bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Evaluation Method for Random Fatigue Based on Spectrum Characteristics
Authors: Sakai Shinsuke , Okajima Satoshi , Izumi Satoshi , Kasahara Naoto
Published: May 2012

This paper shows a new design approach for random fatigue evaluation based on spectral characteristics. Fatigue damage under random loading is usually evaluated by first, decomposing random waves to stress amplitudes using the rainflow-cycle counting (RFC) method; then, evaluating fatigue damage using Palmgren–Miner’s linear summation rule. In the design process, the fluctuation of load is usually characterized through power spectral density (PSD). Therefore, the design process is expected to be generalized, if the fatigue damage is directly evaluated from the PSD together with the S-N diagram of the material. In fact, many properties related to fatigue damage, such as distribution of extreme values, can be derived theoretically from the geometrical properties of PSD. However, it is rather difficult to derive the distribution of stress amplitude counted by RFC theoretically due to its complicated procedure. In this paper, the upper bound of stress amplitude distribution is confirmed for many random waves generated by numerical simulation for many types of PSDs. Expressing the upper-bound distribution by a closed form function using PSD characteristics leads us to the direct evaluation of fatigue damage with a safety margin if the fatigue damage by a particular stress amplitude is approximated using a series expansion form. A simple procedure for approximating high-cycle fatigue damage for austenitic stainless steel and ferritic steel is proposed in this paper. Finally, a design evaluation procedure based on the fatigue-damage evaluation from PSD together with an S-N diagram is summarized.
Direct Measurement of Thermal Emission From a Fabry–Perot Cavity Resonator
Authors: Wang L. P. , Basu S. , Zhang Z. M.
Published: May 2012

There have been growing interests in selective control of thermal emission by using micro/nanostructures. The present study describes direct measurements of infrared thermal emission at elevated temperatures of an asymmetric Fabry–Perot resonator at variable angles for each polarization. The multilayered structure mainly contains a SiO2 optical cavity sandwiched between a thick (opaque) Au film and a thin Au film. Metallic adhesive and diffusion-barrier layers were deposited on a Si substrate before depositing the thick Au film. A dielectric protection layer was deposited atop the thin Au film to prevent oxidation at high temperatures. A SiC wafer was used as the reference to test the emittance measurement facility, which includes a heated sample holder, a blackbody source, mirror assembly, a polarizer, and a Fourier-transform infrared spectrometer with different detectors. The measured emittance spectra of the Fabry–Perot structure exhibit peak broadening and shifting as temperature increases; the mechanisms are elucidated by comparison with theoretical modeling.
Multiple Analytic Solutions of Heat and Mass Transfer of Magnetohydrodynamic Slip Flow for Two Types of Viscoelastic Fluids Over a Stretching Surface
Authors: Turkyilmazoglu Mustafa
Published: May 2012

This paper focuses on the magnetohydrodynamic (MHD) slip flow of an electrically conducting, viscoelastic fluid past a stretching surface. The main concern is to analytically investigate the structure of the solutions and determine the thresholds beyond which multiple solutions exist or the physically pure exponential type solution ceases to exist. In the case of the presence of multiple solutions, closed-form formulae for the boundary layer equations of the flow are presented for two classes of viscoelastic fluid, namely, the second-grade and Walter’s liquid B fluids. Heat transfer analyzes are also carried out for two general types of boundary heating processes, either by a prescribed quadratic power law surface temperature or by a prescribed quadratic power law surface heat flux. The flow field is affected by the presence of several physical parameters, whose influences on the unique/multiple solutions of velocity and temperature profiles, and Nusselt numbers are examined and discussed.
Analysis on Elastoplastic Stress Distribution in a Layered Cylindrical Vessel With Interlayer Gaps
Authors: Xu Shugen , Wang Weiqiang
Published: May 2012

In this paper, the formulae for elastoplastic stress distribution in layered cylindrical vessel layers with gaps have been provided. These formulae are based on the modified Pimshtein formulae for the elastic stress of layers. Plane strain with ideal elastoplastic model of materials is adopted. A practice example is presented to show how the formulae can be used for elastoplastic stress calculation. The hoop, radial, axial, and Von Mises equivalent stresses are obtained. The calculation result showed that the stress state of layered cylindrical vessel is more complex than that of monobloc cylindrical shell due to the interlayer gaps. The stress distribution is discontinuous. Calculation results obtained theoretically were compared to those obtained by finite element method (FEM). It shows that the results from the proposed formulae are in good agreement with finite element results.
A Risk-Informed Methodology for ASME Section XI, Appendix G
Authors: Gamble Ronald , Server William , Bishop Bruce , Palm Nathan , Heinecke Carol
Published: May 2012

