bluuebunny/crossref_metadata_2025 huggingface dataset:
Intrauterine growth restriction is associated with alterations in placental lipoprotein receptors and maternal lipoprotein composition
Authors: Wadsack Christian , Tabano Silvia , Maier Alexandra , Hiden Ursula , Alvino Gioia , Cozzi Veronica , Hüttinger Manfred , Schneider Wolfgang J. , Lang Uwe , Cetin Irene , Desoye Gernot
Published: September 2006

Among other factors, fetal growth requires maternal supply of cholesterol. Cellular cholesterol uptake is mainly mediated by the LDL receptor (LDL-R) and the scavenger receptor family. We hypothesized that expression levels of key receptors of these families were regulated differently in placentas from IUGR pregnancies with varying degrees of severity. Third-trimester placentas from IUGR pregnancies with (IUGR-S) and without (IUGR-M) fetal hemodynamic changes and from control (AGA) pregnancies were studied. LDL-R, LDL-R-related protein (LRP-1), and scavenger receptor class B type I (SR-BI) mRNA and protein levels were measured. Cholesterol concentration and composition of lipoproteins were analyzed enzymatically and by lipid electrophoresis, respectively, in maternal and umbilical cord blood. LDL-R mRNA levels in IUGR-M were similar to AGA but lower ( P < 0.05) in IUGR-S. In contrast, LDL-R protein was twofold (IUGR-M) and 1.8-fold (IUGR-S) higher ( P < 0.05) than in the AGA group. LRP-1 mRNA and protein levels were not altered in the IUGR cases. SR-BI mRNA was unchanged in IUGR, but protein levels were lower ( P < 0.05) in IUGR-S than in the other groups. Maternal plasma concentrations of LDL cholesterol were higher ( P < 0.05) in the AGA group (188.5 ± 23.6 mg/dl) than in the IUGR-S group (154.2 ± 26.1). Electrophoretic mobility of the LDL fraction in maternal plasma demonstrated significant changes in migration toward higher values (AGA 0.95 ± 0.06, IUGR-M 1.12 ± 0.11, P < 0.001; IUGR-S 1.28 ± 0.20, P = 0.002). We conclude that LDL-R and SR-BI levels are altered in IUGR pregnancies. These differences were associated with changes in LDL, but not HDL, mobility and cholesterol concentration in maternal circulation.
Regulation of renal amino acid transporters during metabolic acidosis
Authors: Moret Caroline , Dave Mital H. , Schulz Nicole , Jiang Jean X. , Verrey Francois , Wagner Carsten A.
Published: September 2006

The kidney plays a major role in acid-base homeostasis by adapting the excretion of acid equivalents to dietary intake and metabolism. Urinary acid excretion is mediated by the secretion of protons and titratable acids, particularly ammonia. NH3 is synthesized in proximal tubule cells from glutamine taken up via specific amino acid transporters. We tested whether kidney amino acid transporters are regulated in mice in which metabolic acidosis was induced with NH4Cl. Blood gas and urine analysis confirmed metabolic acidosis. Real-time RT-PCR was performed to quantify the mRNAs of 16 amino acid transporters. The mRNA of phosphoenolpyruvate carboxykinase (PEPCK) was quantified as positive control for the regulation and that of GAPDH, as internal standard. In acidosis, the mRNA of kidney system N amino acid transporter SNAT3 (SLC38A3/SN1) showed a strong induction similar to that of PEPCK, whereas all other tested mRNAs encoding glutamine or glutamate transporters were unchanged or reduced in abundance. At the protein level, Western blotting and immunohistochemistry demonstrated an increased abundance of SNAT3 and reduced expression of the basolateral cationic amino acid/neutral amino acid exchanger subunit y+-LAT1 (SLC7A7). SNAT3 was localized to the basolateral membrane of the late proximal tubule S3 segment in control animals, whereas its expression was extended to the earlier S2 segment of the proximal tubule during acidosis. Our results suggest that the selective regulation of SNAT3 and y+LAT1 expression may serve a major role in the renal adaptation to acid secretion and thus for systemic acid-base balance.
The 3′-untranslated region of the Ste20-like kinase SLK regulates SLK expression
Authors: Cybulsky Andrey V. , Takano Tomoko , Papillon Joan , Hao Wen , Mancini Arturo , Di Battista John A. , Cybulsky Myron I.
Published: September 2006

Ste20-like kinase, SLK, a germinal center kinase found in kidney epithelial cells, signals to promote apoptosis. Expression of SLK mRNA and protein and kinase activity are increased during kidney development and recovery from ischemic acute renal failure. The 3′-untranslated region (3′-UTR) of SLK mRNA contains multiple adenine and uridine-rich elements, suggesting that 3′-UTR may regulate mRNA stability. This was confirmed in COS cell transient transfection studies, which showed that expression of the SLK open-reading frame plus 3′-UTR mRNA was reduced by 35% relative to the open-reading frame alone. To further characterize the SLK-3′-UTR, this nucleotide sequence was subcloned downstream of enhanced green fluorescent protein (EGFP) cDNA. In COS, 293T, and glomerular epithelial cells, expression of EGFP mRNA and protein was markedly reduced in the presence of the SLK-3′-UTR. After transfection and subsequent addition of actinomycin D, EGFP mRNA remained stable in cells for at least 6 h, whereas EGFP-SLK-3′-UTR mRNA decayed with a half-life of ∼4 h. A region containing five AUUUA motifs within the SLK-3′-UTR destabilized EGFP mRNA. Deletion of this region from the SLK-3′-UTR, in part, restored mRNA stability. By UV cross-linking and SDS-PAGE, the SLK-3′-UTR bound to protein(s) of ∼30 kDa in extracts of COS cells, glomerular epithelial cells, and kidney. Cotransfection of HuR (a RNA binding protein of ∼30 kDa) increased the steady-state mRNA level of EGFP-SLK-3′-UTR but not EGFP. Thus the SLK-3′-UTR may interact with kidney RNA-binding proteins to regulate expression of SLK mRNA during kidney development and after ischemic injury.
Hemispheric Asymmetry in Memory-Guided Pointing During Single-Pulse Transcranial Magnetic Stimulation of Human Parietal Cortex
Authors: Vesia Michael , Monteon Jachin A. , Sergio Lauren E. , Crawford J. D.
Published: September 2006

Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. The present study examines the causal effect of single-pulse transcranial magnetic stimulation (TMS) over the left and right dorsal posterior parietal cortex during a memory-guided “reach-to-touch” movement task in six human subjects. Stimulation of the left parietal hemisphere significantly increased endpoint variability, independent of visual field, with no horizontal bias. In contrast, right parietal stimulation did not increase variability, but instead produced a significantly systematic leftward directional shift in pointing (contralateral to stimulation site) in both visual fields. Furthermore, the same lateralized pattern persisted with left-hand movement, suggesting that these aspects of parietal control of pointing movements are spatially fixed. To test whether the right parietal TMS shift occurs in visual or motor coordinates, we trained subjects to point correctly to optically reversed peripheral targets, viewed through a left–right Dove reversing prism. After prism adaptation, the horizontal pointing direction for a given visual target reversed, but the direction of shift during right parietal TMS did not reverse. Taken together, these data suggest that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. These results also suggest that a brief TMS pulse modifies the output of the right PPC in motor coordinates downstream from the adapted visuomotor reversal, rather than modifying the upstream visual coordinates of the memory representation.
Sleep-Related Spike Bursts in HVC Are Driven by the Nucleus Interface of the Nidopallium
Authors: Hahnloser Richard H. R. , Fee Michale S.
Published: September 2006

The function and the origin of replay of motor activity during sleep are currently unknown. Spontaneous activity patterns in the nucleus robustus of the arcopallium (RA) and in HVC (high vocal center) of the sleeping songbird resemble premotor patterns in these areas observed during singing. We test the hypothesis that the nucleus interface of the nidopallium (NIf) has an important role for initiating and shaping these sleep-related activity patterns. In head-fixed, sleeping zebra finches we find that injections of the GABAA-agonist muscimol into NIf lead to transient abolishment of premotor-like bursting activity in HVC neurons. Using antidromic activation of NIf neurons by electrical stimulation in HVC, we are able to distinguish a class of HVC-projecting NIf neurons from a second class of NIf neurons. Paired extracellular recordings in NIf and HVC show that NIf neurons provide a strong bursting drive to HVC. In contrast to HVC neurons, whose bursting activity waxes and wanes in burst epochs, individual NIf projection neurons are nearly continuously bursting and tend to burst only once on the timescale of song syllables. Two types of HVC projection neurons—premotor and striatal projecting—respond differently to the NIf drive, in agreement with notions of HVC relaying premotor signals to RA and an anticipatory copy thereof to areas of a basal ganglia pathway.
Assessment of Stimulus-Induced Changes in Human V1 Visual Field Maps
Authors: Liu Junjie V. , Ashida Hiroshi , Smith Andrew T. , Wandell Brian A.
Published: September 2006

Visual cortex contains a set of field maps in which nearby scene points are represented in the responses of nearby neurons. We tested a recent hypothesis that the visual field map in primary visual cortex (V1) is dynamic, changing in response to stimulus motion direction. The original experimental report replicates, but further experimental and analytical investigations do not support, the interpretation of the results. The V1 map remains invariant when measured using stimuli moving in different directions. The measurements can be explained by small and systematic response amplitude differences that arise when probing with stimuli moving in different directions.
Beta Oscillatory Activity in the Subthalamic Nucleus and Its Relation to Dopaminergic Response in Parkinson's Disease
Authors: Weinberger Moran , Mahant Neil , Hutchison William D. , Lozano Andres M. , Moro Elena , Hodaie Mojgan , Lang Anthony E. , Dostrovsky Jonathan O.
Published: September 2006

Recent studies suggest that beta (15–30 Hz) oscillatory activity in the subthalamic nucleus (STN) is dramatically increased in Parkinson's disease (PD) and may interfere with movement execution. Dopaminergic medications decrease beta activity and deep brain stimulation (DBS) in the STN may alleviate PD symptoms by disrupting this oscillatory activity. Depth recordings from PD patients have demonstrated beta oscillatory neuronal and local field potential (LFP) activity in STN, although its prevalence and relationship to neuronal activity are unclear. In this study, we recorded both LFP and neuronal spike activity from the STN in 14 PD patients during functional neurosurgery. Of 200 single- and multiunit recordings 56 showed significant oscillatory activity at about 26 Hz and 89% of these were coherent with the simultaneously recorded LFP. The incidence of neuronal beta oscillatory activity was significantly higher in the dorsal STN ( P = 0.01) and corresponds to the significantly increased LFP beta power recorded in the same region. Of particular interest was a significant positive correlation between the incidence of oscillatory neurons and the patient's benefit from dopaminergic medications, but not with baseline motor deficits off medication. These findings suggest that the degree of neuronal beta oscillatory activity is related to the magnitude of the response of the basal ganglia to dopaminergic agents rather than directly to the motor symptoms of PD. The study also suggests that LFP beta oscillatory activity is generated largely within the dorsal portion of the STN and can produce synchronous oscillatory activity of the local neuronal population.
Novel algorithm for transcriptome analysis
Authors: Saama Peter M. , Patel Osman V. , Bettegowda Anilkumar , Ireland James J. , Smith George W.
Published: September 2006

