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1.
Sensors (Basel) ; 23(22)2023 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-38005537

RESUMO

The congestion problem has driven many researchers to address it, among other networking issues. In a packet-switched network, congestion is essential; it leads to a high response time to deliver packets due to heavy traffic, which eventually causes packet loss. Hence, congestion control mechanisms are utilized to prevent such cases. Several interesting algorithms are proposed to focus on this dilemma, such as the Self-Clocked Rate Adaptation for Multimedia (SCReAM) designed for interactive real-time video streaming applications. One of the main issues of SCReAM is the high design complexity due to the large size of its documentation and coding. Furthermore, there is a considerable number of parameters that can be adjusted to accomplish the desired performance. This study proposes a guided parameters' tuning approach to assess and optimize the SCReAM algorithm in an emulated 5G environment through a detailed exploration of its parameters. The proposed approach consists of three phases, namely, the initialization phase, the standalone experimentation phase, and the hybrid experimentation phase. In the first phase, we illustrate the method of initializing and implementing the environment, followed by specifying the investigated parameters' settings, testing, and validation. The second phase aims to investigate SCReAM parameters in isolation to identify the effect on the performance in relation to network queue delay, smoothed Round Trip Time (sRTT), and throughput. The final phase discusses the possibility of achieving the optimum performance by combining various sets to provide researchers with clear and explicit guidelines to establish an adequate SCReAM behavior for the desired application. To the best of our knowledge, this is the first study that proposes a preliminary and comprehensive analysis of the SCReAM algorithm. Based on the proposed approach, when L4S/ECN is disabled, we reduced the network queue delay by 63.36% and increased the network throughput by 48.6% as compared to the results generated by the original design. In L4S/ECN-enabled mode, the network queue delay is reduced by 16.17% while the network throughput increased by 93%.

2.
Sensors (Basel) ; 23(2)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36679582

RESUMO

As the Internet of Things (IoT) concept materialized worldwide in complex ecosystems, the related data security and privacy issues became apparent. While the system elements and their communication paths could be protected individually, generic, ecosystem-wide approaches were sought after as well. On a parallel timeline to IoT, the concept of distributed ledgers and blockchains came into the technological limelight. Blockchains offer many advantageous features in relation to enhanced security, anonymity, increased capacity, and peer-to-peer capabilities. Although blockchain technology can provide IoT with effective and efficient solutions, there are many challenges related to various aspects of integrating these technologies. While security, anonymity/data privacy, and smart contract-related features are apparently advantageous for blockchain technologies (BCT), there are challenges in relation to storage capacity/scalability, resource utilization, transaction rate scalability, predictability, and legal issues. This paper provides a systematic review on state-of-the-art approaches of BCT and IoT integration, specifically in order to solve certain security- and privacy-related issues. The paper first provides a brief overview of BCT and IoT's basic principles, including their architecture, protocols and consensus algorithms, characteristics, and the challenges of integrating them. Afterwards, it describes the survey methodology, including the search strategy, eligibility criteria, selection results, and characteristics of the included articles. Later, we highlight the findings of this study which illustrates different works that addressed the integration of blockchain technology and IoT to tackle various aspects of privacy and security, which are followed by a categorization of applications that have been investigated with different characteristics, such as their primary information, objective, development level, target application, type of blockchain and platform, consensus algorithm, evaluation environment and metrics, future works or open issues (if any), and further notes for consideration. Furthermore, a detailed discussion of all articles is included from an architectural and operational perspective. Finally, we cover major gaps and future considerations that can be taken into account when integrating blockchain technology with IoT.


Assuntos
Blockchain , Internet das Coisas , Ecossistema , Privacidade , Tecnologia , Segurança Computacional
3.
Ideggyogy Sz ; 72(11-12): 407-412, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31834684

RESUMO

BACKGROUND AND PURPOSE: Acute mortality rate of stroke in Hungary is significantly higher than in Western Europe, which is likely to be partially attributable to suboptimal treatment. METHODS: We examined the use of acute vascular imaging and mechanical thrombectomy for acute ischaemic stroke patients. We collected data on 20 consecutive patients from Hungarian stroke centers before 31st August 2016. RESULTS: Out of the reported 410 patients, 166 (40.4%) underwent CT angiography and 44 (10.7%) had mechanical thrombectomy. CONCLUSION: Only about 1/3 of acute ischaemic stroke patients eligible for thrombectomy actually had it. The underlying reasons include long onset-to-door time, low utilization of acute vessel imaging and a limited neuro-intervention capacity needing improvement.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/cirurgia , Angiografia por Tomografia Computadorizada/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/cirurgia , Trombectomia/métodos , Humanos , Hungria , Resultado do Tratamento
4.
Heliyon ; 10(3): e25516, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38333798

