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Biomedical subjects

P Linkowski

Publications and source records attributed to P Linkowski.

At least 37 records · Page 2Linked to original sources
PubMed1998

Shortened REM latency as a psychobiological marker for psychotic depression? An age-, gender-, and polarity-controlled study.

BACKGROUND: Previous reports suggest that the clinical dichotomy separating psychotic and nonpsychotic depression corresponds to different neurobiological profiles. The aim of the present study is to further investigate the psychobiological correlates of these two particular depressive subtypes. METHODS: Thyroid-stimulating hormone response to thyrotropin-releasing hormone postdexamethasone cortisol levels, and electroencephalgraphic sleep characteristics of 44 psychotic major depressive patients were compared to those of 44 nonpsychotic depressives matched for age, gender, and polarity. RESULTS: Some biological disturbances usually associated with depression (increased wakefulness, diminished rapid eye movement latency, hypercortisolism, blunted thyroid-stimulating hormone response to thyrotropin-releasing hormone stimulation) seemed to be significantly more pronounced in the psychotic depressed group as a reflection of greater illness severity; however, shortened REM latency was not influenced by severity and seemed to be more specifically related to the co-occurrence of psychotic and depressive symptoms. CONCLUSIONS: Our data provide further support for the validity of the clinical dichotomy separating psychotic and nonpsychotic major depression independently of severity.

Age Factors↗
PubMed1998

Neuroendocrine and clinical characteristics of major depressed patients exhibiting sleep-onset REM.

BACKGROUND: Previous reports suggest an association between sleep-onset REM (SOREM) and some clinical characteristics in depressive illness such as age, psychosis, and depression severity. The present study is aimed at further investigating clinical and neuroendocrine correlates of SOREM, controlling for the age-related variability in clinical data. METHODS: Thyroid-stimulating hormone response to thyrotropin-releasing hormone, postdexamethasone cortisol levels, and clinical characteristics of 25 major depressive (MD) patients exhibiting SOREM in at least one of three consecutive recording nights were compared to those of 25 age- and sex-matched MD patients with three REM latencies above 50 min. RESULTS: SOREM patients experienced more affective episodes leading to hospitalization and a shorter duration of current episode than patients with three REM latencies above 50 min. No association between psychosis and SOREM could be demonstrated, and hypothalamic-pituitary-adrenal or -thyroid axis disturbances were not more prevalent in SOREM patients. CONCLUSIONS: Our results suggest that clinical history rather than cross-sectional clinical characteristics relates to the occurrence of SOREM in major depressed patients.

Adult↗
PubMed1998

The dexamethasone suppression test and sleep electroencephalogram in nonbipolar major depressed inpatients: a multivariate analysis.

BACKGROUND: The present study further examined relationships between postdexamethasone cortisol plasma values and sleep electroencephalogram (EEG) parameters. METHODS: The dexamethasone suppression test (DST) and polysomnographic recordings were performed in a sample of 300 inpatients with primary major depressive disorder (MDD) (102 men and 198 women, mean age 44 +/- 12 years, range 20-74 years) consecutively admitted to Erasme Hospital (Brussels, Belgium) between 1981 and 1992. RESULTS: The DST was abnormal in 40% of the sample. Postdexamethasone cortisol plasma values at 4:00 PM were significantly influenced by age, but not by gender. They were also significantly and positively correlated with weight loss, total scores on the Hamilton Depression Rating Scale, total scores on the Newcastle Scale, percentage of awakenings during sleep, and percent of stage 1. They were significantly and negatively correlated with percent of stage 2, slow-wave sleep, and REM sleep. Multiple regression analyses were conducted in two successive steps. First among clinical variables, only age and depressive symptom severity remained correlated with postdexamethasone plasma cortisol values. In the second step, with age and severity held constant, postdexamethasone plasma cortisol values were positively associated with amount of wake time and stage 1, and negatively with amount of slow-wave sleep. CONCLUSIONS: These findings provide further indirect support for an overarousal state in MDD with sympathoadrenal system hyperactivity and impaired sleep continuity. They also underline the importance of taking into account various clinical confounding factors in the interpretation of both DST and sleep EEG results.

