Integrins in synapse regulation.

Integrins are a large family of extracellular matrix (ECM) receptors. In the developing and adult brain, many integrins are present at high levels at synapses. The tetrapartite structure of synapses - which comprises presynaptic and postsynaptic neurons, the ECM and glial processes - places synaptic integrins in an excellent position to sense dynamic changes in the synaptic environment and use this information to coordinate further changes in synapse structure and function that will shape neural circuit properties. Recent developments in our understanding of the cellular and physiological roles of integrins, which range from control of neural process outgrowth and synapse formation to regulation of synaptic plasticity and memory, enable us to attempt a synthesis of synaptic integrin function.

Astrocytes regulate heterogeneity of presynaptic strengths in hippocampal networks.

Dendrites are neuronal structures specialized for receiving and processing information through their many synaptic inputs. How input strengths are modified across dendrites in ways that are crucial for synaptic integration and plasticity remains unclear. We examined in single hippocampal neurons the mechanism of heterosynaptic interactions and the heterogeneity of synaptic strengths of pyramidal cell inputs. Heterosynaptic presynaptic plasticity that counterbalances input strengths requires N-methyl-d-aspartate receptors (NMDARs) and astrocytes. Importantly, this mechanism is shared with the mechanism for maintaining highly heterogeneous basal presynaptic strengths, which requires astrocyte Ca(2+) signaling involving NMDAR activation, astrocyte membrane depolarization, and L-type Ca(2+) channels. Intracellular infusion of NMDARs or Ca(2+)-channel blockers into astrocytes, conditionally ablating the GluN1 NMDAR subunit, or optogenetically hyperpolarizing astrocytes with archaerhodopsin promotes homogenization of convergent presynaptic inputs. Our findings support the presence of an astrocyte-dependent cellular mechanism that enhances the heterogeneity of presynaptic strengths of convergent connections, which may help boost the computational power of dendrites.

Genetic and Non-Genetic Factors Affecting the Quality of Anticoagulation Control and Vascular Events in Atrial Fibrillation.

BACKGROUND: Warfarin has a narrow therapeutic window. We hypothesized that genetic factors related to warfarin metabolism (CYP2C9) and activity (VKORC1) would show stronger associations than modifiable factors with the quality of anticoagulation control and risks for thromboembolism and hemorrhage. METHODS: In this retrospective cohort analysis, clinical and genetic data were collected from 380 patients with atrial fibrillation (AF) who were followed for an average observation period of 4 years. We evaluated the factors associated with time in therapeutic range (TTR, international normalized ratio [INR]: 2-3) and vascular events (either thromboembolic or hemorrhagic), including both genetic (CYP2C9 and VKORC1 genotype) and modifiable factors (anticoagulation service and warfarin dose assessment interval). RESULTS: The genotypic frequency of CYP2C9*3 (rs1057910) was 9.5% and that of VKORC1 1173C>T (rs9934438) was 16.3%. TTR showed dependence on VKORC1 polymorphism: TTR was higher in carriers of the VKORC1 1173C>T than of the VKORC1 TT genotype (61.7 ± 16.0% versus 56.7 ± 17.4%, P = .031). Multivariate testing showed that the VKORC1 genotype and anticoagulation service were independently related to labile INRs (TTR <65%). Vascular events were observed in 66 patients (18.4%) during the study period. A Cox proportional hazard model showed that the use of anticoagulation service and patients' characteristics, such as AF-thromboembolic risk (CHA2DS2-VASc score: Congestive heart failure, Hypertension, Age 75 years or older, Diabetes mellitus, previous Stroke or transient ischemic attack, Vascular disease, Age 65 to 74 years, female) and consequence (neurologic disability), but not genetic factors, were independently associated with vascular events. CONCLUSIONS: Both genetic factor (VKORC1 genotype) and clinical efforts (anticoagulation service) influenced the quality of anticoagulation control. However, clinical events were more strongly associated with patient characteristics and clinical efforts than with genetic factors.

