Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 188
Filtrar
Mais filtros

Bases de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Public Health ; 159: 17-20, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29679861

RESUMO

OBJECTIVES: The outcomes of hygiene audits carried out two times per year were used to determine the correct execution of the procedures foreseen by the Hazard Analysis and Critical Control Points (HACCP) plan over 4 years (2013-2016) in a university canteen producing about 1200 meals a day. STUDY DESIGN: Critical analysis of hygiene audits. METHODS: Hygiene audits were carried out on the basis of a checklist divided into seven main items and subitems that covered all the production areas of the canteen. For each audit subitem, total percentage of inadequacy was calculated as the total number of negative answers (N) divided by the total number of answers (n = 8) collected in the period 2013-2016. RESULTS: The results showed a discontinuous trend among years. In more detail, the highest percentage of inadequacy was seen for food maintaining temperatures, thus highlighting management issues mainly related to time taken for food preparation. A relatively high level of inadequacy was also recorded for staff clothing and hygiene. CONCLUSIONS: The critical analysis of data emerged from the audits was useful to obtain an overview of improvements and emerging criticalities.


Assuntos
Manipulação de Alimentos/normas , Serviços de Alimentação/normas , Higiene/normas , Universidades , Serviços de Alimentação/organização & administração , Análise de Perigos e Pontos Críticos de Controle , Humanos , Itália
2.
Epidemiol Infect ; 144(14): 3000-3012, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27426630

RESUMO

Salmonella spp. is the causative agent of a foodborne disease called salmonellosis, which is the second most commonly reported gastrointestinal infection in the European Union (EU). Although over the years the annual number of cases of foodborne salmonellosis within the EU has decreased markedly, in 2014, a total of 88 715 confirmed cases were still reported by 28 EU Member States. The European Food Safety Authority reported that, after the household environment, the most frequent settings for the transmission of infection were catering services. As evidenced by the reviewed literature, which was published over the last 15 years (2000-2014), the most frequently reported causative agents were Salmonella Enteritidis and Salmonella Typhimurium serovars. These studies on outbreaks indicated the involvement of various facilities, including hospital restaurants, takeaways, ethnic restaurants, hotels, in-flight catering, one fast-food outlet and the restaurant of an amusement park. The most commonly reported sources of infection were eggs and/or egg-containing foods, followed by meat- and vegetable-based preparations. Epidemiological and microbiological studies allowed common risk factors to be identified, including the occurrence of cross-contamination between heat-treated foods and raw materials or improperly cleaned food-contact surfaces.


Assuntos
Surtos de Doenças , União Europeia/estatística & dados numéricos , Microbiologia de Alimentos , Serviços de Alimentação , Intoxicação Alimentar por Salmonella/epidemiologia , Europa (Continente)/epidemiologia , Fatores de Risco , Intoxicação Alimentar por Salmonella/microbiologia
3.
Environ Monit Assess ; 185(6): 4765-74, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23054270

RESUMO

Over the past decade, an increased tendency to consume meals at dining facilities outside the home has been highlighted; moreover, meals supplied in food businesses have been involved in many foodborne disease outbreaks. Therefore, microbial air contamination in food processing facilities could be a concern and an increase of microbial loads could represent a risk factor, especially for the potential contamination of foods due to undesirable spoiling and pathogenic bacteria. In this paper, the results of an 11-year microbiological monitoring of air quality in a university canteen are reported. The study, which started in the year 2000, was performed within a hazard analysis and critical control point (HACCP) plan implementation of a canteen that produces about 1,000 meals a day in order to verify the effectiveness of corrective actions on the indoor air quality. The primary food preparation room, the kitchen, and three cold rooms underwent air sampling by using a calibrated impaction sampler. Our investigation detected a general and progressive improvement in the air quality of the canteen since the beginning of the study, thus suggesting the appropriateness of the corrective action undertaken during the HACCP implementation program.


