bluuebunny/crossref_metadata_2025 huggingface dataset:
Human PTH gene regulation in vivo using transgenic mice
Authors: Lavi-Moshayoff Vardit , Silver Justin , Naveh-Many Tally
Published: July 2009

To study the regulation of the human PTH (hPTH) gene in vivo, we generated transgenic mice with the hPTH gene expressed in the mouse parathyroid using a bacterial artificial chromosome (BAC) containing the hPTH gene within its 144-kb chromosomal region. The BAC construct maintains the native hPTH gene surrounding sequences and isolates it from positional effects. The transgenic mice had normal levels of serum mouse PTH (mPTH) in addition to both intact and bioactive hPTH. Despite the presence of both mPTH and hPTH, serum calcium and 1,25(OH)2vitamin D levels were normal. The lack of response to hPTH may be due to tachyphylaxis of the mPTH receptor (PTH1R) and/or impaired recognition of the mPTH1R. In contrast, the regulation of hPTH levels in the mouse was intact. A calcium-depleted diet increased serum mPTH and both intact and bioactive hPTH. mPTH and hPTH mRNA levels were also markedly increased. The calcimimetic R-568 dramatically decreased mPTH and hPTH serum levels. Administered recombinant fibroblast growth factor (FGF)23 decreased hPTH. Therefore, the regulation of hPTH gene expression and serum hPTH levels is intact in the transgenic mice, indicating preservation of the signal transduction of the parathyroid calcium receptor and the Klotho-FGF receptor between mouse and man.
Prior exercise improves survival, infarct healing, and left ventricular function after myocardial infarction
Authors: de Waard Monique C. , Duncker Dirk J.
Published: July 2009

We investigated the effects of voluntary wheel running before an acute myocardial infarction (MI) on survival, left ventricular (LV) remodeling and dysfunction and whether exercise before and after MI provides superior protection compared with either exercise intervention alone. After 2 wk of voluntary wheel running or sedentary housing, MI was induced in C57Bl/6 mice, after which exercise was stopped (EX-MI-SED and SED-MI-SED groups, where EX is exercise and SED is sedentary) or continued (EX-MI-EX and SED-MI-EX groups) for a period of 8 wk. Exercise after MI in SED-MI-EX mice had no effect on survival, the area of infarction, and global LV remodeling, but attenuated fibrosis and apoptosis in the remote myocardium and blunted LV dysfunction and pulmonary congestion compared with SED-MI-SED mice. Exercise before MI in both EX-MI-SED and EX-MI-EX mice decreased post-MI mortality compared with both SED-MI-SED and SED-MI-EX mice. Furthermore, in both pre-MI exercise groups, the infarct area was thicker, whereas interstitial fibrosis and apoptosis in the remote LV myocardium were blunted. In contrast, the ameliorating effects of either pre-MI or post-MI exercise alone on LV dysfunction were lost in EX-MI-EX mice, which may in part be related to the increased daily exercise distance in the first week post-MI in EX-MI-EX versus SED-MI-EX mice. In conclusion, exercise before or after MI blunted LV dysfunction, whereas only exercise before MI improved survival. These findings suggest that even when regular physical activity fails to prevent an acute MI, it can still act to improve cardiac function and survival after MI.
Simulation in Sensory Neurons Reveals a Key Role for Delayed Na+Current in Subthreshold Oscillations and Ectopic Discharge: Implications for Neuropathic Pain
Authors: Kovalsky Yifat , Amir Ron , Devor Marshall
Published: July 2009

Somata of primary sensory neurons are thought to contribute to the ectopic neural discharge that is implicated as a cause of some forms of neuropathic pain. Spiking is triggered by subthreshold membrane potential oscillations that reach threshold. Oscillations, in turn, appear to result from reciprocation of a fast active tetrodotoxin-sensitive Na+current ( INa+) and a passive outward IK+current. We previously simulated oscillatory behavior using a transient Hodgkin–Huxley-type voltage-dependent INa+and ohmic leak. This model, however, diverged from oscillatory parameters seen in live cells and failed to produce characteristic ectopic discharge patterns. Here we show that use of a more complete set of Na+conductances—which includes several delayed components—enables simulation of the entire repertoire of oscillation-triggered electrogenic phenomena seen in live dorsal root ganglion (DRG) neurons. This includes a physiological window of induction and natural patterns of spike discharge. An INa+component at 2–20 ms was particularly important, even though it represented only a tiny fraction of overall INa+amplitude. With the addition of a delayed rectifier IK+the singlet firing seen in some DRG neurons can also be simulated. The model reveals the key conductances that underlie afferent ectopia, conductances that are potentially attractive targets in the search for more effective treatments of neuropathic pain.
Functional Specialization of Medial Auditory Belt Cortex in the Alert Rhesus Monkey
Authors: Kuśmierek Paweł , Rauschecker Josef P.
Published: July 2009

