bluuebunny/crossref_metadata_2025 huggingface dataset:
Charakterisierung stabiler Bruchvorgänge in Kurzfaser‐Verbundwerkstoffen
Authors: Langer B. , Seidler S. , Grellmann W.
Published: December 2004

Im vorliegenden Bericht wird die Anwendbarkeit des Rißwider‐stands‐Konzeptes zur Erfassung und Bewertung des Rißinitiierungs‐ und ‐ausbreitungsprozesses in PA/CF‐ Verbunden diskutiert. Am Beispiel von PA/CF‐ Verbunden werden die Grenzen der Anwendung eines Standards, der sich auf die Zähigkeitsbewertung von duktilen Werkstoffen und eines Standardvorschlags der ESIS‐Gruppe TC4 „Polymers and Composites”︁, der sich auf die Zähigkeitsbewertung Zäher Kunststoffe bezieht, untersucht. Weiterhin werden zur Beschreibung der stabilen Bruchprozesse in Abhängigkeit vom Faservolumenanteil die bruchmechanischen Kennwerte TJund JTJherangezogen. Aussagen zum Initiierungsverhalten der betrachteten Verbunde werden unter Berücksichtigung der kritischen Abmessungen der Stretchzone getroffen. In Abhängigkeit vom Faservolumenanteil ist ein Optimum der Zähigkeitseigenschaften bei geringen Anteilen durch eine dahin positive Wirkung der Fasern auf die Verformungs‐ und Festigkeitseigenschaften der Verbunde festzustellen.
Evidence for mixed‐phase crystalline β‐C3N4 and c‐BN films
Authors: Rie K.‐T. , Ahn H.
Published: December 2004

In this paper strong experimental evidence is presented suggesting that we have synthesized the β‐C3N4 phase. This is a material predicted by theory to have comparable property to diamond. The films containing mixed‐phase crystalline β‐C3N4 and c‐BN were deposited on steel substrate Ck 35 by a hot filament assisted r. f. plasma CVD method using organo‐metallic precursor. The crystal structure of these mixed‐phases was identified by X‐ray diffraction (XRD) as well as transmission electron diffraction analysis (TED).
Charakterisierung faserverstärkter Leichtmetalle
Authors: Tietz H.‐D. , Behrends A. , Palm Th.
Published: December 2004

Die Einsatzmöglichkeiten für faserverstärkte Aluminiumwerkstoffe sind vielgestaltig: Die Anwendung erfolgt vor allem im Motoren, Maschinen‐ und Fahrzeugbau. Neben der Anwendung in der Feinwerktechnik für Manipulatoren sowie im Maschinenbau für Radial‐ und Kolbenverdichter besteht eine interessante Applikation bei der Herstellung von Kolben für Verbrennungsmotoren. Durch die hohe Verschleiß‐ und Temperaturwechselbeständigkeit gegenüber unverstärktem Aluminium sowie der Masseeinsparung gegenüber herkömmlichen Kolbenwerkstoffen stellen diese Verbundwerkstoffe vor allem bei der Steigerung der Leistungsfähigkeit eine gute Alternative dar. Die durch den Einsatz von Aluminium‐Matrix‐Verbundwerkstoffen mögliche größere Brennraummuldenhinter‐schneidung ermöglicht eine bessere Verwirbelung bzw. Verbrennung des Kraftstoffgemisches. Dadurch erhöht sich der Wirkungsgrad des Motors, und die Emission von Schadstoffen wird gesenkt.
Zeitstandfestigkeit und Hochtemperatur‐schädigung von Incoloy 800 HT nach Lösungsglühbehandlung und langzeitiger Hochtemperaturauslagerung
Authors: El‐Magd E. , Nicolini G.
Published: December 2004

In der vorliegenden Arbeit wird der Einfluß der Wärmebehandlung, insbesondere der einer langzeitigen Hochtemperaturauslagerung, auf die Zeitstandfestigkeit und die interkristalline Schädigung der Eisenbasislegierung Incoloy 800 HT (X10 NiCrAlTi 32 20 HT) untersucht. Dabei werden zum einen der lösungsgeglühte Zu‐stand und zum anderen langzeitig, bis zu einer Gesamtdauer von 3000h, überalterte Werkstoffzustände bei zwei Versuchstemperaturen im Zeitstandexperiment miteinander verglichen. Die Ergebnisse metallographischer und elektronenmikroskopischer Untersuchungen zur Beeinflussung der auftretenden interkristallinen Schädigung durch die Langzeitauslagerung werden vorgestellt und mit einem quantitativen Schädigungsparameter beschrieben. Die auftretende Schädigung im überalterten und löungsgeglühten Werkstoff nach Zeitstandbeanspruchung werden miteinander verglichen.
Kraft‐Eindringtiefe‐Messungen mit verschiedenen pyramidenförmigen Indentern
Authors: Rother B.
Published: December 2004

Kraft‐Eindringtiefe‐Messungen werden mit einem Vickers‐, einem Berkovich‐ und einem Knoop‐Indenter auf Kompaktproben aus Keramik, Glas, Metall und aus einem Polymerwerkstoff durchgeführt. Die Bewertung der Kraft‐Eindringtiefe‐Daten erfolgt in Form einer indenterspezifischen Energiedichte, welche als Härteäquivalent bezeichnet wird.