A growing body of evidence implicates the oocyte as a key regulator of ovarian folliculogenesis and early embryonic development. We have screened bovine cDNA microarrays (containing expressed sequence tags representing >15,000 unique genes) with Cy3- and Cy5-labeled cDNA derived from bovine oocyte samples collected at two different stages of meiotic maturation (germinal vesicle vs. metaphase II; n = 3 samples per group). Here, we present a novel data analysis approach that uses all available information from above experiments to obtain and index the transcriptome of bovine oocytes and changes in transcriptome composition in response to meiotic maturation. Signal intensities (Fg) for all housekeeping genes were omitted prior to analysis. A local threshold for gene expression was computed as background intensity (Bg) plus 2 times the standard deviation of background and foreground signals. Within each array, data were normalized by the LOWESS procedure. Subsequently, a two-stage mixed model was fitted to remove systematic variations. In the first stage, the response was the LOWESS normalized Fg with treatment as a fixed effect. In stage 2, the residuals from stage 1 were analyzed in a gene-specific model that included treatment group and spots nested within patch and array. A test for the difference between least squares means for the treatment effect was performed. A false discovery rate (FDR) adjustment on the p values for the difference was carried out. This novel algorithm was compared with approaches that ignore the FDR and the threshold described herein and stark differences obtained.
Understanding the Information Needs of General Practitioners Managing a Rare Genetic Disorder (Osteogenesis Imperfecta)
Authors: Zack Philip , DeVile Catherine , Clark Christine , Surtees Robert
Published: September 2006

Background: Lack of adequate knowledge is a common problem in medicine, but is a particular problem in a rapidly advancing field like genetics. This study uses the example of a rare genetic disorder (osteogenesis imperfecta) to understand the information needs of primary care physicians (GPs). Objectives: To determine whether a knowledge gap is recognised, how GPs currently attempt to overcome it, and what features of an information resource are preferred by GPs. Methods: GPs of children affected by osteogenesis imperfecta in and around Greater London were interviewed, using both questionnaire-based semi-structured interview and a qualitatively analysed open-ended discussion. Consultations in both primary and tertiary care settings over a 5-year period were compared. Results: Problems due to osteogenesis imperfecta were presented to GPs in about one third of consultations with these patients. GPs reported finding such patients difficult to manage due to lack of knowledge. Knowledge from tertiary sources, which was authoritative, accessible and relevant, was preferred, particularly when reasoning was explained. Primary literature and clinical guidelines were not favoured. Conclusions: Empirical evidence supports and elaborates theoretical models for provision of clinically useful information. A model for improved information services using authoritative web-based information linked to electronic patient records is suggested.
El sistema muscular es el impulsor del desarrollo esquelético
Authors: Schoenau Eckhard
Published: September 2006

En esta revisión se abordan los conceptos metodológicos de evaluación de la función de la musculatura esquelética y adaptación ósea. Actualmente se considera que la propiedad crítica del hueso no es tanto su peso como su resistencia, y que el control de la resistencia ósea se ejerce principalmente a través del efecto de las cargas mecánicas que inciden sobre el hueso. La contracción muscular representa la carga fisiológica más importante sobre el hueso y, en consecuencia, la estabilidad del hueso debe adaptarse a la fuerza muscular (la unidad funcional músculo-hueso). Las sugerencias y recomendaciones descritas esbozan un concepto nuevo: la masa y la resistencia ósea no estarían relacionadas con la edad. Se dispone cada vez de más pruebas de que la masa y la resistencia óseas estarían relacionadas con la función muscular. Del análisis se infiere que no existiría una entidad denominada ‘masa ósea máxima’. Se están realizando actualmente numerosos estudios para evaluar si estos nuevos enfoques incrementan la sensibilidad y la especificidad del pronóstico de fracturas en un individuo. Además, el enfoque de muchos investigadores en la biología ósea se está desplazando desde la masa ósea hasta la geometría ósea o la resistencia ósea y su relación con el impulso del sistema muscular.
Nutrición deportiva en la infancia: Cumplimiento de las demandas metabólicas del crecimiento y el ejercicio
Authors: Zanker C.L.
Published: September 2006

