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1.
Nurse Educ Today ; 34(6): 934-9, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24225346

RESUMO

BACKGROUND: Conflict management is an essential skill that nursing students need to master as conflict is unavoidable in clinical settings. Examining nursing students' conflict management styles and the associating factors can inform nurse educators on how to equip nursing students for effective conflict management. OBJECTIVES: This study aimed at examining undergraduate nursing students conflict management styles in managing conflict with their supervisors in clinical placement. The associations of emotional intelligence and implicit theories of personality with conflict management styles were also investigated. DESIGN: This is a cross-sectional quantitative survey. SETTING: This study took place at a nursing school at a university in Hong Kong. PARTICIPANTS: 568 undergraduate nursing students participated in the study. METHODS: Students completed a questionnaire which consisted of demographics, Measure of Implicit Theories of Personality, The Schutte Emotional Intelligence Scale (SEIS) and The Rahim Organizational Conflict Inventory-II (ROCI-II) and received a HKD 20 book coupon as compensation. The data were analyzed by descriptive statistics, reliability analyses, t-tests, correlational and linear regression analyses. RESULTS: For managing conflict with clinical supervisors, students used obliging and integrating most frequently whereas used dominating least. Emotional intelligence was a significant predictor of all five conflict management styles. The higher the emotional intelligence, the more students used integrating, obliging, compromising and dominating. The lower the emotional intelligence, the more students used avoiding. There was a significant association between implicit theories of personality and compromising. The less malleable students perceived personality to be, the more they used compromising. CONCLUSIONS: Emotional intelligence was significantly associated with all five conflict management styles while implicit theories of personality were significantly associated with compromising style only. Efforts of nurse educators to enhance students' conflict management skills and emotional intelligence to face conflicts in clinical settings are discussed.


Assuntos
Conflito Psicológico , Inteligência Emocional , Personalidade , Estudantes de Enfermagem/psicologia , Estudos Transversais , Docentes de Enfermagem , Feminino , Hong Kong , Humanos , Relações Interprofissionais , Masculino , Reprodutibilidade dos Testes , Inquéritos e Questionários
2.
Analyst ; 136(11): 2270-6, 2011 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-21509366

RESUMO

For sectioned biologic tissues, atomic force microscopy (AFM) topographic images alone hardly provide adequate information leading to revealing biological structures. We demonstrate that phase imaging in amplitude-modulation AFM is a powerful tool in mapping structures present on the surface of unfixed rat brains sections. The contrast in phase images is originated from the difference in mechanical properties between biological structures. Visualization of the native state of biological structures by way of their mechanical properties provides a complementary technique to more traditional imaging techniques such as optical and electron microscopy.


Assuntos
Encéfalo/ultraestrutura , Microscopia de Força Atômica/métodos , Animais , Encéfalo/anatomia & histologia , Lipídeos/análise , Masculino , Microscopia de Força Atômica/instrumentação , Ratos , Ratos Long-Evans , Espectrometria de Massa de Íon Secundário
3.
J Chem Phys ; 134(7): 074704, 2011 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-21341866

RESUMO

A low-energy hydrogen bombardment method, without using any chemical additives, has been designed for fine tuning both physical and chemical properties of molecular thin films through selectively cleaving C-H bonds and keeping other bonds intact. In the hydrogen bombardment process, carbon radicals are generated during collisions between C-H bonds and hydrogen molecules carrying ∼10 eV kinetic energy. These carbon radicals induce cross-linking of neighboring molecular chains. In this work, we focus on the effect of hydrogen bombardment on dotriacontane (C(32)H(66)) thin films as growing on native SiO(2) surfaces. After the hydrogen bombardment, XPS results indirectly explain that cross-linking has occurred among C(32)H(66) molecules, where the major chemical elements have been preserved even though the bombarded thin film is washed by organic solution such as hexane. AFM results show the height of the perpendicular phase in the thin film decreases due to the bombardment. Intriguingly, Young's modulus of the bombarded thin films can be increased up to ∼6.5 GPa, about five times of elasticity of the virgin films. The surface roughness of the thin films can be kept as smooth as the virgin film surface after thorough bombardment. Therefore, the hydrogen bombardment method shows a great potential in the modification of morphological, mechanical, and tribological properties of organic thin films for a broad range of applications, especially in an aggressive environment.


