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Biomedical subjects

K J Leonard

Publications and source records attributed to K J Leonard.

10 recordsLinked to original sources
PubMed2005

Quantitative trait loci for partial resistance to crown rust, Puccinia coronata, in cultivated oat, Avena sativa L.

To facilitate the detection of quantitative trait loci (QTLs) for partial resistance to oat crown rust, Puccinia coronata f. sp. avenae Eriks., a genetic map was generated in a population of 158 F(6)-derived oat recombinant inbred lines from a cross of a partial resistance line MN841801-1 by a susceptible cultivar selection 'Noble-2'. The map, developed using 230 marker loci, mostly restriction fragment length polymorphism and amplified fragment length polymorphism markers, spanned 1,509 cM (Haldane) arranged into 30 linkage groups of 2-18 markers each. Four consistently detected major QTLs for partial rust resistance, Prq1a, Prq1b, Prq2, and Prq7, and three minor QTLs, Prq3, Prq5, and Prq6, were found in tests involving three field and two greenhouse environments. In addition, two major QTLs for flowering time, Ftq1 and Ftq7, and five weaker QTLs, Ftq2, Ftq3, Ftq4, Ftq5, and Ftq6, were revealed. Overlapping of the map segments of Ftq1 and Prq1 and of Ftq7 and Prq7 suggested either linkage between the flowering time QTLs and resistance QTLs or a pleiotropic effect of the Ftq QTLs on rust resistance. Relatively low heritability estimates (0.30) obtained for partial resistance to crown rust in the field indicate a potential value for marker-assisted selection.

Avena↗
PubMed2005

Similarity coefficients for molecular markers in studies of genetic relationships between individuals for haploid, diploid, and polyploid species.

Determining true genetic dissimilarity between individuals is an important and decisive point for clustering and analysing diversity within and among populations, because different dissimilarity indices may yield conflicting outcomes. We show that there are no acceptable universal approaches to assessing the dissimilarity between individuals with molecular markers. Different measures are relevant to dominant and codominant DNA markers depending on the ploidy of organisms. The Dice coefficient is the suitable measure for haploids with codominant markers and it can be applied directly to (0,1)-vectors representing banding profiles of individuals. None of the common measures, Dice, Jaccard, simple mismatch coefficient (or the squared Euclidean distance), is appropriate for diploids with codominant markers. By transforming multiallelic banding patterns at each locus into the corresponding homozygous or heterozygous states, a new measure of dissimilarity within locus was developed and expanded to assess dissimilarity between multilocus states of two individuals by averaging across all codominant loci tested. There is no rigorous well-founded solution in the case of dominant markers. The simple mismatch coefficient is the most suitable measure of dissimilarity between banding patterns of closely related haploid forms. For distantly related haploid individuals, the Jaccard dissimilarity is recommended. In general, no suitable method for measuring genetic dissimilarity between diploids with dominant markers can be proposed. Banding patterns of diploids with dominant markers and polyploids with codominant markers represent individuals' phenotypes rather than genotypes. All dissimilarity measures proposed and developed herein are metrics.

Genetic Markers↗
PubMed2000

The adoption of distance education technology in a master of health administration (MHA/MHSc) curriculum: anecdotes and antidotes.

In the fall of 1997, a team of faculty members from the Department of Health Administration (University of Toronto) began work on the introduction of Distance Education Technology (DET) into the MHA/MHSc course curriculum. This paper describes the almost three-year process from original discussion through to full implementation across the entire first year course curriculum by the fall semester of 1999. In fact, the final course assignment in one of the courses was to write a paper critiquing DET, outlining both the good and bad components. Consequently, we conclude with a detailed student evaluation of the advantages and drawbacks of such technology.

Antidotes↗
PubMed1998

The use of computer-based simulation in a Master of Health Administration curriculum.

In this paper, the use of a simulation tool to support the appreciation of data and information by health administration students with varied backgrounds and educational training is discussed. Specifically, the authors developed educational and training material that can be used in a variety of courses to improve information management and decision making. Improved information management is being recognized as a critical component of the movement to achieve consistent quality in patient care, institutional performance, and policy planning. This is now especially important as new information systems are making data and good quality evidence increasingly more available. Ultimately, it is hoped that this process will lead to findings that will assist evidence-based decision making within all health providers.