RESUMO

Atomic migration of silicon through grain boundaries of a thin polycrystalline Cu film and island formation on the Cu surface were studied in the temperature range of 403-520 K. Samples used in these experiments was prepared on Si(111) wafers by room temperature magnetron sputtering and they consisted of amorphous Si layer (80 nm) and polycrystalline Cu layer (40 nm). The silicon layer served as the source layer of diffusion, while the copper surface was the accumulation surface. Detection of Si atoms on the accumulation surface after penetration through the Cu layer was made by low energy ion scattering spectroscopy and the grain boundary diffusion coefficient DGB was determined from the appearance time. The depth distribution of Si in the Cu film was analysed by secondary neutral mass spectroscopy. From this depth distribution, DGB was also determined. By scanning probe microscope and electron microscope measurements, it was experimentally detected that Si atoms on the Cu surface did not form a continuous layer. Instead, amorphous Si islands were formed at the accumulation surface with surface protrusions in their centres.

5.
Urol Ann ; 14(1): 102-104, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35197714

RESUMO

Vesicovaginal fistula (VVF) is the most common genitourinary fistula associated with significant, detrimental impact on the quality of life. Surgical repair of VVF may be complex requiring tissue interposition techniques to bring fresh blood supply, minimize recurrence, and improve functional outcomes. The international literature is scarce regarding complications related to interposition tissue. However, caution is particularly recommended in selecting the tissue interposition technique to avoid unexpected and frustrating problems. We present a 57-year-old woman following multiple failed transvaginal and transabdominal VVF repairs involving a labium majus skin island flap (Lehoczky flap) after radical hysterectomy for cervical cancer.

6.
J Vasc Res ; 47(3): 214-20, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-19893318

RESUMO

BACKGROUND/AIMS: In our previous study, impaired visually evoked flow velocity response was demonstrated in young chronic smokers. Our aim was to study whether impaired cerebrovascular reactivity is reversible 6-18 months after smoking cessation. METHODS: Flow velocity changes, evoked by visual stimulus, were recorded in the posterior cerebral arteries in 15 smokers, 15 former smokers and 15 nonsmokers. The stimulation protocol consisted of 10 cycles with a resting phase of 20 s (baseline) and a stimulating phase of 40 s for each cycle. Relative changes of flow velocity were expressed in relation to baseline. Breath holding index, visual evoked potential and intima-media thickness were also examined. RESULTS: Repeated measures ANOVA revealed marked difference in the flow velocity time courses between the 3 groups (p < 0.01). The flow response was significantly worse in former smokers than in nonsmokers (p < 0.002), however, no significant difference was found between former and current smokers (p = 0.0556). CONCLUSION: This is the first transcranial Doppler study demonstrating long-term impairment of visually evoked cerebrovascular response after smoking cessation. These findings indicate that the impairment of neurovascular coupling caused by smoking is due to structural changes of the vessels, rather than acute effect of smoking.


Assuntos
Circulação Cerebrovascular , Estimulação Luminosa , Artéria Cerebral Posterior/fisiopatologia , Abandono do Hábito de Fumar , Fumar/efeitos adversos , Vias Visuais/fisiopatologia , Adulto , Velocidade do Fluxo Sanguíneo , Artéria Carótida Primitiva/diagnóstico por imagem , Potenciais Evocados Visuais , Feminino , Humanos , Masculino , Artéria Cerebral Posterior/diagnóstico por imagem , Artéria Cerebral Posterior/inervação , Recuperação de Função Fisiológica , Mecânica Respiratória , Fatores de Tempo , Ultrassonografia Doppler Transcraniana , Vasodilatação , Adulto Jovem
7.
Orv Hetil ; 151(7): 243-9, 2010 Feb 14.
Artigo em Húngaro | MEDLINE | ID: mdl-20133243

RESUMO

Fabry disease is a rare, X-linked lysosomal storage disorder that leads to accumulation of globotriaosylceramide in different tissues of the body. The disease is progressive, first symptoms usually present in childhood. Consequencies of the diseases are disability and premature death. The disease in females could be as severe as in males although women may also be asymptomatic. The possibility of enzyme replacement therapy has made it necessary to elaborate a comprehensive guideline for the diagnosis and treatment follow-up. The guideline was established by a Hungarian multi-disciplinary working group, consisting of physicians who are involved in health care of Fabry patients. Previous clinical studies, published materials, and recently established international treatment guidelines were reviewed by the group.


