bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Body-Thickness Dependence of the Linearly Extrapolated Threshold Voltage of a Double-Gate Metal–Oxide–Semiconductor Field-Effect Device
Authors: Wong Man , Shi Xuejie , Chow Thomas
Published: December 2006

An approximate but simple expression explicitly relating the surface potential to the surface electric field of a symmetrical double-gate metal–oxide–semiconductor field-effect device is used to derive a compact expression for the linearly extrapolated threshold voltage V
Te of such a device with a uniformly doped channel region. The expression is shown to be valid for both partially and fully depleted devices. V
Te is predicted to exhibit a global minimum as the thickness of the channel is systematically increased.
Thermal and Electrical Properties of 5-nm-Thick TaN Film Prepared by Atomic Layer Deposition Using a Pentakis(ethylmethylamino)tantalum Precursor for Copper Metallization
Authors: Bae Nam-Jin , Na Kyoung-Il , Cho Hyun-Ick , Park Ki-Yeol , Boo Sung-Eun , Bae Jeung-Ho , Lee Jung-Hee
Published: December 2006

We first report on the thermal stability and electrical properties of 5 nm-thick TaN films prepared by atomic layer deposition (ALD) using pentakis(ethylmethylamino)tantalum (PEMAT) and ammonia. The deposition rate of the ALD-TaN process was about ∼0.067 nm per cycle in a temperature range between 200 and 250 °C, which is a typical feature of ALD process. In cross sectional transmission electron microscopy (TEM) images, the deposited TaN films exhibited a very smooth and uniform interface. The thermal stabilities of these films were tested by depositing a Cu film of 200 nm thickness on a TaN layer and subsequently performing annealing for 30 min by varying the temperature from 300 to 800 °C in N2 ambient. The high and low-frequency capacitance–voltage (C–V) and breakdown characteristics of a Cu/TaN/SiO2/Si capacitor showed that the barrier properties of thin TaN films against Cu diffusion are inhibited above 500 °C, which is considerably lower than the inhibition temperature estimated by four-point probe or X-ray diffraction (XRD) measurement.
Synthesis and Characteristics of Fe Nanowires
Authors: Shi Jen Bin , Chen Yu Jheng , Lin Ya Ting , Wu Chien , Chen Chih Jung , Lin Jer Yan
Published: December 2006

Arrays of 60-nm-diameter pores are synthesized by the electrochemical anodization of an aluminum substrate. Fe is electrodeposited in the pores to obtain the nanowire arrays. X-ray diffraction patterns and energy dispersive X-ray spectroscopy (EDS) show that the deposited material is pure iron. The Fe nanowire arrays possess a body-centered-cubic structure, and the wire direction of the nanowire arrays is orientated along the [110] direction. In the present study, we report the preferred [110] orientation along Fe nanowires with a diameter of 60 nm with values of parallel and perpendicular remanent magnetization of 0.4 and 4 memu, respectively.
Energy Spectrum of Two-Dimensional Electron Gas to be Used in Quantum Cross Structures
Authors: Kondo Kenji , Ishibashi Akira
Published: December 2006

A quantum cross system consisting of the edge-to-edge configuration of two-dimensional (2D) conductors is expected to serve as an ideal platform for molecular electronic devices. As the first step, we have calculated the electron energy spectrum of 2D electron gas at a GaAs/AlGaAs heterointerface as a candidate for the 2D conductor in the quantum cross, taking into consideration the electron correlation for the 2D electron system. As a result, we have confirmed that a plasmaron can exist stably. This means that we will observe the broadening of the conductance peak due to the scattering induced by plasmons when we measure the current–voltage characteristics of the quantum cross device.
Effective Surface Area of SnO2-Sputtered Films Evaluated by Measurement of Physical Adsorption Isotherms
Authors: Yamazaki Toshinari , Furuta Tomoyasu , Shen Yanbai , Jin Chengji , Kikuta Toshio , Nakatani Noriyuki
Published: December 2006

The microstructure of SnO2 sputtered films was investigated by field emission electron microscopy (FE-SEM), and by the measurement of film density and physical adsorption isotherms. FE-SEM shows that the SnO2-sputtered films are composed of columnar grains with thicknesses of about 10–45 nm. The density of the film deposited at a high temperature of 573 K and a low pressure of 0.4 Pa was 6.38×103 kg/m3. On the other hand, the density of the film deposited at room temperature and a high pressure of 12 Pa was 3.82×103 kg/m3. This value is much lower than the bulk density 6.95×103 kg/m3, indicating that the film is very porous. According to the results of the physical adsorption isotherms for Kr gas, the effective surface area of this porous film was 91.0 times larger than the apparent surface area, indicating that the columnar grains are mostly isolated by gaps. Furthermore, the density is discussed in relation to the total pore volume determined from pore size distributions.
Design and Fabrication of Pure Green Color Microcavity Organic Light Emitting Device
Authors: Ma F. , Liu X. , Zhang C. , Li H. , Wang L.
Published: December 2006

A pure green microcavity organic light emitting device (MOLED) was designed and fabricated with an emission peak of 552 nm and the full width at half maximum (FWHM) of 24 nm. The maximum luminous efficiency and luminance are 8.4 cd/A at 13 V and 35000 cd/m2 at 21 V for the MOLED, and 3.2 cd/A at 18 V and 27000 cd/m2 at 25 V for the normal noncavity OLED. The luminous efficiency, voltage and current density are 6.3 cd/A, 7 V and 1.6 mA/cm2 for the MOLED, and 2.4 cd/A, 12 V and 4.2 mA/cm2 for the noncavity OLED at the luminance of 100 cd/m2. The CIE 1931 chromaticity coordinates of the MOLED at the normal direction is (0.35,0.62), which shows purer green emission comparing with that of the noncavity OLED (0.36,0.46).
Improvement in Performance of Stack as Heat Pump of Thermoacoustic Cooling System: Effect of Thickness of Heat Boundary Layer upon Cooling Effect
Authors: Sakamoto Shin-ichi , Watanabe Yoshiaki
Published: December 2006

