Incidence of osteoporosis and ambient air pollution in South Korea: a population-based retrospective cohort study.

BACKGROUND: This study investigated the associations between exposure to ambient air pollutants and the incidence of osteoporosis using the Korean National Insurance Service-National Sample Cohort. METHODS: This nationwide, population-based, retrospective cohort study included 237,149 adults aged ≥40 years that did not have a diagnosis of osteoporosis at baseline between January 1, 2003, and December 31, 2015. Osteoporosis was defined as claim codes and prescriptions of bisphosphonates or selective estrogen receptor modulators at least twice annually. After matching values for PM10, NO2, CO, and SO2 during the 2002-2015 time period and PM2.5 in 2015 with residential areas, the incidence of osteoporosis was analyzed using a Cox proportional hazards regression model according to the quartile of average yearly concentrations of pollutants. RESULTS: Overall 22.2% of the study subjects, 52,601 (male: 5.6%, female: 37.6%) adults in total, were newly diagnosed with osteoporosis and treated. Exposure to PM10 was positively associated with incidence of osteoporosis (Q4: 1798 per 100,000 person-years vs. Q1: 1655 per 100,000 person-years). The adjusted hazard ratio (HR) with 95% confidence interval (CI) of Q4 in PM10 was 1.034 (1.009-1.062). The effect of PM10 on osteoporosis incidence was distinct in females (adjusted sub-HR: 1.065, 95% CI: 1.003-1.129), subjects aged < 65 years (adjusted sub-HR: 1.040, 95% CI: 1.010-1.072), and for residents in areas with low urbanization (adjusted sub-HR: 1.052, 95% CI: 1.019-1.087). However, there was no increase in osteoporosis based on exposure to NO2, CO, SO2, or PM2.5. CONCLUSIONS: Long-term exposure to PM10 was associated with newly diagnosed osteoporosis in Korean adults aged ≥40 years. This finding can aid in policy-making that is directed to control air pollution as a risk factor for bone health.

Synergistic efficacy and diminished adverse effect profile of composite treatment of several ADHD medications.

Although attention-deficit/hyperactivity disorder (ADHD) is widely studied, problems regarding the adverse effect risks and non-responder problems still need to be addressed. Combination pharmacotherapy using standard dose regimens of existing medication is currently being practiced mainly to augment the therapeutic efficacy of each drug. The idea of combining different pharmacotherapies with different molecular targets to alleviate the symptoms of ADHD and its comorbidities requires scientific evidence, necessitating the investigation of their therapeutic efficacy and the mechanisms underlying the professed synergistic effects. Here, we injected male ICR mice with MK-801 to induce ADHD behavioral condition. We then modeled a "combined drug" using sub-optimal doses of methylphenidate, atomoxetine, and fluoxetine and investigated the combined treatment effects in MK-801-treated mice. No sub-optimal dose monotherapy alleviated ADHD behavioral condition in MK-801-treated mice. However, treatment with the combined drug attenuated the impaired behavior of MK-801-treated animals. Growth impediment, sleep disturbances, or risk of substance abuse were not observed in mice treated subchronically with the combined drugs. Finally, we observed that the combined ADHD drug rescued alterations in p-AKT and p-ERK1/2 levels in the prefrontal cortex and hippocampus, respectively, of MK-801-treated mice. Our results provide experimental evidence of a possible new pharmacotherapy option in ameliorating the ADHD behavioral condition without the expected adverse effects. The detailed mechanism of action underlying the synergistic therapeutic efficacy and reduced adverse reaction by combinatorial drug treatment should be investigated further in future studies.

Hospital adverse outcomes of the elderly in a tertiary referral hospital: A prospective cohort study of 9,586 admissions.

