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1.
Phys Chem Chem Phys ; 26(13): 10168-10182, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38495023

RESUMO

The innovative design of thin, multiphase flexible composite systems with good mechanical properties, low density and improved EMI shielding properties at low filler content has become a key area of research. In this work, we report the low temperature synthesis of three-dimensional ternary composites (PANI/NFO@CNTs and PANI/NFO@RGO) by oxidative chemical polymerization of aniline in the presence of two different binary composites, viz. NFO@CNTs and NFO@RGO. Enhanced impedance matching is achieved by varying the ratio of the carbon allotropes (CNTs and RGO) to the ferrite component. The synthesis of NFO, PANI/NFO@CNTs and PANI/NFO@RGO is validated by XRD and FTIR spectroscopy. Field emission scanning electron microscopy (FE-SEM) confirmed the synthesis of core-shell structures of PANI/NFO@CNTs and PANI/NFO@RGO, where the binary composites (NFO@CNTs and NFO@RGO) serve as a core onto which a tubular PANI layer was coated. Shielding effectiveness of 22.36 dB (99.41% attenuation) is exhibited by the ternary composite PANI/NFO@CNTs (8 : 1), while for PANI/NFO@RGO (20 : 1) a total shielding effectiveness of 31 dB equivalent to 99.92% attenuation was observed at a thickness of 2 mm. The ternary composite PANI/NFO@RGO (20 : 1) 4 mm showed a maximum SET of 43 dB corresponding to 99.996% attenuation of incident EM waves. The enhanced EMI shielding properties of the synthesized ternary composite systems are accredited to good impedance matching, effective dielectric and magnetic loss mechanisms and good conductivity, which facilitate multiple reflections and scattering of incident radiation.

2.
J Am Chem Soc ; 144(20): 9138-9148, 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35546521

RESUMO

Spin-crossover (SCO) materials display many fascinating behaviors including collective phase transitions and spin-state switching controlled by external stimuli, e.g., light and electrical currents. As single-molecule switches, they have been fêted for numerous practical applications, but these remain largely unrealized-partly because of the difficulty of switching these materials at high temperatures. We introduce a semiempirical microscopic model of SCO materials combining crystal field theory with elastic intermolecular interactions. For realistic parameters, this model reproduces the key experimental results including thermally induced phase transitions, light-induced spin-state trapping (LIESST), and reverse-LIESST. Notably, we reproduce and explain the experimentally observed relationship between the critical temperature of the thermal transition, T1/2, and the highest temperature for which the trapped state is stable, TLIESST, and explain why increasing the stiffness of the coordination sphere increases TLIESST. We propose strategies to design SCO materials with higher TLIESST: optimizing the spin-orbit coupling via heavier atoms (particularly in the inner coordination sphere) and minimizing the enthalpy difference between the high-spin (HS) and low-spin (LS) states. However, the most dramatic increases arise from increasing the cooperativity of the spin-state transition by increasing the rigidity of the crystal. Increased crystal rigidity can also stabilize the HS state to low temperatures on thermal cycling yet leave the LS state stable at high temperatures following, for example, reverse-LIESST. We show that such highly cooperative systems offer a realistic route to robust room-temperature switching, demonstrate this in silico, and discuss material design rationale to realize this.

3.
J Neurovirol ; 27(3): 463-475, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33983505

RESUMO

People with human immunodeficiency virus (HIV) often have neurocognitive impairment. People with HIV make riskier decisions when the outcome probabilities are known, and have abnormal neural architecture underlying risky decision making. However, ambiguous decision making, when the outcome probabilities are unknown, is more common in daily life, but the neural architecture underlying ambiguous decision making in people with HIV is unknown. Eighteen people with HIV and 20 controls completed a decision making task while undergoing functional magnetic resonance imaging scanning. Participants chose between a certain reward and uncertain reward with a known (risky) or unknown (ambiguous) probability of winning. There were three levels of risk: high, medium, and low. Ambiguous > risky brain activity was compared between groups. Ambiguous > risky brain activity was correlated with emotional/psychiatric functioning in people with HIV. Both groups were similarly ambiguity-averse. People with HIV were more risk-averse than controls and chose the high-risk uncertain option less often. People with HIV had hypoactivity in the precuneus, posterior cingulate cortex (PCC), and fusiform gyrus during ambiguous > medium risk decision making. Ambiguous > medium risk brain activity was negatively correlated with emotional/psychiatric functioning in individuals with HIV. To make ambiguous decisions, people with HIV underrecruit key regions of the default mode network, which are thought to integrate internally and externally derived information to come to a decision. These regions and related cognitive processes may be candidates for interventions to improve decision-making outcomes in people with HIV.


