Biology subjects

Singer, T.

Publications and source records attributed to Singer, T..

6 recordsLinked to original sources

bioRxiv2026

Rapid Micronucleus-Sequencing (RaMN-Seq) Reveals Patterns of Bias in Induced and Spontaneous Chromosomal Instability

Micronuclei are extra-nuclear structures formed following aberrant chromosome mis-segregation. Due to abnormal membrane features, micronuclei are liable to membrane rupture and are proposed as an important intermediate of extreme genome evolution events in cancer such as chromothripsis. Studying the features and contents of micronuclei can be informative about the underlying defective genomic instability process, but current purification strategies are time-consuming and require specialised methods. We developed Rapid MicroNucleus sequencing (RaMN-seq), a rapid (~2 hour), kit-style micronucleus purification strategy coupled to single micronucleus low-pass DNA sequencing to explore the genomic contents of micronuclei. Using RaMN-Seq we recapitulate the known chromosome bias of nocodazole washout-induced chromosome mis-segregation in diploid cells. We explore the features of ruptured (cGAS-positive) and intact micronuclei, finding no substantial differences in chromosomal contents or sizes between rupture states. Finally, we extend RaMN-Seq to cancer models, demonstrating the ability to rapidly explore features of chromosomal instability in cancer cell lines and fresh-frozen tumour samples. Overall, RaMN-Seq allows simple, rapid purification of micronuclei from a range of sources, and offers an inexpensive alternative to single cell genome sequencing to examine properties and chromosomal identities of genetic material affected by chromosomal instability.

cancer biology↗

bioRxiv2023

Mapping Pathways to Neuronal Atrophy in Healthy, Mid-aged Adults: From Chronic Stress to Systemic Inflammation to Neurodegeneration?

Growing evidence implicates systemic inflammation in the loss of structural brain integrity in natural ageing and disorder development. Chronic stress and glucocorticoid exposure can potentiate inflammatory processes and have also been linked to neuronal atrophy, particularly in the hippocampus and the human neocortex. To improve understanding of emerging maladaptive interactions between stress and inflammation, this study examined evidence for glucocorticoid- and inflammation-mediated neurodegeneration in healthy mid-aged adults. N=169 healthy adults (mean age = 39.4, 64.5% female) were sampled from the general population in the context of the ReSource Project. Stress, inflammation and neuronal atrophy were quantified using physiological indices of chronic stress (hair cortisol and cortisone concentration), systemic inflammation (interleukin-6, high-sensitive C-reactive protein), the systemic inflammation index (SII), hippocampal volume (HCV) and cortical thickness (CT) in regions of interest. Structural equation models were used to examined evidence for pathways from stress and inflammation to neuronal atrophy. Model fit indices indicated good representation of stress, inflammation, and neurological data through the constructed models (CT model: robust RMSEA = 0.041, robust{chi} 2= 910.90; HCV model: robust RMSEA < 0.001, robust{chi} 2 = 40.95). We replicated typical negative age-cortical thickness associations (Anterior cingulate cortex ({beta} =-0.51, p < .001), Parahippocampal Cortex ({beta} = -0.50, p = .012), Frontal Lobe ({beta} = -0.56, p < .001) and Temporal Lobe ({beta} = -0.61, p < .001). Among inflammatory indices, only the SII was positively associated with hair cortisol as one indicator of chronic stress ({beta} = 0.18, p<.05). Direct and indirect pathways from chronic stress and systemic inflammation to cortical thickness or hippocampal volume were non-significant. We identify the SII as a potential marker of systemic inflammation in human psychobiological studies. More generally, these data suggest that neurophysiological associations found in at-risk populations are not detectable in healthy, mid-aged populations. We conclude that inflammation and glucocorticoid-mediated neurodegeneration may only emerge during advanced ageing and disorder processes and may thus have limited use as early risk markers. Future work should examine these pathways in prospective longitudinal designs, for which the present investigation serves as a baseline.

neuroscience↗

bioRxiv2023

Hippocampal subfield CA1-3 shows differential structural and functional network plasticity after stress-reducing socio-affective mental training

