bluuebunny/crossref_metadata_2025 huggingface dataset:
New vehicle based on a microemulsion for topical ocular administration of dexamethasone
Authors: Fialho Sílvia Ligório , Da Silva‐Cunha Armando
Published: December 2004

Aim: Eye drops are the most used dosage form by the ocular route, in spite of their low bioavailability. Due to their properties and numerous advantages, microemulsions are promising systems for topical ocular drug delivery. They can increase water solubility of the drug and enhance drug absorption into the eye. The present study describes the development and characterization of an oil‐in‐water microemulsion containing dexamethasone and the evaluation of its pharmacokinetics in rabbits after topical ocular application.

Methods: The microemulsion was prepared by the titration technique. Its physico‐chemical characteristics and stability were determined. The ocular irritation test and the pharmacokinetics of this system were studied in white rabbits.

Results: The developed system showed an acceptable physico‐chemical behaviour and presented good stability for 3 months. The ocular irritation test used suggested that the microemulsion did not provide significant alteration to eyelids, conjunctiva, cornea and iris. This formulation showed greater penetration of dexamethasone in the anterior segment of the eye and also release of the drug for a longer time when compared with a conventional preparation. The area under the curve obtained for the microemulsion system was more than twofold higher than that of the conventional preparation (P < 0.05).

Conclusions: The microemulsion‐based dexamethasone eye drop is advantageous for ophthalmic use because it is well‐tolerated in the eye and seemed to provide a higher degree of bioavailability. The developed system shows greater penetration in the eye, allowing the possibility of decreasing the number of applications of eye drops per day.
Reduced food anticipatory activity in genetically orexin (hypocretin) neuron‐ablated mice
Authors: Akiyama Masashi , Yuasa Tomoyo , Hayasaka Naomi , Horikawa Kazumasa , Sakurai Takeshi , Shibata Shigenobu
Published: December 2004

Daily restricted feeding (RF) produces an anticipatory locomotor activity rhythm and entrains the peripheral molecular oscillator independently of the central pacemaker located in the suprachiasmatic nucleus (SCN). As orexins (hypocretins) are neuropeptides that coordinate sleep/wake patterns and motivated behaviours, such as food seeking, we studied the involvement of orexin in the food anticipatory activity (FAA) induced by RF. Daily RF shifted the mRNA rhythm of a clock‐controlled gene mDbp in the cerebral cortex and caudate putamen but not in the SCN. Under these experimental conditions, prepro‐orexin mRNA and orexin A immunoreactivity in the lateral hypothalamic area (LHA) did not show daily variation. Fasting increased the number of orexin A‐ir cells, while RF did not. However, RF shifted the peak of Fos expression of the orexin neurons from night to day. Genetic ablation of orexin neurons in orexin/ataxin‐3 transgenic mice severely reduced the formation of FAA under RF conditions. The expression of mNpas2 mRNA, a transcription factor thought to be involved in regulation of the food entrainable oscillator as well as mPer1 and mBmal1 mRNA, was reduced in the forebrain of orexin/ataxin‐3 mice. Based on these results, we suggest that activity of the orexin neuron in the LHA contributes to the promotion and maintenance of FAA.
Caspase signalling in neuropathic and inflammatory pain in the rat
Authors: Joseph Elizabeth K. , Levine Jon D.
Published: December 2004

Whereas small‐fibre sensory neuropathies might ultimately lead to cell death and loss of sensation, they first progress through a phase, which might last for years, characterized by the presence of analgesia‐resistant neuropathic dysesthesias and pain. Much previous research has addressed these two phases as separate phenomena mediated by presumably discrete biochemical mechanisms. We hypothesized that activity in signalling pathways that ultimately lead to apoptosis plays a critical role in the generation of neuropathic pain, before death of sensory neurons becomes apparent. We have tested the hypothesis that activator and effector caspases, defining components of programmed cell death (apoptosis) signalling pathways, also contribute to pain‐related behaviour in animals with small‐fibre peripheral neuropathies and that the death receptor ligand, tumour necrosis factor‐α, and its downstream second messenger, ceramide, also produce pain‐related behaviour via this mechanism. In two models of painful peripheral neuropathy, HIV/AIDS therapy (induced by the nucleoside reverse transcriptase inhibitor, dideoxycytidine), and cancer chemotherapy (induced by vincristine) peripheral neuropathy, and for pain‐related behaviour induced by tumour necrosis factor‐α and its second messenger, ceramide, inhibition of both activator (1, 2, 8 and 9) and effector (3) caspases attenuates neuropathic pain‐related behaviour, although has no effect in streptozotocin‐diabetic neuropathy and control rats. We conclude that during a latent phase, before apoptotic cell death is manifest, the caspase signalling pathway can contribute to pain in small‐fibre peripheral neuropathies, and that inflammatory/immune mediators also activate these pathways. This suggests that these pathways are potential targets for novel pharmacological agents for the treatment of inflammatory as well as neuropathic pain.
Differential activation of MAPK in injured and uninjured DRG neurons following chronic constriction injury of the sciatic nerve in rats
Authors: Obata Koichi , Yamanaka Hiroki , Dai Yi , Mizushima Toshiyuki , Fukuoka Tetsuo , Tokunaga Atsushi , Noguchi Koichi
Published: December 2004