Quercetin-rich onion peel extract suppresses adipogenesis by down-regulating adipogenic transcription factors and gene expression in 3T3-L1 adipocytes.

BACKGROUND: Onion peel contains a high amount of quercetin, which has been reported to have anti-cholesterol, antithrombotic and insulin-sensitizing properties. This study aimed to elucidate the anti-adipogenic effects of quercetin-rich onion peel extract (OPE) and to compare it with commercially available quercetin using 3T3-L1 preadipocytes. RESULTS: Without affecting cell viability, both OPE and quercetin averted adipogenesis, as characterized by dose-dependent decreases in intracellular triglyceride content and glycerol 3-phosphate dehydrogenase activity, but the effect was more pronounced with OPE than with quercetin. The mRNA expression levels of key adipogenic genes such as PPARγ, C/EBPα, FABP4, aP2 and LPL were decreased in a dose-dependent manner by both OPE and quercetin. CONCLUSION: The results indicate that OPE treatment significantly prevents intracellular lipid accumulation via hyperactivation of genes regulating lipolysis as compared with quercetin alone.

Is atrial fibrillation always a culprit of stroke in patients with atrial fibrillation plus stroke?

BACKGROUND: Some ischemic strokes in patients with atrial fibrillation (AF) are caused by noncardioembolic etiologies (AF-unrelated stroke), but not AF itself (AF-related stroke). However, most clinical trials on the risk of stroke in AF have not distinguished between these. We investigated the frequency and features of AF-unrelated versus AF-related strokes in patients with AF plus ischemic stroke. We hypothesized that certain clinical factors, including chronicity of AF, treatment at the time of stroke onset and echocardiographic findings, may help to discriminate between AF-related and AF-unrelated strokes. The mechanisms and antithrombotic medications at the time of stroke recurrence in the two groups were also examined. METHODS: Consecutive patients with ischemic stroke within 7 days of symptom onset and with AF were included. Patients were classified according to the previously published criteria. Clinical factors including CHADS2 and CHA2DS2-VASc scores and transthoracic echocardiographic (TTE) findings were evaluated. RESULTS: Of 522 patients, 424 (81.2%) were grouped as AF-related stroke and the remaining 90 (17.2%) were classified as AF-unrelated stroke. Among the patients with AF-unrelated stroke, 51 (9.8%) were categorized as possible large artery atherosclerosis and 38 (7.3%) as possible small artery occlusion; 1 patient (0.2%) was assigned to miscellaneous cause. The AF-related and AF-unrelated strokes had similar CHADS2 and CHA2DS2-VASc scores. However, compared to AF-unrelated stroke, AF-related stroke was independently associated with female sex (odds ratio, OR, 2.19; 95% confidence interval, CI, 1.18-4.05), sustained AF (OR, 2.09; 95% CI, 1.21-3.59), inadequate anticoagulation at stroke onset (OR, 3.21; 95% CI, 1.33-7.75) and left ventricular dysfunction on TTE (OR, 2.84; 95% CI, 1.40-5.74). We identified 26 patients who experienced 2 strokes during the study period. The initial stroke subtype was a strong predictor of the recurrent stroke mechanism (p < 0.001). Among 17 events of AF-related recurrent stroke in these subpopulation, only 2 strokes (11.8%) occurred in a setting of adequate anticoagulation, whereas 4 out of 9 patients (44.4%) who had AF-unrelated strokes at recurrence were sufficiently anticoagulated at the time of admission (p = 0.138). CONCLUSION: AF is not always a culprit of stroke in patients with AF plus ischemic stroke; approximately one sixth of these cases are unrelated to AF and have distinct characteristics compared to AF-related stroke. There are significant differences in terms of some clinical and TTE parameters between AF-related and AF-unrelated stroke. Future studies are warranted to optimize strategies for risk stratification, treatment and prevention of stroke in these patients.

Imaging neural circuit dynamics with a voltage-sensitive fluorescent protein.

