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2.
Epidemiol Infect ; 146(12): 1511-1518, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29923481

RESUMO

Improving access to tuberculosis (TB) care and ensuring early diagnosis are two major aims of the WHO End TB strategy and the Collaborative TB Strategy for England. This study describes risk factors associated with diagnostic delay among TB cases in England. We conducted a retrospective cohort study of TB cases notified to the Enhanced TB Surveillance System in England between 2012 and 2015. Diagnostic delay was defined as more than 4 months between symptom onset and treatment start date. Multivariable logistic regression was used to identify demographic and clinical factors associated with diagnostic delay. Between 2012 and 2015, 22 422 TB cases were notified in England and included in the study. A third (7612) of TB cases had a diagnostic delay of more than 4 months. Being female, aged 45 years and older, residing outside of London and having extra-pulmonary TB disease were significantly associated with a diagnostic delay in the multivariable model (aOR = 1.2, 1.2, 1.2, 1.3, 1.8, respectively). This study identifies demographic and clinical factors associated with diagnostic delay, which will inform targeted interventions to improve access to care and early diagnosis among these groups, with the ultimate aim of helping reduce transmission and improve treatment outcomes for TB cases in England.


Assuntos
Diagnóstico Tardio , Tempo para o Tratamento , Tuberculose/diagnóstico , Tuberculose/tratamento farmacológico , Adulto , Inglaterra/epidemiologia , Feminino , Acessibilidade aos Serviços de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Vigilância da População , Estudos Retrospectivos , Fatores de Risco , Tuberculose/epidemiologia , Tuberculose/transmissão
3.
J Med Syst ; 42(4): 73, 2018 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-29511944

RESUMO

The original version of this article unfortunately contained a mistake. The name of Matthew Gerber was incorrectly spelled as Mathew Gerber. The correct spelling is now presented correctly in this correction article.

4.
J Med Syst ; 41(11): 182, 2017 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-29027078

RESUMO

The Veterans Health Administration (VHA) is plagued by abnormally high no-show and cancellation rates that reduce the productivity and efficiency of its medical outpatient clinics. We address this issue by developing a dynamic scheduling system that utilizes mobile computing via geo-location data to estimate the likelihood of a patient arriving on time for a scheduled appointment. These likelihoods are used to update the clinic's schedule in real time. When a patient's arrival probability falls below a given threshold, the patient's appointment is canceled. This appointment is immediately reassigned to another patient drawn from a pool of patients who are actively seeking an appointment. The replacement patients are prioritized using their arrival probability. Real-world data were not available for this study, so synthetic patient data were generated to test the feasibility of the design. The method for predicting the arrival probability was verified on a real set of taxicab data. This study demonstrates that dynamic scheduling using geo-location data can reduce the number of unused appointments with minimal risk of double booking resulting from incorrect predictions. We acknowledge that there could be privacy concerns with regards to government possession of one's location and offer strategies for alleviating these concerns in our conclusion.


Assuntos
Instituições de Assistência Ambulatorial/organização & administração , Agendamento de Consultas , Telefone Celular , Eficiência Organizacional , Análise Espaço-Temporal , Algoritmos , Simulação por Computador , Humanos , Fatores de Tempo , Estados Unidos , United States Department of Veterans Affairs
5.
One Health ; 3: 44-50, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28616503

RESUMO

The need for multidisciplinary research to address today's complex health and environmental challenges has never been greater. The One Health (OH) approach to research ensures that human, animal, and environmental health questions are evaluated in an integrated and holistic manner to provide a more comprehensive understanding of the problem and potential solutions than would be possible with siloed approaches. However, the OH approach is complex, and there is limited guidance available for investigators regarding the practical design and implementation of OH research. In this paper we provide a framework to guide researchers through conceptualizing and planning an OH study. We discuss key steps in designing an OH study, including conceptualization of hypotheses and study aims, identification of collaborators for a multi-disciplinary research team, study design options, data sources and collection methods, and analytical methods. We illustrate these concepts through the presentation of a case study of health impacts associated with land application of biosolids. Finally, we discuss opportunities for applying an OH approach to identify solutions to current global health issues, and the need for cross-disciplinary funding sources to foster an OH approach to research.