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code [1], Section XI, Appendix G provides a deterministic procedure for defining Service Level A and B pressure–temperature limits for ferritic components in the reactor coolant pressure boundary. An alternative risk-informed methodology has been developed for ASME Section XI, Appendix G. This alternative methodology provides easy to use procedures to define risk-informed pressure–temperature limits for Service Level A and B events, including leak testing and reactor start-up and shut-down. Risk-informed pressure–temperature limits provide more operational flexibility, particularly for reactor pressure vessels with relatively high irradiation levels and radiation sensitive materials. This work evaluated selected plants spanning the population of pressurized water reactors (PWRs) and boiling water reactors (BWRs). The evaluation included determining appropriate material properties, reviewing operating history and system operational constraints, and performing probabilistic fracture mechanics (PFM) analyses. The analysis results were used to define risk-informed pressure–temperature relationships that comply with safety goals defined by the United States (U.S.) Nuclear Regulatory Commission (NRC). This alternative methodology will provide greater operational flexibility, especially for Service Level A and B events that may adversely affect efficient and safe plant operation, such as low-temperature-over-pressurization for PWRs and system leak testing for BWRs. Overall, application of this methodology can result in increased plant efficiency and increased plant and personnel safety.
A Contribution to the Design of Robust Profile Modifications in Spur and Helical Gears by Combining Analytical Results and Numerical Simulations
Authors: Ghribi D. , Bruyère J. , Velex Ph. , Octrue M. , Haddar M.
Published: May 2012

This paper addresses the definition of robust profile modifications in spur and helical gears. An original methodology is introduced which relies on closed-form analytical results on transmission errors combined with a gradient descent algorithm and a Gauss quadrature (GQ) based full factorial method. The results compare very well with those delivered by using classic Monte Carlo simulations with a considerable gain in computational time. The influence of the probability distribution law for the design parameters (depth and extent of modification) is analyzed along with the contribution of gear quality grade and load variation. Some optimum robust linear relief is presented which minimizes transmission error fluctuations over a broad range of loads even in the presence of significant geometrical tolerances.
Discrete Time Transfer Matrix Method for Launch Dynamics Modeling and Cosimulation of Self-Propelled Artillery System
Authors: Rong Bao , Rui Xiaoting , Tao Ling
Published: May 2012

In many industrial applications, complex mechanical systems can often be described by multibody systems (MBS) that interact with electrical, flowing, elastic structures, and other subsystems. Efficient, precise dynamic analysis for such coupled mechanical systems has become a research focus in the field of MBS dynamics. In this paper, a coupled self-propelled artillery system (SPAS) is examined as an example, and the discrete time transfer matrix method of MBS and multirate time integration algorithm are used to study the dynamics and cosimulation of coupled mechanical systems. The global error and computational stability of the proposed method are discussed. Finally, the dynamic simulation of a SPAS is given to validate the method. This method does not need the global dynamic equations and has a low-order system matrix, and, therefore, exhibits high computational efficiency. The proposed method has advantages for dynamic design of complex mechanical systems and can be extended to other coupled systems in a straightforward manner.
Visualizing Poynting vector energy flow in electric circuits
Authors: Morris Noah A. , Styer Daniel F.
Published: May 2012

According to standard Poynting vector arguments, energy in a circuit flows from the batteries to the resistors, not through the connecting wires, but through empty space between the wires. The computer simulation CircuitSurveyor helps to visualize this counterintuitive fact. The simulation also demonstrates the electric fields present near a circuit.
Jacobi elliptic functions and the complete solution to the bead on the hoop problem
Authors: Baker Thomas E. , Bill Andreas
Published: May 2012

Jacobi elliptic functions are flexible functions that appear in a variety of problems in physics and engineering. We introduce and describe important features of these functions and present a physical example from classical mechanics where they appear: a bead on a spinning hoop. We determine the complete analytical solution for the motion of a bead on the driven hoop for arbitrary initial conditions and parameter values.
The Acyl Homoserine Lactone Receptor, SdiA, of Escherichia coli and Salmonella enterica Serovar Typhimurium Does Not Respond to Indole
Authors: Sabag-Daigle Anice , Soares Jitesh A. , Smith Jenée N. , Elmasry Mohamed E. , Ahmer Brian M. M.
Published: May 2012

