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Biomedical subjects

L A Dixon

Publications and source records attributed to L A Dixon.

5 recordsLinked to original sources
PubMed2005

Analysis of artificially degraded DNA using STRs and SNPs--results of a collaborative European (EDNAP) exercise.

Recently, there has been much debate about what kinds of genetic markers should be implemented as new core loci that constitute national DNA databases. The choices lie between conventional STRs, ranging in size from 100 to 450 bp; mini-STRs, with amplicon sizes less than 200 bp; and single nucleotide polymorphisms (SNPs). There is general agreement by the European DNA Profiling Group (EDNAP) and the European Network of Forensic Science Institutes (ENFSI) that the reason to implement new markers is to increase the chance of amplifying highly degraded DNA rather than to increase the discriminating power of the current techniques. A collaborative study between nine European and US laboratories was organised under the auspices of EDNAP. Each laboratory was supplied with a SNP multiplex kit (Foren-SNPs) provided by the Forensic Science Service, two mini-STR kits provided by the National Institute of Standards and Technology (NIST) and a set of degraded DNA stains (blood and saliva). Laboratories tested all three multiplex kits, along with their own existing DNA profiling technique, on the same sets of degraded samples. Results were collated and analysed and, in general, mini-STR systems were shown to be the most effective. Accordingly, the EDNAP and ENFSI working groups have recommended that existing STR loci are reengineered to provide smaller amplicons, and the adoption of three new European core loci has been agreed.

Analysis of Variance↗
PubMed2005

Validation of a 21-locus autosomal SNP multiplex for forensic identification purposes.

A single nucleotide polymorphism (SNP) multiplex has been developed to analyse highly degraded and low copy number (LCN) DNA template, i.e. <100 pg, for scenarios including mass disaster identification. The multiplex consists of 20 autosomal non-coding loci plus Amelogenin for sex determination, amplified in a single tube PCR reaction and visualised on the Applied Biosystems 3100 capillary electrophoresis (CE) system. Allele-specific primers tailed with shared universal tag sequences were designed to speed multiplex design and balance the amplification efficiencies of all loci through the use of a single reverse and two differentially labelled allele denoting forward universal primers. As the multiplex is intended for use with samples too degraded for conventional profiling, a computer program was specifically developed to aid interpretation. Critical factors taken into account by the software include empirically determined extremes of heterozygous imbalance (Hb) and the drop-out threshold (Ht) defined as the maximum peak height of a surviving heterozygous allele, where its partner may have dropped out. The discrimination power of the system is estimated at 1 in 4.5 million, using a White Caucasian population database. Comparisons using artificially degraded samples profiled with both the SNP multiplex and AMPFISTR SGM plus (Applied Biosystems) demonstrated a greater likelihood of obtaining a profile using SNPs for certain sample types. Saliva stains degraded for 147 days generated an 81% complete SNP profile whilst short tandem repeats (STRs) were only 18% complete; similarly blood degraded for 243 days produced full SNP profiles but only 9% with STRs. Reproducibility studies showed concordance between SNP profiles for different sample types, such as blood, saliva, semen and hairs, for the same individual, both within and between different DNA extracts.

Amelogenin↗
PubMed1998

Two routes to privacy protection: a comparison of health information legislation in Canada and the United States.

The privacy of health information is a subject of great sensitivity in both Canada and the United States. As a result of public demands for more effective protection of such information as medical records, Canada and, particularly, its provincial governments, have implemented extensive legislation. The United States, on the other hand, has largely confined its efforts to private sector initiatives that are more reflective of voluntary codes than legal statutes. Because new technologic developments facilitate data sharing in the medical field, especially in the face of a continual reduction of healthcare budgets, the concern for privacy protection in this domain has intensified. Correspondingly, there has been a gradual theoretical shift in protective health information policies on both sides of the border. As Canada pushes to extend its federal and provincial legislation to the private sector, the United States is on the brink of approving a national bill that would protect the privacy of personal medical records. It is becoming evident that efforts to secure the privacy of health information in both countries are converging.

Canada↗
PubMed1986

Postpartum moods in men and women.

Twenty-one married couples, recruited from childbirth classes (mean age 29.6 years), were administered questionnaires measuring 20 different moods during the third trimester of pregnancy (prepartum period), during the postpartum period, and at 6 months after birth (follow-up period). In each questionnaire period individual questionnaires were filled out daily by both the mother and father for 10 consecutive days. The results indicated that the postpartum period, compared with the prepartum and follow-up periods, is an emotionally unique time but not a period marked by depression. The moods that were rated as being experienced more strongly by men and women during the postpartum period were associated with anxiety and concern for one's ability to cope such as "nervousness," "worried," "helpless," and "anxious" or positive emotions such as "enthusiastic" and "happy." It is concluded that men and women in this sample tend to experience the postpartum period in an emotionally similar way.

Adult↗