Assuntos
Tomada de Decisões , Giro do Cíngulo/fisiopatologia , Infecções por HIV/fisiopatologia , Lobo Parietal/fisiopatologia , Assunção de Riscos , Lobo Temporal/fisiopatologia , Adulto , Estudos de Casos e Controles , Feminino , Jogos Experimentais , Giro do Cíngulo/diagnóstico por imagem , Giro do Cíngulo/virologia , HIV/crescimento & desenvolvimento , HIV/patogenicidade , Infecções por HIV/diagnóstico por imagem , Infecções por HIV/psicologia , Infecções por HIV/virologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/virologia , Testes Psicológicos , Recompensa , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/virologia
4.
Neuropathol Appl Neurobiol ; 45(4): 380-397, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30252960

RESUMO

AIMS: Alzheimer's disease (AD) is characterized by degeneration of cholinergic basal forebrain (CBF) neurons in the nucleus basalis of Meynert (nbM), which provides the major cholinergic input to the cortical mantle and is related to cognitive decline in patients with AD. Cortical histone deacetylase (HDAC) dysregulation has been associated with neuronal degeneration during AD progression. However, whether HDAC alterations play a role in CBF degeneration during AD onset is unknown. We investigated global HDAC protein levels and nuclear HDAC2 immunoreactivity in tissue containing the nbM, changes and their association with neurofibrillary tangles (NFTs) during the progression of AD. METHODS: We used semi-quantitative western blotting and immunohistochemistry to evaluate HDAC and sirtuin (SIRT) levels in individuals that died with a premortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), mild/moderate AD (mAD) or severe AD (sAD). Quantitative immunohistochemistry was used to identify HDAC2 protein levels in individual cholinergic nbM nuclei and their colocalization with the early phosphorylated tau marker AT8, the late-stage apoptotic tau marker TauC3 and Thioflavin-S, a marker of ß-pleated sheet structures in NFTs. RESULTS: In AD patients, HDAC2 protein levels were dysregulated in the basal forebrain region containing cholinergic neurons of the nbM. HDAC2 nuclear immunoreactivity was reduced in individual cholinergic nbM neurons across disease stages. HDAC2 nuclear reactivity correlated with multiple cognitive domains and with NFT formation. CONCLUSIONS: These findings suggest that HDAC2 dysregulation contributes to cholinergic nbM neuronal dysfunction, NFT pathology, and cognitive decline during clinical progression of AD.


Assuntos
Doença de Alzheimer/metabolismo , Disfunção Cognitiva/metabolismo , Histona Desacetilase 2/metabolismo , Emaranhados Neurofibrilares/metabolismo , Doença de Alzheimer/patologia , Neurônios Colinérgicos/metabolismo , Disfunção Cognitiva/patologia , Progressão da Doença , Feminino , Humanos , Masculino , Emaranhados Neurofibrilares/patologia , Proteínas tau/metabolismo
6.
Transfus Med ; 27(1): 10-15, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27730692

