Spontaneously Released Research Articles

Isolation of spontaneously‐released brain extracellular vesicles: implications for brain pathology

AbstractBackgroundIn the era of Precision Medicine, extracellular vesicles (EVs) exhibit great potential for the theragnostic of brain disorders such as Alzheimer’s disease (AD), a complex disease with no effective treatment and poorly understood risk factors, where pathological heterogeneity and diverse clinical presentations complicate the development of precise patient‐tailored therapies. Thus, the collection and characterization of physiologically relevant EVs, as well as the study of its precipitating/risk factors, are of the utmost importance. However, standard brain EV isolation approaches rely on tissue dissociation, which can contaminate EV preparations with intracellular vesicles.MethodBased on a multiscale analysis, including cryo‐EM, label‐free proteomics, and ExoView, we hereby present a novel purification method of small EVs (sEVs) based on the spontaneous release of EVs from the brain.ResultOur advanced EVs analysis demonstrated that our method represents an efficient purification method that captures a small EV‐enriched population spontaneously released by mouse and human brain tissue. In addition, we tested the significance of the release method under conditions where biogenesis/secretion of sEVs was pharmacologically manipulated and under exposure to chronic stress, a clinically‐relevant precipitant of AD. Here we found that the released method monitors the drug‐evoked inhibition or enhancement of sEVs secretion in a very sensitive manner, while chronic stress induces the secretion of brain exosomes accompanied by memory loss and mood deficits suggesting a potential role of sEVs in the brain response to stress and related stress‐driven brain pathologies.ConclusionOverall, this method will contribute to the characterization of the biomarker profile of physiologically relevant brain‐derived sEVs in brain function and pathology.

Spontaneous and multifaceted ATP release from astrocytes at the scale of hundreds of synapses.

Astrocytes participate in information processing by releasing neuroactive substances termed gliotransmitters, including ATP. Individual astrocytes come into contact with thousands of synapses with their ramified structure, but the spatiotemporal dynamics of ATP gliotransmission remains unclear, especially in physiological brain tissue. Using a genetically encoded fluorescent sensor, GRABATP1.0 , we discovered that extracellular ATP increased locally and transiently in absence of stimuli in neuron-glia co-cultures, cortical slices, and the anesthetized mouse brain. Spontaneous ATP release events were tetrodotoxin-insensitive but suppressed by gliotoxin, fluorocitrate, and typically spread over 50-250 μm2 area at concentrations capable of activating purinergic receptors. Besides, most ATP events did not coincide with Ca2+ transients, and intracellular Ca2+ buffering with BAPTA-AM did not affect ATP event frequency. Clustering analysis revealed that these events followed multiple distinct kinetics, and blockade of exocytosis only decreased a minor group of slow events. Overall, astrocytes spontaneously release ATP through multiple mechanisms, mainly in non-vesicular and Ca2+ -independent manners, thus potentially regulating hundreds of synapses all together.

A novel isolation method for spontaneously released extracellular vesicles from brain tissue and its implications for stress-driven brain pathology