Responses of neural units in two areas of the medial auditory belt (middle medial area [MM] and rostral medial area [RM]) were tested with tones, noise bursts, monkey calls (MC), and environmental sounds (ES) in microelectrode recordings from two alert rhesus monkeys. For comparison, recordings were also performed from two core areas (primary auditory area [A1] and rostral area [R]) of the auditory cortex. All four fields showed cochleotopic organization, with best (center) frequency [BF(c)] gradients running in opposite directions in A1 and MM than in R and RM. The medial belt was characterized by a stronger preference for band-pass noise than for pure tones found medially to the core areas. Response latencies were shorter for the two more posterior (middle) areas MM and A1 than for the two rostral areas R and RM, reaching values as low as 6 ms for high BF(c) in MM and A1, and strongly depended on BF(c). The medial belt areas exhibited a higher selectivity to all stimuli, in particular to noise bursts, than the core areas. An increased selectivity to tones and noise bursts was also found in the anterior fields; the opposite was true for highly temporally modulated ES. Analysis of the structure of neural responses revealed that neurons were driven by low-level acoustic features in all fields. Thus medial belt areas RM and MM have to be considered early stages of auditory cortical processing. The anteroposterior difference in temporal processing indices suggests that R and RM may belong to a different hierarchical level or a different computational network than A1 and MM.
Discharge Properties of Motor Units of the Abductor Hallucis Muscle During Cramp Contractions
Authors: Minetto Marco A. , Holobar Aleš , Botter Alberto , Farina Dario
Published: July 2009

We analyzed individual motor units during electrically elicited cramp contractions with the aim of characterizing the variability and degree of common oscillations in their discharges. Intramuscular and surface electromyographic (EMG) signals were detected from the abductor hallucis muscle of 11 healthy subjects (age 27.0 ± 3.7 yr) during electrically elicited cramps. In all, 48 motor units were identified from the intramuscular EMG. These motor units were active for 23.6 ± 16.2 s, during which their average discharge rate was 14.5 ± 5.1 pulses/s (pps) and their minimum and maximum rates were, respectively, 6.0 ± 0.8 and 25.0 ± 8.0 pps ( P < 0.001). The coefficient of variation for the interspike interval (ISI) was 44.6 ± 9.7% and doublet discharges constituted 4.1 ± 4.7% of the total number of discharges. In 38 motor units, the SD of the ISI was positively correlated to the mean ISI ( R2= 0.37, P < 0.05). The coherence spectrum between smoothed discharge rates of pairs of motor units showed one significant peak at 1.4 ± 0.4 Hz for 29 of the 96 motor unit pairs and two significant peaks at 1.3 ± 0.5 and 1.5 ± 0.5 Hz for 8 motor unit pairs. The cross-correlation function between pairs of discharge rates showed a significant peak (0.52 ± 0.11) in 26 motor unit pairs. In conclusion, motor units active during cramps showed a range of discharge rates similar to that observed during voluntary contractions but larger ISI variability, probably due to large synaptic noise. Moreover, the discharge rates of the active motor units showed common oscillations.
Models for the Extrapolation of Target Motion for Manual Interception
Authors: Soechting John F. , Juveli John Z. , Rao Hrishikesh M.
Published: July 2009

Intercepting a moving target requires a prediction of the target's future motion. This extrapolation could be achieved using sensed parameters of the target motion, e.g., its position and velocity. However, the accuracy of the prediction would be improved if subjects were also able to incorporate the statistical properties of the target's motion, accumulated as they watched the target move. The present experiments were designed to test for this possibility. Subjects intercepted a target moving on the screen of a computer monitor by sliding their extended finger along the monitor's surface. Along any of the six possible target paths, target speed could be governed by one of three possible rules: constant speed, a power law relation between speed and curvature, or the trajectory resulting from a sum of sinusoids. A go signal was given to initiate interception and was always presented when the target had the same speed, irrespective of the law of motion. The dependence of the initial direction of finger motion on the target's law of motion was examined. This direction did not depend on the speed profile of the target, contrary to the hypothesis. However, finger direction could be well predicted by assuming that target location was extrapolated using target velocity and that the amount of extrapolation depended on the distance from the finger to the target. Subsequent analysis showed that the same model of target motion was also used for on-line, visually mediated corrections of finger movement when the motion was initially misdirected.
Modulation of Stretch Reflexes of the Finger Flexors by Sensory Feedback From the Proximal Upper Limb Poststroke
Authors: Hoffmann Gilles , Kamper Derek G. , Kahn Jennifer H. , Rymer William Z. , Schmit Brian D.
Published: July 2009

Neural coupling of proximal and distal upper limb segments may have functional implications in the recovery of hemiparesis after stroke. The goal of the present study was to investigate whether the stretch reflex response magnitude of spastic finger flexor muscles poststroke is influenced by sensory input from the shoulder and the elbow and whether reflex coupling of muscles throughout the upper limb is altered in spastic stroke survivors. Through imposed extension of the metacarpophalangeal (MCP) joints, stretch of the relaxed finger flexors of the four fingers was imposed in 10 relaxed stroke subjects under different conditions of proximal sensory input, namely static arm posture (3 different shoulder/elbow postures) and electrical stimulation (surface stimulation of biceps brachii or triceps brachii, or none). Fast (300°/s) imposed stretch elicited stretch reflex flexion torque at the MCP joints and reflex electromyographic (EMG) activity in flexor digitorum superficialis. Both measures were greatest in an arm posture of 90° of elbow flexion and neutral shoulder position. Biceps stimulation resulted in greater MCP stretch reflex flexion torque. Fast imposed stretch also elicited reflex EMG activity in nonstretched heteronymous upper limb muscles, both proximal and distal. These results suggest that in the spastic hemiparetic upper limb poststroke, sensorimotor coupling of proximal and distal upper limb segments is involved in both the increased stretch reflex response of the finger flexors and an increased reflex coupling of heteronymous muscles. Both phenomena may be mediated through changes poststroke in the spinal reflex circuits and/or in the descending influence of supraspinal pathways.
Organization of Hue Selectivity in Macaque V2 Thin Stripes
Authors: Lim Heejin , Wang Yi , Xiao Youping , Hu Ming , Felleman Daniel J.
Published: July 2009

