bluuebunny/crossref_metadata_2025 huggingface dataset:
Amino Acid 226 in the Hemagglutinin of H9N2 Influenza Viruses Determines Cell Tropism and Replication in Human Airway Epithelial Cells
Authors: Wan Hongquan , Perez Daniel R.
Published: March 2007

Influenza A viruses of the H9N2 subtype are endemic in poultry in many Eurasian countries and have occasionally caused clinical respiratory diseases in humans. While some avian H9N2 viruses have glutamine (Q) at amino acid position 226 of the hemagglutinin (HA) receptor-binding site, an increasing number of isolates have leucine (L) at this position, which has been associated with the establishment of stable lineages of the H2 and H3 subtypes of viruses in humans. Little is known about the importance of this molecular trait in the infection of H9N2 viruses in humans. We show here that during the course of a single cycle of infection in human airway epithelial (HAE) cells cultured in vitro, the L-226-containing H9N2 viruses displayed human virus-like cell tropisms (preferentially infecting nonciliated cells) different from the tropisms showed by Q-226-containing H9N2 isolates (which infect both ciliated and nonciliated cells at ratios of 1:1 to 3:2) or other waterfowl viruses (which preferentially infect ciliated cells). During multiple cycles of replication in HAE cultures, L-226-containing H9N2 isolates grew consistently more efficiently and reached approximately 100-fold-higher peak titers than those containing Q-226, although peak titers were significantly lower than those induced by human H3N2 viruses. Our results suggest that the variation in residue 226 in the HA affects both cell tropism and replication of H9N2 viruses in HAE cells and may have implications for the abilities of these viruses to infect humans.
Long-Term Control of Simian Immunodeficiency Virus Replication with Central Memory CD4
+
T-Cell Preservation after Nonsterile Protection by a Cytotoxic T-Lymphocyte-Based Vaccine
Authors: Kawada Miki , Tsukamoto Tetsuo , Yamamoto Hiroyuki , Takeda Akiko , Igarashi Hiroko , Watkins David I. , Matano Tetsuro
Published: March 2007

Induction of virus-specific CD8
+
cytotoxic T-lymphocyte (CTL) responses is a promising strategy for AIDS vaccine development. However, it has remained unclear if or how long-term viral containment and disease control are attainable by CTL-based nonsterile protection. Here, we present three rhesus macaques that successfully maintained Env-independent vaccine-based control of simian immunodeficiency virus (SIV) mac239 replication without disease progression for more than 3 years. SIV-specific neutralizing antibody induction was inefficient in these controllers. Vaccine-induced Gag-specific CTLs were crucial for the chronic as well as the primary viral control in one of them, whereas those Gag-specific CTL responses became undetectable and CTLs specific for SIV antigens other than Gag, instead, became predominant in the chronic phase in the other two controllers. A transient CD8
+
cell depletion experiment 3 years postinfection resulted in transient reappearance of plasma viremia in these two animals, suggesting involvement of the SIV non-Gag-specific CTLs in the chronic SIV control. This sustained, neutralizing antibody-independent viral control was accompanied with preservation of central memory CD4
+
T cells in the chronic phase. Our results suggest that prophylactic CTL vaccine-based nonsterile protection can result in long-term viral containment by adapted CTL responses for AIDS prevention.
Endometrial stromal tumours of the uterus: a practical approach using conventional morphology and ancillary techniques
Authors: Baker Patricia , Oliva Esther
Published: March 2007

Endometrial stromal tumours (ESTs) are diagnosed in most instances by light microscopy. Often, the greatest challenge is to distinguish between the different subtypes of these tumours. Furthermore, a handful of new or relatively new entities have been described in the literature, which may cause problems in the differential diagnosis; highly cellular leiomyoma is the most common. In addition, new antibodies have been developed to help in the distinction of ESTs from their mimics, as there are prognostic and therapeutic implications. A practical approach is provided for the diagnosis of ESTs on the basis of systematic assessment of histological and immunohistochemical parameters, and recent developments related to these tumours are highlighted.
Early percutaneous transhepatic gallbladder drainage compared with endoscopic retrograde cholangiopancreatography and papillotomy treatment for severe gallstone associated acute pancreatitis
Authors: Yu Wenkui , Li Weiqin , Wang Zhiming , Ye Xianghong , Li Ning , Li Jieshou
Published: March 2007

Objective

Percutaneous transhepatic gallbladder drainage (PTGD) was compared with endoscopic treatment (within 72 hours after the onset of symptoms) in patients with severe biliary pancreatitis to evaluate the curative effect of PTGD in preventing bile track complications in these patients.

Methods

Eligible patients were randomised to receive early treatment with PTGD or endoscopic treatment. If the initial emergency endoscopic or PTGD treatment failed, patients received another drainage treatment within 24 hours. From November 2001 to August 2005, 101 patients were randomly assigned to early PTGD (n = 51) or endoscopic retrograde cholangiopancreatography (ERCP) (n = 50). Overall mortality, mortality due to pancreatitis and complications were compared in these two groups.

