Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
1.
Science ; 384(6692): 214-217, 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38603482

RESUMO

Massive stars (those ≥8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7% of massive stars have observed magnetic fields, the origin of which is debated. We used multi-epoch interferometric and spectroscopic observations to characterize HD 148937, a binary system of two massive stars. We found that only one star is magnetic and that it appears younger than its companion. The system properties and a surrounding bipolar nebula can be reproduced with a model in which two stars merged (in a previous triple system) to produce the magnetic massive star. Our results provide observational evidence that magnetic fields form in at least some massive stars through stellar mergers.

2.
New Phytol ; 196(4): 1001-1014, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23121314

RESUMO

Tree species exceeding 70 m in height are rare globally. Giant gymnosperms are concentrated near the Pacific coast of the USA, while the tallest angiosperms are eucalypts (Eucalyptus spp.) in southern and eastern Australia. Giant eucalypts co-occur with rain-forest trees in eastern Australia, creating unique vegetation communities comprising fire-dependent trees above fire-intolerant rain-forest. However, giant eucalypts can also tower over shrubby understoreys (e.g. in Western Australia). The local abundance of giant eucalypts is controlled by interactions between fire activity and landscape setting. Giant eucalypts have features that increase flammability (e.g. oil-rich foliage and open crowns) relative to other rain-forest trees but it is debatable if these features are adaptations. Probable drivers of eucalypt gigantism are intense intra-specific competition following severe fires, and inter-specific competition among adult trees. However, we suggest that this was made possible by a general capacity of eucalypts for 'hyper-emergence'. We argue that, because giant eucalypts occur in rain-forest climates and share traits with rain-forest pioneers, they should be regarded as long-lived rain-forest pioneers, albeit with a particular dependence on fire for regeneration. These unique ecosystems are of high conservation value, following substantial clearing and logging over 150 yr. Contents Summary 1001 I. Introduction 1001 II. Giant eucalypts in a global context 1002 III. Giant eucalypts - taxonomy and distribution 1004 IV. Growth of giant eucalypts 1006 V. Fire and regeneration of giant eucalypts 1008 VI. Are giant eucalypts different from other rain-forest trees? 1009 VII. Conclusions 1010 Acknowledgements 1011 References 1011.

3.
Aust N Z J Public Health ; 29(2): 117-22, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15915614

RESUMO

OBJECTIVE: Decades of health-related research have produced a large body of knowledge describing alarming rates of morbidity, mortality and social/cultural disruption among Indigenous Australians, but have failed to deliver sustainable interventions to arrest the deepening spiral of ill-health. This paper explores the potential of Indigenous natural resource management (NRM) activities to promote and preserve Indigenous health in remote areas of northern Australia. METHOD: A literature review of the health, social science and ecology peer-reviewed journals and secondary literature. CONCLUSIONS AND IMPLICATIONS: Effective interventions in Indigenous health will require trans-disciplinary, holistic approaches that explicitly incorporate Indigenous health beliefs and engage with the social and cultural drivers of health. Aboriginal peoples maintain a strong belief that continued association with and caring for ancestral lands is a key determinant of health. Individual engagement with 'country' provides opportunities for physical activity and improved diet as well as boosting individual autonomy and self-esteem. Internationally, such culturally congruent health promotion activities have been successful in programs targeting substance abuse and chronic diseases. NRM is fundamental to the maintenance of biodiversity of northern Australia. Increased support for Indigenous involvement in land and sea NRM programs would also deliver concrete social benefits for communities including opportunities for sustainable and culturally apt regional employment, applied education and economic development. NRM may also reinvigorate societal/cultural constructs, increasing collective esteem and social cohesion.


