Polymorphisms in the vicinity of the hypocretin/orexin are not associated with human narcolepsy.

Human narcolepsy/cataplexy is associated with reduced hypocretin (orexin) transmission. A common preprophypocretin (HCRT) polymorphism (-909C/T) was identified and tested in 502 subjects (105 trio families, 80 Caucasian narcolepsy cases, and 107 Caucasian control subjects). This polymorphism was not associated with the disease. The promoter and 5' untranslated (5'URT) regions of the HCRT gene (-320 to +21 from ATG) were also sequenced in 281 subjects. None of the subjects carried -22T, a rare 5'UTR polymorphism previously reported to be associated with narcolepsy. The HCRT locus is not a major narcolepsy susceptibility locus.

Repetitive transcranial magnetic stimulation effects on language function depend on the stimulation parameters.

In previous studies it has been shown that picture-naming latencies can be facilitated with both suprathreshold single and repetitive transcranial magnetic stimulation (TMS/rTMS) over Wernicke's area. The aim of this study was to investigate whether low-frequency rTMS (1 Hz) or high-frequency rTMS (20 Hz) at subthreshold intensities is also capable of influencing picture naming. In 16 healthy right-hand male subjects, trains of 1 Hz or 20 Hz were applied over either Wernicke's area, Broca's area, or the primary visual cortex. The subjects had to name 20 black-and-white line drawings, which were shown immediately after rTMS and again 2 minutes later. Naming latency could be facilitated only immediately after Wernicke's area stimulation at a frequency of 20 Hz and at an intensity of 55% of the maximal stimulator output, which was more than the motor threshold. All other stimulation procedures failed to influence naming latencies. These results indicate that language functions can be facilitated in healthy subjects only by high-frequency rTMS with intensities at or above the motor threshold.

Narcolepsy and the HLA region.

Narcolepsy was first shown to be tightly associated with HLA-DR2 and DQ1 in 1983, suggesting a possible autoimmune mechanism. Early investigations failed to demonstrate this hypothesis, postulating that HLA-DR2 was only a linkage marker for another, unknown narcolepsy-causing gene. The autoimmune hypothesis is now being re-evaluated under the light of recent results. Like many other autoimmune disorders, narcolepsy usually starts during adolescence, is human leukocyte antigen (HLA)-associated, multigenic and environmentally influenced. Furthermore, HLA-association studies indicated a primary HLA-DQ effect with complex HLA class II allele interactions and a partial contribution of HLA to overall genetic susceptibility. Finally, recent result suggests that human narcolepsy is associated with the destruction of a small number of hypothalamic neurons containing the peptide hypocretins (orexins). This data is consistent with an immune destruction of hypocretin-containing cells as the most common etiology for human narcolepsy.

Hypocretin/orexin, sleep and narcolepsy.

The discovery that hypocretins are involved in narcolepsy, a disorder associated with excessive daytime sleepiness, cataplexy and unusually rapid transitions to rapid-eye-movement sleep, opens a new field of investigation in the area of sleep control physiology. Hypocretin-1 and -2 (also called orexin-A and -B) are newly discovered neuropeptides processed from a common precursor, preprohypocretin. Hypocretin-containing cells are located exclusively in the lateral hypothalamus, with widespread projections to the entire neuroaxis. Two known receptors, Hcrtr1 and Hcrtr2, have been reported. The functional significance of the hypocretin system is rapidly emerging in both animals and humans. Hypocretin abnormalities cause narcolepsy in dogs, human and mice. The role of the hypocretin system in normal sleep regulation is more uncertain. We believe hypocretin cells drive cholinergic and monoaminergic activity across the sleep cycle. Input from the suprachiasmatic nucleus to hypocretin-containing neurons may explain the occurrence of clock-dependent alertness. Other functions are suggested by pharmacological and neurochemical experiments. These include regulation of food intake, neuroendocrine function, autonomic nervous system activity and energy balance.