V2 has long been recognized to contain functionally distinguishable compartments that are correlated with the stripelike pattern of cytochrome oxidase activity. Early electrophysiological studies suggested that color, direction/disparity, and orientation selectivity were largely segregated in the thin, thick, and interstripes, respectively. Subsequent studies revealed a greater degree of homogeneity in the distribution of response properties across stripes, yet color-selective cells were still found to be most prevalent in the thin stripes. Optical recording studies have demonstrated that thin stripes contain both color-preferring and luminance-preferring modules. These thin stripe color-preferring modules contain spatially organized hue maps, whereas the luminance-preferring modules contain spatially organized luminance-change maps. In this study, the neuronal basis of these hue maps was determined by characterizing the selectivity of neurons for isoluminant hues in multiple penetrations within previously characterized V2 thin stripe hue maps. The results indicate that neurons within the superficial layers of V2 thin stripe hue maps are organized into columns whose aggregated hue selectivity is closely related to the hue selectivity of the optically defined hue maps. These data suggest that thin stripes contain hue maps not simply because of their moderate percentage of hue-selective neurons, but because of the columnar and tangential organization of hue selectivity.
Effects of VPAC2 Receptor Activation on Membrane Excitability and GABAergic Transmission in Subparaventricular Zone Neurons Targeted by Suprachiasmatic Nucleus
Authors: Hermes M.L.H.J. , Kolaj M. , Doroshenko P. , Coderre E. , Renaud L. P.
Published: July 2009

The hypothalamic suprachiasmatic nucleus (SCN) harbors the master circadian pacemaker. SCN neurons produce the amino acid γ-aminobutyric acid (GABA) and several peptide molecules for coordination and communication of their circadian rhythms. A subpopulation of SCN cells synthesizes vasoactive intestinal polypeptide (VIP) and provides a dense innervation of the subparaventricular zone (SPZ), an important CNS target of the circadian pacemaker. In this study, using patch-clamp recording techniques and rat brain slice preparations, the contribution of VIP to SCN efferent signaling to SPZ was evaluated by examining membrane responses of SPZ neurons to exogenous VIP receptor ligands. In ∼50% of the SPZ neurons receiving monosynaptic GABAA receptor–mediated inputs from SCN, bath-applied VIP (0.5–1 μM) resulted in a membrane depolarization caused by tetrodotoxin-resistant inward currents reversing at ∼−23 mV. These data suggest the existence of postsynaptic receptors that activate a nonselective cationic conductance. In addition, a subset of SPZ neurons showed an increase in the amplitude of SCN-evoked GABAergic inhibitory postsynaptic currents (IPSCs) and a decrease in their paired-pulse ratios. This, together with an increase in frequency of spontaneous and miniature IPSCs, implies the presence of presynaptic receptors that facilitate GABA release from SCN and possibly other synaptic terminals. The effects occurred in separate neurons and could be mimicked by the selective VPAC2 receptor agonist BAY 55-9837 (0.2–0.5 μM) and partially blocked by the VIP receptor antagonist VIP(6-28) (5 μM). The results indicate that VIP acts via both post- and presynaptic VPAC2 receptors to differentially modulate SCN GABAergic signaling to distinct subpopulations of SPZ neurons.
Efferent Control of Hair Cell and Afferent Responses in the Semicircular Canals
Authors: Boyle Richard , Rabbitt Richard D. , Highstein Stephen M.
Published: July 2009

The sensations of sound and motion generated by the inner ear are controlled by the brain through extensive centripetal innervation originating within the brain stem. In the semicircular canals, brain stem efferent neurons make synaptic contacts with mechanosensory hair cells and with the dendrites of afferent neurons. Here, we examine the relative contributions of efferent action on hair cells and afferents. Experiments were performed in vivo in the oyster toadfish, Opsanus tau. The efferent system was activated via electrical pulses to the brain stem and sensory responses to motion stimuli were quantified by simultaneous voltage recording from afferents and intracellular current- and/or voltage-clamp recordings from hair cells. Results showed synaptic inputs to both afferents and hair cells leading to relatively long-latency intracellular signaling responses: excitatory in afferents and inhibitory in hair cells. Generally, the net effect of efferent action was an increase in afferent background discharge and a simultaneous decrease in gain to angular motion stimuli. Inhibition of hair cells was likely the result of a ligand-gated opening of a major basolateral conductance. The reversal potential of the efferent-evoked current was just below the hair cell resting potential, thus resulting in a small hyperpolarization. The onset latency averaged about 90 ms and latency to peak response was 150–400 ms. Hair cell inhibition often outlasted afferent excitation and, in some cases, latched hair cells in the “off” condition for >1 s following cessation of stimulus. These features endow the animal with a powerful means to adjust the sensitivity and dynamic range of motion sensation.
Design of a Dual-Band Sectoral Antenna for Hiperlan2 Application Using Double Layers of Metallic Electromagnetic Band Gap (M-EBG) Materials as a Superstrate
Authors: Hajj M. , Chantalat R. , Jecko B.
Published: July 2009