Assuntos
Diacetil/química , Hidrogênio/química , Alcanos/química , Fenômenos Mecânicos , Microscopia de Força Atômica , Espectroscopia Fotoeletrônica , Dióxido de Silício/química , Fatores de Tempo
4.
J Phys Chem B ; 112(47): 14851-6, 2008 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-18973368

RESUMO

The mechanism for the diffusion of vinyl bromide (VB) through the nonporous van der Waals organic solid of p-tert-butylcalix[4]arene (tBC) is examined by molecular mechanics calculations. In a "squeeze" mechanism, a VB molecule passes through the interstitial space in the rim regions of tBC bowls, after the partial filling of nearby inclusion sites, and couples with the both the rotation of butyl groups and the translational sliding of the bilayers, until it encounters and falls into a empty site. In a "relay" mechanism, translational sliding shifts the skew angle between two tBC bowls and makes it possible to pass a VB from one bowl to another and throughout the solid. The barrier for the "relay" mechanism is 4 kcal/mol lower than the "squeeze" mechanism, although the "squeeze" mechanism is favored by entropy. The "squeeze" mechanism should be more sensitive to the size of the diffusion molecule and should leave residue VB molecules in the interstitial regions. In contrast, the VB molecule hops from one site to another in the "relay" mechanism, and the kinetically limiting step is the translational sliding of the bilayer. Such contrasts should help resolve the relative importance of the two mechanisms in future kinetic studies.

5.
Curr Pharm Des ; 14(8): 794-802, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18393881

RESUMO

Many currently available drugs show unfavourable physicochemical properties for delivery into or across the skin and temporary chemical modulation of the penetrant is one option to achieve improved delivery properties. Pro-drugs are chemical derivatives of an active drug which is covalently bonded to an inactive pro-moiety in order to overcome pharmaceutical and pharmacokinetic barriers. A pro-drug relies upon conversion within the body to release the parent active drug (and pro-moiety) to elicit its pharmacological effect. The main drawback of this approach is that the pro-moiety is essentially an unwanted ballast which, when released, can lead to adverse effects. The term 'co-drug' refers to two or more therapeutic compounds active against the same disease bonded via a covalent chemical linkage and it is this approach which is reviewed for the first time in the current article. For topically applied co-drugs, each moiety is liberated in situ, either chemically or enzymatically, once the stratum corneum barrier has been overcome by the co-drug. Advantages include synergistic modulation of the disease process, enhancement of drug delivery and pharmacokinetic properties and the potential to enhance stability by masking of labile functional groups. The amount of published work on co-drugs is limited but the available data suggest the co-drug concept could provide a significant therapeutic improvement in dermatological diseases. However, the applicability of the co-drug approach is subject to strict limitations pertaining mainly to the availability of compatible moieties and physicochemical properties of the overall molecule.


Assuntos
Fármacos Dermatológicos , Sistemas de Liberação de Medicamentos , Pró-Fármacos , Absorção Cutânea/efeitos dos fármacos , Administração Tópica , Fármacos Dermatológicos/administração & dosagem , Fármacos Dermatológicos/metabolismo , Fármacos Dermatológicos/uso terapêutico , Combinação de Medicamentos , Desenho de Fármacos , Sinergismo Farmacológico , Olho/metabolismo , Humanos , Fenômenos Fisiológicos Oculares , Soluções Oftálmicas , Permeabilidade , Pró-Fármacos/administração & dosagem , Pró-Fármacos/metabolismo , Pró-Fármacos/uso terapêutico , Dermatopatias/tratamento farmacológico
6.
Langmuir ; 24(6): 2884-91, 2008 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-18237199

