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1.
J Stud Int Educ ; 27(1): 3-20, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36744242

RESUMO

This study examines how the COVID-19 pandemic has impacted the academic experience at international branch campuses (IBCs) and has changed the relationship between the IBC and the home campus. Semi-structured interviews with 26 leaders, academic staff, and students at seven IBCs in Malaysia revealed that the COVID-19 pandemic has changed the experience at IBCs in unique ways, including collaboration and communication with the home campus; increasing campus-specific resources for student wellbeing; and playing a larger role in student enrollment, recruitment, and mobility initiatives. Findings provide useful insights for higher education institutions (HEIs) engaged in transnational education (TNE).

2.
Sleep ; 43(4)2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-31702010

RESUMO

STUDY OBJECTIVES: Sleep problems are a core feature of post-traumatic stress disorder (PTSD). The aim of this study was to find a robust objective measure for the sleep disturbance in patients having PTSD. METHODS: The current study assessed EEG power across a wide frequency range and multiple scalp locations, in matched trauma-exposed individuals with and without PTSD, during rapid eye movement (REM) and non-REM (NREM) sleep. In addition, a full polysomnographical evaluation was performed, including sleep staging and assessment of respiratory function, limb movements, and heart rate. The occurrence of sleep disorders was also assessed. RESULTS: In patients having PTSD, NREM sleep shows a substantial loss of slow oscillation power and increased higher frequency activity compared with controls. The change is most pronounced over right-frontal sensors and correlates with insomnia. PTSD REM sleep shows a large power shift in the opposite direction, with increased slow oscillation power over occipital areas, which is strongly related to nightmare activity and to a lesser extent with insomnia. These pronounced spectral changes occur in the context of severe subjective sleep problems, increased occurrence of various sleep disorders and modest changes in sleep macrostructure. CONCLUSIONS: This is the first study to show pronounced changes in EEG spectral topologies during both NREM and REM sleep in PTSD. Importantly, the observed power changes reflect the hallmarks of PTSD sleep problems: insomnia and nightmares and may thus be specific for PTSD. A spectral index derived from these data distinguishes patients from controls with high effect size, bearing promise as a candidate biomarker.


Assuntos
Transtornos do Sono-Vigília , Transtornos de Estresse Pós-Traumáticos , Eletroencefalografia , Humanos , Polissonografia , Transtornos do Sono-Vigília/diagnóstico , Sono REM , Transtornos de Estresse Pós-Traumáticos/diagnóstico
3.
Arch Ital Biol ; 156(3): 87-98, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30324605

RESUMO

Anecdotal reports recount of individuals obtaining insights during sleep. For instance, various acclaimed scientists have attributed some of their greatest insights to sleep-related mentation. To date, this phenomenon has not been systematically investigated. The current study explored the occurrence and characteristics of Sleep-Related Insights (SRIs) in a large population sample, using a questionnaire approach. We found that a large majority of participants (~80%) experienced SRIs at some point in their lives and about 40% obtained SRIs regularly. Most of these subjects could link SRIs to remembered sleep mentation. SRIs were reported to occur in both sleep and half-sleep states, and at any point of the sleep period. Furthermore, SRIs regarded emotional preoccupations about twice as often as theoretical problems. Finally, SRIs were not robustly related to subjective sleep-quality, but small positive correlations with insomnia and narcolepsy-like symptoms were observed. In conclusion, SRIs are much more common than might have been expected, manifest in several forms and appear to be part of normal, healthy sleep. Importantly, the strong link of SRIs with sleep mentation suggests they result from some form of higher-order information processing during sleep, rather than being (fully) secondary to general restorative effects of sleep. Finally, our findings show that a large portion of the sampled population is aware of sleep's benefits for real life problem solving and experiences such benefits on a regular basis.


