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Biomedical subjects

S Tufik

Publications and source records attributed to S Tufik.

At least 55 records · Page 3Linked to original sources
PubMed2003

IGF-I, IGF-BP3, and GH serum levels after stimulation tests in prepubertal allergic boys.

The prevalence of short stature (SS, < 3rd percentile NCHS) among children with respiratory allergy (asthma and/or rhinitis) varies from 2% to 10%. In spite of several studies, the etiology of SS in those patients remains unknown. We evaluated growth hormone (GH) serum levels in response to two stimulating tests (standardized exercise and clonidine) in prepubertal boys (G1P1, Tanner; 8 years and 5 months to 14 years) with SS, 14 of them with respiratory allergy (A, positive skin prick test to D. pteronyssinus) and 5 nonallergic children (NA). Other causes of SS were excluded in both groups. Patients had mild asthma and/or rhinitis, and they had never received inhaled or systemic corticosteroid at any time. Tests were performed on different days, at least 1 week apart. [To prevent exercise-induced asthma, 30 min before the exercise test, allergic children inhaled disodium cromoglycate (2 mg)]. GH serum levels (Immunoassay, AIA-PACK HGH, Tosoh Co, Japan) were determined at the following times: exercise (E)--basal, 5, 15, and 30 min after exercising for 6 min; clonidine (C)--basal, 30, 60, and 90 min after clonidine (0.15 mg/m2 body surface) ingestion. A response was considered positive when GH serum levels reached the minimum of 10 ng/ml. Among (the allergic) A patients, four responded to both tests, five to C (clonidine) alone, four to E (exercise) alone and one had no response. Among NA, four had a positive response to both tests and one to C (clonidine) alone. The serum levels of insulin-like growth factor I (IGF-I) (DSL-5600 Active TM IGF-I Coated-Tube IRMA [DSL Lab Inc, USA]) and its binding protein (IGF-BP3) (DSL-6600 Active TM IGF-BP3 Coated-Tube IRMA [DSL Lab Inc, USA]) were within the normal range except for one A child. Bone age was delayed in relation to chronological age in all children, but adequate for height age. All children had delayed skeletal age in relation to chronological age, but bone age was normal for height. We concluded that in the children studied a deficiency of GH does not seem to be responsible for SS.

Adolescent↗
PubMed2002

Effects of melatonin on orofacial movements in rats.

RATIONALE: While reserpine-induced oral movements (OM), an animal model of tardive dyskinesia, are more persistent in old than in adult rats, old animals present spontaneous OM, which are phenomenologically similar to those presented by reserpine-treated adult rats. We postulate that these OM may be the result of oxidative stress induced by both age and reserpine treatment. OBJECTIVES: We intended to determine the preventative effects of exogenous melatonin (one of the most important endogenous antioxidants) as well as suppression of endogenous melatonin via continuous exposure to light on reserpine- or age-induced OM in rats. METHODS: Adult (4 months of age) male Wistar rats were repeatedly treated with saline or melatonin (5 mg/kg, IP) and saline or reserpine and kept under a 12-h light/dark cycle for quantification of reserpine-induced OM as well as oxidative stress (via quantification of lipid peroxidation). To verify the effects of endogenous melatonin suppression on reserpine-induced OM, adult rats were repeatedly treated with saline or reserpine and continuously exposed to light. To verify the effects of exogenous melatonin on age-induced OM older (20 months of age) rats were long-term treated with saline or melatonin and kept under a 12-h light/dark cycle. RESULTS: Melatonin attenuated both reserpine- and age-induced OM. Reserpine enhanced striatal lipid peroxidation, that was prevented by melatonin co-administration. Continuous exposure to light increased spontaneous as well as reserpine-induced OM, indicating that endogenous melatonin may be involved in this movement disorder. CONCLUSIONS: We suggested that melatonin attenuates both reserpine- and age-induced OM in rats.

Age Factors↗
PubMed2002

Reduction of periodic leg movement in individuals with paraplegia following aerobic physical exercise.

