bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular Changes Underlying Hyperoxia-Induced Delay of White Matter Development
Authors: Schmitz Thomas , Ritter Jonathan , Mueller Susanne , Felderhoff-Mueser Ursula , Chew Li-Jin , Gallo Vittorio
Published: March 2011

Impaired neurological development in premature infants frequently arises from periventricular white matter injury (PWMI), a condition associated with myelination abnormalities. Recently, exposure to hyperoxia was reported to disrupt myelin formation in neonatal rats. To identify the causes of hyperoxia-induced PWMI, we characterized cellular changes in the white matter (WM) using neonatal wild-type, 2–3-cyclic nucleotide 3-phosphodiesterase–enhanced green fluorescent protein (EGFP) and glial fibrillary acidic protein (GFAP)–EGFP transgenic mice exposed to 48 h of 80% oxygen from postnatal day 6 (P6) to P8. Myelin basic protein expression and CC1+oligodendroglia decreased after hyperoxia at P8, but returned to control levels during recovery between P12 and P15. At P8, hyperoxia caused apoptosis of NG2+O4−progenitor cells and reduced NG2+cell proliferation. This was followed by restoration of the NG2+cell population and increased oligodendrogenesis in the WM after recovery. Despite apparent cellular recovery, diffusion tensor imaging revealed WM deficiencies at P30 and P60. Hyperoxia did not affect survival or proliferation of astrocytesin vivo, but modified GFAP and glutamate-aspartate transporter expression. The rate of [3H]-d-aspartic acid uptake in WM tissue was also decreased at P8 and P12. Furthermore, cultured astrocytes exposed to hyperoxia showed a reduced capacity to protect oligodendrocyte progenitor cells against the toxic effects of exogenous glutamate. This effect was prevented by 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide treatment. Our analysis reveals a role for altered glutamate homeostasis in hyperoxia-induced WM damage. Understanding the cellular dynamics and underlying mechanisms involved in hyperoxia-induced PWMI will allow for future targeted therapeutic intervention.
Control of Prestimulus Activity Related to Improved Sensory Coding within a Discrimination Task
Authors: Yoshida Takashi , Katz Donald B.
Published: March 2011

Network state influences the processing of incoming stimuli. It is reasonable to expect, therefore, that animals might adjust cortical activity to improve sensory coding of behaviorally relevant stimuli. We tested this hypothesis, recording single-neuron activity from gustatory cortex (GC) in rats engaged in a two-alternative forced-choice taste discrimination task, and assaying the responses of these same neurons when the rats received the stimuli passively. We found that the task context affected the GC network state (reducing beta- and gamma-band field potential activity) and changed prestimulus and taste-induced single-neuron activity: before the stimulus, the activity of already low-firing neurons was further reduced, a change that was followed by comparable reductions of taste responses themselves. These changes served to sharpen taste selectivity, mainly by reducing responses to suboptimal stimuli. This sharpening of taste selectivity was specifically attributable to neurons with decreased prestimulus activities. Our results suggest the importance of prestimulus activity control for improving sensory coding within the task context.
GABABReceptor Modulation of Voltage-Sensitive Calcium Channels in Spines and Dendrites
Authors: Chalifoux Jason R. , Carter Adam G.
Published: March 2011

Although primarily studied at the cell body, GABABreceptors (GABABRs) are abundant at spines and dendrites of cortical pyramidal neurons, where they are positioned to influence both synaptic and dendritic function. Here, we examine how GABABRs modulate calcium (Ca) signals evoked by action potentials (APs) in spines and dendrites of layer 2/3 pyramidal neurons in mouse prefrontal cortex. We first use two-photon microscopy to show that GABABRs inhibit AP Ca signals throughout the entire dendritic arbor of these neurons. We then use local pharmacology and GABA uncaging to show that dendritic GABABRs also decrease the input resistance, shorten the AP afterdepolarization, and generate inhibitory postsynaptic potentials. However, we find that these electrophysiological effects recorded at the cell body do not correlate with the inhibition of AP Ca signals measured in spines and dendrites. Instead, we use voltage-clamp recordings to show that GABABRs directly inhibit several subtypes of voltage-sensitive calcium channels (VSCCs) in both spines and dendrites. Given the importance of VSCC-mediated Ca signals for neuronal function, our results have implications for the functional role of dendritic GABABRs in the prefrontal cortex and throughout the brain.
Partial Occlusion Modulates Contour-Based Shape Encoding in Primate Area V4
Authors: Bushnell Brittany N. , Harding Philip J. , Kosai Yoshito , Pasupathy Anitha
Published: March 2011

Past studies of shape coding in visual cortical area V4 have demonstrated that neurons can accurately represent isolated shapes in terms of their component contour features. However, rich natural scenes contain many partially occluded objects, which have “accidental” contours at the junction between the occluded and occluding objects. These contours do not represent the true shape of the occluded object and are known to be perceptually discounted. To discover whether V4 neurons differentially encode accidental contours, we studied the responses of single neurons in fixating monkeys to complex shapes and contextual stimuli presented either in isolation or adjoining each other to provide a percept of partial occlusion. Responses to preferred contours were suppressed when the adjoining context rendered those contours accidental. The observed suppression was reversed when the partial occlusion percept was compromised by introducing a small gap between the component stimuli. Control experiments demonstrated that these results likely depend on contour geometry at T-junctions and cannot be attributed to mechanisms based solely on local color/luminance contrast, spatial proximity of stimuli, or the spatial frequency content of images. Our findings provide novel insights into how occluded objects, which are fundamental to complex visual scenes, are encoded in area V4. They also raise the possibility that the weakened encoding of accidental contours at the junction between objects could mark the first step of image segmentation along the ventral visual pathway.
Dopaminergic Modulation of Cortical Inputs during Maturation of Adult-Born Dentate Granule Cells
Authors: Mu Yangling , Zhao Chunmei , Gage Fred H.
Published: March 2011

