Inclusive Approaches for Measuring Demographics of Underrepresented Populations in STEM and Biomedical Research Training Programs.

As federal strategic plans prioritize increasing diversity within the biomedical workforce, and STEM training and outreach programs seek to recruit and retain students from historically underrepresented populations, there is a need for interrogation of traditional demographic descriptors and careful consideration of best practices for obtaining demographic data. To accelerate this work, equity-focused researchers and leaders from STEM programs convened to examine approaches for measuring demographic variables. Gender, race/ethnicity, disability, and disadvantaged background were prioritized given their focus by federal funding agencies. Categories of sex minority, sexual (orientation) minority, and gender minority (SSGM) should be included in demographic measures collected by STEM programs, consistent with recommendations from White House Executive Orders and federal reports. Our manuscript offers operationalized phrasing for demographic questions and recommendations for use across student-serving programs. Inclusive demographics permit the identification of individuals who are being excluded, marginalized, or improperly aggregated, increasing capacity to address inequities in biomedical research training. As trainees do not enter training programs with equal access, accommodations, or preparation, inclusive demographic measures can welcome trainees and inform a nuanced set of program outcomes that facilitate research on intersectionality to support the recruitment and retention of underrepresented students in biomedical research.

Lived experiences of village-based patients with chronic kidney disease receiving haemodialysis at Mirpur, Azad Kashmir, Pakistan: a transcendental phenomenology study protocol.

BACKGROUND: Chronic kidney disease (CKD) is one of the major health issues in Pakistan, exerting notable effects on both the physical and mental well-being of individuals undergoing haemodialysis. Of particular concern to healthcare professionals is the potential adverse influence of haemodialysis on the lives of patients with CKD residing in rural areas of the country. This study will explore and describe the lived experiences and needs of patients with CKD receiving haemodialysis from the perspectives of patients and their family caregivers. METHODS AND ANALYSIS: Transcendental phenomenological research design will be used. Participants will be recruited from the dialysis centre of a tertiary hospital through purposive sampling based on specific inclusion criteria. In-depth unstructured interviews, observation and document analysis will be the methods for data collection. Data will be analysed using Colaizzi's approach following the transcription of the interviews. ETHICS AND DISSEMINATION: The study has been approved by the Institutional Review Board (IRB) of Shifa Tameer-e-Millat University, Pakistan (IRB # 0307-23) and written permission was obtained from the administration of the study hospital. Before giving written and verbal consent, all participants will receive detailed information about the study. Participants will maintain the freedom to withdraw from the study at any point. Confidentiality of the participants will be ensured. The study findings will be disseminated to important stakeholders and published in scientific papers and conference proceedings.

An Unusual Case of Paroxysmal Third-Degree Atrioventricular Block: Thinking Outside the Box.

During the assessment of a third-degree atrioventricular (AV) block in a patient with syncope, different etiologies should be considered and evaluated. Extrinsic vagal paroxysmal AV block, extrinsic idiopathic AV block and intrinsic paroxysmal AV block are among the types of third-degree AV block in the differential diagnoses. Extrinsic vagal paroxysmal third-degree atrioventricular block (EV-AVB) is linked to parasympathetic influence on cardiac conduction and can be observed in bladder distention and urinary retention. Topical and ophthalmic beta-blockers have shown systemic effects such as bradycardia with and without syncope. We present the case of an 80-year-old male with symptomatic EV-AVB likely precipitated by bladder outlet obstruction and chronic use of an ophthalmic beta-blocker, often overlooked causes of third-degree AV block.

Prussian blue nanocubes with peroxidase-like activity for polyphenol detection in commercial beverages.