RESUMO

Electrokinetic phenomena play a major role in microfluidic systems, and such a role becomes even more significant in nanofluidic systems due to the increase of the surface-to-volume ratio. Description of the electric double layer (EDL) at a solid-liquid interface is the key to understand and utilize electrokinetic phenomena. However, the traditional Gouy-Chapman (GC) theory for the EDL, which has been successfully used in many microfluidic applications, does not include some important characteristics such as ion size and image effect. These characteristics are indeed important in nanofluidics. This paper explores the impacts of ion size and the image effect on micro- and nanoscale electrokinetic flows. An advanced theory, the modified Poisson-Boltzmann (MPB) theory proposed by Outhwaite and his co-workers,1,26 is adopted to describe the EDL. Electrokinetic flows in micro- and nanochannels are reinvestigated. The results show that ion size has significant effects on electrokinetic flows in nanosystems in terms of both the flow field and the streaming potential, while the image effect only significantly affects the streaming potential.


Assuntos
Técnicas Analíticas Microfluídicas/métodos , Eletroquímica , Íons/química , Cinética , Pressão
7.
Oncogene ; 26(41): 6050-60, 2007 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-17369842

RESUMO

p16(INK4A) (p16) has been suggested to be an early biomarker for the detection of cervical cancer. However, its functional role in cervical cancer is not well characterized. In this study, we reported the consistent and significant upregulation of p16 in cervical cancer tissues when compared to both matched non-tumourous tissues of the same patient and normal cervical tissues from non-cancer patients. We have employed p16 small interfering RNA (siRNA) to dissect the role of p16 in cervical carcinogenesis. Although the silencing of p16 was accompanied by the upregulation of p53, p21 and RB in the p16 siRNA-transfected cells, no significant effect on cell cycle progression was observed. When the p16 siRNA-silenced cells were subjected to DNA damage stress including ultraviolet-irradiation and cisplatin treatments, a significantly higher percentage of apoptotic cells could be observed in the p16-siRNA silenced cells compared to control siRNA-treated cells. Moreover, induction of apoptosis was associated with the activation of p53 through phosphorylation, and this process, when studied by gene profiling experiments, involved both the intrinsic and extrinsic apoptotic pathways. The observation that silencing of p16 expression augments DNA damage-induced apoptosis in cervical cancer cells offers alternative strategies for anti-cancer therapies for human cervical cancer.


Assuntos
Dano ao DNA , Inativação Gênica , Genes p16 , Neoplasias do Colo do Útero/patologia , Apoptose , Células Cultivadas , Colo do Útero/citologia , Colo do Útero/patologia , DNA Complementar/genética , Feminino , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , RNA Interferente Pequeno/genética , Transfecção , Células Tumorais Cultivadas , Neoplasias do Colo do Útero/genética
8.
J Phys Chem B ; 110(42): 21073-6, 2006 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-17048928

RESUMO

Thermal stability of well-crystallized cubic boron nitride (cBN) films grown by chemical vapor deposition has been investigated by cathodoluminescence (CL), Raman spectroscopy, and scanning electron microscopy (SEM) with the cBN films annealed at various temperatures up to 1,300 degrees C. The crystallinity of the cBN films further improves, as indicated by a reduction of the relevant Raman line width, when the annealing temperature exceeds 1,100 degrees C. Structural damage or amorphization was observed on the grain boundaries of the cBN crystals when annealing temperature reaches 1,300 degrees C. The CL spectra are found to be unchanged up to 1,100 degrees C after annealing at 500 degrees C, showing the stability of the cBN films in electronic properties up to this temperature. New features were observed in the CL spectra when annealing temperature reaches 1,200-1,300 degrees C.