PURPOSE: According to the American Association of Sleep Disorders, periodic leg movements (PLM) are classified into the group of intrinsic sleep disorders. Studies on PLM in individuals with spinal cord injury are very recent. The objective of the present study was to assess the efficacy of aerobic training in reducing the index/score of PLM in individuals with complete spinal cord injury. METHODS: Twelve male volunteers with complete spinal cord injury between T7 and T12 were submitted to six polysonographies (PSG Oxford Medilog SAC system; EEG, EMG and EOG: (1) basal night, (2) 12 h after a maximum effort test, (3) 36 h after a maximum effort test, (4) after 44 days of aerobic physical training, (5) 12 h after the last training session, and (6) 36 h after the last training session. All volunteers participated in a physical training program for 44 days using an arm crank ergometer. Data were analyzed statistically by the Wilcoxon test, with the level of significance set at alpha5%. RESULTS: The results demonstrated a statistically significant reduction (P < or = 0.05) in the comparison of first evaluation (35.1 PLM/h) with fifth (12.70 PLM/h) and sixth evaluation (18.5 PLM/h). CONCLUSION: This study suggests that a program of regular and systematized physical activity promotes an effective reduction of PLM in individuals with spinal cord injury.

Adult↗
PubMed2002

Hormonal and behavioural responses of paradoxical sleep-deprived rats to the elevated plus maze.

Activation of the hypothalamic-pituitary-adrenal (HPA) axis is observed immediately after 96 h of paradoxical sleep (PS) deprivation. However, when individually or group PS-deprived rats are challenged with a mild stressor, they exhibit a facilitation of the corticosterone response, and a faster return to basal levels than control rats. Because the housing condition influences coping behaviour, we tested whether the type of PS deprivation (individually or in group) influenced anxiety-like behaviour in the elevated plus-maze and the accompanying adrenocorticotropin (ACTH) and corticosterone responses. Individually (I-DEP) or group deprived (G-DEP) rats and their appropriate control groups were either killed immediately after 96 h of sleep deprivation (time-point 0 or 'basal') or exposed to a 5-min test on the elevated plus maze and sampled 5, 20 or 60 min after test onset. Control of I-DEP rats showed reduced locomotor activity and augmented anxiety-like behaviour, replicating the effects of social isolation. Although I-DEP rats exhibited higher motor activity than cage control rats, these groups did not differ in regard to the percentage of entry and time spent in the open arms. G-DEP rats, in turn, ambulated more, entered and remained longer in the open arms, exhibiting less anxiety-like behaviour. PS-deprived rats exhibited higher ACTH and corticosterone 'basal' secretion than control rats. For all groups, peak ACTH secretion was reached at the 5-min time-point, returning to unstressed basal levels 60 min after the test, except for G-DEP rats, which showed a return at 20 min. Peak levels of corticosterone occurred at 5 min for PS-deprived groups and at 20 min for control groups. G-DEP rats showed a return to 'basal' unstressed levels at 20 min, whereas the I-DEP and control groups did so at 60 min. A negative correlation between exploration in the open arms and hormone concentrations was observed. These data indicate that housing condition influences the subsequent behaviour of PS-deprived rats in the EPM which, in turn, seems to determine the secretion profile of ACTH and corticosterone in response to the test.

Adrenocorticotropic Hormone↗
PubMed2002

Sleep deprivation reduces total plasma homocysteine levels in rats.

Hyperhomocysteinemia has been associated with pathological and stressful conditions and is a risk factor for cardiovascular disease. Since sleep deprivation is a stressful condition that is associated with disruption of various physiological processes, we investigated whether it would also be associated with increases in plasma homocysteine levels. Further, since hyperhomocysteinemia may promote oxidative stress, and we had previously found evidence of oxidative stress in brain following sleep deprivation, we also searched for evidence of systemic oxidative stress by measuring glutathione and thiobarbituric acid reactive substance levels. Rats were sleep deprived for 96 h using the platform technique. A group was killed after sleep deprivation and another two groups were allowed to undergo sleep recovery for 24 or 48 h. Contrary to expectation, plasma homocysteine was reduced in sleep-deprived rats as compared with the control group and did not revert to normal levels after 24 or 48 h of sleep recovery. A trend was observed towards decreased glutathione and increased thiobarbituric acid reactive substance levels in sleep-deprived rats. It is possible that the observed decreases in homocysteine levels may represent a self-correcting response to depleted glutathione in sleep-deprived animals, which would contribute to the attenuation of the deleterious effects of sleep deprivation.

