Publications by authors named "David Marais"

Article Synopsis
  • Data on acute coronary syndrome (ACS) in Africa is insufficient, particularly regarding the increasing cases of premature ACS, highlighting the need for an epidemiological assessment to identify risk factors and improve management practices.
  • The European Atherosclerosis Society initiated the Lipid Registry of Africa (EAS-LIPRA) to create a standardized registry that collects and analyzes data on premature ACS across multiple African countries.
  • EAS-LIPRA aims to enhance understanding of ACS by stratifying data based on income levels and urban/rural residence, using valid statistical methods to compare demographics and management trends, potentially serving as a model for similar initiatives in other developing regions.
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The extraordinary diversity and adaptive fit of organisms to their environment depends fundamentally on the availability of variation. While most population genetic frameworks assume that random mutations produce isotropic phenotypic variation, the distribution of variation available to natural selection is more restricted, as the distribution of phenotypic variation is affected by a range of factors in developmental systems. Here, we revisit the concept of developmental bias - the observation that the generation of phenotypic variation is biased due to the structure, character, composition, or dynamics of the developmental system - and argue that a more rigorous investigation into the role of developmental bias in the genotype-to-phenotype map will produce fundamental insights into evolutionary processes, with potentially important consequences on the relation between micro- and macro-evolution.

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Carbonate minerals are of particular interest in paleoenvironmental research as they are an integral part of the carbon and water cycles, both of which are relevant to habitability. Given that these cycles are less constrained on Mars than they are on Earth, the identification of carbonates has been a point of emphasis for rover missions. Here, we present carbon (δC) and oxygen (δO) isotope data from four carbonates encountered by the Curiosity rover within the Gale crater.

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  • Phenology, the timing of plant development, is influenced by genetic variation and affects how traits manifest across different seasons, although much remains unknown about its genetic contributions in wild populations.
  • Researchers compared germination and flowering time data from controlled experiments with wild plant collection dates to see if genetic variation could predict natural phenology.
  • Although there was a weak correlation found between controlled experiments and wild phenology, local collection date variations were not explained by genetic factors, indicating significant environmental influence and potential for rapid plasticity in natural settings.
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Scientists must have an integrative understanding of ecology and evolution across spatial and temporal scales to predict how species will respond to global change. Although comprehensively investigating these processes in nature is challenging, the infrastructure and data from long-term ecological research networks can support cross-disciplinary investigations. We propose using these networks to advance our understanding of fundamental evolutionary processes and responses to global change.

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Organisms experience a constantly changing environment and must adjust their development to maximize fitness. These "life histories" are fantastically diverse and have fascinated biologists for decades. Recent work published in Cell reveals the complex genetic mechanisms that drive life-history variation within and among species in the Brassicaceae plant family.

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As scientific investigations increasingly adopt Open Science practices, reuse of data becomes paramount. However, despite decades of progress in internet search tools, finding relevant astrobiology datasets for an envisioned investigation remains challenging due to the precise and atypical needs of the astrobiology researcher. In response, we have developed the Astrobiology Resource Metadata Standard (ARMS), a metadata standard designed to uniformly describe astrobiology "resources," that is, virtually any product of astrobiology research.

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Leaf-out in temperate forests is a critical transition point each spring and advancing with global change. The mechanism linking phenological variation to external cues is poorly understood. Nonstructural carbohydrate (NSC) availability may be key.

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How do selection and standing genetic variation shape population divergence across landscapes? Henry and Stinchcombe estimated selection gradients on traits in the ivy-leaved morning glory (Ipomoea hederacea) in the field and compared them with the G-matrix and population divergence for four populations in North America. The authors show that population divergence and genetic covariances are largely unaligned with the selection gradient at the species' range edge. These findings raise the question of whether limited evolvability or multivariate genetic variation of populations at range edges prevent species from range expansion, which is important for understanding the role of genetic constraint in population divergence and predicting local adaptation in the face of climate change.

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Background: Proprotein convertase subtilisin kexin type 9 (PCSK9) monoclonal antibodies (mAbs) reduce fasting and post fat load cholesterol in non-HDL and intermediate density lipoprotein (IDL) in familial dysbetalipoproteinemia (FD). However, the effect of PCSK9 mAbs on the distribution and composition of atherogenic lipoproteins in patients with FD is unknown.

Objective: To evaluate the effect of the PCSK9 mAb evolocumab added to standard lipid-lowering therapy in patients with FD on fasting and post fat load lipoprotein distribution and composition.

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Non-Alcoholic Fatty Liver Disease (NAFLD) is a common condition affecting around 10-25% of the general adult population, 15% of children, and even > 50% of individuals who have type 2 diabetes mellitus. It is a major cause of liver-related morbidity, and cardiovascular (CV) mortality is a common cause of death. In addition to being the initial step of irreversible alterations of the liver parenchyma causing cirrhosis, about 1/6 of those who develop NASH are at risk also developing CV disease (CVD).

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Unlabelled: Clearance of triglyceride-rich lipoproteins (TRLs) is mediated by several receptors, including heparan sulfate proteoglycans (HSPGs). Sulfate glucosamine-6-O-endosulfatase-2 is a gene related to the regulation of HSPG. A variant in this gene, rs2281279, has been shown to be associated with triglycerides and insulin resistance.