Assuntos
Criatividade , Resolução de Problemas , Sono/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Inquéritos e Questionários , Adulto Jovem
4.
Adv Health Sci Educ Theory Pract ; 18(3): 485-95, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22736061

RESUMO

The influence of problem-based learning (PBL) and open-book tests on long-term knowledge retention is unclear and subject of discussion. Hypotheses were that PBL as well as open-book tests positively affect long-term knowledge retention. Four progress test results of fifth and sixth-year medical students (n = 1,648) of three medical schools were analyzed. Two schools had PBL driven curricula, and the third one had a traditional curriculum (TC). One of the PBL schools (PBLob) used a combination of open-book (assessing backup knowledge) and closed-book tests (assessing core knowledge); the other two schools (TC and PBLcb) only used closed-book tests. The items of the progress tests were divided into core and backup knowledge. T tests (with Bonferroni correction) were used to analyze differences between curricula. PBL students performed significantly better than TC students on core knowledge (average effect size (av ES) = 0.37-0.74) and PBL students tested with open-book tests scored somewhat higher than PBL students tested without such tests (av ES = 0.23-0.30). Concerning backup knowledge, no differences were found between the scores of the three curricula. Students of the two PBL curricula showed a substantially better long-term knowledge retention than TC students. PBLob students performed somewhat better on core knowledge than PBLcb students. These outcomes suggest that a problem-based instructional approach in particular can stimulate long-term knowledge retention. Distinguishing knowledge into core and backup knowledge and using open-book tests alongside closed-book tests could enhance long-term core knowledge retention.


Assuntos
Educação Médica/métodos , Avaliação Educacional/métodos , Rememoração Mental , Aprendizagem Baseada em Problemas/métodos , Humanos , Estudantes de Medicina/psicologia
5.
Med Teach ; 33(1): e16-21, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21182369

RESUMO

BACKGROUND: Considering the growing amount of medical knowledge and the focus of medical education on acquiring competences, using open-book tests seems inevitable. A possible disadvantage of these tests is that students underestimate test preparation. AIMS: We examined whether students who used a deep learning approach needed less open-book test time, and how students performed on open-book questions asked in a closed-book setting. METHOD: Second- (N = 491) and third-year students (N = 325) prepared half of the subject matter to be tested closed-book and half to be tested open-book. In agreement with the Board of Examiners, some questions in the closed-book test concerned open-book subject matter, and vice versa. Data were gathered about test time, deep learning and preparation time. Repeated measurement analysis, t-tests and partial correlations were used to analyse the data. RESULTS: We found a negative relationship between deep learning and open-book test time for second-year students. Students scored the lowest on closed-book questions about open-book subject matter. CONCLUSIONS: Reduction of the available test time might force students to prepare longer and deeper for open-book tests. Further research is needed to identify variables that influence open-book test time and to determine how restrictive this time should be.


Assuntos
Avaliação Educacional/métodos , Aprendizagem , Estudantes de Medicina , Livros de Texto como Assunto , Educação de Graduação em Medicina/métodos , Feminino , Humanos , Masculino , Países Baixos , Adulto Jovem
6.
Med Educ ; 44(9): 884-891, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20716098

RESUMO

OBJECTIVES: The ability to master discipline-specific knowledge is one of the competencies medical students must acquire. In this context, 'mastering' means being able to recall and apply knowledge. A way to assess this competency is to use both open- and closed-book tests. Student performance on both tests can be influenced by the way the student processes information. Deep information processing is expected to influence performance positively. The personal preferences of students in relation to how they process information in general (i.e. their level of need for cognition) may also be of importance. In this study, we examined the inter-relatedness of deep learning, need for cognition and preparation time, and scores on open- and closed-book tests. METHODS: This study was conducted at the University Medical Centre Groningen. Participants were Year 2 students (n = 423). They were asked to complete a questionnaire on deep information processing, a scale for need for cognition on a questionnaire on intellectualism and, additionally, to write down the time they spent on test preparation. We related these measures to the students' scores on two tests, both consisting of open- and closed-book components and used structural equation modelling to analyse the data. RESULTS: Both questionnaires were completed by 239 students (57%). The results showed that need for cognition positively influenced both open- and closed-book test scores (beta-coefficients 0.05 and 0.11, respectively). Furthermore, study outcomes measured by open-book tests predicted closed-book test results better than the other way around (beta-coefficients 0.72 and 0.11, respectively). CONCLUSIONS: Students with a high need for cognition performed better on open- as well as closed-book tests. Deep learning did not influence their performance. Adding open-book tests to the regularly used closed-book tests seems to improve the recall of knowledge that has to be known by heart. Need for cognition may provide a valuable addition to existing theories on learning.


