SEARCH · PubMed Health

Results for “ECOG”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources

PubMed1993

EST 2582 phase II trial of cisplatin in metastatic or recurrent thymoma.

In 1982 there were four reports of cisplatin-induced remissions of invasive thymoma. These observations led the Eastern Cooperative Oncology Group (ECOG) to conduct a Phase II trial of cisplatin (50 mg/m2 intravenously every 3 weeks). During a 4-year period 24 patients were entered on this trial; 3 were excluded because review of histologic material failed to confirm the presence of thymoma. The characteristics of the remaining 21 patients were as follows: median age, 51; males/females, 11/10; ECOG performance status, 0-1/2-3, 16/5; previous treatment with chemotherapy, 3; previous surgery, 20; previous radiation, 15; weight loss, < 5%/ > or = 5%: 17/4. One patient was eliminated from response analysis because of failure to return for follow-up tumor measurements. The following responses were observed in the remaining 20 patients. Partial remission, 2 (10%); stable disease, 8 (40%); and progression, 10 (50%). The median survival was 76 weeks, and the 2-year survival rate was 39%. Four patients experienced severe nausea and vomiting, but life-threatening and lethal toxicities were not observed. Cisplatin given at this dose was relatively ineffective in producing tumor regression in recurrent or metastatic thymoma.

Aged↗

PubMed1996

Randomized trial of 5-fluorouracil and high-dose folinic acid with or without alpha-2B interferon in advanced colorectal cancer.

We evaluated the role of low-dose alpha-2b interferon, added to chemotherapy, for advanced colorectal cancer; we randomized patients, to either a combination chemotherapy of 5-fluorouracil (5-FU) and high-dose folinic acid (HDFA) or the same regimen plus interferon. Between January 1990 and March 1992, 100 untreated patients (PTS) with advanced colorectal cancer, 53 men and 47 women, with an ECOG performance status (PS) of < or = 3, were randomized to either HDFA 200 mg/m2 iv bolus and 5FU 370 mg/m2 in 15-min iv infusion days 1-5 every 4 weeks (arm A), or the same chemotherapy plus IFN 3 x 10(6) IU subcutaneously three times a week in chemotherapy intervals (arm B). A total of 97 PTS are evaluable for response, toxicity, and survival; 3 PTS are not evaluable in arm B for major protocol violations. PTS characteristics were well balanced in both arms for age (median, 64 years), disease-free survival, and disease site. ECOG PS was 0 in 28% of PTS in arm A and in 13% in arm B. Response rates were as follows: arm A, 40%; and arm B, 23%. Median time to failure was as follows: 10.2 months arm A versus 9 months arm B. Median survival was as follows: 13.3 months arm A versus 10.9 months arm B. Grade 3 haematological toxicity was 9% of PTS in both arms. Gastrointestinal toxicity was as follows: 17% arm A versus 22% arm B. The cost of drugs expressed per m2/month was $60 in arm A and $390 in arm B. The results show that IFN at the schedule and doses employed adds no benefit to the combination of 5FU/HDFA.

Adult↗

PubMedDate not supplied

Results of a dose-intense phase 1 study of a combination chemotherapy regimen with cisplatin and epidoxorubicin including medroxyprogesterone acetate and recombinant interleukin-2 in patients with inoperable primary lung cancer.

