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1.
Ann Oncol ; 26(6): 1110-1118, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25735316

RESUMO

BACKGROUND: Comprehensive molecular profiling led to the recognition of multiple prostate cancer (PCa) molecular subtypes and driving alterations, but translating these findings to clinical practice is challenging. PATIENTS AND METHODS: We developed a formalin-fixed paraffin-embedded (FFPE) tissue compatible integrative assay for PCa molecular subtyping and interrogation of relevant genetic/transcriptomic alterations (MiPC). We applied MiPC, which combines capture-based next generation sequencing and quantitative reverse transcription PCR (qRT-PCR), to 53 FFPE PCa specimens representing cases not well represented in frozen tissue cohorts, including 8 paired primary tumor and lymph node metastases. Results were validated using multiplexed PCR based NGS and Sanger sequencing. RESULTS: We identified known and novel potential driving, somatic mutations and copy number alterations, including a novel BRAF T599_V600insHT mutation and CYP11B2 amplification in a patient treated with ketoconazole (a potent CYP11B2 inhibitor). qRT-PCR integration enabled comprehensive molecular subtyping and provided complementary information, such as androgen receptor (AR) target gene module assessment in advanced cases and SPINK1 over-expression. MiPC identified highly concordant profiles for all 8 tumor/lymph node metastasis pairs, consistent with limited heterogeneity amongst driving events. MiPC and exome sequencing were performed on separately isolated conventional acinar PCa and prostatic small cell carcinoma (SCC) components from the same FFPE resection specimen to enable direct comparison of histologically distinct components. While both components showed TMPRSS2:ERG fusions, the SCC component exclusively harbored complete TP53 inactivation (frameshift variant and copy loss) and two CREBBP mutations. CONCLUSIONS: Our results demonstrate the feasibility of integrative profiling of routine PCa specimens, which may have utility for understanding disease biology and enabling personalized medicine applications.


Assuntos
Biomarcadores Tumorais/genética , Perfilação da Expressão Gênica/métodos , Neoplasias da Próstata/genética , Biópsia , Variações do Número de Cópias de DNA , Análise Mutacional de DNA , Estudos de Viabilidade , Fixadores , Formaldeído , Regulação Neoplásica da Expressão Gênica , Predisposição Genética para Doença , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Metástase Linfática , Masculino , Mutação , Inclusão em Parafina , Fenótipo , Polimorfismo de Nucleotídeo Único , Medicina de Precisão , Valor Preditivo dos Testes , Prognóstico , Neoplasias da Próstata/classificação , Neoplasias da Próstata/patologia , Neoplasias da Próstata/terapia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fixação de Tecidos
2.
Scand J Med Sci Sports ; 22(6): 804-15, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21599754

RESUMO

Lung cancer patients experience loss of physical capacity, dyspnea, pain, reduced energy and psychological distress. The aim of this study was to explore feasibility, health benefits and barriers of exercise in former sedentary patients with advanced stage lung cancer, non-small cell lung cancer (NSCLC) (III-IV) and small cell lung cancer (SCLC) (ED), undergoing chemotherapy. The intervention consisted of a hospital-based, supervised, group exercise and relaxation program comprising resistance-, cardiovascular- and relaxation training 4 h weekly, 6 weeks, and a concurrent unsupervised home-based exercise program. An explorative study using individual semi-structured interviews (n=15) and one focus group interview (n=8) was conducted among the participants. Throughout the intervention the patients experienced increased muscle strength, improvement in wellbeing, breathlessness and energy. The group exercise and relaxation intervention showed an adherence rate of 76%, whereas the patients failed to comply with the home-based exercise. The hospital-based intervention initiated at time of diagnosis encouraged former sedentary lung cancer patients to participation and was undertaken safely by cancer patients with advanced stages of disease, during treatment. The patients experienced physical, functional and emotional benefits. This study confirmed that supervised training in peer-groups was beneficial, even in a cancer population with full-blown symptom burden and poor prognosis.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/terapia , Terapia por Exercício , Neoplasias Pulmonares/terapia , Terapia de Relaxamento , Carcinoma de Pequenas Células do Pulmão/terapia , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/complicações , Carcinoma Pulmonar de Células não Pequenas/psicologia , Dispneia/etiologia , Dispneia/terapia , Terapia por Exercício/psicologia , Fadiga/etiologia , Fadiga/terapia , Estudos de Viabilidade , Feminino , Grupos Focais , Nível de Saúde , Humanos , Entrevistas como Assunto , Neoplasias Pulmonares/complicações , Neoplasias Pulmonares/psicologia , Masculino , Pessoa de Meia-Idade , Motivação , Força Muscular , Cooperação do Paciente , Terapia de Relaxamento/psicologia , Carcinoma de Pequenas Células do Pulmão/complicações , Carcinoma de Pequenas Células do Pulmão/psicologia
3.
Scand J Med Sci Sports ; 19(1): 55-66, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18266788

