bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic fetal hypoglycemia inhibits the later steps of stimulus-secretion coupling in pancreatic β-cells
Authors: Rozance Paul J. , Limesand Sean W. , Zerbe Gary O. , Hay William W.
Published: January 2007

We measured the impact of chronic late gestation hypoglycemia on pancreatic islet structure and function to determine the cause of decreased insulin secretion in this sheep model of fetal nutrient deprivation. Late gestation hypoglycemia did not decrease pancreas weight, insulin content, β-cell area, β-cell mass, or islet size. The pancreatic islet isolation procedure selected a group of islets that were larger and had an increased proportion of β-cells compared with islets measured in pancreatic sections, but there were no morphologic differences between islets isolated from control and hypoglycemic fetuses. The rates of glucose-stimulated pancreatic islet glucose utilization (126.2 ± 25.3 pmol glucose·islet−1·h−1, hypoglycemic, vs. 93.5 ± 5.5 pmol glucose·islet−1·h−1, control, P = 0.47) and oxidation (10.5 ± 1.7 pmol glucose·islet−1·h−1, hypoglycemic, vs. 10.6 ± 1.6 pmol glucose·islet−1·h−1, control) were not different in hypoglycemic fetuses compared with control fetuses. Chronic late gestation hypoglycemia decreased insulin secretion in isolated pancreatic islets by almost 70% in response to direct nonnutrient membrane depolarization and in response to increased extracellular calcium entry. β-Cell ultrastructure was abnormal with markedly distended rough endoplasmic reticulum in three of the seven hypoglycemic fetuses studied, but in vitro analysis of hypoglycemic control islets showed no evidence that these changes represented endoplasmic reticulum stress, as measured by transcription of glucose regulatory protein-78 and processing of X-box binding protein-1. In conclusion, these studies show that chronic hypoglycemia in late gestation decreases insulin secretion by inhibiting the later steps of stimulus-secretion coupling after glucose metabolism, membrane depolarization, and calcium entry.
Angiotensin II increases adipose angiotensinogen expression
Authors: Lu Hong , Boustany-Kari Carine M. , Daugherty Alan , Cassis Lisa A.
Published: January 2007

In addition to the well-defined contribution of the liver, adipose tissue has been recognized as an important source of angiotensinogen (AGT). The purpose of this study was to define the angiotensin II (ANG II) receptors involved in regulation of adipose AGT and the relationship of this control to systemic AGT and/or angiotensin peptide concentrations. In LDL receptor-deficient (LDLR−/−) male mice, adipose mRNA abundance of AGT was 68% of that in liver, and adipose mRNA abundance of the angiotensin type 1a (AT1a) receptor (AT1aR) was 38% of that in liver, whereas mRNA abundance of the angiotensin type 2 (AT2) receptor (AT2R) was 57% greater in adipose tissue than in liver. AGT and angiotensin peptide concentrations were decreased in plasma of AT1aR-deficient (AT1aR−/−) mice and were paralleled by reductions in AGT expression in liver. In contrast, adipose AGT mRNA abundance was unaltered in AT1aR−/−mice. AT2R−/−mice exhibited elevated plasma angiotensin peptide concentrations and marked elevations in adipose AGT and AT1aR mRNA abundance. Increases in adipose AGT mRNA abundance in AT2R−/−mice were abolished by losartan. In contrast, liver AGT and AT1aR mRNA abundance were unaltered in AT2R−/−mice. Infusion of ANG II for 28 days into LDLR−/−mice markedly increased adipose AGT and AT1aR mRNA but did not alter liver AGT and AT1aR mRNA. These results demonstrate that differential mRNA abundance of AT1a/AT2receptors in adipose tissue vs. liver contributes to tissue-specific ANG II-mediated regulation of AGT. Chronic infusion of ANG II robustly stimulated AT1aR and AGT mRNA abundance in adipose tissue, suggesting that adipose tissue serves as a primary contributor to the activated systemic renin-angiotensin system.
Glucose transporter isoform-3 mutations cause early pregnancy loss and fetal growth restriction
Authors: Ganguly Amit , McKnight Robert A. , Raychaudhuri Santanu , Shin Bo-Chul , Ma Zhigui , Moley Kelle , Devaskar Sherin U.
Published: January 2007

Glucose transporter isoform-3 (GLUT3) is the trophoblastic facilitative glucose transporter. To investigate the role of this isoform in embryonic development, we created a novel GLUT3-null mouse and observed arrested early embryonic development and loss at neurulation stage when both alleles were mutated. This loss occurred despite the presence of other related isoforms, particularly GLUT1. In contrast, when a single allele was mutated, despite increased embryonic cell apoptosis, adaptive changes in the subcellular localization of GLUT3 and GLUT1 in the preimplantation embryo led to postimplantation survival. This survival was compromised by decreased GLUT3-mediated transplacental glucose transport, causing late-gestation fetal growth restriction. This yielded young male and female adults demonstrating catch-up growth, with normal basal glucose, insulin, insulin-like growth factor-I and IGF-binding protein-3 concentrations, fat and lean mass, and glucose and insulin tolerance. We conclude that GLUT3 mutations cause a gene dose-dependent early pregnancy loss or late-gestation fetal growth restriction despite the presence of embryonic and placental GLUT1 and a compensatory increase in system A amino acid placental transport. This critical life-sustaining functional role for GLUT3 in embryonic development provides the basis for investigating the existence of human GLUT3 mutations with similar consequences during early pregnancy.
Hepatic autoregulation: response of glucose production and gluconeogenesis to increased glycogenolysis
Authors: Staehr Peter , Hother-Nielsen Ole , Beck-Nielsen Henning , Roden Michael , Stingl Harald , Holst Jens J. , Jones Paul K. , Chandramouli Visvanathan , Landau Bernard R.
Published: January 2007