The present study describes an efficient method for the determination of polyphenol content in beverages based on a composite material of graphene oxide decorated with Prussian blue nanocubes (rGO/PBNCs). In this method, rGO/PBNCs act as a nanoenzyme with peroxidase-like catalytic activity and produce a colorimetric product in the presence of hydrogen peroxide and tetramethylbenzidine (TMB). To verify the effectiveness of the method, we used two model standards for antioxidants: gallic acid (GA) and tannic acid (TA). The method validation included a comparison of the performance of a natural enzyme and an artificial one (rGO/PBNCs) and two polyphenols in the analysis of commercial beverage samples. After optimization, a pH of 4, ambient temperature (22 °C), a reaction time of 2 minutes and an rGO/PBNCs concentration of 0.01 µg mL-1 were found to be the most favorable conditions. The detection limits obtained were 5.6 µmol L-1 for GA and 1.5 µmol L-1 for TA. Overall, rGO/PBNCs offer advantages over natural enzymes in terms of stability, versatility, scalability and durability, making them attractive candidates for a wide range of catalytic and sensory applications.

A pocket companion to cell-free DNA (cfDNA) preanalytics.

The cumulative pool of cell-free DNA (cfDNA) molecules within bodily fluids represents a highly dense and multidimensional information repository. This "biological mirror" provides real-time insights into the composition, function, and dynamics of the diverse genomes within the body, enabling significant advancements in personalized molecular medicine. However, effective use of this information necessitates meticulous classification of distinct cfDNA subtypes with exceptional precision. While cfDNA molecules originating from different sources exhibit numerous genetic, epigenetic, and physico-chemical variations, they also share common features that complicate analyses. Considerable progress has been achieved in mapping the landscape of cfDNA features, their clinical correlations, and optimizing extraction procedures, analytical approaches, bioinformatics pipelines, and machine learning algorithms. Nevertheless, preanalytical workflows, despite their profound impact on cfDNA measurements, have not progressed at a corresponding pace. In this perspective article, we emphasize the pivotal role of robust preanalytical procedures in the development and clinical integration of cfDNA assays, highlighting persistent obstacles and emerging challenges.

Single-center outcome analysis of 46 fetuses with megacystis after intrauterine vesico-amniotic shunting with the Somatex®intrauterine shunt.

OBJECTIVES: To assess the spectrum of underlying pathologies, the intrauterine course and postnatal outcome of 46 fetuses with megacystis that underwent intrauterine vesico-amniotic shunting (VAS) with the Somatex® shunt in a single center. METHODS: Retrospective analysis of 46 fetuses with megacystis that underwent VAS either up to 14 + 0 weeks (early VAS), between 14 + 1 and 17 + 0 weeks (intermediate VAS) or after 17 + 0 weeks of gestation (late VAS) in a single tertiary referral center. Intrauterine course, underlying pathology and postnatal outcome were assessed and correlated with the underlying pathology and gestational age at first VAS. RESULTS: 46 fetuses underwent VAS, 41 (89%) were male and 5 (11%) were female. 28 (61%) fetuses had isolated and 18 (39%) had complex megacystis with either aneuploidy (n = 1), anorectal malformations (n = 6), cloacal malformations (n = 3), congenital anomalies overlapping with VACTER association (n = 6) or Megacystis-Microcolon Intestinal-Hypoperistalsis Syndrome (MMIHS) (n = 2). The sonographic 'keyhole sign' significantly predicted isolated megacystis (p < 0.001). 7 pregnancies were terminated, 4 babies died in the neonatal period, 1 baby died at the age of 2.5 months and 34 (74%) infants survived until last follow-up. After exclusion of the terminated pregnancies, intention-to-treat survival rate was 87%. Mean follow-up period was 24 months (range 1-72). The underlying pathology was highly variable and included posterior urethral valve (46%), hypoplastic or atretic urethra (35%), MMIHS or prune belly syndrome (10%) and primary vesico-ureteral reflux (2%). In 7% no pathology could be detected postnatally. No sonographic marker was identified to predict the underlying pathology prenatally. 14 fetuses underwent early, 24 intermediate and 8 late VAS. In the early VAS subgroup, amnion infusion prior to VAS was significantly less often necessary (7%), shunt complications were significantly less common (29%) and immediate kidney replacement therapy postnatally became less often necessary (0%). In contrast, preterm delivery ≤ 32 + 0 weeks was more common (30%) and survival rate was lower (70%) after early VAS compared to intermediate or late VAS. Overall, 90% of liveborn babies had sufficient kidney function without need for kidney replacement therapy until last follow-up, and 95% had sufficient pulmonary function without need for mechanical respiratory support. 18% of babies with complex megacystis suffered from additional health restrictions due to their major concomitant malformations. CONCLUSIONS: Our data suggest that VAS is feasible from the first trimester onward. Early intervention has the potential to preserve neonatal kidney function in the majority of cases and enables neonatal survival in up to 87% of cases. Despite successful fetal intervention, parents should be aware of the potential of mid- or long-term kidney failure and of additional health impairments due to concomitant extra-renal anomalies that cannot be excluded at time of intervention.