To investigate the intracellular signal transduction pathways involved in the pathophysiological mechanisms of neuropathic pain after partial nerve injury, we examined the activation of extracellular signal‐regulated protein kinase (ERK) and p38 mitogen‐activated protein kinase (MAPK) in the dorsal root ganglion (DRG) in the chronic constriction injury (CCI) model. The CCI induced an increase in the phosphorylation of ERK in predominantly injured medium‐sized and large‐sized DRG neurons and in satellite glial cells. Treatment with the MAPK kinase 1/2 inhibitor, U0126, suppressed CCI‐induced mechanical allodynia and partially reversed the increase in neuropeptide Y (NPY) expression in damaged DRG neurons. In contrast, the CCI induced the activation of p38, mainly in uninjured small‐to‐medium‐diameter DRG neurons and in satellite glial cells. The p38 inhibitor, SB203580, reversed the CCI‐induced heat hyperalgesia and also the increase in brain‐derived neurotrophic factor (BDNF) expression in intact DRG neurons. On the other hand, the nerve growth factor (NGF)‐induced increase in BDNF expression in small‐to‐medium‐diameter neurons was reversed by SB203580, whereas the anti‐NGF‐induced increase in NPY in medium‐sized and large‐sized neurons was partially blocked by U0126. Taken together, our results demonstrate that the activation of ERK and p38 and also the changes in NPY and BDNF expression may occur in different populations of DRG neurons after CCI, partially through alterations in the target‐derived NGF. These changes in injured and intact primary afferents are likely to have a substantial role in pathological states, and MAPK pathways in nociceptors may be potential targets for the development of novel analgesics.
Rt‐PA causes a significant increase in endogenous u‐PA during experimental focal cerebral ischemia
Authors: Burggraf Dorothe , Martens Helge K. , Wunderlich Nathalie , Jäger Gabriele , Hamann Gerhard F.
Published: December 2004

The aim of this study was to investigate the effects of different doses of exogenous recombinant human tissue plasminogen activator (rt‐PA) on the endogenous cerebral plasminogen–plasmin system in focal ischemia in rats. Ischemia was induced using the suture model. Each group of rats (n = 6) received either treatment (0.9, 9 or 18 mg rt‐PA/kg body weight) or saline (control group) at the end of ischemia; a sham‐operated group was added. The activity of the plasminogen activators was measured by casein‐dependent plasminogen zymography. In the cortex urokinase (u‐PA) rose from sham (no ischemia), 91 ± 7% to ischemia, 176 ± 10% (P < 0.005). Increasing rt‐PA doses led to further significant (P < 0.001) cortical u‐PA activation which was maximal at 18 mg: 249 ± 13%. An extreme increase in the u‐PA activity was observed in the basal ganglia to 1019 ± 22% (P < 0.001). This increase was further aggravated by higher rt‐PA doses (18 mg, 1236 ± 15%; P < 0.001). The t‐PA level did not change I3R24 during (3 h ischemia followed by reperfusion for 24 h); however, during low and moderate doses of rt‐PA, endogenous t‐PA was reduced. In conclusion, while ischemia leads to a significant increase in u‐PA, mainly in the basal ganglia, t‐PA is not altered. Increasing doses of rt‐PA lead to a further elevation of u‐PA. Thus, u‐PA seems to play a major role in the endogenous plasminogen activator system following focal cerebral ischemia.
GABA‐immunoreactive starburst amacrine cells in pigmented and albino rats
Authors: Blaszczyk W. M. , Telkes I. , Distler C.
Published: December 2004

In this study we tested whether the critical anatomical substrate for retinal direction selectivity is altered in albino mammals. We used dual immunostaining for GABA and choline acetyltransferase and quantitatively analyzed the number of double‐labelled starburst amacrine cells in wild‐type and albino rats. In albino rats, the percentage of ON‐amacrine cells with high GABA content was significantly lower than in pigmented animals. OFF‐amacrines did not significantly differ between the two rat strains. Thus, the decreased GABA content in ON‐amacrine cells could reflect an altered neuronal substrate for retinal direction selectivity. These results are discussed in relation to the optokinetic deficits described in albino mammals.
Effects of ventral hippocampal lesion on thermal and mechanical nociception in neonates and adult rats
Authors: Al Amin Hassen A. , Atweh Samir F. , Jabbur Suhayl J. , Saadé Nayef E.
Published: December 2004

The proper maturation of the hippocampus is essential for the development of different behaviours, including memory, pain responses and avoidance. The mechanisms involved in the neurodevelopment of nociception have also been implicated in several neuropsychiatric disorders. The neonatal lesion of the ventral hippocampus (VH) in rats, an animal model of schizophrenia, can be utilized to study the developmental neurobiology of animal behaviour. We examined the nociceptive responses in this animal model at different stages of development. Rat pups were lesioned at postnatal day 7 by injecting ibotenic acid into the VH bilaterally, and then tested for thermal and mechanical nociception at the age of 35, 65 and 180 days. The nociceptive tests used were the hot plate (HP), paw pressure (PP) and tail flick (TF) tests. Another group of adult rats had the same lesion in the VH and then underwent the same tests at 28, 56 and 168 days post‐lesions. When compared with sham controls, the rats with neonatal VH lesion showed decreased latency for the HP and PP tests only after puberty. The TF test showed significant increase in latency for both groups at age 65 and 180 days. The adult rats with VH lesion showed no major changes over all periods of testing. These results suggest that early lesion of VH can alter the development of the neural mechanisms involved in the processing of thermal and mechanical nociception.
Fez1 is layer‐specifically expressed in the adult mouse neocortex
Authors: Inoue Kiyoshi , Terashima Toshio , Nishikawa Toru , Takumi Toru
Published: December 2004

