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1.
Sci Rep ; 10(1): 21110, 2020 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-33273513

RESUMO

Visual hallucinations (VH) are common in patients with Parkinson's disease (PD), yet the underlying pathophysiological mechanisms are still unclear. We aimed to explore the association of the presence of VH with inner retinal thinning and, secondarily, with visual acuity. To this end, we included 40 PD patients in this exploratory study, of whom 14 had VH, and 22 age- and sex-matched healthy controls. All participants were interviewed for the presence of VH by a neurologist specialized in movement disorders and underwent a thorough ophthalmologic examination, including measurement of the best-corrected visual acuity (BCVA) and optical coherence tomography to obtain macular scans of the combined ganglion cell layer and inner plexiform layer (GCL-IPL). Patients with VH had a thinner GCL-IPL than patients without VH, which persisted after correction for age, disease stage, levodopa equivalent daily dose (LED) and cognitive function. Furthermore, BCVA was lower in the PD group with VH than in the PD group without VH, although only a trend remained after correction for age, disease stage, LED and cognitive function. Taken together, in patients with PD, visual hallucinations appear to be associated with a thinning of the inner retinal layers and, possibly, with reduced visual acuity. Further research using a longitudinal design is necessary to confirm these findings and to establish the causality of these relationships.


Assuntos
Alucinações/complicações , Doença de Parkinson/complicações , Retina/patologia , Idoso , Cognição , Feminino , Alucinações/fisiopatologia , Humanos , Modelos Logísticos , Masculino , Doença de Parkinson/fisiopatologia , Índice de Gravidade de Doença , Acuidade Visual
2.
Neurobiol Learn Mem ; 160: 132-138, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-29864525

RESUMO

Atrophy of the medial temporal lobe of the brain is key to memory function and memory complaints in old age. While age and some morbidities are major risk factors for medial temporal lobe atrophy, individual differences remain, and mechanisms are insufficiently known. The largest combined neuroimaging and whole genome study to date indicates that medial temporal lobe volume is most associated with common polymorphisms in the GRIN2B gene that encodes for the 2B subunit (NR2B) of the NMDA receptor. Because sleep disruption induces a selective loss of NR2B from hippocampal synaptic membranes in rodents, and because of several other reports on medial temporal lobe sensitivity to sleep disruption, we hypothesized a contribution of the typical age-related increase in sleep-wake rhythm fragmentation to medial temporal lobe atrophy. Magnetic resonance imaging and actigraphy in 138 aged individuals showed that individual differences in sleep-wake rhythm fragmentation accounted for more (19%) of the variance in medial temporal lobe atrophy than age did (15%), or any of a list of health and brain structural indicators. The findings suggest a role of sleep-wake rhythm fragmentation in age-related medial temporal lobe atrophy, that might in part be prevented or reversible.


Assuntos
Envelhecimento , Transtornos Cronobiológicos , Privação do Sono , Lobo Temporal , Actigrafia , Idoso , Envelhecimento/patologia , Envelhecimento/fisiologia , Atrofia/diagnóstico por imagem , Atrofia/patologia , Transtornos Cronobiológicos/patologia , Transtornos Cronobiológicos/fisiopatologia , Feminino , Humanos , Individualidade , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Privação do Sono/patologia , Privação do Sono/fisiopatologia , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/patologia
3.
Int Psychogeriatr ; 31(6): 857-868, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30560737

RESUMO

OBJECTIVES: Various art programs are available for people with dementia. These have been shown to contribute to the patient's quality of life. But are all types of art suitable for this purpose and for the target group? This study investigated whether responsiveness during museum programs depends on the type of art work shown and/or characteristics of the person with dementia, such as severity of dementia or specific cognitive impairments. METHOD: A cross-sectional observational study was conducted in which the responsiveness of people with dementia to different types of art was investigated as part of a study into the implementation of the Unforgettable program, an interactive guided museum tour program in Dutch museums for people with dementia. RESULTS: The appreciative and active responsiveness and interaction with others during the program appeared related to the severity of dementia, to specific cognitive impairments, and to type of artworks. People with more severe dementia responded less to art than people with mild dementia. Artworks with more natural elements revealed less interaction with others. Artifacts (i.e., objects not originally meant as artworks) evoked more reactions than artworks. CONCLUSION: The study results are important to take into account when designing and offering art programs for people with dementia. Knowing which type of art works appeals most to (subgroups of) people with dementia will contribute to the optimization of art programs for this target group and to their active participation in such programs.

