Dissertations / Theses on the topic 'Chemoreceptors'
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1
Lai, Runzhi. "Signal processing within and between bacterial chemoreceptors." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1337.
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Kazemian, Pedram. "Pulmonary neuroepithelial bodies as airway oxygen chemoreceptors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ54077.pdf.
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McQueen, Daniel Sinclair. "Studies on the pharmacology of carotid body chemoreceptors." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/24163.
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Yost, Christopher K. "Characterization of Rhizobium leguminosarum genes homologous to chemotaxis chemoreceptors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ31082.pdf.
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Taylor, John Andrew 1960. "RESPIRATORY CHEMOSENSITIVITY IN SYNCHRONIZED SWIMMERS AND SWIM-TRAINED WOMEN." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276444.
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Reyes, Catalina. "Peripheral arterial chemoreceptors and their role in cardio-respiratory control." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44568.
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Peripheral arterial chemoreceptors show anatomical and functional similarities and differences among vertebrate groups. Fishes have widely distributed neuroepithelial cells containing serotonin in all gill arches and extrabranchial sites, while mammals have clustered glomus cells in the carotid bifurcation and aortic arch that contain a number of neurotransmitters. However, we do not know how peripheral arterial chemoreceptors of amphibians and reptiles compare to other groups. My thesis established the location, distribution, neurochemical content, reflex roles and plasticity of peripheral arterial chemoreceptors in representative amphibians and reptiles (snakes (Crotalus durissus); turtles (Trachemys scripta elegans) and frogs (Rana catesbeiana)). I found functional chemosensory areas in the carotid bifurcation, aorta and pulmonary artery of rattlesnakes, the same locations where peripheral chemoreceptors are found in amphibians, turtles and tortoises. I used immunohistochemistry and tract tracing to identify putative O₂-sensing cells in snakes, turtles and frogs, and determined their neurochemical content and anatomical relation to branches of the glossopharyngeal and vagus nerves. Although the structure and innervation pattern of these cells is clearly maintained among vertebrate taxa, the types of neurochemicals involved in oxygen chemotransduction seem to have increased in number progressing throughout the vertebrate taxa. While serotonin is found in all vertebrates, the presence of other neurotransmitters varied among species. Catecholamines were found in the chemosensory areas of amphibians, while turtles and snakes contained acetylcholine. While the serotonergic and catecholamine containing cells were organized singly or in small clusters in amphibians and reptiles, cholinergic cells in reptiles were always arranged in large clusters. Unlike mammals, anatomically distinct chemoreceptor groups in snakes did not differ in their reflex response. All chemosensory areas regulated the respiratory and cardiovascular systems, the latter through adjustments in heart rate and the cardiac shunt. Furthermore, changes in the breathing pattern of turtles resulted from daily changes in the sensitivity of chemoreceptors independent of metabolism, indicating that biological rhythms play a role in respiratory control in reptiles. My findings suggest that while O₂-sensing structures are essential among vertebrate groups, considerable plasticity exists for the specifics of location and neurochemicals, which is likely related to differing needs to match oxygen supply and demand.
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Nunes, Ana Rita Silva Martins. "O2/CO2-sensitive cyclic AMP-signalling pathway in peripheral chemoreceptors." Doctoral thesis, Faculdade de Ciências Médicas. UNL, 2013. http://hdl.handle.net/10362/9153.
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RESUMO: O corpo carotídeo (CB) é um pequeno órgão sensível a variações na PaO2, PaCO2 e pH. As células tipo I (células glómicas) do corpo carotídeo, as unidades sensoriais deste órgão, libertam neurotransmissores em resposta às variações dos gases arteriais. Estes neurotransmissores atuam quer em
recetores pré-sinápticos, localizados nas células tipo I, quer em recetores póssinápticos, localizados nas terminações do nervo do seio carotídeo, ou em
ambos. A activação dos recetores pré-sinápticos modula a atividade do corpo
carotídeo, enquanto que, a activação dos recetores pós-sinápticos, de carater
excitatório, desencadeia um aumento da frequência de descarga das fibras do
CSN, com subsequente despolarização dos neurónios do gânglio petroso, e
posterior despolarização de um grupo específico de neurónios do centro
respiratório central, desencadeando, como resposta final, hiperventilação. Estes
recetores pré- e pós-sinápticos podem ser classificados em ionotrópicos ou
metabotrópicos, estando os últimos acoplados a adenilatos ciclases transmembranares (tmAC). O mecanismo exato pelo qual as variações dos gases arteriais são detetadas pelo CB não se encontra ainda completamente elucidado, mas tem sido sugerido que alterações nos níveis de cAMP estejam associadas ao mecanismo de deteção de variações de O2 e CO2. Os níveis de cAMP podem ser regulados através da sua via de síntese, mediada por dois tipos de adenilatos
ciclases: tmAC sensível aos eurotransmissores e adenilato ciclase solúvel (sAC)sensível a variações de HCO3/CO2, e pela sua via de degradação mediada por fosfodiesterases. A via de degradação do cAMP pode ser manipulada
farmacologicamente, funcionando enquanto alvo terapêutico para o tratamento de
patologias do foro respiratório (e.g. asma, hipertensão pulmonar, doença pulmonar obstructiva crónica e apneia do sono), que induzem um aumento da actividade do CB.O trabalho descrito nesta dissertação partiu da hipótese de que a actividade do CB é manipulada por fármacos, que interferem com a via de sinalização do cAMP, tendo sido nosso objectivo geral, investigar o papel do
cAMP na quimiotransdução do CB de rato, e determinar se a actividade dos enzimas responsáveis pela via de sinalização do cAMP é ou não regulada por variações de O2/CO2. Assim, a relevância deste trabalho é a de estudar e identificar possíveis alvos moleculares (sAC, isoformas de tmAC e PDE) com potencial para serem usados no tratamento de patologias relacionadas com o
controlo respiratório.
A primeira parte do presente trabalho, centrou-se na caracterização farmacológica da PDE4 no CB e em tecidos não quimiorecetores (e.g. gânglio cervical superior e artérias carótidas), e na observação do efeito de hipóxia aguda
na acumulação dos níveis de cAMP, induzidos pelos inibidores de PDE, nestes tecidos. A quantificação de cAMP foi efectuada por técnica imunoenzimática (EIA), tendo sido elaboradas curvas de dose-resposta para os efeitos de inibidores, não específicos (IBMX) e específicos para a PDE2 e PDE4 (EHNA, Rolipram e Ro 20-1724), nos níveis de cAMP acumulados, em situações de normóxia (20%O2/5%CO2) e hipóxia (5%O2/5%CO2). A caracterização das PDE no gânglio cervical superior foi aprofundada, utilizando-se a técnica de transferência de energia de ressonância por fluorescência (FRET) em culturas primárias de neurónios, na presença de inibidores não específicos (IBMX) e
específicos para a PDE3 e PDE4 (milrinone e rolipram, respetivamente). Foram igualmente estudadas, através de RT-qPCR, as alterações na expressão de PDE3A-B e PDE4A-D, no gânglio cervical superior, em resposta a diferentes percentagens de oxigénio.
Na segunda parte do trabalho investigou-se a via de síntese do cAMP no CB em resposta a variações na concentração de HCO3/CO2. Em concreto, o protocolo experimental centrou-se na caracterização da sAC, dado que a sua actividade é regulada por variações de HCO3/CO2. A caracterização da expressão e regulação da sAC, em resposta a variações de HCO3/CO2 ,foi efectuada no CB e em tecidos não quimioreceptores periféricos (e.g. gânglio cervical superior, petroso e nodoso) por qRT-PCR. A actividade deste enzima foi caracterizada indirectamente através da quantificação dos níveis de cAMP (quantificação por EIA), induzidos por diferentes concentrações de HCO3/CO2, na presença de MDL-12,33-A, um inibidore da tmAC. A expressão das isoformas da tmAC no CB e gânglio petroso foi determinada por RT-qPCR. Adicionalmente, estudámos a
contribuição relativa da tmAC e sAC no mecanismo de sensibilidade ao CO2 no
CB. Para o efeito foram estudadas as alterações: 1) nos níveis de cAMP
(quantificado por EIA) na presença de diferentes concentrações de HCO3/CO2 e
ao longo do tempo (5-30 min); 2) na ativação da proteína cinase A (PKA, FRET baseado em sensores) em células tipo I do CB; e 3) na frequência de descarga do CSN (registos) na presença e ausência de ativadores e inibidores da sAC,tmAC e PKA. Por último, foi caracterizada a expressão e actividade da sAC nos quimioreceptors centrais (locus ceruleus, rafe e medula ventro-lateral) através de técnicas de RT-qPCR e EIA. A expressão das isoformas da tmAC foi aprofundada no locus coeruleus através de RT-qPCR. Por fim, comparámos a contribuição da tmAC e sAC nos níveis de cAMP no locus coeruleus em condições de normocapnia e hipercapnia.O nosso trabalho teve os seguintes resultados principais: 1) PDE4 está
funcional no corpo carotídeo, artérias carótidas e gânglio cervical superior de rato, embora a PDE2 só se encontre funcional neste último; 2) Os efeitos dos inibidores de PDE nos níveis de acumulação de cAMP foram exacerbados em situações de hipóxia aguda no CB e artérias carótidas, mas foram atenuados no gânglio cervical superior; 3) No gânglio cervical superior, diferentes tipos de células apresentaram uma caracterização específica de PDEs, sugerindo uma subpopulação de células neste gânglio com funções fisiológicas distintas; 4)
Embora todas as isoformas de PDE4 e PDE3 estivessem presentes no gânglio, a PDE3a, PDE4b e a PDE4d foram as isoformas mais expressas. Por outro lado, incubações de gânglio cervical superior, em diferentes percentagens de oxigénio, não alteraram (não regularam) significativamente a expressão das diferentes isoformas de PDE neste órgão; 5) a sAC encontra-se expressa e funcional no CB e nos quimiorecetores centrais estudados (locus coeruleus, rafe e medula
ventrolateral). A sAC apresenta maior expressão no CB comparativamente aos
restantes orgãos estudados, exceptuando os testículos, orgão controlo. Variações
de HCO3/CO2 de 0/0 para 24/5 aumentaram os níveis de cAMP no CB e quimiorecetores centrais, tendo sido o aumento mais significativo observado no CB. Concentrações acima dos 24mM HCO3/5%CO2 não induziram alterações nos níveis de cAMP, sugerindo que a actividade da sAC se encontra saturada em
condições fisiológicas (normocapnia) e que este enzima não desempenha qualquer papel na deteção de situações de hipercapnia; 6) No CB, a expressão das isoformas tmAC1, tmAC4, tmAC6 e tmAC9 é mais elevada comparativamente à expressão da sAC; 7) Utilizamos diferentes inibidores da
tmAC (MDL 12-330A, 500μM, 2’5’-ddADO, 30-300μM, SQ 22536, 200μM) e da
sAC (KH7, 10-100μM) para estudar a contribuição relativa destes enzimas na
acumulação do cAMP no CB. Tanto a tmAC como a sAC contribuem para a acumulação dos níveis de cAMP em condições de hipercapnia. Contudo, existe um maior efeito destes inibidores nas condições de 12 mM HCO3/2.5%CO2 do que em condições de normocapnia e hipercapnia, sugerindo um papel relevante destes enzimas na atividade do CB em situações de hipocapnia; 8) Não se
observaram variações nos níveis de cAMP em resposta a diferentes concentrações de HCO3/CO2 ao longo do tempo (5-30 min). O efeito inibitório induzido por ddADO e KH7 foi sobreponível após 5 ou 30 minutos de incubação em todas as concentrações de HCO3/CO2 estudadas; 9) Por último, verificou-se um aumento na frequência da descarga do nervo do seio carotídeo entre as
condições de normocapnia e hipercapnia acídica. Ao contrário do KH7 (10μM), o
2’5’-ddADO reduziu significativamente a frequência de descarga do nervo, quer
em condições de normocapnia quer de hipercapnia acídica. Contudo, não se
verificou aumento na frequência de descarga do nervo entre normocapnia e hipercapnia isohídrica, sugerindo que a sensibilidade à hipercapnia no CB é mediada por variações de pH. Em conclusão, os resultados decorrentes deste trabalho permitiram demonstrar que, embora os enzimas que medeiam a via de sinalização do cAMP possam ser bons alvos terapêuticos em condições particulares, a sua actividade não é específica para o CB. Os resultados sugerem ainda que o cAMP não é um mediador específico da transdução à hipercapnia neste orgão. Contudo, os
nossos resultados demonstraram que os níveis de cAMP são mais elevados em condições fisiológicas, o que sugere que o cAMP possa ter uma função homeostática neste orgão. Por último, o presente trabalho demonstrou que os
aumentos de cAMP descritos por outros em condições de hipercapnia, não são
observáveis quando o pH se encontra controlado. ------------------ ABSTRACT: The work presented in this dissertation was aimed to establish how specific is
cAMP-signaling pathways in the CB mainly in different CO2 conditions and how O2
concentrations alter/drives the manipulation of cAMP signaling in the CB. The
experimental studies included in this thesis sought to investigate the role of cAMP
in the rat CB chemotransduction mechanisms and to determine whether the enzymes that participate in cAMP signal transduction in the CB are regulated by O2/CO2. We characterized the enzymes involved in the cAMP-signaling pathway in the CB (sAC, tmAC, PDE) under different O2/CO2 conditions. Our results demonstrated that many of these enzymes are involved in CO2/O2 sensing and
while they may be useful in treating conditions with alterations in CO2/O2 sensing,they will not be specific to chemoreception within the CB: 1) PDE4 is ubiquitously expressed in CB and non-chemoreceptor related tissues and their affinity to inhibitors change with O2 tensions in both CB and carotid arteries, and 2) sAC and tmAC are expressed in peripheral and central chemo- and non-chemoreceptor tissues and their effect on cAMP levels do not change between normocapnic and isohydric hypercapnic conditions. Our results provide evidence against a specific role of cAMP as a mediator for O2 and CO2 chemotransduction in the rat CB and emphasized the role of pH in CO2 sensitivity of the CB. Furthermore, our results demonstrate that cAMP levels are maintained higher under physiological
conditions, supporting recent finding from our lab, which all together suggests that
cAMP has a homeostatic function in this organ.
