bluuebunny/crossref_metadata_2025 huggingface dataset:
Choroidal ependymocytes in culture: Expression of markers of polarity and function
Authors: Péraldi‐Roux S. , Dao B. Nguyen‐Than , Hirn M. , Gabrion J.
Published: April 2003

Long‐term primary cultures derived from fetal mouse or rat choroid plexus were obtained in serum‐supplemented media. Monoclonal and polyclonal antibodies to basolateral and apical membrane components were used to observe the expression of specific markers of polarity and function. Choroid plexus cultures and thin frozen sections of adult tissues were compared by immunocytochemistry. Two polyclonal antibodies directed against laminin and fibronectin were used on cultured choroid plexus and sectioned tissues, showing that fibronectin and laminin are located on the basolateral membrane domain in ependymocytes in vitro, as well as in vivo. Na+‐K+ATPase was apically detected by light and electron microscopy with a monoclonal antibody (Mab H30) in both cultured cells and sectioned tissues. Double immunofluorescent staining with Mab H30 and affinity‐purified polyclonal antibodies to the α subunit of G0 protein (G0α) demonstrated the relatively similar distribution of the two antigens on the apical face of the choroidal tissue, both in vivo and in vitro. The distribution of these markers shows a typical differentiation with maintenance of polarized features in choroidal ependymocytes in culture, testifying that this cell culture system constitutes an interesting model for studying the functional characteristics of ependymal cells of the choroid plexus.
DNA synthesis experimentally induced in neurons: Tetraploidy or hyperdiploidy?
Authors: Poncino A. , Geuna S. , Scherini E. , Robecchi M. G. Giacobini , Filogamo G.
Published: April 2003

DNA synthesis triggered in Auerbach's plexus neurons by hypertrophy of muscular territory is related to a condition of hyperdiploidy.
Expression and quantitative changes of carbonic anhydrase in developing neurones of rat central nervous system
Authors: Nógrádi Antal , Mihály András
Published: April 2003

Postnatal changes in carbonic anhydrase activity were investigated in the islands of Calleja, which have been previously reported to contain the enzyme. Results obtained with a new modified method of Hansson provided further evidence for the distinction between the medial and lateral islands of Calleja. The enzyme was localized mainly in the nucleus and cytoplasm of granule cells without showing binding to any cytoplasmic organelle. No large neurons of the islands displayed carbonic anhydrase reactivity. The time course and rate of increase of carbonic anhydrase expression were different in the giant island of Calleja and lateral islands and this finding may strengthen the hypothesis regarding the medio‐lateral diversity of Calleja's islands. On the other hand, at the end of the maturation process the granule cell complexes showed no significant difference in the proportion of carbonic anhydrase positive neurones. The almost equal rate of appearance of carbonic anhydrase reactive granule cells raises the possibility of a basic common role of both medial and lateral islets.
Absolute refractory period of human nerve fibres during postnatal myelination
Authors: Duron Bernard , Khater‐Boidin Josette
Published: April 2003

In order to study the absolute refractory period of a given group of nerve fibres during development we measured absolute refractory periods and conduction velocities of motor fibres and the most excitable fibres in the human ulnar nerve of newborns, children and adults. In each group of nerve fibres absolute refractory period was not correlated to conduction velocity (i.e. fibre diameters) and was rather constant during development. However, absolute refractory period of the most excitable fibres was smaller than absolute refractory period of motor fibres independently of the subject's age. Thus, it appears that already at birth, absolute refractory period is characteristic for a given group of nerve fibres.
Effects of serotonin on intracellular calcium in embryonic and adult Helisoma neurons
Authors: Goldberg Jeffrey I. , Mills Linda R. , Kater Stanley B.
Published: April 2003

The neurotransmitter serotonin has been shown to regulate neurite outgrowth in many embryonic and adult Helisoma neurons. To determine whether intracellular calcium concentration is also regulated by serotonin in large numbers of neurons, the calcium indicator Fura 2 was used to measure intracellular calcium in mass‐dissociated cultures of embryonic and adult neurons. Comparisons between embryonic and adult neurons revealed that embryonic neurons have a narrow population distribution of rest intracellular calcium levels around relatively low values. In contrast, the population distribution for adult neurons covered a much wider range of rest calcium concentrations. In both embryonic and adult cultures, serotonin induced a shift in the population distribution of calcium concentrations to higher levels, and increased the mean and median calcium concentrations. Analysis of individual adult neurons prior to and following the addition of serotonin revealed that approximately 50% of the neurons responded with an increase in calcium concentration. In contrast, there was no evidence of a serotonin‐induced decrease in calcium concentration in any neurons. Since the percentage of neurons responding to serotonin in this study is very similar to the percentage that responded in previous studies on neurite outgrowth, these data support the hypothesis that an increase in intracellular calcium is a common intermediate step in the regulation of neurite outgrowth by serotonin throughout the Helisoma nervous system.
Activation of phosphoinositide turnover and protein kinase C by neurotransmitters that modulate calcium channels in embryonic chick sensory neurons
Authors: Harish O.E. , Role L.W.
Published: April 2003