4.
J Neurol Sci ; 394: 132-137, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30261428

RESUMO

INTRODUCTION: Patients with complete occlusion of the internal carotid artery (CAO) are vulnerable to cerebral hypoperfusion. Since cerebral hypoperfusion is associated with accelerated cognitive decline, patients with CAO may have an increased risk of cognitive impairment. We aimed to assess the prevalence and profile of cognitive impairment in patients with CAO and to explore the relation between hemodynamic impairment and cognitive functioning. METHODS: We systematically searched Medline and EMBASE for studies including patients with symptomatic or asymptomatic CAO subjected to cognitive testing that were published between 1980 and 2017. We did not include patients with carotid stenosis. We obtained data on type of study, patient characteristics, cerebral imaging and neuropsychological testing. In addition, we extracted data on potential causes of systemic hemodynamic impairment and the presence and stage of cerebral hemodynamic impairment. We assessed methodological quality of included studies with the Newcastle-Ottawa Scale. RESULTS: We found eight studies comprising 244 patients (mean age 61 years, 76% male, 93% symptomatic CAO). The proportion of patients with cognitive impairment ranged from 54 to 71% in four studies; in the other four studies patients with CAO performed worse on cognitive testing than controls, but results were not quantified. Impairment was reported in all cognitive domains. We found no data on the association between systemic hemodynamic impairment and cognitive functioning. Studies that assessed whether cerebral hemodynamic impairment was associated with cognitive functioning showed conflicting results. CONCLUSION: In patients with CAO, cognitive impairment is present in about half to two-thirds of patients and is not restricted to specific cognitive domains. The effect of systemic and cerebral hemodynamic impairment on cognitive functioning in patients with CAO deserves further study.


Assuntos
Estenose das Carótidas/complicações , Transtornos Cognitivos/etiologia , Bases de Dados Bibliográficas/estatística & dados numéricos , Humanos
5.
NeuroRehabilitation ; 34(3): 401-7, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24473242

RESUMO

BACKGROUND: Despite the beneficial effect of cardiac rehabilitation after myocardial infarction, a rehabilitation program to improve cardiorespiratory fitness and influence secondary prevention has not been implemented for ischemic stroke and transient ischemic attack (TIA). OBJECTIVE: To investigate the safety and feasibility of a post-stroke care including an exercise program after minor ischemic stroke or TIA. METHODS: In a randomised controlled trial, 20 patients with a recent minor stroke or TIA without cardiac contraindications were randomly assigned to one of the two interventions; post-stroke care without exercise or post-stroke care with exercise. Patients were evaluated at baseline, 6 and 12 months. RESULTS: Eighteen patients completed the intervention. In none of the patients cardiopulmonary contraindications for the maximal exercise test and exercise program were found. No cardiovascular events occurred during the maximal exercise tests and exercise program. After one year, significantly more patients in the post-stroke care with exercise group achieved the composite endpoint of optimal medical therapy. CONCLUSIONS: Post-stroke care including an exercise program is safe and feasible in the acute phase after minor stroke or TIA and might be a way to increase effectiveness of secondary stroke prevention. We are currently conducting a larger trial to validate these results.


Assuntos
Terapia por Exercício , Ataque Isquêmico Transitório/reabilitação , Aptidão Física , Prevenção Secundária/métodos , Reabilitação do Acidente Vascular Cerebral , Idoso , Teste de Esforço , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Motivação , Fatores de Risco
6.
BMJ Open ; 4(12): e007065, 2014 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-25552615