Assuntos
Atitude Frente a Saúde/etnologia , Promoção da Saúde , Área Carente de Assistência Médica , Havaiano Nativo ou Outro Ilhéu do Pacífico/psicologia , Saúde da População Rural , Antropologia Cultural , Austrália , Características Culturais , Carência Cultural , Saúde Holística , Humanos , Autonomia Pessoal , Condições Sociais
4.
Hear Res ; 145(1-2): 17-24, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10867273

RESUMO

Distortion product otoacoustic emission (DPOAE) measurements are becoming popular in the clinical realm because they have been shown to reflect cochlear function. The primary tones used to evoke the DPOAE are important in determining the amplitude of the emission recorded in the ear canal. This study examined the ratio of the primaries necessary to determine the maximum amplitude emission as a function of development, stimulus level and frequency. Optimum f(2)/f(1) ratios were measured utilizing the f(1)-sweep technique from 105 neonates between 30-42 weeks conceptional age (CA) and 40 adults. No significant difference for optimum ratio was shown between the neonatal and the adult groups. Primary tone frequency had a significant effect on optimum ratio for both neonates and adults. Low f(2) frequencies (<4 kHz) were associated with higher optimum ratios than high f(2) frequencies (>4 kHz). The adult group was used to investigate the effect of stimulus level on the optimum f(2)/f(1) ratio for f(2) frequencies from 1.7 to 10 kHz. Regression analysis showed significant differences across levels of the primaries at all frequencies except for f(2)=3.4 and 7.0 kHz. These differences in f(2)/f(1) ratio across stimulus frequency and level may be attributed to the change in the shape of the excitation profiles along the basilar membrane.


Assuntos
Envelhecimento/fisiologia , Desenvolvimento Infantil/fisiologia , Recém-Nascido/fisiologia , Emissões Otoacústicas Espontâneas , Estimulação Acústica/métodos , Adolescente , Adulto , Feminino , Idade Gestacional , Humanos , Recém-Nascido Prematuro , Masculino , Distorção da Percepção
5.
Hear Res ; 142(1-2): 1-11, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10748323

RESUMO

This study examined gender differences in f(1)- and f(2)-sweep distortion product otoacoustic emission (DPOAE) phase delay measures in 60 normal-hearing human adults. Phase delay measures were obtained at six different f(2) frequencies ranging from 1.1 to 6.0 kHz (f(2)/f(1) ratios were 1.1-1.3). Primary levels for f(2) were 45 and 50 dB SPL (f(1)f(2)). Gender differences have been observed in normal-hearing human adults in both auditory brainstem response (ABR) and f(1)-sweep DPOAE studies. Gender differences in delay have been attributed to differences in the average length of the cochlea, where female cochleas are 13% shorter than male cochleas. Previously, the authors have proposed that the f(1)-sweep phase delay estimate is predominantly composed of a level-independent transport time to the site of DPOAE generation and a small proportion of the level and frequency-dependent filter build-up time. The f(2)-sweep delay also contains the transport time, however, it is predominantly composed of the filter build-up time. Therefore, delay differences between stimulation paradigms are equal to a proportion of the filter build-up time. In this study, mean f(1)- and f(2)-sweep delays were significantly longer in male ears than female ears at 1.1 kHz (45 and 50 dB). At 50 dB, f(1)-sweep phase delay measures were 18% longer in male ears (6.5 ms) than female ears (5.5 ms). Mean f(2)-sweep delays were 23% longer in male ears (10.0 ms) than female ears (8.1 ms). This gender difference was not observed when the isolated filter build-up time was calculated from the DPOAE phase delay difference. These observations may therefore be attributed to a gender-related anatomical difference in cochlear length.


Assuntos
Audição/fisiologia , Emissões Otoacústicas Espontâneas , Caracteres Sexuais , Adulto , Feminino , Humanos , Masculino , Distorção da Percepção , Tempo de Reação , Valores de Referência
6.
Hear Res ; 119(1-2): 14-26, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9641315