Results

48 of 52 patients were successfully treated with ERCP and 53 of 55 with PTGD. Seven patients (6.9%; three in the endoscopic treatment group and four in the PTGD group) died within four months after the onset of pancreatitis (p = 0.798); three patients in the endoscopic group and three in the PTGD group died from acute biliary pancreatitis. The overall rate of complications was similar in the two groups and there were no major differences in the incidence of local or systemic complications.

Conclusions

PTGD treatment is a simple, convenient and effective treatment of severe gallstone associated acute pancreatitis when endoscopic treatment fails.
Raised cardiac troponin T levels in patients without acute coronary syndrome
Authors: Wong P , Murray S , Ramsewak A , Robinson A , van Heyningen C , Rodrigues E
Published: March 2007

Objective

To investigate the frequency, diagnosis and outcome of patients admitted to hospital with acute coronary syndrome (ACS) or other conditions associated with raised levels of cardiac troponin T.

Design

Observational study.

Setting

A large university hospital.

Patients

Consecutive patients admitted over an 8-week period who had a serum troponin T test as part of their clinical assessment were included. Patients were separated into those with raised (⩾0.01 μg/l) or normal (<0.01 μg/l) troponin T levels, and further categorised into those with or without a diagnosis of ACS.

Main outcome measures

In-hospital mortality in all patients; and 6-month hospital re-admissions and all-cause mortality in patients without or with ACS and raised levels of troponin T.

Results

Of 1021 patients, 118 patients had no ACS but raised troponin T levels, 195 had ACS with raised troponin T, 80 had ACS with normal troponin T and 628 had no ACS with normal troponin T. Their in-hospital all-cause mortalities were 36%, 18%, 0% and 3%, respectively (p<0.001, highest mortality v other groups). 6-month all-cause mortality remained higher in patients without ACS and with raised levels of troponin T than in those with ACS and raised troponin T (42% v 29%; p = 0.020).

Conclusions

Patients without ACS but with raised levels of troponin T comprised 38% of all hospitalised patients found to have raised troponin T. These patients had worse in-hospital and 6-month outcome than those having ACS with raised levels of troponin T.
Heights and haematology: the story of haemoglobin at altitude
Authors: Windsor Jeremy S , Rodway George W
Published: March 2007

In order to compensate for the low partial pressure of oxygen at altitude, the human body undergoes a number of physiological changes. A vital component in this process is the increase in the concentration of circulating haemoglobin. The role of HIF-1α, erythropoietin and red blood cells in this acclimatisation process is described, together with the fall in plasma volume that increases the concentration of haemoglobin in the early stages of hypoxic exposure.
How do you treat bleeding disorders with desmopressin?
Authors: Özgönenel Bülent , Rajpurkar Madhvi , Lusher Jeanne M
Published: March 2007

Desmopressin is an analog of vasopressin that exerts a substantial haemostatic effect by inducing the release of von Willebrand factor from its storage sites in endothelial cells. It has proved useful in treating or preventing bleeding episodes in patients with von Willebrand disease, haemophilia A and platelet function defects. Its efficacy in achieving a satisfactory level of haemostasis has reduced the use of blood products to treat bleeding episodes. Clinicians need to become familiar with the use of this drug that has become a home medication for many patients with inherited bleeding disorders.
Prevalence and risk factors of fatty liver disease in the Shuiguohu district of Wuhan city, central China
Authors: Wang Zhongli , Xia Bing , Ma Chunwei , Hu Zhengguo , Chen Xiangqun , Cao Ping
Published: March 2007

Background

Fatty liver disease (FLD) is highly prevalent in Western countries, but recent data have shown that FLD is also emerging in China.

Aim

To investigate the prevalence and risk factors of FLD in the Shuiguohu district of Wuhan city, central China, during 1995–2004.

Methods

12247 individuals (7179 men and 5068 women) over 18 years of age who were living in the area were investigated for FLD in the Zhongnan Hospital of Wuhan University from 1995 to 2004. FLD was determined by the ultrasonographic method. Height, weight, blood pressure, fasting blood sugar, alanine aminotransferase, total cholesterol and triglyceride were determined by routine laboratory methods.

Results

The prevalence of FLD was 12.5% in 1995, and rose gradually to 24.5% by 2003–4. The prevalence was twice as high in men (28.1%) as in women (13.8%), and increased with age in females, and males <60 years of age. Multivariate analysis showed that several risk factors were profoundly associated with the prevalence of FLD, including male sex, old age, obesity, hyperlipidaemia (cholesterol or triglyceride), fasting hyperglycemia and hypertension.

Conclusion

The prevalence of FLD in the Shuiguohu district of Wuhan city, central China, was shown to have increased during the 10-year period, 1995 to 2004. The FLD was found to be closely associated with sex, age, obesity and other metabolic syndrome features.
NT-proBNP and the diagnosis of left ventricular systolic dysfunction within two acute NHS trust catchment areas: the initial Teesside experience
Authors: Turley A J , Roberts A P , Davies A , Rowell N , Drury J , Smith R H , Shyam-Sundar A , Stewart M J
Published: March 2007

Purpose

To evaluate the predictive value of N-terminal pro B-type natiuretic peptide (NT-proBNP) reference cut-off values as diagnostic markers for left ventricular systolic dysfunction (LVSD).

