Mitochondrial Calcium Waves by Electrical Stimulation in Cultured Hippocampal Neurons.

Mitochondria are critical to cellular Ca2+ homeostasis via the sequestering of cytosolic Ca2+ in the mitochondrial matrix. Mitochondrial Ca2+ buffering regulates neuronal activity and neuronal death by shaping cytosolic and presynaptic Ca2+ or controlling energy metabolism. Dysfunction in mitochondrial Ca2+ buffering has been implicated in psychological and neurological disorders. Ca2+ wave propagation refers to the spreading of Ca2+ for buffering and maintaining the associated rise in Ca2+ concentration. We investigated mitochondrial Ca2+ waves in hippocampal neurons using genetically encoded Ca2+ indicators. Neurons transfected with mito-GCaMP5G, mito-RCaMP1h, and CEPIA3mt exhibited evidence of mitochondrial Ca2+ waves with electrical stimulation. These waves were observed with 200 action potentials at 40 Hz or 20 Hz but not with lower frequencies or fewer action potentials. The application of inhibitors of mitochondrial calcium uniporter and oxidative phosphorylation suppressed mitochondrial Ca2+ waves. However, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and N-methyl-d-aspartate receptor blockade had no effect on mitochondrial Ca2+ wave were propagation. The Ca2+ waves were not observed in endoplasmic reticula, presynaptic terminals, or cytosol in association with electrical stimulation of 200 action potentials at 40 Hz. These results offer novel insights into the mechanisms underlying mitochondrial Ca2+ buffering and the molecular basis of mitochondrial Ca2+ waves in neurons in response to electrical stimulation.

Benzo[a]pyrene represses synaptic vesicle exocytosis by inhibiting P/Q-type calcium channels in hippocampal neurons.

Humans are exposed to the common carcinogen benzo[a]pyrene (BaP) by ingesting contaminated foods and water or inhaling polluted air. Given the enriched lipids and reduced antioxidative properties in the brain and the accumulation of BaP in the brain due to its high lipophilicity, the brain is susceptible to BaP-induced toxicity. Exposure to BaP leads to impairments in learning and memory, increased anxiety behavior, and neuronal death. It induces protein dysfunctions in neuronal compartments that play essential roles in neuronal activity or physiology. However, the neurotoxicity of BaP on presynaptic terminals, which is crucial to neurotransmission by releasing synaptic vesicles that contain neurotransmitters, has not yet been investigated. In the present study, we investigated the toxicity of BaP at presynaptic terminals in living hippocampal neurons. These neurons were sourced from transgenic mice pups (postnatal 1-day, a total of 12 pups, equal numbers for each sex) that endogenously express synaptic vesicle-fused pHluorin, which is a green fluorescent protein that enables monitoring of synaptic vesicle dynamics. We observed that BaP suppressed synaptic vesicle exocytosis by inhibiting presynaptic Ca2+ entry via P/Q-type Ca2+ channels. Together with molecular docking simulation, we speculate that BaP and metabolites may bind to the P/Q Ca2+ channels. These results suggest the toxic mechanism of BaP exposure-induced abnormal behavior that provides a basis to evaluate the risk assessment of BaP-induced neurotoxicity.

Anti-inflammatory effect of Ailanthus altissima (Mill.) Swingle leaves in lipopolysaccharide-stimulated astrocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: Activated astrocytes are involved in the progression of neurodegenerative diseases. Traditionally, Ailanthus altissima (Mill.) Swingle, widely distributed in East Asia, has been used as a medicine for the treatment of fever, gastric diseases, and inflammation. Although A. altissima has been reported to play an anti-inflammatory role in peripheral tissues or cells, its role in the central nervous system (CNS) remains unclear. AIM OF THE STUDY: In the present study, we investigated the anti-inflammatory effects and mechanism of action of A. altissima in primary astrocytes stimulated by lipopolysaccharide (LPS). MATERIALS AND METHODS: A nitrite assay was used to measure nitric oxide (NO) production, and the tetrazolium salt 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was performed to determine cytotoxicity. The expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and mitogen-activated protein kinase (MAPK) were determined with western blotting. Reverse-transcription PCR was used to assess the expression of inflammatory cytokines. The levels of reactive oxygen species were measured using 2,7-dichlorodihydrofluorescein diacetate. Luciferase assay and immunocytochemistry were used for assessing nuclear factor-kappa B (NF-κB) transcription and p65 localization, respectively. Memory and social interaction were analyzed using the Y-maze and three-chamber tests, respectively. RESULTS: The ethanol extract of A. altissima leaves (AAE) inhibited iNOS and COX-2 expression in LPS-stimulated astrocytes. Moreover, AAE reduced the transcription of various proinflammatory mediators, hindered NF-κB activation, and suppressed extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) activation without p38 activation. Ultra-high performance liquid chromatography with mass spectrometry analysis revealed that AAE comprised ethyl gallate, quercetin, and kaempferol, along with luteolin, which has anti-inflammatory properties, and repressed LPS-induced nitrite levels and the nuclear translocation of p65. Finally, oral administration of AAE attenuated LPS-induced memory and social impairment in mice and repressed LPS-induced ERK and JNK activation in the cortices of mice. CONCLUSION: AAE could have therapeutic uses in the treatment of neuroinflammatory diseases via suppression of astrocyte activation.