RESUMO

Cancer and treatment can negatively affect the body's performance and appearance. Exercise has been tested in a few studies for altered body image among middle-aged women with breast cancer. The aim of the study was to explore how young pre-cancer athletes of both genders experience disease- and treatment-related physical fitness and appearance changes while undergoing chemotherapy and participating in a 6-week group exercise intervention. A prospective, explorative study using semi-structured interviews was conducted before and at termination of the intervention. The study included 22 cancer patients (median age 28 years). The young athletes experienced a change from a high level of physical activity, body satisfaction and a positive self-identity to a low level of physical activity, body denial and a negative self-identity. In the program, the patients experienced increased physical strength and recapture of certain aspects of their former positive body perception. Deterioation of muscle functions caused by chemotherapy was particularly painful to these patients, independent of gender and age. Young physically active patients are heavily dependent on their physical capacity, body satisfaction and self-identity. This should be taken into account when designing programs to rehabilitate and encourage these patients through the often-strenuous antineoplastic treatments.


Assuntos
Exercício Físico/fisiologia , Neoplasias/tratamento farmacológico , Desempenho Psicomotor/fisiologia , Esportes , Sobreviventes , Adolescente , Adulto , Imagem Corporal , Dinamarca , Feminino , Processos Grupais , Humanos , Entrevistas como Assunto , Masculino , Força Muscular , Neoplasias/reabilitação , Estudos Prospectivos , Adulto Jovem
4.
J Dairy Sci ; 91(9): 3412-23, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18765600

RESUMO

The main objectives were to analyze milking-to-milking variability in milk yield, fat and protein percentages, and somatic cell count (SCC). Additional objectives were to investigate the factors that affect variation in milk fat percentage and to study the seasonal variations in milk, fat, and protein yields and SCC. A total of 16 farms (14 milked 2x and 2 milked 3x) across Canada participated in a 5-d milk-sampling study, with 27,328 milk samples collected and analyzed for fat and protein yields and SCC. Descriptive statistics for both 2x and 3x herds for milk yield and fat and protein percentages followed a typical pattern throughout lactation, and the somatic cell linear scores were higher in early lactation for first-lactation cows (4.7 vs. 3.8) but were higher at the end of lactation for cows in second lactation or greater (5.1 vs. 4.9). The 2x herds had higher milk yields in the morning (approximately 17 vs. approximately 14 kg), whereas the 3x herds had the lowest milk yields in the morning, and yields peaked at the evening milking (approximately 9 vs. approximately 11.2 kg). A herd management questionnaire was distributed to participating producers to investigate the relationship between management variables and variations in milk fat percentage over the 5-d sampling period. Data from the questionnaire determined that milking period had a significant effect on milk fat in 2x herds, with fat percentage 1.11% lower in the morning compared with the evening milking period. Seasonal differences in milk, fat, and protein yields were investigated in 910 cows on 3 farms, with 5,517 fat and 5,534 protein samples. The seasonal differences in fat yield [summer = 1.02 +/- 1.05 kg/d (SEM); winter = 1.19 +/- 1.05 kg/d] and protein yield (summer = 0.85 +/- 1.05 kg/d; winter = 0.96 +/- 1.05 kg/d) were significant only for first lactation. Understanding the variability in milk yield, fat and protein percentages, and SCC is important when making management decisions and in milk-recording programs.