The effect that stack channel radius and the thickness of the heat boundary layer in a stack of the heat pump have upon the cooling effect of a thermoacoustic cooling system is discussed. For the stack of the heat pump, two stacks with different channel radii are combined. It is found that the cooling effect becomes larger as the stack channel radius approaches the thickness of the heat boundary layer.
Superconductor-Based Quantum-Dot Light-Emitting Diodes: Role of Cooper Pairs in Generating Entangled Photon Pairs
Authors: Suemune Ikuo , Akazaki Tatsushi , Tanaka Kazunori , Jo Masafumi , Uesugi Katsuhiro , Endo Michiaki , Kumano Hidekazu , Hanamura Eiichi , Takayanagi Hideaki , Yamanishi Masamichi , Kan Hirofumi
Published: December 2006

The realization of solid-state photon sources that are capable of on-demand generation of an entangled single-photon pair at a time is highly desired for quantum information processing and communication. A new method of generating an entangled single-photon pair at a time is proposed employing Cooper-pair-related radiative recombination in a quantum dot (QD). Cooper pairs are bosons and the control of their number states is difficult. Pauli's exclusion principle on quasiparticles in a discrete state of a QD regulates the number state of the generated photon pairs in this scheme. The fundamental heterostructures for constructing superconductor-based quantum-dot light-emitting diodes (SQ-LEDs) and the fundamental operation conditions of SQ-LED will be discussed. The experimental studies on Cooper-pair injection into the related semiconductor structures will be also discussed.
Dialectical Behavior Therapy for Borderline Personality Disorder
Authors: Lynch Thomas R. , Trost William T. , Salsman Nicholas , Linehan Marsha M.
Published: December 2006

Since the introduction of Linehan's treatment manuals in 1993, dialectical behavior therapy (DBT) has been widely disseminated throughout multiple therapeutic settings and applied to a variety of diagnoses. The enthusiasm with which it was embraced by clinicians early on led some to question whether DBT's popularity was outstripping its empirical foundation. Most of the specific concerns raised regarding DBT's early empirical base have been meaningfully addressed in subsequent randomized controlled trials. This review provides a brief introduction to DBT, followed by a critical appraisal of empirical support for the treatment and a discussion of current research trends.
PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle
Authors: Poole Daniel P. , Furness John B.
Published: December 2006

PKC is involved in mediating the tonic component of gastrointestinal smooth muscle contraction in response to stimulation by agonists for G protein-coupled receptors. Here, we present pharmacological and immunohistochemical evidence indicating that a member of the novel PKC isoforms, PKC-δ, is involved in maintaining muscarinic receptor-coupled tonic contractions of the guinea pig ileum. The tonic component of carbachol-evoked contractions was enhanced by an activator of conventional and novel PKCs, phorbol 12,13-dibutyrate (PDBu; 200 nM or 1 μM), and by an activator of novel PKCs, ingenol 3,20-dibenzoate (IDB; 100 or 500 nM). Enhancement was unaffected by concentrations of bisindolylmaleimide I (BIM-I; 22 nM) that block conventional PKCs or by a PKC-ε-specific inhibitor peptide but was attenuated by higher doses of BIM-I (2.2 μM). Relevant proteins were localized at a cellular and subcellular level using confocal analysis. Immunohistochemical staining of the ileum showed that PKC-δ was exclusively expressed in smooth muscles distributed throughout the layers of the gut wall. PKC-ε immunoreactivity was prominent in enteric neurons but was largely absent from smooth muscle of the muscularis externa. Treatment with PDBu, IDB, or carbachol resulted in a time- and concentration-dependent translocation of PKC-δ from the cytoplasm to filamentous structures within smooth muscle cells. These were parallel to, but distinct from, actin filaments. The translocation of PKC-δ in response to carbachol was significantly reduced by scopolamine or calphostin C. The present study indicates that the tonic carbachol-induced contraction of the guinea pig ileum is mediated through a novel PKC, probably PKC-δ.
Supramaximal CCK-58 does not induce pancreatitis in the rat: role of pancreatic water secretion
Authors: Yamamoto Mitsuyoshi , Reeve Joseph R. , Green Gary M.
Published: December 2006

