Biomedical subjects

M Dumont

Publications and source records attributed to M Dumont.

At least 37 records · Page 2Linked to original sources

PubMed2002

Brain metabolic differences as a function of hemisphere, writing hand preference, and gender.

A total of 35 university-educated normal men (24 right handwriters and 11 left handwriters) and 36 age- and education-matched women (25 right handwriters and 11 left handwriters) underwent a proton magnetic resonance spectroscopy examination in seven 8 cm(3) voxels including the right and left frontal lobe tips, the right and left mid-temporal lobes, the right and left thalami, and the hypothalamus. Dependent measures were N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine/phosphocreatine (Cr) metabolite peak area ratios relative to total H(2)O. As expected, thalamic grey matter contained higher NAA ratios than telencephalic voxels (containing white and grey matter) (p < .001). The thalamic Cr/ H(2)O ratio was higher on the right, but the opposite asymmetry was observed for the temporal lobe (p < .05). Women had a higher left frontal NAA/ H(2)O ratio than men, but men had a higher hypothalamic NAA/ H(2)O ratio than women. Right-handers had a higher temporal lobe NAA/H(2)O ratio than left-handers, particularly in the left hemisphere. In addition, several significant 2- and 3-way interactions between writing hand preference, gender, and hemisphere were observed, but only in the frontal lobe.

Journal Article↗

PubMed2002

[Paget's extramammary disease of the axillae and perineum].

INTRODUCTION: Paget's extramammary disease mostly affects genital, perianal and axillary regions. Whilst triple involvement has been described in Japanese patients, simultaneous lesions of both axillary regions and the inguinal area are exceptional among European patients. We report a case of triple Paget's extramammary disease in a Caucasian patient. CASE-REPORT: A 79-year-old male patient who developed a prostatic adenocarcinoma 3 years ago, was seen for an erythemato-squamous intertrigo of both axillary folds and the pubic area, present for 10 years, not diagnosed and resistant to topical treatments. Triple Paget's extramammary disease was confirmed by both histopathological and immunohistochemical investigations. No recurrence of the prostatic adenocarcinoma was observed. DISCUSSION: Since the first description of triple Paget's extramammary disease, 28 cases have been reported in Japan. To our knowledge, this is the first case observed in a Caucasian patient. The clinical features of axillary lesions are described as pigmented or depigmented plaques, sometimes lichenoid or erosive. For some Japanese authors, a biopsy is mandatory even in the absence of clinical lesions, since typical Paget cells can be found. Immunohistochemical studies reveal CK7 expression, the marker of choice for primary extramammary Paget's disease. CK7 - would suggest underlying regional internal malignancy as well as CK20 +. Despite the fact that the immunophenotype was CK7 +/CK20- the patient developed an evolving prostatic adenocarcinoma. Although various treatments are described in the literature, surgical excision remains the first line treatment whenever possible.

Aged↗

PubMed2001

Effects of electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin.

In 1998, the authors studied the effect of residential exposure to electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin (6-OHMS) in the Quebec city, Canada, metropolitan area. A sample of 221 women living near a 735-kV line was compared with 195 women the same age living away from any power lines. Participants provided morning urine samples on 2 consecutive days and wore a magnetic dosimeter for 36 consecutive hours to measure personal magnetic exposure. The indoor electric field was assessed by spot measurements. After adjustment for other factors associated with low melatonin secretion, such as medication use or light exposure, nighttime concentration of 6-OHMS was similar in the two groups. When either 24-hour or sleep-time exposure to magnetic field or electric field measurements was used, no exposure-effect relation was evident. However, the trend of decreasing 6-OHMS concentration with age was more pronounced for women living near the lines, as was a lower 6-OHMS concentration in women with high body mass index. Chronic residential exposure to magnetic fields from high-power lines may accentuate the decrease in melatonin secretion observed in some vulnerable subgroups of the population.

Adult↗

PubMed2001

Intensive Care Delirium Screening Checklist: evaluation of a new screening tool.