Assuntos
Bovinos/fisiologia , Indústria de Laticínios , Gorduras/análise , Proteínas do Leite/análise , Animais , Contagem de Células , Feminino , Lactação , Modelos Lineares , Leite/química , Leite/citologia , Leite/metabolismo , Estações do Ano , Inquéritos e Questionários
5.
J Dairy Sci ; 90(10): 4684-92, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17881690

RESUMO

The objectives of this study were to compare the multiple trait prediction (MTP) model estimate of 305-d lactation yield with the 305-d daily milk yield data from on-farm automated meters and software and to examine the accuracy of electronic identification (ID). Twenty-four-hour milk and component yields are calculated by using milk weights and samples collected 8 to 10 times/yr by Dairy Herd Improvement (DHI) organizations. Daily milk weights were collected from cows on 20 Canadian farms that used parlor milking systems with electronic ID and that were enrolled in a regular DHI program. A total of 10,175 DHI test days from 1,103 cows with complete 305-d lactation yields were entered into the MTP model, and lactation yields were predicted. Test days were grouped into first, second, and third and greater lactations and within each lactation group, days in milk were categorized in 3 stages (5 to 60, 61 to 120, and 120 to 305 d in milk) for a total of 9 classes. Agreement analysis was used to compare the 305-d sum of daily milk to the MTP 305-d lactation yield predictions by using inputs from test days throughout the lactations. Results indicated that the MTP model overestimated lactation yields across all parity groups, ranging from 310 to 1,552 kg in parity 1, 640 to 2,000 kg in parity 2, and 567 to 1,476 kg in parity 3 and greater. A preliminary examination of electronic ID accuracy was conducted on 4 farms. Two electronic ID systems were examined for cow ID accuracy by verifying the ID number appearing in the parlor with the corresponding ear tag number. There were no ID errors on 3 of 4 farms tested and only a very small number of errors (3/80) on the fourth farm, indicating that the electronic ID systems used in milking parlors identify cows accurately.


Assuntos
Bovinos/fisiologia , Lactação/fisiologia , Leite/metabolismo , Sistemas de Identificação Animal/métodos , Sistemas de Identificação Animal/veterinária , Animais , Canadá , Indústria de Laticínios/métodos , Feminino , Análise de Regressão , Fatores de Tempo
6.
Bone Marrow Transplant ; 40(8): 793-800, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17704795

RESUMO

Substantial physical and functional deconditioning and diminished psychological wellbeing are all potential adverse effects of allogeneic stem cell transplantation (allo-HSCT). The aim of this study was to evaluate the feasibility, safety and benefits (physical and functional capacity) of a 4-6 week supervised and structured mixed-type exercise, progressive relaxation and psychoeducation programme in patients undergoing allo-HSCT. Nineteen patients were randomized to an intervention or a conventional care group (CC) and were tested for physical and functional capacity before admission and upon hospital discharge. In all, 14 patients completed all study requirements (74%) and no adverse reactions that could be attributed to the intervention were observed. At the time of discharge, the intervention group showed significant improvements in several muscle strength scores as compared to the CC group; chest press (P=0.023), leg extension (P=0.007) and isometric right knee flexor (P=0.033). The intervention proved feasible, safe and well tolerated in this small sample of patients undergoing allo-HSCT. An intervention of this type may be a useful strategy for maintaining or improving muscle strength, and minimizing loss of physical and functional capacity in patients undergoing allo-HSCT.


Assuntos
Terapia por Exercício , Educação de Pacientes como Assunto , Transplante de Células-Tronco/psicologia , Adolescente , Adulto , Terapia Combinada , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Terapia de Relaxamento/educação , Transplante Homólogo
7.
AJNR Am J Neuroradiol ; 28(5): 927-32, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17494672

RESUMO

BACKGROUND AND PURPOSE: To establish intraobserver and interobserver variability for regional measurement of CT brain perfusion (CTP) and to determine whether reproducibility can be improved by calculating perfusion ratios. MATERIALS AND METHODS: CTP images were acquired in 20 patients with unilateral symptomatic carotid artery stenosis (CAS). We manually drew regions of interest (ROIs) in the cortical flow territories of the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries and the basal ganglia in each hemisphere; recorded cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT); and calculated ratios of perfusion values between symptomatic and asymptomatic hemisphere. We assessed intraobserver and interobserver variability by performing a Bland-Altman analysis of the relative differences between 2 observations and calculated SDs of relative differences (SDD(rel)) as a measure of reproducibility. We used an F test to assess significance of differences between SDD(rel) of absolute CTP values and CTP ratios, and the Levine test to compare the 4 perfusion territories. RESULTS: MTT was the most reproducible parameter (SDD(rel)