The effect of increased glycogenolysis, simulated by galactose's conversion to glucose, on the contribution of gluconeogenesis (GNG) to hepatic glucose production (GP) was determined. The conversion of galactose to glucose is by the same pathway as glycogen's conversion to glucose, i.e., glucose 1-phosphate → glucose 6-phosphate → glucose. Healthy men ( n = 7) were fasted for 44 h. At 40 h, hepatic glycogen stores were depleted. GNG then contributed ∼90% to a GP of ∼8 μmol·kg−1·min−1. Galactose, 9 g/h, was infused over the next 4 h. The contribution of GNG to GP declined from ∼90% to 65%, i.e., by ∼2 μmol·kg−1·min−1. The rate of galactose conversion to blood glucose, measured by labeling the infused galactose with [1-2H]galactose ( n = 4), was also ∼2 μmol·kg−1·min−1. The 41st h GP rose by ∼1.5 μmol·kg−1·min−1and then returned to ∼9 μmol·kg−1·min−1, while plasma glucose concentration increased from ∼4.5 to 5.3 mM, accompanied by a rise in plasma insulin concentration. Over 50% of the galactose infused was accounted for in blood glucose and hepatic glycogen formation. Thus an increase in the rate of GP via the glycogenolytic pathway resulted in a concomitant decrease in the rate of GP via GNG. While the compensatory response to the galactose administration was not complete, since GP increased, hepatic autoregulation is operative in healthy humans during prolonged fasting.
Possible CaMKK-dependent regulation of AMPK phosphorylation and glucose uptake at the onset of mild tetanic skeletal muscle contraction
Authors: Jensen Thomas E. , Rose Adam J. , Jørgensen Sebastian B. , Brandt Nina , Schjerling Peter , Wojtaszewski Jørgen F. P. , Richter Erik A.
Published: January 2007

The Ca2+/calmodulin (CaM) competitive inhibitor KN-93 has previously been used to evaluate 5′-AMP-activated protein kinase (AMPK)-independent Ca2+-signaling to contraction-stimulated glucose uptake in muscle during intense electrical stimulation ex vivo. With the use of low-intensity tetanic contraction of mouse soleus and extensor digitorum longus (EDL) muscles ex vivo, this study demonstrates that KN-93 can potently inhibit AMPK phosphorylation and activity after 2 min but not 10 min of contraction while strongly inhibiting contraction-stimulated 2-deoxyglucose uptake at both the 2- and 10-min time points. These data suggest inhibition of Ca2+/CaM-dependent signaling events upstream of AMPK, the most likely candidate being the novel AMPK kinase CaM-dependent protein kinase kinase (CaMKK). CaMKK protein expression was detected in mouse skeletal muscle. Similar to KN-93, the CaMKK inhibitor STO-609 strongly reduced AMPK phosphorylation and activity at 2 min and less potently at 10 min. Pretreatment with STO-609 inhibited contraction-stimulated glucose uptake at 2 min in soleus, but not EDL, and in both muscles after 10 min. Neither KN-93 nor STO-609 inhibited 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside-stimulated glucose uptake, AMPK phosphorylation, or recombinant LKB1 activity, suggestive of an LKB1-independent effect. Finally, neither KN-93 nor STO-609 had effects on the reductions in glucose uptake seen in mice overexpressing a kinase-dead AMPK construct, indicating that the effects of KN-93 and STO-609 on glucose uptake require inhibition of AMPK activity. We propose that CaMKKs act in mouse skeletal muscle regulating AMPK phosphorylation and glucose uptake at the onset of mild tetanic contraction and that an intensity- and/or time-dependent switch occurs in the relative importance of AMPKKs during contraction.
Glucose and insulin improve cardiac efficiency and postischemic functional recovery in perfused hearts from type 2 diabetic (db/db) mice
Authors: Hafstad Anne D. , Khalid Ahmed M. , How Ole-Jakob , Larsen Terje S. , Aasum Ellen
Published: January 2007

Hearts from type 2 diabetic ( db/ db) mice demonstrate altered substrate utilization with high rates of fatty acid oxidation, decreased functional recovery following ischemia, and reduced cardiac efficiency. Although db/ db mice show overall insulin resistance in vivo, we recently reported that insulin induces a marked shift toward glucose oxidation in isolated perfused db/ db hearts. We hypothesize that such a shift in metabolism should improve cardiac efficiency and consequently increase functional recovery following low-flow ischemia. Hearts from db/ db and nondiabetic ( db/+) mice were perfused with 0.7 mM palmitate plus either 5 mM glucose (G), 5 mM glucose and 300 μU/ml insulin (GI), or 33 mM glucose and 900 μU/ml insulin (HGHI). Substrate oxidation and postischemic recovery were only moderately affected by GI and HGHI in db/+ hearts. In contrast, GI and particularly HGHI markedly increased glucose oxidation and improved postischemic functional recovery in db/ db hearts. Cardiac efficiency was significantly improved in db/ db, but not in db/+ hearts, in the presence of HGHI. In conclusion, insulin and glucose normalize cardiac metabolism, restore efficiency, and improve postischemic recovery in type 2 diabetic mouse hearts. These findings may in part explain the beneficial effect of glucose-insulin-potassium therapy in diabetic patients with cardiac complications.
Sucrose feeding during pregnancy and lactation elicits distinct metabolic response in offspring of an inbred genetic model of metabolic syndrome
Authors: Šedová Lucie , Šeda Ondřej , Kazdová Ludmila , Chylíková Blanka , Hamet Pavel , Tremblay Johanne , Křen Vladimír , Křenová Drahomíra
Published: January 2007