Study design

A retrospective study assessing the use of NT-proBNP in the diagnostic algorithm for the investigation of patients with suspected signs and symptoms of LVSD presenting to primary care.

Results

A generic NT-proBNP cut-off (150 ng/l) value has similar negative and positive predictive valves, specificity and sensitivity compared to age and sex specific cut-off values.

Conclusion

When using NT-proBNP as a triage tool for screening patients with signs and symptoms suggestive of LVSD, a simple generic cut-off level is as effective as more complex age sex specific cut-off values.
Inhaled insulins
Authors: Ghosh Sujoy , Collier Andrew
Published: March 2007

As a result of knowledge gained from the management of asthma with inhalers and nebulisers, pulmonary delivery devices for insulin have been developed. Particle size of the aerosol particularly influences drug delivery. Although several pharmaceutical companies are developing different systems, Pfizer have launched the first inhaled insulin (Exubera). Clinical trials have taken place in patients with both type 1 and type 2 diabetes, but have shown similar glucose control as subcutaneous insulin delivery. However, patient satisfaction does seem to be increased in patients taking inhaled insulins. Further studies are needed to investigate compliance, side-effect profiles, quality of life, long-term glycaemia control and cost effectiveness.
Drying and wetting characteristics of a two-layer soil column
Authors: Indrawan I Gde Budi , Rahardjo Harianto , Leong Eng-Choon
Published: March 2007

The drying and wetting characteristics of a two-layer soil column consisting of a 50 cm thick soil mixture over a 50 cm thick gravelly sand were investigated in this study. A series of infiltration tests were conducted in the laboratory through an infiltration column apparatus equipped with a tensiometer–transducer system, time-domain reflectometry, and water flow measurement system. Numerical analyses were performed using a finite element model to simulate water infiltration into the laboratory model under steady-state and transient conditions. The experimental data and numerical simulation results showed that static nonequilibrium profiles of pore-water pressure head were developed in the gravelly sand shortly after a drying process was started. The low unsaturated permeability of the gravelly sand resulted in a delay in downward water flow into the lower soil layer during a wetting process portion of the rainfall test.Key words: drying and wetting characteristics, soil column, infiltration, numerical analyses, soil-water characteristic curve, permeability function.
Elastoplastic model for unsaturated soil with incorporation of the soil-water characteristic curve
Authors: Thu Trinh Minh , Rahardjo Harianto , Leong Eng-Choon
Published: March 2007

An elastoplastic model is proposed in this paper that incorporates the soil-water characteristic curve (SWCC) for obtaining soil parameters of unsaturated soil. The SWCC is shown to govern the rate of change in the soil parameters for the elastoplastic model with respect to matric suction. A series of isotropic consolidation tests under different matric suctions and tests for obtaining SWCC were carried out on statically compacted kaolin specimens. Nanyang Technological University (NTU) mini suction probes were installed along the height of the specimen to measure pore-water pressures during isotropic consolidation and SWCC tests. The results of isotropic consolidation tests demonstrate the strong influence of matric suction on compressibility and stiffness of the soil specimens. The experiments were also simulated using the proposed elastoplastic model and SWCC of the compacted kaolin. The simulated results agree closely with the experimental results. In addition, the proposed elastoplastic model was also verified against published data from the literature.Key words: matric suction, yield surface, soil-water characteristic curve, mini suction probe, elastoplastic model, unsaturated soil.
MEASUREMENT OF FISSION FRAGMENT ANISOTROPIES FOR PROTON-INDUCED FISSION OF TWO PRE-ACTINIDE NUCLEI AT SEVERAL ENERGIES
Authors: SOHEYLI S. , NOSHAD H. , LAMEHI-RACHTI M.
Published: March 2007

The angular distribution of fission fragments has been measured for proton-induced fission of197Au and209Bi nuclei at several energies between 25 and 30 MeV using surface-barrier detectors. The measured anisotropies are found to be in agreement with the predictions of the standard saddle-point statistical model. The measured anisotropies for neither of the nuclei show any anomalous behavior as a function of both energy and entrance channel mass asymmetry. The fission cross sections of197Au and209Bi nuclei were also measured and compared with that of the previous works.
CLASSICAL SOLUTIONS OF SIGMA MODELS IN CURVED BACKGROUNDS BY THE POISSON–LIE T-PLURALITY
Authors: HLAVATÝ LADISLAV , HÝBL JAN , TUREK MIROSLAV
Published: March 2007

Classical equations of motion for three-dimensional σ-models in curved background are solved by a transformation that follows from the Poisson–Lie T-plurality and transform them into the equations in the flat background. Transformations of coordinates that make the metric constant are found and used for solving the flat model. The Poisson–Lie transformation is explicitly performed by solving the PDE's for auxiliary functions and finding the relevant transformation of coordinates in the Drinfel'd double. String conditions for the solutions are preserved by the Poisson–Lie transformations. Therefore we are able to specify the type of σ-model solutions that solve also equations of motion of three-dimensional relativistic strings in the curved backgrounds. Some simple examples are given.
ANOMALY FOR MODEL BUILDING
Authors: SARKAR UTPAL
Published: March 2007