A novel design of a sectoral antenna that utilizes a double layer Metallic Electromagnetic Band Gap (M-EBG) as a superstrate for dual band directivity enhancement is presented in this paper. We obtain the different operating frequencies by adjusting the distance of the lower M-EBG layer from printed patch antenna and also the height between upper and lower M-EBG layers. This antenna operates according to a sectoral radiation pattern form presenting a half power beamwidth of at least . The proposed structure presents more than 17 dB directivity enhancement at 5.25 GHz and 5.65 GHz as compared to those of a patch antenna with 9 dB directivity. The principle is explained and applied to a Hiperlan2 antenna.
vMAGIC—Automatic Code Generation for VHDL
Authors: Pohl Christopher , Paiz Carlos , Porrmann Mario
Published: July 2009

Automatic code generation is a standard method in software engineering, improving the code reliability as well as reducing the overall development time. In hardware engineering, automatic code generation is utilized within a number of development tools, the integrated code generation functionality, however, is not exposed to developers wishing to implement their own generators. In this paper, VHDL Manipulation and Generation Interface (vMAGIC), a Java library to read, manipulate, and write VHDL code is presented. The basic functionality as well as the designflow is described, stressing the advantages when designing with vMAGIC. Two real‐world examples demonstrate the power of code generation in hardware engineering.
Periodic Solution of Second‐Order Hamiltonian Systems with a Change Sign Potential on Time Scales
Authors: Su You-Hui , Li Wan-Tong
Published: July 2009

This paper is concerned with the second‐order Hamiltonian system on time scales 𝕋 of the form Δ‐a.e. t ∈ [0, T] 𝕋 , u(0) − u(T) = uΔ(ρ(0)) − uΔ(ρ(T)) = 0, where 0, T ∈ 𝕋. By using the minimax methods in critical theory, an existence theorem of periodic solution for the above system is established. As an application, an example is given to illustrate the result. This is probably the first time the existence of periodic solutions for second‐order Hamiltonian system on time scales has been studied by critical theory.
The Average Errors for the Grünwald Interpolation in the Wiener Space
Authors: Du Yingfang , Zhao Huajie
Published: July 2009

We determine the weakly asymptotically orders for the average errors
of the Grünwald interpolation sequences based on the Tchebycheff nodes
in the Wiener space. By these results we know that for the Lp‐norm
(2 ≤ q ≤ 4) approximation, the p‐average (1 ≤ p ≤ 4) error of some Grünwald interpolation sequences is weakly equivalent to the p‐average
errors of the best polynomial approximation sequence.
A Comprehensive Bioinformatics Analysis of the Nudix Superfamily inArabidopsis thaliana
Authors: Gunawardana D. , Likic V. A. , Gayler K. R.
Published: July 2009

Nudix enzymes are a superfamily with a conserved common reaction mechanism that provides the capacity for the hydrolysis of a broad spectrum of metabolites. We used hidden Markov models based on Nudix sequences from the PFAM and PROSITE databases to identify Nudix hydrolases encoded by theArabidopsisgenome. 25 Nudix hydrolases were identified and classified into 11 individual families by pairwise sequence alignments. Intron phases were strikingly conserved in each family. Phylogenetic analysis showed that all multimember families formed monophyletic clusters. Conserved familial sequence motifs were identified with the MEME motif analysis algorithm. One motif (motif 4) was found in three diverse families. All proteins containing motif 4 demonstrated a degree of preference for substrates containing an ADP moiety. We conclude that HMM model-based genome scanning and MEME motif analysis, respectively, can significantly improve the identification and assignment of function of new members of this mechanistically-diverse protein superfamily.
Prevalence of Underweight, Stunting, and Wasting among Children Infected with Human Immunodeficiency Virus in South India
Authors: Padmapriyadarsini C. , Pooranagangadevi N. , Chandrasekaran K. , Subramanyan Sudha , Thiruvalluvan C. , Bhavani P. K. , Swaminathan Soumya
Published: July 2009

Background. Growth failure is a common feature of children with human immunodeficiency virus (HIV) infection. Malnutrition increases mortality and may impair the response to antiretroviral treatment.Objective. Our objective was to describe the prevalence of stunting, underweight, and wasting in HIV-infected children in south India and to assess the utility of these parameters in predicting immune status.Methodology. In this cross-sectional study, anthropometric measurements and CD4 counts were performed on 231 HIV-infected children. scores for height for age, weight for age, and weight for height were correlated with CD4 cell counts and receiver operating characteristic curves plotted.Results. Prevalence of underweight was 63%, stunting 58%, and wasting 16%, respectively. 33–45% of children were moderately or severely malnourished even at CD4 >25%; sensitivity and specificity of stunting or underweight to predict HIV disease severity was low.Conclusions. Undernutrition and stunting are common among HIV-infected children at all stages of the disease in India. Early and aggressive nutritional intervention is required, if long-term outcomes are to be improved.
Investigation of the Surrounding Environment′s Influence on Gait Sensing Using a Plant as a Sensor
Authors: Hirobayashi Shigeki , Tamura Yusuke , Yamamoto Kazuhiro
Published: July 2009