OBJECTIVE: This study aimed to evaluate the hospital adverse outcomes (HAO) of admitted older adult patients in a large prospective cohort and investigate the demographic, economic, and health-related characteristics at risk of HAO in all older adult patients admitted in the general ward of a tertiary referral hospital. MATERIALS AND METHODS: We recruited admission episodes of older adult patients aged over 65 years who were admitted at the general ward of Konkuk University Medical Center, which is a tertiary referral hospital, from September 2016 to October 2017. Out of 9,586 admission episodes, 8,263 were included. Modified from the Geriatric Screening for Care-10, six common geriatric health issues, namely, dysphagia, polypharmacy, fecal incontinence, functional mobility, depression, and dementia, were evaluated. Fall, hospital-acquired pressure ulcer (HPU), and mortality were checked daily by experienced nurses during the patients' hospital stay. A logistic regression model was used, and P < 0.05 was the threshold of significance. RESULTS: The incidence rates of fall and HPU were 1.3 % and 4.0 %, respectively. The hospital mortality was 6.1 %. Older adult patients with dysphagia or dementia upon admission were significantly associated with an increased likelihood of falls. Furthermore, age, ER admission, low income, fecal incontinence, or functional immobility increased the HPU incidence. Meanwhile, age, male, ER admission, fecal incontinence, or functional immobility significantly increased the hospital mortality. CONCLUSION: All demographic, economic, and health-related characteristics, except for polypharmacy and depression, affect the incidence of HAO. Intervention to vulnerable older adult patients with HAO risk could improve the treatment outcome.

Astaxanthin Suppresses PM2.5-Induced Neuroinflammation by Regulating Akt Phosphorylation in BV-2 Microglial Cells.

Air pollution has become one of the most serious issues for human health and has been shown to be particularly concerning for neural and cognitive health. Recent studies suggest that fine particulate matter of less than 2.5 (PM2.5), common in air pollution, can reach the brain, potentially resulting in the development and acceleration of various neurological disorders including Alzheimer's disease, Parkinson's disease, and other forms of dementia, but the underlying pathological mechanisms are not clear. Astaxanthin is a red-colored phytonutrient carotenoid that has been known for anti-inflammatory and neuroprotective effects. In this study, we demonstrated that exposure to PM2.5 increases the neuroinflammation, the expression of proinflammatory M1, and disease-associated microglia (DAM) signature markers in microglial cells, and that treatment with astaxanthin can prevent the neurotoxic effects of this exposure through anti-inflammatory properties. Diesel particulate matter (Sigma-Aldrich) was used as a fine particulate matter 2.5 in the present study. Cultured rat glial cells and BV-2 microglial cells were treated with various concentrations of PM2.5, and then the expression of various inflammatory mediators and signaling pathways were measured using qRT-PCR and Western blot. Astaxanthin was then added and assayed as above to evaluate its effects on microglial changes, inflammation, and toxicity induced by PM2.5. PM2.5 increased the production of nitric oxide and reactive oxygen species and upregulated the transcription of various proinflammatory markers including Interleukin-1ß (IL-1ß), Interleukin-6 (IL-6), Tumor necrosis factor α (TNFα), inducible nitric oxide synthase (iNOS), triggering receptor expressed on myeloid cells 2 (TREM2), Toll-like receptor 2/4 (TLR2/4), and cyclooxygenase-2 (COX-2) in BV-2 microglial cells. However, the mRNA expression of IL-10 and arginase-1 decreased following PM2.5 treatment. PM2.5 treatment increased c-Jun N-terminal kinases (JNK) phosphorylation and decreased Akt phosphorylation. Astaxanthin attenuated these PM2.5-induced responses, reducing transcription of the proinflammatory markers iNOS and heme oxygenase-1 (HO-1), which prevented neuronal cell death. Our results indicate that PM2.5 exposure reformulates microglia via proinflammatory M1 and DAM phenotype, leading to neurotoxicity, and the fact that astaxanthin treatment can prevent neurotoxicity by inhibiting transition to the proinflammatory M1 and DAM phenotypes. These results demonstrate that PM2.5 exposure can induce brain damage through the change of proinflammatory M1 and DAM signatures in the microglial cells, as well as the fact that astaxanthin can have a potential beneficial effect on PM2.5 exposure of the brain.

The Experience of Providing Older Adult Patients with Transitional Care from an Acute Care Hospital to Home in Cooperation with a Public Health Center.

