bluuebunny/crossref_metadata_2025 huggingface dataset:
Local manufacturing systems and global economy: are they compatible?
Authors: Nassimbeni Guido
Published: February 2003

In the era of global economy, are local manufacturing systems still playing a role or are they destined to fade away? No unequivocal answer to this question can be found in the literature. Some think that globalization exposes all the limits of local industrial systems. Others consider the contraposition between global and local to be only apparent. There could be, however, a clear relation between the firm’s competitiveness on the international market and its territorial roots. The present paper focuses on one of the most important local systems in Italy, i.e. the eyewear district. Based on empirical research, the study analyzes the evolution of the eyewear industry, the strategies used by the larger producers to face the current competitive challenges and the consequences of such actions on the local supply system. It is shown that the district has lost most of its traditional features and inter‐organizational relations have significantly changed. Opportunities arising from new technologies and global economy seem to favor better equipped, large‐sized enterprises rather than small suppliers, or in any case, single units or groups rather than the system. Finally, some suggestions are provided for entrepreneurs or managers operating in industrial districts, concerning vertical integration and sourcing choices (main‐contracting firms), and technological and managerial levers that could better qualify the supply offer (sub‐contracting firms).
Lean manufacturing: context, practice bundles, and performance
Authors: Shah Rachna , Ward Peter T
Published: February 2003

Management literature has suggested that contextual factors may present strong inertial forces within organizations that inhibit implementations that appear technically rational [R.R. Nelson, S.G. Winter, An Evolutionary Theory of Economic Change, Harvard University Press, Cambridge, MA, 1982]. This paper examines the effects of three contextual factors, plant size, plant age and unionization status, on the likelihood of implementing 22 manufacturing practices that are key facets of lean production systems. Further, we postulate four “bundles” of inter‐related and internally consistent practices; these are just‐in‐time (JIT), total quality management (TQM), total preventive maintenance (TPM), and human resource management (HRM). We empirically validate our bundles and investigate their effects on operational performance. The study sample uses data from IndustryWeek’s Census of Manufacturers. The evidence provides strong support for the influence of plant size on lean implementation, whereas the influence of unionization and plant age is less pervasive than conventional wisdom suggests. The results also indicate that lean bundles contribute substantially to the operating performance of plants, and explain about 23% of the variation in operational performance after accounting for the effects of industry and contextual factors.
Global boundary controllability of the de St. Venant equations between steady states
Authors: Gugat M. , Leugering G.
Published: February 2003

We consider the problem of exactly controlling the states of the de St. Venant equations from a given constant state to another constant state by applying nonlinear boundary controls. During this transition the solution stays in the class of

C^1

-solutions. There are no restrictions on the distance between the initial state and the target state, so our result is a global controllability result for a nonlinear hyberbolic system.

On s’intéresse ici à un système décrit par les equations de St. Venant. On montre qu’on peut contrôler le système d’un état initial constant à un autre état constant avec des contrôles frontières non linéaires de façon qu’il y ait une solution

C^1

.

Il n’y a pas de restriction concernant la distance entre les données initiales et les données finales, donc notre résultat est un résultat de contrôlabilité globale exacte pour un système hyperbolique non linéaire.
A Riemann–Hilbert problem and the Bernoulli boundary condition in the variational theory of Stokes waves
Authors: Shargorodsky E. , Toland J.F.
Published: February 2003

This paper concerns the question of equivalence between the Euler–Lagrange equation of a certain functional and periodic Stokes waves on the surface of an infinitely deep irrotational incompressible flow of an ideal fluid under gravity. Of particular concern is Bernoulli’s constant-pressure condition on a free surface.

Cet article concerne la question de l’équivalence entre les solutions de l’équation d’Euler–Lagrange pour une certaine fonctionnelle et les ondes périodiques de Stokes à la surface d’un liquide de profondeur infinie. Une attention particulière est portée sur la condition de Bernoulli qui dit que le pression est atmosphérique le long de la frontière libre.
A comparison of joint stability between anterior cruciate intact and deficient knees: A new canine model of anterior cruciate ligament disruption
Authors: Lopez Mandi J. , Kunz David , Jr Ray Vanderby , Heisey Dennis , Bogdanske John , Markel Mark D.
Published: February 2003

Transection of the canine anterior cruciate ligament (ACL) is a well‐established osteoarthritis (OA) model. This study evaluated a new method of canine ACL disruption as well as canine knee joint laxity and joint capsule (JC) contribution to joint stability at two time points (16 and 26 weeks) after ACL disruption (n = 5/time interval). Ten crossbreed hounds were evaluated with force plate gait analysis and radiographs at intervals up to 34 weeks after monopolar radiofrequency energy (MRFE) treatment of one randomly selected ACL. Each contralateral ACL was sham treated. The MRFE treated ACLs ruptured approximately eight weeks (mean 52.5 days, SEM ± 1.0, range 48–56 days) after treatment. Gait analysis and radiographic changes were consistent with established canine ACL transection models of OA. Anterior‐posterior (AP) translation and medial‐lateral (ML) rotation were measured in each knee at 30°, 60°, and 90° of flexion with and then without JC with loads of 40 N in AP translation and 4 N m in ML rotation. A statistically significant interaction in AP translation included JC by cruciate (P = 0.02), and there was a trend for a cruciate by time (P = 0.07) interaction. Significant interactions in ML rotational testing included the presence of joint capsule (P = 0.0001) and angle by cruciate (P = 0.0012). This study describes a model in which canine ACLs predictably rupture approximately eight weeks after arthroscopic surgery and details the contribution of JC to canine knee stability in both ACL intact and deficient knees. The model presented here avoids the introduction of potential surgical variables at the time of ACL rupture and may contribute to studies of OA pathogenesis and inhibition. This model may also be useful for insight into the pathologic changes that occur in the knee as the ACL undergoes degeneration prior to rupture.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Spinal somatosensory evoked potential evaluation of acute nerve‐root injury associated with pedicle‐screw placement procedures: An experimental study
Authors: Jou I‐Ming , Hsu Che‐Chia , Chern Tai‐Chang , Chen Wen‐Yi , Dau Yuan‐Chang
Published: February 2003

