bluuebunny/crossref_metadata_2025 huggingface dataset:
Microarchitectural and Physical Changes During Fetal Growth in Human Vertebral Bone
Authors: Nuzzo S , Meneghini C , Braillon P , Bouvier R , Mobilio S , Peyrin F
Published: April 2006

The ossification process in human vertebra during the early stage of its formation was studied by X-ray diffraction (XRD) and X-ray microtomography (μCT) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Twenty-two samples taken from vertebral ossification centers of human fetal bone (gestational age ranging between 16 and 26 weeks) were investigated. The analysis of three-dimensional images at high spatial resolution (∼10 and ∼2 μm) allows a detailed quantitative description of bone microarchitecture. A denser trabecular network was found in fetal bone compared with that of adult bone. The images evidenced a global isotropic structure clearly composed of two regions: a central region (trabecular bone) and a peripheral region (immature bone). XRD experiments evidenced hydroxyapatite-like crystalline structure in the mineral phase at any fetal age after 16 weeks. Interestingly, the analysis of XRD patterns highlighted the evolution of crystalline structure of mineralized bone as a function of age involving the growth of the hydroxyapatite crystallites.
p21WAF1/CIP1 Acts as a Brake in Osteoblast Differentiation
Authors: Bellosta Paola , Masramon Laia , Mansukhani Alka , Basilico Claudio
Published: April 2006

Continuous fibroblast growth factor signaling inhibits the differentiation of primary osteoblasts and osteoblastic cell lines. We studied the expression of several cell cycle regulatory molecules in response to fibroblast growth factor, and found that fibroblast growth factor strongly upregulates the expression of p21WAF1/CIP1, a CDK inhibitor that has also been implicated in the regulation of apoptosis and cell differentiation. To test the hypothesis that p21 mediated the fibroblast growth factor effects on osteoblasts, we studied the differentiation of primary osteoblasts and osteoblastic cell lines derived from p21 null mice in the presence or absence of fibroblast growth factor. While the results obtained indicate that p21 is not the major mediator of the inhibition of osteoblast differentiation by fibroblast growth factor, we found that p21 per se acts as a brake on osteoblast proliferation and differentiation. p21 is strongly downregulated during differentiation and is highly expressed in osteoblastic cell lines expressing activated FGFR2, which do not differentiate. p21 null osteoblasts differentiate faster than wild-type cells, are more susceptible to the differentiation-promoting action of BMP-2, and undergo increased differentiation-related apoptosis. Furthermore, transient overexpression of p21 from an adenovirus vector delayed the onset of differentiation both in wild-type and in p21 null osteoblasts. These results highlight a new function for p21 in osteoblast differentiation.
Distinct Phases of Coordinated Early and Late Gene Expression in Growth Plate Chondrocytes in Relationship to Cell Proliferation, Matrix Assembly, Remodeling, and Cell Differentiation
Authors: Tchetina E , Mwale F , Poole Ar
Published: April 2006

Although much has been learned about growth plate development and chondrocyte gene expression during cellular maturation and matrix remodeling in the mouse, there has been a limited study of the interrelationships of gene expression between proteinases, growth factors, and other regulatory molecules in the mouse and in other species. Here we use RT-PCR of sequential transverse sections to examine the expression profiles of genes involved in chondrocyte growth, differentiation, matrix assembly, remodeling, and mineralization in the bovine proximal tibial growth plate. Specifically, we studied the expression of genes encoding COL2A1 and COL10A1, the latter a marker of cellular hypertrophy, the matrix metalloproteinases (MMP), MMP-13 and MMP-9, as well as the transcriptional factors, Sox9 and Cbfa1, the growth factors basic fibroblast growth factor (bFGF), parathyroid hormone-related peptide (PTHrP), transforming growth factor (TGF)β1, and β2, Indian hedgehog (Ihh), and the matrix protein osteocalcin. These were analyzed in relationship to cell division defined by cyclin B2 expression. Two peaks of gene expression activity were/observed. One was transient, limited, and located immediately before and at the onset of cyclin B2 expression in the early proliferative zone. The other was generally much more pronounced and was located in the early hypertrophic zone. The upregulation of expression of COL2A1, its transcriptional activator Sox9, osteocalcin, MMP-13, and TGFβ2 was observed immediately before and at the onset of cyclin B2 expression and also in the hypertrophic zones. The upregulation of COL10A1, Cbfa1, MMP-9, TGFβ-1, and Ihh gene expression was associated exclusively with the terminal differentiation of chondrocytes at the time of mineral formation in the extracellular matrix. In contrast, bFGF and PTHrP expression was observed in association with the onset of cyclin B2 expression and hypertrophy. This initial cluster of gene expression associated predominantly with matrix assembly and onset of cell proliferation is therefore characterized by expression of regulatory molecules distinct from those involved at hypertrophy. Together these results identify separate phases of coordinated gene expression associated with the development of the physis in endochondral bone formation.
Relationships Between Pharmacokinetics and Rate of Bone Turnover After Intravenous Bisphosphonate (Olpadronate) in Patients With Paget's Disease of Bone
Authors: Cremers Serge CLM , Eekhoff Marelise EMW , Den Hartigh Jan , Hamdy Neveen AT , Vermeij Pieter , Papapoulos Socrates E
Published: April 2006