BACKGROUND: This study aimed to describe the experience of providing older adult patients with transitional care from an acute care hospital to home in cooperation with a public health center, in order to present the barriers to that care and suggest better organizational methods. METHODS: This was a cross-sectional study to show the results of the Geriatric Screening for Care-10 (GSC-10) and outcomes of transitional care. Among 659 hospitalized patients aged 65 years or above who lived in an administrative district, forty-five subjects were enrolled between June 24, 2019 and January 23, 2020. Within 48 hours of admission, using the 10 areas of GSC-10, they were assessed for cognitive impairment, depression, polypharmacy (5 or more medications), functional mobility, dysphagia, malnutrition, pain, and incontinence, and were reassessed before discharge. The transitional care plan (containing the treatment summary, the results of the GSC-10 assessment, and the post-discharge plan) was forwarded to a representative of the public health center, who provided continued disease management and various health care services, such as chronic disease and frailty care, and physical rehabilitation. RESULTS: Of all the participants, 64.4% had more than 1 GSC-10 concern. The most prevalent concerns were functional immobility (35.6%) and polypharmacy (22.2%). About 15.6% of the participants were readmitted to a nursing home or hospital. A total of 38 participants received the transitional care intervention. They received an average of 2.7 administered interventions. However, the rate of rejection was high (30.1%) and patients were visited an average of 16.5 days after discharge. CONCLUSION: Through our experience of providing transitional care from an acute care hospital to home in cooperation with a public health center, we expect that the transitional care suitable for the Korean medical situation could be established and successful.

Importance of Geriatric Syndrome Screening within 48 Hours of Hospitalization for Identifying Readmission Risk: A Retrospective Study in an Acute-Care Hospital.

BACKGROUND: Given the association between geriatric syndrome and hospital readmission, we evaluated the suitability of geriatric syndrome screening for care (GSC) in identifying readmission risk and suggested the appropriate time for GSC. METHODS: GSC considering cognitive impairment, depression, polypharmacy (five or more medications), functional mobility, dysphagia, malnutrition, pain, and incontinence was performed among 2,663 general ward inpatients aged 65 years or older within 48 hours after admission and again before discharge between November 2016 and October 2017. From each patient, fall events, pressure ulcers, potentially inappropriate medication use, and delirium were assessed at admission. Patients were divided into two groups on the basis of readmission within 1 year after the first admission. According to the screening period (at admission and before discharge) and in-hospital decline, we applied receiver operating characteristic curve analysis to compare the prevalence of clinical concerns between the readmission and no-readmission groups. We also used multiple logistic regression analysis to evaluate the risk of readmission according to the presence of geriatric syndrome and clinical outcomes. RESULTS: The 782 readmitted patients (29.4%) showed a higher rate of poor GSC than those who were not readmitted. Polypharmacy at admission was significantly correlated with readmission risk (area under the receiver operating characteristic curve=0.602). Fall events (odds ratio [OR]=4.36; 95% confidence interval [CI], 2.36-8.05), urinary incontinence (OR=4.21; 95% CI, 3.28-5.39), and depressive mood (OR=3.88; 95% CI, 2.69-5.59) at admission were risk factors for readmission. CONCLUSION: Geriatric syndromes assessed by GSC at admission was associated with an increased risk of readmission.

Applicability of the 48/6 Model of Care as a Health Screening Tool, and its Association with Mobility in Community-Dwelling Older Adults.

BACKGROUND: The 48/6 Model of Care is an integrative care initiative for improving the health outcomes of hospitalized older patients; however, its applicability in community-dwelling older adults as a health screening tool has not been investigated. The present study aimed to examine the applicability of this model, prevalence of dysfunction in 6 care areas, and its relationship with self-reported mobility in community-dwelling older adults. METHODS: This was a cross-sectional survey study of community-dwelling adults aged 65 or older. Participants were screened for problems using 9 items corresponding to the 6 care areas of the 48/6 Model of Care (cognitive functioning, functional mobility, pain management, nutrition and hydration, bladder and bowel management, and medication management). Mobility was assessed via the Life-Space Assessment (LSA). We examined the correlation between each screening item and the LSA. RESULTS: A total of 444 older adults (260 women, 58.6%) participated. The mean number of health problems was 2.3 ± 2.1, with the most common being pain, cognitive impairment, and urinary incontinence. These problems and LSA scores were significantly different by age groups. A multiple regression analysis showed that polypharmacy (ß = -10.567, P < 0.001), dysphagia (ß = -9.610, P = 0.021), and pain (ß = -7.369, P = 0.004) were significantly associated with life-space mobility after controlling for age. CONCLUSION: The 48/6 Model of Care is applicable to community-dwelling older adults, who show high prevalence of dysfunction in the 6 care areas. This study supports the role of the model in screening for the health status of older adults living in the community, and in estimating mobility.