Animals↗
PubMed2002

Paradoxical sleep deprivation increases plasma endothelin levels.

The endothelins (ET-1, 2 and 3) constitute a family of 21 amino acid peptides with potent biological activities. ET-1 is one of the most potent endogenous vasoconstrictors so far identified and its increased concentration in plasma appears to be closely related to the pathogenesis of arterial hypertension as well as to obstructive sleep apnea (OSA). OSA patients exhibit repetitive episodes of apnea and hypopnea that result in hypoxia and consecutive arousals. These patients are chronically sleep deprived, which may aggravate the hypertensive features, since literature data show that sleep deprivation results in hypertension both in humans and in animals. Based on the reported relationship between ET-1, hypertension and sleep deprivation consequences, the purpose of the present study was to determine plasma ET concentrations in paradoxical sleep-deprived animals. Male Wistar rats, 3 to 4 months old (N = 10 per group), were deprived of sleep for 24 and 96 h by the platform technique and plasma ET-(1/2) was measured by radioimmunoassay. Analysis of plasma revealed that 96 h of sleep deprivation induced a significant increase in ET-(1/2) release (6.58 fmol/ml) compared to control (5.07 fmol/ml). These data show that sleep deprivation altered plasma ET-(1/2) concentrations, suggesting that such an increase may participate in the genesis of arterial hypertension and cardiorespiratory changes observed after sleep deprivation.

Analysis of Variance↗
PubMed2002

Sawtooth waves during REM sleep after administration of haloperidol combined with total sleep deprivation in healthy young subjects.

We sought to examine the possible participation of dopaminergic receptors in the phasic events that occur during rapid eye movement (REM) sleep, known as sawtooth waves (STW). These phasic phenomena of REM sleep exhibit a unique morphology and, although they represent a characteristic feature of REM sleep, little is known about the mechanisms which generate them and which are apparently different from rapid eye movements. STW behavior was studied in 10 male volunteers aged 20 to 35 years, who were submitted to polysomnographic monitoring (PSG). On the adaptation night they were submitted to the first PSG and on the second night, to the basal PSG. On the third night the volunteers received placebo or haloperidol and spent the whole night awake. On the fourth night they were submitted to the third PSG. After a 15-day rest period, the volunteers returned to the sleep laboratory and, according to a double-blind crossover randomized design, received haloperidol or placebo and spent the whole night awake, after which they were submitted to the fourth PSG. The volunteers who were given haloperidol combined with sleep deprivation exhibited an elevation of the duration and density of the STW, without significant alterations of the other REM sleep phasic phenomena such as rapid eye movement. These findings suggest that sawtooth waves must have their own generating mechanisms and that the dopaminergic receptors must exert a modulating role since REM sleep deprivation, as well as administration of neuroleptics, produces supersensitivity of dopaminergic receptors.

Adult↗
PubMed2001

Alpha sleep characteristics in fibromyalgia.

OBJECTIVE: To characterize the patterns of alpha electroencephalographic sleep and their associations with pain and sleep in patients with fibromyalgia. METHODS: Pain and sleep symptoms of 40 female patients with fibromyalgia and 43 healthy control subjects were studied before and after overnight polysomnography. Blinded analyses of alpha activity in non-rapid eye movement (non-REM) sleep were performed using time domain, frequency domain, and visual analysis techniques. RESULTS: Three distinct patterns of alpha sleep activity were detected in fibromyalgia: phasic alpha (simultaneous with delta activity) in 50% of patients, tonic alpha (continuous throughout non-REM sleep) in 20% of patients, and low alpha activity in the remaining 30% of patients. Low alpha activity was exhibited by 83.7% of control subjects (P < 0.01). All fibromyalgia patients who displayed phasic alpha sleep, activity reported worsening of pain after sleep, compared with 58.3% of patients with low alpha activity (P < 0.01) and 25.0% of patients with tonic alpha activity (P < 0.01). Postsleep increase in the number of tender points occurred in 90.0% of patients with phasic alpha activity, 41.7% of patients with low alpha activity, and 25.0% of patients with tonic alpha activity (P < 0.01). Self ratings of poor sleep were reported by all patients with phasic alpha activity, 58.3% of patients with low alpha activity (P < 0.01), and 12.5% of patients with tonic alpha activity (P < 0.01). Patients with phasic alpha activity reported longer duration of pain than patients in other subgroups (P < 0.01). Additionally, patients with phasic alpha sleep activity exhibited less total sleep time than patients in other subgroups (P < 0.05), as well as lower sleep efficiency (P < 0.05) and less slow wave sleep (P < 0.05) than patients with a tonic alpha sleep pattern. CONCLUSION: Alpha intrusion during sleep can be of different patterns. Phasic alpha sleep activity was the pattern that correlated better with clinical manifestations of fibromyalgia.

