bluuebunny/crossref_metadata_2025 huggingface dataset:
Müller cells are living optical fibers in the vertebrate retina
Authors: Franze Kristian , Grosche Jens , Skatchkov Serguei N. , Schinkinger Stefan , Foja Christian , Schild Detlev , Uckermann Ortrud , Travis Kort , Reichenbach Andreas , Guck Jochen
Published: May 2007

Although biological cells are mostly transparent, they are phase objects that differ in shape and refractive index. Any image that is projected through layers of randomly oriented cells will normally be distorted by refraction, reflection, and scattering. Counterintuitively, the retina of the vertebrate eye is inverted with respect to its optical function and light must pass through several tissue layers before reaching the light-detecting photoreceptor cells. Here we report on the specific optical properties of glial cells present in the retina, which might contribute to optimize this apparently unfavorable situation. We investigated intact retinal tissue and individual Müller cells, which are radial glial cells spanning the entire retinal thickness. Müller cells have an extended funnel shape, a higher refractive index than their surrounding tissue, and are oriented along the direction of light propagation. Transmission and reflection confocal microscopy of retinal tissue
in vitro
and
in vivo
showed that these cells provide a low-scattering passage for light from the retinal surface to the photoreceptor cells. Using a modified dual-beam laser trap we could also demonstrate that individual Müller cells act as optical fibers. Furthermore, their parallel array in the retina is reminiscent of fiberoptic plates used for low-distortion image transfer. Thus, Müller cells seem to mediate the image transfer through the vertebrate retina with minimal distortion and low loss. This finding elucidates a fundamental feature of the inverted retina as an optical system and ascribes a new function to glial cells.
Carbonic anhydrase XIV deficiency produces a functional defect in the retinal light response
Authors: Ogilvie Judith Mosinger , Ohlemiller Kevin K. , Shah Gul N. , Ulmasov Barbara , Becker Timothy A. , Waheed Abdul , Hennig Anne K. , Lukasiewicz Peter D. , Sly William S.
Published: May 2007

Members of the carbonic anhydrase (CA) family play an important role in the regulation of pH, CO2, ion, and water transport. CA IV and CA XIV are membrane-bound isozymes expressed in the eye. CA IV immunostaining is limited to the choriocapillaris overlying the retina, whereas CA XIV is expressed within the retina in Müller glial cells and retinal pigment epithelium. Here, we have characterized the physiological and morphological phenotype of the CA IV-null, CA XIV-null, and CA IV/CA XIV-double-null mouse retinas. Flash electroretinograms performed at 2, 7, and 10 months of age showed that the rod/cone a-wave, b-wave, and cone b-wave were significantly reduced (26–45%) in the CA XIV-null mice compared with wild-type littermates. Reductions in the dark-adapted response were not progressive between 2 and 10 months, and no differences in retinal morphology were observed between wild-type and CA XIV-null mice. Müller cells and rod bipolar cells had a normal appearance. Retinas of CA IV-null mice showed no functional or morphological differences compared with normal littermates. However, CA IV/CA XIV double mutants showed a greater deficit in light response than the CA XIV-null retina. Our results indicate that CA XIV, which regulates extracellular pH and pCO2, plays an important part in producing a normal retinal light response. A larger functional deficit in the CA IV/CA XIV double mutants suggests that CA IV can also contribute to pH regulation, at least in the absence of CA XIV.
Agalactosylated IgG antibodies depend on cellular Fc receptors forin vivoactivity
Authors: Nimmerjahn Falk , Anthony Robert M. , Ravetch Jeffrey V.
Published: May 2007

IgG antibodies are glycoproteins containing a branched sugar moiety attached to the asparagine 297 residue in the antibody constant region (Fc). This glycan is essential for maintaining a functional Fc structure, which is a prerequisite for antibody-mediated effector functions, such as the interaction with cellular Fc receptors or the complement component C1q. Variations in the composition of the sugar moiety can dramatically influence antibody activity. Moreover, humans and mice with autoimmune disorders, such as rheumatoid arthritis, have altered IgG glycosylation patterns with increased levels of antibodies lacking terminal sialic acid and galactose residues (IgG-G0). There is great interest in understanding whether this altered glycosylation pattern influences antibody-mediated effector functions.In vitrostudies have suggested that IgG-G0 antibodies gain the capacity to activate the complement pathway via mannose-binding lectin (MBL), which could contribute to antibody-mediated inflammation. We have analyzed the activity of IgG-G0 antibodies in mice with a genetic deletion of MBL (MBL-null mice) and demonstrate that IgG-G0 antibodies are unimpaired in MBL-null mice. In contrast, the activity of these antibody glycovariants is fully dependent on the presence of activating Fc receptors.
Semaphorin 7A plays a critical role in TGF-β1–induced pulmonary fibrosis
Authors: Kang Hye-Ryun , Lee Chun Geun , Homer Robert J. , Elias Jack A.
Published: May 2007