Ein Prinzip zur Umrechnung von Härteäquivalenten verschiedener pyramidenförmiger Indenter wird hergeleitet und auf die Meßergebnisse angewandt. Das Umrechnungsprinzip ist im Rahmen der Meßgenauigkeit materialunabhängig. Der Umrechnungsfaktor wird aus dem durch den eindringenden Indenter verdrängtem Materialvolumen abgeleitet.
Testverfahren zur bruchmechanischen Charakterisierung der Delamination gekrümmter Verbundwerkstoffe
Authors: Beckert W. , Lauke B. , Voigtländer R.
Published: December 2004

Ausgehend von einer makroskopischen, bruchmechanischen Betrachtung werden die Deformation und das Delaminationsversagen beim, ‚Curved Double Cantilever Beam Test mit’︁ einem Finite‐Elemente‐Modell untersucht. Dieser Test wird zur Charakterisierung des Delaminationswiderstandes von gekrümmten Probekörpern aus faserverstärkten Verbundwerkstoffen eingesetzt, die z. B. im Resultat einer Wickeltechnologie entstehen. Die Interpretation der experimentellen Ergebnisse wird für diesen Test durch verschiedene Faktoren erschwert, wie z. B. gekrümmte Probengeometrie, Auftreten Starker Deformationen und brchmechanischer, ‚Mixed‐Mode’︁‐Belastungen. Aufgrund dieser Schwierigkeiten konnte bisher kein spezielles Deformationsmodell für den Versuch angegeben werden. Die vorgestellte Finite‐Elemente‐Modellierung liefert die Basis für die Ermittlung der kritischen Energiefreisetzungsrate Gc der Delamination aus dem CDCB‐Test. Es kann gezeigt werden, daß ein einfaches, jedoch hinreichend genaues empirisches Verfahren zur Bestimmung von Gc aus den experimentellen Resultaten existiert, obwohl die Deformation der Probe nichtlinear ist und aufgrund der wirkenden Scherdeformationen auch mit aufwendigen analytischen Modellen nicht befriedigend beschrieben werden kann. Trotz der unsymmetrischen Geometrie der CDCB‐Probe ist der Mode‐II‐Anteil der Belastung bei mittiger Lage der Rißebene in der Probe vernachlässigbar. Allerdings ergeben sich bei bereits geringen Abweichungen der Rißlage von der Mittelebene der Probe starke Mode‐II‐Beiträge. In der Praxis muß daher vom Auftreten schwierig einschätzbarer ‚Mixed‐Mode’︁‐Situationen bei der Delamination ausgegangen werden. Die theoretische Untersuchung wird durch experimentelle Ergebnisse an Glasfaser/Polyamid 6‐Proben uuntersetzt.
Duroplastische Formmassen für Gleitlager
Authors: Haase I. , Franke R. , Schimke M.
Published: December 2004

Tribologische Untersuchungen an duroplastischen Formmassen zeigten, daß diese Werkstoffe in Abhängigkeit von den verwendeten Füllstoffen und/oder von tribologischen Additiven für den Einsatz unter geschmierten Gleitreibungsbedingungen geeignet sind. Hochgraphithaltige Formmassen weisen auch unter Trockenreibungsbedingungen einen ausreichenden Verschleißwiderstand auf, wenn die Pressungen nicht zu hoch gewählt werden.
Mikrostruktur und Anlaßverhalten aufgedampfter bzw. thermisch gespritzter ZrO2‐Schichten auf metallischen Substraten
Authors: Wehner B. I. , Blennemann K. P. , Babiak Z. , Selvadurai‐Laßl U. , Köster U.
Published: December 2004

Durch ihren Einsatz in Gasturbinen sind plasmagespritzte Wärmedämmschichten aus teilstabilisierten Zirkoniumdioxid auf metallischen Substraten ein Beispiel für einen in der Praxis eingesetzten Schichtverbundwerkstoff aus Keramik und Metall. Die damit verbundenen Probleme vor allem im Bereich der Grenzflächenhaftung sind immer noch teilweise unverstanden [1,2,3]. In der vorliegenden Arbeit werden verschiedene systeme elektronenmikroskopisch untersucht, bei denen eine keramische ZrO2‐Schicht auf ein metallisches Substrat aufgedampft bzw. thermisch gespritzt worden ist. Im Vordergrund steht die Gefügeanalyse des Verbundwerkstoffes, wobei der Versuch unternommen wird, mit Hilfe der durch TEM‐Querschliffe möglichen Zielpräparation auch die Grenzflächenmorphologie aufzuklären.
Mikromechanische Bewertung von mineralgefüllten Kunststoffen mit Hilfe dielektrischer Relaxationsspektroskopie und Mechano‐Dielektrometrie
Authors: Schreyer G. W. , Bartnig K. , Sander M.
Published: December 2004

Dieser Beitrag beschreibt die Möglichkeit der quantitativen Bestimmung von Rißbildungsgrenzen polarer, mineralmodifizierter Kunststoffe durch Kombination von mechanischem Experiment und dielektrischer Meßtechnik. Durch Ermittlung der dielektrischen Kennfunktion tan δ = f (ϵmech) während des Zugversuches nach DIN 53455 läßt sich ein Zusammenhang zwischen beanspruchungsbedingten Strukturänderungen und Versagensgrenzen herstellen. Für das dielektrische Relaxationsverhalten der Verbundwerkstoffe, in Verbindung mit den mechanisch induzierten Werkstoffschädigungen, wird eine mikromechanisch begründete Interpretation vorgeschlagen.
Die elektrische Emission beim Versagen von Faserverbundwerkstoffen und ihren Komponenten
Authors: Sklarczyk C. , Winkler S. , Thielicke B.
Published: December 2004

Verformungen und Schädigungen können die Ursache von elektrischen Ladungsverschiebungen in Faserverbundwerkstoffen (FVW) sein, welche zu Änderungen des äußeren elektrischen Feldes führen. Diese können mit geeigneten Sonden berührungslos beobachtet und aufgezeichnet werden. Die Analyse dieser elektrische Emission (EE) genannten Signale kann individuell oder statistisch geschehen, wobei im letzteren Falle Schallemissionsgeräte verwendet werden können. Das Brechen von Carbon ‐oder Glasfasern erzeugt EE‐Signale großer Amplitude, das Brechen des Polykarbonat‐Matrixmaterials dagegen geringere. Das Zerreißen der Verbundwerkstoffe im Zugversuch ist zwar von größeren Signalen begleitet als das des reinen Matrixmaterials; jedoch erreichen diese Signale nicht die Amplituden des Fasermaterials. Die Analyse der Signalformen gestattet Rückschlüsse auf den Ablauf der elementaren Bruchprozesse und deren Dynamik. Diese Arbeit hat gezeigt, daß die elektrische Emission neben anderen Methoden – wie der Schallemission – ein brauchbares Werkzeug zur Beobachtung des Eintritts von Schädigungen in Verbundwerkstoffen ist. Da diese Methode kontaktlos arbeitet und keine Probenvorbereitung erfordert, ist sie nicht nur kostengünstig. Sie kann möglicherweise auch vorteilhaft über Laboratoriumsanwendungen hinaus benutzt werden.
Entwicklungen von verschleiß‐und korrosionsbeständigen Oberflächensystemen. Development of wear and corrosion resistant surface syatems
Authors: Ahn H. , Pfohl C. , Wöhle J. , Gebauer A. , Biemer S. , Bulak A. , Menthe E. , Cabeo E. Rodriguez , Stucky T. , Gebauer A.
Published: December 2004