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Bormans, Arjan Frank. "Intradimer and interdimer methylation response by bacterial chemoreceptors to attractant stimulus." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4884.
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This study focuses on the mechanism of transmembrane signaling by Tar, the aspartate chemoreceptor of Escherichia coli. Like other bacterial chemoreceptors, Tar localizes to the cell membrane and relays information about the external chemical environment through the membrane to a cytoplasmic signaling domain. The output of the signaling domain controls the directional bias of the rotary flagellar motors of the cell. Net movement of a cell in a chemical gradient involves temporal comparison of the current concentration with the concentration in the recent (a few seconds) past. The current concentration is measured as the percent occupancy of the extracellular ligand-binding domain of the receptor, and the past is represented by the extent of covalent methylation of four conserved glutamyl residues in the cytoplasmic domain. Under steady-state conditions, the methylation level corresponds to ligand occupancy. Tar is a dimer, and much evidence suggests that dimers associate into trimers of dimers. Higher-order arrays of receptors form in the presence of the cytoplasmic proteins CheA and CheW. The conformational change generated by ligand binding is transmitted through the membrane by one subunit of a dimer. To examine whether this initially asymmetric signal becomes symmetric within the cytoplasmic domain, I examined aspartate-induced adaptive methylation of the two subunits of mutant Tar receptor heterodimers. In the presence of CheA and CheW, adaptive methylation after addition of aspartate was symmetric, but in their absence, although the level of methylation increased, the rates were different for the two subunits. I also found that cross-talk, at the level of adaptive methylation, occurs between different receptor types even in the absence of CheA and CheW. These results provide support for the idea that a tight association of receptor dimers within trimers of dimers allows for an actively signaling receptor to affect the methylation state, and thus presumably the signaling state, of receptors within a trimer that are not bound to an attractant ligand.
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Burleson, Mark Logan. "Oxygen-sensitive chemoreceptors and cardiovascular and ventilatory control in rainbow trout." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30963.
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Fish respond to changes in external (water) and internal (blood/tissue) O₂ levels by altering cardiovascular and ventilatory performance. These reflexes are mediated, for the most part, by O₂-sensitive chemoreceptors. Although the reflex responses of intact fishes have been characterized in detail, the receptors mediating these reflexes to hypoxia are poorly understood. To this end, afferent neural activity from O₂-sensitive chemoreceptors was recorded from the glossopharyngeal nerve (cranial nerve IX) in the isolated, perfused first gill arches of rainbow trout (Oncorhynchus mykiss).
Branchial O₂-sensitive chemoreceptors were sensitive to changes in external and/or internal O₂ tensions. Some receptors were sensitive to either internal or external O₂ levels and others were sensitive to both. External receptors showed an increase in activity as the PO₂ was decreased to about 40 torr. Below 40 torr, afferent activity was depressed but recovered as P₀₂s was increased. Reversible depression of O₂ receptor activity at low P₀₂s has been observed in mammalian O₂ receptors and is believed to illustrate the dependence of receptor activity on oxidative metabolism (Lahiri et al., 1983). Occluding perfusate flow through the gill had little effect on afferent activity indicating that the internal receptors were not very flow sensitive. Sodium cyanide, a potent O₂ receptor stimulant, dramatically increased afferent neural activity. The response characteristics of these receptors are similar to tuna gill and mammalian carotid body O₂ receptors and suggest that these may be the receptors that mediate the cardiovascular and ventilatory reflex responses of fishes to hypoxia.
A number of different neurochemicals are thought be involved in O₂ transduction. Catecholamines are released into the circulation of fishes in response to hypoxia and it was hypothesized that adrenergic stimulation of O₂ receptors might contribute to the observed reflex
responses. Epinephrine and norepinephrine stimulate O₂ receptors and ventilation in mammals (Fidone and Gonzalez, 1986). Although fish respond to large dosages of epinephrine and norepinephrine (100-1000 nmol/kg) with hyperventilation (lower dosages, 5 nmol/kg, have little or no effect in intact fish), the afferent neural activity from the branchial O₂ receptors was not affected by these neurochemicals. Thus, ventilatory responses to increased circulating catecholamines do not appear to be mediated by branchial O₂ receptors. Inhibition of O₂ receptor activity by propranolol was probably due to indirect effects. Dopamine elicited a dose-dependent brief burst of chemoreceptor activity followed by inhibition but had only modest effects on DA blood pressure and inhibited opercular pressure amplitude in intact fish.
Serotonin (5-Hydroxytryptamine) caused a transient increase in chemoreceptor activity. In intact fish, serotonin, stimulated heart rate, decreased DA blood pressure and stimulated ventilation.
Cholinergic agonists (acetylcholine, nicotine and muscarine) significantly stimulated O₂ receptor discharge. Acetylcholine and nicotine increased heart rate, DA blood pressure and ventilation in intact fish, whereas, muscarine decreased heart rate and DA blood pressure and increased ventilation. Atropine inhibited O₂ receptor activity but had little affect on ventilation in intact fish.
Cholinergic mechanisms appear to be more important than adrenergic mechanisms in controlling the cardiovascular and ventilatory reflex responses mediated by branchial Gysensitive chemoreceptors. The response characteristics of branchial O₂-sensitive chemoreceptors indicates that they are homologous to the O₂ receptors of the mammalian aortic and carotid bodies.Science, Faculty of
Zoology, Department of
Graduate
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Douse, Mark Alan. "Baroreceptor and chemoreceptor activity during nasal stimulation in the muskrat (Ondatra zibethica)." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24631.
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Diving muskrats (Ondatra zibethica) invoke a series of cardiovascular and respiratory adjustments in response to stimulation of the nares with water. This dive response is characterized by apnoea, a decrease in cardiac output and an increase in peripheral resistance. The result is that blood flow is maintained to those organs most susceptible to oxygen deprivation, the heart and the brain.
The initiation of the dive response in mammals is primarily the result of nasal stimulation with water. In addition, the baroreceptors acting via the baroreflex have been suggested to be involved in either the initiation or the maintenance of this response. The chemoreceptors, acting via the chemoreflex, have also been implicated in the maintenance of the dive response, although the importance of this contribution is controversial.
The purpose of this thesis was to examine the role of the baroreceptors and chemoreceptors in the diving response of the muskrat. Changes in input from these receptors recorded from the cut carotid sinus nerve and their modulation by the carotid sinus efferent activity during nasal stimulation may have important implications for the role of the baroreceptors and chemoreceptors in the diving response. In the initial part of the dive, baroreceptor activity decreased, while chemoreceptor activity did not change. Subsequently, baroreceptor and chemoreceptor activity increased, exceeding pre-dive levels. This increase was not due to a change in receptor threshold or sensitivity induced by the nasal stimulation, but was a reflection of the increase in the usual stimulus modality of both receptor groups.
The efferent activity recorded from the central end of the cut carotid sinus nerve was of two types, both of which responded to nasal stimulation. This change in the efferent discharge has the potential to modify afferent activity. Nasal stimulation caused one type of efferent activity (type A) to stop. The second type of efferent activity (type B) responded with an initial increase in discharge, returning to pre-dive levels after 6.6 seconds. Based-on the similar characteristics of these efferents to those of previous work it is postulated that the actions of the efferents would be to inhibit the baroreceptors and chemoreceptors during the initiation of the nasal stimulation, but to be less effective as the dive progressed.
It is concluded that there is no contribution from the baroreceptors to the initiation of the diving bradycardia, although the lack of baroreceptor activity may contribute to the increase in peripheral resistance. Later in the dive, both heart rate and arterial blood pressure increase, despite a concomitant elevation in baroreceptor activity. The baroreceptors therefore have no role in the maintenance of the diving response. The initial inhibition of the chemoreceptors may be important to permit the full expression of the dive response, including a decrease in central respiratory output. Later in the dive the chemoreceptors may contribute to the maintenance and termination of the diving response.Science, Faculty of
Zoology, Department of
Graduate
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Chow, S. N. "Investigation of radio- and chemosensitivity mechanisms in Nasopharyngeal Carcinoma cells." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22786545.
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McMahon, Michael E. "Altered chemoreceptor response and improved cycling performance following respiratory muscle training." Thesis, University of Hawaii at Manoa, 2003. http://proquest.umi.com/pqdweb?index=2&did=765961041&SrchMode=2&sid=5&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209406131&clientId=23440.
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Moore, P. J. "The involvement of peripheral chemoreceptors in the control of fetal breathing movements." Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233658.
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Webb, Benjamin Allen. "Elucidation of the Specificity of S. meliloti Chemoreceptors for Host Derived Attractants." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82140.