9.
Phys Rev Lett ; 96(7): 079801; author reply 079802, 2006 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-16606153
10.
Phys Rev Lett ; 94(1): 016101, 2005 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-15698099

RESUMO

It has long been understood that a precursor mediated chemisorption is a significant part of the dynamics for the adsorption of O(2) on Si(100), which is a much studied model system of surface reaction with considerable technological relevance. However, theoretical studies on the interaction between O(2) and Si(100) have been focused on the excited singlet state of O2 and unable to explain the observations in surface scattering experiments. We demonstrate by first principles calculations that such a focus is misplaced. In reality, triplet O(2) can also react with Si(100), after overcoming small barriers, and its reaction paths provide a full account for experiments. Our results highlight the important role played by triplet O(2) in surface oxidation.

11.
Br J Cancer ; 86(2): 274-81, 2002 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-11870519

RESUMO

To identify novel cellular genes that could potentially act as predictive molecular markers for human cervical cancer, we employed RT--PCR differential display, reverse Northern and Northern blot analysis to compare the gene expression profiles between squamous cell carcinoma biopsies and adjacent histo-pathological normal epithelium tissues. Twenty-eight cDNA clones were isolated that were demonstrated to be consistently over-expressed in squamous cell cervical cancer biopsies of FIGO stages 1B to 3B. Most importantly, it was observed that, in addition to their over-expression in cancer lesions, some of these genes are upregulated in the presumably histo-pathological normal adjacent tissues. Of particular interest is clone G30CC that has been identified to be the gene that encodes S12 ribosomal protein. When employed for RNA--RNA in situ hybridization experiments, expression of G30CC could be detected in the immature basal epithelial cells of histo-pathological normal tissues collected from cervical cancer patients of early FIGO stages. In comparison, the expression of G30CC was not detected in cervical tissues collected from patients admitted for surgery of non-malignant conditions. These results allow the distinct possibility of employing the ribosomal protein S12 gene as an early molecular diagnostic identifier for the screening of human cervical cancer and a potential target employed for cancer gene therapy trials.


Assuntos
Biomarcadores Tumorais/análise , Carcinoma de Células Escamosas/diagnóstico , Regulação Neoplásica da Expressão Gênica , Proteínas Ribossômicas/biossíntese , Neoplasias do Colo do Útero/diagnóstico , Northern Blotting , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Primers do DNA , DNA Complementar , Feminino , Humanos , Hibridização In Situ , Estadiamento de Neoplasias , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas Ribossômicas/análise , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia
12.
Med J Malaysia ; 56(1): 10-7, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11503285

RESUMO

INTRODUCTION: The flow-volume curves of patients with obstructive sleep apnoea (OSA) obtained during the awake state are frequently abnormal. OBJECTIVE: To determine 1) the relationship between the awake respiratory function and the severity of sleep-disordered breathing in a group of Malaysian patients with the OSA syndrome and 2) the frequency of flow-volume curve abnormality in these patients. MATERIALS AND METHODS: A retrospective analysis of the data from respiratory function tests during wakefulness and nocturnal polysomnography was performed on 48 patients with OSA. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) and the lowest oxygen saturation during sleep (SpO2nadir). RESULTS: AHI had a significant relationship with alveolar-arterial oxygen gradient (r = 0.34, p = 0.046) and SpO2nadir (r = -0.49, p < 0.001) but not with any anthropometric parameter or the other awake respiratory function variables measured. SpO2nadir had a significant relationship with body mass index (r = -0.54, p < 0.001), neck circumference (r = -0.39, p = 0.013), awake room air PaO2 (r = 0.61, p < 0.001), alveolar-arterial oxygen gradient (r = -0.41, p = 0.015) and baseline supine SpO2 (r = 0.53, p < 0.001). There was no correlation between SpO2nadir and any spirometric or static lung volume parameters. The maximum inspiratory and maximum expiratory flow-volume curves of 26 patients (54%) showed a ratio of forced expiratory flow to forced inspiratory flow at mid-vital capacity (FEF50/FIF50) greater than one. In addition, flow oscillations (the "sawtooth" sign) were noted in the inspiratory and/or expiratory flow-volume curves of 21 patients (44%), 9 of whom did not have an FEF50/FIF50 > 1. Altogether, the maximum flow-volume curves during wakefulness of 35 (73%) of the 48 patients showed variable upper airway obstruction and/or flow oscillations. However, the presence of these two upper airway abnormalities, either occurring alone or together did not have an effect on the severity of OSA as measured by the AHI or SpO2nadir. CONCLUSIONS: Abnormalities of the flow-volume loop consistent with inspiratory flow limitation and/or upper airway instability during wakefulness are common in patients with the OSA syndrome. The degree of oxygen desaturation during sleep in these patients is related to their awake oxygenation status.