A simple algorithm to calculate the group theory factor entering in anomalies at four and six dimensions for SU (N) and SO (N) groups in terms of the Casimir invariants of their subgroups is presented. Explicit examples of some of the lower dimensional representations of SU (n), n ≤ 5 and SO (10) groups are presented, which could be used for model building in four and six dimensions.
ON GRAPH-THEORETIC IDENTIFICATIONS OF ADINKRAS, SUPERSYMMETRY REPRESENTATIONS AND SUPERFIELDS
Authors: DORAN C. F. , FAUX M. G. , GATES S. J. , HÜBSCH T. , IGA K. M. , LANDWEBER G. D.
Published: March 2007

In this paper, we discuss off-shell representations of N-extended supersymmetry in one dimension, i.e. N-extended supersymmetric quantum mechanics, and following earlier work on the subject, we codify them in terms of graphs called Adinkras. This framework provides a method of generating all Adinkras with the same topology, and so also all the corresponding irreducible supersymmetric multiplets. We develop some graph theoretic techniques to understand these diagrams in terms of a relatively small amount of information, namely, at what heights various vertices of the graph should be "hung."

We then show how Adinkras that are the graphs of N-dimensional cubes can be obtained for superfields satisfying constraints that involve superderivatives. This dramatically widens the range of supermultiplets that can be described using the superspace formalism and also organizes them. Other topologies for Adinkras are possible, and we show that it is reasonable that these are also the result of constraining superfields using superderivatives.

We arrange the family of Adinkras with an N-cubical topology, and so also the sequence of corresponding irreducible supersymmetric multiplets, in a cyclic sequence, which we call the main sequence. We produce the N = 1 and N = 2 main sequences in detail, and indicate some aspects of the situation for higher N.
Effects of elevated physiological temperatures on sarcoplasmic reticulum function in mechanically skinned muscle fibers of the rat
Authors: van der Poel C. , Stephenson D. G.
Published: March 2007

Properties of the sarcoplasmic reticulum (SR) with respect to Ca2+ loading and release were measured in mechanically skinned fiber preparations from isolated extensor digitorum longus (EDL) muscles of the rat that were either kept at room temperature (23°C) or exposed to temperatures in the upper physiological range for mammalian skeletal muscle (30 min at 40 or 43°C). The ability of the SR to accumulate Ca2+ was significantly reduced by a factor of 1.9–2.1 after the temperature treatments due to a marked increase in SR Ca2+ leak, which persisted for at least 3 h after treatment. Results with blockers of Ca2+ release channels (ruthenium red) and SR Ca2+ pumps [2,5-di( tert-butyl)-1,4-hydroquinone] indicate that the increased Ca2+ leak was not through the SR Ca2+ release channel or the SR Ca2+ pump, although it is possible that the leak pathway was via oligomerized Ca2+ pump molecules. No significant change in the maximum SR Ca2+-ATPase activity was observed after the temperature treatment, although there was a tendency for a decrease in the SR Ca2+-ATPase. The observed changes in SR properties were fully prevented by the superoxide (O2•−) scavenger Tiron (20 mM), indicating that the production of O2•− at elevated temperatures is responsible for the increase in SR Ca2+ leak. Results show that physiologically relevant elevated temperatures 1) induce lasting changes in SR properties with respect to Ca2+ handling that contribute to a marked increase in the SR Ca2+ leak and, consequently, to the reduction in the average coupling ratio between Ca2+ transport and SR Ca2+-ATPase and muscle performance, and 2) that these changes are mediated by temperature-induced O2•− production.
Effect of Ca2+ on cardiac mitochondrial energy production is modulated by Na+ and H+ dynamics
Authors: Nguyen My-Hanh T. , Dudycha S. J. , Jafri M. Saleet
Published: March 2007

The energy production of mitochondria in heart increases during exercise. Several works have suggested that calcium acts at multiple control points to activate net ATP production in what is termed “parallel activation”. To study this, a computational model of mitochondrial energy metabolism in the heart has been developed that integrates the Dudycha-Jafri model for the tricarboxylic acid cycle with the Magnus-Keizer model for mitochondrial energy metabolism and calcium dynamics. The model improves upon the previous formulation by including an updated formulation for calcium dynamics, and new descriptions of sodium, hydrogen, phosphate, and ATP balance. To this end, it incorporates new formulations for the calcium uniporter, sodium-calcium exchange, sodium-hydrogen exchange, the F1F0-ATPase, and potassium-hydrogen exchange. The model simulates a wide range of experimental data, including steady-state and simulated pacing protocols. The model suggests that calcium is a potent activator of net ATP production and that as pacing increases energy production due to calcium goes up almost linearly. Furthermore, it suggests that during an extramitochondrial calcium transient, calcium entry and extrusion cause a transient depolarization that serve to increase NADH production by the tricarboxylic acid cycle and NADH consumption by the respiration driven proton pumps. The model suggests that activation of the F1F0-ATPase by calcium is essential to increase ATP production. In mitochondria very close to the release sites, the depolarization is more severe causing a temporary loss of ATP production. However, due to the short duration of the depolarization the net ATP production is also increased.
Cardiac mitochondrial bioenergetics, oxidative stress, and aging
Authors: Judge Sharon , Leeuwenburgh Christiaan
Published: March 2007