D-Transposition of the great arteries with restrictive foramen ovale in the fetus: the dilemma of predicting the need for postnatal urgent balloon atrial septostomy.

OBJECTIVE: Restrictive foramen ovale (FO) in dextro-transposition of the great arteries (d-TGA) with intact ventricular septum may lead to severe life-threatening hypoxia within the first hours of life, making urgent balloon atrial septostomy (BAS) inevitable. Reliable prenatal prediction of restrictive FO is crucial in these cases. However, current prenatal echocardiographic markers show low predictive value, and prenatal prediction often fails with fatal consequences for a subset of newborns. In this study, we described our experience and aimed to identify reliable predictive markers for BAS. METHODS: We included 45 fetuses with isolated d-TGA that were diagnosed and delivered between 2010 and 2022 in two large German tertiary referral centers. Inclusion criteria were the availability of former prenatal ultrasound reports, of stored echocardiographic videos and still images, which had to be obtained within the last 14 days prior to delivery and that were of sufficient quality for retrospective re-analysis. Cardiac parameters were retrospectively assessed and their predictive value was evaluated. RESULTS: Among the 45 included fetuses with d-TGA, 22 neonates had restrictive FO postnatally and required urgent BAS within the first 24 h of life. In contrast, 23 neonates had normal FO anatomy, but 4 of them unexpectedly showed inadequate interatrial mixing despite their normal FO anatomy, rapidly developed hypoxia and also required urgent BAS ('bad mixer'). Overall, 26 (58%) neonates required urgent BAS, whereas 19 (42%) achieved good O2 saturation and did not undergo urgent BAS. In the former prenatal ultrasound reports, restrictive FO with subsequent urgent BAS was correctly predicted in 11 of 22 cases (50% sensitivity), whereas a normal FO anatomy was correctly predicted in 19 of 23 cases (83% specificity). After current re-analysis of the stored videos and images, we identified three highly significant markers for restrictive FO: a FO diameter < 7 mm (p < 0.01), a fixed (p = 0.035) and a hypermobile (p = 0.014) FO flap. The maximum systolic flow velocities in the pulmonary veins were also significantly increased in restrictive FO (p = 0.021), but no cut-off value to reliably predict restrictive FO could be identified. If the above markers are applied, all 22 cases with restrictive FO and all 23 cases with normal FO anatomy could correctly be predicted (100% positive predictive value). Correct prediction of urgent BAS also succeeded in all 22 cases with restrictive FO (100% PPV), but naturally failed in 4 of the 23 cases with correctly predicted normal FO ('bad mixer') (82.6% negative predictive value). CONCLUSION: Precise assessment of FO size and FO flap motility allows a reliable prenatal prediction of both restrictive and normal FO anatomy postnatally. Prediction of likelihood of urgent BAS also succeeds reliably in all fetuses with restrictive FO, but identification of the small subset of fetuses that also requires urgent BAS despite their normal FO anatomy fails, because the ability of sufficient postnatal interatrial mixing cannot be predicted prenatally. Therefore, all fetuses with prenatally diagnosed d-TGA should always be delivered in a tertiary center with cardiac catheter stand-by, allowing BAS within the first 24 h after birth, regardless of their predicted FO anatomy.

