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1.
Ir Med J ; 114(7): 403, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34520346

RESUMO

Introduction Remote consultation is of growing in importance and gaining popularity in both primary and secondary healthcare settings. Reduced necessity for a physical presence of the patient within the healthcare setting is of particular benefit in the current COVID-19 era. It is also of benefit to a diverse group of patients, for example: those who are geographically distant from the base hospital, those suffering from mobility issues or chronic illness, those who require chaperoning as well as those with limited access to transport. We have developed guidelines for the use of the medical telecommunications platform, Attend Anywhere, which has been utilised across the English and Scottish National Health Services, as well as with the Australian Health service, and is now available in Health Service Executive (HSE) settings. Herein we describe and recommend a process that we have found helpful, and we propose guidelines on how a Health Care Worker (HCW) might consider approaching a virtual consultation when initiating and safely executing a patient encounter on Attend Anywhere, in a secure and efficient manner. The guidelines were created following review of the literature on previous experience by others with this software, as well as recent guidance published by the Irish Medical Council. A proportion of this guidance is transferable to other platforms. Methods We also undertook a short survey of our patients and physicians in Sligo University Hospital, who used Attend Anywhere over a six-week period to gauge their satisfaction levels with the experience., We estimated distance that our patients would have travelled for their appointment had the traditional face-to-face consultation been carried out. We noted whether we considered the medium appropriate for the patient consultations. Results 53 patients took part and satisfaction was rated from satisfied to very satisfied on a 3-point scale for all stakeholders. In addition, we found that remote consultation, when compared to face-to-face consultation, alleviated an average of 144km of unnecessary travel per appointment. Remote consultation was deemed appropriate in all cases and no rescheduled face-to-face appointments were required due to failure of the consultation due to difficulties encountered. Conclusion The authors recommend the implementation of the described guidance, with suggested Checklist, Information leaflet and Consent form, as a means of ensuring the confidentiality of the consultation and to ensure that processes are adhered to that optimise protection for both the patient and the clinician, while reducing the burden of attendance to the healthcare location.


Assuntos
COVID-19/epidemiologia , Dor Crônica/diagnóstico , Dor Crônica/terapia , Consulta Remota/organização & administração , Tecnologia de Sensoriamento Remoto/métodos , Austrália , Humanos , Programas Nacionais de Saúde , Manejo da Dor , Satisfação do Paciente , Pesquisa Qualitativa , Telecomunicações/organização & administração , Tecnologia sem Fio
2.
Insect Mol Biol ; 28(3): 392-408, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30548465

RESUMO

Embryonic terminal patterning and moulting are critical developmental processes in insects. In Drosophila and Tribolium both of these processes are regulated by the Torso-activation cassette (TAC). The TAC consists of a common receptor, Torso, ligands Trunk and prothoracicotropic hormone (PTTH), and the spatially restricted protein Torso-like, with combinations of these elements acting mechanistically to activate the receptor in different developmental contexts. In order to trace the evolutionary history of the TAC we determined the presence or absence of TAC components in the genomes of arthropods. Our analyses reveal that Torso, Trunk and PTTH are evolutionarily labile components of the TAC with multiple individual or combined losses occurring in the arthropod lineages leading to and within the insects. These losses are often correlated, with both ligands and receptor missing from the genome of the same species. We determine that the PTTH gene evolved in the common ancestor of Hemiptera and Holometabola, and is missing from the genomes of a number of species with experimentally demonstrated PTTH activity, implying another molecule may be involved in ecdysis in these species. In contrast, the torso-like gene is a common component of pancrustacean genomes.