Adult neurogenesis, a particular form of plasticity in the adult brain, is under dynamic control of neuronal activity mediated by various neurotransmitters. Despite accumulating evidence suggesting that the neurotransmitter dopamine (DA) regulates proliferation of neural precursor cells in the neurogenic zones, whether and how it acts on newly generated neurons that integrate into the established network remains unknown. Using patch-clamp recordings from retrovirus-labeled newborn hippocampal dentate granule cells (DGCs) in acute mouse brain slices, we found that DA not only caused a long-lasting attenuation of medial perforant path (MPP) inputs to the young DGCs, but also decreased their capacity to express long-term potentiation (LTP). In contrast, DA suppressed MPP transmission to mature DGCs to a similar extent but did not influence their LTP expression. This difference was linked to activation of distinct subtypes of DA receptors in DGCs at different developmental stages. Our observations suggest that DA is particularly effective in modulating the activities of hyperexcitable young neurons, which may have important implications for the dentate function as a filter for incoming information to the hippocampus.
Robust Amyloid Clearance in a Mouse Model of Alzheimer's Disease Provides Novel Insights into the Mechanism of Amyloid-β Immunotherapy
Authors: Wang Allan , Das Pritam , Switzer Robert C. , Golde Todd E. , Jankowsky Joanna L.
Published: March 2011

Many new therapeutics for Alzheimer's disease delay the accumulation of amyloid-β (Aβ) in transgenic mice, but evidence for clearance of preexisting plaques is often lacking. Here, we demonstrate that anti-Aβ immunotherapy combined with suppression of Aβ synthesis allows significant removal of antecedent deposits. We treated amyloid-bearing tet-off APP (amyloid precursor protein) mice with doxycycline to suppress transgenic Aβ production before initiating a 12 week course of passive immunization. Animals remained on doxycycline for 3 months afterward to assess whether improvements attained during combined treatment could be maintained by monotherapy. This strategy reduced amyloid load by 52% and Aβ42 content by 28% relative to pretreatment levels, with preferential clearance of small deposits and diffuse Aβ surrounding fibrillar cores. We demonstrate that peripherally administered anti-Aβ antibody crossed the blood–brain barrier, bound to plaques, and was still be found associated with a subset of amyloid deposits many months after the final injection. Antibody accessed the brain independent of plasma Aβ levels, where it enhanced microglial internalization of aggregated Aβ. Our data support a mechanism by which passive immunization acts centrally to stimulate microglial phagocytosis of aggregated Aβ, but is opposed by the continued aggregation of newly secreted Aβ. By arresting the production of Aβ, combination therapy allows microglial clearance to work from a static amyloid burden toward a significant reduction in plaque load. Our findings suggest that combining two therapeutic approaches currently in clinical trials may improve neuropathological outcome over either alone.
SIRT1 Regulation of Wakefulness and Senescence-Like Phenotype in Wake Neurons
Authors: Panossian Lori , Fenik Polina , Zhu Yan , Zhan Guanxia , McBurney Michael W. , Veasey Sigrid
Published: March 2011

Wake neurons in the basal forebrain and brainstem provide critical inputs to optimize alertness and attention. These neurons, however, evidence heightened vulnerability to a diverse array of metabolic challenges, including aging. SIRT1 is an nicotinamide adenine dinucleotide responsive deacetylase serving diverse adaptive responses to metabolic challenges, yet this metabolic rheostat may be downregulated under conditions of significant oxidative stress. We hypothesized that SIRT1 might serve as a critical neuroprotectant for wake neurons in young animals but that this protectant would be lost upon aging, rendering the neurons more vulnerable to metabolic insults. In this collection of studies, we first established the presence of nuclear SIRT1 in wake neurons throughout the forebrain and brainstem. Supporting functional and behavioral roles for SIRT1 in wake–active neurons, transgenic whole animal, and conditional loss of brain SIRT1 in the adult mouse impart selective impairments in wakefulness, without disrupting non-rapid eye movement or rapid eye movement sleep. Populations of wake neurons, including the orexinergic, locus ceruleus, mesopontine cholinergic, and dopaminergic wake neurons, evidence loss of dendrites and neurotransmitter synthesis enzymes and develop accelerated accumulation of lipofuscin, consistent with a senescence-like phenotype in wake neurons. Normal aging results in a progressive loss of SIRT1 in wake–active neurons, temporally coinciding with lipofuscin accumulation. SIRT1 is a critical age-sensitive neuroprotectant for wake neurons, and its deficiency results in impaired wakefulness.
Cocaine Withdrawal Impairs Metabotropic Glutamate Receptor-Dependent Long-Term Depression in the Nucleus Accumbens
Authors: Huang Chiung-Chun , Yeh Che-Ming , Wu Mei-Ying , Chang Alice Y. W. , Chan Julie Y. H. , Chan Samuel H. H. , Hsu Kuei-Sen
Published: March 2011

