Studies on the expression and cellular function of sigma receptors in autonomic neurons were conducted in neonatal rat intracardiac and superior cervical (SCG) ganglia. Individual neurons from SCG and intracardiac ganglia were shown to express transcripts encoding the sigma-1 receptor using single-cell RT-PCR techniques. The relationship between sigma receptors and calcium channels was studied in isolated neurons of these ganglia under voltage-clamp mode using the perforated-patch configuration of the whole cell patch-clamp recording technique. Bath application of sigma receptor agonists was shown to rapidly depress peak calcium channel currents in a reversible manner in both SCG and intracardiac ganglion neurons. The inhibition of barium (I(Ba)) currents was dose-dependent, and half-maximal inhibitory concentration (IC50) values for haloperidol, ibogaine, (+)-pentazocine, and 1,3-Di-O-tolylguanidin (DTG) were 6, 31, 61, and 133 microM, respectively. The rank order potency of haloperidol > ibogaine > (+)-pentazocine > DTG is consistent with the effects on calcium channels being mediated by a sigma-2 receptor. Preincubation of neurons with the irreversible sigma receptor antagonist, metaphit, blocked DTG-mediated inhibition of Ca2+ channel currents. Maximum inhibition of calcium channel currents was > or =95%, suggesting that sigma receptors block all calcium channel subtypes found on the cell body of these neurons, which includes N-, L-, P/Q-, and R-type calcium channels. In addition to depressing peak Ca2+ channel current, sigma receptors altered the biophysical properties of these channels. Following sigma receptor activation, Ca2+ channel inactivation rate was accelerated, and the voltage dependence of both steady-state inactivation and activation shifted toward more negative potentials. Experiments on the signal transduction cascade coupling sigma receptors and Ca2+ channels demonstrated that neither cell dialysis nor intracellular application of 100 microM guanosine 5'-O-(2-thiodiphosphate) trilithium salt (GDP-beta-S) abolished the modulation of I(Ba) by sigma receptor agonists. These data suggest that neither a diffusible cytosolic second messenger nor a G protein is involved in this pathway. Activation of sigma receptors on sympathetic and parasympathetic neurons is likely to modulate cell-to-cell signaling in autonomic ganglia and thus the regulation of cardiac function by the peripheral nervous system.

Value co-destruction is emerging as an important way to conceptualize non-positive outcomes from actor-to-actor interactions. However, current research in this area neither offers a clear way to understand how value co-destruction manifests nor does it consider the role of actor engagement behaviors. Drawing on a case study in the aerospace industry, the present study begins by identifying and describing two ways in which actor perceptions of value co-destruction form: goal prevention and net deficits. Next, the study identifies and describes nine actor engagement behaviors that moderate actor experiences of value co-destruction. The study also unpacks these concepts at both the actor-to-actor and service ecosystem levels. The article concludes with implications for marketing theory and practice.

The paradigm of value co-creation in business markets is now well established in the marketing literature. However, the practices and capabilities for collaborative value co-creation are less understood, particularly in increasingly boundary-less interorganizational, network and ecosystem relationships. This paper describes sets of practices that organizations in business markets adopt to co-create value. We provide a theoretically-grounded, empirically-informed classification of value co-creating practices, identifying the underlying capabilities needed to realize value in B2B systems. We adopt a case study approach utilizing various methods of data collection to explore co-creation practices from four organizations. The analysis reveals that ‘sustained purposeful engagement’ underpins the organizations' ability to co-create and capture value. Implications for organizations willing to develop co-creation capabilities and practices are discussed

Recent studies have highlighted the involvement of the peripheral immune system in delayed cellular degeneration after stroke. In the permanent middle cerebral artery occlusion (MCAO) model of stroke, the spleen decreases in size. This reduction occurs through the release of splenic immune cells. Systemic treatment with human umbilical cord blood cells (HUCBC) 24 hours post-stroke blocks the reduction in spleen size while significantly reducing infarct volume. Splenectomy two weeks prior to MCAO also reduces infarct volume, further demonstrating the detrimental role of this organ in stroke-induced neurodegeneration. Activation of the sympathetic nervous system after MCAO results in elevated catecholamine levels both at the level of the spleen, through direct splenic innervation, and throughout the systemic circulation upon release from the adrenal medulla. These catecholamines bind to splenic α and β adrenoreceptors. This study examines whether catecholamines regulate the splenic response to stroke. Male Sprague-Dawley rats either underwent splenic denervation two weeks prior to MCAO or received injections of carvedilol, a pan adrenergic receptor blocker, prazosin, an α1 receptor blocker, or propranolol, a β receptor blocker. Denervation was confirmed by reduced splenic expression of tyrosine hydroxylase. Denervation prior to MCAO did not alter infarct volume or spleen size. Propranolol treatment also had no effects on these outcomes. Treatment with either prazosin or carvedilol prevented the reduction in spleen size, yet only carvedilol significantly reduced infarct volume (p<0.05). These results demonstrate that circulating blood borne catecholamines regulate the splenic response to stroke through the activation of both α and β adrenergic receptors.