6.
Thorax ; 70(3): 297-8, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24928813

RESUMO

Using the best available evidence and expert consensus, this document provides guidance for adverse effect monitoring in multidrug-resistant TB (MDR-TB). It includes recommendations for baseline tests, routine drug and toxicity monitoring guides as well as individual drug monographs for all drugs currently available in the UK to treat TB. These recommendations provide a structure through which healthcare professionals can better manage the complex drug regimens required for the treatment of MDR-TB; minimising the risk of adverse incidents and helping to improve patients' tolerance, compliance and treatment completion.


Assuntos
Antituberculosos/uso terapêutico , Guias de Prática Clínica como Assunto , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Pulmonar/tratamento farmacológico , Antituberculosos/efeitos adversos , Humanos , Reino Unido
7.
Endocrinology ; 154(9): 3022-30, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23825120

RESUMO

Little is known about the mechanism for the prolonged residence time of 25-hydroxyvitamin D (25OHD) in blood. Several lines of evidence led us to propose that skeletal muscle could function as the site of an extravascular pool of 25OHD. In vitro studies investigated the capacity of differentiated C2 murine muscle cells to take up and release 25OHD, in comparison with other cell types and the involvement of the membrane protein megalin in these mechanisms. When C2 cells are differentiated into myotubes, the time-dependent uptake of labeled 25OHD is 2-3 times higher than in undifferentiated myoblasts or nonmuscle osteoblastic MG63 cells (P < .001). During in vitro release experiments (after 25OHD uptake), myotubes released only 32% ± 6% stored 25OHD after 4 hours, whereas this figure was 60% ± 2% for osteoblasts (P < .01). Using immunofluorescence, C2 myotubes and primary rat muscle fibers were, for the first time, shown to express megalin and cubilin, endocytotic receptors for the vitamin D binding protein (DBP), which binds nearly all 25OHD in the blood. DBP has a high affinity for actin in skeletal muscle. A time-dependent uptake of Alexafluor-488-labeled DBP into mature muscle cells was observed by confocal microscopy. Incubation of C2 myotubes (for 24 hours) with receptor-associated protein, a megalin inhibitor, led to a 40% decrease in 25OHD uptake (P < .01). These data support the proposal that 25OHD, after uptake into mature muscle cells, is held there by DBP, which has been internalized via membrane megalin and is retained by binding to actin.


Assuntos
Calcifediol/metabolismo , Endocitose , Atividade Motora , Músculo Esquelético/metabolismo , Proteína de Ligação a Vitamina D/metabolismo , Animais , Calcifediol/sangue , Diferenciação Celular , Linhagem Celular , Células Cultivadas , Líquido Extracelular/metabolismo , Feminino , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/antagonistas & inibidores , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/citologia , Mioblastos Esqueléticos/citologia , Mioblastos Esqueléticos/metabolismo , Osteoblastos/citologia , Osteoblastos/metabolismo , Distribuição Aleatória , Receptores de Superfície Celular/metabolismo
8.
J Hum Nutr Diet ; 26(2): 111-25, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23331476

RESUMO

BACKGROUND: Compounds other than macronutrients have been shown to influence blood glucose concentrations and insulin sensitivity in people with diabetes, with caffeine being one such substance. The present study systematically reviewed the evidence of the effects of caffeine on blood glucose concentrations and/or insulin sensitivity in people with diabetes. METHODS: Four databases, including MEDLINE and EMBASE, were searched up to 1 February 2012. Randomised controlled trials (RCTs) investigating the effects of caffeine on blood glucose and/or insulin sensitivity in humans, diagnosed with type I, type II or gestational diabetes mellitus (GDM), were included. Quality assessment and data extraction were conducted and agreed by both authors. RESULTS: Of 253 articles retrieved, nine trials (134 participants) were identified. Trials in people with type II diabetes demonstrated that the ingestion of caffeine (approximately 200-500 mg) significantly increased blood glucose concentrations by 16-28% of the area under the curve (AUC) and insulin concentrations by 19-48% of the AUC when taken prior to a glucose load, at the same time as decreasing insulin sensitivity by 14-37%. In type I diabetes, trials indicated enhanced recognition and a reduced duration of hypoglycaemic episodes following ingestion of 400-500 mg caffeine, without altering glycated haemoglobin. In GDM, a single trial demonstrated that approximately 200 mg of caffeine induced a decrease in insulin sensitivity by 18% and a subsequent increase in blood glucose concentrations by 19% of the AUC. CONCLUSIONS: Evidence indicates a negative effect of caffeine intake on blood glucose control in individuals with type II diabetes, as replicated in a single trial in GDM. Larger-scale RCTs of longer duration are needed to determine the effects of timing and dose. Early indications of a reduced duration and an improved awareness of hypoglycaemia in type I diabetes require further confirmation.


