Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 143
Filtrar
4.
Br J Dermatol ; 175(5): 930-936, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27169607

RESUMO

BACKGROUND: Mindfulness, defined as purposively and nonjudgementally paying attention in the present moment, could be used within psychosocial interventions to reduce the distress associated with social anxiety and avoidance found in many skin conditions. However, little is known about the relationship between naturally occurring levels of mindfulness and distress in dermatology patients. OBJECTIVES: To examine the relationship between mindfulness and psychosocial distress in a dermatological population. It was hypothesized that higher levels of mindfulness would be associated with lower levels of social anxiety, anxiety, depression and skin shame, and with better quality of life. METHODS: Adult dermatology outpatients (n = 120) from one hospital completed items assessing subjective severity, skin shame, fear of negative evaluation, anxiety and depression, quality of life, and levels of mindfulness. RESULTS: Considering depression, 14% reported mild, 5% moderate and 2·5% severe symptoms. For anxiety, 22% reported mild, 23% moderate and 6% severe symptoms. In addition, 33·4% reported clinically significant social anxiety. After controlling for subjective severity, mindfulness explained an additional 19% of the variance in depression, 39% in anxiety, 41% in social anxiety, 13% in skin shame and 6% in dermatological quality of life. One specific facet of mindfulness (acting with awareness) was found to be the most consistent predictor of distress. CONCLUSIONS: The findings indicate that higher levels of mindfulness are associated with lower distress. This suggests that facilitating mindfulness may be helpful in reducing distress in dermatology patients, and the use of mindfulness techniques warrants further investigation.


Assuntos
Atenção Plena , Qualidade de Vida , Dermatopatias/psicologia , Estresse Psicológico/etiologia , Transtorno Depressivo/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fobia Social/etiologia , Vergonha
6.
Eur J Phys Rehabil Med ; 50(3): 355-62, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24518145

RESUMO

BACKGROUND: In today's health care environment where resources are scarce discharge planning is an important component of resource allocation. Knowledge of the factors that influence discharge disposition is fundamental to such planning. Further, return to home is an important outcome metric related to the effectiveness of a stroke rehabilitation program. AIM: To test the hypothesis that the patients who have a caregiver at home willing to participate in the care of the patient discharged from a stroke rehabilitation unit are more likely to be discharged home given other predictive factors being the same. DESIGN: Retrospective cohort study using binary logistic regression analysis with outcome as discharge home vs. discharge not home after in-patient stroke rehabilitation. SETTING: Hamilton Health Sciences multidisciplinary integrated stroke program unit. POPULATION: During this period, 276 patients were admitted to the integrated stroke unit, of which 268 patients were living in the community prior to hospitalization. The remaining eight patients were admitted from a care facility, such as a nursing home or assisted living facility. Since a sample size of eight is too small, these patients were excluded from the analysis. As such, the analysis is based on the 268 patients who were living at home prior to the onset of stroke. METHODS: The data points collected during the study period were age, gender, days from stroke onset to rehabilitation unit admission, pre-stroke living arrangement (lived alone vs. lived with spouse, partner, or another family member), FIMTM at admission, type of stroke, laterality of impairment, and discharge destination (i.e., private dwelling vs. nursing home, assisted living facility, or back to acute care). RESULTS: As established by a number of previous studies, the most significant predictors of home as discharge destination was admission FIMTM. However, the second most important predictive factor for home discharge was prestroke living arrangement (lived alone vs lived with spouse/partner/other family member) as hypothesized by the authors. CONCLUSION: Literature is rich with studies showing functional independence to be the most important predictor of home as discharge disposition but our analysis shows that pre-stroke living arrangement, i.e., lived alone vs lived not alone is also an important predictor for patients to be discharged home after stroke rehabilitation. CLINICAL REHABILITATION IMPACT: If current discharge planning relies on the availability of a caregiver at home after discharge from in-patient stroke rehabilitation then it may be worthwhile to include these caregivers in the inpatient rehabilitation process, to prepare them for their loved one's return home. Additionally, once the patient is discharged home more resources should be made available to support caregivers in the community. This may include more home healthcare personnel training and availability along with respite care.


