Search PubMed⌕ Search

Biomedical subjects

E Mignot

Publications and source records attributed to E Mignot.

At least 73 records · Page 4Linked to original sources
PubMed1999

Construction and characterization of an eightfold redundant dog genomic bacterial artificial chromosome library.

A large insert canine genomic bacterial artificial chromosome (BAC) library was built from a Doberman pinscher. Approximately 166,000 clones were gridded on nine high-density hybridization filters. Insert analysis of randomly selected clones indicated a mean insert size of 155 kb and predicted 8.1 coverage of the canine genome. Two percent of the clones were nonrecombinant. Chromosomal fluorescence in situ hybridization studies of 60 BAC clones indicated no chimerism. The library was hybridized with dog PCR products representing eight genes (ADA, TNFA, GCA, MYB, HOXA, GUSB, THY1, and TOP1). The resulting positive clones were characterized and shown to be compatible with an eightfold redundant library.

Animals↗
PubMed1999

Nocturnal sleep and daytime sleepiness in normal subjects with HLA-DQB1*0602.

Narcolepsy, a neurological disorder characterized by excessive daytime sleepiness and abnormal REM sleep, is known to be tightly associated with the Human Leukocyte Antigen (HLA) DQ allele DQB1*0602. In this study, we have explored the possibility that normal subjects carrying this HLA allele (25% of the general population) could display subclinical REM sleep abnormalities and increased daytime sleepiness. Data from 525 middle-aged adults enrolled in the Wisconsin Sleep Cohort study were used for this analysis. Nocturnal polysomnography, sleep latency during the multiple sleep latency test (MSLT), and questionnaire items pertaining to excessive daytime sleepiness were compared between DQB1*0602 positive (n = 132) and negative (n = 393) participants. Results indicate shorter REM latency whether or not the latency was adjusted for wake after sleep onset (p = 0.003) and p = 0.02 respectively), increased sleep efficiency (p = 0.06) and decreased percent time spent in stage I sleep (p = 0.02) during nocturnal polysomnography in DQB1*0602 subjects. Data gathered using the Multiple Sleep Latency Test or the Epworth and Stanford sleepiness scales did not differentiate between DQB1*0602 positive and negative subjects. These results support the hypothesis that polymorphisms at the level of HLA DQ modulates sleep tendencies in humans.

Adult↗
PubMed1999

Validation of a cataplexy questionnaire in 983 sleep-disorders patients.

Our goal was to validate a self-administered narcolepsy questionnaire focusing on cataplexy. Nine hundred and eight three consecutive subjects entering the Stanford Sleep Disorder Clinic completed the questionnaire. Clinic physicians reported on the presence or absence of "clear-cut" cataplexy. Responses to 51 cataplexy-related questionnaire items were compared between subjects with clear-cut cataplexy (n = 63) and all other patients (n = 920). As previously reported, a large portion of the non-narcoleptic population was found to experience muscle weakness with various intense emotions (1.8% to 18.0%) or athletic activities (26.2% to 28.8%). Factor analysis and Receiver Operating Characteristic Curve (ROC) analysis were used to determine the most predictive items for clear-cut cataplexy. Most strikingly, cataplexy was best differentiated from other types of muscle weakness when triggered by only three typical situations: "when hearing and telling a joke," "while laughing," or "when angry." Face or neck, rather than limbs, were also more specifically involved in clear-cut cataplexy. Other items, such as length of attacks, bilaterality, and alteration in consciousness, were poorly predictive. A simple decision tree was constructed to isolate high-(91.7%) and low-(0.6%) risk groups for cataplexy. This questionnaire will be used to increase diagnostic consistency across clinical centers, thus providing more homogenous subject pools for clinical and basic research studies.

Adolescent↗
PubMed1999

Neuronal degeneration in canine narcolepsy.

Narcolepsy is a lifelong illness characterized by persistent sleepiness, hypnagogic hallucinations, and episodes of motor paralysis called cataplexy. We have tested the hypothesis that a transient neurodegenerative process is linked to symptom onset. Using the amino-cupric silver stain on brain sections from canine narcoleptics, we found elevated levels of axonal degeneration in the amygdala, basal forebrain (including the nucleus of the diagonal band, substantia innominata, and preoptic region), entopeduncular nucleus, and medial septal region. Reactive neuronal somata, an indicator of neuronal pathology, were found in the ventral amygdala. Axonal degeneration was maximal at 2-4 months of age. The number of reactive cells was maximal at 1 month of age. These degenerative changes precede or coincide with symptom onset. The forebrain degeneration that we have observed can explain the major symptoms of narcolepsy.

Animals↗
PubMed1999

Locus coeruleus neurons: cessation of activity during cataplexy.