Assuntos
Cafeína/efeitos adversos , Diabetes Mellitus Tipo 2/sangue , Medicina Baseada em Evidências , Hiperglicemia/induzido quimicamente , Resistência à Insulina , Bebidas/efeitos adversos , Glicemia/análise , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Gestacional/sangue , Diabetes Gestacional/metabolismo , Feminino , Interações Alimento-Droga , Humanos , Hiperinsulinismo/induzido quimicamente , Hipoglicemia/induzido quimicamente , Hipoglicemiantes/uso terapêutico , Insulina/uso terapêutico , Masculino , Gravidez , Ensaios Clínicos Controlados Aleatórios como Assunto
9.
Sci Total Environ ; 407(14): 4238-42, 2009 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-19406452

RESUMO

The global fallout (236)U level in soil was deduced from measurements of (236)U, (239+240)Pu and (137)Cs in surface soils which are solely influenced by global fallout. A total of 12 soil cores from the depths of 0-10, 0-20 and 0-30 cm were collected at a flat forest area in Japan. Concentrations of (239+240)Pu and (238)U were determined by alpha-particle spectrometry, while the (236)U/(238)U ratio was measured with accelerator mass spectrometry (AMS). Consistent (236)U/(239)Pu ratios between 0.212 and 0.253 were found. Using this ratio, the total global fallout of (236)U on the earth is estimated to be as much as ca. 900 kg. This knowledge will contribute to the promotion of research on U isotopes, including (236)U, for the fields of geo-resources, waste management and geochemistry.


Assuntos
Poluentes Radioativos do Solo/análise , Urânio/análise , Japão , Espectrometria de Massas
10.
J Environ Radioact ; 99(2): 260-70, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17904707

RESUMO

Cosmogenic (10)Be, known for use in dating studies, unexpectedly is also produced in nuclear explosions with an atom yield almost comparable to (e.g.) (137)Cs. There are major production routes via (13)C(n, alpha)(10)Be, from carbon dioxide in the air and the organic explosives, possibly from other bomb components and to a minor extent from the direct fission reaction. Although the detailed bomb components are speculative, carbon was certainly present in the explosives and an order of magnitude calculation is possible. The (n, alpha) cross-section was determined by irradiating graphite in a nuclear reactor, and the resulting (10)Be estimated by Accelerator Mass Spectrometry (AMS) giving a cross-section of 34.5+/-0.7mb (6-9.3MeV), within error of previous work. (10)Be should have applications in forensic radioecology. Historical environmental samples from Hiroshima, and Semipalatinsk (Kazakhstan) showed two to threefold (10)Be excesses compared with the background cosmogenic levels. A sample from Lake Chagan (a Soviet nuclear cratering experiment) contained more (10)Be than previously reported soils. (10)Be may be useful for measuring the fast neutron dose near the Hiroshima bomb hypocenter at neutron energies double those previously available.