Gamma aminobutyric acid (GABA) and norepinephrine modulate the excitability of primary chick sensory neurons by decreasing the voltage dependent Ca current. Although previous electro‐physiological studies indicate that neurotransmitter modulation of the Ca current in these neurons involves protein kinase C, the biochemical aspects of this mechanism have not been examined directly. We find that both norepinephrine (via a unique a receptor subtype) and GABA (via GABAb receptors) linked to pertussis toxin sensitive pathways, stimulate the metabolism of membrane phosphatidylinositol phospholipids in primary chick sensory neurons. In addition, norepinephrine causes the rapid translocation of C kinase activity from cytosolic to membrane associated distribution, consistent with its rapid activation in response to applied neurotransmitter. The pharmacology, pertussis toxin sensitivity and time course of the biochemical changes due to neurotransmitter treatment parallel the effects of these transmitters on calcium current modulation. These biochemical studies confirm the hypothesis that activation of protein kinase C is critically involved in calcium channel modulation in embryonic chick sensory neurons.
Correlation between p19 presence and MHC class II expression in human fetal astroglial cells cocultured with HTLV‐I donor cells
Authors: Macchi B. , Caronti B. , Cocchia D. , Gremo F. , Torelli S. , Sogos V. , Bonmassar E. , Lauro G.M.
Published: April 2003

The possibility of a direct infection of human brain by HTLV‐I, has been studied using an in vitro model. Human fetal astroglial cells were cocultivated with irradiated HTLV‐I donor cell line MT‐2, and assayed for the presence of HTLV‐I core protein p19 after 1 week. Fifty‐six per cent of GFAP positive astrocytes showed the viral core protein p19 and increased expression of Class II MHC antigens. Electron microscopy of astroglial cells exposed to HTLV‐I revealed the presence of vacuoli‐like structures containing viral core protein p19. Cell intermediate filament cytoskeleton was also disorganized. Even if this study does not provide direct evidence for virus replication inside astroglial cells, all these findings suggest that HTLV‐I can indeed enter the cell and exert a cytopathic effect. Therefore the results of the present study are consistent with the hypothesis that astroglial cells could be involved in demyelination processes occurring in the HTLV‐I associated neurological disorders, such as human associated myelopathy and tropical spastic paraparesis.
Localization and activity of transglutaminase, a retinoid‐inducible protein, in developing rat spinal cord
Authors: Perry Michael J.M. , Haynes Laurence W.
Published: April 2003

The distribution of the retinoid‐inducible enzyme, tissue transglutaminase (tTG) in developing rat spinal cord was determined by enzyme assay and immunocytochemistry. tTG activity was at its highest in the forebrain in late foetal development. In hindbrain and spinal cord, elevated activity persisted until after birth. In spinal cord only, a second peak of activity occurred during the first week post partum (P3). tTG was associated with both the cytosolic and particulate tissue fractions throughout spinal cord development, but the particulate component was more prominent in the early postnatal period. tTG was more concentrated during this period in the ventral horn, where the particulate‐associated enzyme activity was highest. In spinal cord at 3 days post partum, particulate tTG could be solubilized with lubrol‐PX, dithiothreitol and potassium thiocyanate. Both soluble and particulate‐associated tTG coeluted with guinea‐pig liver transglutaminase C by DEAE‐sephacel chromatography. The first peak of tTG activity during late foetal life coincided with the transient localization of the enzyme by immunocytochemistry in vascular endothelia throughout the spinal cord. The second peak of activity at 3 days post partum, by which time vascular immunoreactivity was absent, coincided with the occurrence of small numbers of intensely immunoreactive motor neurones in the ventral horn. Immunoreactive motor neurones were seen predominantly at two levels: the lower thoracic segments and lumbar enlargement. The abnormal appearance of many immunoreactive neurones suggested degenerative changes were occurring. tTG was also present in central canal cluster cells from birth onwards. No neuronal immunoreactivity was seen throughout foetal development. A proportion of motor neurones prepared from E15 spinal cord and grown in coculture with spinal cord astrocytes, were immunoreactive for tTG. All immunoreactive neurones showed signs of degeneration. Addition of myotube‐conditioned medium (a source of cholinergic differentiation factor, CDF) reduced the proportion of tTG‐immunoreactive neurons in the cultures. Schwann cell‐conditioned medium (a source of ciliary neurotrophic factor, CNTF) had a similar but less potent effect on the numbers of immunoreactive neurones. The possibility that tTG is a marker for late, but not early‐phase programmed cell death in the developing rat spinal cord is discussed in the light of a proposed role for tTG in the mechanism of natural cell death by apoptosis.
Developmental profile of glucocorticoid binding to synaptic plasma membrane from rat brain
Authors: Sze Paul Y. , Towle Andrew C.
Published: April 2003

The plasma membranes of several mammalian tissues including the brain are known to have specific binding sites for glucocorticoids. The developmental changes in specific glucocorticoid binding to synaptic plasma membrane (SPM) from rat brain were determined at various postnatal ages, using [3H]triamcinolone acetonide (TA) as the steroid ligand. The specific binding of the labeled glucocorticoid to SPM during the first 2 postnatal weeks was only 40% of the adult level. An increase of the specific binding occurred after day 15 and this developmental rise of binding reached the adult level approximately by the end of the fourth week. Methodologically, these developmental data are detailed in the present article to include nonspecific binding as well as specific binding. Scatchard analysis indicates that the developmental rise of the specific glucocorticoid binding was due to an increase in the membrane binding sites. The ontogenetic increase of membrane binding sites during postnatal brain development provides additional evidence that these binding sites have physiological significance in brain function.
Differential laminar expression of AMPA receptor genes in the developing rat visual cortex using in situ hybridization histochemistry. Effect of visual deprivation
Authors: Roβner Steffen , Kumar Ashok , Kues Wilfried , Witzemann Veit , Schliebs Reinhard
Published: April 2003

The postnatal development of laminar pattern of AMPA receptor mRNA subtypes GluR‐A through to GluR‐D (flip variants) in the visual cortex of both normally raised and monocularly deprived rats (one eyelid sutured at the age of 11 days) was studied using in situ hybridization histochemistry and computer‐assisted image analysis. The AMPA receptors GluR‐A through to GluR‐D transcripts exhibit a differential laminar expression pattern in the developing rat visual cortex. At birth the levels of GluR‐A transcripts are lower by about 50% in each visual cortical layer as compared to the adult values. In contrast, GluR‐B to GluR‐D mRNAs are expressed in all cases at higher levels at birth than in the adult brain.