Assuntos
Doença de Fabry/diagnóstico , alfa-Galactosidase/administração & dosagem , alfa-Galactosidase/metabolismo , Sistema Cardiovascular/metabolismo , Sistema Cardiovascular/patologia , Cromatografia Líquida de Alta Pressão , Diagnóstico Diferencial , Doença de Fabry/complicações , Doença de Fabry/tratamento farmacológico , Doença de Fabry/enzimologia , Doença de Fabry/genética , Feminino , Trato Gastrointestinal , Humanos , Rim/metabolismo , Rim/patologia , Pulmão/fisiopatologia , Masculino , Espectrometria de Massas , Sistema Nervoso/metabolismo , Sistema Nervoso/patologia , Pele/metabolismo , Pele/patologia , Triexosilceramidas/sangue , Triexosilceramidas/metabolismo , Visão Ocular , alfa-Galactosidase/sangue , alfa-Galactosidase/genética
8.
Orv Hetil ; 151(31): 1243-51, 2010 Aug 01.
Artigo em Húngaro | MEDLINE | ID: mdl-20656661

RESUMO

Fabry disease is a rare, X-linked lysosomal storage disorder that leads to accumulation of globotriaosylceramide in different tissues of the body. The disease is progressive and the first symptoms usually present in childhood. Consequences of the disease are disability and premature death. The disease in females could be as severe as in males although women may be asymptomatic. The possibility of enzyme replacement therapy has made it necessary to elaborate a comprehensive guideline for the diagnosis and treatment follow-up. The guideline has been summarized by a Hungarian multi-disciplinary working group consisting of physicians who are involved in diagnosis and care of Fabry patients. Previous clinical studies, published articles, and recently established international treatment guidelines were reviewed by the group.


Assuntos
Doença de Fabry , alfa-Galactosidase/uso terapêutico , Ensaios Clínicos como Assunto , Terapia de Reposição de Enzimas , Doença de Fabry/complicações , Doença de Fabry/diagnóstico , Doença de Fabry/tratamento farmacológico , Doença de Fabry/enzimologia , Doença de Fabry/fisiopatologia , Feminino , Heterozigoto , Humanos , Masculino , Resultado do Tratamento , alfa-Galactosidase/genética
9.
Bioresour Technol ; 291: 121861, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31376666

RESUMO

The aim of this work was to investigate whether the agronomic traits of vermicompost prepared from partially stabilised sewage sludge digestate after thermophilic composting were more favourable than those of conventional compost. The effects of various additives (green waste, spent mushroom compost, wheat straw, biochar) were also tested after 1.5 months precomposting followed by 3 months vermicomposting with Eisenia fetida or by compost maturing. Vermicomposting did not result in significantly more intensive mineralisation than composting; the average organic carbon contents were 21.2 and 22.2% in vermicomposts and composts, respectively. Hence, the average total (N: 2.4%; P: 1.9%; K: 0.9%) and available (N: 160 mg/kg; P: 161 mg/kg; K: 0.8%) macronutrient concentrations were the same in both treatments. The processing method did not influence the organic matter quality (E4/E6) either. However, on average the concentration of the plant growth regulator kinetin was more than twice as high in vermicomposts.


Assuntos
Agroquímicos/metabolismo , Compostagem , Esgotos , Agroquímicos/análise , Animais , Oligoquetos/metabolismo , Esgotos/química
10.
J Clin Hypertens (Greenwich) ; 21(5): 658-667, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30980603

RESUMO

Beside the well-known complications of poorly controlled, long-standing hypertension, milder abnormalities induced by early-stage hypertension have also been described. In our study, the authors examined the reversibility of changes induced by early-stage hypertension. The authors performed laboratory testing, ambulatory blood pressure monitoring, carotid intima-media thickness (IMT) measurement, evaluation of stiffness parameters, assessment of various cardiac and cerebral hemodynamic parameters during head-up tilt table (HUTT) testing, and neuropsychological examinations in 49 recently diagnosed hypertensive patients. Following baseline assessment, antihypertensive therapy was commenced. After one year of therapy, lower IMT values were found. Pulse wave velocity showed a borderline significant decrease. During HUTT, several hemodynamic parameters improved. The patients performed better on neuropsychological testing and reached significantly lower scores on questionnaires evaluating anxiety. The present study shows that early vascular changes and altered cognitive function observed in newly diagnosed hypertensive patients may improve with promptly initiated antihypertensive management.


