Replication Pauses of the Wild-Type and Mutant Mitochondrial DNA Polymerase Gamma: A Simulation Study

The activity of polymerase γ is complicated, involving both correct and incorrect DNA polymerization events, exonuclease activity, and the disassociation of the polymerase:DNA complex. Pausing of pol-γ might increase the chance of deletion and depletion of mitochondrial DNA. We have developed a stochastic simulation of pol-γ that models its activities on the level of individual nucleotides for the replication of mtDNA. This method gives us insights into the pausing of two pol-γ variants: the A467T substitution that causes PEO and Alpers syndrome, and the exonuclease deficient pol-γ (exo−) in premature aging mouse models. To measure the pausing, we analyzed simulation results for the longest time for the polymerase to move forward one nucleotide along the DNA strand. Our model of the exo− polymerase had extremely long pauses, with a 30 to 300-fold increase in the time required for the longest single forward step compared to the wild-type, while the naturally occurring A467T variant showed at most a doubling in the length of the pauses compared to the wild-type. We identified the cause of these differences in the polymerase pausing time to be the number of disassociations occurring in each forward step of the polymerase

Stochastic Drift in Mitochondrial DNA Point Mutations: A Novel Perspective Ex Silico

The mitochondrial free radical theory of aging (mFRTA) implicates Reactive Oxygen Species (ROS)-induced mutations of mitochondrial DNA (mtDNA) as a major cause of aging. However, fifty years after its inception, several of its premises are intensely debated. Much of this uncertainty is due to the large range of values in the reported experimental data, for example on oxidative damage and mutational burden in mtDNA. This is in part due to limitations with available measurement technologies. Here we show that sample preparations in some assays necessitating high dilution of DNA (single molecule level) may introduce significant statistical variability. Adding to this complexity is the intrinsically stochastic nature of cellular processes, which manifests in cells from the same tissue harboring varying mutation load. In conjunction, these random elements make the determination of the underlying mutation dynamics extremely challenging. Our in silico stochastic study reveals the effect of coupling the experimental variability and the intrinsic stochasticity of aging process in some of the reported experimental data. We also show that the stochastic nature of a de novo point mutation generated during embryonic development is a major contributor of different mutation burdens in the individuals of mouse population. Analysis of simulation results leads to several new insights on the relevance of mutation stochasticity in the context of dividing tissues and the plausibility of ROS ”vicious cycle” hypothesis

Patients’ experiences with pre-test genetic counseling provided by breast cancer healthcare professionals: Results from a large prospective multicenter study

Background: Pre-test genetic counseling of patients with breast cancer is increasingly being offered by non-genetic healthcare professionals. We aimed to evaluate the experiences of patients with breast cancer receiving pre-test genetic counseling from a non-genetic healthcare professional (i.e., surgeon or nurse). Methods: Patients who were diagnosed with breast cancer and received pre-test counseling from their surgeon or nurse (mainstream group), and patients who received pre-test counseling from a clinical geneticist (usual care group) were invited to participate in our multicenter study. Between September 2019 and December 2021, patients received a questionnaire after pre-test counseling (T0) and four weeks after receiving their test results (T1) to evaluate psychosocial outcomes, knowledge, discussed topics and satisfaction. Results: We included 191 patients in our mainstream and 183 patients in our usual care group and received, respectively 159 and 145 follow-up questionnaires. Levels of distress and decisional regret were comparable in both groups. Decisional conflict was higher in our mainstream group (p = 0.01), but only 7% had clinically relevant decisional conflict (vs 2% in usual care group). The possible implications of a genetic test on (secondary) breast or ovarian cancer risks were less frequently discussed in our mainstream group (p = 0.03 and p = 0.000, respectively). In both groups knowledge about genetics was comparable, satisfaction was high and the majority of patients in both groups preferred to give both verbal and written consent for genetic testing. Conclusion: Mainstreamed genetic care provides sufficient information for the majority of breast cancer patients to decide about genetic testing with minimal distress

Transcription errors induce proteotoxic stress and shorten cellular lifespan

Transcription errors occur in all living cells; however, it is unknown how these errors affect cellular health. To answer this question, we monitored yeast cells that were genetically engineered to display error-prone transcription. We discovered that these cells suffer from a profound loss in proteostasis, which sensitizes them to the expression of genes that are associated with protein-folding diseases in humans; thus, transcription errors represent a new molecular mechanism by which cells can acquire disease. We further found that the error rate of transcription increases as cells age, suggesting that transcription errors affect proteostasis particularly in aging cells. Accordingly, transcription errors accelerate the aggregation of a peptide that is implicated in Alzheimer’s disease, and shorten the lifespan of cells. These experiments reveal a novel, basic biological process that directly affects cellular health and aging

Investigating the critical elements and psychosocial outcomes of Youth Flexible Assertive Community Treatment: A study protocol for an observational prospective cohort study