Assuntos
Cognição/fisiologia , Educação de Graduação em Medicina/métodos , Avaliação Educacional/métodos , Aprendizagem/fisiologia , Estudantes de Medicina/psicologia , Adolescente , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Estatística como Assunto , Inquéritos e Questionários , Livros de Texto como Assunto , Fatores de Tempo , Adulto Jovem
7.
Med Educ ; 42(10): 967-74, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18823515

RESUMO

CONTEXT: Two learning approaches are consistently distinguished in the literature: deep and surface learning. The deep learning approach is considered preferable. Open-book tests are expected to stimulate deep learning and to offer a possible way of handling the substantial growth in medical knowledge. In this study we test the hypothesis that open-book tests stimulate deep learning more than closed-book tests. METHODS: Medical students in Years 2 (n = 423) and 3 (n = 306) participated in this study. They evaluated their preparation for open- and closed-book tests using the test for Deep Information Processing (DIP). This questionnaire consists of 24 items divided into three subscales: Critical Reading; Broaden One's Context, and Structuring. A paired t-test was used to analyse the data. RESULTS: Both cohorts scored significantly higher when preparing for closed-book tests for the overall DIP score and on the Broaden One's Context and Structuring scales. Year 3 students also scored significantly higher on the Critical Reading scale when preparing for closed-book tests. Gender differences were found: women used deeper learning approaches than men. CONCLUSIONS: Our hypothesis was not supported. In fact, the opposite was found: closed-book tests stimulated a deep learning approach more than open-book tests. Three possible explanations are: deep learning is particularly necessary for remembering and recalling knowledge; students feel more confident when preparing for closed-book tests, and students are more motivated to study for closed-book tests. The debate on the concept of deep learning in higher education should probably be renewed.


Assuntos
Educação de Graduação em Medicina/métodos , Avaliação Educacional/métodos , Estudantes de Medicina/psicologia , Adulto , Estudos de Coortes , Avaliação Educacional/normas , Humanos , Estatística como Assunto , Inquéritos e Questionários , Livros de Texto como Assunto
8.
N Engl J Med ; 342(7): 513; author reply 514, 2000 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-10691485
9.
Crit Care Med ; 27(1): 120-9, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9934905

RESUMO

OBJECTIVE: Changes in pulmonary blood flow rate can alter the size of the perfused pulmonary capillary surface area. We tested the hypothesis that full recruitment of the pulmonary vascular bed may decrease evidence of lung injury by recruiting less injured capillaries. We also tested the hypothesis that endothelial ectoenzyme activity is an earlier indicator of lung injury than are permeability measures. DESIGN: Isolated canine lung lobes were perfused with autologous blood at constant blood flows of either 2.05+/-0.04 L/min (SEM) (high flow, full recruitment, n = 12) or 0.600 +/- 0.004 L/min (low flow, 33% full recruitment, n = 12) after lung injury to determine the effect of vascular recruitment on measures of injury. SETTING: Research laboratory at a medical university. SUBJECTS: Lung lobes were obtained from 36 mongrel dogs of either gender. INTERVENTIONS: Lung injury was induced by adding phorbol myristate acetate (PMA) to the blood perfusing the isolated lung. MEASUREMENTS AND MAIN RESULTS: Indicator dilution methods were used to measure single pass hydrolysis of 3[H]-benzoyl-Phe-Ala-Pro, a synthetic substrate for angiotensin converting enzyme, and calculate the modified first order kinetic parameter corresponding to the ratio of a normalized maximal enzymatic conversion rate (A(max)) to the Michaelis-Menten constant (K(m)), i.e., A(max)/K(m), before and after PMA. At a given flow rate, the decrease in A(max)/K(m)serves as an index of vascular injury. PMA decreased A(max)/K(m), percent metabolism, and fractional substrate utilization, and increased permeability, vascular resistance, and vascular pressures regardless of flow rate. The decrease in enzyme activity was detected earlier than the increase in permeability. CONCLUSION: The greater percentage decrease in percent metabolism and fractional substrate utilization and the earlier appearance of increased permeability during high flow indicates that increasing blood flow three-fold recruited injured vessels and/or increased vascular injury by increasing vascular perfusion pressures.