In dieser Arbeit werden zwei Verfahren zur Realisierung verschleiß‐und korrosionsbeständiger Oberflächensysteme beschrieben: Plasmadiffusionsbehandlung (PDT) und Plasmagestütztes CVD (PACVD). Neben den Plasmanitrierverfahren werden auch Plasmanitrocarburieren und Plasmanborieren von unterschiedlichen Substratwerkstoffen behandelt. Die Fortschirtte beim PACVD und die Entwicklung zu den Niedertemperaturbeschichtungsverfahren werden erläutert und Anwendungen dieser Techniken in der Industrie beispielhaft erwähnt.
Einfaches partielles Aufkohlen für industrielle Anwendungen. Simple Partial Carburizing for Industrial Applications
Authors: Schnatbaum F.
Published: December 2004

Das partielle Aufkohlen von Bauteilen mit Hilfe konventioneller Methoden ist ein relativ aufwendiger und kostenintensiver Prozeß. Als Möglichkeiten stehen derzeit im wesentlichen 2 Methoden zur Verfügung:

das Abdecken der fraglichen Bereiche mit Pasten vor dem Aufkohlen oder

das Fertigen mit Übermaß und anschließendem Abschleifen aufgekohlter Bereiche.

Anhand von Beispielen wird gezeigt, daß das Aufkohlen im Plasma durch einfaches Abdecken von Bauteilbereichen mit Masken oder Blechen erreicht wird und damit eine Möglichkeit gegeben ist, Bauteile einfach und kostengünstig partiell aufzukohlen.
Witterungsbeständige Kunststoffe und Textilien im Automobilbau – Korrelation zwischen Frei‐und Gerätrebewitterung – Teil I
Authors: Lampe Thomas , Schwarzer Peter , Ackermann Matthias , Kaiser Hans‐Georg , Roggenbach W.
Published: December 2004

Kunststoffe und Textilien sind im Automobilbau zum Teil extremen Witterungseinflüssen ausgesetzt. Diese bewirken eine Alterung der Materialien und Bauteile, die z. B. in Form von Rissen, Farbänderungen oder Verformungen sichtbar werden kann.

Im ersten Teil dieses Beitrages werden die für die Alterung von Polymerwerkstoffen wesentlichen Klimagrößen und die hieraus resultierenden Beanspruchungen von Fahrzeugbauteilen beschrieben.

Im zweiten Teil werden Methoden zur Prüfung der Witterungsbeständigkeit vorgestellt, zunächst die Freibewitterung, bei der die Prüfobjekte der natürlichen Witterung ausgesetzt sind, danach einige Kurzzeitprüfmethoden, die auf künstlich in Geräten erzeugten Klimata basieren. Anschließend wird die Korrelation zwischen Frei‐und Gerätebewitterung anhand ausgewählter Beispiele dargestellt.
Schädigungsentwicklung der Legierung IN 738 LC bei Hochtemperatur‐LCF‐Beanspruchung
Authors: Frenz Holger , Klingelhöffer Hellmuth
Published: December 2004

In einer Serie von unterbrochenen Low‐Cycle‐Fatigue Versuchen wurden diese Schädigungsentwicklungen der Legierung IN 738 LC bei 850°C untersucht. Intensive Nachuntersuchungen der Probenoberflächen mittels REM lieferten Aussagen zu der statischen Entwicklung von Rißentstehung und Rißwachstum. Anrisse an oxidierten Korngrenzen entstehen während des gesamten Experimentes. Dem Zusammenwachsen kleiner Risse zu einem Makroriß kommt einer dominierende Rolle bis zum Versagen der Proben zu.
Huntington's disease in venezuela: 7 years of follow‐up on symptomatic and asymptomatic individuals
Authors: Penney John B. , Young Anne B. , Shoulson Ira , Starosta‐Rubenstein Simon , Snodgrass S. Robert , Sanchez‐Ramos Juan , Ramos‐Arroyo Maria , Gomez Fidela , Penchaszadeh Graciela , Alvir Jose , Esteves Jesus , DeQuiroz Iris , Marsol Nelson , Moreno Humberto , Conneally P. Michael , Bonilla Ernesto , Wexler Nancy S.
Published: December 2004

Persons symptomatic and at risk for Huntington's disease (HD) from a large extended family in the state of Zulia, Venezuela, have been followed prospectively for 7 years. Between 1981 and 1988, 593 people were examined, of whom 128 had symptomatic HD and 171 persons at risk had examination abnormalities that were insufficient to meet criteria for diagnosis. The remaining 294 had normal examinations. Abnormalities of saccadic eye movement and slowness of rapid alternating movements were the most common abnormalities found in at‐risk individuals. Thirty persons who did not meet criteria for diagnosis at their first examination have subsequently been diagnosed with symptomatic HD. Their average age at diagnosis was 33.5 ± 8.3 (SD) years. The likelihood of developing symptomatic HD within 3 years was 3% for those persons with normal first examinations, 23% for those with mildly abnormal first examinations, and 60% for those with highly abnormal first examinations. The rate of disease progression in early symptomatic cases were 1.4 ± 0.1 (SEM) points per year on the Shoulson‐Fahn functional capacity scale. Paternal or maternal inheritance did not appear to affect the rate of progression in this group of individuals. The data suggest that there is not a discrete age of onset but rather a prolonged period of time during which symptoms unfold.
Movement disorders in mitochondrial myopathies. A study of nine cases with two autopsy studies
Authors: Truong Daniel Dung , Harding A. E. , Scaravilli F. , Smith S. J. M. , Morgan‐Hughes J. A. , Marsden C. D.
Published: December 2004

