apolipoprotein B levels were similar irrespective of age (25 49 years vs. 50-64 years). Finally, multiple logistic regression analyses revealed that compared to non-FH men, the relative odds of being affected by CAD before the age of 50 years was 7.3-fold higher for carriers of a receptor negative mutation and 2.7-fold higher for men with a receptor defective mutation at the LDL-R locus. These results suggest that CAD could be an earlier event among heterozygous FH subjects bearing a receptor negative mutation compared to LDL-R defective patients. It also suggest that the selective screening for mutations in the LDL-R gene may allow a better assessment of the individual risk and facilitate the development of family-based preventive strategies or intervention programs in FH.

Fine mapping of low-density lipoprotein receptor gene by genetic linkage on chromosome 19p13.1-p13.3 and study of the founder effect of four French Canadian low-density lipoprotein receptor gene mutations

Familial hypercholesterolemia (FH) is one of the most common autosomal codominant diseases. FH is caused by mutations in the low-density lipoprotein receptor (LDLR) gene and is characterized by raised plasma LDL-cholesterol, tendon xanthomas, and premature coronary heart disease. The frequency of FH among French Canadians in northeastern Quebec is higher than in most other populations, 1:154 vs. 1:500 due to high prevalence of few recurrent mutations in the LDLR gene. In the French Canadian population, 11 mutations in the LDLR gene have been found to occur in geographically diverse areas and account for > 90% of cases. We have first constructed a high-resolution genetic map to locate several highly polymorphic markers close to LDLR locus, thus providing the necessary tools to study the origin of the four most common mutations which account for approximately 80% of our FH patients. We have then genotyped five markers (D19S413, D19S865, D19S221, D19S914, D19S586) in 102 heterozygotes (38 del > 15kb; 36 W66G; 16 C646Y; 12 E207K), two compound heterozygotes (del > 15kb/W66G; del > 15kb/C646Y) and seven homozygotes (three del > 15 kb; three W66G: one E207K) with FH unrelated to the first and second degree. We have found that patients bearing the same LDLR gene mutation carry a common haplotype at the LDLR locus although there is evidence for the early occurrence of a recombinational event between the LDLR and the D19S221 locus in the French Canadian patients bearing the W66G mutation. The fine mapping of LDLR gene close to several highly informative microsatellite markers provide fine mapping details of the LDLR region and additional tools for studies of association between plasma lipoprotein levels and LDLR gene.

Relative contribution of low-density lipoprotein receptor and lipoprotein lipase gene mutations to angiographically assessed coronary artery disease among French Canadians

Men with low-density lipoprotein receptor gene mutations causing familial hypercholesterolemia (FH) are at high risk of premature coronary artery disease (CAD). The dyslipidemic state found among patients who are heterozygous for mutations in the lipoprotein lipase (LPL) gene may also increase the risk of CAD. In the present study, the association of the heterozygous forms of low-density lipoprotein receptor gene mutations causing FH as well as of LPL gene mutations causing (P207L and G188E) or not causing (D9N and N291S) complete loss of LPL activity with angiographically assessed CAD was estimated in a cohort of 412 French Canadian men aged <60 years who consecutively underwent coronary angiography for the investigation of retrosternal pain. The frequency of FH as well as of LPL gene mutations tended to increase with the number of narrowed coronary arteries. However, CAD occurred earlier in FH patients than in partly LPL-deficient patients. Indeed, the proportion of men affected by FH was of 16.4% in those <45 years of age, and solely 4.3% among those between 56 and 60 years of age (p <0.0001). In contrast, the LPL gene defect was found in only 4.0% of men aged <45 years, whereas this prevalence reached 8.3% among those aged 56 to 60 years. In multivariate analyses, the association of LPL with CAD was not independent of age, high-density lipoprotein cholesterol concentrations, and other covariates included at baseline, and was not affected by the type of mutation in the LPL gene. In contrast, FH was associated with CAD with minimal contribution of other cardiovascular risk factors. However, the relation between FH and CAD was at least partly dependent on plasma apolipoprotein B concentrations. In the different regression models, fasting insulin and plasma high-density lipoprotein cholesterol concentrations were important covariates of CAD, whether or not patients were affected by FH or LPL deficiency. In conclusion, the association of LPL gene mutations with CAD was delayed compared with FH, appeared to be markedly exacerbated by the presence of additional risk factors, and was not affected by the type of mutation in the LPL gene.

