bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurovascular coupling investigated with two‐dimensional optical imaging spectroscopy in rat whisker barrel cortex
Authors: Berwick J. , Johnston D. , Jones M. , Martindale J. , Redgrave P. , McLoughlin N. , Schiessl I. , Mayhew J. E. W. 
Published: October 2005

AbstractOptical imaging slit spectroscopy is a powerful method for estimating quantitative changes in cerebral haemodynamics, such as deoxyhaemoglobin, oxyhaemoglobin and blood volume (Hbr, HbO2 and Hbt, respectively). Its disadvantage is that there is a large loss of spatial data as one image dimension is used to encode spectral wavelength information. Single wavelength optical imaging, on the other hand, produces high‐resolution spatiotemporal maps of brain activity, but yields only indirect measures of Hbr, HbO2 and Hbt. In this study we perform two‐dimensional optical imaging spectroscopy (2D‐OIS) in rat barrel cortex during contralateral whisker stimulation to obtain two‐dimensional maps over time of Hbr, HbO2 and Hbt. The 2D‐OIS was performed by illuminating the cortex with four wavelengths of light (575, 559, 495 and 587 nm), which were presented sequentially at a high frame rate (32 Hz). The contralateral whisker pad was stimulated using two different durations: 1 and 16 s (5 Hz, 1.2 mA). Control experiments used a hypercapnic (5% CO2) challenge to manipulate baseline blood flow and volume in the absence of corresponding neural activation. The 2D‐OIS method allowed separation of artery, vein and parenchyma regions. The magnitude of the haemodynamic response elicited varied considerably between different vascular compartments; the largest responses in Hbt were in the arteries and the smallest in the veins. Phase lags in the HbO2 response between arteries and veins suggest that a process of upstream signalling maybe responsible for dilating the arteries. There was also a consistent increase in Hbr from arterial regions after whisker stimulation.
A similar impairment in CA3 mossy fibre LTP in the R6/2 mouse model of Huntington's disease and in the complexin II knockout mouse
Authors: Gibson Helen E. , Reim Kerstin , Brose Nils , Morton A. Jennifer , Jones Susan 
Published: October 2005

AbstractComplexin II is reduced in Huntington's disease (HD) patients and in the R6/2 mouse model of HD. Mice lacking complexin II (Cplx2–/– mice) show selective cognitive deficits that reflect those seen in R6/2 mice. To determine whether or not there is a common mechanism that might underlie the cognitive deficits, long‐term potentiation (LTP) was examined in the CA3 region of hippocampal slices from R6/2 mice and Cplx2–/– mice. While associational/commissural (A/C) LTP was not significantly different, mossy fibre (MF) LTP was significantly reduced in slices from R6/2 mice and Cplx2–/– mice compared with wild‐type (WT) and Cplx2+/+ control mice. MF field excitatory postsynaptic potentials (fEPSPs) in response to paired stimuli were not significantly different between control mice and R6/2 or Cplx2–/– mice, suggesting that MF basal glutamate release is unaffected. Forskolin (30 µm) caused an increase in glutamate release at MF synapses in slices from R6/2 mice and from Cplx2–/– mice that was not significantly different from that seen in control mice, indicating that the capacity for increased glutamate release is not diminished. Thus, R6/2 mice and Cplx2–/– mice have a common selective impairment of MF LTP in the CA3 region. Together, these data suggest that complexin II is required for MF LTP, and that depletion of complexin II causes a selective impairment in MF LTP in the CA3 region. This impairment in MF LTP could contribute to spatial learning deficits observed in R6/2 and Cplx2–/– mice.
Thyroid hormone‐induced morphological differentiation and maturation of astrocytes involves activation of protein kinase A and ERK signalling pathway
Authors: Ghosh Mausam , Gharami Kusumika , Paul Surojit , Das Sumantra 
Published: October 2005