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The bacterium Sinorhizobium (Ensifer) meliloti is a member of the Rhizobiaceae family and can enter a mutualistic, diazotrophic relationship with most plants of the genera Medicago, Melilotus, and Trigonella. Medicago sativa (alfalfa) is an agriculturally important legume that hosts S. meliloti and allows the bacterium to invade the plant root and begin fixing nitrogen. Prior to invasion, S. meliloti exists as a free living bacterium and must navigate through the soil to find alfalfa, using chemical signals secreted by the root. Alfalfa is the 4th most cultivated crop in the United States, therefore, identification of plant host signals that lure S. meliloti, and identification of the bacterium's chemoreceptors that perceive the signals can aid in propagating the symbiosis more efficiently, thus leading to greater crop yields. Investigations here focus on discovering alfalfa derived attractant signals and matching them to their respective chemoreceptors in S. meliloti. We have determined the chemotactic potency of alfalfa seed exudate and characterized and quantified two classes of attractant compounds exuded by germinating alfalfa seeds, namely, amino acids and quaternary ammonium compounds (QACs). At all points possible, we have compared alfalfa with the closely related non-host, spotted medic (Medicago arabica). The chemotactic potency of alfalfa seed exudate is the same as spotted medic seed exudate, however, the attractant compositions are chemically different. The amount of each proteinogenic amino acid (AA) exuded by spotted medic is slightly greater than the amounts exuded by alfalfa. In addition, the five QACs studied are exuded in various amounts between the two Medicago species. In comparison, the total amount of proteinogenic AAs exuded be alfalfa and spotted medic are 2.01 μg/seed and 1.94 μg/seed respectively, and the total amount of QACs exuded are 249 ng/seed and 221 ng/seed respectively. By performing a chemotaxis assay with synthetic AA mixtures mimicking the amounts exuded from the medics, it was found that the AA mixtures contribute to 23% and 37% of the responses to alfalfa and spotted medic exudates, respectively. The chemoreceptor McpU was found to be the most important chemoreceptor of the eight for chemotaxis to the whole exudates and the AA mixtures. Furthermore, McpU is shown to mediate chemotaxis to 19 of 20 AAs excluding aspartate. McpU directly interacts with 18 AAs and indirectly mediates chemotaxis to glutamate. Through single amino acid residue substitutions, it is determined that McpU directly binds to amino acids in the annotated region called the Cache_1 domain, likely utilizing residues D155 and D182 to interact with the amino group of AA ligands. In all, McpU is a direct sensor for AAs except for the acidic AAs aspartate and glutamate. Work is presented to show that the QACs betonicine, choline, glycine betaine, stachydrine, and trigonelline are potent attractants for S. meliloti, McpX is the most important chemoreceptor for chemotaxis to these QACs, and we demonstrate the binding strength of McpX to the QACs with dissociation constants ranging from low millimolar to low nanomolar, thus making McpX the first observed bacterial MCP that mediates chemotaxis to QACs. Overall, we match medic derived AAs with McpU and QACs with McpX. These results can aid in optimizing chemotaxis to the host derived attractants in order to propagate the symbiosis more efficiently resulting in greater crop yields.
Chapter 2 characterizes the function of the S. meliloti Methyl accepting Chemotaxis Protein U (McpU) as receptor for the attractant, proline. A reduction in chemotaxis to proline is observed in an McpU deletion strain, but the defect is restored in an mcpU complemented strain. Single amino acid substitution mutant strains were created, each harboring a mutant mcpU gene. The behavioral experiments with the mutants display a reduction in chemotaxis to proline when aspartate 155 and aspartate 182 are changed to glutamates. The periplasmic region of wild type McpU was purified and demonstrated to directly bind proline with a dissociation constant (Kd) of 104 μM. The variant McpU proteins show a reduction in binding affinity confirming McpU as a direct proline sensor.
Chapter 3, describes the development of a high-throughput technique that is able to observe chemotaxis responses in ten separate chemotaxis chambers all at once. This procedure also allows for real time observations at intervals of two minutes for however long the experiment is scheduled. Using this new method it was found that McpU and the Internal Chemotaxis Protein A (IcpA) are the most involved with chemotaxis to seed exudates followed by McpV, W, X, and Y. The amounts of each proteinogenic amino acid (AA) in host and non-host seed exudates are quantified, which reveals that similar amounts are exuded from each species. It is shown that McpU is the most important receptor for chemotaxis toward synthetic mixtures that mimic the amounts seen in the exudates.
Chapter 4 further investigates the role of McpU in sensing amino acids using the high-throughput technique developed in Chapter 3. It is shown that McpU is important for chemotaxis to all individual proteinogenic amino acids except the acidic AA, aspartate. In vitro binding experiments confirm that McpU directly interacts with all AAs except the acidic AAs aspartate and glutamate. Binding parameters are determined for aspartate, glutamate, phenylalanine and proline.
In Chapter 5, five quaternary ammonium compounds (QACs) are quantified from the host and non-host seed exudates, which reveals distinctive QAC profiles. S. meliloti is found to display strong chemotaxis to all QACs, which is further shown to be mediated mostly by McpX. McpX is then established as a direct binder to all QACs as well as proline, with dissociation constants ranging from nanomolar to millimolar.
These studies have increased our knowledge of how chemoreceptors sense attractants, and they have contributed to the bank of known attractant molecules for bacteria. Our new understandings of chemotaxis and how it relates to the Sinorhizobium-alfalfa model can allow for manipulations of the system to enhance chemotaxis to the host, thus propagating the symbiosis more efficiently, ultimately leading to greater crop yields.Ph. D.
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Jackson, Adele. "Oxygen sensing, plasticity and catecholaminergic functions in cultured chromaffin cells of rat carotid body and adrenal medulla : modulation by chronic hypoxia and acetylcholine receptors /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0018/NQ30096.pdf.
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Zhong, Huijun. "Electrophysiology and transmitter sensitivities of isolated rat petrosal neurons : synapse formation and hypoxic signaling in co-culture with carotid body chemoreceptors /." *McMaster only, 1997.
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Turesson, Jenny. "Oxygen chemoreflexes in fish : with emphasis on glutamatergic control mechanisms in the medulla /." Göteborg : Göteborg University, Department of Zoology, Zoophysiology, 2006. http://www.loc.gov/catdir/toc/fy0705/2006436782.html.
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Draheim, Roger Russell. "The role of protein-membrane interactions in modulation of signaling by bacterial chemoreceptors." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1336.
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Ward, Scott Michael. "Comparison of the mechanism of transmembrane signaling in bacterial chemoreceptors and sensor kinases." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4229.
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Membrane-bound receptors transmit information from the cell exterior to the cell interior.
Bacterial receptors capable of transmitting this information include sensor kinases, which
control gene expression via response regulators, and methyl-accepting chemotaxis proteins
(MCPs), which control rotation of the flagellar motor. These receptors, which have a
similar general architecture and function, are predicted to share similar mechanisms of
transmembrane signaling. The majority of such work has been conducted on MCPs. Our
goal is to extend this work to the closely related sensor kinases by creating functional
hybrid transducers. I show that a chimeric protein (Nart) that joins the periplasmic, ligandbinding
domain of the sensor kinase NarX (nitrate/nitrite sensor) to the cytoplasmic
signaling domain of the chemoreceptor Tar is capable of modulating flagellar rotation in
response to both nitrate and nitrite. Consistent with the properties of NarX, our Nart elicits
a stronger response to nitrate than to nitrite. Introduction of mutations into a highly
conserved periplasmic region affects Nart signaling in a fashion that is consistent with the
effects seen in NarX. I also present the first example of a substitution in a presumed
ligand-binding domain that confers a reverse-signal phenotype for both nitrate and nitrite in Nart. These results support the hypothesis that the key aspects of transmembrane
signaling are closely similar in homodimeric bacterial chemoreceptors and sensor kinases.
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Kumar, Prem. "Oscillations in the discharge of arterial chemoreceptors : their origin and some reflex effects." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371545.
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Greaney, Jody. "Interaction of chemoreceptors and osmoreceptors in the control of sympathetic outflow in healthy humans." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 51 p, 2009. http://proquest.umi.com/pqdweb?did=1889099011&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Mayola, Coromina Albert. "Relationship between the SOS system and the chemoreceptors clustering in Salmonella enterica sv. Typhimurium." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/131316.
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La proteïna RecA és coneguda per ser la principal recombinasa bacteriana I també l’activador del sistema SOS. RecA no només s’associa amb processos de reparació del DNA sinó que també està relacionada amb altres funcions com ara el control d’integrons, la transferència de resistències antibiòtiques i d’elements de virulència o la inducció de pròfags. A més, en els últims anys s’ha associat a la proteïna RecA un nou paper com a modulador del moviment en eixam o swarming a E. Coli i a S. Typhimurium. A dia d’avui, es coneix que tant la deficiència com l’excés de RecA causen una disminució dràstica de la capacitat de desplaçar-se mitjançant swarming. També es coneix que, en una soca de S. Typhimurium que sobreexpressa recA i que per tant és incapaç de desplaçar-se per swarming, aquest moviment es pot recuperar a través de l’expressió concomitant del gen cheW, indicant que in vivo aquestes dues proteïnes poden estar relacionades. A més, hi ha evidències experimentals de la interacció entre les proteïnes RecA i CheW in vitro.
El gen cheW és un dels gens que componen el nucli de l’aparell de quimiotaxi. El seu producte, la proteïna CheW, és la encarregada de l’acoblament entre la proteïna CheA (una histidina quinasa) i els trímers de dímers de quimioreceptors formant la unitat de senyalització bàsica per la quimiotaxi. Es coneix que diverses unitats de senyalització són capaces d’agregar als pols de la cèl·lula donant lloc a una estructura macromolecular coneguda com a clústers de quimioreceptors que, a part de tenir un paper en la transducció de la senyal quimiotàctica, són necessaris per el moviment en swarming. De fet, mutants de E. Coli que sobreexpressen o presenten deficiències en el gen cheW presenten també una estructuració aberrant dels clústers de quimioreceptors, fet que s’ha relacionat amb els defectes en la quimiotaxis i el swarming també observats en aquestes cèl·lules.
El mecanisme molecular a través del qual els sistema SOS, i més concretament RecA, modula el moviment per swarming encara es desconeix. De tota manera, hi ha suficients evidències que apunten a una connexió entre el sistema SOS i el sistema de quimiotaxi a través de la interacció entre les proteïnes RecA i CheW. Per això, el principal objectiu d’aquest treball és aclarir el paper del sistema SOS, i de la proteïna RecA, en el moviment per swarming de S. Typhimurium.
Els resultats presentats en aquest treball demostren que les proteïnes RecA i CheW de S. Typhimurium són capaces d’interaccionar tant in vivo com in vitro. A més, també es demostra la tenir una estequiometria concreta entre aquestes dues proteïnes constitueix un factor clau a la hora de desplaçar-se per swarming. El mecanisme molecular que permet al sistema SOS controlar la motilitat per swarming encara no ha pogut ser descobert però en aquest treball es demostra que soques de S. Typhimurium que sobreexpressen recA i mutants deficients en el mateix gen presenten severes deficiències en l’estructuració dels clústers polars de quimioreceptors.
En conclusió, el present treball clarifica la relació existent entre el sistema SOS i els sistema de quimiotaxi a S. Typhimurium a través de la interacció entre les proteïnes RecA i CheW. Malgrat la demostració de que la variació de la concentració cel·lular de RecA a les cèl·lules ocasiona defectes en l’estructuració dels clústers de quimioreceptors, el mecanisme molecular que permet la regulació del swarming a través de RecA encara no s’ha establert. En aquest treball, s’hipotetitza que RecA afecta el procés de formació de clústers de quimoreceptors a S. Typhimurium i que l’impediment de formar aquests clústers correctament és el motiu principal per el qual els mutants recA presenten defectes en el moviment per swarming.The RecA protein is known to be the main bacterial recombinase and the activator of the SOS system. RecA is associated not only with DNA repair but also with several other functions such as the control of integron dynamics, prophage induction and the transfer of antibiotic resistances and virulence factors. Furthermore, in the last years a novel role of the RecA protein as a modulator of the swarming motility in E. coli and S. Typhimurium has been revealed. Up to date, it is known that the lack or the excess of RecA causes a dramatic depletion of the swarming motility in the aforementioned bacterial species. Also, the ability to swarm of an S. Typhimurium strain that overexpresses the recA gene can be recovered by concomitantly overexpressing the cheW gene. Moreover, there are experimental evidences of the interaction between RecA and CheW proteins. The cheW gene is one of the chemotaxis system core genes. Its product, the CheW protein, is known to serve in the cell as the coupling protein between the CheA histidine kinase and the chemoreceptors trimers of dimers to form the basic chemotaxis signaling unit. Several chemotaxis signaling units are known to aggregate at the cell poles forming a macromolecular structure known as chemoreceptor signaling arrays that, apart from their role in signal transduction during chemotaxis, are known to be required for swarming motility. E. coli mutants that either overexpress or lacks the cheW gene are known to have severe impairments in the formation of this chemoreceptor clusters. This, have been linked with the depletion of the swarming and chemotactic abilities displayed by those mutants The molecular mechanism by which the SOS system modulates the swarming motility through RecA still remains unknown. There are sufficient evidences pointing towards a link between the chemotaxis and the SOS systems through a RecA-CheW interaction. Thus, the main aim of this work is to elucidate the role of the SOS system through the RecA protein in the swarming motility of S. Typhimurium. Results presented here demonstrate that RecA and CheW proteins of S. Typhimurium are able to interact both in vivo and in vitro thus establishing a link between the SOS system and the bacterial motility. Also, the importance of a concrete stoichiometric relationship between both proteins have been established as a key factor for swarming motility. The molecular mechanism that exactly allows the SOS system to control the swarming motility still remains poorly understood but in this work it has been demonstrated that strains that either overexpress or lack the recA gene present a severe impairment to successfully structuring the chemoreceptor clusters arrays at its cell poles. In conclusion, the present work clarifies the relationship between the SOS and chemotaxis systems of S. Typhimurium through the interaction between the RecA and CheW proteins. The molecular mechanism behind the RecA modulation of the swarming motility still needs to be further investigated but in this work the affectation of the ability to form chemoreceptor signaling arrays in cells with an excess or lack of RecA is reported. Thus, it is hypothesized that RecA affects the clustering process in S. Typhimurium and that the inability to successfully form this clusters is at the core of the swarming impairment shown by the recA mutants of this specie.