Assuntos
Cuidadores/provisão & distribuição , Pacientes Internados , Alta do Paciente , Recuperação de Função Fisiológica , Centros de Reabilitação/organização & administração , Reabilitação do Acidente Vascular Cerebral , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Tempo de Internação/tendências , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Fatores Socioeconômicos , Acidente Vascular Cerebral/fisiopatologia
7.
Neuroscience ; 200: 74-90, 2012 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-22056599

RESUMO

Brain-derived neurotrophic factor (BDNF) has been characterized as a potent modulator of neural plasticity in both the brain and spinal cord. The present experiments use an in vivo model system to demonstrate that training with controllable stimulation increases spinal BDNF expression and engages a BDNF-dependent process that promotes adaptive plasticity. Spinally transected rats administered legshock whenever one hind limb is extended (controllable stimulation) exhibit a progressive increase in flexion duration. This simple form of response-outcome (instrumental) learning is not observed when shock is given independent of leg position (uncontrollable stimulation). Uncontrollable electrical stimulation also induces a lasting effect that impairs learning for up to 48 h. Training with controllable shock can counter the adverse consequences of uncontrollable stimulation, to both prevent and reverse the learning deficit. Here it is shown that the protective and restorative effect of instrumental training depends on BDNF. Cellular assays showed that controllable stimulation increased BDNF mRNA expression and protein within the lumbar spinal cord. These changes were associated with an increase in the BDNF receptor TrkB protein within the dorsal horn. Evidence is then presented that these changes play a functional role in vivo. Application of a BDNF inhibitor (TrkB-IgG) blocked the protective effect of instrumental training. Direct (intrathecal) application of BDNF substituted for instrumental training to block both the induction and expression of the learning deficit. Uncontrollable stimulation also induced an increase in mechanical reactivity (allodynia), and this too was prevented by BDNF. TrkB-IgG blocked the restorative effect of instrumental training and intrathecal BDNF substituted for training to reverse the deficit. Taken together, these findings outline a critical role for BDNF in mediating the beneficial effects of controllable stimulation on spinal plasticity.


Assuntos
Adaptação Fisiológica/fisiologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Condicionamento Operante/fisiologia , Regulação da Expressão Gênica/fisiologia , Plasticidade Neuronal/fisiologia , Medula Espinal/metabolismo , Análise de Variância , Animais , Comportamento Animal , Fator Neurotrófico Derivado do Encéfalo/genética , Estimulação Elétrica/efeitos adversos , Regulação da Expressão Gênica/efeitos dos fármacos , Hiperalgesia/metabolismo , Hiperalgesia/patologia , Imunoglobulina G/farmacologia , Masculino , Plasticidade Neuronal/efeitos dos fármacos , Limiar da Dor/efeitos dos fármacos , Fosfopiruvato Hidratase/metabolismo , Estimulação Física , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptor trkB/imunologia , Receptor trkB/metabolismo , Fatores de Tempo
8.
Neurobiol Aging ; 32(7): 1273-85, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19720431

RESUMO

Computational modeling predicts that the hippocampus plays an important role in the ability to apply previously learned information to novel problems and situations (referred to as the ability to generalize information or simply as 'transfer learning'). These predictions have been tested in humans using a computer-based task on which individuals with hippocampal damage are able to learn a series of complex discriminations with two stimulus features (shape and color), but are impaired in their ability to transfer this information to newly configured problems in which one of the features is altered. This deficit occurs despite the fact that the feature predictive of the reward (the relevant information) is not changed. The goal of the current study was to develop a mouse analog of transfer learning and to determine if this new task was sensitive to pathological changes in a mouse model of AD. We describe a task in which mice were able to learn a series of concurrent discriminations that contained two stimulus features (odor and digging media) and could transfer this learned information to new problems in which the irrelevant feature in each discrimination pair was altered. Moreover, we report age-dependent deficits specific to transfer learning in APP+PS1 mice relative to non-transgenic littermates. The robust impairment in transfer learning may be more sensitive to AD-like pathology than traditional cognitive assessments in that no deficits were observed in the APP+PS1 mice on the widely used Morris water maze task. These data describe a novel and sensitive paradigm to evaluate mnemonic decline in AD mouse models that has unique translational advantages over standard species-specific cognitive assessments (e.g., water maze for rodent and delayed paragraph recall for humans).