RESUMO

INTRODUCTION: Patients with transient ischaemic attack (TIA) or stroke are at risk for cognitive impairment and dementia. Currently, there is no known effective strategy to prevent this cognitive decline. Increasing evidence exists that physical exercise is beneficial for cognitive function. However, in patients with TIA or stroke who are at risk of cognitive impairment and dementia, only a few trials have been conducted. In this study, we aim to investigate whether a physical exercise programme (MoveIT) can prevent cognitive decline in patients in the acute phase after a TIA or minor ischaemic stroke. METHODS AND ANALYSIS: A single-blinded randomised controlled trial will be conducted to investigate the effect of an aerobic exercise programme on cognition compared with usual care. 120 adult patients with a TIA or minor ischaemic stroke less than 1 month ago will be randomly allocated to an exercise programme consisting of a 12-week aerobic exercise programme and regular follow-up visits to a specialised physiotherapist during the period of 1 year or to usual care. Outcome measures will be assessed at the baseline, and at the 1-year and 2-year follow-up. The primary outcome is cognitive functioning measured with the Montreal Cognitive Assessment (MoCA) test and with additional neuropsychological tests. Secondary outcomes include maximal exercise capacity, self-reported physical activity and measures of secondary prevention. ETHICS AND DISSEMINATION: The study received ethical approval from the VU University Amsterdam Ethics committee (2011/383). The results of this study will be published in peer-reviewed journals and presented at international conferences. We will also disseminate the main results to our participants in a letter. TRIAL REGISTRATION NUMBER: The Nederlands Trial Register NTR3884.


Assuntos
Transtornos Cognitivos/prevenção & controle , Terapia por Exercício/métodos , Ataque Isquêmico Transitório/complicações , Acidente Vascular Cerebral/complicações , Adulto , Feminino , Humanos , Masculino , Prevenção Secundária/métodos , Método Simples-Cego
9.
Neurobiol Aging ; 29(8): 1265-71, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17368870

RESUMO

Distortions in the rest-activity rhythm in aging are commonly observed. Neurodegenerative changes of the suprachiasmatic nucleus have been proposed to underlie this disrupted rhythm. However, based on previous studies, it can be proposed that white matter hyperintensities (WMH) may also play a role in the altered rest-activity rhythm in aging. The present study focused on the rest-activity rhythm, as assessed with actigraphy, and WMH in nondemented aging. With regard to the rest-activity rhythm, the interdaily stability (IS), intradaily variability (IV) and the amplitude (AMP) of the rhythm were of interest. The white matter hyperintensities were examined separately for the periventricular (PVH) and deep white matter (DWMH) regions, while distinguishing between the various locations within these regions (e.g. occipital PVH). The results indicated that frontal DWMH related to both IS and AMP. A reduction in the most active 10-h period mediated the relationship between frontal DWMH and AMP. Possible underlying mechanisms of these associations are discussed.


Assuntos
Envelhecimento/patologia , Envelhecimento/fisiologia , Atividade Motora/fisiologia , Fibras Nervosas Mielinizadas/ultraestrutura , Periodicidade , Descanso/fisiologia , Adaptação Fisiológica , Idoso , Feminino , Humanos , Masculino , Estatística como Assunto
10.
Asia Pac J Public Health ; 19 Spec No: 52-9, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18277529

RESUMO

This paper describes the results of an investigation into how the December, 2004 tsunami and its aftermath affected the human rights of the survivors. Teams of researchers interviewed survivors, government officials, representatives of international and local nongovernmental organisations, UN officials, the military, police, and other key informants in India, Sri Lanka, the Maldives, Indonesia, and Thailand. We also analysed newspaper articles, reports released by governments, UN agencies, NGOs, and private humanitarian aid groups, and we examined the laws and policies related to survivors' welfare in the affected countries. We found worsening of prior human rights violations, inequities in aid distribution, lack of accountability and impunity, poor coordination of aid, lack of community participation in reconstruction, including coastal redevelopment. Corruption and preexisting conflict negatively impact humanitarian interventions. We make recommendations to international agencies, states, and local health service providers. A human rights framework offers significant protection to survivors and should play a critical role in disaster response.