Pedicle screws for spinal fixation risk neural damage because of the proximity between screw and nerve root. We assessed whether spinal somatosensory evoked potential (SSEP) could selectively detect pedicle‐screw‐related acute isolated nerve injury. Because pedicle screws are too large for a rat's spine, we inserted a K‐wire close to the pedicle in 32 rats, intending not to injure the nerve root in eight (controls), and to injure the L4 or L5 root in 24. We used sciatic‐nerve‐elicited SSEP pre‐ and postinsertion. Radiologic, histologic, and postmortem observations confirmed the level and degree of root injury. Sciatic (SFI), tibial (TFI), and peroneal function indices (PFI) were calculated and correlated with changes in potential. Although not specific for injuries to different roots, amplitude reduction immediately postinsertion was significant in the experimental groups. Animals with the offending wire left in place for one hour showed a further non‐significant deterioration of amplitude. Electrophysiologic changes correlated with SFI and histologic findings in all groups. SSEP monitoring provided reliable, useful diagnostic and intraoperative information about the functional integrity of single nerve‐root injury. These findings are clinically relevant to acute nerve‐root injury and pedicle‐screw insertion. If a nerve‐root irritant remains in place, a considerable neurologic deficit will occur.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
The biomechanical response to doses of TGF‐β2 in the healing rabbit medial collateral ligament
Authors: Spindler Kurt P. , Murray Martha M. , Detwiler Kenneth B. , Tarter Jeremy T. , Dawson John M. , Nanney Lillian B. , Davidson Jeffrey M.
Published: February 2003

Ligament injuries result in significant disability in over 100,000 patients each year. Despite current methods of treatment, 13% of patients with medial collateral ligament (MCL) injury develop early signs of arthritis, suggesting an incomplete return of knee stability. The principal hypothesis of this work was that the addition of TGF‐β2 to the healing MCL would accelerate the development of scar strength and stiffness. Forty‐four rabbits were divided evenly into four groups, with each group receiving either 0.1, 1 or 5 μg of TGF‐β2 and the fourth group receiving 1 μg TGF‐β2 and 1 μg of PDGF. Each rabbit underwent bilateral transection of the MCL, with one side having treatment with one of four doses of growth factor and the other side left untreated. All animals were sacrificed at 6 weeks and the structural properties of maximum load at failure, stiffness, and energy absorbed at failure measured. All treatment groups demonstrated an increase in scar mass, but no group had a significant increase in scar load at failure at 6 weeks. The addition of 0.1 μg TGF‐β2 led to a significant increase in scar stiffness. The addition of PDGF had no significant effect on any of the parameters studied. This study suggests the mechanical stiffness, but not the load at failure, of ligament scar can be significantly altered by the administration of TGF‐β2.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Acute changes in the axonal cytoskeleton after mild stretching of the rat brachial plexus
Authors: Kikukawa Kenshi , Fukunaga Kohji , Kato Teiji , Yamaga Makio , Miyamoto Eishichi , Takagi Katsumasa
Published: February 2003

We have developed an animal model to investigate acute changes in the axonal cytoskeleton caused by a mild stretching of the peripheral nerve in the upper limbs of rats. Rat forelimbs were continuously stretched at 2 N for 1 h. Thereafter, a part of the brachial plexus and median nerve were harvested and processed for electron microscopic analysis. The total number of microtubules in the brachial plexus decreased to 55% of that of the control animals (p<0.05) without change in the number of neurofilaments. No significant changes in microtubules or neurofilaments were observed in the median nerve. By Western blotting analysis, the amount of tau protein in the stretch group significantly decreased in the brachial plexus but not in the median nerve. However, no significant changes in the amount of tubulin protein were observed in either the brachial plexus or median nerve. These results suggest that the microtubules were depolymerized by stretching of the brachial plexus and that the depolymerization may have been mediated by the decrease in the tau protein.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Influence of a standardized closed soft tissue trauma on resistance to local infection. An experimental study in rats
Authors: Kälicke Thomas , Schlegel Urs , Printzen Gert , Schneider Erich , Muhr Gert , Arens Stephan
Published: February 2003

Purpose: The etiology of local posttraumatic infection in the locomotor system depends on the amount, virulence and pathogenicity of the inoculated microorganisms and the local/systemic host damage due to the type and extent of the accident or iatrogenic trauma. The relative effect of these factors remains unclear. In particular, it is still unclear today whether—in presence of microorganisms—soft tissue damage and its pathophysiological consequences lead to infection after soft tissue trauma, or whether the bacterial contamination is the primarily cause for posttraumatic infection. The aim of the project was to gain information on the consequences of a soft tissue injury in terms of resistance to local infection. Since clinical populations are too heterogeneous, the problem was investigated in a standardized, reduced (no surgery or implants) experimental in vivo model.