Unilateral eyelid closure at postnatal day 11 for several periods of time resulted in both transient and permanent changes in the laminar development of GluR‐A through to GluR‐C transcripts but hardly affected the GluR‐D mRNA subtype. The distinct laminar developmental pattern of AMPA receptor mRNAs in rat visual cortex as well as the differential effects of visual deprivation suggest specific roles of AMPA receptor subtypes during the early postnatal maturation of visual function.
Differential development of the stress response in congenital learned helplessness
Authors: King J.A. , Campbell D. , Edwards E.
Published: April 2003

Early in the development of the hypothalamic‐pituitary‐adrenal (HPA) axis, the rat undergoes a stress hyporesponsive period of blunted responses to several Stressors including cold exposure (CE) and maternal deprivation (MD). We examined the development of the axis by monitoring adrenocorticotropin hormone (ACTH) plasma levels in an animal model of depression and/or anxiety characterized by learned helpless (LH) behavior and a dysfunctional HPA axis in adult life. On postnatal day 7 there was no significant difference in basal plasma ACTH levels between congenital (cLH) and controls, but cLH animals showed a blunted response to CE (P<0.001). By postnatal day 14 there was a dramatic increase in ACTH response to CE (P<0.005). On postnatal day 21 baseline ACTH and response to CE were again significantly suppressed in cLH rats. Stress responsiveness to MD was present in all groups and was insignificantly different for all ages of development between groups. These findings suggest that rats with congenital learned helplessness undergo a differential response in the development of the HPA axis in that the axis was hypersensitive at postnatal day 14 and became hyporesponsive beyond day 14 and this may, in part, account for the dysfunctional stress response observed during adulthood.
Neuraminic acid specific lectins as markers of early cortical plate neurons
Authors: Adam E. , Dziegielewska K.M. , Saunders N.R. , Schumacher U.
Published: April 2003

Early cortical plate and subplate cells in the developing neocortex of many animal species and humans contain one specific plasma protein, fetuin. Fetuin is heavily glycosylated and it is possible that due to the large amount of sugars, this molecule may play a part in cellular recognition during brain development.

Cellular and extracellular carbohydrates in the developing brain of the sheep were studied histochemically using a battery of fluorescein‐labelled lectins. Two neuraminic acid specific lectins, Sambucus nigra and Maackia amurensis, labelled consistently the fetuin‐positive cells as demonstrated by double labelling with lectins and antifetuin antibodies. Brain sections from other species, known to contain fetuin‐positive cells (fetal cow, postnatal tammar wallaby) showed a similar lectin staining pattern to that of the sheep fetus. Additionally, sections from species thought to contain fetuin in their developing brains that failed to cross‐react with available antifetuin antibodies (postnatal Monodelphis, fetal cat) also demonstrated lectin‐positive staining in the same neuronal cell population.

Thus, neuraminic acid is a common and well conserved terminal carbohydrate in cortical plate and subplate neurons of the developing brain. Neuraminic‐specific lectins are useful markers for these neurons in addition to the more traditional use of immunocytochemical methods in studies of formation of the neocortex.
Acute effects of perinatal hypoxic insult on concentrations of dopamine, serotonin, and metabolites in fetal monkey brain
Authors: Binienda Zbigniew , Fogle C. Matthew , Slikker William , Ali Syed F.
Published: April 2003

Seven monkeys (Macaca mulatta) were laparotomized under general anesthesia (halothane, nitrous oxide, oxygen). Fetal hypoxia was induced in four monkeys by occlusion of the umbilical cord with a hydraulic occluder for 5–6 min. Three sham‐operated fetuses served as controls. After unclamping, the fetuses were allowed to reperfuse for 20–30 min. To monitor hypoxia, the fetal electrocardiogram was recorded continuously. Hypoxic insult was associated with a decrease in fetal heart rate during the occlusion. After reperfusion, fetuses were immediately sacrificed and neocortex regions dissected on ice, frozen on dry ice and stored at −70°C. Dopamine, 3,4‐dihydroxyphenylacetic acid, homovanillic acid, serotonin, and 5‐hydroxyindoleacetic acid were assayed by high performance liquid chromatography with electrochemical detection (HPLC/EC) in hippocampus, caudate nucleus and cortical regions. In the hippocampus, there was a significant increase in 5‐hydroxyindoleacetic acid concentration. In prefrontal cortex, there was a trend toward an increase in serotonin but no effects on dopamine and homovanillic acid concentrations. Dopamine, serotonin and metabolites were not altered in the caudate nucleus. These data demonstrate that fetal hypoxia followed by reperfusion produced an increase in serotonin concentration measured within the hippocampus and selected cortical areas known to be targets of hypoxic injury.
Nicotine effects on the regulation of amyloid precursor protein splicing, neurotrophin and glucose transporter RNA levels in aged rats
Authors: Monteggia L.M. , Arneric S.P. , Giordano T.
Published: April 2003