Population signals from neuronal ensembles in cortex during behavior are commonly measured with EEG, local field potential (LFP), and voltage-sensitive dyes. A genetically encoded voltage indicator would be useful for detection of such signals in specific cell types. Here we describe how this goal can be achieved with Butterfly, a voltage-sensitive fluorescent protein (VSFP) with a subthreshold detection range and enhancements designed for voltage imaging from single neurons to brain in vivo. VSFP-Butterfly showed reliable membrane targeting, maximum response gain around standard neuronal resting membrane potential, fast kinetics for single-cell synaptic responses, and a high signal-to-noise ratio. Butterfly reports excitatory postsynaptic potentials (EPSPs) in cortical neurons, whisker-evoked responses in barrel cortex, 25-Hz gamma oscillations in hippocampal slices, and 2- to 12-Hz slow waves during brain state modulation in vivo. Our findings demonstrate that cell class-specific voltage imaging is practical with VSFP-Butterfly, and expand the genetic toolbox for the detection of neuronal population dynamics.

Molecular interaction between HAX-1 and XIAP inhibits apoptosis.

Caspase-3 is an important executor caspase that plays an essential role in apoptosis. Recently, HS1-associated protein X1 (HAX-1) was found to be a substrate of caspase-3. Although HAX-1 has serve multifunctional roles in cellular functions such as cell survival and calcium homeostasis, the detailed functional mechanism of HAX-1 remains still unclear. In this study, we performed proteomic experiments to identify the HAX-1 interactome. Through immunoprecipitation and 2D gel electrophoresis, we identified X-linked inhibitor of apoptosis protein (XIAP) as a novel HAX-1-interacting protein. By performing the GST pull-down assay, we defined the interaction domains in HAX-1 and XIAP, showing that HAX-1 binds to the BIR2 and BIR3 domains of XIAP whereas XIAP binds to the C-terminal domain of HAX-1. In addition, surface plasma resonance experiments showed that both BIR2 and BIR3 domains of XIAP bind to HAX-1 with affinity similar to that of full-length XIAP, indicating that either domain is necessary and sufficient for tight binding to HAX-1. Taken together with the observation that HAX-1 suppresses the polyubiquitination of XIAP, the cell viability assay results suggest that the formation of the HAX-1-XIAP complex inhibits apoptosis by enhancing the stability of XIAP against proteosomal degradation.

Altered Regional Cerebral Blood Flow Associated with Mood and Sleep in Shift Workers: Cerebral Perfusion Magnetic Resonance Imaging Study.

BACKGROUND AND PURPOSE: Shift work disrupts the body's circadian rhythms and increases the risk of health problems. Despite evidence of neuropsychological disturbances in shift workers (SW), the brain functional status as measured by brain perfusion in chronic shift work has not been evaluated previously. We investigated the regional cerebral blood flow (rCBF) in SW using perfusion MRI (pMRI) and evaluated the relationships between altered rCBF and sleep, mood, psychometric measures, and quality of life. METHODS: Fifteen rotational SW and 15 day workers (DW) were enrolled. The participants were all female nurses working at a university-affiliated hospital. During 2 weeks of actigraphy they underwent pMRI scanning and psychometric testing on the last day immediately after working. Demographic characteristics, insomnia, daytime sleepiness, and mood were compared between the groups. RESULTS: The participants were aged 35.3±2.9 years (mean±SD) and had been performing their current work for more than 2 years. The demographic characteristics did not differ between SW and DW, but the levels of insomnia, anxiety, depression, and hyperactivity-restlessness in psychometric measures were higher in SW than in DW. Cerebral perfusion in SW was significantly decreased in the cuneus, fusiform/parahippocampal gyri, and cerebellum of the right hemisphere, while it was increased in the inferior occipital gyrus of the left hemisphere. Perfusion changes in SW were significantly correlated with depression and insomnia severity. The onset and duration irregularity of sleep among SW were related to insomnia, mood, hyperactivity/ restlessness, and quality of life. CONCLUSIONS: SW experience considerably more insomnia and mood disturbances than do DW, and this is significantly related to perfusion changes in multiple brain areas.