Mitochondria have been a central focus of several theories of aging as a result of their critical role in bioenergetics, oxidant production, and regulation of cell death. A decline in cardiac mitochondrial function coupled with the accumulation of oxidative damage to macromolecules may be causal to the decline in cardiac performance with age. In contrast, regular physical activity and lifelong caloric restriction can prevent oxidative stress, delay the onset of morbidity, increase life span, and reduce the risk of developing several pathological conditions. The health benefits of life long exercise and caloric restriction may be, at least partially, due to a reduction in the chronic amount of mitochondrial oxidant production. In addition, the available data suggest that chronic exercise may serve to enhance antioxidant enzyme activities, and augment certain repair/removal pathways, thereby reducing the amount of oxidative tissue damage. However, the characterization of age-related changes to cardiac mitochondria has been complicated by the fact that two distinct populations of mitochondria exist in the myocardium: subsarcolemmal mitochondria and interfibrillar mitochondria. Several studies now suggest the importance of studying both mitochondrial populations when attempting to elucidate the contribution of mitochondrial dysfunction to myocardial aging. The role that mitochondrial dysfunction and oxidative stress play in contributing to cardiac aging will be discussed along with the use of lifelong exercise and calorie restriction as countermeasures to aging.
S-acylation regulates Kv1.5 channel surface expression
Authors: Zhang Lian , Foster Karyn , Li Qiuju , Martens Jeffrey R.
Published: March 2007

The number of ion channels expressed on the cell surface shapes the complex electrical response of excitable cells. An imbalance in the ratio of inward and outward conducting channels is unfavorable and often detrimental. For example, over- or underexpression of voltage-gated K+ (Kv) channels can be cytotoxic and in some cases lead to disease. In this study, we demonstrated a novel role for S-acylation in Kv1.5 cell surface expression. In transfected fibroblasts, biochemical evidence showed that Kv1.5 is posttranslationally modified on both the NH2 and COOH termini via hydroxylamine-sensitive thioester bonds. Pharmacological inhibition of S-acylation, but not myristoylation, significantly decreased Kv1.5 expression and resulted in accumulation of channel protein in intracellular compartments and targeting for degradation. Channel protein degradation was rescued by treatment with proteasome inhibitors. Time course experiments revealed that S-acylation occurred in the biosynthetic pathway of nascent channel protein and showed that newly synthesized Kv1.5 protein, but not protein expressed on the cell surface, is sensitive to inhibitors of thioacylation. Sensitivity to inhibitors of S-acylation was governed by COOH-terminal, but not NH2-terminal, cysteines. Surprisingly, although intracellular cysteines were required for S-acylation, mutation of these residues resulted in an increase in Kv1.5 cell surface channel expression, suggesting that screening of free cysteines by fatty acylation is an important regulatory step in the quality control pathway. Together, these results show that S-acylation can regulate steady-state expression of Kv1.5.
Role of glycolytically generated ATP for CaMKII-mediated regulation of intracellular Ca2+ signaling in bovine vascular endothelial cells
Authors: Aromolaran Ademuyiwa S. , Zima Aleksey V. , Blatter Lothar A.
Published: March 2007

The role of glycolytically generated ATP in Ca2+/calmodulin-dependent kinase II (CaMKII)-mediated regulation of intracellular Ca2+ signaling was examined in cultured calf pulmonary artery endothelial (CPAE) cells. Exposure of cells (extracellular Ca2+ concentration = 2 mM) to glycolytic inhibitors 2-deoxy-d-glucose (2-DG), pyruvate (pyr) + β-hydroxybutyrate (β-HB), or iodoacetic acid (IAA) caused an increase of intracellular Ca2+ concentration ([Ca2+]i). CaMKII inhibitors (KN-93, W-7) triggered a similar increase of [Ca2+]i. The rise of [Ca2+]i was characterized by a transient spike followed by a small sustained plateau of elevated [Ca2+]i. In the absence of extracellular Ca2+ 2-DG caused an increase in [Ca2+]i, suggesting that inhibition of glycolysis directly triggered release of Ca2+ from intracellular endoplasmic reticulum (ER) Ca2+ stores. The inositol-1,4,5-trisphosphate receptor (IP3R) inhibitor 2-aminoethoxydiphenyl borate abolished the KN-93- and 2-DG-induced Ca2+ response. Ca2+ release was initiated in peripheral cytoplasmic processes from which activation propagated as a [Ca2+]i wave toward the central region of the cell. Focal application of 2-DG resulted in spatially confined elevations of [Ca2+]i. Propagating [Ca2+]i waves were preceded by [Ca2+]i oscillations and small, highly localized elevations of [Ca2+]i (Ca2+ puffs). Inhibition of glycolysis with 2-DG reduced the KN-93-induced Ca2+ response, and vice versa during inhibition of CaMKII 2-DG-induced Ca2+ release was attenuated. Similar results were obtained with pyr + β-HB and W-7. Furthermore, 2-DG and IAA caused a rapid increase of intracellular Mg2+ concentration, indicating a concomitant drop of cellular ATP levels. In conclusion, CaMKII exerts a profound inhibition of ER Ca2+ release in CPAE cells, which is mediated by glycolytically generated ATP, possibly through ATP-dependent phosphorylation of the IP3R.
Corticosteroid receptor-mediated mechanisms in the amygdala regulate anxiety and colonic sensitivity
Authors: Myers Brent , Greenwood-Van Meerveld Beverley
Published: March 2007