Assuntos
Doença de Alzheimer/genética , Hipocampo/fisiopatologia , Deficiências da Aprendizagem/genética , Transtornos da Memória/genética , Transferência de Experiência/fisiologia , Doença de Alzheimer/psicologia , Precursor de Proteína beta-Amiloide/deficiência , Precursor de Proteína beta-Amiloide/genética , Animais , Modelos Animais de Doenças , Feminino , Humanos , Deficiências da Aprendizagem/psicologia , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/psicologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Presenilina-1/deficiência , Presenilina-1/genética , Pesquisa Translacional Biomédica/métodos , Pesquisa Translacional Biomédica/tendências
9.
Oncogene ; 30(5): 521-34, 2011 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-20838383

RESUMO

Many cancer cells contain more than two centrosomes, which imposes a potential for multipolar mitoses, leading to cell death. To circumvent this, cancer cells develop mechanisms to cluster supernumerary centrosomes to form bipolar spindles, enabling successful mitosis. Disruption of centrosome clustering thus provides a selective means of killing supernumerary centrosome-harboring cancer cells. Although the mechanisms of centrosome clustering are poorly understood, recent genetic analyses have identified requirements for both actin and tubulin regulating proteins. In this study, we demonstrate that the integrin-linked kinase (ILK), a protein critically involved in actin and mitotic microtubule organization, is required for centrosome clustering. Inhibition of ILK expression or activity inhibits centrosome clustering in several breast and prostate cancer cell lines that have centrosome amplification. Furthermore, cancer cells with supernumerary centrosomes are significantly more sensitive to ILK inhibition than cells with two centrosomes, demonstrating that inhibiting ILK offers a selective means of targeting cancer cells. Live cell analysis shows ILK perturbation leads cancer cells to undergo multipolar anaphases, mitotic arrest and cell death in mitosis. We also show that ILK performs its centrosome clustering activity in a focal adhesion-independent, but centrosome-dependent, manner through the microtubule regulating proteins TACC3 and ch-TOG. In addition, we identify a specific TACC3 phosphorylation site that is required for centrosome clustering and demonstrate that ILK regulates this phosphorylation in an Aurora-A-dependent manner.


Assuntos
Centrossomo/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Aurora Quinases , Compostos Azo/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular , Linhagem Celular Tumoral , Citocinese/efeitos dos fármacos , Feminino , Imunofluorescência , Humanos , Masculino , Microscopia de Fluorescência , Proteínas Associadas aos Microtúbulos/genética , Fosforilação , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Ligação Proteica , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Pirazóis/farmacologia , Interferência de RNA , Fuso Acromático/efeitos dos fármacos , Fuso Acromático/metabolismo
10.
Br J Cancer ; 102(3): 561-9, 2010 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-20051957