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Stein, Pamela. "Fetal responses to prolonged reduced uterine blood flow, the role of the peripheral chemoreceptors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ31109.pdf.
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Kirby, Geoffrey Charles. "Studies on the effects of some polypeptides and monoamines on the carotid body chemoreceptors." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/19018.
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Jones, Christopher William. "Dynamics, formation and segregation of the cytoplasmic chemoreceptor cluster in Rhodobacter sphaeroides." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:73ce27e2-260e-4b1d-a746-cf7e7df6a02e.
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The internal organisation of bacteria is far more complex than originally thought. Many components of the cell have specific localisation patterns. Proteins are localised to many different regions of the cell by numerous mechanisms, and often their function depends on correct localisation. Bacterial and plasmid DNA are also highly organised and actively positioned. These tightly regulated positioning patterns ensure stable maintenance of genetic material. Members of the ParA/MinD family of ATPases are responsible for the segregation of a large number of bacterial chromosomes and plasmids. Recently members of this family have been shown to position and segregate protein complexes. One such complex is the cytoplasmic chemosensory cluster of Rhodobacter sphaeroides. This large complexes are segregated from a single cluster positioned at the mid-cell to two clusters at 1/4, 3/4 positions by the ParA homologue PpfA using the nucleoid as a scaffold. This ensures that each daughter cell inherits a cluster. This study sought to investigate this cytoplasmic chemosensory cluster, and its positioning and segregation by PpfA through the cell cycle. The use of fluorescence recovery after photobleaching revealed that like membrane bound chemoreceptor arrays the cytoplasmic cluster of R. sphaeroides is a highly stable complex. The difference seen between the cytoplasmic cluster and the data reported for the membrane bound cluster of Escherichia coli is probably due to the lack of membrane helping hold the array together. Investigation of the role of PpfA in segregation of the cytoplasmic cluster, using fluorescence imaging and single molecule tracking with a range of mutants through the cell cycle, suggest that it uses a mechanism unlike any reported for ParA homologues. Single molecule tracking of PpfA molecules shows that the chemoreceptor TlpT stabilises PpfA molecules resulting in slower diffusion of PpfA molecules at the cluster. The use of a ΔppfA mutant shows that PpfA restrains the movement of the cluster, together these results suggest a model in which TlpT stabilises PpfA’s interaction with the nucleoid and PpfA positions the cluster.
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Campanucci, Veronica A. Nurse Colin A. "Electrophysiological properties, PO₂- and ATP-sensitivity of paraganglion neurons of the rat glossopharyngeal nerve /." *McMaster only, 2004.
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Andrews, Dawn Michele. "Chemical Communication in House Mice (Mus musculus): Can They Recognize Gender from the Anogenital, Harderian Gland or Mouth/Nose Odor?" PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5230.
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Identifying the sensory systems animals employ to communicate chemically and the function of the chemical signals facilitates further understanding of chemical communication. Increased knowledge of how animals use the olfactory and vomeronasal systems in order to interpret the meaning of body odors will aid in developing a more detailed organization of chemosensory pathways. The message that each body odor contains can change from species to species. The purpose of this thesis was to study three previously untested body odors in house mice (M musculus) for their role in gender recognition of conspecifics. These odors are the anogenital (feces, urine, and preputial gland secretions), the Harderian gland (Harderian gland sebaceous secretion; gland located at inner comer of eye), and mouth/nose (saliva, mucus, and food). The amount of time in seconds and the number of sniffs were measured in an habituation paradigm which involved four trials per odor. The means of the amount of time spent sniffing and the number of sniffs per odor showed that the mice sniffed the novel odor the most, the non-novel an intermediate amount, and the control the least amount. The mice recognized the novel as foreign and the non-novel as familiar and the mice could not determine the gender of the odor-donor from any of the three odors.
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Wyon, Nicholas. "On the interaction between a neuromuscular blocking agent and regulation of breathing during hypoxia /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-659-6.
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Sachs, Nadja [Verfasser], and Victor [Akademischer Betreuer] Sourjik. "Effects of membrane lipid composition on the organization and signalling properties of bacterial chemoreceptors / Nadja Sachs ; Betreuer: Victor Sourjik." Marburg : Philipps-Universität Marburg, 2020. http://d-nb.info/1223130479/34.
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Henriques, Virgínia Maria Cavalari [UNESP]. "Desenvolvimento ontogenético de estruturas sensoriais em Macrobrachium rosenbergii (De Man 1879) (Crustacea, Palaemonidae)." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/100200.
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Os crustáceos dispõem de estruturas sensitivas que permitem receber estímulos do meio. Estes são usados para localizar e capturar o alimento. As estruturas de quimiorrecepção e mecanorrecepção são reconhecidas como os principais sentidos usados pelos crustáceos decápodas para identificação de partículas alimentares. O Macrobrachium rosenbergii é uma espécie que passa por uma fase planctônica e outra bentônica, faz grandes migrações a favor ou contra a corrente conforme a fase do ciclo de vida ou estágio fisiológico e muda o hábito alimentar de carnívoro à onívoro. Portanto, deve apresentar mecanismos de percepção dos estímulos do meio, que se modificam ao longo do desenvolvimento. Assim, a hipótese levantada nessa pesquisa foi que M. rosenbergii apresenta estruturas sensitivas na superfície do corpo e apêndices, que se modificam desde a eclosão da larva até a fase adulta. O objetivo deste trabalho foi pesquisar a ocorrência de estruturas sensitivas ao longo do desenvolvimento ontogenético de M. rosenbergii. A pesquisa ocorreu no setor de carcinicultura do CAUNESP. As larvas e pós-larvas foram coletadas de larvicultura sob sistema fechado dinâmico segundo Valenti (1998) e os juvenis e adultos dos sistemas de cultivo do setor. Os animais foram fixados com Karnovsky e dissecados. De cada animal, retiraram-se as antênulas, as antenas, as maxilas, as placas mandibulares, os três maxilípedes e os olhos para possibilitar a observação dos apêndices e as estruturas sensitivas. Os apêndices e olhos foram metalizados e fotodocumentados em microscópio eletrônico de varredura. Os olhos também foram analisados com técnicas de microscopia eletrônica de transmissão e técnica de rotina para análises histológicas segundo Behmer (2003). Identificaram-se setas sensitivas em todos os estágios larvais, pós-larva, juvenil e adulto. Elas distribuem-se em todos...
The crustaceans dispose of sensitive structures that allow them to receiive stimuli from environment. These are used to locate and capture food. Chemoreceprion and mechanoreption are known as the main senses used by the decapod crustaceans to indentify food particles. The Macrobrachium rosenbergii is a species that goes through a planktonic and a benthonic phase performs great migrations against or within the current depending on the life cycle phase or physiological stage and changes its feeding haits from carnivorous to omnivorous. Thus, it should present perception mechanisms of environment stimuli that are modified during development. Therefore, the hypotheisis brought up in this research was that the M. rosenbergii presents sensitive structures on the surface of the body and appendices that change from since the hatching of the larva up to the adult phase. The object of this paper was to research the occurrence of the sensitive structures during the entogenetic development of the M. rosenbergii. The research was performed at the carciniculture sector of the CAUNESP. The larvae and post larvae were collected from larvae culture under a closed dynamic system according to Valenti (1998) and the yong and adult larvae from the cultivating systems of the sector. The animals were set with Karnovsky and dissected. From each animal the antennules, the antennas, the maxillas, the mouthpiece plates, the three maxilipedes and the sensitve structures. The appendices and eyes were metalized and photo documented by way of electronic transmission techniques and rotine techniques for histological analysis according to Behmer (2003). Sencitive setae were identified in all larval stages, post larval, young and adult. They are distributed in all of the dissected appendices with Intense morphological variantions. They present. They present typical morphological pattern of the sensitive setae, with basal... (Complete abstract click electronic access below)
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周淑雅 and S. N. Chow. "Investigation of radio- and chemosensitivity mechanisms in Nasopharyngeal Carcinoma cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31224283.
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Hargens, Trent Alan. "The Effects of Obstructive Sleep Apnea Syndrome on Cardiovascular Function with Exercise Testing in Young Adult Males." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/26185.
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Obstructive sleep apnea syndrome (OSAS) is a serious disorder that affects an estimated 24% of middle-age males, and 9% of middle-aged females. In addition, a large portion of individuals with OSAS go undiagnosed. OSAS is associated with several adverse health problems, including the metabolic syndrome. Therefore, there is a clear need to identify new methods for assessing OSAS risk. The exercise test has been used effectively as a diagnostic and prognostic tool for those at high risk for cardiovascular disease and hypertension. Research into the cardiopulmonary responses to exercise testing in young adult men with OSAS has not been examined. Objectives: The objectives of this study were to: 1) evaluate whether OSAS is characterized by exaggerated ventilatory responses to ramp exercise testing, with a secondary aim to evaluate if variations in serum leptin concentration might exert a regulatory in ventilatory responses during exercise; 2) To evaluate whether autonomic control of the cardiovascular response during exercise is distorted by OSAS in young overweight men, as manifested by a blunting of heart rate and exaggeration of blood pressure responses.; 3) To explore whether various simple clinical measures and response patterns from graded exercise testing might serve to discriminate between young men with and without OSAS. Methods: For objectives one and two, 14 obese men with OSAS [age = 22.4 ± 2.8; body mass index (BMI) = 32.0 ± 3.7; apnea-hypopnea index (AHI) = 22.7 ± 18.5], 16 obese men without OSAS (age = 21.4 ± 2.6; BMI = 31.4 ± 3.7), and 14 normal weight subjects (objective 2) (age = 21.4 ± 2.1; BMI = 22.0 ± 1.3) were recruited. For objective three, 91 men (age = 21.6 ± 2.8; AHI range = 0.6 â 60.5; BMI range = 19.0 â 43.9) were recruited. Subjects completed a ramp cycle ergometer exercise test, and a fasting blood sample was obtained to measure plasma leptin and blood lipid levels. Repeated measures ANOVA and stepwise linear regression was used to examine objectives 1 and 2. For objective 3, stepwise linear regression and receiver operator curve (ROC) analysis was utilized. Results: Ventilation (VE), the ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2) were greater in the OSAS subjects vs. the overweight subjects without OSAS (P = 0.05, P < 0.05 and P < 0.005, respectively) at all exercise intensities. Heart rate (HR) recovery was attenuated in the overweight OSAS subjects compared to the No-OSAS and Control groups throughout 5 minutes of active recovery (P = 0.009). Oxygen uptake, HR, and blood pressure did not differ throughout exercise. Leptin was not associated with ventilatory responses at any exercise intensity. Linear regression analysis revealed hip-to-height ratio (HHR), hip circumference (HC), triglyceride levels, and recovery systolic blood pressure ratio (SBPR) at 2 and 4 minutes were independent predictors of AHI (model fit: R2 = 0.68, p <0.0001). ROC analysis determined that percent body fat, HHR, and recovery HR at 2 minutes and 4 minutes were the best single predictors of OSAS risk (AUC = 0.77 for each measure, p = 0.003). Conclusions: Unique ventilatory and hemodynamic characteristics to maximal exercise testing are exhibited in young men with OSAS. These characteristics may be related to alterations in the sympathetic nervous system and chemoreceptor activation, and may be early clinical signs in the progression of OSAS. These exercise characteristics, along with anthropometric and body composition measures may provide useful information in identifying young men at risk for OSAS.Ph. D.