Our previous studies have shown that stereotaxic implantation of corticosterone (Cort) onto the central amygdaloid nucleus increases both anxiety and colonic sensitivity. The goal of this study was to examine the relative importance of amygdaloid glucocorticoid (GR) and mineralocorticoid receptor (MR)-mediated mechanisms in the induction of anxiety and colonic hypersensitivity. In male Fischer 344 rats, Cort or cholesterol micropellets were stereotaxically implanted bilaterally at the dorsal boundary of the central amygdaloid nucleus either alone or in combination with a GR antagonist, mifepristone, or a MR antagonist, spironolactone. Anxiety was assessed on the elevated plus maze and quantified as the percentage of time spent in open arm exploration. Colonic sensitivity was measured by recording a visceromotor response, the number of abdominal muscle contractions in response to colorectal distension. In Cort-implanted rats there was a significant reduction in the percentage of time spent in the open arms of the elevated plus maze compared with cholesterol controls, indicating increased anxiety. Furthermore, colonic hypersensitivity was observed in response to colorectal distension compared with rats with cholesterol implants. In rats with Cort implants combined with either a GR or MR antagonist, there was a significant inhibition of anxiety and colonic hypersensitivity. Our data suggest that both GR and MR play a critical role in Cort-induced anxiety and colonic hypersensitivity.
In Vitro Properties of Neurons in the Rat Pretectal Nucleus of the Optic Tract
Authors: Prochnow N. , Lee P. , Hall W. C. , Schmidt M.
Published: March 2007

The nucleus of the optic tract (NOT) has been implicated in the initiation of the optokinetic reflex (OKR) and in the modulation of visual activity during saccades. The present experiments demonstrate that these two functions are served by separate cell populations that can be distinguished by differences in both their cellular physiology and their efferent projections. We compared the response properties of NOT cells in rats using target-directed whole cell patch-clamp recording in vitro. To identify the cells at the time of the recording experiments, they were prelabeled by retrograde axonal transport of WGA-apo-HRP-gold (15 nm), which was injected into their primary projection targets, either the ipsilateral superior colliculus (iSC), or the contralateral NOT (cNOT), or the ipsilateral inferior olive (iIO). Retrograde labeling after injections in single animals of either WGA-apo-HRP-gold with different particle sizes (10 and 20 nm) or two different fluorescent dyes distinguished two NOT cell populations. One projects to both the iSC and cNOT. These cells are spontaneously active in vitro and respond to intracellular depolarizations with temporally regular tonic firing. The other population projects to the iIO and consists of cells that show no spontaneous activity, respond phasically to intracellular depolarization, and show irregular firing patterns. We propose that the spontaneously active pathway to iSC and cNOT is involved in modulating the level of visual activity during saccades and that the phasically active pathway to iIO provides a short-latency relay from the retina to premotor mechanisms involved in reducing retinal slip.
Precise Alignment of Micromachined Electrode Arrays With V1 Functional Maps
Authors: Nauhaus Ian , Ringach Dario L.
Published: March 2007

Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. Our strategy consists of first measuring the orientation maps in V1 using intrinsic optical imaging. A micromachined electrode array is subsequently implanted in the same patch of cortex for electrophysiological recordings, including the measurement of orientation tuning curves. The location of the array within the map is obtained by finding the position that maximizes the agreement between the preferred orientations measured electrically and optically. Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.
Variability and Corresponding Amplitude–Velocity Relation of Activity Propagating in One-Dimensional Neural Cultures
Authors: Jacobi Shimshon , Moses Elisha
Published: March 2007

We investigate the propagation of neural activity along one-dimensional rat hippocampal cultures patterned in lines over multielectrode arrays. Activity occurs spontaneously or is evoked by local electrical or chemical stimuli, with different resulting propagation velocities and firing rate amplitudes. A variability of an order of magnitude in velocity and amplitude is observed in spontaneous activity. A linear relation between velocity and amplitude is identified. We define a measure for neuron activation synchrony and find that it correlates with front velocity and is higher for electrically evoked fronts. We present a model that explains the linear relation between amplitude and velocity, which highlights the role of synchrony. The relation to current models for signal propagation in neural media is discussed.
Muscarinic Receptor Activation Elicits Sustained, Recurring Depolarizations in Reticulospinal Neurons
Authors: Smetana R. W. , Alford S. , Dubuc R.
Published: March 2007