Assuntos
Padronização Corporal , Regulação da Expressão Gênica no Desenvolvimento , Genoma de Inseto , Hormônios de Inseto/metabolismo , Proteínas de Insetos/genética , Insetos/genética , Animais , Proteínas de Insetos/metabolismo , Insetos/crescimento & desenvolvimento , Ligantes
3.
Genesis ; 55(5)2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28432809

RESUMO

Honeybees are an important component of modern agricultural systems, and a fascinating and scientifically engrossing insect. Honeybees are not commonly used as model systems for understanding development in insects despite their importance in agriculture. Honeybee embryogenesis, while being superficially similar to Drosophila, is molecularly very different, especially in axis formation and sex determination. In later development, much of honeybee biology is modified by caste development, an as yet poorly understood, but excellent, system to study developmental plasticity. In adult stages, developmental plasticity of the ovaries, related to reproductive constraint exhibits another aspect of plasticity. Here they review the tools, current knowledge and opportunities in honeybee developmental biology, and provide an updated embryonic staging scheme to support future studies.


Assuntos
Abelhas/genética , Desenvolvimento Embrionário/genética , Animais , Abelhas/embriologia , Genes de Insetos
4.
Oral Dis ; 21(1): e121-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24725067

RESUMO

RATIONALE: Obstructive sleep apnoea syndrome (OSAS) is a debilitating condition characterized by recurrent occlusions of the pharyngeal airway during sleep accompanied by arterial hypoxaemia. Upper airway muscle dysfunction is implicated in the pathophysiology of OSAS. Pharmacological agents that improve muscle contractile and endurance properties may have therapeutic value. AIM: We tested the hypothesis that the ß(2) -adrenoceptor agonist terbutaline improves rat sternohyoid muscle performance especially during hypoxic stress. METHODS: Isometric contractile and endurance properties were examined ex vivo in Krebs solution at 35°C. Muscles were incubated in tissue baths under hyperoxic (95% O(2) /5% CO(2)) conditions in the absence (control) or presence of the ß(2) -adrenoceptor agonist terbutaline (1 µM). In additional experiments under hypoxic (95% N(2) /5% CO(2)) conditions, the effects of terbutaline were examined in the presence of the ß-adrenoceptor antagonist propranolol (1 µM). RESULTS: Hypoxia significantly impaired sternohyoid force production. Terbutaline completely recovered hypoxic depression of force, an effect that was blocked by co-application with propranolol. CONCLUSION: The ß(2) -adrenoceptor agonist terbutaline completely recovers hypoxic depression of upper airway muscle force. ß(2) -adrenoceptor agonists warrant investigation in animal models of OSAS reporting upper airway and diaphragm muscle dysfunction.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Hipóxia/fisiopatologia , Músculos Faríngeos/efeitos dos fármacos , Terbutalina/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculos Faríngeos/fisiopatologia , Propranolol/farmacologia , Ratos , Ratos Wistar
5.
Exp Physiol ; 99(4): 688-700, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24443349

RESUMO

Respiratory muscle dysfunction documented in sleep apnoea patients is perhaps due to oxidative stress secondary to chronic intermittent hypoxia (CIH). We sought to explore the effects of different CIH protocols on respiratory muscle form and function in a rodent model. Adult male Wistar rats were exposed to CIH (n = 32) consisting of 90 s normoxia-90 s hypoxia (either 10 or 5% oxygen at the nadir; arterial O2 saturation ∼ 90 or 80%, respectively] for 8 h per day or to sham treatment (air-air, n = 32) for 1 or 2 weeks. Three additional groups of CIH-treated rats (5% O2 for 2 weeks) had free access to water containing N-acetyl cysteine (1% NAC, n = 8), tempol (1 mM, n = 8) or apocynin (2 mM, n = 8). Functional properties of the diaphragm muscle were examined ex vivo at 35 °C. The myosin heavy chain and sarco(endo)plasmic reticulum Ca(2+)-ATPase isoform distribution, succinate dehydrogenase and glyercol phosphate dehydrogenase enzyme activities, Na(+)-K(+)-ATPase pump content, concentration of thiobarbituric acid reactive substances, DNA oxidation and antioxidant capacity were determined. Chronic intermittent hypoxia (5% oxygen at the nadir; 2 weeks) decreased diaphragm muscle force and endurance. All three drugs reversed the deleterious effects of CIH on diaphragm endurance, but only NAC prevented CIH-induced diaphragm weakness. Chronic intermittent hypoxia increased diaphragm muscle myosin heavy chain 2B areal density and oxidized glutathione/reduced glutathione (GSSG/GSH) ratio. We conclude that CIH-induced diaphragm dysfunction is reactive oxygen species dependent. N-Acetyl cysteine was most effective in reversing CIH-induced effects on diaphragm. Our results suggest that respiratory muscle dysfunction in sleep apnoea may be the result of oxidative stress and, as such, antioxidant treatment could prove a useful adjunctive therapy for the disorder.