In contrast to supramaximal CCK-8 or caerulein, acute or prolonged supraphysiological levels of endogenous CCK-58 do not cause pancreatitis. Compared with CCK-8, CCK-58 is a much stronger stimulant of pancreatic chloride and water secretion, equivalent to maximally effective secretin, but with a chloride-to-bicarbonate ratio characteristic of acinar fluid. Because supraphysiological endogenous CCK does not cause pancreatitis and because coadministration of secretin ameliorated caerulein- or CCK-8-induced pancreatitis, coincident with restoring pancreatic water secretion, we hypothesized that supramaximal CCK-58 would not induce pancreatitis. Conscious rats were infused intravenously with 2 or 4 nmol·kg−1·h−1of CCK-8 or synthetic rat CCK-58 for 6 h, and pancreases were examined for morphological and biochemical indexes of acute pancreatitis. A second group was treated as above while monitoring pancreatic protein and water secretion. CCK-8 at 2 nmol·kg−1·h−1caused severe edematous pancreatitis as evidenced by morphological and biochemical criteria. CCK-58 at this dose had minimal or no effect on these indexes. CCK-58 at 4 nmol·kg−1·h−1increased some indexes of pancreatic damage but less than either the 2 or 4 nmol·kg−1·h−1dose of CCK-8. Pancreatic water and protein secretion were nearly or completely abolished within 3 h of onset of CCK-8 infusion, whereas water and protein secretion were maintained near basal levels in CCK-58-treated rats. We hypothesize that supramaximal CCK-58 does not induce pancreatitis because it maintains pancreatic acinar chloride and water secretion, which are essential for exocytosis of activated zymogens. We conclude that CCK-58 may be a valuable tool for investigating events that trigger pancreatitis.
Development of colonic motility in the neonatal mouse-studies using spatiotemporal maps
Authors: Roberts Rachael R. , Murphy Jessica F. , Young Heather M. , Bornstein Joel C.
Published: December 2006

Colonic migrating motor complexes (CMMCs) are spontaneous, anally propagating constrictions, repeating every 3–5 min in mouse colon in vitro. They are regulated by the enteric nervous system and may be equivalent to mass movement contractions. We examined postnatal development of CMMCs and circular muscle innervation to gain insight into mechanisms regulating transit in the maturing colon. Video recordings of mouse colon in vitro were used to construct spatiotemporal maps of spontaneous contractile patterns. Development of nitric oxide synthase (NOS) and cholinergic nerve terminals in the circular muscle was examined immunohistochemically. In adults, CMMCs appeared regularly at 4.6 ± 0.9-min intervals ( n = 5). These intervals were reduced by inhibition of NOS (2.7 ± 0.2 min; n = 5; P < 0.05). CMMCs were abolished by tetrodotoxin ( n = 4). CMMCs at postnatal day (P)10 were indistinguishable from adult. At birth and P4, CMMCs were absent. Instead, small constrictions that propagated both orally and anally, “ripples,” were seen. Ripples were unaffected by tetrodotoxin or inhibition of NOS and were present in Ret−/−mice (which lack enteric neurons) at embryonic day 18.5. In P6 mice, only ripples were seen in control, but NOS inhibition induced CMMCs ( n = 8). NOS terminals were abundant in the circular muscle at birth; cholinergic terminals were sparse but were common by P10. In mouse, myogenic ripples are the only mechanism available to produce colonic transit at birth. At P6, neural circuits that generate CMMCs are present but are inhibited by tonic activity of nitric oxide. Adult patterns appear by P10.
Dynamics of endogenous ATP7A (Menkes protein) in intestinal epithelial cells: copper-dependent redistribution between two intracellular sites
Authors: Nyasae L. , Bustos R. , Braiterman L. , Eipper B. , Hubbard A.
Published: December 2006

We report for the first time on the copper-dependent behavior of endogenous ATP7A in two types of polarized intestinal epithelia, rat enterocytes in vivo and filter-grown Caco-2 cells, an accepted in vitro model of human small intestine. We used high-resolution, confocal immunofluorescence combined with quantitative cell surface biotinylation and found that the vast majority of endogenous ATP7A was localized intracellularly under all copper conditions. In copper-depleted cells, virtually all of the ATP7A localized to a post-TGN compartment, with <3% of the total protein detectable at the basolateral cell surface. When copper levels were elevated, ATP7A dispersed to the cell periphery in punctae whose pattern did not overlap with the steady-state distributions of post-Golgi, endosomal, or basolateral membrane markers; only ∼8–10% of the recovered ATP7A was detected at the basolateral cell surface. These results raise several questions regarding prevailing models of ATP7A dynamics and the mechanism of copper efflux.
Regulation of Triglyceride Metabolism II. Function of mitochondrial GPAT1 in the regulation of triacylglycerol biosynthesis and insulin action
Authors: Gonzalez-Baró Maria R. , Lewin Tal M. , Coleman Rosalind A.
Published: December 2006

GPAT1, one of four known glycerol-3-phosphate acyltransferase isoforms, is located on the mitochondrial outer membrane, allowing reciprocal regulation with carnitine palmitoyltransferase-1. GPAT1 is upregulated transcriptionally by insulin and SREBP-1c and downregulated acutely by AMP-activated protein kinase, consistent with a role in triacylglycerol synthesis. Knockout and overexpression studies suggest that GPAT1 is critical for the development of hepatic steatosis and that steatosis initiated by overexpression of GPAT1 causes hepatic, and perhaps also peripheral, insulin resistance. Future questions include the function of GPAT1 in relation to the other GPAT isoforms and whether the lipid intermediates synthesized by GPAT and downstream enzymes in the pathway of glycerolipid biosynthesis participate in intracellular signaling pathways.
Phosphatidylinositol 3-kinase facilitates bile acid-induced Ca2+responses in pancreatic acinar cells
Authors: Fischer L. , Gukovskaya A. S. , Penninger J. M. , Mareninova O. A. , Friess H. , Gukovsky I. , Pandol S. J.
Published: December 2006

