Titanium dioxide induces apoptotic cell death through reactive oxygen species-mediated Fas upregulation and Bax activation

Background: Titanium dioxide (TiO2) has been widely used in many areas, including biomedicine, cosmetics, and environmental engineering. Recently, it has become evident that some TiO2 particles have a considerable cytotoxic effect in normal human cells. However, the molecular basis for the cytotoxicity of TiO2 has yet to be defined.Methods and results: In this study, we demonstrated that combined treatment with TiO2 nanoparticles sized less than 100 nm and ultraviolet A irradiation induces apoptotic cell death through reactive oxygen species-dependent upregulation of Fas and conformational activation of Bax in normal human cells. Treatment with P25 TiO2 nanoparticles with a hydrodynamic size distribution centered around 70 nm (TiO2P25-70) together with ultraviolet A irradiation-induced caspase-dependent apoptotic cell death, accompanied by transcriptional upregulation of the death receptor, Fas, and conformational activation of Bax. In line with these results, knockdown of either Fas or Bax with specific siRNA significantly inhibited TiO2-induced apoptotic cell death. Moreover, inhibition of reactive oxygen species with an antioxidant, N-acetyl-L-cysteine, clearly suppressed upregulation of Fas, conformational activation of Bax, and subsequent apoptotic cell death in response to combination treatment using TiO2P25-70 and ultraviolet A irradiation.Conclusion: These results indicate that sub-100 nm sized TiO2 treatment under ultraviolet A irradiation induces apoptotic cell death through reactive oxygen species-mediated upregulation of the death receptor, Fas, and activation of the preapoptotic protein, Bax. Elucidating the molecular mechanisms by which nanosized particles induce activation of cell death signaling pathways would be critical for the development of prevention strategies to minimize the cytotoxicity of nanomaterials.This work was supported by the Korea Ministry of Environment and The Eco-Technopia 21 Project (091-091-081)

Interactions between subjective memory complaint and objective cognitive deficit on memory performances

Background Subjective memory complaint (SMCs) is a common trait amongst older population. The subjective cognition about their memory could depend on objective cognition. The aim of the current study was to examine the interaction between subjective memory cognition (i.e., SMC) and objective cognition on cognitive functions in participants from older generation. Methods A total of 219 patients, 181 normal control (NC) patients and 38 patients with mild cognitive impairment (MCI), were examined through standardized and comprehensive clinical evaluation and neuropsychological assessment. The Subjective Memory Complaints Questionnaire was used to assess SMCs along with five cognitive tasks were used to evaluate cognitive decline over following areas: verbal memory, visuospatial memory, attention, fluency, and language. Results The results of 2 × 2 two-way analysis of variance (ANOVA) showed that there were significant interactions between SMCs and cognitive status (NC, MCI) on memory performances. NC with SMCs showed significantly lower performance in verbal memory and visuospatial memory compared to NCs without SMCs. Conversely, no effect was observed in the MCI group. Conclusion There are interactions between subjective cognition (i.e., SMC) and objective cognition (i.e., cognitive status) on memory performances in older adults. The roles of SMCs on memory performances should be interpreted with older adults objective cognitive status.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. NRF-2017R1D1A1A02018479). This funding source had no role in the design of this study and will not have any role during its execution, analyses, interpretation of the data, or decision to submit result

Thermally Stable and High???Mobility Dithienopyran???Based Copolymers: How Donor???Acceptor??? and Donor???Donor???Type Structures Differ in Thin???Film Transistors

Although rapid and remarkable progress has been made in semiconducting polymers used in organic field-effect transistors (OFETs), the development of novel ??-conjugated backbones remains the central issue in this field. High FET mobilities have been achieved for copolymers based on fused-ring building blocks due to their strong tendency to form ??????? stacks. However, introducing the recently formulated strong electron-rich fused-ring dithienopyran (DTP) unit in the polymer backbone has garnered considerably less attention. Herein, four new copolymers (donor???acceptor (D???A)-type versus donor???donor (D???D)-type structures) are synthesized based on the DTP unit by adopting different types of counterparts of the backbone. The characteristics of these copolymers, derived from different structural types, are investigated and compared and they are implemented in OFET devices. The D???A-type copolymers (P1 and P2) show higher charge-carrier mobilities and better thermal stability than the D???D-type copolymers (P3 and P4), attributed to enhanced crystalline features induced by strong intermolecular interactions and preferential 3D-textured molecular orientation of the D???A-type copolymers. Particularly, P1 exhibits the highest mobility of up to 0.22???cm2???V???1???s???1. This study provides a reference for understanding the influence of the backbone type on the structure???property relation and promotes the development of high-performance DTP-based copolymers

Interpersonal trauma moderates the relationship between personality factors and suicidality of individuals with posttraumatic stress disorder.

Individuals with posttraumatic stress disorder (PTSD) are more prone to suicidal ideation and behavior. While those who have experienced interpersonal trauma exhibit more suicidality than those who have experienced non-interpersonal trauma, it is unclear how the traumatic effects are related to an individual's personality characteristics. This study examined the association between interpersonal trauma and personality factors with suicidality, and elucidated the moderating role of interpersonal trauma in individuals with PTSD. The study included 6,022 participants from the Korean Epidemiologic Catchment Area Study 2011. The Korean Version of Composite International Diagnostic Interview was used for the survey, including the participants' history of suicidality, the traumas they have experienced, and their PTSD symptoms. The 11-item version of the Big Five Inventory (BFI-11) was used to assess the participants' personality factors. 76 individuals were diagnosed with PTSD, while 810 had been exposed to trauma but were not diagnosed with any DSM-IV mental disorder. Among the individuals with PTSD, those who had experienced interpersonal trauma were more likely to have suicidal ideation than those who had experienced non-interpersonal trauma (p = .020; odds ratio [OR] = 3.643; 95% confidence interval of OR = [1.226, 10.825]). High agreeableness and conscientiousness predicted less suicidality in those exposed to non-interpersonal trauma, while predicting more suicidality in those exposed to interpersonal trauma. Clinicians examining individuals with PTSD should pay closer attention to the trauma that they have experienced, as well as their personality factors, to provide appropriate treatment

Classification of traumatic events and the number of individuals with PTSD and trauma-exposed healthy controls reporting each event as a trauma producing the worst reactions.

<p>Classification of traumatic events and the number of individuals with PTSD and trauma-exposed healthy controls reporting each event as a trauma producing the worst reactions.</p

The relationships between BFI-11 personality factor scores and suicidality according to the type of trauma experienced among individuals with PTSD.

<p>The effect of the conscientiousness (a) and agreeableness (b) scores on suicidal ideation. The effect of the conscientiousness (c) and agreeableness (d) scores on suicidal planning. The effect of the conscientiousness (e) and agreeableness (f) scores on suicidal attempt. Interaction terms between the respective personality factor scores and the type of trauma were significant for suicidal ideation and attempt. Abbreviations: IT, interpersonal trauma; NIT, non-interpersonal trauma; BFI-11, Big Five Inventory, 11-item version; PTSD, posttraumatic stress disorder.</p

Demographics and suicidality of trauma-exposed participants.

<p>Demographics and suicidality of trauma-exposed participants.</p