The mammalian cerebral neocortex occupies the largest area of the cerebral cortex and is cytoarchitectually composed of six layers (I–VI). Recent molecular analysis has begun to reveal the existence of various developmental programs, including the genetic regulation of arealization of the neocortex. Although an increasing number of molecular determinants of the developmental stages of the neocortex have been identified, no genes specifically expressed in the adult neocortex have been identified to date. By global screening using microarrays, combined with systematic in situ hybridization, we identified a zinc‐finger type transcription factor, Fez1, which is expressed predominantly in the mouse adult neocortex. No other genes in the neocortex have been shown to date to have their expression with such high specificity. Using two‐color in situ hybridization, we show that Fez1 is mainly expressed in cortical layers V and VI, not in γ‐aminobutyric acid neurons but in pyramidal neurons, the projection neurons of the cerebral cortex. Immunohistochemistry also shows that Fez1 is expressed in deep layers of the neocortex. Fez1 will be invaluable not only for the molecular understanding of corticogenesis but also for understanding the physiological functions of the adult neocortex, as well as for the use of its promoter in gene‐manipulated animals and in conditional expression systems.
Benefit of valproic acid in suppressing disease progression of ALS model mice
Authors: Sugai Fuminobu , Yamamoto Yoichi , Miyaguchi Katsuyuki , Zhou Zhiwei , Sumi Hisae , Hamasaki Toshimitsu , Goto Masashi , Sakoda Saburo
Published: December 2004

Valproic acid (VPA) has long been used as an antiepileptic drug and recently as a mood stabilizer, and evidence is increasing that VPA exerts neuroprotective effects through changes in a variety of intracellular signalling pathways including upregulation of Bcl‐2 protein with an antiapoptotic property and inhibiting glycogen synthase kinase 3‐β, which is considered to promote cell survival. Although the neuroprotective effects of VPA have been demonstrated in a murine model of human immunodeficiency virus‐1 encephalitis, there have been no reports on the effect of VPA in chronic progressing neurodegenerative disease models including amyotrophic lateral sclerosis (ALS). ALS is a devastating disease selectively affecting motoneurons, and its disease model mice bear a close resemblance to ALS symptomatically and pathologically. First, we used an organotypic slice culture using mouse spinal cord, and showed that VPA protected spinal motoneurons against death from glutamate toxicity in vitro. Then, we treated ALS model mice with VPA at the dose effective level for epileptic model mice after 45 days of age (pre‐onset treatment) or the day of the disease onset (post‐onset treatment). We found a significant prolongation of the disease duration in ALS model mice in both methods of treatment. Considering the long usage of VPA for epileptic patients with good tolerance and safety, these data strongly support the clinical application of VPA for ALS treatment.
Signaling complex formation of phospholipase Cβ4 with metabotropic glutamate receptor type 1α and 1,4,5‐trisphosphate receptor at the perisynapse and endoplasmic reticulum in the mouse brain
Authors: Nakamura Michiko , Sato Kazunori , Fukaya Masahiro , Araishi Kenji , Aiba Atsu , Kano Masanobu , Watanabe Masahiko
Published: December 2004

Upon activation of cell surface receptors coupled to the Gq subclass of G proteins, phospholipase C (PLC) β hydrolyses membrane phospholipid to yield a pair of second messengers, inositol 1,4,5‐trisphosphate (IP3) and 1,2‐diacylglycerol. PLCβ4 has been characterized as the isoform enriched in cerebellar Purkinje cells (PCs) and the retina and involved in motor and visual functions. Here we examined cellular and subcellular distributions of PLCβ4 in adult mouse brains. Immunohistochemistry showed that high levels of PLCβ4 were detected in the somatodendritic domain of neuronal populations expressing the metabotropic glutamate receptor (mGluR) type 1α, including olfactory periglomerular cells, neurons in the bed nucleus anterior commissure, thalamus, substantia nigra, inferior olive, and unipolar brush cells and PCs in the cerebellum. Low to moderate levels were detected in many other mGluR1α‐positive neurons and in a few mGluR1α‐negative neurons. In PCs, immunogold electron microscopy localized PLCβ4 to the perisynapse, at which mGluR1α is concentrated, and to the smooth endoplasmic reticulum in dendrites and spines, an intracellular Ca2+ store gated by IP3 receptors. In the cerebellum, immunoblot demonstrated its concentrated distribution in the post‐synaptic density and microsomal fractions, where mGluR1α and type 1 IP3 receptor were also greatly enriched. Furthermore, PLCβ4 formed coimmunoprecipitable complexes with mGluR1α, type 1 IP3 receptor and Homer 1. These results suggest that PLCβ4 is preferentially localized in the perisynapse and smooth endoplasmic reticulum as a component of the physically linked phosphoinositide signaling complex. This close molecular relationship might provide PLCβ4 with a high‐fidelity effector function to mediate various neuronal responses under physiological and pathophysiological conditions.
Extensive exercise is not harmful in amyotrophic lateral sclerosis
Authors: Liebetanz David , Hagemann Katrin , Von Lewinski Friederike , Kahler Elke , Paulus Walter
Published: December 2004