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Article Synopsis
  • The study aimed to compare different methods for measuring LDL-C concentrations against a reference standard in patients with Familial Dysbetalipoproteinemia (FD).
  • It analyzed data from 28 FD patients using the Friedewald formula, Martin-Hopkins formula, direct assay, and PGGE, comparing results to density gradient ultracentrifugation.
  • The findings revealed that all four LDL-C measurement methods had significant inaccuracies compared to ultracentrifugation, while non-HDL-C measurements were more reliable, suggesting a preference for using non-HDL-C in FD patients.
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Chylomicronaemia accompanies hypertriglyceridaemia, usually due to a polygenic predisposition in combination with secondary risk factors. Monogenic chylomicronaemia represents a small subgroup of patients with hypertriglyceridaemia. This article describes three patients and illustrates the heterogeneity in the presentation of monogenic chylomicronaemia.

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Article Synopsis
  • Familial dysbetalipoproteinemia (FD) is a lipid disorder affecting about 1 in 850-3500 people, linked to a higher risk of cardiovascular disease due to lipid imbalances, with many patients not reaching their cholesterol treatment goals.* -
  • A study assessed the effectiveness of adding the PCSK9 monoclonal antibody evolocumab to standard lipid-lowering therapy in FD patients, using a randomized, placebo-controlled, double-blind design over two 12-week periods.* -
  • Results showed that evolocumab significantly lowered levels of non-HDL cholesterol and apolipoprotein B, potentially reducing cardiovascular risk, although it did not prevent a rise in lipid levels after fat consumption.*
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Natural populations are characterized by abundant genetic diversity driven by a range of different types of mutation. The tractability of sequencing complete genomes has allowed new insights into the variable composition of genomes, summarized as a species pan-genome. These analyses demonstrate that many genes are absent from the first reference genomes, whose analysis dominated the initial years of the genomic era.

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Statin intolerance is a clinical syndrome whereby adverse effects (AEs) associated with statin therapy [most commonly statin-associated muscle symptoms (SAMS)] result in the discontinuation of therapy and consequently increase the risk of adverse cardiovascular outcomes. However, complete statin intolerance occurs in only a small minority of treated patients (estimated prevalence of only 3-5%). Many perceived AEs are misattributed (e.

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Article Synopsis
  • - Familial Dysbetalipoproteinemia (FD) is a common genetic condition that significantly increases the risk of cardiovascular disease due to high levels of certain cholesterol types, typically caused by genetic variants in the APOE gene.
  • - Diagnosing FD involves confirming both the genetic variant and related symptoms, with Next Generation Sequencing helping identify potentially pathogenic APOE gene variants.
  • - The article discusses two methods to determine if a new APOE variant causes FD: a comprehensive approach involving various tests and a more practical one for patient management in clinical settings.
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Article Synopsis
  • * Recent studies reveal that the APOE gene also plays a significant role in Lp(a) levels, especially where the apoE2 variant is concerned, showing that carriers of this variant have lower Lp(a) concentrations.
  • * While the apoE2 genotype can lead to another lipid disorder called dysbetalipoproteinemia, it does not affect Lp(a) levels, indicating that there are complex mechanisms involved in Lp(a) production and metabolism.
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Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model grass species. Due to limited knowledge on dehydrin expression under water deprivation stress in we also performed a drought-induced gene expression analysis in 32 ecotypes of the genus' flagship species showing different hydric requirements.

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We develop a method to artificially select for rhizosphere microbiomes that confer salt tolerance to the model grass grown under sodium salt stress or aluminum salt stress. In a controlled greenhouse environment, we differentially propagated rhizosphere microbiomes between plants of a nonevolving, highly inbred plant population; therefore, only microbiomes evolved in our experiment, but the plants did not evolve in parallel. To maximize microbiome perpetuation when transplanting microbiomes between plants and, thus, maximize response to microbiome selection, we improved earlier methods by (i) controlling microbiome assembly when inoculating seeds at the beginning of each selection cycle; (ii) fractionating microbiomes before transfer between plants to harvest, perpetuate, and select on only bacterial and viral microbiome components; (iii) ramping of salt stress gradually from minor to extreme salt stress with each selection cycle to minimize the chance of overstressing plants; (iv) using two nonselection control treatments (e.

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Heterozygous familial hypercholesterolaemia (FH) is among the most common genetic metabolic lipid disorders characterised by elevated low-density lipoprotein cholesterol (LDL-C) levels from birth and a significantly higher risk of developing premature atherosclerotic cardiovascular disease. The majority of the current pediatric guidelines for clinical management of children and adolescents with FH does not consider the impact of genetic variations as well as characteristics of vascular phenotype as assessed by recently developed non-invasive imaging techniques. We propose a combined integrated approach of cardiovascular (CV) risk assessment and clinical management of children with FH incorporating current risk assessment profile (LDL-C levels, traditional CV risk factors and familial history) with genetic and non-invasive vascular phenotyping.

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