OBJECTIVE: Delirium in the intensive care unit is poorly defined. Clinical evaluation is difficult in the setting of unstable, often intubated patients. A screening tool may improve the detection of delirium. METHOD: We created a screening checklist of eight items based on DSM criteria and features of delirium: altered level of consciousness, inattention, disorientation, hallucination or delusion, psychomotor agitation or retardation, inappropriate mood or speech, sleep/wake cycle disturbance, and symptom fluctuation. During 3 months, all patients admitted to a busy medical/surgical intensive care unit were evaluated, and the scale score was compared to a psychiatric evaluation. RESULTS: In 93 patients studied, 15 developed delirium. Fourteen (93%) of them had a score of 4 points or more. This score was also present in 15 (19%) of patients without delirium, 14 of whom had a known psychiatric illness, dementia, a structural neurological abnormality or encephalopathy. A ROC analysis was used to determine the sensitivity and specificity of the screening tool. The area under the ROC curve is 0.9017. Predicted sensitivity is 99% and specificity is 64%. CONCLUSION: This study suggests that the Intensive Care Delirium Screening Checklist can easily be applied by a clinician or a nurse in a busy critical care setting to screen all patients even when communication is compromised. The tool can be utilized quickly and helps to identify delirious patients. Earlier diagnosis may lead to earlier intervention and better patient care.

APACHE↗

PubMed2001

Delirium in an intensive care unit: a study of risk factors.

OBJECTIVES: (1) To establish risk factors for the development of delirium in an intensive care unit (ICU) and (2) to determine the effect of delirium on morbidity, mortality and length of stay. DESIGN: Prospective study. SETTING: Sixteen-bed medical/surgical ICU in a university hospital. PATIENTS: Two hundred and sixteen consecutive patients admitted to the ICU for more than 24 h during 5 months were included in the study. INTERVENTIONS: Medical history, selected laboratory values, drugs received and factors that may influence patient psychological and emotional well-being were noted. All patients were screened with a delirium scale. A psychiatrist confirmed the diagnosis of delirium. Major complications such as self-extubation and removal of catheters, as well as mortality and length of stay were recorded. RESULTS: Forty patients (19%) developed delirium; of these, one-third were not agitated. In the multivariate analysis hypertension, smoking history, abnormal bilirubin level, epidural use and morphine were statistically significantly associated with delirium. Traditional factors associated with the development of delirium on general ward patients were not significant in our study. Morbidity (self-extubation and removal of catheters), but not mortality, was clearly increased. CONCLUSION: Predictive risk factors for the development of delirium in studies outside the ICU may not be applicable to critically ill patients. Delirium is associated with increased morbidity. Awareness of patients at risk may lead to better recognition and earlier intervention.

Analysis of Variance↗

PubMed2001

The dispositional inference strikes back: situational focus and dispositional suppression in causal attribution.

The authors propose that correction of dispositional inferences involves the examination of situational constraints and the suppression of dispositional inferences. They hypothesized that suppression would result in dispositional rebound. In Study 1, participants saw a video of either a free or a forced speaker. Participants shown a forced speaker later made stronger dispositional inferences about a 2nd, free speaker than control participants did. Study 2 provided evidence for higher rebound among participants who reported trying harder to suppress dispositional inferences during the 1st video. In Study 3, participants were asked to focus on situational constraints or to avoid thinking about the speaker's characteristics. Only the latter instructions led to a dispositional rebound. These data support the view that the correction of dispositional inferences involves 2 processes that lead to distinct consequences in subsequent attribution work.

Adult↗

PubMed2001

A candidate prostate cancer susceptibility gene at chromosome 17p.

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

Amino Acid Sequence↗

PubMed2001

Is the relationship between adipose tissue and waist girth altered by weight loss in obese men?