Bile acids are known to induce Ca2+signals in pancreatic acinar cells. We have recently shown that phosphatidylinositol 3-kinase (PI3K) regulates changes in free cytosolic Ca2+concentration ([Ca2+]i) elicited by CCK by inhibiting sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA). The present study sought to determine whether PI3K regulates bile acid-induced [Ca2+]iresponses. In pancreatic acinar cells, pharmacological inhibition of PI3K with LY-294002 or wortmannin inhibited [Ca2+]iresponses to taurolithocholic acid 3-sulfate (TLC-S) and taurochenodeoxycholate (TCDC). Furthermore, genetic deletion of the PI3K γ-isoform also decreased [Ca2+]iresponses to bile acids. Depletion of CCK-sensitive intracellular Ca2+pools or application of caffeine inhibited bile acid-induced [Ca2+]isignals, indicating that bile acids release Ca2+from agonist-sensitive endoplasmic reticulum (ER) stores via an inositol ( 1 , 4 , 5 )-trisphosphate-dependent mechanism. PI3K inhibitors increased the amount of Ca2+in intracellular stores during the exposure of acinar cells to bile acids, suggesting that PI3K negatively regulates SERCA-dependent Ca2+reloading into the ER. Bile acids inhibited Ca2+reloading into ER in permeabilized acinar cells. This effect was augmented by phosphatidylinositol ( 3 , 4 , 5 )-trisphosphate (PIP3), suggesting that both bile acids and PI3K act synergistically to inhibit SERCA. Furthermore, inhibition of PI3K by LY-294002 completely inhibited trypsinogen activation caused by the bile acid TLC-S. Our results indicate that PI3K and its product, PIP3, facilitate bile acid-induced [Ca2+]iresponses in pancreatic acinar cells through inhibition of SERCA-dependent Ca2+reloading into the ER and that bile acid-induced trypsinogen activation is mediated by PI3K. The findings have important implications for the mechanism of acute pancreatitis since [Ca2+]iincreases and trypsinogen activation mediate key pathological processes in this disorder.
Male sex hormones promote vagally mediated reflex airway responsiveness to cholinergic stimulation
Authors: Card Jeffrey W. , Voltz James W. , Ferguson Catherine D. , Carey Michelle A. , DeGraff Laura M. , Peddada Shyamal D. , Morgan Daniel L. , Zeldin Darryl C.
Published: December 2006

A sex disparity in airway responsiveness to cholinergic stimulation has been observed in laboratory mice in that males are considerably more responsive than females, but the basis for this difference is unclear. In this report, we demonstrate that male sex hormones promote murine airway responsiveness to cholinergic stimulation via vagus nerve-mediated reflex mechanisms. In tissue bath preparations, no sex-based differences were observed in the contractile responses of isolated tracheal and bronchial ring segments to carbachol, indicating that the mechanism(s) responsible for the in vivo sex difference is (are) absent ex vivo. Bilateral cervical vagotomy was found to abolish in vivo airway responsiveness to methacholine in male mice, whereas it did not alter the responses of females, suggesting a regulatory role for male sex hormones in promoting reflex airway constriction. To test this possibility, we next studied mice with altered circulating male sex hormone levels. Castrated male mice displayed airway responsiveness equivalent to that observed in intact females, whereas administration of exogenous testosterone to castrated males restored responsiveness, albeit not to the level observed in intact males. Administration of exogenous testosterone to intact female mice similarly enhanced responsiveness. Importantly, the promotive effects of exogenous testosterone in castrated male and intact female mice were absent when bilateral vagotomy was performed. Together, these data indicate that male sex hormones promote cholinergic airway responsiveness via a vagally mediated reflex mechanism that may be important in the regulation of airway tone in the normal and diseased lung.
A mathematical model of twin-twin transfusion syndrome with pulsatile arterial circulations
Authors: van den Wijngaard Jeroen P. H. M. , Westerhof Berend E. , Ross Michael G. , van Gemert Martin J. C.
Published: December 2006

The twin-twin transfusion syndrome (TTTS) is a severe complication of monochorionic twin pregnancies caused by a net transfusion of blood from one twin (the donor) to the other (the recipient) through placental anastomoses. To examine the pathophysiology of TTTS evolving through clinical stages I to IV, we extended our mathematical model to include pulsating circulations propagating along the arterial tree as well as placental and cerebral vascular resistances, and arterial wall thickness and stiffness. The model demonstrates that abnormal umbilical arterial flow (TTTS stage III) in the donor twin results from increased placental resistance as well as reduced resistance in the cerebral arteries. In contrast, recipient twin abnormal umbilical arterial flow requires a significantly greater increase in placental resistance, resulting from the compressive effects of high amniotic fluid pressure. Thus simulated abnormalities of donor umbilical arterial pulsations occur in the donor more commonly and earlier than in the recipient. The “normal” staging sequence (I, II, III, IV) correlates with the presence of compensating placental anastomoses, constituting the majority of monochorionic twin placentas. However, TTTS stage III may occur before manifestations of stage II (lack of donor bladder filling), in our model correlating with severe TTTS from a single arteriovenous anastomosis, an infrequent occurring placental angioarchitecture. In conclusion, this mathematical model describes the onset and development of the four stages of TTTS, reproduces a variety of clinical manifestations, and may contribute to identifying the underlying pathophysiology of the staging sequence in TTTS.
Liver glyconeogenesis: a pathway to cope with postprandial amino acid excess in high-protein fed rats?
Authors: Azzout-Marniche Dalila , Gaudichon Claire , Blouet Clémence , Bos Cécile , Mathé Véronique , Huneau Jean-François , Tomé Daniel
Published: December 2006