Assuntos
Respiração , Apneia Obstrutiva do Sono/fisiopatologia , Adulto , Idoso , Índice de Massa Corporal , Humanos , Pessoa de Meia-Idade , Pescoço/anatomia & histologia , Estudos Retrospectivos
13.
Artigo em Inglês | MEDLINE | ID: mdl-11282316

RESUMO

Military operations in tropical environments have imposed a significant challenge to the Australian Defence Forces (ADF). The hot and humid conditions are known to cause debilitating effects on soldiers deployed to northern regions of Australia, with the consequence that the effectiveness and efficiency of operations are severely compromised. While the adverse effects of thermal stress on soldiers' physiological capability are well established, this has not been confirmed for cognitive performance. A select range of psychometric tests were administered and functional brain electrical activity imaging was performed to investigate the impact of thermal stress on cognitive performance. The brain electrical activity of subjects was measured while undertaking a range of cognitive tasks. Steady State Probe Topography (SSPT), a novel brain imaging technology, was employed to monitor the changes in regional brain activity and neural processing speed of subjects under thermal stress. The psychometric test batteries included the following tasks; Rey Auditory Verbal Learning Test; Inspection Time; Digit Span test; a spatial working memory task; and the AX-continuous performance task. These tasks measure a range of cognitive processes including attention, memory, verbal learning, information processing and concentration. The functional brain imaging provided topographical information, which showed changes in electrical activity in response to thermal stress during cognitive performance. These changes in brain electrical activity and neural speed induced by thermal stress may help to identify the type of cognitive functions that are likely to be impaired under operational conditions. Results indicated that subjects experienced increasing cardiovascular strain through thermally neutral to thermally straining conditions. The results from the psychometric test battery showed some promising effects given the small sample size including deficits in working memory, in information retention and in information processing. There was also marked differences in the electrical responses of the brain when subjects were thermally strained. The Steady-State Visual Evoked Potential recordings showed an increase in amplitude and a decrease in latency, suggesting an increase in the utilisation of neural resources or effort by subjects to maintain the same level of performance as under thermally neutral conditions. The data are suggestive of the high sensitivity of brain imaging techniques with high temporal resolution to identify important decrements in cognitive performance in hostile environments.


Assuntos
Encéfalo/fisiologia , Cognição/fisiologia , Temperatura Alta , Psicometria/métodos , Adulto , Regulação da Temperatura Corporal , Eletroencefalografia/métodos , Potenciais Evocados Visuais , Frequência Cardíaca , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Memória de Curto Prazo
14.
Mil Med ; 165(12): 961-6, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11149070

RESUMO

The physiological and cognitive performance of acclimatized soldiers undertaking routine patrol and reconnaissance activities in the tropics was investigated. Data were obtained during a patrol and a reconnaissance exercise followed by a short assault. Ambient conditions were characterized by temperatures of 30 to 33 degrees C, low humidity (52-59%), and moderate to high solar radiation. Maximum metabolic rates during patrol were high, although the equipment carried was modest and the terrain was not severe. Rectal temperatures peaked at 38.2 and 38.4 degrees C for patrol and assault activities, respectively; peak heart rates were 160 beats min-1 for each activity. Sweat rates of approximately 9 and 14 g kg-1 body weight h-1 were recorded for patrol and assault activities, respectively. The soldiers maintained adequate hydration levels and displayed no evidence of deterioration in cognitive performance. The data show that routine operational activities in tropical conditions induced physiological strain in acclimatized soldiers. However, this strain was not maintained at hazardous levels for lengthy periods.