Assuntos
Barreira Alveolocapilar , Pulmão/patologia , Circulação Pulmonar , Síndrome do Desconforto Respiratório/fisiopatologia , Animais , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Permeabilidade Capilar , Dimetil Sulfóxido , Cães , Endotélio/irrigação sanguínea , Endotélio/enzimologia , Endotélio/patologia , Feminino , Pulmão/irrigação sanguínea , Pulmão/enzimologia , Masculino , Peptidil Dipeptidase A/metabolismo , Síndrome do Desconforto Respiratório/induzido quimicamente , Acetato de Tetradecanoilforbol , Resistência Vascular
10.
Pers Individ Dif ; 27(5): 853-60, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-11542386

RESUMO

Differences in lifestyle may account for a considerable portion of the reported age-related changes in overt circadian rhythmicity. By instructing a group of healthy, noninstitutionalized, elderly subjects and a group of young adults to keep a sleep-wake log for a period of two weeks, and to wear an activity monitor for an overlapping period of 11 days, we attempted to assess age-related differences in the habitual sleep-wake behavior, in particular its day-to-day variability. Four clusters of coherent variables were constructed, reflecting (1) circadian phase, (2) variability of sleep-wake behavior, (3) sleep-wake continuity and (4) subjective sleep-wake quality. The results showed that, in comparison with the young subjects, the elderly had a relatively advanced and more regular sleep-wake pattern, reported more midnight awakening and did not differ in their subjective sleep evaluation. In spite of a greater regularity in their lifestyle (which would favor a larger amplitude of the overt circadian rhythmicity) oral temperature measurements showed some evidence of a weakened 24-h periodicity in the elderly.


Assuntos
Envelhecimento , Ritmo Circadiano , Sono , Vigília , Adolescente , Adulto , Fatores Etários , Idoso , Análise de Variância , Temperatura Corporal , Coleta de Dados/métodos , Processamento Eletrônico de Dados , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos
11.
Microvasc Res ; 54(2): 145-55, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9327385

RESUMO

Whether the pulmonary vascular bed accommodates flow-induced increases in blood volume mainly through recruitment of previously unperfused capillaries or distension of already perfused vessels remains controversial. The modified first order reaction parameter of an enzyme and substrate, Amax/K(m), is, under nontoxic conditions, proportional to enzyme mass. Thus for ACE, an endothelium-bound ectoenzyme uniformly distributed along the luminal surface of the pulmonary capillary bed, Amax/K(m) is proportional to the dynamically perfused capillary surface area (PCSA). We estimated single-pass translobar hydrolysis and calculated the corresponding Amax/K(m) values of the synthetic ACE substrate 3H-benzoyl-Phe-Ala-Pro (BPAP), under first-order reaction conditions, in isolated blood-perfused dog lung lobes. We additionally studied blood flow distribution using radioactive microsphere techniques. Experiments were performed under zone III conditions over a wide range of lobar blood flow rates (Qb). As Qb was increased, Amax/K(m) rose linearly, while lobar vascular resistance (LVR) decreased, suggesting capillary recruitment rather than distension. Single pass BPAP hydrolysis (v approximately 2.9 at resting Qb) was not altered over a wide range of Qb, indicative of unchanging capillary transit times. When full capillary recruitment was achieved (at Qb > 70 ml/min/g lung wet weight), further Qb elevations failed to increase Amax/K(m), but decreased BPAP hydrolysis, denoting shorter transit times through the fully recruited capillary bed. Our data indicate that, as previously shown for rabbit lung, in this canine model, increases in pulmonary blood volume are mainly accommodated through recruitment of previously unperfused capillaries throughout the entire lung.