AbstractThyroid hormone (TH) has a profound effect on astrocyte differentiation and maturation. Astrocytes cultured under TH‐deficient conditions fail to transform from flat polygonal morphology to mature, process‐bearing, stellate cells. Supplementation of physiological concentrations of TH initiate gradual transformation of the cells and the process takes ≈ 48 h to complete. The signal transduction pathways associated with TH‐mediated maturation of astrocytes have been investigated. TH treatment caused an initial activation of protein kinase A (PKA), with a peak activity at 2 h which fell back to basal level there after. Although there was no visible change in morphology of the cells during the observed activation of PKA, it was sufficient to drive the process of transformation to completion, suggesting the involvement of downstream regulators of PKA. PKA inhibitors as well as the MEK inhibitor PD098059 attenuated the TH‐induced morphological transformation. Further studies showed that TH treatment resulted in a biphasic response on the cellular phospho‐MAP kinase (p‐MAPK or p‐ERK) level: an initial decline in the p‐ERK level followed by an induction at 18–24 h, both of which could be blocked by a PKA inhibitor. Such sustained activation of p‐ERK levels by TH at this later stage coincided with initiation of morphological differentiation of the astrocytes and appeared to be critical for the transformation of astrocytes. The nitric oxide synthase (NOS) inhibitor 7‐NI inhibited this induction of p‐ERK activity. Moreover, the induction was accompanied by a parallel increase in phospho‐CREB activity which, however, persisted at the end of the transformation of the astroglial cells.
Recruitment of local excitatory circuits in the superior colliculus following deafferentation and the regeneration of retinocollicular inputs
Authors: Turner J. P. , Sauvé Y. , Varela‐Rodriguez C. , Lund R. D. , Salt T. E. 
Published: October 2005

AbstractThe local synaptic connectivity in the superficial gray layer of the superior colliculus (SC) was assessed following retinal ganglion cell axonal regeneration through a peripheral nerve graft into the SC of Lister Hooded rats, using in vitro brain slice techniques. Repair was effected between the ipsilateral eye and SC, following bilateral lesion of optic nerves and ablation of ipsilateral occipital cortex. Deafferentation surgery alone resulted in a complete loss of synaptic potentials of extrinsic origin, once both retinal and cortical inputs were removed. Stimulation of graft insertion sites elicited synaptic responses comprising monosynaptic and network‐mediated depolarising events. This activity, together with similar spontaneous bursts of depolarising events and action potential firing, was generated by the activation of non‐N‐methyl‐d‐aspartate glutamate receptors. This behaviour may reflect the development of a local recurrent synaptic connectivity following the repair surgery, as both evoked and spontaneous responses developed into large long‐lasting bursts of excitatory activity when inhibition mediated by GABA receptors was blocked. These results suggest that the ultrastructural changes in the superficial layers of the SC resulting from deafferentation are reflected functionally at the synaptic level in the target structure even after repair. Such changes are likely to compromise the ability of the target structure to function normally during information processing. Therefore, although axons regenerating along peripheral nerve grafts can make functional synaptic connections, their efficacy in activating the target structure will probably be compromised by local changes in synaptic connectivity.
Memory strengthening by a real‐life episode during reconsolidation: an outcome of water deprivation via brain angiotensin II
Authors: Frenkel Lia , Maldonado Héctor , Delorenzi Alejandro 
Published: October 2005

AbstractA considerable body of evidence reveals that consolidated memories, recalled by a reminder, enter into a new vulnerability phase during which they are susceptible to disruption again. Consistently, reconsolidation was shown by the amnesic effects induced by administration of consolidation blockers after memory labilization. To shed light on the functional value of reconsolidation, we explored whether an endogenous process activated during a concurrent real‐life experience improved this memory phase. Reconsolidation of long‐term contextual memory has been well documented in the crabChasmagnathus. Previously we showed that angiotensin II facilitates memory consolidation. Moreover, water deprivation increases brain angiotensin and improves memory consolidation and retrieval through angiotensin II receptors. Here, we tested whether concurrent water deprivation improves reconsolidation via endogenous angiotensin and therefore strengthens memory. We show that memory reconsolidation, induced by training context re‐exposure, is facilitated by a concurrent episode of water deprivation, which induces a raise in endogenous brain angiotensin II. Positive modulation is expressed by full memory retention, despite a weak training, 24 or 72 but not 4 h after memory reactivation. This is the first evidence that memory can be positively modulated during reconsolidation through an identified endogenous process triggered during a real‐life episode. We propose that the functional value for reconsolidation would be to make possible a change in memory strength by the influence of a concurrent experience. Reconsolidation improvement would lead to memory re‐evaluation, not by altering memory content but by modifying the behaviour as an outcome of changing the hierarchy of the memories that control it.
Design of Shewanella‐specific 16S rRNA primers and application to analysis of Shewanella in a minerotrophic wetland
Authors: Todorova Svetoslava G. , Costello Andria M. 
Published: October 2005