Assuntos
Cognição/fisiologia , Transtornos de Estresse por Calor/etiologia , Militares/psicologia , Desempenho Psicomotor/fisiologia , Clima Tropical/efeitos adversos , Aclimatação , Adulto , Temperatura Corporal , Peso Corporal , Metabolismo Energético , Frequência Cardíaca , Transtornos de Estresse por Calor/diagnóstico , Transtornos de Estresse por Calor/fisiopatologia , Transtornos de Estresse por Calor/psicologia , Humanos , Masculino , Northern Territory , Equilíbrio Hidroeletrolítico , Suporte de Carga
15.
Changgeng Yi Xue Za Zhi ; 22(3): 439-44, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10584416

RESUMO

BACKGROUND: Backache is a common postoperative complaint after lumbar epidural anesthesia. Our study was aimed to compare the effect of the local addition of ketoprofen on the incidence of postepidural backache after nonobstetric surgery. METHODS: One thousand patients scheduled for hemorrhoidectomy were randomly given 4 ml of 1% lidocaine with ketoprofen 1:400 (ketoprofen group) or without ketoprofen (control group) for local skin infiltration prior to epidural needle placement. Each of them received a single epidural injection of 25 ml 2% lidocaine with epinephrine 1:200000, and was interviewed 24, 48, and 72 hours postoperatively using a standard visual analog scale (VAS) for evaluation of postepidural backache. RESULTS: The incidence of postepidural backache in the ketoprofen-group patients for the 3 days was 9.8%, 4.6%, and 1.8%, all rates which were significantly less than those observed in the control-group patients (22.8%, 17.4%, and 9.2%, p < 0.001). There was also a significant association between postepidural backache and multiple attempts at epidural needle insertion. CONCLUSION: In summary, the local addition of ketoprofen reduced the incidence and severity of postepidural backache.


Assuntos
Anestesia Epidural/efeitos adversos , Anti-Inflamatórios não Esteroides/administração & dosagem , Dor nas Costas/prevenção & controle , Cetoprofeno/administração & dosagem , Adulto , Idoso , Dor nas Costas/epidemiologia , Feminino , Hemorroidas/cirurgia , Humanos , Incidência , Lidocaína/administração & dosagem , Masculino , Pessoa de Meia-Idade
16.
Eur J Pharmacol ; 365(2-3): 241-51, 1999 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-9988108

RESUMO

The vasorelaxant actions of adenosine 5'-triphosphate (ATP)-dependent K+ channel openers and sodium nitroprusside in isolated thoracic aorta and pulmonary artery of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats (14-18 weeks old) were investigated. Cumulative addition of sodium nitroprusside and different ATP-dependent K+ channel openers (pinacidil, cromakalim, nicorandil, 2-(2"(1",3"-dioxolone)-2-methyl-4-(2'-oxo-1'-pyrrolidinyl)-6-nitro -2H-1-benzopyren (KR-30450) and aprikalim) to these preparations caused a concentration-dependent relaxation of noradrenaline-pre-contracted aorta and pulmonary artery from both strains. The relative order of relaxation potency, estimated by comparing the IC50, was sodium nitroprusside > KR-30450 > aprikalim > or = cromakalim > pinacidil > nicorandil in pulmonary artery and aorta from both strains. At high concentrations (> or =1 microM), cromakalim, aprikalim and KR-30450 produced a greater percentage relaxation in SHR aorta than in WKY aorta. However, there was no apparent difference between SHR and WKY in the relaxation response to all drugs tested on the pulmonary artery. The effects of cromakalim, aprikalim, pinacidil and KR-30450 observed in aorta and pulmonary artery were significantly attenuated by 3 microM glibenclamide. 6-Anilino-5,8-quinolinequinone (LY 83583, 1 microM), a soluble guanylate cyclase inhibitor, abolished the vasorelaxant effects of nicorandil and sodium nitroprusside. In conclusion, sodium nitroprusside and ATP-dependent K+ channel openers cause relaxation of noradrenaline-pre-contracted aorta and pulmonary artery from both strains. However, all the drugs tested failed to cause selective relaxation of the pulmonary artery relative to the thoracic aorta.