Assuntos
Berílio/química , Ecologia , Explosões , Ciências Forenses , Guerra Nuclear , Japão , Espectrometria de Massas
11.
J Biosoc Sci ; 39(6): 905-21, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17316469

RESUMO

The maternal immune hypothesis (MIH) argues same sex attraction (SSA) results from maternal immune attack on fetal male-specific brain structures and involves the previous biological influence of elder brothers. One of the surveys supporting this is shown to be based on an unsuitable sample and to contain some strong contrary evidence. The hypothesis relies on at least four speculative ideas and there is evidence against each. (1) Likely immune response prevalence is too low compared with calculated SSA prevalence resulting from the fraternal birth order effect. (2) Testis immune attack would be more likely than brain attack but is not known. (3) Fetal brain structures are practically indistinguishable at birth and subsequent brain anatomical gender differentiation only occurs after birth when no attack is occurring. (4) The hypothesis also predicts unfavourable biology for late birth-order males but in fact the reverse is generally true, and neurological effects are very minor. Studies show aborted fetuses caused by likely maternal immune attack are predominantly girls rather than boys, which also argues against the theory. Studies on identical twins show that common factors such as uterine environment are only a small influence on SSA and post-natal idiosyncratic reactions and non-shared environmental factors are much larger influences.


Assuntos
Anticorpos , Antígenos , Ordem de Nascimento , Imunidade , Resultado da Gravidez , Processos de Determinação Sexual , Peso ao Nascer , Feminino , Feto/imunologia , Humanos , Masculino , Gravidez , Fatores Sexuais
12.
J Environ Radioact ; 92(1): 16-29, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17056160

RESUMO

222Rn and 220Rn in geothermal steam at Wairakei, NZ, range from 11 to 19, 500 Bq kg-1, and 25 to 16, 700 Bq kg-1, respectively, but do not cause toxic concentrations in air. The wide ranges are mainly due to differences in different physical conditions underground (e.g. thin silica diffusion barriers), not geochemical differences. Groundwater Rn from outside the area probably plays only a minor role. 210Po was found present in non-toxic levels in the steam. Historical records showed little change in Rn concentration over several decades, therefore potentially hazardous concentrations might be predicted from early exploration. 220Rn concentrations at Wairakei should decrease as the field becomes steam-dominated. Rock surfaces were variably leached or enriched with U, Th, Ra and 210Pb, providing a possible model for deposition in cooler regions near the field. Estimates of 222Rn permeability ranged from 2 to 77% of the maximum possible, with a median of 13%.


Assuntos
Monitoramento Ambiental/métodos , Fontes Termais , Radônio/análise , Nova Zelândia , Polônio/análise , Monitoramento de Radiação
13.
J Physiol ; 567(Pt 3): 723-35, 2005 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-16002444

RESUMO

Muscle damage, characterized by prolonged weakness and delayed onset of stiffness and soreness, is common following contractions in which the muscles are stretched. Stretch-induced damage of this sort is more pronounced in the muscular dystrophies and the profound muscle damage observed in these conditions may involve similar pathways. It has been known for many years that damaged muscles accumulate calcium and that elevating calcium in normal muscles simulates many aspects of muscle damage. The changes in intracellular calcium, sodium and pH following stretched contractions are reviewed and the various pathways which have been proposed to allow ion entry are discussed. One possibility is that TRPC1 (transient receptor potential, canonical), a protein which seems to form both a stretch-activated channel and a store-operated channel, is the main source of Ca(2+) entry. The mechanisms by which the changes in intracellular ions contribute to reduced force production, to increased protein breakdown and to increased membrane permeability are considered. A hypothetical scheme for muscle damage which incorporates these ideas is presented.


Assuntos
Contração Muscular , Doenças Musculares/fisiopatologia , Canais de Cátion TRPC/metabolismo , Animais , Cálcio/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Músculo Esquelético/metabolismo , Doenças Musculares/metabolismo , Distrofias Musculares/metabolismo , Sódio/metabolismo
14.
Mol Plant Microbe Interact ; 18(4): 343-53, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15828686

RESUMO

Seven new genes controlled by the quorum-sensing signal molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) have been identified in Erwinia carotovora subsp. carotovora. Using TnphoA as a mutagen, we enriched for mutants defective in proteins that could play a role in the interaction between E. carotovora subsp. carotovora and its plant hosts, and identified NipEcc and its counterpart in E. carotovora subsp. atroseptica. These are members of a growing family of proteins related to Nep1 from Fusarium oxysporum which can induce necrotic responses in a variety of dicotyledonous plants. NipEcc produced necrosis in tobacco, NipEca affected potato stem rot, and both affected virulence in potato tubers. In E. carotovora subsp. carotovora, nip was shown to be subject to weak repression by the LuxR family regulator, EccR, and may be regulated by the negative global regulator RsmA.