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Wickström, Ronny. "Respiratory control in the newborn : central chemosensitivity, neuropeptides and nicotinic effects /." Stockholm : Karolinska Univ. Press, 2002. http://diss.kib.ki.se/2002/91-7349-323-6/.
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Cohen, Staci Padove. "Functional identification and initial characterization of a fish co-receptor involved in aversive signaling." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29677.
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Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2009.Committee Chair: McCarty, Nael A.; Committee Co-Chair: Kubanek, Julia; Committee Member: Derby, Charles; Committee Member: Goodisman, Michael; Committee Member: Pardue, Machelle; Committee Member: Weissburg, Marc. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Moura, Lidia Ana Zytynski. ""Modulação do quimioreflexo por hipóxia e hipercapnia durante exercício submáximo na insuficiência cardíaca"." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-27092005-161809/.
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A dispnéia na insuficiência cardíaca(IC) é complexa, com possível envolvimento de quimioreceptores periféricos(QP) e centrais(QC). Avaliamos a resposta de QP e QC no exercício submáximo em 15 pcts com IC e 7 ind. normais em testes ergoespirométricos de caminhada de 6 min: hipóxia isocápnica(HPX),hipercapnia hiperóxica(HPC) e ar ambiente. HPX aumentou ventilação (VE) com resposta aguda(RVA), freq. cardíaca(FC) e volume de O2 consumido;reduziu o espaço morto,distância caminhada(DC) e pressão arterial sistêmica(PAS). A HPC aumentou VE acima da HPX com RVA.Os QP têm ação maior sobre FC e PAS do que QC, apesar da maior ativação simpática.QP possuem estimulo rápido sobre VE,porém menor do que QC.Heart failure(HF) dyspnea is complex with potential enrolment of central(CC) and peripheric chemoreceptors(PC).We investigated CC and CP behavior through submaximal exercise in 15 HF patients and 7 normal subjects in treadmill 6-minute cardiopulmonary walking tests:isocapnic hypoxia(HPO), hypercapnia hyperoxic(HCP) and room air.HPO increased:ventilation(VE) with acute ventilatory response(AVR), heart rate (HR) and O2 uptake and reduced dead space, distance walked (DW) and systemic blood pressure(SBP).The HPC improved VE above HPO level with AVR. PC have greater action on HR and SBP than CC,despite their largest sympathetic activation. PC have faster impulse on VE although be lowest than CC
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Henriques, Virgínia Maria Cavalari. "Desenvolvimento ontogenético de estruturas sensoriais em Macrobrachium rosenbergii (De Man 1879) (Crustacea, Palaemonidae) /." Jaboticabal : [s.n.], 2006. http://hdl.handle.net/11449/100200.
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Orientador: Wagner Cotroni ValentiBanca: Laura Satiko Okada Nakaghi
Banca: Irene Bastos Franceschini Vicentini
Banca: Helenice Pereira de barros
Banca: Roberto Munehisa Shimizy
Resumo: Os crustáceos dispõem de estruturas sensitivas que permitem receber estímulos do meio. Estes são usados para localizar e capturar o alimento. As estruturas de quimiorrecepção e mecanorrecepção são reconhecidas como os principais sentidos usados pelos crustáceos decápodas para identificação de partículas alimentares. O Macrobrachium rosenbergii é uma espécie que passa por uma fase planctônica e outra bentônica, faz grandes migrações a favor ou contra a corrente conforme a fase do ciclo de vida ou estágio fisiológico e muda o hábito alimentar de carnívoro à onívoro. Portanto, deve apresentar mecanismos de percepção dos estímulos do meio, que se modificam ao longo do desenvolvimento. Assim, a hipótese levantada nessa pesquisa foi que M. rosenbergii apresenta estruturas sensitivas na superfície do corpo e apêndices, que se modificam desde a eclosão da larva até a fase adulta. O objetivo deste trabalho foi pesquisar a ocorrência de estruturas sensitivas ao longo do desenvolvimento ontogenético de M. rosenbergii. A pesquisa ocorreu no setor de carcinicultura do CAUNESP. As larvas e pós-larvas foram coletadas de larvicultura sob sistema fechado dinâmico segundo Valenti (1998) e os juvenis e adultos dos sistemas de cultivo do setor. Os animais foram fixados com Karnovsky e dissecados. De cada animal, retiraram-se as antênulas, as antenas, as maxilas, as placas mandibulares, os três maxilípedes e os olhos para possibilitar a observação dos apêndices e as estruturas sensitivas. Os apêndices e olhos foram metalizados e fotodocumentados em microscópio eletrônico de varredura. Os olhos também foram analisados com técnicas de microscopia eletrônica de transmissão e técnica de rotina para análises histológicas segundo Behmer (2003). Identificaram-se setas sensitivas em todos os estágios larvais, pós-larva, juvenil e adulto. Elas distribuem-se em todos... (resumo completo, clicar acesso eletrônico abaixo)
Abstract: The crustaceans dispose of sensitive structures that allow them to receiive stimuli from environment. These are used to locate and capture food. Chemoreceprion and mechanoreption are known as the main senses used by the decapod crustaceans to indentify food particles. The Macrobrachium rosenbergii is a species that goes through a planktonic and a benthonic phase performs great migrations against or within the current depending on the life cycle phase or physiological stage and changes its feeding haits from carnivorous to omnivorous. Thus, it should present perception mechanisms of environment stimuli that are modified during development. Therefore, the hypotheisis brought up in this research was that the M. rosenbergii presents sensitive structures on the surface of the body and appendices that change from since the hatching of the larva up to the adult phase. The object of this paper was to research the occurrence of the sensitive structures during the entogenetic development of the M. rosenbergii. The research was performed at the carciniculture sector of the CAUNESP. The larvae and post larvae were collected from larvae culture under a closed dynamic system according to Valenti (1998) and the yong and adult larvae from the cultivating systems of the sector. The animals were set with Karnovsky and dissected. From each animal the antennules, the antennas, the maxillas, the mouthpiece plates, the three maxilipedes and the sensitve structures. The appendices and eyes were metalized and photo documented by way of electronic transmission techniques and rotine techniques for histological analysis according to Behmer (2003). Sencitive setae were identified in all larval stages, post larval, young and adult. They are distributed in all of the dissected appendices with Intense morphological variantions. They present. They present typical morphological pattern of the sensitive setae, with basal... (Complete abstract click electronic access below)
Doutor
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Bukusoglu, Gul H. "Genetic and Biochemical Analysis of the Activation Mechanism of the Saccharomyces Cerevisiae Pheromone Receptor." eScholarship@UMMS, 1998. https://escholarship.umassmed.edu/gsbs_diss/152.
Full textAbstract:
Activation mechanism of the α-factor pheromone receptor of Saccharomyces cerevisiae was analyzed using biochemical and genetic techniques. An in vitro partial proteolysis assay was developed to determine the conformational change of the receptor that occurs upon binding of agonist. The activation specific cleavages were established by comparing cleavage products with antagonist versus agonist occupied receptor. Of the changes in peptide pattern that were revealed by trypsinization, the fragment resulting from the exposure of the third loop to the protease was found to be agonist specific and to be G-protein independent. A low-affinity binding receptor mutant was isolated which failed to undergo this agonist induced conformational change. Four intra-allelic suppressors of this receptor mutant were isolated and all were mapped to the ends of transmembrane helices 4, 5, 6 and 7; all were found to be replacements of non-polar residues by polar ones. The role of the suppressor mutations in conformational change was analyzed.
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Beloka, Sofia. "Contribution to the study of sympathetic nervous system modulation of exercise capacity: effects of ß-blocker and ß2-stimulant drugs." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209831.
Full textAbstract:
The sympathetic nervous system plays a key role in the regulation of cardiovascular and ventilatory responses during exercise. The regulation of the heart and peripheral circulation by the autonomic nervous system is accomplished by control centers that receive input from mechanical and chemical receptors through the body. Therefore, the changes in sympathetic and parasympathetic activity allow for rapid responses. Exercise is associated with increases of ventilation, heart rate and blood pressure. Ventilation increases adaptedly to increased oxygen uptake (VO2) and carbon dioxide output (VCO2) and eventually to limit metabolic acidosis occurring above the ventilatory threshold. Cardiac output increases to meet the contracting muscles’ requirement for flow. The increase in cardiac output occurs through increases in both heart rate and stroke volume and is regulated by feed-forward mechanisms: central command and exercise pressor reflex.
Skeletal muscle contraction elicits a reflex increase in sympathetic outflow which causes vasoconstriction contributing to the exercise induced rise in blood pressure. This reflex is triggered by stimulation of metabo- and chemoreceptors. Although the precise stimulus is not known, adrenergic receptor signaling is involved in the cardiovascular and respiratory alterations in response to exercise.
This thesis has been devoted to a better understanding of the functional aspects of sympathetic nervous system activation during dynamic and resistive exercise, with use of β blocker and β2 stimulant interventions The hypotheses were: 1) that β blocker interventions would decrease aerobic exercise capacity by a limitation of maximal cardiac output, but more so the ventilatory responses to exercise because of a decreased chemosensitivity, thereby decreasing dyspnea, and 2) β2 stimulant interventions would slightly increase aerobic exercise capacity by an increase in maximal cardiac output, but also the ventilatory responses because of an increased chemosensitivity, with possible decrease of the ventilatory reserve at exercise and increased dyspnea. Both interventions could affect maximal muscle strength through central effects.
Ventilatory responses to hyperoxic hypercapnia (central chemoreflex) and to isocapnic hypoxia (peripheral chemoreflex) were confronted to measurements of ventilatory equivalents for oxygen (O2) and carbon dioxide (CO2) during standard cardiopulmonary exercise test (CPET). Resting 5 measurements of muscle sympathetic nervous activity (MSNA) were obtained in different conditions with and without pharmacological interventions. Muscle metaboreflex and muscle stength measurements were also considered. Drugs with β blocker or β2 stimulant properties were administered in range of doses used in clinical practice for the teatment of cardiovascular or rerspiratory conditions. The results show that β blockade with bisoprolol slightly reduced maximal exercise capacity as assessed by a maximal oxygen uptake (VO2max) or maximal workload (Wmax), with a decreased maximal heart rate, without significant effect on ventilation (VE) or MSNA responses to hypercapnia, hyperoxia or to isometric muscle contraction or ischemia. Both VE/VO2 and VE/VCO2 slopes were decreased during CPET, which was attributable to β blockade-related hemodynamic changes. On the other hand, stimulation of β2 receptors with salbutamol did not affect exercise capacity as assessed by VO2max or Wmax in spite of increased peripheral chemosensitivity with increased VE/VCO2 slopes and early lactic acidosis. MSNA burst frequency, muscle metaboreflex and maximal isokinetic muscle strength were not affected by salbutamol.
Thus, aerobic exercise capacity in healthy subjects is sensitive to sympathetic nervous system modulation by β blocker or β2 stimulant interventions with drugs at doses prescribed in clinical practice. B blocker intervention has a slight limitation of aerobic exercise capacity and a hemodynamic decrease in ventilation, while β2 stimulant intervention has no change in exercise capacity with associated increased ventilatory responses because of increased chemosensitivity, partly related to early lactic acidosis. None of the studied phamacologic interventions affected MSNA or muscle strength measurements.
We hope that these results might be useful for the understanding of the effects of revalidation to exercise of patients treated with β blocker or β2 stimulant drugs, document the limited ergogenic properties and also side effects of the intake of these substances in healthy exercising subjects.