BackgroundExtracellular vesicles (EVs), including small EVs (sEVs) such as exosomes, exhibit great potential for the diagnosis and treatment of brain disorders, representing a valuable tool for precision medicine. The latter demands high-quality human biospecimens, especially in complex disorders in which pathological and specimen heterogeneity, as well as diverse individual clinical profile, often complicate the development of precision therapeutic schemes and patient-tailored treatments. Thus, the collection and characterization of physiologically relevant sEVs are of the utmost importance. However, standard brain EV isolation approaches rely on tissue dissociation, which can contaminate EV fractions with intracellular vesicles.MethodsBased on multiscale analytical platforms such as cryo-EM, label-free proteomics, advanced flow cytometry, and ExoView analyses, we compared and characterized the EV fraction isolated with this novel method with a classical digestion-based EV isolation procedure. Moreover, EV biogenesis was pharmacologically manipulated with either GW4869 or picrotoxin to assess the validity of the spontaneous-release method, while the injection of labelled-EVs into the mouse brain further supported the integrity of the isolated vesicles.ResultsWe hereby present an efficient purification method that captures a sEV-enriched population spontaneously released by mouse and human brain tissue. In addition, we tested the significance of the release method under conditions where biogenesis/secretion of sEVs was pharmacologically manipulated, as well as under animals’ exposure to chronic stress, a clinically relevant precipitant of brain pathologies, such as depression and Alzheimer’s disease. Our findings show that the released method monitors the drug-evoked inhibition or enhancement of sEVs secretion while chronic stress induces the secretion of brain exosomes accompanied by memory loss and mood deficits suggesting a potential role of sEVs in the brain response to stress and related stress-driven brain pathology.ConclusionsOverall, the spontaneous release method of sEV yield may contribute to the characterization and biomarker profile of physiologically relevant brain-derived sEVs in brain function and pathology.7SKHktGsByupRjRZYNwNfMVideo

Spontaneous Release of Metalloradicals and Coordinatively Unsaturated Species in Asymmetric Iridium Dimers to Promote C-N Bond Formation

An unusual iridium dimer 1, [(4-cpbo)Ir(μ-Cl)(μ-O)Ir(4-cpbo)] (4-cpbo = 4-chlorophenylbenzoxazolato-N,C2), was obtained by the oxidative addition of oxygen and reductive elimination of chlorine from a precursor [(4-cpbo)2Ir(μ-Cl)]2. This iridium dimer 1 has a metastable structure with an asymmetric bridge, can spontaneously release metalloradicals and coordinatively unsaturated species in solution at room temperature, and exhibits high catalytic ability for synthetic applications.

PREDICTIVE FACTORS OF SPONTANEOUS RELEASE OF VITREOMACULAR TRACTION: A Systematic Review and Meta-Analysis.

To review predictive factors of spontaneous vitreomacular traction (VMT) release. A systematic literature search was performed on Ovid MEDLINE, Embase, and Cochrane Library. Studies comparing spontaneously released VMT to persistent VMT were included. A meta-analysis was performed using a random effects model, and weighted mean difference, risk ratio (RR), and 95% confidence intervals (95% CI) were reported as appropriate. Of a search of 258 studies, 12 studies were included, from which 272 of 934 eyes (29%) underwent spontaneous release. Mean age was 70.0 years, 37.2% of patients were men, and mean follow-up was 22.0 months. Significant predictive factors for spontaneous release were smaller VMT diameter (n = 177; weighted mean difference = -212.48 µm, 95% CI = [-417.36, -7.60], P = 0.04), epiretinal membrane absence (n = 162; RR = 2.17, 95% CI = [1.18, 3.97], P = 0.01), and right eye involvement (n = 76; RR = 2.10, 95% CI = [1.14, 3.88], P = 0.02). Nonsignificant factors were age, initial best-corrected visual acuity, sex, ocular comorbidity, fellow-eye posterior vitreous detachment, previous intravitreal injection, and VMT classification with focal defined as ≤400 µm. Mean release time was 15.3 months (n = 212). Mean best-corrected visual acuity improved from 0.34 ± 0.21 (Snellen 20/44) to 0.20 ± 0.58 logMAR (Snellen 20/32) postrelease (n = 121). Smaller VMT diameter, epiretinal membrane absence, and right eye involvement may support spontaneous VMT release. If patients have tolerable symptoms, clinicians may consider observation in patients with these predictive factors.

Photocoagulation-associated spontaneous release of epiretinal membrane secondary to retinal vascular tumor: case series of 8 cases.