OBJECTIVE: The aim of the present study was to examine whether the association of waist girth to visceral adipose tissue (AT) accumulation was altered by weight loss in abdominally obese men. RESEARCH METHODS AND PROCEDURES: We studied 45 dyslipidemic abdominally obese men (45.4 +/- 6.2 years of age; body mass index [BMI], 31.3 +/- 3.0 kg/m(2); waist circumference, 103.4 +/- 7.6 cm; total cholesterol, <6.72 mM; triglycerides, > or =1.7 mM but < or =5.65 mM; high density lipoprotein cholesterol, < or =1.2 mM). Each of them followed nutritional recommendations combined with a prescription of gemfibrozil (1200 mg/d) or a placebo for 1 year. After 6 months, a training exercise program was added at a frequency of four sessions of 60 minutes per week at 50% of maximal oxygen uptake. RESULTS: In response to the 1-year intervention program, men showed significant reductions in body weight, BMI, waist circumference, and in the partial volume of visceral and abdominal subcutaneous AT measured from two abdominal computed tomography scans performed at lumbar vertebra (L)2 to L3 and L4 to L5 levels. No change in waist-to-hip ratio was observed. Changes in visceral AT were strongly correlated with changes in body weight, BMI, and waist circumference (0.83 < r < 0.85; p < 0.001). However, a weak association was noted between waist-to-hip ratio and changes in visceral AT (r = 0.40; p < 0.05). There was no change in slopes or in intercepts before and after treatment in the relationships between volume or area of abdominal AT and anthropometric markers. DISCUSSION: Despite a greater level of the partial volume of subcutaneous AT than of the partial volume of visceral AT at baseline (p < 0.001), the greater relative reduction in the visceral AT volume in comparison with the subcutaneous AT volume suggested a preferential mobilization of visceral AT with weight loss in these abdominally obese men. The close relationship between changes in the partial volume of visceral AT and changes in cross-sectional areas of visceral AT measured at L2 to L3 (r = 0.94; p < 0.001) or L4 to L5 (r = 0.88; p < 0.001) suggests that a single computed tomography scan performed at L2 to L3 or L4 to L5 could predict changes in the partial volume of visceral AT secondary to weight loss.

Adipose Tissue↗

PubMed2001

Effect of a six month gemfibrozil treatment and dietary recommendations on the metabolic risk profile of visceral obese men.

OBJECTIVE: The aim of the present study was to investigate the effects of a 6 month gemfibrozil treatment. SUBJECTS: A sample of 64 visceral obese men (age 46+/-6 y; body mass index 31+/-3 kg/m(2); waist circumference 104+/-7 cm; mean+/-s.d.) who received dietary recommendations. METHODS: Subjects were randomly assigned to receive a placebo (n=32) or gemfibrozil (1200 mg/day) (n=32). RESULTS: In both placebo and gemfibrozil treated groups, significant reductions were noted in body weight, fat mass, waist circumference and visceral adipose tissue area measured by computed tomography (0.0001<P<0.05). Plasma cholesterol (CHOL) and apolipoprotein B (apo B) levels were also decreased in both groups (P<0.01) whereas plasma high density lipoprotein (HDL) and HDL-3-CHOL levels were only significantly (P<0.01) increased in the gemfibrozil-treated group. After the 6 month treatment period, gemfibrozil-treated men displayed significantly lower plasma triglycerides (TG) levels, compared to those who received the placebo (P<0.01). Finally, both fasting plasma insulin concentration and insulin area measured during an oral glucose load were significantly decreased only in the placebo group (P<0.05). Taken together, these results suggest that the improvement in plasma lipid/lipoprotein profile observed in gemfibrozil treated visceral obese men seems to be independent from changes in adipose tissue mass and in visceral fat accumulation. Furthermore, improvements in the plasma lipoprotein profile produced by gemfibrozil therapy appear to be independent from changes in indices of plasma glucose-insulin homeostasis.

Adipose Tissue↗

PubMed2001

Skeletal muscle low attenuation area and maximal fat oxidation rate during submaximal exercise in male obese individuals.

BACKGROUND: Muscle triacylglycerols (TG) are known to be a source of energy during submaximal exercise. OBJECTIVE: The aim of this study was to assess whether an index of muscle fat content is related to maximal fat oxidation rate (FATOXmax) in 58 obese men (mean age 46.0+/-0.8 (s.e.) y, body weight 96.4+/-1.4 kg, percentage fat: 31.9+/-0.5%) [corrected]. DESIGN: FATOXmax was defined as the highest value of fat oxidation rate, measured by indirect calorimetry, while walking on a treadmill (4.3 km/h) at three different slopes: 0% (40+/-1% of VO2max), 3% (47+/-1% of VO2max) and 6% (58+/-1% of VO2max). Fat-free mass (FFM) and fat mass (FM) were measured with the underwater technique and scans were obtained by computed tomography (CT) at the mid thigh level to assess areas of adipose tissue within skeletal muscle, ie deep adipose tissue (DAT), subcutaneous adipose tissue (SAT), skeletal muscle (M) and low attenuation skeletal muscle (LAM, range of attenuation values: 0-34 Hounsfield units). LAM and DAT were used as indices of skeletal muscle fat content. RESULTS: FATOXmax, adjusted for age, was correlated with FFM (r=0.26, P<0.05), LAM (r=0.29, P<0.05), abdominal visceral adipose tissue (r=0.30, P<0.05) and plasma free fatty acid (FFA) levels (r=0.33, P<0.05) but not with SAT (r=0.03) and DAT (r=0.21) [corrected]. In a stepwise linear multiple regression, plasma FFA, age and LAM significantly predicted FATOXmax (r2=0.27). Each independent variable explained about 9% of the FATOXmax variance. CONCLUSION: LAM makes a significant but weak contribution to the modulation of fat oxidation during submaximal exercise in obese men.