Doctorat en Sciences de la motricité
info:eu-repo/semantics/nonPublished
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Florez, Guilherme Gainett Cardoso Martins de Carvalho. "Estruturas sensoriais tarsais de opiliões (Arachnida, Opiliones): morfologia funcional, evolução e uso em sistemática." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-15122016-144100/.
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Opiliões (Arachnida, Opiliones) são especialmente dependentes da quimiorecepção de contato, além de serem muito dependentes de altos níveis de umidade e de temperaturas amenas. No entanto, o conhecimento acerca das estruturas que detectam esses estímulos é muito limitado em opiliões, quando comparado ao que se sabe sobre outros aracnídeos. Além disso, são raros os estudos investigando a morfologia interna dessas estruturas - um tipo de informação essencial para a determinação de suas funções- e o potencial das sensilla para a sistemática. Neste trabalho, nós investigamos as sensilla tarsais de todos os pares de perna do opilião Heteromitobates discolor (Laniatores, Gonyleptidae), buscando refinar o conhecimento das sensilla quimioreceptoras e investigar a localização dos receptores de temperatura e umidade, através de microscopia eletrônica de varredura (MEV) e transmissão. Para determinar a abrangência dos resultados obtidos com H. discolor e testar o uso de algumas estruturas para a sistemática do grupo, realizamos uma amostragem com MEV em espécies das quatro subordens de Opiliones (Cyphophthalmi, Eupnoi, Dyspnoi e Laniatores), com foco em Laniatores (subordem com 2/3 das espécies do grupo). Na primeira parte, fornecemos a primeira evidência morfológica de receptores olfativos em Laniatores (em H. discolor), mostrando que há abundância e diversidade de sensilla olfativas. Além disso, fornecemos evidência (com MEV) de cerdas olfativas em 17 famílias de Laniatores, o que sugere que a olfação é mais importante para os Laniatores do que previamente considerado. Na segunda parte, fornecemos a primeira evidência morfológica de detectores de umidade e temperatura em opiliões (em H. discolor), discutindo os mecanismos de funcionamento dessas estruturas e uma associação morfológica entre elas, localizada na parte mais distal das pernas I e II. Por fim, mostramos que essas sensilla candidatas a detectores de umidade e temperatura são extremamente conservadas em Laniatores (28 famílias), e que existem estruturas comparáveis em espécies de Cyphophtalmi, Eupnoi e Dyspnoi. Com uma análise de reconstrução de estado ancestral em uma filogenia de Opiliones compilada da literatura, mostramos que as variações na morfologia externa dessas estruturas fornecem informação filogenética em vários níveis de relacionamento em Opiliones. Esse estudo contribui para o conhecimento de aspectos básicos da anatomia celular de sensilla em Opiliones, refinando o conhecimento sobre a função das sensilla tarsais e forncendo uma base para fomentar o uso de sensilla para a sistemática do grupoHarvestmen (Arachnida, Opiliones) are especially dependent on contact chemoreception and are dependent on high humidity levels and amenable temperatures. However, knowledge on the sensory structures (sensilla) that detect such stimuli is limited in harvestmen when compared with other arachnid orders. Besides, there are few studies investigating the internal morphology of these structures -which is important for inferring function - and the potential of sensilla for systematics. To refine the knowledge on chemoreceptive sensilla and investigate the identity of hygro- and thermoreceptors, we investigated the tarsal sensilla of all leg pairs of the species Heteromitobates discolor (Laniatores, Gonyleptidae), using scanning electron microscopy (SEM) and transmission electron microscopy. To determine scope of the results obtained with H. discolor and to test the use of some structures for systematics, we surveyed (with SEM) species in all four suborders of Opiliones (Cyphophthalmi, Eupnoi, Dyspnoi and Laniatores), with focus in Laniatores (suborder with 2/3 of harvestmen species). In the first part, we provide the first morphological evidence of olfactory receptors in a species of Laniatores (H. discolor), showing that olfactory sensilla are abundant and diverse. Also, we show evidence (with SEM) of olfactory sensilla on 17 families of Laniatores, which suggests that olfaction is more important for Laniatores than previously considered. In the second part, we provide the first morphological evidence of hygro- and thermoreceptors in harvestmen (in H. discolor) discussing the functioning mechanisms of these structures and their morphological inter-association on the distal-most part of leg pairs I and II. Finally, we show that these putative hygro- thermoreceptive sensilla are widespread in species of Laniatores (28 families) and that comparable structures occur on species of the suborders Cyphophthalmi, Eupnoi and Dyspnoi. With an ancestral state reconstruction on a compiled phylogeny of Opiliones, we show that morphological variations on these sensilla are informative on several levels of phylogenetic relationships in Opiliones. This study constributes for the basic knowledge on the cellular anatomy of Opiliones sensilla, refining the function of tarsal sensillar types and providing a base for their use in systematics
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Damasceno, Rosélia dos Santos. "Envolvimento do núcleo Kölliker-Fuse e do núcleo parabraquial lateral no controle cardiorrespiratório promovido pela ativação dos quimiorreceptores centrais e periféricos." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-10072014-162705/.
Full textAbstract:
No presente trabalho, avaliamos o envolvimento da região Kölliker Fuse (KF) e núcleo parabraquial lateral (NPBL) nas respostas cardiorrespiratórias induzidas pela ativação dos quimiorreceptores centrais e periféricos em ratos não anestesiados. A injeção bilateral de muscimol (200 pmol/100 nl) no KF reduziu a ventilação basal (978 ± 100, vs. salina: 1436 ± 155 ml/kg/min). Injeção de muscimol no KF reduziu a hiperventilação (1827 ± 61, vs. salina: 3179 ± 325 ml/kg/min) e a taquicardia (380 ± 9, vs. salina: 423 ± 12 bpm), produzidos pela hipóxia (8% O2 - 10 min). Muscimol no KF reduziu a hiperventilação (1488 ± 277, vs. salina: 3539 ± 374 ml/kg/min) produzida por hipercapnia (7% CO2 - 10 min). Injeção de muscimol no NPBL promoveu um aumento de PAM (D = 119 ± 2, vs. salina: 104 ± 2 mmHg), mas não foi capaz de alterar a hiperventilação produzida por hipóxia e hipercapnia. Nossos experimentos mostram a participação da região KF, e não do NPBL, no controle do respiratório durante a ativação do quimiorreflexo central e periférico.Here we evaluated the involvement of Kölliker-Fuse region (KF) and lateral parabrachial nucleus (LPBN) in the cardiorespiratory responses elicited by chemoreceptor activation in conscious rats. Bilateral injection of muscimol (200 pmol/100 nl) into the KF decreased resting ventilation (978 ± 100, vs. saline: 1436 ± 155 ml/kg/min). Muscimol injection into the KF reduced the increase in ventilation (1827 ± 61, vs. saline: 3179 ± 325 ml/kg/min) produced by hypoxia (8% O2 - 10 min) or hypercapnia (7% CO2 - 10 min) (1488 ± 277, vs. saline: 3539 ± 374 ml/kg/min). The injection of muscimol into the LPBN increased resting MAP (D =119 ± 2, vs. saline: 104 ± 2 mmHg). Muscimol into the LPBN did not change the increase in ventilation elicited by hypoxia or hypercapnia in unrestrained rats. The results of the present study suggest that KF region, but not LPBN, have mechanisms to control the ventilation in resting, hypoxic or hypercapnic conditions in conscious rats.
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Zena, Lucas Aparecido. "Efeito da temperatura sobre as interações cardiorrespiratórias em sapos Rhinella schneideri." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8493.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
For adequate blood supply to match metabolic demand, vertebrates regulate blood pressure (BP) in order to maintain adequate perfusion of target organs avoiding ischemia and tissue damage like edema. Effective short-term BP regulation in anuran amphibians occurs through adjustments in heart rate (HR), peripheral vascular resistance, and changing pulsatile frequency of lymph hearts. In addition, pulmonary ventilation in anurans is directly linked to blood volume homeostasis by facilitating lymph fluid movement back into the cardiovascular system which takes place by changing pressure and volume within anurans' lymphatic sacs. It is apparent that an interaction between baroreflex regulation and breathing control exists in anuran amphibians. In the present study I used pharmacological methods (phenylephrine and sodium nitroprusside; infusion ramp and in bolus methods) to investigate baroreflex sensitivity at different temperatures in the cururu toad Rhinella schneideri. I evaluated the degree to which arterial baroreflex plays a role in pulmonary ventilation in the cururu toad. Baroreflex regulation in the toad R. schneideri was temperature dependent and influenced the toad’s ventilation. Hypotension and hypertension resulted in increases and decreases in HR, respectively, as well as increases and decreases in pulmonary ventilation mainly through adjustments in breathing frequency. In contrast to data from the literature, anuran amphibians seem to defend lower BP events primarily rather than hypertension independent of temperature. Anurans exhibit higher rates of transcapillary fluid filtration which means during hypertension fluid filtration is increased and excess interstitial fluid formation will be reclaimed by an efficient lymphatic system. Therefore, besides pulmonary ventilation's role in matching O2 delivery to demand (e.g. temperatures) in anurans, it also plays a role in BP regulation possibly owing to an interaction between baroreflex control and respiratory areas in the brain.
Para um adequado suprimento sanguíneo de modo a atender as diferentes demandas metabólicas, os vertebrados regulam a pressão arterial (PA) mantendo adequada perfusão dos órgãos evitando assim eventos isquêmicos ou outros danos teciduais, como edema. O controle efetivo da PA a curto prazo em anfíbios anuros se dá por ajustes da frequência cardíaca (FC), resistência vascular periférica e também por ajustes da frequência de pulsação dos corações linfáticos. Além disso, a ventilação pulmonar nos anuros está diretamente associada à homeostase do volume sanguíneo por meio da facilitação do transporte de fluído linfático de volta ao sistema cardiovascular, que se dá por meio da alteração de pressão e volume dos sacos linfáticos. Isso parece sugerir a existência de uma possível interação entre a regulação barorreflexa e o controle da respiração nos anfíbios anuros, como já observado para os mamíferos. No presente estudo utilizamos de um método farmacológico (fenilefrina e nitroprussiato de sódio: infusão em rampa e injeção in bolus) para investigar a sensibilidade barorreflexa em diferentes temperaturas no sapo cururu Rhinella schneideri. Também avaliamos o papel do barorreflexo arterial na modulação da ventilação pulmonar nesta mesma espécie. A regulação barorreflexa no sapo R. schneideri apresentou dependência térmica, além de afetar consideravelmente a ventilação dos sapos. A hipotensão e hipertensão resultaram em aumentos e reduções da FC, respectivamente, bem como na ventilação pulmonar, que se deu prioritariamente por meio de ajustes na frequência respiratória. Ao contrário dos dados da literatura, os anfíbios anuros parecem defender prioritariamente eventos de hipotensão ao invés da hipertensão, independente da temperatura testada. É importante salientar que os anuros apresentam alta taxa de filtração transcapilar, e que durante eventos de PA elevada, um aumento na formação de fluido transcapilar pulmonar seria recrutado por um eficiente sistema linfático, característico dos anuros. Portanto, apesar da função da ventilação pulmonar em corresponder à disponibilidade de O2 em diferentes demandas metabólicas (e.g. temperatura), também parece apresentar participação na regulação da PA, possivelmente devido a uma interação entre o barorreflexo e as áreas respiratórias no sistema nervoso central.
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O'Donnell, Jean. "Mechanism of excitation of carotid body chemoreceptor cells." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236119.
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Landauer, Rachel Clare. "Maturation of carotid body chemoreceptor sensitivity to natural stimuli." Thesis, University of Birmingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251135.
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Irazoki, Oihane. "Elucidation of the RecA-mediated mechanisms governing swarming motility in Salmonella enterica." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/405518.
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RecA es una proteína multifuncional que, aparte de ser la recombinasa principal implicada en los pasos cenrrales de la recombinación homóloga y en los mecanismos de reparación de DNA,también es el activador de la respuesta SOS.RecA actúa como sensor de lesiones en el DNA.Al unirse a DNA monocarenario, la proteína se activa (RecA*)y promueve la auto-hidrólisis del represor lexA,induciendo asíla expresión de los genes de la respuesta SOS.Además,se ha descrito que la proteína RccA está también vinculada con la motilidad en enjambre.