Whether physical activity increases risk or promotes progression of motor neurone degeneration in amyotrophic lateral sclerosis (ALS) is still debated. Current pathophysiological hypotheses include excitotoxicity, oxidative stress and increased calcium loads as causes of selective degeneration of vulnerable motor neurones. Vigorous exercise might amplify these factors by increasing firing rates at motor neurones. To test this hypothesis, we constrained a transgenic mouse model of ALS overexpressing the mutant human form of the Cu/Zn superoxide dismutase‐1 (SOD‐1) to a lifetime exercise on motor‐driven running wheels for 10 h daily (active group, n = 12). Onset and progression of disease were assessed by grip strength, stride length and tight rope test. Data were compared with SOD‐1 mice placed in running wheels set to slow speed (sedentary group, n = 13). Untreated SOD‐1 mice were an additional control group (n = 12). We found no differences in disease onset, which was determined by a change‐point analysis using an iterative fitting of segmented linear regression models, or in disease progression. However, the running group showed a non‐significant 6‐day improvement in survival (133.7 ± 3.2 days) compared with the sedentary group (127.2 ± 3.2 days) and a 4‐day improvement compared with the control group (129.1 ± 2.5 days). We demonstrate that a lifetime of vigorous exercise does not promote onset or progression of motor degeneration in SOD‐1‐mediated ALS. Moreover, the results suggest that the level of excitatory input and calcium turnover at motor neurones, both of which should be increased by running activity, do not interfere with the pathophysiology of SOD‐1‐mediated ALS.
Homophilic interactions of chick neurofascin in trans are important for neurite induction
Authors: Pruss Thomas , Niere Marc , Kranz Eva Ursula , Volkmer Hansjürgen
Published: December 2004

Neurofascin is a member of the immunoglobulin superfamily involved in axon extension and fasciculation. Here we apply adenoviral short hairpin RNA (shRNA) expression in primary neurons, PC12–NIH/3T3 co‐cultures in combination with Luminex® assays, to demonstrate homophilic interactions of neurofascin for neurite outgrowth. An adenoviral vector was constructed for the expression of shRNA in primary tectal cells that inhibits gene expression similar to short interfering RNA. We demonstrate that after shRNA‐mediated knockdown neuronal neurofascin expression is important for neurite outgrowth on a neurofascin substrate. Neurite outgrowth assays reveal that neurite formation of PC12 cells is increased when neurofascin is overexpressed on both outgrowing PC12 cells and substrate NIH/3T3 cells, suggesting that neurofascin expression is also sufficient for neurite induction. Luminex technology for the analysis of protein–protein interactions showed homophilic binding of neurofascin to itself.
Progressive abnormalities in skeletal muscle and neuromuscular junctions of transgenic mice expressing the Huntington's disease mutation
Authors: Ribchester Richard R. , Thomson Derek , Wood Nigel I. , Hinks Tim , Gillingwater Thomas H. , Wishart Thomas M. , Court Felipe A. , Morton A. Jennifer
Published: December 2004

Huntington's disease (HD) is a neurodegenerative disorder with complex symptoms dominated by progressive motor dysfunction. Skeletal muscle atrophy is common in HD patients. Because the HD mutation is expressed in skeletal muscle as well as brain, we wondered whether the muscle changes arise from primary pathology. We used R6/2 transgenic mice for our studies. Unlike denervation atrophy, skeletal muscle atrophy in R6/2 mice occurs uniformly. Paradoxically however, skeletal muscles show age‐dependent denervation‐like abnormalities, including supersensitivity to acetylcholine, decreased sensitivity to µ‐conotoxin, and anode‐break action potentials. Morphological abnormalities of neuromuscular junctions are also present, particularly in older R6/2 mice. Severely affected R6/2 mice show a progressive increase in the number of motor endplates that fail to respond to nerve stimulation. Surprisingly, there was no constitutive sprouting of motor neurons in R6/2 muscles, even in severely atrophic muscles that showed other denervation‐like characteristics. In fact, there was an age‐dependent loss of regenerative capacity of motor neurons in R6/2 mice. Because muscle fibers appear to be released from the activity‐dependent cues that regulate membrane properties and muscle size, and motor axons and nerve terminals become impaired in their capacity to release neurotransmitter and to respond to stimuli that normally evoke sprouting and adaptive reinnervation, we speculate that in these mice there is a progressive dissociation of trophic signalling between motor neurons and skeletal muscle. However, irrespective of the cause, the abnormalities at neuromuscular junctions we report here are likely to contribute to the pathological phenotype in R6/2 mice, particularly in late stages of the disease.
Synergistic action of GABA‐A and NMDA receptors in the induction of long‐term depression in glutamatergic synapses in the newborn rat hippocampus
Authors: Pavlov Ivan , Riekki Ruusu , Taira Tomi
Published: December 2004

We show that activation of GABAA receptors (GABAARs) promotes induction of N‐methyl‐d‐aspartate (NMDA) receptor (NMDAR)‐dependent long‐term depression (LTD) of glutamatergic synapses in the newborn rat hippocampal area CA1 in a developmentally restricted manner. In the newborn rat hippocampus two mechanistically different types of LTD of glutamatergic synapses could be induced under similar experimental conditions. The form of the LTD induced depended on the stimulation protocol and on the age of the animal. Low‐frequency stimulation (1 Hz) with 100 stimuli induced a robust homosynaptic, reversible LTD at postnatal days 2–8 (P2–P8) but not at P14. This LTD was blocked by the NMDAR antagonist AP5 or by the GABAAR antagonist picrotoxin. Use of a low‐chloride solution in the patch pipette resulting in EGABA‐A < –70 mV blocked the NMDAR‐dependent LTD, whereas clamping the cell to –40 mV during induction rescued it. In addition, it was possible to induce LTD at P14 with 100 stimuli if the cells were clamped to –40 mV during induction. Low‐frequency stimulation with 900 stimuli induced a robust homosynaptic, reversible LTD both at P2–P8 and at P14. However, neither AP5 nor picrotoxin affected the LTD induced by 900 pulses at P2–P8. Instead, the 900 stimuli‐induced LTD was blocked by the metabotropic glutamate receptor antagonists when co‐applied with AP5. We suggest that during the first postnatal week postsynaptic depolarization provided by the activation of GABAARs shifts the threshold for the LTD induction, making the synapses more prone to activity‐induced plasticity. From the second postnatal week onwards, when the GABAA responses are already hyperpolarizing, different mechanisms for LTD induction prevail.
Living learning theory through My Fair Lady
Authors: Glenzer Holly
Published: December 2004