Bisphosphonates are the treatment of choice of Paget's disease, but variable responses have been reported, and despite the availability of potent bisphosphonates, biochemical remission is not achieved in a substantial number of patients. This may, in part at least, be because of the influence of pharmacokinetics of bisphosphonates on their pharmacodynamics. That is the response of bone turnover to treatment. To address this issue, we examined the pharmacokinetics and pharmacodynamics of the bisphosphonate olpadronate given intravenously to 75 patients with Paget's disease, using a specific assay for olpadronate concentrations in serum and urine. The skeletal uptake of olpadronate varied greatly among patients and ranged between 10% and 90% of the administered dose. The two major determinants of skeletal uptake were renal function and prevalent rate of bone turnover. Serum and urinary data were well described by a physiology-based four-compartment pharmacokinetic model that takes into account the distribution of the bisphosphonate in the bone and its subsequent elimination. Bone turnover was suppressed to well within the normal range in virtually all patients. This, together with the absence of resolution of effect during 1 year, does not allow the construction of an adequate integrated pharmacokinetic/pharmacodynamic model. However, the pharmacokinetic model, described for the first time in Paget's disease, can accurately simulate the amount of bisphosphonate delivered to the skeleton with different dose regimens as well as the amount still present in bone after 1 year. Such approaches can lead to improved patient care and individualization of treatment of Paget's disease with bisphosphonates.
Randomized Trial of Physical Activity and Calcium Supplementation on Bone Mineral Content in 3- to 5-Year-Old Children
Authors: Specker Bonny , Binkley Teresa
Published: April 2006

A meta-analysis of adult exercise studies and an infant activity trial show a possible interaction between physical activity and calcium intake on bone. This randomized trial of activity and calcium supplementation was conducted in 239 children aged 3-5 years (178 completed). Children were randomized to participate in either gross motor or fine motor activities for 30 minutes/day, 5 days per week for 12 months. Within each group, children received either calcium (1000 mg/day) or placebo. Total body and regional bone mineral content by DXA and 20% distal tibia measurements by peripheral quantitative computed tomography (pQCT) were obtained at 0 and 12 months. Three-day diet records and 48-h accelerometer readings were obtained at 0, 6, and 12 months. Higher activity levels were observed in gross motor versus fine motor activity groups, and calcium intake was greater in calcium versus placebo (1354 ± 301 vs. 940 ± 258 mg/day, p < 0.001). Main effects of activity and calcium group were not significant for total body bone mineral content or leg bone mineral content by DXA. However, the difference in leg bone mineral content gain between gross motor and fine motor was more pronounced in children receiving calcium versus placebo (interaction, p = 0.05). Children in the gross motor group had greater tibia periosteal and endosteal circumferences by pQCT compared with children in the fine motor group at study completion (p < 0.05). There was a significant interaction (both p ≤ 0.02) between supplement and activity groups in both cortical thickness and cortical area: among children receiving placebo, thickness and area were smaller with gross motor activity compared with fine motor activity, but among children receiving calcium, thickness and area were larger with gross motor activity. These findings indicate that calcium intake modifies the bone response to activity in young children.
Nulliparity and Fracture Risk in Older Women: The Study of Osteoporotic Fractures
Authors: Hillier Teresa A , Rizzo Joanne H , Pedula Kathryn L , Stone Katie L , Cauley Jane A , Bauer Doug C , Cummings Steven R
Published: April 2006

Whether nulliparity increases fracture risk is unclear from prior studies, which are limited by small samples or lack of measured bone mineral density. No study has evaluated whether the effect of parity differs by skeletal site. We prospectively analyzed the relationship of parity to the risk of incident nontraumatic hip, spine, and wrist fractures in 9704 women aged 65 years or older participating in the Study of Osteoporotic Fractures to determine if parity reduces postmenopausal fracture risk, and if so, if this risk reduction is (1) greater at weight-bearing skeletal sites and (2) independent of bone mineral density. Parity was ascertained by self-report. Incident hip and wrist fractures were determined by physician adjudication of radiology reports (mean follow-up, 9.8 years) and spine fractures by morphometric criteria on serial radiographs. The relationship of parity to hip and wrist fracture was assessed by proportional hazards models. Spine fracture risk was evaluated by logistic regression. Compared with parous women, nulliparous women (n = 1835, 19%) had an increased risk of hip and spine, but not wrist, fractures. In multivariate models, parity remained a significant predictor only for hip fracture. Nulliparous women had a 44% increased risk of hip fractures independent of hip bone mineral density (hazards ratio, 1.44; 95% CI, 1.17-1.78). Among parous women, each additional birth reduced hip fracture risk by 9% (p = 0.03). Additionally, there were no differences in mean total hip, spine, or radial bone mineral density values between nulliparous and parous women after multivariate adjustment. In conclusion, childbearing reduces hip fracture risk by means that may be independent of hip bone mineral density.
A Longitudinal Study of the Effect of Subcutaneous Estrogen Replacement on Bone in Young Women With Turner's Syndrome
Authors: Khastgir Gautam , Studd John WW , Fox Simon W , Jones Julia , Alaghband-Zadeh Jamshid , Chow Jade WM
Published: April 2006