Cataplexy, a symptom of narcolepsy, is a loss of muscle tone usually triggered by sudden, emotionally significant stimuli. We now report that locus coeruleus neurons cease discharge throughout cataplexy periods in canine narcoleptics. Locus coeruleus discharge rates during cataplexy were as low as or lower than those seen during rapid-eye-movement sleep. Prazosin, an alpha1 antagonist, and physostigmine, a cholinesterase inhibitor, both of which precipitate cataplexy, decreased locus coeruleus discharge rate. Our results are consistent with the hypothesis that locus coeruleus activity contributes to the maintenance of muscle tone in waking, and that reduction in locus coeruleus discharge plays a role in the loss of muscle tone in cataplexy and rapid-eye-movement sleep. Our results also show that the complete cessation of locus coeruleus activity is not sufficient to trigger rapid-eye-movement sleep in narcoleptics.

Adrenergic alpha-Antagonists↗
PubMed1999

A human period gene (HPER1) polymorphism is not associated with diurnal preference in normal adults.

Mammalian circadian rhythmicity has recently been shown to be regulated at the genetic level by transcription--translation feed-back loops. Key molecular components such as Clock, Bmal-1, Timeless and three Period proteins have been isolated in mammals. In this study, we hypothesized that polymorphisms at the level of one of these genes--HPER1--could be associated with differential morningness-eveningness tendencies. The sample comprised 463 middle-aged participants enrolled in the Wisconsin Sleep Cohort Study. Diurnal preferences were evaluated using the Horne-Ostberg questionnaire. An A to G synonymous substitution at position 2548 was identified in HPER1 c-DNA sequence by comparing available sequence data. This polymorphism was verified by sequencing and typed using established oligotyping techniques in all subjects, yielding allele frequencies of 0.85 and 0.15 for HPER1 2548G and HPER1 2548A, respectively. Morningness-eveningness scores were then compared between genotype groups. In contrast to data previously published using a Clock polymorphism, scores did not differ significantly across HPER1 groups. These results suggest that polymorphism at the level of HPER1 does not significantly modulate morningness-eveningness tendencies in the general population.

Adult↗
PubMed1999

Drug treatment of patients with insomnia and excessive daytime sleepiness: pharmacokinetic considerations.

Insomnia and excessive daytime sleepiness (EDS) are frequently observed conditions in the general public. A national survey in the USA in 1979 indicated that 35% of American adults experience insomnia in the course of a year. The prevalence of EDS varies depending on the survey (0.3 to 13.3%), but a recent study stated that 2.4% of individuals reported that they continually fell asleep at work. These problems are often long term and negatively affect the individuals' quality of life. People with these sleep problems often have difficulties maintaining high levels of productivity at work or pursuing their daily activities; individuals with insomnia lack the feeling of being rested or refreshed in the morning and EDS is unavoidable in most cases. Behavioural therapy has been shown to be effective for many people affected with insomnia and EDS. However, pharmacological treatments using hypnosedatives and central nervous system (CNS) stimulants are usually necessary, and effective, for those with more severe cases. These compounds have thus been widely prescribed in clinical practice (e.g., 2.6% of all adults surveyed used medically prescribed hypnosedatives and 4.5% used over-the-counter drugs to promote sleep). The onset and duration of action of these hypnosedatives and CNS stimulant drugs are important factors to be considered when prescribing these compounds. These factors primarily depend on physicochemical properties (lipid solubility and protein binding), as well as the pharmacokinetic profile (absorption, distribution, elimination and clearance) of the compounds. Significant differences in profile exist amongst hypnosedatives and CNS stimulants, and these differences may account for the observed variations in clinical action and adverse effects during and after treatment. In this review, we will introduce recently obtained knowledge of the pharmacokinetics of hypnosedatives and CNS stimulants and their applications for patients affected with insomnia and EDS.

Humans↗
PubMed1998

Neuronal activity in the cholinoceptive basal forebrain of freely moving narcoleptic dobermans.

Cholinergic stimulation in the basal forebrain (BF) triggers cataplexy in canine narcolepsy. Extracellular single unit recordings in the BF were carried out in freely moving narcoleptic dogs to study the neuronal mechanisms mediating cataplexy induction in the BF. Among the 64 recorded neurons, 12 were wake-active, three were slow wave sleep (SWS)-active, 17 were wake-/REM-active, 11 were REM sleep-active, three were cataplexy-active, and the other 18 were state-independent. Systemic administration of physostigmine, a cholinesterase inhibitor, induces status cataplecticus, decreases SWS and increases acetylcholine levels in the BF. Firing of most of the state-dependent neurons in the BF was significantly modified by physostigmine. Some of these neurons may thus mediate sleep stage changes or the effect on cataplexy observed after cholinergic stimulation in the BF.

Acetylcholine↗
PubMed1998

A CLOCK polymorphism associated with human diurnal preference.