Chemical profiling by UHPLC-Q-TOF-HRESI-MS/MS and antibacterial properties of Entada abyssinica (Fabaceae) constituents.

A rapid untargeted UHPLC-Q-TOF-ESI-MS/MS-Based metabolomic profiling of the medicinal plant Entada abyssinica was performed. A total of 18 metabolites were detected, of which 10 could not be identified. Based on this result, an extensive chemical investigation of the CH2Cl2-MeOH (1:1) extract of this plant was carried out, leading to the isolation of a new ceramide, named entadamide (1), together with nine known compounds: monomethyl kolavate (2), 24-hydroxytormentic acid (3) chondrillasterol (4), 3-O-ß-D glucopyranosylstigmasterol (5), 3-O-ß-D glucopyranosylsitosterol (6), quercetin 3'-methylether (7), 2,3-dihydroxypropyl icosanoate (8), 2,3-dihydroxy-propyl 23-hydroxytricosanoate (9) and 2,3-dihydroxy-propyl 24-hydroxytetracosanoate (10). Their structures were elucidated by the analyses of their spectroscopic and spectrometric data (1D and 2D NMR, and HRESI-MS) in comparison with those reported in the literature. Furthermore, the crude extract and some isolated compounds were tested against non-ciprofloxacin resistant strains viz, Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Samonella thyphi (ATCC 19430) and Samonella enterica (NR4294). The tested samples demonstrated significant activity against all the tested bacteria (MIC values: 3.12-12.5 µg/mL).

Sertraline associated with gold nanoparticles reduce cellular toxicity and induce sex-specific responses in behavior and neuroinflammation biomarkers in a mouse model of anxiety.

This study aimed to evaluate the effects of sertraline associated with gold nanoparticles (AuNPs) in vitro cell viability and in vivo behavior and inflammatory biomarkers in a mouse model of anxiety. Sertraline associated with AuNPs were synthesized and characterized. For the in vitro study, NIH3T3 and HT-22 cells were treated with different doses of sertraline, AuNPs, and sertraline + AuNPs and their viability was evaluated using the MTT assay. For the in vivo study, pregnant Swiss mice were administered a single dose of lipopolysaccharide (LPS) on the ninth day of gestation. The female and male offspring were divided into five treatment groups on PND 60 and administered chronic treatment for 28 days. The animals were subjected to behavioral testing and were subsequently euthanized. Their brains were collected and analyzed for inflammatory biomarkers. Sertraline associated with AuNPs exhibited significant changes in surface characteristics and increased diameters. Different doses of sertraline + AuNPs showed higher cell viability in NIH3T3 and HT-22 cells compared with sertraline alone. The offspring of LPS-treated dams exhibited anxiety-like behavior and neuroinflammatory biomarker changes during adulthood, which were ameliorated via sertraline + AuNPs treatment. The treatment response was sex-dependent and brain region-specific. These results suggest that AuNPs, which demonstrate potential to bind to other molecules, low toxicity, and reduced inflammation, can be synergistically used with sertraline to improve drug efficacy and safety by decreasing neuroinflammation and sertraline toxicity.

Cell-Free Nucleic Acids: Physico-Chemical Properties, Analytical Considerations, and Clinical Applications.

Human body fluids are rich sources of cell-free nuclear material, which exhibits unique characteristics [...].

Why Low-level Radiation Exposure Should Not Be Feared.

ABSTRACT: The purpose of this paper is to address the public fear that is usually associated with low-level radiation exposure situations. Its ultimate objective is to provide persuasive assurances to informed but skeptical members of the public that exposure situations involving low-level radiation are not to be feared. Unfortunately, just acquiescing to an unsupportive public fear of low-level radiation is not without consequences. It is causing severe disruptions to the benefits that harnessed radiation can produce for the well-being of all humanity. In this pursuit, the paper provides the scientific and epistemological basis needed for regulatory reform by reviewing the history in quantifying, understanding, modeling, and controlling radiation exposure, including some of the evolving contributions of the United Nations Scientific Committee on the Effects of Atomic Radiation, the International Commission on Radiological Protection, and the myriad of international and intergovernmental organizations establishing radiation safety standards. It also explores the various interpretations of the linear no-threshold model and the insights gained from radiation pathologists, radiation epidemiologists, radiation biologists, and radiation protectionists. Given that the linear no-threshold model is so deeply imbedded in current radiation exposure guidance, despite the lack of a solid scientific base on the actually proven radiation effects at low-doses, the paper suggests near-term ways to improve regulatory implementation and better serve the public by excluding and/or exempting trivial low-dose situations from the regulatory scope. Several examples are given where the unsubstantiated public fear of low-level radiation has resulted in crippling the beneficial effects that controlled radiation offers to a modern society.