RESUMO

This study examined cochlear filter response properties derived from f1- and f2-sweep phase delay difference measures in 60 normal hearing human adults. Seven different f2 frequencies ranging from 1.1 to 9.2 kHz were presented (f2/f1 ratios of 1.1-1.3). F2 intensity level was varied in 5 dB steps from 30 to 50 dB SPL (the level of f1 was 15 dB above the level of f2). DPOAE delay estimates in a f2-sweep paradigm are longer than in a f1-sweep paradigm at the same frequency and intensity. This indicates that the f2-sweep DPOAE phase delay is composed of a greater proportion of the filter response time at the site of DPOAE generation than the f1-sweep delay. This proportion was isolated by subtracting f1-sweep DPOAE delays from f2-sweep delays at similar f2 frequencies and intensities. Under the assumption of linearity and minimum phase the impulse response of the filter at each f2 stimulus level was calculated from the mean phase delay difference. Frequency response properties were calculated by Fourier transformation of the impulse response at each f2 frequency and intensity. High frequency low intensity impulse responses had longer response times and narrower frequency bandwidths than low frequency high intensity responses. The Q10dB values of DPOAE derived tuning curves ranged from 2.4 (1.5 kHz) to 7.3 (8.5 kHz).


Assuntos
Limiar Auditivo/fisiologia , Cóclea/fisiologia , Emissões Otoacústicas Espontâneas/fisiologia , Estimulação Acústica , Adulto , Feminino , Análise de Fourier , Testes Auditivos , Humanos , Masculino
7.
Am J Ophthalmol ; 125(4): 493-501, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9559735

RESUMO

PURPOSE: To estimate the prevalence of abnormalities in visual function and ocular structures associated with the long-term use of tamoxifen citrate. METHODS: A single-masked, cross-sectional study involving multiple community and institutional ophthalmologic departments was conducted with a volunteer sample of 303 women with breast cancer currently taking part in a randomized clinical trial to determine the efficacy of tamoxifen (20 mg/day) in preventing recurrences. Participants included women who had never been on drug (n=85); women who had taken tamoxifen for an average of 4.8 years, then been off the drug for an average of 2.7 years (n=140); and women who had been on tamoxifen continuously for an average of 7.8 years (n=78). Women were evaluated by questionnaire, psychophysical testing, and clinical examination to determine any abnormalities in visual function and the comparative prevalences of corneal, lens, retinal, and optic nerve pathology. RESULTS: There were no cases of vision-threatening ocular toxicity among the tamoxifen-treated participants. Compared with nontreated participants, the tamoxifen-treated women had no differences in the activities of daily vision, visual acuity measurements, or other tests of visual function except for color screening. Intraretinal crystals (odds ratio [OR]=3.58, P=.178) and posterior subcapsular opacities (OR=4.03, P=.034) were more frequent in the tamoxifen-treated group. CONCLUSIONS: Women should have a thorough baseline ophthalmic evaluation within the first year of initiating tamoxifen therapy and receive appropriate follow-up evaluations.


Assuntos
Antineoplásicos Hormonais/efeitos adversos , Oftalmopatias/induzido quimicamente , Tamoxifeno/efeitos adversos , Visão Ocular/efeitos dos fármacos , Idoso , Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/prevenção & controle , Catarata/induzido quimicamente , Estudos Transversais , Feminino , Humanos , Cristalino/efeitos dos fármacos , Estudos Longitudinais , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/prevenção & controle , Prevalência , Retina/efeitos dos fármacos , Doenças Retinianas/induzido quimicamente , Método Simples-Cego , Tamoxifeno/uso terapêutico , Testes Visuais
8.
New Phytol ; 140(3): 385-410, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33862877