Assuntos
Diafragma/metabolismo , Hipóxia/metabolismo , Contração Muscular , Fadiga Muscular , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Animais , Antioxidantes/farmacologia , Doença Crônica , Diafragma/efeitos dos fármacos , Diafragma/fisiopatologia , Modelos Animais de Doenças , Glutationa/metabolismo , Glicerolfosfato Desidrogenase/metabolismo , Hipóxia/fisiopatologia , Masculino , Contração Muscular/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Cadeias Pesadas de Miosina/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos Wistar , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Succinato Desidrogenase/metabolismo , Fatores de Tempo
6.
Am J Respir Cell Mol Biol ; 46(2): 139-48, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21868712

RESUMO

Respiratory muscle dysfunction is implicated in the pathophysiology of obstructive sleep apnea syndrome (OSAS), an oxidative stress disorder prevalent in men. Pharmacotherapy for OSAS is an attractive option, and antioxidant treatments may prove beneficial. We examined the effects of chronic intermittent hypoxia (CIH) on breathing and pharyngeal dilator muscle structure and function in male and female rats. Additionally, we tested the efficacy of antioxidant treatment in preventing (chronic administration) or reversing (acute administration) CIH-induced effects in male rats. Adult male and female Wistar rats were exposed to alternating cycles of normoxia and hypoxia (90 s each; Fi(O(2)) = 5% O(2) at nadir; Sa(O(2)) ∼ 80%) or sham treatment for 8 h/d for 9 days. Tempol (1 mM, superoxide dismutase mimetic) was administered to subgroups of sham- and CIH-treated animals. Breathing was assessed by whole-body plethysmography. Sternohyoid muscle contractile and endurance properties were examined in vitro. Muscle fiber type and cross-sectional area and the activity of key metabolic enzymes were determined. CIH decreased sternohyoid muscle force in male rats only. This was not attributable to fiber transitions or alterations in oxidative or glycolytic enzyme activity. Muscle weakness after CIH was prevented by chronic Tempol supplementation and was reversed by acute antioxidant treatment in vitro. CIH increased normoxic ventilation in male rats only. Sex differences exist in the effects of CIH on the respiratory system, which may contribute to the higher prevalence of OSAS in male subjects. Antioxidant treatment may be beneficial as an adjunct OSAS therapy.


Assuntos
Óxidos N-Cíclicos/farmacologia , Modelos Animais de Doenças , Hipóxia/fisiopatologia , Músculos Faríngeos/efeitos dos fármacos , Animais , Peso Corporal , Doença Crônica , Enzimas/metabolismo , Feminino , Coração/fisiopatologia , Hematócrito , Masculino , Cadeias Pesadas de Miosina/metabolismo , Tamanho do Órgão , Músculos Faríngeos/metabolismo , Músculos Faríngeos/fisiopatologia , Pletismografia , Ratos , Ratos Wistar , Marcadores de Spin
7.
Respiration ; 82(6): 539-49, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21997469