Method: In female Sprague‐Dawley‐rats with a standardized closed soft tissue trauma to the tibialis anterior muscle (group I: n = 13) or without (group II: n = 13), we compared the incidence of local infection after a pairwise local, percutaneously injected bacterial challenge with various concentrations of Staphylococcus aureus (2 × 104‐2 × 106 colony forming units, CFU). The standardized closed soft tissue trauma was created by application of a specially designed, computer controlled impact device. The contaminated soft tissue and the underlying bone were removed under sterile conditions after five days and quantitatively evaluated for bacterial growths. Infection was defined as positive bacterial growth at the soft tissue and/or bone. A stepwise experimental design with an „up‐and‐down”︁ dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the difference between the infection rates of both groups was performed by two‐sided fisher exact test (p<0.05).

Results: The overall infection rate was 46%. For the group with soft tissue trauma the ID50 was 1.32 × 105 CFU and 1.05 × 106 CFU for the group without soft tissue trauma. The infection rate was 69% (9 of 13 animals) for the group with soft tissue trauma and 23% (3 of 13 animals) for the group without soft tissue trauma. This difference is statistically significant (p = 0.047).

Conclusions: The infection rate after a standardized closed soft tissue injury was significantly higher and the ID50 lower than without soft tissue trauma. Our results demonstrate that in presence of microorganisms it is not primarily the bacterial contamination but rather the soft tissue damage and its pathophysiological consequences resulting in decreased infection resistance that secondarily lead to infection.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Inhibition of tendon cell migration by dexamethasone is correlated with reduced alpha‐smooth muscle actin gene expression: A potential mechanism of delayed tendon healing
Authors: Tsai Wen‐Chung , Tang Fuk‐Tan , Wong May‐Kuen , Pang Jong‐Hwei S.
Published: February 2003

Local corticosteroid injection is commonly used to treat sports‐related tendon injuries. However, isolated cases of tendon rupture following injection suggest that this treatment may impair the healing process. Tendon healing requires the migration of tendon cells to the repair site, followed by the proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of dexamethasone on the migration of tendon cells intrinsic to rat Achilles tendon at concentrations similar to those typically used for local injection treatment.

Furthermore, the existence of a correlation between this effect and the expression of the contractile actin isoform, α‐smooth muscle (SM) actin, which is associated with cell motility, was also examined. Using cultured tendon cells, migration was evaluated by counting the number of initial outgrowths from the tendon explants and by transwell filter migration assay. The distribution and assembly of α‐SM actin were assessed by immunocytochemistry. The mRNA and protein expressions of α‐SM actin were determined by reverse transcription‐polymerase chain reaction (RT‐PCR) and Western blot analysis. Dose‐dependent dexamethasone inhibition was demonstrated for both tendon cells outgrowth from the explants, ex vivo, and migration of tendon cells through the transwell filter, in vitro. Immunocytochemical staining revealed significant decreases in both the amount and assembly of α‐SM actin in cells.

Suppression of mRNA expression and protein level of α‐SM actin was revealed from RT‐PCR and Western blot analyses. In conclusion, dexamethasone inhibits tendon cell migration that is correlated with decreased gene expression of α‐SM actin.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Effects of a cultured autologous chondrocyte‐seeded type II collagen scaffold on the healing of a chondral defect in a canine model
Authors: Lee C. R. , Grodzinsky A. J. , Hsu H.‐P. , Spector M.
Published: February 2003

Using a previously established canine model for repair of articular cartilage defects, this study evaluated the 15‐week healing of chondral defects (i.e., to the tidemark) implanted with an autologous articular chondrocyte‐seeded type II collagen scaffold that had been cultured in vitro for four weeks prior to implantation. The amount and composition of the reparative tissue were compared to results from our prior studies using the same animal model in which the following groups were analyzed: defects implanted with autologous chondrocyte‐seeded collagen scaffolds that had been cultured in vitro for approximately 12 h prior to implantation, defects implanted with autologous chondrocytes alone, and untreated defects. Chondrocytes, isolated from articular cartilage harvested from the left knee joint of six adult canines, were expanded in number in monolayer for three weeks, seeded into porous type II collagen scaffolds, cultured for an additional four weeks in vitro and then implanted into chondral defects in the trochlear groove of the right knee joints. The percentages of specific tissue types filling the defects were evaluated histomorphometrically and certain mechanical properties of the repair tissue were determined. The reparative tissue filled 88 ± 6% (mean ± SEM; range 70–100%) of the cross‐sectional area of the original defect, with hyaline cartilage accounting for 42 ± 10% (range 7–67%) of defect area. These values were greater than those reported previously for untreated defects and defects implanted with a type II collagen scaffold seeded with autologous chondrocytes within 12 h prior to implantation. Most striking, was the decreased amount of fibrous tissue filling the defects in the current study, 5 ± 5% (range 0–26%) as compared to previous treatments. Despite this improvement, indentation testing of the repair tissue formed in this study revealed that the compressive stiffness of the repair tissue was well below (20‐fold lower stiffness) that of native articular cartilage.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
AMPA receptor potentiation by acetylcholinesterase is age‐dependently upregulated at synaptogenesis sites of the rat brain
Authors: Olivera Silvia , Henley Jeremy M. , Rodriguez‐Ithurralde Daniel
Published: February 2003