Neuroadaptation in the nucleus accumbens (NAc), a central component of the mesolimbic dopamine (DA) system, has been implicated in the development of cocaine-induced psychomotor sensitization and relapse to cocaine seeking. However, little is known about the cellular and synaptic mechanisms underlying such adaptation. Using a mouse model of behavioral sensitization, we show that animals withdrawn from repeated cocaine exposure have a selective deficit in the ability to elicit metabotropic glutamate receptor (mGluR)-dependent long-term depression (LTD) in the shell of the NAc in response to bath application of the group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (DHPG). Experiments conducted in the presence of the selective mGluR1 antagonists 7-(hydroxyimino)cyclopropachromen-carboxylate ethyl ester and (S)-(+)-α-amino-4-carboxy-2-methylbenzeneacetic acid, or the mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine, demonstrated that the impaired DHPG-LTD is likely attributable to a loss of mGluR5 function. Quantitative real-time reverse transcriptase-PCR and Western blot analysis revealed significant downregulation of mGluR5, but not mGluR1, mRNA and protein levels in the NAc shell. The inhibitory effect of repeated cocaine exposure on DHPG-LTD was selectively prevented when cocaine was coadministered with the selective D1-like DA receptor antagonist (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine. Furthermore, the levels of brain-derived neurotrophic factor (BDNF) protein in the NAc shell increased progressively after cocaine withdrawal, and the impairment of DHPG-LTD in the NAc shell was not found in slices from BDNF-knock-out mice after cocaine withdrawal. These results suggest that withdrawal from repeated cocaine exposure may result in increased BDNF levels in the NAc shell, which leads to a selective downregulation of mGluR5 and thereby impairs the induction of mGluR-dependent LTD.
Delayed Postnatal Loss of P/Q-Type Calcium Channels Recapitulates the Absence Epilepsy, Dyskinesia, and Ataxia Phenotypes of GenomicCacna1AMutations
Authors: Mark Melanie D. , Maejima Takashi , Kuckelsberg Denise , Yoo Jong W. , Hyde Robert A. , Shah Viral , Gutierrez Davina , Moreno Rosa L. , Kruse Wolfgang , Noebels Jeffrey L. , Herlitze Stefan
Published: March 2011

Inherited loss of P/Q-type calcium channel function causes human absence epilepsy, episodic dyskinesia, and ataxia, but the molecular “birthdate” of the neurological syndrome and its dependence on prenatal pathophysiology is unknown. Since these channels mediate transmitter release at synapses throughout the brain and are expressed early in embryonic development, delineating the critical circuitry and onset underlying each of the emergent phenotypes requires targeted control of gene expression. To visualize P/Q-type Ca2+channels and dissect their role in neuronal networks at distinct developmental stages, we created a novel conditionalCacna1aknock-in mouse by inserting the floxed green fluorescent protein derivative Citrine into the first exon ofCacna1aand then crossed it with a postnatally expressing PCP2-Cre line for delayed Purkinje cell (PC) gene deletion within the cerebellum and sparsely in forebrain (purky). PCs inpurkymice lacked P/Q-type calcium channel protein and currents within the first month after birth, displayed altered spontaneous firing, and showed impaired neurotransmission. Unexpectedly, adultpurkymice exhibited the full spectrum of neurological deficits seen in mice with genomicCacna1aablation. Our results show that the ataxia, dyskinesia, and absence epilepsy caused by inherited disorders of the P/Q-type channel arise from signaling defects beginning in late infancy, revealing an early window of opportunity for therapeutic intervention.
Histone Deacetylase Inhibitors Preserve White Matter Structure and Function during Ischemia by Conserving ATP and Reducing Excitotoxicity
Authors: Baltan Selva , Murphy Sean P. , Danilov Camelia A. , Bachleda Amelia , Morrison Richard S.
Published: March 2011

The importance of white matter (WM) injury to stroke pathology has been underestimated in experimental animal models and this may have contributed to the failure to translate potential therapeutics into the stroke clinic. Histone deacetylase (HDAC) inhibitors are neuroprotective and also promote neurogenesis. These properties make them ideal candidates for stroke therapy. In a pure WM tract (isolated mouse optic nerve), we show that pan- and class I-specific HDAC inhibitors, administered before or after a period of oxygen and glucose deprivation (OGD), promote functional recovery of axons and preserve WM cellular architecture. This protection correlates with the upregulation of an astrocyte glutamate transporter, delayed and reduced glutamate accumulation during OGD, preservation of axonal mitochondria and oligodendrocytes, and maintenance of ATP levels. Interestingly, the expression of HDACs 1, 2, and 3 is localized to astrocytes, suggesting that changes in glial cell gene transcription and/or protein acetylation may confer protection to axons. Our findings suggest that a therapeutic opportunity exists for the use of HDAC inhibitors, targeting mitochondrial energy regulation and excitotoxicity in ischemic WM injury.
Factors Controlling the Input–Output Relationship of Spherical Bushy Cells in the Gerbil Cochlear Nucleus
Authors: Kuenzel Thomas , Borst J. Gerard G. , van der Heijden Marcel
Published: March 2011