Assuntos
Endotélio Vascular/enzimologia , Peptidil Dipeptidase A/análise , Circulação Pulmonar/fisiologia , Animais , Capilares/enzimologia , Capilares/ultraestrutura , Cães , Feminino , Hemodinâmica/fisiologia , Cinética , Masculino , Microesferas , Propriedades de Superfície
12.
J Vasc Res ; 33(4): 340-5, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8695758

RESUMO

Methylene blue (MB) is a widely used putative inhibitor of nitric oxide (NO)-dependent responses, particularly in cell culture and vascular ring studies. MB is postulated to diminish vasodilation to NO either by preventing activation of guanylate cyclase by NO or by oxidizing NO formed by NO synthase. In the present study we examined whether MB inhibited vasodilation to bradykinin (BK) in the cyclooxygenase-inhibited, isolated canine lung lobe perfused with blood at constant flow. One group of lobes (n = 5) was challenged with BK at baseline vascular tone, after tone was doubled by infusion of serotonin (5-HT), and again after MB treatment. Bradykinin challenge failed to evoke a depressor response at baseline vascular tone but induced marked vasodilation after vascular tone was increased by 5-HT. Subsequent treatment with MB, however, failed to significantly diminish vasodilation to BK (p > 0.05). A second group of lobes (n = 4) was challenged with BK after cyclooxygenase inhibition and the doubling of vascular tone with serotonin infusion. The dose-dependent vasodilation to BK was diminished (p < 0.01) after treatment with 1.8 mM N omega-nitro-L-arginine (L-NA), a potent inhibitor of nitric oxide synthase. However, subsequent treatment with MB restored the vasodilator response to bradykinin to pre-L-NA values (p < 0.01). While our results suggest that vasodilation to bradykinin is mediated in part by NO formation, MB treatment does not appear to alter BK-induced vasodilation, and even enhanced vasodilation to bradykinin after L-NA. MB appears to have some nonspecific effects on vascular tone and reactivity that are unrelated to NO formation.


Assuntos
Bradicinina/farmacologia , Pulmão/irrigação sanguínea , Azul de Metileno/farmacologia , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico/farmacologia , Vasodilatação/efeitos dos fármacos , Animais , Arginina/análogos & derivados , Arginina/farmacologia , Cães , Inibidores Enzimáticos/farmacologia , Feminino , Masculino , Óxido Nítrico Sintase/antagonistas & inibidores , Nitroarginina , Serotonina/farmacologia , Resistência Vascular/efeitos dos fármacos
13.
Alzheimer Dis Assoc Disord ; 9(3): 170-5, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8534416

RESUMO

The prevalence of the symptoms at disease onset reported by close informants, in an unselected group of demented elderly, is presented in this study. Of the 174 dementia cases, 98 were Alzheimer disease (AD), 41 were vascular dementia (VaD), and 35 were other dementias. In 42% of AD subjects, single memory deficit was the earliest problem, while in 56% of VaD cases, the tendency was to present two or more disturbances in the early stages. Slightly younger mean age at onset was reported in VaD than in AD cases. Our results support the hypothesis that the debut of the dementia is variable with any combination of symptoms. However, when memory problems start, assessment is needed. Among the neurological findings in the clinical examination, extrapyramidal signs were present in 25% of all dementia cases and in 20% of AD cases. A higher frequency of extrapyramidal signs was present in more severe cases, confirming previous reports of the unfavorable prognostic value of these signs.