Los objetivos fundamentales de la infancia son el crecimiento y la maduración óptimos. Estos procesos relacionados con el desarrollo exigen un balance energético y nitrogenado positivo. Aunque la actividad física regular puede intensificar el desarrollo en la infancia, un entrenamiento físico extenuante puede reducir las reservas de energía y nitrógeno del organismo que, entonces, deberán reemplazarse a través de la alimentación. Los adolescentes físicamente activos son propensos a trastornos del comer, que pueden dar lugar a una malnutrición proteico-energética. Entre las consecuencias de un balance energético y nitrogenado negativos, destacan el retraso o la detención del crecimiento y la maduración puberal retardada. Actualmente las pruebas disponibles son insuficientes para asegurar que el entrenamiento físico ejerce un impacto negativo directo sobre el crecimiento y la maduración. Una alimentación bien equilibrada es esencial para el mantenimiento del rendimiento físico y la conservación del estado de salud en todos los individuos físicamente activos, independientemente de su edad. Los alimentos proporcionan los elementos químicos necesarios para la producción de energía por medio de la ejercitación de la musculatura esquelética, la reposición después del ejercicio de las reservas de energía y la regeneración del músculo dañado. Las necesidades alimentarias de los niños físicamente activos varían a medida que aumenta el tamaño corporal y progresa la pubertad. El estado de maduración es un determinante importante de las respuestas metabólicas y fisiológicas al ejercicio y, en consecuencia, influyen tanto sobre la capacidad del rendimiento físico como sobre las necesidades alimentarias. Estudios de metabolismo energético en niños dan a entender que, si bien están bien dotados para una actividad aerobia persistente, su capacidad para la actividad anaerobia está limitada debido a su estado de maduración. Es importante destacar que restricciones éticas impiden el tipo de investigación detallada e invasora que ha sido empleada para determinar las necesidades nutricionales en adultos físicamente activos. No obstante, parecería que, lo mismo que estos adultos, los niños físicamente activos presentan mayores demandas alimentarias con respecto a energía, hidratos de carbono, proteínas y agua que sus contrapartes sedentarias. En este artículo se justifican las necesidades nutricionales de niños atletas basándose en las demandas fisiológicas y metabólicas de supervivencia, crecimiento y actividad física.
Consecuencias de la restricción de peso impuesta por el deporte en la infancia
Authors: Boisseau Nathalie
Published: September 2006

Actualmente, los competidores jóvenes emprenden programas de entrenamiento que se basan en un nivel elevado de actividad física desde una temprana edad. Este entrenamiento intensivo (volumen e intensidad) aumenta el gasto de energía, que tiene que ser compensado por una mayor ingesta nutricional. Los bailarines de ballet, los patinadores artísticos, los gimnastas o los gimnastas rítmicos comienzan a entrenar a los 5 o 6 años de edad, y la mayoría practica durante más de 20 a 30 horas por semana. En estas actividades, así como en los deportes clasificados por peso (luchadores, jinetes y atletas practicantes de judo o boxeo), los jóvenes atletas de elite adoptan decisiones conscientes para reducir su ingesta alimentaria con objeto de mantener la esbeltez, el físico prepuberal o para ‘dar el peso’. El consumo adecuado de energía y micronutrientes es esencial para los niños en fase de crecimiento, y las restricciones calóricas y de líquidos durante el entrenamiento físico en la infancia o durante la adolescencia podrían perturbar las regulaciones metabólicas y hormonales que influyen sobre el crecimiento, la maduración, la composición corporal, el ciclo menstrual y la capacidad reproductora, lo que puede incrementar el riesgo de traumatismos como fracturas por sobrecarga. Además, estas estrategias pueden generar trastornos del comer (anorexia y/o bulimia nerviosa), especialmente durante la adolescencia femenina, afectando a la imagen corporal, a la imagen de uno mismo y ocasionando inadaptaciones sociales y emocionales.
Pubertad y deportes atléticos en adolescentes femeninas
Authors: Klentrou Panagiota (Nota)
Published: September 2006

La creciente participación de niños pequeños en el entrenamiento físico intensivo, durante las últimas décadas, ha generado temores con respecto a sus efectos potenciales sobre el crecimiento y la maduración de los niños. La pubertad en el humano se caracteriza por cambios hormonales considerables, que resultan tanto en maduración física como en maduración sexual. Dado que un entrenamiento intensivo antes de la pubertad, junto a los efectos metabólicos potenciales del seguimiento de una dieta, puede alterar la función hipotalámica e hipofisaria, el momento en que se inicia el entrenamiento atlético ha sido implicado como un factor en el retraso de la menarquia y la maduración sexual en atletas femeninas. Por otra parte, en algunos estudios se ha dejado entrever la probabilidad de que el retraso de la menarquia puede deberse a factores genéticos. Las niñas que maduran más tardíamente, a menudo se autoseleccionan o son reclutadas por preparadores para deportes que favorecen cuerpos de tamaños reducidos o muy delgados. También se ha utilizado la composición corporal para explicar el retraso de la menarquia y las irregularidades menstruales que se observan en atletas de elite. Se ha descrito una mayor prevalencia de disfunción menstrual en atletas adolescentes que participan en deportes dependientes del peso, en comparación con lo que se observa en otros deportes. No obstante, tal como se ha dejado entrever recientemente, no existe una relación directa entre causa y efecto entre la obesidad y la reproducción y, en realidad, la función reproductora en las mujeres está regulada por la disponibilidad energética y no por la grasa corporal. Está justificado intensificar la investigación para indagar adicionalmente esta interacción entre los cambios a corto plazo en la disponibilidad de los combustibles y la amenorrea atlética en adolescentes femeninas. Se llega a la conclusión de que, teniendo en cuenta los numerosos factores que, según se ha comprobado, influyen sobre la menarquia y la menstruación, el papel desempeñado por el mero entrenamiento físico como factor causal del inicio más tardío de la pubertad y de las irregularidades menstruales en niñas físicamente activas sigue siendo dudoso. Es imprescindible una investigación basada en estudios diseñados longitudinalmente para identificar si las diferencias en la maduración, observadas entre atletas femeninas y niñas que no practican actividades atléticas, son el resultado de la naturaleza o la nutrición, y cuál es el equilibrio entre ambos factores.
Itraconazole Comedication Increases Systemic Levels of Inhaled Fluticasone in Lung Transplant Recipients
Authors: Naef Rahel , Schmid Christoph , Hofer Markus , Minder Stefan , Speich Rudolf , Boehler Annette
Published: September 2006