RESUMO

OBJECTIVE: The aim of the study was to determine the frequency and reasons for donor deferral prior to the blood donation process in our population. BACKGROUND: Transfusion is an irreversible event that carries potential risks as well as benefits to the recipient. Therefore, donor selection prior to blood donation is one of the most important steps in ensuring the safety of blood and blood products. METHODS: A cross-sectional study was carried out at the blood bank department in our hospital from January 2012 to December 2014. All the blood donors who visited our department in the study period were included in this study. RESULTS: A total of 25 901 potential donations were recorded during the study period, comprising 24 309 (93·8%) replacement and 1592 (6·2%) voluntary donations. Females accounted for only 222 (0·9%) of potential donations. Deferral occurred in 3156 (12·2%) of attempts; 280 (1·1%) were permanently deferred, while 2876 (11·1%) were temporarily deferred. The most common reason for permanent deferral was a history of hepatitis B infection (n = 147, 4·7% of all deferrals). Major reasons for temporary donor deferral were low levels of haemoglobin (n = 971, 30·76%), low levels of platelets (n = 611, 19·35%) and previous history of jaundice (n = 192, 6·1%). CONCLUSIONS: This study reported a fairly similar pattern of donor deferrals as in other regional studies. Low haemoglobin levels and a history of hepatitis B infection were the most common factors for temporary and permanent donor deferrals, respectively.


Assuntos
Doadores de Sangue , Seleção do Doador/métodos , Adolescente , Adulto , Estudos Transversais , Seleção do Doador/organização & administração , Feminino , Hemoglobinas/metabolismo , Hepatite B/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Paquistão
7.
Ir Med J ; 110(5): 572, 2017 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-28737312

RESUMO

Apparent Life-Threatening Events (ALTEs) are a common presentation to paediatric hospitals and represent a significant cause of parental anxiety. Basic Life Support (BLS) training is recommended for all caregivers following ALTEs. This study aimed to assess the rate of caregiver BLS training and reviewed parents experience following discharge. Parents were interviewed by phone following discharge. Over the study period 25 children attended the Emergency Department with ALTE, 17/25 (68%) were trained and 13/17 (76%) were contactable for interview. All parents found training decreased their anxiety level and were interested in attending for re-training. BLS resuscitation was subsequently required by 2/13 (15%) of children. Non-medical grade monitors were in use by 10/13 (77%) of caregivers following discharge. Caregivers are eager to engage in BLS training and it effectively reduces their caregiver anxiety. We recommend an increase in instructor staff and use of group re-training post discharge.


Assuntos
Reanimação Cardiopulmonar/educação , Cuidados para Prolongar a Vida , Pais/educação , Alta do Paciente , Ansiedade/prevenção & controle , Criança , Serviço Hospitalar de Emergência , Humanos , Pais/psicologia
8.
Genet Mol Res ; 15(2)2016 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-27420957

RESUMO

Mitochondrial DNA (mtDNA) is an important tool used to explore ethnogenetics and the evolutionary history of human populations. In this study, hypervariable segment I (HVSI) from mtDNA was analyzed to establish the genetic lineage of the Hazarewal populations residing in the Mansehra and Abbottabad districts of Northern Pakistan. HVSI was extracted from genetic specimens obtained from 225 unrelated male and female individuals belonging to seven distinct Pakistani ethnic groups (31 Abbassis, 44 Awans, 38 Gujars, 16 Jadoons, 23 Karlals, 33 Syeds, and 40 Tanolis). Eighty-three haplogroups, 39 of which were unique, were identified; haplogroup H was predominantly represented (in 40% of the people), followed by haplogroups M (21.78%), R (16.89%), N (15.56%), L (3.11%), and HV (2.67%). The results revealed a sex-biased genetic contribution from putative West Eurasian, South Asian, and Sub-Saharan populations to the genetic lineage of Hazarewal ancestry, with the effect of Eurasians being predominant. The HVSI nucleotide sequences exhibited some characteristic deletion mutations between 16,022 and 16,193 bp, which is characteristic of specific ethnic groups. HVSI sequence homology showed that Hazarewal populations fall into three major clusters: Syeds and Awans sorted out into cluster I; Tanolis, Gujars, and Karlals segregated in cluster II; and Abbassis and Jadoons in cluster III. Here, we have reported the firsthand genetic information and evolutionary sketch of the selected populations residing alongside the historical Silk Route, which provides a baseline for collating the origin, route of migration, and phylogenetics of the population.