RESUMO

One of the most complex and contentious issues in Australian ecology concerns the environmental impact of Aboriginal landscape burning. This issue is not only important for the development of a comprehensive understanding of the dynamics and evolution of the Australian biota, but is central to the formulation of appropriate strategies for the conservation of the nation's biodiversity. Ethnographic evidence leaves little doubt that Aboriginal burning played a central role in the maintenance of the landscapes subsequently colonized by Europeans. Both 19th century European colonists and anthropologists in the 20th century documented the indispensability of fire as a tool in traditional Aboriginal economies, which have aptly been described as 'fire-stick farming'. Aborigines used fire to achieve short-term outcomes such as providing favourable habitats for herbivores or increasing the local abundance of food plants, but it is not clear whether or not Aborigines had a predictive ecological knowledge of the long-term consequences of their use of fire. A large body of ecological evidence suggests that Aboriginal burning resulted in substantial changes in the geographic range and demographic structure of many vegetation types. Aboriginal burning was important in creating habitat mosaics that favoured the abundance of some mammal species and in the maintenance of infrequently burnt habitats upon which the survival of specialized fauna depends. Aboriginal fire regimes were probably critical for the maintenance of at least one species of tree (Callitris intratropica) in the monsoon tropics. The question of the original impact of humans on the Australian environment is fundamentally speculative because of vague, disputed time frames proposed for the waves of colonization and shifting settlement patterns of Aborigines in the late Quaternary period. There is an inherent circular argument concerning the cause and effect of climate change, vegetation change, and burning through the late Quaternary. Charcoal and pollen evidence from long sedimentary cores is ambiguous and cannot be used to demonstrate unequivocally the initial impact of Aboriginal people on the landscapes of Pleistocene Australia. The sparse available evidence does not support the hypotheses that Aboriginal burning was primarily responsible for the extinction of Pleistocene megafauna; was critical for the maintenance of habitats of small mammals that have become extinct following European colonization; initiated widespread accelerated soil erosion rates in either the Pleistocene or Holocene; or forced the evolutionary diversification of the Australian biota. Burning may have caused the extinction of some fire-sensitive species of plants and animals dependent upon infrequently burnt habitats, and it must have maintained structurally open vegetation such as grasslands and also extended the range of fire-adapted species, such as Eucalyptus, into environments climatically suitable for rain forest. Palaeoecological research concerning prior impacts of Aborigines must give way to focused studies of the role of different anthropogenic fire regimes in contemporary ecosystems that have not been destroyed by European colonization. Such research is crucial for comprehending the role of Aboriginal burning in the maintenance of Australia's unique, rich biodiversity. CONTENTS Summary 385 I. Introduction 386 II. Aborigines and fire 386 III. Ecological perspectives 390 IV. Palaeoecological perspectives 394 V. General conclusions 404 Acknowledgements 405 References 405.

9.
J Acoust Soc Am ; 101(3): 1550-9, 1997 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9069625

RESUMO

Phase measurements of distortion product otoacoustic emissions (DPOAE) provide an estimate of round-trip travel times in the cochlea. This study examined differences in f1- and f2-sweep round-trip delays estimated from DPOAE phase responses in 20 normal-hearing adult human subjects as a function of f2 frequency and sound intensity. Eight different f2 frequencies ranging from 1.1-13 kHz were presented. For both the f1- and the f2-sweep stimulation conditions the f2/f1 ratios were between 1.1 and 1.3. Primary intensity levels for f2 were varied in 5-dB steps from 30-50 dB SPL (where f1 was 15 dB > f2). Delays in the f2-sweep condition were equal to or longer than travel times in the f1-sweep condition. Round-trip delays showed a significant intensity dependence in both the f1- and f2-sweep conditions (p < or = 0.01). In both conditions, the delay increased as stimulus intensity decreased. Delay estimates in the f2-sweep condition were more strongly intensity dependent than estimates in the f1-sweep condition at f2 frequencies above 1.6 kHz. The mean difference in f2- and f1-sweep delays at low intensities ranged from 15.9 periods at the 9.2 kHz f2 place, to 2.5 periods at the 1.6 kHz f2 place. The intensity dependence of round-trip delay estimates in both conditions may be attributed to intensity-dependent changes in the cochlear filter response time related to the sharpness of tuning of DPOAE responses. The steeper intensity dependence and longer delays observed in the f2-sweep condition may similarly be attributed to a greater proportion of the f2-sweep response being composed of the filter response time.


Assuntos
Estimulação Acústica , Cóclea/fisiologia , Som , Adolescente , Adulto , Feminino , Humanos , Masculino
10.
J Natl Cancer Inst ; 88(21): 1529-42, 1996 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-8901851