We have used radioligand binding to synaptic membranes from distinct rat brain regions and quantitative autoradiography to investigate the postnatal evolution of acetylcholinesterase (AChE)‐evoked up‐regulation of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptors in CNS areas undergoing synaptogenesis. Incubation of synaptosomal membranes or brain sections with purified AChE caused a developmentally modulated enhancement in the binding of [3H]‐(S)–AMPA and the specific AMPA receptor ligand [3H]‐(S)‐5–fluorowillardiine, but did not modify binding to kainate neitherN‐methyl‐d‐aspartate receptors. In all postnatal ages investigated (4, 7, 14, 20, 27, 40 days‐old and adult rats), AChE effect on binding was concentration‐dependent and blocked by propidium, BW 284c51, diisopropylfluorophosphonate and eserine, therefore requiring indemnity of both peripheral and active sites of the enzyme. AChE‐mediated enhancement of [3H]–fluorowillardiine binding was measurable in all major CNS areas, but displayed remarkable anatomical selectivity and developmental regulation. Autoradiograph densitometry exhibited distinct temporal profiles and peaks of treated/control binding ratios for different cortices, cortical layers, and nuclei. Within the parietal, occipital and temporal neocortices, hippocampal CA1 field and cerebellum, AChE‐potentiated binding ratios peaked in chronological correspondence with synaptogenesis periods of the respective AMPA‐receptor containing targets. This modulation of AMPA receptors by AChE is a molecular mechanism able to transduce localized neural activity into durable modifications of synaptic molecular structure and function. It might also contribute to AChE‐mediated neurotoxicity, as postulated in Alzheimer's disease and other CNS disorders.
Lead‐induced developmental perturbations in hippocampal Sp1 DNA‐binding are prevented by zinc supplementation: in vivo evidence for Pb and Zn competition
Authors: Basha Md.Riyaz , Wei Wei , Brydie Michelle , Razmiafshari M. , Zawia N.H.
Published: February 2003

Zinc finger protein (ZFP) transcription factors are essential for regulation of gene expression in the developing brain. We previously reported that Pb exposure perturbed the DNA‐binding of ZFP such as Sp1 and Egr‐1 in the cerebellum, which play critical role in CNS development. In this study, we focused on hippocampal Sp1 DNA‐binding and mRNA expression in neonatal Pb‐exposed animals. The expression pattern of an Sp1 target (NMDAR1) gene was also monitored. To study in vivo and in vitro competition between Pb and Zn, we supplemented animals with Zn, and examined the effects of both metals on hippocampal Sp1 DNA‐binding and the DNA‐binding of a recombinant Sp1 protein (rhSp1). Tissue metal analysis revealed that only the disposition of Pb in the brain but not its distribution in the blood was influenced by the presence of Zn. The developmental profile of Sp1 DNA‐binding exhibited a peak on PND 15 which subsequently declined to adult levels. Consistent with earlier studies, Pb exposure produced premature peaks of Sp1 DNA‐binding on PND 5 which later returned to adult levels. The basal and Pb‐induced developmental patterns of Sp1 mRNA departed from its DNA‐binding profiles. However, the expression patterns of the NMDAR1 gene were relative to Sp1 DNA‐binding. Supplementation with zinc provided a protective effect on Pb‐induced changes in Sp1 DNA‐binding. Moreover, Pb and Zn directly interfered with the DNA‐binding of rhSp1 in vitro. These data suggest that Pb and Zn can compete both in vivo and in vitro at the zinc finger domain of Sp1 with a consequential effect on Sp1 DNA‐binding, subsequent gene expression and brain development.
Localization of urokinase‐type plasminogen activator, its receptor, and inhibitors in mouse forebrain during postnatal development
Authors: Del Bigio Marc R. , Hosain Shahid , Altumbabic Mensura
Published: February 2003

Proteolytic enzymes are postulated to play a role in cell migration and synapse organization during brain development. Among these, urokinase‐type plasminogen activator (uPA) has been studied in neoplastic and cultured brain cells extensively. We hypothesized that uPA, its receptor, and its inhibitors would be expressed in immature glial and neuronal cells in postnatal mouse forebrain. Immature cortical neurons were immunoreactive for uPA, its receptor, and its substrate plasminogen peaking at the end of postnatal week two, consistent with the postulated role in synaptogenesis. Immunoreactivity for uPA receptor was also observed on astroglial cells in vitro. Neither it nor uPA were convincingly detected in subventricular zone precursor cells, immature white matter or pre‐labeled immature cells that had been transplanted into brain. Plasminogen activator inhibitor type 1 immunoreactivity was observed on endothelia up to 12 days age, and type 2 was observed to surround immature cells.

