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PubMedDate not supplied

A conceptual map for studying long-term exercise adherence in a cardiac population.

The failure of people with coronary heart disease to adhere to prescribed programs of long-term exercise is a growing concern among healthcare professionals. The problem is attributed partly to not correctly identifying the specific exercise adherence behavior desired. There is a need in cardiac rehabilitation for different theoretical and practical approaches to the study of patient adherence to short-term and long-term exercise prescriptions. This article is a review of behavioral and cognitive models used to promote exercise in cardiac rehabilitation programs. Concepts are borrowed from these models to design a conceptual map intended to identify variables and relationships associated with exercise adherence behaviors. In this article, the Coronary Artery Disease Exercise Map (CADEM), an evolving conceptual map, addresses exercise behavior within a coronary population. However, this map may also be applied to people who have other chronic conditions. It is believed that the CADEM will provide researchers and healthcare providers with a framework with which to understand, promote, and evaluate adherence to exercise regimes within the rehabilitation population.

Coronary Disease↗
PubMed2005

Polymorphisms in cinnamoyl CoA reductase (CCR) are associated with variation in microfibril angle in Eucalyptus spp.

Linkage disequilibrium (LD) mapping using natural populations results in higher resolution of marker-trait associations compared to family-based quantitative trait locus (QTL) studies. Depending on the extent of LD, it is possible to identify alleles within candidate genes associated with a trait. Analysis of a natural mutant in Arabidopsis has shown that mutations in cinnamoyl CoA reductase (CCR), a key lignin gene, affect physical properties of the secondary cell wall such as stiffness and strength. Using this gene, we tested whether LD mapping could identify alleles associated with microfibril angle (MFA), a wood quality trait affecting stiffness and strength of wood. We identified 25 common single-nucleotide polymorphism (SNP) markers in the CCR gene in Eucalyptus nitens. Using single-marker and haplotype analyses in 290 trees from a E. nitens natural population, two haplotypes significantly associated with MFA were found. These results were confirmed in two full-sib families of E. nitens and Eucalyptus globulus. In an effort to understand the functional significance of the SNP markers, we sequenced the cDNA clones and identified an alternatively spliced variant from the significant haplotype region. This study demonstrates that LD mapping can be used to identify alleles associated with wood quality traits in natural populations of trees.

Aldehyde Oxidoreductases↗
PubMed2006

Population growth rate and carrying capacity for springtails Folsomia candida exposed to ivermectin.

Forecasting the effects of stressors on the dynamics of natural populations requires assessment of the joint effects of a stressor and population density on the population response. The effects can be depicted as a contour map in which the population response, here assessed by population growth rate, varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. We present the first complete map of this type using as our model Folsomia candida exposed to five different concentrations of the widespread anthelmintic veterinary medicine ivermectin in replicated microcosm experiments lasting 49 days. The concentrations of ivermectin in yeast were 0.0, 6.8, 28.8, 66.4, and 210.0 mg/L wet weight. Increasing density and chemical concentration both significantly reduced the population growth rate of Folsomia candida, in part through effects on food consumption and fecundity. The interaction between density and ivermectin concentration was "less-than-additive," implying that at high density populations were able to compensate for the effects of the chemical. This result demonstrates that regulatory protocols carried out at low density (as in most past experiments) may seriously overestimate effects in the field, where densities are locally high and populations are resource limited (e.g., in feces of livestock treated with ivermectin).

Animals↗
PubMed2000

Adaptive control methods for the dose individualisation of anticancer agents.

Numerous studies have found a clear relationship between systemic exposure and the toxicity or (more rarely) the efficacy of anticancer agents. Moreover, the clearance of most of these drugs differs widely between patients. These findings, combined with the narrow therapeutic index of anticancer drugs, suggest that patient outcome would be improved if doses were individualised to achieve a target systemic exposure. Bayesian maximum a posteriori probability (MAP) forecasting is an efficient and robust method for the optimisation of drug therapy, but its use for anticancer drugs is not yet extensive. The aim of this paper is to review the application of population pharmacokinetics and MAP to anticancer drugs and to evaluate whether and when MAP Bayesian estimation improves the clinical benefit of anticancer chemotherapy. For each drug, the relationships between pharmacokinetic variables [e.g. plasma concentration or the area under the concentration-time curve] and pharmacodynamic effects are described. Secondly, the methodologies employed are considered and, finally, the results are analysed in terms of predictive performance as well as, where possible, the impact on clinical end-points. Some studies were retrospective and intended only to evaluate individual pharmacokinetic parameter values using very few blood samples. Among the prospective trials, a few studied the pharmacokinetic/pharmacodynamic relationships which provided the basis for routine pharmacokinetic monitoring. Others were performed in clinical context where MAP Bayesian estimation was used to determine maximum tolerated systemic exposure (e.g. for carboplatin, topotecan, teniposide) or for pharmacokinetic monitoring (e.g. for methotrexate or platinum compounds). Indeed, its flexibility in blood sampling times makes this technique much more applicable than other limited sampling strategies. These examples demonstrate that individual dose adjustment helps manage toxicity. The performance of pharmacokinetic monitoring is linked to the methodology used at each step of its design and application. Moreover, a limitation to the use of pharmacokinetic monitoring for certain anticancer drugs has been the difficulty in obtaining pharmacokinetic or pharmacodynamic data. Recent progress in analytical methods, as well as the development of noninvasive methods (such as positron emission tomography) for evaluating the effects of chemotherapy, will help to define pharmacokinetic-pharmacodynamic relationships. Bayesian estimation is the strategy of choice for performing pharmacokinetic studies, as well as ensuring that a given patient benefits from the desired systemic exposure. Together, these methods could contribute to improving cancer chemotherapy in terms of patient outcome and survival.