Assuntos
Microbiologia do Ar , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Microbiologia de Alimentos , Humanos , Medição de Risco , Universidades
4.
Lett Appl Microbiol ; 52(6): 651-9, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21466567

RESUMO

AIMS: To investigate the bacterial dynamics of a Caciotta cheese traditionally manufactured in the Montefeltro area (Central Italy) with raw cow's milk and an aqueous extract of dried flowers from Cynara cardunculus as a coagulating agent. METHODS AND RESULTS: Conventional methods and a combined PCR-DGGE approach, relying on culture-dependent and -independent analyses, were used to investigate the cheese bacterial community, with a special focus on lactic acid bacteria. A heterogeneous population, including enterococci, lactococci, lactobacilli, food spoilage and other banal micro-organisms, was found. SIGNIFICANCE AND IMPACT OF THE STUDY: The study contributed to highlighting the influence of different technological parameters on bacterial dynamics of a raw milk Caciotta cheese coagulated with vegetable rennet. CONCLUSIONS: None of the species found in the vegetable rennet became dominant during the cheese-making and a prevailing role of the adventitions microbita coming from the raw milk and the dairy environment was highlighted.


Assuntos
Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Queijo/microbiologia , Cynara , Flores , Animais , Bactérias/classificação , Bactérias/genética , Bovinos , Eletroforese em Gel de Gradiente Desnaturante/métodos , Itália , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/isolamento & purificação , Lactococcus/crescimento & desenvolvimento , Lactococcus/isolamento & purificação , Leite/microbiologia , Reação em Cadeia da Polimerase/métodos
5.
J Cell Biol ; 41(1): 33-58, 1969 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-5775791

RESUMO

Horseradish peroxidase (mol. diam. approximately 50 A) and ferritin (mol. diam. approximately 110 A) were used as probe molecules for the small and large pore system, respectively, in blood capillaries of the intestinal mucosa of the mouse. Peroxidase distribution was followed in time, after intravenous injection, by applying the Graham-Karnovsky histochemical procedure to aldehyde-fixed specimens. The tracer was found to leave the plasma rapidly and to reach the pericapillary spaces 1 min post injection. Between 1 min and 1 min 30 sec, gradients of peroxidase reaction product could be demonstrated regularly around the capillaries; their highs were located opposite the fenestrated parts of the endothelium. These gradients were replaced by even distribution past 1 min 30 sec. Ferritin, followed directly by electron microscopy, appeared in the pericapillary spaces 3-4 min after i.v. injection. Like peroxidase, it initially produced transient gradients with highs opposite the fenestrated parts of the endothelium. For both tracers, there was no evidence of movement through intercellular junctions, and transport by plasmalemmal vesicles appeared less efficient than outflow through fenestrae. It is concluded that, in the blood capillaries of the inintestinal mucosa, the diaphragms of the endothelial fenestrae contain the structural equivalents of the small pore system. The large pore system seems to be restricted to a fraction of the fenestral population which presumably consists of diaphragm-free or diaphragm-deficient units.


Assuntos
Capilares/citologia , Permeabilidade Capilar , Ferritinas , Mucosa Intestinal/irrigação sanguínea , Peroxidases , Animais , Sangue , Tempo de Circulação Sanguínea , Linfa , Camundongos , Microscopia Eletrônica
6.
J Cell Biol ; 42(3): 706-14, 1969 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-4979362

RESUMO

Perfusion of the fenestrated capillaries of the intestinal mucosa of the rat with 0.05-0.1 M EDTA removes the diaphragms of the endothelial cells and detaches these cells from one another and from the basement membrane. The latter, even when completely denuded, retains effectively particles of 340 A (average) diameter. Perfusion with histamine (1 microg/ml) results in partial removal of fenestral diaphragms, occasional detachment of the endothelium from the basement membrane, and focal separation of endothelial intercellular junctions.