RESUMO

BACKGROUND: Age, obesity and male sex are risk factors for the development of obstructive sleep apnoea syndrome. OBJECTIVE: We examined structural and functional properties of the sternohyoid muscle in young lean and aged obese male rats. We hypothesized that the aged muscle would be vulnerable to oxidative stress (hypoxia). METHODS: Isometric contractile and endurance properties of the sternohyoid muscle were assessed in vitro with or without the superoxide scavenger Tempol (10 mM). Muscle fibre size and density were determined by myosin heavy chain immunofluorescence. Succinate dehydrogenase (SDH) and glycerol-3- phosphate dehydrogenase (GPDH) enzyme activities were determined. RESULTS: Fibre hypertrophy, increased fast twitch (type 2X) fibre density, decreased SDH activity and increased GPDH activity, together with increased force and fatigue, were observed in aged obese muscles compared to young lean muscles. Tempol treatment increased strength and sensitivity to stimulation. Hypoxic depression of force was ameliorated by antioxidant treatment with equivalent effects in young lean and aged obese muscle. CONCLUSIONS: We conclude that the rat sternohyoid exhibits indefinite growth and is protected from oxidative stress as the animal ages.


Assuntos
Envelhecimento , Obesidade/fisiopatologia , Músculos Respiratórios/fisiopatologia , Apneia Obstrutiva do Sono/fisiopatologia , Animais , Antioxidantes/farmacologia , Hipóxia Celular , Óxidos N-Cíclicos/farmacologia , Estimulação Elétrica , Masculino , Contração Muscular/efeitos dos fármacos , Obesidade/complicações , Obesidade/tratamento farmacológico , Estresse Oxidativo , Ratos , Ratos Wistar , Músculos Respiratórios/efeitos dos fármacos , Fatores de Risco , Apneia Obstrutiva do Sono/tratamento farmacológico , Apneia Obstrutiva do Sono/etiologia , Marcadores de Spin
8.
Am J Respir Cell Mol Biol ; 42(6): 725-31, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19635929

RESUMO

Obstructive sleep apnea is a common disorder associated with upper airway muscle dysfunction. Agents that improve respiratory muscle performance may be useful as an adjunct therapy. The aim of this study was to examine the effects of antioxidants on rat pharyngeal dilator muscle performance. Adult male Wistar rats were killed humanely and isometric contractile properties of isolated sternohyoid muscle strips were examined in physiological salt solution at 35 degrees C in vitro. Muscle strips were incubated in tissue baths under hyperoxic (95%O(2)/5%CO(2)) or hypoxic (95%N(2)/5%CO(2)) conditions in the absence (control) or presence of the antioxidants: N-acetylcysteine (10 mM), Tiron (10 mM), or Tempol (10 mM). Force-frequency relationship was determined in response to supramaximal stimulation (10-100 Hz in increments of 10-20 Hz, train duration: 300 ms). Isometric force was also recorded during repetitive muscle stimulation (40 Hz, 300 ms every 2 s for 2 min). Under hyperoxic conditions, Tiron and Tempol, but not N-acetylcysteine, significantly increased sternohyoid muscle force and caused a left-shift in the force-frequency relationship. In addition, Tempol had a significant positive inotropic effect over the initial 90 seconds of repeated muscle activation. Hypoxia caused a significant decrease in sternohyoid muscle force. Under hypoxic conditions, Tempol-incubated muscles generated significantly higher forces compared with control muscles and showed improved performance in the early phase of the fatigue trial. This study illustrates that superoxide scavengers increase upper airway muscle force and that this effect persists under hypoxic conditions. We conclude that antioxidant treatment may be beneficial as a therapy in obstructive sleep apnea.


Assuntos
Sequestradores de Radicais Livres/farmacologia , Contração Isométrica/efeitos dos fármacos , Força Muscular/efeitos dos fármacos , Músculos Faríngeos/efeitos dos fármacos , Superóxidos/metabolismo , Sal Dissódico do Ácido 1,2-Di-Hidroxibenzeno-3,5 Dissulfônico/farmacologia , Acetilcisteína/farmacologia , Animais , Óxidos N-Cíclicos/farmacologia , Estimulação Elétrica , Hiperóxia/metabolismo , Hiperóxia/fisiopatologia , Hipóxia/metabolismo , Hipóxia/fisiopatologia , Técnicas In Vitro , Masculino , Músculos Faríngeos/metabolismo , Músculos Faríngeos/fisiopatologia , Ratos , Ratos Wistar , Apneia Obstrutiva do Sono/tratamento farmacológico , Apneia Obstrutiva do Sono/metabolismo , Apneia Obstrutiva do Sono/fisiopatologia , Marcadores de Spin , Fatores de Tempo
9.
Adv Exp Med Biol ; 669: 285-7, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20217367