This paper provides molecular evidence for a liver glyconeogenic pathway, that is, a concomitant activation of hepatic gluconeogenesis and glycogenesis, which could participate in the mechanisms that cope with amino acid excess in high-protein (HP) fed rats. This evidence is based on the concomitant upregulation of phosphoenolpyruvate carboxykinase (PEPCK) gene expression, downregulation of glucose 6-phosphatase catalytic subunit (G6PC1) gene expression, an absence of glucose release from isolated hepatocytes and restored hepatic glycogen stores in the fed state in HP fed rats. These effects are mainly due to the ability of high physiological concentrations of portal blood amino acids to counteract glucagon-induced liver G6PC1 but not PEPCK gene expression. These results agree with the idea that the metabolic pathway involved in glycogen synthesis is dependent upon the pattern of nutrient availability. This nonoxidative glyconeogenic disposal pathway of gluconeogenic substrates copes with amino excess and participates in adjusting both amino acid and glucose homeostasis. In addition, the pattern of PEPCK and G6PC1 gene expression provides evidence that neither the kidney nor the small intestine participated in gluconeogenic glucose production under our experimental conditions. Moreover, the main glucose-6-phosphatase (G6Pase) isoform expressed in the small intestine is the ubiquitous isoform of G6Pase (G6PC3) rather than the G6PC1 isoform expressed in gluconeogenic organs.
Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow
Authors: Lee T.-K. , Lois J. H. , Troupe J. H. , Wilson T. D. , Yates B. J.
Published: December 2006

Despite considerable interest in the neural mechanisms that regulate muscle blood flow, the descending pathways that control sympathetic outflow to skeletal muscles are not adequately understood. The present study mapped these pathways through the transneuronal transport of two recombinant strains of pseudorabies virus (PRV) injected into the gastrocnemius muscles in the left and right hindlimbs of rats: PRV-152 and PRV-BaBlu. To prevent PRV from being transmitted to the brain stem via motor circuitry, a spinal transection was performed just below the L2 level. Infected neurons were observed bilaterally in all of the areas of the brain that have previously been shown to contribute to regulating sympathetic outflow: the medullary raphe nuclei, rostral ventrolateral medulla (RVLM), rostral ventromedial medulla, A5 adrenergic cell group region, locus coeruleus, nucleus subcoeruleus, and the paraventricular nucleus of the hypothalamus. The RVLM, the brain stem region typically considered to play the largest role in regulating muscle blood flow, contained neurons infected following the shortest postinoculation survival times. Approximately half of the infected RVLM neurons were immunopositive for tyrosine hydroxylase, indicating that they were catecholaminergic. Many (47%) of the RVLM neurons were dually infected by the recombinants of PRV injected into the left and right hindlimb, suggesting that the central nervous system has a limited capacity to independently regulate blood flow to left and right hindlimb muscles.
Early onset airway obstruction in response to organic dust in the horse
Authors: Deaton Christopher M. , Deaton Laura , Jose-Cunilleras Eduard , Vincent Thea L. , Baird Alan W. , Dacre K. , Marlin David J.
Published: December 2006

Equine recurrent airway obstruction (RAO) has been used as a naturally occurring model of human asthma. However, it is unknown whether there is an early-phase response in RAO. The aim of this study was to determine whether exposure to organic dust induces immediate changes in lung function in RAO-affected horses, which could be mediated by airway mast cells. Six RAO-affected horses in remission and six control horses were challenged with hay-straw dust suspension by nebulization. Total respiratory resistance at 1 Hz, measured by forced oscillation, was increased from 0.62 ± 0.09 cmH2O·l−1·s (mean ± SE) to 1.23 ± 0.20 cmH2O·l−1·s 15 min after nebulization in control horses ( P = 0.023) but did not change significantly in the RAO group. Total respiratory reactance at 1 Hz ( P = 0.005) was significantly lower in the control horses (−0.77 ± 0.07 cmH2O·l−1·s) than in the RAO group (−0.49 ± 0.04 cmH2O·l−1·s) 15 min after nebulization. Bronchoalveolar lavage fluid (BALF) histamine concentration was significantly elevated 10 and 20 min postnebulization in control horses but not in RAO horses. Minimum reactance at 1 Hz in the early postnebulization period significantly correlated with both prechallenge BALF mast cell numbers ( r = −0.65, P = 0.02) and peak BALF histamine concentration postnebulization ( r = −0.61, P = 0.04). In conclusion, RAO horses, unlike human asthmatic patients, do not exhibit an early-phase response. However, healthy control horses do demonstrate a mild but significant early (<20 min) phase response to inhaled organic dust. This response may serve to decrease the subsequent dose of dust inhaled and as such provide a protective mechanism, which may be compromised in RAO horses.
The acute impact of continuous positive airway pressure on nasal resistance: a randomized controlled comparison
Authors: Willing Stephanie , Pedro Maybelle San , Driver Helen S. , Munt Peter , Fitzpatrick Michael F.
Published: December 2006

Subjective nasal obstruction is common among users of continuous positive airway pressure (CPAP). The aim of this study was to measure the acute effect of CPAP on nasal resistance and nasal symptoms in awake normal subjects. Twenty-four healthy CPAP-naive adults [8 men, 16 women; mean age 30 yr (SD 14)] underwent a randomized controlled crossover study comparing nasal CPAP (8 cmH2O) for 6 h on one occasion and the control condition (nasal mask without CPAP) on the other. Nasal resistance measurements (posterior active rhinometry) before and after the test exposure were similar on both test days. Nasal resistance during CPAP exposure [2.04 cmH2O·l−1·s (SD 0.72)] was significantly lower than that of the control [2.67 cmH2O·l−1·s (SD 1.07)]: mean difference 0.66 cmH2O·l−1·s, 95% confidence interval 0.19–1.13 cmH2O·l−1·s. The gradient in pressure from CPAP mask to posterior naris during CPAP exposure varied from 1.6 to 2 cmH2O but was not significantly different between time points. Subjective nasal symptom scores and peak nasal inspiratory flow rates did not change significantly on either test day. We conclude that in awake CPAP-naive normal subjects, acute CPAP exposure is associated with a reduction in nasal resistance compared with the control condition, but it is not associated with an immediate post-CPAP change in subjective or objective nasal resistance.
Microsphere maps of regional blood flow and regional ventilation
Authors: Robertson H. Thomas , Hlastala Michael P.
Published: December 2006