It is desirable that young women with primary ovarian failure achieve normal peak bone mass to reduce the subsequent risk of osteoporosis, and that there are management strategies to replace bone that is already lost. While estrogen (E2) is generally considered to prevent bone loss by suppressing bone resorption, it is now recognized that estrogen also exerts an anabolic effect on the human skeleton. In this study, we tested whether estrogen could increase bone mass in women with primary ovarian failure. We studied the mechanism underlying this by analyzing biochemical markers of bone turnover and iliac crest biopsy specimens obtained before and 3 years after E2 replacement. Twenty-one women with Turner's syndrome, aged 20-40 years, were studied. The T scores of bone mineral density at lumbar spine and proximal femur at baseline were −1.4 and -1.1, respectively. Hormone replacement was given as subcutaneous E2 implants (50 mg every 6 months) with oral medroxy progesterone. Serum E2 levels increased incrementally from 87.5 pM at baseline to 323, 506, 647, and 713 pM after 6 months and 1, 2, and 3 years of hormone replacement therapy (HRT), respectively. The bone mineral density at the lumbar spine and proximal femur increased after 3 years to T scores of -0.2 and -0.4, respectively. The cancellous bone volume increased significantly from 13.4% to 18.8%. There was a decrease in activation frequency, but the active formation period was increased by HRT. There was a significant increase in the wall thickness from 33.4 μm at baseline to 40.9 μm after 3 years of HRT, reflecting an increase in bone formed at individual remodeling units. Although there was an early increase in biochemical markers of bone formation, these declined thereafter. Our results show that estrogen is capable of exerting an anabolic effect in the skeleton of young women with Turner's syndrome and low bone mass.
Bone Malformations in Interleukin-18 Transgenic Mice
Authors: Kawase Yusuke , Hoshino Tomoaki , Yokota Koichi , Kuzuhara Akemi , Nakamura Masanori , Maeda Yu , Nishiwaki Eiji , Zenmyo Michihisa , Hiraoka Koji , Aizawa Hisamichi , Yoshino Kohichiro
Published: April 2006

The in vivo effects of IL-18 on bone metabolism were investigated by histopathology in IL-18 transgenic mice. Deformed cortical bone and decreased turnover rate of lumbar trabecular bone are consistent with increased expression of IFN-γ and IL-18 in the bone marrow.

Interleukin (IL)-18 has been demonstrated to inhibit osteoclastogenesis in an in vitro co-culture system. We investigated the effects of IL-18 overexpression on bone metabolism by comparing bone characteristics in male IL-18 transgenic (TG) mice, which secrete mature murine IL-18 from their B- and T-cells, and their wildtype littermates (WT). Histopathological analysis revealed that the cortical bone of the femur was thinner and more deformed in IL-18 TG mice. Bone histomorphometry showed that the cortical bone area of the mid-diaphysis of the femur and the trabecular bone volume of the lumbar vertebrae were significantly reduced in IL-18 TG mice. IL-18 TG mice also exhibited significantly fewer osteoclasts and a reduced bone formation rate in the trabecular bones of their lumbar vertebrae. Real-time reverse transcriptase-polymerase chain reaction amplification of bone marrow cell mRNA revealed that interferon (IFN)-γ mRNA expression was significantly increased, whereas IL-4 mRNA expression was significantly reduced, in IL-18 TG mice. However, the expression ratio of receptor activator of NFκB ligand and osteoprotegerin mRNA was not significantly altered. Thus, deformed cortical bone and a decreased turnover rate of lumbar trabecular bone are characteristic of IL-18 TG mice, and these features might be associated with the increased expression of IFN-γ and IL-18 in the bone marrow.
Bone Morphogenetic Protein-2 Restores Mineralization in Glucocorticoid-Inhibited MC3T3-E1 Osteoblast Cultures
Authors: Luppen Cynthia A , Smith Elisheva , Spevak Lyudmila , Boskey Adele L , Frenkel Baruch
Published: April 2006

The anti-glucocorticoid potential of BMP-2 in osteoblasts was tested in MC3T3-E1 cells using dexamethasone (1 μM) and rhBMP-2 (10 or 100 ng/ml). rhBMP-2 restored mineralization but not condensation or collagen accumulation. These results demonstrate the potential and limitations of BMPs in counteracting glucocorticoids.

Introduction: Pharmacologic glucocorticoids (GCs) inhibit osteoblast function and induce osteoporosis. Bone morphogenetic proteins (BMPs) stimulate osteoblast differentiation and bone formation. Here we tested the anti-glucocorticoid potential of BMP-2 in cultured osteoblasts.

Materials and Methods: MC3T3-E1 cells were treated with dexamethasone (DEX; 1 μM) and/or recombinant human BMP-2 (rhBMP-2; 10 or 100 ng/ml). Culture progression was characterized by cell cycle profiling, biochemical assays for DNA, alkaline phosphatase (ALP), collagen, and calcium, and by reverse transcriptase-polymerase chain reaction (RT-PCR) of osteoblast phenotypic mRNAs. Mineralization was characterized by Alizarin red and von Kossa staining and by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).