Assuntos
Aorta Torácica/efeitos dos fármacos , Hipertensão/fisiopatologia , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Canais de Potássio/agonistas , Artéria Pulmonar/efeitos dos fármacos , Vasodilatadores/farmacologia , Trifosfato de Adenosina/farmacologia , Aminoquinolinas/farmacologia , Animais , Apamina/farmacologia , Benzopiranos/farmacologia , Charibdotoxina/farmacologia , Cromakalim/farmacologia , Relação Dose-Resposta a Droga , Glibureto/farmacologia , Técnicas In Vitro , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Nicorandil/farmacologia , Nitroprussiato/farmacologia , Norepinefrina/farmacologia , Picolinas/farmacologia , Pinacidil/farmacologia , Potássio/farmacologia , Piranos/farmacologia , Pirrolidinonas/farmacologia , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY
17.
J Appl Toxicol ; 16(5): 423-30, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8889794

RESUMO

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.


Assuntos
Substâncias para a Guerra Química/toxicidade , Inibidores da Colinesterase/toxicidade , Reativadores da Colinesterase/farmacologia , Antagonistas Muscarínicos/farmacologia , Soman/toxicidade , Acetilcolinesterase/sangue , Animais , Atropina/administração & dosagem , Atropina/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Temperatura Corporal/efeitos dos fármacos , Butirilcolinesterase/sangue , Reativadores da Colinesterase/administração & dosagem , Sinergismo Farmacológico , Cromatografia Gasosa-Espectrometria de Massas , Glicopirrolato/administração & dosagem , Glicopirrolato/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Injeções Intravenosas , Masculino , Antagonistas Muscarínicos/administração & dosagem , Oximas , Intoxicação/mortalidade , Compostos de Piridínio/farmacologia , Ratos , Ratos Sprague-Dawley , Respiração/efeitos dos fármacos , Tacrina/administração & dosagem , Tacrina/farmacologia
18.
Am J Surg ; 171(5): 464-6, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8651385

RESUMO

BACKGROUND: We conducted this animal study to investigate the cardiopulmonary effects of carbon dioxide pneumothorax during laparoscopic surgery and determine what intervention, if any, is necessary for this phenomenon. METHODS: A swine animal model was used (n = 8). Animals were anesthetized and underwent peritoneal insufflation with carbon dioxide. A laceration was created in the left diaphragm. pO2, pCO2, oxygen saturation, peak inspiratory pressure (PIP), systolic blood pressure, and heart rate were measured and subjected to statistical analysis. RESULTS: Significant changes were noted in the pO2, O2 saturation, pCO2, and PIP upon creation of the pneumothorax. Trends were also noted in the heart rate and the systolic blood pressure. The physiologic changes could be corrected by noninvasive means and without terminating the procedure. CONCLUSIONS: Carbon dioxide pneumothorax produces reproducible cardiopulmonary changes in laparoscopic surgery. These changes are easily monitored and the resulting cardiopulmonary changes can be treated without invasive means.