Systematically mapped samples cut from lungs previously labeled with intravascular and aerosol microspheres can be used to create high-resolution maps of regional perfusion and regional ventilation. With multiple radioactive or fluorescent microsphere labels available, this methodology can compare regional flow responses to different interventions without partial volume effects or registration errors that complicate interpretation of in vivo imaging measurements. Microsphere blood flow maps examined at different levels of spatial resolution have revealed that regional flow heterogeneity increases progressively down to an acinar level of scale. This pattern of scale-dependent heterogeneity is characteristic of a fractal distribution network, and it suggests that the anatomic configuration of the pulmonary vascular tree is the primary determinant of high-resolution regional flow heterogeneity. At ∼2-cm3 resolution, the large-scale gravitational gradients of blood flow per unit weight of alveolar tissue account for <5% of the overall flow heterogeneity. Furthermore, regional blood flow per gram of alveolar tissue remains relatively constant with different body positions, gravitational stresses, and exercise. Regional alveolar ventilation is accurately represented by the deposition of inhaled 1.0-μm fluorescent microsphere aerosols, at least down to the ∼2-cm3 level of scale. Analysis of these ventilation maps has revealed the same scale-dependent property of regional alveolar ventilation heterogeneity, with a strong correlation between ventilation and blood flow maintained at all levels of scale. The ventilation-perfusion (V̇a/Q̇) distributions obtained from microsphere flow maps of normal animals agree with simultaneously acquired multiple inert-gas elimination technique V̇a/Q̇ distributions, but they underestimate gas-exchange impairment in diffuse lung injury.
Changes in expiratory muscle function following spinal cord section
Authors: Kowalski Krzysztof E. , Romaniuk Jaroslaw R. , DiMarco Anthony F.
Published: December 2006

Following spinal cord injury, muscles below the level of injury develop variable degrees of disuse atrophy. The present study assessed the physiological changes of the expiratory muscles in a cat model of spinal cord injury. Muscle fiber typing, cross-sectional area, muscle weight, and changes in pressure-generating capacity were assessed in five cats spinalized at the T6level. Airway pressure (P)-generating capacity was monitored during lower thoracic spinal cord stimulation before and 6 mo after spinalization. These parameters were also assessed in five acute animals, which served as controls. In spinalized animals, P fell from 41 ± l to 28 ± 3 cmH2O (means ± SE; P < 0.001). Muscle weight of the external oblique, internal oblique, transversus abdominis, and internal intercostal muscles decreased significantly ( P < 0.05 for each). Muscle weight of the external oblique, internal oblique, transversus abdominis, and internal intercostal, but not rectus abdominis (RA), correlated linearly with P ( r > 0.7 for each; P < 0.05 for each). Mean muscle fiber cross-sectional area of these muscles was significantly smaller ( P < 0.05 for each; except RA) and also correlated linearly with P ( r > 0.55 for each; P < 0.05 for each, except RA). In spinalized animals, the expiratory muscles demonstrated a significant increase in the population of fast muscle fibers. These results indicate that, following spinalization, 1) the expiratory muscles undergo significant atrophy and fiber-type transformation and 2) the P-generating capacity of the expiratory muscles falls significantly secondary to reductions in muscle mass.
Acute volume overload elevates T-wave alternans magnitude
Authors: Narayan Sanjiv M. , Drinan Darrel D. , Lackey Robert P. , Edman Carl F.
Published: December 2006

The objective of this study was to determine whether acute volume loading elevates T-wave alternans (TWA) in dogs with structurally normal hearts. TWA predicts sudden cardiac arrest in patients with left ventricular dysfunction and congestive heart failure. However, volume load and ventricular stretch may themselves precipitate arrhythmias. It is unclear to what extent volume load causes TWA. In six male mongrel dogs [25.8 kg (SD 4.2)] under general anesthesia, we measured TWA during progressive atrial pacing to 160 beats/min. Pacing was performed at baseline, at the midpoint and peak of a saline infusion designed to induce acute CHF, and then during diuresis. Dog 1 was hypothermic throughout the protocol and excluded from analysis. For dogs 2– 6, 102 ml/kg (SD 30) were infused over 315 min (SD 50), causing pulmonary capillary wedge pressure to rise from 9.6 (SD 3.5) to 21.2 mmHg (SD 1.6) ( P < 0.01), and heart rate variability to fall ( P < 0.01). TWA magnitude (Valt) rose in all dogs with volume load ( P < 0.001). Compared with baseline, TWA at peak infusion had higher magnitude [Valt 3.4 (SD 1.95) vs. 0.5 μV (SD 0.35); P = 0.011] and occurred at lower heart rates [128 (SD 6) vs. 151 beats/min (SD 12); P = 0.008]. Net volume load was linearly related to Valt ( P < 0.01), with each 10 ml/kg net volume load increasing Valt by 0.23 μV. Acute volume overload elevates TWA in normal canine hearts. Although dramatic, however, this effect may contribute clinically to abnormal TWA only in patients with marked volume overload. Future studies should examine the interaction of fluid overload, myocardial disease, and arrhythmia susceptibility.
The effect of a myocardial infarction on the normalized time-varying elastance curve
Authors: Jegger David , Mallik Ajit S. , Nasratullah Mohammed , Jeanrenaud Xavier , Silva Rafaela da , Tevaearai Hendrik , von Segesser Ludwig K. , Stergiopulos Nikolaos
Published: December 2006