In My Fair Lady (Lerner & Lowe, 1956), the play, the renowned linguistics professor, Henry Higgins, attempts to instruct the common flower‐vendor, Eliza Doolittle, in proper English etiquette and speech. Revisit the colourful story from the perspective of a twenty‐first century instructional designer. Set in the 1910s, but written in the heyday of behaviourism, the play reflects the idea that behavioural change is the evidence of learning. As we analyse Professor Higgins's applied theory of learning and instruction, we find unique examples of behaviourism, cognitivism and constructivism at work in the instructional strategies and activities and in the good professor's interpretations of Ms Doolittle's actions and attitudes toward learning.
THE OTHER SIDE OF SILENCE: RACHEL CARSON'S VIEWS OF ANIMALS
Authors: Bekoff Marc , Nystrom Jan
Published: December 2004

Abstract The publication of Rachel Carson's Silent Spring, a compelling blend of stories, natural history, human values, and biological facts, in 1962 was instrumental in launching the modern environmental movement. We consider Carson's attitude toward animals in Silent Spring and in her other writings. Carson favored responsible stewardship and was more of an animal welfarist and environmentalist/conservation biologist who privileged ecosystems and species than an animal activist who privileged individuals, and she did not advocate an animal‐rights agenda. There is clear tension in Carson's writings. Often she seems troubled by attempting to come across as a moderate and practical scientist, and some of her words, when considered out of context, could lead one to label her as an animal‐rightist. While some of Carson's writing favors human‐centered interests, she did not believe that only humans counted. Her warnings about silent springs must be taken seriously, perhaps even more seriously than when they were penned more than four decades ago. Carson was a passionate and extremely influential activist and if a world of persons like her were in charge of our global environmental policies, we and our fellow animals would be in much better shape than we currently are.
DOES GOD PLAY DICE? INSIGHTS FROM THE FRACTAL GEOMETRY OF NATURE
Authors: Carr Paul H.
Published: December 2004

AbstractAlbert Einstein and Huston Smith reflect the old metaphor that chaos and randomness are bad. Scientists recently have discovered that many phenomena, from the fluctuations of the stock market to variations in our weather, have the same underlying order. Natural beauty from plants to snowflakes is described by fractal geometry; tree branching from trunks to twigs has the same fractal scaling as our lungs, from trachea to bronchi. Algorithms for drawing fractals have both randomness and global determinism. Fractal statistics is like picking a card from a stacked deck rather than from one that is shuffled to be truly random. The polarity of randomness (or freedom) and law characterizes the self‐creating natural world. Polarity is in consonance with Taoism and contemporary theologians such as Paul Tillich, Alfred North Whitehead, Gordon Kaufman, Philip Hefner, and Pierre Teilhard de Chardin. Joseph Ford's new metaphor is replacing the old: “God plays dice with the universe, but they're loaded dice.”
BCL‐2‐induced glioma cell invasiveness depends on furin‐like proteases
Authors: Wick Wolfgang , Wild‐Bode Christine , Frank Brigitte , Weller Michael
Published: December 2004

Migration and invasion are prerequisites for the neoplastic phenotype of malignant glioma. Ectopic expression of BCL‐2 enhances migration and invasion of glioma cells and promotes their synthesis of transforming growth factor‐β2 (TGF‐β2). We here report that BCL‐2‐expressing cells show enhanced expression and activity of the proprotein convertase, furin, which processes metalloproteinases (MMP) and TGF‐β. Consistent with a biological role for a BCL‐2‐dependent increase in furin‐like protease (FLP) activity, BCL‐2‐expressing cells exhibit enhanced MMP activity. Both a pseudosubstrate furin inhibitor, decanoyl‐Arg‐Val‐Lys‐Arg‐chloromethylketone (dec‐RVKR‐cmk), or alpha 1‐anti‐trypsin Portland (PDX), a recombinant furin‐inhibitory protein, suppress constitutive and BCL‐2‐mediated MMP activity and invasion. This inhibition is not overcome by TGF‐β or hepatocyte growth factor (HGF). A neutralizing TGF‐β antibody attenuates, but not abrogates, the invasive properties conferred by exogenous expression of BCL‐2, whereas the MMP inhibitor o‐phenantroline (o‐PA) abolishes the pro‐invasive action of BCL‐2. Exogenous HGF results in enhanced, and expression of dominant‐negative ezrin in reduced, FLP activity, and dec‐RVKR‐cmk blunts the HGF‐induced expression of mature TGF‐β2. Consequently, HGF and BCL‐2 family proteins use a furin‐dependent pathway to promote invasion via TGF‐β and MMP in human malignant glioma cells and the pro‐invasive properties of TGF‐β require furin‐ dependent MMP activity.
Neurotrophin‐3‐induced production of nerve growth factor is suppressed in Schwann cells exposed to high glucose: involvement of the polyol pathway
Authors: Suzuki Takeshi , Sekido Hiromi , Kato Noriaki , Nakayama Yukiharu , Yabe‐Nishimura Chihiro
Published: December 2004