Assuntos
Cognição/efeitos dos fármacos , Hipertensão/complicações , Hipertensão/fisiopatologia , Adulto , Monitorização Ambulatorial da Pressão Arterial , Espessura Intima-Media Carotídea , Cognição/fisiologia , Estudos de Coortes , Feminino , Humanos , Hungria/epidemiologia , Hipertensão/tratamento farmacológico , Hipertensão/epidemiologia , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos Prospectivos , Análise de Onda de Pulso/métodos , Teste da Mesa Inclinada/métodos
11.
Cerebrovasc Dis ; 25(1-2): 170-5, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18212523

RESUMO

BACKGROUND: Both clinical and pathological alterations of the carotid arteries were correlated with Chlamydia pneumoniae infection in 67 acute ischemic stroke patients with severe neurological symptoms. METHODS: In the clinical study, intima-media thickness (IMT) of the common carotid arteries was determined in vivo by B-mode ultrasound measurement and C. pneumoniae-specific IgG and IgA responses were detected. In the pathological study, the absolute wall thickness of the common, internal and external carotid arteries was measured postmortem in specimens obtained at the autopsy of patients who died due to complications of acute stroke. In the atherosclerotic plaques of the autopsy specimens, C. pneumoniae genomic DNA was detected by polymerase chain reaction amplification. RESULTS: The Spearman's rho correlation coefficient of IMT with the average wall thickness of the common, internal and external carotid arteries was 0.51 (p = 0.002), 0.34 (p = 0.052) and 0.58 (p < 0.001), respectively. Anti-C. pneumoniae IgG and IgA antibodies were detected in 43 (73%) and 29 (49%) patients, but neither antibody marker correlated with IMT (median: 0.91 mm in IgG positives vs. 0.90 mm in IgG negatives, p = 0.86; 0.88 mm in IgA positives vs. 0.90 mm in IgA negatives, p = 0.53). The presence of C. pneumoniae DNA was detected in the carotid plaques of 21 (54%) of the 39 tested patients, independently of either IMT values or the average wall thickness of all carotid arteries. CONCLUSIONS: In acute ischemic stroke patients, C. pneumoniae infection was frequently detected in the arteriosclerotic plaques of the carotid arteries but it did not correlate with the severity of carotid arteriosclerosis.


Assuntos
Isquemia Encefálica/complicações , Doenças das Artérias Carótidas/microbiologia , Doenças das Artérias Carótidas/patologia , Artéria Carótida Primitiva , Chlamydophila pneumoniae/isolamento & purificação , Acidente Vascular Cerebral/complicações , Idoso , Idoso de 80 Anos ou mais , Autopsia , Isquemia Encefálica/microbiologia , Isquemia Encefálica/patologia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Acidente Vascular Cerebral/microbiologia , Acidente Vascular Cerebral/patologia , Túnica Íntima/patologia , Túnica Média/patologia
12.
J Neurol Sci ; 257(1-2): 149-54, 2007 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-17321550