Assuntos
Laparoscopia/efeitos adversos , Pneumotórax/etiologia , Pneumotórax/fisiopatologia , Respiração , Animais , Dióxido de Carbono/sangue , Modelos Animais de Doenças , Ventilação Pulmonar , Suínos
19.
Gen Pharmacol ; 24(6): 1513-9, 1993 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8112529

RESUMO

1. The negative inotropic effects of soman have been reported previously. It was suggested that the depression in atrial force of contraction was a consequence of continuous muscarinic receptor activation by excessive acetylcholine (ACh) accumulation and also possibly through direct interactions at the receptor-associated K+ channels by organophosphate (OP). 2. In this study, the protective effects of tacrine (THA), an antimuscarinic as well as a K+ channel blocker, against soman in guinea-pig atrium were investigated. 3. It was found that tacrine could antagonize the negative inotropic effects of soman. This antagonism occurred in a concentration dependent manner, with effective concentrations (ECs) for tacrine ranging from 1.7 to 12.1 microM when the atrium was equilibrated with 0.05-10 microM soman. 4. Inclusion of an oxime HI-6 (100 microM) in the regimen improved the efficacy of tacrine against soman (1 microM) by 16.1 fold. 5. Addition of a potent antimuscarinic, either atropine or glycopyrrolate with tacrine also improved tacrine's efficacy against soman significantly. 6. Atropine, at equivalent concentration, appeared to be the most effective of the three. At 0.1 microM concentration, atropine was 4.25 and 3.47 times more potent than HI-6 and glycopyrrolate respectively in enhancing THA efficacy. 7. Our results suggested that the immediate suppression of the muscarinic manifestations and the reactivation of the enzyme acetylcholinesterase for the removal of excess ACh are both critical in maintaining the mechanical functions of a heart during acute OP poisoning. The blockade of K+ channels by tacrine may also contribute to countering the depressant effects of soman.


Assuntos
Contração Miocárdica/efeitos dos fármacos , Soman/antagonistas & inibidores , Tacrina/farmacologia , Animais , Atropina/farmacologia , Reativadores da Colinesterase/farmacologia , Feminino , Glicopirrolato/farmacologia , Cobaias , Átrios do Coração/efeitos dos fármacos , Técnicas In Vitro , Masculino , Oximas , Parassimpatolíticos/farmacologia , Compostos de Piridínio/farmacologia , Soman/toxicidade , Tacrina/análogos & derivados
20.
Pharmacology ; 47(4): 223-9, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8234410

RESUMO

Tacrine (THA) selectively modulates binding of M1 ligands in an allosteric fashion causing positive cooperativity. The binding affinity of THA to M1 and M2 cholinoceptors is similar. It is therefore proposed that the allosteric selectivity of THA is a function of the binding site and not of THA itself. Its interaction of M1 and M2 cholinoceptors was examined in guinea pig brain homogenates using the selective M1 and M2 antagonists [3H]-pirenzepine ([3H]PZ) and [3H]AF-DX 384. The dissociation constants were 0.36 nmol/l for the M1 receptor and 0.23 nmol/l for the M2 receptor. We also compared the binding of THA and methoctramine (MTA) at M2 receptors. Tacrine displayed similar binding affinity for both M1 and M2 receptor subtypes. MTA was 100 times more potent an inhibitor of [3H]AF-DX 384 binding at M2 receptors than THA. In addition, THA was found to slow the dissociation of [3H]PZ from the M1 receptor. In contrast, the dissociation of [3H]AF-DX 384 from M2 receptor subtypes was unaffected. We conclude that THA acts as an agonist at M1 cholinoceptors because it slowed the dissociation of [3H]PZ. At M2 cholinoceptors its nature is that of an antagonist because it had no effect on [3H]AF-DX 384 dissociation.


Assuntos
Encéfalo/metabolismo , Receptores Colinérgicos/metabolismo , Tacrina/metabolismo , Animais , Sítios de Ligação , Encéfalo/efeitos dos fármacos , Diaminas/metabolismo , Diaminas/farmacologia , Interações Medicamentosas , Feminino , Cobaias , Parassimpatolíticos/metabolismo , Parassimpatolíticos/farmacologia , Pirenzepina/análogos & derivados , Pirenzepina/metabolismo , Pirenzepina/farmacologia , Receptores Colinérgicos/efeitos dos fármacos , Tacrina/farmacologia
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