Electroencephalography↗
PubMed2001

The variability of the apnoea-hypopnoea index.

This study was designed to evaluate the variability of the apnoea-hypopnoea index (AHI) in 20 patients with obstructive sleep apnoea-hypopnoea syndrome (OSAHS) and to determine possible relationships of this variability with other polysomnographic parameters. The subjects were recorded on four consecutive nights. The mean AHI values were not significantly altered throughout the four recording nights (P=0.67). The intraclass correlation coefficient of the AHI on the four nights was 0.92. However, the Bland and Altman plot showed that, individually, the AHI presented an important variability, which was not related to its initial value. In regard to the OSAHS severity, 50% of the patients changed the classification from the first to the subsequent nights. Thirteen of the 20 patients (65%) presented a variation in the AHI value equal or higher than 10 events h(-1). When we evaluated the AHI mean values for a specific body position and sleep stage, no difference was observed among the nights. In both supine and lateral-ventral decubitus, higher AHI was observed during Stages 1 and 2 than the other stages. Additionally, the AHI during Stages 1 and 2 and REM sleep was higher on the supine than on the lateral-ventral decubitus. The AHI in OSAHS patients presented a good correlation among the four recording nights; however, a significant individual variability should be considered, especially when AHI is applied in OSAHS classification or as a criterion of therapeutic success.

Adult↗
PubMed2001

Hypothalamic involvement in chronic migraine.

OBJECTIVES: Chronic migraine (CM), previously called transformed migraine, is a frequent headache disorder that affects 2%-3% of the general population. Analgesic overuse, insomnia, depression, and anxiety are disorders that are often comorbid with CM. Hypothalamic dysfunction has been implicated in its pathogenesis, but it has never been studied in patients with CM. The aim was to analyze hypothalamic involvement in CM by measurement of melatonin, prolactin, growth hormone, and cortisol nocturnal secretion. METHODS: A total of 338 blood samples (13/patient) from 17 patients with CM and nine age and sex matched healthy volunteers were taken. Melatonin, prolactin, growth hormone, and cortisol concentrations were determined every hour for 12 hours. The presence of comorbid disorders was also evaluated. RESULTS: An abnormal pattern of hypothalamic hormonal secretion was found in CM. This included: (1) a decreased nocturnal prolactin peak, (2) increased cortisol concentrations, (3) a delayed nocturnal melatonin peak in patients with CM, and (4) lower melatonin concentrations in patients with CM with insomnia. Growth hormone secretion did not differ from controls. CONCLUSION: These results support hypothalamic involvement in CM, shown by a chronobiologic dysregulation, and a possible hyperdopaminergic state in patients with CM. Insomnia might be an important variable in the study findings.

Adult↗
PubMed2001

Acute effect of nasal continuous positive air pressure on the ventilatory control of patients with obstructive sleep apnea.

