Prediction model for anabolic androgenic steroid positivity in forensic autopsy cases - a new tool to the autopsy room

Non-prescription use of anabolic androgenic steroids (AAS) is associated with an increased risk of premature death. However, these substances are seldom screened in connection with forensic cause-of-death investigation, unless the forensic pathologist specifically suspects use, often based on a positive AAS use history. Since AAS use is often concealed from others, this practice may lead to mistargeting of these analyses and significant underestimation of the true number of AAS positive cases undergoing forensic autopsy. Thus, more accurate diagnostic tools are needed to identify these cases. The main objective of this study was to determine, whether a multivariable model could predict AAS urine assay positivity in forensic autopsies. We analyzed retrospectively the autopsy reports of all cases that had been screened for AAS during forensic cause-of-death investigation between 2016-2019 at the Finnish Institute for Health and Welfare forensic units (n = 46). Binary logistic regression with penalized maximum likelihood estimation was used to generate a nine-variable model combining circumferential and macroscopic autopsy-derived variables. The multivariable model predicted AAS assay positivity significantly better than a "conventional" model with anamnestic information about AAS use only (area under the receiver operating characteristic curve [AUC] = 0.968 vs. 0.802, p = 0.005). Temporal validation was conducted in an independent sample of AAS screened cases between 2020-2022 (n = 31), where the superiority of the multivariable model was replicated (AUC = 0.856 vs. 0.644, p = 0.004). Based on the model, a calculator predicting AAS assay positivity is released as a decision-aiding tool for forensic pathologists working in the autopsy room.

Association of anabolic androgenic steroid use with perimortem polypharmacy, antemortem prescription drug use, and utilization of health care services - A Finnish triple register study of forensic autopsy cases

Anabolic androgenic steroid (AAS) use has previously been associated with complex polysubstance use that may increase morbidity and mortality among these individuals. In this study we aimed to further describe the features of perimortem polysubstance use, antemortem central nervous system (CNS) drug use and health care service utilization of AAS using males that suffer premature death. The main sample included all cases that were screened for AAS in connection with forensic autopsy between 2016-2019 and tested positive (n = 16). The control samples included autopsy cases that were screened for AAS but tested negative (n = 30) and randomly selected, age and sex matched autopsy cases not suspected of having used AAS but were otherwise fully toxicologically investigated (n = 43). Postmortem toxicological results were used for perimortem polysubstance use prevalence and severity estimation. Antemortem CNS drug use was calculated from a national register of reimbursed prescription medicines, and health care utilization from public health care registers, covering the last five years of life. Perimortem polysubstance use was prevalent in all groups, but the AAS positive had a tendency for greater CNS drug polypharmacy and the highest number of antemortem CNS drug purchases during the last five years of life, with a median of 14.5 purchases/person, vs. 1/person in the AAS negative and 0/person in the random group (Kruskal-Wallis H test, p < .001). Yearly medical contacts increased in all groups as death approached. Our findings suggest that prescription CNS drug use may play a significant role in polysubstance use disorders of AAS using males that suffer premature death.

Glucose metabolism in completed suicide: a forensic-pathological pilot study

Aim

To determine whether antemortem blood levels of glycated hemoglobin (HbA_1c) and glucose predict completed suicide and, by extension, whether markers of glucose metabolism might be associated with a prosuicidal trait or state.

Method

From consecutively performed autopsies, samples of blood and vitreous humor from 17 suicide victims and 27 non-suicide controls were compared with regard to levels of glucose, lactate, and HbA_1c.

Results

Mean HbA1c was higher and mean estimated blood glucose was lower among suicide victims, although tests revealed no significant differences (P = 0.171 and P = 0.395, respectively). HbA1c levels exceeding 48.0 mmol/mol, which were indicative of persistent hyperglycemia, were twice as common in suicide victims (59% vs 30%; P = 0.068).

Conclusion

The finding of this pilot study suggest that deranged glucose metabolism may reflect biological events antecedent to, or concomitant with, completed suicide, with the following clinical implications: recurring hyperglycemia due to defective glucose transport, which may give rise to depression and suicidal ideation, and elevated HbA_1c levels, which may represent an assayable correlate to neurobiological conditions predisposing to suicide.