RESUMO

The activation-flow coupling describes a mechanism, which adapts local cerebral blood flow in accordance with the underlying neuronal activity. It was suggested that the mechanism helps in differentiation between Alzheimer and vascular type of dementia. We combined EEG and Doppler techniques and assessed integrity of the activation-flow coupling in the occipital cortex utilizing a visual stimulation task. Alzheimer patients (MMSE: 18+/-8 points, DemTect 5+/-4 points) without signs of vascular lesions on a MRI scan and vascular demented patients (MMSE: 20+/-6 points, DemTect 6+/-3 points; MRI Fazekas score 7+/-3 points) were compared with data from an age-matched control group. Evoked flow velocity responses in the posterior cerebral artery were analysed according to a control system model specifying the parameters gain, attenuation, natural frequency and rate time. Evoked potentials were analysed for the N(75)-P(100) amplitude difference. Vascular demented patients exhibited a significant decreased gain parameter and increased attenuation parameter indicating severe cerebrovascular dysfunction. Also, the potential amplitudes were significantly decreased indicating neuronal damage due to the vascular disease process. Alzheimer patients did not differ in parameters as compared to the control group supporting other reports of intact occipital function at this stage of disease. Simultaneous assessment of electrical as well as vascular integrity might help in differentiating the most frequent forms of dementia.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Circulação Cerebrovascular/fisiologia , Demência Vascular/diagnóstico por imagem , Lobo Occipital/diagnóstico por imagem , Artéria Cerebral Posterior/diagnóstico por imagem , Idoso , Doença de Alzheimer/metabolismo , Doença de Alzheimer/fisiopatologia , Demência Vascular/metabolismo , Demência Vascular/fisiopatologia , Diagnóstico Diferencial , Eletroencefalografia/métodos , Metabolismo Energético/fisiologia , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Degeneração Neural/diagnóstico por imagem , Degeneração Neural/metabolismo , Degeneração Neural/fisiopatologia , Testes Neuropsicológicos , Lobo Occipital/metabolismo , Lobo Occipital/fisiopatologia , Estimulação Luminosa , Artéria Cerebral Posterior/fisiopatologia , Valor Preditivo dos Testes , Ultrassonografia Doppler Transcraniana/métodos
13.
Mol Cell Biol ; 24(18): 8154-66, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15340076

RESUMO

Cholesterol uptake and efflux are key metabolic processes associated with macrophage physiology and atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor alpha (LXRalpha) have been linked to the regulation of these processes. It remains to be identified how activation of these receptors is connected and regulated by endogenous lipid molecules. We identified CYP27, a p450 enzyme, as a link between retinoid, PPARgamma, and LXR signaling. We show that the human CYP27 gene is under coupled regulation by retinoids and ligands of PPARs via a PPAR-retinoic acid receptor response element in its promoter. Induction of the enzyme's expression results in an increased level of 27-hydroxycholesterol and upregulation of LXR-mediated processes. Upregulated CYP27 activity also leads to LXR-independent elimination of CYP27 metabolites as an alternative means of cholesterol efflux. Moreover, human macrophage-rich atherosclerotic lesions have an increased level of retinoid-, PPARgamma-, and LXR-regulated gene expression and also enhanced CYP27 levels. Our findings suggest that nuclear receptor-regulated CYP27 expression is likely to be a key integrator of retinoic acid receptor-PPARgamma-LXR signaling, relying on natural ligands and contributing to lipid metabolism in macrophages.


Assuntos
Macrófagos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Esteroide Hidroxilases/genética , Animais , Arteriosclerose/enzimologia , Arteriosclerose/metabolismo , Células Cultivadas , Colestanotriol 26-Mono-Oxigenase , Proteínas de Ligação a DNA , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Humanos , Hidroxicolesteróis/metabolismo , Ligantes , Receptores X do Fígado , Macrófagos/efeitos dos fármacos , Camundongos , Receptores Nucleares Órfãos , Regiões Promotoras Genéticas , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores do Ácido Retinoico/metabolismo , Receptor alfa de Ácido Retinoico , Receptores X de Retinoides , Retinoides/farmacologia , Transdução de Sinais , Fatores de Transcrição/agonistas , Fatores de Transcrição/metabolismo , Transcrição Gênica
14.
Ultrasound Med Biol ; 33(8): 1171-8, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17466442

RESUMO

Increased common carotid artery (CCA) intima-media thickness (IMT) measured by B-mode ultrasound is an early marker of the atherosclerotic process. Arterial calcification is not clearly understood. Using the particle-induced X-ray emission (PIXE) method, we have looked for the location in the artery wall where calcium accumulated in the early phase of atherosclerosis. Twelve segments of CCAs of deceased stroke patients were investigated. In-vivo, carotid duplex ultrasound was performed with bilateral CCA IMT measurement at plaque-free sections. During autopsy, segments of carotid arteries were collected and filled under pressure with a stained histologic embedding material. The frozen arteries were cut into 60-microm-thick slices. Calcium distribution maps from the segments of arteries were determined by PIXE method. IMT measured by ultrasound and calcium distribution maps measured by PIXE were compared. In our cross-sectional study, using the PIXE analysis and ultrasound images, we could demonstrate early calcium accumulation in the media layer. Our results have also shown a significant relationship between calcium content of distributional maps measured by PIXE analysis and corresponding IMT on B-mode ultrasound images of human CCAs.