Of 85 consecutive patients with mitochondrial myopathy, 29 had clinically significant central nervous system involvement. Nine of these had movement disorders that included dystonia, chorea, parkinsonism, and myoclonus. Autopsy studies of one patient with ataxia, dementia, and parkinsonism followed by dystonia showed the features of olivopontocerebellar atrophy with additional degenerative changes in the basal ganglia. Postmortem in a further case with myoclonus, deafness, muscle weakness, retinopathy, and ataxia showed symmetrical mineralisation of the striatopallidodentatal system.
Primary writing tremor. A form of focal dystonia?
Authors: Elble Rodger J. , Moody Charles , Higgins Constance
Published: December 2004

Five patients exhibited severe tremor in the upper extremity, primarily when attempting to write or draw. Electromyography was performed to determine the patterns of muscle activity that were responsible for this tremor. Tremor was measured with an accelerometer and with a digitizing tablet. Two patients had postural tremor that was indistinguishable from mild, high‐frequency essential tremor. All patients exhibited a severe 5–7‐Hz tremor during the acts of writing and drawing. Muscles throughout the affected extremity exhibited rhythmic 5–7‐Hz bursts of motor unit discharge, and the average level of motor unit activity was tonically increased in antagonistic muscles. This abnormal coactivation of antagonistic muscles produced subtle dystonic posturing of the affected limb that was overshadowed by severe tremor. Electromyography was useful in confirming the coexistence of tremor and dystonia in our patients. The nonspecificity of dystonia and postural tremor must be considered when discussing the nosology and pathophysiology of primary writing tremor.
Psychogenic dyskinesias in patients with organic movement disorders
Authors: Ranawaya Ranjit , Riley David , Lang Anthony
Published: December 2004

The association of psychogenic neurological features with organic neurological disease is commonly acknowledged. However, the occurrence of psychogenic dyskinesias in patients with underlying organic movement disorders is not well recognized. Six cases of psychogenic dyskinesias complicating preexisting organic movement disorders are described. This possibility must be carefully considered and excluded before an unusual movement disorder can be considered entirely psychogenic.
Dentatorubro‐pallidoluysian atrophy of the myoclonus epilepsy type with posterior column degeneration
Authors: Pfeiffer Ronald F. , McComb Rodney D.
Published: December 2004

Dentatorubro‐pallidoluysian atrophy (DRPLA) has a variable clinical presentation but the pathology is routinely confined to cerebellifugal and pallidofugal systems. We present a case of DRPLA of the myoclonus epilepsy type in which prominent posterior column degeneration was added to the pathological picture. This case illustrates the concept that the neurodegenerative diseases can be a continuum of both clinical and pathological presentations.
Gaze‐evoked involuntary movement
Authors: Sethi K. D. , Hess D. C. , Harbour R. C. , Holmes G. L.
Published: December 2004

Voluntary gaze may evoke a number of neurological phenomena such as vertigo, tinnitus, blepharoclonus, eyelid nystagmus, “facial nystagmus,” involuntary laughter, and seizures. We report two patients in whom eccentric gaze evoked facial twitching and arm movement. Electroencephalograms remained unchanged during these movements. The pathogenesis of these movements is unclear but may involve ephaptic transmission.
Diffuse lewy body disease with dementia and oculomotor dysfunction
Authors: Lewis A. J. , Gawel M. J.
Published: December 2004

The case is presented of an elderly patient who had dementia, axial rigidity, and bradykinesia with limitation of horizontal and vertical gaze. Pathological examination disclosed Lewy and Lewy‐like bodies in the substantia nigra, locus ceruleus, and neocortex, leading to a final diagnosis of diffuse Lewy body disease. Similar inclusions were found in areas of the pons and midbrain believed to be associated with gaze control. Moderate numbers of neuritic plaques, but no neurofibrillary tangles, were present in limbic cortex and neocortex. Review of the literature has not shown previous association of diffuse Lewy body disease with both horizontal and vertical gaze anomalies.
Mood changes and “on‐off” phenomena in Parkinson's disease
Authors: Menza Matthew A. , Sage Jacob , Marshall Eric , Cody Ronald , Duvoisin Roger
Published: December 2004

Ten patients with idiopathic Parkinson's disease and motor fluctuations were rated for mood changes during discrete “off,” “on,” and “on with dyskinesia” periods. The Profile of Mood States and visual analogue scales were used. Significant changes in mood and anxiety were found to parallel changes in motor fluctuations. One patient rated his moods as consistently improving from the “off” state to the “on” state and finally to the “on with dyskinesia” state, a finding that is consistent with concomitant central dopaminergic changes. All other patients showed moods that improved significantly from the “off” state to the “on” state but then worsened significantly in the “on with dyskinesia” state, a finding that is consistent with the fact that patients feel worse when impaired by dyskinesias. It is suggested that these results argue for multiple etiologies of depression in Parkinson's disease. The literature on dopamine and depression in Parkinson's disease is briefly reviewed and the opportunity provided by “on‐off” phenomena to study the effect of dopamine on mood changes is discussed.
A pilot study of risk factors for dementia in Parkinson's disease
Authors: Marder Karen , Flood Pamela , Cote Lucien , Mayeux Richard
Published: December 2004