Background: After lung transplantation (LTx), inhaled corticosteroids may be prescribed and at the same time prophylaxis against fungal infections with itraconazole is common. In our center, the addition of inhaled fluticasone propionate to systemic immunosuppression resulted in clinical Cushing’s syndrome in 4 lung transplant recipients on itraconazole comedication. Objectives: The current study was undertaken to compare systemic levels of inhaled fluticasone in patients with and without concomitant itraconazole therapy. Methods: The single-center, prospective controlled study was performed in the LTx program in Zurich, Switzerland. Twenty stable recipients, 1–7 years after LTx, on a prednisone maintenance dose (5–7.5 mg/day) gave informed consent and were assigned to 2 groups: (A) without itraconazole comedication and (B) currently on itraconazole, being continued during the study period. The patients of both groups started inhalation of 1 mg fluticasone propionate twice daily for 14 days with a powder disc inhaler. Plasma fluticasone levels were measured before the start of the study and on day 14. Results: Fluticasone levels before starting the treatment were below the detection limit in all 17 patients (7 in group A and 10 in group B) adhering to the study protocol. Baseline characteristics (underlying disease, age at LTx, time since LTx, FEV1) were comparable between the 2 groups. On study day 14, plasma fluticasone levels had increased to detectable levels in all patients (A: 273 ± 124 pg/ml, B: 701 ± 131 pg/ml), i.e. to significantly higher (p = 0.038) concentrations in patients on itraconazole. Conclusions: Itraconazole comedication substantially increases systemic levels of inhaled fluticasone, most likely by inhibiting the cytochrome P450 3A4 enzyme system and thus the clearance of fluticasone. Accumulation of fluticasone can result in increased systemic effects and therefore comedication has to be taken into consideration when inhaled fluticasone is prescribed.
A Simple Method for Rapid Separation of Endothelial and Smooth Muscle mRNA Reveals Na+/K+-ATPase Alpha-Subunit Distribution in Rat Arteries
Authors: Krenek Peter , Hamaide Marie-Christine , Morel Nicole , Wibo Maurice
Published: September 2006

Background/Aims: The endothelium has been recognized as a key component in the regulation of blood vessels. We designed a simple procedure to separate endothelial and smooth muscle RNA from rat aorta and mesenteric artery and used this method to establish the distribution of Na+/K+-ATPase α-subunit isoforms (NaKα1, NaKα2 and NaKα3) within the arterial wall. Methods: Rat aorta was perfused with Tripure, a reagent for RNA isolation, yielding 3 successive RNA fractions (E1–E3) and the remaining tissular RNA (Ao[E–]). A similar procedure was applied to the mesenteric artery. Gene expression was studied by semiquantitative reverse-transcription polymerase chain reaction. Results: Compared to unperfused aorta (Ao[E+]), typical endothelial mRNAs were enriched 3- to 5-fold in E1–E3 but almost absent in Ao[E–], whereas smooth muscle mRNAs were low in E1–E3 but similarly expressed in Ao[E–] and Ao[E+]. NaKα1 was uniformly expressed in all fractions, NaKα2 closely followed the expression pattern of smooth muscle markers and NaKα3 expression was weak and attributable to blood contamination. Comparable results were obtained with the mesenteric artery. Conclusion: We conclude that, in aorta and mesenteric artery, Tripure perfusion allows for a rapid and reliable separation of endothelial mRNA from smooth muscle mRNA, and that endothelium only expresses NaKα1, whereas smooth muscle expresses NaKα1 and NaKα2, but not NaKα3.
Responses of the Rat Medullary Neurons to Central Penicillin Microinjection
Authors: Lebedeva M.A.
Published: September 2006

Background: The microinjection of penicillin in the medulla oblongata caused different alterations in the global respiratory output. The purpose of this paper was to study the involvement of impulse activity and the functional relationship of bulbar neurons in mechanisms underlying experimentally induced respiratory arrhythmias. Methods: Extracellular activity of neurons and diaphragmatic electromyogram activity were recorded and analyzed. Results: Penicillin microinjection increased the mean discharge rate of bulbar neurons and caused the prolongation of discharge of inspiratory neurons. Cross-correlation analysis revealed new excitatory connections between neurons and a high level of positive synchronization of neuronal activity. Conclusion: The local blockage of synaptic inhibition by penicillin within respiratory areas leads to drastic changes in the functioning of neuronal elements of the single respiratory network.
Critical Examination of the Use of Coherent Gradient Sensing in Measuring Fracture Parameters in Functionally Graded Materials
Authors: Rousseau Carl-Ernst
Published: September 2006

Specific relations for out-of-plane deformation near crack tips of linearly graded materials are introduced and used with the optical method of coherent gradient sensing (CGS) to interpret experimentally obtained fringes. Stress intensity factors are thus derived and used to reconstruct synthetic fringes that are then compared to experimental ones. An error function is used with sets of 2-6 terms in the asymptotic solution to gage the incremental accuracy contributed by using these additional terms with the experimental results. The study reveals the necessity of using up to the sixth higher-order term to obtain a precise agreement between the analytical solution and the experimental interferograms. Specimen configurations with cracks consecutively positioned at the stiffer, and then at the more compliant end of the gradient are used. Distinct features of the interferograms indicate the benefits of having the crack on the compliant side of the elastic modulus variation.
From Union Inspired to Industry Led: How Australian Labour's Training Reform Experiment Turned Sour
Authors: Brown Tony
Published: September 2006