Semaphorin (SEMA) 7A regulates neuronal and immune function. In these studies, we tested the hypothesis that SEMA 7A is also a critical regulator of tissue remodeling. These studies demonstrate that SEMA 7A and its receptors, plexin C1 and β1 integrins, are stimulated by transforming growth factor (TGF)-β1 in the murine lung. They also demonstrate that SEMA 7A plays a critical role in TGF-β1–induced fibrosis, myofibroblast hyperplasia, alveolar remodeling, and apoptosis. TGF-β1 stimulated SEMA 7A via a largely Smad 3–independent mechanism and stimulated SEMA 7A receptors, matrix proteins, CCN proteins, fibroblast growth factor 2, interleukin 13 receptor components, proteases, antiprotease, and apoptosis regulators via Smad 2/3–independent and SEMA 7A–dependent mechanisms. SEMA 7A also played an important role in the pathogenesis of bleomycin-induced pulmonary fibrosis. TGF-β1 and bleomycin also activated phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB)/AKT via SEMA 7A–dependent mechanisms, and PKB/AKT inhibition diminished TGF-β1–induced fibrosis. These observations demonstrate that SEMA 7A and its receptors are induced by TGF-β1 and that SEMA 7A plays a central role in a PI3K/PKB/AKT-dependent pathway that contributes to TGF-β1–induced fibrosis and remodeling. They also demonstrate that the effects of SEMA 7A are not specific for transgenic TGF-β1, highlighting the importance of these findings for other fibrotic stimuli.
Activation-induced cytidine deaminase acts as a mutator in BCR-ABL1–transformed acute lymphoblastic leukemia cells
Authors: Feldhahn Niklas , Henke Nadine , Melchior Kai , Duy Cihangir , Soh Bonaventure Ndikung , Klein Florian , von Levetzow Gregor , Giebel Bernd , Li Aihong , Hofmann Wolf-Karsten , Jumaa Hassan , Müschen Markus
Published: May 2007

The Philadelphia chromosome (Ph) encoding the oncogenic BCR-ABL1 kinase defines a subset of acute lymphoblastic leukemia (ALL) with a particularly unfavorable prognosis. ALL cells are derived from B cell precursors in most cases and typically carry rearranged immunoglobulin heavy chain (IGH) variable (V) region genes devoid of somatic mutations. Somatic hypermutation is restricted to mature germinal center B cells and depends on activation-induced cytidine deaminase (AID). Studying AID expression in 108 cases of ALL, we detected AID mRNA in 24 of 28 Ph+ ALLs as compared with 6 of 80 Ph− ALLs. Forced expression of BCR-ABL1 in Ph− ALL cells and inhibition of the BCR-ABL1 kinase showed that aberrant expression of AID depends on BCR-ABL1 kinase activity. Consistent with aberrant AID expression in Ph+ ALL, IGH V region genes and BCL6 were mutated in many Ph+ but unmutated in most Ph− cases. In addition, AID introduced DNA single-strand breaks within the tumor suppressor gene CDKN2B in Ph+ ALL cells, which was sensitive to BCR-ABL1 kinase inhibition and silencing of AID expression by RNA interference. These findings identify AID as a BCR-ABL1–induced mutator in Ph+ ALL cells, which may be relevant with respect to the particularly unfavorable prognosis of this leukemia subset.
Inflammatory monocytes recruited after skeletal muscle injury switch into antiinflammatory macrophages to support myogenesis
Authors: Arnold Ludovic , Henry Adeline , Poron Françoise , Baba-Amer Yasmine , van Rooijen Nico , Plonquet Anne , Gherardi Romain K. , Chazaud Bénédicte
Published: May 2007

Macrophages (MPs) are important for skeletal muscle regeneration in vivo and may exert beneficial effects on myogenic cell growth through mitogenic and antiapoptotic activities in vitro. However, MPs are highly versatile and may exert various, and even opposite, functions depending on their activation state. We studied monocyte (MO)/MP phenotypes and functions during skeletal muscle repair. Selective labeling of circulating MOs by latex beads in CX3CR1GFP/+ mice showed that injured muscle recruited only CX3CR1lo/Ly-6C+ MOs from blood that exhibited a nondividing, F4/80lo, proinflammatory profile. Then, within muscle, these cells switched their phenotype to become proliferating antiinflammatory CX3CR1hi/Ly-6C− cells that further differentiated into F4/80hi MPs. In vitro, phagocytosis of muscle cell debris induced a switch of proinflammatory MPs toward an antiinflammatory phenotype releasing transforming growth factor β1. In co-cultures, inflammatory MPs stimulated myogenic cell proliferation, whereas antiinflammatory MPs exhibited differentiating activity, assessed by both myogenin expression and fusion into myotubes. Finally, depletion of circulating MOs in CD11b–diphtheria toxin receptor mice at the time of injury totally prevented muscle regeneration, whereas depletion of intramuscular F4/80hi MPs at later stages reduced the diameter of regenerating fibers. In conclusion, injured skeletal muscle recruits MOs exhibiting inflammatory profiles that operate phagocytosis and rapidly convert to antiinflammatory MPs that stimulate myogenesis and fiber growth.
Distinct domains in Nbs1 regulate irradiation-induced checkpoints and apoptosis
Authors: Difilippantonio Simone , Celeste Arkady , Kruhlak Michael J. , Lee Youngsoo , Difilippantonio Michael J. , Feigenbaum Lionel , Jackson Stephen P. , McKinnon Peter J. , Nussenzweig André
Published: May 2007