Assuntos
Doença de Alzheimer/diagnóstico , Demência/diagnóstico , Neurologia , Distribuição por Idade , Idade de Início , Idoso , Idoso de 80 Anos ou mais , Coleta de Dados , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Escalas de Graduação Psiquiátrica
14.
J Appl Physiol (1985) ; 76(6): 2342-7, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-7928856

RESUMO

The elevated cardiac output associated with exercise increases lung lymph flow and may increase extravascular lung water. However, it is not known if extremely elevated cardiac output alters pulmonary vascular permeability. The hematocrit-protein method was used to determine the solvent drag reflection coefficient, an index of vascular permeability to proteins, in the isolated blood-perfused canine lung lobe. Microvascular pressure was obtained by double vascular occlusion. Lobes filtered fluid during perfusion at normal flow, 0.451 +/- 0.005 l/min (LF; n = 8), or high flow, 2.319 +/- 0.080 l/min (HF; n = 7). In the LF, venous pressure was elevated to 19.0 +/- 0.5 Torr to induce filtration, whereas Pv was 3.3 +/- 0.1 Torr in the HF. In HF vs. LF, respectively, arterial pressure was 61.4 +/- 7.1 vs. 28.0 +/- 1.0 Torr (P < 0.05), microvascular pressure was 31.9 +/- 3.0 vs. 22.2 +/- 0.9 Torr (P < 0.05), and sigma was 0.52 +/- 0.07 vs. 0.51 +/- 0.02 (P > 0.05). The fivefold increase in blood flow did not alter pulmonary vascular permeability to proteins; however, the capillary filtration coefficient was fivefold greater in the HF vs. LF group (0.328 +/- 0.059 vs. 0.067 +/- 0.007; P < 0.002). These data are compatible with enzyme activity measures indicating a direct linear relationship between blood flow rate and perfused pulmonary microvascular surface area. Although the data do not rule out the possibility of increased pulmonary vascular permeability to water during very elevated blood flow rates, the greater filtration rate during elevated flow is more likely related to increases in both microvascular pressure and surface area.


Assuntos
Proteínas Sanguíneas/metabolismo , Permeabilidade Capilar/fisiologia , Circulação Pulmonar/fisiologia , Animais , Gasometria , Pressão Sanguínea/fisiologia , Cães , Feminino , Hematócrito , Hemodinâmica/fisiologia , Pulmão/metabolismo , Masculino , Tamanho do Órgão/fisiologia , Resistência Vascular/fisiologia
15.
J Appl Physiol (1985) ; 74(5): 2502-8, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8335583

RESUMO

Average microvascular filtration pressure and vascular permeability measures were obtained in 100-microns glass bead-embolized dog lung lobes randomly assigned to groups in which isolated perfusion was designed to produce weight gain (edema groups) or no weight gain (isogravimetric groups). The solvent drag reflection coefficient (sigma), an index of vascular permeability, was obtained during edema formation, whereas isogravimetric capillary pressure was obtained during isogravimetry. Vascular permeability increased in response to embolism, because sigma was 0.53 +/- 0.03 vs. 0.80 +/- 0.05 (P < 0.005) in embolized and control lobes, respectively. Vascular occlusion methods indicated the greatest resistance increase in response to embolism in the vascular segment represented by Pao--Pdo (arterial occlusion pressure--double occlusion pressure). Because papaverine vasodilation reduced total vascular resistance (RT; P < 0.05) by decreasing Pao (P < 0.01) without altering Pdo, the RT increase in response to embolism was likely due to both vasoconstriction and obstruction. Because Pdo approximated capillary pressure at isogravimetry, Pdo appears to estimate average filtration pressure in both embolized (n = 6) and control lungs (n = 6). Arterial pressure was 56.2 +/- 13.6 vs. 17.6 +/- 1.5 cmH2O (P < 0.01) in embolized (n = 5) and control lobes (n = 6), respectively, whereas Pdo values of 16.1 +/- 1.5 vs. 12.4 +/- 0.8 (P < 0.05) suggested relatively little increase in filtration pressure in response to embolism. If the beads obstructed 100-microns vessels, the vascular segment represented by Pao--Pdo, the major site of vasoconstriction as well as mechanical obstruction, likely includes 100-microns arteries.