It has been suggested that the shape of the normalized time-varying elastance curve [En( tn)] is conserved in different cardiac pathologies. We hypothesize, however, that the En( tn) differs quantitatively after myocardial infarction (MI). Sprague-Dawley rats ( n = 9) were anesthetized, and the left anterior descending coronary artery was ligated to provoke the MI. A sham-operated control group (CTRL) ( n = 10) was treated without the MI. Two months later, a conductance catheter was inserted into the left ventricle (LV). The LV pressure and volume were measured and the En( tn) derived. Slopes of En( tn) during the preejection period (αPEP), ejection period (αEP), and their ratio (β = αEP/αPEP) were calculated, together with the characteristic decay time during isovolumic relaxation (τ) and the normalized elastance at end diastole (Eminn). MI provoked significant LV chamber dilatation, thus a loss in cardiac output (−33%), ejection fraction (−40%), and stroke volume (−30%) ( P < 0.05). Also, it caused significant calcium increase (17-fold), fibrosis (2-fold), and LV hypertrophy. End-systolic elastance dropped from 0.66 ± 0.31 mmHg/μl (CTRL) to 0.34 ± 0.11 mmHg/μl (MI) ( P < 0.05). Normalized elastance was significantly reduced in the MI group during the preejection, ejection, and diastolic periods ( P < 0.05). The slope of En( tn) during the αPEPand β were significantly altered after MI ( P < 0.05). Furthermore, τ and end-diastolic Eminnwere both significantly augmented in the MI group. We conclude that the En( tn) differs quantitatively in all phases of the heart cycle, between normal and hearts post-MI. This should be considered when utilizing the single-beat concept.
Eighteenth Annual Pezcoller Symposium: Tumor Microenvironment and Heterotypic Interactions
Authors: Weinberg Robert , Mihich Enrico
Published: December 2006

This symposium was held in Trento, Italy, from June 27 to 29, 2006, and was co-chaired by Robert Weinberg and Enrico Mihich. The interactions between tumor cells and their microenvironment were discussed with particular emphasis on their molecular mechanisms. The roles of transforming growth factor β signaling, urokinase, and matrix metalloproteinases in matrix remodeling; the effects of matrix-tumor interactions on cell proliferation and migration; the tumor-promoting effects of inflammation and of related host cell and cytokine functions; the signaling mechanisms affecting the biology of the stroma; and the mechanisms governing angiogenesis were discussed. (Cancer Res 2006; 66(24): 11550-3)
Cancer Chemoprevention and Cancer Preventive Vaccines—A Call to Action: Leaders of Diverse Stakeholder Groups Present Strategies for Overcoming Multiple Barriers to Meet an Urgent Need
Authors: Herberman Ronald B. , Pearce Homer L. , Lippman Scott M. , Pyenson Bruce S. , Alberts David S.
Published: December 2006

The emerging field of cancer prevention through chemoprevention agents and cancer vaccines offers significant promise for reducing suffering and death from cancer. However, that promise may not be kept unless major barriers to progress are lowered or eliminated. Among the most significant barriers are the relatively small investment from government and industry in research and development of cancer preventive agents; a predominant emphasis of translational cancer research on therapeutic interventions for metastatic or advanced cancer; complexities of prevention trial design; a relatively uncharted Food and Drug Administration (FDA) approval process for preventive agents; insufficient public and patient understanding of the importance and potential for cancer preventive measures, with consequent unpredictable public and patient willingness to take preventive agents; an uncertain reimbursement from payors; and limitations in patent law, liability protection, and data package exclusivity that undermine the opportunity for recouping investment. Viewed individually or collectively, each of these barriers serves as a substantial deterrent to intellectual and financial investment by all sectors of the cancer community. In an effort to ultimately overcome these barriers, a Cancer Prevention Research Summit was assembled June 12–13, 2006 in Bethesda, Maryland, organized by C-Change with support from the AACR. The Summit brought together some 120 leaders from private, public, and not-for-profit entities, including cancer researchers and clinicians; federal health officials; regulatory agency representatives; pharmaceutical, biotech, and food industry leaders; patent attorneys; economists; public and private provider group executives; and advocates. Participants engaged in a detailed process to more carefully define the major barriers, identify potential solutions, and formulate initial priorities and recommendations for action. At the conclusion of this dialogue among experts, the following recommended actions were outlined: define policy solutions to patent, intellectual property, and liability law barriers; create an advisory document about the approval process for cancer chemopreventive agents and vaccines for the FDA; develop new design models for cancer chemopreventive clinical trials; outline the business case for chemopreventive agents and vaccines for federal research agencies, payors and investors; and implement a communications strategy to increase public awareness about the importance of chemoprevention and cancer preventive vaccines. (Cancer Res 2006; 66(24): 11540-9)
Effect of Frequency of Sucrose Exposure on Dental Biofilm Composition and Enamel Demineralization in the Presence of Fluoride
Authors: Ccahuana-Vásquez R.A. , Tabchoury C.P.M. , Tenuta L.M.A. , Del Bel Cury A.A. , Vale G.C. , Cury J.A.
Published: December 2006