The usefulness of point-of-care (POC) tests in screening elevated glucose and ketone body levels postmortem

The aim was to evaluate the performance of point-of-care (POC) tests in detecting glucose and ketone bodies in postmortem (PM) samples and to assess the usefulness of POC tests in sample screening for more precise analyses. Glucose and ketone body, β-hydroxybutyrate (BHB), were measured from vitreous humor (VH) in 52 autopsy cases with a POC blood glucose monitoring device (BGMD). In addition glucose and ketone bodies, acetone (Ac) and acetoacetate (AcAc), were measured from urine samples in another set of 59 cases with semi-quantitative stick tests. The results were compared to the concentration in VH measured with validated methods (values ≥ 7mmol/l indicate possible hyperglycemia and total ketone body levels ≥ 3mmol/l ketoacidosis). The sensitivity for glucose with the BGMD was 1.0 and specificity 0.94 when the threshold value for the meter to predict elevated glucose was set to ≥ 10mmol/l. The correlation between the BGMD and the validated method was strong (R(2)=0.89). For detecting ketoacidosis, the BGMD had a sensitivity of 1.0 and specificity of 0.73, when the threshold value was set to 2.5mmol/l. The urine stick test presented a sensitivity of 0.89 and specificity of 0.90 for detecting elevated VH glucose concentration. The sensitivity and specificity for the stick test to detect cases with possible ketoacidosis were 0.84 and 0.68, respectively. According to the results, BGMD can be reliably applied for sample screening, although more samples need to be analyzed for delineating the correct threshold values. In the case of glucose, the urine stick tests could be indicative in detecting cases with VH glucose ≥ 10mmol/l. For predicting possible ketoacidosis with elevated VH total ketone bodies, the stick test is not reliable as the test presented both false-positive and -negative results.

Measuring postmortem glycated hemoglobin - A comparison of three methods

Glycated hemoglobin (HbA1c) is a glycoprotein formed as a result of the non-enzymatic addition of d-glucose to the hemoglobin β-chain. The amount of HbA1c in the blood is dependent on mean glucose levels present during the 1-2 months preceding measurement, and it is an indicator of long-term glycemic levels. HbA1c is a useful marker in postmortem biochemistry in determining cause of death in acetonemic cases by allowing to distinguish diabetic ketoacidosis (DKA) from starvation or alcoholic ketoacidosis (AKA) and intoxication by acetone or isopropanol. We evaluated three methods for postmortem HbA1c measurement: Mono S cation exchange HPLC, affinity chromatography using point-of-care analyzer and a direct enzymatic method by. Additionally, optimization of sample storage and preservatives was performed and interpretation of the results in autopsy cases is discussed. Our results indicate that the HbA1c levels of postmortem samples can be reliably measured with Mono S HPLC. EDTA is the preferable preservative, as samples can be measured after as long as 4 weeks storage at +4°C. Our study shows that HbA1c analysis is a valuable tool alongside glucose and ketone body analysis in determining the metabolic state of deceased persons in medicolegal autopsies.

Amount of introgression in flycatcher hybrid zones reflects regional differences in pre and post-zygotic barriers to gene exchange