RESUMO

BACKGROUND: In 1982, the National Surgical Adjuvant Breast and Bowel Project initiated a randomized, double-blinded, placebo-controlled trial (B-14) to determine the effectiveness of adjuvant tamoxifen therapy in patients with primary operable breast cancer who had estrogen receptor-positive tumors and no axillary lymph node involvement. The findings indicated that tamoxifen therapy provided substantial benefit to patients with early stage disease. However, questions arose about how long the observed benefit would persist, about the duration of therapy necessary to maintain maximum benefit, and about the nature and severity of adverse effects from prolonged treatment. PURPOSE: We evaluated the outcome of patients in the B-14 trial through 10 years of follow-up. In addition, the effects of 5 years versus more than 5 years of tamoxifen therapy were compared. METHODS: In the trial, patients were initially assigned to receive either tamoxifen at 20 mg/day (n = 1404) or placebo (n = 1414). Tamoxifen-treated patients who remained disease free after 5 years of therapy were then reassigned to receive either another 5 years of tamoxifen (n = 322) or 5 years of placebo (n = 321). After the study began, another group of patients who met the same protocol eligibility requirements as the randomly assigned patients were registered to receive tamoxifen (n = 1211). Registered patients who were disease free after 5 years of treatment were also randomly assigned to another 5 years of tamoxifen (n = 261) or to 5 years of placebo (n = 249). To compare 5 years with more than 5 years of tamoxifen therapy, data relating to all patients reassigned to an additional 5 years of the drug were combined. Patients who were not reassigned to either tamoxifen or placebo continued to be followed in the study. Survival, disease-free survival, and distant disease-free survival (relating to failure at distant sites) were estimated by use of the Kaplan-Meier method; differences between the treatment groups were assessed by use of the logrank test. The relative risks of failure (with 95% confidence intervals [CIs]) were determined by use of the Cox proportional hazards model. Reported P values are two-sided. RESULTS: Through 10 years of follow-up, a significant advantage in disease-free survival (69% versus 57%, P < .0001; relative risk = 0.66; 95% CI = 0.58-0.74), distant disease-free survival (76% versus 67%, P < .0001; relative risk = 0.70; 95% CI = 0.61-0.81), and survival (80% versus 76%, P = .02; relative risk = 0.84; 95% CI = 0.71-0.99) was found for patients in the group first assigned to receive tamoxifen. The survival benefit extended to those 49 years of age or younger and to those 50 years of age or older. Tamoxifen therapy was associated with a 37% reduction in the incidence of contralateral (opposite) breast cancer (P = .007). Through 4 years after the reassignment of tamoxifen-treated patients to either continued-therapy or placebo groups, advantages in disease-free survival (92% versus 86%, P = .003) and distant disease-free survival (96% versus 90%, P = .01) were found for those who discontinued tamoxifen treatment. Survival was 96% for those who discontinued tamoxifen compared with 94% for those who continued tamoxifen treatment (P = .08). A higher incidence of thromboembolic events was seen in tamoxifen-treated patients (through 5 years, 1.7% versus 0.4%). Except for endometrial cancer, the incidence of second cancers was not increased with tamoxifen therapy. CONCLUSIONS AND IMPLICATIONS: The benefit from 5 years of tamoxifen therapy persists through 10 years of follow-up. No additional advantage is obtained from continuing tamoxifen therapy for more than 5 years.


Assuntos
Antineoplásicos Hormonais/administração & dosagem , Neoplasias da Mama/tratamento farmacológico , Antagonistas de Estrogênios/administração & dosagem , Receptores de Estrogênio , Tamoxifeno/administração & dosagem , Antineoplásicos Hormonais/efeitos adversos , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Quimioterapia Adjuvante , Intervalo Livre de Doença , Método Duplo-Cego , Neoplasias do Endométrio/etiologia , Antagonistas de Estrogênios/efeitos adversos , Feminino , Seguimentos , Humanos , Metástase Linfática , Pessoa de Meia-Idade , Risco , Tamoxifeno/efeitos adversos , Fatores de Tempo
11.
J Clin Oncol ; 14(7): 1982-92, 1996 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8683228