RESUMO

Upper airway muscle dysfunction is implicated in obstructive sleep apnoea syndrome (OSAS), a common respiratory disorder associated with recurrent hypoxaemia. The prevalence of OSAS is higher in males than females. We tested the hypothesis that sex differences exist in the effects of intermittent hypoxia on upper airway muscle function. Adult Wistar rats were exposed to intermittent hypoxia (IH, 90 s air/90 s N(2); 5% O(2) at nadir) or sham treatment for 8 hours/day for 9 days. Following treatments, animals were killed humanely and isometric contractile properties of the sternohyoid (SH) muscle were examined at 35OC in vitro. Force-frequency relationship was determined at stimulus frequencies ranging 10-100 Hz. In male rats, SH peak force was decreased in IH-treated male rats [22.7 +/- 08. vs. 15.9 +/- 0.9 N/cm(2), sham (n = 8) vs. IH (n = 8), p < 0.001 ANOVA]. Conversely, in female rats, IH treatment had no effect on SH peak force [21.0 +/- 1.2 vs. 19.8 +/- 0.8 N/cm(2), sham (n = 8) vs. IH (n = 8), p > 0.05 ANOVA]. We conclude that IH-induced impairment of pharyngeal dilator muscle performance may contribute to OSAS.


Assuntos
Hipóxia/fisiopatologia , Músculos Faríngeos/fisiopatologia , Caracteres Sexuais , Animais , Feminino , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
10.
Adv Exp Med Biol ; 669: 267-70, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20217363

RESUMO

Chronic intermittent hypoxia (CIH), a feature of obstructive sleep apnoea (OSA) has been shown to have myriad effects on the respiratory control system. The effects on breathing are of great clinical significance for the sleep apnoea patient. We sought to determine the effect of CIH on normoxic ventilation. Both male and female adult Wistar rats were studied due to the evident sex difference in the prevalence of OSA. A role for oxidative stress in respiratory modifications was also explored. Adult male (n = 30) and female (n = 16) rats were exposed to alternating periods of N(2) and O(2) for 90 s each, bringing the ambient oxygen concentration to 5% at nadir (CIH) group. Sham groups were subject to cycles of air/air under identical experimental conditions. A subset of male rats (8 controls, 8 CIH) had free access to water containing 1 mM Tempol (SOD-mimetic) at all times. Treatments were carried out for 8 hours a day for 9 days. Following treatment, normoxic ventilation was assessed by whole body plethysmography in sleeping animals. Baseline normoxic ventilation was increased in both male and female treated rats but this did not achieve statistical significance. However, ventilatory drive (V(T)/Ti) was significantly increased in male rats. Chronic treatment with Tempol abolished this effect. Conversely, CIH had no significant effect on VT/Ti in female rats. Our results indicate subtle effects of intermittent hypoxia on breathing in conscious behaving rats. We speculate the increased ventilatory drive following CIH represents a form a neural plasticity - a ROS dependent phenomenon - with sexual dimorphism.


Assuntos
Hipóxia/fisiopatologia , Plasticidade Neuronal/fisiologia , Respiração , Animais , Comportamento Animal , Materiais Biomiméticos/farmacologia , Óxidos N-Cíclicos/farmacologia , Feminino , Masculino , Plasticidade Neuronal/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Ventilação Pulmonar/efeitos dos fármacos , Ratos , Ratos Wistar , Marcadores de Spin , Superóxido Dismutase/metabolismo , Fatores de Tempo
11.
Adv Exp Med Biol ; 648: 337-44, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19536497