Assuntos
Estenose das Carótidas/diagnóstico por imagem , Circulação Cerebrovascular , Tomografia Computadorizada por Raios X/estatística & dados numéricos , Tomografia Computadorizada por Raios X/normas , Idoso , Idoso de 80 Anos ou mais , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Estenose das Carótidas/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes
8.
Scand J Med Sci Sports ; 16(6): 403-11, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17121642

RESUMO

BACKGROUND: Over the past few years there has been a growing interest in the field of physical exercise in rehabilitation of cancer patients, leading to requirements for objective maximum physical capacity measurement (maximum oxygen uptake (VO(2max)) and one-repetition maximum (1RM)) to determine dose-response levels in different cancer diagnoses. AIM: To explore the patients' experiences of maximum physical capacity testing while concurrently undergoing chemotherapy and participating in a 6-week, 9 h weekly multidimensional exercise program. DESIGN AND METHOD: Prospective, exploratory study using semi-structured qualitative interviews conducted prior to and at termination of the program. The study included 100 patients (18-65 years, median 42 years) with or without residual disease and with mixed diagnoses. RESULTS: Following the intervention, cancer patients felt significantly safer in performing maximum physical capacity tests as these motivated them through self-perceived competitiveness and set a standard that served to encourage peak performance. CONCLUSION: The positive attitudes in this sample towards maximum physical capacity open the possibility of introducing physical testing early in the treatment process. However, the patients were self-referred and thus highly motivated and as such are not necessarily representative of the whole population of cancer patients treated with chemotherapy.


Assuntos
Tolerância ao Exercício , Exercício Físico , Neoplasias/reabilitação , Adolescente , Adulto , Idoso , Antineoplásicos/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Motivação , Força Muscular , Neoplasias/tratamento farmacológico , Neoplasias/psicologia , Consumo de Oxigênio , Estudos Prospectivos
9.
Scand J Med Sci Sports ; 16(5): 349-57, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16978255

RESUMO

The purpose of the study was to examine the effects of a supervised high- and low-intensity structured training program in cancer patients concurrently undergoing chemotherapy. Seventy patients, in different stages of the disease and with different diagnoses (48 females, 22 males), between 18 and 65 years of age (mean age 42.8) participated in a 9-h weekly training program over 6 weeks. The intervention involved physical exercise, relaxation, massage, and body-awareness training. Physical capacity (one-repetition maximum tests (1RM), VO2max) and body composition (weight, skin-fold) were compared before and after the exercise intervention. The average increase in muscular strength was 41.3% (P<0.001) and 14.5% in aerobic fitness (pre: 2.27+/-0.597 L/min, post: 2.56+/-0.644 L/min, (P<0.001). The exercise intervention significantly increased the weight of the subjects by 1% (pre: 72.62+/-13.42 kg, post: 73.25+/-13.44 kg, P=0.016). There was a significant decrease in skin-fold measurements by 3% (P=0.031). The exercise intervention was well tolerated, provided that daily screening criteria were adhered to. The effects of resistance and cardiovascular training observed in this short-term study support the theory that exercise is a beneficial intervention strategy for increasing muscle strength and aerobic fitness during antineoplastic chemotherapy. This type of exercise program can be an important component of complementary treatment for cancer patients undergoing chemotherapy.


