Study environment and the incidence of mental health problems and activity-limiting musculoskeletal problems among university students: the SUN cohort study.

OBJECTIVE: To determine the association between different aspects of study environment and the incidence of mental health problems and activity-limiting musculoskeletal problems. DESIGN, SETTING AND PARTICIPANTS: We recruited a cohort of 4262 Swedish university students of whom 2503 (59%) were without moderate or worse mental health problems and 2871 (67%) without activity-limiting musculoskeletal problems at baseline. The participants were followed at five time points over 1 year using web surveys. EXPOSURES: Self-rated discrimination, high study pace, low social cohesion and poor physical environment measured at baseline. OUTCOMES: Self-rated mental health problems defined as scoring above cut-off on any of the subscales of the Depression, Anxiety and Stress Scale. Self-rated activity-limiting musculoskeletal problems in any body location assessed by the Nordic Musculoskeletal Questionnaire. STATISTICAL ANALYSIS: Discrete survival-time analysis was used to estimate the hazard rate ratio (HR) of each exposure-outcome combination while adjusting for gender, age, living situation, education type, year of studies, place of birth and parental education as potential confounders. RESULTS: For discrimination, adjusted HRs were 1.75 (95% CI 1.40 to 2.19) for mental health problems and 1.39 (95% CI 1.12 to 1.72) for activity-limiting musculoskeletal problems. For high study pace, adjusted HRs were 1.70 (95% CI 1.48 to 1.94) for mental health problems and 1.25 (95% CI 1.09 to 1.43) for activity-limiting musculoskeletal problems. For low social cohesion, adjusted HRs were 1.51 (95% CI 1.29 to 1.77) for mental health problems and 1.08 (95% CI 0.93 to 1.25) for activity-limiting musculoskeletal problems. For perceived poor physical study environment, adjusted HRs were 1.20 (95% CI 0.99 to 1.45) for mental health problems and 1.20 (95% CI 1.01 to 1.43) for activity-limiting musculoskeletal problems. CONCLUSIONS: Several aspects of the study environment were associated with the incidence of mental health problems and activity-limiting musculoskeletal problems in this sample of Swedish university students.

Forensic mitochondrial coding region analysis for increased discrimination using pyrosequencing technology.

Analysis of mitochondrial DNA (mtDNA) is very useful when nuclear DNA analysis fails due to degradation or insufficient amounts of DNA in forensic analysis. However, mtDNA analysis has a lower discrimination power compared to what can be obtained by nuclear DNA (nDNA) analysis, potentially resulting in multiple individuals showing identical mtDNA types in the HVI/HVII region. In this study, the increase in discrimination by analysis of mitochondrial coding regions has been evaluated for identical or similar HVI/HVII sequences. A pyrosequencing-based system for coding region analysis, comprising 17 pyrosequencing reactions performed on 15 PCR fragments, was utilised. This assay was evaluated in 135 samples, resulting in an average read length of 81 nucleotides in the pyrosequencing analysis. In the sample set, a total of 52 coding region SNPs were identified, of which 18 were singletons. In a group of 60 samples with 0 or 1 control region difference from the revised Cambridge reference sequence (rCRS), only 12 samples could not be resolved by at least two differences using the pyrosequencing assay. Thus, the use of this pyrosequencing-based coding region assay has the potential to substantially increase the discriminatory power of mtDNA analysis.

Mitochondrial D-loop and coding sequence analysis using pyrosequencing.

In forensic casework analysis, mitochondrial deoxyribonucleic acid (DNA) often is used when the evidence material contains scarce amounts of DNA. Here, a mitochondrial DNA typing system for D-loop and coding region analysis based on pyrosequencing is described. Pyrosequencing is a real-time, single-tube sequencing-by-synthesis method, in which a cascade of enzymatic reactions yields detectable light. This pyrosequencing system has a higher resolution than the D-loop analysis performed routinely today as it also covers informative positions in the mitochondrial coding region. The system is composed of 16 polymerase chain reaction (PCR) fragments and 24 pyrosequencing reactions with a turn around time for a 96-well plate of less than 3 h after PCR.

Rapid quantification and sex determination of forensic evidence materials.

DNA quantification of forensic evidence is very valuable for an optimal use of the available biological material. Moreover, sex determination is of great importance as additional information in criminal investigations as well as in identification of missing persons, no suspect cases, and ancient DNA studies. While routine forensic DNA analysis based on short tandem repeat markers includes a marker for sex determination, analysis of samples containing scarce amounts of DNA is often based on mitochondrial DNA, and sex determination is not performed. In order to allow quantification and simultaneous sex determination on minute amounts of DNA, an assay based on real-time PCR analysis of a marker within the human amelogenin gene has been developed. The sex determination is based on melting curve analysis, while an externally standardized kinetic analysis allows quantification of the nuclear DNA copy number in the sample. This real-time DNA quantification assay has proven to be highly sensitive, enabling quantification of single DNA copies. Although certain limitations were apparent, the system is a rapid, cost-effective, and flexible assay for analysis of forensic casework samples.

Real-time DNA quantification of nuclear and mitochondrial DNA in forensic analysis.

The rapid development of molecular genetic analysis tools has made it possible to analyze most biological materialfound at the scene of a crime. Evidence materials containing DNA quantities too low to be analyzed using nuclear markers can be analyzed using the highly abundant mtDNA. However, there is a shortage of sensitive nDNA and mtDNA quantification assays. In this study, an assay for the quantification of very small amounts of DNA, based on the real-time Taq-Man assay, has been developed. This analysis will provide an estimate of the total number of nDNA copies and the total number of mtDNA molecules in a particular evidence material. The quantification is easy to perform, fast, and requires a minimum of the valuable DNA extracted from the evidence materiaL The results will aid in the evaluation of whether the specific sample is suitable for nDNA or mtDNA analysis. Furthermore, the optimal amount of DNA to be used in further analysis can be estimated ensuring that the analysis is successful and that the DNA is retained for future independent analysis. This assay has significant advantages over existing techniques because of its high sensitivity, accuracy, and the combined analysis of nDNA and mtDNA. Moreover, it has the potential to provide additional information about the presence of inhibitors in forensic samples. Subsequent mitochondrial and nuclear analysis of quantified samples illustrated the potential to predict the number of DNA copies required for a successful analysis in a certain typing assay.