The importance of early environment, including maternal diet during pregnancy, is suspected to play a major role in pathogenesis of metabolic syndrome and related conditions. One of the proposed mechanisms is a mismatch between the prenatal and postnatal environments, leading to misprogramming of the metabolic and signaling pathways of the developing fetus. We assessed whether the exposure to high-sucrose diet (HSD) alleviates the detrimental effects of sucrose feeding in later life (predictive adaptive hypothesis) in a highly inbred model of metabolic syndrome, the PD/Cub rat. Rat dams were continuously fed either standard or HSD (70% calories as sucrose) starting 1 wk before breeding, throughout pregnancy, at birth, and until weaning of the offspring. After weaning, all male offspring were fed HSD until the age of 20 wk, when detailed metabolic and morphometric profiles were ascertained. The early life exposure to a sucrose-rich diet resulted in distinct responses to longtime postnatal HSD feeding. Offspring of the sucrose-fed mothers displayed higher adiposity and substantial increases in triglyceride liver content together with unfavorable distribution of cholesterol into lipoprotein subfractions. On the other hand, their adiponectin concentrations were significantly higher, and insulin sensitivity of skeletal muscle was enhanced compared with the offspring of standard diet-fed mothers. Triglycerides, free fatty acids, overall glucose tolerance, and the insulin sensitivity of adipose tissue were comparable in both groups. In the genetically identical animals, maternal HSD feeding elicited a variety of subtle effects but did not lead to predictive adaptive protection from most HSD-induced metabolic derangements.
Intestinal epithelial cell-derived interleukin-7: a mechanism for the alteration of intraepithelial lymphocytes in a mouse model of total parenteral nutrition
Authors: Yang Hua , Sun Xiaoyi , Haxhija Emir Q. , Teitelbaum Daniel H.
Published: January 2007

Total parenteral nutrition (TPN), with the absence of enteral nutrition, results in profound changes to both intestinal epithelial cells (EC) as well as the adjacent intraepithelial lymphocyte (IEL) population. Intestinal EC are a rich source of IL-7, a critical factor to support the maintenance of several lymphoid tissues, and TPN results in marked EC changes. On this basis, we hypothesized that TPN would diminish EC-derived IL-7 expression and that this would contribute to the observed changes in the IEL population. Mice received enteral food and intravenous crystalloid solution (control group) or TPN. TPN administration significantly decreased EC-derived IL-7 expression, along with significant changes in IEL phenotype; decreased IEL proliferation; and resulted in a marked decrease in IEL numbers. To better determine the relevance of TPN-related changes in IL-7, TPN mice supplemented with exogenous IL-7 or mice allowed ad libitum feeding and treated with exogenous administration of anti-IL-7 receptor (IL-7R) antibody were also studied. Exogenous IL-7 administration in TPN mice significantly attenuated TPN-associated IEL changes, whereas blocking IL-7R in normal mice resulted in several similar changes in IEL to those observed with TPN. These findings suggest that a decrease in EC-derived IL-7 expression may be a contributing mechanism to account for the observed TPN-associated IEL changes.
Attenuated vasoconstrictor responses to endothelin in afferent arterioles during a high-salt diet
Authors: Schneider Markus P. , Inscho Edward W. , Pollock David M.
Published: January 2007

Endothelin-1 (ET-1) is increased in rats on a high-salt (HS) diet and participates in salt-dependent hypertension. Afferent arterioles (AA) are important for long-term blood pressure control, and therefore we hypothesized that a HS diet would alter their responsiveness to ET-1. Sprague-Dawley rats were fed either a normal-salt (NS; 0.66% NaCl) or HS (8%) diet for 1 wk. Diameters of AA were determined in response to increasing concentrations of big ET-1, ET-1, sarafotoxin 6c (S6c), or norepinephrine (NE), using the blood-perfused juxtamedullary nephron technique. ET-1 responses were also determined during blockade of endothelin type A (ETA) or type B (ETB) receptors with 10 nM ABT-627 or 30 nM A-192621, respectively. Expression of ETAand ETBreceptors was determined in renal microvessels. Responses of AA to big ET-1, ET-1, and S6c were significantly attenuated during a HS diet (e.g., response to 10−10M ET-1 in NS vs. HS rats: −52.5 ± 10.2 vs. +5.6 ± 11.3% of control diameter; P < 0.05), with no change in the responses to NE. ETB, but not ETAreceptor blockade abolished the different response to ET-1 between the NS and HS groups. ETBreceptor expression in renal microvessels was increased in response to HS (17.7 ± 2.4 vs. 6.6 ± 3.0% of β-actin, P = 0.02), whereas ETAreceptor expression was unchanged. These results suggest that the reduced vasoconstrictor response of AA to endothelin peptides during a HS diet is mediated by increased vasodilatory function of endothelial ETBreceptors. By preserving renal blood flow, this may be an important mechanism to restore sodium balance during a HS diet.
Psychophysical Evidence for Long-Term Potentiation of C-Fiber and Aδ-Fiber Pathways in Humans by Analysis of Pain Descriptors
Authors: Hansen Niels , Klein Thomas , Magerl Walter , Treede Rolf-Detlef
Published: January 2007