It has been reported that an inverse relationship exists between nicotine intake and the incidence of Alzheimer's Disease (AD). Although nicotine has been reported to induce c‐fos, in the present study it was shown that this induction does not alter the accumulation of a number of transcripts associated with AD. Altered splicing patterns of Amyloid Precursor Protein (APP) and changes in neurotrophin and glucose transporter expression have been implicated in AD and behavioral deficits in rats. The effects of subacute administration of nicotine (12 mg/ml at 2.3 μl/hr for 14 days) on the abundance levels of APP, glucose transporter(GLUT) and neurotrophin transcripts were determined by rtPCR in the hippocampus, cortex, and striatum of aged (22–24 months) male Wistar rats. No significant differences between saline and nicotine infused rats were detected for APP abundance levels or ratio of the various isoforms. However, both groups had a higher level of APP transcripts containing the Kunitz Protease Inhibitor (KPI) domain in the hippocampus than in either the cortex or striatum. The mean percentages of APP 695 for the two groups were 75% in the hippocampus and 82 and 81% in the cortex and striatum, respectively (P<0.01). No changes in the abundance of GLUT1, GLUT3, nerve growth factor (NGF) or brain derived neurotrophic factor (BDNF) transcripts were detected. However, since both APP and GLUT1 are thought to be regulated post‐transcriptionally, the present results do not rule out a change at the protein level. Further work will be required to determine whether nicotine can influence the expression of these proteins which affect neuronal function.
Migration behavior of granule cells on laminin in cerebellar microexplant cultures from early postnatal reeler mutant mice
Authors: Nagata Isao , Terashima Toshio
Published: April 2003

The behaviors of neuroblasts of granule cell neurons and their precursor cells on a poly‐l‐lysine/laminin substratum were examined in cerebellar microexplant cultures from early postnatal reeler mutant and normal mice. The total numbers of migrating neuroblasts and their precursor cells or blast cells derived from the mutant cerebellum were markedly reduced in comparison with their normal counterparts. However, no difference was shown between these two strains in either the numbers of blast cells or neuroblasts that migrated from single explants. In addition, all behaviors examined, such as migration of neuroblasts and the proliferation of blast cells in culture were identical between both genotypes. Thus, behaviors of both granule cells and their precursors in the cerebellar cortex of reeler mutant mouse may be qualitatively identical to those of normal counterparts, but precursors of granule cells in the external germinal layer of the cerebellar cortex may be reduced in the reeler mouse.
The survival of cultured mouse cerebellar granule cells is not dependent on elevated potassium‐ion concentration
Authors: Mogensen Helle S. , Hack Nicola , Balázs Robert , Jørgensen Ole Steen
Published: April 2003

The effects of K+‐induced membrane depolarization were studied on the survival and biochemical parameters in mouse and rat cerebellar granule cells grown in micro‐well cultures. Cell numbers were determined by estimating DNA content using the Hoechst 33258 fluorochrome binding assay. DNA from degenerated cells was removed by prior DNAase treatment. These DNA estimates of cell numbers were comparable with values obtained by direct counting of fluorescein diacetate‐stained viable cells. In agreement with previous studies, the survival of rat granule cells was promoted by increasing the concentration of K+ in the medium from 5 to 25 mM throughout a 7‐day culture period. In contrast, mouse granule cells survived in culture containing ‘low’ K+ (5 or 10 mM), as well as in the presence of ‘high’ K+ (25 mM). On the other hand, several biochemical parameters in mouse granule cells were markedly increased by cultivation in ‘high’ as compared with ‘low’ K+‐containing media, demonstrated by increased fluorescein diacetate esterase activity, enhanced rate of NADPH‐dependent tetrazolium reduction, augmented 2‐deoxy‐d‐glucose accumulation and increased N‐methyl‐d‐aspartate‐evoked 45Ca2+ influx. It was concluded that although cultivation in ‘high’ K+ promotes biochemical differentiation in mouse cerebellar granule cells, these cells differ from their rat counterparts in that they do not develop a survival requirement for K+‐induced membrane depolarization.
Intracerebroventricular injection of streptozotocin induces discrete local changes in cerebral glucose utilization in rats
Authors: Duelli Roman , Schröck Helmut , Kuschinsky Wolfgang , Hoyer Siegfried
Published: April 2003

The purpose of the present study was to investigate whether or not cerebral glucose utilization is changed locally after damage of the neuronal insulin receptor by means of intracerebroventricular (icv) streptozotocin (STZ) administered in a subdiabetogenic dosage (1.5 mg/kg bw.). STZ was administered at the start of the study, and 2 and 21 days later bilaterally into the cerebral ventricles in rats of a mean age of 18 months. The local distribution of cerebral glucose utilization was analyzed in conscious rats on the 42nd day after the first STZ injection using the quantitative (14C)‐2‐deoxyglucose method. Of the 35 brain structures investigated from autoradiograms of brain sections, 17 showed a reduction in glucose utilization. Decreases in glucose utilization were observed in the frontal, parietal, sensory motor, auditory and entorhinal cortex and in all hippocampal subfields. In contrast, glucose utilization was increased in two white matter structures. The decrease in cerebral glucose utilization observed in cortical and hippocampal areas in the present study may correspond to changes in morphobiological parameters which have been found in patients with Alzheimer's disease. The present data are in accordance with the hypothesis that an impairment in the control of neuronal glucose metabolism at the insulin receptor site may exist in sporadic dementia of Alzheimer type (DAT), and can be studied by the icv STZ animal model.
Hyperglycemia delays rostral initiation sites during neural tube closure
Authors: Peng Ying , Finley Brent E. , Fechtel Kim
Published: April 2003