Animals↗
PubMed1983

Four new haplotypes observed in Algerian beta-thalassemia patients.

beta-Thalassemia, a heterogeneous group of human anemias affecting the expression of beta-globin, is caused by a number of molecular defects. Restriction endonuclease mapping of ethnic populations has revealed many polymorphisms within and around the beta-like globin genes, combinations of which are assigned as haplotypes. Several haplotypes appear to be strongly linked with the molecular defects causing thalassemia in Greek and Italian patients (Orkin et al. 1982). We describe here haplotypes from 40 Algerian beta-thalassemic patients and eight normals determined by restriction endonuclease mapping at seven polymorphic sites. Four haplotypes previously unreported were observed in these thalassemic patients; this argues the existence in this population of undescribed beta-thalassemia alleles. The knowledge of the haplotypes in thalassemic families could be used for prenatal diagnosis of homozygote forms.

Algeria↗
PubMedDate not supplied

Pharmacogenetics and pharmacoepidemiology.

This paper seeks to stimulate consideration of the short- and long-term possibilities raised by research into pharmacogenetics and pharmacoepidemiology, to identify potential tissue databanks linked to population data, and to summarize our ethical responsibilities. Short term, we might identify selected disorders or risk factors, such as for drug-associated serious events, and might find selected target populations. Long term, we might incorporate genomics techniques into population data and map genetic risk factors for diseases and drug responses. Tissue specimens that might be linked to clinical data lie in certain data resources: clinical trials, ad hoc cohorts, case registries, and cross-sectional and longitudinal population samples. Specific areas must be addressed in research using human tissue and genetic material, including the ethical threat to privacy. We must avoid misuse of genetic information by breaching confidentiality and putting at risk specific genetically identifiable groups. The National Bioethics Advisory Commission recently addressed the issue of serum and tissue data banks in a published report summarized in this paper. Social, methodologic, and ethical issues relate to any protocol using serum and tissue, and indicate a need for broad educational efforts. We must set guidelines as pharmacogenetics research becomes a dimension of pharmacoepidemiology.

Cohort Studies↗
PubMed1995

Locus for the inducible, but not a constitutive, nitric oxide synthase cosegregates with blood pressure in the Dahl salt-sensitive rat.

Alleles of the inducible nitric oxide synthase locus (Nos2) cosegregated highly significantly (P < 0.0001) with blood pressure in an F2 population [F2(S x MNS), n = 171] derived from a cross of inbred Dahl salt-sensitive (S) rats with Milan normotensive rats (MNS). In contrast, alleles at the constitutive brain nitric oxide synthase locus (Nos1) did not cosegregate with blood pressure in several F2 populations. Nos2 was mapped on rat chromosome 10. Nine genetic markers, including the angiotensin-converting enzyme (Ace) and Nos2 loci spanning roughly 46 cM on rat chromosome 10, all cosegregated strongly with blood pressure in the F2(S x MNS) population. Nos2 showed the highest LOD score of 6.3. Ace and Nos2 are 30 cM apart. In an F2 population [F2(S x WKY), n = 159] derived from a cross of S rats with Wistar-Kyoto (WKY) rats, Nos2 alleles did (P = 0.0070), but Ace alleles did not (P = 0.91), cosegregate with blood pressure. We conclude that the Nos2 locus rather than the Nos1 locus is a candidate for influencing blood pressure in the S rat. There are probably two separate but linked quantitative trait loci (QTL) for blood pressure on rat chromosome 10, one marked by Ace and the other marked by Nos2. In F2(S x MNS) functionally variant alleles at both QTL influence blood pressure, but in F2(S x WKY) only the QTL marked by Nos2 is segregating alleles influencing blood pressure.

