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1.
J Ayurveda Integr Med ; 11(3): 329-335, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30685096

RESUMO

BACKGROUND: Currently, no vaccines or modern drugs are available for dengue and chikungunya and only symptomatic relief is provided to the patients. Siddha medicine, a traditional form of indigenous medical system uses specific polyherbal formulations for the treatment of such infections with considerable success. One such polyherbal formulation for the treatment of chikungunya and dengue is Nilavembu kudineer (NVK). The mechanistic details of this drug as an antiviral for chikungunya virus (CHIKV) and dengue virus (DENV) is poorly understood. OBJECTIVES: The current study was undertaken to study the efficacy of NVK as an antiviral formulation against CHIKV and DENV. MATERIALS AND METHODS: Cytotoxicity assays (MTT) were performed to determine the role of NVK as an antiviral during chikungunya and dengue infections in the following conditions-i). post infection, ii). during active infections and iii) protective, not allowing virus infection. RESULTS: It was observed that NVK provides protection against CHIKV and DENV-2 during active infection as well can help to prevent virus infection in the cells and it mainly depends on the cellular availability of drugs for maximum protection against both the infections. CONCLUSION: Our study establishes that extraction protocols are important to ensure maximum efficacy of NVK along with the time of addition of the drug during CHIKV and DENV infections in the cells. This study provides insights to the possible mode of action of NVK in in vitro condition during CHIKV and DENV infection.

2.
J Ayurveda Integr Med ; 10(2): 135-138, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30635248

RESUMO

A 42-year-old man with the complaints of left knee swelling, severe pain, difficult to stand was reported to Siddha Varmam division after a road accident. He was diagnosed as acute avulsion of Posterior cruciate ligament (PCL). It was diagnosed based on the history of trauma, knee pain and swelling after trauma, positive posterior drawer test and avulsion fracture shown by radiograph. He was treated with Siddha Varmam therapy and traditional bone setting. After a month of treatment, the PCL avulsion fracture got healed without any surgical interventions and patient able to walk normally. This case report summarises the novel Siddha Varmam therapy and traditional bone setting treatments for acute avulsion of PCL with bony fragment.

3.
Int J Behav Med ; 23(1): 63-70, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26025629

RESUMO

BACKGROUND: One of the biggest challenges in the spirituality, religiosity, and health field is to understand how patients and physicians from different cultures deal with spiritual and religious issues in clinical practice. PURPOSE: The present study aims to compare physicians' perspectives on the influence of spirituality and religion (S/R) on health between Brazil, India, and Indonesia. METHOD: This is a cross-sectional, cross-cultural, multi-center study carried out from 2010 to 2012, examining physicians' attitudes from two continents. Participants completed a self-rated questionnaire that collected information on sociodemographic characteristics, S/R involvement, and perspectives concerning religion, spirituality, and health. Differences between physicians' responses in each country were examined using chi-squared, ANOVA, and MANCOVA. RESULTS: A total of 611 physicians (194 from Brazil, 295 from India, and 122 from Indonesia) completed the survey. Indonesian physicians were more religious and more likely to address S/R when caring for patients. Brazilian physicians were more likely to believe that S/R influenced patients' health. Brazilian and Indonesians were as likely as to believe that it is appropriate to talk and discuss S/R with patients, and more likely than Indians. No differences were found concerning attitudes toward spiritual issues. CONCLUSION: Physicians from these different three countries had very different attitudes on spirituality, religiosity, and health. Ethnicity and culture can have an important influence on how spirituality is approached in medical practice. S/R curricula that train physicians how to address spirituality in clinical practice must take these differences into account.


Assuntos
Médicos , Religião e Medicina , Espiritualidade , Adulto , Atitude do Pessoal de Saúde/etnologia , Brasil , Comparação Transcultural , Estudos Transversais , Feminino , Humanos , Índia , Indonésia , Masculino , Médicos/psicologia , Médicos/estatística & dados numéricos , Inquéritos e Questionários
4.
Int Sch Res Notices ; 2015: 473296, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-27347522