Pre-Analytical Evaluation of Streck Cell-Free DNA Blood Collection Tubes for Liquid Profiling in Oncology.

Excellent pre-analytical stability is an essential precondition for reliable molecular profiling of circulating tumor DNA (ctDNA) in oncological diagnostics. Therefore, in vitro degradation of ctDNA and the additional release of contaminating genomic DNA from lysed blood cells must be prevented. Streck Cell-Free DNA blood collection tubes (cfDNA BCTs) have proposed advantages over standard K2EDTA tubes, but mainly have been tested in healthy individuals. Blood was collected from cancer patients (n = 53) suffering from colorectal (n = 21), pancreatic (n = 11), and non-small-cell lung cancer (n = 21) using cfDNA BCT tubes and K2EDTA tubes that were processed immediately or after 3 days (BCTs) or 6 hours (K2EDTA) at room temperature. The cfDNA isolated from these samples was characterized in terms of yield using LINE-1 qPCR; the level of gDNA contamination; and the mutation status of KRAS, NRAS, and EGFR genes using BEAMing ddPCR. CfDNA yield and gDNA levels were comparable in both tube types and were not affected by prolonged storage of blood samples for at least 3 days in cfDNA BCTs or 6 hours in K2EDTA tubes. In addition, biospecimens collected in K2EDTA tubes and cfDNA BCTs stored for up to 3 days demonstrated highly comparable levels of mutational load across all respective cancer patient cohorts and a wide range of concentrations. Our data support the applicability of clinical oncology specimens collected and stored in cfDNA BCTs for up to 3 days for reliable cfDNA and mutation analyses.

The influence of obstructive sleep apnea and continuous positive airway pressure on the nasal microbiome.

OBJECTIVE: The aim of this study was to investigate the influence of obstructive sleep apnea and continuous positive airway pressure on the nasal microbiome. PATIENTS AND METHODS: Endonasal swabs from the olfactory groove of 22 patients with moderate and severe obstructive sleep apnea (OSA) and a control group of 17 healthy controls were obtained at the Department of Otorhinolaryngology of the Friedrich-Alexander-Universität Erlangen-Nürnberg. 16S rRNA gene sequencing was performed to further evaluate the endonasal microbiome. In a second step, the longitudinal influence of continuous positive airway pressure (CPAP) therapy on the nasal microbiome was investigated (3-6 and 6-9 months). RESULTS: Analysis of the bacterial load and ß-diversity showed no significant differences between the groups, although patients with severe OSA showed increased α-diversity compared to the control group, while those with moderate OSA showed decreased α-diversity. The evaluation of longitudinal changes in the nasal microbiota during CPAP treatment showed no significant difference in α- or ß-diversity. However, the number of bacteria for which a significant difference between moderate and severe OSA was found in the linear discriminant analysis decreased during CPAP treatment. CONCLUSIONS: Long-term CPAP treatment showed an alignment of the composition of the nasal microbiome in patients with moderate and severe OSA as well as an alignment of biodiversity with that of the healthy control group. This change in the composition of the microbiome could be both part of the therapeutic effect in CPAP therapy and a promoting factor of the adverse side effects of the therapy. Further studies are needed to investigate whether the endonasal microbiome is related to CPAP compliance and whether CPAP compliance can be positively influenced in the future by therapeutic modification of the microbiome.

Indigenous practitioners' views on causes of female infertility.