Assuntos
Pressão Sanguínea/fisiologia , Embolia Pulmonar/fisiopatologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Proteínas Sanguíneas/metabolismo , Permeabilidade Capilar/efeitos dos fármacos , Permeabilidade Capilar/fisiologia , Cães , Feminino , Técnicas In Vitro , Masculino , Tamanho do Órgão/efeitos dos fármacos , Tamanho do Órgão/fisiologia , Oxigênio/sangue , Papaverina/farmacologia , Artéria Pulmonar/fisiologia , Pressão Propulsora Pulmonar/fisiologia , Resistência Vascular/efeitos dos fármacos , Resistência Vascular/fisiologia , Vasoconstrição/efeitos dos fármacos
16.
J Sleep Res ; 2(1): 21-27, 1993 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10607066

RESUMO

EEG spectral power was studied during periods of rapid eye movements (REMs) and tonic intervals in REM sleep of 7 young and 7 older male subjects. Significant symmetrical decreases in alpha and beta1 power at central and occipital sites, concurrent with an increase in frontal theta power, were observed during the production of REMs. The former findings are discussed as sleep analogues to changes in alpha and beta1 during waking, showing increased information processing and behavioural activation, and that of theta is tentatively presented as reflecting an increase in afferent thresholds. Independent of the phasic-tonic REM distinction, total EEG power markedly decreased as a function of time of night and did not interact with age. Significant age differences in the overall spectral composition of the EEG were obtained, namely, a lower level of delta power and a relative shift towards more power in frequencies above 12 Hz for the older group. Further, older subjects also demonstrated a more uniform topographical distribution of alpha and sigma power.

17.
Res Commun Chem Pathol Pharmacol ; 78(1): 47-56, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1361070

RESUMO

The effect of increasing blood levels of aspirin on pulmonary hemodynamics and pressor response to vasoactive amines was examined in the isolated canine lung lobe, blood perfused at constant flow. At steady state lobar vascular resistance (LVR), lobes were challenged with either 250 micrograms serotonin (5-HT; n = 4), 5.0 mumol acetylcholine (ACh; n = 4) or 50 micrograms norepinephrine (NE; n = 4) before and after blood aspirin concentration [ASA] was incrementally increased from 17 to 3140 microM. LVR was partitioned into arterial (Ra) and venous (Rv) segments by venous outflow occlusions 20 min after each ASA addition and at the peak of the pressor response to each amine. ASA treatment was associated with a dose-related 105% increase in LVR (P < 0.01) accounted for by a 154% increase in Ra (P < 0.01) and a 70% increase in Rv (P < 0.01) at 3150 microM ASA (n = 12). In spite of increased vascular tone, higher [ASA] also potentiated increases in both pulmonary arterial pressure and LVR to both 5-HT and NE whereas only Ra increased with ACh challenge. Thus, the increase in pulmonary vascular tone and reactivity to vasoactive amines is positively correlated with blood aspirin levels in the dog.


Assuntos
Aspirina/farmacologia , Pulmão/irrigação sanguínea , Músculo Liso Vascular/efeitos dos fármacos , Resistência Vascular/efeitos dos fármacos , Animais , Pressão Sanguínea , Cães , Hemodinâmica/efeitos dos fármacos , Neurotransmissores/farmacologia , Perfusão
18.
Sleep ; 15(4): 371-5, 1992 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1519014

RESUMO

The present report concerns the first study in which electrooculographic (EOG) contamination of electroencephalographic (EEG) recordings in rapid eye movement (REM) sleep is systematically investigated. Contamination of REM sleep EEG recordings in six subjects was evaluated in the frequency domain. REM-active and REM-quiet series were obtained for each subject. Transfer coefficients and power spectra of EOG and EEG indicated that (a) increases in transfer coefficients beyond 4.5 Hz are brought about by residual EEG in the EOG, and (b) EOG-EEG contamination in the delta band is most pronounced in frontal, intermediate in central and negligible in occipital leads. It was found that correction of the REM-active series resulted in significant (c) reductions in power, (d) increases in interhemispheric coherences and (e) reductions in degree of lateral asymmetry. These effects were largest for frontal leads, but still marked for central ones. The results are discussed in the light of previous findings concerning models of hemispheric functioning during REM sleep.