Assuntos
4-Butirolactona/análogos & derivados , 4-Butirolactona/metabolismo , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Homosserina/análogos & derivados , Homosserina/metabolismo , Pectobacterium carotovorum/genética , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Elementos de DNA Transponíveis , Teste de Complementação Genética , Dados de Sequência Molecular , Mutagênese , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Solanum tuberosum/genética
15.
J Psychosom Obstet Gynaecol ; 24(2): 77-86, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12854392

RESUMO

This study evaluates the prevalence of selected life events around the time of pregnancy, examining changes in the prevalence of these events, and identifying maternal characteristics associated with these events. We used data from the Pregnancy Risk Assessment Monitoring System (PRAMS) to examine 18 stressful life events among women who recently gave birth and to identify maternal characteristics associated with these events. PRAMS is a mail sample survey with telephone follow-up for non-respondents. Sixty-four percent of women experienced at least one event. The prevalence of specific events ranged from 0.4 to 30%. Women who experienced events differed from those who did not. Most notably, women of low socioeconomic status (SES) were much more likely to experience stressful life events. These events were also associated with other demographic and behavioral characteristics after controlling for SES. These results have implications for interpreting studies of stressful life events. The strong associations with SES highlight the importance of controlling for SES in studies of life events and health, and of considering differences in SES when interpreting these studies.


Assuntos
Acontecimentos que Mudam a Vida , Estresse Psicológico/epidemiologia , Estresse Psicológico/psicologia , Adolescente , Adulto , Demografia , Feminino , Humanos , Gravidez , Prevalência , Fatores de Tempo
16.
J Appl Physiol (1985) ; 95(3): 1224-34, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12740312

RESUMO

This is a report of experiments carried out on the medial gastrocnemius muscle of the anesthetized cat, investigating the effects of eccentric contractions carried out at different muscle lengths on the passive and active length-tension relationships. In one series of experiments, the motor supply to the muscle was divided into three approximately equal parts; in the other, whole muscles were used. Fifty eccentric contractions were carried out over different regions of the active length-tension curve for each partial or whole muscle. Active and passive length-tension curves were measured before and after the eccentric contractions. When eccentric contractions were carried out at longer lengths, there was a larger shift of the optimum length for active tension in the direction of longer muscle lengths and a larger fall in peak isometric tension. Passive tension was higher immediately after the eccentric contractions, and if the muscle was left undisturbed for 40 min, it increased further to higher values, particularly after contractions at longer lengths. A series of 20 passive stretches of the same speed and amplitude and covering the same length range as the active stretches, reduced the passive tension which redeveloped over a subsequent 40-min period. It is hypothesized that there are two factors influencing the level of passive tension in a muscle after a series of eccentric contractions. One is injury contractures in damaged muscle fibers tending to raise passive tension; the other is the presence of disrupted sarcomeres in series with still-functioning sarcomeres tending to reduce it.


Assuntos
Músculo Esquelético/fisiologia , Animais , Gatos , Complacência (Medida de Distensibilidade) , Estimulação Elétrica , Feminino , Contração Isométrica/fisiologia , Masculino , Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/citologia , Músculo Esquelético/lesões , Sarcômeros/fisiologia
17.
J Physiol ; 538(Pt 1): 209-18, 2002 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-11773329

