Youth Suicide in Korea Across the Educational Stages.

Background: Youth suicides have diverse characteristics according to the young people's developmental stages. Warning signs and communication of suicidal intent can be vague among early adolescents, while mental health problems may be more evidently related to suicidal ideation in older adolescents. Understanding the developmental characteristics of youth suicide is necessary for effective suicide prevention. Aims: We explored the differences between children and adolescents who died by suicide and the characteristics of these young people as observed by their school teachers. Method: We analyzed teachers' mandatory postmortem reports of suicides among 308 Korean students. We compared: suicide-related information including personal, familial, and school factors; stressful life events; and participation in interventions among elementary, middle, and high school students who died by suicide. We also assessed the distribution of student suicides per month. Results: Suicide among elementary school students increased during school vacations, and suicide among middle and high school students increased during the school semester. According to the teachers' reports, elementary school students who died by suicide were more extroverted and had better academic achievements than their high school peers, and had significantly lower levels of substance/tobacco use. Elementary school students who died by suicide showed significantly less academic stress and use of external professional help than did other groups. Limitations: Because this research is based on mandatory teacher reports, the subjective opinions of teachers may have affected the reliability of the data. Suicide by out-of-school youth was not included. Conclusion: School-based suicide prevention should be implemented in accordance with young people's developmental characteristics.

Gender differences in Korean adolescents who died by suicide based on teacher reports.

BACKGROUND: We investigated the characteristics of adolescents who committed suicide in South Korea, and how these characteristics differed by gender. METHOD: Data from middle and high school students who committed suicide between 2014 and 2016 were analyzed. We evaluated differences in suicide method and place, personal characteristics, and school life characteristics by gender using the Chi square test and t test. RESULTS: Jumping from a high place was the most common suicide method for both male and female students. A significantly greater proportion of female adolescents had experienced depressive symptoms, previous self-injury, previous suicide attempts, and had problems with school attendance and peers. Additionally, they were more likely to be classified as high risk according to a school-based mental health screening test and to utilize professional mental health treatment services. CONCLUSION: Our results demonstrate that adolescents who committed suicide exhibited gender differences in personal characteristics and school life. These characteristics might aid in the development of adolescent suicide policies and intervention programs.

CXCR3-deficient natural killer cells fail to migrate to B16F10 melanoma cells.

Natural killer (NK) cells eliminate cancer cells in a contact-dependent manner. However, how NK cells find cancer cells remain unclear. Here, using time-lapse imaging, we investigated how individual NK cells migrate toward cancer cells. Although naïve B16F10 cancer cells produce low levels of chemokines, IFN-γ-treated B16F10 cells secreted high levels of CXCL10, low levels of CCL5, but did not secrete CCL2, CCL7, or CXCL12. Wild-type NK cells migrated well toward cancer cells and killed them, whereas NK cells deficient in CXCR3 did not. CXCR3-deficient NK cells also showed slower migration speed than did wild-type NK cells. Taken together, our data show that NK cells find cancer cells, at least in part, by sensing CXCL10 produced by cancer cells and suggest that a strategy to increase CXCL10 secretion by cancer cells may improve the efficacy of NK cell-based immunotherapy.

Cd226-/- natural killer cells fail to establish stable contacts with cancer cells and show impaired control of tumor metastasis in vivo.

CD226 is an activating receptor expressed on natural killer (NK) cells, CD8+ T cells, and other immune cells. Upon binding to its ligands expressed on target cells, CD226 activates intracellular signaling that triggers cytokine production and degranulation in NK cells. However, the role of CD226 in contact dynamics between NK and cancer cells has remained unclear. Our time-lapse images showed that individual wild-type CD226+ NK cells contacted B16F10 melanoma cells for 23.7 min, but Cd226-/- NK cells only for 12.8 min, although both NK cell subsets showed equal contact frequency over 4 h. On the surface of B16F10 cells, CD226+ cells stayed at the same site with oscillating movement (named stable contact), while Cd226-/- NK cells moved around at a velocity of 4 µm/min (named unstable contact). Consequently, Cd226-/- NK cells did not kill B16F10 cells in vitro and did not inhibit their metastasis into the lung in vivo. Taken together, our data demonstrate that CD226 enables prolonged stable interaction between NK and cancer cells, which is needed for efficient killing of cancer cells.

A polysaccharide isolated from Pueraria lobata enhances maturation of murine dendritic cells.

Maturation of dendritic cells (DCs) is a critical factor for initiating the immune response. However, DC maturation is usually attenuated in the tumor microenvironment, which is an important immunological problem in DC-based immunotherapy against cancer. Here, we report the effect of a polysaccharide (PLP) isolated from Pueraria lobata on phenotypic and functional maturation of DCs. Phenotypic maturation was demonstrated by increased expression of CD40, CD86, and major histocompatibility complex I/II. PLP induced functional maturation of DCs, as shown by increased production of interleukin (IL)-12, IL-1ß, and tumor necrosis factor-α, decreased antigen capture capacity, and enhanced allogenic T cell stimulation. In addition, PLP activated DCs generated from C3H/HeN mice with normal TLR4, but not DCs from C3H/HeJ mice with mutated TLR4, suggesting that the TLR4 is a membrane receptor of PLP. We showed that PLP increased ERK, JNK, and p38 mitogen-activated protein kinase phosphorylation, and nuclear translocation of the nuclear factor-kappaB p65 subunit, which are signaling molecules downstream of TLR4. These results indicate that PLP induced DC maturation through TLR4 signaling.