SummaryIn this study, an existing probe was used as a polymerase chain reaction (PCR) primer to study iron‐reducing members of the genus Shewanella in a minerotrophic wetland where iron reduction had previously been implicated. The probe was found to be non‐specific and a new set of PCR primers were developed that were specific for Shewanella. These primers were used to analyse the wetland iron‐reducing communities by characterizing 16S rRNA genes amplified from DNA extracted from peat. Polymerase chain reaction clone libraries were screened using restriction fragment length polymorphism and diagnostic operational taxonomic units for Shewanella species were identified. A statistical method was used to determine the coverage of the clone libraries, which was found to be between 83% and 97%. The dominant species in the wetland samples at two geochemically distinct zones were phylogenetically related to the iron‐reducing microorganism Shewanella oneidensis.
Measurement of Prochlorococcus ecotypes using real‐time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies
Authors: Ahlgren Nathan A. , Rocap Gabrielle , Chisholm Sallie W. 
Published: October 2005

Summary Prochlorococcus is a marine cyanobacterium which is found at high abundances in world's tropical and subtropical oligotrophic oceans. The genus Prochlorococcus can be divided into two major groups based on light physiology. Both of these groups can be further subdivided into genetically distinct lineages, or ecotypes. Real‐time polymerase chain reaction (PCR) assays based on sequence differences in the 16S‐23S rDNA internal transcribed spacer or the 23S rDNA were developed to examine the distribution of each ecotype in the field. The real‐time PCR assays enabled linear quantification of concentrations ranging from 10 to 4 × 105 cells ml−1. These assays were applied to a stratified water column in the Sargasso Sea. The majority of Prochlorococcus cells above 110 m belonged to the one of the low chlorophyll b/a ratio (high‐light adapted) ecotypes, while two types of high chlorophyll b/a ratio (low‐light adapted) cells dominated below 110 m. The other three types were found at significantly lower numbers or not detected at all. Differences in the abundance of ecotypes within the major light physiology groupings suggest that other factors, such as nutrient utilization and differential mortality, are driving their relative distributions. Real‐time PCR assays will enable further exploration of these factors and temporal and geographic variability in ecotype abundance.
Protecting Neurons
Authors: Ferriero Donna M. 
Published: October 2005

Summary:  Brain injury evolves over time, often taking days or even weeks to fully develop. It is a dynamic process that involves immediate oxidative stress and excitotoxicity followed by inflammation and preprogrammed cell death. This article presents a brief overview of mechanisms of neuroprotection in the developing brain. Although the focus is on ischemic injury, the conclusions drawn apply to any type of brain insult—epileptic seizures, trauma, or ischemia. Strategies of neuroprotection include salvaging neurons through the use of targeted pharmacotherapies, protecting neurons through preconditioning, and repairing neurons by enhancing neurogenesis. Drug therapies that dampen the impact of immediate and downstream postinjury events are only modestly effective in protecting the brain from ischemic injury. In experimental models, complete or true protection can be achieved only through preconditioning, a process during which an animal develops tolerance to an otherwise lethal stressor. Although of no clinical use, preconditioning models have provided valuable insight into how repair systems work in the brain. Cumulative evidence indicates that the same genes that are upregulated during preconditioning, those mediating true protection, are also upregulated during injury and repair. Specifically, hypoxic preconditioning and hypoxic‐ischemic insult have been shown to induce hypoxia inducible factor‐1 (HIF‐1) and its target survival genes, vascular endothelial growth factor (VEGF), and erythropoietin (Epo) in rodents. Of particular interest is the upregulation of Epo, a growth factor that may have therapeutic potential in the treatment of ischemic stroke. At this time, however, the postinjury enhancement of neurogenesis appears to offer the best hope for long‐lasting functional recovery following brain injury.
Significance of the signal‐to‐cutoff ratios of anti‐hepatitis C virus enzyme immunoassays in screening of Chinese blood donors
Authors: Ren Fu‐Rong , Lv Qiu‐Shuang , Zhuang Hui , Li Jing‐Jing , Gong Xiao‐Yan , Gao Guo‐Jing , Liu Chang‐Li , Wang Jing‐Xing , Yao Fu‐Zhu , Zheng You‐Rong , Zhu Fa‐Ming , Tiemuer Mei‐Hei‐Li , Bai Xu‐Hua , Shan Hua 
Published: October 2005