Adult↗
PubMed1998

Does sleep EEG data distinguish between UP, BPI or BPII major depressions? An age and gender controlled study.

Clinical characteristics and sleep EEG data of 14 unipolar (UPR), 14 bipolar I (BPI) and 14 bipolar II (BPII) patients, matched for age and gender, were investigated during a major depressive episode. We observed a remarkable similarity in the clinical characteristics of the three samples and, concerning sleep EEG data, a trend to a higher percentage of awakening among BPI patients. Pairwise comparisons of the three subgroups showed that only the Newcastle rating scale score reached significant difference between BPI and UPR groups. We observed trends regarding the difference of awakening both between BPI and BPII groups and between BPI and UPR groups, difference of percentage of REM sleep between BPI and BPII groups and difference of Sleep Period Time between BPII and UPR groups. We also observed that the distribution of REM latencies in the BPI subgroup was different from the two others.

Adult↗
PubMed1998

Kinematics of fast wrist movements in manic-depressive illness chronically treated with lithium carbonate.

Lithium salts have been shown to impair kinematics of fast voluntary movements during acute intoxication. The aim of the present study was to determine whether lithium carbonate affected the kinematics of fast movements in patients chronically treated and who did not exhibit signs of neurotoxicity. We analysed fast wrist flexion movements in 6 healthy subjects, in 5 patients presenting a manic-depressive illness without treatment, and in 8 patients receiving lithium carbonate for a manic-depressive disease. The mean duration of treatment was 3.9 +/- 4.1 years, the mean daily dose 837 +/- 341 mg and the mean serum level 0.95 +/- 0.15 mEq/l. Although mean movement amplitudes were similar in the 3 groups, the variability of fast movements was increased in patients receiving lithium salts. The ratio of maximum to average velocities (Vm/Vave) was significantly higher in patients treated, and their movements were temporally asymmetrical, with a ratio of acceleration duration divided by deceleration duration being lower than in the 2 other groups. These kinematic abnormalities show that a chronic treatment with lithium salts is associated with an impairment of the cerebellar control of fast single-joint movements.

Acceleration↗
PubMed1998

Genetic and environmental influences on prolactin secretion during wake and during sleep.

To delineate the contributions of genetic and environmental factors in the regulation of human prolactin (PRL) secretion, the 24-h profile of plasma PRL was obtained at 15-min intervals in 10 pairs of monozygotic and 10 pairs of dizygotic twins. Sleep was monitored polygraphically. PRL secretory rates were derived from plasma concentrations by deconvolution. Diurnal (24-h) variations were quantified by a regression curve to define nadir, acrophase, and amplitude. Pulses of PRL secretion were identified using a computerized algorithm. A procedure specifically developed for twin studies was used to partition the variance into genetic and environmental contributions. Significant genetic effects were identified for daytime PRL concentrations, rhythm amplitude, and overall wave-shape of the daily PRL profile. In contrast, environmental effects were dominant for mean concentrations during sleep, total secretory output during sleep, overall 24-h concentrations, and total 24-h secretion. However, when interindividual variations in sleep fragmentation were taken into account, the estimates of genetic variance for PRL concentrations and secretion during sleep approached statistical significance. Significant genetic influences were identified for slow-wave sleep (SWS). Because SWS is associated with increased nocturnal PRL secretion, it is possible that genetic effects on PRL secretion during sleep reflect genetic influences on SWS. In conclusion, genetic factors determine partially both the basal daytime concentrations of PRL and the temporal organization of PRL secretion over the 24-h cycle in normal young men.

Adult↗
PubMed1997

Distribution of delta activity across nonrapid eye movement sleep episodes in healthy young men.