We conclude, based on the spatial and temporal distribution of immunoreactivity, that uPA and its receptor may be relatively more important for synaptogenesis, remodeling, and reactive processes than for cell migration in developing mouse brain.
Repeated seizure‐associated long‐lasting changes of N‐methyl‐d‐aspartate receptor properties in the developing rat brain
Authors: Doriat Jean‐François , Koziel Violette , Humbert Anne‐Claude , Daval Jean‐Luc
Published: February 2003

Glutamate NMDA receptor has been implicated in brain developmental processes as well as in excitotoxicity and seizure mediation. A previous study has shown that an acute episode of seizures for 30 min in rats altered NMDA receptor characteristics, mainly in the very immature animal. In order to assess whether receptor modifications may also account for long‐lasting cerebral disabilities, medium‐ and long‐term consequences of repeated seizures in developing rats on brain NMDA receptor properties were investigated. Seizures were induced once a day for 3 consecutive days, either from postnatal day 5 (P5) to P7 or from P15 to P17. NMDA receptors were then analysed at P15, P25 and P60 (adulthood) by measuring specific binding of [3H]MK‐801 on brain membrane preparations. In addition, allosteric modulation of NMDA receptors by exogenous glutamate and glycine was investigated. Seizures from P5 to P7 led to a 22% increase in the density of [3H]MK‐801 binding sites measured at P15, but did not affect NMDA receptor density or affinity at P25 or P60. P15–P17 seizures led to a 21% decrease in the density of binding sites and to a 33% decrease in receptor dissociation constant at P25, while they were without effect at P60. Moreover, P5–P7 and P15–P17 seizures were both associated with a suppression of the glutamate/glycine‐induced receptor activation at P60. These modifications might account for long‐term alterations in cerebral excitability or plasticity after early convulsive disorders, with regards to altered cognitive capacities, epileptogenesis and brain susceptibility to recurrent seizures.
Fluoride‐induced depletion of polyphosphoinositides in rat brain cortical slices: a rationale for the inhibitory effects on phospholipase C
Authors: Sarri Elisabet , Claro Enrique
Published: February 2003

Fluoride, which is used commonly as a pharmacological tool to activate phosphoinositide‐phospholipase C coupled to the heterotrymeric Gq/11 proteins, inhibited the phosphorylation of phosphatidylinositol (PtdIns) to polyphosphoinositides (PtdIns4P and PtdIns4,5P2) in membranes from rat brain cortex. Fluoride enhanced basal production of 3H‐inositol phosphates in membranes prepared from brain cortical slices that had been prelabeled with [3H]inositol, but inhibited the stimulation elicited by carbachol in the presence of GTPγS. However in both cases fluoride depleted [3H]PtdIns4P content by 95%. The inhibitory effects of fluoride on the release of 3H‐inositol phosphates in slices were not apparent in a pulse [3H]inositol‐labeling strategy, but became dramatic in a continuous labeling protocol, particularly at long incubation times. Prelabeling slices with [3H]inositol in the presence of fluoride precluded polyphosphoinositide labeling, and eliminated phospholipase C responsiveness to carbachol under normal or depolarizing conditions, and to the calcium ionophore ionomycin. The lack of response of 3H‐polyphosphoinositide‐depleted slices to phospholipase C stimuli was not due to fluoride poisoning, unaccesibility of the [3H]inositol label to phospholipase C or desensitization of Gq/11, as the effect of carbachol and GTPγS was restored, in the presence of ATP, in membranes prepared from slices that had been labeled in the presence of fluoride. In conclusion, our data show that fluoride, at a concentration similar to that used to stimulate directly Gq/11‐coupled phospholipase C, effectively blocks the synthesis of phospholipase C substrates from PtdIns.
Cellular localization of estrogen receptors on neurones in various regions of cultured rat CNS: coexistence with cholinergic and galanin receptors
Authors: Hösli Elisabeth , Hösli L.
Published: February 2003

Autoradiographic studies have shown that many neurones in explant cultures of rat neocortex, hippocampus, preoptic area and spinal cord express binding sites for [3H]‐estradiol which are distributed over the cell bodies and primary processes. By means of immunohistochemistry, it was observed that neurones were labelled by monoclonal antibodies against estrogen α‐receptors and a polyclonal antibody against estrogen β‐receptors. Immunoreactivity was distributed over the soma and primary processes of the cells, the nuclei being more intensely stained. Double‐immunostaining revealed a colocalization of estrogen α‐ and β‐receptors on approximately half of the neurones in cultures from neocortex and hippocampus whereas in cultures from preoptic area and spinal cord only few cells were double‐stained. On many neurones, a coexistence of estrogen receptors and cholinergic muscarinic or nicotinic sites was found. Furthermore, combined autoradiographic and immunohistochemical studies have shown a colocalization of receptors for estrogen and the neuropeptide [125I]‐galanin. The coexistence of estrogen and cholinergic sites as well as of estrogen and galanin receptors on the same neurones are discussed with respect to neurodegenerative events such as Alzheimer's disease.
Plasticity of 5‐hydroxytryptamine1B receptors during postnatal development in the rat visual cortex
Authors: Ruiz Gloria , Bancila Mircea , Valenzuela Mauricio , Daval Geneviève , Hossein Kia Kami , Vergé Daniel
Published: February 2003

The distribution of 5‐hydroxytryptamine1A and 5‐hydroxytryptamine1B receptors in the visual cortex was studied by quantitative autoradiography during postnatal development. Overall, receptor densities increased throughout development, but exhibited regional rearrangements, particularly in the case of 5‐hydroxytryptamine1B receptors. Neonatal treatment with 5,7‐dihydroxytryptamine, which causes selective degeneration of serotoninergic neurons, had no effect on the density of 5‐hydroxytryptamine1A receptors in the visual cortex. However, a transient increase in 5‐hydroxytryptamine1B at postnatal days 10–12 was observed after this treatment, suggesting a regulation of postsynaptic receptors. Neonatal enucleation resulted in a marked increase in 5‐hydroxytryptamine1B binding sites in all layers of the visual cortex by P16, whereas it had no effect upon 5‐hydroxytryptamine1A binding sites.