A single nucleotide polymorphism located in the 3' flanking region of the human CLOCK gene was investigated as a predictor of diurnal preference in a population-based random sample of 410 normal adults. Morningness-eveningness preferences were determined using the 19-item Home-Ostberg questionnaire. Subjects carrying one of the two CLOCK alleles, 3111C, had a significantly lower mean Horne-Ostberg score. The distribution of scores was clearly shifted toward eveningness for these subjects. The score difference was independent of age, sex and ethnic heritage, thus making population stratification effects unlikely to explain this difference. These subjects had a substantial 10- to 44-minute delay in preferred timing for activity or sleep episodes. We suggest that the identified polymorphism or another tightly linked polymorphism within the CLOCK gene or its regulatory elements may be responsible for the finding.

Adult↗
PubMed1998

Cerebrospinal fluid prostaglandins and corticotropin releasing factor in schizophrenics and controls: relationship to sleep architecture.

Sleep abnormalities have been consistently observed in patients with schizophrenia. Elevated levels of corticotropin releasing factor (CRF) and prostaglandins (PGs) in the cerebrospinal fluid (CSF) of patients with schizophrenia have been reported, and these neurochemical substances, known to modulate sleep in experimental animals, may play a role in these sleep abnormalities. In this study, we measured PGD2, PGE2, PGF2alpha and CRF levels in the CSF of 14 unmedicated schizophrenic patients and 14 age- and sex-matched control subjects. Polysomnographic recordings were also carried out for each subject. As expected, the sleep of the schizophrenic subjects significantly differed from that of the controls; schizophrenic subjects had a longer sleep onset latency, slept less, spent fewer minutes in stage 2 sleep and had a lower sleep efficiency. We could not, however, detect any differences in CSF CRF and PG levels between normal and schizophrenic subjects, nor could we find any correlation between CSF variables and sleep parameters in the schizophrenic subjects and the non-psychiatric controls. These results do not favor the hypothesis of a role for CRF or PGs in the pathophysiology of sleep disturbances in schizophrenia.

Adult↗
PubMed1998

Breeding history of the Stanford colony of narcoleptic dogs.

Narcolepsy is a disabling sleep disorder of unknown aetiology. In humans, the disease is mostly sporadic, with a few familial cases having been reported. In 1973 a sporadic case of narcolepsy was reported in a poodle, and in 1975 familial cases of narcolepsy occurred in dobermanns. As with human narcoleptics, these narcoleptic dogs exhibited excessive daytime sleepiness and cataplexy. A colony of narcoleptic dogs was established at Stanford University in 1976 to study the pathophysiology of the disease. Between 1976 and 1995, a total of 669 animals of various breeds were born, of which 487 survived. Dobermanns accounted for 78 per cent of the total. The narcolepsy genotype in dobermanns had no significant influence on puppy mortality rate (numbers of stillborn and survival rate). The sex, maternal parity or the age of the sire or dam had no significant effect. The percentage of stillborn puppies increased from 6.1 per cent in outbred litters to 15.4 per cent in inbred litters (P = 0.10). Birth season also had a significant effect, and the highest survival rate (P = 0.02), and the lowest percentage of stillborn puppies (P = 0.09) occurred between April and June.

Animals↗
PubMed1998

Neuropharmacological characterization of basal forebrain cholinergic stimulated cataplexy in narcoleptic canines.

Basal forebrain (BF) cholinergic regulation of cataplexy was investigated in narcoleptic canines. Specific cholinergic agonists and antagonists, and excitatory or inhibitory amino acid neurotransmitter receptor agonists, were perfused through microdialysis probes implanted bilaterally in the BF of narcoleptic canines. Cataplexy was monitored using the food-elicited cataplexy test (FECT) and recordings of electroencephalogram, electrooculogram, and electromyogram. In narcoleptic canines, carbachol and oxotremorine (10(-5)-10(-3) M), but not McN-A-343 or nicotine (10(-4)-10(-3) M), produced a dose-dependent increase in cataplexy. In addition, N-methyl-d-aspartate (10(-4)-10(-3) M) and kainic acid (10(-5)-10(-4) M) did not have any effects, while muscimol (10(-3) M) produced a weak (P < 0.10) increase in cataplexy. In control canines, carbachol (10(-5)-10(-3) M), but not oxotremorine (10(-4)-10(-3) M), produced muscle atonia after the highest concentration in one of three animals. Carbachol (10(-3) M)-induced cataplexy in narcoleptic canines was blocked by equimolar perfusion with the muscarinic antagonists atropine, gallamine, and 4-DAMP but not pirenzepine. These findings indicate that carbachol-stimulated cataplexy in the BF of narcoleptic canines is mediated by M2, and perhaps M3, muscarinic receptors. The release of acetylcholine in the BF was also examined during FECT and non-FECT behavioral stimulation in narcoleptic and control canines. A significant increase in acetylcholine release was found in both narcoleptic and control BF during FECT stimulation. In contrast, simple motor activity and feeding, approximating that which occurs during an FECT, did not affect acetylcholine release in the BF of narcoleptic canines. These findings indicate that BF acetylcholine release is enhanced during learned emotion/reward associated behaviors in canines.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1998

Development of cataplexy in genetically narcoleptic Dobermans.