Assuntos
Capilares/efeitos dos fármacos , Ácido Edético/farmacologia , Histamina/farmacologia , Mucosa Intestinal/irrigação sanguínea , Animais , Membrana Basal/fisiologia , Cálcio/metabolismo , Permeabilidade Capilar/efeitos dos fármacos , Epitélio/fisiologia , Masculino , Ratos
7.
J Cell Biol ; 108(6): 2291-300, 1989 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-2544606

RESUMO

IMR-32 human neuroblastoma cells are unable to release [3H]dopamine in response to secretagogues. However, they express a normal complement of membrane receptors and ion channels which are efficiently coupled to second messenger production. In the present study we took advantage of the ability of this cell line to differentiate in vitro in the presence of either dibutyrryl-cAMP or 5-bromodeoxyuridine, to analyze any developmentally regulated changes in its secretory properties. Uptake, storage, and release of [3H]dopamine were studied biochemically and by autoradiography. The calcium ionophore ionomycin, phorbol 12-myristate 13-acetate and the presynaptic acting neurotoxin alpha-latrotoxin were used in both control and differentiated cells as secretagogue agents. The presence of secretory organelles was investigated by electron microscopy; the expression of secretory organelle markers, such as chromogranin/secretogranin proteins (secretory proteins) and synaptophysin (membrane protein), was detected by Western blotting and immunofluorescence. The results obtained indicate that IMR-32 cells acquire regulated secretory properties after in vitro drug-induced differentiation: (a) they assemble "de novo" secretory organelles, as revealed by electron microscopy and detection of secretory organelle markers, and (b) they are able to store [3H]dopamine and to release the neurotransmitter in response to secretagogue stimuli. Furthermore, secretagogue sensitivity was found to be different, depending on the differentiating agent. In fact, dibutyrryl-cAMP treated cells release [3H]dopamine in response to alpha-latrotoxin, but not in response to ionomycin, whereas 5-bromodeoxyuridine treated cells release the neurotransmitter in response to both secretagogues. All together these results suggest that IMR-32 cells represent an adequate model for studying the development of the secretory apparatus in cultured human neurons.


Assuntos
Cálcio/fisiologia , Dopamina/metabolismo , Neuroblastoma/metabolismo , Transporte Biológico , Bromodesoxiuridina/farmacologia , Bucladesina/farmacologia , Compartimento Celular , Diferenciação Celular , Sobrevivência Celular , Grânulos Cromafim/ultraestrutura , Éteres/farmacologia , Humanos , Ionomicina , Cinética , Neuroblastoma/ultraestrutura , Proteína Quinase C/fisiologia , Venenos de Aranha/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas
9.
Minerva Cardioangiol ; 57(5): 597-609, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19838150

RESUMO

Despite the impressive progress of percutaneous treatment modalities, restenosis remains the major Achilles heel of interventional cardiology. Approximately 25% of the general population treated for coronary diseases with a bare-metal stent and about 10% of patients treated with a drug-eluting stent develop an overgrowth of vascular tissue and renarrowing inside the stent, or in-stent restenosis. These rates are even greater in diabetics and patients at higher risk of restenosis both for clinical presentation (patients in dialysis, low ejection fraction) or anatomical characteristics (ostial, bifurcation, long lesions). Non-stent based local drug delivery and particularly the use of paclitaxel eluting balloon (PEB) could be one promising strategy to reduce restenosis. This review will briefly explore the different characteristics of PEB devices currently present in the market and summarize the results obtained both in animal models and clinical practice, giving an indication of the potential field of application of this new technology.


Assuntos
Cateterismo/instrumentação , Reestenose Coronária/prevenção & controle , Paclitaxel/administração & dosagem , Próteses e Implantes , Animais , Cateterismo/tendências , Stents Farmacológicos , Previsões , Humanos
10.
Neuron ; 12(2): 317-26, 1994 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8110461

RESUMO

125I-omega-conotoxin binding to neuroblastoma cells at 37 degrees C continuously increased, reaching a plateau after 6-8 hr; this was up to 6 times higher than that observed at lower temperatures. The same effect was induced by short pulses with omega-conotoxin followed by a chase period at 37 degrees C in control medium. Cd2+ also induced up-regulation of surface 125I-omega-conotoxin-binding sites. Fura-2 and patch-clamp experiments showed that the recruited binding sites corresponded to functional voltage-operated Ca2+ channels. Permeabilization experiments revealed a large intracellular pool of 125I-omega-conotoxin-binding sites, whose recruitment to the plasmamembrane was prevented by brefeldin A and nocodazole. These data suggest that specific stimuli might induce voltage-operated Ca2+ channel translocation to plasmamembrane and, in this way, modulate presynaptic events.