Long-term potentiation of human pain perception (nociceptive LTP) to single electrical test stimuli was induced by high-frequency stimulation (HFS) of cutaneous nociceptive afferents. Numerical pain ratings and a list of sensory pain descriptors disclosed the same magnitude of nociceptive LTP (23% increase for >60 min, P < 0.001), whereas affective pain descriptors were not significantly enhanced. Factor analysis of the sensory pain descriptors showed that facilitation was restricted to two factors characterized by hot and burning (+41%) and piercing and stinging (+21%, both P < 0.01), whereas a factor represented by throbbing and beating was not significantly increased (+9%, P = 0.47). The increased perception of the burning pain quality for >1 h after HFS is interpreted as a LTP-like facilitation of the conditioned cutaneous C-fiber pathway. Additionally, the increase of the stinging pain quality supplied evidence for facilitation of a sharpness-sensitive Aδ-fiber pathway.
Network Modeling of Adult Neurogenesis: Shifting Rates of Neuronal Turnover Optimally Gears Network Learning according to Novelty Gradient
Authors: Chambers R. Andrew , Conroy Susan K.
Published: January 2007

Apoptotic and neurogenic events in the adult hippocampus are hypothesized to play a role in cognitive responses to new contexts. Corticosteroid-mediated stress responses and other neural processes invoked by substantially novel contextual changes may regulate these processes. Using elementary three-layer neural networks that learn by incremental synaptic plasticity, we explored whether the cognitive effects of differential regimens of neuronal turnover depend on the environmental context in terms of the degree of novelty in the new information to be learned. In “adult” networks that had achieved mature synaptic connectivity upon prior learning of the Roman alphabet, imposition of apoptosis/neurogenesis before learning increasingly novel information (alternate Roman < Russian < Hebrew) reveals optimality of informatic cost benefits when rates of turnover are geared in proportion to the degree of novelty. These findings predict that flexible control of rates of apoptosis-neurogenesis within plastic, mature neural systems optimizes learning attributes under varying degrees of contextual change, and that failures in this regulation may define a role for adult hippocampal neurogenesis in novelty- and stress-responsive psychiatric disorders.
Temporal Order is Coded Temporally in the Brain: Early Event-related Potential Latency Shifts Underlying Prior Entry in a Cross-modal Temporal Order Judgment Task
Authors: Vibell J. , Klinge C. , Zampini M. , Spence C. , Nobre A. C.
Published: January 2007

The speeding-up of neural processing associated with attended events (i.e., the prior-entry effect) has long been proposed as a viable mechanism by which attention can prioritize our perception and action. In the brain, this has been thought to be regulated through a sensory gating mechanism, increasing the amplitudes of early evoked potentials while leaving their latencies unaffected. However, the majority of previous research has emphasized speeded responding and has failed to emphasize fine temporal discrimination, thereby potentially lacking the sensitivity to reveal putative modulations in the timing of neural processing. In the present study, we used a cross-modal temporal order judgment task while shifting attention between the visual and tactile modalities to investigate the mechanisms underlying selective attention electrophysiologically. Our results indicate that attention can indeed speed up neural processes during visual perception, thereby providing the first electrophysiological support for the existence of prior entry.
Expectancy Induces Dynamic Modulation of Corticospinal Excitability
Authors: van Elswijk Gijs , Kleine Bert U. , Overeem Sebastiaan , Stegeman Dick F.
Published: January 2007

Behavioral studies using motor preparation paradigms have revealed that increased expectancy of a response signal shortens reaction times (RTs). Neurophysiological data suggest that in such paradigms, not only RT but also neuronal activity in the motor structures involved is modulated by expectancy of behaviorally relevant events. Here, we directly tested whether expectancy of a response signal modulates excitability of the corticospinal system used in the subsequent movement. We combined single- and paired-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex with a simple RT task with variable preparatory delays. We found that, in line with typical behavioral observations, the subjects' RTs decreased with increasing response signal expectancy. TMS results revealed a modulation of corticospinal excitability in correspondence with response signal expectancy. Besides an increased excitability over the time-course of the preparatory delay, corticospinal excitability transiently increased whenever a response signal was expected. Paired-pulse TMS showed that this modulation is unlikely to be mediated by excitability changes in interneuronal inhibitory or facilitatory networks in the primary motor cortex. Changes in corticospinal synchronization or other mechanisms involving spinal circuits are candidates mediating the modulation of corticospinal excitability by expectancy.
The Role of the Lateral Prefrontal Cortex and Anterior Cingulate in Stimulus-Response Association Reversals
Authors: Parris Benjamin A. , Thai Ngoc J. , Benattayallah Abdelmalek , Summers Ian R. , Hodgson Timothy L.
Published: January 2007