The chromosomal instability syndromes Nijmegen breakage syndrome (NBS) and ataxia telangiectasia (AT) share many overlapping phenotypes, including cancer predisposition, radiation sensitivity, cell-cycle checkpoint defects, immunodeficiency, and gonadal dysfunction. The NBS protein Nbs1 is not only a downstream target of AT mutated (ATM) kinase but also acts upstream, promoting optimal ATM activation, ATM recruitment to breaks, and ATM accessibility to substrates. By reconstituting Nbs1 knockout mice with bacterial artificial chromosomes, we have assessed the contribution of distinct regions of Nbs1 to the ATM-dependent DNA damage response. We find that T cell and oocyte development, as well as DNA damage-induced G2/M and S phase checkpoint arrest and radiation survival are dependent on the N-terminal forkhead-associated domain, but not on the principal residues phosphorylated by ATM (S278 and S343) or on the evolutionarily conserved C-terminal region of Nbs1. However, the C-terminal region regulates irradiation-induced apoptosis. These studies provide insight into the complex interplay between Nbs1 and ATM in the DNA damage response.
SQUINT: a multiple alignment program and editor
Authors: Goode Matthew G. , Rodrigo Allen G.
Published: May 2007

Summary: SQUINT is a sequence alignment tool, and combines both automated progressive sequence alignment with facilities for manual editing. The program imports nucleotide or amino acid sequence multiple alignment files in standard formats, and permits users to view two translations of the same multiple alignment simultaneously. Edits in one view are instantaneously reflected in the other, and the scoring cost of the changes are shown in real-time. Progressive multiple alignments, using a variety of alignment parameters, can be performed on any block of sequences, including blocks embedded in the existing alignment.

Availability: The software is freely available for download at http://www.cebl.auckland.ac.nz

Contact:  a.rodrigo@auckland.ac.nz
AutoCSA, an algorithm for high throughput DNA sequence variant detection in cancer genomes
Authors: Dicks E. , Teague J. W. , Stephens P. , Raine K. , Yates A. , Mattocks C. , Tarpey P. , Butler A. , Menzies A. , Richardson D. , Jenkinson A. , Davies H. , Edkins S. , Forbes S. , Gray K. , Greenman C. , Shepherd R. , Stratton M. R. , Futreal P. A. , Wooster R.
Published: May 2007

The undertaking of large-scale DNA sequencing screens for somatic variants in human cancers requires accurate and rapid processing of traces for variants. Due to their often aneuploid nature and admixed normal tissue, heterozygous variants found in primary cancers are often subtle and difficult to detect. To address these issues, we have developed a mutation detection algorithm, AutoCSA, specifically optimized for the high throughput screening of cancer samples.

Availability: http://www.sanger.ac.uk/genetics/CGP/Software/AutoCSA.

Contact: mrs@sanger.ac.uk
Comparing association network algorithms for reverse engineering of large-scale gene regulatory networks: synthetic versus real data
Authors: Soranzo Nicola , Bianconi Ginestra , Altafini Claudio
Published: May 2007

Motivation: Inferring a gene regulatory network exclusively from microarray expression profiles is a difficult but important task. The aim of this work is to compare the predictive power of some of the most popular algorithms in different conditions (like data taken at equilibrium or time courses) and on both synthetic and real microarray data. We are in particular interested in comparing similarity measures both of linear type (like correlations and partial correlations) and of non-linear type (mutual information and conditional mutual information), and in investigating the underdetermined case (less samples than genes).

Results: In our simulations we see that all network inference algorithms obtain better performances from data produced with ‘structural’ perturbations, like gene knockouts at steady state, than with any dynamical perturbation. The predictive power of all algorithms is confirmed on a reverse engineering problem from Escherichia coli gene profiling data: the edges of the ‘physical’ network of transcription factor–binding sites are significantly overrepresented among the highest weighting edges of the graph that we infer directly from the data without any structure supervision. Comparing synthetic and in vivo data on the same network graph allows us to give an indication of how much more complex a real transcriptional regulation program is with respect to an artificial model.

Availability: Software is freely available at the URL http://people.sissa.it/~altafini/papers/SoBiAl07/

Contact: altafini@sissa.it

Supplementary information: Supplementary data are available at Bioinformatics online.
Genetdes: automatic design of transcriptional networks
Authors: Rodrigo Guillermo , Carrera Javier , Jaramillo Alfonso
Published: May 2007

Motivation: The rational design of biological networks with prescribed functions is limited to gene circuits of a few genes. Larger networks involve complex interactions with many parameters and the use of automated computational tools can be very valuable. We propose a new tool to design transcriptional networks with targeted behavior that could be used to better understand the design principles of genetic circuits.

Results: We have implemented a Simulated Annealing optimization algorithm that explores throughout the space of transcription networks to obtain a specific behavior. The software outputs a transcriptional network with all the corresponding kinetic parameters in SBML format. We provide examples of transcriptional circuits with logical and oscillatory behaviors. Our tool can also be applied to design networks with multiple external input and output genes.

Availability: The software, a tutorial manual, parameter sets and examples are freely available at http://synth-bio.yi.org/genetdes.html

Contact:  Alfonso.Jaramillo@polytechnique.edu
Clinical outcome of de novo acute myeloid leukaemia patients with normal cytogenetics is affected by molecular genetic alterations: a concise review
Authors: Baldus Claudia D. , Mrózek Krzysztof , Marcucci Guido , Bloomfield Clara D.
Published: May 2007

Normal cytogenetics are detected pretreatment in approximately 45% of patients with de novo acute myeloid leukaemia (AML); thus this constitutes the single largest cytogenetic group of AML. Recently, molecular genetic alterations with prognostic significance have been reported in these patients. They include internal tandem duplication of the FLT3 gene, partial tandem duplication of the MLL gene, mutations of the CEBPA and NPM1 genes and aberrant expression of the BAALC, ERG and MN1 genes. Additionally, gene‐expression profiling has been applied to identify prognostically relevant subgroups. Substantial progress has been made in the understanding of molecular pathways deregulated in leukaemogenesis and how these defects can be targeted by novel therapeutic compounds. Here we critically review the molecular heterogeneity among AML patients with normal cytogenetics and discuss how these data may translate into a prognostic, molecular‐based treatment stratification that may improve the currently unsatisfactory outcome of these patients.
Women's experience of ageing with a chronic condition
Authors: Giddings Lynne S. , Roy Dianne E. , Predeger Elizabeth
Published: May 2007

Title. Women's experience of ageing with a chronic condition

Aim.  This paper is a report of a study to explore the experiences of ‘almost old’ women as they grow older while living with a chronic condition.

Background.  Little is known about the contextual effects of ageing and how it shapes and is shaped by a woman's chronic illness experience. Nurses’ understanding of this phenomenon can have positive effects on how their client accesses and responds to healthcare.

Method.  Seven women aged between 50 and 58 years participated in this interpretive descriptive study that explored the issues of ageing with a chronic condition. Three focus groups were held between March 2003 and March 2004. Transcriptions were analyzed after each focus group. Participants were given the opportunity to respond to the findings as the analysis progressed.

Findings.  The experience of living with a chronic illness foreshadowed what was to come with ageing and embodied the ageing process: it was just part of their lives. Alongside this, the women now felt less out of place. Their peers were catching up and beginning to experience aspects of participants’ everyday reality. The women, however, experienced double jeopardy because ageing amplified the ongoing vulnerabilities of living with a chronic condition.

Conclusion.  Nurses who recognize the resourcefulness and expertise of women who live with a chronic condition can effectively be co‐strategists in their helping them to age well.
Impact of intravenous drug use on quality of life for patients with venous ulcers
Authors: Palfreyman Simon J. , Tod Angela M. , King Brenda , Tomlinson Darlene , Brazier John E. , Michaels Jonathan A.
Published: May 2007

Title.  Impact of intravenous drug use on quality of life for patients with venous ulcers

Aim.  This paper is a report of a study to examine, from the perspective of patients, the impact of venous leg ulcers on health‐related quality of life in current and former intravenous drug users and the general population.

Background.  Venous ulceration can be caused by intravenous drug use. There has been little examination on how this affects the quality of life of this group of patients and how they compare with other patients who have venous ulcers.

Method.  A qualitative approach was adopted, using framework analysis. Semi‐structured interviews with 19 participants who had a venous leg ulcer were conducted between August 2005 and February 2006. Interview audiotapes were analysed to identify recurring themes relating to the impact of venous leg ulcers on overall quality of life.

Findings.  A complex interaction between symptoms, social restriction and attribution of illness influenced the impact of venous leg ulcers. Smell and pain were the symptoms that had the most profound impacts. In addition to the physical and psychological consequences, participants’ activities and social interactions were restricted. Intravenous drug users experienced more social isolation and difficulties in accessing treatment for their venous ulcers.

Conclusion.  While leg ulcer services remain focused on the needs of older people, services for young intravenous drug users are unlikely to improve. A more coherent and earlier intervention, when the ulcers are not as difficult to treat, would decrease time and costs to the health service. The challenge is to find new ways of providing effective and accessible care to this growing population.
Genetic monogamy despite social promiscuity in the pot‐bellied seahorse (Hippocampus abdominalis)
Authors: WILSON A. B. , MARTIN‐SMITH K. M.
Published: May 2007

Sexual selection theory predicts a positive correlation between relative parental investment and mate choice. In syngnathid fishes (seahorses and pipefish), males brood offspring in specialized brooding structures. While female‐female mating competition has been demonstrated in some pipefishes, all seahorses (genus Hippocampus) studied to date have been found to have conventional sex roles with greater male–male competition for access to mates despite possessing the most complex brood structures in the family. Although multiple mating is common in pipefish, seahorses are again exceptional, exhibiting strict genetic monogamy. Both demographic and behavioural explanations have been offered to explain the lack of multiple mating in seahorse species, but these hypotheses have not yet been explicitly addressed. We investigated mating systems and brood parentage of the pot‐bellied seahorse, Hippocampus abdominalis, a temperate‐water species that is socially promiscuous with conventional sex roles in laboratory populations. We observed promiscuous courtship behaviour and sex‐role reversal in high density, female‐biased field populations of H. abdominalis. We hypothesize that sex roles are plastic in H. abdominalis, depending on local population density and sex ratio. Despite promiscuous courtship behaviour, all assayed male seahorses were genetically monogamous in both laboratory and wild populations. Physiological limitations associated with embryo incubation may explain the absence of multiple mating in seahorses and may have played an important role in the development of the unique reproductive behaviour typical in these species.
Genetic consequences of Pleistocene range shifts: contrast between the Arctic, the Alps and the East African mountains
Authors: EHRICH DOROTHEE , GAUDEUL MYRIAM , ASSEFA ADANE , KOCH MARCUS A. , MUMMENHOFF KLAUS , NEMOMISSA SILESHI , CONSORTIUM INTRABIODIV , BROCHMANN CHRISTIAN
Published: May 2007

In wide‐ranging species, the genetic consequences of range shifts in response to climate change during the Pleistocene can be predicted to differ among different parts of the distribution area. We used amplified fragment length polymorphism data to compare the genetic structure of Arabis alpina, a widespread arctic‐alpine and afro‐alpine plant, in three distinct parts of its range: the North Atlantic region, which was recolonized after the last ice age, the European Alps, where range shifts were probably primarily altitudinal, and the high mountains of East Africa, where the contemporary mountain top populations result from range contraction. Genetic structure was inferred using clustering analyses and estimates of genetic diversity within and between populations. There was virtually no diversity in the vast North Atlantic region, which was probably recolonized from a single refugial population, possibly located between the Alps and the northern ice sheets. In the European mountains, genetic diversity was high and distinct genetic groups had a patchy and sometimes disjunct distribution. In the African mountains, genetic diversity was high, clearly structured and partially in accordance with a previous chloroplast phylogeography. The fragmented structure in the European and African mountains indicated that A. alpina disperses little among established populations. Occasional long‐distance dispersal events were, however, suggested in all regions. The lack of genetic diversity in the north may be explained by leading‐edge colonization by this pioneer plant in glacier forelands, closely following the retracting glaciers. Overall, the genetic structure observed corresponded to the expectations based on the environmental history of the different regions.
Effect of the NK3receptor antagonist, talnetant, on rectal sensory function and compliance in healthy humans
Authors: Houghton L. A. , Cremonini F. , Camilleri M. , Busciglio I. , Fell C. , Cox V. , Alpers D. H. , Dewit O. E. , Dukes G. E. , Gray E. , Lea R. , Zinsmeister A. R. , Whorwell P. J.
Published: May 2007

Abstract Visceral hypersensitivity is important in the pathophysiology of irritable bowel syndrome and thus a target for modulation in drug development. Neurokinin (NK) receptors, including NK3receptors, are expressed in the motor and sensory systems of the digestive tract. The aim of this study was to compare the effects of two different doses (25 and 100 mg) of the NK3receptor antagonist, talnetant (SB223412) with placebo on rectal sensory function and compliance in healthy volunteers studied at two centres. Rectal barostat tests were performed on 102 healthy volunteers, randomized to receive either oral talnetant 25 or 100 mg or placebo over 14–17 days. Studies were performed on three occasions: day 1 immediately prior to 1st dose, day 1 4 h postdose, and after 14‐ to17‐day therapy. Compliance, and pressure thresholds for first sensation, urgency, discomfort and pain were measured using ascending method of limits, and sensory intensity ratings for gas, urgency, discomfort and pain determined during four random phasic distensions (12, 24, 36 and 48 mmHg). Talnetant had no effect on rectal compliance, sensory thresholds or intensity ratings compared with placebo. In general, the results obtained at the two centres differed minimally, with intensity scores at one centre consistently somewhat lower. At the doses tested, talnetant has no effect on rectal compliance or distension‐induced rectal sensation in healthy participants.
Amyloid fibrils of mammalian prion protein induce axonal degeneration in NTERA2‐derived terminally differentiated neurons
Authors: Novitskaya Vera , Makarava Natallia , Sylvester Ian , Bronstein Igor B. , Baskakov Ilia V.
Published: May 2007

Defects in axonal transport and synaptic dysfunctions are associated with early stages of several neurodegenerative diseases including Alzheimer’s, Huntington’s, Parkinson’s, and prion diseases. Here, we tested the effect of full‐length mammalian prion protein (rPrP) converted into three conformationally different isoforms to induce pathological changes regarded as early subcellular hallmarks of prion disease. We employed human embryonal teratocarcinoma NTERA2 cells (NT2) that were terminally differentiated into neuronal and glial cells and co‐cultured together. We found that rPrP fibrils but not α‐rPrP or soluble β‐sheet rich oligomers caused degeneration of neuronal processes. Degeneration of processes was accompanied by a collapse of microtubules and aggregation of cytoskeletal proteins, formation of neuritic beads, and a dramatic change in localization of synaptophysin. Our studies demonstrated the utility of NT2 cells as valuable human model system for elucidating subcellular events of prion pathogenesis, and supported the emerging hypothesis that defects in neuronal transport and synaptic abnormalities are early pathological hallmarks associated with prion diseases.
GluR2‐free α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate receptors intensify demyelination in experimental autoimmune encephalomyelitis
Authors: Bannerman Peter , Horiuchi Makoto , Feldman Daniel , Hahn Ashleigh , Itoh Aki , See Jill , Jia Zheng Ping , Itoh Takayuki , Pleasure David
Published: May 2007

We adopted a genetic approach to test the importance of edited GluR2‐free, Ca2+‐permeable, α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) receptors in the pathophysiology of experimental autoimmune encephalomyelitis, an inflammatory demyelinative disorder resembling multiple sclerosis. Initial studies showed that oligodendroglial lineage cells from mice lacking functional copies of the gene encoding the GluR3 AMPA receptor subunit (Gria3) had a diminished capacity to assemble edited GluR2‐free AMPA receptors, and were resistant to excitotoxicity in vitro. Neurological deficits and spinal cord demyelination elicited by immunization with myelin oligodendrocyte glycoprotein peptide were substantially milder in these Gria3 mutant mice than in their wild‐type littermates. These results support the hypothesis that oligodendroglial excitotoxicity mediated by AMPA receptors that do not contain edited GluR2 subunits contributes to demyelination in experimental autoimmune encephalomyelitis, and suggest that inhibiting these Ca2+‐permeable AMPA receptors would be therapeutic in multiple sclerosis.
Differential effects of Parkin and its mutants on protein aggregation, the ubiquitin‐proteasome system, and neuronal cell death in human neuroblastoma cells
Authors: Kyratzi Elli , Pavlaki Maria , Kontostavlaki Dimitra , Rideout Hardy J. , Stefanis Leonidas
Published: May 2007

Mutations in Parkin, an E3 ligase, which participates in the ubiquitin‐proteasome system (UPS), cause juvenile onset Parkinson’s disease (PD). Some mutants aggregate upon over‐expression, but the effects of such aggregation on the UPS and neuronal survival have not been characterized. We show in this study that transient over‐expression of wild type (WT) Parkin or various mutants in human neuroblastoma cells leads to localized accumulation of green fluorescent protein (GFPu), an artificial proteasomal substrate, indicative of UPS dysfunction. Parkin mutants, but not WT, aggregated, and GFPu and ubiquitin accumulated within such aggregates. Apoptotic death occurred only with mutant Parkin over‐expression, and correlated with aggregation, but not GFPu accumulation. Enzymatic proteasomal activity was slightly increased with WT Parkin and decreased with mutant Parkin over‐expression. This decrease was, at least in part, due to caspase activation. We conclude that mutant forms of Parkin can exert toxic effects on neuronal cells, possibly through their propensity to aggregate. Both WT and mutant forms can induce localized UPS dysfunction, likely through different mechanisms. This raises a note of caution regarding forced over‐expression of Parkin as a neuroprotective strategy in PD or other neurodegenerative conditions and suggests a possible toxic gain of function for certain mutant forms of Parkin.
Cleavage of neuronal synaptosomal‐associated protein of 25 kDa by exogenous matrix metalloproteinase‐7
Authors: Szklarczyk Arek , Oyler George , McKay Ron , Gerfen Charles , Conant Katherine
Published: May 2007

Matrix metalloproteinases (MMPs) belong to a family of zinc dependent enzymes best studied for their role in cancer and inflammation. Though MMPs typically target extracellular proteins, here we show that MMP‐7, an MMP family member which lacks a C‐terminal hemopexin‐like domain, can cleave an intraneuronal protein that is critical to vesicular fusion and neurotransmitter release, synaptosomal‐associated protein of 25 kDa (SNAP‐25). Western blot analysis using an N‐terminal specific antibody on extracts from cultured neurons suggests that cleavage occurs towards the C‐terminal portion of SNAP 25. Additional studies with recombinant SNAP‐25 demonstrate that cleavage occurs at amino acid 129. The ability of MMP‐7 to cleave SNAP‐25 is diminished by chlorpromazine and phenylarsine oxide, inhibitors of clathrin dependent endocytosis. Together, these results imply that exogenous MMP‐7 can access an intraneuronal substrate and suggest that additional studies may be warranted to determine if SNAP function is impaired with brain inflammation.
Curcumin suppresses growth and chemoresistance of human glioblastoma cells via AP‐1 and NFκB transcription factors
Authors: Dhandapani Krishnan M. , Mahesh Virendra B , Brann Darrell W
Published: May 2007

Malignant gliomas are a debilitating class of brain tumors that are resistant to radiation and chemotherapeutic drugs, contributing to the poor prognosis associated with these tumors. Over‐expression of transcription factors such as NFκB and AP‐1 contribute to the enhanced glioma survival, radioresistance, and chemoresistance. Curcumin, which may inhibit these pathways, was therefore investigated for a potential therapeutic role in glioma. The effect of curcumin on glioma survival was investigated in human (T98G, U87MG, and T67) and rat (C6) glioma cell lines. The ability of curcumin to overcome glioma cell radioresistance and chemoresistance was also explored. Curcumin reduced cell survival in a p53‐ and caspase‐independent manner, an effect correlated with the inhibition of AP‐1 and NFκB signaling pathways via prevention of constitutive JNK and Akt activation. Curcumin‐sensitized glioma cells to several clinically utilized chemotherapeutic agents (cisplatin, etoposide, camptothecin, and doxorubicin) and radiation, effects correlated with reduced expression of bcl‐2 and IAP family members as well as DNA repair enzymes (MGMT, DNA‐PK, Ku70, Ku80, and ERCC‐1). These findings support a role for curcumin as an adjunct to traditional chemotherapy and radiation in the treatment of brain cancer.
Atmospheric Pressure and Seizure Frequency in the Epilepsy Unit: Preliminary Observations
Authors: Doherty Michael J. , Youn Clover , Gwinn Ryder P. , Haltiner Alan M.
Published: May 2007

Summary:  Objective: To demonstrate that seizure frequency in patients undergoing video EEG telemetry does not correlate with atmospheric pressure (AP) changes.

Method: Historical automated AP data from weather stations in the Seattle Metropolitan area were correlated to seizure frequency and type in consecutive patients undergoing video EEG telemetry at our institution from April 2005–April 2006. Daily maximum, minimum and range of atmospheric pressures were correlated to daily number of events (seizures, pseudoseizures, unknown) per patient. Alternatively, whether or not events occurred during a change of greater or less than 5.5 mBar per day were used to evaluate odds ratios of events occurring.

Results: Of 191 patients, 96 were diagnosed with epilepsy, 60 with pseudoseizures, and 40 had different diagnoses. A total of 159 seizures, 59 pseudoseizures, and 40 unknown events occurred. No correlation between daily mean, maximum or minimum pressure change with seizure or other event frequency was seen. With increased daily AP range an increase in daily seizure per known seizure patient occurred (P = 0.03). Patients with known epilepsy showed an OR of a seizure occurring of 2.80 (95% CI 1.22–6.42 P = 0.02) if pressure changed more than 5.5 mBar that day.