Assuntos
Calcinose/diagnóstico por imagem , Cálcio/análise , Artéria Carótida Primitiva/diagnóstico por imagem , Estenose das Carótidas/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Calcinose/metabolismo , Calcinose/patologia , Artéria Carótida Primitiva/química , Artéria Carótida Primitiva/patologia , Estenose das Carótidas/metabolismo , Estenose das Carótidas/patologia , Estudos Transversais , Feminino , Humanos , Masculino , Túnica Íntima/diagnóstico por imagem , Túnica Íntima/patologia , Túnica Média/diagnóstico por imagem , Túnica Média/patologia , Ultrassonografia Doppler Dupla/métodos
15.
J Neurol ; 253(1): 58-64, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16096820

RESUMO

BACKGROUND: Alzheimer's disease (AD) leads to a degeneration of the nucleus basalis of Meynert and thus to decreased cholinergic tonus in the brain. The transcription of endothelial nitric oxide synthase depends on an adequate cholinergic innervation of microvessels and vasoregulative abnormalities have been reported in AD. We investigated activation-flow coupling to study the role of acetylcholine esterase inhibition (AChEI) on vasoregulative function. METHODS: A functional transcranial Doppler approach was used to measure the visually evoked flow velocity response in the posterior cerebral artery in AD patients who had no vascular risk factors. The diagnosis of AD was made according to the ICD10/DSMIIIR-criteria. After baseline recording the effect of four weeks 5mg donepezil and then four weeks 10 mg was investigated. Doppler data were evaluated with a control system approach to obtain dynamic properties of vasoregulation and were compared with a healthy control group. RESULTS: AD patients showed an increased damping (0.64 +/- 0.2; p = 0.007 vs. control) in evoked responses and lower resting flow velocity levels (40 +/- 13 cm/s; p = 0.06 vs. control), which were restored in a dose-dependent manner under AChEI (0.4 +/- 0.2; 44 +/- 11 cm/s). CONCLUSIONS: AD is associated with a functional vasoregulative deficit possibly due to decreased levels of the endothelial nitric oxide synthase. Augmenting levels with AChEI normalized flow regulation possibly leading to a better blood supply to active neurons.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/fisiopatologia , Circulação Cerebrovascular/efeitos dos fármacos , Inibidores da Colinesterase/uso terapêutico , Indanos/uso terapêutico , Piperidinas/uso terapêutico , Idoso , Análise de Variância , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Donepezila , Ecocardiografia Doppler/métodos , Feminino , Humanos , Masculino , Entrevista Psiquiátrica Padronizada/estatística & dados numéricos
16.
Ultrasound Med Biol ; 32(8): 1171-80, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16875952

RESUMO

Simultaneous assessment of electrical as well as hemodynamic responses in visual stimulation tasks is a relatively new approach to investigate activation-flow coupling in humans. To investigate the relation of both signals, we compared visually evoked potentials (VEP) with evoked flow velocity responses in the posterior cerebral artery by performing different visual stimulation tasks in healthy students. Check sizes and flickering frequency of a checkerboard pattern and the radial visual field section of a dartboard pattern were varied. VEPs were expressed in amplitude differences. Hemodynamic changes were given in terms of a control system model specifying the gain, attenuation, natural frequency and rate time parameters. From the typical VEP amplitude differences, we found the early N75-P100 amplitude difference significantly correlated to the gain parameter of the hemodynamic response. Both parameters increased with higher complexity of the checkerboard pattern and increasing visual field sections, whereas they remained nearly stable in the chosen frequency range. To corroborate the hypothesis of a tight coupling, further studies have to prove if the strength of this coupling could be used in clinical conditions.