El movimiento en enjambre o swarming, que está. ampliamente distribuido en el dominio Bacteria, se defin.e como una translocación multicelular rápida y organiz.ada de lasbacterias sobresuperficies sólidas o semi.sólidasmediada por la rotación Aagclar. Varios estudios asocian la proteína RecA con CheW, un componente davc en el ensamblaje de los quirniorrecepcores y de las matrices de señalización formadas por éstos, queson.esenciales para el swarming.
los resultadospresentados en la presente Tesis Doctoral demuestran inequívocamente la interacción entre RecA y CheW. En el desarrollo de éste trabajo se ha caracterizado el complejo RecA-CheW, permitiendo la identificación de las interfaces
crúicas implicadas en la interacción entre ambas proteín.as y su papel en la forrn.ación de las matrices de señalización . Además, se han podido identificar como esenciales para la interacción los residuos Gln20,Arg222,Argl 76 y Lys250 de RecA,que se encuentran en.losdomin.ios esttucmrales N-terminal ycentral de dicha proteína,y los residuos Phe21,Lys55,
Asp83 y Phe121 de CbeW,que por dónde se ubican no parecen interferir con ninguna otra región de unión descrita para ChcW.
Además, los experimentos realizados demuestran que la pérdida de swarming es consecuencia de la disrupción de las matricesde seúalización generada por el aumemo en la concentración innacelular de la proteína RecA.Los ensayos llevados a cabo mediante microscopía de alta resolución, han permitido rasnear la distribución i nnacelular de las proteínas CheW
y RecA durante la inducción de la respuesta SOS,y elucidar el papel de la proteína RecA en.la distribución de CheW y en
el ensamblajedelasmatrices de sef1alización.
Final meme, los resultados obre.nidos permiten proponer un modelo que explica cómo las células bacterianas adaptan su motilidad sobre superficies en respuesta a la presencia de agentes nocivos para el DNA mediante la detección de ésrns a través. de la induccióndel sis.tema SOS. Durantela coloniz.ación desuperficies,lascélulas bacterianas pueden estar expuestas
a una amplia gama de compuestos dañinosy poten.dalm.ente letales. Sin embargo, las células pueden eludirlos gracias a la
inducción de la respuesta SOS y la consiguiente inhibición del swarmíng. Así, cuando concentraciones sub-letales de compuestos tóxicosgeneran lesionesen el DNA,la proteína RecA se activa induciendo la respuesta SOS, y,dado que recA es uno de Los primeros genesen lajerarquía de la activación SOS,su concen.tración aumenta rápidamence.Éste incremento de la concentración intracelular RecA perturba el equilibrio entre esta proteína y CheW,concretamente,RecA secuestra a la proteína CheW, evitando el correcto ensamblaje de las matrices de seña!i:?ación polar, causando el cese del movimiento swarmingcuando seinduce la respuesta SOS.Mediante este mecanismo ,las bacterias evitan la exposición a concentraciones mayores del agente nocivo,y por lo tanto, la muerte celular. Una vez se reparan las lesiones en el DNA dañado, la concentración de RecA decrece hasta su nivel basal, evitando el secue5tro de la proteína CheW, re5taurándose así el ensamblaje de las matrices quimiosensoriales y también el movimiento en enjanbre.Así pues, los daros presentados han permitido la caracterización del mecanismo molecular que gobierna la modulación de swttrming mediada por RecA, mediante d cualSafmoneüapuede adaptar su motilidad en superficie en respuesta a condiciones ambientales adversas.We characterized the RecA-CheW protein complex, that allowed the identification of the critical interfaces implied in the interaction and its role in the signaling array assembly. RecA residues Gln20, Arg222, Arg176 and Lys250 that are located in the multi-functional N-terminal and central structural domains of the protein, were described as essential for the interaction. In the case of CheW protein, residues Phe21, Lys55, Asp83 and Phe121 were involved in the RecA-binding, that do not seem to interfere with any other CheW-biding targets. Further, the obtained results demonstrate that the loss of swarming ability when there is an increase of RecA concentration was the consequence of chemosensing array assembly disruption, that previous works have established as essential for swarming in temperate swarmers. Using high resolution microscopy assays we were able to track CheW and RecA protein distribution within the cell during SOS response induction, elucidating the role of the RecA protein in the distribution of CheW and the assembly of chemoreceptor signaling arrays. The obtained results head to the proposal of a model that explains how bacterial cells adapt their surface motility in response to the presence of DNA-damaging agents by sensing them via SOS system induction. During surface colonization, bacterial cells will likely be exposed to a wide range of injurious, and potentially lethal, compounds that are avoided through SOS response induction and consequent swarming ability impairment. When DNA injuries are generated, RecA activates the SOS machinery, and its concentration rises swi��ly since recA is one of the first genes to be induced in the hierarchy of SOS activation. The increase of intracellular RecA concentration during SOS-response disturbs the equilibrium between this protein and CheW, causing the cessation of swarming. RecA prompts the titration of CheW protein, preventing polar signaling array assembly during SOS response, and thereby inhibiting motility. By this mechanism, bacteria avoid exposure to higher concentrations of the DNA damaging agent, and so, cell death. Following DNA damage repair, RecA concentration returns to its basal level, releasing CheW, that restores chemosensory array assembly, returning the cell to a non-DNA damage motile condition. Therefore, the present work characterizes the molecular mechanisms that govern RecAmediated swarming modulation, by which using RecA as a sensor, Salmonella cells can adapt their surface motility in response to adverse environmental conditions.
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Furuya, Werner Issao. "Função colinérgica do núcleo do trato solitário comissural nas respostas cardiorrespiratórias à hipóxia e hipercapnia." Universidade Federal de São Carlos, 2017. https://repositorio.ufscar.br/handle/ufscar/9171.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
The nucleus of the solitary tract (NTS) is the primary site of visceral afferents, such as baroreceptors and arterial chemoreceptors. Recent data from our laboratory have shown that the microinjection of acetylcholine (ACh) into the commissural moiety of the NTS (cNTS) of decorticated arterially-perfused in situ preparations of male juvenile rats did not change the sympathetic nerve activity (SNA), but increased the phrenic nerve activity (PNA). Furthermore, we demonstrated that the ACh-induced responses in cNTS involve the activation of both nicotinic and muscarinic receptors. However, nicotinic receptors seem to play a more relevant role in the control of breathing, especially considering that such receptor antagonism promotes a decrease in the KCN- activated peripheral chemoreflex tachypneic response. However, the effects of specific nicotinic and muscarinic agonists in the cNTS on respiratory and sympathetic responses have not been studied yet. Once established the involvement of nicotinic receptors in the cNTS on peripheral chemoreflex ventilatory responses activated by cytotoxic hypoxia (KCN), we also evaluated the involvement of the cholinergic system in the cNTS on respiratory and sympathetic responses induced by hypercapnia or 24 h sustained hypoxia. Therefore, this project proposed to study the effects of selective activation of distinct cholinergic receptors in the cNTS on respiratory and sympathetic activities and the role of the cholinergic system in cNTS on sympathetic and respiratory activities reflex changes in response to hypercapnia or sustained hypoxia. We observed that the injection of both nicotinic and muscarinic agonists in the cNTS induces an increase in SNA and changes in the respiratory modulation pattern. The nicotinic agonist induces a decrease in respiratory frequency, as well as the blockade of the enzyme acetylcholinesterase. It was also observed that the cholinergic agonists promote an increase in the amplitude and duration of the pre-inspiratory (pre-I) period of the hypoglossal nerve and also increased the amplitude of the vagus nerve. When it comes on the protocols involving hypoxia, we observed that the cholinergic antagonists injected into the cNTS of rats previously exposed to hypoxia promoted a decrease in sympathetic activity, increased respiratory frequency, decreased hypoglossal nerve amplitude, and decreased post-inspiratory peak amplitude of the vagus nerve, but only the muscarinic antagonist decreased phrenic nerve amplitude and hypoxia-induced hypoglossal nerve pre-I increase. Regarding to the experiments with hypercapnia, we verified that the nicotinic antagonist in the cNTS inhibited the hypercapnia-induced increase in pre-I of the hypoglossal nerve. In addition, the nicotinic antagonist injected into the cNTS also potentiated the recruitment of late-E activity from the abdominal nerve. Taken together, the responses observed with the cholinergic agonists and injected into the cNTS, as well as the antagonists upon hypoxia, suggest the involvement of cholinergic pathways in the cNTS in the modulation of sympathetic and respiratory responses to sustained hypoxia. On the other hand, it seems that only nicotinic receptors in the cNTS are involved in hypercapnia-induced increase in pre-inspiratory activity and active expiration.
O núcleo do trato solitário (NTS) é o sítio primário de aferências viscerais, como barorreceptores e quimiorreceptores arteriais. Estudos recentes do nosso laboratório demonstraram que, em preparações in situ, decorticadas e perfundidas intra-arterialmente, a microinjeção de acetilcolina (ACh) na porção comissural do NTS (NTSc) não alterou a atividade simpática (SNA), mas promoveu aumento da atividade do nervo frênico (PNA). Além disso, evidenciamos que as respostas induzidas pela ACh no NTSc envolvem a ativação dos receptores nicotínicos e muscarínicos. Contudo, os receptores nicotínicos parecem desempenhar um papel mais relevante no controle da respiração, principalmente considerando que o antagonismo de tais receptores promove uma redução da resposta taquipneica do quimiorreflexo periférico ativado pelo KCN. Entretanto, os efeitos de agonistas específicos nicotínicos e muscarínicos, bem como a inibição da inibição da degradação de ACh no NTSc sobre as respostas respiratórias e sobre a atividade simpática ainda não foram estudados. Sabendo-se da participação dos receptores nicotínicos do NTSc sobre as respostas ventilatórias dos quimiorreceptores periféricos ativados por hipóxia citotóxica (KCN), avaliamos também a participação do sistema colinérgico do NTSc sobre as respostas simpática e respiratória induzidas por hipercapnia ou hipóxia sustentada por 24 h. Portanto, este projeto se propôs a estudar o efeito da ativação seletiva de diferentes receptores colinérgicos no NTSc sobre as atividades simpática e respiratória e o papel do sistema colinérgico no NTSc sobre as alterações reflexas nas atividades simpática e respiratória em resposta à hipercapnia ou hipóxia sustentada por 24 h. Observamos que a injeção de agonistas tanto nicotínico quanto muscarínico no NTSc promovem aumento da SNA e modifica o seu padrão de modulação respiratória. O agonista nicotínico induz uma diminuição da frequência respiratória, assim como o bloqueio da enzima acetilcolinesterase. Também foi observado que os agonistas colinérgicos promovem um aumento na amplitude e duração do período préinspiratório (pre-I) do nervo hipoglosso e também aumento na amplitude do nervo vago. Com relação aos protocolos envolvendo hipóxia, observamos os antagonistas colinérgicos injetados no NTSc de ratos previamente expostos à hipóxia, promoveu diminuição da atividade simpática, aumento da frequência respiratória, diminuição da amplitude do nervo hipoglosso e diminuição da amplitude do pico pós-inspiratório do nervo vago, mas somente o antagonista muscarínico diminuiu a amplitude do nervo frênico e o aumento do pre-I do nervo hipoglosso induzido pela hipóxia. Com relação aos experimentos com hipercapnia, verificamos que o antagonista nicotínico no NTSc inibiu o aumento do pre-I do nervo hipoglosso induzido pela hipercapnia. Além disso, o antagonista nicotínico injetado no NTSc também potencializou o recrutamento de atividade late-E do nervo abdominal. Tomados em conjunto, as respostas observadas com os agonistas colinérgicos injetados no NTSc, bem como com os antagonistas mediante a hipóxia, sugerem a participação de vias colinérgica do NTSc na modulação das respostas simpática e respiratória à hipóxia sustentada. Por outro lado, apenas os receptores nicotínicos do NTSc parecem estar envolvidos com o aumento da atividade pré-inspiratória e da expiração ativa induzidos por hipercapnia.