To evaluate the secondary epiretinal membrane (ERM) response after photocoagulation in retinal vascular tumor. This retrospective interventional case series included 8 patients (8 eyes) who were diagnosed with retinal vascular tumor and secondary ERM. All eyes were treated with photocoagulation and underwent comprehensive ophthalmologic examinations at baseline and at each follow-up. Of the 8 eyes with retinal vascular tumor and associated ERM, 4 eyes (50%) were von Hippel and 4 eyes (50%) were vasoproliferative tumor of the retina. The mean follow-up time was 12.63 ± 14.64 (range, 4-51) months. The BCVA in the eyes at baseline was 1.16 ± 1.10 logMAR (range, HM to 20/40). ERM located in the macular region in 100% of the eyes and led to CME with a mean central foveal thickness of 497.6 ± 147.7 μm (range, 294-736 μm) at presentation. After photocoagulation, the ERM spontaneously peeled in 7 of 8 eyes (87.5%), among which one case required surgical treatment due to complicating tractional retinal detachment. After ERM peeling without complications, 6 eyes recovered normal macular structure, with an improved BCVA in 5 eyes and a stable BCVA in 1 eye. Laser photocoagulation is necessary and effective treatment for retinal vascular tumor. After laser photocoagulation, retinal vascular tumor-related ERM spontaneously released in 75% of the cases, without complication and surgical intervention.

Vascular endothelial growth factors and angiopoietins as new players in mastocytosis

Mastocytosis is a disorder characterized by the abnormal proliferation and/or accumulation of mast cells in different organs. More than 90% of patients with systemic mastocytosis have a gain-of-function mutation in codon 816 of the KIT receptor on mast cells (MCs). The symptoms of mastocytosis patients are related to the MC-derived mediators that exert local and distant effects. MCs produce angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs) and angiopoietins (ANGPTs). Serum concentrations of VEGF-A, VEGF-C, VEGF-D, ANGPT1 and ANGPT2 were determined in 64 mastocytosis patients and 64 healthy controls. Intracellular concentrations and spontaneous release of these mediators were evaluated in the mast cell lines ROSAKIT WT and ROSA KIT D816V and in human lung mast cells (HLMCs). VEGF-A, ANGPT1, ANGPT2 and VEGF-C concentrations were higher in mastocytosis patients compared to controls. The VEGF-A, ANGPT2 and VEGF-C concentrations were correlated with the symptom severity. ANGPT1 concentrations were increased in all patients compared to controls. ANGPT2 levels were correlated with severity of clinical variants and with tryptase levels. VEGF-A, ANGPT1 and VEGF-C did not differ between indolent and advanced mastocytosis. ROSAKIT WT, ROSAKIT D816V and HLMCs contained and spontaneously released VEGFs and ANGPTs. Serum concentrations of VEGFs and ANGPTs are altered in mastocytosis patients.

Long-term Follow-up for Missed Cases of Eosinophilic Esophagitis in Children With Previous Foreign Body in the Esophagus.

A foreign body impacted in the esophagus could be a sign of eosinophilic esophagitis (EoE). Our aim was to investigate if children previously diagnosed with a foreign body in the esophagus had a missed diagnosis of EoE. In this population-based longitudinal study, all children (0-18 years) diagnosed with a foreign body in the esophagus in Stockholm, Sweden 2006 to 2016, were identified. In addition to a review of medical files, each family was contacted (n = 325) and asked standardized questions. Children with symptoms indicating EoE were offered esophagogastroduodenoscopy (EGD). We found 325 pediatric cases of foreign body. Two hundred and seven (64%) underwent an endoscopy at the event, 3 of these had biopsies taken, whereby 2 were diagnosed with EoE. Six additional patients were diagnosed with EoE between the initial event and the study follow-up. Children with persisting symptoms suggestive of EoE at the follow-up (n = 21), were offered EGD whereof 7 accepted. Four new cases of EoE were found. Hence, 12 (3.7%) of the children with a previous foreign body, either spontaneously released or endoscopically removed, were diagnosed with EoE. In the structured interview, dysphagia, food impactions and drinking excessively with meals, as well as food allergies, were significantly more common in EoE patients. Children with a foreign body in the esophagus are at risk of having EoE. Biopsies should be taken during foreign body removal and questions about swallowing problems and allergic diseases should be carefully explored also in children who do not need EGD because of spontaneous release.