HS 1-associated protein X-1 is cleaved by caspase-3 during apoptosis.

Caspase-3 (CASP3) plays a key role in apoptosis. In this study, HAX-1 was identified as a new substrate of CASP3 during apoptosis. HAX-1 was cleaved by CASP3 during etoposide-(ETO) induced apoptosis, and this event was inhibited by a CASP3-specific inhibitor. The cleavage site of HAX-1, at Asp(127), was located using N-terminal amino acid sequencing of in vitro cleavage products of recombinant HAX-1. Overexpression of HAX-1 inhibited ETO-induced apoptotic cell death. It also inhibited CASP3 activity. Together, these results suggest that HAX-1, a substrate of CASP3, inhibits the apoptotic process by inhibiting CASP3 activity.

Altered long-term synaptic plasticity and kainate-induced Ca2+ transients in the substantia gelatinosa neurons in GLU(K6)-deficient mice.

Functional kainate receptors are expressed in the spinal cord substantia gelatinosa region, and their activation contributes to bi-directional regulation of excitatory synaptic transmission at primary afferent synapses with spinal cord substantia gelatinosa neurons. However, no study has reported a role(s) for kainate receptor subtypes in long-term synaptic plasticity phenomena in this region. Using gene-targeted mice lacking glutamate receptor 5 (GLU(K5)) or GLU(K6) subunit, we here show that GLU(K6) subunit, but not GLU(K5) subunit, is involved in the induction of long-term potentiation of excitatory postsynaptic potentials, evoked by two different protocols: (1) high-frequency primary afferent stimulation (100 Hz, 3 s) and (2) low-frequency spike-timing stimulation (1 Hz, 200 pulses). In addition, GLU(K6) subunit plays an important role in the expression of kainate-induced Ca2+ transients in the substantia gelatinosa. On the other hand, genetic deletion of GLU(K5) or GLU(K6) subunit does not prevent the induction of long-term depression. These results indicate that unique expression of kainate receptors subunits is important in regulating spinal synaptic plasticity and thereby processing of sensory information, including pain.

Lack of Association of Clinical Factors (SAMe-TT2R2) with CYP2C9/VKORC1 Genotype and Anticoagulation Control Quality.

BACKGROUND AND PURPOSE: Advantages of new oral anticoagulations may be greater in atrial fibrillation (AF) patients of poor anticoagulation control with warfarin. The SAMe-TT2R2 scoring system, based on clinical variables, was recently developed to aid in identifying these patients. In this study, we investigated the association of this clinical composite score with genetic factors related warfarin dosing and the quality of anticoagulation control. METHODS: Clinical and genetic data were collected from 380 consecutive Korean patients with AF (CHA2DS2-VASc score, 3.5±1.8) who were followed for an average of 4 years. We evaluated factors associated with time in therapeutic range (TTR, INR 2-3), including the CYP2C9 and VKORC1 genotypes and the SAMe-TT2R2 score (Sex female, Age <60 years, Medical history [>two co-morbidities], Treatment [interacting drugs, e.g., amiodarone], Tobacco use within 2 years [doubled], and Race non-white [doubled]). RESULTS: The average SAMe-TT2R2 score was 3.4±0.9, range 2-7; and 153 patients (40.2%) had SAMe-TT2R2 scores ≥4. Time in specific INR ranges varied depending on the VKORC1 genotype but not with the CYP2C9 genotype or the SAMe-TT2R2 score. TTR was higher in patients with the VKORC1 1173C>T than in VKORC1 TT (61.7±16% vs. 56.7±17.4%, P=0.031). Multivariate testing showed that VKORC1 genotype but not the SAMe-TT2R2 score was significantly associated with labile INRs. There was no correlation between the SAMe-TT2R2 scores and pharmacogenetic data. CONCLUSIONS: A genetic factor, but none of the common clinical and demographic factors, as combined in the SAMe-TT2R2 score, was associated with the quality of anticoagulation control in Korean patients with AF.