Assuntos
Cádmio/farmacologia , Canais de Cálcio/metabolismo , Canais de Cálcio/fisiologia , Membrana Celular/metabolismo , Membranas Intracelulares/metabolismo , Peptídeos/farmacologia , Sítios de Ligação/efeitos dos fármacos , Transporte Biológico , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , Permeabilidade da Membrana Celular , Eletrofisiologia , Humanos , Cinética , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Peptídeos/metabolismo , Células Tumorais Cultivadas , ômega-Conotoxina GVIA
11.
J Appl Microbiol ; 105(1): 243-54, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18312562

RESUMO

AIMS: To study lactic acid bacteria (LAB) and yeast dynamics during the production processes of sweet-leavened goods manufactured with type I sourdoughs. METHODS AND RESULTS: Fourteen sourdough and dough samples were taken from a baking company in central Italy during the production lines of three varieties of Panettone. The samples underwent pH measurements and plating analysis on three solid media. The microbial DNA was extracted from both the (sour)doughs and the viable LAB and yeast cells collected in bulk, and subjected to PCR-denaturing gradient gel electrophoresis (DGGE) analysis. The molecular fingerprinting of the cultivable plus noncultivable microbial populations provide evidence of the dominance of Lactobacillus sanfranciscensis, Lactobacillus brevis and Candida humilis in the three fermentation processes. The DGGE profiles of the cultivable communities reveal a bacterial shift in the final stages of two of the production processes, suggesting an effect of technological parameters on the selection of the dough microflora. CONCLUSIONS: Our findings confirm the importance of using a combined analytical approach to explore microbial communities that develop during the leavening process of sweet-leavened goods. SIGNIFICANCE AND IMPACT OF THE STUDY: In-depth studies of sourdough biodiversity and population dynamics occurring during sourdough fermentation are fundamental for the control of the leavening process and the manufacture of standardized, high-quality products.


Assuntos
Pão/microbiologia , Microbiologia de Alimentos , Lactobacillus/fisiologia , Leveduras/fisiologia , Biodiversidade , Contagem de Colônia Microbiana , Meios de Cultura , DNA Bacteriano/análise , DNA Fúngico/análise , Eletroforese em Gel de Poliacrilamida/métodos , Fermentação , Itália
12.
Curr Pharm Des ; 12(4): 407-28, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16472136

RESUMO

Neuronal nicotinic receptors (nAChRs) are a heterogeneous family of ion channels differently expressed in the nervous system where, by responding to the endogenous neurotransmitter acetylcholine, they contribute to a wide range of brain activities and influence a number of physiological functions. Over recent years, the application of newly developed molecular and cellular biological techniques has made it possible to correlate the subunit composition of nAChRs with specific nicotine-elicited behaviours, and refine some of the in vivo physiological functions of nAChR subtypes. The major new findings are the widespread expression of nAChRs, outside the nervous system, their specific and complex organisation, and their relevance to normal brain function. Moreover, the combination of clinical and basic research has better defined the involvement of nAChRs in a growing number of nervous pathologies other than degenerative diseases. However, there are still only a limited number of nicotinic-specific drugs and, although some nicotinic agonists have an interesting pharmacology, their clinical use is limited by undesirable side effects. Some selective nicotinic ligands have recently been developed and used to explore the complexity of nAChR subtype structure and function in the expectation that they will become rational therapeutic alternatives in a number of neurodegenerative, neuropsychiatric and neurological disorders. In this review, we will discuss the molecular basis of brain nAChR structural and functional diversity mainly in pharmacological and biochemical terms, and summarise current knowledge concerning the newly discovered drugs used to classify the numerous receptor subtypes and treat the brain diseases in which nAChRs are involved.