Neural tube defects contribute greatly to perinatal loss, physical handicap, mental retardation and other developmental defects, yet the mechanisms through which they occur are poorly understood. One hindrance to the study of these defects at the cellular and molecular levels is the low frequency with which they arise in susceptible animals. The present study utilizes a culture system for the study of rodent exencephaly, an animal model of human anencephaly, in which a high frequency of affected animals are obtained by culture in hyperglycemic rat serum. Rat embryos were dissected at day 9.5 from timed‐pregnant Sprague‐Dawley dams and cultured under standard conditions developed by New [Biol. Rev. (1978) 53, 81–122]. Embryos cultured under elevated glucose conditions are able to close the caudal neural tube with the failure of neural tube closure limited to the rostral neuralepithelium. In this report we present the novel finding that, although at the end of culture frequently only the hindbrain region remains open, the normal sequence of events expected during rostral closure anterior to the hindbrain is markedly delayed. In embryos cultured in hyperglycemic serum, both rostral initiation sites II and III are significantly delayed. The degree of delay increases with increasing glucose concentration in the culture medium.

These studies support the use of this defined in vitro model of anencephaly for studies of the molecular and cellular bases underlying the failure of hindbrain closure and demonstrate that sufficient numbers of affected animals can be produced to obtain significant results. The similarity of our findings with hyperglycemia‐induced exencephaly to studies in mouse strains that are genetically susceptible to anencephaly suggest that the mechanisms underlying these different routes to failure of neural tube closure share common precursor events.
Coincidental appearance of the α1 subunit of the gaba‐a receptor and the type ibenzodiazepine receptor near birth in macaque monkey visual cortex
Authors: Hendrickson Anita , March Derrick , Richards Grayson , Erickson Andra , Shaw Christopher
Published: April 2003

The expression of subtypes of the GABA‐A/benzodiazepine receptor complex has been studied during pre‐ and postnatal development of Macaca monkey visual cortex using complementary radioligand and immunocytochemical labeling. Type I benzodiazepine receptors were labeled directly by [3H]zolpidem. Type II receptors were determined by the amount of binding for [3H]flunitrazepam (FZ) persisting in the presence of the type I‐specific ligand CL218872. Monoclonal antibody bd24 was used to label α1 subunits and bd17 to label β2 and β3 subunits of the GABA‐A receptor. Radioligand binding data and bd17 immunoreactivity indicated that type II benzodiazepine receptors were present by fetal day (Fd) 74 (44% of gestation). Immunoreactivity for the β2/β3 subunits increased until 3–6 weeks after birth, and then declined somewhat into adulthood. Neither radioligand labeling for type I receptors nor immunocytochemical staining for the α1 subunit were apparent until mid‐gestation. Both markers appeared shortly before birth in layer 4C, and then in other cortical layers after birth. Immunoreactivity for the α1 subunit increased steadily after birth until it became more intense than that for β2/3 subunits in the adult. Quantitative densitometry of CL218872 competition for [3H]FZ binding showed that type I/II distribution was 22%/78% at Fd103; 42%/58% at Fd131; 67%/33% at 9 months; and 61%/39% in adult visual cortex.

This “switch” between benzodiazepine receptor subtypes overlaps the postnatal critical period for geniculostriate development, suggesting that the change from type II to type I receptors and the appearance of α1 subunits may play a decisive role in the maturation of geniculocortical axon terminations and cortical response properties. It remains to be shown whether this ‘switch’ is dependent on functional visual input.
Interaction of the K+ channel KcsA with membrane phospholipids as studied by ESI mass spectrometry
Authors: Demmers Jeroen A.A. , van Dalen Annemieke , de Kruijff Ben , Heck Albert J.R. , Killian J.Antoinette
Published: April 2003

In this study we have used electrospray ionization mass spectrometry (ESI‐MS) to investigate interactions between the bacterial K+ channel KcsA and membrane phospholipids. KcsA was reconstituted into lipid vesicles of variable lipid composition. These vesicles were directly analyzed by ESI‐MS or mixed with trifluoroethanol (TFE) before analysis. In the resulting mass spectra, non‐covalent complexes of KcsA and phospholipids were observed with an interesting lipid specificity. The anionic phosphatidylglycerol (PG), and, to a lesser extent, the zwitterionic phosphatidylethanolamine (PE), which both are abundant bacterial lipids, were found to preferentially associate with KcsA as compared to the zwitterionic phosphatidylcholine (PC). These preferred interactions may reflect the differences in affinity of these phospholipids for KcsA in the membrane.
Cloning, expression and pharmacology of the mouse 5‐HT4L receptor
Authors: Claeysen Sylvie , Sebben Michèle , Journot Laurent , Bockaert Joël , Dumuis Aline
Published: April 2003