To determine whether the risk factors for dementia in idiopathic Parkinson's disease (IPD) are similar to the risk factors for Alzheimer's disease, we conducted a case‐control study of potential risk factors. A structured interview as was administered to surrogates of 17 demented subjects with IPD and 54 nondemented subjects. Two factors emerged as possible risks for dementia. Demented patients were older than nondemented patients, although the duration of symptoms was similar. A family history of dementia was present in 30% of the demented group and 5.6% of the nondemented group. Dementia was most often reported among siblings. No difference was seen in toxic and occupational exposure, personal habits, or medical or surgical illnesses. We conclude that dementia in IPD shares some common risk factors with Alzheimer's disease. Efforts to assess the contribution of genetic susceptibility or shared environmental influences may clarify the relationship between these two diseases.
Neuroleptic malignant syndrome treated with subcutaneous lisuride infusion
Authors: Rodriguez M. E. , Luquin M. R. , Lera G. , Delgado G. , Salazar J. M. , Obeso José A.
Published: December 2004

A schizophrenic patient developed a characteristic clinical picture of neuroleptic malignant syndrome (NMS) while admitted to the hospital during an exacerbation of his psychiatric symptoms. Oral treatment of the NMS with bromocriptine (7.5 mg/day) or levodopa/carbidopa (125/12.5 mg) provoked intense vomiting in spite of domperidone (60 mg/day), which led to their discontinuation. In view of the deterioration of the symptoms, treatment was begun with lisuride (1–2 mg/24 h) subcutaneously. An obvious improvement was shown in 24 h, but levodopa/carbidopa (125/12.5 mg t.d.s. orally) had to be added later to achieve complete resolution of the NMS. During the recovery phase, while being treated with subcutaneous lisuride infusion and levodopa (p.o.), the patient presented with confusion, agitation, and hallucination. Lisuride infusion was stopped and levodopa was continued until complete resolution of the NMS. This case indicates that parenteral administration of lisuride or other dopamine agents such as levodopa (i.v.) or apomorphine (s.c.) may be considered an effective and practical way of treating NMS, particularly when the patient's condition makes it difficult or impossible to use other dopaminergic drugs by the oral route.
Hypoxic‐ischemic damage of the basal ganglia case reports and a review of the literature
Authors: Hawker Kathleen , Lang Anthony E.
Published: December 2004

Three cases of movement disorders secondary to hypoxic‐ischemic encephalopathy are reported. Despite similarities among the clinical events, the neurological syndromes produced were dissimilar. Cerebral hypoxiaischemia typically produces lesions of the globus pallidus that may result in an akinetic rigid syndrome. Due to its unique blood supply, vascular insufficiency is found to be a major factor. Lesions in the putamen also occur, and these tend to be associated with dystonia. Recent evidence supports a specific neuronal sensitivity in the striatum, possibly due to afferent excitatory amino acid connections. These two components and changes in the levels of neurotransmitters during hypoxia‐ischemia may interact to produce varied clinical outcomes. These factors must also be considered when planning therapeutic interventions.
Clozapine‐responsive tremor in Parkinson's disease
Authors: Friedman J. H. , Lannon M. C.
Published: December 2004

Clozapine is an atypical neuroleptic medication that is free of parkinsonian side effects and that has been reported to ameliorate the tremor of Parkinson's disease. We report (with videotape illustration) the dramatic improvement of severe yet classic rest tremors in one elderly nonpsychotic patient with Parkinson's disease and significant improvement in four others. We believe that clozapine, in low doses, may be a useful medication for the treatment of rest tremor in Parkinson's disease, even in cases without mental abnormalities.
Paroxysmal kinesigenic dystonic choreoathetosis associated with a thalamic infarct
Authors: Camac Ann , Greene Paul , Khandji Alex
Published: December 2004

We describe a patient with the development of paroxysmal kinesigenic dystonic choreoathetosis (PKDC) after a thalamic infarct. PKDC consists of brief episodes of dystonia or choreoathetosis triggered by movement. PKDC improves with anticonvulsants, and in some cases, with L‐Dopa or anticholinergics. We review PKDC, and relate its salient features to idiopathic and secondary torsion dystonia. We postulate a similar underlying pathophysiology.
Clozapine for psychosis in Parkinson's disease
Authors: Pfeiffer Ronald F. , Kang Jasbir , Graber Benjamin , Hofman Ruth , Wilson James
Published: December 2004

The clinical efficacy of clozapine, an atypical antipsychotic, in treating levodopa‐induced hallucinations was investigated in five patients with Parkinson's disease under open label conditions. Two patients could not tolerate clozapine, even in doses as low as 12.5–25 mg daily, because of extreme sedation. Three patients could tolerate clozapine and experienced improvement or elimination of their hallucinations at doses below 100 mg daily. Despite a significant risk of adverse effects, cautious use of clozapine in low doses may be beneficial for patients with levodopa‐induced psychosis who do not respond to more conservative measures.
A case of senile chorea
Authors: Friedman Joseph H. , Ambler Mary
Published: December 2004

Senile chorea, a late‐onset, slowly progressive disorder without mental changes, is a poorly characterized entity. It is often thought to represent late‐onset Huntington's disease in which the chorea precedes the mental changes and the family history is absent due to parental death before symptoms. The following case differs pathologically from Huntington's disease and from previous reports of senile chorea.
Antiparkinsonian activity of a non‐ergot dopamine agonist, CV 205‐502, in patients with fluctuating Parkinson's disease
Authors: Poewe W. , Luef G. , Kleedorfer B. , Emre M.
Published: December 2004

Six patients with fluctuating Parkinson's disease received single rising oral doses of the nonergot dopamine agonist CV 205‐502 in an open experimental study. Doses of 0.5 mg produced antiparkinsonian effects of comparable intensity but longer duration than 200 mg of L‐DOPA. CV 205‐502, which combines structural features common to both ergolines and apomorphine, thus revealed interesting antiparkinsonian properties, but nausea and vomiting were dose‐limiting side effects in all patients tested.
Dopaminergic responsiveness to apomorphine after chronic treatment with subcutaneous lisuride infusion in Parkinson's disease
Authors: Vaamonde J. , Luquin M. R. , Obeso J. A.
Published: December 2004