BACKGROUND: Sleep fragmentation can decrease the awake ventilatory control. Since patients with obstructive sleep apnea (OSA) patients exhibit sleep fragmentation linked to respiratory events, their ventilatory control could be impaired. However, most of these patients are also obese, which could conversely increase the ventilatory control. The effect of nasal continuous positive airway pressure (CPAP) on the awake ventilatory control in normocapnic OSA patients is unclear. OBJECTIVES: To study the acute effect of nasal CPAP on the awake ventilatory control in normocapnic OSA patients. METHODS: 12 normocapnic OSA patients, with an apnea/hypopnea index (AHI) >15 with moderate obesity (body mass index: 33.5 kg/m2) and normal pulmonary function tests were submitted to two polysomnography studies (diagnostic and for CPAP titration). Before and after 3 consecutive nights of nasal CPAP we analyzed the hypersomnia score and the ventilatory and the mouth occlusion pressure (P.1) responses at rest (breathing room air and a mixture of 8% CO2 + 40% O2). RESULTS: The respiratory drive of OSA patients as evaluated by P.1 was in the range of the controls of our laboratory. After nasal CPAP, a significant decrease in AHI (mean: 51.9-9.4/h) and arousal (mean: 88.7-43/h) occurred, as well as improvement in nocturnal oxyhemoglobin. There was a marginal increase in DeltaV(E)/DeltaP(ET)CO2 (mean: 1.41-1.87 liters/min/ mm Hg, p = 0.09) and a significant rise in P.1/DeltaP(ET)CO2 (mean: 0.29-0.43 cm H2O/mm Hg), a better indicator of ventilatory drive. CONCLUSIONS: Normocapnic OSA patients increased their awake ventilatory drive response to a hypercapnic and hyperoxic mixture with the use of 3 consecutive nights of nasal CPAP.

Female↗
PubMed2001

Thyroid function and serum prolactin levels in patients with juvenile systemic lupus erythematosus.

OBJECTIVE: To evaluate both thyroid function and serum prolactin levels in patients with juvenile systemic lupus erythematosus (JSLE) and to detect possible correlation with disease activity. METHODS: Forty-two JSLE patients (3-15 years old at disease onset), twenty-two pubertal. All patients were evaluated according their clinical manifestations and disease activity. We determined serum prolactin, thyroid-stimulating hormone (TSH), T4, free T4, T3, thyroid peroxidasis and thyreoglobulin antibodies in all patients and controls. Thyroid ultrasonography was performed in the patients. RESULTS: We did not observe any difference in thyroid hormone and prolactin levels between patients and controls. One patient with JSLE presented with hyperthyroidism and six had thyroid antibodies. We observed abnormalities by ultrasonography in four patients (9.3%), specially heterogeneity of the gland echotexture. We did not find any correlation between prolactin levels, clinical manifestations or disease activity. CONCLUSIONS: Evaluation of thyroid function should not be routine for JSLE patients. Thyroid hormones and prolactin should be measured only in patients with clinical manifestations of hypo- or hyperthyroidism.

Adolescent↗
PubMed2000

Phosphatidylserine reverses reserpine-induced amnesia.

The effects of phosphatidylserine (PS) were studied in rats treated with reserpine (1 mg/kg) immediately after training in the passive avoidance task. In experiment I, phosphatidylserine (25 mg/kg) was administered 30 min before or immediately after training. Acute pre- or post-treatment with phosphatidylserine was effective in reversing the amnestic effect of reserpine in test trials performed 24 h and 1 week after training. Experiment II was performed to determine if the long-term pretreatment with phosphatidylserine (25 mg/kg) for 7 days is able to protect the rats against the amnestic effects of reserpine in this task. The data show that phosphatidylserine reverses the impairment induced by reserpine in trials performed 24 h and 1 week after training. These results indicate that the memory deficits associated with catecholamine depletion caused by reserpine can be attenuated by acute pre- or post-training or by long-term pretreatment with this phospholipid.

Amnesia↗
PubMed2000

Sleep rebound in animals deprived of paradoxical sleep by the modified multiple platform method.

The objective of the present study was to assess the sleep rebound of animals exposed to the modified multiple platform method (MMPM), in which cage-mate rats were placed onto narrow platforms (NP=6.5 cm in diameter), onto wide platforms (WP=14 cm in diameter) or onto a grid (GR). The last two groups were included as environmental controls for the deprivation method. Animals were implanted with bipolar electrodes in the cortex, hippocampus and neck muscle. Baseline sleep was recorded for 6 h, after which the animals were placed in one of the above-mentioned settings for 90 h and their sleep was again recorded. Comparison between baseline and post-GR recordings revealed no sleep differences in these animals. Placement of animals onto WP resulted in augmented sleep time (16%), time spent in PS (+99%), duration of PS episodes (+77%), sleep efficiency (+16%), and in reduced latency to PS (-84.8%). Finally, NP animals exhibited a dramatic increase in sleep time (+34.3%), time spent in PS (+184.7%), duration of PS episodes (+106%), and in sleep efficiency (+34.4%). Moreover, sleep latency (-52.2%) and time spent in SWS (-12.2%) were reduced. Based on the results of sleep rebound, the data indicated that placement of animals onto narrow platforms in the MMPM was an effective PS deprivation method and the grid should be considered as an adequate environmental control.