Association of specific LDL receptor gene mutations with differential plasma lipoprotein response to simvastatin in young French Canadians with heterozygous familial hypercholesterolemia

In familial hypercholesterolemia (FH), the efficacy of the inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase shows considerable interindividual variation, and several genetic and environmental factors can contribute to explaining this variability. A randomized, double-blind, placebo-controlled clinical trial with simvastatin, an HMG-CoA reductase inhibitor, was conducted in 63 children and adolescents with heterozygous FH. The patients were grouped according to known LDL receptor genotype. After 6 weeks of treatment with 20 mg/d simvastatin, the mean reduction in plasma LDL cholesterol in patients with the W66G mutation (n=14) was 31%, whereas in the deletion>15 kb (n=23) and the C646Y mutation groups (n=10), it was 38% and 42%, respectively (P<0.05). After treatment with simvastatin, HDL cholesterol levels were increased in all groups, and triglyceride concentrations were significantly reduced. Multiple regression analyses suggested that 42% of the variation of the LDL cholesterol response to simvastatin can be attributed to variation in the mutant LDL receptor locus, apolipoprotein E genotype, and body mass index, while 35% of the variation in HDL cholesterol response was explained by sex and baseline HDL cholesterol. These results show that simvastatin was an effective and well-tolerated therapy for FH in the pediatric population for all LDL receptor gene mutations. Moreover, the nature of LDL receptor gene mutations and other genetic and constitutional factors play a significant role in predicting the efficacy of simvastatin in the treatment of FH in children and adolescents.

Relationships of abdominal obesity and hyperinsulinemia to angiographically assessed coronary artery disease in men with known mutations in the LDL receptor gene

BACKGROUND

Patients with a mutation in the LDL receptor gene (familial hypercholesterolemia, or FH) are characterized by substantial elevations in plasma LDL cholesterol and are at higher risk of developing coronary artery disease (CAD). Correlates of abdominal obesity may also contribute to the risk of ischemic cardiac events. Whether the hyperinsulinemic-insulin-resistant state of abdominal obesity affects coronary atherosclerosis among FH patients has not been determined.

METHODS AND RESULTS

The relation of abdominal adiposity and hyperinsulinemia to angiographically assessed CAD was evaluated in a sample of 120 French Canadian men aged <60 years who were heterozygotes for FH and in a group of 280 men without FH. In the present study, the risk of CAD associated with abdominal obesity, as estimated by the waist circumference, was largely dependent on the concomitant variation in plasma lipoprotein and insulin concentrations. In contrast, the association between fasting insulin and CAD was independent of variations in waist girth, triglyceride, HDL, and apolipoprotein B concentrations (odds ratio, 1.86; P=.0005). However, the most substantial increase in the risk of CAD was observed among abdominally obese (waist circumference >95 cm) and hyperinsulinemic FH patients (odds ratio, 12.9; P=.0009). This increase in risk remained significant even after adjustment for LDL cholesterol or apolipoprotein B concentrations.

CONCLUSIONS

Results of the present study provide support for the notion that the hyperinsulinemic-insulin-resistant state of abdominal obesity is a powerful predictor of CAD in men, even in a group of patients with raised LDL cholesterol concentrations due to FH.

Hyperinsulinemia and abdominal obesity affect the expression of hypertriglyceridemia in heterozygous familial lipoprotein lipase deficiency

We have reported three missense mutations (G188E, P207L, and D250N) in the lipoprotein lipase (LPL) gene among French-Canadians, resulting in the absence of measurable postheparin plasma LPL activity in homozygotes. Presence of triglyceride- and cholesterol-rich VLDL, as well as cholesterol-poor HDL particles, has been shown in heterozygotes affected by partial reduction in postheparin LPL activity. However, significant heterogeneity in their plasma triglyceride levels has been found, even among individuals carrying the same LPL gene mutation, indicating that factors other than LPL deficiency could affect the phenotypic expression of hypertriglyceridemia in the heterozygous state. The aim of the present study was to examine the combined effects of abdominal fat accumulation and hyperinsulinemia on plasma triglyceride levels among heterozygous patients for familial LPL deficiency. Based on sex and BMI, 43 heterozygotes (25 women and 18 men) were matched with noncarrier control subjects. Our data indicate that heterozygotes with higher abdominal fat deposition, as defined as waist girth values above the 50th percentile, had higher plasma triglyceride levels than nonobese heterozygotes. However, an important proportion of male heterozygote subjects were hypertriglyceridemic, even in absence of abdominal obesity, suggesting that another factor(s) was involved in the modulation of hypertriglyceridemia in these subjects. Indeed, multivariate analyses revealed that fasting hyperinsulinemia was a significant correlate of hypertriglyceridemia among these heterozygotes. Results of the present study indicate that abdominal obesity and hyperinsulinemia both have deleterious effects on plasma triglyceride levels in familial LPL deficiency. It is suggested that heterozygotes with moderate obesity and/or insulin resistance may be at higher risk of coronary artery disease because of the expression of an atherogenic lipoprotein phenotype among these patients.