Adipose Tissue↗

PubMed2001

The wide spectrum of multidrug resistance 3 deficiency: from neonatal cholestasis to cirrhosis of adulthood.

BACKGROUND & AIMS: We have specified the features of progressive familial intrahepatic cholestasis type 3 and investigated in 31 patients whether a defect of the multidrug resistance 3 gene (MDR3) underlies this phenotype. METHODS: MDR3 sequencing, liver MDR3 immunohistochemistry, and biliary phospholipid dosage were performed. RESULTS: Liver histology showed a pattern of biliary cirrhosis with patency of the biliary tree. Age at presentation ranged from the neonatal period to early adulthood. Sequence analysis revealed 16 different mutations in 17 patients. Mutations were identified on both alleles in 12 patients and only on 1 allele in 5. Four mutations lead to a frame shift, 2 are nonsense, and 10 are missense. An additional missense mutation probably representing a polymorphism was found in 5 patients. MDR3 mutations were associated with abnormal MDR3 canalicular staining and a low proportion of biliary phospholipids. Gallstones or episodes of cholestasis of pregnancy were found in patients or parents. Children with missense mutations had a less severe disease and more often a beneficial effect of ursodeoxycholic acid therapy. CONCLUSIONS: At least one third of the patients with a progressive familial intrahepatic cholestasis type 3 phenotype have a proven defect of MDR3. This gene defect should also be considered in adult liver diseases.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

Profile of 24-h light exposure and circadian phase of melatonin secretion in night workers.

Light exposure was measured in 30 permanent night nurses to determine if specific light/dark profiles could be associated with a better circadian adaptation. Circadian adaptation was defined as a significant shift in the timing of the episode of melatonin secretion into the daytime. Light exposure was continuously recorded with ambulatory wrist monitors for 56 h, including 3 consecutive nights of work. Participants were then admitted to the laboratory for 24 h where urine was collected every 2 h under dim light for the determination of 6-sulphatoxymelatonin concentration. Cosinor analysis was used to estimate the phase position of the episode of melatonin secretion. Five participants showed a circadian adaptation by phase delay ("delayed participants") and 3 participants showed a circadian adaptation by phase advance ("advanced participants"). The other 22 participants had a timing of melatonin secretion typical of day-oriented people ("nonshifters"). There was no significant difference between the 3 groups for total light exposure or for bright light exposure in the morning when traveling home. However, the 24-h profiles of light exposure were very distinctive. The timing of the main sleep episode was associated with the timing of light exposure. Delayed participants, however, slept in darker bedrooms, and this had a major impact on their profile of light/dark exposure. Delayed and advanced participants scored as evening and morning types, respectively, on a morningness-eveningness scale. This observation suggests that circadian phase prior to night work may contribute to the initial step toward circadian adaptation, later reinforced by specific patterns of light exposure.

Adaptation, Physiological↗

PubMed2001

Human gastrocnemius medialis pennation angle as a function of age: from newborn to the elderly.

The aim of the present study was to quantify changes in human skeletal muscle pennation angle (F theta) values during growth and adult life. The human gastrocnemius medialis muscle of 162 subjects (96 males and 66 females) in the age range 0-70 years was scanned with ultrasonography. The subjects were laying prone, at rest, with the ankle maintained at 90 degrees with all muscles relaxed. F theta increased monotonically starting from birth (0 years) and reached a stable value after the adolescent growth spurt. There was a significant (p < 0.05) linear relationship between F theta and muscle thickness (TK). F theta = 0.84 (+/- 0.09) * TK + 3.15 (+/- 1.13). Human gastrocnemius medialis F theta and TK data found in the literature seem to fit the F theta-TK plot in a coherent manner, independent of the physiological or anatomical characteristics of the subject. The present findings indicate that F theta is not a constant parameter but evolves, as is the case for bone length and height, as a function of age.

Adolescent↗

PubMed2001

[Cutaneous acanthamoebiasis in a lung transplant patient].