RESUMO

BACKGROUND: Tumours contain hypoxic regions that select for an aggressive cell phenotype; tumour hypoxia induces metastasis-associated genes. Treatment refractory patients with metastatic cancer show increased numbers of circulating tumour cells (CTCs), which are also associated with disease progression. The aim of this study was to examine the as yet unknown relationship between hypoxia and CTCs. METHODS: We generated human MDA-MB-231 orthotopic xenografts and, using a new technology, isolated viable human CTCs from murine blood. The CTCs and parental MDA-MB-231 cells were incubated at 21 and 0.2% (hypoxia) oxygen, respectively. Colony formation was assayed and levels of hypoxia- and anoxia-inducible factors were measured. Xenografts generated from CTCs and parental cells were compared. RESULTS: MDA-MB-231 xenografts used to generate CTCs were hypoxic, expressing hypoxia factors: hypoxia-inducible factor1 alpha (HIF1alpha) and glucose transporter protein type 1 (GLUT1), and anoxia-induced factors: activating transcription factor 3 and 4 (ATF3 and ATF4). Parental MDA-MB-231 cells induced ATF3 in hypoxia, whereas CTCs expressed it constitutively. Asparagine synthetase (ASNS) expression was also higher in CTCs. Hypoxia induced ATF4 and the HIF1alpha target gene apelin in CTCs, but not in parental cells. Hypoxia induced lower levels of carbonic anhydrase IX (CAIX), GLUT1 and BCL2/adenovirus E1B 19-KD protein-interacting protein 3 (BNIP3) proteins in CTCs than in parental cells, supporting an altered hypoxia response. In chronic hypoxia, CTCs demonstrated greater colony formation than parental cells. Xenografts generated from CTCs were larger and heavier, and metastasised faster than MDA-MB-231 xenografts. CONCLUSION: CTCs show an altered hypoxia response and an enhanced aggressive phenotype in vitro and in vivo.


Assuntos
Hipóxia Celular , Células Neoplásicas Circulantes/patologia , Fator 3 Ativador da Transcrição/genética , Fator 4 Ativador da Transcrição/genética , Animais , Linhagem Celular Tumoral , Feminino , Humanos , Neoplasias Pulmonares/secundário , Camundongos , Camundongos Endogâmicos NOD , Transplante de Neoplasias , Células Neoplásicas Circulantes/metabolismo , Fenótipo , Transplante Heterólogo
11.
Breast Cancer Res Treat ; 123(2): 397-404, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19949854

RESUMO

Recent advances in the study of the tumor microenvironment have revealed significant interaction between tumor cells and their surrounding stroma in model systems. We have previously shown that two distinct stromal signatures derived from a macrophage (CSF1) response and a fibroblastic (DTF-like) response are present in subsets of invasive breast cancers and show a correlation with clinical outcome. In the present study we explore whether these signatures also exist in the stroma of ductal carcinoma in situ (DCIS). We studied the signatures by both gene expression profile analysis of a publically available data set of DCIS and by immunohistochemistry (IHC) on a tissue microarray of DCIS and invasive breast cancer cases. Both the gene expression and immunohistochemical data show that the macrophage response and fibroblast expression signatures are present in the stroma of subsets of DCIS cases. The incidence of the stromal signatures in DCIS is similar to the incidence in invasive breast cancer that we have previously reported. We also find that the macrophage response signature is associated with higher grade DCIS and cases which are ER and PR negative, whereas the fibroblast signature was not associated with any clinicopathologic features in DCIS. A comparison of 115 matched cases of DCIS and invasive breast cancer found a correlation between the type of stromal response in DCIS and invasive ductal carcinoma (IDC) within the same patient for both the macrophage response and the fibroblast stromal signatures (P = 0.03 and 0.08, respectively). This study is a first characterization of these signatures in DCIS. These signatures have significant clinicopathologic associations and tend to be conserved as the tumor progresses from DCIS to invasive breast cancer.


Assuntos
Biomarcadores Tumorais/análise , Neoplasias da Mama/química , Neoplasias da Mama/genética , Carcinoma Ductal de Mama/química , Carcinoma Ductal de Mama/genética , Carcinoma Intraductal não Infiltrante/química , Carcinoma Intraductal não Infiltrante/genética , Células Estromais/química , Biomarcadores Tumorais/genética , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Carcinoma Intraductal não Infiltrante/patologia , Progressão da Doença , Feminino , Fibroblastos/química , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica , Genótipo , Humanos , Imuno-Histoquímica , Macrófagos/química , Invasividade Neoplásica , Estadiamento de Neoplasias , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Células Estromais/patologia , Análise Serial de Tecidos
12.
Oncogene ; 29(6): 845-54, 2010 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-19901961