BACKGROUND: The correlation between signal‐to‐cutoff (S/CO) ratios of a second‐generation hepatitis C virus (HCV) enzyme immunoassay (EIA; Abbott) and a third‐generation HCV enzyme‐linked immunosorbent assay (ELISA; Ortho) and confirmed HCV infection has been reported. The utility of the values for the Chinese anti‐HCV EIA kits, however, has not been studied in evaluating test results in Chinese blood donors.STUDY DESIGN AND METHODS: A total of 156 donor samples repeat reactive for anti‐HCV at routine screening from five representative regions of China were retested for anti‐HCV by the Ortho third‐generation HCV ELISA and six Chinese EIA kits and for HCV RNA by a human immunodeficiency virus‐1 and HCV assay (Procleix, Chiron Corp.). The HCV RNA–nonreactive samples were further tested for anti‐HCV by a third‐generation recombinant immunoblot assay RIBA (Chiron Corp.). The positive result by either nucleic acid amplification test or RIBA was interpreted as confirmed HCV infection.RESULTS: The confirmed HCV prevalence rate in donors in five representative regions obtained in this study was 0.20 percent (77/37,900) in 2004. All seven anti‐HCV EIA kits had a significant correlation between S/CO ratios and confirmed HCV infection. The threshold S/CO ratios, which predicted more than 95 percent of confirmed HCV infections for the Ortho, SABC, BGI‐GBI, InTec, GWK, KHB, and WANTAI kits, were 3.8, 6.0, 7.0, 8.6, 10.0, 10.0, and 14.0, respectively.CONCLUSIONS: Anti‐HCV EIA kits commonly used in Chinese donors screening demonstrate good correlation between S/CO ratios and the confirmed infection. For the Ortho third‐generation HCV ELISA, the S/CO ratio of 3.8 determined by the US Centers for Disease Control and Prevention is applicable to Chinese blood donors. The Chinese domestic EIA kits evaluated show a diverse range of threshold S/CO ratios.
Interpretation of Ultrasonic Experiments on Finite-Amplitude Waves
Authors: Thurston R. N. , Shapiro M. J. 
Published: October 2005

An analysis was made for the purpose of relating higher-order elastic constants to the growth of harmonics in an initially sinusoidal wave. It is supposed that the face of a semiinfinite nondissipative elastic medium—for which the equation of one-dimensional motion is ü = (∂2u/∂x2)g(∂u/∂x)—is subjected to the sinusoidal displacement u = u0 cos(ωt−φ). The function g(∂u/∂x) is given as g(ξ) = (1/ρ0)[M2+M3ξ+M4ξ2+⋯+Miξi−2], where Mi depends on elastic constants up to and including order i. A solution, including the effects due to terms as high as M5 in the function g(ξ), is expressed as u = u0 Σn{Dn sin[n(ωt− Kx)]+En cos[n(ωt− Kx)]}+F(x), where the summation over n goes from 1 to ∞. Dn and En are expanded in powers of a Mach number M and a dimensionless distance X (M = ωu0/c0, X = ωx/c0, c02 = M2/ρ0). It is found that as u0 → 0, the limiting value of the ratio of the second-harmonic amplitude, H2 = u0(D22+E22)12, to u0M is given by −M3X/8M2, independently of M4, M5, etc. Thus, with M2 already known, M3 can be calculated from an experimental determination of this ratio. Similarly, it is found that the limiting value of the ratio of the third harmonic amplitude to u0M2 depends on elastic constants only up through order four.
[Tutorial material is included to make the paper reasonably self-contained and to relate the present analysis to corresponding work for fluids. Careful derivations show that purely longitudinal waves in elastic solids and nondissipative fluids are governed by an equation of motion of precisely the same form. Hence, with appropriate choice of the parameters, an analysis of the one case applies equally well to the other.]
Session WII. Musical Acoustics Workshop: Concert/Demonstration of New Bowed String Instruments Developed by Catgut Acoustical Society, Inc.
Authors: Neustadt Herbert M. 
Published: October 2005