Based on the role of cytokines in the pathogenesis of cancer-related anorexia-cachexia and the ability of progestins, such as medroxyprogesterone acetate, to reduce cytokine production and relieve cancer-related anorexia-cachexia symptoms, the authors designed an open, dose-finding phase I study of a combined chemotherapy regimen (cisplatin [CDDP], epidoxorubicin [EPI]), including recombinant interleukin-2 (IL-2) and medroxyprogesterone acetate for patients with stage IIIB to IV inoperable primary lung cancer. The end points were clinical response and toxicity with definition of dose-limiting toxicity and maximal tolerable dose; relief of cancer-related anorexia-cachexia symptoms; the assessment of patient serum levels of IL-1beta, IL-6, tumor-necrosing factor-alpha (TNF-alpha), and soluble IL-2 receptor (sIL-2R). From March to October 1997, 16 patients (M:F ratio, 14:2; mean age, 60.5 years; age range, 41 to 74 years) were enrolled. All patients were evaluable for toxicity and 14 of them for response. The patients were assigned to increasing dose levels of drugs according to a dose-escalation schedule. The weekly schedule consisted of a combination of CDDP given intravenously on day 1, EPI given intravenously on day 1, 1 g/day medroxyprogesterone acetate given orally on days 1 to 7, and recombinant IL-2 1.8 MIU administered subcutaneously on days 2 to 7 plus 300 microg granulocyte-colony stimulating factor support given subcutaneously on days 2 to 5. Administration of medroxyprogesterone acetate began 1 week before the first cycle. Dose escalation of the drugs was as follows: 30 mg x m2 x week(-1) CDDP and 25 mg x m2 x week(-1) EPI (first level, two patients); 30 mg x m2 x week(-1) CDDP and 33 mg x m2 x week(-1) EPI (second level, 2 patients); 40 mg x m2 x week(-1) CDDP and 33 mg x m2 x week(-1) EPI (third level, 6 patients); and 40 mg x m2 x week(-1) CDDP and 40 mg x m2 x week(-1) EPI (fourth level, 6 patients). Six cycles were planned for each patient. The actual dose intensity delivered was more than 80% of the projected dose intensity of all drugs. After six cycles, clinical response (according to World Health Organization criteria), toxicity (according to World Health Organization criteria), Eastern Cooperative Oncology Group (ECOG) performance status, body weight, appetite, and serum levels of cytokines were evaluated. After six cycles, 9 of 14 patients (64.3%) had partial response, 3 of 14 (21.4%) had stable disease, and 2 of 14 (14.3%) had progressive disease, and the objective response rate was 64.3%. ECOG performance status and body weight did not change significantly after treatment, whereas appetite showed an increase that was of borderline statistical significance. Toxicity was acceptable and only hematologic. Dose-limiting toxicity was established at the fourth dose level; consequently, maximal tolerable dose was assessed at the third dose level. Before treatment, the serum levels of IL-1beta, IL-6, and TNF-alpha were significantly greater in the patients than in healthy persons. The comparison between pretreatment and posttreatment serum values of IL-1beta, IL-6, TNF-alpha, and sIL-2R did not reveal significant differences in the patients. Similar results were obtained when the patients were considered as responders (partial response) or non-responders (stable or progressive disease) to therapy. Only IL-6 serum levels were increased (p = 0.014) after treatment.

Adult↗

PubMedDate not supplied

Quality of life in patients with advanced non-small cell lung cancer.

Quality of life (QOL) has been shown to improve with chemotherapy in patients with advanced non-small cell lung cancer (NSCLC), but the determinants of this improvement have not been thoroughly explored. Fifty consecutive NSCLC patients starting chemotherapy with measurable disease and with an Eastern Co-operative Oncology Group (ECOG) performance status of <or=2 were evaluated for change in QOL by European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ-C30). The status of global QOL before chemotherapy influenced the degree of change in physical functioning (F = 8.71, P =.001), global QOL (F = 23.82, P <.001), and fatigue (F = 7.92, P =.001), whereas age of the patient was again linked with the change in global QOL (F = 4.68, P =.014), and type of chemotherapy administration (1st vs. 2nd line) was associated with the change in fatigue (F = 7.82, P =.001). Our findings show that patient age and baseline QOL assessed by EORTC-QLQ-C30, but not ECOG performance status, may help predict the amount of improvement in certain aspects of QOL in patients with advanced NSCLC undergoing chemotherapy. Conversely, in this cohort, patients who are likely to have deteriorating QOL on chemotherapy may benefit from closer follow-up and nursing care to optimize supportive measures.

Adult↗

PubMedDate not supplied

Subcortical EEG changes in rhesus monkeys following experimental hyperextension-hyperflexion (whiplash).

A controlled study, involving EEG recordings from the scalp and chronically implanted electrodes in the cortex (ECoG), as well as from selected subcortical nuclei, was undertaken to investigate the neurophysiologic effects on rhesus monkeys following experimental whiplash (hyperextension of the head and neck). Sixteen animals, equally divided into four groups, were studied through the following protocol: (1) two animals within each group were whiplashed and then electrodes were implanted into the brain of one; (2) the second two animals were implanted with deep electrodes and then one was whiplashed. Weekly EEG follow-ups showed hippocampal spiking in three of the four whiplashed and then electrode-implanted animals and in one of implanted and then whiplashed animals 6 to 8 weeks postwhiplash. Several results deserve attention. (1) The "whiplash syndrome" owes part of its symptoms to EEG disturbances in the brain. (2) Prior to the onset of spiking, ie, 6 to 8 weeks postwhiplash, practically all scalp, cortical, and subcortical EEG recordings were normal. (3) When hippocampal EEG spiking did take place, only normal and mildly abnormal changes were seen in either the electrocorticogram (ECoG) or scalp electroencephalogram (EEG). (4) The growth and development of this trauma-induced hippocampal spiking followed the classic sequence for the spread of an epileptogenic focus. (5) This apparent subclinical form of posttraumatic epilepsy may be due to the combined effects of the whiplash plus the subcortical electrode placements further decreasing the already well-known, low-spiking threshold of the hippocampi.