Motor cortex hypointensity on susceptibility-weighted imaging: a potential imaging marker of iron accumulation in patients with cognitive impairment.

PURPOSE: To assess the prevalence and characteristics of motor cortex hypointensity on 3-T susceptibility-weighted imaging (SWI) in patients with cognitive impairment and examine its clinical significance. METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. A total of 127 patients with a clinical diagnosis of probable Alzheimer's disease (AD) (n = 32) or mild cognitive impairment (MCI) (n = 95) and 127 age- and sex-matched control subjects underwent 3-T brain magnetic resonance imaging. SWI was analyzed for both subjective visual scoring and the quantitative estimation of phase shift in the posterior bank of the motor cortex. A multivariate logistic regression analysis was performed to identify clinical and imaging variables associated with motor cortex hypointensity on SWI. RESULTS: Motor cortex hypointensity on SWI was observed in 94/127 cognitively impaired patients (74.0%) and 72/127 control subjects (56.7%) (p = 0.004). Age was the only variable that was significantly associated with motor cortex hypointensity in patients with cognitive impairment (odds ratio, 1.15; 95% confidence interval, 1.065-1.242; p < 0.001). The quantitative analysis confirmed a significant increase in phase shifting in the posterior bank of the motor cortex in patients with positive motor cortex hypointensity on SWI (p < 0.001). CONCLUSION: Motor cortex hypointensity on SWI was more frequently found in patients with cognitive impairment than in age-matched controls and was positively associated with age. Thus, it may be a potential imaging marker of iron accumulation in patients with MCI or AD.

Tenovin-1 Induces Senescence and Decreases Wound-Healing Activity in Cultured Rat Primary Astrocytes.

Brain aging induces neuropsychological changes, such as decreased memory capacity, language ability, and attention; and is also associated with neurodegenerative diseases. However, most of the studies on brain aging are focused on neurons, while senescence in astrocytes has received less attention. Astrocytes constitute the majority of cell types in the brain and perform various functions in the brain such as supporting brain structures, regulating blood-brain barrier permeability, transmitter uptake and regulation, and immunity modulation. Recent studies have shown that SIRT1 and SIRT2 play certain roles in cellular senescence in peripheral systems. Both SIRT1 and SIRT2 inhibitors delay tumor growth in vivo without significant general toxicity. In this study, we investigated the role of tenovin-1, an inhibitor of SIRT1 and SIRT2, on rat primary astrocytes where we observed senescence and other functional changes. Cellular senescence usually is characterized by irreversible cell cycle arrest and induces senescence- associated ß-galactosidase (SA-ß-gal) activity. Tenovin-1-treated astrocytes showed increased SA-ß-gal-positive cell number, senescence-associated secretory phenotypes, including IL-6 and IL-1ß, and cell cycle-related proteins like phospho-histone H3 and CDK2. Along with the molecular changes, tenovin-1 impaired the wound-healing activity of cultured primary astrocytes. These data suggest that tenovin-1 can induce cellular senescence in astrocytes possibly by inhibiting SIRT1 and SIRT2, which may play particular roles in brain aging and neurodegenerative conditions.

Association of Geriatric Syndromes with Urinary Incontinence according to Sex and Urinary-Incontinence-Related Quality of Life in Older Inpatients: A Cross-Sectional Study of an Acute Care Hospital.