Many complex tasks require us to flexibly switch between behavioral rules, associations, and strategies. The prefrontal cerebral cortex is thought to be critical to the performance of such behaviors, although the relative contribution of different components of this structure and associated subcortical regions are not fully understood. We used functional magnetic resonance imaging to measure brain activity during a simple task which required repeated reversals of a rule linking a colored cue and a left/right motor response. Each trial comprised three discrete events separated by variable delay periods. A colored cue instructed which response was to be executed, followed by a go signal which told the subject to execute the response and a feedback instruction which indicated whether to “hold” or “flip” the rule linking the colored cue and response. The design allowed us to determine which brain regions were recruited by the specific demands of preparing a rule contingent motor response, executing such a response, evaluating the significance of the feedback, and reconfiguring stimulus-response (SR) associations. The results indicate that an increase in neural activity occurs within the anterior cingulate gyrus under conditions in which SR associations are labile. In contrast, lateral frontal regions are activated by unlikely/unexpected perceptual events regardless of their significance for behavior. A network of subcortical structures, including the mediodorsal nucleus of the thalamus and striatum were the only regions showing activity that was exclusively correlated with the neurocognitive demands of reversing SR associations. We conclude that lateral frontal regions act to evaluate the behavioral significance of perceptual events, whereas medial frontal-thalamic circuits are involved in monitoring and reconfiguring SR associations when necessary.
Too Many Trees to See the Forest: Performance, Event-related Potential, and Functional Magnetic Resonance Imaging Manifestations of Integrative Congenital Prosopagnosia
Authors: Bentin Shlomo , DeGutis Joseph M. , D'Esposito Mark , Robertson Lynn C.
Published: January 2007

Neuropsychological, event-related potential (ERP), and functional magnetic resonance imaging (fMRI) methods were combined to provide a comprehensive description of performance and neurobiological profiles for K.W., a case of congenital prosopagnosia. We demonstrate that K.W.'s visual perception is characterized by almost unprecedented inability to identify faces, a large bias toward local features, and an extreme deficit in global/configural processing that is not confined to faces. This pattern could be appropriately labeled congenital integrative prosopagnosia, and accounts for some, albeit not all, cases of face recognition impairments without identifiable brain lesions. Absence of face selectivity is evident in both biological markers of face processing, fMRI (the fusiform face area [FFA]), and ERPs (N170). Nevertheless, these two neural signatures probably manifest different perceptual mechanisms. Whereas the N170 is triggered by the occurrence of physiognomic stimuli in the visual field, the deficient face-selective fMRI activation in the caudal brain correlates with the severity of global processing deficits. This correlation suggests that the FFA might be associated with global/configural computation, a crucial part of face identification.
The Role of the Cerebellum in Subsecond Time Perception: Evidence from Repetitive Transcranial Magnetic Stimulation
Authors: Lee Kwang-Hyuk , Egleston Paul N. , Brown Wendy H. , Gregory Abigail N. , Barker Anthony T. , Woodruff Peter W. R.
Published: January 2007

In three experiments, we investigated the role of the cerebellum in sub- and suprasecond time perception by using repetitive transcranial magnetic stimulation (rTMS). In Experiment 1, subjects underwent four 8-min 1-Hz rTMS sessions in a within-subject design. rTMS sites were the medial cerebellum (real and sham rTMS), left lateral cerebellum, and right lateral cerebellum. Following each rTMS session, subjects completed a subsecond temporal bisection task (stimuli in the range 400–800 msec). Compared with sham rTMS, rTMS applied over the right lateral or medial cerebellum induced a leftward shift of the psychophysical function (perceived lengthening of time). In Experiment 2, a separate sample of subjects underwent the identical rTMS procedure and completed a suprasecond bisection task (stimuli in the 1000–2000 msec range). In this experiment, rTMS to the cerebellar sites did not produce any significant changes compared with sham rTMS. Experiment 3 employed a within-subject design to replicate findings from Experiments 1 and 2. Subjects underwent four rTMS conditions (sub- and suprabisection tasks following medial cerebellar and sham rTMS). rTMS induced a significant leftward shift of psychophysical function in the subsecond bisection, but not in the suprasecond bisection. In this study, we have demonstrated that transient cerebellar stimulation can differently affect the ability to estimate time intervals below and above a duration of 1 sec. The results of this study provide direct evidence for the role of the cerebellum in processing subsecond time intervals. This study further suggests that the perception of sub- and suprasecond intervals is likely to depend upon distinct neural systems.
Brain Response to Unexpected Novel Noises in Children with Low and High Trait Anxiety
Authors: Hogan Alexandra M. , Butterfield Elinor L. , Phillips Luke , Hadwin Julie A.
Published: January 2007

The behavioral inhibition system [Gray, J. A. The neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system. Oxford: Oxford University Press, 1982] proposes that anxiety is associated with the processing of novel stimuli. We aimed to explore this relationship by recording auditory event-related potentials associated with unexpected novel noises in typically developing children. Children aged 10–14 years with low (n = 12) and high (n = 11) self-report trait anxiety were assessed using a novelty oddball task. The N1 associated with novel stimuli, specifically the “N1c” component maximal at temporal lobe sites, was of significantly longer latency (p = .014) and greater amplitude (p = .004) in the high compared with the low anxious group. This group difference was supported by linear correlations between N1c amplitude and trait anxiety scores. There was no effect of anxiety on the later novelty P3. These data suggest a subtle moderating role of trait anxiety on brain response to novelty, and further research with clinically anxious children is indicated.
Genetic Variations of the NR3A Subunit of the NMDA Receptor Modulate Prefrontal Cerebral Activity in Humans
Authors: Gallinat Jürgen , Götz Thomas , Kalus Peter , Bajbouj Malek , Sander Thomas , Winterer Georg
Published: January 2007