Promoting effect of polysaccharide isolated from Mori fructus on dendritic cell maturation.

Maturation of dendritic cells (DCs) is usually attenuated in the tumor microenvironment, which is an important immunological problem in DC-based immunotherapy of cancer. In this study, we report the effect of a Mori fructus polysaccharide (MFP) on DC maturation. MFP was treated to DCs generated from mouse BM cells. MFP induced phenotypic maturation of DCs, as proven by the increased expression of CD40, CD80/86, and MHC-I/II molecules. MFP induced functional maturation of DCs, in that MFP increased the expression of IL-12, IL-1ß, TNF-α, and IFN-ß, decreased antigen capture capacity, and enhanced allogenic T cell stimulation. MFP efficiently induced maturation of DCs from C3H/HeN mice having normal toll-like receptor4 (TLR4), but not DCs from C3H/HeJ mice having mutated TLR4, suggesting that TLR4 might be one of the membrane receptors of MFP. As a mechanism of action, MFP increased phosphorylation of mitogen-activated protein kinase (MAPKs), and nuclear translocation of NF-κB p65 subunit, which were important signal molecules downstream from TLR4. These data suggest that MFP induces DC maturation through TLR4 and MFP can be used as an adjuvant in DC-based cancer immunotherapy.

Dendritic cell activation by polysaccharide isolated from Angelica dahurica.

Angelica dahurica is used in functional foods for the prevention and treatment of various diseases, such as inflammation and cancer. In the present study, we examined the effect of A. dahurica polysaccharide (ADP) on dendritic cell (DC) maturation. ADP increased the expressions of CD86 and MHC-II molecules, the production of IL-12, IL-1ß, and TNF-α, and allogeneic T cell activation ability of DCs, and reduced DC endocytosis. As a mechanism of action, the knockdown of TLR4 with small interfering RNA decreased the ADP-induced production of nitric oxide and IL-12 by DCs, suggesting the membrane receptor candidate of ADP. After binding to TLR4, ADP increased the phosphorylation of ERK, JNK, and p38 MAPKs, and the nuclear translocation of NF-κB p50/p65. These results indicate that ADP activates DCs through TLR4 and downstream signalings.

Efficacy of a training program for long-term disease- free cancer survivors as health partners: a randomized controlled trial in Korea.

BACKGROUND: To determine whether the Health Partner Program is effective in training long-term cancer survivors to be health coaches. MATERIALS AND METHODS: We randomly assigned cancer survivors who were selected through a rigorous screening process to either the Health Partner Program or the waiting-list control group. The program consisted of 8 weeks of training in health management, leadership, and coaching. At baseline, 8, and 16 weeks, we measured primary outcomes using the Seven Habit Profile (SHP), the Korean Leadership Coaching Competency Inventory (KCCI), Ed Diner's Satisfaction with Life Scale (SWLS), and the Posttraumatic Growth inventory (PTGI) and secondary outcomes using the Hospital Anxiety and Depression Scale (HADS), the Impact of Event Scale-Revised (IES-R), and the Medical Outcomes Study (MOS) short form 36-item questionnaire (SF- 36). RESULTS: We recruited 70 subjects and randomly assigned 34 to the intervention group. The Sharpen the Saw habit of the SHP increased significantly more in intervention group than in the control group (p = 0.049), as did most PTGI factors. The intervention group also showed a significantly greater enhancement of vitality (p = 0.015) and mental health (p = 0.049) SF-36 scores but no improvement in KCCI, SWLS, HADS, or IES-R scores. The intervention group also showed a greater clinically meaningful improvement in the "Think Win-Win" of SHP (p = 0.043) and in the personal strength score (p = 0.025) and total score (p = 0.015) of the PTGI. CONCLUSIONS: Long-term cancer survivors can benefit from the Health Partner Program to become health coaches.

Phenotypic and functional maturation of dendritic cells induced by polysaccharide isolated from Paecilomyces cicadae.

Paecilomyces cicadae Miquel Samson is the anamorph of Cordyceps cicadae Shing and is used in functional foods for the prevention and treatment of various diseases. In the present study, we examined the effects of P. cicadae polysaccharide (PCP) on dendritic cell (DC) maturation. Phenotypic maturation of DCs by PCP was confirmed by the elevated expressions of CD80, CD86, major histocompatibility complex (MHC)-I, and MHC-II molecules and functional maturation by increased expression of interleukin-12, interleukin-1ß, and tumor necrosis factor-α, enhanced allogenic T cell stimulation, and decreased endocytosis. PCP induced the maturation of DCs from C3H/HeN and C57BL/6 mice but not from Toll-like receptor (tlr) 4⁻/⁻ knockout mice and TLR4-mutated C3H/HeJ mice, which suggests that TLR4 is the membrane receptor for PCP. PCP increased the degradation of inhibitor of nuclear factor-κB (NF-κB) α/ß, which enhanced the nuclear translocation of NF-κB p50/p65 and induced the phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinases, which are signaling molecules downstream of TLR4. These results indicate that PCP induces DC maturation through TLR4 signaling.