Since most of our knowledge on pharmacological properties of brain 5‐HT4 receptors have been discussed for mouse colliculi neurons, we cloned the corresponding receptor using the RT‐PCR approach. As expected, the homology with the already cloned rat 5‐HT4L
receptor was high, revealing only 16 differences at the amino‐acid level. One of the differences, proline75 in mouse, alanine75 in the already published rat sequences was not confirmed. Therefore this proline is part of the consensus sequence present in all 5‐HT receptor transmembrane domain II (LVMP). Comparing the affinities of 11 agonists and five antagonists for the cloned mouse receptor (5‐HT4L
) expressed in LLCPK1 and the corresponding receptor in mouse colliculi shows an excellent correlation. The transfected mouse 5‐HT4L
receptor stimulated cAMP production. When expressed at high density, it exhibited intrinsic activity. In contrast to the previously described distribution, we found that mRNA encoding for both the short (5‐HT4S
) and the long form (5‐HT4L
) of 5‐HT4 receptors are expressed in all mouse and rat brain areas.
The manufacturing strategy formulation process: Linking multifunctional viewpoints
Authors: Menda Rafael , Dilts David
Published: April 2003

While there has been considerable research on thecontentof manufacturing strategy, there is a paucity of literature concerning theprocessof manufacturing strategy formulation [Ward, P.T., Brickford, D.J., Leong, G.K., 1996. Configuration of manufacturing strategy, business strategy, environment, and structure, J. Manage., 22(4) 597–626; Leong, G.K., Snyder, D.L., Ward, P.T., 1990. Research in the process and content of manufacturing strategy, Omega, 18(2) 109–122]. Many researchers have highlighted the need to overcome this deficiency by studying the process of developing manufacturing strategy [Adam, E.E., Swamidass, P.M., 1989. Assessing operations management from a strategic perspective, J. Manage., 15(2) 181–203; Anderson et al., 1989; Leong, G.K., Snyder, D.L., Ward, P.T., 1990. Research in the process and content of manufacturing strategy, Omega, 18(2) 109–122]. To effectively link the manufacturing strategy of a firm to the needs of the marketplace, critical competitive factors or order‐winning criteria must be understood and agreed upon both by operations and marketing managers [Hill, T.J., 1983. Manufacturing's strategic role, J. Operational Res. Soc., 34(9) 853–860; Hill, T.J., 1994. Manufacturing Strategy—Text and Cases, 2nd edn., Irwin, Homewood, IL]. For this study, we created and examined a process of establishing a set of order‐winning criteria for a consumer pharmaceuticals firm which involved the participation of sixteen managers from seven functional areas over four months. The foundation of the process was developed by Hill [Hill, T.J., 1989. Manufacturing Strategy—Text and Cases. Irwin, Homewood, IL; Hill, T.J., 1994. Manufacturing Strategy—Text and Cases, 2nd edn., Irwin, Homewood, IL], however it was soon evident that additional steps were required. The expanded process we developed both exposed significantly differing views among the managers and raised several questions with important managerial and research implications.
Advanced manufacturing technology: Implementation policy and performance
Authors: Small Michael H. , Yasin Mahmoud M.
Published: April 2003

This article investigates the relationships between adoption of various advanced manufacturing technologies (AMT), the way that firms plan for and implement them, and their eventual performance. Data obtained from 125 manufacturing firms in the U.S. is used to test several hypotheses which were derived from an extensive review of the AMT implementation literature. The four research questions that drive this study are: (1) What types of planning and installation activities have firms utilized to support their AMT adoptions?, (2) do differences in the level of effort applied to these activities have any impact on the eventual performance of the systems?, (3) are firms that are using integrated technologies, such as FMC/FMS and CIM, applying higher levels of effort on these planning and installation activities than other firms?, and (4) Are these firms achieving higher levels of success than firms that are not using the integrated technologies. The results indicate that firms adopting integrated technologies had exerted significantly higher levels of effort on strategic planning and team‐based project management and had also achieved higher levels of performance across a wider range of performance factors than other firms. In addition, firms that had exerted higher levels of effort on developing human factors appeared to be achieving more of the benefits of AMT than their counterparts. The overall results and the research and practical implications of this study are discussed.
Postnatal phencyclidine‐induced deficit in adult water maze performance is associated with N‐methyl‐d‐aspartate receptor upregulation
Authors: Sircar Ratna
Published: April 2003

The N‐methyl‐d‐aspartate (NMDA) receptor plays an important role in developmental plasticity. Earlier, we have shown that blocking the NMDA receptor with the non‐competitive antagonist phencyclidine (PCP), during a brief postnatal period, disrupts the water maze performance in young juvenile rats (starting at 25 days of age). We now show the long‐term effects of postnatal phencyclidine exposure on spatial learning and memory. Male and female rats were exposed to PCP (1 and 5 mg/kg) or saline, from postnatal days 5–15, and their performance in the Morris water maze (MWM) was tested both as adolescents (starting on postnatal day (PD) 35) and as adults (starting on postnatal day 60). Separate groups of adult male and female postnatal PCP‐treated and saline‐treated rats were sacrificed and saturation [3H]MK‐801 binding experiments were carried out in their hippocampi and frontal cortices; hippocampus and frontal cortex have high densities of NMDA receptors and both regions are important in spatial learning and memory. Postnatal PCP administration disrupted the water maze performance both in adolescent and adult rats of both sexes. Adult male and female rats treated postnatally with PCP had increased maximal [3H]MK‐801 binding in the hippocampus and frontal cortex compared to same‐sex saline‐treated controls. Taken together, repeated postnatal PCP (RPP) administration impaired the acquisition of spatial learning in adolescent and adult male and female rats, and this cognitive deficit was associated with increased [3H]MK‐801 labeled NMDA receptor in the hippocampus and frontal cortex. These findings are consistent with the hypothesis that PCP treatment during the postnatal period produces deficits in the water maze performance by disrupting the developing glutamatergic system.
Stärken und Schwächen der Gestaltung eines kollaborativen Teleseminars zum Thema “Distance Learning“
Authors: Horz Holger , Fries Stefan , Hofer Manfred
Published: April 2003