RESUMO

Leiomyosarcoma (LMS) is a soft tissue tumor with a significant degree of morphologic and molecular heterogeneity. We used integrative molecular profiling to discover and characterize molecular subtypes of LMS. Gene expression profiling was performed on 51 LMS samples. Unsupervised clustering showed three reproducible LMS clusters. Array comparative genomic hybridization (aCGH) was performed on 20 LMS samples and showed that the molecular subtypes defined by gene expression showed distinct genomic changes. Tumors from the 'muscle-enriched' cluster showed significantly increased copy number changes (P=0.04). A majority of the muscle-enriched cases showed loss at 16q24, which contains Fanconi anemia, complementation group A, known to have an important role in DNA repair, and loss at 1p36, which contains PRDM16, of which loss promotes muscle differentiation. Immunohistochemistry (IHC) was performed on LMS tissue microarrays (n=377) for five markers with high levels of messenger RNA in the muscle-enriched cluster (ACTG2, CASQ2, SLMAP, CFL2 and MYLK) and showed significantly correlated expression of the five proteins (all pairwise P<0.005). Expression of the five markers was associated with improved disease-specific survival in a multivariate Cox regression analysis (P<0.04). In this analysis that combined gene expression profiling, aCGH and IHC, we characterized distinct molecular LMS subtypes, provided insight into their pathogenesis, and identified prognostic biomarkers.


Assuntos
Perfilação da Expressão Gênica , Leiomiossarcoma/classificação , Leiomiossarcoma/genética , Biomarcadores Tumorais/metabolismo , Hibridização Genômica Comparativa , Genômica , Humanos , Imuno-Histoquímica , Leiomiossarcoma/diagnóstico , Leiomiossarcoma/metabolismo , Prognóstico , Análise Serial de Tecidos
13.
Neurobiol Aging ; 30(4): 646-55, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17889407

RESUMO

Loss of mnemonic function is among the earliest and most disconcerting consequences of the aging process. This study was designed to provide a comprehensive profile of spatial mnemonic abilities in male Fischer 344 (F344) rats across the lifespan. Young, middle-aged, and aged F344 rats were trained in spatial reference and working memory versions of the water maze task. There was a progressive age-related decline in spatial reference memory across the lifespan. Reliable individual differences were observed among aged rats, with some aged rats performing as well as young cohorts and others performing outside this range. An age-related delay-dependent decline was observed on a working memory version of the water maze task although no relationship between performance on reference and working memory tasks was present. Notably, middle-aged rats were impaired relative to young on both tasks. Together these data demonstrate that individual differences in spatial reference memory exist among aged F344 rats and provide novel data demonstrating an unrelated decline in working memory across the lifespan, suggesting that age-related mnemonic dysfunction may occur across multiple brain systems.


Assuntos
Envelhecimento/psicologia , Transtornos da Memória/fisiopatologia , Memória de Curto Prazo/fisiologia , Envelhecimento/fisiologia , Animais , Sinais (Psicologia) , Modelos Animais de Doenças , Progressão da Doença , Hipocampo/fisiopatologia , Longevidade/fisiologia , Masculino , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/diagnóstico , Rede Nervosa/fisiopatologia , Testes Neuropsicológicos , Orientação/fisiologia , Ratos , Ratos Endogâmicos F344 , Fatores Sexuais , Percepção Espacial/fisiologia
14.
Intern Med J ; 38(8): 624-8, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18808560