Despite the presence of large endbulb inputs, the spherical bushy cells (SBCs) of the rostral anteroventral cochlear nucleus do not function as simple auditory relays. We used the good signal-to-noise ratio of juxtacellular recordings to dissect the intrinsic and network mechanisms controlling the input–output relationship of SBCs in anesthetized gerbils. The SBCs generally operated close to action potential (AP) threshold and showed no evidence for synaptic depression, suggesting that the endbulbs of Held have low release probabilityin vivo. Analysis of the complex waveforms suggested that in the absence of auditory stimulation, postsynaptic spike depression and stochastic fluctuations in EPSP size were the main factors determining jitter and reliability of the endbulb synapse. During auditory stimulation, progressively larger EPSPs were needed to trigger APs at increasing sound intensities. Simulations suggested hyperpolarizing inhibition could explain the observed decrease in EPSP efficacy. Synaptic inhibition showed a delayed onset and generally had a higher threshold than excitatory inputs, but otherwise inhibition and excitation showed mostly overlapping frequency–response areas. The recruitment of synaptic inhibition caused postsynaptic spikes to be preferentially triggered by well-timed, large EPSPs, resulting in improved phase locking despite more variable EPSP–AP latencies. Our results suggest that the lack of synaptic depression, caused by low release probability, and the apparent absence of sound-evoked synaptic inhibition at low sound intensity maximize sensitivity of SBCs. At higher sound intensities, the recruitment of synaptic inhibition constrains their firing rate and optimizes their temporal precision.
11β-Hydroxysteroid Dehydrogenase Type 1 Deficiency Prevents Memory Deficits with Aging by Switching from Glucocorticoid Receptor to Mineralocorticoid Receptor-Mediated Cognitive Control
Authors: Yau Joyce L. W. , Noble June , Seckl Jonathan R.
Published: March 2011

Local brain amplification of glucocorticoids (GCs) by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays a pivotal role in age-related memory deficits. 11β-HSD1 deficient mice are protected from spatial memory impairments with aging, but the underlying mechanisms are unknown. To determine which brain receptors [high-affinity mineralocorticoid receptors (MRs) or low-affinity glucocorticoid receptors (GRs)] are involved, spatial memory was measured in aged 11β-HSD1−/−mice before and during intracerebroventricular infusion (10 d) of spironolactone (MR antagonist) or RU486 (GR antagonist). Aged C57BL/6J control mice showed impaired spatial memory in the Y-maze; this improved with GR blockade, while MR blockade had no effect. In contrast, aged 11β-HSD1−/−mice showed intact spatial memory that became impaired with MR blockade, but not GR blockade. Hippocampal MR and GR mRNA expression and plasma corticosterone levels were not significantly altered with spironolactone or RU486 in either genotype. These data support the notion that 11β-HSD1 deficiency in aging mice leads to lower intracellular GC concentrations in brain, particularly in the hippocampus, which activate predominantly MRs to enhance memory, while in aging C57BL/6J controls, the increased intracellular GCs saturate MRs and activate predominantly GRs, thus impairing memory, an effect reversed by GR blockade.
FACS Identifies Unique Cocaine-Induced Gene Regulation in Selectively Activated Adult Striatal Neurons
Authors: Guez-Barber Danielle , Fanous Sanya , Golden Sam A. , Schrama Regina , Koya Eisuke , Stern Anna L. , Bossert Jennifer M. , Harvey Brandon K. , Picciotto Marina R. , Hope Bruce T.
Published: March 2011

Numerous studies with the neural activity marker Fos indicate that cocaine activates only a small proportion of sparsely distributed striatal neurons. Until now, efficient methods were not available to assess neuroadaptations induced specifically within these activated neurons. We used fluorescence-activated cell sorting (FACS) to purify striatal neurons activated during cocaine-induced locomotion in naive and cocaine-sensitizedcfos-lacZtransgenic rats. Activated neurons were labeled with an antibody against β-galactosidase, the protein product of the lacZ gene. Cocaine induced a unique gene expression profile selectively in the small proportion of activated neurons that was not observed in the nonactivated majority of neurons. These genes included altered levels of the immediate early genesarc,fosB, andnr4a3, as well as genes involved in p38 MAPK signaling and cell-type specificity. We propose that this FACS method can be used to study molecular neuroadaptations in specific neurons encoding the behavioral effects of abused drugs and other learned behaviors.
A Three-Year Longitudinal Functional Magnetic Resonance Imaging Study of Performance Monitoring and Test-Retest Reliability from Childhood to Early Adulthood
Authors: Koolschijn P. Cédric M. P. , Schel Margot A. , de Rooij Mark , Rombouts Serge A. R. B. , Crone Eveline A.
Published: March 2011