Australian labour set out on a grand attempt to restructure vocational education and training in the 1980s and 1990s. The reforms were intended to go beyond the scope of previous worker education by aiming at complete systemic change by linking skill development to wages through the award system. This article locates labour's training reform in the wider program of economic modernization. It argues that unions provided the inspiration for the new system but by the early 1990s had lost the initiative as enterprise bargaining was introduced and as employer associations and state education bureaucracies re-asserted control and established a new training market. That training reform's original expectations were not delivered demands closer attention and analysis. Learning the lessons of this experiment is an essential step for labour in developing a positive agenda for workers' education in the future.
Employers' Choices in Workplace Regulation: Individual Agreements
Authors: Todd Patricia , Caspersz Donella , Sutherland Michael
Published: September 2006

In Western Australia (WA) the state IR regulatory framework has been changed substantially in recent times, firstly, by the former Coalition Government facilitating individualism and subsequently by the Labor Government attempting to reverse this trend by reinstating a greater emphasis on collective bargaining. The WA Coalition Government introduced the option for employers to negotiate and register individual agreements based on a very limited set of minimum employment standards, as a critical part of their change package. Subsequently these were abolished by the Gallop Labor Government and replaced by the less flexible Employer Employee Agreements based on awards, as part of a package of changes to encourage employers to return to collective bargaining. This article considers the response of employers in WA to these changes, focusing in particular on those who chose to utilize the individual agreements option during the 1990s and how they later responded to the Labor Government's regime favouring collective agreements.
Performance Pay and Job Satisfaction
Authors: Heywood John S. , Wei Xiangdong
Published: September 2006

This article estimates the direct effect of performance pay schemes on job satisfaction for a representative sample of US workers. Both individual performance pay and profit sharing are routinely associated with higher satisfaction even as the level of pay and a long list of other determinants are held constant. This result holds in panel estimates designed to control for fixed effects. When individual performance pay is disaggregated into five specific schemes, all but one associate with higher satisfaction and piece rates associate with lower satisfaction. The role of gender is explored as an explanation for the results.
Appearance-Based Topological Bayesian Inference for Loop-Closing Detection in a Cross-Country Environment
Authors: Chen Cheng , Wang Han
Published: September 2006

In this paper, an appearance-based environment modeling technique is presented. Based on this approach, the probabilistic Bayesian inference can work together with a symbolic topological map to relocalize a mobile robot. One prominent advantage offered by this algorithm is that it can be applied to a cross-country environment where no features or landmarks are available. Further more, the loop-closing can be detected independently of estimated map and vehicle location. High dimensional laser measurements are projected into a low dimensional space (mapspace) which describes the appearance of the environment. Since laser scans from the same region share a similar appearance, after the projection, they are expected to form a distinct cluster in the low dimensional space. This small cluster essentially encodes appearance information of the specific region in the environment, and it can be approximated by a Gaussian distribution. This Gaussian model can serve as the “joint” between the topological map structure and the probabilistic Bayesian inference. By employing such “joints”, the Bayesian inference in the metric level can be conveniently implemented on a topological level. Based on appearance, the proposed inference process is thus completely independent of local metric features. Extensive experiments were conducted using a tracked vehicle traveling in an open jungle environment. Results from live runs verified the feasibility of using the proposed methods to detect loop-closing. The performances are also given and thoroughly analyzed.
Force Analysis of Connected Differential Mechanisms: Application to Grasping
Authors: Birglen Lionel , Gosselin Clément M.
Published: September 2006

In this paper, a methodology is proposed for the analysis of the force capabilities of connected differential mechanisms. These systems are the key elements used to extend the principle of underactuation in grasping from the fingers to the hand itself. The concept of under-actuation in robotic grasping—with fewer actuators than degrees of freedom (DOF)—allows the hand to adjust itself to an irregularly shaped object without complex control strategies and sensors. Several technological solutions have been proposed in the past but no theoretical background has been provided to analyze their characteristics, especially with respect to the forces generated. The purpose of this paper is to provide such a theoretical foundation and to illustrate its usefulness with examples applied to grasping. First, several differential elements are presented and studied. Second, a mathematical method to obtain the output force capabilities of connected differential mechanisms is presented. Finally, the technique presented is applied to two types of underactuated robotic hands.
Rubbed Thin Films of Well-defined Brush Polyimides for Flat-Panel Liquid Crystal Displays: Surface Morphology, Molecular Orientation, and Liquid Crystal Alignability
Authors: Hahm Suk Gyu , Lee Seung Woo , Suh Jinsuk , Chae Boknam , Kim Seung Bin , Lee Seong Joon , Lee Kyung Hoon , Jung Jin Chul , Ree Moonhor
Published: September 2006