In this study, we tested the hypothesis that the SdiA proteins of
Escherichia coli
and
Salmonella enterica
serovar Typhimurium respond to indole. While indole was found to have effects on gene expression and biofilm formation, these effects were not
sdiA
dependent. However, high concentrations of indole did inhibit
N
-acyl-
l
-homoserine lactone (AHL) sensing by SdiA. We conclude that SdiA does not respond to indole but indole can inhibit SdiA activity in
E. coli
and
Salmonella
.
Development of a Tightly Regulatable Copper-Mediated Gene Switch System in Dermatophytes
Authors: Iwata Atsushi , Alshahni Mohamed Mahdi , Nishiyama Yayoi , Makimura Koichi , Abe Shigeru , Yamada Tsuyoshi
Published: May 2012

Targeted gene deletion is now available for molecular genetic research of dermatophytes, and the physiological roles of several genes have been elucidated. However, this method cannot be applied to essential genes, which can be potential drug targets. To overcome this limitation, we have developed a conditional gene knockdown system using a copper-responsive promoter. The promoter sequence of the copper transporter gene
CTR4
(P

CTR4

) and that of the copper efflux pump gene
CRP1
(P

CRP1

) derived from
Trichophyton rubrum
were examined for their response to copper in
Arthroderma vanbreuseghemii
. P

CTR4

was demonstrated to repress expression of a reporter gene in the presence of copper, while the activity of P

CRP1

was induced by addition of copper. Importantly, P

CTR4

regulated the gene expression more tightly. Furthermore, when P

CTR4

was applied to regulate the expression of the endogenous genes
ERG1
and
TRP5
, their conditional mutants exhibited decreased growth activity under the repressive conditions. These results suggest that the P

CTR4

-based gene regulation system represents a powerful tool for identification and characterization of a broad range of genes, including essential genes, in dermatophytes.
Influence of Cofermentation by Amylolytic Lactobacillus plantarum and Lactococcus lactis Strains on the Fermentation Process and Rheology of Sorghum Porridge
Authors: Mukisa Ivan M. , Byaruhanga Yusuf B. , Muyanja Charles M. B. K. , Aijuka Matthew , Schüller Reidar B. , Sahlstrøm Stefan , Langsrud Thor , Narvhus Judith A.
Published: May 2012

Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB,
Lactobacillus plantarum
MNC 21 and
Lactococcus lactis
MNC 24, isolated from
Obushera
, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain
Lb. plantarum
A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (
P
< 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (
G
′), loss modulus (
G
″), phase angle (δ), and complex viscosity (η*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (
P
< 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials.
The HU Protein Is Important for Apicoplast Genome Maintenance and Inheritance in Toxoplasma gondii
Authors: Reiff Sarah B. , Vaishnava Shipra , Striepen Boris
Published: May 2012

The apicoplast, a chloroplast-like organelle, is an essential cellular component of most apicomplexan parasites, including
Plasmodium
and
Toxoplasma
. The apicoplast maintains its own genome, a 35-kb DNA molecule that largely encodes proteins required for organellar transcription and translation. Interference with apicoplast genome maintenance and function is a validated target for drug therapy for malaria and toxoplasmosis. However, the many proteins required for genome maintenance and inheritance remain largely unstudied. Here we genetically characterize a nucleus-encoded homolog to the bacterial HU protein in
Toxoplasma gondii
. In bacteria, HU is a DNA-binding structural protein with fundamental roles in transcription, replication initiation, and DNA repair. Immunofluorescence assays reveal that in
T. gondii
this protein localizes to the apicoplast. We have found that the HU protein from
Toxoplasma
can successfully complement bacterial Δ
hupA
mutants, supporting a similar function. We were able to construct a genetic knockout of
HU
in
Toxoplasma
. This Δ
hu
mutant is barely viable and exhibits significant growth retardation. Upon further analysis of the mutant phenotype, we find that this mutant has a dramatically reduced apicoplast genome copy number and, furthermore, suffers defects in the segregation of the apicoplast organelle. Our findings not only show that the HU protein is important for
Toxoplasma
cell biology but also demonstrate the importance of the apicoplast genome in the biogenesis of the organelle.
Plasmid Vectors for Proteomic Analyses in Giardia: Purification of Virulence Factors and Analysis of the Proteasome
Authors: Jerlström-Hultqvist Jon , Stadelmann Britta , Birkestedt Sandra , Hellman Ulf , Svärd Staffan G.
Published: May 2012