Geographic distribution of French-Canadian low-density lipoprotein receptor gene mutations in the Province of Quebec

A total of 35 homozygous and 1320 heterozygous patients with familial hypercholesterolemia (FH) was screened for the presence of six low-density lipoprotein receptor (LDLR) gene mutations previously reported among French-Canadians. The geographic distribution of patients' birthplaces and the relative prevalence of these six mutations in the LDLR gene in the province of Quebec were compared. For this purpose, the 16 administrative regions of the province of Quebec were grouped into seven geographic regions. The relative frequency of the six mutations differed in the seven regions: the > 15 kb deletion (delta > 15 kb) had the highest relative frequency in the Bas St-Laurent/Gaspésie region, and the point mutation in exon 3 had the highest relative frequency in the Saguenay-Lac-St-Jean/Côte-Nord region. In the Montreal area, the delta > 15 kb and the mutation in exon 3 had prevalence rates of 71.2% and 13.0%, respectively, whereas the relative frequencies of the delta > 15 kb and the point mutation in exon 3 in the Quebec city region were 57.5 and 21.8%, respectively. Finally, in Saguenay-Lac-St-Jean/Côte-Nord, the relative frequency of the delta > 15 kb only reached 31.5% and the point mutation in exon 3, 59.2%. Thus, on the north shore of the St. Lawrence River, the prevalence of the delta > 15 kb decreases from west to north-east, whereas the relative frequency of the mutation in exon 3 appears to increase. These observations provide a better characterization of FH among French-Canadians of Quebec, a Canadian province with a high prevalence of this inherited disease.

Comparison of the effect of two low-density lipoprotein receptor class mutations on coronary heart disease among French-Canadian patients heterozygous for familial hypercholesterolaemia

The aim of this study was to compare the age at first elective coronary angiogram and the age at first revascularization (coronary artery bypass grafting or percutaneous transluminal coronary angioplasty) in 102 patients without familial hypercholesterolaemia (FH), who were matched for age and sex with 76 heterozygous FH patients carrying a defective allele at the low-density lipoprotein (LDL) receptor gene (LDL-R) and 26 heterozygous FH patients bearing a null mutation at the LDL-R. The prevalence of diabetes was significantly higher in the non-FH group than in the two FH groups (P < 0.05). Furthermore, mean body mass index (BMI) and waist circumference values were also higher in the non-FH group than in the two FH heterozygous groups (P < 0.005). However, FH patients who were null allele carriers had the highest plasma total and LDL-cholesterol levels and the highest cholesterol/HDL-cholesterol ratio, whereas the defective allele carriers group had intermediate levels between null allele carriers and non-FH patients. Comparison of the age at first coronary angiography revealed that the null allele carriers group were younger at first angiogram than the non-FH patients (P < 0.005). In addition, a trend was observed for a younger age at first angiogram in FH heterozygotes bearing a null allele than in carriers of a defective allele (P = 0.06). Moreover, null allele carriers were younger at first revascularization than defective allele carriers (P < 0.005) or non-FH patients (P < 0.005). Finally, the mean number of diseased vessels with > 50% stenosis was higher in null allele carriers than in non-FH patients and tended to be higher than among defective allele carriers (P < 0.01). Although no difference in plasma Lp(a) levels were noted between null allele carrier and non-FH patients, plasma Lp(a) concentrations were higher in the defective allele group than in the other two groups. In summary, the development of coronary artery disease as estimated by the age at first elective coronary angiography or at first revascularization is premature in FH patients carrying a null mutation compared with defective allele carriers or with non-FH patients. Moreover, the higher number of stenosed vessels among null allele carriers suggests that coronary artery disease was more severe in FH subjects with a null allele at the LDL-R locus.

Heterozygous familial hypercholesterolemia in children: low-density lipoprotein receptor mutational analysis and variation in the expression of plasma lipoprotein-lipid concentrations

The phenotypic expression of heterozygous familial hypercholesterolemia (FH) is variable form biochemical and clinical standpoints and several genetic and environmental factors could contribute to explain this variability. We have compared, in a cohort of 266 heterozygous FH children and adolescents (1-19 years), the variation in plasma lipoprotein-lipid levels among patients defined by three mutations in the low density lipoprotein receptor (LDLR) gene. Comparison of the plasma total and LDL-cholesterol (LDL-C) levels among the three mutation groups revealed significant differences. Plasma total and LDL-C levels were significantly higher (P < 0.05) in the group bearing the French-Canadian delta > 15 kb null allele mutation (8.17 +/- 1.45 and 6.58 +/- 1.42 mmol/l) and in the group with the defective allele C646Y missense mutation (8.18 +/- 1.53 and 6.65 +/- 1.50 mmo/l) compared to the group with the defective allele W66G missense mutation (7.19 +/- 1.23 and 5.62 +/- 1.16 mmol/l). Comparisons of other lipoprotein-lipid parameters between FH heterozygotes and normolipemic (n = 120) children indicated that all mutation groups had significantly (P = 0.0001) lower plasma HDL-cholesterol (HDL-C) levels and a higher total cholesterol (TC) to HDL-C ratio (P < 0.05). Among FH heterozygote groups, the W66G group had the lowest TC to HDL-C ratio. Multivariate analyses revealed that in FH heterozygotes as well as in controls, HDL-C levels contributed to a greater proportion of the variation in TC to HDL-C ratio than TC. In order to examine the age effect, control and FH heterozygote delta > 15 kb groups were then subdivided into four groups (1-4; 5-8; 9-13, and 14-19 years). The variation in HDL-C and triglycerides with age in heterozygous FH children showed a pattern which was similar to the one noted in the control group. In conclusion, the present study demonstrated that the overall contribution of age to variation in the lipoprotein profile of heterozygous FH children is similar to the effect observed among healthy children. The effect of LDLR gene in FH is dominant and there was no difference in plasma TC and LDL-C due to gender. Finally, this study indicates that the LDLR gene type mutations are a modulator of the magnitude of the increase in plasma TC and LDL-C levels noted among FH heterozygote children.

