Gender moderates the association between resting vagally mediated heart rate variability and attentional control.

Background: Women typically exhibit weaker attentional control ability than men. Lower resting vagally mediated heart rate variability (vmHRV) is thought to reflect the poorer function of the neurophysiological pathways underlying attentional control and thus, poorer attentional control ability. However, existing findings are inconsistent regarding the relationship between vmHRV and attentional control. Gender may be an important moderator. Objective: To examine whether gender moderates the relationship between resting vmHRV and attentional control, and to provide neurophysiological evidence for elucidating gender differences in attentional control ability. Methods: Two hundred and twenty college students completed the Attentional Control Scale to evaluate their attentional control ability. Resting vmHRV was assessed during a 5 min baseline period using an electrocardiographic amplifier (ECG100C) of the Biopac MP150 physiological recorder. Results: (1) There was no significant difference in the total scores of the Attentional Control Scale between men and women (t = 0.498, p > 0.05), but the scores of the attentional shifting dimension of women were significantly lower than those of men (t = 1.995, p < 0.05); (2) Resting vmHRV was significantly negatively correlated with attentional control in women(r = -0.233, p < 0.01), whereas the correlation was not significant in men; (3) Gender significantly moderated the relationship between resting vmHRV and attentional control (B = -3.088, 95% boot CI [-5.431, -0.745], t = -2.598, p < 0.05); (4) Among participants with lower resting vmHRV, there was no significant difference in attentional control between men and women (B = 2.284, 95% boot CI [-0.748, 5.310], p > 0.05), but among participants with higher resting vmHRV, men scored significantly higher than women in attentional control (B = -3.377, 95% boot CI [-6.406, -0.348], p < 0.05). Conclusion: Gender moderates the relationship between resting vmHRV and attentional control, with higher resting vmHRV in women reflecting a compensatory response to deficits in attentional control.

Probing interactions of red blood cells and contracting fibrin platelet clots.

Contraction of blood clots plays an important role in blood clotting, a natural process that restores hemostasis and regulates thrombosis in the body. Upon injury, a chain of events culminate in the formation of a soft plug of cells and fibrin fibers attaching to wound edges. Platelets become activated and apply contractile forces to shrink the overall clot size, modify clot structure, and mechanically stabilize the clot. Impaired blood clot contraction results in unhealthy volumetric, mechanical, and structural properties of blood clots associated with a range of severe medical conditions for patients with bleeding and thrombotic disorders. Due to the inherent mechanical complexity of blood clots and a confluence of multiple interdependent factors governing clot contraction, the mechanics and dynamics of clot contraction and the interactions with red blood cells (RBCs) remain elusive. Using an experimentally informed, physics-based mesoscale computational model, we probe the dynamic interactions among platelets, fibrin polymers, and RBCs, and examine the properties of contracted blood clots. Our simulations confirm that RBCs strongly affect clot contraction. We find that RBC retention and compaction in thrombi can be solely a result of mechanistic contraction of fibrin mesh due to platelet activity. Retention of RBCs hinders clot contraction and reduces clot contractility. Expulsion of RBCs located closer to clot outer surface results in the development of a dense fibrin shell in thrombus clots commonly observed in experiments. Our simulations identify the essential parameters and interactions that control blood clot contraction process, highlighting its dependence on platelet concentration and the initial clot size. Furthermore, our computational model can serve as a useful tool in clinically relevant studies of hemostasis and thrombosis disorders, and post thrombotic clot lysis, deformation, and breaking.

A nanoparticle-based molecular beacon for directly detecting attomolar small RNA from plasma without purification.