BACKGROUND: Geriatric syndromes are associated with morbidity and poor quality of life (QOL). Urinary incontinence (UI) is one of the most prevalent geriatric syndromes. However, there is little research on the association of UI and UI-related QOL with other geriatric syndromes. We investigated the relationship between geriatric syndromes and UI according to gender and UI-related QOL among older inpatients. METHODS: This study was conducted among 444 older inpatients (aged 65 years and older) between October 2016 and July 2017. We examined geriatric syndromes and related factors involving cognitive impairment, delirium, depression, mobility decline, polypharmacy, undernutrition, pain, and fecal incontinence. UI-related QOL was assessed using the International Consultation on Incontinence Questionnaire-Short Form. Multiple logistic regression analysis was used to evaluate these associations. RESULTS: Geriatric syndromes and related factors were associated with UI. Mobility decline (odds ratio [OR], 4.16; 95% confidence interval [CI], 2.29-7.56), polypharmacy (OR, 3.35; 95% CI, 1.89-5.92), and pain (OR, 6.80; 95% CI, 3.53-13.09) were related to UI in both genders. Especially, delirium (OR, 7.55; 95% CI, 1.61-35.44) and fecal incontinence (OR, 10.15; 95% CI, 2.50-41.17) were associated with UI in men, while cognitive impairment (OR, 4.19; 95% CI, 1.14-15.44) was significantly associated with UI in women. Patients with depression were more likely to have poor UI-related QOL (OR, 8.54; 95% CI, 1.43-51.15). CONCLUSION: UI was associated with different geriatric syndromes and related factors according to gender. Care for patients with depression, related to poor UI-related QOL, should be considered in primary care to improve the UI-related QOL of these individuals.

Tyrosine kinase Fyn regulates iNOS expression in LPS-stimulated astrocytes via modulation of ERK phosphorylation.

The high concentrations of nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) in activated glial cells in response to neuroinflammatory stimuli have neurotoxic effects on the brain. At basal levels, iNOS expression is low, and proinflammatory stimuli induce iNOS expression in astrocytes, microglia, and oligodendrocytes. Fyn, a non-receptor tyrosine kinase, regulates iNOS expression in several types of immune cells. However, its role in stimulated astrocytes is less clear. In this study, we investigated the role of Fyn in the regulation of lipopolysaccharide (LPS)-induced iNOS expression in astrocytes from mice and rats. Intracerebroventricular LPS injections in cortical regions enhanced iNOS mRNA and protein levels, which were increased in Fyn-deficient mice. Accordingly, LPS-induced nitrite production was enhanced in primary astrocytes cultured from Fyn-deficient mice or rats. Similar results were observed in cultured astrocytes after the siRNA-induced knockdown of Fyn expression. Finally, we observed increased LPS-induced extracellular signal-regulated protein kinase (ERK) activation in Fyn-deficient astrocytes. These results suggested that Fyn has a regulatory role in iNOS expression in astrocytes during neuroinflammatory responses.

Chronic cerebral hypoperfusion induces post-stroke dementia following acute ischemic stroke in rats.

BACKGROUND: Post-stroke dementia (PSD) is one of the major consequences after stroke. Chronic cerebral hypoperfusion (CCH) can induce vascular cognitive impairment and potentiate amyloid pathology. We investigated how CCH contributes to the development of PSD after stroke in the context of neuroinflammation and amyloid pathology. METHODS: We designed a unique animal model for PSD. We performed middle cerebral artery occlusion (MCAO) surgery in rats mimicking acute territorial infarct, which was followed by bilateral common carotid artery occlusion (BCCAo) surgery mimicking CCH. We performed behavioral tests including neurologic function test and water maze task and histological investigations including neuroinflammation, neuronal cell death, amyloid pathology, and aquaporin 4 (AQP4) distribution. RESULTS: Spatial memory was synergistically impaired when BCCAo was superimposed on MCAO. Neuroinflammation with astroglial or microglial activation and amyloid pathology were enhanced in the ipsilateral cortex, thalamus, and hippocampus when BCCAo was superimposed on MCAO. Glymphatic pathway-related AQP4 distribution changed from perivascular to parenchymal pattern. CONCLUSIONS: Our experimental results suggest that CCH may contribute to the development of PSD by interfering with amyloid clearance through the glymphatic pathway and concomitant neuroinflammation. Therapeutic strategy to clear brain metabolic waste through the glymphatic pathway may be a promising approach to prevent PSD after stroke.