Computer Simulation↗
PubMed1998

Total quality in information systems management: issues for the health care industry.

Faced with rising costs, growing demand and declining funding, hospitals and others must either cut services or improve the efficiency and effectiveness of what they do. Neither solution can be implemented without adequate relevant information. Without understanding which services are providing the most value to its customers, sensible cutbacks will be difficult to make. Improving efficiency requires a knowledge of where there are inefficiencies, and improving effectiveness requires an understanding of what the outcomes of health care are. The solution, as many have documented, is to create, as a first step, a database containing detailed health care patient data. In this paper, we present continuous improvement techniques as a requirement for the design and development of this much needed database.

Computer Security↗
PubMed1996

Staff security and work pressure: contrasting patterns of stability and change across five dialysis units.

Differences among clinical care units in social dynamics and social organization are associated with differences in the clinical course of patients with a range of chronic illness. These differences are also associated with well-being of staff members. Recent attention has focused on understanding these differences among units with an eye towards correcting deficiencies and enhancing strengths of clinical care units. The current study sought to delineate the effect of social and organizational dynamics unique to each unit on staff perceptions of the security of their relationships with other staff and their perceived work pressure. The unit as a major source of differences among staff subjects was compared with the impact of ethnic identity, of work in the morning shift vs other shifts, and of professional role. Results confirmed that unit membership was, by far, the most important correlate of staff perceptions of the unit, particularly those concerning security of relationships with others and perceived work pressure. Moreover, the results suggested that unit differences in perceived security were due to differences among units in long standing turmoil within the unit or long standing problematic ties between the unit and the larger institution which controls it. However, perceived work pressure seems more transient and may reflect the challenge of shorter-term fluctuations in the demands of patient care.

Adult↗
PubMed1987

Site selectivity of fluorescent bisquaternary phenanthridinium ligands for acetylcholinesterase.

The synthesis of decidium and hexidium diiodides, their spectroscopic properties, and association with acetylcholinesterase from Torpedo californica are described and compared with those for propidium. Decidium, hexidium, and propidium, bisquaternary analogs of the fluorescent phenanthridinium ligand ethidium, contain 10, 6, and 3 methylene carbons, respectively, interposed between the exocyclic and endocyclic quaternary nitrogens. The three ligands exhibit linear competitive inhibition of enzyme carbamylation by N-methyl-7-dimethylcarbamoxyquinolinium. Dissociation constants for decidium, hexidium, and propidium are found by direct fluorescence titration to be 2.1 +/- 0.2 X 10(-8), 5.8 +/- 1.4 X 10(-7), and 3.7 +/- 0.4 X 10(-6) M, values in close accord with the inhibition constants obtained from kinetic analyses. Association of the three ligands is characterized by a stoichiometry of one fluorescent ligand per 80-kDa molecular weight subunit and occurs with respective 6.5-, 4.5-, and 3-fold increases in both quantum yield and fluorescence lifetime. Decidium and hexidium, in marked contrast with propidium, are dissociated by ligands selective for the active center and undergo pronounced reduction in affinity upon modification of the active center with pyrenebutyl methylphosphonofluoridate. Whereas the kinetics reveal no clear distinctions in inhibitory action of the three ligands, the fluorescence studies indicate that the alkyltrimethylammonium moiety of decidium and hexidium occludes the active center; propidium, in contrast, associates solely with the peripheral anionic site and does not occlude the active center. The temperature dependence of binding indicates that decidium association engenders a substantial increase (+55 eu) in entropy. The data indicate that the active center and peripheral anionic sites are separated by a crevice which can accommodate the hydrocarbon portion of extended n-alkyl cationic ligands, thereby affording entropic stabilization of complex formation. This stabilization is realized, however, only when the anionic subsite of the active center is not occluded, enabling electrostatic interaction between cationic ligand and the anionic active center.

Acetylcholinesterase↗