Introduction: Recently, a novel N-methyl-D-aspartate (NMDA) receptor subunit, NR3A, has been discovered in the brain. This subunit decreases NMDA receptor activity by modulating the calcium permeability of the receptor channel and current density in cortical cells. Because the NR3A is expressed in the human prefrontal cortex, we hypothesized that genetic variations of the NR3A subunit modulate prefrontal activation. Methods: Electromagnetic activity during selective attention (auditory oddball task with target processing) was measured in 281 healthy subjects. Genotyping of a missense variation (rs10989591, Val362Met) of the NR3A gene was performed. Results: Individuals carrying Val/Val genotype showed significantly reduced frontal P300 amplitudes compared with Met/Met subjects. Subsequent low-resolution electromagnetic source analysis revealed that this group difference is likely caused by reduced activation in the inferior frontal gyrus. Conclusions: It was shown for the first time that the genetic constitution of the subunit composition of NMDA receptor regulation might be relevant for prefrontal information processing in humans. The results underline the pivotal role of glutamate in frontal lobe function and indicate that the NR3A subunit could be a plausible candidate gene for diseases with prefrontal dysfunctions.
Water Vapor Transport and the Production of Precipitation in the Eastern Fertile Crescent
Authors: Evans J. P. , Smith R. B.
Published: January 2007

The study presented here attempts to quantify the significance of southerly water vapor fluxes on precipitation occurring in the eastern Fertile Crescent region. The water vapor fluxes were investigated at high temporal and spatial resolution by using a Regional Climate Model [fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5)–Noah land surface model] to downscale the NCEP–NCAR reanalysis. Using the Iterative Self-Organizing Data Analysis Techniques (ISODATA) clustering algorithm, the 200 largest precipitation events, occurring from 1990 through 1994, were grouped into classes based on the similarity of their water vapor fluxes. Results indicate that, while southerly fluxes were dominant in 24% of tested events, these events produced 43% of the total precipitation produced by the 200 largest events. Thus, while the majority of precipitation events occurring in the Fertile Crescent involve significant water vapor advected from the west, those events that included southerly fluxes produced much larger precipitation totals. This suggests that changes that affect these southerly fluxes more than the westerly fluxes (e.g., changes in the Indian monsoon, movement of the head of the Persian Gulf, etc.) may have a relatively strong affect on the total precipitation falling in the Fertile Crescent even though they affect relatively few precipitation events. To obtain a clearer view of the precipitation mechanisms, the authors used a linear model, along with the estimated water vapor fluxes, to downscale from 25 to 1 km. The result shows a spectrum of mountain scales not seen in the regional model, exerting tight control on the precipitation pattern.
Experimental and Numerical Studies on Longitudinal Smoke Temperature Distribution Upstream and Downstream from the Fire in a Road Tunnel
Authors: Hu L. H. , Huo R. , Wang H. B. , Yang R. X.
Published: January 2007

Four full-scale tests are conducted in a real road tunnel, with ceiling jet temperature distributions measured 200 m upstream and downstream from the fire. Two sizes of pool fires, 1.8 and 3.2 MW, with two different fire surface heights, 0.2 and 1.7 m from the floor level, are considered. Longitudinal ventilation velocities are also varied. The experimental data obtained in these four tunnel fire tests are used for validation of FDS 4.0 parallel simulation on tunnel fires. The ceiling jet temperature distributions upstream and downstream, and thus the back-layering length are compared. Results show that the temperatures predicted by FDS 4.0 are near to the measured data. In near fire regions, for instance, not more than 40–80 m away from the fire, the temperature predicted is very close to the full-scale data. There is a deviation between the predicted value and the measured one, shown to be mainly less than 4–5 C, at positions further away. The back-layering length predicted by FDS 4.0 also seems to agree fairly well with that deduced from the full-scale experiments.
A Comparative Study on the Synergistic Effect of Expandable Graphite with APP and IFR in Polyethylene
Authors: Han Zhidong , Dong Limin , Li Ying , Zhao Hong
Published: January 2007

In this study, synergistic effects of expandable graphite (EG) and ammonium polyphosphate (APP) or intumescent flame retardant (IFR) on flame retardant polyethylene (PE) have been comparatively investigated by means of limiting oxygen index (LOI), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). The results of LOI reveal better synergistic effects of EG with IFR than that with APP. According to TGA and SEM results, EG/APP can retard the degradation to some extent, while EG/IFR can promote the formation of a more compact char layer, consequently leading to much lower weight loss rate and better flame retardant synergistic effect of EG with IFR. EDS gives positive evidences of the interaction of EG/APP or EG/IFR by showing the char that is rich in elements P and S.
Commingled Hybrid Yarn Diameter Ratio in Continuous Fiber-reinforced Thermoplastic Composites
Authors: Golzar M. , Brünig H. , Mäder E.
Published: January 2007