The effects of endogenous and exogenous catecholamines on hypoxic cardiac performance in red-bellied piranhas.

Catecholamines protect the fish heart during hypoxia. However, the humoral adrenergic stress response may only be invoked in extremis. We investigated the hypothesis that endogenous (e.g., neuronal) myocardial catecholamines may also impact cardiac performance during hypoxia in a hypoxia-tolerant tropical fish, the red-bellied piranha (Pygocentrus nattereri). First, we measured endogenous tissue catecholamines and in vitro catecholamine release from piranha myocardium using ultraperformance liquid chromatography. Ventricle homogenates contained detectable levels of both adrenaline (7.27 ng/g) and noradrenaline (14.48 ng/g), but only noradrenaline was released from ventricular tissue incubated in Ringer's solution. Noradrenaline released in this assay was not affected by hypoxia but was promoted by the catecholamine releasing agent tyramine. Our second series of experiments explored cardiac contractile performance in vitro using tyramine, exogenous noradrenaline or adrenaline, and propranolol (a β-adrenoceptor antagonist). In ventricular strip preparations, β-adrenergic blockade with propranolol had no effects on twitch force or contraction kinetics in either normoxia or hypoxia, confirming that spontaneous endogenous catecholamine release did not impact cardiac performance. However, in the absence of propranolol, tyramine mimicked the positive inotropic effect of noradrenaline (10 µM) during hypoxia, although adrenaline was capable of generating larger effects. Our results suggest that, although it is not spontaneously released, inducible endogenous noradrenaline release may have a significant β-adrenoceptor-dependent impact on hypoxic performance in the fish heart.

Astrocyte-Mediated Neuronal Synchronization Properties Revealed by False Gliotransmitter Release.

Astrocytes spontaneously release glutamate (Glut) as a gliotransmitter (GT), resulting in the generation of extrasynaptic NMDAR-mediated slow inward currents (SICs) in neighboring neurons, which can increase local neuronal excitability. However, there is a deficit in our knowledge of the factors that control spontaneous astrocyte GT release and the extent of its influence. We found that, in rat brain slices, increasing the supply of the physiological transmitter Glut increased the frequency and signaling charge of SICs over an extended period. This phenomenon was replicated by exogenous preexposure to the amino acid D-aspartate (D-Asp). Using D-Asp as a “false” GT, we determined the extent of local neuron excitation by GT release in ventrobasal thalamus, CA1 hippocampus, and somatosensory cortex. By analyzing synchronized neuronal NMDAR-mediated excitation, we found that the properties of the excitation were conserved in different brain areas. In the three areas, astrocyte-derived GT release synchronized groups of neurons at distances of >;200 μm. Individual neurons participated in more than one synchronized population, indicating that individual neurons can be excited by more than one astrocyte and that individual astrocytes may determine a neuron's synchronized network. The results confirm that astrocytes can act as excitatory nodes that can influence neurons over a significant range in a number of brain regions. Our findings further suggest that chronic elevation of ambient Glut levels can lead to increased GT Glut release, which may be relevant in some pathological states.SIGNIFICANCE STATEMENT Astrocytes spontaneously release glutamate (Glut) and other gliotransmitters (GTs) that can modify neuronal activity. Exposing brain slices to Glut and D-aspartate (D-Asp) before recording resulted in an increase in frequency of GT-mediated astrocyte–neuron signaling. Using D-Asp, it was possible to investigate the effects of specific GT release at neuronal NMDARs. Calcium imaging showed synchronized activity in groups of neurons in cortex, hippocampus, and thalamus. The size of these populations was similar in all areas and some neurons were involved in more than one synchronous group. The findings show that GT release is supply dependent and that the properties of the signaling and activated networks are largely conserved between different brain areas.