The hippocampus is a central modulator of the HPA-axis, impacting the regulation of stress on brain structure, function, and behavior. The current study assessed whether three different types of 3-months mental Training Modules geared towards nurturing a) attention-based mindfulness, b) socio-affective or c) socio-cognitive skills may impact hippocampal organization by reducing stress. We evaluated mental training-induced changes in hippocampal subfield volume and intrinsic functional connectivity, by combining longitudinal structural and resting-state fMRI connectivity analysis in 332 healthy adults. We related these changes to changes in diurnal and chronic cortisol levels. We observed increases in bilateral cornu ammonis volume (CA1-3) following the 3-months compassion-based module targeting socio-affective skills (Affect module), as compared to socio-cognitive skills (Perspective module) or a waitlist cohort with no training intervention. Structural changes were paralleled by relative increases in functional connectivity of CA1-3 when fostering socio-affective as compared to socio-cognitive skills. Furthermore, training-induced changes in CA1-3 structure and function consistently correlated with reductions in cortisol output. Notably, using a multivariate approach, we found that other subfields that did not show group-level changes also contributed to changes in cortisol levels. Overall, we provide a link between a socio-emotional behavioural intervention, changes in hippocampal subfield structure and function, and reductions in cortisol in healthy adults.

neuroscience↗

bioRxiv2021

Human immunocompetent Organs-on-Chips platforms allow safety profiling of tumor-targeted T-cell bispecific antibodies

AbstractTraditional drug safety assessment often fails to predict complications in humans, especially when the drug targets the immune system. Here, we show the unprecedented capability of two Organs-on-Chips to evaluate the safety profile of T-cell bispecific antibodies (TCBs) targeting tumor antigens. Although promising for cancer immunotherapy, TCBs are associated with an on-target, off-tumor risk due to low levels of expression of tumor antigens in healthy tissues. We leveraged in vivo target expression and toxicity data of TCBs targeting folate receptor 1 (FOLR1) or carcinoembryonic antigen (CEA) to design and validate human immunocompetent Organs-on-Chips safety platforms. We discovered that the Lung-Chip and Intestine-Chip could reproduce and predict target-dependent TCB safety liabilities, based on sensitivity to key determinants thereof, such as target expression and antibody affinity. These novel tools broaden the research options available for mechanistic understandings of engineered therapeutic antibodies and assessing safety in tissues susceptible to adverse events.

cancer biology↗

bioRxiv2020

Contemplative mental training reduces hair glucocorticoid levels in a randomized clinical trial

ObjectiveThis study had the objective to investigate the effect of regular contemplative mental training on endocrine indices of long-term stress. MethodsAn open-label efficacy trial comprising three distinct 3-month modules targeting attention and interoception, socio-affective or socio-cognitive abilities through dyadic exercises and secularised meditation practices was designed and carried out in 332 healthy meditation-naive adults. Participants underwent the training for up to 9 months or were assigned to a retest control cohort. Chronic stress indices were assayed at four timepoints, i.e., pre-training and following each module. The main outcome measures were cortisol and cortisone concentration in hair and self-reported chronic stress ResultsN=362 initial individuals were randomized, of whom n=30 dropped out before study initiation, n=4 before first sampling and n=2 were excluded. N=99 participants did not provide hair samples. Data from three separate training cohorts revealed consistent decreases in hair cortisol and cortisone levels over the training period. This effect increased with practice frequency, was independent of training content and not associated with change in self-reported chronic stress. ConclusionsOur results point to the reduction of long-term cortisol exposure as a mechanism via which contemplative mental training may exert positive effects on practitioners health. Trial registrationClinicalTrials.gov identifier: NCT01833104

molecular biology↗

bioRxiv2020

A low-dimensional connectome manifold governs the organization and plasticity of social brain functions in humans.

The human brain scaffolds social cognitive functions, including Theory of Mind, empathy and compassion, through its functional and microstructural organization. However, it remains unclear how the learning and refinement of these skills may, in turn, shape brain function and structure. Here we studied if different types of social mental training can lead to plastic changes in brain function and microstructure. We studied a group of 332 healthy adults (197 women, 20-55 years) with repeated multimodal neuroimaging and behavioral testing. Our neuroimaging approach capitalized on the quantification of cortical functional gradients and myelin-sensitive T1 relaxometry, two emerging measures of cortical functional organization and microstructure. Longitudinal analysis indicated marked changes in intrinsic cortical function and microstructure, which varied as a function of social training content. In particular, we observed consistent differential change in function and microstructure between attention-mindfulness and socio-cognitive training in regions functionally associated with attention and interoception, including insular and parietal cortices. Conversely, socio-affective and socio-cognitive training resulted in differential microstructural changes in regions classically implicated in interoceptive and emotional processing, including insular and orbitofrontal areas, but did not result in functional reorganization. Notably, longitudinal changes in cortical function and microstructure were predictive of behavioral change in attention, compassion and perspective-taking, suggesting behavioral relevance. In sum, our work provides evidence for functional and microstructural plasticity after the training of social-interoceptive functions, and provides a causal perspective on the neural basis of behavioral adaptation in human adults.

neuroscience↗