Assuntos
Desastres , Disparidades em Assistência à Saúde , Violação de Direitos Humanos/estatística & dados numéricos , Direitos Humanos/normas , Adulto , Idoso , Ásia , Participação da Comunidade/estatística & dados numéricos , Anticoncepcionais Femininos/provisão & distribuição , Comparação Transcultural , Países em Desenvolvimento/estatística & dados numéricos , Feminino , Serviços de Saúde para Idosos/normas , Serviços de Saúde para Idosos/provisão & distribuição , Humanos , Ilhas do Oceano Índico , Cooperação Internacional , Entrevistas como Assunto , Masculino , Serviços de Saúde Materna/normas , Serviços de Saúde Materna/provisão & distribuição , Pessoa de Meia-Idade , Organizações , Gravidez , Socorro em Desastres/normas , Socorro em Desastres/estatística & dados numéricos , Delitos Sexuais/estatística & dados numéricos , Serviços de Saúde da Mulher/normas , Serviços de Saúde da Mulher/provisão & distribuição
11.
Dement Geriatr Cogn Disord ; 21(5-6): 322-7, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16484811

RESUMO

OBJECTIVE: The event-related potential (ERP) evoked by the auditory oddball paradigm has been investigated mainly in patients with Alzheimer's disease and in patients with different causes of subcortical dementia. Subcortical ischemic vascular disease (SIVD) seems to be an important cause of vascular cognitive impairment (VCI) frequently not fulfilling the criteria for dementia. Recognition of VCI is needed in order to provide adequate care and therapy. The aim of this study was to investigate the diagnostic value of the different elements of this response (N(1), N(2) complex and P(3) latencies) in a group of elderly patients with VCI caused by SIVD. METHODS: The study population consisted of patients with a clinical and neuropsychological diagnosis of VCI caused by SIVD (n = 38) and healthy control subjects (n = 53) aged 60 years or older. The mean Mini Mental State Examination score of both groups was 27.6, and the mean HIV Dementia Scale score was 6.1 in the patient group and 12.3 in the control group. In all subjects, the ERP was recorded under standardized conditions, and the latencies and amplitudes of N(1), N(2) and P(3) were analyzed by two clinical neurophysiologists in consensus. Both were blinded to the diagnosis. RESULTS: The N(2) latency was significantly longer in patients with VCI than in age-matched controls, whereas the latencies of the P(3) and N(1) were not significantly different. The peak-to-peak amplitude of the N(2) complex to the P(3) wave was significantly lower in the patient group. White matter abnormalities on MRI were not significantly correlated with the N(2) latency. CONCLUSION: Our findings suggest that the latency of the N(2) complex is prolonged and the peak-to-peak amplitude of the N(2) complex to the P(3) wave is lowered in patients with VCI caused by SIVD.


Assuntos
Encéfalo/irrigação sanguínea , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/epidemiologia , Demência Vascular/epidemiologia , Demência Vascular/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Idoso , Circulação Cerebrovascular/fisiologia , Eletroencefalografia , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Índice de Gravidade de Doença , Fatores de Tempo
12.
Leukemia ; 19(12): 2101-16, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16136167

RESUMO

From 1981 to 2000, a total of 1823 children with acute myeloid leukemia (AML) enrolled on four consecutive Pediatric Oncology Group (POG) clinical trials. POG 8101 demonstrated that the induction rate associated with the 3+7+7 combination of daunorubicin, Ara-C, and 6-thioguanine (DAT) was greater than that associated with an induction regimen used to treat acute lymphoblastic leukemia (82 vs 61%; P=0.02). Designed as a pilot study to determine the feasibility of administration of noncross-resistant drug pairs and later modified to assess the effect of dose intensification of Ara-C during the second induction course, POG 8498 confirmed the high initial rate of response to DAT (84.2%) and showed that dose intensification of Ara-C during the second induction course resulted in a trend toward higher event-free survival (EFS) estimates than did standard-dose DAT (2+5) during the second induction course (5 year EFS estimates, 22 vs 27%; P=0.33). Age <2 years and leukocyte count <100 000/mm3 emerged as significantly good prognostic factors. The most significant observation made in the POG 8498 study was the markedly superior outcome of children with Down's syndrome who were treated on the high-dose Ara-C regimen. POG 8821 compared the efficacy of autologous bone marrow transplantation (BMT) with that of intensive consolidation chemotherapy. Intent-to-treat analysis revealed similar 5-year EFS estimates for the group that underwent autologous BMT (36+/-4.7%) and for the group that received only intensive chemotherapy (35+/-4.5%) (P=0.25). There was a high rate of treatment-related mortality in the autologous transplantation group. The study demonstrated superior results of allogeneic BMT for patients with histocompatible related donors (5-year EFS estimate 63+/-5.4%) and of children with Down's syndrome (5-year EFS estimate, 66+/-8.6%). The POG 9421 AML study evaluated high-dose Ara-C as part of the first induction course and the use of the multidrug resistance modulator cyclosporine. Preliminary results showed that patients receiving both high-dose Ara-C for remission induction and the MDR modulator for consolidation had a superior outcome (5-year EFS estimate, 42+/-8.2%) than did patients receiving other treatment; however, the difference was not statistically significant. These four studies demonstrate the importance of dose intensification of Ara-C in the treatment of childhood AML; cytogenetics as the single most prognostic factor and the unique curability of AML in children with Down's syndrome.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos Antineoplásicos/normas , Leucemia Mieloide/terapia , Doença Aguda , Adolescente , Transplante de Medula Óssea , Criança , Pré-Escolar , Citarabina/uso terapêutico , Relação Dose-Resposta a Droga , Síndrome de Down/complicações , Síndrome de Down/tratamento farmacológico , Seguimentos , Humanos , Lactente , Recém-Nascido , Leucemia Mieloide/complicações , Leucemia Mieloide/mortalidade , Prognóstico , Indução de Remissão/métodos , Análise de Sobrevida , Resultado do Tratamento
13.
Ned Tijdschr Geneeskd ; 149(13): 673-6, 2005 Mar 26.
Artigo em Holandês | MEDLINE | ID: mdl-15819129