Amino Acid Oxidoreductases↗
PubMed1999

Homozygosity mapping to the USH2A locus in two isolated populations.

Usher syndrome is a group of autosomal recessive disorders characterised by progressive visual loss from retinitis pigmentosa and moderate to severe sensorineural hearing loss. Usher syndrome is estimated to account for 6-10% of all congenital sensorineural hearing loss. A gene locus in Usher type II (USH2) families has been assigned to a small region on chromosome 1q41 called the UHS2A locus. We have investigated two families with Usher syndrome from different isolated populations. One family is a Norwegian Saami family and the second family is from the Cayman Islands. They both come from relatively isolated populations and are inbred families suitable for linkage analysis. A lod score of 3.09 and 7.65 at zero recombination was reached respectively in the two families with two point linkage analysis to the USH2A locus on 1q41. Additional homozygosity mapping of the affected subjects concluded with a candidate region of 6.1 Mb. This region spans the previously published candidate region in USH2A. Our study emphasises that the mapped gene for USH2 is also involved in patients from other populations and will have implications for future mutation analysis once the USH2A gene is cloned.

Chromosomes, Human, Pair 1↗
PubMed2004

Seed quality QTL in a prominent soybean population.

Soybean [Glycine max (L.) Merr.] is a versatile crop due to its multitude of uses as a high protein meal and vegetable oil. Soybean seed traits such as seed protein and oil concentration and seed size are important quantitative traits. The objective of this study was to identify representative protein, oil, and seed size quantitative trait loci (QTL) in soybean. A recombinant inbred line (RIL) population consisting of 131 F6-derived lines was created from two prominent ancestors of North American soybeans ('Essex' and 'Williams') and the RILs were grown in six environments. One hundred simple sequence repeat (SSR) markers spaced throughout the genome were mapped in this population. There were a total of four protein, six oil, and seven seed size QTL found in this population. The QTL found in this study may assist breeders in marker-assisted selection (MAS) to retain current positive QTL in modern soybeans while simultaneously pyramiding additional QTL from new germplasm.

Agriculture↗
PubMed2005

Genetic approaches to studying common diseases and complex traits.

Most common diseases and most quantitative traits that can be measured in human populations are complex genetic traits. That is, many genetic and nongenetic factors interact to determine the final phenotype, whether that phenotype is susceptibility to disease, or a quantifiable trait such as height, weight, serum cholesterol, or blood pressure. Identifying the genes that underlie the population variation in these phenotypes has been challenging. Recently, databases of common genetic variants, recognition of the patterns of genetic variation, and rapid genotyping methodologies have emerged, and the combination of these tools and resources will greatly facilitate genetic association studies, a potentially powerful method to map the genes for complex traits. However, care will be required in performing and interpreting these association studies. Until genome-wide studies are feasible, choosing candidate genes will be necessary. In addition, the choice of phenotype will likely influence the success of these gene mapping efforts. Finally, population genetic methods, including searching for genes under selection, may provide clues to the location of the genes for common disease and complex traits.

Alanine↗
PubMed2006

The genetic basis of floral traits associated with mating system evolution in Leptosiphon (Polemoniaceae): an analysis of quantitative trait loci.

Mapping of quantitative trait loci (QTL) was used to investigate the genetic architecture of divergence in floral characters associated with the mating system, an important adaptive trait in angiosperms. Two species of Leptosiphon (Polemoniaceae), one strongly self-fertilizing (L. bicolor) and the other partially outcrossing (L. jepsonii), were crossed to produce F2 and both backcross progenies. For each crossing population, a linkage map was created using amplified fragment length polymorphism markers, and QTL were identified for several dimensions of floral size. For each of the five traits examined, three to seven QTL were detected, with independent datasets yielding congruent results in some but not all cases. The phenotypic effect of individual QTL was generally moderate. We estimated that many of the QTL were additive or showed dominance toward L. bicolor, whereas comparison of mean trait values for parental and cross progenies showed apparent overall dominance of L. jepsonii traits. Colocalization of QTL for different dimensions of floral size was consistent with high phenotypic correlations between floral traits. Substantial segregation distortion was observed in marker loci, the majority favoring alleles from the large-flowered parent. A low frequency of male sterility in the F2 population is consistent with the Dobzhansky-Muller model for the evolution of reproductive isolation.

Biological Evolution↗
PubMed2026

Large-scale admixture mapping in the All of Us Research Program improves the characterization of cross-population phenotypic differences.