Simulation study of the ionic mechanisms underlying Torsade de Pointes in a 2D cardiac tissue

BackgroundTo understand the ionic mechanism behind the genesis of Torsade de Pointes (TdP) occurring with long QT syndrome 2 (LQTS2) in a remodelled transmural tissue. MethodsThe TP06 model is used to simulate the electrical activity of cells in a 2D transmural ventricular model. LQTS2 is realised by reducing the potassium current (IKr) to 0.5 in each cell. Each cell of the tissue is remodelled by increasing the conductance of calcium current (GCaL). The above two factors make the cells prone to early after depolarizations (EADs) development. The rise in GCaL that can develop a sustained TdP at normal pacing rate is determined from this study. A look at the calcium dynamics, sodium-calcium exchanger current (INaCa) and slow delayed rectifier potassium current (IKs) distribution maps of the tissue helps us in analysing the mechanism of TdP generation. ResultsA TdP type pattern at normal pacing rate is generated when GCaL is more than 3.5 times the control parameter. From the M-cell island, an adequate number of cells spontaneously release calcium from their sarcoplasmic reticulum leading to increased intracellular calcium and inward sodium current through the sodium calcium exchanger current (INaCa). These contribute to the development of EADs which create a depolarising wavefront that triggers TdP in the tissue. When GCaL is less than 3.5 times the control value, premature ventricular complexes (PVC) occur interspersed between normal beats. ConclusionNormal pacing rates can induce a multi focal TdP when sufficient number of M-cells simultaneously undergo spontaneous calcium release (SCR) events.

Epigenetic regulation of proinflammatory chemokines in Cystic Fibrosis lung epithelium

Abstract Functional loss of CFTR in lung epithelial cells leads to pulmonary disease in Cystic Fibrosis (CF) patients. Our preliminary data indicates that proinflammatory chemokines and cytokines are spontaneously released by Human Bronchial Epithelial (HBE) cells established from CF patients and the spontaneous release can be abolished by a bromodomain inhibitor, a small molecule that inhibits epigenetic enhancement of gene transcription. Epigenetics alter gene expression in many other diseases, thus, this mechanism could also be responsible for the dysregulation of inflammatory mediators observed in the CF airway. We hypothesize that the enhanced production of proinflammatory mediators observed in CF airways are in part controlled by an epigenetic regulatory program. RNA-seq analysis revealed a dramatic upregulation of chemokine genes in the airway epithelium from CF patients, which correlated with downregulation of histone deacetylases, suggesting chemokine expression in CF airway can be modified by histone acetylation. In vitro, chemokine productions in polarized HBE cells from CF donors are also enhanced and are sensitive to BET inhibition. ATAC-seq analysis on HBE cells derived from control and CF donors was conducted and more peaks were observed in CF cells at the promoter regions of several chemokine genes suggesting these loci are more accessible compared to control HBE cells. These data strongly implicate that pro-inflammatory environment in CF lungs epigenetically enhances chemokines production through repressing histone deacetylases, suggesting that therapeutic approaches aiming to reverse the consequence of losing histone deacetylases can be beneficial to CF patients through reducing lung inflammation.

Receptor Level Dissection of Common Versus Discrete Vesicle Release Pathways from Primary Vagal Afferent Terminals