Molecular beacons (MBs) are DNA-based probes that detect DNA or RNA fragments and hold promise for monitoring diseases and studying protein-nucleic acid interactions. MBs usually use fluorescent molecules as fluorophores for reporting the target detection event. However, the fluorescence of the traditional fluorescent molecules can bleach and even be interfered with the background autofluorescence, reducing the detection performance. Hence, we propose to develop a nanoparticle-based MB (NPMB) that uses upconversion nanoparticles (UCNPs) as a fluorophore, which can be excited by near-infrared light to avoid background autofluorescence and thus enables us to detect small RNA from complicated clinical samples such as plasma. Specifically, we employ a DNA hairpin structure, with one segment complementary to the target RNA, to position a quencher (gold nanoparticles, Au NPs) and the UCNP fluorophore in close proximity, leading to the quenching of the fluorescence of UCNPs in the absence of a target nucleic acid. Only when the hairpin structure is complementary with the detection target, will the hairpin structure be destroyed to separate Au NPs and UCNPs, resulting in the instant recovery of the fluorescence signal of UCNPs and the consequent ultrasensitive detection of the target concentrations. The NPMB has an ultra-low background signal because UCNPs can be excited with NIR light with a wavelength longer than the emitted visible light. We demonstrate that the NPMB can successfully detect a small (22-nt) RNA (using a microRNA cancer biomarker, miR-21, as an example) and a small single-stranded DNA (complementing the cDNA of miR-21) in aqueous solutions from 1 aM to 1 pM, with the linear detection range being 10 aM to 1 pM for the former and 1 aM to 100 fM for the latter. We further show that the NPMB can be used to detect unpurified small RNA (miR-21) in clinical samples such as plasma with the same detection region. Our work suggests that the NPMB is a promising label-free and purification-free method for detecting small nucleic acid biomarkers in clinical samples with a detection limit as low as the aM level.

Social isolation, psychological distress and resilience of Chinese college students during COVID-19 pandemic.

It has been 3 years since the first appearance of COVID-19 in China. During this time, social isolation was widely used as an important method to fight it. However, this measure had many negative effects on the mental health of college students. To better understand this issue, this study aims to explore the impact of social isolation and COVID-19-related stress on psychological distress among Chinese college students. Additionally, resilience has been evaluated as a key component of stress resistance in this situation. Coronavirus Stress Measure (CSM), the Connor-Davidson Resilience Scale (CD-RISC) and the Brief Symptom Inventory (BSI) were used in this study. A total of 388 Chinese college students participated in the survey via the Internet. Two groups (isolated group vs. non-isolated group) were divided according to whether they have been isolated from their classmates and families. Data analysis adopts t-test, F test and mediate effect analysis by SPSS21.0. (1) All factors, except resilience, were found to have lower scores in the isolated group; (2) significant correlations were found between all factors; (3) resilience partially mitigated the impact of COVID-19 stress on psychological symptoms. Social isolation has been found to be a significant factor contributing to negative psychological distress in Chinese college students. The COVID-19-related stress may increase the likelihood of psychological suffering among isolated group. Resilience can help reduce the negative effects of COVID-19 stress on college students. Therefore, providing appropriate psychological support tailored to different isolation situations is crucial.

COVID-19 burnout, resilience, and psychological distress among Chinese college students.

Background: Since the outbreak of coronavirus disease 2019 (COVID-19), Chinese college students have spent 3 years dealing with infection prevention. Some students have undergone quarantine due to the detection of new variants of COVID-19 and the rise in cases. This study examines pandemic-related isolation and its psychological impact on Chinese college students and explores the relationships among COVID-19 burnout, resilience, and psychological distress in Chinese college students during the pandemic. Methods: The COVID-19 Burnout Scale, the Connor-Davidson Resilience Scale, and the Brief Symptom Inventory were used to investigate 388 college students from Nanjing City, China. All participants were enrolled in university after 2019, and they participated in the survey voluntarily via the Internet. Participants were divided into two groups (isolated group vs. non-isolated group) based on whether or not they had been isolated. Results: (1) Significantly lower scores were found for all factors in the isolated group; (2) COVID-19 burnout significantly negatively predicted resilience and significantly positively predicted psychological distress (anxiety, depression, and somatization symptoms), while resilience significantly negatively predicted psychological distress; and (3) Resilience mediated the relationship between COVID-19 burnout and psychological distress. Conclusion: Isolation is a risk factor for psychological distress related to COVID-19. Resilience can buffer psychological distress and help improve Chinese college students' wellbeing during the COVID-19 pandemic.