FAPESP: 2013/22526-4
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MELIS, MELANIA. "Sensitivity to chemical stimuli plays a fundamental role in the food preferences. Examples in the evolutionary scale: 1. Role of the walking leg chemoreceptors in the red swamp crayfish Procambarus Clarkii 2. PROP bitter taste sensitivity and its nutritional implications in Humans." Doctoral thesis, Università degli Studi di Cagliari, 2014. http://hdl.handle.net/11584/266417.
Full textAbstract:
In this thesis, we studied two examples of the sensitivity to chemical stimuli and its role in the food preferences in two models of the evolutionary scale.
The red swamp crayfish Procambarus clarkii (Girard, 1852) (Crustacea: Decapoda) is an invasive species of freshwater habitats that has spread worldwide. In crayfish, like in other decapod crustaceans, reception of chemical cues occurs by way of peripheral chemoreceptors grouped within sensory hairs and typically located on the cuticle of cephalothoracic appendages. Antennules and pereopods (walking legs), in particular, have been reported to be olfactory organs involved in a number of behavioral responses, such as, sex recognition and localization of food sources in the environment. By way of extracellular nerve recordings coupled with behavioral bioassays, we investigated the sensitivity spectra of the walking leg chemoreceptors in the crayfish P. clarkii in response to different compounds of feeding significance and related to its omnivorous habits. Our results confirmed a marked sensitivity of the legs to trehalose, cellobiose, sucrose, maltose, glycine and leucine. Some sensitivity to glucose, fructose, asparagine (all food indicators) and taurocholic acid was also found, the sugar-sensitive chemoreceptor units resulting as broadly tuned to the carbohydrates. Responses were highly phasic to trehalose (hemolymph sugar in the body fluid of many invertebrates), phasic to glycine and leucine and phasic-tonic to the other compounds. This suggests that chemoreceptor phasicity is an additional property for better discrimination of the protein components in the diet from other stimuli. The behavioral bioassays excluded, at least under confined experimental conditions, any involvement of antennules in the detection of food-related compounds, thus emphasizing the role of the crayfish legs as the main short-distance, broad-spectrum sensors for feeding. Such information may be valuable for the identification of key chemicals aimed at the future development of strategies for crayfish population control programs.
Taste sensitivity varies greatly in humans, influencing eating behavior and therefore may play a role in body composition. PROP bitter taste sensitivity is the most studied example of the individual variability of taste sensitivity. Some studies show that PROP bitter taste sensitivity may be correlated with sensitivity to other oral stimuli, food preferences and BMI, while other studies did not confirm this association. It is known that PROP phenotype is associated with variant in bitter taste receptors TAS2R38 and with density of fungiform papillae on tongue surface. Although most of PROP phenotypic variations are explained by the allelic diversity of the bitter receptor TAS2R38, they cannot explain the PROP taster status-related differences above all that in the perception to different oral stimuli. The aim of this study was identify and characterize other factors that may contribute to differences in the genetic predisposition to taste PROP and identify confounding variables which may explain the controversial data in the literature about the relationship between PROP taste sensitivity and BMI. 1) We investigated the possible relationship between PROP bitter taste responsiveness and salivary proteins by using HPLC-ESI-MS on saliva sample before and after PROP taste stimulation. 2) We evaluated the role of proteins and free amino acids in modulating bitter taste responsiveness. Subjects rated PROP bitterness after supplementation of two salivary proteins (Ps-1 and II-2), and the free form of constituent amino acids of the two proteins sequences (L-Arg and L-Lys) whose interaction with PROP was demonstrated by 1H-NMR spectroscopy. 3) We investigate the role of polymorphism rs2274333 (A/G) in the gene that codify for the salivary trofic factor gustin protein, in PROP sensitivity and fungiform papilla density and morphology and in vitro we investigate the effect of this gustin gene polymorphism on cell proliferation and metabolic activity, following treatment with saliva of individuals with and without the gustin gene mutation, and with isolated protein, in the two iso-forms. 4) We investigated whether the endocannabinoid system, which modulates hunger/satiety and energy balance, plays a role in modulating eating behaviour influenced by a sensitivity to PROP which could explain the controversial data in literature. In particular we determined the plasma profile of the endocannabinoids 2-arachidonoylglycerol (2-AG), anandamide (AEA) and congeners in normal-weight PROP super-tasters and non-tasters, also we assessed the cognitive eating behavior disorder by the Three-Factor Eating Questionnaire.
The results showed that: 1) Basal levels of II-2 and Ps-1 proteins, belonging to the basic proline-rich protein (bPRPs) family, were significantly higher in PROP super-taster than in non-taster unstimulated saliva, and PROP stimulation elicited a rapid increase in the levels of these same proteins only in PROP super-taster saliva. 2) Supplementation of Ps-1 protein in individuals lacking it in saliva enhanced their PROP bitter responsiveness. 1H-NMR results showed that the interaction between PROP and L-Arg is stonger than that involving L-Lys, and taste experiments confirmed that oral supplementation with L-Arg increase more PROP bitterness intensity than L-Lys. 3) Gustin and TAS2R38 genotypes were associated with PROP threshold, while bitterness intensity was mostly determined by TAS2R38 genotypes. Fungiform papillae densities were associated with both genotypes (with a stronger effect for gustin), but papilla morphology was a function of gustin alone. In vitro experiment, the treatment of isolated cells with saliva from individuals with AA form, and direct application of the active iso-form of gustin protein, increased cell proliferation and metabolic activity. 4) The disinhibition score of non-taster was higher than those of super-tasters. In addition, we found that the concentration
of endocannabinoid AEA (anandamide) and 2-AG (2-arachidonoylglycerol) was lower in the plasma of non taster compared with super-tasters subjects.
In conclusion, among the factors contributing to individual differences of PROP sensitivity, in addition to the TAS2R38 variants with its different affinity for the stimulus, we found: 1-2) the specific salivary proteins of bPRP family (Ps-1) and L-Arg that could be involved in twist and turn of the PROP molecule, thus facilitating its binding with the receptor. 3) A gustin gene polymorphism that, by modulating the protein activity, controls the growth and maintenance of taste buds and 4) the higher disinhibition behaviour in non-tasters may be compensated in part, in normal-weight subjects, by the decrease of peripheral endocannabinoids to downregulate the hunger-energy intake circuitry.
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Khemiri, Hanan. "Caractérisation des effets périphériques et centraux de l'érythropoïétine sur la sensibilité chimique à l'O2 et au CO2." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM5034.
Full textAbstract:
L'érythropoïétine (EPO) est une cytokine ayant un rôle important dans l'homéostasie de l'oxygène (O2). Lors d'une hypoxie chronique, l'EPO stimule la maturation des progéniteurs érythroïdes en globules rouges augmentant ainsi le transport de l'O2 aux tissus. Outre cet effet érythropoïétique, l'EPO module la réponse ventilatoire à l'hypoxie (RVH) par une action directe sur la commande centrale respiratoire (CCR) et les chémorécepteurs périphériques. Cet effet a été principalement caractérisé chez des souris mutantes surexprimant l'EPO. Cependant, plusieurs aspects de l'effet de l'EPO sur l'activité du réseau respiratoire demeurent inconnus. Nos résultats montrent qu'une application aigüe d'EPO diminue la dépression centrale hypoxique mesurée in vitro chez le nouveau-né. En revanche, elle n'affecte pas la RVH mesurée in vivo au cours du développement postnatal mais diminue la fréquence des apnées survenant en hypoxie sévère à 6% d'O2. Aussi, chez la souris adulte, l'administration chronique d'EPO et de C-EPO augmente la sensibilité des chémorécepteurs périphériques à l'O2 et maintient la ventilation durant la phase tardive de la RVH. Enfin, l'EPO diminue la sensibilité ventilatoire à l'hypercapnie grâce à des effets périphériques et centraux. L'ensemble de nos résultats montrent que l'EPO module la respiration et contribue à l'homéostasie de l'O2 et du CO2 grâce à ses effets plasmatiques et centraux. Elle représente un candidat à fort potentiel thérapeutique pour les pathologies respiratoires où la sensibilité chimique à l'O2 et au CO2 sont altérés telles que l'apnée du nouveau-né ou le mal chronique des montagnesErythropoietin (EPO) is a cytokine that plays a major role in O2 homeostasis. Upon chronic hypoxia, EPO stimulates the maturation of erythroid progenitors into red blood cells, contributing to increased O2 carrying to tissues. Besides this well-known erythropoietic effect, EPO also modulates the respiratory response to hypoxia by interacting with the central respiratory network in the brainstem and the peripheral chemoreceptors. This effect was mainly characterized in adult mutant mice that overexpress EPO. Several aspects regarding EPO's effect on breathing regulation remain unknown. Our results show that acute EPO treatment increases the O2 sensitivity of the central respiratory network in newborn mice in vitro. However, EPO does not impact the hypoxic ventilatory response to hypoxia in vivo, but decreases the apneic events during severe hypoxia in mice at postnatal day 7. In WT adults, chronic but not acute EPO and C-EPO treatment increases the O2 sensitivity by stimulating both peripheral chemoreceptor and central respiratory network. Finally, both cerebral and plasmatic EPO blunt the ventilatory response to increased CO2 levels in adult mice. Taken together, these results imply that EPO, by acting on the ventilatory system, plays a key role in the modulation of the chemical sensitivity to O2 and CO2
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McCooke, H. B. "Carotid chemoreceptor sensitivity in the fetus and in the neonate." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376794.
Full text
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Gulbransen, Brian D. "Nasal solitary chemoreceptor cells : cell turnover, nerve dependence, and detection capabilities /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2007.
Find full textAbstract:
Thesis (Ph.D. in Neuroscience) -- University of Colorado Denver, 2007.Typescript. Includes bibliographical references (leaves 129-151). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;
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Gaudel, Fanny. "Caractérisation des chimiorécepteurs dans le cerveau." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0732.
Full textAbstract:
Molécules du goût et odeurs se fixent sur des récepteurs dits gustatifs et olfactifs, présents dans la bouche et le nez. Ils sont donc en contact avec le monde environnant. Toutefois, on les trouve également dans des organes isolés de l’extérieur, comme le pancréas ou le cerveau, où ils ne sont plus impliqués dans la détection du non-soi. Ils y régulent la glycémie ou l’activation du système immunitaire. Dans le cerveau, leurs rôles demeurent mystérieux. Mon travail a consisté à déterminer: 1) si, et où les récepteurs gustatifs et olfactifs sont présents dans le cerveau humain, 2) quand, où et pourquoi les récepteurs olfactifs sont présents dans le cerveau de souris et 3) si une maladie comme Alzheimer peut modifier leur expression. Mes résultats montrent qu’ils sont présents dans l’ensemble du cerveau humain et particulièrement dans le «cerveau émotionnel». De plus, le cerveau de souris «Alzheimer» surexprime des récepteurs olfactifs, notamment dans les neurones. Le cerveau est donc capable de goûter et sentir son monde intérieur. On peut imaginer que ces récepteurs jouent un rôle dans la détection de la maladie et, qui sait, qu’ils participent à la lutte contre ses effets néfastesTaste molecules and odours bind to so-called gustatory and olfactory receptors present in the mouth and nose. They are therefore in contact with the surrounding world. However, they are also found in organs isolated from the outside, such as the pancreas or brain, where they are no longer involved in the detection of non-self. They regulate blood sugar levels or the activation of the immune system. In the brain, their roles remain mysterious. My work consisted in determining: 1) if, and where, taste and smell receptors are present in the human brain, 2) when, where and why smell receptors are present in the mouse brain, and 3) whether a disease like Alzheimer's can change their expression. My results show that they are present in the entire human brain and particularly in the "emotional brain". In addition, the brains of "Alzheimer" mice overexpress olfactory receptors, particularly in neurons. The brain is therefore able to taste and feel its inner world. It is conceivable that these receptors play a role in detecting the disease and, who knows, in combating its harmful effects