These results show that both receptor subtypes do not exhibit striking transient features in the visual cortex during postnatal development, but rather undergo discrete reorganizations. 5‐Hydroxytryptamine1B receptors show changes in density after either neonatal degeneration of serotoninergic neurons or enucleation, indicating that the serotoninergic system involving this receptor subtype can exhibit some postnatal plasticity in the visual cortex.
Expression of synaptic proteins in the developing rat cerebellum following ionizing radiation
Authors: Goutan E. , Martı́ E. , Ferrer I.
Published: February 2003

Various proteins regulating neurotransmission release and synaptic vesicle exocytosis have been implicated in axonal elongation and synaptic maturation. In the present study, immunohistochemistry to the presynaptic membrane proteins syntaxin‐I and synaptosomal‐associated protein of 25 kDa (SNAP‐25), synaptic vesicle‐associated proteins synaptophysin and synapsin‐I and the neuronal maturation and axonal growth‐related protein GAP‐43, has been carried out in the normal developing cerebellum and following a single dose of ionizing radiation (2 Gy gamma‐rays) at postnatal day 1. Our aim has been to learn about the morphological and possible functional modalities that occur during the progression of neuronal connectivity in normal and abnormal development. Expression of all these proteins is associated with the arrival of afferents in the subcortical white matter and with the maturation of the internal granule cell layer and molecular layer during normal development. In addition, SNAP‐25 and GAP‐43 are strongly expressed in granule cells of the external granule cell layer, thus suggesting that these proteins are involved in cell elongation of granule cells. Apoptosis appears at 3 h and peaks at 6 h following ionizing radiation. Radiation‐induced apoptosis in the external granule cell layer produces a transient decrease in the expression of SNAP‐25 and GAP‐43 in the external granule cell layer. The external granule cell layer recovers at 48 h and external granule cells of proliferating cells also express SNAP‐25 and GAP‐43, thus indicating that proliferating cells in this layer are equipped with proteins involved in cell elongation. Furthermore, expression of synaptophysin, synapsin‐I, syntaxin‐I and SNAP‐25 is the same in the cerebellum of irradiated and normal rats from this time to adulthood (3 months). These results point to the likelihood that recovery of the cerebellar cortex occurs following a single exposure of ionizing radiation during postnatal development.
The effect of chelerythrine on depolarization‐induced force responses in skinned fast skeletal muscle fibres of the rat
Authors: Han Renzhi , Bakker Anthony J
Published: February 2003

We examined the effect of the protein kinase C (PKC) inhibitor chelerythrine on depolarization‐induced force responses (DIFRs) and sarcoplasmic reticulum (SR) function in single, mechanically skinned skeletal muscle fibres of the rat.

In this study, the DIFRs in the skinned fibres normally underwent an irreversible loss of excitation‐contraction coupling (ECC) after 10–15 responses. Chelerythrine (12 μM) was shown to restore ECC in these fibres. Restored force responses were similar in peak (control 50.8±6.4%, chelerythrine 56.9±12.4% of maximum force, P=0.42, n=21), but significantly broadened compared to initial control responses (full‐width at half maximum, control; 3.7±0.3 s, chelerythrine; 13.3±1.1 s, P<0.001). Early exposure to chelerythrine prevented run‐down of DIFRs. Chelerythrine also induced spontaneous force responses in some fibres.

The PKC inhibitors calphostin C and staurosporine did not restore ECC, and the PKC activator phorbol 12‐myristate 13‐acetate did not promote loss of ECC in the skinned fibres.

Chelerythrine significantly increased SR Ca2+ loading by 8.4±1.7% (P=0.02, n=9) and SR Ca2+ release by at least 14.1±2.7% (P=0.004, n=11) in the skinned fibres.

Chelerythrine had no significant effect on maximum force production or the [Ca2+] producing half maximal activation of the myofilaments. However, chelerythrine did have a small effect on the slope of the force‐Ca2+ relationship (P=0.02, n=10).

Chelerythrine reverses the use‐dependent loss of excitation‐contraction coupling in skinend skeletal muscle fibres by a PKC independent pathway. Chelerythrine may be an important pharmacological probe for examining the mechanisms of contraction‐induced muscle injury.

British Journal of Pharmacology (2003) 138, 417–426. doi:10.1038/sj.bjp.0705035
Attenuation of acute and chronic effects of morphine by the imidazoline receptor ligand 2‐(2‐benzofuranyl)‐2‐imidazoline in rat locus coeruleus neurons
Authors: Ruiz‐Durántez Eduardo , Torrecilla María , Pineda Joseba , Ugedo Luisa
Published: February 2003

The aim of this study was to determine if 2‐(2‐benzofuranyl)‐2‐imidazoline (2‐BFI) interacts with the opioid system in the rat locus coeruleus, using single‐unit extracellular recordings.

In morphine‐dependent rats, acute administration of the selective imidazoline receptor ligands 2‐BFI (10 and 40 mg kg−1, i.p. and 100 μg, i.c.v.) or valldemossine (10 mg kg−1, i.p.) did not modify the naloxone‐induced hyperactivity of locus coeruleus neurons compared with that observed in the morphine‐dependent control group.

After chronic administration of 2‐BFI (10 mg kg−1, i.p., three times daily, for 5 days) and morphine, naloxone‐induced hyperactivity and tolerance to morphine were attenuated. This effect was not observed when a lower dose of 2‐BFI (1 mg kg−1, i.p.) or valldemossine (10 mg kg−1, i.p.) were used.