Conclusions: Surprisingly, in patients with known epilepsy, increased seizure frequency occurred with changes in barometric pressure, particularly over 5.5 mBar range per day. Speculative mechanisms of AP change on seizure susceptibility are discussed.
Area‐Specific Resonance of Excitatory Networks in Neocortex: Control by Outward Currents
Authors: Castro‐Alamancos Manuel A. , Tawara‐Hirata Yoshie
Published: May 2007

Summary:  During disinhibition or low [Mg++]o buffer, 7–14 Hz (∼10 Hz) oscillations are generated by excitatory networks of interconnected pyramidal cells in motor (agranular) cortex but are absent in barrel (granular) cortex. Here we studied if the inability of barrel cortex to produce ∼10 Hz oscillations during these conditions is because barrel cortex networks lack the necessary cellular mechanisms or, alternatively, because those mechanisms are inhibited by outward currents. The results show that blockers of slowly inactivating voltage‐dependent K+ currents unmask ∼10 Hz oscillations in barrel cortex, and this occurs in unison with the unmasking of intrinsic inward Ca++ currents that are kept suppressed by the outward currents. Moreover, the ∼10 Hz oscillations unmasked in barrel cortex occur independently in upper and lower layers indicating that the ∼10 Hz oscillation mechanisms are kept suppressed in multiple networks. The results reveal that the propensity of distinct excitatory networks of neocortex to generate epileptiform oscillatory activities is controlled by outward currents.
A Randomized, Double‐Blind, Placebo‐Controlled Trial of Donepezil to Improve Memory in Epilepsy
Authors: Hamberger Marla J. , Palmese Christina A. , Scarmeas Nikolaos , Weintraub David , Choi Hyunmi , Hirsch Lawrence J.
Published: May 2007

Summary:  Purpose: To determine whether an acetylcholinesterase inhibitor, such as donepezil, would improve memory or other cognitive/psychological functions in epilepsy patients with subjective memory complaints.

Methods: Twenty‐three epilepsy patients with subjective memory difficulty were randomized to either 3 months of donepezil (10 mg/day) or 3 months of placebo treatment, and then crossed over to the other treatment arm. Patients and physicians were blinded to treatment phase throughout data acquisition. Assessment of memory and other cognitive functions, subjective memory, mood, and self‐rated quality of life (QOL) and social functioning was performed at baseline and following completion of both treatment phases. Seizure frequency and severity as well as treatment emergent adverse effects were also monitored.

Results: Donepezil treatment was not associated with improvement in memory or other cognitive functions, mood, social functioning or QOL. Comparable increases in self‐rated memory functioning relative to baseline were evident during donepezil and placebo phases. Donepezil treatment was not associated with increased seizure frequency or severity. Similar to group results, analysis of change within individual patients as a function of treatment phase also showed neither significant benefit nor detriment associated with donepezil.

Conclusion: This study found no benefit on memory or other cognitive/psychological functions in a heterogeneous group of epilepsy patients with subjective memory difficulty. Further investigation would be required to determine whether individual patients, or those with particular epilepsy syndromes, might benefit from donepezil or other acetylcholinesterase inhibitors, or if a higher dosage might be effective.
Substantial Thalamostriatal Dopaminergic Defect in Unverricht‐Lundborg Disease
Authors: Korja Miikka , Kaasinen Valtteri , Lamusuo Salla , Parkkola Riitta , Någren Kjell , Marttila Reijo J.
Published: May 2007

Summary:  Purpose: Unverricht‐Lundborg disease (ULD) is currently classified as progressive myoclonus epilepsy. Myoclonus, the characteristic symptom in ULD, suggests that dopamine neurotransmission may be involved in the pathophysiology of ULD. Our purpose was to examine brain dopaminergic function in ULD patients.

Methods: Four genetically and clinically diagnosed ULD patients and eight healthy controls were scanned with [11C]raclopride‐PET. PET images were coregistered to individual 1.5T MR images and region‐of‐interest analysis was performed for the striatum and thalamus. Standardized uptake values and individual voxel‐wise binding potential maps of the patients and controls were also analyzed.

Results: ULD patients had markedly higher (31–54%) dopamine D2‐like receptor availabilities than healthy controls in both the striatum and the thalamus. The proportionally highest binding potentials were detected in the thalamus. There were no significant differences in the cerebellar uptake of [11C]raclopride in ULD patients versus healthy controls. Voxel‐based results were in accordance with the region‐of‐interest analysis.

Conclusions: These results suggest that dopaminergic modulation at the level of the striatum and thalamus could be a crucial factor contributing to the symptoms of ULD. In the light of our data, we propose that ULD with dopamine dysfunction and dyskinetic symptoms shares certain pathophysiological mechanisms with classical movement disorders. Future studies are therefore warranted to study the effect of dopaminergic pharmacotherapy in ULD.
Line Transect Methods for Plant Surveys
Authors: Buckland S. T. , Borchers D. L. , Johnston A. , Henrys P. A. , Marques T. A.
Published: May 2007

SummaryInterest in surveys for monitoring plant abundance is increasing, due in part to the need to quantify the rate of loss of biodiversity. Line transect sampling offers an efficient way to monitor many species. However, the method does not work well in some circumstances, for example on small survey plots, when the plant species has a strongly aggregated distribution, or when plants that are on the line are not easily detected. We develop a crossed design, together with methods that exploit the additional information from such a design, to address these problems. The methods are illustrated using data on a colony of cowslips.
A Class of Markov Models for Longitudinal Ordinal Data
Authors: Lee Keunbaik , Daniels Michael J.
Published: May 2007