Results: DEX inhibited differentiation-related cell cycle, nodule formation, collagen accumulation, osteocalcin, and BMP-2 gene expression as well as mineralization. Replenishment of GC-inhibited cultures with 10 or 100 ng/ml rhBMP-2 dramatically rescued mineral deposition. The rhBMP-2-rescued mineral was bone-like apatite nearly identical to the mineral of control cultures. The rhBMP-2 rescue was associated with increased mRNA levels for α1(I) collagen, osteocalcin, and Cbfa1 types I and II, as well as ALP activity. In contrast, rhBMP-2 did not rescue the GC-inhibited differentiation-related cell cycle, nodule formation, or collagen accumulation. When administered alone, rhBMP-2 also increased the mRNA levels for α1(I) collagen, osteocalcin, and Cbfa1 types I and II, as well as ALP activity. However, treatment with rhBMP-2 alone inhibited cell cycle progression, nodule formation, and collagen accumulation. Surprisingly, in contrast to its rescue of mineralization in DEX-treated cultures, rhBMP-2 inhibited mineralization in the absence of DEX. In parallel to its bimodal effect on mineralization, rhBMP-2 stimulated endogenous BMP-2 mRNA in the presence of DEX, but inhibited endogenous BMP-2 mRNA in the absence of DEX.

Conclusions: Suppression of BMP-2 gene expression plays a pivotal role in GC inhibition of osteoblast differentiation. However, the inability of rhBMP-2 to rescue the entire osteoblast phenotype suggests BMP-2-independent inhibitory effects of GCs. BMP-2 exerts both positive and negative effects on osteoblasts, possibly depending on the differentiation stage and/or the existing BMP signaling.
Modeling the Formation and Growth of Cracks from Cold-Worked Holes
Authors: Fujimoto WT
Published: April 2006

First generation crack formation and crack growth predictive approaches for cold-worked holes—based on the growth of a single noninteracting crack in a stationary residual stress field—fail to account fully for the physical mechanisms by which cracks form and grow from cold-worked holes. This failure leads in many cases to large differences between predicted and actual lives. Factors not accounted for in first generation approaches include the following: 1. 3-D nature of residual stress field due to mandrel pull-through. 2. Multistage crack growth involving a progressively spreading system of cracks. 3. Multiple potential initial crack sites, and the effect of site upon the multistage crack growth path. 4. Relaxation of the residual stress field due to overloads/underloads, or due to cyclic reyielding from crack growth. 5. Interaction of the hole with adjacent structural elements for multilayer joints. A physics-based second generation methodology for accounting for these factors is described. This methodology separates into individual building blocks each of the various mechanisms controlling the formation and relaxation of residual stresses, and the nucleation and progression of a system of cracks. Because it explicitly models each of these mechanisms, it is capable of eliminating or reducing the uncertainty over the life improvement potential of the cold-working process, allowing the full potential of cold-working to alleviate the aging aircraft problem to be untapped.
Hyperexcitability, Interneurons, and Loss of GABAergic Synapses in Entorhinal Cortex in a Model of Temporal Lobe Epilepsy
Authors: Kumar Sanjay S. , Buckmaster Paul S.
Published: April 2006

Temporal lobe epilepsy is the most common type of epilepsy in adults, and its pathophysiology remains unclear. Layer II stellate cells of the entorhinal cortex, which are hyperexcitable in animal models of temporal lobe epilepsy, provide the predominant synaptic input to the hippocampal dentate gyrus. Previous studies have ascribed the hyperexcitability of layer II stellate cells to GABAergic interneurons becoming “dormant” after disconnection from their excitatory synaptic inputs, which has been reported to occur during preferential loss of layer III pyramidal cells. We used whole-cell recording from slices of entorhinal cortex in pilocarpine-treated epileptic rats to test the dormant interneuron hypothesis. Hyperexcitability appeared as multiple action potentials and prolonged depolarizations evoked in layer II stellate cells of epileptic rats but not controls. However, blockade of glutamatergic synaptic transmission caused similar percentage reductions in the frequency of spontaneous IPSCs in layer II stellate cells of control and epileptic rats, suggesting similar levels of excitatory synaptic input to GABAergic interneurons. Direct recordings and biocytin labeling revealed two major types of interneurons in layer III whose excitatory synaptic drive in epileptic animals was undiminished. Interneurons in layer III did not appear to be dormant; therefore, we tested whether loss of GABAergic synapses might underlie hyperexcitability of layer II stellate cells. Stereological evidence of fewer GABAergic interneurons, fewer gephyrin-immunoreactive punctae, and reduced frequency of spontaneous IPSCs and miniature IPSCs (recorded in tetrodotoxin) confirmed that layer II stellate cell hyperexcitability is attributable, at least in part, to reduced inhibitory synaptic input.
Chronic Oral Nicotine Normalizes Dopaminergic Function and Synaptic Plasticity in 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Lesioned Primates
Authors: Quik Maryka , Chen Li , Parameswaran Neeraja , Xie Xinmin , Langston J. William , McCallum Sarah E.
Published: April 2006