Assuntos
Povo Asiático/genética , DNA Mitocondrial/genética , Polimorfismo Genético , População/genética , Povo Asiático/etnologia , Evolução Molecular , Feminino , Deleção de Genes , Migração Humana , Humanos , Masculino , Paquistão
9.
Molecules ; 21(9)2016 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-27649120

RESUMO

Despite progressive research being done on drug therapy to treat breast cancer, the number of patients succumbing to the disease is still a major issue. Combinatorial treatment using different drugs and herbs to treat cancer patients is of major interest in scientists nowadays. Doxorubicin is one of the most used drugs to treat breast cancer patients. The combination of doxorubicin to other drugs such as tamoxifen has been reported. Nevertheless, the combination of doxorubicin with a natural product-derived agent has not been studied yet. Morinda citrifolia has always been sought out for its remarkable remedies. Damnacanthal, an anthraquinone that can be extracted from the roots of Morinda citrifolia is a promising compound that possesses a variety of biological properties. This study aimed to study the therapeutic effects of damnacanthal in combination with doxorubicin in breast cancer cells. Collectively, the combination of both these molecules enhanced the efficacy of induced cell death in MCF-7 as evidenced by the MTT assay, cell cycle, annexin V and expression of apoptosis-related genes and proteins. The effectiveness of doxorubicin as an anti-cancer drug was increased upon addition of damnacanthal. These results could provide a promising approach to treat breast cancer patients.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Neoplasias da Mama/tratamento farmacológico , Antraquinonas/química , Antraquinonas/farmacocinética , Protocolos de Quimioterapia Combinada Antineoplásica/química , Neoplasias da Mama/metabolismo , Doxorrubicina/química , Doxorrubicina/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Células MCF-7 , Morinda/química
10.
Ir Med J ; 109(7): 442, 2016 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-27834092

RESUMO

Acute urinary tract infections are common in children. Our aim was to establish whether peripheral blood tests correlate with urinary culture. We also examined the relationship between peripheral blood results and the length of stay (LOS) in children and adolescents with UTI. We studied 135 patients admitted with UTI, mean (SD) age 3.0 (4.1) years. Of these 135 patients, 16 (11.9%) had combined normal serum WCC, normal neutrophil count and CRP < 5 mg/L. In this group of patients, there was no significant association between LOS and serum WCC, serum neutrophil values, E. coli infection or CRP values (p value 0.51, 0.98, 0.87, 0.82, respectively).


Assuntos
Infecções Urinárias/sangue , Doença Aguda , Adolescente , Biomarcadores/sangue , Proteína C-Reativa/análise , Criança , Pré-Escolar , Escherichia coli , Infecções por Escherichia coli/sangue , Infecções por Escherichia coli/diagnóstico , Humanos , Lactente , Tempo de Internação , Contagem de Leucócitos , Infecções Urinárias/diagnóstico
11.
J Food Sci Technol ; 53(4): 1750-8, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27413203

RESUMO

The ancient grain is becoming enormously popular in modern food regimen in many countries; the higher proportion of α-linolenic acid makes chia the superb source of omega-3 fatty (about 65 % of the oil content). Omega-3 fatty acid has been associated with a large number of physiological functions in human body. Chia seed is a potential source of antioxidants with the presence of chlorogenic acid, caffeic acid, myricetin, quercetin, and kaempferol which are believed to have cardiac, hepatic protective effects, anti-ageing and anti-carcinogenic characteristics. It is also a great source of dietary fibre which is beneficial for the digestive system and controlling diabetes mellitus with higher concentration of beneficial unsaturated fatty acids, gluten free protein, vitamin, minerals and phenolic compounds. Therapeutic effects of chia in the control of diabetes, dyslipidaemia, hypertension, as anti-inflammatory, antioxidant, anti-blood clotting, laxative, antidepressant, antianxiety, analgesic, vision and immune improver is scientifically established.