Occupational Attainment as Risk Factor for Progression from Mild Cognitive Impairment to Alzheimer's Disease: A CREDOS Study.

High occupational attainment has been known as a marker of cognitive reserve. Previous studies in the general population have shown that high occupational attainment is associated with reduced risk of Alzheimer's disease (AD). However, few studies have assessed the effect of occupational attainment on the clinical course of mild cognitive impairment (MCI). In this study, we evaluated whether individuals with high occupational attainment show more frequent progression from MCI to AD. Participants (n = 961) with MCI were recruited from a nationwide, hospital-based multi-center cohort, and were followed for up to 60 months (median: 17.64, interquartile range [12.36, 29.28]). We used Cox regression for competing risks to analyze the effect of occupational attainment on development of AD, treating dementia other than AD as a competing risk. Among the 961 individuals with MCI, a total of 280 (29.1%) converted to dementia during the follow-up period. The risk of progression to AD was higher in the individuals with high occupational attainment after controlling for potential confounders (hazard ratio = 1.83, 95% confidence interval = 1.25-2.69, p = 0.002). High occupational attainment in individuals with MCI is an independent risk factor for higher progression rate of MCI to AD. This result suggests that the protective effect of high occupational attainment against cognitive decline disappears in the MCI stage, and that careful assessment of occupational history can yield important clinical information for prognosis in individuals with MCI.

Which Stratum of Urban Elderly Is Most Vulnerable for Dementia?

Many factors associated with a patient's lifestyle may disrupt timely access to dementia diagnosis and management. The aim of this study was to compare characteristics of lifestyle factors at the time of initial evaluation for dementia across degrees of dementia, and to identify risk factors relating to late detection of dementia, in order to understand the various lifestyle barriers to timely recognition of the disease. We reviewed medical records of 1,409 subjects who were diagnosed as dementia among 35,723 inhabitants of Gwangjin-gu. Dementia severity was divided into three degrees. Age, sex, education, income, smoking, heavy drinking, physical activity, religion, and living conditions were evaluated. There was a significantly greater proportion of individuals who were old age, female, less educated, who had never smoked or drank heavily, without physical activity, with no religious activity and living with family other than spouse in the severe dementia group. The lifestyle risks of late detection were old age, lower education, less social interactions, less physical activity or living with family. We can define this group of patients as the vulnerable stratum to dementia evaluation. Health policy or community health services might find ways to better engage patients in this vulnerable stratum to dementia.

Patterns of Brain Iron Accumulation in Vascular Dementia and Alzheimer's Dementia Using Quantitative Susceptibility Mapping Imaging.

BACKGROUND: Emerging evidence suggests that the excessive accumulation of iron in subcortical and deep gray matter has been related to dementia. However, the presence and pattern of iron accumulation in vascular dementia (VaD) and Alzheimer's disease (AD) are rarely investigated. OBJECTIVE: To examine and compare the pattern and presence of brain iron accumulation of VaD and AD using quantitative susceptibility mapping (QSM). MATERIALS AND METHODS: Twelve patients with VaD, 27 patients with AD, and 18 control subjects were recruited in this institutional review-board approved study. Susceptibility maps were reconstructed from a three-dimensional multiecho spoiled gradient-echo sequence. Four regions of interest were drawn manually on QSM images, namely the globus pallidus, putamen, caudate nucleus, and pulvinar nucleus of the thalamus. Comparisons of patient demographics, and iron concentrations among the VaD, AD, and control subjects were assessed using analysis of variance and post-hoc analyses. The relationships of age and cognitive state with susceptibility values were assessed using partial correlation analysis. RESULTS: In VaD and AD, overall susceptibility values were higher than those of control subjects. A significant difference in susceptibility values was found in the putamen and caudate nucleus (p <  0.001 and p = 0.002, respectively). However, susceptibility values did not differ between VaD and AD. Age and cognitive deficit severity were not related to susceptibility values in the VaD and AD groups. CONCLUSION: Increased iron deposition in the putamen and caudate nucleus in VaD and AD patients was not associated with age or the severity of cognitive deficits. Further evaluations are needed to determine the temporal changes in iron load and their diagnostic role in dementia pathology.