Identification and functional analysis of mutations in the hypocretin (orexin) genes of narcoleptic canines.

Narcolepsy is a sleep disorder affecting animals and humans. Exon skipping mutations of the Hypocretin/Orexin-receptor-2 (Hcrtr2) gene were identified as the cause of narcolepsy in Dobermans and Labradors. Preprohypocretin (Hcrt) knockout mice have symptoms similar to human and canine narcolepsy. In this study, 11 sporadic cases of canine narcolepsy and two additional multiplex families were investigated for possible Hcrt and Hcrtr2 mutations. Sporadic cases have been shown to have more variable disease onset, increased disease severity, and undetectable Hypocretin-1 levels in cerebrospinal fluid. The canine Hcrt locus was isolated and characterized for this project. Only one novel mutation was identified in these two loci. This alteration results in a single amino acid substitution (E54K) in the N-terminal region of the Hcrtr2 receptor and autosomal recessive transmission in a Dachshund family. Functional analysis of previously-described exon-skipping mutations and of the E54K substitution were also performed using HEK-293 cell lines transfected with wild-type and mutated constructs. Results indicate a truncated Hcrtr2 protein, an absence of proper membrane localization, and undetectable binding and signal transduction for exon-skipping mutated constructs. In contrast, the E54K abnormality was associated with proper membrane localization, loss of ligand binding, and dramatically diminished calcium mobilization on activation of the receptor. These results are consistent with a loss of function for all three mutations. The absence of mutation in sporadic cases also indicates genetic heterogeneity in canine narcolepsy, as reported previously in humans.

CSF hypocretin/orexin levels in narcolepsy and other neurological conditions.

OBJECTIVE: To examine the specificity of low CSF hypocretin-1 levels in narcolepsy and explore the potential role of hypocretins in other neurologic disorders. METHODS: A method to measure hypocretin-1 in 100 microL of crude CSF sample was established and validated. CSF hypocretin-1 was measured in 42 narcolepsy patients (ages 16-70 years), 48 healthy controls (ages 22-77 years,) and 235 patients with various other neurologic conditions (ages 0-85 years). RESULTS: As previously reported, CSF hypocretin-1 levels were undetectably low (<100 pg/mL) in 37 of 42 narcolepsy subjects. Hypocretin-1 levels were detectable in all controls (224-653 pg/mL) and all neurologic patients (117-720 pg/mL), with the exception of three patients with Guillain-Barré syndrome (GBS). Hypocretin-1 was within the control range in most neurologic patients tested, including patients with AD, PD, and MS. Low but detectable levels (100-194 pg/mL) were found in a subset of patients with acute lymphocytic leukemia, intracranial tumors, craniocerebral trauma, CNS infections, and GBS. CONCLUSIONS: Undetectable CSF hypocretin-1 levels are highly specific to narcolepsy and rare cases of GBS. Measuring hypocretin-1 levels in the CSF of patients suspected of narcolepsy is a useful diagnostic procedure. Low hypocretin levels are also observed in a large range of neurologic conditions, most strikingly in subjects with head trauma. These alterations may reflect focal lesions in the hypothalamus, destruction of the blood brain barrier, or transient or chronic hypofunction of the hypothalamus. Future research in this area is needed to establish functional significance.

A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains.

We explored the role of hypocretins in human narcolepsy through histopathology of six narcolepsy brains and mutation screening of Hcrt, Hcrtr1 and Hcrtr2 in 74 patients of various human leukocyte antigen and family history status. One Hcrt mutation, impairing peptide trafficking and processing, was found in a single case with early onset narcolepsy. In situ hybridization of the perifornical area and peptide radioimmunoassays indicated global loss of hypocretins, without gliosis or signs of inflammation in all human cases examined. Although hypocretin loci do not contribute significantly to genetic predisposition, most cases of human narcolepsy are associated with a deficient hypocretin system.

RTMS induces brief events of muscle atonia in patients with narcolepsy.