12.
J Appl Microbiol ; 119(4): 1035-45, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26258580

RESUMO

AIM: This work was conducted to produce, purify and characterize biosurfactants from Aspergillus flavus AF612 isolated from citrus fruit. METHODS AND RESULTS: Biosurfactant named 'Uzmaq' was isolated from A. flavus AF612. The chemical characterization of the biosurfactant was conducted. Biosurfactant Uzmaq produced by A. flavus, was composed of methoxy phenyl oxime glycosides. Two molecular forms of the biosurfactant, Uzmaq-A and Uzmaq-B were isolated. Biological properties (antifungal activity) were evaluated. The fractions of the biosurfactant were isolated and their surface properties were analysed. Uzmaq-A and Uzmaq-B had critical micelle concentration (CMC) around 170 and 80 mg l(-1) , and lowered surface tension of water up to 20 and 25 m Nm(-1) respectively. The biosurfactants were stable at pH 3-12 and temperature up to 80°C. Growth and biosurfactant production kinetics were also analysed. CONCLUSION: Novel biosurfactant Uzmaq was produced from A. flavus, which was composed of methoxy phenyl oxime glycosides. The surface activity of Uzmaq was better than the maximum values of synthetic chemical surfactants. The biosurfactant showed antifungal activity and self-assembling properties. SIGNIFICANCE AND IMPACT OF THE STUDY: Aspergillus flavus AF612 can be used for commercial production of Uzmaq that may be employed for controlled drug release applications and bioremediation.


Assuntos
Aspergillus flavus/metabolismo , Tensoativos/química , Tensoativos/metabolismo , Aspergillus flavus/química , Cinética , Micelas , Propriedades de Superfície , Tensão Superficial , Temperatura
14.
Phys Chem Chem Phys ; 16(30): 16030-8, 2014 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-24963819

RESUMO

Co ions with 100 keV energy with a fluence of 1 × 10(15) cm(-2) are implanted into ZnO(0001) single crystals at 300 °C under vacuum. The resulting Co-implanted ZnO single crystals and the subsequent 750 °C and 900 °C annealed samples are analysed with respect to their structural, optical, electronic, magnetic and ac electrical properties. Photoluminescence and X-ray photoelectron spectroscopy results indicate the signatures of the Co(2+) state and its substitution at the tetrahedrally coordinated Zn-sites. X-ray diffraction and X-ray photoelectron spectroscopy identify the presence of the ZnCo2O4 and Co3O4 phases in the 900 °C annealed sample. By comparing the resistance response of the identified phases towards different magnetic environments, the impedance spectroscopy results successfully identify two magnetic phases (ZnCo2O4 and Co3O4) and a paramagnetic (CoZn) phase for the 750 °C and 900 °C annealed samples, implying the extrinsic nature of room temperature ferromagnetism. The observed ferromagnetism in each sample is not of single origin, instead the mutual effects of the secondary phases embedded in the paramagnetic host matrix are in competition with each other.

15.
Genet Mol Res ; 13(3): 6184-90, 2014 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-25117374

RESUMO

Genuine medicinal plant materials are very important for potential crude drug production, which can be used to cure many human diseases. DNA barcoding of medicinal plants is an effective way to identify adulterated or contaminated market materials, but it can be quite challenging to generate barcodes and analyze the data to determine discrimination power. The molecular phylogeny of a plant species infers its relationship to other species. We screened the various loci of the nuclear and chloroplast genome for the barcoding of Plectranthus asirensis, an endemic plant of Saudi Arabia. The chloroplast genome loci such as rps16 and rpoB showed maximum similarity to taxa of the same and other genera via BLAST of the National Center for Biotechnology Information (NCBI) GenBank database; hence, they are less preferable for the development of a DNA barcode. However, nrDNA-ITS and chloroplast loci rbcL and rpoC1 showed less similarity via BLAST of the NCBI GenBank database; therefore, they could be used for DNA barcoding for this species.


Assuntos
Código de Barras de DNA Taxonômico , Filogenia , Plectranthus/classificação , Plectranthus/genética , Madeira , DNA de Cloroplastos/genética , DNA Intergênico , DNA de Plantas , Dados de Sequência Molecular , Fenótipo , Plantas Medicinais , Locos de Características Quantitativas , RNA Ribossômico 5,8S/genética , Arábia Saudita
16.
Genet Mol Res ; 13(1): 1144-51, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24634170

RESUMO

Molecular markers, mainly DNA-based are potential tools for DNA barcoding and phylogenetic study. The plant species belonging to the Nepeta genus have important medicinal value because of the presence of nepetalactones, and they have been used to treat human diseases. We amplified nuclear and chloroplast gene loci to develop a DNA barcode and phylogenetic study of Nepeta deflersiana. Among the studied loci, psbA-trnH and rps16 showed less identity within the genus than the other loci using the Basic Local Alignment Search Tool of the National Center for Biotechnology Information GenBank database. These loci can be used for the development of a DNA barcode to identify and preserve the identity of this species. We also constructed the phylogram of N. deflersiana and other Nepeta species retrieved from the GenBank database (nonredundant DNA-internal transcribed spacer). N. deflersiana was placed in the same clade as N. insaurica with a 99% bootstrap value.