Animals↗

PubMed2004

Serious adverse cutaneous and hepatic toxicities associated with nevirapine use by non-HIV-infected individuals.

BACKGROUND: Nevirapine is a nonnucleoside reverse transcriptase antiretroviral agent. Among HIV-infected individuals, rare instances (<1%) of serious cutaneous and hepatic toxicity have been reported. Because of its favorable pharmacokinetic profile, non-HIV-infected individuals have received nevirapine-containing postexposure prophylaxis (PEP). OBJECTIVE: To describe the clinical features of cutaneous and hepatic toxicity that occurred when nevirapine was administered to non-HIV-infected individuals. METHODS: Reports of nevirapine-associated cutaneous or hepatic toxicity occurring among non-HIV-infected individuals were obtained from the US Food and Drug Administration's adverse event reporting system, the pharmaceutic manufacturer, occupational health programs in Chicago, physicians, and case reports. The Eastern Cooperative Oncology Group (ECOG) scoring system was used to grade toxicity. RESULTS: Twelve non-HIV-infected individuals developed severe cutaneous toxicity, including 3 with Stevens-Johnson syndrome, after 7 to 12 days of nevirapine-containing PEP regimens. Thirty non-HIV-infected individuals developed hepatotoxicity after 8 to 35 days of single-agent nevirapine (n = 8) or a nevirapine-containing PEP regimen (n = 22). Findings included ECOG grade 3 or 4 hepatotoxicity (n = 14), fevers (n = 11), skin rashes (n = 8), eosinophilia (n = 6), and fulminant hepatic necrosis requiring an orthotopic liver transplant (n = 1). Rates of severe hepatotoxicity (grade 3 or 4) in non-HIV-infected individuals ranged from 10% (4/41) to 62% (5/8). Liver biopsy material from 2 individuals was consistent with a hypersensitivity syndrome. CONCLUSIONS: Serious hepatic and cutaneous toxicities can occur in non-HIV-infected individuals who receive short-term nevirapine therapy. The rate of severe hepatotoxicity appears to be greater in non-HIV-infected individuals than in HIV-infected persons and may be associated with higher CD4 counts. The use of PEP regimens containing nevirapine should be discouraged.

Adult↗

PubMed2007

Locally advanced tonsillar squamous cell carcinoma: Treatment approach revisited.

AIMS: The purpose of this study was to review the treatment policy for locally advanced stage III and IV squamous cell carcinoma (SCC) of the tonsil at the Princess Alexandra Hospital Head and Neck Unit, Brisbane, Australia. MATERIALS AND METHODS: The records of 148 patients with curable stage III and IV SCC of the tonsil were reviewed from the years 1992 to 2004 inclusive. During this period, patients were treated with surgery and postoperative radiotherapy and only offered definitive radiation if they were medically or surgically inoperable. There were 102 patients treated with surgery +/- postoperative radiotherapy (group 1) and 46 patients treated with definitive radiotherapy +/- chemotherapy (group 2). The endpoints of locoregional control (LRC), disease specific survival (DSS), and overall survival (OS) were studied and prognostic factors were investigated with univariate and multivariate analyses. RESULTS: The 5-year OS, DSS, and LRC were 57%, 69%, and 84%, respectively. Univariate analyses showed that patients in group 1 had a superior OS (69% vs. 41%, P = .007), a trend toward improvement in LRC (88% vs. 73%, P = .08), and a nonsignificant improvement in DSS (75% vs. 56%, P = .14). There was a greater percentage of patients with an Eastern Cooperative Oncology Group (ECOG) score of 2 or less in group 1, suggesting selection bias toward the surgical group. Multivariate analyses, which adjusted for known prognostic factors, showed that treatment group was significant for OS but not for LRC or DSS. CONCLUSIONS: Surgery and postoperative radiotherapy continues to provide a superior outcome in locally advanced tonsil SCC in patients with surgically resectable disease, good ECOG performance status, and medically operable.