RESUMO

PURPOSE: To compare sequential methotrexate (M) and fluorouracil (F) (M-->F) with surgery (National Surgical Adjuvant Breast and Bowel Project [NSABP] B-13) and cyclophosphamide (C), M, and F with M-->F (NSABP B-19), in patients with estrogen receptor (ER)-negative tumors and negative axillary nodes. PATIENTS AND METHODS: A total of 760 patients were randomized to B-13; 1,095 patients with the same eligibility requirements were randomized to B-19. Disease-free survival (DFS), distant disease-free survival (DDFS), and survival were determined using life-table estimates. RESULTS: A significant benefit in overall DFS (74% v 59%; P < .001) was demonstrated at 8 years in all B-13 patients who received M-->F (69% v 56% [P = .006] in those or= 50 years). A survival advantage was evident in older patients (89% v 80%; P = .03). In B-19, through 5 years, an overall DFS advantage (82% v 73%; P < .001) and a borderline survival advantage (88% v 85%; P = .06) were evident with CMF. The DFS (84% v 72%; P < .001) and survival (89% v 84%; P = .04) benefits from CMF were greater in women aged F or CMF after lumpectomy and breast irradiation resulted in a low probability of ipsilateral breast tumor recurrence (IBTR). In B-13, the frequency of IBTR was 2.6% following M-->F versus 13.4% in women treated by lumpectomy; it was 0.6% following CMF in B-19. Toxicity >or= grade 3 was more frequent among CMF patients in B-19. The age-related difference in CMF benefit was not related to amount of drug received. CONCLUSION: M-->F and CMF are effective for node-negative patients with ER-negative tumors. The incidence of local-regional or distant metastases and IBTR decreased after either therapy. The benefit from either therapy was evident in all patients, but the CMF advantage was greater in those F may be used in patients with medical problems that would preclude CMF administration.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Receptores de Estrogênio/análise , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias da Mama/química , Neoplasias da Mama/cirurgia , Quimioterapia Adjuvante , Ciclofosfamida/administração & dosagem , Ciclofosfamida/efeitos adversos , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/efeitos adversos , Humanos , Leucovorina/administração & dosagem , Metástase Linfática , Mastectomia , Metotrexato/administração & dosagem , Metotrexato/efeitos adversos , Pessoa de Meia-Idade , Metástase Neoplásica , Recidiva Local de Neoplasia , Taxa de Sobrevida
12.
J Neurophysiol ; 74(5): 1841-55, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8592178

RESUMO

1. Neural activity was recorded extracellularly with two independent microelectrodes aligned in parallel and advanced perpendicular to isofrequency sheets in cat primary auditory cortex. Multiunit activity was separated into single-unit spike trains using a maximum variance spike sorting algorithm. Only units that demonstrated a high quality of sorting and a minimum spontaneous firing rate of 0.2 spikes/s were considered for analysis. The primary aim of this study was to describe the effect of periodic click train and broadband noise stimulation on short-time-scale (< or = 50 ms) bursts in the spike trains of single auditory cortical units and to determine whether stimulation influenced the occurrence, spike count, and/or temporal structure of burst firing relative to a spontaneous baseline. 2. Extracellular recordings were made in 20 juvenile and adult cats from 69 single auditory cortical units during click train stimulation and silence, and from 30 single units during noise stimulation and in silence. In an additional 15 single units the effect of both click train and noise stimulation was investigated. The incidence, spike count, and temporal structure of short-time-scale burst firing in the first 100 ms following stimulus presentation was compared with burst firing in the period starting 500 ms after stimulus presentation and with spontaneous burst firing. In addition, the serial dependence of interspike intervals within a burst was tested during periods of stimulation. 3. Burst firing was present in the stimulation, poststimulation, and spontaneous conditions. Longer bursts (consisting of > or = 3 spikes) were more commonly observed in the poststimulation and spontaneous conditions than in the stimulation condition. This effect was most pronounced during click stimulation. A period of elevated firing activity was present in a subset of units 0.5-1.5 s after stimulus presentation, indicating prolonged effects of stimulation on single-unit firing behavior. 4. For both stimuli, the proportion of single-unit responses composed of bursts was significantly greater in poststimulation and spontaneous periods than during stimulation. Burst rate was higher in post-click-train stimulation and spontaneous periods than during periods of click stimulation. The isolated spike rate was significantly higher during periods of noise and click stimulation than in the poststimulation and spontaneous periods. 5. An examination of the autocorrelograms and higher-order interspike interval histograms of single-unit responses during click train stimulation indicated that 25% of single-unit spike trains contained an excess of brief first-order intervals and 14% of spike trains contained a shortage of long higher-order interspike intervals relative to a spontaneous baseline. During noise stimulation, 10% of single-unit responses contained an excess of short intervals relative to baseline. Interspike intervals of short-duration bursts were not serially dependent during periods of stimulation. 6. A comparison of the autocorrelograms and higher-order interval histograms of single-unit responses in the poststimulation and spontaneous conditions indicated that 20% of single-unit spike trains contained an excess of short first-, second-, and third-order intervals following stimulation. This subgroups of single units could not be distinguished on the basis of the age of the animal or the depth at which the recording was made. 7. The low incidence of burst firing during stimulation opposes the view that bursts serve as a mechanism to emphasize or amplify particular stimulus-related responses in the presence of ongoing spontaneous activity in the primary auditory cortex. Moreover, there is little evidence to support the notion that brief bursts represent neural codes, because intraburst intervals are not serially dependent. It is suggested that pyramidal burst firing may be an effective way to evoke postsynaptic firing in inhibitory interneurons and subsequ