Assuntos
Desenho de Fármacos , Neurônios/efeitos dos fármacos , Receptores Nicotínicos/fisiologia , Animais , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Colinérgicos/farmacologia , Humanos , Modelos Moleculares , Neurônios/fisiologia , Receptores Nicotínicos/química , Receptores Nicotínicos/classificação , Tecnologia Farmacêutica/métodos , Tecnologia Farmacêutica/tendências
13.
Prog Neurobiol ; 74(6): 363-96, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15649582

RESUMO

Neuronal nicotinic receptors (NAChRs) form a heterogeneous family of ion channels that are differently expressed in many regions of the central nervous system (CNS) and peripheral nervous system. These different receptor subtypes, which have characteristic pharmacological and biophysical properties, have a pentameric structure consisting of the homomeric or heteromeric combination of 12 different subunits (alpha2-alpha10, beta2-beta4). By responding to the endogenous neurotransmitter acetylcholine, NAChRs contribute to a wide range of brain activities and influence a number of physiological functions. Furthermore, it is becoming evident that the perturbation of cholinergic nicotinic neurotransmission can lead to various diseases involving nAChR dysfunction during development, adulthood and ageing. In recent years, it has been discovered that NAChRs are present in a number of non-neuronal cells where they play a significant functional role and are the pathogenetic targets in several diseases. NAChRs are also the target of natural ligands and toxins including nicotine (Nic), the most widespread drug of abuse. This review will attempt to survey the major achievements reached in the study of the structure and function of NAChRs by examining their regional and cellular localisation and the molecular basis of their functional diversity mainly in pharmacological and biochemical terms. The recent availability of mice with the genetic ablation of single or double nicotinic subunits or point mutations have shed light on the role of nAChRs in major physiological functions, and we will here discuss recent data relating to their behavioural phenotypes. Finally, the role of NAChRs in disease will be considered in some details.


Assuntos
Neurônios/patologia , Neurônios/fisiologia , Receptores Nicotínicos , Envelhecimento/fisiologia , Animais , Animais Geneticamente Modificados/fisiologia , Bungarotoxinas/metabolismo , Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo , Modelos Animais de Doenças , Humanos , Modelos Biológicos , Modelos Moleculares , Conformação Proteica , Subunidades Proteicas/fisiologia , Receptores Nicotínicos/química , Receptores Nicotínicos/classificação , Receptores Nicotínicos/fisiologia
14.
Prog Neurobiol ; 53(2): 199-237, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9364611

RESUMO

Nicotine is a very widely used drug of abuse, which exerts a number of neurovegetative, behavioural and psychological effects by interacting with neuronal nicotinic acetylcholine receptors (NAChRs). These receptors are distributed widely in human brain and ganglia, and form a family of ACh-gated ion channels of different subtypes, each of which has a specific pharmacology and physiology. As human NAChRs have been implicated in a number of human central nervous system disorders (including the neurodegenerative Alzheimer's disease, schizophrenia and epilepsy), they are suitable potential targets for rational drug therapy. Much of our current knowledge about the structure and function of NAChRs comes from studies carried out in other species, such as rodents and chicks, and information concerning human nicotinic receptors is still incomplete and scattered in the literature. Nevertheless, it is already evident that there are a number of differences in the anatomical distribution, physiology, pharmacology, and expression regulation of certain subtypes between the nicotinic systems of humans and other species. This review will attempt to survey the major achievements reached in the study of the structure and function of NAChRs by examining the molecular basis of their functional diversity viewed mainly from pharmacological and biochemical perspectives. It will also summarize our current knowledge concerning the structure and function of the NAChRs expressed by other species, and the newly discovered drugs used to classify their numerous subtypes. Finally, the role of NAChRs in behaviour and pathology will be considered.