A series of well-defined brush polyimide (PI) composed of two 4- n-alkyloxyphenyloxy bristles per repeat unit on a semi-rigid poly(4,4′-methylenyldiphenylene pyromellitimide), Cm-PMDA-MDA PIs, were synthesized and their nanoscale thin films prepared by conventional spin-coating of their soluble poly(amic acid) precursor solutions and subsequent drying and thermal imidization in a nitrogen atmosphere. All the PIs were determined to be a positively birefringent polymer. The surface morphology and molecular orientation of each PI in films before and after rubbing were investigated in detail by atomic force microscopy, optical retardation analysis, and linearly polarized infrared spectroscopy. The sequence of the rubbing-induced polymer segmental orientations was further investigated in detail. In addition, the liquid crystal alignment and pretilt ability of the rubbed PI films were examined, and their thermal stability investigated. The present study provides important information on the sequence of the polymer segmental orientations induced by rubbing and additionally the mechanisms of the alignment and pretilt of liquid crystal molecules in contact with the rubbed PI film surface.
Synthesis and Characterization of Novel Aromatic Polyimides from Bis(4-amino-2-biphenyl) ether and Aromatic Tetracarboxylic Dianhydrides
Authors: Morikawa Atsushi , Furukawa Takaaki , Moriyama Yukari
Published: September 2006

Aromatic polyimides having phenyl groups at the 2- and 2′-positions of the diphenyl ether moiety were synthesized from bis(4-amino-2-biphenyl) ether and various tetracarboxylic dianhydrides by the conventional two-step procedure using N-methyl-2-pyrrolidone (NMP) as a solvent [Morikawa et al., Polymer Journal37, 759, 2005]. The phenyl groups at the 2,2′-position of the phenyl ether improved the solubility of polyimides without decreasing the thermal and thermo-mechanical properties. In this paper, soluble polyimides were synthesized in a one-step procedure by reacting this diamine with various tetracarboxylic dianhydrides in m-cresol at 190°C, and the properties, especially the thermal properties, thermo-mechanical properties and solubility were compared with those of the polyimides synthesized by the two-step procedure.
Effect of Photo-active Compound Structure on Photosensitivity of Positive Photosensitive Polyimide
Authors: Tomikawa Masao , Yuba Tomoyuki , Ohbayashi Gentaro , Kim Jae Hyun , Kim Youngho , Kim Taesung
Published: September 2006

The photo-active compound (PAC) in positive tone photosensitive polyimide (posi PSPI) was investigated in order to obtain good photo lithographic performance (small development loss and good photosensitivity). When the PAC structure was changed posi PSPI showed different levels of photosensitivity and development loss. The development loss and photosensitivity showed a good correlation. The lower development loss posi PSPI showed lower photosensitivity. From the molecular orbital calculation, the PAC in the lower development loss posi PSPI had a lower dipole moment than that in the larger development loss posi PSPI. In addition, dissolution rate measurement (DRM) results suggest that posi PSPI may have two layers from the point of dissolution. The dissolution rate of the surface layer in posi PSPI was shown to be lower than that of a bottom layer. This suggests that PAC using the lower development loss posi PSPI may exist mainly on its surface. These results are quite important for the design of good posi PSPI.
Structure-property Relationship of Polyimides Derived from Sulfonated Diamine Isomers
Authors: Yin Yan , Chen Shouwen , Guo Xiaoxia , Fang Jianhua , Tanaka Kazuhiro , Kita Hidetoshi , Okamoto Ken-Ichi
Published: September 2006

Four novel sulfonated diamine monomers which are isomers to each other, 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid ( pBAPBDS), 4,4′-bis(3-aminophenoxy)biphenyl-3,3′-disulfonic acid ( mBAPBDS), 2,2′-bis(4-aminophenoxy)biphenyl-5,5″-disulfonic acid ( oBAPBDS), and 4,4--bis(4-amino-2-sulfophenoxy)biphenyl ( iBAPBDS), were synthesized and the related sulfonated polyimides (SPIs) were prepared from these sulfonated diamines and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The resulting SPIs had the same chemical composition and ion exchange capacity (IEC) but quite different solubility behaviors and water stability. Nonlinear sulfonated diamine ( m-BAPBDS and oBAPBDS)-based polyimides showed much better solubility in many organic solvents than the linear diamine ( pBAPBDS and iBAPBDS)-based ones. It was found that the water stability of the SPI membranes was the total effects of solubility stability and hydrolysis stability. Solubility stability is mainly determined by the IEC level and the configuration of the sulfonated diamine moiety. High IEC and nonlinear configuration lead to poor solubility stability and vice versa. Hydrolysis stability is strongly dependent on the basicity of the sulfonated diamine moiety. Highly basic diamines give much better hydrolysis stability than weakly basic ones. Water stability is also affected by the chain flexibility of the SPIs, i.e., polyimides with flexible structure tend to have better water stability than the ones with rigid structure. As a result, NTDA- pBAPBDS, which has linear and highly basic diamine moiety and flexible main chain showed excellent water stability at high temperature. For example, it could maintain mechanical strength after being soaked in water at 80°C for more than 1000 h and the pBAPBDS-based co-SPIs displayed much better water stability at 100 or 130°C.
Synthesis and Characterization of Novel Sulfonated Polyimides Derived from Naphthalenic Dianhydride
Authors: Chen Xinbing , Yin Yan , Tanaka Kazuhiro , Kita Hidetoshi , Okamoto Ken-Ichi
Published: September 2006

