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Chemical Stimuli (chemical + stimulus)
Selected AbstractsChemosensory Recognition of Familiar and Unfamiliar Conspecifics by Juveniles of the Iberian Wall Lizard Podarcis hispanicaETHOLOGY, Issue 4 2002Enrique Font Chemosensory recognition of familiar conspecifics has been reported in studies with members of several lizard families and may be advantageous to distinguish between intruders and neighbors or group members. However, few species have been studied and information on the ability to discriminate between familiar and unfamiliar conspecifics by chemosensory means is lacking for most lizard families. In this paper we ask whether juveniles of the Iberian wall lizard Podarcis hispanica (Lacertidae), can discriminate between chemical signals from familiar conspecifics with whom they have shared a terrarium for several months and those from unfamiliar conspecifics housed in a different terrarium. Experimental trials were conducted by transferring juveniles to a test terrarium with a filter paper substrate. We tested the responses of lizards to paper substrates labeled by familiar cage-mates, unfamiliar conspecifics, or unlabeled. Tongue-flicks and other behaviors in response to pheromonal stimuli were recorded for 10 min Juveniles directed more chemosensory behavior towards paper substrates bearing chemicals from familiar conspecifics than towards similar paper substrates labeled by unfamiliar conspecifics. These results indicate that juveniles in this lizard species can recognize familiar conspecifics and discriminate between familiar and unfamiliar individuals using only chemical stimuli. We discuss the role of habituation in familiar conspecific recognition and review possible explanations of the functional significance of this type of discrimination in lizards. [source] Chemical Alarm Signals Enhance Survival of Brook Charr (Salvelinus fontinalis) During Encounters with Predatory Chain Pickerel (Esox niger)ETHOLOGY, Issue 11 2001Reehan S. Mirza A diversity of aquatic organisms release chemical alarm signals when attacked or captured by a predator. These alarm signals are thought to warn other conspecifics of danger and, consequently, may benefit receivers by increasing their survival. Here we experimentally investigated the differences in behaviour and survival of hatchery-reared juvenile brook charr Salvelinus fontinalis that had been exposed to either brook charr skin extract (experimental treatment) or a control of swordtail skin extract (control treatment). Charr exposed to conspecific skin extract exhibited a significant reduction in movement and/or altered their foraging behaviour in the laboratory when compared with charr exposed to swordtail skin extract. We also exposed charr to either water conditioned by a single brook charr disturbed by a predatory bird model or water conditioned by a single undisturbed brook charr. Charr exposed to disturbance signals reduced activity significantly more than charr exposed to chemical stimuli from undisturbed charr. These results demonstrate the existence of both damage-released alarm signals and disturbance signals in brook charr. Wild brook charr also responded to damage-released alarm cues under natural conditions. Charr avoided areas of a stream with minnow traps labelled with conspecific alarm cues vs. control cues. During staged encounters with chain pickerel Esox niger in the laboratory, predator-naive charr fry were better able to evade the predator if they were previously warned by an alarm signal, thus suggesting a survival benefit to receivers. Collectively, these results demonstrate that the presence of alarm signals in brook charr has important implications for understanding predator,prey interactions. [source] Respiratory responses evoked by blockades of ionotropic glutamate receptors within the Bötzinger complex and the pre-Bötzinger complex of the rabbitEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Donatella Mutolo Abstract The respiratory role of excitatory amino acid (EAA) receptors within the Bötzinger complex (BötC) and the pre-Bötzinger complex (pre-BötC) was investigated in ,-chloralose,urethane anaesthetized, vagotomized, paralysed and artificially ventilated rabbits by using bilateral microinjections (30,50 nL) of EAA receptor antagonists. Blockade of both N -methyl- d -aspartic acid (NMDA) and non-NMDA receptors by 50 mm kynurenic acid (KYN) within the BötC induced a pattern of breathing characterized by low-amplitude, high-frequency irregular oscillations superimposed on tonic phrenic activity and successively the disappearance of respiratory rhythmicity in the presence of intense tonic inspiratory discharges (tonic