Our recent studies show that chronic oral nicotine partially protects against striatal damage in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated nonhuman primates. To identify the cellular changes associated with this protective action, we investigated the effects of nicotine treatment on stimulus-evoked dopamine release, dopamine turnover, and synaptic plasticity in striatum from lesioned and unlesioned animals. Monkeys were chronically (6 months) treated with nicotine in the drinking water and subsequently lesioned with the dopaminergic neurotoxin MPTP (6 months) while nicotine was continued. Nigrostriatal damage increased nicotinic acetylcholine receptor (nAChR)-mediated fractional dopamine release from residual terminals, primarily through changes in α3*/α6* nAChRs. In contrast, fractional receptor-evoked dopamine release was similar to control in unlesioned and lesioned animals with chronic oral nicotine. Long-term nicotine administration also attenuated the enhanced K+-evoked fractional dopamine release from synaptosomes of MPTP-lesioned animals, suggesting that nicotine treatment had a generalized effect on dopaminergic function. This premise was further supported by experiments showing that nicotine dosing decreased the elevated dopamine turnover that occurs after nigrostriatal damage. We next investigated changes in synaptic plasticity with lesioning and nicotine treatment. Nicotine treatment alone enhanced synaptic plasticity by lowering the threshold for long-term depression (LTD) in the corticostriatal pathway. MPTP lesioning led to a loss of LTD, a measure of short-term synaptic plasticity. In contrast, LTD was preserved in nicotine-treated lesioned animals. Thus, the present data show that the disruptions in striatal dopaminergic function after nigrostriatal damage were attenuated with chronic nicotine administration. These cellular alterations may underlie the ability of nicotine to maintain/restore normal function with nigrostriatal damage.
Anticipatory Movement Timing Using Prediction and External Cues
Authors: Badler Jeremy B. , Heinen Stephen J.
Published: April 2006

Animals often make anticipatory movements to compensate for slow reaction times. Anticipatory movements can be timed using external, sensory cues, or by an internal prediction of when an event will occur. However, it is unknown whether external or internal cues dominate the anticipatory response when both are present. Smooth pursuit eye movements are generated by a motor system heavily influenced by anticipation. We measured pursuit to determine how its timing was influenced when both a predictable event and a visual cue were present. Monkeys tracked a moving target that appeared at a constant time relative to the onset of a fixation point. At a randomized time before target onset, the fixation point disappeared, creating a temporal “gap” that cued impending target motion. We found that the gap onset cue and prediction of target onset together determined pursuit initiation time. We also investigated whether prediction could override the gap onset cue or vice versa by manipulating target onset and, hence, the duration of time that the animal had to estimate to predict it. When target motion began earlier, the pursuit system relied more on prediction to trigger a movement, whereas the cue was more often used when the target moved later. Pursuit latency in previous trials partially accounted for this behavior. The results suggest that neither internal nor external factors dominate to control the anticipatory response and that the relative contributions vary with stimulus conditions. A model in which neuronal anticipation and fixation signals interact can explain the results.
Radial Migration of Superficial Layer Cortical Neurons Controlled by Novel Ig Cell Adhesion Molecule MDGA1
Authors: Takeuchi Akihide , O’Leary Dennis D. M.
Published: April 2006

MAM (meprin/A5 protein/receptor protein tyrosine phosphatase mu) domain glycosylphosphatidylinositol anchor 1 (MDGA1), a unique cell surface glycoprotein, is similar to Ig-containing cell adhesion molecules that influence neuronal migration and process outgrowth. We show in postnatal mice that MDGA1 is expressed by layer 2/3 neurons throughout the neocortex. During development, MDGA1 is expressed in patterns consistent with its expression by migrating layer 2/3 neurons, suggesting a role for MDGA1 in controlling their migration and settling in the superficial cortical plate. To test this hypothesis, we performed loss-of-function studies using RNA interference (RNAi) targeting different sequences of mouse MDGA1. RNAi or empty vectors were coelectroporated with an enhanced green fluorescent protein reporterin uterointo the lateral ventricle at embryonic day 15.5 to transfect progenitors of superficial layer neurons; the distributions of transfected neurons were analyzed late on postnatal day 0. We found a direct correlation between effectiveness of an RNAi in suppressing MDGA1 expression and disrupting migration of superficial layer neurons. An RNAi with no effect on MDGA1 expression has no effect on the migration. In contrast, an RNAi that suppresses MDGA1 expression also blocks proper migration of transfected superficial layer neurons, with essentially all transfected cells found deep in the cortical plate or beneath it. This migration defect is rescued by cotransfection of a rat MDGA1 expression construct along with the effective RNAi, confirming that the RNAi effect is specific to diminishing mouse MDGA1 expression. RNAi transfections of deep layer neurons that do not express MDGA1 do not significantly affect their migration. We conclude that MDGA1 acts cell autonomously to control the migration of MDGA1-expressing superficial layer cortical neurons.
Activity-Dependent Movements of Postsynaptic Scaffolds at Inhibitory Synapses
Authors: Hanus Cyril , Ehrensperger Marie-Virginie , Triller Antoine
Published: April 2006

Dendritic spines show an activity-dependent cytoskeleton-based remodeling coupled with variations in receptor number and the functional properties of excitatory synapses. In this study, we analyzed the dynamics of gephyrin containing inhibitory postsynaptic scaffolds imaging a Venus::gephyrin (VeGe) chimera in dissociated spinal cord neurons. We provide evidence that the postsynaptic scaffolds at mature synapses display a submicrometric rapid lateral motion and are continuously moving on the dendritic shaft. This dynamic behavior is calcium dependent and is controlled by the cytoskeleton. Minute rearrangement within the gephyrin scaffold as well as the scaffold lateral displacements are F-actin dependent. The lateral movements are counteracted by microtubules. Moreover, the action of the potassium channel blocker 4-aminopyridine and receptor antagonists indicate that the dynamics of postsynaptic gephyrin scaffolds are controlled by synaptic activity.
Is Violence Against Women about Women or about Violence?
Authors: Felson Richard B.
Published: April 2006