The aim of this study was to assess whether or not continuous infusion of lisuride in combination with intermittent levodopa‐carbidopa administration was associated with tolerance. Intravenous apomorphine was given to four patients before initiation of chronic treatment with subcutaneous lisuride infusion and oral levodopa. The study was repeated under identical conditions after a mean of 18 months of treatment. In no case was the motor response induced by apomorphine infusion reduced as compared to baseline assessment. Choreic dyskinesias accompanying the “on” state were enhanced in all patients. These findings suggest that chronic continuous infusion of a dopamine agonist like lisuride, associated with oral levodopa, is not accompanied by tolerance or down‐regulation of striatal dopaminergic receptors.
Alcohol‐responsive myoclonic dystonia in a large family: Dominant inheritance and phenotypic variation
Authors: Kyllerman M. , Forsgren L. , Sanner G. , Holmgren G. , Wahlström J. , Drugge U.
Published: December 2004

Alcohol‐responsive myoclonic dystonia is reported in 26 individuals in a six‐generation family, thus indicating autosomal dominant inheritance. Twenty affected family members aged between 3 and 56 years were examined on one occasion. Myoclonus in arms, shoulder, and neck distribution was seen in 17, with occasional generalized jerks in 14. Leg dystonia/hemidystonia was seen in two infant cases, writer's cramp in seven, torticollis/retrocollis in two, and finger tremor in three. The onset of myoclonus was regularly reported from 2 to 3 years of age, the onset of leg dystonia/hemidystonia from 6 to 18 months of age, writer's cramp from early school age, and neck dystonia from late teenage. The effect of alcohol had been noted in 10 individuals, and seven of them abused alcohol. Once established, the neurological signs did not progress significantly. Leg dystonia resolved in two juvenile members. Two adult members had recovered from myoclonus: one elderly man and one posthemorrhagic spastic hemiplegic man. Extensive family investigation is necessary to clarify the clinical variation of this autosomal dominant disorder of involuntary movements.
Neuropathological studies in a mutant hamster model of paroxysmal dystonia
Authors: Wahnschaffe Ulrich , Fredow Gabriele , Heintz Peter , Löscher Wolfgang
Published: December 2004

Dystonic movements in a mutation of the Syrian golden hamster, named dtsz, have several features in common with clinically observed paroxysmal dystonic choreoathetosis. In this study the CNS of the mutant hamsters and age‐matched nondystonic controls was examined for morphological alterations at the age of 30 days, i.e., when the severity of the dystonic syndrome is fully developed. Particular interest was directed to those brain regions (caudate nucleus, putamen, globus pallidus, ventrolateral thalamus) that are presumably involved in symptomatic dystonia of humans, as well as to regions (e.g., spinal cord, dorsal root ganglia, nucleus ruber) for which neuropathologically detectable lesions have been found previously in the dystonia musculorum mouse. The neuropathological investigation was carried out on routine paraffin histology on step sections of the whole brain and spinal cord. In addition, a silver impregnation method was used for detection of pre‐ and/or postsynaptic degeneration. Light microscopic examination, including morphometry, of the nervous tissue failed to reveal any morphological or morphometric differences between control and dystonic hamsters. The only abnormality that was found in several control and dystonic hamsters was hydrocephalus. Breeding studies using magnetic resonance imaging for detection of hydrocephalus showed that hydrocephalus was hereditary but not related to dystonia. Virus infections as a cause of hydrocephalus or dystonia could be excluded by serological analysis with determinations of various virus antibodies in hamster sera. The lack of neuropathological alterations related to dystonic movements in the present study in dtsz hamsters is comparable to most cases of human hereditary or idiopathic dystonia, which show dystonic movements in the absence of morphological alterations.
Sustained‐release (+)‐PHNO [MK‐458 (HPMC)] in the treatment of Parkinson's disease: Evidence for tolerance to a selective D2‐receptor agonist administered as a long‐acting formulation
Authors: Cedarbaum Jesse M. , Clark Mary , Toy Linda H. , Green‐Parsons Alison
Published: December 2004

4‐‐Propyl‐9‐hydroxynaphthoxazine, or MK‐458 (HPMC), a selective, nonergot D2 agonist administered orally twice a day in sustained‐release form, was studied as adjunctive therapy with carbidopa‐levodopa (Sinemet) in 12 Parkinson's disease patients with motor response fluctuations. The dosage of agonist was gradually increased over 12 weeks to a maximum tolerated level of up to 60 mg/day, and that of Sinemet was reduced concurrently. After 8 weeks, reduction of Sinemet averaged 45.1%, but over the next 4 weeks, despite a continued increase in dosage of the agonist, patients were unable to decrease their Sinemet further, and by 12 weeks mean reduction in Sinemet was only 32%. Only five patients completed the planned 24‐week study, mostly due to progressive loss of efficacy. The MK‐458 is capable of partially substituting for Sinemet in dosages employed in this study. Reduced sensitivity to the drug can appear over a relatively short time, perhaps as a result of downregulation of postsynaptic dopamine receptors.
Limb positioning and magnitude of essential tremor and other pathological tremors
Authors: Sanes Jerome N. , Hallett Mark
Published: December 2004

We examined the influence of maintaining different postural configurations of the upper extremity on the magnitude of tremor in patients with essential tremor and with postural tremor from a variety of other neurological disorders. Patients maintained postures requiring different angles of forward flexion in the sagittal plane, of horizontal flexion, and of elbow extension. The tremor of patients diagnosed with essential tremor was either unaffected or affected only little by changes in limb position. In contrast, patients with pathological tremors, of the cerebellar postural, parkinsonian, and other types, exhibited positional dependence of their tremor. When there was positional dependence of tremor, it was always largest when the hands were near the nose or chin. These observations suggest a practical method for assistance with the clinical discrimination of essential tremor from other postural tremors.
Blepharoclonus and parkinsonism associated with aqueductal stenosis
Authors: Gatto Mabel , Micheli Federico , Pardal Manuel Fernandez
Published: December 2004