Development of hypesthesia, a loss of sensitivity to stimulation, is associated with impaired regeneration of peripheral sensory fibers, in which Schwann cells play a key role by secreting nerve growth factor (NGF). Recent clinical trials indicated that an inhibitor of aldose reductase (AR), the rate‐limiting enzyme in the polyol pathway, significantly improved hypesthesia in diabetic patients. The fact that AR is localized in Schwann cells led us to investigate the role of the polyol pathway in NGF production of isolated Schwann cells. Among various endogenous factors examined, increased production of NGF was demonstrated in the cells treated with neurotrophin‐3 (NT‐3) for 24 h. NT‐3‐induced NGF production was significantly suppressed when cells were cultured in the medium containing high glucose. In these cells, the levels of glutathione (GSH) and cAMP‐response element binding protein (CREB) were reduced, whereas the level of activated nuclear factor‐κB (NF‐κB) was elevated. These changes were abolished when an AR inhibitor fidarestat was included in the medium. NT‐3‐induced NGF production was further attenuated in the cells treated with an inhibitor of GSH synthesis. Together, the enhanced polyol pathway activity under high‐glucose conditions seems to elicit reduced NT‐3‐induced NGF production in Schwann cells. Enhanced oxidative stress linked to the polyol pathway activity may mediate this process.
Prostaglandin E2 and microsomal prostaglandin E synthase‐2 expression are decreased in the cyclooxygenase‐2‐deficient mouse brain despite compensatory induction of cyclooxygenase‐1 and Ca2+‐dependent phospholipase A2
Authors: Bosetti Francesca , Langenbach Robert , Weerasinghe Gayani R.
Published: December 2004

We previously demonstrated that brain cyclooxygenase (COX)‐2 mRNA and protein levels, and prostaglandin E2 (PGE2) level, are down‐regulated in cytosolic phospholipase A2 (cPLA2) ‐deficient mice. To further investigate the interaction between upstream and downstream enzymes involved in brain prostaglandin synthesis, we examined expression and activity of COX‐1, of different PLA2 enzymes and of prostaglandin E synthase (PGES) enzymes in COX‐2–/– mice. We found that the PGE2 level was decreased by 51.5% in the COX‐2–/– mice brains, indicating a significant role of COX‐2 in brain formation of PGE2. However, when we supplied exogenous arachidonic acid (AA) to brain homogenates, COX activity was increased in the COX‐2–/– mice, suggesting a compensatory activation of COX‐1 and an intracellular compartmentalization of the COX isozymes. Consistent with COX‐1 increased activity, brain expression of COX‐1 protein and mRNA also was increased. Activity and expression of cPLA2 and secretory PLA2 (sPLA2) enzymes, supplying AA to COX, were significantly increased. Also, the PGE2 biosynthetic pathway downstream from COX‐2 was affected in the COX‐2–/– mice, as decreased expression of microsomal prostaglandin E synthase‐2 (mPGES‐2), but not mPGES‐1 or cytosolic PGES, was observed. Overall, the data suggest that compensatory mechanisms exist in COX‐2–/– mice and that mPGES‐2 is functionally coupled with COX‐2.
Arrestin2 expression selectively increases during neural differentiation
Authors: Gurevich Eugenia V. , Benovic Jeffrey L. , Gurevich Vsevolod V.
Published: December 2004

Arrestins and G protein‐coupled receptor kinases (GRKs) are key players in homologous desensitization of G protein‐coupled receptors. Two non‐visual arrestins, arrestin2 and 3, and five GRKs (GRK2, 3, 4, 5 and 6) are involved in desensitization of many receptors. Here, we demonstrate a steady increase in arrestin2 expression during prenatal development. The density of arrestin2 mRNA is higher in differentiated areas as compared with proliferative zones, whereas arrestin3 mRNA shows the opposite distribution. At embryonic day 14, concentrations of arrestin proteins are similar (32–34 nm). Later in development, arrestin2 expression rises, leading to a fourfold excess of arrestin2 over arrestin3 at birth (48 vs. 11 ng/mg protein or 102 vs. 25 nm). Among GRKs, only GRK5 increased with embryonic age from 124 nmat E14 to 359 nmat birth. Similarly,in vitrodifferentiation of cultured precursor cells, neurospheres, leads to a significant up‐regulation of arrestin2 resulting in > 20‐fold excess of arrestin2 (160 vs. 7 nm). GRK5 is the only subtype increased with neurosphere differentiation, although the change is only about twofold. The data demonstrate selective increases in the expression of arrestin2 associated with neural development and suggest specific yet unappreciated roles for arrestin2 in neural differentiation.
Middle ear tumours with brainstem extension treated by ventral bulla osteotomy and craniectomy in two cats
Authors: Lucroy M. D. , Vernau K. M. , Samii V. F. , LeCouteur R. A.
Published: December 2004