Assuntos
Código de Barras de DNA Taxonômico/métodos , Nepeta/genética , Evolução Molecular , Marcadores Genéticos , Genoma de Cloroplastos , Genoma de Planta , Dados de Sequência Molecular , Nepeta/classificação , Filogenia , Folhas de Planta/genética , Análise de Sequência de DNA
17.
ScientificWorldJournal ; 2014: 940502, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25436237

RESUMO

Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.


Assuntos
Resinas Sintéticas/síntese química , Temperatura , Triazinas/síntese química , Triazinas/metabolismo , Resinas Sintéticas/metabolismo
19.
Ir Med J ; 107(1): 26-8, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24592647

RESUMO

This study investigates attitudes of parents and staff to medical students on paediatric wards in a Dublin teaching hospital. We invited 100 parents of patients and 30 staff involved in the care of children on the paediatric wards to participate. The majority of parents agreed or strongly agreed that they would be happy for a student to interview them (n = 87; (87%)), interview their child (80%) or examine their child (74%). Of 30 staff, 12 (40%) staff agreed that the presence of medical students on the ward increased their job satisfaction, 13 (43%) agreed or strongly agreed that medical student presence encouraged them to keep up to date with recent medical developments and 6 (20%) felt that it increased the quality of patient care. Attitudes of both parents and staff to medical students on paediatric wards are positive with both emphasising the need for professional behaviour.


Assuntos
Recursos Humanos de Enfermagem Hospitalar , Pais , Estudantes de Medicina , Adolescente , Atitude do Pessoal de Saúde , Criança , Pré-Escolar , Feminino , Hospitais de Ensino , Humanos , Lactente , Recém-Nascido , Relações Interpessoais , Irlanda , Satisfação no Emprego , Masculino
20.
Acta Biol Hung ; 65(3): 252-64, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25194729

RESUMO

The dynamical fluctuations of biological signals provide a unique window to construe the underlying mechanism of the biological systems in health and disease. Recent research evidences suggest that a wide class of diseases appear to degrade the biological complexity and adaptive capacity of the system. Heart rate signals are one of the most important biological signals that have widely been investigated during the last two and half decades. Recent studies suggested that heart rate signals fluctuate in a complex manner. Various entropy based complexity analysis measures have been developed for quantifying the valuable information that may be helpful for clinical monitoring and for early intervention. This study is focused on determining HRV dynamics to distinguish healthy subjects from patients with certain cardiac problems using symbolic time series analysis technique. For that purpose, we have employed recently developed threshold based symbolic entropy to cardiac inter-beat interval time series of healthy, congestive heart failure and atrial fibrillation subjects. Normalized Corrected Shannon Entropy (NCSE) was used to quantify the dynamics of heart rate signals by continuously varying threshold values. A rule based classifier was implemented for classification of different groups by selecting threshold values for the optimal separation. The findings indicated that there is reduction in the complexity of pathological subjects as compared to healthy ones at wide range of threshold values. The results also demonstrated that complexity decreased with disease severity.


Assuntos
Fibrilação Atrial/fisiopatologia , Eletrocardiografia , Insuficiência Cardíaca/fisiopatologia , Frequência Cardíaca , Processamento de Sinais Assistido por Computador , Adulto , Idoso , Fibrilação Atrial/diagnóstico , Estudos de Casos e Controles , Eletrocardiografia Ambulatorial , Entropia , Feminino , Insuficiência Cardíaca/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Índice de Gravidade de Doença , Fatores de Tempo , Adulto Jovem
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