Assuntos
Neurônios/fisiologia , Receptores Nicotínicos/fisiologia , Humanos , Receptores Nicotínicos/biossíntese , Receptores Nicotínicos/química , Receptores Nicotínicos/efeitos dos fármacos
15.
Cancer Res ; 50(13): 3892-6, 1990 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-2162247

RESUMO

Different subtypes of voltage-operated calcium channels (VOCCs) are expressed in different tissues and can be distinguished by functional and pharmacological criteria. One type of high voltage-activated calcium channel, specifically recognized by the peptide neurotoxin omega-conotoxin (omega CTx), is expressed only in neurons. Seven different human small cell lung carcinoma (SCC) cell lines were also found to bind 125I-omega CTx. The binding was specific, saturable, and of high affinity. 125I-omega CTx binding was not antagonized by the calcium channel ligands verapamil, nitrendipine, and diltiazem. There was a correlation between the amount of toxin binding and the detection of depolarization-induced calcium fluxes studied with the fluorimetric probe Fura2. Fura2 experiments also demonstrated that, in addition to omega CTx-sensitive calcium channels, SCC cell lines also expressed omega CTx-insensitive calcium channels, which were antagonized by nitrendipine and verapamil. 125I-omega CTx-labeled VOCCs from SCC cells were, furthermore, precipitated by anti-VOCC autoantibodies obtained from patients affected by the Lambert-Eaton myasthenic syndrome, a neuromuscular disease often associated with SCC. The present findings further indicate the presence of neuronal molecules with important biological function on SCC plasma membrane and add new insights into the pathogenetic mechanism of autoimmune neurological paraneoplastic diseases, like Lambert-Eaton myasthenic syndrome.


Assuntos
Canais de Cálcio/metabolismo , Carcinoma de Células Pequenas/metabolismo , Conotoxinas , Neoplasias Pulmonares/metabolismo , Peptídeos Cíclicos/metabolismo , Sítios de Ligação , Ligação Competitiva , Canais de Cálcio/análise , Canais de Cálcio/efeitos dos fármacos , Carcinoma de Células Pequenas/análise , Humanos , Neoplasias Pulmonares/análise , Nitrendipino/farmacologia , Células Tumorais Cultivadas , Verapamil/farmacologia
16.
Cancer Res ; 53(22): 5566-8, 1993 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-8221698

RESUMO

Small-cell lung carcinoma cells express different plasma membrane nicotinic acetylcholine receptor subtypes. We have now found that interacting with these receptors (-)-nicotine induces a dose-dependent and stereoselective release of [3H]serotonin which is dependent on external calcium and blocked by the specific ganglionic nicotinic antagonist mecamylamine. With the same potency (-)-nicotine stimulates tumor cell proliferation, an effect also blocked by mecamylamine. Serotonin itself stimulates cell proliferation in a dose-dependent manner, an effect blocked by the selective serotonergic receptor antagonists methiotepine and metergoline. These data suggest that nicotine might affect proliferation of small-cell lung carcinoma cells by inducing the release of hormones (such as serotonin) with autocrine capabilities and place both the nicotinic and the serotonergic receptors at key positions in the biological and, possibly, pharmacological approach to this human lung cancer.


Assuntos
Carcinoma de Células Pequenas/metabolismo , Neoplasias Pulmonares/metabolismo , Nicotina/farmacologia , Serotonina/metabolismo , Carcinoma de Células Pequenas/patologia , Relação Dose-Resposta a Droga , Humanos , Neoplasias Pulmonares/patologia , Mecamilamina/farmacologia
17.
Neuropharmacology ; 108: 324-31, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27157710