Two geriatric domestic shorthaired cats (DSH) were treated surgically with a ventral bulla osteotomy and craniectomy for middle ear tumours that invaded the calvarium. Both cats had a history of vestibular disease. One cat had a normal neurological examination. Both cats underwent computed tomographic imaging of the head. After intravenous injection of an iodinated contrast material, one cat had a ring‐enhancing intracranial lesion and the other had a uniform contrast‐enhancing intracranial lesion, which either communicated with the bulla or was associated with bulla osseous lysis/production. One cat had a papillary adenoma and the other had an adenocarcinoma. Both cats had prolonged survivals (630 days; alive and lost to follow‐up at 840 days), which is longer than reported in cats with middle ear neoplasia. Craniectomy, in addition to ventral bulla osteotomy, may be part of the treatment plan for middle ear tumours that invade the calvarium.
Evaluation of telomerase‐targeted therapies in canine cancer cell lines
Authors: Argyle D. J. , McKevitt T. , Gault E. , Nasir L.
Published: December 2004

Despite advances in conventional therapeutics, cancer remains an invariably fatal disease, the major challenge being to develop tumour‐specific cancer treatment strategies. Current treatments such as chemotherapy and radiotherapy rely on a crude distinction between cancer cells and normal cells. However, with an increased understanding of the molecular events in the development of cancer, it is possible that far more innovative and targeted approaches can be developed. From studies on humans and dogs, the enzyme telomerase has emerged as a central unifying mechanism underlying the immortal phenotype of cancer and has thus become a candidate for differentiating between normal and cancer cells. The level and frequency of telomerase activity and component gene expression in cancers reinforces this as a potential target for cancer therapies. This article describes two approaches to target cancer by capitalizing on the expression of this enzyme. In the first approach, we target the enzyme itself, the goal being to cause cancer cell death. In the second approach, we utilize the respective gene promoters for telomerase component enzymes to drive expression of a reporter gene in cancer cell lines. The results demonstrated that targeted gene expression using promoter elements can be achieved specifically in telomerase‐positive cell lines. However, targeting the enzyme itself proved less successful and warrants investigations into alternative approaches.
Treatment of canine haemangiosarcoma with suberoylanilide hydroxamic acid, a histone deacetylase inhibitor
Authors: Cohen L. A. , Powers B. , Amin S. , Desai D.
Published: December 2004

A case report is presented by describing the treatment of a 12‐year‐old dog – diagnosed with haemangiosarcoma (HSA) – with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor. The drug was administered orally, on a daily basis, approximately 2 weeks post‐splenectomy at a dose of 3 mg kg−1. HSA is a lethal malignancy of the endothelium, which is usually disseminated by the time it is diagnosed. Median survival time, usually, is no longer than 80 days. Following treatment with SAHA, no sign of malignant growth could be discerned by means of diagnostic abdominal ultrasound, chest X‐ray or with the help of clinical symptoms, over a period of >1000 days. The precise mechanism by which HDAC inhibitors exert their anti‐cancer effects is uncertain, but evidence suggests that exposure to SAHA generates hyperacetylated chromosomal histones, which, in turn, facilitates the expression of tumour suppressor genes turned off by epigenetic mechanisms during neoplastic transformation of the endothelium.
Kinase inhibitors in cancer therapy
Authors: London C.
Published: December 2004

Over the past few years, protein kinases have arisen as promising targets for therapeutic intervention in cancer therapy. This is due to a combination of several key events, including the identification of common kinase dysfunction in particular tumours and the recent success of such targeted kinase inhibitors as Gleevec (imatinib mesylate) and Iressa (Gefatinib). Ultimately, the success of this novel approach will be dependent on the careful identification and characterization of protein kinase dysregulation in particular forms of cancer. This review focuses on the function of protein kinases in normal cells, the mechanisms through which these kinases contribute to tumorigenesis, and the development and application of agents designed to inhibit dysfunctional kinases.
Promoting Evidence‐Based Practice: An Internship for Staff Nurses
Authors: Cullen Laura , Titler Marita G.
Published: December 2004

Implementing evidence‐based practice is a complex but valued process that requires support for nurses to make it a reality in care delivery. To address this, an Evidence‐Based Practice Staff Nurse Internship was developed at the University of Iowa Hospitals and Clinics in the United States.

Program Overview: The objective of this internship is to promote use of evidence by staff nurses to improve patient outcomes. Through a competitive application process, six nurses are accepted in each cohort. The program provides didactic content and dedicated work time on topics interns select (e.g., family pet visitation, sedation management, bowel sounds assessment, guided imagery, family transition to pediatric floor). Interns receive paid clinical release time for participating.

Roles and Responsibilities: Teams include the staff nurse, the nurse manager, and an advanced practice nurse. Responsibilities for each step are assigned to the person with the appropriate expertise.

Evaluation: Interns report understanding the process, appreciate the opportunity for professional growth, and report their objectives are being met. Participants evaluated the program very positively and also provided recommendations for revision (e.g., revising class content). The program resulted in improved quality of care such as increased patient and family satisfaction, decreased length of stay, and cost savings.

Implications: Programs that support practitioners through the evidence‐based practice process are needed for use in a variety of settings internationally. This unique program supports staff nurses in making evidence‐based practice a reality for their work and patients and might be transferable across settings.
Sustaining Knowledge Transfer Through Leadership
Authors: Gifford Wendy , Davies Barbara , Edwards Nancy , Griffin Pat
Published: December 2004

The delivery of efficient and high quality nursing care in today's health care environment requires that nurses utilize research evidence to guide their decision‐making in clinical practice. Best Practice Guidelines (BPGs) are an accessible link to research evidence and an effective tool for improving quality health care. Despite reported benefits and dissemination strategies, the transfer and uptake of guidelines does not always occur, and sustainability over time is seldom evaluated. Emerging evidence indicates that leadership plays a fundamental role in the transfer and sustained use of BPGs in clinical decision‐making. However, a clear understanding of effective nursing leadership to sustain knowledge transfer remains unclear and research is limited.