RESUMO

Purna Cantirotaya Centuram (PCC), a herbometallic formulation of Siddha medicine, consists of mercury, sulphur, and gold, processed with red cotton flower and plantain stem pith juices. To evaluate its safety, acute and 28-day repeated oral toxicity studies were performed following OECD test guidelines 423 and 407, respectively. In acute study, PCC was administered orally at 5, 50, 300, and 2000 mg/kg body weight. Animals were observed for toxic signs for 14 days. Gross pathology was performed at the end of the study. In repeated dose toxicity study, PCC was administered at 2.5, 25, and 50 mg/kg body weight daily for 28 days. Satellite groups (control and high dose) were also maintained to determine the delayed onset toxicity of PCC. In acute toxicity study, no treatment related death or toxic signs were observed. It revealed that the LD50 cut-off value of PCC is between 2000 and 5000 mg/kg body weight. The repeated dose study did not show evidence of any treatment related changes in all observations up to the high dose level, when compared with the control. Histopathological examination revealed no abnormalities except mild hyperplasia of stomach in high dose group. This study provides scientific validation for the safety of PCC.

5.
J Relig Health ; 53(6): 1800-14, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24430129

RESUMO

Persons with mental illnesses in India and rest of developing world continue to consult religious/spiritual (R/S) healers or traditional, complementary and alternative medicine (TCAM) professionals prior to seeking psychiatric services that are devoid of spiritual components of care. We aim to understand TCAM and allopathic professionals' perspectives on patients' R/S needs within mental health services, cross-sectional study was conducted at five TCAM and two allopathic tertiary care hospitals in three different Indian states; 393 participants completed RSMPP, a self-administered, semi-structured survey questionnaire. Perspectives of TCAM and allopathic health professionals on role of spirituality in mental health care were compared. Substantial percentage, 43.7 % TCAM and 41.3 % allopathic, of participants believe that their patients approach R/S or TCAM practitioners for severe mental illness; 91.2 % of TCAM and 69.7 % of allopaths were satisfied with R/S healers (p = 0.0019). Furthermore, 91.1 % TCAM and 73.1 % allopaths (p = 0.000) believe that mental health stigma can be minimized by integrating with spiritual care services. Overall, 87 % of TCAM and 73 % of allopaths agreed to primary criterion variable: 'spiritual healing is beneficial and complementary to psychiatric care.' A quarter of allopaths (24.4 %) and 38 % of TCAM physicians reportedly cross-refer their grieving patients to religious/TCAM healer and psychiatrist/psychologist, respectively; on logistic regression, significant (p < 0.05) predictors were clinical interactions/references to r/s healers. Providing spiritual care within the setup of psychiatric institution will not only complement psychiatric care but also alleviate stigma against mental health services. Implications on developing spiritual care services like clinical chaplaincy are discussed.


Assuntos
Atitude do Pessoal de Saúde , Serviços de Saúde Mental , Terapias Espirituais , Estereotipagem , Adulto , Estudos Transversais , Feminino , Humanos , Índia , Masculino , Centros de Atenção Terciária
6.
J Relig Health ; 53(4): 1161-75, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23625126

RESUMO

Allopathic medical professionals in developed nations have started to collaborate with traditional, complementary, and alternative medicine (TCAM) to enquire on the role of religion/spirituality (r/s) in patient care. There is scant evidence of such movement in the Indian medical community. We aim to understand the perspectives of Indian TCAM and allopathic professionals on the influence of r/s in health. Using RSMPP (Religion, Spirituality and Medicine, Physician Perspectives) questionnaire, a cross-sectional survey was conducted at seven (five TCAM and two allopathic) pre-selected tertiary care medical institutes in India. Findings of TCAM and allopathic groups were compared. Majority in both groups (75% of TCAM and 84.6% of allopathic practitioners) believed that patients' spiritual focus increases with illness. Up to 58% of TCAM and allopathic respondents report patients receiving support from their religious communities; 87% of TCAM and 73% of allopaths believed spiritual healing to be beneficial and complementary to allopathic medical care. Only 11% of allopaths, as against 40% of TCAM, had reportedly received 'formal' training in r/s. Both TCAM (81.8%) and allopathic (63.7%) professionals agree that spirituality as an academic subject merits inclusion in health education programs (p = 0.0003). Inclusion of spirituality in the health care system is a need for Indian medical professionals as well as their patients, and it could form the basis for integrating TCAM and allopathic medical systems in India.