Acute administration of 2‐BFI (10 and 40 mg kg−1, i.p. and 100 μg, i.c.v.) but not valldemossine (40 mg kg−1, i.p.) diminished the potency of morphine to inhibit locus coeruleus neuron activity in vivo (ED50 values increased by 2.3, 2.9; and 3.1 fold respectively). Similarly, the potency of Met5‐enkephalin to inhibit locus coeruleus neurons was decreased when 2‐BFI (100 μM) was applied to rat brain slices (EC50 increased by 5.6; P<0.05).

The present data demonstrate that there is an interaction between 2‐BFI and the opioid system in the locus coeruleus. This interaction leads to an attenuation of both the hyperactivity of locus coeruleus neurons during opiate withdrawal and the development of tolerance to morphine when 2‐BFI is chronically administered. These results suggest that imidazoline drugs may prove to be useful agents for the management of opioid dependence and tolerance.

British Journal of Pharmacology (2003) 138, 494–500. doi:10.1038/sj.bjp.0705052
RSD931, a novel anti‐tussive agent acting on airway sensory nerves
Authors: Adcock J J , Douglas G J , Garabette M , Gascoigne M , Beatch G , Walker M , Page C P
Published: February 2003

The anti‐tussive effects, of the local anaesthetic, lidocaine and carcainium chloride (RSD931) have been investigated in guinea‐pigs and rabbits.

Pre‐treatment of guinea‐pigs with aerosols of lidocaine or RSD931 at 0.1, 1.0 and 10 mg ml−1 reduced the number of citric acid‐induced coughs by 9.3, 32.6 and 40.9% (P>0.05) for lidocaine and by 25.3% (P>0.05), 40.4% (P>0.05) and 97.6% (P<0.01) for RSD931, respectively and increased the latency to onset of cough at 10.0 mg ml−1 only. In addition, RSD931 at 10 mg ml−1 reduced citric acid‐evoked cough responses in rabbits (with prior exposure to ozone at 3 p.p.m. for 1 h) from 22.1±5.1 to 2.7±0.9 coughs (P<0.01).

Acute pre‐treatment of guinea‐pigs with aerosols of lidocaine or RSD931 at 10.0 and 30.0 mg ml−1 reduced the number of capsaicin‐evoked coughs by 42.2 and 10.3% (P>0.05) (lidocaine) and by 25% (P>0.05) and 76.9% (P<0.01) (RSD931), respectively. Lidocaine had little effect on the latency of cough onset at either 10.0 or 30.0 mg ml−1, however, RSD at 30.0 mg ml−1 significantly (P<0.05) prolonged the latency of cough onset.

RSD931 (10.0 mg ml−1) significantly (P<0.05–<0.01) reduced the spontaneous and histamine‐evoked discharges in Aδ‐fibres originating from airway, rapidly adapting stretch receptors (RARs) without affecting histamine‐evoked bronchoconstriction. Lidocaine at 10.0 mg ml−1 also significantly (P<0.05) inhibited the spontaneous and histamine‐induced discharges of RARs without affecting histamine‐evoked bronchoconstriction.

Aerosols of RSD931 (10.0 mg ml−1) caused a transient, but significant (P<0.05), activation of pulmonary C‐fibre endings 2.5 min after administration started. RSD931 had no significant (P>0.05) effects on discharges in bronchial C‐fibres originating from bronchial C‐fibre endings, capsaicin‐evoked discharges of either pulmonary or bronchial C‐fibre endings or on capsaicin‐evoked bronchoconstriction. In contrast, lidocaine (10.0 mg ml−1) significantly (P<0.05) inhibited spontaneous and capsaicin‐induced discharges in both pulmonary and bronchial C‐fibres respectively. Lidocaine also significantly (P<0.05) reduced capsaicin‐evoked bronchoconstriction.

These studies suggest that the anti‐tussive actions of RSD931 are mediated via inhibition of discharges in Aδ‐fibres originating from airway RARs. The mechanism of action of RSD931 is distinct from that of the local anaesthetic lidocaine and RSD931 may represent a novel class of anti‐tussive agent.

British Journal of Pharmacology (2003) 138, 407–416. doi:10.1038/sj.bjp.0705056
A unique phenotype of 5‐HT2C, agonist‐induced GTPγ35S binding, transferable to 5‐HT2A and 5‐HT2B, upon swapping intracellular regions
Authors: Alberts Glen L , Chio Christopher L , Im Wha Bin , Slightom Jerry L
Published: February 2003

The human 5‐HT2C receptor, when expressed heterologously in various mammalian cell lines (HEK293, SH‐EP and NIH‐3T3) at various receptor densities (6 to 45 pmol mg−1 protein), mediates robust agonist‐induced GTPγ35S binding from coupling to Gi subtypes of G proteins, in addition to Gq/11. Such a phenotype, however, was not seen with the human 5‐HT2A and 5‐HT2B receptors, indicating their common pathway with 5‐HT2C limited to Gq/11, not including Gi.

Because intracellular regions are largely responsible for signalling pathways, we prepared the chimeras of the 5‐HT2A and 5‐HT2B receptors where the second and third intracellular loops, and the C‐terminal region were replaced with the 5‐HT2C counterparts.

The chimeras showed robust agonist‐induced GTPγ35S binding. Relative intrinsic efficacies of agonists from the GTPγ35S binding were nearly identical to the reported values for their parent receptors as measured with Ca2+ or [3H]‐inositol phosphate accumulation. Also the chimeras displayed the same ligand‐binding properties as the parent receptors.