Manufacturing of lightweight structures from fiber-reinforced thermoplastic composites is of great benefit. Among various manufacturing methods the usage of semi-finished products is in high demand. To improve the mechanical properties and increase the productivity, the commingled hybrid yarn was developed recently. Among many parameters the fiber volume fraction and was diameters of reinforcement filaments and thermoplastic filaments in hybrid yarn are investigated in this study. The target is to improve the impregnation of reinforcement by molten thermoplastic polymer. Two hybrid yarn samples are illustrated (a) high performance thermoplastic PEEK/CF and (b) standard thermoplastic/glass fibers polypropylene (PP)/GF. The unidirectional (UD) composite samples, manufactured using thinner filaments, show little improvement of mechanical properties within the investigated region. In this study, a new technological approach will be introduced to increase the homogeneity of PP/GF commingled yarns by online hybrid spinning.
Magnetoactive Polymer Composite Fibers and Fabrics -Processing and Mechanical Characterization
Authors: Farshad Mehdi , Clemens Frank , Le Roux Magali
Published: January 2007

A new polymer composite material and textile product has been developed. The main constituents of this composite are thermoplastic polymer and embedded carbonyl iron powder. Through an extrusion process, endless flexible fibers having diameters of 200 and 500 mm have been produced. The fibers show a very high degree of bending flexibility to the extent of knotting. Endless fibers with a 20-60% volume fraction of carbonyl iron could easily be produced. In this study, only fibers with a diameter of 500 μm are investigated. Tensile strengths ranging from 8 to 20 MPa, and strains ranging from 6 to 20% have been recorded. In a further development, fibers have been woven into flexible plain weave woven fabrics. The magnetoactive fibers and fabrics offer many advantages over the steel fibers and fabrics. These include no conductivity, light weight, corrosion resistance and high degree of flexibility. Applications of this new material include covers for magnetic shielding, sensors, actuators, functional clothing, drapes, wall papers, sieves, covers, and other rigid or flexible objects.
Family Caregiving to Those With Dementia in Rural Alabama
Authors: Kosberg Jordan I. , Kaufman Allan V. , Burgio Louis D. , Leeper James D. , Sun Fei
Published: January 2007

This study explored differences and similarities in the experiences of African American and White family caregivers of dementia patients living in rural Alabama. This cross-sectional survey used a caregiving stress model to investigate the interrelationships between caregiving burden, mediators, and outcomes. Random-digit-dialing telephone interviews were used to obtain data on a probability sample of 74 non-Hispanic White and 67 African American caregivers. White caregivers were more likely to be married and older, used acceptance and humor as coping styles, and had fewer financial problems. African American caregivers gave more hours of care, used religion and denial as coping styles, and were less burdened. The authors have developed a methodology for obtaining a representative sample of African American and White rural caregivers. Further investigations are needed of the interactions between urban/rural location and ethnic/racial backgrounds of dementia caregivers for heuristic and applied reasons.
Quality of LifeDemands Comprehension and Further Exploration
Authors: Bergland Astrid , Narum Ingrid
Published: January 2007

The intention of this study was to elucidate what the concept “quality of life” means to elderly women. A qualitative approach based on 282 women (age 75-93 years) showed that the participants were able to articulate what quality of life meant to them. Thinking about what makes for a good quality of life, 82.3% mentioned the importance of good social functioning, 68.8% mentioned good health, 22.3% mentioned good economic circumstances, and 14.9% mentioned the importance of living in their own flat or house. Six categories were identified based on the women’s descriptions: holism, relationships, activity and participation, pragmatic approach to health, belonging and social environment, and personal values. The lay perspective on quality of life is characterized by three qualities: preservation of continuity—sameness within change, power-empowerment, and the quest for meaning.
Rural Family Caregivers and Health Behaviors
Authors: Castro Cynthia M. , King Abby C. , Housemann Robyn , Bacak Stephen J. , McMullen Kathleen M. , Brownson Ross C.
Published: January 2007

This study examined health behaviors in a sample of rural family caregivers. In a community telephone survey of rural Missouri, Arkansas, and Tennessee, respondents were asked about their health, physical activity, nutrition, health providers, and family caregiving. Among 1,234 survey respondents, 12% self-identified as family caregivers. Caregivers reported lower fruit intake, more walking for exercise, and more provider advice about stress, fruits, and vegetables than noncaregivers. Groups did not differ in smoking, dietary fat, obesity, or self-rated health. Women caregivers reported more favorable patterns of physical activity, smoking, and provider interactions than men caregivers, and White caregivers had healthier reports of physical activity and body mass index than Black caregivers. These results provide new information about rural caregivers’ health habits. Apart from nutritional intake, caregivers were not significantly different in most health behaviors. However, health providers seemed more attentive to caregivers regarding nutrition and stress.
Examining the Association Between Lung Functioning and Cognitive Performance in African American Adults
Authors: Allaire Jason C. , Tamez Elaine , Whitfield Keith E.
Published: January 2007

The current study examined the extent to which pulmonary functioning, as measured by average peak expiratory flow, was related to performance on seven cognitive measures. Analyses were conducted on a sample of 396 African American adults ranging in age from 22 to 89 years. Results revealed significant differences in mean levels of expiratory flow between the younger and older African Americans, with older adults performing more poorly. Lung functioning was not uniquely associated with cognitive performance in the younger adults, though it emerged as a significant predictor of individual differences in performance on the Telephone Interview of Cognitive Status even after controlling for age, education, and smoking history. Biobehavioral assessments such as the one presented here appear to provide important new insights into the sources of individual differences in cognition observed in this understudied population.
Predicting the Changes in Depressive Symptomatology in Later Life
Authors: Choi Namkee G. , Bohman Thomas M.
Published: January 2007