apnea). KYN microinjections into the pre-BötC caused similar respiratory responses that, however, never led to tonic apnea. Blockade of NMDA receptors by D(,)-2-amino-5-phosphonopentanoic acid (D-AP5; 1, 10 and 20 mm) within the BötC induced increases in respiratory frequency and decreases in peak phrenic amplitude; the highest concentrations caused tonic apnea insensitive to chemical stimuli. Blockade of non-NMDA receptors by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 1, 10 and 20 mm) within the BötC produced only less pronounced increases in respiratory frequency. Responses to D-AP5 in the pre-BötC were similar, although less pronounced than those elicited in the BötC and never characterized by tonic apnea. In the same region, CNQX provoked increases in respiratory frequency similar to those elicited in the BötC, associated with slight reductions in peak phrenic activity. The results show that EAA receptors within the investigated medullary subregions mediate a potent control on both the intensity and frequency of inspiratory activity, with a major role played by NMDA receptors. [source] Epidermal keratinocytes as the forefront of the sensory systemEXPERIMENTAL DERMATOLOGY, Issue 3 2007Mitsuhiro Denda Abstract, Various sensors that respond to physical or chemical environmental factors have been identified in the peripheral nervous system. Some of them, which respond to mechanical stress, osmotic pressure, temperature and chemical stimuli (such as pH), are also expressed in epidermal keratinocytes. Neurotransmitters and their receptors, as well as receptors that regulate the neuroendocrine system of the skin, are also present in keratinocytes. Thus, broadly speaking, epidermal keratinocytes appear to be equipped with sensing systems similar to those of the peripheral and central nervous systems. It had long been considered that only nerve C-terminals in the epidermis play a role in skin surface perception. However, building on earlier work on skin receptors and new findings introduced here, we present in this review a novel hypothesis of skin sensory perception, i.e. first, keratinocytes recognize various environmental factors, and then the information is processed and conveyed to the nervous system. [source] Neurotransmitter and neuromodulatory mechanisms at peripheral arterial chemoreceptorsEXPERIMENTAL PHYSIOLOGY, Issue 6 2010Colin A. Nurse The control of breathing depends critically on sensory inputs to the central pattern generator of the brainstem, arising from peripheral arterial chemoreceptors located principally in the carotid bodies (CBs). The CB receptors, i.e. glomus or type I cells, are excited by chemical stimuli in arterial blood, particularly hypoxia, hypercapnia, acidosis and low glucose, which initiate corrective reflex cardiorespiratory and cardiovascular adjustments. Type I cells occur in clusters and are innervated by petrosal afferent fibres. Synaptic specializations (both chemical and electrical) occur between type I cells and petrosal terminals, and between neighbouring type I cells. This, together with the presence of a wide array of neurotransmitters and neuromodulators linked to both ionotropic and metabotropic receptors, allows for a complex modulation of CB sensory output. Studies in several laboratories over the last ,20 years have provided much insight into the transduction mechanisms. More recent studies, aided by the development of a co-culture model of the rat CB, have shed light on the role of neurotransmitters and neuromodulators in shaping the afferent response. This review highlights some of these developments, which have contributed to our current understanding of information processing at CB chemoreceptors. [source] Tunable Colors in Opals and Inverse Opal Photonic CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Carlos I. Aguirre Abstract Colloidal photonic crystals and materials derived from colloidal crystals can exhibit distinct structural colors that result from incomplete photonic band gaps. Through rational materials design, the colors of such photonic crystals can be tuned reversibly by external physical and chemical stimuli. Such stimuli include solvent and dye infiltration, applied electric or magnetic fields, mechanical deformation, light irradiation, temperature changes, changes in pH, and specific molecular interactions. Reversible color changes result from alterations in lattice spacings, filling fractions, and refractive index of system components. This review article highlights the different systems and mechanisms for achieving tunable color based on opaline materials with close-packed or non-close-packed structural elements and inverse opal photonic crystals. Inorganic and polymeric