Background: The use of indigenous practices has increased remarkably throughout the world. Subsequently, society uses this practice for the treatment of various health problems, including infertility. This research focussed on the role of indigenous practitioners (IPs) using a holistic approach to explore the causes of infertility in women. Aim: This study aimed to explore and describe the views of IPs on the causes of female infertility in Ngaka Modiri Molema health district. Setting: The study was conducted in Ngaka Modiri Molema, North West Province, one of the most rural provinces in South Africa. Methods: The study followed a qualitative explorative design. A purposive sampling technique identified five IPs who were experts in managing infertility. Individual semi-structured interviews were conducted, and data analysis used Creswell's method of qualitative data analysis. Results: Findings revealed that IPs offered a wide range of services in the treatment and management of infertility among rural women. Hence, the following themes emerged, namely, history taking regarding infertility, treatment of infertility and holistic care on infertility. Conclusion: The IPs are important providers of healthcare in the management of infertility in indigenous communities. The findings revealed that there are various causes of female infertility according to the indigenous healthcare system. Contribution: In contribution, the study described the unique practices found in the community as executed by the IPs. This care focusses on holistic care, including treatment and continuous care for the healthcare user and the family. Noteworthy to mention, this holistic care extends to subsequent pregnancies. However, there is a need for further research to valorise the indigenous knowledge unearthed in this study.

The changing face of circulating tumor DNA (ctDNA) profiling: Factors that shape the landscape of methodologies, technologies, and commercialization.

Liquid biopsies, in particular the profiling of circulating tumor DNA (ctDNA), have long held promise as transformative tools in cancer precision medicine. Despite a prolonged incubation phase, ctDNA profiling has recently experienced a strong wave of development and innovation, indicating its imminent integration into the cancer management toolbox. Various advancements in mutation-based ctDNA analysis methodologies and technologies have greatly improved sensitivity and specificity of ctDNA assays, such as optimized preanalytics, size-based pre-enrichment strategies, targeted sequencing, enhanced library preparation methods, sequencing error suppression, integrated bioinformatics and machine learning. Moreover, research breakthroughs have expanded the scope of ctDNA analysis beyond hotspot mutational profiling of plasma-derived apoptotic, mono-nucleosomal ctDNA fragments. This broader perspective considers alternative genetic features of cancer, genome-wide characterization, classical and newly discovered epigenetic modifications, structural variations, diverse cellular and mechanistic ctDNA origins, and alternative biospecimen types. These developments have maximized the utility of ctDNA, facilitating landmark research, clinical trials, and the commercialization of ctDNA assays, technologies, and products. Consequently, ctDNA tests are increasingly recognized as an important part of patient guidance and are being implemented in clinical practice. Although reimbursement for ctDNA tests by healthcare providers still lags behind, it is gaining greater acceptance. In this work, we provide a comprehensive exploration of the extensive landscape of ctDNA profiling methodologies, considering the multitude of factors that influence its development and evolution. By illuminating the broader aspects of ctDNA profiling, the aim is to provide multiple entry points for understanding and navigating the vast and rapidly evolving landscape of ctDNA methodologies, applications, and technologies.

The Clinical Utility of Droplet Digital PCR for Profiling Circulating Tumor DNA in Breast Cancer Patients.

Breast cancer is the most common cancer affecting women worldwide. It is a malignant and heterogeneous disease with distinct molecular subtypes, which has prognostic and predictive implications. Circulating tumor DNA (ctDNA), cell-free fragmented tumor-derived DNA in blood plasma, is an invaluable source of specific cancer-associated mutations and holds great promise for the development of minimally invasive diagnostic tests. Furthermore, serial monitoring of ctDNA over the course of systemic and targeted therapies not only allows unparalleled efficacy assessments but also enables the identification of patients who are at risk of progression or recurrence. Droplet digital PCR (ddPCR) is a powerful technique for the detection and monitoring of ctDNA. Due to its relatively high accuracy, sensitivity, reproducibility, and capacity for absolute quantification, it is increasingly used as a tool for managing cancer patients through liquid biopsies. In this review paper, we gauge the clinical utility of ddPCR as a technique for mutational profiling in breast cancer patients and focus on HER2, PIK3CA, ESR1, and TP53, which represent the most frequently mutated genes in breast cancers.