RESUMO

Studies with heterologous expression systems have shown that the α4ß2 nicotinic acetylcholine receptor (nAChR) subtype can exist in two stoichiometries (with two [(α4)2(ß2)3] or three [(α4)3(ß2)2] copies of the α subunit in the receptor pentamer) which have different pharmacological and functional properties and are differently regulated by chronic nicotine treatment. However, the effects of nicotine treatment in vivo on native α4ß2 nAChR stoichiometry are not well known. We investigated in C57BL/6 mice the in vivo effect of 14-day chronic nicotine treatment and subsequent withdrawal, on the subunit expression and ß2/α4 subunit ratio of (3)H-epibatidine labeled α4ß2*-nAChR in total homogenates of cortex and thalamus. We found that in basal conditions the ratio of the ß2/α4 subunit in the cortex and thalamus is different indicating a higher proportion in receptors with (α4)2(ß2)3 subunit stoichiometry in the thalamus. For cortex exposure to chronic nicotine elicited an increase in receptor density measured by (3)H-epibatidine binding, an increase in the α4 and ß2 protein levels, and an increase in ß2/α4 subunit ratio, that indicates an increased proportion of receptors with the (α4)2(ß2)3 stoichiometry. For thalamus we did not find a significant increase in receptor density, α4 and ß2 protein levels, or changes in ß2/α4 subunit ratio. All the changes elicited by chronic nicotine in cortex were transient and returned to basal levels with an average half-life of 2.8 days following nicotine withdrawal. These data suggest that chronic nicotine exposure in vivo favors increased assembly of α4ß2 nAChR containing three ß2 subunits. A greater change in stoichiometry was observed for cortex (which has relatively low basal expression of (α4)2(ß2)3 nAChR) than in thalamus (which has a relatively high basal expression of (α4)2(ß2)3 nAChR).


Assuntos
Córtex Cerebral/metabolismo , Nicotina/administração & dosagem , Receptores Nicotínicos/biossíntese , Tálamo/metabolismo , Regulação para Cima/fisiologia , Animais , Córtex Cerebral/efeitos dos fármacos , Esquema de Medicação , Infusões Intravenosas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Receptores Nicotínicos/química , Estereoisomerismo , Tálamo/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
18.
J Neurosci ; 21(18): 7037-45, 2001 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-11549713

RESUMO

Phox2a is a vertebrate homeodomain transcription factor that is involved in the specification of the autonomic nervous system. We have isolated the 5' regulatory region of the human Phox2a gene and studied the transcriptional mechanisms underlying its expression. We first identified the minimal gene promoter by means of molecular and functional criteria and demonstrated that its activity relies on a degenerate TATA box and a canonical Sp1 site. We then concentrated on the region immediately upstream of the promoter and found that it stimulates transcription in a neurospecific manner because its deletion caused a substantial decline in reporter gene expression only in neuronal cells. This DNA region contains a putative binding site for homeodomain transcription factors, and its mutation severely affects the transcriptional activity of the entire 5' regulatory region, thus indicating that this site is necessary for the expression of Phox2a in this cellular context. The use of the electrophoretic mobility shift assay showed that Phox2b/PMX2b is capable of specifically interacting with this site, and cotransfection experiments demonstrated that it is capable of transactivating the human Phox2a promoter. Many data obtained from knock-out mice support the hypothesis that Phox2a acts downstream of Phox2b during the development of most of the autonomic nervous system. We have provided the first molecular evidence that Phox2b can regulate the expression of Phox2a by directly binding to its 5' regulatory region.


Assuntos
Regulação da Expressão Gênica/fisiologia , Proteínas de Homeodomínio/metabolismo , Fator de Transcrição Sp1/metabolismo , Fatores de Transcrição/metabolismo , Regiões 5' não Traduzidas/genética , Sistema Nervoso Autônomo/embriologia , Sistema Nervoso Autônomo/metabolismo , Sequência de Bases , Sítios de Ligação/genética , Ligação Competitiva/fisiologia , Northern Blotting , Linhagem Celular , DNA/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Genes Reporter , Células HeLa , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/farmacologia , Humanos , Dados de Sequência Molecular , Proteínas do Tecido Nervoso , Neuroblastoma/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , Sequências Reguladoras de Ácido Nucleico , Fator de Transcrição Sp1/farmacologia , Relação Estrutura-Atividade , Fatores de Transcrição/genética , Fatores de Transcrição/farmacologia , Ativação Transcricional , Transfecção
19.
Eur Neuropsychopharmacol ; 25(10): 1775-86, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26141510