It has been suggested that enamel would resist higher frequencies of sucrose exposure if fluoride from water or dentifrice is being used. However, the effect of increasing frequencies of sugar on dental biofilm composition is not well known. Ten volunteers living in a fluoridated area wore palatal appliances bearing human enamel slabs during 14 days. The slabs were exposed to 20% sucrose solution 0 (control), 2, 4, 6, 8 or 10 times/day and the volunteers used fluoride dentifrice 3 times/day. Enamel demineralization was significantly greater than control for sucrose frequencies higher than 6 times/day. However, biofilm mass, total microbiota, total streptococci, lactobacilli counts and insoluble extracellular polysaccharide concentration increased, while Ca, Pi and F concentration in whole biofilm decreased significantly, with frequencies of sucrose exposure lower than 6 times/day. The findings confirm that fluoride can reduce enamel demineralization if sucrose consumption is not higher than 6 times/day, but changes in the biochemical and microbiological composition of the biofilm are observed with lower frequencies of sucrose use.
Diet Intake and Caries Prevalence in Four-Year-Old Children Living in a Low-Prevalence Country
Authors: Öhlund I. , Holgerson P.L. , Bäckman B. , Lind T. , Hernell O. , Johansson I.
Published: December 2006

Preventive measures have dramatically decreased the prevalence of dental caries in children. However, risk factors for the disease in children living in low-prevalence areas remain elusive. In the present study we evaluated associations between dental caries, saliva levels of mutans streptococci and lactobacilli, and diet with special emphasis on the intake of fermentable carbohydrates and dairy products in 4-year-old children living in an area where the overall caries prevalence was low. Dietary intake was recorded in 234 infants as part of the Study of Infant Nutrition in Umeå, Sweden (SINUS). Of these the parents of 124 children gave consent to participate in a follow-up at 4 years of age. Dietary intake, height and weight, dental caries, oral hygiene, including tooth brushing habits, presence of plaque and gingival inflammation, fluoride habits and numbers of mutans streptococci and lactobacilli in saliva were recorded. Using multivariate stepwise logistic regression, caries experience was negatively associated with intake frequency of cheese (OR = 0.67; 95% CI = 0.44–0.98) and positively associated with the salivary level of mutans streptococci (OR = 1.57; 95% CI = 1.21–2.03). Caries experience was not correlated with intake frequency or amounts of carbohydrate-containing foods, with any other particular food, or with daily intake of energy, carbohydrate or any other macro- or micronutrient. We conclude that cheese intake may have a caries-protective effect in childhood populations where the overall caries prevalence and caries experience are low and the children are regularly exposed to fluoride from toothpaste.
A Comparison of Myocardial Perfusion Gated SPECT Studies Obtained at Rest and after Stress
Authors: Alfeeli Mahmoud A. , Syed Ghulam M. , Fielding Henry W. , Alenizi Eman K. , Collier Bert D. , Scheutz Flemming
Published: December 2006

Objective: To perform a comparison between post-stress and rest gated single-photon emission computer tomography (SPECT) myocardial perfusion imaging (MPI) studies to assess post-stress stunning and the variables underlying this phenomenon. Subjects and Methods: This was a prospective study of 318 consecutive adult patients undergoing stress and rest gated SPECT using a 2-day 99mTc-tetrofosmin protocol. Bruce protocol treadmill stress (n = 93) or i.v. dipyridamole pharmacologic stress (n = 225) were used as stressors. Ejection fractions (EF) and left ventricular (LV) end-diastolic (EDV) and end-systolic volumes (ESV) were calculated using the Cedars Sinai Quantitative Gated SPECT software. Perfusion defects were visually scored using a 20-segment model to obtain summed stress scores. Statistical analysis was performed by applying paired t test and multi-regression. Statistically significant (p < 0.05) paired differences between post-stress and rest EF and ESV and type of stressing were noted. Results: Analysis of patient groups based on the type of stress showed significantly low EF on post-stress studies for both treadmill and dipyridamole stressing and also significantly high ESV on post-stress studies for dipyridamole. Multi-regression analysis using differences in post-stress and rest EF, EDV and ESV as dependent and summed stress scores, type of stress, delay time, previous myocardial infarction and size of LV as independent variables showed statistically significant associations between high summed stress scores (>13) and size of post-stress LV for EDV and ESV differences. High volumes were noted on post-stress studies. The magnitudes of the observed differences were well within the reproducibility of LV volume calculations. Conclusions: Patients showing stunning had significant ischemia or a dilated LV. The stunning manifested as high EDV and ESV differences. The magnitude of the differences observed in EF and LV volumes were not clinically significant.
Occurrence of Campylobacter jejuni in Shiraz, Southwest Iran
Authors: Hassanzadeh Parvin , Motamedifar Mohammad
Published: December 2006

Objective: To investigate the occurrence of Campylobacter jejuni among other bacterial agents of acute diarrhea. Subjects and Methods: Over a period of 3 months, 114 specimens of acute diarrhea were collected from patients aged 2–58 years referred to Nemazi Hospital, Shiraz, Iran. The samples were tested for bacterial pathogens causing acute diarrhea. Results: Of the 114 samples, 40 proved to be positive for bacterial enteric pathogens: C. jejuni 11 (9.6%), Salmonella spp.18 (15.8%) and Shigella spp. 11 (9.6%). Maximum prevalence of C. jejuni was observed in patients aged 11–15 years. Significantly more females than males were infected with all diarrheal agents (p <0.05). Conclusion: This study confirmed the presence of C. jejuni as a significant cause of gastroenteritis in Shiraz, Southwest Iran.