The distribution of delta activity across successive nonrapid eye movement (NREM) sleep episodes and its night-to-night stability across three consecutive nights were investigated by studying delta power with spectral analysis in 31 healthy young men. Repeated-measures analysis of variance (ANOVA) with polynomial contrast was applied to grouped data of absolute delta power and three indexes: (1) the rate of delta power per NREM episode to its duration, 2) the standardized rate for the last NREM episode, and 3) the logarithm of the standardized rate. A significant linear decrease across NREM episodes was observed for each variable in each successive night. In addition, using night as a second within-subjects factor, no night effect was observed. Yet, the subsequent analysis of the logarithmic data yielded greater F values in all three nights' data as well as a linear function that accounted for a greater proportion of total variance than the analysis of the nonlogarithmic data. Since a linear decline for the logarithm of a variable implies an exponential distribution for that variable, we conclude that delta activity is distributed exponentially across NREM episodes, and this finding shows a remarkable night-to-night stability.

Adolescent↗
PubMed1997

[Sleep apnea and nocturnal ventilatory assistance (nCPAP): 5-year experience in the conventional system].

The reimbursement of nasal continuous positive airway pressure (nCPAP) by the Belgian social security, via a conventional system, has made since 1991 this treatment available to an increasing number of patients having moderate to severe sleep apnoea hypopnoea syndrome (SAHS). We have reviewed our experience in prescribing domiciliary nCPAP from 1991 to 1995. Three hundred twenty-five subjects with SAHS, predominantly male (89%) and/or obese (77%) subjects, have benefited. Mean use of nCPAP machine, assessed by reading the time counter, amounted 4.7 h per 24 h, with only 23% of non-compliant patients (use < 3 h per 24 h). In 205 patients nCPAP was effective in controlling SAHS-related symptoms. Cure, with successful weaning from nCPAP, was obtained in 16 patients, as a result of marked weight loss in 13 of them. Forty-six non-compliant subjects were not allowed by the physician to go on, and 40 subjects left nCPAP because of intolerance. Finally, 10 patients abandoned nCPAP because of inefficacy, ascribed to some associated condition, being predominant, and 8 patients died. Our results suggest that domiciliary nCPAP is an effective treatment for SAHS in a majority of subjects, but that this kind of treatment is prescribed lifelong, unless there is a marked weight loss. The Belgian conventional system, as it requires a regular follow-up, contributes to keep non-compliance within acceptable limits.

Adult↗
PubMed1996

Neuroendocrine and sleep variables in major depressed inpatients: role of severity.

To evaluate the reliability of the endogenous concept of depressive illness according to the Newcastle Endogenous Depression Diagnostic Index (NEDDI), 155 major depressive inpatients with NEDDI scores > or = 6 (endogenous) were matched for gender and age (+/- 5 years) to 155 major depressive inpatients with NEDDI scores < 6 (nonendogenous). When sleep polygraphic variables, neuroendocrine parameters (dexamethasone suppression and thyrotropin-releasing hormone tests), and various clinical variables (unipolar/bipolar status, psychotic/nonpsychotic subtype, and severity of the depressive episode) were examined, statistically significant differences between endogenous and nonendogenous patients emerged for three variables: the thyroid-stimulating hormone response to the thyrotropin-releasing hormone test, the dexamethasone suppression test response at 16:00 h, and the percentage of time awake during the night. However, when the effects of age and severity of depression were controlled, those differences disappeared.

Adult↗
PubMed1996

Sleep EEG analysis by linear prediction: frequency changes of slow-wave activity within NREM and REM sleep episodes in healthy men.

The linear prediction method was applied to obtain a power spectra estimate of sleep EEG in 10 healthy young men. In order to analyze frequency changes of the slow-wave activity (EEG power in the delta band, 0.05-2.88 Hz), the delta mean frequency was computed for each 20-second sleep epoch. A mean delta mean frequency was calculated for each sleep stage in each individual. Our observations indicate that the delta mean frequency decreases during NREM periods and increases mainly at the onset of the REM episodes. This finding, in parallel with the detailed analysis of slow-wave power variations, leads to an additional description of sleep characteristics during transitions between the NREM-REM sleep episodes.

Adult↗
PubMed1996

Diurnal variations in cardiovascular function and glucose regulation in normotensive humans.