Adult↗

PubMed2004

Health-related quality of life among patients with breast cancer receiving zoledronic acid or pamidronate disodium for metastatic bone lesions.

BACKGROUND: Research on individual differences in health-related quality of life (HRQOL) can identify intervention targets and important covariates in analyses of treatment outcomes. OBJECTIVES: The objectives of this study were to describe HRQOL trajectories for women with metastatic breast cancer in a randomized trial of bisphosphonates and to identify characteristics associated with variations in HRQOL. RESEARCH DESIGN: We conducted a prospective quality-of-life study within a randomized, controlled trial. SUBJECTS: We studied women with metastatic breast cancer receiving zoledronic acid or pamidronate disodium to reduce the incidence of skeletal-related events (SREs). MAIN OUTCOME MEASURES: HRQOL was measured at fixed time points during the trial. Individual growth-curve modeling was used to describe longitudinal trajectories and to identify predictors of trajectories. RESULTS: For most domains of HRQOL, the mean trajectory reflected a mild increase, which leveled off later in the trial. Older age and full-time employment were associated with higher baseline HRQOL. Longer time from cancer diagnosis to randomization, lower Eastern Cooperative Oncology Group (ECOG) status (score of 2 ["inactive"]), and a history of SREs were associated with lower baseline HRQOL. Significant differences across geographic regions were observed for all domains. Active ECOG status (score of 0-1) at baseline was predictive of greater increases in all domains of HRQOL except Social/Family Well-Being. Age, geographic region, and time from first bone metastases to randomization were associated with longitudinal changes in some domains. CONCLUSIONS: Women with metastatic breast cancer receiving bisphosphonates for prevention of SREs experienced an overall increase in HRQOL. Variations among women's experiences are explained partly by such characteristics as a history of SREs.

Bone Neoplasms↗

PubMed2003

Comment on "Performance of different synchronization measures in real data: a case study on electroencephalographic signals".

Quian Quiroga et al. [Phys. Rev. E 65, 041903 (2002)] reported a similar performance of several linear and nonlinear measures of synchronization when applied to the rat electrocorticogram (ECoG). However, they found that the mutual information measure did not produce robust estimates of synchronization when compared to other measures. We reexamined their data using a histogram method with adaptive partitioning and found the mutual information to be a useful measure of regional ECoG interdependence.

Comment↗

PubMed2003

Inability of Lyapunov exponents to predict epileptic seizures.

It has been claimed that Lyapunov exponents computed from electroencephalogram or electrocorticogram (ECoG) time series are useful for early prediction of epileptic seizures. We show, by utilizing a paradigmatic chaotic system, that there are two major obstacles that can fundamentally hinder the predictive power of Lyapunov exponents computed from time series: finite-time statistical fluctuations and noise. A case study with an ECoG signal recorded from a patient with epilepsy is presented.

Cerebral Cortex↗

PubMed2003

Detection of movement-related desynchronization patterns in ongoing single-channel electrocorticogram.

Adaptive autoregressive parameters and a linear classifier were used to detect movement related desynchronization and synchronization patterns in single-channel electrocorticogram (ECoG) obtained from implanted electrode grids. The best classification accuracies found had more than 90% hits and less than 10% false positives. The findings show that the detection of event-related desynchronization and synchronization in ECoG data can be used to reliably provide switch control directly by the brain and is therefore very suitable as the basis of a direct brain interface.

Algorithms↗

PubMed2006

Electrocorticography-based brain computer interface--the Seattle experience.

Electrocorticography (ECoG) has been demonstrated to be an effective modality as a platform for brain-computer interfaces (BCIs). Through our experience with ten subjects, we further demonstrate evidence to support the power and flexibility of this signal for BCI usage. In a subset of four patients, closed-loop BCI experiments were attempted with the patient receiving online feedback that consisted of one-dimensional cursor movement controlled by ECoG features that had shown correlation with various real and imagined motor and speech tasks. All four achieved control, with final target accuracies between 73%-100%. We assess the methods for achieving control and the manner in which enhancing online control can be accomplished by rescreening during online tasks. Additionally, we assess the relevant issues of the current experimental paradigm in light of their clinical constraints.