Primary vagal afferent neurons form strong excitatory glutamatergic synapses onto second-order neurons in the nucleus of the solitary tract and initiate key autonomic and homeostatic reflex pathways. Vesicle fusion and release from vagal central terminals occurs via three distinct pathways including synchronous, asynchronous, and spontaneous. While synchronous and asynchronous release mechanisms require presynaptic action-potential depolarization; spontaneous release is ongoing and independent of action potentials. Evidence suggests these forms of release can be controlled independently indicating discrete and potentially separate vesicle pools and release sites. However, the presence and activation of transient receptor potential (TRP) channels (including TRPV1) at the central terminals dramatically increases the rate of spontaneous vesicle release and eventually diminish action-potential driven synchronous release; consistent with a common releasable pool. Confounding this interpretation is the observation that TRP channel activation also diminishes voltage activated sodium channel signaling. As such the decrease in synchronous release may be a result of action potential failure, rather than depleted vesicle pools. Given that synchronous and spontaneously release glutamate activates both AMPA and NMDA receptors postsynaptically we utilized ligand dependent post-synaptic NMDA receptor blockade (MK-801) to overcome this confound. We found that treatment with MK-801 during exclusively spontaneous release blocked the NMDA component of spontaneous events and subsequent action-potential driven synchronous release. This result demonstrates that glutamate released via spontaneous vesicle release is activating the same population of NMDA receptors as glutamate released synchronously. This finding is consistent with a common release site for synchronous and spontaneous release at vagal afferent terminals.

Differential Expression and Release of Activin A and Follistatin in Chronic Rhinosinusitis with and without Nasal Polyps.

BackgroundChronic rhinosinusitis with (CRSwNP) and without nasal polyps (CRSsNP) should be regarded as distinct clinical entities based on differential inflammatory mediator and remodeling profiles. Activin A, a member of the TGF-β superfamily, plays an important role in inflammation and remodeling in the lower airways, although its expression and release in the upper airways remain undescribed.ObjectiveTo investigate the expression of activin A and its inhibitor follistatin in nasal tissue samples from CRSsNP and CRSwNP patients, and to monitor the spontaneous release of these molecules in a human mucosal model.MethodsProtein levels were determined using ELISA for activin A, follistatin, TGF-β1 and indicator proteins (IL-5, ECP, IFNγ) in 13 CRSsNP, 23 CRSwNP, and 10 control samples. The spontaneous release rate and the release ratios of activin A, follistatin and TGF-β1 were determined in 9 CRSsNP and 7 CRSwNP tissue fragments cultured ex-vivo. The induction of activin A and TGF-β1 by one another was studied in 7 CRSsNP tissue fragments cultured ex-vivo.ResultsSignificantly higher concentrations of activin A, follistatin, TGF-β1, and IFNγ were observed in CRSsNP compared with CRSwNP samples, whereas the concentrations of IL-5 and ECP were significantly lower. Follistatin was positively and linearly correlated with activin A in CRSsNP and CRSwNP. Activin A, follistatin and TGF-β1 were all spontaneously released by the samples, although the relative ratios released by tissue fragments from CRSsNP and CRSwNP samples were significantly different, with a higher follistatin/activin A-ratio and a follistatin/TGFß1-ratio (with less overall TGF-β1) in CRSwNP than in CRSsNP. Furthermore, TGF-β1 enhanced activin A secretion in CRSsNP tissue fragments cultured ex-vivo.ConclusionThe differences in tissue concentrations and spontaneous release rates for activin A and follistatin in different CRS samples support the hypothesis that CRSsNP and CRSwNP are two distinct disease entities with respect to remodeling patterns.

Nitric oxide released from luminal s-nitroso-N-acetylcysteine increases gastric mucosal blood flow.

Nitric oxide (NO)-mediated vasodilation plays a key role in gastric mucosal defense, and NO-donor drugs may protect against diseases associated with gastric mucosal blood flow (GMBF) deficiencies. In this study, we used the ex vivo gastric chamber method and Laser Doppler Flowmetry to characterize the effects of luminal aqueous NO-donor drug S-nitroso-N-acetylcysteine (SNAC) solution administration compared to aqueous NaNO2 and NaNO3 solutions (pH 7.4) on GMBF in Sprague-Dawley rats. SNAC solutions (600 μM and 12 mM) led to a rapid threefold increase in GMBF, which was maintained during the incubation of the solutions with the gastric mucosa, while NaNO2 or NaNO3 solutions (12 mM) did not affect GMBF. SNAC solutions (600 μM and 12 mM) spontaneously released NO at 37 °C at a constant rate of 0.3 or 14 nmol·mL−1·min−1, respectively, while NaNO2 (12 mM) released NO at a rate of 0.06 nmol·mL−1·min−1 and NaNO3 (12 mM) did not release NO. These results suggest that the SNAC-induced GMBF increase is due to their higher rates of spontaneous NO release compared to equimolar NaNO2 solutions. Taken together, our data indicate that oral SNAC administration is a potential approach for gastric acid-peptic disorder prevention and treatment.