When men are violent to women, is it a form of sexist oppression? Or are they simply brutes? And are there political reasons to view them one way or the other?
Chess, Cheerleading, Chopin: What Gets You Into College?
Authors: Gabler Jay , Kaufman Jason
Published: April 2006

Do extracurricular activities increase students' likelihood of attending college, including prestigious institutions? Yes, but grades, test scores, and family background still matter more.
Clock Time/Stomach Time
Authors: boisvert raymond d.
Published: April 2006

The stomach embodies one of biology's ways of measuring change. It is a clock. As a dependent entity, the stomach never measures change in isolation. It is heteronymous. Mechanical clocks, by contrast, measure time independently from external events. They are rigorously autonomous. This essay aims to restore stomach time to its proper role. It draws inspiration from the philosopher François Jullien's study of time in Chinese thought, and builds its case via an interpretation of two food-centered paintings: Millet's Angelus, and Hopper's, Nighthawks. The art works allow an exploration of two etymological trajectories giving rise to the senses of time. One, from the root *di, to divide, gives us the English "time." The other, from *ten, to stretch, gives us the Romance family of terms cognate with the Latin tempus. The first suggests that time is a series of instants constantly fading away. The second, more consistent with the Chinese approach, thinks of time as a cluster of opportunities surging toward us. When the former dominates completely, as in our world, a particular anxiety, chronomania, excessive fear of the wasted moment, becomes an existential accompaniment.
A Semiotic Ontology of the Commodity
Authors: Kockelman Paul
Published: April 2006

The commodity is analyzed from a semiotic stance. Rather than systematically unfold a subject‐object dichotomy (via Hegel's history as dialectic), it systematically deploys a sign‐object‐interpretant trichotomy (via Peirce's logic as semiotic). Rather than conflate economic value and linguistic meaning through the lens of Saussure s semiology, it uses Peirce's semiotic to provide a theory of meaning that is general enough to include commodities and utterances as distinct species. Rather than relegate utility and measure to the work of history (as per the opening pages of Marx's Capital), these are treated as essential aspects of political economy. And rather than focus on canonical 19th‐century commodities (such as cotton, iron, and cloth), the analysis is designed to capture salient features of modern immaterial commodities (such as affect, speech acts, and social relations).
African American English: Linguistic Introduction
Authors: Alim H. Samy
Published: April 2006

African American English: Linguistic Introduction By Lisa Green. Cambridge. Cambridge University Press. 2002.
An Introduction to the Shoshoni Language: Dammen Daigwape
Authors: Dayley Jon P.
Published: April 2006

An Introduction to the Shoshoni Language: Dammen Daigwape. By Drusilla Gould and Christopher Loether. Salt Lake City. The University of Utah Press. 2002.
Benjamin Britten, the “National Faith,” and the Animation of History in 1950s England
Authors: WIEBE HEATHER
Published: April 2006

ABSTRACT This article examines constructions of national Christian tradition in 1950s England, focusing on images of deadness and revivification in two products of the religious drama movement: the York Mystery and other plays presented at the 1951 Festival of Britain, and Benjamin Britten's 1958 children's opera Noye's Fludde.
An Examination of Environmental Factors Associated with Myxobolus cerebralis Infection of Wild Trout in Pennsylvania
Authors: Kaeser Adam J. , Rasmussen Charlotte , Sharpe William E.
Published: April 2006

Salmonid whirling disease, caused by the myxosporean parasite Myxobolus cerebralis, was first observed in the United States in 1956 in central Pennsylvania. The parasite was subsequently discovered at several culture facilities throughout the state, and widespread distribution of this parasite via the stocking of subclinically infected brook trout Salvelinus fontinalis, rainbow trout Oncorhynchus mykiss, and brown trout Salmo trutta has been assumed. Although no monitoring of wild populations occurred until the late 1970s, it is a common belief that epizootics of whirling disease, now realized in the Intermountain West, are unlikely to have occurred in Pennsylvania. We conducted a review of historical information and a synoptic survey aimed at identifying factors that may prevent whirling disease outbreak in this region, reasoning that such information might be useful in identifying management strategies for populations affected by this parasite. Here we present data on parasite prevalence, fish populations, stream attributes, and the genetics of Tubifex tubifex (the obligate oligochaete host for the parasite) to evaluate various hypotheses proposed for low whirling disease impact in the region. We did not find clear associations between factors such as stream gradient, the genetics of T. tubifex populations, or the composition of resident trout populations and the pattern of M. cerebralis occurrence in Pennsylvania. We suggest that this pattern may be best explained by the association between T. tubifex host populations and point sources of organic enrichment. The potential restriction of T. tubifex populations to locations near sources of organic enrichment may be a factor in explaining why whirling disease has not been observed to cause population declines among wild trout in this region and should be further investigated.
Tagging Juvenile Pacific Lamprey with Passive Integrated Transponders: Methodology, Short-Term Mortality, and Influence on Swimming Performance
Authors: Mueller Robert P. , Moursund Russell A. , Bleich Matthew D.
Published: April 2006