Assuntos
Potenciais Evocados Visuais , Estimulação Luminosa , Ultrassonografia Doppler Transcraniana , Adulto , Análise de Variância , Velocidade do Fluxo Sanguíneo , Eletroencefalografia , Feminino , Humanos , Masculino , Análise de Regressão
17.
Ideggyogy Sz ; 59(11-12): 433-7, 2006 Nov 20.
Artigo em Húngaro | MEDLINE | ID: mdl-17203880

RESUMO

The vascular diseases (myocardial infarct, stroke, peripheral occlusive disease) have a common pathophysiological background, the arteriosclerosis, that impairs the autoregulation of cerebral vessels, decreases the endothelium mediated flow in the peripheral vessels. Therefore the assessment of the vascular damage or the follow-up of therapy need a complex and simultaneous approach. Currently the morphological and functional changes in the vascular system can be investigated with separated measuring systems, focusing either to cardiac or cerebral parameters (intermittent blood pressure measurement, ECG, cerebral blood flow by transcranial Doppler e.g.). Our purpose is to establish a complex non-invasive system for the simultaneous measurement and comparison of cardiac/cerebral/peripheral hemodynamics. The hemodynamic parameters in hypertensive patients are examined with transcranial Doppler and cardiac monitoring during tilt-table test. Intima-media thickness, flow-mediated dilatation in brachial artery, augmentation index and pulse wave velocity are also measured. The measurement will be repeated after 6 and 12 months follow-up. Our preliminary results are similar to those found in the literature, that proves the reliability of our complex noninvasive hemodynamic system. It is assumed, that 12 months antihypertensive therapies with ACE inhibitors, calcium antagonist etc. might result in different effects on different vascular parameters. Our system enables the individualization of antihypertensive therapy.


Assuntos
Doenças Vasculares/diagnóstico , Doenças Vasculares/fisiopatologia , Adulto , Inibidores da Enzima Conversora de Angiotensina/administração & dosagem , Anti-Hipertensivos/administração & dosagem , Velocidade do Fluxo Sanguíneo , Artéria Braquial/fisiopatologia , Circulação Cerebrovascular , Circulação Coronária , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Pulsátil , Fluxo Sanguíneo Regional , Teste da Mesa Inclinada , Túnica Íntima/patologia , Túnica Média/patologia , Ultrassonografia Doppler Transcraniana , Resistência Vascular , Vasodilatação
18.
Biosystems ; 141: 45-54, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26911807

RESUMO

The paper is aimed at a methodological development in biological pest control. The considered one pest two-agent system is modelled as a verticum-type system. Originally, linear verticum-type systems were introduced by one of the authors for modelling certain industrial systems. These systems are hierarchically composed of linear subsystems such that a part of the state variables of each subsystem affect the dynamics of the next subsystem. Recently, verticum-type system models have been applied to population ecology as well, which required the extension of the concept a verticum-type system to the nonlinear case. In the present paper the general concepts and technics of nonlinear verticum-type control systems are used to obtain biological control strategies in a two-agent system. For the illustration of this verticum-type control, these tools of mathematical systems theory are applied to a dynamic model of interactions between the egg and larvae populations of the sugarcane borer (Diatraea saccharalis) and its parasitoids: the egg parasitoid Trichogramma galloi and the larvae parasitoid Cotesia flavipes. In this application a key role is played by the concept of controllability, which means that it is possible to steer the system to an equilibrium in given time. In addition to a usual linearization, the basic idea is a decomposition of the control of the whole system into the control of the subsystems, making use of the verticum structure of the population system. The main aim of this study is to show several advantages of the verticum (or decomposition) approach over the classical control theoretical model (without decomposition). For example, in the case of verticum control the pest larval density decreases below the critical threshold value much quicker than without decomposition. Furthermore, it is also shown that the verticum approach may be better even in terms of cost effectiveness. The presented optimal control methodology also turned out to be an efficient tool for the "in silico" analysis of the cost-effectiveness of different biocontrol strategies, e.g. by answering the question how far it is cost-effective to speed up the reduction of the pest larvae density, or along which trajectory this reduction should be carried out.


Assuntos
Algoritmos , Modelos Biológicos , Mariposas/parasitologia , Controle Biológico de Vetores/métodos , Vespas/fisiologia , Animais , Análise Custo-Benefício , Ecossistema , Feminino , Interações Hospedeiro-Parasita , Larva/parasitologia , Óvulo/parasitologia , Controle Biológico de Vetores/economia , Densidade Demográfica , Reprodutibilidade dos Testes
19.
J Clin Pharmacol ; 45(9): 1048-54, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16100299