Cerebral Cortex↗

PubMed2003

Maximum likelihood methods for nonignorable missing responses and covariates in random effects models.

This article analyzes quality of life (QOL) data from an Eastern Cooperative Oncology Group (ECOG) melanoma trial that compared treatment with ganglioside vaccination to treatment with high-dose interferon. The analysis of this data set is challenging due to several difficulties, namely, nonignorable missing longitudinal responses and baseline covariates. Hence, we propose a selection model for estimating parameters in the normal random effects model with nonignorable missing responses and covariates. Parameters are estimated via maximum likelihood using the Gibbs sampler and a Monte Carlo expectation maximization (EM) algorithm. Standard errors are calculated using the bootstrap. The method allows for nonmonotone patterns of missing data in both the response variable and the covariates. We model the missing data mechanism and the missing covariate distribution via a sequence of one-dimensional conditional distributions, allowing the missing covariates to be either categorical or continuous, as well as time-varying. We apply the proposed approach to the ECOG quality-of-life data and conduct a small simulation study evaluating the performance of the maximum likelihood estimates. Our results indicate that a patient treated with the vaccine has a higher QOL score on average at a given time point than a patient treated with high-dose interferon.

Analysis of Variance↗

PubMed2003

Single-unit analysis of substantia nigra pars reticulata neurons in freely behaving rats with genetic absence epilepsy.

PURPOSE: The substantia nigra pars reticulata (SNpr) is assumed to be involved in the control of several kinds of epileptic seizures, an assumption based mostly on neuropharmacologic evidence. However, only very few neurophysiological recordings from the basal ganglia support neuropharmacologic data. We investigated the electrophysiologic activity of SNpr neurons in rats with genetic absence epilepsy. METHODS: Electrocorticography (ECoG) and multi-unit recordings using permanently implanted tetrodes were obtained in freely behaving rats. After spike sorting, auto- and cross-correlation analysis was used to detect oscillatory neuronal activities and synchronizations. RESULTS: During interictal periods, neither oscillation nor synchronization could be observed in the firing patterns of SNpr neurons. At the beginning of the absence seizure, the firing rate increased significantly. The SNpr neurons started firing in bursts of action potentials. Bursts were highly correlated to the spike-and-wave discharges (SWDs) in the ECoG, mainly after the spike component of the cortical spike-and-wave complex. Moreover, pairs of SNpr neurons tended to fire synchronously. Before the end of the seizure, the firing rate decreased progressively, and the burst-firing pattern ended at or before the end of the SWDs. Once the SWDs had stopped, the SNpr neurons resumed their basal firing pattern as before the seizure onset. CONCLUSIONS: These results provide electrophysiologic evidence that firing patterns and synchronization of SNpr neurons are in phase with the occurrence of SWDs. The findings support the concept that nigral control mechanisms are involved in modulating the propagation of an ongoing generalized seizure.

Animals↗

PubMed2006

Medium-term results of percutaneous vertebroplasty in multiple myeloma.

Vertebral compression fractures (VCFs) are common in multiple myeloma (MM). Percutaneous vertebroplasty (PVP) is used to stabilize vertebral collapse and treat the pain. Few studies have been carried out on PVP in MM and follow-up has tended to be short. We have prospectively evaluated the safety and efficacy of PVP in the VCFs resulting from MM or plasmacytomas. Nineteen PVP were performed in 12 consecutive patients. We monitored their pain and functional status using visual analog (VAS) and Eastern Cooperative Oncology Group (ECOG) scale, respectively. For a subjective assessment, every patient was asked about his/her degree of satisfaction. The mean age of the participants was 66 yr. Significant improvement occurred 1 d after PVP according to the VAS score (7.5 pre-PVP to 3.7, P < 0.0001) and ECOG assessment (3.1 to 2.5, P = 0.002). This significant improvement was maintained after 3.2 yr of follow-up. Sixty-three percent of patients were highly satisfied with the result of the PVP and 37% were satisfied. The peri-operative mortality was 0%. Leakage of the cement outside of the vertebral body was noted in 16 of 19 injected vertebrae (84%) but none of the patients developed any clinical or neurological symptoms. At the last follow-up, no further collapse in the treated or neighboring vertebrae was noted. VCFs caused by MM or plasmacytomas can be effectively treated by vertebroplasty. PVP is associated with early clinical improvement of pain and function and can be maintained after a long follow-up without major procedure-related complications.

Aged↗

PubMed1992

Sequential administration of recombinant interferon alpha and deoxycoformycin in the treatment of hairy cell leukaemia.

Both recombinant interferon alpha and deoxycoformycin (dCF) are effective in the treatment of hairy cell leukaemia. In an attempt to reduce the complications from dCF therapy, a pilot study of the Eastern Cooperative Oncology Group (ECOG) first treated patients with interferon to improve peripheral blood cell counts before dCF treatment began. Thirty-four patients were treated for 3 months with recombinant interferon alpha-2a (rIFN alpha-2a), 3 x 10(6) IU subcutaneously three times a week for 3 months, and then by dCF, 4 mg/m2 intravenously every 2 weeks for a maximum of 12 months. The overall response rate was 94% (32/34); 76% of patients (26/34) had complete response (CR) (90% confidence interval, 62-88%) and 18% (6/34) partial response. One patient was found to have a Mycobacterium avium infection while receiving rIFN alpha-2a. Without specific antimycobacterial therapy and with continued administration of rIFN alpha-2a and dCF, the infection resolved and he achieved CR. Three patients had culture-negative febrile episodes during the dCF phase of treatment. Non-disseminated herpes zoster developed in four patients, but three of the episodes occurred only after treatment was discontinued. Sequential administration of rIFN alpha-2a and dCF resulted in fewer infections (P = 0.027) than in ECOG's previous study of dCF used alone. Two patients died, one of combined hairy cell leukaemia and non-Hodgkin's lymphoma of intermediate histologic type 17 months after entry into the study and the other of cardiac arrest 20 months after entry. Thirty-two patients were alive with a median follow-up of 21 months (range 13-31 months). This combination produces durable CRs with a low incidence of infection.

Adult↗

PubMed2004

Intravascular lymphoma: clinical presentation, natural history, management and prognostic factors in a series of 38 cases, with special emphasis on the 'cutaneous variant'.

Despite its recognition as a distinct, extremely rare entity, no large studies of intravascular lymphoma (IVL) have been reported. The clinico-pathological characteristics of 38 human immunodeficiency virus-negative patients with IVL diagnosed in Western countries were reviewed to better delineate clinical presentation, clinical variants, natural history and optimal therapy. The IVL is an aggressive and usually disseminated disease (Ann Arbor stage IV in 68% of cases) that predominantly affects elderly patients (median age 70 years, range: 34-90; male:female ratio 0.9), resulting in poor Eastern Cooperative Oncology Group Performance Status (ECOG-PS >1 in 61%), B symptoms (55%), anaemia (63%) and high serum lactate dehydrogenase level (86%). The brain and skin are the most common sites of disease. In contrast to previous reports, hepatosplenic involvement (26%) and bone marrow infiltration (32%) were found to be common features in IVL, while nodal disease was confirmed as rare (11% of cases). Patients with disease limited to the skin ('cutaneous variant'; 26% of cases) were invariably females with a normal platelet count, and exhibited a significantly better outcome than the remaining patients, which deserves further investigation. Overall survival was usually poor; however, the early use of intensive therapies could improve outcome in young patients with unfavourable features. ECOG-PS >1, 'cutaneous variant', stage I and chemotherapy use were independently associated with improved survival.

Adult↗

PubMed1993

Sleep in the harp seal (Pagophilus groenlandica). Comparison of sleep on land and in water.

Four young harp seals (aged three to five months) were implanted with electrodes for recording electrocorticograms (ECoG) of the two hemispheres, and electrocardiogram, electroculogram, and electromyogram of the neck muscles. In all the seals ECoG slow waves developed simultaneously in both hemispheres, irrespective of whether they slept on land, on the water surface or submerged. Slow-wave sleep (SWS) was present in animals on the water surface and submerged, while paradoxical sleep (PS) occurred only when the animals were submerged. Breathing in SWS could be both regular (pauses less than twenty seconds) and intermittent (pauses lasting up to three minutes alternating with hyperventilation periods). All the PS episodes occurred during single respiratory pauses and ended by waking while the seal ascended to the water surface to breathe. Flipper movements were sometimes observed in SWS, but never in PS. The ability of harp seals to cease respiration during sleep and to sleep under water could be an adaptation to living conditons in the freezing seas.

Journal Article↗