4,4′-Ketone dinaphthalene 1,1′,8,8′-tetracarboxylic dianhydride (KDNTDA) was prepared by a new route including six steps with an overall yield of 19%. The structure was confirmed by IR, 1H NMR and UV spectroscopy. Several novel sulfonated polyimides (SPIs) derived from KDNTDA were synthesized and their structures were characterized by IR and 1H NMR. Their reduced viscosity ranged from 0.8 to 4.5 dL g-1 at 35°C. They had good solubility in common aprotic solvents not only in triethylamine salt form but also in proton form. The co-SPIs showed anisotropic membrane swelling with larger swelling in thickness than in plane, while the homo-polymer displayed isotropic membrane swelling. The thermal stability measurements revealed that sulfonic acid group in KDNTDA-based SPIs were stable up to 300°C. They displayed reasonably high proton conductivity, water stability and mechanical properties.
Solid-state Conducting Polymer Actuator based on Electrochemically-deposited Polypyrrole and Solid Polymer Electrolyte
Authors: Kang Hye-Ran , Jo Nam-Ju
Published: September 2006

Conducting polymer (CP) actuators undergo a volumetric change as their redox state is changed. The volumetric change is due to the movement of counter ions into the film during the electrical oxidation process. Liquid electrolytes are mostly used for the actuation of CP actuators, but that is an impediment for practical use of CP actuator. To overcome this problem, in this study solid polymer electrolyte (SPE) was introduced into the CP actuator instead of electrolyte solution. A polypyrrole (PPy)/SPE/PPy electroactive tri-layer actuator was prepared by the electrochemical polymerization of pyrrole and the actuation characteristics were studied. An all-solid actuator, consisting of two PPy films and a SPE based on polyurethane (PU), clearly showed a reversible displacement in an atmosphere when a voltage was applied.
Synthesis of Blue Emitting Alicyclic Polyimides using One-pot Alternating Copolymerization Method
Authors: Kudo Kazuaki , Imai Takahiro , Hamada Takashi , Sakamoto Seiji
Published: September 2006

A series of alternating copolyimides (altPIs) having highly blue fluorescing 9,10-diphenyl-anthracene units were synthesized and the photoluminescence of the altPIs were investigated. The alt-PIs were prepared by sequential addition of two diamines to a solution of spiroalicyclic tetracarboxylic dianhydride, rel[1R,5S,6R]-3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3--(tetrahydrofuran-2-,5--dione) (DAn), on the basis of the unique regioselective ring opening reactivity of DAn to the aromatic amines. The alternating structure of the polyimides was confirmed by comparison of its 1H NMR with that of the corresponding random counterparts. The altPIs showed glass transition temperature higher than 240°C. A 5% weight loss temperature was in a range of 335 to 376°C. The polyimides showed blue fluorescence (λmax = 435 to 436 nm) in DMSO solution with a fluorescence quantum yield of 0.64 to 0.77. In the film state, although small red shift was observed compared to the solution state, the altPIs gave blue emission (λmax = 437 to 447 nm).
High Performance Polybenzoxazines as Novel Thermosets
Authors: Takeichi Tsutomu , Agag Tarek
Published: September 2006

Polybenzoxazine as a novel phenolic type thermoset has been developed to overcome the shortcomings associated with the use of the traditional phenolics. It can be prepared from cyclic benzoxazines via thermally induced ring-opening polymerization. Various benzoxazine monomers can be synthesized from mono-or diamines and mono-or bisphenols with formaldehyde. Polybenzoxazines have not only the advantageous properties of conventional phenolic resins such as high thermal properties, but also other interesting advantages that are not found in the traditional phenolic resins such as excellent dimensional stability. The disadvantages of the typical polybenzoxazines are the high temperature needed for complete cure and the brittleness of the cured materials. Further improvement of thermal properties is also expected for application in harsh conditions. Herein we report on various approaches for performance improvement of polybenzoxazine. These approaches include alloying with other high performance polymers, hybridization with inorganics, and designing of novel monomers as well as high molecular weight polymeric precursors. By these approaches, lowering of the cure temperature, improvement of toughness, and enhancement of thermal and mechanical properties were achieved.
Direct Polycondensation of Aromatic Tetracarboxylic acids with Aromatic Diamines in Ionic Liquids
Authors: Yoneyama Masaru , Matsui Yuichi
Published: September 2006

The direct polycondensation of aromatic diamines and tetracarboxylic acids was studied using imidazolium-type ionic liquids as the reaction medium. Polyimides with inherent viscosities of 0.05 dL g-1 could be prepared in high yields by this novel polycondensation at 150°C for 12 h without polyamic acids. In this reaction, ionic liquids could catalyze the condensation and cyclodehydration reaction of dicarboxylic acids and amines to directly give imide rings.
End-Crosslinking Gelation of Poly(amide acid) Gels studied with Scanning Microscopic Light Scattering
Authors: Furukawa Hidemitsu , Kobayashi Mizuha , Miyashita Yoshiharu , Horie Kazuyuki
Published: September 2006

Network formation in the gelation process of end-crosslinked poly(amide acid) gels, which are the precursor of end-crosslinked polyimide gels, was studied by scanning dynamic light scattering. The gelation process is essentially non-reversible due to the formation of covalent bonds. The molecular structure formed in the gelation process is controlled by varying the equivalence ratio of end-crosslinker to oligomer during the preparation. It was found that a couple of relaxation modes are observed in the gelation point even for semi-rigid poly(amide acid) solutions. This is similar to flexible polymer solutions and convenient to characterize the molecular structure in the gelation processes. The fast mode is related to the cooperative diffusion process of the network structure formed by over lapped macromolecules, i.e., gel mode, which determines the averaged mesh-size of the network structure. The slow mode is related to the relaxation time of the formation of the transient network structure, which shows a slowing down close to the gelation point and disappears after gelation due to the formation of the permanent network structure.