Assuntos
Atitude do Pessoal de Saúde , Terapias Complementares , Medicina Integrativa/métodos , Medicina Tradicional , Religião e Medicina , Espiritualidade , Adulto , Estudos Transversais , Feminino , Humanos , Índia , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Adulto Jovem
7.
Clin Radiol ; 68(7): 708-15, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23510619

RESUMO

AIM: To evaluate if diffusion-weighted imaging (DWI) is useful in characterizing liver lesions in patients with cirrhosis. MATERIALS AND METHODS: A retrospective review revealed 37 patients with cirrhosis who had 41 histologically proven hepatocellular carcinoma (HCC) lesions. Another 20 patents with cirrhosis had 29 solid nodules that remained stable for at least 12 months and were deemed to be benign hepatic nodules (BHN). Of the HCC lesions, 14 were well-differentiated (WD HCC), 20 were moderately differentiated, and seven were poorly differentiated histology. For all lesions, two reviewers analysed signal characteristics and made apparent diffusion coefficient value (ADC) measurements. RESULTS: Visual analysis of DWI was useful in that no HCC was hypointense and no BHN was hyperintense to liver. Visual analysis of DWI was not useful in separating WD HCC from higher grades. There was substantial overlap in ADC values of the HCC and BHN. Among HCC lesions, ADC values of more than 0.99 × 10(-3) mm(2)/s had sensitivity and specificity of 85% and 86% for reviewer 1, and 63% and 64% for reviewer 2 in diagnosing WD HCC. CONCLUSIONS: ADC measurements of BHN were higher than that of HCC, and the ADC values of WD HCC were higher than that of more aggressive grades of HCC. However, quantitative measurements may not help in determining the histological grade of individual cases of HCC.


Assuntos
Carcinoma Hepatocelular/patologia , Cirrose Hepática/patologia , Neoplasias Hepáticas/patologia , Adulto , Idoso , Carcinoma Hepatocelular/complicações , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Cirrose Hepática/complicações , Neoplasias Hepáticas/complicações , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Retrospectivos
8.
Comput Biol Chem ; 41: 10-7, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23131789

RESUMO

We examine the possibilities of various coupling mechanisms among a group of identical stochastic oscillators via Chemical Langevin formalism where each oscillator is modeled by stochastic model of testosterone (T) releasing pathway. Our results show that the rate of synchrony among the coupled oscillators depends on various parameters namely fluctuating factor, coupling constants [symbol; see text], and interestingly on system size. The results show that synchronization is achieved much faster in classical deterministic system rather than stochastic system. Then we do large scale simulation of such coupled pathways using stochastic simulation algorithm and the detection of synchrony is measured by various order parameters such as synchronization manifolds, phase plots etc and found that the proper synchrony of the oscillators is maintained in different coupling mechanisms and support our theoretical claims. We also found that the coupling constant follows power law behavior with the systems size (V) by [symbol; see text] ~ AV(-γ), where γ=1 and A is a constant. We also examine the phase transition like behavior in all coupling mechanisms that we have considered for simulation. The behavior of the system is also investigated at thermodynamic limit; where V → ∞, molecular population, N → ∞ but N/V → finite, to see the role of noise in information processing and found the destructive role in the rate of synchronization.


Assuntos
Modelos Biológicos , Testosterona/química , Testosterona/metabolismo , Algoritmos , Processos Estocásticos , Termodinâmica
9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 85(2 Pt 2): 027201, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22463360

RESUMO

In a chain of mutually coupled oscillators, the coupling threshold for synchronization between the outermost identical oscillators decreases when a type of impurity (in terms of parameter mismatch) is introduced in the inner oscillator(s). The outer oscillators interact indirectly via dynamic relaying, mediated by the inner oscillator(s). We confirm this enhancing of critical coupling in the chaotic regimes of the Lorenz system, in the Rössler system in the absence of coupling delay, and in the Mackey-Glass system with delay coupling. The enhancing effect is experimentally verified in the electronic circuit of Rössler oscillators.