To define the physiological relationships between cardiovascular function, glucose regulation, and insulin secretion, we submitted nine young normotensive subjects to ambulatory blood pressure monitoring and blood sampling at 20-minute intervals for 24 hours to measure glucose, insulin, C peptide, cortisol, and growth hormone. Subjects ingested three identical carbohydrate-rich meals in the morning (8:30 AM), early afternoon (2 PM), and evening (8 PM). On the following day, they underwent an intravenous glucose tolerance test for quantification of insulin sensitivity. Significant postmeal increases in systolic pressure averaging 18 +/- 10 mm Hg in the morning, 18 +/- 8 mm Hg in the early afternoon, and 26 +/- 19 mm Hg in the evening were observed. Postprandial variations in diastolic pressure and heart rate were significant only for the morning meal. The magnitude of the postprandial increases in systolic pressure was correlated with the amount of insulin secreted in the morning but not later in the day. Pulses of growth hormone consistently occurred 3 to 4 hours after the morning and midday meals, as well as after the onset of sleep. Our findings indicate that under normal conditions, there is a quantitative relationship between postprandial insulin secretion and blood pressure.

Blood Glucose↗
PubMed1996

Sleep apnea after 1 year domiciliary nasal-continuous positive airway pressure and attempted weight reduction. Potential for weaning from continuous positive airway pressure.

STUDY OBJECTIVE: To assess the effect of 1 year of therapy for sleep apnea syndrome (SAS) combining domiciliary nasal-continuous positive airway pressure (N-CPAP) and attempted weight loss on the severity of disease and to evaluate the potential for weaning from continuous positive airway pressure (CPAP). METHODS AND PROCEDURES: Ninety-five patients having a baseline apnea hypopnea index (AHI) greater than 10/h were prescribed N-CPAP at home. Weight loss was attempted by dietary counseling and by single ring vertical gastroplasty in those patients with a body mass index (BMI) greater than 40 kg/m2. Subjects were asked to return after 1 year for a full-night polysomnography (PSG) without CPAP and the results were compared with baseline PSG. RESULTS: Thirty-nine patients compliant to CPAP were evaluated. Weight had decreased from 108.3 +/- 29.0 to 99.7 +/- 17.7 kg as a result of dietary counseling (n = 36) or gastroplasty (n = 3). A significant improvement was found in AHI (66.5 +/- 28.7-->50.3 +/- 38.4/h; p < 0.05), maximal duration of apnea or hypopnea (66 +/- 22-->47 +/- 18 s; p < 0.001), minimal oxyhemoglobin saturation (62 +/- 16-->78 +/- 7%; p < 0.001), and stage shift index (SSI) (76 +/- 29-->62 +/- 28/h; p < 0.05). The drop in AHI correlated with the reduction in BMI (r = 0.47; p < 0.01) and with the decrease in SSI (r = 0.50; p < 0.001). Weaning from CPAP was proposed to six patients and succeeded in four (three with 29, 93, and 94 kg weight loss, respectively, and one subject with a normal unchanged weight). CONCLUSION: In 39 patients with SAS, 1-year domiciliary N-CPAP combined with weight loss resulted in a significant improvement in breathing during sleep and in sleep fragmentation, as judged from PSG without CPAP. Four subjects were successfully weaned, three of whom had in parallel a substantial decrease in weight.

Body Mass Index↗
PubMed1996

[Range of activity of anxiolytic and antidepressant drugs].

The treatment of depressive and anxiety disorders might be complex, due to the various clinical subtypes and frequent comorbidity of anxiety and depression. We will review some treatment characteristics of mixed anxiety-depressive disorders, pointing out their spectrum of activity and pharmacological profiles.

Anti-Anxiety Agents↗
PubMed1995

Relationship between the Newcastle scale and sleep polysomnographic variables in major depression: a controlled study.