STUDY OBJECTIVES: To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) in patients with narcolepsy. DESIGN: Using rTMS, three patients with narcolepsy and cataplexy were investigated with and without their anticataplectic medication. rTMS of the motor cortex was performed at an intensity of 110% of resting motor threshold, a frequency of 20 Hz, and a duration of 2s. EMG activity was recorded for both the right and left first dorsal interosseous muscle (FDI). Eight healthy controls were also investigated under the same conditions. SETTING: The study was carried out in the sleep laboratory of the Neurology Department (University of Aachen). PATIENTS: One female and two male patients with narcolepsy/cataplexy. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: In three narcoleptic patients, after three days of not taking their usual anticataplectic medication, rTMS of the motorcortex induced an interruption of voluntary EMG activity in the FDI. EMG reduction lasted from 0.6 to 3.5s and was more pronounced in the hand contralateral to the stimulated hemisphere. This result was not observed in these patients when taking their regular medication nor in the normal controls. Stimulation of other cortical areas, as well as stimulation of the peripheral nervous system, did not induce muscle weakness episodes. CONCLUSIONS: We postulate that rTMS of the descending voluntary motor pathway triggers muscle atonia similar to cataplexy by indirectly activating the mechanisms responsible for the generation of muscle atonia during REM sleep and cataplexy. We conclude that rTMS, in the future, might prove to be a useful addition to the diagnostic repertoire for narcolepsy.

[Spontaneous intracranial hypotension: a rare cause of chronic headache]. / Spontane intrakranielle Hypotension: Eine seltene Ursache für chronische Kopfschmerzen.

Spontaneous intracranial hypotension is a rare cause of chronic postural headache. We report the case of a 58-year-old woman with a 1.5 year history of chronic headache in upright position, nausea and vomiting. Neurological examination was normal. The Gd-enhanced MRI of the brain showed an abnormal meningeal enhancement over the cerebral convexity. The CSF was normal. Opening pressure during lumbar puncture was 6 cm H2O in the lateral recumbent position. No evidence of underlying systemic, infectious or neoplastic diseases could be detected. The headache was alleviated under theophylline therapy. Spontaneous intracranial hypotension should be considered in the differential diagnosis of chronic postural headache. MRI revealing meningeal enhancement and low opening pressure in lumbar puncture are important findings for the diagnosis of spontaneous intracranial hypotension.

Facilitation of picture naming after repetitive transcranial magnetic stimulation.

OBJECTIVE: To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) on picture naming. BACKGROUND: Previous studies have shown that rTMS disrupts ongoing speech processes when delivered over frontal or parietal areas of the dominant hemisphere. METHODS: In 15 healthy right-handed male individuals, rTMS trains of 20 Hz with a duration of 2 seconds and an intensity of 55% of maximum stimulator output were delivered either to Wernicke's area, to the right-hemisphere homologue of Wernicke's area, to Broca's area, or to the primary visual cortex. Twenty black-and-white line drawings, which the individuals had to name as quickly as possible, were shown immediately after the completion of rTMS and again 2 minutes later. RESULTS: Immediately after the end of a train over Wernicke's area a shortening of naming latency was observed compared with naming without rTMS (p < 0.001). No significant effects on picture naming were observed 2 minutes later or at any time after stimulation of the right-hemisphere homologues of Wernicke's area, Broca's area, or the visual cortex. CONCLUSION: Repetitive transcranial magnetic stimulation over Wernicke's area leads to a brief facilitation of picture naming by shortening linguistic processing time.

X-linked dominant Charcot-Marie-Tooth neuropathy: clinical, electrophysiological, and morphological phenotype in four families with different connexin32 mutations(1).