A classic problem of acoustics is: How can one build a violin having a tone quality that matches the tone of a Stradivarius? This problem has been under enthusiastic attack for many years by a group of researchers led originally by the late Professor Frederick A. Saunders of Harvard, and more recently by Carleen M. Hutchins. The group calls itself “The Catgut Acoustical Society” and has four hundred members in fourteen nations. Many of the members have achieved professional distinction as mathematicians, physicists, and musicians.
Forty years of work in a multidisciplinary situation involving technical researchers, violin makers, performing musicians, conductors, and composers as well as listeners have yielded a vast store of information on the conventional violin, viola, cello, and string bass. Many of these findings have been incorporated into experimental instruments built and tested by Carleen Hutchins in her basement laboratory and workshop resulting not only in improvements in conventional violins, violas, cellos, and basses but also in design and construction of a whole new family of eight violin-type instruments which give a uniform tone quality across the entire range of musical frequencies.
These eight new instruments are to be played by musicians of the National Gallery Orchestra and Mrs. Hutchins will lecture briefly.
Impulse noise of army weapons
Authors: Garinther Georges R. 
Published: October 2005

Exposure to the impulse noise produced by certain weapons is known to cause hearing loss among Army personnel if they do not wear hearing protection. These high levels are produced by weapons as small as a 5.56 mm rifle up to as large as a 155 mm Howitzer. Typical sound pressure levels and B durations produced by weapons are:
22 cal rifle: 140 dB; 2 ms 155 mm Howitzer: 178 dB; 50 ms
5.56 mm rifle: 155 dB; 4 ms M72 Rocket Launcher: 179 dB; 12 ms
105 mm Howitzer: 171 dB; 30 ms Dragon Rocket Launcher: 185 dB; 5 ms.
The hazard to hearing presented by these weapons has been assessed by MIL-STD 1472 which is based upon the Impulse Noise Hearing Damage Risk Criterion of CHABA Working Group 57. This Standard considers peak pressure level, duration, number of pulses, interval, orientation of the ear, percent risk, and hearing protection. Attempts have been made to reduce the noise produced by these weapons with good success for small caliber weapons, but very limited success for large weapons. A different approach to the assessment of the hazard of impulse noise, which considers spectrum, is presently being studied at the US Army Human Engineering Laboratory.
Intensity, spectrum, and directivity of turbulent boundary layer noise
Authors: Tam Christopher K. W. 
Published: October 2005

The problem of noise radiated from a turbulent boundary layer is studied. It is found that the farfield noise power, spectrum, and directivity can be determined completely if the nearfield pressure cross−correlation function is known. The role of supersonic and subsonic pressure components associated with the turbulent boundary layer in relation to noise radiation is examined. By using an empirical model of wall pressure cross−correlation function, it is found that the directivity pattern of turbulent boundary layer noise differs considerably from that of a free dipole. One principal reason for this difference is the fact that the noise sources of a turbulent boundary layer are constantly in motion. The effect of mean flow outside the boundary layer on the radiated noise power and spectrum is also investigated. Numerical results indicate that this effect is very important for low frequency noise components and for a high subsonic flow Mach number.
Subject Classification: 28.65; 50.55.
Determination of sonic velocities from reflectivity losses at sea ice/water boundaries
Authors: Mayer Walter G. , Behravesh Mohamad , Plona Thomas J. 
Published: October 2005

Reflectivities are calculated as functions of sonic incidence angle, densities, and sonic velocities. The resulting sets of curves are used to determine under which conditions reflectivity measurements can or cannot yield information about the values of sonic velocities and density of sea ice.
Subject Classification: 30.25, 30.30.
Attenuation of sound by rigid spheres: measurement of the viscous and thermal components of attenuation and comparison with theory
Authors: Foner S. N. , Nall B. H. 
Published: October 2005

An acoustic cavity technique has been developed to separately measure the viscous and thermal components of the attenuation of sound by rigid spheres in various gases. A rigorous quantitative test of theoretical predictions for the individual components of attenuation has been carried out for spheres of known size in argon, nitrogen, and dichlorodifluoromethane (Freon−12), gases selected to cover a wide range in the relative influence of thermal damping to viscous damping. Theory and experiment are in good agreement in regard to both qualitative and quantitative features. Qualitatively, the most striking feature observed is the sinusoidal variation of attenuation with displacement of the spheres along the cavity axis, as predicted by theory. The absolute values of the viscous and thermal damping constants agree quite well with theory. Even better agreement with theory is obtained for the difference between viscous and thermal attenuation, a measurement that does not require opening the cavity to insert or remove the spheres. In addition, the damping produced by the slender cylindrical translating rod exhibits some interesting structure which can be quantitatively explained by theory.
Subject Classification: 35.20; 20.35.