BACKGROUND: Cutaneous acanthamoebiasis is a rare opportunistic infection in immunocompromised patients, particularly in HIV infected patients. We report a case of a primary cutaneous Acanthamoeba infection, in a patient with a double lung transplant not infected by the HIV. CASE REPORT: A 38 year-old white man, with a double lung transplant 3 years ago, developed a painful fibrinous ulceration of the right foot, with cellulitis. A few days later, two purplish nodules were observed, surrounded by an inflammatory reaction. Histologic examination revealed trophozoite and cyst forms. Therapy was begun with intravenous pentamidine and itraconazole along with topical ketoconazole and chlorhexidine, but was ineffective. Because of the renal toxicity of pentamidine, the patient was treated by dialysis. He died six months after diagnosis of Acanthamoeba infection. DISCUSSION: Acanthamoeba, a free-living amoeba is the causative organism of few human diseases. In immunocompromised hosts (particularly HIV infected), besides granulomatous amebic encephalitis, it can provoke some cutaneous lesions such as nodules, pustules, ulcerations... Skin biopsy is diagnostic: numerous amebic trophozoites and cysts are visualized. Recommended treatments are pentamidine, itraconazole and flucytosine. Due to the morbidity and mortality of acanthamoeba infection optimal therapy must be defined.

Acanthamoeba↗

PubMed2000

Interactions of dynorphin A-(1-13) and nociceptin with cardiac D2 binding sites: inhibition of ischemia-evoked release of noradrenaline from synaptosomal-mitochondrial fractions.

The effect of dynorphin A (Dyn A)-related peptides and nociceptin on the binding of the D2 receptor antagonist, [(3)H]raclopride, was examined in membrane preparations of rat heart. Non-linear regression saturation binding analysis of [(3)H]raclopride binding revealed the presence of a single high-affinity binding site with a K(d)of 4.1 n M and a B(max)of 220 fmol/mg protein. The D2 stereospecificity of [(3)H]raclopride binding was demonstrated by competition experiments using two enantiomer pairs of antagonists. (+)-Butaclamol (IC(50): 8.0 n M) and (-)-sulpiride (IC(50): 112.3 n M) were 27 000 and 24 times more potent than (-)-butaclamol (IC(50): >100 microm) and (+)-sulpiride (IC(50): 2666 n M), respectively. Nociceptin and Dyn A-(1-13) were also potent inhibitors of the binding of [3H]raclopride with shallow inhibition curves that fitted best with two sites model. Their order of potency on the low affinity site [alpha -Neo-endorphin>nociceptin>Dyn A-(2-13)>Dyn A-(1-13)>Dyn B>Dyn A-(6-10)] correlated well with their ability to inhibit the binding of [3H]nociceptin (r=0.82). The indirect nature of the inhibitory effects of the peptides on the D2 receptor was demonstrated by their inability to inhibit [(3)H]raclopride binding to a membrane preparation (Sf9 cells transfected with the human D2(long)receptor) that does not contain the ORL(1)receptor and the lack of effect of raclopride (0.1 n M-10 microm) on both [(3)H]nociceptin and [(3)H]Dyn A-(1-13) binding. Isolated cardiac mitochondrial-synaptosomal fractions submitted to ischemic conditions (1 m M iodoacetate +2 m M NaCN, 5 min at 37 degrees C) released 10.9% of their content in preloaded [(3)H]noradrenaline ([(3)H]NA). Dyn A-(1-13) (10 microm), nociceptin (10 microm) and the selective D2 receptor agonist, quinpirole (10 microm) were potent blockers of the release of [(3)H]NA evoked by the ischemic conditions. The inhibitory effect of Dyn A-(1-13), nociceptin and quinpirole were antagonized by the selective D2 receptor antagonist, raclopride (10 microm); whereas naloxone, at a concentration (1 microm) known to affect the ORL(1)receptor, blocked the effects of the peptides but not those of quinpirole. The results demonstrate the presence of D2 receptors in rat heart and suggest that Dyn A-(1-13) and nociceptin modulate ischemia-induced NA release by a mechanism that involves the participation of both ORL(1)and D2 receptors.

Animals↗

PubMed2000

Diurnal variations in the waking EEG: comparisons with sleep latencies and subjective alertness.