Introgression is the incorporation of alleles from one species or semispecies into the gene pool of another through hybridization and backcrossing. The rate at which this occurs depends on the frequency of hybridization and the fitness of hybrids and backcrosses compared to 'pure' individuals. The collared flycatcher (Ficedula albicollis) and the pied flycatcher (F. hypoleuca) co-exist and hybridize at low to moderate frequencies in a clinal hybrid zone in Central Europe and on the islands of Gotland and Oland off the Swedish east coast. Data on hatching success suggest that hybrids are less fertile in Central Europe compared to on the islands. Direct fitness estimates using molecular markers to infer paternity are consistent with the demographic data. Applying a tag-array-based minisequencing assay to genotype interspecific substitutions and single nucleotide polymorphisms we demonstrate that the amount of introgression from the pied to the collared flycatcher is higher in the two island populations (Gotland and Oland) than in two geographically distinct areas from the Central European hybrid zone (Czech Republic and Hungary). In all areas the amount of introgression from collared to pied flycatchers is very low or seemingly absent. The different patterns of introgression are consistent with regional differences in rates of hybridization and fitness of hybrids. We suggest that barriers to gene exchange may have been partly broken down on the islands due to asymmetric gene flow from allopatry. Alternatively, or in addition, more pronounced reinforcement of prezygotic isolation in Central Europe might have increased post-zygotic isolation through hitchhiking, since genes affecting pre and post-zygotic isolation are both sex-linked in these birds. One of our genetic markers appears to introgress from pied to collared flycatchers at a much higher rate than the other markers. We discuss the possibility that the introgressed marker may be linked to a gene which is under positive selection in the novel genetic background.

Polymorphisms in the tyrosine kinase 2 and interferon regulatory factor 5 genes are associated with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease caused by both genetic and environmental factors. Genome scans in families with SLE point to multiple potential chromosomal regions that harbor SLE susceptibility genes, and association studies in different populations have suggested several susceptibility alleles for SLE. Increased production of type I interferon (IFN) and expression of IFN-inducible genes is commonly observed in SLE and may be pivotal in the molecular pathogenesis of the disease. We analyzed 44 single-nucleotide polymorphisms (SNPs) in 13 genes from the type I IFN pathway in 679 Swedish, Finnish, and Icelandic patients with SLE, in 798 unaffected family members, and in 438 unrelated control individuals for joint linkage and association with SLE. In two of the genes--the tyrosine kinase 2 (TYK2) and IFN regulatory factor 5 (IRF5) genes--we identified SNPs that displayed strong signals in joint analysis of linkage and association (unadjusted P<10(-7)) with SLE. TYK2 binds to the type I IFN receptor complex and IRF5 is a regulator of type I IFN gene expression. Thus, our results support a disease mechanism in SLE that involves key components of the type I IFN system.

Sex chromosome evolution and speciation in Ficedula flycatchers

Speciation is the combination of evolutionary processes that leads to the reproductive isolation of different populations. We investigate the significance of sex-chromosome evolution on the development of post- and prezygotic isolation in two naturally hybridizing Ficedula flycatcher species. Applying a tag-array-based mini-sequencing assay to genotype single nucleotide polymorphisms (SNPs) and interspecific substitutions, we demonstrate rather extensive hybridization and backcrossing in sympatry. However, gene flow across the partial postzygotic barrier (introgression) is almost exclusively restricted to autosomal loci, suggesting strong selection against introgression of sex-linked genes. In addition to this partial postzygotic barrier, character displacement of male plumage characteristics has previously been shown to reinforce prezygotic isolation in these birds. We show that male plumage traits involved in reinforcing prezygotic isolation are sex linked. These results suggest a major role of sex-chromosome evolution in mediating post- and prezygotic barriers to gene flow and point to a causal link in the development of the two forms of reproductive isolation.

Multiplex SNP genotyping in pooled DNA samples by a four-colour microarray system

We selected 125 candidate single nucleotide polymorphisms (SNPs) in genes belonging to the human type 1 interferon (IFN) gene family and the genes coding for proteins in the main type 1 IFN signalling pathway by screening databases and by in silico comparison of DNA sequences. Using quantitative analysis of pooled DNA samples by solid-phase mini-sequencing, we found that only 20% of the candidate SNPs were polymorphic in the Finnish and Swedish populations. To allow more effective validation of candidate SNPs, we developed a four-colour microarray-based mini-sequencing assay for multiplex, quantitative allele frequency determination in pooled DNA samples. We used cyclic mini-sequencing reactions with primers carrying 5'-tag sequences, followed by capture of the products on microarrays by hybridisation to complementary tag oligonucleotides. Standard curves prepared from mixtures of known amounts of SNP alleles demonstrate the applicability of the system to quantitative analysis, and showed that for about half of the tested SNPs the limit of detection for the minority allele was below 5%. The microarray-based genotyping system established here is universally applicable for genotyping and quantification of any SNP, and the validated system for SNPs in type 1 IFN-related genes should find many applications in genetic studies of this important immunoregulatory pathway.