Some animals and plants function as bioantennas in that changes in their surrounding environment produce variations in their bioelectric potentials. While the bioelectric potential is affected by living activities of the plant, it has been observed that the bioelectric potential can be reduced using plants. Thus, the influence of the life activity of a plant on the reception signal must be accounted for when a plant is used as a sensor. In this study, we produced an environmental change near a foliage plant growing in an indoor environment and examined the directivity of the plant′s sensing ability. The sensitivity of the plant was a roughly circular area centered on the location of the plant. We also investigated the influence of the number of leaves on the plant on its sensing ability and found that it decreased with a reduction in the number of leaves.
In addition, we monitored the effect of a person walking on the spot near the plant on the bioelectric potential of the plant. Six subjects stepped on the spot 50 cm from a rubber tree and we measured the variation in the bioelectric potential of the tree produced by this stepping motion. The results confirmed that stepping motion produces a measurable response in the bioelectric potential of a plant and that this response varies in synchrony with the subject′s stepping rate. Moreover, by conducting principal component analysis using the peak value of the spectrum characteristics of the measured bioelectric potential, cumulative proportion was found to reach nearly 97% at low‐frequency components up to the fifth peak.
The Meaning of Time and Covariant Superderivatives in Supermechanics
Authors: Salgado Gil , Vallejo-Rodríguez José A.
Published: July 2009

We present a review of the basics of supermanifold theory
(in the sense of Berezin‐Kostant‐Leites‐Manin) from a physicist′s
point of view. By considering a detailed example of what does it mean
the expression “to integrate an ordinary superdifferential equation”
we show how the appearance of anticommuting parameters playing the
role of time is very natural in this context. We conclude that in
dynamical theories formulated whithin the category of supermanifolds,
the space that classically parametrizes time (the real line ℝ)
must be replaced by the simplest linear supermanifold ℝ1|1.
This supermanifold admits several different Lie supergroup structures, and we
analyze from a group‐theoretic point of view what is the meaning of the usual
covariant superderivatives, relating them to a change in the underlying group law. This result is extended to the case of N‐supersymmetry.
Polymorphisms in the Renin-Angiotensin System and Outcome of Very-Low-Birthweight Infants
Authors: Spiegler J. , Gilhaus A. , König I.R. , Kattner E. , Vochem M. , Küster H. , Möller J. , Müller D. , Kribs A. , Segerer H. , Wieg C. , Nikischin W. , von der Wense A. , Gebauer C. , Herting E. , Göpel W.
Published: July 2009

Background: The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE-ins/del) and the angiotensin II type 1 receptor 1166A/C polymorphism (ATR1166A/C) were reported to be associated with several unfavorable outcome parameters in preterm infants like bronchopulmonary dysplasia, persistent ductus arteriosus and impaired insulin sensitivity. Objective: To confirm the above-mentioned associations in a large cohort of very-low-birthweight (VLBW) infants. Method: Clinical data of VLBW infants were prospectively recorded. The ACE-ins/del polymorphism and the ATR1166A/C polymorphism were determined by polymerase chain reaction in 1,209 and 1,168 infants, respectively. Results: There was no significant association between ACE-ins/del or ATR1166A/C genotype and outcome parameters (death, intraventricular hemorrhage, sepsis, bronchopulmonary dysplasia, ventilation, supplemental oxygen at discharge, postnatal treatment with insulin, surgery for intestinal perforation/necrotizing enterocolitis/retinopathy of prematurity/persistent ductus arteriosus. Conclusion: Both known functional polymorphisms of the renin-angiotensin system do not seem to be associated with the outcome of VLBW infants.
Apparent Diffusion Coefficient on Magnetic Resonance Imaging in Pons and in Corona Radiata and Relation with the Neurophysiologic Measurement and the Outcome in Very Preterm Infants
Authors: Kaukola Tuula , Perhomaa Marja , Vainionpää Leena , Tolonen Uolevi , Jauhiainen Jukka , Pääkkö Eija , Hallman Mikko
Published: July 2009

Background: New imaging techniques allow a detailed visualization of the brain and the findings possibly correlate with neurophysiologic measurements and neurosensory and motor outcomes. Postnatal clinical factors known to associate with neurologic disabilities may contribute to brain abnormalities not visible to the naked eye. Objectives: We evaluated whether quantitative measurement of organized water diffusion on MR imaging, apparent diffusion coefficient (ADC), relates to neurophysiologic function and to clinical risk factors and motor outcome in preterm infants. Methods: Diffusion-weighted imaging was successfully performed at term age on 30 infants born <32 weeks of gestation, birth weight <1,000 g. Infants with major destructive brain lesions were excluded from the final analysis (n = 2). ADC was calculated within regions of interest placed in pons and in white matter regions known to contain motor fibers. Brain stem auditory evoked potentials (BAEP) were registered at term age. Gross motor outcome was assessed using Griffiths Scales at 2 years of corrected age. Results: A positive correlation was found between ADC in the pons and the latency of wave III in BAEP (r = 0.619, p = 0.024). Need for inotrope support during the postnatal period and bronchopulmonary dysplasia associated with high ADC values in the pons and in the corona radiata. Infants with poor gross motor outcome had higher ADC in the corona radiata than infants with better outcome (mean = 1.343 vs. 1.197, p = 0.004). Conclusions: This is the first study to report a relationship between ADC and BAEP measurements in the pons. The study may add to the current knowledge about the relation between postnatal clinical factors and diffusion-weighted imaging when evaluating the high-risk infants.
Long-Term Trends in the Epidemiology of Neonatal Sepsis and Antibiotic Susceptibility of Causative Agents
Authors: van den Hoogen Agnes , Gerards Leo J. , Verboon-Maciolek Malgorzata A. , Fleer André , Krediet Tannette G.
Published: July 2009