In lampreys, brain stem reticulospinal (RS) neurons constitute the main descending input to the spinal cord and activate the spinal locomotor central pattern generators. Cholinergic nicotinic inputs activate RS neurons, and consequently, induce locomotion. Cholinergic muscarinic agonists also induce locomotion when applied to the brain stem of birds. This study examined whether bath applications of muscarinic agonists could activate RS neurons and initiate motor output in lampreys. Bath applications of 25 μM muscarine elicited sustained, recurring depolarizations (mean duration of 5.0 ± 0.5 s recurring with a mean period of 55.5 ± 10.3 s) in intracellularly recorded rhombencephalic RS neurons. Calcium imaging experiments revealed that muscarine induced oscillations in calcium levels that occurred synchronously within the RS neuron population. Bath application of TTX abolished the muscarine effect, suggesting the sustained depolarizations in RS neurons are driven by other neurons. A series of lesion experiments suggested the caudal half of the rhombencephalon was necessary. Microinjections of muscarine (75 μM) or the muscarinic receptor (mAchR) antagonist atropine (1 mM) lateral to the rostral pole of the posterior rhombencephalic reticular nucleus induced or prevented, respectively, the muscarinic RS neuron response. Cells immunoreactive for muscarinic receptors were found in this region and could mediate this response. Bath application of glutamatergic antagonists (6-cyano-7-nitroquinoxaline-2,3-dione/d-2-amino-5-phosphonovaleric acid) abolished the muscarine effect, suggesting that glutamatergic transmission is needed for the effect. Ventral root recordings showed spinal motor output coincides with RS neuron sustained depolarizations. We propose that unilateral mAchR activation on specific cells in the caudal rhombencephalon activates a circuit that generates synchronous sustained, recurring depolarizations in bilateral populations of RS neurons.
Repetition Suppression in Monkey Inferotemporal Cortex: Relation to Behavioral Priming
Authors: McMahon David B. T. , Olson Carl R.
Published: March 2007

In tasks requiring judgments about visual stimuli, humans exhibit repetition priming, responding with increased speed when a stimulus is repeated. Repetition priming might depend on repetition suppression, a phenomenon first observed in monkey inferotemporal cortex (IT) whereby, when a stimulus is repeated, the strength of the neuronal visual response is reduced. If the reduction resulted in sharpening of the cortical representation of the stimulus, and did not just scale it down, then speeded processing might result. To explore the relation between repetition priming and repetition suppression, we monitored neuronal activity in IT while monkeys performed a symmetry decision task. We found 1) that monkeys exhibit repetition priming, 2) that IT neurons simultaneously exhibit repetition suppression, 3) that repetition priming and repetition suppression do not vary in a significantly correlated fashion across trials, and 4) that repetition suppression scales down the representation of the stimulus without sharpening it. We conclude that repetition suppression accompanies repetition priming but is unlikely to be its cause.
Desynchronization of Glutamate Release Prolongs Synchronous CA3 Network Activity
Authors: Jones Jethro , Stubblefield Elizabeth A. , Benke Timothy A. , Staley Kevin J.
Published: March 2007

Periodic bursts of activity in the disinhibited in vitro hippocampal CA3 network spread through the neural population by the glutamatergic recurrent collateral axons that link CA3 pyramidal cells. It was previously proposed that these bursts of activity are terminated by exhaustion of releasable glutamate at the recurrent collateral synapses so that the next periodic burst of network activity cannot occur until the supply of glutamate has been replenished. As a test of this hypothesis, the rate of glutamate release at CA3 axon terminals was reduced by substitution of extracellular Ca2+ with Sr2+. Reduction of the rate of glutamate release reduces the rate of depletion and should thereby prolong bursts. Here we demonstrate that Sr2+ substitution prolongs spontaneous bursts in the disinhibited adult CA3 hippocampal slices to 37.2 ± 7.6 (SE) times the duration in control conditions. Sr2+ also decreased the probability of burst initiation and the rate of burst onset, consistent with reduced synchrony of glutamate release and a consequent reduced rate of spread of excitation through the slice. These findings support the supply of releasable glutamate as an important determinant of the probability and duration of synchronous CA3 network activity.
Numerical Flow Analysis in a Rotating Square Duct and a RotatingCurved‐Duct
Authors: Baekt Je Hyun , Ko Chang Hwan
Published: March 2007

A numerical study is conducted on the fully‐developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter‐rotating vortices are shown with a quasi‐parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double‐vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter‐rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double‐vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a 90°‐bend square duct that rotates about axis parallel to the axial direction of the inlet. At a 90°‐bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.
Experimental Modal Analysis – A Tool for UnbalanceIdentification of Rotating Machines
Authors: Kreuzinger-Janik T. , Irretier H.
Published: March 2007

In this paper a method is proposed for unbalance identification ofelastic rotors. The method is essentially based on the rotordynamic theory combined with experimental modal analysis and allows to identify the unbalance distribution on the complete rotor. A rotor test rig designed for rotordynamic experiments, modal analysis and especially for the unbalance identification has been developed. It allows an arbitrary excitation with a particularly developed noncontact magnetic exciter, as well as measuring vibrations in radial direction with non‐contact laser sensors and eddy currents. Special effects of rotordynamic like anisotropic journal bearings and gyroscopic forces can be simulated. Experimental and theoretical results like mode shapes and unbalance parameters for the laboratory model are presented in detail.
An Efficient Method of Vibration Diagnostics For Rotating Machinery Using a Decision Tree
Authors: Yang Bo Suk , Park Chul Hyun , Kim Ho Jong
Published: March 2007