In order to investigate the reliability of the endogenous concept of depressive illness with some sleep EEG parameters, we studied 39 male inpatients suffering from a nonbipolar major depressive episode (15 endogenous (MDDE) and 24 nonendogenous (MDDNE)) and 20 age and sex matched normal controls (C). All patients were diagnosed according to the Research Diagnostic Criteria (RDC) and the endogenous character of the episode was assessed with the Newcastle Endogenous Depression Diagnostic Index. We found significant differences for the following variables between the three groups (MDDE, MDDNE and C): sleep period time (SPT), REM latency, stage II, slow wave sleep (SWS), REM latency expressed as a continuous variable and REM latency expressed as a dichotomizing variable with a threshold of 50 min. These variables were used to compare the endogenous and the nonendogenous depressed patients and also the major depressed patients and the normal controls. Significant differences were observed between all depressed patients and control subjects for amount of SWS and REM latency which were both reduced in endogenous and nonendogenous depressed patients. No significant difference was observed between endogenous and nonendogenous depressed patients, except for the REM latency expressed with a threshold of 50 min (more frequently observed in endogenous depressed patients). Our data support the observation that SWS and REM latency are decreased in major depressive patients. However, in this age and sex controlled study, subtyping nonbipolar major depressive disorder for an endogenous character by the Newcastle Endogenous Depression Diagnostic Index (NEDDI) did not reveal further significant differences for sleep EEG variables, except for the shortening of the REM latency expressed as a dichotomizing variable.

Adult↗
PubMed1995

Cardiorespiratory transfer during sleep: a study in healthy young men.

This study tested the concept that changes in breathing parameters account for modifications in respiratory-related blood pressure (BP) and R-R interval (RRI) variability during nocturnal sleep. BP (Finapres), electrocardiogram, respiration (Respitrace), and polygraphic sleep recordings were recorded continuously in 13 healthy men aged 18-37 yr. The transfer characteristics identified by coherence and gain measures between the calibrated thoraco-abdominal motion and the respiratory-related BP and RRI variability evidenced a consistent increase during transitions from wake to light sleep and from light to deep sleep but returned to waking levels during rapid-eye-movement sleep (P < 0.0001). These changes were related to the specific modifications occurring in the respiratory rate, tidal volume, and ribcage-to-abdominal motion ratio during the different sleep stages (0.28 < r < 0.39; P < 0.0001). This study demonstrates 1) that modifications in the breathing pattern account for 8-15% of the variance in the cardiorespiratory transfer, and 2) that respiratory modulation of vagal activity is not the main mechanism controlling the magnitude of the respiratory-related BP and RRI variability during sleep.

Adolescent↗
PubMed1995

Acute, subchronic and withdrawal sleep EEG changes during treatment with paroxetine and amitriptyline: a double-blind randomized trial in major depression.

Paroxetine (30 mg), a selective serotonin (5-HT) reuptake inhibitor, was compared in a double-blind trial to amitriptyline (150 mg) in a sample of 40 inpatients aged 18-65 years who fulfilled Research Diagnostic Criteria for major depression. Patients were studied after a placebo drug washout period of 10 days and after an active 4-week treatment period. Sleep EEG recordings were performed before and at the end of the study as well as during acute treatment (first 2 days) and following withdrawal of active medication. Paroxetine shows an antidepressant effect similar to amitriptyline with a different side-effect profile typical of 5-HT reuptake inhibition. Paroxetine and amitriptyline decreased the amount of REM sleep, a well-known effect of classical antidepressants. Paroxetine also shared with other 5-HT reuptake inhibitors an alerting effect on sleep that was not shown to be detrimental on subjective sleep quality.

Adolescent↗
PubMed1995

[Sleep disorders and neuroendocrine regulation in depression].

In a series of investigations we explored 24 hour neuroendocrine profiles as well as sleep patterns in a sample of monozygotic and dizygotic normal twins as well as in a group of depressed and schizophrenic patients. Our results indicate that genetic factors influence some sleep variables, mainly the slow wave sleep. They also indicate that a disorder of circadian time-keeping (a phase advance of the biological clock) characterizes some forms of affective illness.

Adult↗