systems, such as hydrogels, metallopolymers, and elastomers are discussed. [source] Subicular and CA1 hippocampal projections to the accessory olfactory bulbHIPPOCAMPUS, Issue 2 2009C. de la Rosa-Prieto Abstract The hippocampal formation is anatomically and functionally related to the olfactory structures especially in rodents. The entorhinal cortex (EC) receives afferent projections from the main olfactory bulb; this constitutes an olfactory pathway to the hippocampus. In addition to the olfactory system, most mammals possess an accessory olfactory (or vomeronasal) system. The relationships between the hippocampal formation and the vomeronasal system are virtually unexplored. Recently, a centrifugal projection from CA1 to the accessory olfactory bulb has been identified using anterograde tracers. In the study reported herein, experiments using anterograde tracers confirm this projection, and injections of retrograde tracers show the distribution and morphology of a population of CA1 and ventral subicular neurons projecting to the accessory olfactory bulb of rats. These results extend previous descriptions of hippocampal projections to the accessory olfactory bulb by including the ventral subiculum and characterizing the morphology, neurochemistry (double labeling with somatostatin), and distribution of such neurons. These data suggest feedback hippocampal control of chemosensory stimuli in the accessory olfactory bulb. Whether this projection processes spatial information on conspecifics or is involved in learning and memory processes associated with chemical stimuli remains to be elucidated. © 2008 Wiley-Liss, Inc. [source] The contribution of neurogenic inflammation to sensitive skin: concepts, mechanisms and cosmeceutical interventionINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2009A. Ferrer-Montiel IFSCC Magazine, 11 (2008) (4) 311,315 This paper was presented as a keynote lecture at the IFSCC Congress 2008, Barcelona, Spain. Cutaneous neurogenic inflammation is emerging as an underlying mechanism for several skin conditions. The intimate cross-talk between the cutaneous immune system and the peripheral nervous system is fundamental for skin biology. However, an imbalance or dysfunction results in the onset of an inflammatory state that is reinforced by the synergic and complementary action of both systems. Cumulative evidence indicates that the thermoreceptor TRPV1 is a key player of neurogenic inflammation. This receptor is activated by both physical and chemical stimuli, and its activity is potentiated by pro-inflammatory mediators. An increase in TRPV1 activity results in an increment of neuronal excitability that leads to the release of proalgesic agents that stimulate the immune system. Therefore, the TRPV1 receptor is being considered as a cosmeceutical target, and agents that reduce its activity will be useful cosmeceuticals. Keywords:, Algogens, epidermis, immune system, nociceptor, sensitization [source] Pheromone blends and trap designs can affect catches of Sesamia nonagrioides Lef. (Lep., Noctuidae) males in maize fieldsJOURNAL OF APPLIED ENTOMOLOGY, Issue 1-2 2001A. Ameline Among lepidopteran insects, the female-produced sex pheromones are the most widely used chemical stimuli for pest management by (i) mating disruption, and (ii) monitoring adult insect populations in agricultural crops. Sesamia nonagrioides is one of the main pests on maize crops around the Mediterranean area and monitoring adult populations with synthetic sex pheromone is of great interest. The technique used involved field trapping with synthetic pheromone blend. The reliability of the technique is directly related to the trap shape and pheromone blends. Universal Moth Trap® (UM trap, Biosyste,mes, France) and Service Régional de la Protection des Végétaux (SRPV) traps baited with either synthetic pheromone blend or virgin females were evaluated in two commercial maize fields (var.cecilia) (Belleserre, Tarn. France) to determine the potential use of synthetic lures in monitoring S. nonagrioides populations in maize field. The study showed that SRPV traps baited with synthetic pheromone blend caught significantly more S. nonagrioides males than UM traps baited with the same blend, indicating the efficiency of the SRPV traps in monitoring field population of S. nonagrioides. The study also showed that the synthetic pheromone-baited SRPV trap caught three times less adult males than the same traps baited with virgin females indicating that the synthetic blend was less attractive than the natural blend released by virgin females. However, despite the lower number of catches in the SRPV traps baited with synthetic pheromones, there was a significant and positive