Contains fulltext : 217735.pdf (publisher's version ) (Open Access)Introduction: When adolescents experience complex psychiatric and social problems, numerous healthcare services usually become involved. In these cases, fragmentation of care services is a risk that often results in both ineffective care and in patients disengaging from care services. To address these issues, Youth Flexible Assertive Community Treatment (Youth Flexible ACT) was developed in the Netherlands. This client-centred service delivery model aims to tackle the fragmented care system by providing psychiatric treatment and support in a flexible and integrated manner. While Youth Flexible ACT is gaining in popularity, the effectiveness of the care model remains largely unexamined. Methods and analysis: Here, we present an observational prospective cohort (2017-2021) in which a broad range of treatment outcomes will be monitored. The primary aim of the study is to examine change in treatment outcomes over the course of the Flexible ACT care. The secondary aim is to examine the association between (elements of) Youth Flexible ACT model fidelity and treatment outcomes. An estimated total number of 200 adolescents who receive care from one of the 16 participating Youth Flexible ACT teams will be included in the study. Participants will be asked to complete assessments at four time points in 6-month intervals, resulting in a study duration of 18 months. Latent growth curve analysis will be conducted to examine change in psychosocial functioning over time and its relation to model fidelity. Ethics and dissemination: This study received ethical approval from Trimbos Ethics Committee (201607_75-FACT2). This approval applies for all participating institutions. The results of the study will be reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology statement. Results will be disseminated via peer-reviewed academic journals and presentations at conferences. In addition, results will be made available for participating sites, funders and researchers.10 p

Young patients with persistent and complex care needs require an integrated care approach: Baseline findings from the Multicenter Youth Flexible ACT Study

Contains fulltext : 228238.pdf (publisher's version ) (Open Access)Background: The Multicenter Youth Flexible ACT Study is an ongoing observational prospective cohort study that examines the effects of Youth Flexible ACT (Assertive Community Treatment) on young people with complex care needs who are difficult to engage in traditional (office-based) mental health services. However, a clear and detailed description of this patient group is lacking. In the current paper, we present baseline characteristics and psychosocial outcomes of the Youth Flexible ACT target group and explore the existence of underlying specific patient subgroups.Methods: Sixteen Youth Flexible ACT teams from seven mental healthcare institutes in the Netherlands participated in the study. Research participants were monitored for 18 months and administered questionnaires measuring psychiatric- and social functioning every 6 months, yielding four measurements. Baseline data were obtained from 199 adolescents, their mental health workers, and parents/carers. Latent Class Analysis based on HoNOSCA scores (measuring psychosocial and daily functioning) was conducted to identify underlying subgroups.Results: The target group of Youth Flexible ACT mainly consisted of patients older than 15 years of age with a history of (specialized) mental healthcare. They face many complex problems, including trauma; developmental, mood, and anxiety disorders; and problems with school attendance, family life, and peer relationships. Other frequently reported difficulties were substance misuse, the involvement of the legal system or police, problems with intellectual functioning, and personal finance. Patients were classified into four distinct classes: the "internalizing," "externalizing," "non-specific," and the "overly impulsive" subgroup. Each subgroup had its unique pattern of difficulties and focus, respectively, high levels of depression and anxiety, disruptive behavior, unspecific difficulties, and substance misuse.Conclusions: As expected, patients in Youth Flexible ACT experienced many severe problems, rendering them vulnerable to fragmented and, thus, ineffective care. Our findings underscore the need for an integrated care approach with a multidisciplinary team of skilled professionals that can bridge these wide-ranging psychosocial problems, as each class of participants experienced a different set of difficulties. Youth Flexible ACT teams need to adjust their care services accordingly.14 p

Occurence of internet addiction in a general population sample: A latent class analysis

Background: Prevalence studies of Internet addiction in the general population are rare. In addition, a lack of approved criteria hampers estimation of its occurrence. Aims: This study conducted a latent class analysis (LCA) in a large general population sample to estimate prevalence. Methods: A telephone survey was conducted based on a random digit dialling procedure including landline telephone (n = 14,022) and cell phone numbers (n = 1,001) in participants aged 14-64. The Compulsive Internet Use Scale (CIUS) served as the basis for a LCA used to look for subgroups representing participants with Internet addiction or at-risk use. CIUS was given to participants reporting to use the Internet for private purposes at least 1 h on a typical weekday or at least 1 h on a day at the weekend (n = 8,130). Results: A 6-class model showed best model fit and included two groups likely to represent Internet addiction and at-risk Internet use. Both groups showed less social participation and the Internet addiction group less general trust in other people. Proportions of probable Internet addiction were 1.0% (CI 0.9-1.2) among the entire sample, 2.4% (CI 1.9-3.1) in the age group 14-24, and 4.0% (CI 2.7-5.7) in the age group 14-16. No difference in estimated proportions between males and females was found. Unemployment (OR 3.13; CI 1.74-5.65) and migration background (OR 3.04; CI 2.12-4.36) were related to Internet addiction. Conclusions: This LCA-based study differentiated groups likely to have Internet addiction and at-risk use in the general population and provides characteristics to further define this rather new disorder