RESUMO

Four patients, two women aged 29 and 52 and two men aged 46 and 25, respectively, consulted a neurologist for attention and memory disorders. Further investigation revealed that the symptoms were caused by metachromatic leucodystrophy, Graves' disease, Huntington's disease, and a psychological background, respectively. The first patient became dependent in 1.5 years, the second recovered after treatment, the third was independent with slowly progressive symptoms after 1 year, and the fourth was advised to consult a psychologist. Disorders of attention and memory in relatively young people deserve a detailed evaluation at the very first visit, involving the elaboration of an initially extensive differential diagnosis. Too early a separation between a psychic and an organic pathogenesis should be avoided. Indications for the presence of a neurological condition include: consultation at the initiative of others, a relatively brief duration of symptoms without a clear provoking factor, the absence of a psychiatric history or life event, cognitive dysfunction in several areas, abnormal behaviour and an incriminating family history.


Assuntos
Transtornos Cognitivos/diagnóstico , Transtornos da Memória/diagnóstico , Transtornos Psicofisiológicos/diagnóstico , Adulto , Transtornos Cognitivos/etiologia , Diagnóstico Diferencial , Feminino , Doença de Graves/complicações , Doença de Graves/diagnóstico , Humanos , Doença de Huntington/complicações , Doença de Huntington/diagnóstico , Leucodistrofia Metacromática/complicações , Leucodistrofia Metacromática/diagnóstico , Masculino , Transtornos da Memória/etiologia , Pessoa de Meia-Idade , Exame Neurológico , Testes Neuropsicológicos , Transtornos Psicofisiológicos/complicações
15.
Leukemia ; 16(5): 920-7, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-11986955

RESUMO

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Ciclosporina/farmacocinética , Etoposídeo/farmacocinética , Leucemia Mieloide/tratamento farmacológico , Mitoxantrona/farmacocinética , Doença Aguda , Adolescente , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/sangue , Área Sob a Curva , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Ciclosporina/administração & dosagem , Ciclosporina/toxicidade , Interações Medicamentosas , Resistência a Múltiplos Medicamentos , Etoposídeo/administração & dosagem , Etoposídeo/sangue , Feminino , Humanos , Lactente , Leucemia Mieloide/complicações , Masculino , Taxa de Depuração Metabólica/efeitos dos fármacos , Mitoxantrona/administração & dosagem , Mitoxantrona/sangue
17.
J Comput Aided Mol Des ; 16(11): 841-53, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12825797