Previous cross-sectional functional magnetic resonance imaging studies have shown that performance monitoring functions continue to develop well into adolescence, associated with increased activation in brain regions important for cognitive control (prefrontal cortex, anterior cingulate cortex, and parietal cortex). To date, however, the development of performance monitoring has not yet been studied longitudinally, which leaves open the question whether changes can be detected within individuals over time. In the present study, human boys and girls, between ages 8 and 27 years, performed a child-friendly rule-switch task in the scanner on two occasions ∼3.5 years apart. Change versus stability was examined using two methods: (1) repeated-measures analyses and (2) test-retest reliabilities of blood oxygenation level-dependent responses. Results showed that with increasing age, participants performed better on the task. The changes in neural activation associated with the processing of performance feedback were, however, more reliably correlated with changes in performance than with age. Test-retest reliability was at least fair to good for adults and adolescents, but poor to fair for the youngest age group. Substantially more variability was observed in the pattern and magnitude of children compared with adults, which may be interpreted as proxy for developmental change. Together, the results show that (1) change within individuals is variable, and more so for children than for adolescents and adults, and (2) performance is a better predictor for change in neural activation over time. These findings set the stage for studying developmental change in the perspective of multiple predictors, rather than solely by divisions based on age groups.
New99mTc(CO)3(NNO) complexes in the development of 5HT1Areceptor imaging agents
Authors: Chiotellis A. , Tsoukalas C. , Pelecanou M. , Pirmettis I. , Papadopoulos M.
Published: March 2011

In this work we report the synthesis, characterization and biological evaluation of two new neutral tricarbonylfac-M(CO)3(NNO) (M=Re,99mTc) derivatives of WAY-100635 as potential99mTc agents for thein vivoimaging of 5HT1Areceptors. The new pharmacophore NNO ligands are based on the picolylamineN,N-diacetic acid (PADA) ligand and their synthesis was achieved through the PADA anhydride, showing thus the applicability of this synthetic approach, developed in our laboratory, for the incorporation of bioactive amines in the PADA molecule and the development of target specific radiopharmaceuticals. The rhenium complexes were synthesized using [NEt4]2[Re(CO)3Br3] as a precursor and fully characterized by elemental analysis and spectroscopic methods. The analogous technetium-99m complexes were also prepared quantitatively using the [99mTc(CO)3(H2O)3]+precursor and their structure corroborated by means of the rhenium complexes. The lipophilicity of the Tc complexes is in the range normally accepted for substances to be able to cross the BBB. Competition binding tests showed moderate affinity for the 5HT1Areceptors, with IC50values at the nanomolar range (30 and 116 nM). Biodistribution in healthy animals was characterized by high initial blood and liver uptake and fast blood and tissue depuration with excretion taking place mainly through the hepatobiliary system. None of the new complexes showed any significant brain uptake, suggesting that the ability of a compound to cross the BBB is determined by more factors than charge, lipophilicity and size.
Solubility of ThO2·xH2O(am) in the presence of gluconate
Authors: Colàs E. , Grivé M. , Rojo I. , Duro L.
Published: March 2011

Thorium complexation with gluconate has been studied from solubility experiments at gluconate concentrations between 10−6and 10−1 mol/l, with pHcbetween 9 and 13 andI=0.5 M (NaClO4). Solubility experiments indicate the formation of a 1:1 thorium:gluconate complex. The stability constant for this species, extrapolated toI=0 by using the SIT (specific interaction theory), has been determined to be log10Kº=−11.5 ± 0.6 for the reaction: Th4++ GH4−+ 2H2O = Th(OH)2(GH2)−+ 4H+. In the presence of ThO2·xH2O, sorption of the organic ligand onto solid surface seems to limit thorium dissolution.
Study of Hydrogen Bonding Patterns of a Pharmaceutically Active Drug Molecule Paraldehyde: a Raman and DFT Study
Authors: Singh Shweta , Singh Dheeraj K. , Srivastava Sunil K. , Asthana Birendra P.
Published: March 2011

Raman spectra of neat paraldehyde (prldh) and its binary mixtures with methanol (M) with varying mole fractions of prldh from 0.1 to 0.8 were recorded in order to explore the hydrogen bonding patterns of prldh and their influence on spectral features of some selected vibrational bands of prldh in the region 400–1200 cm−1. Only few vibrational bands of paraldehyde show a significant change in their peak position in going from neat prldh to the complexes. One peculiar feature in this study is that the solvent band which occurs at ∼1034 cm−1 shows significant red shift of >4 cm−1 at higher mole fractions of prldh. This red shift is caused due to the hydrogen bonding between the O atom of the prldh ring and H atom of the methanol molecules. The Raman band at ∼1097 cm−1 band shows a blue shift of ∼5 cm−1 upon dilution and its linewidth also shows an increase of ∼5 cm−1 in going from neat prldh to extreme dilution. The line broadening upon dilution clearly indicates that the diffusion mechanism plays a dominant role in the dephasing of this vibrational mode. Density functional theoretic (DFT) calculations were performed employing B3LYP functional and high level basis set, 6-311++G(d,p) to obtain the ground state geometry of neat prldh and its hydrogen bonded complexes with methanol in gas phase. Basis set superimpose error (BSSE) correction was also introduced using the counterpoise method. In order to realize a condition quite close to the experiment, the polarizable continuum model (PCM, specific plus bulk solvation) calculations were also performed. For a detailed vibrational assignment of the normal modes, potential energy distribution (PED) calculation was also performed.
Durability of wheat straw ash concrete exposed to freeze–thaw damage
Authors: Al-Akhras Nabil M
Published: March 2011