This study was conducted to determine the feasibility (i.e., efficiency and nonintrusiveness) of tagging juvenile Pacific lampreys Lampetra tridentata with passive integrated transponder (PIT) tags and to determine any associated impacts on survivorship and swimming ability. Juvenile Pacific lampreys were obtained from the John Day Dam fish collection facility and tests were conducted at the Pacific Northwest National Laboratory in 2001 and 2002. A new PIT-tagging procedure was used to inject 12-mm tags 5 mm posterior to the gill openings. Lampreys were allowed to recover for 3–4 d following surgery before postmortality and swimming tests were conducted. The PIT tagging procedure during 2001 did not include a suture, and 2.6% of the tags were shed after 40 d. During 2002 a single suture was used to close the opening after inserting a tag, and no tag shedding was observed. Overall short-term mortality rates for lampreys 120–155 mm (total length) held for 40 d at 8°C was 2.2% for tagged and 2.7% for untagged fish. Mortality increased significantly when tagged and untagged groups were held in warmer (19–23°C) river water: 50% for tagged and 60% for untagged animals. Lengths did not significantly affect survival for either the tagged or untagged group held in warm water. A fungal infection was observed to be the cause of death when water temperature increased. Swimming tests to determine any adverse effects due to tag insertion showed no significant difference (P = 0.12) between tagged and untagged lampreys for mean burst speed; however, maximum burst speeds were significantly lower for the PIT-tagged group.
Visible Implant Elastomer Color Determination, Tag Visibility, and Tag Loss: Potential Sources of Error for Mark–Recapture Studies
Authors: Curtis Janelle M. R.
Published: April 2006

Errors in visible implant elastomer (VIE) color determination may exert stronger influences on mark–recapture data quality than poor tag visibility and tag loss. I applied individual VIE tags to 567 wild long-snouted seahorses Hippocampus guttulatus using four fluorescent colors (red, orange, green, and yellow). Given VIE tag data were compared with tag data recorded by observers as they released recently tagged individuals back to initial capture locations. During releases, 13.3% of VIE tags were incorrectly read, primarily because of confusions between orange and red markings and between green and yellow markings. Tags were partially invisible in 5% of released individuals; yellow and green markings were the least visible. Whole or partial tag loss was 2.3% within 14 months of tagging. The ability to correctly determine VIE tag colors or detect markings varied among observers and according to the VIE tag color employed, skin color, and shade of the skin color (e.g., light versus dark green). Observer experience did not influence ability to correctly determine VIE colors or detect tags. Pilot studies should precede mark–recapture studies employing multiple VIE colors to identify strategies for reducing confusion among colors in addition to evaluating tag visibility, tag loss, and tag effects on life history rates.
Multicultural Literature and Young Adolescents: A Kaleidoscope of Opportunity
Authors: Landt Susan M.
Published: April 2006

Adolescents seek to understand who they are and where they belong in the world. Quality young adult literature can familiarize them with a broader view of the world, open doors in their minds, and reveal similarities and differences among a multitude of others who have struggled with similar issues. Literature that provides a range of perspectives can broaden young adolescents' vision of self and the world, providing an avenue for reflection and a means for personal development. Quality multicultural literature can also help to interrupt prejudice and misunderstanding by exposing unacknowledged bias and intolerance. Availability of quality young adult literature written by people with a range of perspectives provides all students with affirming images of self and culture.

When selecting multicultural literature, accuracy and authenticity about the cultures portrayed are crucial. Identifying appropriate multicultural literature can be problematic for teachers whose days are already encumbered with multiple tasks. To assist in the process, a guide for evaluating multicultural literature is provided, along with suggestions for substantiating an author's credentials for writing about a specific culture. Examples of quality multicultural literature appropriate for middle‐level students are also included.
Response of Bentgrass Cultivars to Sclerotinia homoeocarpa Isolates Representing 10 Vegetative Compatibility Groups
Authors: Chakraborty Nanda , Chang Taehyun , Casler Michael D. , Jung Geunhwa
Published: April 2006

Dollar spot caused by Sclerotinia homoeocarpa F.T. Bennett is a major disease of turfgrass throughout the world. Current control strategies depend heavily on fungicide application. Host resistance is an alternate management strategy, but a thorough understanding of the pathogen and host interaction is required to utilize it successfully. Seventy‐nine clones of 10 cultivars of creeping (A. stolonifera L.), colonial (A. capillaris L.), dryland (A. castellana Boiss. & Reut.), and velvet (A. canina L.) bentgrass species were inoculated with an isolate of S. homoeocarpa in the greenhouse. A large degree of genetic variation in response to S. homoeocarpa at the species, cultivar, and clone levels was detected. In addition, 18 isolates of S. homoeocarpa representing 10 vegetative compatibility groups (VCGs) were used to inoculate 12 bentgrass cultivars. Disease severity evaluations showed significant difference among bentgrass cultivars and species in their response to dollar spot. The colonial and velvet bentgrass cultivars were significantly less susceptible to all the isolates of S. homoeocarpa compared to the creeping bentgrass cultivars. The isolates of S. homoeocarpa showed significant differences in levels of aggressiveness. However, data from pathogenicity tests indicated a lack of race‐specific interactions. Therefore, turfgrass breeders should be able to select for resistance to one or a few highly virulent isolates of the pathogen, and obtain resistance to a wide array of isolates.
Elevated Atmospheric Carbon Dioxide and Weed Populations in Glyphosate Treated Soybean
Authors: Ziska Lewis H. , Goins Ernie W.
Published: April 2006