RESUMO

Nicotine is the primary addictive substance in tobacco smoke and electronic cigarette (e-cig) vapour. Methodological limitations have made it difficult to compare the role of the nicotine and non-nicotine constituents of tobacco smoke. The aim of this study was to compare the effects of traditional cigarette smoke and e-cig vapour containing the same amount of nicotine in male BALB/c mice exposed to the smoke of 21 cigarettes or e-cig vapour containing 16.8 mg of nicotine delivered by means of a mechanical ventilator for three 30-min sessions/day for seven weeks. One hour after the last session, half of the animals were sacrificed for neurochemical analysis, and the others underwent mecamylamine-precipitated or spontaneous withdrawal for the purposes of behavioural analysis. Chronic intermittent non-contingent, second-hand exposure to cigarette smoke or e-cig vapour led to similar brain cotinine and nicotine levels, similar urine cotinine levels and the similar up-regulation of α4ß2 nicotinic acetylcholine receptors in different brain areas, but had different effects on body weight, food intake, and the signs of mecamylamine-precipitated and spontaneous withdrawal episodic memory and emotional responses. The findings of this study demonstrate for the first time that e-cig vapour induces addiction-related neurochemical, physiological and behavioural alterations. The fact that inhaled cigarette smoke and e-cig vapour have partially different dependence-related effects indicates that compounds other than nicotine contribute to tobacco dependence.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina/efeitos adversos , Poluição por Fumaça de Tabaco/efeitos adversos , Tabagismo/fisiopatologia , Animais , Peso Corporal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cotinina/metabolismo , Modelos Animais de Doenças , Ingestão de Alimentos/efeitos dos fármacos , Emoções/efeitos dos fármacos , Masculino , Mecamilamina/farmacologia , Memória de Curto Prazo/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Nicotina/administração & dosagem , Nicotina/metabolismo , Agonistas Nicotínicos/administração & dosagem , Agonistas Nicotínicos/metabolismo , Antagonistas Nicotínicos/farmacologia , Receptores Nicotínicos/metabolismo , Respiração Artificial , Memória Espacial/efeitos dos fármacos , Síndrome de Abstinência a Substâncias/fisiopatologia , Síndrome de Abstinência a Substâncias/psicologia , Tabagismo/etiologia
20.
Eur J Cell Biol ; 37: 220-8, 1985 May.
Artigo em Inglês | MEDLINE | ID: mdl-2992977

RESUMO

The loss from the cell surface of cholinergic nicotinic receptors induced by exposure to antireceptor antibodies, and the mechanism of this loss has been studied in the BC3H-1 cell line. The maximal effect, i.e. 50% loss of receptors, was observed after 30 min. Receptor loss was due to internalization, which was not accompanied by a detectable increase in fluid phase endocytosis nor by changes in the number and distribution of intramembrane particles (IMP) revealed by freeze-fracture of the plasmalemma. The internalization was specific since the concentration of other receptors exposed at the surface of BC3H-1 cells (alpha and beta adrenergic receptors) was not affected by anticholinergic antibodies. It was temperature-dependent, independent of external calcium, but was blocked by trifluoperazine (TFP), a calmodulin antagonist. The rate of antibodies-induced receptor internalization was much more rapid than that of degradation and furthermore low concentrations of antibodies increased receptor internalization but did not increase receptor degradation. Our findings may be relevant to the clarification of the mechanism of Ab-induced alteration in autoimmune diseases, and in particular in myasthenia gravis.


Assuntos
Anticorpos , Músculos/metabolismo , Receptores Nicotínicos/metabolismo , Animais , Bungarotoxinas/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Técnica de Fratura por Congelamento , Cinética , Camundongos , Camundongos Endogâmicos C3H , Microscopia Eletrônica , Povidona-Iodo/metabolismo , Receptores Adrenérgicos alfa/metabolismo , Receptores Adrenérgicos beta/metabolismo , Receptores Nicotínicos/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA