bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal Cell Death in Hippocampus Induced by Homocysteic Acid in Immature Rats
Authors: Langmeier Miloš , Folbergrová Jaroslava , Haugvicová Renata , Pokorný Jaroslav , Mareš Pavel
Published: March 2003

Summary:  Purpose: To examine the morphologic alterations in the cerebral cortex and hippocampus of immature rats 6 days after the generalized clonic–tonic seizures induced by homocysteic acid (HCA).

Methods: Seizures were induced by bilateral intracerebroventricular infusion of HCA (600 nmol per each side) in 12‐day‐old rats. After 6 days, rat pups were transcardially perfused under deep ether anesthesia with heparinized normal saline and subsequently with the fixation solution (4% paraformaldehyde in phosphate buffer, pH 7.4, for light microscopy) or with Karnovsky's solution (4% paraformaldehyde and 2% glutaraldehyde in phosphate buffer, pH 7.4, for electron microscopic analysis). Nissl stain and the DNA‐specific dye bis‐benzimide (Hoechst 33342) were used.

Results: No pathologic changes were found in the cerebral cortex, whereas serious alterations occurred in the hippocampus. A total loss of CA3 pyramidal cells was observed, with marked changes in the CA1 region and dentate gyrus. A prominent glial reaction was seen in many regions of the hippocampal formation. A slight dilatation of the cerebral ventricles was noticed in some experimental as well as control animals. In the granule cell layer of the dentate gyrus, neurons with segmented or fragmented nuclei in various stages of degeneration were detected, displaying the features of apoptotic death.

Conclusions: These findings demonstrate the vulnerability of the immature rat brain, which most likely reflects both the direct neurotoxic effect of HCA and prolonged seizure activity. The relative contribution of these two factors still remains to be assessed.
Effects of Topiramate in Two Models of Genetically Determined Generalized Epilepsy, the GAERS and the Audiogenic Wistar AS
Authors: Rigoulot Marie‐Aude , Boehrer Any , Nehlig Astrid
Published: March 2003

Summary:  Purpose: The antiepileptic effects of topiramate (TPM) were assessed in two models of genetically determined generalized epilepsy. The model of nonconvulsive epilepsy used was a model of absence seizures, the GAERS (Genetic Absence Epilepsy Rat from Strasbourg); and the model of convulsive seizures was an audiogenic rat model, the Wistar Audiogenic Sensitive (AS) rat.

Methods: GAERS were equipped with four cortical electrodes over the frontoparietal cortex, and the duration of spike‐and‐wave discharges (SWDs) on the EEG was recorded for periods of 20 to 120 or 300 min. In Wistar AS, the occurrence of, latency to, and duration of one or two wild running episodes and tonic seizures were recorded.

Results: In the 16 GAERS studied, TPM (10, 30, and 60 mg/kg) dose‐dependently reduced the expression of SWD that almost totally disappeared at the two highest doses between 40 and 120 min. SWD duration returned to control levels by 180 and 280 min after the injection of 30 and 60 mg/kg TPM, respectively. In Wistar AS, 10 mg/kg TPM induced the occurrence of a second running episode not present in control rats, indicative of a decrease in sensitivity of the rats to the stimulus and increased by 330% the latency to the tonic seizure that still occurred in the eight rats studied. At 30 and 60 mg/kg, the latency to wild running increased by 140%; the second running episode was suppressed in six and seven rats, respectively, whereas the tonic seizure occurred only in one of the eight rats studied at these two doses.

Conclusions: These results support the broad spectrum of antiepileptic activity of TPM, confirming its efficacy in primary generalized seizures of both tonic–clonic and of the absence type.
Epilepsy and EEG in the tElderly
Authors: Van Cott Anne C.
Published: March 2003

Summary: Seizures are now the third most frequently encountered neurologic problem in the elderly population. The incidence of recurrent unprovoked seizures peaks in older patients. Because of this age‐related increase and the growing elderly population, evaluation and treatment of the elderly patient has received increasing attention. This article focuses on epilepsy, not acute seizures in the elderly. The causes and types of epilepsy older individuals experience are reviewed, along with the diagnostic role of EEG. Treatment options are briefly addressed.
The Spectrum of Nonepileptic Events in Children
Authors: Paolicchi Juliann M.
Published: March 2003

Summary:Nonepileptic events (NEE) are common in children, and can be difficult to distinguish from epileptic events. Several strategies can assist in differentiation. The first is an age‐based approach to the differential of commonly presenting EEs in neonates, infants, and adolescents. The next strategy is to identify key elements of the patient's history to narrow the possibilities, and third is a rational approach to ancillary testing. There are additional challenges to the diagnosis and evaluation of NEEs in patients with cognitive impairments or mental retardation (MR). Twenty to 25% of neurologically normal patients(34), and up to 60% of children with MR(35)referred for an evaluation of seizures, have NEE. In most instances, the clinical history leads to the diagnosis, and ancillary testing serves as confirmation. But in certain populations, neonates, children with concurrent epilepsy, children in whom pseudoseizures are suspected, and children with MR, early use of video‐EEG telemetry is indicated to establish the diagnosis and avoid overtreatment with antiepileptic drugs (AEDs).
Changes in Nonlinear Signal Processing in Rat Hippocampus Associated with Loss of Paired‐Pulse Inhibition or Epileptogenesis
Authors: Naylor David
Published: March 2003

Summary:  Purpose: To study acute and chronic physiological effects of perforant path stimulation using paired‐pulse and nonlinear signal analysis techniques (Wiener kernel analysis).

Methods: Two to 3‐month‐old Wistar rats were implanted with stimulating electrodes in the perforant path and recording electrodes in the granule cell layer. Loss of paired‐pulse inhibition was produced with 2 Hz continuous and 20 Hz (10 s/min) intermittent stimulation for periods of 1–15 min (0.1 ms, 20 v pulses). Some animals received 30–60 min of stimulation, a model for status epilepticus/epileptogenesis. Responses to paired‐pulse or white noise inputs were recorded sequentially.

Results: Loss of inhibition with brief 1–3 min of stimulation, measured by increase paired‐pulse ratio (P2/P1 ISI 40 ms) from 0.25 (±0.27) pre‐ to 1.02 (±0.18) post‐stimulation (p < 0.001), lasted 43 (±15) min. For 30–60 min of stimulation, the paired‐pulse ratios were 0.088 (±0.11), 1.59 (±0.036), 0.06 (±0.11), 0.82 (±0.22) for pre‐, immediate post‐, 1 week post‐, and 1 month poststimulation, respectively (p < 0.025). Compared to prestimulation values, Wiener kernel amplitudes for immediate, 1 week, and 1 month poststimulation were 24% (±13%), 72% (±17%), and 31% (±21%), respectively (p < 0.05). Wiener kernels 1 month poststimulation showed response prolongation with increased opportunity for excitatory interactions of inputs (particularly those separated by 4 ms).

Conclusions: Brief perforant path stimulation causes sustained loss of inhibition in the dentate, possibly an early event in the transition to status epilepticus. Stimulation for 30–60 min causes chronic changes in paired‐pulse and white noise (Wiener kernel) responses. Transient recovery occurs by 1 week, but later new features appear (including delayed/late inhibition and potential excitatory cross‐talk) that might favor epileptic seizures.
Genetic Identifiers of Epilepsy
Authors: Kaneko Sunao , Iwasa Hiroto , Okada Motohiro
Published: March 2003

Summary: Epilepsy affects >0.5% of the world's population and has a large genetic component. The most common human genetic epilepsies display a complex pattern of inheritance, and the identity of the susceptibility genes is largely unknown despite recent advances in molecular biology. However, genetic identifiers of certain types of epilepsy with neurodegenerative characteristics and of a small number of familial idiopathic epilepsies have been uncovered to date. This article reviews recent progress made in molecular genetics of epilepsy, focusing mostly on idiopathic epilepsy together with our own discovery of novel mutations in the genes of autosomal dominant nocturnal frontal lobe epilepsy and benign familial neonatal convulsions (BFNCs), and the genetic locus of benign adult familial myoclonic epilepsy. Pathogenesis of epilepsy as a channelopathy and of BFNC also is discussed.
Die Histopathologie der Helicobacter pylori‐Infektion
Authors: Oberhuber G. , Haidenthaler A.
Published: March 2003

Praktisch jede Besiedelung mit Helicobacter pylori (H. p.) führt zu einer immunologischen Reaktion der gastralen Mukosa in Form einer chronisch aktiven Gastritis. Nach der Houston‐Überarbeitung der Sydney‐Klassifikation müssen vom Pathologen die durch H. p.‐induzierten histologischen Veränderungen (Grad und Aktivität der Gastritis, intestinale Metaplasie, Atrophie und Besiedelungsdichte von H. p.) semiquantitativ angeben werden. Die Ausprägung der Gastritis in Antrum und Korpus wird vor allem durch das Ausmaß der Säureproduktion bestimmt. Aus bisher ungeklärter Ursache kann bei einem Teil der Patienten der histologische Typ der Gastritis abweichen und eine lymphozytäre Gastritis, eine atrophische Gastritis und eine Riesenfaltengastritis entstehen. Nach Eradikation bleibt ein chronisch entzündliches Infiltrat in der Lamina propria noch jahrelang zurück.
Schilddrüsensonographie in Praxis und Klinik
Authors: Klima G. , Rothlauer W.
Published: March 2003

Zusammenfassung: Die Ultraschalluntersuchung stellt heute das zentrale Verfahren der morphologischen Abklärung der Schilddrüse dar und ist mit dem Stellenwert des basalen Thyreoidea‐stimulierenden Hormonspiegels (b‐TSH) bei der funktionellen Abklärung vergleichbar. Beide Methoden können schon im Vorfeld morphologische bzw. funktionelle Veränderungen weitestgehend ausschließen. Im Falle einer Erkrankung ermöglicht die Sonographie die Selektion weiterer Untersuchungsverfahren hinsichtlich Notwendigkeit und Dringlichkeit. Die Organgröße (in allen 3 Dimensionen), die Beziehung zu den Nachbarstrukturen, das Echomuster oder die Organdurchblutung sind Ultraschallinformationen, die mit meist unterschiedlicher Gewichtung beim Niedergelassenen, in der Schilddrüsenspezialambulanz oder beim Chirurgen einem Ziel in hervorragender Weise dienen: dem Ausschluss, der Diagnose, der Abklärung und der Therapieplanung von Schilddrüsenerkrankungen.
Die gegenseitige Beeinflussung von Fas‐Aktivierung und Stressproteinantwort entscheidet über Apoptose oder Resistenzentwicklung von Zellen
Authors: Schett G. , Steiner C.‐W. , Winkler S. , Graninger W. , Smolen J. , Xu Q. , Steiner G.
Published: March 2003

Zusammenfassung: Die Expression von Hitzeschockprotein (hsp) 70 und die Aktivierung von Hitzeschockfaktor (HSF)‐1 sind Teil der Resistenzentwicklung von Zellen gegen die Einwirkung äußerer Stressfaktoren und ermöglichen damit das Überleben von Zellen. Fas, ein membrangebundenes Protein, ist ein zentraler proapoptotischer Faktor, dessen Aktivierung über eine Kaskade von Signalen den programmierten Zelltod, auch Apoptose genannt, einleitet. In dieser Arbeit untersuchten wir das Zusammenspiel beider Mechanismen in Bezug auf Überleben und Tod von Zellen. Bei Aktivierung von Fas konnte eine rasche Hemmung der Aktivierung von HSF‐1 und hsp70 nachgewiesen werden. Diese Hemmung der HSF1/­hsp70‐Stressantwort wird durch eine Blockierung der Phosphorylierung von HSF‐1 durch Fas erreicht. Dieser Prozess kann durch Zugabe von ICE (caspase 1)‐Inhibitor verhindert werden, wodurch eine Beteiligung der ICE‐Kaskade bei der Hemmung der HSF1/hsp70‐Stressantwort wahrscheinlich gemacht wird. Die Hemmung der Stressantwort wirkt sich insofern aus, dass die Apoptoserate durch Hitzestress von 20 % auf 50 % bei gehemmter HSF1/hsp70‐Stressantwort ansteigt. Bei Analyse des Effekts von Hitzestress auf Fas konnte gezeigt werden, dass die Fas‐mediierte Apoptoserate durch Überexpression von hsp70, nicht aber durch die alleinige Aktivierung von HSF1 reduziert werden kann. Zusammenfassend schließen wir daraus, dass die gegenseitige Hemmung von Fas‐Apoptose und HSF1/hsp70‐Stressantwort es einer Zelle erleichtert, ohne Einwirkung eines hemmenden Signals entweder den Weg der Apoptose oder aber der Resistenzentwicklung einzuschlagen.
Endokrine Orbitopathie – Augenmuskeloperationen
Authors: Langmann Andrea , Lindner S.
Published: March 2003

Zusammenfassung: Die extraokulären Augenmuskeln sind bei der endokrinen Orbitopathie in typischer Reihenfolge betroffen. Charakteristisch daher auch die Bewegungseinschränkung eines oder beider Augen. Ist das akut entzündliche Stadium abgelaufen, und sind trotz gut eingestellter Schilddrüsenfunktion Bewegungseinschränkungen der Augen geblieben, ist die Therapie der Wahl die Augenmuskelchirurgie, die einerseits der Verbesserung der Beweglichkeit und damit der Erweiterung des Blickfeldes und andererseits der Beseitigung von Doppelbildern dient.
T Lymphocyte Activation – An Inside Overview
Authors: Aringer M.
Published: March 2003

Summary: Activated T lymphocytes play an important role in autoimmune disease. The process of T‐cell activation is therefore of significant importance in understanding the pathogenesis of many rheumatic diseases. This process can be observed from outside the lymphocyte, but we have also gained increased understanding of many of the intracellular events of T‐cell activation. This review tries to draw out the most important receptors, pathways, and transcription factors involved in the process
Raltitrexed und Oxaliplatin beim kolorektalen Karzinom: In‐vitro‐ und In‐vivo‐Untersuchungen einer synergistisch wirksamen Zytostatikakombination
Authors: Schüll Birgit , Scheithauer W.
Published: March 2003

Zusammenfassung: Ziel der vorliegenden Untersuchung war die Prüfung der Wirksamkeit der Kombination von Raltitrexed und Oxaliplatin in vitro unter Verwendung von 4 Kolonkarzinomzellinien und in einem Kollektiv von 36 Patienten mit fortgeschrittenem 5‐FU/Leukovorin ± Irinotecan‐refraktärem Kolonkarzinom.

 Im präklinischen Teil wurde die Wirksamkeit von Oxaliplatin und Raltitrexed sowie von 5‐FU jeweils allein bzw. in Kombination mittels MTT‐Test (Microculture Tetrazolium Assay) an 4 verschiedenen etablierten humanen Kolorektalkarzinom‐Zellinien überprüft. Im klinischen Teil wurden 36 Patienten mit fortgeschrittenem kolorektalen Karzinom eingeschlossen, die während bzw. binnen 6 Monate nach dem Erhalt einer palliativen First‐line‐Chemotherapie mit 5‐FU/LV ± Irinotecan eine Tumorprogression aufwiesen. Es wurden Oxaliplatin 130 mg/m2 und Raltitrexed 3,0 mg/m2 am Tag 1 alle 3 Wochen für insgesamt 8 Zyklen bzw. bis zum Nachweis einer Progression verabreicht. Bei der verwendeten In‐vitro‐Zytostatikakonzentration fand sich für die experimentelle Kombination von Oxaliplatin und Raltitrexed bei 3/4 der Zellinien ein supraadditiver Effekt. Bei der klinischen Studie wurde eine partielle Krankheitsremission bei 12 der 36 Patienten (33 %) festgestellt und weitere 17 Patienten (47,2 %) hatten eine Krankheitsstabilisierung. Bei nur 7 Patienten (19,5 %) kam es zur einer Progression. Das mediane progressionsfreie Überleben betrug beachtliche 6,5 Monate und nach einer mittleren Nachbeobachtungsdauer von 12 Monaten waren noch 23 Patienten (64 %) am Leben. Die Verträglichkeit dieser durchwegs ambulant realisierten Behandlung schien akzeptabel, nur bei 8/36 Patienten (22 %) wurde eine WHO‐Grad 3 oder 4 Neutropenie festgestellt. Grad 3 nicht‐hämatologische Nebenwirkungen umfaßten periphere sensorische Neuropathie (3 Pat.), Asthenie (1 Pat.), Diarrhoe (2 Pat.) und Erhöhung der Leberfunktionsproben.  Die Daten zeigen, daß die Kombination von Oxaliplatin und Raltitrexed nicht nur in vitro, sondern auch in vivo und zwar bei Patienten, die unter einer vorangegangenen Therapie mit 5‐FU/LV ± Irinotecan bei fortgeschrittenem kolorektalen Karzinom progredient waren, gute antitumorale Wirksamkeit besitzt. Aufgrund des akzeptablen Toxizitätsprofils und des einfachen Applikationsschemas sollte der therapeutische Stellenwert dieser Kombination beim metastasierten kolorektalen Karzinom im Rahmen nachfolgender prospektiv‐randomisierter Studien weiter überprüft werden.
Quality of Blood Pressure Control and Risk of Cerebral Bleeding in Patients with Oral Anticoagulation
Authors: Huber J. , Stöllberger Claudia , Finsterer J. , Schneider Barbara , Länger Th.
Published: March 2003

Summary: Background
: We assessed how many patients on long‐term oral anticoagulation (OAC) (i) suffer from arterial hypertension (AH), (ii) are aware of AH, (iii) need improvement of their therapy and (iv) suffer from cerebral bleeding.
Methods
: Outpatients on long‐term OAC were asked to measure blood pressure at least 4 times. Blood pressure was classified as normotensive if at least 75 % of all measurements were < 139/89 mm Hg; as mild/moderate AH if > 25 % of all measurements were 140 – 179 mm Hg systolic or 90 – 109 mm Hg diastolic; and as severe AH if > 25 % of all measurements were > 180 mm Hg systolic or > 110 mm Hg diastolic. Bleeding complications were registered.
Results
: Of the 235 patients (108 female, 67 ± 12 years), 80 % suffered from AH. Severe AH was present in 5 %. Only 56 % were aware of suffering from AH. An improvement of antihypertensive therapy was needed in 64 %. Over 225 days, only one cerebral bleeding occurred. Blood pressure was normotensive in 30 % with known AH.
Conclusions : Blood pressure control seems better in OAC patients than in normals, if the patient is aware of AH. Patients with AH on OAC are not aware of AH in > 50 %. Repeated blood pressure measurements in OAC are recommended, even if patients are not aware of AH.
Introduction of parasitoids has maintained a stable population of arrowhead scales at extremely low levels
Authors: Matsumoto Takashi , Itioka Takao , Nishida Takayoshi , Inoue Tamiji
Published: March 2003

We previously reported the drastic decline of the arrowhead scale,Unaspis yanonensisKuwana (Hemiptera: Diaspididae) following the introduction of two parasitoid species,Aphytis yanonensisDeBach et Rosen andCoccobius fulvusCompere et Annecke (Hymenoptera: Aphelinidae), which were used as biological control agents in a Japanese grove of Satsuma mandarin oranges,Citrus unshiuMarc. (Rutaceae). In this study, we examined whether the parasitoids regulated the scale population at lower levels after its initial decline. Specifically, we monitored the population dynamics of the scale and the rates of parasitism by the two parasitoids three times per year for 16 years following the introduction of the wasps. The two parasitoid species maintained aU. yanonensisdensity at 1/200 of the density prior to their introduction. When we excluded the wasps, the scale population grew at a rate that was more than fivefold that of a control (parasitoid‐infested) group. Although the rates of parasitism byC. fulvusfluctuated, they remained at relatively high levels, whereas those ofA. yanonensiswere 0% over the last 6 years. A repeated‐measures ANOVA indicated that scale density remained stable subsequent to its rapid decline. This showed that the parasitoids stabilized the scale population at a lower level than host plant limitations would have dictated, and strongly suggests thatC. fulvusalone regulates the scale population density at an extremely low level. The latter finding contradicts other studies which have suggested that the two parasitoid species complement each other in regulating scale density. We discuss whether a behavioral refuge used by the scale against parasitoids, which we have demonstrated in an earlier study, might contribute to the observed stable host–parasitoid system at low densities.
The ultimate chip shot: can microarray technology deliver for neuroscience?
Authors: Nisenbaum L. K.
Published: March 2003

The use of cDNA and oligonucleotide microarrays, or ‘chips’, is emerging as a powerful, new technology in the field of neuroscience for examining gene expression in a high‐throughput fashion. The application of microarray technology to the study of brain and behavior has lagged behind other areas of biology such as cancer and yeast genetics due to the challenges presented by the heterogeneous and complex organization of the nervous system. This review provides a brief overview of available microarray technology as well as a description of experimental considerations in planning and implementing a neuroscience‐based array study. Successful implementation of microarray technology within the field of neuroscience will provide a molecular approach to studying systems neurobiology, leading to insights into areas ranging from fundamental questions of developmental neurobiology to neurological and psychiatric disorders.
Trichoteiromanie
Authors: Reich Stefanie , Trüeb Ralph M.
Published: March 2003

Hintergrund: Unter den physikalischen Schädigungen der Haare, die akzidentell, durch kosmetische Maßnahmen oder durch den Patienten selbst verursacht werden, stellt die Trichotillomanie die häufigste selbst induzierte Form dar. Seltener ist die Trichotemnomanie, bei der die Haare vorsätzlich abgeschnitten werden. Für eine weitere Variante des selbstzugefügten Haarverlustes, bei dem es durch Scheuern und Kratzen am Kapillitium zur Pseudoalopezie kommt, schlugen Freyschmidt‐Paul et al. die Bezeichnung Trichoteiromanie vor.

Patienten und Methodik: Vier Patienten mit Trichoteiromanie werden klinisch, morphologisch und psychopathologisch weiter charakterisiert.

Ergebnisse: Im Unterschied zur Trichotillomanie finden sich bei der Trichoteiromanie histopathologisch keine diagnostisch wegweisenden Veränderungen, und das Trichogramm fällt normal aus. Auffällig sind als weißliche Haarspitzen imponierende, ausgefranste Haarenden, die lichtmikroskopisch pinselartigen Haarbrüchen entsprechen. Bei allen Patienten fanden sich unterschiedliche zugrundeliegende Störungen. In allen Fällen bestand aber eine Skalpdysästhesie, die nicht auf eine spezifische dermatologische Kopfhauterkrankung zurückzuführen war.

Schlußfolgerung: Während die Trichotillomanie psychopathologisch als Störung der Impulskontrolle bzw. Zwangsstörung aufgefaßt wird, handelt es sich bei der Trichoteiromanie um eine weniger einheitliche Störung. Die Kooperation mit einem Psychiater ist angezeigt, insofern als die Therapie und Prognose von der zugrundeliegenden psychopathologischen Störung und ihrer spezifischen psychotherapeutischen und pharmakologischen Behandlung abhängen.
Features of fatigue crack growth due to repeated thermal shock
Authors: Kerezsi B. B. , Price J. W. H. , Kotousov A. G.
Published: March 2003

Abstract Thermal shock loading, such as that which occurs when a hot material is sprayed with cold water, produces a very high stress level near the exposed surface that eventually may lead to the development of cracks. Further growth of the cracks under repeated thermal shock is a very complex phenomenon due to the transient nature of the highly non‐linear thermal stresses and the strong influence of the environment. There are cases in industry where cracks created by thermal shocks have arrested and stopped, and others where the cracks have progressed. Understanding this difference in behaviour is very important to the operators of pressure plant. This paper describes an experimental examination of crack growth in pressure vessel steel specimens exposed to repeated thermal shock. A test‐rig that achieves large‐scale thermal shocks through the repeated water quenching of heated flat plate specimens is used. The effect of steady‐state loads on the growth is also analysed. Environmental effects due to the aqueous nature of the testing environment are found to be a major contributor to the crack growth kinetics.
Pre-M Phase-promoting Factor Associates with Annulate Lamellae inXenopusOocytes and Egg Extracts
Authors: Beckhelling Clare , Chang Patrick , Chevalier Sandra , Ford Chris , Houliston Evelyn
Published: March 2003

We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising “annulate lamellae” (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates.
Loss of Protooncogene c-Myc Function Impedes G1 Phase Progression Both before and after the Restriction Point
Authors: Schorl Christoph , Sedivy John M.
Published: March 2003

c-myc is an important protooncogene whose misregulation is believed to causally affect the development of numerous human cancers. c-myc null rat fibroblasts are viable but display a severe (two- to threefold) retardation of proliferation. The rates of RNA and protein synthesis are reduced by approximately the same factor, whereas cell size remains unaffected. We have performed a detailed kinetic cell cycle analysis of c-myc −/− cells by using several labeling and synchronization methods. The majority of cells (>90%) in asynchronous, exponential phase c-myc −/−cultures cycle continuously with uniformly elongated cell cycles. Cell cycle elongation is due to a major lengthening of G1 phase (four- to fivefold) and a more limited lengthening of G2phase (twofold), whereas S phase duration is largely unaffected. Progression from mitosis to the G1 restriction point and the subsequent progression from the restriction point into S phase are both drastically delayed. These results are best explained by a model in which c-Myc directly affects cell growth (accumulation of mass) and cell proliferation (the cell cycle machinery) by independent pathways.
Renewable resources and the gains from trade
Authors: Hannesson Rögnvaldur
Published: March 2003

The Brander‐Taylor small, open‐economy model of trade in a renewable resource and other goods is modified to allow for diminishing returns in the other goods sector. It is shown that opening up for trade may result in steady‐state gains from trade, even when there is open access to the resource and the country does not specialize fully in resource extraction. It is also shown that transition to optimal management, with price‐taking behaviour, may result in a welfare loss.

Resources renouvelables et gains en provenance du commerce international. L'auteur modifie le modèle Brander‐Taylor de commerce international d'une ressource renouvelable et d'autres biens dans le cas d'une petite économie ouverte afin de tenir compte des rendements décroissants dans le secteur des autres biens. On montre que I'ouverture au commerce international peut entraîner des gains en provenance de l'échange international en régime permanent, et ce même quand l'accès à la ressource est ouvert et que le pays ne se spécialise pas dans l'extraction de la ressource. On montre que dans la période de transition vers un management optimal, quand il y a ajustement aux prix de marché, il peut y avoir perte de bien‐être.
Evaluating trade reform with many consumers
Authors: Ju Jiandong , Krishna Kala
Published: March 2003

In this paper we look at the welfare effects of trade reform in the many‐consumers case. We show that Pareto‐improving reforms with lump‐sum taxation or with non‐lump‐sum taxation are possible in the small country case if sufficient conditions for welfare to rise in the single‐consumer case are met. JEL Classification: F0, F1

Evaluation d'une réforme de la politique commerciale quand il y a plusieurs consommateurs. Les auteurs examinent les effets de bien‐être d'une réforme de la politique commerciale quand il y a plusieurs consommateurs. On montre que des réformes améliorant la situation au sens de Pareto sont possibles grâce à des taxes forfaitaires ou non forfaitaires dans le cas de petits pays si on satisfait les conditions nécessaires pour une amélioration du niveau de bien‐être dans le cas d'un seul consommateur.
Monetary aggregates as indicators of economic activity in Canada: empirical evidence
Authors: Siklos Pierre L. , Barton Andrew G.
Published: March 2003

Empirical evidence linking monetary aggregates to variables such as inflation and economic growth has weakened over the past two decades. In this study we re‐examine these relationships by creating composite monetary aggregates that switch among existing monetary aggregates, using quarterly data over the sample 1971–99. Overall, composite monetary aggregates appear to be useful in explaining or forecasting short‐run movements in GDP growth and inflation. Also, the most successful composite monetary aggregates produce switch dates that overlap with the introduction of financial innovations. These subsequently prompted the Bank of Canada to revise or introduce new monetary aggregates. JEL Classification: E51, E52, C52, C53

Les agrégats monétaires en tant qu'indicateurs de l'activitééconomique: résultats empiriques. Les résultats empiriques jaugeant les liens entre les agrégats monétaires et des variables telles que l'inflation et la croissance économique montrent que ces liens se sont affaiblis au cours des deux dernières décennies. Ce mémoire examine ces relations en créant des agrégats monétaires composites qui se déplacent entre les agrégats usuels selon certains critères statistiques. L'étude utilise des données trimestrielles pour la période 1971–99. Dans l'ensemble, les agrégats monétaires composites semblent plus utiles pour expliquer ou prévoir les mouvements à court terme dans le niveau de croissance du PIB et de l'inflation. De plus, les agrégats monétaires composites qui ont le plus de succès suggèrent des moments de déplacement qui correspondent à des discontinuités marquant la mise en place d'innovations financières. Celles‐ci ont entraîné la Banque du Canada à reviser les agrégats monétaires usuels ou à en suggérer de nouveaux.
Union suppression and certification success
Authors: Riddell Chris
Published: March 2003

Over the past decade a number of provinces have abandoned the long‐standing Canadian tradition of automatic certification of unions based on card‐signing and instead opted for mandatory representation voting. This trend, however, has developed with little understanding of the effectiveness of management opposition within a voting regime. In this paper the impact of union suppression on union organizing success within the voting regime of British Columbia is examined. We find that union suppression tactics were highly effective with estimates rivalling those found in the United States. Moreover, results from instrumental variable models suggest that OLS estimates may seriously underestimate the true impact of suppression.

Effort de suppression du syndicat et succès dans le processus de certification. Au cours de la dernière décennie, un certain nombre de provinces canadiennes ont abandonné la pratique traditionnelle de certification automatique des syndicats sur la base des signatures de cartes d'adhésion au syndicat, et ont choisi de réclamer un scrutin pour déterminer le support des membres potentiels. On ne comprend pas bien l'efficacité de l'action d'opposition des patrons au syndicat dans ce régime de scrutin. Ce mémoire examine l'impact des efforts de suppression des syndicats sur les succès des syndicats dans leurs efforts d'organisation dans le cadre du régime de scrutin en Colombie Britannique. On découvre que ces tactiques ont été très efficaces, tout autant qu'aux Etats‐Unis. De plus, les résultats obtenus à l'aide de modèles de variables instrumentales montrent que ceux qu'on obtient à l'aide de la méthode des moindres carrés ordinaires peuvent sous‐évaluer l'impact des tactiques de suppression de manière significative.
What impact does the choice of formula have on international comparisons?
Authors: Armstrong Keir G.
Published: March 2003

In this paper an empirical comparison of a number of alternative multilateral index‐number formulae is undertaken. The magnitude of the effect of choosing one formula over another is ascertained using an appropriate cross‐sectional data set constructed under the auspices of the Eurostat‐OECD Purchasing Power Parity Programme. To this end, a new indicator is proposed that facilitates the measurement of the difference between two sets of bloc consumption shares, each computed using a different multilateral comparison method. JEL Classification: C31, C43, C81, E31, F31, O57

Quel impact est‐ce que le choix des formules a sur les comparaisons internationales? Ce mémoire propose une comparaison empirique d'un certain nombre de formules de nombres‐indices multilatéraux. On tente de jauger la magnitude de l'impact du choix d'une formule plutôt qu'une autre en utilisant une base de données transversales appropriée construite sous l'égide du Programme de parité du pouvoir d'achat Eurostat‐OCDE. On propose un nouvel indicateur qui facilite la mesure de la différence entre deux ensembles de patterns de consommation, chacun calculéà l'aide d'une méthode de comparaison multilatérale différente.
Geographical Spillovers and University Research: A Spatial EconometricPerspective
Authors: Anselin Luc , Varga Attila , Acs Zoltan
Published: March 2003

Using data for U.S. metropolitan statistical areas, an earlier study of aggregate local geographic research spillovers generated by universities (Anselin et al.1997) was extended to a sectorally disaggregated level. These findings suggest the existence of significant sectoral variation with respect to local university effects on innovation. Apparent differences were found across sectors with respect to the “mix” of applied local knowledge inputs in general, and the extent to which university research plays a role in innovation in particular. The main conclusion is that local university spillovers seem to be specific to certain industries, such that at the two‐digit SIC level, no university spillover effects are at work in the Drugs and Chemicals (SIC28) and in the Machinery (SIC35) sectors. On the contrary, very strong and significant university research spillovers are evidenced in the Electronics (SIC36) and the Instruments (SIC38) industries. These spillovers extend beyond the boundary of the MSA within a 75‐mile range from the central city.
Immigration, Migration, and State Redistributive Expenditures
Authors: Hempstead Katherine
Published: March 2003

The effect of immigration on state and local budgets is a frequent topic of both political and academic conversations. A controversial issue among scholars is whether or not immigration induces outmigration of low income native born residents, a population movement which would potentially have implications for the jurisdictional distribution of immigration's fiscal impact. It is hypothesized here that if interstate poverty migration occurred, it should cause fiscal spillovers by distributing some of the public sector burden of immigration from immigrant “host” states to neighboring states. This paper uses cross‐sectional state data from 1988–1995 to explore the relationship between immigration in neighbor states and state redistributive expenditures. The results suggest that there is a positive relationship between immigration to neighboring states and redistributive expenditures. While most discussion of the fiscal impact of immigration has focused on the effects on host states and localities, the implications of these findings are that there are fiscal spillovers to neighboring states, suggesting that fiscal impacts on host states have been over‐estimated and effects on neighboring states have been underestimated. Additionally, the implications of recent welfare reform, which gives states the opportunity to use citizenship as a criterion for program eligibility, are discussed.
Returning and New Montana Migrants: Socio‐economic and Motivational Differences
Authors: Von Reichert Christiane
Published: March 2003

This paper examines return migrants and new migrants to Montana: Who are they? Why do they move? Do return migrants move for different reasons than new migrants? Data from the 1994–1997 Montana Poll, a representative survey of Montana households, are used. A comparison of socio‐economic differences of return and new migrants shows that the two migrant types are very similar in terms of education, income, and age. This stands in contrast to the findings of others who maintain that return migrants are negatively selected with respect to education. Logistic regressions were employed to identify the effect of age and place ties on reasons for moving. Return migrants and new migrants move to Montana for very similar reasons, with family being the most important primary reason for moving. Moving for lifestyle reasons, such as environmental quality and urban amenities, were found to systematically change with age. This could explain why people return to a place they left earlier in life. While other research on return migration compared return migrants and other migrants who left the same place of origin, this paper offers a comparison of return migrants and other migrants who seek out the same destination. Results from the Montana Poll suggest that the same destination attracts return migrants and new migrants with similar socio‐economic characteristics who move there for very similar reasons.
Property Rights and Public Interests: A Wyoming Agricultural Lands Study
Authors: Inman Katherine , Mcleod Donald M.
Published: March 2003

Rocky Mountain states have experienced unprecedented growth as agricultural land is converted to residences. Preservation efforts meet with protest from private landholders claiming public efforts undermine private property rights. This paper explores the degree to which respondents think management of agricultural lands is a public versus a private matter. Data are from a Sublette County, Wyoming, mail survey. Results are relevant to many western counties having public lands and high growth rates. They suggest that landowners, wage earners, college graduates, and those who value the county’s rural community lifestyle support public management strategies. Well‐established residents and those with economic reasons for living in the county support private management strategies.
Default Reasoning and Generics
Authors: Cohen Ariel
Published: March 2003

There are numerous logical formalisms capable of drawing conclusions using default rules. Such systems, however, do not normally determine where the default rules come from; i.e., what it is that makes Birds flya good rule, but Birds drive trucksa bad one.

Generic sentences such as Birds fly are often used informally to describe default rules. I propose to take this characterization seriously, and claim that a default rule is adequate if the corresponding generic sentence is true. Thus, if we know that Tweety is a bird, we may conclude by default that Tweety flies, just in case Birds fly is a true sentence.

In this paper, a quantificational account of the semantics of generic sentences is presented. It is argued that a generic sentence is evaluated not in isolation, but with respect to a set of relevant alternatives. For example, Mammals bear live young is true because among mammals that bear live young, lay eggs, undergo mitosis, or engage in some alternative form of procreation, the majority bear live young. Since male mammals do not procreate in any form, they do not count. Some properties of alternatives are presented, and their interactions with the phenomena of focus and presupposition is investigated.

It is shown how this account of generics can be used to characterize adequate default reasoning systems, and several desirable properties of such systems are proved. The problems of the automatic acquisition of rules from natural language are discussed. Because rules are often explicitly expressed as generics, it is argued that the interpretation of generic sentences plays a crucial role in this endeavor, and it is shown how the theory presented here can facilitate such interpretation.
Updates with Disjunctive Information: From Syntactical and Semantical Perspectives
Authors: Zhang Yan , Foo Norman Y.
Published: March 2003

The possible models approach is a classical minimal change semantics for knowledge base update, which provides an exclusive interpretation for disjunctive information in updates. It has been recognized that the exclusive interpretation for disjunction may be problematic under some circumstances. In this paper, we investigate inclusive interpretations for disjunctions in updates from both syntactical and semantical viewpoints. In particular, we propose two approaches for disjunctive update—the minimal change with exceptions (MCE) and the minimal change with maximal disjunctive inclusions (MCD). Both approaches provide inclusive interpretations for disjunctions in updates, though the first is syntax‐based and the second is model‐theoretic. We then characterize the MCE and MCD in terms of alternative minimal change criteria and relate them to traditional Katsuno and Mendelzon's update postulates.
Semantic Distance Measures
Authors: Cooper Martin C.
Published: March 2003

The measurement of information is potentially as important to an information engineer as the measurement of physical quantities is to a civil or mechanical engineer. This article introduces semantic measures, representing the distance between the meanings of two messages. We demonstrate one possible application by giving a small‐scale example in which a semantic measure was used to retrieve information by meaning rather than by word‐occurrence. The distance function between the meanings of two messages can be generalized to cover fuzzy meanings. A possible application, the processing of free responses to opinion polls, is described.
A Guided Tour through some Extensions of the Event Calculus
Authors: Cervesato Iliano , Franceschet Massimo , Montanari Angelo
Published: March 2003

Kowalski and Sergot's Event Calculus (EC) is a simple temporal formalism that, given a set of event occurrences, derives the maximal validity intervals (MVIs) over which properties initiated or terminated by these events hold. In this paper, we conduct a systematic analysis of EC by which we gain a better understanding of this formalism and determine ways of augmenting its expressive power. The keystone of this endeavor is the definition of an extendible formal specification of its functionalities. This formalization has the effects of casting determination of MVIs as a model checking problem, of setting the ground for studying and comparing the expressiveness and complexity of various extensions of EC, and of establishing a semantic reference against which to verify the soundness and completeness of implementations.

We extend the range of queries accepted by EC, which is limited to Boolean combinations of MVI verification or computation requests, to support arbitrary quantification over events and modal queries. We also admit specifications based on preconditions. We demonstrate the added expressive power by encoding a number of diagnosis problems. Moreover, we provide a systematic comparison of the expressiveness and complexity of the various extended event calculi against each other. Finally, we propose a declarative encoding of these enriched event calculi in the logic programming language λProlog and prove the soundness and completeness of the resulting logic programs.
Applying Machine Learning for High‐Performance Named‐Entity Extraction
Authors: Baluja Shumeet , Mittal Vibhu O. , Sukthankar Rahul
Published: March 2003

This paper describes a machine learning approach to building an efficient and accurate name spotting system. Finding names in free text is an important task in many text‐based applications. Most previous approaches were based on hand‐crafted modules encoding language and genre‐specific knowledge. These approaches had at least two shortcomings: They required large amounts of time and expertise to develop and were not easily portable to new languages and genres. This paper describes an extensible system that automatically combines weak evidence from different, easily available sources: parts‐of‐speech tags, dictionaries, and surface‐level syntactic information such as capitalization and punctuation. Individually, each piece of evidence is insufficient for robust name detection. However, the combination of evidence, through standard machine learning techniques, yields a system that achieves performance equivalent to the best existing hand‐crafted approaches.
Probabilistic Decision Tables in the Variable Precision Rough Set Model
Authors: Ziarko Wojciech
Published: March 2003

The Variable Precision Rough Set Model (VPRS) is an extension of the original rough set model. This extension is directed towards deriving decision table‐based predictive models from data with parametrically adjustable degrees of accuracy. The imprecise nature of such models leads to quite significant modification of the classical notion of decision table. This is accomplished by introducing the idea of approximation region‐based, or probabilistic decision table which is a tabular specification of three, in general uncertain, disjunctive decision rules corresponding to rough approximation regions: positive, boundary and negative regions. The focus of the paper is on the extraction of such decision tables from data, their relationship to conjunctive rules and probabilistic assessment of decision confidence with such rules.
The Influence of EU Membership on Methods and Processes of Budgeting in Britain and France, 1970–1995
Authors: Albert‐Roulhac Catherine
Published: March 2003

This article explores the impact European Union (EU) integration has had on methods and processes of budgeting in France and Britain from 1970 to 1995. It assesses whether convergence of budgetary institutions occurs and, if so, whether it is promoted by an obligation of compliance or by an hybridization effect. Compliance refers to changes in national budgetary institutions made compulsory by membership in the EU. Hybridization emphasizes that national and EU budgetary processes are increasingly interwoven and indivisible. Public budgeting is no longer purely national because part of the decision‐making on national expenditure is made at the EU level and because the national budget is closely linked to the EU budget in financial and policy terms. Based on an institutional analysis, combined with elite interviewing, the article suggests that hybridization is a significant factor contributing to a convergence of budgetary practices in Britain and France. Underlying the argument is the fact that an increasingly important function of departmental actors involves negotiating with their EU counterparts at the EU level, in addition to the conventional budgetary game at the domestic level. Regarding compliance, there is an influence as testified by significant formal institutional convergence. However, compliance seems a less effective factor in influencing convergence than hybridization because it conveys a “negative” approach to convergence, based on enforcement and sanctions. The article suggests that the convergence of administrative systems is promoted by the growing similarity of administrative practices more than by the harmonization of rules.