relationship between the number of catches in SRPV traps baited with the synthetic pheromone and with the females. This result indicates that synthetic pheromones can be used as baits in SRPV traps to monitor S. nonagrioides adult population in commercial maize crops. Nevertheless, to use the synthetic pheromone to monitor S. nonagrioides population effectively in the field, further refinement and improvement of the synthetic blend should be carried out in order to obtain a blend that is equally as attractive as the natural blend released by virgin females. [source] Sturgeon food searching behaviour evoked by chemical stimuli: a reliable sensory mechanismJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4-6 2002A. O. Kasumyan First page of article [source] Olfactory receptors: G protein-coupled receptors and beyondJOURNAL OF NEUROCHEMISTRY, Issue 6 2009Marc Spehr Abstract Sensing the chemical environment is critical for all organisms. Diverse animals from insects to mammals utilize highly organized olfactory system to detect, encode, and process chemostimuli that may carry important information critical for health, survival, social interactions and reproduction. Therefore, for animals to properly interpret and react to their environment it is imperative that the olfactory system recognizes chemical stimuli with appropriate selectivity and sensitivity. Because olfactory receptor proteins play such an essential role in the specific recognition of diverse stimuli, understanding how they interact with and transduce their cognate ligands is a high priority. In the nearly two decades since the discovery that the mammalian odorant receptor gene family constitutes the largest group of G protein-coupled receptor (GPCR) genes, much attention has been focused on the roles of GPCRs in vertebrate and invertebrate olfaction. However, is has become clear that the ,family' of olfactory receptors is highly diverse, with roles for enzymes and ligand-gated ion channels as well as GPCRs in the primary detection of olfactory stimuli. [source] Nerve growth factor-evoked nociceptor sensitization in pig skin in vivoJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2010Roman Rukwied Abstract Peripheral sensitization of skin nociceptors by nerve growth factor (NGF) was explored in pig skin in vivo. As an objective output measure, the area of axon-reflex-mediated erythema was assessed upon mechanical, thermal, chemical, and electrical stimuli delivered at 1, 3, and 7 days after i.d. injection of 1 ,g NGF into the pig's back skin (n = 8). Pretreatment with NGF provoked a sensitization to mechanical (600 mN), thermal (10 sec 49°C) and chemical (15 ,l, pH 3) stimuli that lasted for 7 days. No sensitization, however, was found in response to weak mechanical (100 mN), weak thermal (10 sec 45°C), or electrical stimuli. Irrespective of the skin pretreatment (NGF or PBS vehicle control), the area of electrically induced erythema decreased upon repetition (days 1,7) by 70% (P < 0.05). Sensitization of sensory endings by NGF upon mechanical, heat, and chemical stimuli suggests recruitment of sensory transducer molecules [e.g., TRPV1, acid-sensing ion channels (ASICs)]. In contrast, the gradual decrease in electrically induced erythema over 7 days might be attributable to axonal desensitization and possibly activity-dependent down-regulation of sodium channels. Thus, long-lasting sensitization processes of nociceptor endings or axonal sodium channel desensitization mechanisms can be explored in the pig as a translational experimental animal model. © 2010 Wiley-Liss, Inc. [source] Sensory neurone responses to mucosal noxae in the upper gut: relevance to mucosal integrity and gastrointestinal painNEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2002P. Holzer Abstract ,The digestive tract is supplied by extrinsic and intrinsic sensory neurones that, together with endocrine and immune cells, form a surveillance network that is essential to gut function. This article focuses on the responses of extrinsic afferent neurones to chemical insults of the gastrointestinal mucosa and their pathophysiological relevance to mucosal integrity and abdominal pain. Within the gastroduodenal region, spinal afferents subserve an emergency function because, in case of alarm by influxing acid, they stimulate mechanisms of mucosal protection via an efferent-like release of transmitters. Other sensory neurones signal chemical noxae to the brain, a task that is not confined to spinal afferents because vagal afferents communicate gastric acid and peripheral immune challenges to the brainstem and in this way elicit autonomic, endocrine, affective and behavioural reactions. Emerging evidence indicates that