The sensorimotor neuropathy of the Charcot-Marie-Tooth type (CMT) is the most common hereditary disorder of the peripheral nervous system. The X-linked dominant form of CMT (CMTX) is associated with mutations in the gene for the gap junction protein connexin32. We examined four CMTX pedigrees two of which had potentially novel mutations in the only coding exon of connexin32. One previously unreported missense mutation, Ala39Val, was found in a family displaying a CMT phenotype with additional upper limb postural tremor reminiscent of a Roussy-Lévy syndrome. A novel single base insertion, 679insT, is among the first mutations found in the fourth transmembrane domain of connexin32. Frameshift and premature stop of translation are supposed to result in a non-functional carboxy-terminus. Two further families had the known missense mutations Arg15Trp and Arg22Gln. Several female carriers were found normal on clinical presentation, however, the genotype was paralleled by decreased nerve conduction velocities (NCV) and slowed central conduction of brain stem auditory evoked responses (BAER). Median motor NCVs showed mild (in women) to intermediate (in males) reduction, indicating a peripheral neuropathy with a predominating axonal component. Nerve biopsy findings were consistent with the electrophysiological data showing a marked loss of large myelinated fibres and clusters of regenerating axons. Electron microscopy revealed various alterations of the axoglial attachment zone. This suggests defective axon-Schwann cell interactions which may induce the axonopathy in CMTX.

Increased susceptibility to sporadic Parkinson's disease by a certain combined alpha-synuclein/apolipoprotein E genotype.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders affecting about 1% of Western populations older than age 50. The pathological hallmark of PD are Lewy bodies, that is, intracytoplasmic inclusion bodies in affected neurons of the substantia nigra. Recently, alpha-synuclein (alpha-SYN) has been identified as the main component of Lewy bodies in sporadic PD, suggesting involvement in neurodegeneration via protein accumulation. The partially overlapping pathology of PD and Alzheimer's disease, as well as striking structural similarities of alpha-SYN and apolipoprotein E, which is a major risk factor for late-onset Alzheimer's disease, prompted us to investigate the influence of different alpha-SYN and apolipoprotein E alleles for developing sporadic PD. We performed association studies in 193 German PD patients and 200 healthy control subjects matched for age, sex, and origin. A polymorphism in the promoter region of the alpha-SYN gene (NACP-Rep1) as well as of the closely linked DNA markers D4S1647 and D4S1628 revealed significant differences in the allelic distributions between PD patients and the control group. Furthermore, the Apo epsilon4 allele but not the Th1/E47 promoter polymorphism of the apolipoprotein E gene was significantly more frequent among early-onset PD patients (age at onset, <50 years) than in late-onset PD. Regarding the combination of the Apo epsilon4 allele and allele 1 of the alpha-SYN promoter polymorphism, a highly significant difference between the group of PD patients and control individuals has been found, suggesting interactions or combined actions of these proteins in the pathogenesis of sporadic PD. PD patients harboring this genotype have a 12.8-fold increased relative risk for developing PD during their lives.

Interhemispheric inhibition in patients with multiple sclerosis.

OBJECTIVES: A single focal magnetic stimulus applied to the motor cortex of normal subjects can suppress ongoing voluntary electromyographic activity in ipsilateral small hand muscles. This inhibition is mediated from one motor cortex to the contralateral side via a transcallosal pathway. METHODS: We have investigated transcallosal inhibition in 24 patients with definite multiple sclerosis (MS) and in 24 healthy volunteers. A focal magnetic stimulus was applied to the hand area of the motor cortex and the onset latency of the inhibition of the ongoing EMG activity of the ipsilateral first dorsal interosseus muscle was evaluated. Cortico-motor conduction time to the same muscle was revealed, using a magnetic stimulus over the contralateral motor cortex. The difference between these values was calculated as transcallosal conduction time. Cerebral magnetic resonance imaging (MRI) scans including sagittal T2-weighted images were performed in 18 patients. RESULTS: The depth of inhibition (maximal inhibition as percentage of the baseline EMG) in the MS patients was comparable to normal values, but the transcallosal conduction time was significantly delayed (patients 17.2 +/- 6.4 ms; normal subjects 12.2 +/- 2.6 ms; P < 0.001). The duration of the inhibition was significantly prolonged in MS patients (patients 47.9 +/- 20.9 ms; normal subjects 38.9 +/- 10.1 ms; P = 0.02). Transcallosal conduction time was delayed in 11 (46%) of 24 patients, compared with normal subjects. It exceeded the normal range (mean +/- 2.5 SD) in one normal subject (specificity 96%). No correlation could be found between the size or extent of the lesions obtained from the MRI scan and the onset latency or the depth of the inhibition. CONCLUSIONS: We conclude that conduction over transcallosal connections is significantly slower in patients with MS.