SummaryGeneralized linear models with serial dependence are often used for short longitudinal series.Heagerty(2002,Biometrics58,342–351) has proposed marginalized transition models for the analysis of longitudinal binary data. In this article, we extend this work to accommodate longitudinal ordinal data. Fisher‐scoring algorithms are developed for estimation. Methods are illustrated on quality‐of‐life data from a recent colorectal cancer clinical trial.
Regression Analysis of Panel Count Data with Dependent Observation Times
Authors: Sun Jianguo , Tong Xingwei , He Xin
Published: May 2007

Summary Panel count data often occur in long‐term studies that concern occurrence rate of a recurrent event. Methods have been proposed for regression analysis of panel count data, but most of the existing research focuses on situations where observation times are independent of longitudinal response variables and therefore rely on conditional inference procedures given the observation times. This article considers a different situation where the independence assumption may not hold. That is, the observation times and the response variable may be correlated. For inference, estimating equation approaches are proposed for estimation of regression parameters and both large and finite sample properties of the proposed estimates are established. An illustrative example from a cancer study is provided.
FTY720 attenuates accumulation of EMAP‐II+ and MHC‐II+ monocytes in early lesions of rat traumatic brain injury
Authors: Zhang Zhiyuan , Zhang Zhiren , Fauser Uwe , Artelt Matthias , Burnet Michael , Schluesener Hermann J.
Published: May 2007

FTY720 (Fingolimod) is a novel type of immunosuppressive agent inhibiting lymphocyte egress from secondary lymphoid tissues thereby causing peripheral lymphopenia. FTY720 can inhibit macrophage infiltration into inflammatory lesions under pathological conditions. FTY720 has been clinically evaluated for prophylaxis of allograft rejection and treatment of multiple sclerosis, showing promising immunosuppressive effects. A robust inflammatory response after traumatic brain injury (TBI) plays an important role in the secondary or delayed injuries of TBI. Here we have investigated by immunohistochemistry in a rat TBI model the effects of FTY720 on early cell accumulation into the inflammatory tissue response and on expression of major histo‐compatibility complex class II (MHC‐II) and endothelial‐monocyte activating polypeptide II (EMAP‐II). Accumulation of MHC‐II+ or EMAP‐II+ cells became significant 1 day after injury and continuously increased during the early time periods. Further, double‐staining experiments confirmed that the major cellular sources of MHC‐II were reactive macrophages, however MHC‐II+ cells only constituted a small subpopulation of reactive macrophages. Immediately after TBI, peripheral administration of FTY720 (1 mg/kg in 1 mL saline, every second day) significantly attenuated the accumulation of MHC‐II+ macrophages from Day 1 to 4 and significantly attenuated the accumulation of EMAP‐II+ macrophages/microglia at Day 4. Our findings show that FTY720 attenuates early accumulation of EMAP‐II+ and MHC‐II+ reactive monocytes following TBI, indicating that FTY720 might be a drug candidate to inhibit brain inflammatory reaction following TBI.
5′AMP‐activated protein kinase α deficiency enhances stress‐induced apoptosis in BHK and PC12 cells
Authors: Shaw Margaret M. , Gurr Werner K. , McCrimmon Rory J. , Schorderet Daniel F. , Sherwin Robert S.
Published: May 2007

5′AMP‐activated protein kinase (AMPK) activation occurs under a variety of stress conditions but the role of this enzyme in the promotion or inhibition of stress‐induced cell death is unclear. To address this issue, we transformed two different cell lines with shRNA‐expressing plasmids, targeting the alpha subunit of AMPK, and verified AMPKα downregulation. The cell lines were then stressed by exposure to medium without glucose (PC12 cells) or with the viral thymidine kinase‐specific DNA replication inhibitors: acyclovir, penciclovir and ganciclovir (herpes simplex virus thymidine kinase‐expressing Baby Hamster Kidney cells). In non‐AMPK‐downregulated cells, these stress treatments induced AMPK upregulation and phosphorylation, leaving open the question whether the association of AMPK activation with stress‐induced cell death reflects a successful death‐promoting or an ineffective death‐inhibiting activity. In AMPKα‐deficient cells (expressing AMPKα‐specific shRNAs or treated with Compound C) exposure to low glucose medium or DNA replication inhibitors led to an enhancement of cell death, indicating that, under the conditions examined, the role of activated AMPK is not to promote, but to protect from or delay stress‐induced cell death.
Gene transfer strategies in tissue engineering
Authors: Bleiziffer Oliver , Eriksson Elof , Yao Feng , Horch Raymund E. , Kneser Ulrich
Published: May 2007

Introduction

Methods of gene delivery

Gene delivery from scaffolds for tissue engineering

Gene therapy applications in tissue engineering

Outlook

Aiming for regeneration of severed or lost parts of the body, the combined application of gene therapy and tissue engineering has received much attention by regenerative medicine. Techniques of molecular biology can enhance the regenerative potential of a biomaterial by co‐delivery of therapeutic genes, and several different strategies have been used to achieve that goal. Possibilities for application are many‐fold and have been investigated to regenerate tissues such as skin, cartilage, bone, nerve, liver, pancreas and blood vessels. This review discusses advantages and problems encountered with the different gene delivery strategies as far as they relate to tissue engineering, analyses the positive aspects of polymeric gene delivery from matrices and discusses advances and future challenges of gene transfer strategies in selected tissues.