Assuntos
Movimentos Oculares/fisiologia , Sono REM/fisiologia , Adulto , Análise de Variância , Eletroencefalografia , Eletroculografia , Humanos , Masculino , Análise de Regressão , Processamento de Sinais Assistido por Computador
19.
Am J Physiol ; 263(2 Pt 2): H587-96, 1992 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1510156

RESUMO

We examined the effect of methylene blue (MB), a putative inhibitor of guanylate cyclase (GC) activation by endothelium-derived relaxing factor (EDRF) and nitrovasodilator compounds, on vascular tone and reactivity to vasoactive substances in the isolated, blood-perfused canine lower left lung lobe. Lobar vascular resistance was partitioned into arterial and venous segments by venous outflow occlusion. Because MB did not alter vasoconstriction to either serotonin or acetylcholine (P greater than 0.05) except after cyclooxygenase inhibition (COI), we determined the effectiveness of MB as an inhibitor of GC activation by nitrovasodilators. Lobes were given graded bolus doses of nitroglycerin (GTN), sodium nitroprusside (SNP), and bradykinin (BK) at baseline vascular tone, after COI, and after vascular tone was raised by either U-46619, a thromboxane analogue, or MB infusion. GTN and BK but not SNP induced dose-dependent vasodilation when vascular tone was raised by U-46619. However, when vascular tone was increased to a similar level by 30 mg MB and 0.5 mg/min infusion, vasodilation to GTN, SNP, and BK was enhanced from U-46619 infusion. In contrast to MB, NG-nitro-L-arginine, a putative inhibitor of EDRF synthesis, diminished vasodilation to BK in cyclooxygenase-inhibited lobes with elevated vascular tone. Because MB potentiated vasodilation to GTN, SNP, and BK, it is questionable whether MB is an effective inhibitor of vasodilation to nitrovasodilators or BK in the isolated, blood-perfused canine lung.


Assuntos
Azul de Metileno/farmacologia , Circulação Pulmonar/efeitos dos fármacos , Sistema Vasomotor/efeitos dos fármacos , Acetilcolina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase/farmacologia , Cães , Feminino , Técnicas In Vitro , Masculino , Serotonina/farmacologia , Resistência Vascular/efeitos dos fármacos , Vasodilatadores/farmacologia
20.
Neuropsychobiology ; 26(4): 193-7, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1299794

RESUMO

The influence of delta sleep-inducing peptide (DSIP) on sleep was studied in 16 chronic insomniac patients according to a double-blind matched-pairs parallel-groups design. Subjects slept for 5 consecutive nights in the laboratory. Night 1 was used for adaptation, night 2 for baseline measurements. In the afternoon before the 3rd, 4th and 5th night, half of the patients received intravenously 25 nmol/kg body weight DSIP, and half of the patients a glucose solution (placebo). Measures for sleep structure, objective (polysomnography) and subjective sleep quality and for subjective tiredness were assessed. The results for objective sleep quality indicated higher sleep efficiency and shorter sleep latency with DSIP as compared to placebo. One measure of subjectively estimated tiredness decreased within the DSIP group. Data analysis suggested, however, that the statistically significant effects were weak and in part could be due to an incidental change in the placebo group. As none of the other measures, including subjective sleep quality, showed any change, it was concluded that short-term treatment of chronic insomnia with DSIP is not likely to be of major therapeutic benefit.


Assuntos
Nível de Alerta/efeitos dos fármacos , Peptídeo Indutor do Sono Delta/uso terapêutico , Distúrbios do Início e da Manutenção do Sono/terapia , Fases do Sono/efeitos dos fármacos , Adulto , Idoso , Nível de Alerta/fisiologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/fisiopatologia , Método Duplo-Cego , Eletroencefalografia/efeitos dos fármacos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia , Tempo de Reação/efeitos dos fármacos , Distúrbios do Início e da Manutenção do Sono/fisiopatologia , Fases do Sono/fisiologia , Vigília/efeitos dos fármacos
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