Background: In an era with increased maternal antibiotic use, patterns in early- and late-onset sepsis and antibiotic susceptibility may have changed. Objectives: To identify longitudinal trends in causative microorganisms for neonatal sepsis and analyze antibiotic susceptibility of all blood isolates of infants with sepsis. Methods: Early- and late-onset sepsis cases from 29 years (1978–2006) were studied retrospectively, in five clusters of 5 years (period I–V) and one cluster of 4 years (period VI), including antibiotic susceptibility profiles of blood isolates during the years 1999–2006. Results: The incidence of early-onset sepsis decreased (p < 0.01) from 4% during period I (1978–1982) to 1.2% during period VI (2003–2006). 78% of the infants with group B streptococcal (GBS) sepsis were premature during period I, compared to 47% during period VI (p < 0.05). The incidence of early-onset Gram-negative infections remained low during all periods. The incidence of late-onset sepsis, predominantly caused by coagulase-negative staphylococci (CONS) and Staphylococcus aureus, increased since period III from 7.1 to 13.9% in period VI (p < 0.01). Infections due to fungi or yeasts were rare (incidence <0.3%). The majority of CONS blood isolates were oxacillin-resistant, but vancomycin-susceptible. 95% of CONS blood isolates were susceptible for first-generation cephalosporins. Amoxicillin/clavulanic acid-resistant Escherichia coli were infrequent causes of infection. Conclusions: The incidence of early-onset sepsis mainly caused by GBS decreased. In contrast, the incidence of late-onset sepsis, predominantly caused by CONS, increased significantly. The incidence of fungal and yeast infections remained low. The majority of CONS blood isolates were susceptible for first-generation cephalosporins.
G771C Polymorphism in the MLXIPL Gene Is Associated with a Risk of Coronary Artery Disease in the Chinese: A Case-Control Study
Authors: Pan Ling-Ai , Chen Yu-Cheng , Huang Hao , Zhang Li , Liu Rui , Li Xian , Qiang Ou , Zeng Zhi
Published: July 2009

Objectives: Previously, a genome-wide scan has identified a nonsynonymous single nucleotide polymorphism (rs3812316, G771C, Gln241His) in the MLXIPL gene that is associated with the level of plasma triglycerides. However, no data are available on the association of this polymorphism with coronary artery disease (CAD) in the Chinese population. The aim of this study was to evaluate the association between a gene polymorphism related to triglyceride metabolism and CAD. Methods: The genotype of the polymorphism in the MLXIPL gene was determined in 352 CAD patients and 152 CAD-free subjects. All of the participants were selected to study the MLXIPL gene rs3812316 polymorphism using the polymerase chain reaction restriction fragment length polymorphism method. Results: In Chinese participants, we observed that there was a significant difference in genotype between the cases and controls (p = 0.002). After allowance for potential confounders, unconditional logistic analysis revealed that the SNP was significantly related to a risk in CAD patients (adjusted OR 2.96, 95% CI 1.30–5.08; p =0.004). We also found that there was a significant association between the single nucleotide polymorphism and plasma triglyceride levels (OR 1.28, 95% CI 1.061–1.542; p < 0.05). Conclusion: The gene sequence variation in the MLXIPL gene may serve as a novel genetic marker for the risk of significant CAD.
White Matter Lesions and Brain Atrophy: More than Shared Risk Factors? A Systematic Review
Authors: Appelman Auke P.A. , Exalto Lieza G. , van der Graaf Yolanda , Biessels Geert Jan , Mali Willem P.T.M. , Geerlings Mirjam I.
Published: July 2009

Background: White matter lesions (WML) and brain atrophy are often found on MRI in the elderly. Shared vascular risk factors may be an explanation for their concomitance. However, disturbances of white matter integrity could also be involved in the pathogenesis of brain atrophy. Our objective was to systematically review studies that investigated the relation between WML and brain atrophy on MRI, and to investigate whether there is sufficient evidence to indicate that this relation is independent of shared risk factors. Methods: We searched PubMed for studies published in English between 1980 and October 2007, combining search terms for WML and brain atrophy. Articles that studied the relation between WML and brain atrophy were included if they met the following criteria: (1) original study, (2) MRI used for imaging, (3) assessment methods for WML and brain atrophy specified, and (4) a sample size of at least 20 participants. We recorded type and age of the study population, type and assessment of WML and brain atrophy, and variables for which adjustments were made in the analyses. Results: We identified 48 studies that met our inclusion criteria. A significant relation between WML and brain atrophy was found in 37 out of 48 studies. The source of the study population (e.g. clinic or population based) did not affect this relation. However, only 10 studies adjusted for shared risk factors, of which 9 found an association. Conclusions: The majority of studies found an association between WML and brain atrophy, but it is not yet clear if this association is independent of shared risk factors.
Computer-Based Test to Quantify the Pulfrich Stereophenomenon
Authors: Stadelmann Raphael , Jiang Xiaoyi , Mojon Daniel S.
Published: July 2009