Although rising atmospheric carbon dioxide (CO2) is known to stimulate the growth of agronomic weeds, the impact of increasing CO2 on herbicide efficacy has not been elucidated for field‐grown crops. Genetically modified soybean [Glycine max (L.) Merr.] (i.e., Round‐up Ready soybean) was grown over a 2‐yr period at ambient and projected levels of atmospheric carbon dioxide (CO2, 250 μmol mol−1 above ambient), with and without application of the herbicide, glyphosate [N‐(phosphonomethyl)glycine], to assess the impact of rising atmospheric carbon dioxide concentration [CO2] on chemical efficacy of weed control. For both years, soybean showed a significant vegetative response to elevated [CO2], but no consistent effect on seed yield. For 2003, weed populations for all treatments consisted entirely of C4 grasses, with no [CO2] effects on weed biomass (unsprayed plots) or glyphosate efficacy (sprayed plots). However, in 2004, weed populations were mixed and included C3 and C4 broadleaves as well as C4 grasses. In this same year, a significant increase in both C3 broadleaf populations and total weed biomass was observed as a function of [CO2] (unsprayed plots). In addition, a [CO2] by glyphosate interaction was observed with significant C3 broadleaf weed biomass remaining after glyphosate application. Overall, these data emphasize the potential consequences for CO2–induced changes in weed populations, biomass, and subsequent glyphosate efficacy in Round‐up Ready soybean.
A Grief Diagnostic Instrument for General Practice
Authors: Clark Sheila , Marley John , Hiller Janet E. , Leahy Catherine , Pratt Nicole
Published: April 2006

Assisting patients to deal with loss is a major, yet unrecognized, role of general practitioners. Although instruments exist for measuring grief resulting from a given loss, such as bereavement, none exists that detects and measures grief from any loss. This study describes the development of the Grief Diagnostic Instrument for this purpose in general practice patients. Evaluation showed it to be a concise, valid, reliable and sensitive measure, and acceptable to general practice patients. The instrument investigates and measures grief from multiple losses rather than a single loss compared to other grief scales. Suggestions have been made for further validation studies. Its use in future grief research and clinical practice are described.
Death under Control: The Portrayal of Death in Mass Print English Language Magazines in Canada
Authors: Clarke Juanne Nancarrow
Published: April 2006

The purpose of this article is to discuss the portrayal of death in modern North American society in the highest circulating English language magazines available in Canada and published either in the United States or in Canada, in 1991, 1996, and 2001. The prevailing underlying frame/discourse of which there were a number of sub-variants, was the notion of the control of death. Stories focused on people taking control of death by 1) passive and active euthanasia, 2) suicide with political and social motivations and messages, 3) suicide deaths among celebrities and the families of celebrities, 4) dramatic murders, 5) issues in the “right to die movement,” and 6) new techniques and technologies for life extension. There was a very small minority of articles on miscellaneous issues such as death rates and their variation across geographic region, social class, environmental condition, and cause. The article ends with discussion of the ways that this portrayal of death obfuscates the real lack of control most North Americans, particularly those who are poor or “racialized,” have over the timing, or circumstances of death. In addition, as a critical discourse analysis, it discusses the interests that are served by this perspective.
Chekhov's “Three Sisters” at the Gorky Theatre
Authors: Tovstonogov Georgii
Published: April 2006

A classic tends to age, disappear from active repertory, and then revive to meet the spiritual needs of a new audience, no less—and sometimes more—than do contemporary plays.

In recent years, Soviet theatre has increasingly produced the classics. Plays which not long ago saw little more than a dustrag have become the subject of violent debate, making new names for actors and directors.

Venerable academicians, learned literary scholars and theatre historians who have devoted their lives to the study of Russian classics react with divided feelings. They are pleased that their beloved plays once more meet the needs of the day, but are infuriated by what they see as the disrespect of the directors. Some of the older theatre-goers are also unsatisfied with contemporary interpretations of the classics.
Ohorganism: The Lost Years
Authors: Gress Elsa
Published: April 2006

People become myths overnight these days. It is worth looking at the elements of myth and truth in the matter of Tom O'Horgan, not just to save a soul or two, but because the truth in this case is much more interesting. O'Horgan, newly discovered if not newly made director of Hair, Futz, and Tom Paine, and (with England's Brook and Poland's Grotowski) a director who has got something there. But while Brook seems stuck (at least momentarily) in mannerisms and overused-effects, and Grotowski is busy turning theatre into a perpetual wailing wall, O'Horgan manages to make theatre a consistently colorful and often unabashedly joyful experience, with a vitality that even when spurious (which happens), is as catching as the common cold. He is unique, not in method or message, but in his uses of methods and messages: Ohorganism seems the only apt term for what he is doing and being, as none of the common labels quite covers the phenomenon.
Media Freaking
Authors: Hoffman Abbie
Published: April 2006

This sure is fun. You know, the city news bureau here in Chicago, where you can always call and get their version of what's happening, is ST2-8100. You might want to take care of a cat named Jack Lawrence from CBS who threw me out while I was fuckin’ with their teletype machine last night. That was very unfair. I had some good news items. Now, let's see who else is here. The police, there's some good numbers. OK. Now this is a top secret number that like only a few of the top police have. It's the central number for the police station up here in the zoo. They're very fucked up in there. I've been up there, and you think they're organized, well you're full of shit ‘cause their walkie-talkies don't work. I mean they're all stoned up there, tripping over each other, you know, they're rapping, all they want to do is fight and they don't care about all the walkie-talkie shit, they just want to fight, you know.