RESUMO

Some key concerns raised by molecular modeling and computational simulation of functional mechanisms for membrane proteins are discussed and illustrated for members of the family of G protein coupled receptors (GPCRs). Of particular importance are issues related to the modeling and computational treatment of loop regions. These are demonstrated here with results from different levels of computational simulations applied to the structures of rhodopsin and a model of the 5-HT2A serotonin receptor, 5-HT2AR. First, comparative Molecular Dynamics (MD) simulations are reported for rhodopsin in vacuum and embedded in an explicit representation of the membrane and water environment. It is shown that in spite of a partial accounting of solvent screening effects by neutralization of charged side chains, vacuum MD simulations can lead to severe distortions of the loop structures. The primary source of the distortion appears to be formation of artifactual H-bonds, as has been repeatedly observed in vacuum simulations. To address such shortcomings, a recently proposed approach that has been developed for calculating the structure of segments that connect elements of secondary structure with known coordinates, is applied to 5-HT2AR to obtain an initial representation of the loops connecting the transmembrane (TM) helices. The approach consists of a simulated annealing combined with biased scaled collective variables Monte Carlo technique, and is applied to loops connecting the TM segments on both the extra-cellular and the cytoplasmic sides of the receptor. Although this initial calculation treats the loops as independent structural entities, the final structure exhibits a number of interloop interactions that may have functional significance. Finally, it is shown here that in the case where a given loop from two different GPCRs (here rhodopsin and 5-HT2AR) has approximately the same length and some degree of sequence identity, the fold adopted by the loops can be similar. Thus, in such special cases homology modeling might be used to obtain initial structures of these loops. Notably, however, all other loops in these two receptors appear to be very different in sequence and structure, so that their conformations can be found reliably only by ab initio, energy based methods and not by homology modeling.


Assuntos
Receptores Acoplados a Proteínas G/química , Algoritmos , Sequência de Aminoácidos , Simulação por Computador , Membranas Artificiais , Modelos Moleculares , Método de Monte Carlo , Conformação Proteica , Estrutura Terciária de Proteína , Receptor 5-HT2A de Serotonina/química , Receptor 5-HT2A de Serotonina/genética , Rodopsina/química , Rodopsina/genética , Homologia de Sequência de Aminoácidos , Termodinâmica , Vácuo , Água
18.
Biochemistry ; 40(45): 13501-9, 2001 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-11695897

RESUMO

Mutations within the "X1BBX2X3B" motif or its variants in the junction of the third intracellular (i3) loop and the sixth transmembrane domain (TM6) have been shown to lead to constitutive activation of several G protein-coupled receptors (GPCRs). In this study, T6.34(279) at the X3 locus of the rat mu opioid receptor was mutated to Lys and Asp, and the mutants were examined for binding and signaling properties. The T6.34(279)K mutant was poorly expressed, and pretreatment with naloxone greatly enhanced its expression. This construct exhibited properties identified previously with constitutive activation: (1) compared with the wild type, it produced much higher agonist-independent [35S]GTPgammaS binding, which was abolished by pertussis toxin treatment; (2) it displayed an enhanced affinity for the agonist DAMGO similar to that of the high-affinity state of the wild type, which was not altered by GTPgammaS, while having unchanged affinity for the antagonist diprenorphine. The T6.34(279)K mutant displayed a higher intracellular receptor pool than the wild type. Naloxone inhibited the basal [35S]GTPgammaS binding of the T6.34(279)K mutant, demonstrating inverse agonist activity at this mutant receptor. In contrast, the T6.34(279)D substitution did not increase basal [35S]GTPgammaS binding, greatly reduced agonist-promoted [35S]GTPgammaS binding, and markedly decreased affinity for DAMGO. Thus, the T6.34(279)D mutant adopts conformations corresponding to inactive states of the receptor. The results were interpreted in the structural context of a model for the mu opioid receptor that incorporates the information from the crystal structure of rhodopsin. The interaction of T6.34(279) with R3.50(165) in the mu opioid receptor is considered to stabilize the inactive conformations. The T6.34(279)K substitution would then disrupt this interaction and support agonist-free activation, while T6.34(279)D mutation should strengthen this interaction which keeps the receptor in inactive states. T6.34(279) may, in addition, interact with the neighboring R6.35(280) to help constrain the receptor in inactive states, and T6.34(279)K and T6.34(279)D mutations would affect this interaction by disrupting or strengthening it, respectively. To the best of our knowledge, the results presented here represent the first structurally rationalized demonstration that mutations of this locus can lead to dramatically different properties of a GPCR.