This study examined the unique effects of four variable groups on changes in older adults’ depressive symptoms for a 2-year period: (1) baseline health and disability status, (2) changes in health and disability since baseline, (3) stability and changes in marital and caregiving status and in work and volunteering, and (4) stability and changes in health-related behaviors. With data from the 1998 and 2000 interview waves of the Health and Retirement Study, the authors used gender-separate multistep (hierarchical) residualized regression analyses in which the Center for Epidemiological Studies Depression scale (CES-D) score at follow-up is modeled as a function of the effect of each group of independent variables. As hypothesized, changes in health, disability, marital, and caregiving status explained a larger amount of variance than the existing and stable conditions, although each group of variables explained a relatively small amount (0.3-3.4%) of variance in the follow-up CES-D score.
Optimization of Parameters in Hydroentanglement Process
Authors: Rawal Amit , Moyo Doice , Soukupova Vera , Anandjiwala Rajesh
Published: January 2007

Hydroentanglement is a versatile and relatively little explored method of bonding the fibrous web using high-pressure water jets. These nonwoven structures have an extensive range of applications–for example, wipes, carpet backing, filters, sanitary, medical dressings, and composites. Such applications require certain functional characteristics in hydroentangled structures, besides basic properties, which are required to be engineered by judicious optimization of the hydroentanglement process. In this study, a number of hydroentangled structures have been produced based on Taguchi's experimental design technique by varying the process parameters: namely, feed rate and water jet pressures. The simultaneous effect of more than one parameter has been investigated on the dimensional and mechanical properties of hydroentangled fabrics. These process parameters are then empirically related with the fabric properties using the multiple regression technique. The influence of jet pressure was found to be significant on the fiber orientation characteristics of the hydroentangled fabrics.
Prediction of Yarn Paths in Braided Structures Formed on a Square Pyramid
Authors: Rawal Amit , Potluri Prasad , Steele Colin
Published: January 2007

A circular braiding process is used for producing three-dimensional (3D) textile preforms using 3D mandrels. In our previous study, we have predicted and simulated the yarns paths on various 3D mandrels, including cylinder, square prism, and cones with circular and elliptical cross-sections (Rawal, A., Potluri, P. and Steele, C. (2005). Geometrical Modeling of the Yarn Paths in Three-Dimensional Branded Structure, Journal of Industrial Textiles, 34(2): 115–135.). This study predicts the yarn paths on a square pyramid in which the yarns are modeled as straight lines varying in length from the top to the bottom of the square pyramid. The 3D coordinates of the yarn paths on a square pyramid have been mathematically related to the braid angle.
An Application of Six Sigma Methodology to Reduce lot-to-lot Shade Variation of Linen Fabrics
Authors: Das Prasun , Roy Shirshendu , Antony Jiju
Published: January 2007

There was a problem of shade variation of dyed fabrics in a reputed textile company leading to the increase in process cycle time due to the extra amount of color addition or stripping. The extent of reprocessing fabrics was estimated to be around 75%. The objective of this work was to reduce the shade matching time in the fabric dyeing process by optimizing the effect of the controllable parameters. The problem was tackled using the DMAIC cycle of disciplined Six Sigma methodology. Initially, the process baseline sigma level was found as 0.81 and a target sigma level was set at 1.76. The outcome of the analyses observed at every phase was explained based on textile technology. Actions taken on the critical activities led to the reduction in average excess time as 0.0125 h/m. The yield of the overall process has improved to 82% with an improved sigma level of 2.34. The estimated annual saving is to the tune of Rupees eighteen lakhs (over $40,000). The proposed control schemes from this study are already in place.
Enhanced T-cell reconstitution by hematopoietic progenitors expanded ex vivo using the Notch ligand Delta1
Authors: Dallas Mari H. , Varnum-Finney Barbara , Martin Paul J. , Bernstein Irwin D.
Published: January 2007

A physiologic role for Notch signaling in hematopoiesis has been clearly defined in lymphoid differentiation, with evidence suggesting a critical role in T-cell versus B-cell fate decisions. Previously, we demonstrated that activation of endogenous Notch receptors by culture of murine lin−Sca-1+c-kit+ (LSK) hematopoietic progenitors with exogenously presented Notch ligand, Delta1ext-IgG, consisting of the extracellular domain of Delta1 fused to the Fc domain of human IgG1, promoted early T-cell differentiation and increased the number of progenitors capable of short-term lymphoid and myeloid reconstitution. Here we show that culture of LSK precursors with Delta1ext-IgG increases the number of progenitors that are able to rapidly repopulate the thymus and accelerate early T-cell reconstitution with a diversified T-cell receptor repertoire. Most of the early T-cell reconstitution originated from cells that expressed lymphoid-associated antigens: B220, Thy1, CD25, and/or IL7Rα, whereas the most efficient thymic repopulation on a per cell basis originated from the smaller number of cultured cells that did not express lymphoid-associated antigens. These findings demonstrate the potential of Delta1ext-IgG-cultured cells for accelerating early immune reconstitution after hematopoietic cell transplantation.