Biomedical subjects

H Andréasson

Publications and source records attributed to H Andréasson.

4 recordsLinked to original sources

PubMed2006

Quantification of mtDNA mixtures in forensic evidence material using pyrosequencing.

Analysis of mtDNA variation using Sanger sequencing does not allow accurate quantification of the components of mtDNA mixtures. An alternative method to determine the specific mixture ratios in samples displaying hetero-plasma, consisting of DNA contributions from several individuals, or containing contamination would therefore be valuable. A novel quantification system for mtDNA mixture analysis has been developed based on pyrosequencing technology, in which the linear relationship between incorporated nucleotides and released light allows quantification of the components of a sample. Within five polymerase chain reaction fragments, seven variable positions in the mtDNA control and coding region were evaluated using this quantification analysis. For all single nucleotide polymorphisms quantified in this study, a linear relationship was observed between the measured and expected mixture ratios. This mtDNA quantification assay is an easy to use, fast and accurate quantification system, with the ability to resolve and interpret major and minor mtDNA components in forensic mixture samples.

DNA Fingerprinting↗

PubMed2006

Nuclear and mitochondrial DNA quantification of various forensic materials.

Due to the different types and quality of forensic evidence materials, their DNA content can vary substantially, and particularly low quantities can impact the results in an identification analysis. In this study, the quantity of mitochondrial and nuclear DNA was determined in a variety of materials using a previously described real-time PCR method. DNA quantification in the roots and distal sections of plucked and shed head hairs revealed large variations in DNA content particularly between the root and the shaft of plucked hairs. Also large intra- and inter-individual variations were found among hairs. In addition, DNA content was estimated in samples collected from fingerprints and accessories. The quantification of DNA on various items also displayed large variations, with some materials containing large amounts of nuclear DNA while no detectable nuclear DNA and only limited amounts of mitochondrial DNA were seen in others. Using this sensitive real-time PCR quantification assay, a better understanding was obtained regarding DNA content and variation in commonly analysed forensic evidence materials and this may guide the forensic scientist as to the best molecular biology approach for analysing various forensic evidence materials.

DNA Fingerprinting↗

PubMed2002

Mitochondrial sequence analysis for forensic identification using pyrosequencing technology.

Over recent years, requests for mtDNA analysis in the field of forensic medicine have notably increased, and the results of such analyses have proved to be very useful in forensic cases where nuclear DNA analysis cannot be performed. Traditionally, mtDNA has been analyzed by DNA sequencing of the two hypervariable regions, HVI and HVII, in the D-loop. DNA sequence analysis using the conventional Sanger sequencing is very robust but time consuming and labor intensive. By contrast, mtDNA analysis based on the pyrosequencing technology provides fast and accurate results from the human mtDNA present in many types of evidence materials in forensic casework. The assay has been developed to determine polymorphic sites in the mitochondrial D-loop as well as the coding region to further increase the discrimination power of mtDNA analysis. The pyrosequencing technology for analysis of mtDNA polymorphisms has been tested with regard to sensitivity, reproducibility, and success rate when applied to control samples and actual casework materials. The results show that the method is very accurate and sensitive; the results are easily interpreted and provide a high success rate on casework samples. The panel of pyrosequencing reactions for the mtDNA polymorphisms were chosen to result in an optimal discrimination power in relation to the number of bases determined.

Base Sequence↗

PubMed1999

External pedicular fixation of the lumbar spine: outcome evaluation by functional tests.

We analyzed the pain-relieving effect and the functional outcome during external pedicular fixation of the lumbar spine. Twenty patients were included, and the diagnoses were disc degeneration with or without facet joint arthrosis in eight patients, pain after decompression in six patients, spondylolysis/olisthesis in two patients, other types of lumbar anomalies in three patients, and pseudarthrosis after prior uninstrumented fusion in one patient. Before application of the external frame, the pain level on the Visual Analogue Scale was registered at rest, as a mean level for the preceding week, and at seven different functional tests. Maximum walking capacity and walking time needed for a standardized distance were also measured. The same test procedure was repeated 1 week postoperatively with the external frame applied in locked position. With stabilization, 11 patients reported pain relief at rest and 14 when approximating the mean pain level for the week. Both these measured levels correlated to the pain level at all of the seven functional tests. Thus, the patients selected for a subsequent fusion based on pain relief during extended functional provocation would not differ from the patients selected by using only the pain-relieving effect at rest. The patients reporting pain relief tended to increase their walking distance (p = 0.06, t test) but not the speed of walking.

Adult↗