Predicting probative levels of touch DNA on tapelifts using Diamond™ Nucleic Acid Dye

Tapelifting is a common strategy to recover touch DNA deposits from porous exhibits in forensic DNA casework. However, it is known that only about 30 % of tapelifts submitted for DNA analysis in operational forensic laboratories yield profiles suitable for comparison or upload to a searchable database. A reliable means to identify and remove non-probative tapelifts from the workflow would reduce sample backlogs and provide significant cost savings. We investigated whether the amount of macroscopic or microscopic fluorescence on a tapelift following staining with Diamond Nucleic Acid Dye (DD), determined using a Polilight and Dino Lite microscope respectively, could predict the DNA yield and/or the DNA profiling outcome using controlled (saliva), semi-controlled (finger mark) and uncontrolled (clothing) samples. Both macroscopic and microscopic DD fluorescence could predict DNA yield and profiling outcome for all sample types, however the predictive power deteriorated as the samples became less controlled. For tapelifts of clothing, which are operationally relevant, Polilight fluorescence scores were significantly impacted by clothing fibres and other non-cellular debris and could not be used to identify non-probative samples. The presence of less than 500 cells on a clothing tapelift using microscopic counting of stained corneocytes was identified as a potential threshold for a non-probative DNA profiling outcome. A broader examination of the reliability of this threshold using a casework trial is recommended. Due to the labour intensiveness of microscopic cell counting, and the increased risk of inadvertent contamination, automation of this process using image software in conjunction with artificial neural networks (ANN) should be explored.

Satisfaction of mothers regarding human milk donation

In France, human milk banks are in charge of the collection, analysis, processing, and distribution of human milk to neonatology centers for preterm infants. Knowledge of what motivates mothers to donate their milk could lead to better communication regarding human milk donation. A satisfaction survey was conducted among mothers who were donating their milk to a human milk bank. In total, 214 mothers answered a questionnaire in the presence of the collector during a home visit. The median age of the mothers was 31 years (18-46), mainly high school (19%) or university (65%) graduates, and the median duration of donation was 3 months (0.5-22). At the time of the study, the median age of infants was 3 months (0.5-25), and 88% of infants were exclusively breastfed. About three quarters of mothers were motivated by willingness to help others, a quarter of them being especially sensitive to premature neonatal care; 30% of mothers were motivated by having a high supply of milk. Around 25% of mothers were given information on human milk donation during pregnancy, and two thirds after delivery, mainly by the maternity ward midwives (53.4%) or by collectors during their visit (14.1%). Most mothers (72%) found the human milk donation process easy and most of them (92.5%) were willing to donate their milk again after their next pregnancy. This survey shows that more than 90% of mothers are satisfied with donation to human milk banks. However, efforts should be made to provide information on breastfeeding and human milk donation to the general population and health professionals.

IL6 -174 genotype associated with Aggregatibacter actinomycetemcomitans in Indians

AIM

Genetic factors have recently been associated with presence of Aggregatibacter actinomycetemcomitans subgingivally in populations living in industrialized countries. The aim of this study was to analyse associations between Interleukin-6 (IL6) single nucleotide polymorphisms and presence and levels of A. actinomycetemcomitans and other subgingival microbes in a rural Indian population.

SUBJECTS AND METHODS

 A total of 251 individuals from a rural village in India with a periodontal phenotype ranging from healthy to severe periodontitis were included. Checkerboard DNA-DNA analysis was performed to detect 40 periodontal taxa in subgingival plaque samples. Genomic DNA was extracted to genotype five polymorphisms in the IL6 promoter region.

RESULTS

The IL6-74 GG genotype was associated with high (above median) counts of A. actinomycetemcomitans (both in all subjects and in periodontally healthy only) and with presence and counts of Capnocytophaga sputigena. Differences in detection of several other bacteria were noted between periodontitis and healthy subjects.

CONCLUSIONS

These findings support the influence of genetic factors on the subgingival microbiota.