Spontaneous CO release from Ru(II)(CO)2-protein complexes in aqueous solution, cells, and mice.

We demonstrate that RuII(CO)2–protein complexes, formed by the reaction of the hydrolytic decomposition products of [fac-RuCl(κ2-H2NCH2CO2)(CO)3] (CORM-3) with histidine residues exposed on the surface of proteins, spontaneously release CO in aqueous solution, cells, and mice. CO release was detected by mass spectrometry (MS) and confocal microscopy using a CO-responsive turn-on fluorescent probe. These findings support our hypothesis that plasma proteins act as CO carriers after in vivo administration of CORM-3. CO released from a synthetic bovine serum albumin (BSA)–RuII(CO)2 complex leads to downregulation of the cytokines interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α in cancer cells. Finally, administration of BSA–RuII(CO)2 in mice bearing a colon carcinoma tumor results in enhanced CO accumulation at the tumor. Our data suggest the use of RuII(CO)2–protein complexes as viable alternatives for the safe and spatially controlled delivery of therapeutic CO in vivo.

Spontaneous CO Release from RuII(CO)2–Protein Complexes in Aqueous Solution, Cells, and Mice

AbstractWe demonstrate that RuII(CO)2–protein complexes, formed by the reaction of the hydrolytic decomposition products of [fac‐RuCl(κ2‐H2NCH2CO2)(CO)3] (CORM‐3) with histidine residues exposed on the surface of proteins, spontaneously release CO in aqueous solution, cells, and mice. CO release was detected by mass spectrometry (MS) and confocal microscopy using a CO‐responsive turn‐on fluorescent probe. These findings support our hypothesis that plasma proteins act as CO carriers after in vivo administration of CORM‐3. CO released from a synthetic bovine serum albumin (BSA)–RuII(CO)2 complex leads to downregulation of the cytokines interleukin (IL)‐6, IL‐10, and tumor necrosis factor (TNF)‐α in cancer cells. Finally, administration of BSA–RuII(CO)2 in mice bearing a colon carcinoma tumor results in enhanced CO accumulation at the tumor. Our data suggest the use of RuII(CO)2–protein complexes as viable alternatives for the safe and spatially controlled delivery of therapeutic CO in vivo.

Contribution of Water Molecules in the Spontaneous Release of Protein by Graphene Sheets

Applications of graphene sheets in the fields of biosensors and biomedical devices are limited by the aqueous solubility of graphene. Consequently, understanding the role of water molecules in the aggregation or dispersion of graphene in aqueous solution with a biomolecule is of vital importance to its application. Herein, protein is spontaneously released by the layer-to-layer aggregation of two single-layer graphene sheets due to van der Waals force between the sheets. The properties of water molecules, including density and dynamics, are discussed in detail. The dynamic behavior of aggregation of graphene sheets is triggered by the dynamics of water molecules. To stabilize dispersed graphene sheets in aqueous solution, the density of water molecules between the graphene sheets should be larger than 0.83 g cm(-3), and graphene modified by hydroxyl groups could be a good choice. The stability of a model protein on the graphene sheet is studied to investigate the biological compatibility of graphene sheets. To be a material with good biocompatibility, graphene should be functionalized by hydrophilic groups. The results presented herein could be helpful in the research and application of graphene sheets in the fields of biomaterials, biosensors, and biomedical devices.