Assuntos
Motivos de Aminoácidos/fisiologia , Receptores Opioides mu/fisiologia , Motivos de Aminoácidos/genética , Substituição de Aminoácidos , Animais , Ácido Aspártico/genética , Células CHO , Sequência Conservada , Cricetinae , Diprenorfina/metabolismo , Expressão Gênica/efeitos dos fármacos , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Lisina/genética , Modelos Moleculares , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Toxina Pertussis , Ratos , Receptores Opioides mu/química , Receptores Opioides mu/genética , Receptores Opioides mu/metabolismo , Radioisótopos de Enxofre , Treonina/genética , Trítio , Fatores de Virulência de Bordetella/farmacologia
19.
Leuk Lymphoma ; 42(3): 399-405, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11699405

RESUMO

The Pediatric Oncology Group (POG) adopted a histology-based approach to the management of pediatric non-Hodgkin's lymphomas (NHL) utilizing the National Cancer Institute Working Formulation for Clinical Usage. Patients with diffuse large cell lymphoma (DLCL) were treated on a separate protocol from small cell diffuse undifferentiated or lymphoblastic lymphomas. This study assessed the overall and event free survival of children with DLCL and determined the effects of cyclophosphamide upon these end-points in a prospective randomized trial. One hundred and twenty eligible stage III or IV NHL patients with the confirmed diagnosis of diffuse large cell or immunoblastic histology were enrolled on study between October 1986 and November 1991. Patients were randomized to receive or not receive cyclophosphamide; 58 received cyclophosphamide, doxorubicin, vincristine, 6-mercaptopurine (6-MP), and prednisone (ACOP+) and 62 were treated with doxorubicin, vincristine, 6-MP, and prednisone (APO). In both treatment programs methotrexate was substituted when the doxorubicin cumulative dose reached 450 mg/m2. Radiation was administered to bulky disease if progression or no response were observed after induction therapy. Planned duration of therapy was 12 months. The 5-year event free survival (EFS) rates of patients treated with ACOP+ versus APO were 62% +/- 7% and 72% +/- 6%, respectively. While there was no statistically significant difference between the two treatment arms (p = 0.28), we can only say that we are 95% confident that the difference in 5-year EFS falls in the wide range from 28% in favor of APO to 8% favoring ACOP+. Marrow suppression was the main toxicity with one fatal infection. There were three other deaths on study due to respiratory failure in patients with mediastinal masses. Only one patient experienced cardiotoxicity requiring discontinuation of doxorubicin. Ten patients received radiation therapy to achieve. In conclusion the efficacy of elimination of cyclophosphamide from the treatment program of children and adolescents with advanced stage diffuse large cell lymphoma was inconclusive as to its effect on EFS. Furthermore, the majority of the patients (92%) did not require any radiation therapy to bulky disease indicating that the chemotherapy regimens are quite efficient for achievement of complete remission.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Adolescente , Antígenos CD/análise , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Criança , Ciclofosfamida/administração & dosagem , Intervalo Livre de Doença , Doxorrubicina/administração & dosagem , Humanos , Imuno-Histoquímica , Linfoma Difuso de Grandes Células B/patologia , Metástase Neoplásica , Prednisolona/administração & dosagem , Prednisona/administração & dosagem , Grupos Raciais , Indução de Remissão , Fatores de Tempo , Estados Unidos , Vincristina/administração & dosagem
20.
Accid Anal Prev ; 33(6): 723-34, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11579974

RESUMO

Urban arterials by their nature carry heavy traffic volumes and generate large numbers of motor vehicle crashes. The present study involved review of police crash reports to identify precrash events and driver actions for a sample of crashes on urban arterials and describes a method for reducing such crashes based on analyses of collision patterns and identification of locations with excessive numbers of crashes of a particular type. Police-reported crash data were obtained for three urban arterials in the Washington, DC metropolitan area. A total of 2,013 crash reports were analyzed. Seven crash types accounted for nearly 90% of these reports. On each arterial studied, several locations with excessive numbers of crashes of a particular type were identified, and corresponding engineering countermeasures were recommended. Differences between the approach employed in this study and traditional blackspot analyses are discussed.


Assuntos
Acidentes de Trânsito/prevenção & controle , População Urbana , Acidentes de Trânsito/estatística & dados numéricos , Planejamento de Cidades , District of Columbia , Humanos , Fatores de Risco
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