10.
Clin Radiol ; 66(9): 845-52, 2011 09.
Artigo em Inglês | MEDLINE | ID: mdl-21771548

RESUMO

AIM: To assess the role of the hepatocellular phase on magnetic resonance imaging (MRI) following gadobenate in characterizing the grade of hepatocellular carcinoma (HCC) in cirrhotic patients. MATERIALS AND METHODS: A retrospective review of the MRI database from October 2004 to February 2009, performed for this Institutional Review Board-approved and Health Insurance Portability and Accountability Act (HIPAA)-complaint study, revealed 237 cirrhotic patients with focal liver lesions. Patients who had both a hepatocellular phase after gadobenate and pathological confirmation of HCC were included. Forty-six patients with 73 HCC were analysed independently by two reviewers for signal characteristics. Absolute contrast-to-noise ratio (CNR) and enhancement ratio (ER) were calculated. Univariate analysis, stepwise logistic regression analysis, and receiver operating characteristic curves (ROC) were performed. RESULTS: The mean age was 61.3 years (range 45 to 78 years). There were 11 females and 35 males, who had 22 well-differentiated (WD HCC), 35 moderately-differentiated (MD HCC), and 16 poorly-differentiated (PD HCC) hepatocellular carcinomas. On visual analysis of the hepatocellular phase, a hyperintense or isointense lesion had a sensitivity and specificity of 45% and 76%, respectively, for WD HCC. On quantitative analysis, the only significant predictor of the grade of HCC was the ER on the hepatocellular phase (p=0.019 and 0.001 for the two reviewers in logistic regression model). On ROC analysis, an ER of >13% was 47% sensitive and 89% specific in predicting WD HCC histology. CONCLUSION: Although the hepatocellular phase of gadobenate may help to differentiate some cases of WD HCC from the more aggressive grades, there is overlap between the different grades on qualitative and quantitative analysis.


Assuntos
Carcinoma Hepatocelular/diagnóstico , Meios de Contraste , Cirrose Hepática/diagnóstico , Neoplasias Hepáticas/diagnóstico , Imageamento por Ressonância Magnética/métodos , Meglumina/análogos & derivados , Compostos Organometálicos , Idoso , Carcinoma Hepatocelular/patologia , Diagnóstico Diferencial , Feminino , Humanos , Cirrose Hepática/patologia , Neoplasias Hepáticas/patologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Curva ROC , Estudos Retrospectivos
11.
Clin Radiol ; 66(9): 820-5, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21621199

RESUMO

AIM: To assess the value of diffusion-weighted imaging (DWI) in evaluating parenchymal disorders following orthotopic liver transplantation (OLT). MATERIALS AND METHODS: This institutional review board-approved, retrospective study measured the hepatic apparent diffusion coefficients (ADC) in patients following OLT. Those with vascular complications or within 3 months of OLT were excluded. A single-shot echoplanar sequence with b values of 50, 400 (or 500), and 800 s/mm(2) was performed. Liver biopsy specimens [performed with a median of 17 days after magnetic resonance imaging (MRI)] were recorded for the presence and severity of parenchymal disorders, such as acute cellular rejection, and recurrence of fibrosis in all patients, and the recurrence of viral hepatitis in patients with hepatitis C. ADC values were measured blinded to histology in 41 patients (33 males) who had 56 MRI scans. RESULTS: There was a significant difference in ADC values associated with a histological abnormality seen on core biopsy [n=43, mean (SD) ADC of 0.91 (0.15)×10(-3) mm(2)/s] and those associated with no histological abnormality [n=13, mean (SD) ADC of 1.11 (0.17)×10(-3) mm(2)/s; (p=0.003)]. ADC values did not predict any of the individual parenchymal disorders on logistic regression analysis. When the ADC value was <0.99×10(-3) mm(2)/s, there was a sensitivity and specificity of 85% and 72%, respectively, in predicting a parenchymal disorder (area under ROC curve=0.84; 95% CI 0.72 to 0.92). CONCLUSION: ADC measurements may help in deciding which patients require core liver biopsy after OLT. However, ADC values are not likely to be reliable in differentiating between the various parenchymal disorders.


Assuntos
Carcinoma Hepatocelular/diagnóstico , Cirrose Hepática/diagnóstico , Neoplasias Hepáticas/diagnóstico , Transplante de Fígado/efeitos adversos , Fígado/patologia , Idoso , Carcinoma Hepatocelular/patologia , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Cirrose Hepática/patologia , Neoplasias Hepáticas/patologia , Transplante de Fígado/patologia , Masculino , Curva ROC , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade
12.
J Eur Acad Dermatol Venereol ; 25(4): 398-402, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21371128

RESUMO

BACKGROUND: Post-inflammatory hyperpigmentation (PIH) is a common occurrence in patients with acne vulgaris, particularly in those with skin of colour. AIMS: A previous study has demonstrated the benefit of tretinoin (retinoic acid) in the treatment of PIH; however, there is currently no standard protocol to evaluate change in PIH following treatment. Based on these findings, we performed a pilot, exploratory, blinded, intraindividual-controlled methodology study that consisted of a photographic assessment protocol with facial mapping. MATERIALS AND METHODS: The study was based on a secondary analysis of a phase 4, community-based trial of 544 acne patients who were treated with tretinoin gel microsphere 0.04% or 0.1%. Only patients with Fitzpatrick types III-V (skin of colour) were included in the study; subjects with Fitzpatrick skin type VI were excluded because the photographic assessment did not allow for proper evaluation. RESULTS: Despite the small number of subjects evaluated (n=25), the results revealed consistent assessment of improvement in PIH between two independent graders (weighted κ=0.84). CONCLUSION: Further study with a larger population is recommended to validate the accuracy of this method.