Ginkgo biloba Extract (EGb 761®) Inhibits Glutamate-induced Up-regulation of Tissue Plasminogen Activator Through Inhibition of c-Fos Translocation in Rat Primary Cortical Neurons.

EGb 761(®) , a standardized extract of Ginkgo biloba leaves, has antioxidant and antiinflammatory properties in experimental models of neurodegenerative disorders such as stroke and Alzheimer's disease. Tissue plasminogen activator (tPA) acts a neuromodulator and plays a crucial role in the manifestation of neurotoxicity leading to exaggerated neuronal cell death in neurological insult conditions. In this study, we investigated the effects of EGb 761 on the basal and glutamate-induced activity and expression of tPA in rat primary cortical neurons. Under basal condition, EGb 761 inhibited both secreted and cellular tPA activities, without altering tPA mRNA level, as modulated by the activation of p38. Compared with basal condition, EGb 761 inhibited the glutamate-induced up-regulation of tPA mRNA resulting in the normalization of overt tPA activity and expression. c-Fos is a component of AP-1, which plays a critical role in the modulation of tPA expression. Interestingly, EGb 761 inhibited c-Fos nuclear translocation without affecting c-Fos expression in glutamate-induced rat primary cortical neurons. These results demonstrated that EGb 761 can modulate tPA activity under basal and glutamate-stimulated conditions by both translational and transcriptional mechanisms. Thus, EGb 761 could be a potential and effective therapeutic strategy in tPA-excessive neurotoxic conditions.

Valproic acid increases NO production via the SH-PTP1-CDK5-eNOS-Ser(116) signaling cascade in endothelial cells and mice.

Valproic acid (VPA) with its inhibitory activity of histone deacetylase has been used in the treatment of epilepsy and bipolar disorder associated with cerebrovascular dysfunction. Because nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays a role in the maintenance of vascular function, NO is likely to mediate VPA׳s drug effect, but its effect on NO production remains controversial. We investigated whether and how VPA regulates NO production in bovine aortic endothelial cells (BAECs) and mice. VPA increased NO production in BAECs, which was accompanied by a decrease in phosphorylation of eNOS at serine 116 (eNOS-Ser(116)) and cyclin-dependent kinase 5 at tyrosine 15 (CDK5-Tyr(15)). Ectopic expression of p25, a CDK5 activator, restored the VPA-inhibited eNOS-Ser(116) phosphorylation. In silico analysis revealed that the CDK5-Tyr(15) residue might be a substrate for SH2 domain-containing protein tyrosine phosphatase 1 (SH-PTP1), and CDK5 actually interacted with SH-PTP1. VPA increased SH-PTP1 expression and its activity. Stibogluconate, a specific SH-PTP1 inhibitor, reversed the VPA-inhibited phosphorylation of CDK5-Tyr(15) and eNOS-Ser(116). Knockdown of SH-PTP1 using small interfering RNA also reversed all the observed effects of VPA. Finally, both serum NO level and acetylcholine-induced aortic relaxation increased in VPA-medicated male mice. These increases were accompanied by increased SH-PTP1 expression and decreased phosphorylation of CDK5-Tyr(15) and eNOS-Ser(116) in mouse aortas. In conclusion, VPA increases NO production by inhibiting the CDK5-Tyr(15)-eNOS-Ser(116) phosphorylation axis; this process is mediated by SH-PTP1. VPA may be useful in the treatment of NO-related cerebrocardiovascular diseases.