A 28‐year‐old man with a history of congenital hydrocephalus due to aqueductal stenosis shunted at 45 days of age is presented. At age 4 years the valve had to be removed because of septicemia. Twenty‐three years later he developed parkinsonian signs and abnormal, involuntary rhythmic contractions of the eyelids. The latter were elicited on gentle eye closure. Parkinsonism promptly improved after ventriculoperitoneal shunting, but blepharoclonus persisted unchanged.
Geographic distribution of deaths due to Parkinson's disease in canada: 1979–1986
Authors: Svenson Lawrence W.
Published: December 2004

Mortality figures for Parkinson's disease in Canada from 1979 to 1986 were examined by province and by sex. As seen in other studies, Parkinson's disease showed a statistically significantly higher prevalence in males than in females (p < 0.01). An uneven distribution across provinces was found when mortality rates were compared by males and when males and females were grouped together. Females did not show a significant variation across provinces. Five provinces showed a higher incidence of Parkinson's disease among males than in females (p < 0.05), whereas the other provinces showed no difference. British Columbia and Manitoba showed the highest rates for males as well as the highest rates when males and females were grouped together. The uneven geographic distribution of Parkinson's disease offers support for the possible involvement of environmental factors in the etiology of some forms of idiopathic Parkinson's disease. Suggestions for further research are outlined.
Phenytoin potentiation of neuroleptic‐induced dyskinesias
Authors: Sethi K. D. , Hitri Ana , Diamond Bruce I.
Published: December 2004

Clinically phenytoin‐induced movement disorders may resemble neuroleptic‐induced tardive dyskinesia (TD). Neuroleptic‐induced TD is thought to be related to an increase in the number and affinity of dopamine D2 receptors. We investigated the interaction of phenytoin with dopaminergic systems by measuring dopamine behavior and receptor changes in animals treated with phenytoin alone or in combination with chlorpromazine. Phenytoin alone or in combination produced significant behavioral supersensitivity without alteration of dopamine D2 receptor density or affinity. This animal study suggests that phenytoin may aggravate neuroleptic‐induced tardive dyskinesia through mechanisms other than the dopamine D2 receptors.
Stiff‐person syndrome: An autoimmune disease
Authors: Blum Philip , Jankovic Joseph
Published: December 2004

Stiff‐person syndrome (SPS) is characterized by progressive, usually symmetric rigidity of the axial muscles with superimposed painful spasms precipitated by tactile stimuli, passive stretch, volitional movement of affected or unaffected muscles, startling noises, and emotional stimuli. Electromyography demonstrates continuous normal motor unit potentials in the affected muscles. Both the rigidity and the spasms are relieved by sleep, general anesthesia, myoneural blockade, peripheral nerve blockade, and partially by diazepam. Evidence for an autoimmune etiology of SPS includes its association with other autoimmune diseases and autoantibodies and the presence of antibodies against glutamic acid decarboxylase (GAD) in the cerebrospinal fluid (CSF) of many affected patients. We describe two patients with this syndrome who had GAD antibodies in both CSF and serum. Partial relief of the symptoms in these patients by corticosteroid therapy provides additional evidence of an autoimmune etiology of SPS and of the role of immunotherapy in its treatment.
The hemodynamic effects of triglycyl‐lysine‐vasopressin (glypressin) in patients with parkinsonism and orthostatic hypotension
Authors: Rittig Søren , Arentsen Jens , Sørensen Keld , Matthiesen Thorsten , Dupont Erik
Published: December 2004

The hemodynamic effects of triglycyl‐lysine‐vasopressin (TGLVP) were investigated in a single‐blind study in seven patients with chronic orthostatic hypotension and parkinsonism. Blood pressure, heart rate, and stroke volume were measured in the supine position before and after bolus injection of either placebo or TGLVP (5.0, 7.5, or 10.0 μg/kg of body weight). After 40 min in the supine position, the patients were head‐up tilted to 45° for 20 min. All patients underwent four tilt studies with different medication. The TGLVP increased supine blood pressure by approximately 25% and total peripheral resistance by approximately 46%, and reduced heart rate by approximately 13%. No changes in supine stroke volume or cardiac output were seen. The TGLVP slightly reduced the relative fall in blood pressure and increased heart rate during the tilt. After TGLVP, blood pressure levels during tilt were similar to supine levels prior to medication. The TGLVP did not change the effects of tilt on stroke volume or cardiac output. Only few and mild side effects were experienced and no cardiotoxic effects were observed. In conclusion, TGLVP showed marked blood pressure effects of very small doses in this category of patients. The clinical effects of TGLVP and other vasopressor‐specific analogs of vasopressin should be tested in these patients.
Orthostatic tremor: An association with essential tremor
Authors: FitzGerald Patricia M. , Jankovic Joseph
Published: December 2004

Orthostatic tremor is characterized by tremor of the trunk and legs while standing. Rapid frequency has been emphasized as an important criterion for the diagnosis of this tremor. We observed five patients who had the typical findings of orthostatic tremor but had a wide range of frequencies. All five also had postural hand tremor and a family history of essential tremor, suggesting a relationship between orthostatic tremor and essential tremor. This report also emphasizes the association of orthostatic tremor with painful cramps and a relatively consistent improvement with clonazepam.
Quantitative comparison of barbiturates in essential hand and head tremor
Authors: Sasso Enrico , Perucca Emilio , Fava Roberto , Calzetti Stefano
Published: December 2004

The tremorolytic effects of primidone and phenobarbital in essential tremor of hands and head were compared in a double‐blind, placebo‐controlled trial. Quantitative measurements of tremor were obtained in 15 patients by means of an accelerometric method. Only primidone proved to be superior to placebo in reducing hand tremor, suggesting that its tremorolytic effectiveness is largely dependent on the parent drug rather than its metabolite phenobarbital. Head tremor tended to improve only in three out of six patients with both primidone and phenobarbital, but, likely due to the small number of affected patients, the effect failed to reach statistical significance.
A therapeutic trial of milacemide in myoclonus and the stiff‐person syndrome
Authors: Brown P. , Thompson P. D. , Rothwell J. C. , Day B. L. , Marsden C. D.
Published: December 2004