RESUMO

Obstructive sleep apnoea is characterized by chronic intermittent hypoxia (CIH) due to recurrent apnoea. We have developed a rat model of CIH, which shows evidence of impaired respiratory muscle function. In this study, we wished to characterize the ventilatory effects of CIH in conscious male and female animals. Adult male (n=14) and female (n=8) Wistar rats were used. Animals were placed in chambers daily for 8 h with free access to food and water. The gas supply to one half of the chambers alternated between air and nitrogen every 90 s, for 8 h per day, reducing ambient oxygen concentration in the chambers to 5% at the nadir (intermittent hypoxia; n=7 male, n=4 female). Air supplying the other chambers was switched every 90 s to air from a separate source, at the same flow rates, and animals in these chambers served as controls (n=7 male, n=4 female). Ventilatory measurements were made in conscious animals (typically sleeping) after 10 days using whole-body plethysmography. Normoxic ventilation was increased in both male and female CIH-treated rats compared to controls but this did not achieve statistical significance. However, ventilatory drive was increased in CIH-treated rats of both sexes as evidenced by significant increases in mean and peak inspiratory flow. Ventilatory responses to acute hypoxia (F(I)O(2) = 0.10; 6 min) and hyperoxic hypercapnia (F(I)CO(2) = 0.05; 6 min) were unaffected by CIH treatment in male and female rats (P>0.05, ANOVA). We conclude that CIH increases respiratory drive in adult rats. We speculate that this represents a form of neural plasticity that may compensate for respiratory muscle impairment that occurs in this animal model.


Assuntos
Hipóxia/fisiopatologia , Ventilação Pulmonar/fisiologia , Animais , Feminino , Hematócrito , Hipercapnia/fisiopatologia , Masculino , Ratos , Caracteres Sexuais , Fatores de Tempo
13.
Environ Pollut ; 151(1): 79-92, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17524537

RESUMO

Field studies were conducted during 2003 and 2004 from early June to the end of August, at 20 sites of lower or higher elevation within north-central Pennsylvania, using seedlings of black cherry (Prunus serotina, Ehrh.) and ramets of hybrid poplar (Populus maximowiziixtrichocarpa). A linear model was developed to estimate the influence of local environmental conditions on stomatal conductance. The most significant factors explaining stomatal variance were tree species, air temperature, leaf vapor pressure deficit, elevation, and time of day. Overall, environmental factors explained less than 35% of the variation in stomatal conductance. Ozone did not affect gas exchange rates in either poplar or cherry. Ozone-induced foliar injury was positively correlated with cumulative ozone exposures, expressed as SUM40. Overall, the amount of foliar injury was better correlated to a flux-based approach rather than to an exposure-based approach. More severe foliar injuries were observed on plants growing at higher elevations.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Oxidantes Fotoquímicos/toxicidade , Ozônio/metabolismo , Folhas de Planta/metabolismo , Populus/metabolismo , Prunus/metabolismo , Poluentes Atmosféricos/metabolismo , Exposição Ambiental , Monitoramento Ambiental/métodos , Modelos Lineares , Oxidantes Fotoquímicos/metabolismo , Ozônio/toxicidade , Pennsylvania , Estações do Ano , Temperatura
14.
J Mol Biol ; 226(4): 1161-73, 1992 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-1518049

RESUMO

The crystal structure of the dodecanucleotide duplex d(CGCAAATTTGCG)2 has been solved to 2.2 A resolution and refined to an R-factor of 18.1% with the inclusion of 71 water molecules. The structure shows propeller twists of up to -20 degrees for the A.T base-pairs, although there is probably only one (weak) three-centre hydrogen bond in the six base-pair AT narrow minor-groove region. An extensive ribbon of hydration has been located in this groove that has features distinctive from the classic "spine of hydration". Solvation around phosphate groups is described, with several instances of water molecules bridging between phosphates.