Resveratrol down-regulates a glutamate-induced tissue plasminogen activator via Erk and AMPK/mTOR pathways in rat primary cortical neurons.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene, RSV) is a polyphenolic compound present in a variety of plant species (including grapes) that produces a myriad of biological activities including anti-inflammatory, antioxidant and neuroprotective effects. In this study, we investigate the effects of resveratrol on the basal and glutamate-stimulated expression and activity of a tissue plasminogen activator (tPA) that plays neuromodulatory or neurotoxic roles in many different neurological situations. Under basal conditions, resveratrol decreased the tPA expression and activity without affecting the tPA mRNA level in rat primary cortical neurons. RSV induced AMPK phosphorylation and inhibited mTOR phosphorylation. Inhibition of AMPK phosphorylation using compound C prevented resveratrol-induced down-regulation of tPA activity. This suggested that AMPK/mTOR-dependent translational inhibition contributes to the down-regulation of the tPA. Under glutamate-stimulated conditions of rat primary cortical neurons, tPA activity and expression were increased along with increased tPA mRNA expression but afterward treatment of RSV inhibited the glutamate-induced increase in tPA activity and expression and tPA mRNA expression. Glutamate stimulation induced activation of Akt and MAPK pathways as well as mTOR which were inhibited by RSV. Interestingly, the Erk pathway inhibitor U0126, but neither PI3K-Akt inhibitor LY294002 nor p38 inhibitor SB203580, mimicked the inhibitory action of RSV on glutamate-induced tPA up-regulation. This suggested the essential role of Erk in the transcriptional up-regulation of tPA expression, which is targeted by RSV. Glutamate stimulation induced neuronal cell death as determined by PI staining and MTT assay. However, RSV protected the cultured rat primary cortical neurons from glutamate-induced cell death as paralleled with the changes in tPA expression. These results suggested that RSV can modulate tPA activity under basal and stimulated conditions by both translational and transcriptional mechanisms. The regulation of the tPA by RSV provides additional therapeutic targets on top of the growing number of molecular substrates of RSV's action in the brain.

NADPH oxidase 1, a novel molecular source of ROS in hippocampal neuronal death in vascular dementia.

AIMS: Chronic cerebral hypoperfusion (CCH) is a common pathological factor that contributes to neurodegenerative diseases such as vascular dementia (VaD). Although oxidative stress has been strongly implicated in the pathogenesis of VaD, the molecular mechanism underlying the selective vulnerability of hippocampal neurons to oxidative damage remains unknown. We assessed whether the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) complex, a specialized superoxide generation system, plays a role in VaD by permanent ligation of bilateral common carotid arteries in rats. RESULTS: Male Wistar rats (10 weeks of age) were subjected to bilateral occlusion of the common carotid arteries (two-vessel occlusion [2VO]). Nox1 expression gradually increased in hippocampal neurons, starting at 1 week after 2VO and for approximately 15 weeks after 2VO. The levels of superoxide, DNA oxidation, and neuronal death in the CA1 subfield of the hippocampus, as well as consequential cognitive impairment, were increased in 2VO rats. Both inhibition of Nox by apocynin, a putative Nox inhibitor, and adeno-associated virus-mediated Nox1 knockdown significantly reduced 2VO-induced reactive oxygen species generation, oxidative DNA damage, hippocampal neuronal degeneration, and cognitive impairment. INNOVATION AND CONCLUSION: We provided evidence that neuronal Nox1 is activated in the hippocampus under CCH, causing oxidative stress and consequential hippocampal neuronal death and cognitive impairment. This evidence implies that Nox1-mediated oxidative stress plays an important role in neuronal cell death and cognitive dysfunction in VaD. Nox1 may serve as a potential therapeutic target for VaD.

Proteinase 3 induces oxidative stress-mediated neuronal death in rat primary cortical neuron.

The recruitment of neutrophils into the cerebral microcirculation occurs, especially, in acute brain diseases like a focal cerebral ischemia and plays important role in pathological processes. Proteinase 3 is one of the three major proteinases expressed in neutrophils but no reports are available whether proteinase 3 can modulate neuronal survival. In this study, treatment of cultured rat primary cortical neuron with proteinase 3 induced overt reactive oxygen species production and decreased total glutathione contents as well as disruption of mitochondrial transmembrane potential. Proteinase 3 induced neuronal cell death as evidenced by MTT analysis as well as propidium iodide staining, which was prevented by pretreatment with an antioxidant, N-acetyl cysteine. Proteinase 3 increased activation of procaspase-3 and altered expression level of apoptotic regulator proteins, such as Bcl-2, Bax, and Bcl-xL. Similar to in vitro data, a direct microinjection of proteinase 3 into striatum of rat brain induced neuronal death, which was mediated by reactive oxygen species. These results suggest that proteinase 3 is new essential regulator of neuronal cell death pathway in a condition of excess neutrophil encounter in neuroinflammatory conditions.