Different Strategies for Transpancreatic Septotomy and Needle Knife Infundibulotomy Due to the Presence of Unintended Pancreatic Cannulation in Difficult Biliary Cannulation.

BACKGROUND/AIMS: Several precut techniques have been used to gain biliary access for difficult cases. The aim of this study was to evaluate the success and complication rates of two precut techniques, transpancreatic septotomy (TPS) and needle knife infundibulotomy (NKI), in difficult biliary cannulation due to the presence of unintended pancreatic cannulation. METHODS: Eighty-six patients who failed standard biliary cannulation were included. TPS was performed when we failed to achieve biliary access despite 5 minutes of attempted cannulation or when more than three attempted unintended pancreatic cannulations occurred. If deep cannulation was not achieved within 5 minutes for any duct, NKI was performed. If this failed, we crossed over to the other technique in the second attempt. RESULTS: The initial total success rate of biliary cannulation was 88.4% (86.6% for the TPS group and 94.7% for the NKI group, p=0.447). After crossover of the techniques, the final success rate was 95.3%. The complication rate was 20.9% in patients with TPS and 15.8% in patients with NKI (p=0.753). CONCLUSIONS: The use of different strategies based on the presence of unintended pancreatic cannulation may help increase the success rate for difficult biliary cannulation without increasing complication rates.

Activation of presynaptic group I metabotropic glutamate receptors enhances glutamate release in the rat spinal cord substantia gelatinosa.

The activation of group I metabotropic glutamate receptors (mGluRs) produces a long-term potentiation of sensory transmission in the substantia gelatinosa (SG) region of the spinal cord (Prog. Brain Res. 129 (2000) 115). The mechanism(s) responsible for the induction of this potentiation is not known. Using rat spinal cord slice preparation and patch-clamp recordings, here we show, that the activation of the group I mGluRs by (S)-3,5-dihydroxyphenylglycine (DHPG, 1 microM), the mGluR1/5 agonist, increased the frequency of both activity-dependent spontaneous EPSCs, and activity-independent miniature EPSCs (mEPSCs). However, DHPG did not affect amplitude of mEPSCs. The effects of DHPG were not seen in the presence of the preferential mGluR1 antagonist CPCCOEt (10 microM). On the other hand, 2-methyl-6-(phenylethynyl)-pyridine (10 microM), a selective mGluR5 antagonist, blocked the DHPG facilitation present during the wash-out of the drug. This novel facilitating effect of the group I mGluR activation on glutamate release is the first report of a direct facilitatory action of both mGluR1 and mGluR5 subtypes on sensory transmission in the spinal cord SG region. These results indicate the potential contribution of synaptic activation of these facilitatory autoreceptors in plasticity of primary afferent neurotransmission.

Protection against ovariectomy-induced bone loss by tranilast.

BACKGROUND: Tranilast (N-(3',4'-dimethoxycinnamonyl) anthranilic acid) has been shown to be therapeutically effective, exerting anti-inflammatory and anti-oxidative effects via acting on macrophage. We hypothesized that Tranilast may protect against oxidative stress-induced bone loss via action in osteoclasts (OCs) that shares precursors with macrophage. METHODOLOGY AND PRINCIPAL FINDINGS: To elucidate the role of Tranilast, ovariectomy (OVX)-induced bone loss in vivo and OC differentiation in vitro were evaluated by µCT and tartrate-resistant acid phosphatase staining, respectively. Oral administration of Tranilast protected against OVX-induced bone loss with decreased serum level of reactive oxygen species (ROS) in mice. Tranilast inhibited OC formation in vitro. Decreased osteoclastogenesis by Tranilast was due to a defect of receptor activator of nuclear factor-κB ligand (RANKL) signaling, at least partly via decreased activation of nuclear factor-κB and reduced induction and nuclear translocation of nuclear factor of activated T cells, cytoplasmic 1 (or NFAT2). Tranilast also decreased RANKL-induced a long lasting ROS level as well as TGF-ß to inhibit osteoclastogenesis. Reduced ROS caused by Tranilast was due to the induction of ROS scavenging enzymes (peroxiredoxin 1, heme oxygenase-1, and glutathione peroxidase 1) as well as impaired ROS generation. CONCLUSIONS/SIGNIFICANCE: Our data suggests the therapeutic potential of Tranilast for amelioration of bone loss and oxidative stress due to loss of ovarian function.