Objective: To describe the evolving development of a conceptual framework for sustaining knowledge transfer of BPGs into nursing practice in Canadian health care settings.

Methods: A critical review of the literature has been conducted. A model was developed to direct an inquiry about leadership characteristics and activities in 10 organizations that either sustained, partially sustained, or did not sustain practice guidelines 2 years after a pilot implementation initiative administrated by the Registered Nurses Association of Ontario Best Practice Guideline (RNAO‐BPG) Project.

Findings: A conceptual framework has been developed to represent the key components of leadership and how these components are operationalized for knowledge transfer of BPGs into clinical practice. The model is an assimilation of the United Kingdom and North American literature and includes a pathway for personal attributes, defined skills, and knowledge repertoires that emerge from two domains of influence: cultural/clinical and political/organizational. Although the literature shows many similarities between leadership paradigms, some differences in discourse and approach were found.

Implications: To create successful strategies to sustain practice innovations, we need to better understand how nursing leaders operate effectively within both clinical and organizational environments. This framework is the groundwork for conceptualizing nursing leadership as a vehicle to influence, shape, and sustain evidence‐based nursing practice.
On the standard Gibbs energy of formation of CoO
Authors: Fredriksson Patrik , Seetharaman Seshadri
Published: December 2004

The standard Gibbs energy of formation of CoO was determined by the galvanic cell (−) Pt, Fe(s), ‘FeO’(s)//ZrO2 (partially stabilised//CoO(s), Co(s), Pt (+) with CaO or Y2O3) in the temperature range 1052–1488 K. The results are compared with earlier reported values. An equation for the standard Gibbs energy change for the reactions Co(s) +½O2(g) = CoO(s) and Co(s) +O(Co, fcc) = CoO(s) is recommended based on the present data.
A numerical simulation of the DC continuous casting using average heat capacity
Authors: Korti Abdel Illah Nabil , Khadraoui Yahia
Published: December 2004

Continuous casting is one of the prominent methods of production of metals. The effective design and operation of continuous casting machines needs complete analysis of the continuous casting process. In this paper, a finite volume model has been developed and applied to compute the fluid flow, temperature and flux distributions within the liquid, mushy and solid zones in the mold and cooling regions of an aluminum alloy direct‐chill continuous casting machine. The average heat capacity method was successfully implemented for the analysis of conjugate heat transfer during the phase change phenomenon. The effect of phase change on convection is accounted for using a new modification in the velocity vector. The effect of casting speed on fluid flow, temperature and surface heat flux evolution was investigated. The predicted temperature distribution and surface heat flux were compared with experimental measurements and numerical solutions given in the literature. A reasonable agreement was obtained.
Non‐metallic inclusions in the ingot and final products of a medium‐carbon tool steel
Authors: Tripathi Nagendra , Sichen Du
Published: December 2004

The present work was carried out at Uddeholm Tooling AB, Sweden to study the inclusion characteristics in the ingot and the final product of a ‘medium‐carbon’ tool steel. Steel samples were taken during the mould filling, after casting and from the final product. The inclusion populations in the steel samples were examined under a light optical microscope. The chemical compositions of the inclusions were analysed using a scanning electron microscope attached with EDX. The steel samples taken during the mould filling were found to contain alumina‐based inclusions, originated from the erosion of the closing gates, the inner nozzle and the outer nozzle. The analyses of the steel samples from the solidified ingot revealed a non‐uniform distribution of inclusions. The inclusion population was found to be highest in the centre part of the ingot and lowest between the central line and the mould wall. The steel samples from the bars of the final products were taken at an identical position in each case, corresponding to the central part of the ingot. The inclusion populations were found to be somewhat higher in the final product in comparison with the populations before casting. The inclusion populations in the final products were also found to increase with the ladle age.
Crystal Structure of a Photolyase Bound to a CPD-Like DNA Lesion After in Situ Repair
Authors: Mees Alexandra , Klar Tobias , Gnau Petra , Hennecke Ulrich , Eker Andre P. M. , Carell Thomas , Essen Lars-Oliver
Published: December 2004

DNA photolyases use light energy to repair DNA that comprises ultraviolet-induced lesions such as the
cis-syn
cyclobutane pyrimidine dimers (CPDs). Here we report the crystal structure of a DNA photolyase bound to duplex DNA that is bent by 50° and comprises a synthetic CPD lesion. This CPD lesion is flipped into the active site and split there into two thymines by synchrotron radiation at 100 K. Although photolyases catalyze blue light–driven CPD cleavage only above 200 K, this structure apparently mimics a structural substate during light-driven DNA repair in which back-flipping of the thymines into duplex DNA has not yet taken place.
Efficient Deactivation of a Model Base Pair via Excited-State Hydrogen Transfer
Authors: Schultz Thomas , Samoylova Elena , Radloff Wolfgang , Hertel Ingolf V. , Sobolewski Andrzej L. , Domcke Wolfgang
Published: December 2004

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 ± 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited
1
ππ* state and the electronic ground state with a
1
ππ* charge-transfer state that is strongly stabilized by the transfer of a proton.