Assuntos
Terapia por Exercício/métodos , Tolerância ao Exercício/fisiologia , Neoplasias/tratamento farmacológico , Neoplasias/fisiopatologia , Adolescente , Adulto , Idoso , Antineoplásicos/uso terapêutico , Peso Corporal , Fenômenos Fisiológicos Cardiovasculares , Terapia por Exercício/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fenômenos Fisiológicos Musculoesqueléticos , Aptidão Física , Dobras Cutâneas
10.
AJNR Am J Neuroradiol ; 27(1): 46-50, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16418354

RESUMO

BACKGROUND: CT perfusion (CTP) is an important diagnostic tool for the imaging of cerebral hemodynamics. To obtain quantitative values of cerebral blood volume (CBV), blood flow (CBF), and mean transit time (MTT), measurement of the arterial input function (AIF) is required. To correct for partial volume effects (PVEs), it is common to normalize the AIF with respect to the venous output function (VOF). This correction assumes that measurement of the VOF is unhampered by PVEs. The purpose of this study was to evaluate the effect of PVE on the measurement of the AIF and VOF and, consequently, on the absolute perfusion parameters. METHODS: In 10 patients the mean area under the curve (AUC) of the AIF and VOF were quantified for 3-, 6-, and 12-mm-thick sections. Differences in the mean (1) AUC of the VOF, (2) AUC of the AIF, and (3) width of the AIF were compared for the 3 section thicknesses, and the influence on the absolute values of CBV, CBF, and MTT were studied. RESULTS: With thinner sections, the AUC of the VOF and the AIF increased significantly and the width of the AIF decreased slightly. Differences in AUC between the 3 section thicknesses were larger for the AIF than for the VOF. CONCLUSION: PVEs affect not only the AIF, but also the VOF. This results in an overestimation of CBV and CBF when a thicker section is used. To avoid PVE, VOF measurements should be performed at lower section thicknesses.


Assuntos
Volume Sanguíneo , Circulação Cerebrovascular , Tomografia Computadorizada por Raios X , Área Sob a Curva , Tempo de Circulação Sanguínea , Velocidade do Fluxo Sanguíneo , Artérias Cerebrais/anatomia & histologia , Artérias Cerebrais/fisiologia , Veias Cerebrais/anatomia & histologia , Veias Cerebrais/fisiologia , Meios de Contraste , Humanos , Iohexol/análogos & derivados
11.
Eur J Cancer Care (Engl) ; 13(4): 362-70, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15305905

RESUMO

The objective of this study was to explore the nature of fatigue in cancer patients with advanced stages of disease undergoing chemotherapy and concurrently participating in a 6-week multidimensional exercise programme (physical exercise, relaxation, massage and body-awareness training). Semi-structured qualitative interviews were conducted with 23 patients between 18 and 65 years of age prior to, during, and at termination of the programme. The findings endorsed that physical debilitation, fatigue, and uncertainty of physical capacity were the patients' motivation for participation. Throughout the programme the patients experienced exercise-induced fatigue, which they associated with a sense of increased physical strength, improvement in energy and physical well-being. This positive sense of fatigue can be seen as a contrast to the negative chemotherapy-induced fatigue, which is characterized by physical discomfort and uncontrollable exhaustion. The patients learned to manoeuvre through periods of intense fatigue by using exercise as a strategy to adjust their sense of physical debilitation. Visibility of fatigue's qualitative aspects is necessary if patients are to be encouraged to stay active and to set realistic goals. The transformation process of fatigue identified in this study supports the theory of exercise as a beneficial intervention strategy in the treatment of cancer-related fatigue.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Terapia por Exercício/métodos , Fadiga/reabilitação , Neoplasias/reabilitação , Atividades Cotidianas , Adolescente , Adulto , Idoso , Tolerância ao Exercício , Fadiga/induzido quimicamente , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/tratamento farmacológico , Neoplasias/psicologia , Qualidade de Vida
12.
J Neurol ; 248(9): 789-94, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11596784

RESUMO

The aim of this study was to analyse the effect of image registration on interobserver agreement in the visual detection of active multiple sclerosis (MS) lesions from serial magnetic resonance (MR) scans. T2W spin-echo MR scans (3-mm slices) of 16 MS patients participating in a treatment trial were selected. For each patient, two pairs of scans were used: an original (i. e., non-registered) and a registered pair. For the original pair, baseline and month 6 were used, and for the registered pair month 3 and 9. For registration an automatic matching algorithm based on Mutual Information was used. Six observers identified active lesions on both original and registered scans. Kappa values were calculated to assess interobserver agreement. Reslicing caused a slight blurring of the images, but near perfect registration. The kappa value of 0.35 +/- 0.07 for new lesions on original images improved to 0.62 (+/- 0.06) by registration (p = 0.004). For enlarging lesions on original images it was extremely poor (kappa 0.11 +/- 0.05), and did not benefit much by registration (kappa 0.20 +/- 0.11). Thus, image registration improved interobserver agreement for visual detection of new lesions. For enlarging lesions, registration improved agreement but still not to a satisfactory level.