RESUMO

A double-blind, prospective, randomized, placebo-controlled clinical trial was carried out to test the acute and long-term hemodynamical and beneficial cognitive effects of the vasoactive agent vinpocetine on patients suffering from multiple cerebral infarcts by means of functional transcranial Doppler examinations and by neuropsychological tests. Twenty-six patients (17 men, 9 women) with multiple cerebral infarctions, aged between 50 and 83 years (mean age+/-SD=63.4+/-9.39 years) were examined, 14 of whom received vinpocetine and 12 placebo. The functional transcranial Doppler included breath-holding tests, finger movement, word fluency, and picture-discrimination tasks. Twenty-five patients were assessed by neuropsychological battery. No serious side effect was found in the vinpocetine group. The flow velocities were significantly lower in the acute phase after breath holding in the vinpocetine group than in the placebo group. Three months later, the vinpocetine patients did not show any significant worsening in digit span backward test, while the placebo group did. No other significant differences in the neuropsychological test could be detected between the treatment and the placebo groups. Longer lasting and higher dosage of vinpocetine therapy is suggested to prove its potential effect.


Assuntos
Encéfalo/efeitos dos fármacos , Infarto Cerebral/tratamento farmacológico , Fármacos Neuroprotetores/uso terapêutico , Nootrópicos/uso terapêutico , Alcaloides de Vinca/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Circulação Cerebrovascular/efeitos dos fármacos , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fatores de Tempo
20.
J Med Chem ; 45(24): 5260-79, 2002 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-12431053

RESUMO

Carbamate derivatives of N-propargylaminoindans (Series I) and N-propargylphenethylamines (Series II) were synthesized via multistep procedures from the corresponding hydroxy precursors. The respective rasagiline- and selegiline-related series were designed to combine inhibitory activities of both acetylcholine esterase (AChE) and monoamine oxidase (MAO) by virtue of their carbamoyl and propargylamine pharmacophores. Each compound was tested for these activities in vitro in order to find molecules with similar potencies against each enzyme. Compounds with such dual AChE and MAO inhibitory activities are expected to have potential for the treatment of Alzheimer's disease. The observed SAR also offers insight into the requirements of the active sites on these enzymes. A carbamate moiety was found to be essential for AChE inhibition, which was absent in the corresponding hydroxy precursors. The propargyl group caused 2-70-fold decrease in AChE inhibitory activity (depending on the position of the carbamoyl group) of Series I, but had little or no effect in Series II. Thus, the 6- and 7-carbamyloxyphenyls in Series I were either equipotent to, or slightly (2- to 5-fold) less active as AChE inhibitors than, the corresponding compounds in Series II, while the 4-carbamyloxyphenyls were more potent. The presence of the carbamate moiety in 6- and 7-carbamyloxyphenyls of Series I, considerably decreased MAO-A and -B inhibitory activity, compared to that of the parent hydroxy analogues, while the opposite was true for Series II. Thus, the 6- and 7-carbamyloxyphenyls in Series I were 2-3 orders of magnitude weaker MAO inhibitors while the 4- carbamyloxyphenyls were equipotent with the corresponding compounds in Series II. In both series, N-methylation of the propargylamine enhanced the MAO (A and B equally) inhibitory activities and decreased the AChE inhibitory activity. Two candidates belonging to the indan and tetralin ring systems (24c, 27b) and one phenethylamine (53d) were identified as possible leads for further development based on the following criteria: (a) comparable AChE and MAO-B inhibitory activities, (b) good to moderate AChE inhibitory activity, and (c) lack of strong MAO-A selectivity. However, it is likely that these compounds will be metabolized to the corresponding phenols, with inhibitory activities against AChE and/or MAO-A or -B, different from those of the parent carbamates. Thus, the apparent enzyme inhibition will be a result of the combined inhibition of all of these individual metabolites. The results of our ongoing in vivo screening programs will be published elsewhere.


Assuntos
Acetilcolinesterase/química , Inibidores da Colinesterase/química , Indanos/química , Inibidores da Monoaminoxidase/química , Monoaminoxidase/química , Pargilina/análogos & derivados , Fenetilaminas/química , Doença de Alzheimer/tratamento farmacológico , Animais , Sítios de Ligação , Butirilcolinesterase/química , Carbamatos/síntese química , Carbamatos/química , Bovinos , Humanos , Indanos/síntese química , Modelos Moleculares , Pargilina/síntese química , Pargilina/química , Fenetilaminas/síntese química , Propilaminas/síntese química , Propilaminas/química , Relação Estrutura-Atividade
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