Assuntos
Córtex Auditivo/fisiologia , Potenciais Evocados Auditivos/fisiologia , Estimulação Acústica , Animais , Gatos , Ruído , Distribuição de Poisson
14.
Am J Clin Pathol ; 77(1): 60-5, 1982 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-6798858

RESUMO

IgD kappa plasma cell Dyscrasias are rare. Two cases with unusual presentations and courses area described. One of these patients had myelomatous pleural effusions, and subsequently experienced myelomatous leptomeningitis. The significance of this combination is discussed and the literature reviewed. The value of immunofluorescent techniques in identifying plasma cells in the cerebrospinal fluid and pleural fluid is emphasized.


Assuntos
Imunoglobulina D/análise , Cadeias Leves de Imunoglobulina/análise , Cadeias kappa de Imunoglobulina/análise , Meningite/etiologia , Mieloma Múltiplo/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Mieloma Múltiplo/imunologia , Metástase Neoplásica
15.
Can J Surg ; 24(4): 375-8, 1981 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7023633

RESUMO

The data on adjuvant chemotherapy for mammary carcinoma obtained from animal models suggest that (a) systemic chemotherapy combined with tumour excision provides more long-term cures than either method alone, (b) systemic treatment may be effective in eradicating occult micrometastases and (c) the effect of systemic chemotherapy decreases with advancing tumour stage preoperatively, with increasing time lag between operation and chemotherapy, and as the drug dosage decreases. Results from major clinical trials in terms of disease-free and overall survival differ with varying regimens in different subsets of patients, in relation to age, menopausal status and degree of pathologic axillary node involvement. Clearly, different regimens have a favourable impact on short-term disease-free survival, primarily but not exclusively in premenopausal patients. Long-term effects of such treatments on survival and late toxicity require careful continuing evaluation. The current delay in most cooperative group trials of several weeks between operation and adjuvant chemotherapy is disadvantageous. A prospective evaluation should be carried out of chemotherapy begun immediately after operation.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias da Mama/terapia , Vacina BCG/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/cirurgia , Ensaios Clínicos como Assunto , Quimioterapia Combinada , Feminino , Humanos , Imunoterapia , Metástase Linfática , Tamoxifeno/uso terapêutico
17.
J Urol ; 125(2): 255-6, 1981 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-7206068

RESUMO

A case of pure carcinoid of the testis is reported. The patient presented with metastatic carcinoid and the carcinoid syndrome 17 years after removal of the primary tumor. He died 2 years later. The long interval from initial orchiectomy to presentation with metastases strongly suggests that the original lesion was primary rather than metastatic. Only 2 cases have been reported to date in which an apparently pure primary testicular carcinoid developed metastases. In both of these cases the possibility that the testicular lesion itself was metastatic was not excluded.