hypersensitivity of extrinsic afferent pathways to mechanical and chemical stimuli makes an important contribution to the abdominal hyperalgesia seen in functional dyspepsia and irritable bowel syndrome. Sensitization may be brought about by inflammatory processes that lead to up-regulation and functional alterations of receptors and ion channels on sensory neurones. Such sensory neurone-specific molecules, which include vanilloid (capsaicin) receptors, may represent important targets for novel drugs to treat abdominal pain. [source] Enhanced expression of mast cell growth factor and mast cell activation in the bladder following the resolution of trinitrobenzenesulfonic acid (TNBS) colitis in female rats,NEUROUROLOGY AND URODYNAMICS, Issue 6 2007Ruomei Liang Abstract Aims Chronic pelvic pain disorders often overlap. We have shown that acute colonic irritation can produce acute irritative micturition patterns and acutely sensitize bladder afferent responses to mechanical and chemical stimuli. We hypothesize that with time, colonic irritation can lead to neurogenic changes in the bladder and the development of chronic bladder sensitization. Methods Micturition patterns were measured in rats 60,90 days after the induction of trinitrobenzenesulfonic acid (TNBS) colitis in the resolution phase of this model. Total and activated mast cells (MCs) were quantified in the bladder, while mRNA levels of stem cell factor (SCF; a.k.a. MC growth factor) and nerve growth factor (NGF; a MC and nociceptive C-fiber stimulator) were quantified in the bladder and L6-S1 dorsal root ganglia (DRG). Results Following intra-rectal TNBS, voiding volume was reduced (P,<,0.005), while voiding frequency was increased (P,<,0.05), both by ,50%. Furthermore, both the percentage and density of activated bladder MCs were significantly elevated (P,<,0.05), although total MC counts were not statistically increased. At the molecular level, urinary bladder SCF expression increased twofold (P,<,0.005), as did NGF (P,<,0.01), while L6-S1 DRG levels were not significantly elevated. Conclusions Chronic cystitis in the rat as evidenced by changes in micturition patterns and the recruitment of activated MCs can occur during the resolution phase of TNBS colitis. These changes, of which MCs may play an important role, appear to be maintained over time and may occur via stimulation of convergent pelvic afferent input resulting in the upregulation of neurotrophic factors in the target organ. Neurourol. Urodynam. 26:887,893, 2007. © 2007 Wiley-Liss, Inc. [source] Behavioural evidence for a female sex pheromone in Cotesia flavipes (Hymenoptera: Braconidae)PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2004Maria Do Rosário T. De Freitas Abstract., The mating behaviour of Cotesia flavipes Cameron, 1891 (Hymenoptera: Braconidae) was observed under laboratory conditions. The results demonstrate that chemical stimuli play an important role in bringing males and females together for mating. Females from this species release chemical compounds to attract males, which exhibit a distinct courtship behaviour divided into three main steps: (i) antennation, (ii) lateral bouncing and (iii) wing fluttering. Ethological tests using hexane extracts from two different parts of the female's body (head plus thorax and abdomen) demonstrate that males are more attracted and also display a courtship behaviour when a filter paper containing hexane extracts from the abdomen is presented to them, indicating that the abdomen is the source of the sex pheromone of this species. Naive males of this species respond to hexane extracts of this gland by displaying courtship behaviour. Furthermore, additional tests show that C. flavipes females mate only once, whereas virgin males do not show any preference for virgin or mated females, suggesting that mated females of this species continue to produce sex attractants after mating. [source] Evolution of the special senses in primates: Past, present, and futureTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2004Nathaniel J. Dominy Abstract The present special issue of The Anatomical Record is the result of a symposium entitled Evolution of the Special Senses in Primates. Considered together, the special senses of primates are remarkable because they constitute a singular and definitive suite of mammalian characteristics. Examining their evolution is pivotal for understanding the origin and present-day variation of primate behavior and ecology. Accordingly, the 14 articles assembled here consider the different constraints and opportunities associated with the uptake and use of physical and chemical stimuli. The present issue brings together experts on different primate sensory modalities