Perception survey on the introduction of clinical performance examination as part of the national nursing licensing examination in Korea.

PURPOSE: The purpose of this study was to analyze opinions about the action plan for implementation of clinical performance exam as part of the national nursing licensing examination and presents the expected effects of the performance exam and aspects to consider regarding its implementation. METHODS: This study used a mixed-methods design. Quantitative data were collected by a questionnaire survey, while qualitative data were collected by focus group interviews with experts. The survey targeted 200 nursing professors and clinical nurses with more than 5 years of work experience, and the focus group interviews were conducted with 28 of professors, clinical instructors, and nurses at hospitals. RESULTS: First, nursing professors and clinical specialists agreed that the current written tests have limitations in evaluating examinees' ability, and that the introduction of a clinical performance exam will yield positive results. Clinical performance exam is necessary to evaluate and improve nurses' work ability, which means that the implementation of a performance exam is advisable if its credibility and validity can be verified. Second, most respondents chose direct performance exams using simulators or standardized patients as the most suitable format of the test. CONCLUSION: In conclusion, the current national nursing licensing exam is somewhat limited in its ability to identify competent nurses. Thus, the time has come for us to seriously consider the introduction of a performance exam. The prerequisites for successfully implementing clinical performance exam as part of the national nursing licensing exam are a professional training process and forming a consortium to standardize practical training.

[A phenomenological study on the experience of hurt and forgiveness of clinical nurses in Korea after loss of employment].

PURPOSE: The purpose of this study was to understand and analyze the experience of hurt and forgiveness of clinical nurses in Korea. METHODS: A phenomenological research method guided data collection and analysis. The subjects were a total of 5 nurses who had experienced hurt and forgiveness. Data was collected through individual in-depth interviews. All interviews were audio taped and transcribed verbatim. Coding was used to establish different concepts and categories. RESULTS: The following three common constituents have been found as a retrospective focus based on the primary hurt related to the clinical situation; recognizing their personal values, obtaining their view about forgiveness, as well as their view of self. CONCLUSION: The results of this study may contribute to health professionals working in various clinical settings to understand Korean nurses with hurt and forgiveness experiences.

[Development and application of a multidimensional suicide prevention program for Korean elders by utilizing a community network].

PURPOSE: The purpose of this study was to develop a multidimensional suicide prevention program for Korean elders by utilizing a community network and to evaluate its effect. METHODS: A non-equivalent control group pretest-posttest design was used. The subjects were recruited from two different elderly institutions located in D city and K province, Korea. Nineteen subjects in the control group received no intervention and 20 subjects in the experimental group received a multidimensional suicide prevention program. RESULTS: There were more significant decreases in depression, suicide ideation, and increases in life satisfaction in the experimental group compared to the control group. CONCLUSION: According to the above results, the multidimensional suicide prevention program for Korean elders decreased stressful events like depression, and suicide ideation and increased life satisfaction through the community network. These findings suggest that this program can be used as an efficient intervention for elders in a critical situation.

[A phenomenological study on the restoration experience for suicide ideation of Korean elders].

PURPOSE: The purpose of this study was to understand and analyze the experience of restoration among Korean elders with suicide ideation. METHODS: A phenomenological research method guided data collection and analysis. A total of five elders having had suicide ideation participated. Data were collected through individual in-depth interviews. All interviews were audio taped and transcribed verbatim. Coding was used to establish different concepts and categories. RESULTS: As the results of analysis, the following three constituents have been found as a retrospective focus based on the primary suicide ideation: expanding their view and facing reality, reconstructing their view about life and death as well as self. CONCLUSION: The results of this study may contribute to health professionals working at various crisis settings to understand Korean elders with suicide ideation.