RESUMO

BACKGROUND: Informed consent is a mainstay of clinical practice, with both moral and legal forces. Material disclosure about extreme treatments, however, is unlikely to convey the full impact of the experience of treatment. Informed consent may be flawed under such circumstances. The aims of this study were to compare expressed satisfaction with pretreatment information to satisfaction after experiencing autologous stem cell transplantation for recurrent lymphoma. METHODS: A qualitative, narrative-based cohort study was conducted in a bone-marrow transplant unit of a teaching hospital at Westmead Hospital, Sydney, Australia. The cohort consisted of 10 transplant recipients and 9 of their nominated lay carers. The outcome measure was satisfaction expressed in narrative interviews at the time of transplantation and 3 months later. We used discourse-analytic techniques to examine the narratives. RESULTS: Both patients and carers expressed high satisfaction with the information given by individual clinicians and by speakers at a formal Information Day held before transplantation. At the first interview, neither patients nor carers commented much on the forthcoming ordeal of chemotherapy and bone marrow ablation, although all patients had undergone previous chemotherapy. At the second interview, the ordeal dominated the narratives and retrospective dissatisfaction with information was common. CONCLUSION: This study suggests that information about treatment theories and protocols can be satisfactorily communicated, but personal experience of suffering defies communication. This finding has serious implications for the practices involved in obtaining informed consent and for the very notion of informed consent.


Assuntos
Consentimento Livre e Esclarecido , Pesquisa Qualitativa , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Consentimento Livre e Esclarecido/normas , Masculino , Pessoa de Meia-Idade , Participação do Paciente/métodos , Satisfação do Paciente , Relações Médico-Paciente , Transplante de Células-Tronco/métodos , Transplante de Células-Tronco/normas
15.
J Clin Microbiol ; 46(6): 2109-11, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18400919

RESUMO

A total of 500 first-void urine specimens were tested for the presence of Chlamydia trachomatis and Neisseria gonorrhoeae nucleic acids using ProbeTec ET reagents on a Viper platform (BD Diagnostics, Mississauga, Ontario, Canada), Aptima Combo 2 reagents on a Tigris platform (Gen-Probe, Inc., San Diego, CA), and Abbott RealTime CT/NG reagents on an m2000 platform (Abbott Molecular Diagnostics, Des Plaines, IL). The performance of the three assays for detection of N. gonorrhoeae was comparable, but detection of C. trachomatis by the three assays showed more variation. All three platforms were suitable for the detection of C. trachomatis and N. gonorrhoeae, but additional factors, such as maximum daily specimen throughput, are important in evaluating automated systems for C. trachomatis and N. gonorrhoeae detection in high-volume laboratories.


Assuntos
Chlamydia trachomatis/isolamento & purificação , Neisseria gonorrhoeae/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico/métodos , Kit de Reagentes para Diagnóstico , Urina/microbiologia , Automação , Infecções por Chlamydia/microbiologia , Chlamydia trachomatis/genética , Gonorreia/microbiologia , Humanos , Neisseria gonorrhoeae/genética , Manejo de Espécimes/métodos
16.
Biophys J ; 95(3): 1075-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18424492

RESUMO

In response to a sound stimulus, the inner ear emits sounds called otoacoustic emissions. While the exact mechanism for the production of otoacoustic emissions is not known, active motion of individual hair cells is thought to play a role. Two possible sources for otoacoustic emissions, both localized within individual hair cells, include somatic motility and hair bundle motility. Because physiological models of each of these systems are thought to be poised near a Hopf bifurcation, the dynamics of each can be described by the normal form for a system near a Hopf bifurcation. Here we demonstrate that experimental results from three-frequency suppression experiments can be predicted based on the response of an array of noninteracting Hopf oscillators tuned at different frequencies. This supports the idea that active motion of individual hair cells contributes to active processing of sounds in the ear. Interestingly, the model suggests an explanation for differing results recorded in mammals and nonmammals.