Resolving the missing link between single platelet force and clot contractile force.

Blood clot contraction plays an important role in wound healing and hemostasis. Although clot contraction is known to be driven by platelets, how single platelet forces relate to the forces generated by macroscopic clots remains largely unknown. Using our microfabricated high-throughput platelet contraction cytometer, we find that single platelets have an average force of 34 nN ( n = 10 healthy individuals). However, multiple bulk clot experiments predict a mean single platelet force lower than 0.5 nN. To resolve this discrepancy, we use a mesoscale computational model to probe the mechanism by which individual platelets induce forces in macroscopic clots. Our experimentally informed model shows that the number of platelets in the clot cross-section defines the net clot force. We provide a relationship between single platelet force and the clot force that is useful for better understanding of blood disorders associated with bleeding and thrombosis, and facilitates the development of platelet-based and platelet-mimetic biomaterials.

The relationship between stress, resilience, and quality of life in Chinese high school students.

BACKGROUND: Stress is an important factor affecting the dynamic process of resilience. This study aimed to explore the role of stress levels in the relationship between resilience and health consequences by investigating high school students undergoing the National College Entrance Examination (CEE), which often involves intense stressful conditions for students in China, at different stages. METHODS: The CD-RISC [Conner-Davidson Resiliency Scale] and SF-36 [the short form 36 health survey questionnaire, one measurement of the quality of life (QoL)] were used to investigate 435 high school students, including 208 students in grade two (low stress group) and 227 students in grade three (high stress group). RESULTS: This study found that the SF-36 scores under high-stress conditions were significantly lower than those under low-stress conditions, however there were no significant differences in the mental resilience scores. Additionally, under low-stress conditions, mental resilience was found to be significantly correlated with various factors of SF-36, but no significant correlation was observed under high-stress conditions. It was also discovered that stress levels can mediate the relationship between psychological resilience and QoL (the quality of life). CONCLUSIONS: Stress level is an important factor affecting the expression of resilience. This study also discussed the integration of the concept of resilience.

Platelet heterogeneity enhances blood clot volumetric contraction: An example of asynchrono-mechanical amplification.

Physiological processes such as blood clotting and wound healing as well as pathologies such as fibroses and musculoskeletal contractures, all involve biological materials composed of a contracting cellular population within a fibrous matrix, yet how the microscale interactions among the cells and the matrix lead to the resultant emergent behavior at the macroscale tissue level remains poorly understood. Platelets, the anucleate cell fragments that do not divide nor synthesize extracellular matrix, represent an ideal model to study such systems. During blood clot contraction, microscopic platelets actively pull fibers to shrink the macroscale clot to less than 10% of its initial volume. We discovered that platelets utilize a new emergent behavior, asynchrono-mechanical amplification, to enhanced volumetric material contraction and to magnify contractile forces. This behavior is triggered by the heterogeneity in the timing of a population of actuators. This result indicates that cell heterogeneity, often attributed to stochastic cell-to-cell variability, can carry an essential biophysical function, thereby highlighting the importance of considering 4 dimensions (space + time) in cell-matrix biomaterials. This concept of amplification via heterogeneity can be harnessed to increase mechanical efficiency in diverse systems including implantable biomaterials, swarm robotics, and active polymer composites.

Identification of catechol as a new marker for detecting propolis adulteration.

Adulteration of propolis with poplar extract is a serious issue in the bee products market. The aim of this study was to identify marker compounds in adulterated propolis, and examine the transformation of chemical components from poplar buds to propolis. The chemical profiles of poplar extracts and propolis were compared, and a new marker compound, catechol, was isolated and identified from the extracts of poplar buds. The polyphenol oxidase, catechol oxidase, responsible for catalyzing oxidation of catechol was detected in poplar buds and propolis. The results indicate catechol can be used as a marker to detect propolis adulterated with poplar extract.