Evidence that 5‐HT neurotransmission within the nucleus tractus solitarii (NTS) differentially modulates glutamate release via 5‐HT3 and 5‐HT1A receptors

The effects of spontaneously released 5‐HT were investigated in NTS containing slices (300 μm). Recordings were made of glutamatergic mEPSCs (abolished by CNQX) from voltage clamped (−60 mv) NTS neurones in the presence of gabazine (25 μmol) and TTX (1 μmol). Low doses (300μM; n=5) of 5‐HT inhibited (frequency decreased by 53±12%), while high doses 10μM increased mEPSC frequency (1285±276%) and amplitude (21±5 %). In presence of the 5‐HT3 antagonist granisetron (3μM) 5‐HT now only caused a decrease (31±11%) in frequency. The 5‐HT3 receptor agonist PBG (1μM) increased mEPSC frequency by 497±112% and amplitude by 18±4%, which was also blocked by granisetron. Granisetron (1μM; n=6) alone decreased mEPSC frequency by 35±4% as did the SSRI citalopram (0.5μM, n=5; 54±5%) and the OCT3 inhibitor decynium 22 (1μM; n=4; 27±2). The effects of the reuptake inhibitors were blocked by WAY‐100635 (1μM). The data indicates that the spontaneous release of 5‐HT in the NTS only activates presynaptically located 5‐HT3 and 5‐HT1A receptors. However, the ability of 5‐HT uptake blockade to only increase 5‐HT1A receptor activation suggests that the ability of spontaneously released 5‐HT to activate presynaptic 5‐HT3 receptors is not subject to modulation by reuptake. This would be consistent with these 5‐HT3 receptors being heteroreceptors. These data shows that endogenous 5‐HT has two distinct modulatory actions on glutamate release.

Bradykinin modulates spontaneous nerve growth factor production and stretch-induced ATP release in human urothelium

The urothelium plays a crucial role in integrating urinary bladder sensory outputs, responding to mechanical stress and chemical stimulation by producing several diffusible mediators, including ATP and, possibly, neurotrophin nerve growth factor (NGF). Such urothelial mediators activate underlying afferents and thus may contribute to normal bladder sensation and possibly to the development of bladder overactivity. The muscle-contracting and pain-inducing peptide bradykinin is produced in various inflammatory and non-inflammatory pathologies associated with bladder overactivity, but the effect of bradykinin on human urothelial function has not yet been characterized.The human urothelial cell line UROtsa expresses mRNA for both B1 and B2 subtypes of bradykinin receptors, as determined by real-time PCR. Bradykinin concentration-dependently (pEC50=8.3, Emax 4434±277nM) increased urothelial intracellular calcium levels and induced phosphorylation of the mitogen-activated protein kinase (MAPK) ERK1/2. Activation of both bradykinin-induced signaling pathways was completely abolished by the B2 antagonist icatibant (1μM), but not the B1 antagonist R715 (1μM). Bradykinin-induced (100nM) B2 receptor activation markedly increased (192±13% of control levels) stretch-induced ATP release from UROtsa in hypotonic medium, the effect being dependent on intracellular calcium elevations. UROtsa cells also expressed mRNA and protein for NGF and spontaneously released NGF to the medium in the course of hours (11.5±1.4pgNGF/mgprotein/h). Bradykinin increased NGF mRNA expression and accelerated urothelial NGF release to 127±5% in a protein kinase C- and ERK1/2-dependent manner. Finally, bradykinin up-regulated mRNA for transient-receptor potential vanilloid (TRPV1) sensory ion channel in UROtsa.In conclusion, we show that bradykinin represents a versatile modulator of human urothelial phenotype, accelerating stretch-induced ATP release, spontaneous release of NGF, as well as expression of sensory ion channel TRPV1. Bradykinin-induced changes in urothelial sensory function might contribute to the development of bladder dysfunction.