This study investigated the effect of wheat straw ash on the durability of concrete to freeze–thaw deterioration. Three wheat straw ash replacement levels were considered in the study: 5, 10 and 15% by weight of cement. The other experimental parameters investigated in the study included: aggregate type (basalt and pumice), water/binder ratio (0·5 and 0·7) and maximum aggregate size (9·5 and 19 mm). After the initial moist curing, wheat straw ash concrete prisms were subjected to accelerated freeze–thaw cycles following ASTM Procedure B (rapid freezing in air and thawing in water). The freeze–thaw deterioration of wheat straw ash concrete specimens was evaluated using the relative dynamic modulus of elasticity and durability factor. The results showed that the durability of wheat straw ash concrete to freeze–thaw deterioration was greater than that of plain concrete. Furthermore, the durability of wheat straw ash concrete to freeze–thaw deterioration increased with increasing wheat straw ash replacement level. The concrete containing pumice aggregate showed higher durability to freeze–thaw deterioration in comparison with that containing basalt aggregate. The effect of aggregate type was more pronounced for the wheat straw ash concrete than for plain concrete. The concrete at water/binder ratio of 0·5 showed higher durability to freeze–thaw deterioration than that at water/binder ratio of 0·7. The effect of water/binder ratio was more pronounced for the wheat straw ash concrete in comparison with the control concrete. Furthermore, the concrete with maximum aggregate size of 9·5 mm showed higher durability to freeze–thaw deterioration than concrete with maximum aggregate size of 19 mm.
Compacted dune sand concrete for pavement applications
Authors: Khay Saloua El Euch , Neji Jamel , Loulizi Amara
Published: March 2011

Deficits in quarry gravels in some regions initiated the present study to examine the feasibility of using dune sand, obtained from the Sahara region, for road construction. Dune sand was used to produce compacted sand concrete, which serves as a base layer in pavement structures. An investigation of the potential sands was carried out and their physical characteristics were then evaluated. A proportioning study was developed to find the best mixture of compacted dune sand concrete with a minimum 28 day compressive strength of 15 MPa. The paper summarises the steps followed to validate the use of this new material and describes the results of all performed mechanical tests. Furthermore, the paper provides the results of fatigue tests for the retained mixture, reports its fatigue parameters, presents the results of the free shrinkage test, and finally proposes the spacing of sawn joints for compacted dune sand concrete slabs to avoid shrinkage cracking.
Treatment of Unicameral Bone Cyst
Authors: Hou Hsien-Yang , Wu Karl , Wang Chen-Ti , Chang Shun-Min , Lin Wei-Hsin , Yang Rong-Sen
Published: March 2011

BACKGROUND:

There is a variety of treatment modalities for unicameral bone cysts, with variable outcomes reported in the literature. Although good initial outcomes have been reported, the success rate has often changed with longer-term follow-up. We introduce a novel, minimally invasive treatment method and compare its clinical outcomes with those of other methods of treatment of this lesion.

METHODS:

From February 1994 to April 2008, forty patients with a unicameral bone cyst were treated with one of four techniques: serial percutaneous steroid and autogenous bone-marrow injection (Group 1, nine patients); open curettage and grafting with a calcium sulfate bone substitute either without instrumentation (Group 2, twelve patients) or with internal instrumentation (Group 3, seven patients); or minimally invasive curettage, ethanol cauterization, disruption of the cystic boundary, insertion of a synthetic calcium sulfate bone-graft substitute, and placement of a cannulated screw to provide drainage (Group 4, twelve patients). Success was defined as radiographic evidence of a healed cyst or of a healed cyst with some defect according to the modified Neer classification, and failure was defined as a persistent or recurrent cyst that needed additional treatment. Patients who sustained a fracture during treatment were also considered to have had a failure. The outcome parameters included the radiographically determined healing rate, the time to solid union, and the total number of procedures needed.

RESULTS:

The follow-up time ranged from eighteen to eighty-four months. Group-4 patients had the highest radiographically determined healing rate. Healing was seen in eleven of the twelve patients in that group compared with three of the nine in Group 1, eight of the twelve in Group 2, and six of the seven in Group 3. Group-4 patients also had the shortest mean time to union: 3.7 ± 2.3 months compared with 23.4 ± 14.9, 12.2 ± 8.5, and 6.6 ± 4.3 months in Groups 1, 2, and 3, respectively.

CONCLUSIONS:

This new minimally invasive method achieved a favorable outcome, with a higher radiographically determined healing rate and a shorter time to union. Thus, it can be considered an option for initial treatment of unicameral bone cysts.

LEVEL OF EVIDENCE:

Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

ORIGINAL ABSTRACT CITATION:

“Treatment of Unicameral Bone Cyst. A Comparative Study of Selected Techniques” (2010;92:855-62).
Revision Arthroscopic Rotator Cuff Repair: Repair Integrity and Clinical Outcome
Authors: Kowalsky Marc S. , Keener Jay D.
Published: March 2011

BACKGROUND:

Literature regarding the outcomes of revision rotator cuff repair is limited. The purposes of the present study were to report the tendon repair integrity and clinical outcomes for a cohort of patients following revision arthroscopic rotator cuff repair and to examine factors related to tendon healing and the influence of healing on clinical outcomes.

METHODS:

Twenty-one of twenty-nine consecutive revision arthroscopic rotator cuff repairs with a minimum of two years of postoperative follow-up were retrospectively reviewed. Outcomes were evaluated on the basis of a visual analog pain scale, the range of motion of the shoulder, the Simple Shoulder Test, the American Shoulder and Elbow Surgeons score, and the Constant score. Ultrasonography was used to examine repair integrity at a minimum of one year following surgery. Ten shoulders underwent arthroscopic repair of a recurrent single-tendon posterior rotator cuff tear, whereas eleven shoulders had repair of both the supraspinatus and infraspinatus.