We investigated the therapeutic effects of milacemide in seven patients with myoclonus and three patients with the stiff‐person syndrome in an open‐label trial. Milacemide was initiated at 800 mg/day and was gradually increased to a maximum dosage of 2,400 mg/day. No significant improvement occurred in the 10 patients.
Carpal tunnel syndrome: A complication of idiopathic torsion dystonia
Authors: Drory V. E. , Neufeld M. Y. , Korczyn A. D.
Published: December 2004

Carpal tunnel syndrome (CTS) is usually an idiopathic disorder. Certain occupations that require frequent flexion movements of the hand at the wrist are recognized as precipitating the development of CTS. Dystonia can cause similar excessive movements at the wrists. We report the clinical and electromyographic findings of two patients with idiopathic torsion dystonia (ITD), with frequent flexion postures of the wrists, in both of whom typical CTS developed in the more involved hand. It is concluded that nerve entrapment such as CTS has to be considered a possible complication in patients with ITD and other motor control disorders.
Review and videotape recognition of idiopathic restless legs syndrome
Authors: Walters Arthur S. , Hening Wayne A. , Chokroverty Sudhansu
Published: December 2004

The motor phenomena associated with idiopathic restless legs syndrome (RLS) are infrequently seen in the physician's office because they are present only after prolonged sitting or lying and usually at night. These motor phenomena are captured on videotape in four unrelated patients with idiopathic RLS. The clinical features of idiopathic RLS are reviewed in detail, and therapeutic advances in its treatment are summarized.
Visuospatial cognition in Huntington's disease
Authors: Mohr Erich , Brouwers Pim , Claus Jules J. , Mann Ulrike M. , Fedio Paul , Chase Thomas N.
Published: December 2004

The notion of specificity of visuospatial dysfunction in Huntington's disease (HD) was evaluated in a sample of afficted patients as a function of symptom duration, age at onset, and overall dementia severity. Factor analytic procedures indicated that overall visuospatial processing capacity (factor 1) as well as the ability for spatial manipulation (factor 3) was markedly affected in HD patients. In contrast, consistency of spatial judgment (factor 2) appeared to remain relatively intact in these patients. Age at onset seemed to have no relationship with any of these variables, whereas dementia severity demonstrated a significant relationship with overall visuospatial processing capacity. Most importantly, duration of symptoms was significantly associated with the declining ability to mentally perform spatial manipulations. The observation of circumscribed visuospatial impairment in HD patients may have important consequences for the further understanding of the neurobehavioral consequences of this disorder.
Gastrointestinal symptoms in Parkinson's disease
Authors: Edwards L. L. , Pfeiffer R. F. , Quigley E. M. M. , Hofman Ruth , Balluff Mary
Published: December 2004

We have investigated the prevalence of gastrointestinal (GI) symptoms in 98 individuals with Parkinson's disease (PD) and in a control group of 50. Seventy‐nine of those with PD were being treated with dopaminergic medications and 19 were untreated. Those symptoms occurring more frequently in PD patients than in controls included abnormal salivation, dysphagia, nausea, constipation, and defecatory dysfunction. Except for defecatory dysfunction, symptoms did not correlate with treatment but instead correlated with disease severity. This suggests that the GI symptoms of PD reflect direct involvement in the GI tract by the primary disease process.
Two sisters with generalized dystonia associated with homocystinuria
Authors: Berardelli A. , Thompson P. D. , Zaccagnini M. , Giardini O. , D'Eufemia P. , Massoud R. , Manfredi M.
Published: December 2004

Two sisters with progressive dystonic syndromes and homocystinuria are presented. The biochemical defect was not accompanied by the typical clinical features of homocystinuria. Magnetic resonance imaging (MRI) revealed bilateral lesions of the basal ganglia. Homocystinuria should be considered among the causes of symptomatic or secondary dystonias associated with basal ganglia lesions.
Dystonia and akinesia due to pallidoputaminal lesions after disulfiram intoxication
Authors: Krauss Joachim K. , Mohadjer Mohsen , Wakhloo Ajay K. , Mundinger Fritz
Published: December 2004

A case with segmental cranial plus crural dystonia of delayed onset and akinesia after acute intoxication with disulfiram is presented. Computed tomography showed bilateral pallidal lesions, whereas on magnetic resonance imaging aditional small lesions of the putamen could be detected. Long‐term observation with progression and a change of symptoms over a period of 10 years after the intoxication is demonstrated on videotape. Although other central side effects after intoxication with disulfiram are well known, movement disorders are uncommon. Carbon disulfide, a disulfiram metabolite, may be important in the etiopathogenesis.
A case‐control study of idiopathic torsion dystonia
Authors: Fletcher N. A. , Harding A. E. , Marsden C. D.
Published: December 2004

A study of 71 patients with idiopathic torsion dystonia (ITD) and 71 matched controls was performed to investigate the range of possible clinical expression of ITD and the role of environmental factors in the development of the disease. A family history of tremor and stuttering were the only factors significantly associated with ITD. No associated environmental factor was identified.
Inhibition of forearm EMG by palatal myoclonus
Authors: Elble Rodger J.
Published: December 2004

The forearm electromyogram (EMG), pharyngeal EMG, and wrist tremor were recorded simultaneously from a 74‐year‐old woman with the syndrome of palatal myoclonus and progressive ataxia. Her wrist tremor had the characteristics of enhanced physiologic tremor. The enhancement of her tremor was attributable to 50‐ to 80‐ms silent periods in the forearm EMG that followed the 1.9‐Hz bursts of palatal myoclonus by 50 to 60 ms. This observation and those of previous authors support the notion that rhythmic olivocerebellar discharges can cause tremorogenic excitation and inhibition of postural EMG activity in the upper extremities.