Assuntos
DNA/química , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/química , Composição de Bases , Sequência de Bases , Cristalização , Ligação de Hidrogênio , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Molecular , Água/química , Difração de Raios X
15.
J Mol Biol ; 238(5): 852-3, 1994 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-8182754

RESUMO

An FMN-dependent nitroreductase enzyme isolated from Escherichia coli B has been crystallized in a form suitable for high-resolution structural analysis. The crystals belong to the tetragonal space group P4(1)2(1)2 or its enantiomorph P4(3)2(1)2 with cell parameters a = b = 57.74 A, c = 275.51 A and two molecules per asymmetric unit. Diffraction extends to beyond 1.9 A.


Assuntos
Escherichia coli/enzimologia , Nitrorredutases/química , Cristalização , Cristalografia por Raios X , Mononucleotídeo de Flavina , Estrutura Molecular
16.
J Mol Biol ; 205(3): 623-4, 1989 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-2494346

RESUMO

An NAD(P)H quinone reductase isolated from Walker rat 256 carcinoma cells has been crystallized in a form suitable for high-resolution structural analysis. The crystals belong to orthorhombic space group P2(1)2(1)2(1) with cell parameters a = 168.15 A, b = 105.09 A and c = 67.38 A and contain four monomeric or two dimeric enzyme molecules per asymmetric unit. Diffraction extends beyond 2.3 A resolution.


Assuntos
Quinona Redutases , Animais , Linhagem Celular , NAD(P)H Desidrogenase (Quinona) , Ratos , Células Tumorais Cultivadas/enzimologia , Difração de Raios X
17.
Environ Pollut ; 136(1): 33-45, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15809106

RESUMO

Seasonal trends in leaf gas exchange and ozone-induced visible foliar injury were investigated for three ozone sensitive woody plant species. Seedlings of Populus nigra L., Viburnum lantana L., and Fraxinus excelsior L. were grown in charcoal-filtered chambers, non-filtered chambers and open plots. Injury assessments and leaf gas exchange measurements were conducted from June to October during 2002. All species developed typical ozone-induced foliar injury. For plants exposed to non-filtered air as compared to the charcoal-filtered air, mean net photosynthesis was reduced by 25%, 21%, and 18% and mean stomatal conductance was reduced by 25%, 16%, and 8% for P. nigra, V. lantana, and F. excelsior, respectively. The timing and severity of the reductions in leaf gas exchange were species specific and corresponded to the onset of visible foliar injury.


Assuntos
Poluentes Atmosféricos/toxicidade , Gases/metabolismo , Oxidantes Fotoquímicos/toxicidade , Ozônio/toxicidade , Folhas de Planta/efeitos dos fármacos , Estações do Ano , Fraxinus/efeitos dos fármacos , Fraxinus/metabolismo , Mimosa/efeitos dos fármacos , Mimosa/metabolismo , Fotossíntese/efeitos dos fármacos , Populus/efeitos dos fármacos , Populus/metabolismo , Especificidade da Espécie , Tempo (Meteorologia)
18.
Environ Pollut ; 133(3): 553-67, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15519730

RESUMO

The crowns of five canopy dominant black cherry (Prunus serotina Ehrh.), five white ash (Fraxinus americana L.), and six red maple (Acer rubrum L.) trees on naturally differing environmental conditions were accessed with scaffold towers within a mixed hardwood forest stand in central Pennsylvania. Ambient ozone concentrations, meteorological parameters, leaf gas exchange and leaf water potential were measured at the sites during the growing seasons of 1998 and 1999. Visible ozone-induced foliar injury was assessed on leaves within the upper and lower crown branches of each tree. Ambient ozone exposures were sufficient to induce typical symptoms on cherry (0-5% total affected leaf area, LAA), whereas foliar injury was not observed on ash or maple. There was a positive correlation between increasing cumulative ozone uptake (U) and increasing percent of LAA for cherry grown under drier site conditions. The lower crown leaves of cherry showed more severe foliar injury than the upper crown leaves. No significant differences in predawn leaf water potential (psi(L)) were detected for all three species indicating no differing soil moisture conditions across the sites. Significant variation in stomatal conductance for water vapor (g(wv)) was found among species, soil moisture, time of day and sample date. When comparing cumulative ozone uptake and decreased photosynthetic activity (P(n)), red maple was the only species to show higher gas exchange under mesic vs. drier soil conditions (P < 0.05). The inconsistent differences in gas exchange response within the same crowns of ash and the uncoupling relationship between g(wv) and P(n) demonstrate the strong influence of heterogeneous environmental conditions within forest canopies.