Background:Many eye and brain diseases may induce a spontaneous Pulfrich phenomenon (PP), a stereoillusion leading to misjudgments of objects moving in a frontoparallel plane. Since, until now, no simple PP quantification method has been available, a computer pendulum (CP) system was developed and evaluated. Methods: In 5 normal subjects, PP was induced with different neutral density filters. The resulting retardations were measured with the gold standard (a mechanical pendulum; MP), and compared to a CP, allowing the generation of interocular image phase shifts. Results: A high correlation between MP and CP was found (r = 0.97, p < 0.001; slope 0.91, p > 0.1 for difference with slope 1.0). A multiple linear regression showed a significant influence of the filter density and the subject tested. The type of pendulum (MP or CP) and the side on which the filter was held were nonsignificant. Conclusions: A CP allowing an interocular image phase shift can be used as an alternative to a MP for quantification of a PP. Thus, this principle would allow the development of software or an Internet-based test for PP quantification. However, in some subjects, the CP will overestimate and in others underestimate the real retardation measured with the MP.
Advanced Glycation End Products Suppress Neuropilin-1 Expression in Podocytes by a Reduction in Sp1-Dependent Transcriptional Activity
Authors: Bondeva Tzvetanka , Wolf Gunter
Published: July 2009

Background: Neuropilin-1 (NRP1) is a transmembrane glycoprotein, initially defined as a receptor for members of the semaphorin family. We observed that NRP1 expression was downregulated by the addition of advanced glycation end products-modified bovine serum albumin (AGE-BSA). The present study was undertaken to unravel the molecular mechanisms underlying AGE-BSA-mediated NRP1 suppression. Methods: Expression of NRP1 was analyzed in podocytes. The transcriptional activity of the NRP1 promoter was investigated using wild-type and mutant NRP1 promoter reporter constructs. Electrophoretic mobility assays were performed. Results: NRP1 expression was downregulated in podocytes by the addition of AGE-BSA. In contrast, phorbolester induced NRP1 mRNA and protein expression. The wild-type promoter transcriptional activity was significantly reduced when podocytes were treated with AGE-BSA compared with control, unmodified BSA. Point mutations of proximal and distal Sp1-like sites inhibited basal NRP1 promoter activity. AGE-BSA failed to further suppress transcriptional activity of these constructs. Double mutation of the Sp1A and Sp1B binding sites completely abolished NRP1 transcriptional activity. Gel shift analysis showed a specific binding of the Sp1 transcription factor. Treatment of podocytes with AGE-BSA revealed a decrease in Sp1 binding to consensus sequences, but no effect on AP1 binding. Conclusions: AGE-BSA inhibits NRP1 promoter transcriptional activity in podocytes by reducing the binding ability of the Sp1 transcription factor to attach to the NRP1 promoter.
Structure of the Madden–Julian Oscillation in the Superparameterized CAM
Authors: Benedict James J. , Randall David A.
Published: July 2009

The detailed dynamic and thermodynamic space–time structures of the Madden–Julian oscillation (MJO) as simulated by the superparameterized Community Atmosphere Model version 3.0 (SP-CAM) are analyzed. Superparameterization involves substituting conventional boundary layer, moist convection, and cloud parameterizations with a configuration of cloud-resolving models (CRMs) embedded in each general circulation model (GCM) grid cell. Unlike most GCMs that implement conventional parameterizations, the SP-CAM displays robust atmospheric variability on intraseasonal space and time (30–60 days) scales. The authors examine a 19-yr SP-CAM simulation based on the Atmospheric Model Intercomparison Project protocol, forced by prescribed sea surface temperatures. Overall, the space–time structures of MJO convective disturbances are very well represented in the SP-CAM. Compared to observations, the model produces a similar vertical progression of increased moisture, warmth, and heating from the boundary layer to the upper troposphere as deep convection matures. Additionally, important advective and convective processes in the SP-CAM compare favorably with those in observations. A deficiency of the SP-CAM is that simulated convective intensity organized on intraseasonal space–time scales is overestimated, particularly in the west Pacific. These simulated convective biases are likely due to several factors including unrealistic boundary layer interactions, a lack of weakening of the simulated disturbance over the Maritime Continent, and mean state differences.
The Final Warming Date of the Antarctic Polar Vortex and Influences on its Interannual Variability
Authors: Haigh Joanna D. , Roscoe Howard K.
Published: July 2009

More than 40 years of radiosonde data from two Antarctic stations are examined for changes in the date of the final stratospheric warming that occurs each year as the vortex breaks up in spring/summer. A new measure of this date is derived that does not rely on specification of a threshold, as has been common previously. The date of final warming takes between 10 and 40 days to progress from 30 to 100 hPa and occurs 20–30 days later in the 1990s than in the 1960s. Multiple linear regression analyses of these final warming dates, and also of the vertical profile of the southern annular mode (SAM), are presented. Only a weak signal is found for a linear trend, but a significant response is found throughout the atmosphere to ozone mass deficit (OMD), representing stratospheric ozone loss. In the SAM a significant response to the combined influence of solar variability and the quasi-biennial oscillation (QBO) is also found. The seasonal evolution of these signals in the NCEP Reanalysis zonal mean temperatures is examined and their influences on final warming dates is calculated. This confirms that ozone loss is primarily responsible for the delayed warming in the lower stratosphere in recent years, but suggests that the phase of solar activity and the QBO also have an effect. The apparent downward progression of the signal of OMD, and of the combined solar activity and QBO, extends well into the upper troposphere and appears to be caused simply by a delay in the top-down breakup of the vortex.
Observed Feedback between Winter Sea Ice and the North Atlantic Oscillation
Authors: Strong Courtenay , Magnusdottir Gudrun , Stern Hal
Published: July 2009