and stresses events at the sensory periphery, where the organism is exposed to and comes into contact with its environment. Key topics include color vision, the genetics of olfaction, the morphological basis and significance of chemical communication, and the neural organization and scaling of primate sensory systems. The result is a special issue that both reflects our current understanding of primate sensory modalities and challenges certain fundamental assumptions concerning their evolution. © 2004 Wiley-Liss, Inc. [source] Eruptive cherry angiomas associated with vitiligo: Provoked by topical nitrogen mustard?THE JOURNAL OF DERMATOLOGY, Issue 12 2006Hui-Jun MA ABSTRACT We report a 27-year-old man who had suffered with vitiligo for 7 years and with eruptive cherry angiomas within or around the repigmented vitiliginous skin for 2 years. After continual therapy for vitiligo with topical nitrogen mustard in a concentration of 0.001% for 5 years, multiple cherry angiomas erupted within or around the repigmented vitiliginous plaques. The discontinue therapy with nitrogen mustard stopped the appearance of new cherry angiomas. The presence of eruptive cherry angiomas was evident and was confirmed by histopathology. We suggest that the chronic chemical stimuli caused by topical nitrogen mustard might result in the formation of eruptive cherry angiomas. [source] Visualisation of human dental pulp vasculature by immunohistochemical and immunofluorescent detection of CD34: A comparative studyAUSTRALIAN ENDODONTIC JOURNAL, Issue 3 2006Anna Digka Abstract CD34 is considered a pan-endothelial cell marker for paraffin-embedded sections. In this study, both immunohistochemistry and immunofluorescence were applied in human dental pulp specimens of moderate thickness (10 µm) in order to observe the vasculature of this tissue using CD34. Both techniques revealed a homogenous staining pattern with capillaries and larger vessels showing complete and strong membrane staining reflecting the high capacity of the pulp for regeneration and response to different stimuli. A novel approach in the identification of the pulpal vasculature by Cy5-conjugated anti-CD34 is introduced in this study. By this technique the dense capillary plexus of the sub-odontoblastic region, which is responsible for the reaction of the tissue to any physical or chemical stimuli or pathological condition, can be clearly identified, while immunohistochemistry did not reveal such a detailed staining pattern. [source] Sexual selection research on spiders: progress and biasesBIOLOGICAL REVIEWS, Issue 3 2005Bernhard A. Huber ABSTRACT The renaissance of interest in sexual selection during the last decades has fuelled an extraordinary increase of scientific papers on the subject in spiders. Research has focused both on the process of sexual selection itself, for example on the signals and various modalities involved, and on the patterns, that is the outcome of mate choice and competition depending on certain parameters. Sexual selection has most clearly been demonstrated in cases involving visual and acoustical signals but most spiders are myopic and mute, relying rather on vibrations, chemical and tactile stimuli. This review argues that research has been biased towards modalities that are relatively easily accessible to the human observer. Circumstantial and comparative evidence indicates that sexual selection working via substrate-borne vibrations and tactile as well as chemical stimuli may be common and widespread in spiders. Pattern-oriented research has focused on several phenomena for which spiders offer excellent model objects, like sexual size dimorphism, nuptial feeding, sexual cannibalism, and sperm competition. The accumulating evidence argues for a highly complex set of explanations for seemingly uniform patterns like size dimorphism and sexual cannibalism. Sexual selection appears involved as well as natural selection and mechanisms that are adaptive in other contexts only. Sperm competition has resulted in a plethora of morphological and behavioural adaptations, and simplistic models like those linking reproductive morphology with behaviour and sperm priority patterns in a straightforward way are being replaced by complex models involving an array of parameters. Male mating costs are increasingly being documented in spiders, and sexual selection by male mate choice is discussed as a potential result. Research on sexual selection in spiders has come a long way since Darwin, whose spider examples are reanalysed in the context of contemporary knowledge, but the same biases and methodological constraints have persisted almost unchanged through the current boom of research. [source] A Review of HNS-32: A Novel Azulene-l-Carboxamidine Derivative with Multiple Cardiovascular Protective ActionsCARDIOVASCULAR THERAPEUTICS, Issue 4 2001Yoshio Tanaka ABSTRACT HNS-32 [N1,N1 -dimethyl- N2 -(2-pyridylmethyl)-5-isopropyl-3,8-dimethylazulene-1-carboxamidine] (CAS Registry Number: 186086-10-2) is a newly synthesized azulene derivative. Computer simulation showed that its three dimensional structure is similar to that of the class Ib antiarrhythmic drugs, e.g., lidocaine or mexiletine. HNS-32 potently suppressed ventricular arrhythmias induced by ischemia due to coronary ligation and/or ischemia-reperfusion in dogs and rats. In the isolated dog and guinea pig cardiac tissues, HNS-32 had negative inotropic and chronotropic actions, prolonged atrial-His and His-ventricular conduction time and increased coronary blood flow. In the isolated guinea pig ventricular papillary muscle, HNS-32 decreased maximal rate of action potential upstroke (V,max) and shortened action potential duration (APD). These findings suggest that HNS-32 inhibits inward Na+ and Ca2+ channel currents. In the isolated pig coronary and rabbit conduit arteries, HNS-32 inhibited both Ca2+ channel-dependent and -independent contractions induced by a wide variety of chemical stimuli. HNS-32 is a potent inhibitor of protein kinase C (PKC)-mediated constriction of cerebral arteries. It is likely to block both, Na+ and Ca2+ channels expressed in cardiac and vascular smooth muscles. These multiple ion channel blocking effects are largely responsible for the antiarrhythmic and vasorelaxant actions of HNS-32. This drug may represent a novel approach to the treatment of arrhythmias. [source] Nanotube Membrane Based BiosensorsELECTROANALYSIS, Issue 1-2 2004Punit Kohli Abstract We review highly sensitive detection based on electrochemical methods. These methods are based on monodisperse gold and alumina nanotubule membranes with inside diameter approaching molecular dimensions. The analyte species can be detected by measuring a change in trans-membrane current when the analyte is added to the nanotubule-based cell. The second method entails the use of a concentration change based on the nanotubule membrane. Biomemtic ion-gated channels micropore and nanotubule membrane sensors are also reviewed. These synthetic ion channels can be switched from an "off" state to an "on" state in response to an external chemical stimulus. Using these methods, we have achieved detection limits as low as 10,pM. Potential applications for these biosensors are in fields such as bioanalytical, biomedical, pharmaceutical and drug discovery. [source] In vitro evaluation of reactive astrocyte migration, a component of tissue remodeling in glaucomatous optic nerve headGLIA, Issue 3 2001Gülgün Tezel Abstract In order to improve understanding of remodeling events in the glaucomatous optic nerve head, the migration of optic nerve head astrocytes was studied in vitro. Since elevated intraocular pressure is an important stress factor identified in glaucomatous eyes, optic nerve head astrocytes were incubated under physical stress created by elevated hydrostatic pressure. In addition, they were incubated in the presence of a chemical stimulus, lipolysaccharide (LPS). Migration of reactivated astrocytes in the presence of these stressors was examined using chambers in which cell migration through extracellular matrix-coated pores is only possible following proteolytic digestion of the matrix. We observed that the migratory ability of optic nerve head astrocytes was approximately 4,6 times greater following exposure to elevated hydrostatic pressure or LPS for up to 48 h. Phosphoinositide 3-kinase, protein kinase C, and tyrosine kinase were found to be involved in the signal transduction for activated migration of optic nerve head astrocytes in response to elevated hydrostatic pressure or LPS. In addition, we observed that the stress-induced migration of optic nerve head astrocytes, which is accompanied by proteolytic degradation, resulted in the formation of culture cavities containing mucopolysaccharides. These in vitro findings provide a clearer understanding of the pathophysiologic mechanisms of characteristic tissue remodeling events that occur, in vivo, in the glaucomatous optic nerve head. GLIA 34:178,189, 2001. © 2001 Wiley-Liss, Inc. [source] SENSORY APPROACH TO MEASURE FRAGRANCE INTENSITY ON THE SKINJOURNAL OF SENSORY STUDIES, Issue 6 2009CLAUDIA SILVA CORTEZ-PEREIRA ABSTRACT Sensory analysis is a precise and descriptive measuring technique to quantify human responses to stimuli. Odor, one of these stimuli, is basically the result of the interaction between a chemical stimulus and the olfactory receptor system, which can be described