Minisequencing on oligonucleotide microarrays: comparison of immobilisation chemistries

In the microarray format of the minisequencing method multiple oligonucleotide primers immobilised on a glass surface are extended with fluorescent ddNTPs using a DNA polymerase. The method is a promising tool for large-scale single nucleotide polymorphism (SNP) detection. We have compared eight chemical methods for covalent immobilisation of the oligonucleotide primers on glass surfaces. We included both commercially available, activated slides and slides that were modified by ourselves. In the comparison the differently derivatised glass slides were evaluated with respect to background fluorescence, efficiency of attaching oligonucleotides and performance of the primer arrays in minisequencing reactions. We found that there are significant differences in background fluorescence levels among the different coatings, and that the attachment efficiency, which was measured indirectly using extension by terminal transferase, varied largely depending on which immobilisation strategy was used. We also found that the attachment chemistry affects the genotyping accuracy, when minisequencing on microarrays is used as the genotyping method. The best genotyping results were observed using mercaptosilane-coated slides attaching disulfide-modified oligonucleotides.

Y-chromosomal SNPs in Finno-Ugric-speaking populations analyzed by minisequencing on microarrays

An increasing number of single nucleotide polymorphisms (SNPs) on the Y chromosome are being identified. To utilize the full potential of the SNP markers in population genetic studies, new genotyping methods with high throughput are required. We describe a microarray system based on the minisequencing single nucleotide primer extension principle for multiplex genotyping of Y-chromosomal SNP markers. The system was applied for screening a panel of 25 Y-chromosomal SNPs in a unique collection of samples representing five Finno--Ugric populations. The specific minisequencing reaction provides 5-fold to infinite discrimination between the Y-chromosomal genotypes, and the microarray format of the system allows parallel and simultaneous analysis of large numbers of SNPs and samples. In addition to the SNP markers, five Y-chromosomal microsatellite loci were typed. Altogether 10,000 genotypes were generated to assess the genetic diversity in these population samples. Six of the 25 SNP markers (M9, Tat, SRY10831, M17, M12, 92R7) were polymorphic in the analyzed populations, yielding six distinct SNP haplotypes. The microsatellite data were used to study the genetic structure of two major SNP haplotypes in the Finns and the Saami in more detail. We found that the most common haplotypes are shared between the Finns and the Saami, and that the SNP haplotypes show regional differences within the Finns and the Saami, which supports the hypothesis of two separate settlement waves to Finland.

A system for specific, high-throughput genotyping by allele-specific primer extension on microarrays

This study describes a practical system that allows high-throughput genotyping of single nucleotide polymorphisms (SNPs) and detection of mutations by allele-specific extension on primer arrays. The method relies on the sequence-specific extension of two immobilized allele-specific primers that differ at their 3'-nucleotide defining the alleles, by a reverse transcriptase (RT) enzyme at optimized reaction conditions. We show the potential of this simple one-step procedure performed on spotted primer arrays of low redundancy by generating over 8000 genotypes for 40 mutations or SNPs. The genotypes formed three easily identifiable clusters and all known genotypes were assigned correctly. Higher degrees of multiplexing will be possible with this system as the power of discrimination between genotypes remained unaltered in the presence of over 100 amplicons in a single reaction. The enzyme-assisted reaction provides highly specific allele distinction, evidenced by its ability to detect minority sequence variants present in 5% of a sample at multiple sites. The assay format based on miniaturized reaction chambers at standard 384-well spacing on microscope slides carrying arrays with two primers per SNP for 80 samples results in low consumption of reagents and makes parallel analysis of a large number of samples convenient. In the assay one or two fluorescent nucleotide analogs are used as labels, and thus the genotyping results can be interpreted with presently available array scanners and software. The general accessibility, simple set-up, and the robust procedure of the array-based genotyping system described here will offer an easy way to increase the throughput of SNP typing in any molecular biology laboratory.