Assuntos
Acne Vulgar/tratamento farmacológico , Dermatite/complicações , Fármacos Dermatológicos/uso terapêutico , Transtornos da Pigmentação/patologia , Tretinoína/uso terapêutico , Acne Vulgar/complicações , Fármacos Dermatológicos/efeitos adversos , Humanos , Fotografação , Transtornos da Pigmentação/induzido quimicamente , Transtornos da Pigmentação/complicações , Projetos Piloto , Tretinoína/efeitos adversos
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 81(4 Pt 2): 046213, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20481813

RESUMO

Time delay is introduced in the coupling between a pair of electrochemical cells. As coupling parameters are varied, the anodic current in the two cells oscillate in synchrony in regimes of periodic as well as chaotic dynamics. When the time delay is varied a phase-flip transition is observed: the relative phase between the synchronized oscillations changes abruptly by pi . This is accompanied by an experimentally measurable discontinuous change in the frequency of the synchronized oscillators.

14.
J Bone Joint Surg Br ; 92(4): 489-95, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20357323

RESUMO

The hip joint is commonly involved in multiple epiphyseal dysplasia and patients may require total hip replacement before the age of 30 years. We retrospectively reviewed nine patients (16 hips) from four families. The diagnosis of multiple epiphyseal dysplasia was based on a family history, genetic counselling, clinical features and radiological findings. The mean age at surgery was 32 years (17 to 63), with a mean follow-up of 15.9 years (5.5 to 24). Of the 16 hips, ten required revision at a mean of 12.5 years (5 to 15) consisting of complete revision of the acetabular component in three hips and isolated exchange of the liner in seven. No femoral component has loosened or required revision during the period of follow-up. With revision for any reason, the 15-year survival was only 11.4% (95% confidence interval 1.4 to 21.4). However, when considering revision of the acetabular shell in isolation the survival at ten years was 93.7% (95% confidence interval 87.7 to 99.7), reducing to 76.7% (95% confidence interval 87.7 to 98.7) at 15 and 20 years, respectively.


Assuntos
Artroplastia de Quadril/métodos , Osteocondrodisplasias/cirurgia , Adolescente , Adulto , Antropometria , Métodos Epidemiológicos , Humanos , Pessoa de Meia-Idade , Osteoartrite do Quadril/diagnóstico por imagem , Osteoartrite do Quadril/etiologia , Osteoartrite do Quadril/cirurgia , Osteocondrodisplasias/complicações , Osteocondrodisplasias/diagnóstico por imagem , Osteocondrodisplasias/genética , Linhagem , Falha de Prótese , Radiografia , Reoperação/métodos , Resultado do Tratamento , Adulto Jovem
15.
J Bone Joint Surg Br ; 91(11): 1466-71, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19880891

RESUMO

The management of osteoarthritis of the knee associated with patellar instability secondary to external tibial torsion > 45 degrees is challenging. Patellofemoral biomechanics in these patients cannot be achieved by intra-articular correction using standard techniques of total knee replacement. We reviewed seven patients (eight knees) with recurrent patellar dislocation and one with bilateral irreducible lateral dislocation who had undergone simultaneous total knee replacement and internal tibial derotational osteotomy. All had osteoarthritis and severe external tibial torsion. The mean follow-up was for 47.2 months (24 to 120). The mean objective and functional Knee Society scores improved significantly (p = 0.0001) from 29.7 and 41.5 pre-operatively to 71.4 and 73.5 post-operatively, respectively. In all patients the osteotomies healed and patellar stability was restored. Excessive external tibial torsion should be identified and corrected in patients with osteoarthritis and patellar instability. Simultaneous internal rotation osteotomy of the tibia and total knee replacement is a technically demanding but effective treatment for such patients.