Assuntos
Acer/química , Fraxinus/química , Oxidantes Fotoquímicos/toxicidade , Ozônio/toxicidade , Prunus/química , Árvores/química , Acer/fisiologia , Exposição Ambiental/efeitos adversos , Monitoramento Ambiental/métodos , Fraxinus/fisiologia , Pennsylvania , Fotossíntese/fisiologia , Folhas de Planta/química , Folhas de Planta/fisiologia , Prunus/fisiologia , Estações do Ano , Solo , Temperatura , Árvores/fisiologia
19.
FEBS Lett ; 262(1): 127-30, 1990 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-2108052

RESUMO

The intrinsic fluorescence properties of the oncogene protein p21N-ras,p21H-ras and one of its transforming mutants, p21N-ras (Val12), have been investigated. A mutant containing a single tryptophan at position 28 in p21H-ras (Trp28) has been specifically engineered to provide a probe of protein conformation on nucleotide binding. The proteins produced essentially similar circular dichroism spectra typical of alpha/beta proteins. A decrease in the intensity of the fluorescence emission spectrum due to tyrosine occurred on GDP/GTP nucleotide exchange in the native and mutant proteins. Selective excitation of the single tryptophan in p21 produced a decrease in fluorescence intensity which was accompanied by a blue shift in the wavelength of maximum emission on nucleotide exchange. A reduction in the residual Mg2+ ion concentration enhanced this effect.


Assuntos
Nucleotídeos de Guanina/metabolismo , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Proteína Oncogênica p21(ras) , Dicroísmo Circular , Ácido Edético/farmacologia , Fluorescência , Magnésio/farmacologia , Conformação Proteica
20.
J Med Chem ; 43(20): 3624-31, 2000 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-11020276

RESUMO

The FMN-dependent flavoprotein nitroreductase from Escherichia coli B (NTR) is used in cancer chemotherapy to activate a range of prodrugs. The crystal structure of this enzyme has been determined, using molecular replacement methods and refined at 2.06 A resolution. The recombinant 24-kDa enzyme was crystallized in the tetragonal space group P4(1)2(1)2, with unit cell dimensions of a = b = 57.74 A and c = 275.51 A and two molecules in the asymmetric unit. The structure has a final R factor of 20.3% (R(free) = 26.7%), for all data between the resolution ranges of 10-2.06 A, and includes 4453 protein atoms, 230 water molecules, and 2 flavin mononucleotide (FMN) molecules. The functional unit is a homodimer, which forms the asymmetric unit in the crystal structure. The tertiary structures of these two monomers and their subunit interactions are nearly identical. The molecular replacement search model, the crystal structure of the major NAD(P)H:FMN oxidoreductase of Vibrio fisheri (FRase 1), was selected on the basis of its high sequence identity to that of NTR. The final superposition of these two enzymes revealed a very similar overall fold, with variation in the structures focused around surface loops and helices near the FMN cofactor. Helix G is implicated in substrate specificity and is better resolved in the present NTR structure than in the previously reported FRase 1 structure. The FMN binding pocket is also well-resolved, showing the presence of two channels leading into the active site. The amino acid side chains and main chain atoms interacting with the FMN are well-ordered. The structure of the substrate binding pocket has been used to examine substrate specificity and enzyme kinetics for prodrugs used in antibody-directed enzyme prodrug therapy (ADEPT) and gene-directed enzyme prodrug therapy (GDEPT).


Assuntos
Proteínas de Escherichia coli , Escherichia coli/química , Nitrorredutases/química , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Modelos Moleculares , Dados de Sequência Molecular , Pró-Fármacos/química , Estrutura Terciária de Proteína
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