Assuntos
Algoritmos , Encéfalo/patologia , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla Recidivante-Remitente/diagnóstico , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Distribuição Aleatória
13.
Cardiovasc Surg ; 6(6): 604-6, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10395264

RESUMO

Arthroscopy of the ankle has dramatically expanded its role in diagnostic and therapeutic value afforded to the patient; however, it is not without complications. Although the majority of the complications described are neurological in origin, vascular injuries can occur. A case of a patient with normal coagulation parameters who underwent a purely diagnostic ankle arthroscopy and later developed a pseudoaneurysm of her distal anterior tibial artery is described. The pseudoaneurysm was resected without complications and early postoperative recovery has been uneventful.


Assuntos
Falso Aneurisma/diagnóstico , Tornozelo/irrigação sanguínea , Artroscopia , Artérias da Tíbia/lesões , Falso Aneurisma/cirurgia , Traumatismos do Tornozelo/diagnóstico , Traumatismos em Atletas/diagnóstico , Criança , Dança/lesões , Feminino , Humanos , Artérias da Tíbia/cirurgia , Ultrassonografia Doppler Dupla
14.
J Cardiovasc Electrophysiol ; 7(6): 503-11, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8743756

RESUMO

INTRODUCTION: Recent studies have described the presence of M cells in the deep layers of the canine and human ventricle displaying electrophysiologic and pharmacologic features different from those of epicardial (EPI) and endocardial (ENDO) cells. The M cell is distinguished electrophysiologically by the ability of its action potential to prolong disproportionately to that of other myocardial cells with slowing of the stimulation rate and pharmacologically by its unique sensitivity to Class III antiarrhythmic agents. The present study was designed to test the hypothesis that similar cells are present in the guinea pig ventricle. METHODS AND RESULTS: We used a dermatome to obtain-thin strips of left ventricular free wall from the hearts of guinea pigs (8 to 14 weeks old) and standard microelectrode techniques to record transmembrane activity. Action potential duration measured at 90% repolarization (APD90) was significantly longer in mid-myocardial (MID) cells than in surface EPI or ENDO cells at all basic cycle lengths (BCLs) tested. At a BCL of 300 msec, APD90 was 102 +/- 21,136 +/- 9, and 95 +/- 15 msec in EPI, MID, and ENDO cells (mean +/- SD; n = 12). At a BCL of 5000 msec, APD90 was 133 +/- 14, 185 +/- 24, and 135 +/- 13 msec in EPI, MID, and ENDO cells ([K+]o = 4 mM). Thus, APD-rate relations were more pronounced in the MID cells. MID cells were also more sensitive to agents with Class III actions (e.g., d,I-sotalol: 10 to 100 microM), exhibiting a greater APD prolongation than EPI or ENDO. d,I-Sotalol also induced early afterdepolarizations in MID cells but not in EPI or ENDO cells. The rate of rise of the action potential upstroke (Vmax) was significantly greater in MID cells: 129 +/- 13, 240 +/- 42, and 192 +/- 28 V/sec in EPI, MID, and ENDO cells (n = 10 to 18). CONCLUSION: Our results demonstrate the existence of important transmural electrical heterogeneity in guinea pig ventricular myocardium. The study provides data in support of the existence of M cells in the mid-myocardial layers of the guinea pig ventricle exhibiting longer APDs and a greater sensitivity to agents with Class III antiarrhythmic action.


Assuntos
Endocárdio/fisiologia , Miocárdio/citologia , Função Ventricular , Potenciais de Ação/fisiologia , Antagonistas Adrenérgicos beta/farmacologia , Análise de Variância , Animais , Eletrofisiologia , Endocárdio/efeitos dos fármacos , Cobaias , Ventrículos do Coração/citologia , Ventrículos do Coração/efeitos dos fármacos , Microeletrodos , Sotalol/farmacologia
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