Zusammenfassung. Gegenstand dieser Arbeit ist die pädagogisch-psychologische Evaluation eines Teleseminars zum Thema “Distance Learning“, in dem Studierende an vier Universitäten kooperierten. Die in der Evaluation realisierten Kriterien wurden aus dem Learning Cycle ( Mayes, Coventry, Thompson & Mason, 1994 ) sowie aus der DOT-Strategie ( Hofer et al., 2000 ) hergeleitet. Zentrale Ergebnisse der Evaluation sind: (1) Aus Sicht der Studierenden war das Seminar im Hinblick auf den Wissenserwerb in den Phasen der Wissenskonzeptualisierung und Wissenskonstruktion erfolgreich. (2) Es gelang nicht, den Dialog zwischen den Orten ausreichend zu fördern. Ursächlich hierfür sind technische Defizite und eine (vorwissens-)heterogene Zuhörerschaft an den verschiedenen Standorten, die sich hemmend auf die Kommunikation auswirkten. (3) Die Seminarzufriedenheit der Studierenden hing stärker vom vermuteten Wissensgewinn ab als davon, ob und in welchem Umfang technische Probleme aufgetreten waren. Die Ergebnisse verdeutlichen, dass gerade im Bereich der telemedialen Lehre eine längerfristige didaktische und organisatorische Vorbereitung erforderlich ist.
Cleavage of fragments containing DNA mismatches by enzymic and chemical probes
Authors: BROWN James , BROWN Tom , FOX Keith R.
Published: April 2003

We prepared synthetic 50-mer DNA duplexes, each containing four mismatched base-pairs in similar positions. We examined their cleavage by DNases I and II, micrococcal nuclease (MNase), methidiumpropyl-EDTA-Fe(II) [MPE-Fe(II)] and hydroxyl radicals. We find that single mismatches only produce subtle changes in the DNase I-cleavage pattern, the most common of which is attenuated cleavage at locations 2–3 bases on the 3′-side of the mismatch. Subtle changes are also observed in most of the DNase II-cleavage patterns, although GT and GG inhibit the cleavage over longer regions and generate patterns that resemble footprints. MNase cleaves the heteroduplexes at the mismatches themselves (except for CC), and in some cases cleaves CpG and CpC steps. None of the mismatches causes any change in the cleavage patterns produced by hydroxyl radicals or MPE-Fe(II). We also examined the cleavage patterns of fragments containing tandem GA mismatches in the sequences RGAY/RGAY and YGAR/YGAR (R, purine; Y, pyrimidine). RGAY causes only subtle changes in the cleavage patterns, which are similar to those seen with single mismatches, except that there are no changes in MNase cleavage. However, YGAR inhibits DNases I and II cleavage over 4–6 bases, and attenuates MPE-Fe(II) and hydroxyl radical cleavage at 2 bases. These changes suggest that this mismatch has a more pronounced effect on the local DNA structure. These changes are discussed in terms of the structural and dynamic effects of each mismatch.
Nucleotide-dependent protein folding in the type II chaperonin from the mesophilic archaeon Methanococcus maripaludis
Authors: KUSMIERCZYK Andrew R. , MARTIN Jörg
Published: April 2003

We report the characterization of the first chaperonin (Mm-cpn) from a mesophilic archaeon, Methanococcus maripaludis. The single gene was cloned from genomic DNA and expressed in Escherichia coli to produce a recombinant protein of 543 amino acids. In contrast with other known archaeal chaperonins, Mm-cpn is fully functional in all respects under physiological conditions of 37 °C. The complex has Mg2+-dependent ATPase activity and can prevent the aggregation of citrate synthase. It promotes a high-yield refolding of guanidinium-chloride-denatured rhodanese in a nucleotide-dependent manner. ATP binding is sufficient to effect folding, but ATP hydrolysis is not essential.
Stability of a long field-reversed configuration: Complete two-fluid theory
Authors: Barnes D. C.
Published: April 2003

The stability of a long field-reversed configuration is considered within the two-fluid model. A symmetric quadratic form is obtained with all Hall and finite Larmor radius (FLR) terms included. Assuming slow axial variation, this form is used to derive a leading-order stability formulation. As previously found for single fluid magnetohydrodynamics (MHD) analysis of this problem, the stability problem is posed as a field-line ordinary differential equation for the axial electron displacement alone. All stability results depend only on the ratio G=S*/E where E is the separatrix elongation and S* is the separatrix radius relative to the collisionless ion skin depth. Results are obtained for Hall MHD and also with FLR effects included (as large B gyroviscosity) and show stability for G<Gcrit. As previously concluded, it is found that Gcrit∼1 for Hall MHD. This result is now shown to be nearly independent of relative ion temperature and plasma compressibility. FLR is found to have a very strong stabilizing effect, with Gcrit a strong function of separatrix radius and ranging from 2 to 20 over a relevant experimental range. All modes are found to rotate in the electron diamagnetic direction.
Capsule-areal-density asymmetries inferred from 14.7-MeV deuterium–helium protons in direct-drive OMEGA implosions
Authors: Li C. K. , Séguin F. H. , Frenje J. A. , Petrasso R. D. , Rygg R. , Kurebayashi S. , Schwartz B. , Keck R. L. , Delettrez J. A. , Soures J. M. , McKenty P. W. , Goncharov V. N. , Knauer J. P. , Marshall F. J. , Meyerhofer D. D. , Radha P. B. , Regan S. P. , Sangster T. C. , Seka W. , Stoeckl C.
Published: April 2003