RESUMO

To investigate the possibility of a peripheral contribution to the perturbations of force sensation reported to occur after eccentric exercise, responses to passive and active tension were recorded from Golgi tendon organs in the medial gastrocnemius muscle of the anaesthetised cat, before and after a series of eccentric contractions. After the eccentric contractions, nearly all tendon organs commenced firing at a shorter muscle length during slow passive stretch than before, probably because of a rise in whole muscle passive tension. There was a small drop in the sensitivity to incremental tension, but no mean change in tension threshold. Following the eccentric contractions, there was a small, but not significant, increase in tendon organ sensitivity to active tension, which was graded using a method of optimised, distributed stimulation of divided ventral roots. Sensitivity was estimated as the mean response over a range of tensions and as the change in discharge rate in response to incremental tension. The experiments provided the opportunity of comparing tendon organ sensitivities to graded passive and active whole muscle tension. In agreement with previous work in which whole muscle nerve stimulation was employed, little difference was found. It was concluded that the peripheral contribution to perturbations of force perception after eccentric exercise is likely to be small and that the centrally derived sense of effort plays the dominant role. Tendon organs appear to be remarkably reliable in signalling whole muscle tension, whether passive or active, and even after the muscle's force production has been disturbed by fatigue or eccentric exercise.


Assuntos
Mecanorreceptores/fisiologia , Contração Muscular/fisiologia , Animais , Gatos , Estimulação Elétrica , Feminino , Masculino , Músculo Esquelético/fisiologia , Estresse Mecânico
18.
J Physiol ; 536(Pt 3): 893-903, 2001 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11691881

RESUMO

1. This is a report on the history dependence of the passive mechanical properties of the medial gastrocnemius muscle of the anaesthetised cat. 2. The muscle was conditioned with an isometric contraction at the test length, or at 3 mm longer than the test length and then returned to the test length, where the level of resting tension was measured, as well as tension changes during a slow stretch. 3. The level of resting tension depended on the form of conditioning and, at the optimum length for active tension, the history-dependent component was 9 % of the total passive tension. 4. During a slow stretch, tension initially rose steeply up to a yield point, beyond which it rose more gradually. The shape of the tension rise depended on the form of conditioning. The level of tension at the yield point consisted of a stretch-dependent component, the 'short-range tension' plus the resting tension for that length. 5. The short-range tension increased with muscle length to peak close to the optimum for active tension. The slope of the tension rise during a stretch, the short-range stiffness, peaked at 2 mm beyond the optimum. 6. The short-range tension was small immediately after a conditioning contraction but grew in size as the interval was increased up to 60 s, with a time constant of 9.9 +/- 0.6 s. After a series of conditioning movements, it recovered more rapidly, with a time constant of 6.6 +/- 0.5 s. 7. The history-dependent changes in passive tension and the response to stretch are interpreted in terms of the presence, in sarcomeres of resting muscle fibres, of crossbridges between actin and myosin which have very slow formation rates, both at rest and during movements.


Assuntos
Músculo Esquelético/fisiologia , Actinas/fisiologia , Anestesia , Animais , Gatos , Feminino , Contração Isométrica/efeitos dos fármacos , Masculino , Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/citologia , Miosinas/fisiologia , Sarcômeros/fisiologia , Fatores de Tempo
19.
FEMS Microbiol Rev ; 25(4): 365-404, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11524130

RESUMO

It has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. The languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. Many types of signalling molecules, which regulate diverse phenotypes across distant genera, have been described. The most common signalling molecules found in Gram-negative bacteria are N-acyl derivatives of homoserine lactone (acyl HSLs). Modulation of the physiological processes controlled by acyl HSLs (and, indeed, many of the non-acyl HSL-mediated systems) occurs in a cell density- and growth phase-dependent manner. Therefore, the term 'quorum-sensing' has been coined to describe this ability of bacteria to monitor cell density before expressing a phenotype. In this paper, we review the current state of research concerning acyl HSL-mediated quorum-sensing. We also describe two non-acyl HSL-based systems utilised by the phytopathogens Ralstonia solanacearum and Xanthomonas campestris.


Assuntos
4-Butirolactona/análogos & derivados , Proteínas de Bactérias/metabolismo , Bactérias Gram-Negativas/citologia , Bactérias Gram-Negativas/metabolismo , Proteínas Repressoras/metabolismo , Transdução de Sinais , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , 4-Butirolactona/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Contagem de Colônia Microbiana , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/patogenicidade , Modelos Biológicos , Dados de Sequência Molecular , Proteínas Repressoras/química , Transativadores/química , Fatores de Transcrição/química
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