In this work, we describe the fabrication and working of a modular microsystem that recapitulates the functions of the "Neurovascular Unit". The microdevice comprised a vertical stack of a poly(dimethylsiloxane) (PDMS) neural parenchymal chamber separated by a vascular channel via a microporous polycarbonate (PC) membrane. The neural chamber housed a mixture of neurons (~4%), astrocytes (~95%), and microglia (~1%). The vascular channel was lined with a layer of rat brain microvascular endothelial cell line (RBE4). Cellular components in the neural chamber and vascular channel showed viability (>90%). The neural cells fired inhibitory as well as excitatory potentials following 10 days of culture. The endothelial cells showed diluted-acetylated low density lipoprotein (dil-a-LDL) uptake, expressed von Willebrand factor (vWF) and zonula occludens (ZO-1) tight junctions, and showed decreased Alexafluor™-conjugated dextran leakage across their barriers significantly compared with controls (p < 0.05). When the vascular layer was stimulated with TNF-α for 6 h, about 75% of resident microglia and astrocytes on the neural side were activated significantly (p < 0.05 compared to controls) recapitulating tissue-mimetic responses resembling neuroinflammation. The impact of this microsystem lies in the fact that this biomimetic neurovascular platform might not only be harnessed for obtaining mechanistic insights for neurodegenerative disorders, but could also serve as a potential screening tool for central nervous system (CNS) therapeutics in toxicology and neuroinfectious diseases.

During brain injury, microglia become activated and migrate to areas of degenerating neurons. These microglia release pro-inflammatory cytokines and reactive oxygen species causing additional neuronal death. Microglia express high levels of sigma receptors, however, the function of these receptors in microglia and how they may affect the activation of these cells remain poorly understood. Using primary rat microglial cultures, it was found that sigma receptor activation suppresses the ability of microglia to rearrange their actin cytoskeleton, migrate, and release cytokines in response to the activators adenosine triphosphate (ATP), monocyte chemoattractant protein 1 (MCP-1), and lipopolysaccharide (LPS). Next, the role of sigma receptors in the regulation of calcium signaling during microglial activation was explored. Calcium fluorometry experiments in vitro show that stimulation of sigma receptors suppressed both transient and sustained intracellular calcium elevations associated with the microglial response to these activators. Further experiments showed that sigma receptors suppress microglial activation by interfering with increases in intracellular calcium. In addition, sigma receptor activation also prevented membrane ruffling in a calcium-independent manner, indicating that sigma receptors regulate the function of microglia via multiple mechanisms.

Sigma receptors are putative targets for neuroprotection following ischemia; however, little is known on their mechanism of action. One of the key components in the demise of neurons following ischemic injury is the disruption of intracellular calcium homeostasis. Fluorometric calcium imaging was used to examine the effects of sigma receptor activation on changes in intracellular calcium concentrations ([Ca 2ϩ ] i ) evoked by in vitro ischemia in cultured cortical neurons from embryonic rats. The sigma receptor agonist, 1,3-di-o-tolyl-guanidine (DTG), was shown to depress [Ca 2ϩ ] i elevations observed in response to ischemia induced by sodium azide and glucose deprivation. Two sigma receptor antagonists, metaphitwere shown to blunt the ability of DTG to inhibit ischemiaevoked increases in [Ca 2ϩ ] i , revealing that the effects are mediated by activation of sigma receptors and not via the actions of DTG on nonspecific targets such as N-methyl-D-aspartate receptors. DTG inhibition of ischemia-induced increases in [Ca 2ϩ ] i was mimicked by the -1 receptor-selective agonists, carbetapentane, (ϩ)-pentazocine and PRE-084 [2-(4-morpholinethyl) 1-phenylcyclohexanecarboxylate hydrochloride], but not by the sigma-2-selective agonist, ibogaine, showing that activation of sigma-1 receptors is responsible for the effects. In contrast, DTG, carbetapentane, and ibogaine blocked spontaneous, synchronous calcium transients observed in our preparation at concentrations consistent with sigma receptormediated effects, indicating that both sigma-1 and sigma-2 receptors regulate events that affect [Ca 2ϩ ] i in cortical neurons. Our studies show that activation of sigma receptors can ameliorate [Ca 2ϩ ] i dysregulation associated with ischemia in cortical neurons and, thus, identify one of the mechanisms by which these receptors may exert their neuroprotective properties.Sigma receptors are widely distributed in the mammalian brain, and these receptors recognize a diverse array of centrally acting substances including opiates, antipsychotics, antidepressants, phencyclidine (PCP)-related compounds, and neurosteroids Bowen, 2000). Thus far, two sigma receptor subtypes have been identified on the basis of their pharmacological profile, with the sigma-1 receptor showing high affinity for the positive isomer of bezomorphas such as (ϩ)-pentazocine and (ϩ)-SKF-10,047, and the sigma-2 receptor having high affinity for ibogaine (Vilner and Bowen, 2000), but only the sigma-1 receptor has been cloned (Hanner et al., 1996). Sigma receptors have been implicated in numerous physiological and pathophysiological processes such as learning and memory (Senda et al., 1996), movement disorders , and drug addiction (McCracken et al., 1999). These receptors are emerging as therapeutic targets for various diseases such neuropsychiatric disorders and cancer (Casellas et al., 2004;Hayashi and Su, 2004). Moreover, the observation that several sigma receptor ligands are neuroprotective in both in vivo and in vitro models of ischemia has ...

We have isolated and characterized ␣-conotoxin EpI, a novel sulfated peptide from the venom of the molluscivorous snail, Conus episcopatus. The peptide was classified as an ␣-conotoxin based on sequence, disulfide connectivity, and pharmacological target. EpI has homology to sequences of previously described ␣-conotoxins, particularly PnIA, PnIB, and ImI. However, EpI differs from previously reported conotoxins in that it has a sulfotyrosine residue, identified by amino acid analysis and mass spectrometry. Native EpI was shown to coelute with synthetic EpI. The peptide sequence is consistent with most, but not all, recognized criteria for predicting tyrosine sulfation sites in proteins and peptides.