Capsule-areal-density (ρR) asymmetries are studied for direct-drive, spherical implosions on the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Measurements of copious 14.7-MeV protons generated from D3He fusion reactions in the imploded capsules are used to determine ρR. As they pass through the plasma, these protons lose energy, and this energy loss reflects the areal density of the transited plasma. Up to 11 proton spectrometers simultaneously view D3He implosions on OMEGA from different directions. While the burn-averaged and spatially averaged ρR for each implosion is typically between 50 and 75 mg/cm2 for 20-μm plastic shells filled with 18 atm of D3He gas, significant differences often exist between the individual spectra, and inferred ρR on a given shot (as large as ∼±40% about the mean). A number of sources inherent in the direct-drive approach to capsule implosions can lead to these measured ρR asymmetries. For example, in some circumstances these asymmetries can be attributed to beam-to-beam energy imbalance when this imbalance is relatively large (∼25% rms). However, for more uniform illumination the source of the asymmetries is still under investigation.
Modeling the nonlinear saturation of stimulated Brillouin backscatter in laser heated plasmas
Authors: Divol L. , Berger R. L. , Cohen B. I. , Williams E. A. , Langdon A. B. , Lasinski B. F. , Froula D. H. , Glenzer S. H.
Published: April 2003

After showing that the stimulated Brillouin instability (SBS) is likely to be in a saturated regime under conditions of interest for inertial confinement fusion, two examples of reduced models of nonlinear effects that are included in a fluid model are described. Simulations using a nonlinear damping representing the saturation of the amplitude of acoustic waves in the fluid regime (i.e., weak Landau damping) are compared with experimental measurements done on CO2 plasmas. While good agreement is found between the model and a variety of independent experimental measurements, no simple explanation was found for the very low saturation level (well below the amplitude corresponding to the two-ion-decay instability) that has to be used. In the kinetic regime (i.e., large Landau damping), hybrid-particle-in-cell simulations show that nonlinear frequency shifts induced by trapping saturate SBS. A reduced steady-state model has been shown to be in correct agreement with time-integrated measurements done on Be plasmas. Numerical simulations indicate that a more dynamical model is needed to describe the transient evolution of SBS.
The discretized harmonic oscillator: Mathieu functions and a new class of generalized Hermite polynomials
Authors: Aunola M.
Published: April 2003

We present a general, asymptotical solution for the discretized harmonic oscillator. The corresponding Schrödinger equation is canonically conjugate to the Mathieu differential equation, the Schrödinger equation of the quantum pendulum. Thus, in addition to giving an explicit solution for the Hamiltonian of an isolated Josephon junction or a superconducting single-electron transistor (SSET), we obtain an asymptotical representation of Mathieu functions. We solve the discretized harmonic oscillator by transforming the infinite-dimensional matrix-eigenvalue problem into an infinite set of algebraic equations which are later shown to be satisfied by the obtained solution. The proposed ansatz defines a new class of generalized Hermite polynomials which are explicit functions of the coupling parameter and tend to ordinary Hermite polynomials in the limit of vanishing coupling constant. The polynomials become orthogonal as parts of the eigenvectors of a Hermitian matrix and, consequently, the exponential part of the solution can not be excluded. We have conjectured the general structure of the solution, both with respect to the quantum number and the order of the expansion. An explicit proof is given for the three leading orders of the asymptotical solution and we sketch a proof for the asymptotical convergence of eigenvectors with respect to norm. From a more practical point of view, we can estimate the required effort for improving the known solution and the accuracy of the eigenvectors. The applied method can be generalized in order to accommodate several variables.
The increase of binding energy and enhanced binding in nonrelativistic QED
Authors: Chen Thomas , Vougalter Vitali , Vugalter Semjon A.
Published: April 2003

We consider a Pauli–Fierz Hamiltonian for a particle coupled to a photon field. We discuss the effects of the increase of the binding energy and enhanced binding through coupling to a photon field, and prove that both effects are the results of the existence of the ground state of the self-energy operator with total momentum P=0.
A symplectic framework for multiplane gravitational lensing
Authors: Izumiya S. , Janeczko S.
Published: April 2003

We construct a new framework for the study of multiplane gravitational lensing from the view point of symplectic geometry. Symplectic relations are used to compose the systems and weaker Lagrangian equivalence is applied for classifying the caustics of multiplane gravitational lensing.
A bicategorical approach to Morita equivalence for von Neumann algebras
Authors: Brouwer R. M.
Published: April 2003

We relate Morita equivalence for von Neumann algebras to the “Connes fusion” tensor product between correspondences. In the purely algebraic setting, it is well known that rings are Morita equivalent iff they are equivalent objects in a bicategory whose 1-cells are bimodules. We present a similar result for von Neumann algebras. We show that von Neumann algebras form a bicategory, having Connes’s correspondences as 1-morphisms, and (bounded) intertwiners as 2-morphisms. Further, we prove that two von Neumann algebras are Morita equivalent iff they are equivalent objects in the bicategory. The proofs make extensive use of the Tomita–Takesaki modular theory.