Daytime measures of sleep latency and subjective alertness do not correlate with one another, suggesting that they assess different aspects of alertness. In addition, their typical diurnal variations show very different time courses. Quantitative analysis of the waking electroencephalogram (EEG) has been proposed as an objective measure of alertness, but it is not clear how it compares with other measures. In this study, the waking EEG was measured in the daytime to determine the presence of diurnal variations in the activity of standard frequency bands and to compare these variations with the temporal patterns typical of sleep propensity and subjective alertness. Alertness was evaluated in four men and 12 women, aged 19-33 y. Assessments were conducted every 2 h, from 10.00 to 24.00, in the following order: a visual analogue scale of alertness, a waking EEG recording and a sleep latency test. The waking EEG was recorded with eyes open. For each recording session, 32-60 s of artefact-free signals were selected from the C3/A2 derivation, then subjected to amplitude spectral analysis. Four EEG frequency bands showed significant diurnal variations: delta, theta, sigma and beta1. None of these variations showed a significant correlation with the temporal patterns of sleep latencies or subjective alertness. At the individual level, however, theta band activity increased when subjective alertness decreased, suggesting that the theta band can be used to monitor variations in alertness in a given individual, even at the moderate levels of sleepiness experienced during the daytime.

Adult↗

PubMed2000

Contribution of autosomal loci and the Y chromosome to the stress response in rats.

Stress is a critical contributor to cardiovascular diseases through its impact on blood pressure variability and cardiac function. Familial clustering of reactivity to stress has been demonstrated in human subjects, and some rodent models of hypertension are hyperresponsive to stress. Therefore, the present study was designed to uncover the genetic determinants of the stress response. We performed a total genome linkage search to identify the loci of the body temperature response to immobilization stress in a set of recombinant inbred strains (RIS) originating from reciprocal crosses of spontaneously hypertensive rats (SHR) with a normotensive Brown Norway Lx strain. Two quantitative trait loci (QTLs) were revealed on chromosomes (Chrs) 10 and 12 (logarithm of odds scores, 2.2 and 1. 3, respectively). The effects of these QTLs were enhanced by a high sodium diet (logarithm of odds scores, 4.0 and 3.3 for Chrs 10 and 12, respectively), which is suggestive of a salt-sensitive component for the phenotype. Congenics for Chr 10 confirmed both the QTL and the salt effect in RIS. Negatively associated loci were also identified on Chrs 8 and 11. Interaction between the loci of Chrs 10 and 12 was demonstrated, with the rat strains bearing SHR alleles at both loci having the highest thermal response to stress. Furthermore, the Y Chr of SHR origin enhanced the response to immobilization stress, as demonstrated in 2 independent models, RIS and Y Chr consomics. However, its full effect requires autosomes of the SHR strain. These findings provide the first evidence for the genetic determination of reactivity to stress with interactions between autosomal loci and between the Y and autosomal Chrs that contribute to the explanation of the 46% of variance in the stress response.

Animals↗

PubMed1999

Association between melatonin secretion and daytime sleep complaints in night nurses.

STUDY OBJECTIVES: To test the hypothesis that nightworkers' diurnal sleep complaints are associated with the timing of melatonin secretion. DESIGN: After a minimum of three consecutive night shifts, the subjects were admitted to the laboratory for 24 hours during which they were allowed to eat and sleep ad lib. Urine was collected every two hours under dim illumination (<25 lux). Concentration of urinary 6-sulphatoxymelatonin (UaMT6s) was determined by radioimmunoassay. Sleep quality was assessed by questionnaires. SETTING: NA PARTICIPANTS: Two groups of 15 night nurses with mild and severe daytime sleep complaints. INTERVENTIONS: NA RESULTS: The proportion of the episode of UaMT6s excretion happening during the day (between 08:00 and 00:00 hours) was smaller in the group of nightworkers with severe daytime sleep complaints, and was negatively correlated with the severity of the complaints over the 30 subjects. A longer duration of melatonin secretion was associated with a lower severity of daytime sleep complaints. However, in most of the subjects with good daytime sleep quality, melatonin secretion remained essentially nocturnal, and the overlap with the time of their sleep episode was small or even absent. CONCLUSIONS: Timing and duration of melatonin secretion were associated with better daytime sleep quality when the subjects had an increased proportion of melatonin secreted during the day. When there was an indication of circadian phase shift, the direction of the shift was not of primary importance for daytime sleep quality. A longer duration of melatonin secretion may increase the tolerance to an abnormal circadian phase.

Adult↗