Assuntos
Neoplasias Brônquicas/secundário , Tumor Carcinoide/secundário , Neoplasias Hepáticas/secundário , Neoplasias Testiculares/patologia , Adulto , Tumor Carcinoide/patologia , Humanos , Metástase Linfática , Masculino , Síndrome do Carcinoide Maligno/patologia
18.
Br J Urol ; 52(1): 45-9, 1980 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-6159033

RESUMO

Fourteen patients with disseminated non-seminomatous germ cell tumours of the testis were treated with a 3-drug combination of vinblastine, bleomycin and cis-diamminedichloroplatinum. Of 13 patients with measurable disease, 9 (69%) had complete and 3 (23%) partial remission. One patient with a solitary metastasis failed to respond but is disease-free following surgical excision. Toxicity was significant but no drug-related deaths occurred and there were no apparent lasting side effects. No patient attaining complete remission has relapsed. Eleven (79%) of the 14 patients are without evidence of disease from 3+ to 36+ months, 6 of these for 2 years or more. Of the patients in partial remission one died at 16 months and one is undergoing further treatment for relapse with liver metastases. One patient remains in partial remission at 30 months. These results demonstrate the efficacy of this drug combination in testicular cancer.


Assuntos
Bleomicina/uso terapêutico , Cisplatino/uso terapêutico , Neoplasias Testiculares/tratamento farmacológico , Vimblastina/uso terapêutico , Coriocarcinoma/tratamento farmacológico , Quimioterapia Combinada , Humanos , Masculino , Teratoma/tratamento farmacológico , Teratoma/secundário , Fatores de Tempo
19.
Can J Surg ; 22(5): 418-21, 1979 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-574055

RESUMO

Thirteen patients with disseminated nonseminomatous germ cell tumours of the testis were treated with a three-drug combination (vinblastine, bleomycin and cis-diamminedichloroplatinum). Of 12 patients with measurable disease, 8 had complete and 3 partial remission. One patient with a solitary metastasis failed to respond but is disease free following surgical excision. Toxicity was moderate but no drug-related deaths occurred and there were no apparent lasting side-effects. No patients with complete remission have relapsed. Ten of the 13 patients are without evidence of disease from 9 to 36 months after treatment, 6 of these for 2 years or more. One patient died after a partial remission of 16 months. One is undergoing further treatment for relapse with liver metastases and one remains in partial remission at 30 months. These results demonstrate the efficacy of this drug combination in testicular cancer.


Assuntos
Antineoplásicos/administração & dosagem , Coriocarcinoma/tratamento farmacológico , Teratoma/tratamento farmacológico , Neoplasias Testiculares/tratamento farmacológico , Antineoplásicos/efeitos adversos , Quimioterapia Combinada , Seguimentos , Humanos , Neoplasias Hepáticas/secundário , Neoplasias Pulmonares/secundário , Masculino
20.
Cancer ; 36(3): 1067-71, 1975 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-171050

RESUMO

Hypercalcemia is very uncommon in small cell (oat cell) carcinoma of the lung. Two cases of this neoplasm associated with symptomatic hypercalcemia are described. Despite normal skeletal roentgenograms, metastatic bone disease was demonstrated by abnormal bone scans and bone biopsies in both patients. The combination of conventional antihypercalcemia therapy, cytotoxic cancer chemotherapy, and synthetic salmon calcitonin corrected the hypercalcemia despite progression of the small cell carcinoma. One patient with elevated serum immunoreactive parathyroid hormone (PTH) had a parathyroid adenoma at autopsy. This association emphasizes that in cases of bronchogenic small cell carcinoma with hypercalcemia, conincidental primary hyperparathyroidism should be considered.


Assuntos
Carcinoma de Células Pequenas/complicações , Hipercalcemia/etiologia , Neoplasias Pulmonares/complicações , Adenoma/complicações , Adulto , Neoplasias Ósseas/complicações , Calcitonina/uso terapêutico , Carcinoma de Células Pequenas/tratamento farmacológico , Ciclofosfamida/uso terapêutico , Furosemida/uso terapêutico , Humanos , Hidrocortisona/uso terapêutico , Hipercalcemia/tratamento farmacológico , Lomustina/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Neoplasias das Paratireoides/complicações
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...