This paper describes an efficient method to automatize vibration diagnosis for rotating machinery using a decision tree, which is applicable to vibration diagnosis expert system. Decision tree is a widely known formalism for expressing classification knowledge and has been used successfully in many diverse areas such as character recognition, medical diagnosis, and expert systems, etc. In order to build a decision tree for vibration diagnosis, we have to define classes and attributes. A set of cases based on past experiences is also needed. This training set is inducted using a result‐cause matrix newly developed in the present work instead of using a conventionally implemented cause‐result matrix. This method was applied to diagnostics for various cases taken from published work. It is found that the present method predicts causes of the abnormal vibration for test cases with high reliability.
Simulation of Flow in Turbopump Vaneless and VanedDiffusers with Fluid Injection
Authors: Ogut Ali , Pastor Diego Garcia
Published: March 2007

In future space missions by NASA there will be a need for “Space Transfer Vehicles” to perform varying orbital transfers and descents. This requires engines capable of producing different levels of thrust. To accomplish this, the turbopumps employed in these engines should efficiently provide a wide range of flow outputs. However, current fuel and oxidizer turbopumps with vaned diffusers do not perform efficiently at off‐design (low) flow rates mainly due to flow separation in the vaned diffuser.

This paper evaluates the effectiveness of boundary layer control by fluid injection
(blowing) for suppressing or eliminating the flow separation in a vaned diffuser. A 3‐D flow
model including vaneless and vaned diffusers of a liquid hydrogen (LH2) turbopump is studied using the CFD code FIDAP. The paper presents the results of the model at design and offdesign flow conditions.

The model results showed that flow separation occurs at the top or suction surface of the vaneless diffuser and at the bottom or pressure surface of the vaned diffuser at off‐design flow rates. When fluid injection was applied through the bottom surface of the vaned diffuser, the separated flow region was reduced almost entirely, resulting in an increase in pressure recovery of up to 21% with varying fluid injection rates. Results also showed that there is an optimum injection rate which is most effective in reducing or eliminating the region of flow separation.
Vibration Criteria Considered from Case Studies of ActiveMagnetic Bearing Equipped Rotating Machines
Authors: Matsushita Osami , Kanemitsu Youichi , Azuma Takao , Fukushima Yasuo
Published: March 2007

The main part of turbo machinery is conventionally supported by oil film lubricated bearings.
The rotor vibrations can be suppressed within low levels as to satisfy vibration criteria, e.g.,
ISO standards for general rotors and API 617 for process compressors. Recently, the
sophisticated advantages of the active magnetic bearing (AMB) have been increasing the
number of applications to industrial rotors. The AMB vibration control design requires
the weak support which induces inevitably large vibration amplitude, though it is normal for
AMB itself. Vibration criteria indicated by present standards are thus too strict for AMB
equipped rotors. The difference of the bearing dynamic characteristics between the oil film
lubricated bearing and the AMB compels us to prepare a new ISO standard which
recommends the acceptance of higher vibration levels for AMB operation.

In this paper, a case study was executed concerning AMB equipped LP and HP
compressors experiencing long‐term operation with no major trouble since December, 1992.
The rotating rated speed, 10900 rpm, is beyond the first bending critical speed with 5300 kW
of power. The average value of the rotor vibration was about 50 μmpp in the site operation. By reviewing the rotor design concept and field data of these AMB equipped machines, new vibration criteria are considered for a proposal of ISO standardization.
Experimental Examination of an Axial Compressor as aBasis for an Active Stall Avoidance System
Authors: Schulze Richard , Hennecke Dietmar K. , Le Thuyen , Glesner Manfred
Published: March 2007

A single‐stage subsonic compressor was examined with respect to compressor instabilities. During the inception of rotating stall, the transients of the pressure rise and mass flow were measured as well as their hysteresis. The development of the stall cell and the characteristics of the unstable operating range were determined.

Several measurement techniques and data analysis methods for the real‐time detection of unstable compressor operation and aspects of their implementation on a digital signal processor are discussed.

The results of the work are meant to serve as a basis for the design of an active stall avoidance system.
Modeling of Two‐Phase Flow through a Rotating Tube with Twin Exit Branches
Authors: Cheng Sun-Wen , Yang Wen-Jei
Published: March 2007

A numerical model is proposed to determine the dynamic behavior of single‐phase and twophase, two‐component flows through a horizontal rotating tube with identical twin exit branches. The working fluid, oil, enters the tube through a radial duct attached at one end and exits into open air through the twin radial branches, one located at midway and the other at the end of the tube. The branch‐to‐tube diameter ratio, rotational speed, and total oil flow rate are varied. It is experimentally revealed in previous study that the air cavitation occurs at lower speeds, leading to a two‐phase flow with the air‐oil ratio (void fraction) varying with the rotating speed. A unique characteristic in two‐phase flow, i.e., hysteresis, is found to exist in both oil flow rates and inlet pressure. In theoretical modeling, the governing flow equations are incorporated by empirical equations for hydraulic head losses. The predicted and measured exit oil flow rates are compared with good agreement in both the single‐phase and annular flow regimes. Only qualitative agreement is achieved in the bubbly and bubbly‐slug flow regimes. The model can be applied to improve the design and thus enhance the performance of automatic transmission lines, and the cooling efficiency of rotating machines and petroleum drilling process.