We conclude that the phenotype of agonist‐induced GTPγ35S binding is unique to 5‐HT2C among the 5‐HT2 receptor family, and is transferable to 5‐HT2A and 5‐HT2B, upon swapping intracellular sequences, without altering their receptor pharmacology.

British Journal of Pharmacology (2003) 138, 427–434. doi:10.1038/sj.bjp.0705058
Contribution of Na+‐Ca2+ exchanger to pinacidil‐induced relaxation in the rat mesenteric artery
Authors: Tsang Suk Ying , Yao Xiaoqiang , Wong Chi Ming , Au Chak Leung , Chen Zhen Yu , Huang Yu
Published: February 2003

Pinacidil relaxes blood vessels through opening the KATP channels with a resultant membrane hyperpolarization and inhibition of Ca2+ influx. The aim of this study was to examine the mechanisms thereby pinacidil induces K+ channel‐independent relaxation in isolated endothelium‐denuded rat mesenteric artery.

Pinacidil‐induced relaxation was inhibited by glibenclamide (1–10 μM) in phenylephrine‐preconstricted rings, but was unaffected by glibenclamide after inhibition of K+ channels and VGCCs. Pinacidil‐induced K+ channel‐independent relaxation remained unchanged after treatment with cyclopiazonic acid (10 μM), thapsigargin (1 μM), ouabain (100 μM), propranolol (10 μM), Rp‐cAMPS triethylamine (30 μM), L‐NNA (100 μM), or ODQ (10 μM).

Pinacidil induced more relaxant effect in the presence of nifedipine than in the presence of 60 mM K+ plus nifedipine. Pretreatment with Na+‐Ca2+ exchanger inhibitors, nickel (30–300 μM) or benzamil (20 μM) attenuated pinacidil‐induced relaxation in normal or in nifedipine‐containing solution. Pinacidil (1 μM) produced less relaxant effect with decreasing extracellular Na+ concentration. Na+‐free condition abolished the inhibitory effect of benzamil. Both nickel and benzamil inhibited pinacidil‐induced relaxation in the presence of glibenclamide (10 μM). Nickel (300 μM) did not affect the relaxant response to sodium nitroprusside.

Pinacidil relaxed the rings preconstricted by active phorbol and U46619 with similar potency.

The present results indicate that stimulation of the forward mode Na+‐Ca2+ exchange pathway is in part responsible for pinacidil‐induced K+ channel‐independent vasorelaxation. Pinacidil also induces K+ channel‐dependent but VGCCs‐independent relaxation. The PKC‐mediated cellular pathway may be a target site for pinacidil only in higher concentrations.

British Journal of Pharmacology (2003) 138, 453–460. doi:10.1038/sj.bjp.0705062
The preferential β3‐adrenoceptor agonist BRL 37344 increases force viaβ1‐/β2‐adrenoceptors and induces endothelial nitric oxide synthase viaβ3‐adrenoceptors in human atrial myocardium
Authors: Pott C , Brixius K , Bundkirchen A , Bölck B , Bloch W , Steinritz D , Mehlhorn U , Schwinger R H G
Published: February 2003

The present study investigated the effects of the preferential β3‐AR agonist BRL 37344 (BRL) on force of contraction (FOC), Ca2+‐transient and eNOS‐activity in human right atrial myocardium.

BRL concentration‐dependently caused an increase in FOC that was paralleled by an increase in Ca2+‐transient and a shortening of time to half peak relaxation (T0.5T). These effects were abolished in the presence of propranolol (0.3 μM).

BRL acted as a competitive antagonist towards isoprenaline and in binding experiments it was shown to have a distinct affinity towards β1/2‐AR.

In immunohistochemical experiments BRL (10 μM) increased detection of activated eNOS. This effect remained constant in the presence of propranolol (0.3 μM).

BRL increased directly detected NO in DAF‐staining experiments. This increase was significantly smaller in the presence of the NO‐inhibitor L‐NAME.

The inotropic effects of BRL were not changed in the presence of L‐NMA.

These results suggest that the inotropic effects of BRL in human atrium are mediated via β1/2‐AR, whereas the increase of atrial eNOS‐activity is due to β3‐ adrenergic stimulation. This increase in eNOS‐activity did not influence atrial myocardial contractility. In conclusion, this study shows that β3‐adrenergic stimulation is present in human atrium, but may not be functionally as significant as in the left ventricle.

British Journal of Pharmacology (2003) 138, 521–529. doi:10.1038/sj.bjp.0705065
A quantitative structure–function relationship for the Photosystem II reaction center: Supermolecular behavior in natural photosynthesis
Authors: Barter Laura M. C. , Durrant James R. , Klug David R.
Published: February 2003

Light-induced charge separation is the primary photochemical event of photosynthesis. Efficient charge separation in photosynthetic reaction centers requires the balancing of electron and excitation energy transfer processes, and in Photosystem II (PSII), these processes are particularly closely entangled. Calculations that treat the cofactors of the PSII reaction center as a supermolecular complex allow energy and electron transfer reactions to be described in a unified way. This calculational approach is shown to be in good agreement with experimentally observed energy and electron transfer dynamics. This supermolecular view also correctly predicts the effect of changing the redox potentials of cofactors by site-directed mutagenesis, thus providing a unified and quantitative structure–function relationship for the PSII reaction center.