Admixed individuals have been understudied in medical research largely due to their complex genetic ancestries. However, the consideration of admixture can identify ancestry-enriched genetic associations, delineating genetic underpinnings of cross-population phenotypic variation. Here, we performed admixture mapping in individuals with inferred admixture from African and European populations (N&#x2009;=&#x2009;48,921). Across 22 traits, we identified 71 ancestry-trait associations, including loci where ancestral haplotypes explained phenotypic variation yet were missed by single-variant association testing due to their stricter multiple testing burden. One such locus where inferred local AFR ancestries are associated with increased hemoglobin A1c (HbA1c) was 12q14.3, highlighting its potential role in explaining differences between populations. Together, our results expand upon the phenotypic differences between populations and characterize loci where genetic ancestries play a critical role in the architecture of disease.

Humans↗
PubMed2005

Mapping segregation distortion loci and quantitative trait loci for spikelet sterility in rice ( Oryza sativa L.).

Markers with segregation ratio distortion are commonly observed in data sets used for quantitative trait locus (QTL) mapping. In this study, a multipoint method of maximum likelihood (ML) was newly developed to estimate the positions and effects of the segregation distortion loci (SDLs) in two F2 populations of rice (Oryza sativa L.), i.e. Taichung65/Bhadua (TB; japonica-indica cross) and CPSLO17/W207-2 (CW; japonica-japonica). Of the four parents, W207-2 and Bhadua were found to be spikelet semi-sterile and stably inherited through selfing, and spikelet fertility segregated in the two populations. Therefore, recombination frequencies were recalculated after mapping the SDLs by using the multipoint method, and the molecular linkage maps of the two F2 populations were constructed to detect QTLs underlying spikelet fertility. As a result, five SDLs in the TB population were mapped on chromosomes 1, 3, 8 and 9, respectively. Two major QTLs underlying spikelet fertility, namely qSS-6a and qSS-8a, were detected on chromosomes 6 and 8, respectively. In the CW population, a total of 12 SDLs were detected on all 12 chromosomes except 1, 5, 7 and 11. Three QTLs underlying spikelet sterility, namely qSS-2, qSS-6b and qSS-8b on chromosomes 2, 6 and 8, were determined on the whole genome scale. Interestingly, both qSS-6a and qSS-6b, detected in the two F2 populations respectively, were located on a similar position as the S5 gene on chromosome 6; while qSS-8a and qSS-8b were also simultaneously detected on similar positions of the short arm of chromosome 8 in the two populations, which should be a new sterility gene showing the same type of zygotic selection.

Chromosome Mapping↗
PubMed2000

Spatio-temporal interaction with disease mapping.

Markov chain Monte Carlo methods are used to estimate mortality rates under a Bayesian hierarchical model. Spatial correlations are introduced to examine spatial effects relative to both regional and regional changes over time by groups. A special feature of the models is the inclusion of longitudinal variables which will describe temporal trends in mortality or incidences for different population groups. Disease maps are used to illustrate the role of different parameters in the model and pinpointing areas of interesting patterns. The methods are demonstrated by male cancer mortality data from the state of Missouri during 1973-1992. Of special interest will be the geographic variations in the trend of lung cancer mortality over the recent past. Marginal posterior distributions are used to examine effects due to spatial correlations and age difference in temporal trends. Numerical results from the Missouri data show that although spatial correlations exist, they do not have a large effect on the estimated mortality rates.

Aged↗
PubMed1997

Distribution of dystrophin gene deletions mapped by multiplex PCR in the Moravian population.

Twenty two Duchenne muscular dystrophy (DMD) patients from the province of Moravia, Czech Republic, were tested for the presence of dystrophin gene rearrangements using multiplex polymerase chain reaction (PCR). Using primer pairs for amplification of two promoter regions and 27 exons, 11 patients were found positive for deletions spanning one or more exons. In all these cases, the deletions affected the distal part of the dystrophin gene, beginning from exon 44 but not reaching exon 60.

Cytoskeletal Proteins↗
PubMed1974

The utility of photo-affinity labels as "mapping" reagents. A study of sub-populations of a specific rabbit antibody by using structurally related photo-affinity reagents.

A specific rabbit antibody against the 4-azido-2-nitrophenyl determinant was photo-labelled by the homologous hapten epsilon-(4-azido-2-nitrophenyl)-l-lysine, and by the close structural isomer epsilon-(5-azido-2-nitrophenyl)-l-lysine. The extents of covalent labelling of the antibody-binding site were assessed by using radioactive haptens and exhaustive displacement dialysis, which leaves the unlabelled sites empty but largely intact. A single photolysis of hapten-antibody complex suffices to label those sites that are capable of being labelled. Although there is considerable overlap among sub-populations of antibody that will bind the two haptens non-covalently, sites that can be covalently labelled by one reagent cannot be labelled by the other.

Animals↗