Treatment of familial hypercholesterolemia in children and adolescents: effect of lovastatin. Canadian Lovastatin in Children Study Group

OBJECTIVE

Familial hypercholesterolemia (FH), an inherited autosomal dominant disorder of lipoprotein metabolism, is associated with premature atherosclerosis. The recommended pediatric therapy consists of dietary intervention and, when necessary, treatment with bile acid-binding resins. However, compliance has been poor in many children. Therefore, our objectives were to determine the efficacy, safety, and tolerance of the short-term use of lovastatin, a 3-hydroxy 3-methylglutaryl coenzyme A reductase inhibitor, in the control of severe FH in a male pediatric population and to evaluate the dose-response relationship.

METHODS

Sixty-nine male patients with FH 12.9 +/- 2.4 years of age (mean +/- SD) participated in this multicenter, randomized, double-blind trial. After a 4-week placebo period, the patients were allocated to four treatment groups (lovastatin 10, 20, 30, 40 mg/d) for 8 weeks. Plasma lipid and apolipoprotein (Apo) concentrations were measured every 2 weeks. Clinical and laboratory evidence of adverse events was monitored periodically throughout the study.

RESULTS

All lovastatin doses reduced total cholesterol (-17% to -29%), low density lipoprotein cholesterol (-21% to -36%), and ApoB (-19% to -28%) concentrations. A dose-response relationship was seen, and between-group comparisons showed that results were significantly improved up to a dose of 30 mg/d. We observed a 7% increase in high-density lipoprotein cholesterol and a 4% increase in ApoA1 concentrations. The medication was well tolerated by all patients. No serious clinical adverse experience was reported. Lovastatin increased aspartate aminotransferase concentrations, but there was no evidence of a dose-response relationship, and no value exceeded two times the upper limit of normal. No significant change in alanine aminotransferase was observed. Three patients had marked (more than three times the upper limit of normal) asymptomatic elevations in their creatine kinase values, which returned spontaneously to normal, and no action was required regarding the drug.

Alterations in plasma lipoproteins and apolipoproteins before the age of 40 in heterozygotes for lipoprotein lipase deficiency

We have assessed the expression of heterozygosity for lipoprotein lipase (LPL) deficiency by studying a single large French Canadian family comprising 92 persons including 21 carriers of the catalytically defective P207L mutation. Phenotypic changes distinguishing heterozygotes from controls were seen early, before the age of 40 and often before 20 years of age. In the total cohort these changes included an elevation in the mean very low density (VLDL) and intermediate density lipoprotein (IDL) triglyceride (+69%; P = 0.01 and +40%; P = 0.001) and cholesterol (+51%; P = 0.03 and +67%; P = 0.007) and apoB levels but decreased HDL2 and HDL3 cholesterol, (-32%; P = 0.01 and -15%; P = 0.002 respectively). While the lipid compositions of VLDL and IDL were similar between heterozygotes and controls, the low density (LDL) and high density lipoproteins (HDL) of carriers were triglyceride enriched. Heterozygotes also had a markedly lower apoC-III ratio (apoC-III in supernatant/apoC-III in heparin precipitate) (1.46 vs. 3.86 P = 1 x 10(-4)) indicating a substantial enrichment of VLDL and IDL with apoC-III and depletion of HDL apoC-III supporting this ratio as an effective index for efficiency of lipolysis. LpA-I was markedly reduced (0.34 vs. 0.43 P = 1 x 10(-5)) showing that levels of this particle are partly dependent on LPL catalytic activity. Heterozygotes manifest from an early age with a markedly reduced HDL, LpA-I, apoC-III ratio and an increased TC/HDLc ratio which would predict a relatively increased risk of premature coronary artery disease, compared to their normal siblings.