Assuntos
Relógios Biológicos/fisiologia , Células Ciliadas Auditivas Internas/fisiologia , Modelos Biológicos , Emissões Otoacústicas Espontâneas/fisiologia , Animais , Simulação por Computador , Humanos
17.
Phys Rev E Stat Nonlin Soft Matter Phys ; 75(5 Pt 1): 051924, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17677115

RESUMO

A mathematical model describing the coupling between two independent amplification mechanisms in auditory hair cells is proposed and analyzed. Hair cells are cells in the inner ear responsible for translating sound-induced mechanical stimuli into an electrical signal that can then be recorded by the auditory nerve. In nonmammals, two separate mechanisms have been postulated to contribute to the amplification and tuning properties of the hair cells. Models of each of these mechanisms have been shown to be poised near a Hopf bifurcation. Through a weakly nonlinear analysis that assumes weak periodic forcing, weak damping, and weak coupling, the physiologically based models of the two mechanisms are reduced to a system of two coupled amplitude equations describing the resonant response. The predictions that follow from an analysis of the reduced equations, as well as performance benefits due to the coupling of the two mechanisms, are discussed and compared with published experimental auditory nerve data.


Assuntos
Células Ciliadas Auditivas/fisiologia , Audição/fisiologia , Mecanotransdução Celular/fisiologia , Modelos Biológicos , Simulação por Computador , Elasticidade , Estresse Mecânico
18.
Intern Med J ; 36(10): 665-9, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16958645

RESUMO

Exhortations to 'be positive' accompany many situations in life, either as a general injunction or in difficult situations where people are facing pressure or adversity. It is particularly evident in health care, where positive thinking has become an aspect of the way people are expected to 'do' illness in developed society. Positive thinking is framed both as a moral injunction and as a central belief system. It is thought to help patients cope emotionally with illness and to provide a biological benefit. Yet, the meanings, expectations and outcomes of positive thinking are infrequently questioned and the risks of positive thinking are rarely examined. We outline some of the latter and suggest that health professionals should exercise caution in both 'prescribing' positive thinking and in responding to patients and carers whose belief systems and feelings of obligation rest on it.


Assuntos
Papel do Médico , Reforço Psicológico , Papel do Doente , Pensamento/ética , Emoções Manifestas/ética , Humanos , Resolução de Problemas/ética
20.
Kidney Int ; 70(2): 306-14, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16760908

RESUMO

Mechanisms regulating pregnancy-induced changes in renal function are incompletely understood. Few candidate genes have been identified and data suggest that alternate mechanisms remain to be elucidated. Our objective was to screen thousands of genes expressed in kidneys from mice throughout gestation to identify possible key regulators of renal function during pregnancy. Mouse complementary DNA microarrays were used to screen for differences in expression during pregnancy in C57BL/6 mice. Interesting candidate genes whose expression varied with pregnancy were further analyzed by reverse transcription-PCR and Northern blot. Expression was localized by in situ hybridization and immunohistochemistry. Follow-up immunohistochemical analyses in archival human kidney sections from the fetus, non-pregnant, and pregnant women were also performed. Histidine decarboxylase (HDC), the enzyme that synthesizes histamine, was markedly upregulated in the mouse kidney during pregnancy. HDC expression localized to proximal tubule cells of fetal and adult mice. Females showed strong expression in the juxtamedullary zone before pregnancy and upregulation in the superficial cortical zone (SCZ) by mid-gestation. Histamine colocalized with HDC. Male mice showed only low HDC expression. Similar expression patterns were observed in human kidneys. Our results show that HDC expression and histamine production are increased in the SCZ during pregnancy. If histamine acts as a vasodilator, we speculate that increasing production in the SCZ may increase renal blood flow to this zone and recruit superficial cortical nephrons during pregnancy.


Assuntos
Regulação Enzimológica da Expressão Gênica , Histidina Descarboxilase/genética , Córtex Renal/enzimologia , Prenhez/fisiologia , Gravidez/fisiologia , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Feminino , Histidina Descarboxilase/metabolismo , Humanos , Lactente , Córtex Renal/embriologia , Túbulos Renais Proximais/embriologia , Túbulos Renais Proximais/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Néfrons/embriologia , Néfrons/enzimologia , Análise de Sequência com Séries de Oligonucleotídeos , Regulação para Cima/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...