Animals↗
PubMed2000

Pituitary-adrenal axis and behavioural responses of maternally deprived juvenile rats to the open field.

Adult rats submitted to maternal deprivation (DEP) on post-natal day (pnd) 11 show smaller corticosterone (CORT) response to a saline injection than non-deprived (NDEP) rats, mainly at 30 days of age. In the present study we sought to investigate the pituitary-adrenal axis response of 30-day-old DEP rats to a 5-min open-field session, with lights and sound on. Hormone levels were assessed immediately or 20 min after the end of the stress, and were compared to basal levels. The immediate ACTH response of DEP females was the highest; this difference was no longer observed at 20 min, but hormone levels were still higher than basal. Both males and females showed an augmented CORT secretion immediately after the open field session, although only the response of NDEP females was higher than that of male counterparts. Moreover, DEP females showed a lower CORT response than their NDEP counterparts immediately after the stress. The CORT stress response remained equally elevated in males and females at the 20-min time point. Finally, DEP animals, regardless of the gender, ambulated more in the centre of the open field and displayed less grooming behaviour than NDEP pups, suggesting that DEP rats are less emotional than NDEP animals.

Adrenocorticotropic Hormone↗
PubMed2000

Differential effects of acute cold and footshock on the sleep of rats.

Several studies have shown that 1 h of immobilisation stress during the rat's active period results in rebound of paradoxical (PS) and slow wave sleep (SWS). Since the effects of stress on behaviour and physiological parameters vary according to the stimulus, the present study sought to examine the activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sleep pattern of rats submitted to 1 h of footshock, immobilisation or cold, or 18 h of PS deprivation (PSD). Stress sessions began between 0900 and 0930 h. Immediately after the end of the stress session, or at the corresponding time for controls, animals were blood sampled for determination of ACTH and corticosterone (CORT) plasma levels. In Experiment 2, animals were implanted with electrodes for basal and post-stress polysomnographic recording (6 h long). The results showed that all stressors produced an activation of the HPA axis; however, footshock induced the largest ACTH levels, whereas cold resulted in the highest CORT levels. In regard to the sleep data, immobilisation and PSD led to a rebound of SWS (+16.87% and +9.37%, respectively) and PS (+42.45% and +55.25%, respectively). Immobilisation, however, induced an increased number of PS episodes, whereas PSD resulted in longer PS episodes. Cold stress produced an exclusive rebound of SWS (+14.23%) and footshock promoted sustained alertness during the animal's resting period (+47.18%). These results indicate that different stimuli altered the sleep pattern in a distinct manner; and these alterations might be related to the state of the HPA axis activation.

Adrenocorticotropic Hormone↗
PubMed2000

Melatonin treatment does not prevent decreases in brain glutathione levels induced by sleep deprivation.

Recent findings from this laboratory revealed that sleep deprivation reduces total glutathione (GSH) levels in hypothalamus, suggesting an increased vulnerability to oxidative damage. Since melatonin has been shown to prevent oxidative damage in other experimental situations, the present study tested the effects of exogenous melatonin on sleep deprivation-induced GSH decreases. Rats were deprived of sleep for 96 h on small platforms, and melatonin (10 mg/kg body weight; i.p.) or vehicle was given twice a day. Hypothalamic GSH levels were significantly reduced in sleep-deprived groups, irrespective of melatonin treatment. Indeed, unexpectedly, melatonin treatment resulted in lower hypothalamic GSH levels in all groups, including cage controls. These results confirm that sleep deprivation reduces hypothalamic GSH and further indicate that melatonin treatment not only is ineffective in reversing this effect but may actually potentiate it.

Animals↗