RESULTS:

The mean age of the twenty-one subjects was 55.6 years; thirteen subjects were male and eight were female. Complete preoperative and postoperative clinical data were available for nineteen subjects after an average duration of follow-up of thirty-three months. Significant improvements were seen in terms of postoperative pain (p < 0.05), the Simple Shoulder Test score (p < 0.05), the American Shoulder and Elbow Surgeons function (p < 0.05) and total scores (p < 0.05), active forward elevation (p < 0.05), and active external rotation (p < 0.05). Postoperative ultrasound data were available for all twenty-one shoulders after a mean duration of follow-up of twenty-five months. Ten (48%) of the twenty-one shoulders had an intact repair. Seven (70%) of the ten single-tendon repairs were intact, compared with three (27%) of the eleven supraspinatus/infraspinatus repairs (p = 0.05). Patient age (p < 0.05) and the number of torn tendons (p = 0.05) had significant effects on postoperative tendon repair integrity. Shoulders with an intact repair had better postoperative Constant scores (p < 0.05) and scapular plane elevation strength (p < 0.05) in comparison with those with a recurrent tear.

CONCLUSIONS:

Revision arthroscopic rotator cuff repair results in reliable pain relief and improvement in shoulder function in selected cases. Approximately half of the revision repairs can be expected to be intact at a minimum of one year following surgery. Patient age and the number of torn tendons are related to postoperative tendon integrity. The postoperative integrity of the rotator cuff can have a significant influence on shoulder abduction strength and the Constant score.

LEVEL OF EVIDENCE:

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

ORIGINAL ABSTRACT CITATION:

“Revision Arthroscopic Rotator Cuff Repair: Repair Integrity and Clinical Outcome” (2010;92:590-8).
Outcomes of an Anatomic Posterolateral Knee Reconstruction
Authors: LaPrade Robert F. , Johansen Steinar , Engebretsen Lars
Published: March 2011

BACKGROUND:

Chronic posterolateral knee injuries often result in substantial patient morbidity and functional instability. The clinical stability and functional outcomes following anatomic reconstructions in patients with a chronic posterolateral knee injury have not been determined, to our knowledge.

METHODS:

A two-center outcomes study of sixty-four patients with grade-3 chronic posterolateral instability was performed. The patients were evaluated subjectively with the modified Cincinnati and International Knee Documentation Committee (IKDC) subjective scores and objectively with the IKDC objective score.

RESULTS:

Eighteen patients had an isolated posterolateral knee reconstruction, and forty-six patients underwent a single-stage multiple-ligament reconstruction that included reconstruction of one or both cruciate ligaments along with the posterolateral knee reconstruction. The average duration of follow-up was 4.3 years. The fifty-four patients who were available for follow-up had an average total Cincinnati score of 65.7 points. A significant improvement was found between the preoperative and postoperative IKDC objective scores for varus opening at 20°, external rotation at 30°, reverse pivot shift, and single-leg hop.

CONCLUSIONS:

An anatomic posterolateral reconstruction resulted in improved clinical outcomes and objective stability for patients with a grade-3 posterolateral knee injury.

LEVEL OF EVIDENCE:

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

ORIGINAL ABSTRACT CITATION:

“Outcomes of an Anatomic Posterolateral Knee Reconstruction” (2010;92:16-22).
Cesarean Delivery in the Obese Parturient: Anesthetic Considerations
Authors: Loubert Christian , Fernando Roshan
Published: March 2011

Obesity is a worldwide health problem and its prevalence is reaching epidemic proportions. As obesity does not spare women of childbearing age, obstetric anesthesiologists will increasingly be exposed to the challenges of anesthesia in this population. The purpose of this article is to give the reader a thorough understanding of the anesthetic implications of obesity relating to cesarean deliveries. Obesity is associated with hypertension, diabetes, obstructive sleep apnea and other comorbidities. It increases the risk of cesarean delivery, postpartum wound infections and deep venous thromboembolism. Obese parturients are prone to anesthetic complications such as aspiration of gastric contents, difficult monitoring, positioning, airway management and challenging neuraxial techniques. A thorough precesarean delivery preparation should include an evaluation by an anesthesiologist for women with a BMI over 40 kg/m2 and institution of an antacid prophylaxis protocol, thromboprophylaxis and antibiotic prophylaxis. Regional anesthesia should ideally be used in all obese parturients unless contraindicated. The goals of postpartum care include efficacious analgesia, physiotherapy and early mobilization. Monitoring and vigilance in an intensive care unit or step-down units should be considered for morbidly obese women.
Fertility Conservation in Breast Cancer Patients
Authors: Lawrenz Barbara , Henes Melanie , Neunhoeffer Eva , Kraemer Bernhard , Fehm Tanja
Published: March 2011

Breast cancer is the most common malignant tumor in women. Increasing survival rates after breast cancer, new reproductive techniques and growing interest regarding the quality of life after cancer have brought the possibilities of fertility-preserving treatment to the center of attention of oncologists and affected patients. Many of these women suffer from infertility and premature menopause as a result of chemotherapy. Several measures, for example gonadotropin-releasing hormone analogs, hormonal stimulation to cryopreserve oocytes, ovarian tissue cryoconservation or a combination of the methods, can be undertaken depending on the hormone receptor status of the tumor, and the patient's age and partner status. Embryo cryopreservation is currently the most promising fertility preservation option. Early counseling on fertility-preserving strategies is of utmost importance, so that the fertility-preserving method can be integrated into the oncologic therapy regime.
Update on Gynecologic Surgery
Authors: Svets Monica , Falcone Tommaso
Published: March 2011