Assuntos
Artroplastia do Joelho/métodos , Osteoartrite do Joelho/cirurgia , Osteotomia/métodos , Tíbia/cirurgia , Anormalidade Torcional/cirurgia , Feminino , Seguimentos , Humanos , Instabilidade Articular/diagnóstico por imagem , Instabilidade Articular/etiologia , Instabilidade Articular/cirurgia , Luxação do Joelho/diagnóstico por imagem , Luxação do Joelho/etiologia , Luxação do Joelho/cirurgia , Pessoa de Meia-Idade , Osteoartrite do Joelho/complicações , Radiografia , Recidiva , Rotação , Tíbia/diagnóstico por imagem , Anormalidade Torcional/complicações , Anormalidade Torcional/diagnóstico por imagem , Resultado do Tratamento
16.
J Bone Joint Surg Br ; 91(6): 812-4, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19483238

RESUMO

Osteogenesis imperfecta is a rare inherited disorder of connective tissue which may present with recurrent fractures which are prone to nonunion and malunion resulting in deformity. Some patients develop osteoarthritis of the hip. Formation of hyperplastic callus after recurrent fractures may deform the shape of the femur and preclude the use of standard implants at joint replacement. Replacement can thus be technically demanding. We present a case of bilateral hip replacement in a patient with osteogenesis imperfecta and hyperplastic callus which was treated by the use of long femoral allografts and cemented femoral stems.


Assuntos
Artroplastia de Quadril/métodos , Calo Ósseo/cirurgia , Fixação Intramedular de Fraturas/métodos , Osteogênese Imperfeita/cirurgia , Fêmur/transplante , Humanos , Masculino , Pessoa de Meia-Idade , Falha de Prótese , Reoperação , Resultado do Tratamento
17.
Phys Rev E Stat Nonlin Soft Matter Phys ; 75(3 Pt 2): 036222, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17500784

RESUMO

We present methods to detect the transitions from quasiperiodic to chaotic motion via strange nonchaotic attractors (SNAs). These procedures are based on the time needed by the system to recur to a previously visited state and a quantification of the synchronization of trajectories on SNAs. The applicability of these techniques is demonstrated by detecting the transition to SNAs or the transition from SNAs to chaos in representative quasiperiodically forced discrete maps. The fractalization transition to SNAs--for which most existing diagnostics are inadequate--is clearly detected by recurrence analysis. These methods are robust to additive noise, and thus can be used in analyzing experimental time series.

18.
Cancer Inform ; 2: 243-74, 2007 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-19458770

RESUMO

Molecular stratification of disease based on expression levels of sets of genes can help guide therapeutic decisions if such classifications can be shown to be stable against variations in sample source and data perturbation. Classifications inferred from one set of samples in one lab should be able to consistently stratify a different set of samples in another lab. We present a method for assessing such stability and apply it to the breast cancer (BCA) datasets of Sorlie et al. 2003 and Ma et al. 2003. We find that within the now commonly accepted BCA categories identified by Sorlie et al. Luminal A and Basal are robust, but Luminal B and ERBB2+ are not. In particular, 36% of the samples identified as Luminal B and 55% identified as ERBB2+ cannot be assigned an accurate category because the classification is sensitive to data perturbation. We identify a "core cluster" of samples for each category, and from these we determine "patterns" of gene expression that distinguish the core clusters from each other. We find that the best markers for Luminal A and Basal are (ESR1, LIV1, GATA-3) and (CCNE1, LAD1, KRT5), respectively. Pathways enriched in the patterns regulate apoptosis, tissue remodeling and the immune response. We use a different dataset (Ma et al. 2003) to test the accuracy with which samples can be allocated to the four disease subtypes. We find, as expected, that the classification of samples identified as Luminal A and Basal is robust but classification into the other two subtypes is not.

19.
Chaos ; 16(2): 023116, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16822019

RESUMO

We demonstrate a technique for the enhancement of chaos in a computational model of a periodically stimulated excitable neuron. "Anticontrol" of chaos is achieved through intermittent adaptive intervention, which is based on finite-time Lyapunov exponents measured from the time series. Our results suggest that an adaptive strategy for chaos anticontrol is viable for increasing the complexity in physiological systems that are typically both noisy and nonstationary.


Assuntos
Potenciais de Ação/fisiologia , Relógios Biológicos/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Periodicidade , Adaptação Fisiológica/fisiologia , Animais , Simulação por Computador , Estimulação Elétrica/métodos , Humanos , Modelos Estatísticos , Dinâmica não Linear
20.
Pediatr Neurosurg ; 42(3): 168-70, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16636619
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