[Subacute encephalopathy with epileptic seizures in a patient with chronic alcoholism (SESA syndrome)]. / Subakute Enzephalopathie mit epileptischen Anfällen bei einem Patienten mit chronischem Alkoholismus (SESA-Syndrom).

Subacute encephalopathy with seizures in alcoholics (SESA syndrome) is a rare disease entity following chronic alcohol ingestion. It is quite distinct from alcohol withdrawal syndromes, such as delirium, withdrawal seizures or CNS complications of alcohol, such as Wernicke-Korsakow syndrome, central pontine myelinolysis or Marchiafava-Bignami disease, and was proposed in 1981 by Niedermeyer and coworkers. This syndrome consists of multiple neurological deficits, such as hemiparesis or hemianopia, and of recurrent focal and generalized seizures associated with prominent EEG features (periodic lateralized discharges, PLEDs). A 72-year-old Caucasian male with chronic alcoholism and an otherwise unremarkable past medical history was admitted to our hospital because of several secondary generalized simple partial seizures. Laboratory investigations revealed elevated levels of gamma-glutamyltranspeptidase and of mean corpuscular volume. Other laboratory investigations and the CSF examinations on three occasions revealed normal values. Cranial computed and magnetic resonance tomography showed cerebral microangiopathy and generalized atrophy. Despite triple anticonvulsive therapy and an intravenous treatment with acyclovir and thiamine, the epileptic seizures persisted. Several EEGs revealed left parietooccipital periodic lateralized epileptiform discharges (PLEDs). The patient died of an intercurrent pulmonary infection about 3 months after the onset of symptoms. The described clinical picture resembles the symptoms of SESA syndrome.

[The outcome of D2 lymphadenectomy on staging and prognosis of stomach carcinoma--a prospective study]. / Der Einfluss der D2-Lymphadenektomie auf Staging und Prognose des Magenkarzinoms--Eine prospektive Studie.

The influence of D2-lymphadenectomy on staging and prognosis of gastric cancer was evaluated in a study including 195 consecutive patients (1986-1994). An impressive state migration could be proven in the UICC stages II, IIIa und IIIb, which led to significant differences in the survival rates for stages II and IIIa. We conclude that an extended lymphadenectomy contributes mainly to the accuracy of staging, while the improvement of the survival rates in studies comparing D1- with D2-lymphadenectomy is caused mainly by stage migration ("Will-Rogers phenomenon").

[Prognostic improvement by R1 and R2 lymphadenectomy in stomach carcinoma]. / Zur Frage der Prognoseverbesserung durch R1- und R2-Lymphadenektomie beim Magencarcinom.

In 1986 systematic R2 lymphadenectomy was introduced into the surgery for gastric carcinoma in our institution. In an historic analysis 381 patients of the years 1980-1992 were investigated. The effect of R2 lymphadenectomy was studied after R0 resection and exclusion of inhospital mortality. 81 matched pairs of patients with and without lymphadenectomy (LA) were restaged according to the latest classification of the UICC (1987) and compared in an univariate and multivariate analysis. A significant improvement of the estimated 5-year survival-rate was only seen in UICC-stages II (p = 0.05), IIIA (p = 0.01) and patients without lymph node metastases (pN0, p = 0.01). The multivariate analysis did not show an independent effect of LA on prognosis but of the oncological parameters pT and pN (p = 0.0001). We conclude that LA improves the prognosis of gastric carcinoma in certain early stages but the effect is not as impressive as expected.