Christ Hospital of Cincinnati (OH, USA) sponsored the 13th annual Pelvic Anatomy and Gynecologic Surgery Symposium held on 9–11 December 2010 in Las Vegas (NV, USA). Course directors were Mickey M Karram and Michael S Baggish. Invited faculty included Tommaso Falcone and Mark Walters, both from the Cleveland Clinic Foundation in Cleveland (OH, USA). In addition, John Gebhart from the Mayo Clinic in Rochester (MN, USA) and Javier F Magrina from the Mayo Clinic Scottsdale (AZ, USA) rounded out the speakers' list. The symposium gathered renowned experts in open, vaginal, laparoscopic and robotic pelvic surgeries to discuss issues and controversies surrounding minimally invasive gynecologic surgery.
Imaging in Gynecologic Surgery
Authors: Mettler Liselotte , Sammur Wael , Alkatout Ibrahim , Schollmeyer Thoralf
Published: March 2011

The technical development of instruments for endoscopic surgery started in the field of gynecology. In the early 1970s, with the improvement of optics and instruments for laparoscopic surgery, gyne-endoscopic surgery developed and set milestones for all other surgical fields. However, the general surgeons propagated the advantages of 2D or 3D imaging surgery much better than the conservative gynecologists. Surgery on a 2D screen without direct vision is regarded as more advantageous than open surgery and has achieved wide acceptance. Several schools of gynecologic endoscopy in Europe (in Kiel, Giessen, Clermont Ferrand and Strasbourg) have set guidelines for gyne-endoscopic surgery. Our catalog of indications in the areas of gyne-endoscopic surgery, published in 2002, reveals the broad application of these techniques today. 3D vision, robotic instruments and systems, such as the da Vinci® Surgical System from Intuitive Surgical, Inc. (CA, USA), round up the picture of endoscopic surgery. The advantages of endoscopic surgery over open surgery (more precision, less trauma, less postoperative pain, shorter hospital stays and a faster recovery period) are becoming more accepted. The present healthcare systems and hospital administrations understand the challenges of imaging in surgery, particularly in endoscopic surgery.
Colorectal Cancer Screening and Prevention in Women
Authors: Krishnan Sandeep , Wolf Jacqueline L
Published: March 2011

Colorectal cancer (CRC) is the third most common cause of cancer in women. Screening for CRC increases early detection of cancer and premalignant polyps and decreases morbidity from this disease. However, adherence to the screening guidelines continues to remain inadequate both at the physician and patient levels. Several factors are of special importance to women. Presence of prior gynecological malignancies may increase the risk of CRC in women. Furthermore, new studies have shown other factors such as obesity and smoking to increase the risk of CRC in women. This article highlights issues unique to women with regards to CRC and outlines special considerations for determining screening intervals in women, identifies factors that make screening more difficult in women, and reviews studies that identify preventative strategies which, together with screening, may reduce the burden of CRC.
Contribution of Dentist Anesthesiologists to Dental Anesthesiology Research
Authors: Ganzberg Steven , Rashid Robert G , Davidian Edward
Published: March 2011

In order to determine if dentist anesthesiologists (DAs) actively contribute to research in the field of anesthesiology, and thus contribute new knowledge to the field, an extensive literature search was accomplished. DAs make up only 1.5% of dentists who actively contribute to anesthesia research but account for 10% of publications. To determine if the impact of DA research was similar to the American Dental Association (ADA) recognized specialties, h-indices of noted researchers in other specialties were compared to the h-indices of noted DA researchers. The results show that the impact of top DA researchers in dental anesthesiology is similar to the impact of top dental specialty researchers, despite lack of academic departments in dental schools where a large percentage of dental research is completed. Dentist anesthesiologists actively contribute to the research in anesthesiology for dentistry and thus, actively contribute to new knowledge in the field.
Transient Cardiac Arrest in Patient With Left Ventricular Noncompaction (Spongiform Cardiomyopathy)
Authors: Yamazaki Shinya , Ito Hiroshi , Kawaai Hiroyoshi
Published: March 2011

Left ventricular noncompaction (LVNC), also known as spongiform cardiomyopathy, is a severe disease that has not previously been discussed with respect to general anesthesia. We treated a child with LVNC who experienced cardiac arrest. Dental treatment under general anesthesia was scheduled because the patient had a risk of endocarditis due to dental caries along with a history of being uncooperative for dental care. During sevoflurane induction, severe hypotension and laryngospasm resulted in cardiac arrest. Basic life support (cardiopulmonary resuscitation) was initiated to resuscitate the child, and his cardiorespiratory condition improved. Thereafter, an opioid‐based anesthetic was performed, and recovery was smooth. In LVNC, opioid‐based anesthesia is suggested to avoid the significant cardiac suppression seen with a volatile anesthetic, once intravenous access is established. Additionally, all operating room staff should master Advanced Cardiac Life Support/Pediatric Advanced Life Support (including intraosseous access), and more than 1 anesthesiologist should be present to induce general anesthesia, if possible, for this high‐risk patient.