TNFRSF14 deficiency protects against ovariectomy-induced adipose tissue inflammation.

To elucidate the role of tumor necrosis factor receptor superfamily member 14 (TNFRSF14) in metabolic disturbance due to loss of ovarian function, ovariectomy (OVX) was performed in TNFRSF 14-knockout mice. OVX increased fat mass and infiltration of highly inflammatory CD11c cells in the adipose tissue (AT), which was analyzed by flow cytometry, and resulted in disturbance of glucose metabolism, whereas TNFRSF14 deficiency attenuated these effects. TNFRSF14 deficiency decreased recruitment of CD11c-expressing cells in AT and reduced the polarization of bone marrow-derived macrophages to M1. Upon engagement of LIGHT, a TNFRSF14 ligand, TNFRSF14 enhanced the expression of CD11c via generation of reactive oxygen species, suggesting a role of TNFRSF14 as a redox modulator. TNFRSF14 participated in OVX-induced AT inflammation via upregulation of CD11c, resulting in metabolic perturbation. TNFRSF14 could be used as a therapeutic target for the treatment of postmenopausal syndrome by reducing AT inflammation.

Severe rhabdomyolysis associated with concurrent use of simvastatin and sirolimus after cisplatin-based chemotherapy in a kidney transplant recipient.

OBJECTIVES: Cardiovascular disease is the most common cause of sickness and death for long-term kidney transplant recipients, and dyslipidemia is an important risk factor for developing cardiovascular disease. Lipid-lowering strategies, with the use of statins, have been shown to reduce the cardiovascular risks related to dyslipidemia, but concomitant use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and immunosuppressive agents may increase the risk of rhabdomyolysis owing to a drug-drug interaction. We report a case of simvastatin-induced rhabdomyolysis and acute kidney injury triggered by addition of sirolimus and cisplatin-based chemotherapy to a kidney transplant recipient who had previously tolerated chronic statin therapy.

Spontaneous Pneumomediastinum, Pneumopericardium, and Pneumothorax with Respiratory Failure in a Patient with AIDS and Pneumocystis jirovecii Pneumonia.

Spontaneous pneumothorax occurs in up to 35% of patients with Pneumocystis jirovecii pneumonia. However, spontaneous pneumomediastinum and pneumopericardium are uncommon complications in patients infected with human immunodeficiency virus, with no reported incidence rates, even among patients with acquired immunodeficiency syndrome (AIDS) and P. jirovecii pneumonia. We report a case of spontaneous pneumomediastinum, pneumopericardium, and pneumothorax with respiratory failure during treatment of P. jirovecii pneumonia in a patient with AIDS; the P. jirovecii infection was confirmed by performing methenamine silver staining of bronchoalveolar lavage specimens. This case suggests that spontaneous pneumomediastinum and pneumopericardium should be considered in patients with AIDS and P. jirovecii pneumonia.

A case of three consecutive events of acute myocardial infarctions in three different vessels.

A 51-year-old man was being admitted to the emergency department with chest pains. He had a history of acute myocardial infarction (MI) on two prior occasions and was successfully treated with drug eluting stents. He was diagnosed with 3 consecutive events of acute MI in 3 different vessels. The consecutive events of acute MI in different vessels are a very rare case. He did not have risk factors, such as coagulation abnormality, clopidogrel resistance, patient's compliance and vessel abnormality, except for his cigarette smoking. We reported the first case with 3 consecutive events of acute MI in each 3 vessels during a long-term interval.