using a number of different dimensions and measures through different sensory tests: threshold, intensity and quality. To measure fragrance performance on the skin, these parameters are very important, but the main attribute to be evaluated is substantivity, thus the importance of the sensory scale chosen to measure perception, discriminate different intensities and determine the substantivity of the fragrance. Some studies comparing the labeled magnitude scale (LMS) with other magnitude scales and their derivations showed that the use of the LMS scale to measure fragrance intensity could semantically understand the intensity of the stimulus. Tests using this scale confirmed the applicability and efficiency of the LMS. PRACTICAL APPLICATIONS The objective of this article is to review the techniques used to measure odor and fragrance intensities applied on the skin. The review shows general sensory techniques and their goals, the newest olfactory mechanism and its contribution to sensory evaluation and which attributes should be considered to measure odor. Substantivity/retentivity or longevity can be regarded as the most important attributes if you want to measure fragrance performance on the skin. Past studies showed different scales tested to measure odor, and some of them demonstrated that the labeled magnitude scale is very suitable to measure fragrance on the skin. [source] Is seed conditioning essential for Orobanche germination?PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2009Dina Plakhine Abstract BACKGROUND: Parasitic Orobanchaceae germinate only after receiving a chemical stimulus from roots of potential host plants. A preparatory phase of several days that follows seed imbibition, termed conditioning, is known to be required; thereafter the seeds can respond to germination stimulants. The aim of this study was to examine whether conditioning is essential for stimulant receptivity. RESULTS: Non-conditioned seeds of both Orobanche cumana Wallr. and O. aegyptiaca Pers. [syn. Phelipanche aegyptiaca (Pers.) Pomel] were able to germinate in response to chemical stimulation by GR24 even without prior conditioning. Stimulated seeds reached maximal germination rates about 2 weeks after the onset of imbibition, no matter whether the seeds had or had not been conditioned before stimulation. Whereas the lag time between stimulation and germination response of non-conditioned seeds was longer than for conditioned seeds, the total time between imbibition and germination was shorter for the non-conditioned seeds. Unlike the above two species, O. crenata Forsk. was found to require conditioning prior to stimulation. CONCLUSIONS: Seeds of O. cumana and O. aegyptiaca are already receptive before conditioning. Thus, conditioning is not involved in stimulant receptivity. A hypothesis is put forward, suggesting that conditioning includes (a) a parasite-specific early phase that allows the imbibed seeds to overcome the stress caused by failing to receive an immediate germination stimulus, and (b) a non-specific later phase that is identical to the pregermination phase between seed imbibition and actual germination that is typical for all higher plants. Copyright © 2009 Society of Chemical Industry [source] Evidence of alarm pheromones in the venom of Polistes dominulus workers (Hymenoptera: Vespidae)PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2006CLAUDIA BRUSCHINI Abstract The active and coordinating capacity of defending the nest is a key feature of social insects. The present study investigates the presence of alarm pheromones in the venom of workers of the social wasp, Polistes dominulus. Laboratory experiments were performed with caged colonies of P. dominulus using a wind tunnel apparatus to test the behavioural response of workers to venom released by other workers and to venom extracts. Contrary to that previously reported for European paper wasps, the present results show that the venom is the source of alarm pheromones. Field experiments combining a visual (black target) and a chemical stimulus (venom extract) were performed to test the effect of the venom on the reaction of colonies. Wasps leave the nest, land on the visual target and attack the target significantly more once exposed to venom extract plus target than to solvent plus target. This work shows that the venom of P. dominulus workers elicits an alarm response, reduces the threshold for attack and acts as an attractant on targets. These results using P. dominulus indicate that, in both American and European species, colony defence is based on the same features, suggesting that chemical alarm is a widespread trait in the genus Polistes. [source] | ||||||||||||||||||||||||||||||||||