Forty-two genetically narcoleptic Doberman puppies [20 pure narcoleptic (N) puppies (from four narcoleptic x narcoleptic crosses) and 22 backcross narcoleptic (BN) puppies (from six narcoleptic x heterozygous crosses)] were systematically observed during the developmental period (4-24 weeks) to assess the age at onset and severity of cataplexy, a pathological manifestation of REM sleep atonia seen in narcolepsy. The mean age of onset of cataplexy was 9.69 +/- 1.15 weeks, with a median age of 7 weeks. The severity of cataplexy increased with age and reached a plateau at around 16-24 weeks. The effects of cross type (N vs BN) and sex on the development of cataplexy were analyzed. There was no difference in severity between N and BN puppies (P = 0.51). However, females had more severe cataplexy than males (P = 0.01), and this trend was preserved in five of the six litters that had both male and female puppies. These results suggest that the pathophysiological process in genetic canine narcolepsy emerges during the early developmental period and that it may involve a differential development in males and females. Furthermore, our results revealed that cataplexy onset corresponds to the emergence of adult-like REM sleep and to previously reported neuroanatomical and neurochemical abnormalities in canine narcolepsy.

Age of Onset↗
PubMed1998

Characterization of 12 microsatellite loci of the human MHC in a panel of reference cell lines.

The human genome contains a large number of interspersed microsatellite repeats which exhibit a high degree of polymorphism and are inherited in a Mendelian fashion, making them extremely useful genetic markers. Several microsatellites have been described in the HLA region, but allele nomenclature, a set of broadly distributed controls, and typing methods have not been standardized, which has resulted in discrepant microsatellite data between laboratories. In this report we present a detailed protocol for genotyping microsatellites using a semi-automated fluorescence-based method. Twelve microsatellites within or near the major histocompatibility complex (MHC) were typed in the 10th International Histocompatibility Workshop homozygous typing cell lines (HTCs) and alleles were designated based on size. All loci were sequenced in two HTCs providing some information on the level of complexity of the repeat sequence. A comparison of allele size obtained by genotyping versus that obtained by direct sequencing showed minor discrepancies in some cases, but these were not unexpected given the technical differences in the methodologies. Fluorescence-based typing of microsatellites in the MHC described herein is highly efficient, accurate, and reproducible, and will allow comparison of results between laboratories.

Alleles↗
PubMed1998

Genetic studies in the sleep disorder narcolepsy.

Narcolepsy is a chronic neurologic disorder characterized by excessive daytime sleepiness and abnormal manifestations of REM sleep including cataplexy, sleep paralysis, and hypnagogic hallucinations. Narcolepsy is both a significant medical problem and a unique disease model for the study of sleep. Research in human narcolepsy has led to the identification of specific HLA alleles (DQB1*0602 and DQA1*0102) that predispose to the disorder. This has suggested the possibility that narcolepsy may be an autoimmune disorder, a hypothesis that has not been confirmed to date. Genetic factors other than HLA are also likely to be involved. In a canine model of narcolepsy, the disorder is transmitted as a non-MHC single autosomal recessive trait with full penetrance (canarc-1). A tightly linked marker for canarc-1 has been identified, and positional cloning studies are under way to isolate canarc-1 from a newly developed canine genomic BAC library. The molecular cloning of this gene may lead to a better understanding of sleep mechanisms, as has been the case for circadian rhythms following the cloning of frq, per, and Clock.

Alleles↗
PubMed1998

HLA-DQB1*0602 homozygosity increases relative risk for narcolepsy but not disease severity in two ethnic groups. US Modafinil in Narcolepsy Multicenter Study Group.

Narcolepsy is a neurological disorder known to be tightly associated with HLA-DQA1*0102 and DQB1*0602. In this study, we have examined if homozygosity for DQB1*0602 increases disease susceptibility and/or severity. Patients diagnosed at Stanford University (n=160) or enrolled in a multicenter clinical trial (n=509) were included in this analysis. In both African-Americans and Caucasian-Americans with or without cataplexy, a significantly higher than expected number of subjects were DQB1*0602 homozygotes. Relative risks were 2-4 times higher in DQB1*0602 homozygotes vs heterozygotes across all patient groups. In contrast, symptom severity did not differ between DQB1*0602 homozygous and heterozygous subjects. These results indicate that HLA-DQB1*0602 homozygosity increases susceptibility to narcolepsy but does not appear to influence disease severity.

Adult↗