Feedback between the North Atlantic Oscillation (NAO) and winter sea ice variability is detected and quantified using approximately 30 years of observations, a vector autoregressive model (VAR), and testable definitions of Granger causality and feedback. Sea ice variability is quantified based on the leading empirical orthogonal function of sea ice concentration over the North Atlantic [the Greenland Sea ice dipole (GSD)], which, in its positive polarity, has anomalously high sea ice concentrations in the Labrador Sea region to the southwest of Greenland and low sea ice concentrations in the Barents Sea region to the northeast of Greenland. In weekly data for December through April, the VAR indicates that NAO index (N) anomalies cause like-signed anomalies of the standardized GSD index (G), and that G anomalies in turn cause oppositely signed anomalies of N. This negative feedback process operates explicitly on lags of up to four weeks in the VAR but can generate more persistent effects because of the autocorrelation of G. Synthetic data are generated with the VAR to quantify the effects of feedback following realistic local maxima of N and G, and also for sustained high values of G. Feedback can change the expected value of evolving system variables by as much as a half a standard deviation, and the relevance of these results to intraseasonal and interannual NAO and sea ice variability is discussed.
Evaluating Cloud Frequency of Occurrence and Cloud-Top Height Using Spaceborne Lidar Observations
Authors: Ahlgrimm Maike , Randall David A. , Köhler Martin
Published: July 2009

A strategy for model evaluation using spaceborne lidar observations is presented. Observations from the Geoscience Laser Altimeter System are recast onto the model grid to assess the ability of two versions of the Integrated Forecasting System to model marine stratocumulus clouds. The two model versions differ primarily in their treatment of clear and cloudy boundary layers. For each grid column, a representative cloud fraction and cloud-top height are derived from the observations, as well as from the model. By applying the same threshold criteria for cloud fraction and cloud-top height independently to model and observations, samples containing marine stratocumulus clouds can be identified. The frequency of occurrence, cloud fraction, and cloud-top height distributions for all samples thus identified are compared. The evaluation shows improvements in the frequency of occurrence and cloud-top height of marine stratocumulus, though modeled cloud tops remain lower than observed. Additional runs reveal a sensitivity to the strength of the environmental mixing that occurs during the test parcel ascent of the boundary layer parameterization. With a more aggressive parcel, the modeled clouds agree even better with observations.
In-Cloud Icing in the Columbia Basin
Authors: Thorkildson Ronald M. , Jones Kathleen F. , Emery Maggie K.
Published: July 2009

On 24 November 2005, 11 lattice steel towers of a high-voltage electrical transmission line running along the edge of an escarpment were damaged by an accumulation of rime on overhead ground wires. Cold air pooling in the Columbia basin of eastern Washington several days before the failure led to the formation of low-level fog and low clouds with temperatures below freezing at the elevation of the transmission line. The liquid water content profile of the cloud formed by air rising over Badger Mountain north of Wenatchee, Washington, is estimated using the air temperature, dewpoint temperature, and air pressure as measured at Wenatchee in the Columbia River valley below the line. Cloud median volume droplet diameters are estimated using typical droplet concentrations. The validity of the computed liquid water content is determined by comparing the measured cloud-base heights at Wenatchee with the calculated cloud-base heights. The mass and density of ice accreted on the ground wires and conductors of the transmission line are modeled using assumed wind speeds at the top of the escarpment with the estimated cloud properties. Results are compared with the density and mass of an ice sample retrieved from the field. This event is compared with other modeled in-cloud icing events from 1973 to 2007 using the period of record of Wenatchee weather data. This paper illustrates an approach for estimating the severity of in-cloud icing on the wires of transmission lines subject to cloud liquid water contents that have been enhanced by the local terrain.
Numerical Simulation of Tornadogenesis in an Outer-Rainband Minisupercell of Typhoon Shanshan on 17 September 2006
Authors: Mashiko Wataru , Niino Hiroshi , Kato Teruyuki
Published: July 2009

On 17 September 2006, three tornadoes occurred along the east coast of Kyusyu Island in western Japan during the passage of an outer rainband in the right-front quadrant of Typhoon Shanshan. To clarify the structure of the tornado-producing storms and the mechanism of tornadogenesis, quadruply nested numerical simulations were performed using a nonhydrostatic model with an innermost horizontal grid spacing of 50 m. Several simulated convective storms in the outermost rainband exhibited characteristics of a minisupercell. One storm had a strong rotating updraft of more than 30 m s−1 and a large vertical vorticity exceeding 0.06 s−1. This storm spawned a tornado when the low-level mesocyclone intensified. The tornado was generated on the rear-flank gust front near the mesocyclone center when a secondary rear-flank downdraft (RFD) surge advanced cyclonically around the low-level mesocyclone and overtook the rear-flank gust front at its left-front edge. Backward trajectories and vorticity budget analysis along the trajectories indicate that the secondary RFD surge played a key role in tornadogenesis by barotropically transporting the large streamwise vorticity associated with the environmental low-level veering shear toward the surface. When the secondary RFD outflow surge boundary reached the rear-flank gust front, the horizontal convergence was enhanced, contributing to the rapid amplification of the vertically tilted streamwise vorticity. The diagnostics of the vertical momentum equation and several sensitivity experiments demonstrated that precipitation loading in the area of a hook-shaped precipitation pattern was crucial to the behavior of the RFD and the subsequent tornadogenesis.