Isolation and Quantification of Plasma Cell-Free DNA Using Different Manual and Automated Methods.

Plasma cell-free DNA (cfDNA) originates from various tissues and cell types and can enable minimally invasive diagnosis, treatment and monitoring of cancer and other diseases. Proper extraction of cfDNA is critical to obtain optimal yields and purity. The goal of this study was to compare the performance of six commercial cfDNA kits to extract pure, high-quality cfDNA from human plasma samples and evaluate the quantity and size profiles of cfDNA extracts-among them, two spin-column based, three magnetic bead-based and two automatic magnetic bead-based methods. Significant differences were observed in the yield of DNA among the different extraction kits (up to 4.3 times), as measured by the Qubit Fluorometer and Bioanalyzer. All kits isolated mostly small fragments corresponding to mono-nucleosomal sizes. The highest yield and reproducibility were obtained by the manual QIAamp Circulating Nucleic Acid Kit and automated MagNA Pure Total NA Isolation Kit. The results highlight the importance of standardizing preanalytical conditions depending on the requirements of the downstream applications.

New Perspectives on the Importance of Cell-Free DNA Biology.

Body fluids are constantly replenished with a population of genetically diverse cell-free DNA (cfDNA) fragments, representing a vast reservoir of information reflecting real-time changes in the host and metagenome. As many body fluids can be collected non-invasively in a one-off and serial fashion, this reservoir can be tapped to develop assays for the diagnosis, prognosis, and monitoring of wide-ranging pathologies, such as solid tumors, fetal genetic abnormalities, rejected organ transplants, infections, and potentially many others. The translation of cfDNA research into useful clinical tests is gaining momentum, with recent progress being driven by rapidly evolving preanalytical and analytical procedures, integrated bioinformatics, and machine learning algorithms. Yet, despite these spectacular advances, cfDNA remains a very challenging analyte due to its immense heterogeneity and fluctuation in vivo. It is increasingly recognized that high-fidelity reconstruction of the information stored in cfDNA, and in turn the development of tests that are fit for clinical roll-out, requires a much deeper understanding of both the physico-chemical features of cfDNA and the biological, physiological, lifestyle, and environmental factors that modulate it. This is a daunting task, but with significant upsides. In this review we showed how expanded knowledge on cfDNA biology and faithful reverse-engineering of cfDNA samples promises to (i) augment the sensitivity and specificity of existing cfDNA assays; (ii) expand the repertoire of disease-specific cfDNA markers, thereby leading to the development of increasingly powerful assays; (iii) reshape personal molecular medicine; and (iv) have an unprecedented impact on genetics research.

Tracing the Origin of Cell-Free DNA Molecules through Tissue-Specific Epigenetic Signatures.

All cell and tissue types constantly release DNA fragments into human body fluids by various mechanisms including programmed cell death, accidental cell degradation and active extrusion. Particularly, cell-free DNA (cfDNA) in plasma or serum has been utilized for minimally invasive molecular diagnostics. Disease onset or pathological conditions that lead to increased cell death alter the contribution of different tissues to the total pool of cfDNA. Because cfDNA molecules retain cell-type specific epigenetic features, it is possible to infer tissue-of-origin from epigenetic characteristics. Recent research efforts demonstrated that analysis of, e.g., methylation patterns, nucleosome occupancy, and fragmentomics determined the cell- or tissue-of-origin of individual cfDNA molecules. This novel tissue-of origin-analysis enables to estimate the contributions of different tissues to the total cfDNA pool in body fluids and find tissues with increased cell death (pathologic condition), expanding the portfolio of liquid biopsies towards a wide range of pathologies and early diagnosis. In this review, we summarize the currently available tissue-of-origin approaches and point out the next steps towards clinical implementation.