In recent years, proteomics has come of age with the development of efficient tools for purification, identification, and characterization of gene products predicted by genome projects. The intestinal protozoan
Giardia intestinalis
can be transfected, but there is only a limited set of vectors available, and most of them are not user friendly. This work delineates the construction of a suite of cassette-based expression vectors for use in
Giardia
. Expression is provided by the strong constitutive ornithine carbamoyltransferase (OCT) promoter, and tagging is possible in both N- and C-terminal configurations. Taken together, the vectors are capable of providing protein localization and production of recombinant proteins, followed by efficient purification by a novel affinity tag combination, streptavidin binding peptide–glutathione
S
-transferase (SBP-GST). The option of removing the tags from purified proteins was provided by the inclusion of a PreScission protease site. The efficiency and feasibility of producing and purifying endogenous recombinant
Giardia
proteins with the developed vectors was demonstrated by the purification of active recombinant arginine deiminase (ADI) and OCT from stably transfected trophozoites. Moreover, we describe the tagging, purification by StrepTactin affinity chromatography, and compositional analysis by mass spectrometry of the
G. intestinalis
26S proteasome by employing the Strep II-FLAG–tandem affinity purification (SF-TAP) tag. This is the first report of efficient production and purification of recombinant proteins in and from
Giardia
, which will allow the study of specific parasite proteins and protein complexes.
Pseudomonas aeruginosa Thiol Peroxidase Protects against Hydrogen Peroxide Toxicity and Displays Atypical Patterns of Gene Regulation
Authors: Somprasong Nawarat , Jittawuttipoka Thichakorn , Duang-nkern Jintana , Romsang Adisak , Chaiyen Pimchai , Schweizer Herbert P. , Vattanaviboon Paiboon , Mongkolsuk Skorn
Published: May 2012

The
Pseudomonas aeruginosa
PAO1 thiol peroxidase homolog (Tpx) belongs to a family of enzymes implicated in the removal of toxic peroxides. We have shown the expression of
tpx
to be highly inducible with redox cycling/superoxide generators and diamide and weakly inducible with organic hydroperoxides and hydrogen peroxide (H
2
O
2
). The PAO1
tpx
pattern is unlike the patterns for other peroxide-scavenging genes in
P. aeruginosa
. Analysis of the
tpx
promoter reveals the presence of a putative IscR binding site located near the promoter. The
tpx
expression profiles in PAO1 and the
iscR
mutant, together with results from gel mobility shift assays showing that purified IscR specifically binds the
tpx
promoter, support the role of IscR as a transcriptional repressor of
tpx
that also regulates the oxidant-inducible expression of the gene. Recombinant Tpx has been purified and biochemically characterized. The enzyme catalyzes thioredoxin-dependent peroxidation and can utilize organic hydroperoxides and H
2
O
2
as substrates. The Δ
tpx
mutant demonstrates differential sensitivity to H
2
O
2
only at moderate concentrations (0.5 mM) and not at high (20 mM) concentrations, suggesting a novel protective role of
tpx
against H
2
O
2
in
P. aeruginosa
. Altogether,
P. aeruginosa tpx
is a novel member of the IscR regulon and plays a primary role in protecting the bacteria from submillimolar concentrations of H
2
O
2
.
Surface-Layer (S-Layer) Proteins Sap and EA1 Govern the Binding of the S-Layer-Associated Protein BslO at the Cell Septa of Bacillus anthracis
Authors: Kern Valerie J. , Kern Justin W. , Theriot Julie A. , Schneewind Olaf , Missiakas Dominique
Published: May 2012

The Gram-positive pathogen
Bacillus anthracis
contains 24 genes whose products harbor the structurally conserved surface-layer (S-layer) homology (SLH) domain. Proteins endowed with the SLH domain associate with the secondary cell wall polysaccharide (SCWP) following secretion. Two such proteins, Sap and EA1, have the unique ability to self-assemble into a paracrystalline layer on the surface of bacilli and form S layers. Other SLH domain proteins can also be found within the S layer and have been designated

B

acillus
S
-
l
ayer-associated protein (BSLs). While both S-layer proteins and BSLs bind the same SCWP, their deposition on the cell surface is not random. For example, BslO is targeted to septal peptidoglycan zones, where it catalyzes the separation of daughter cells. Here we show that an insertional lesion in the
sap
structural gene results in elongated chains of bacilli, as observed with a
bslO
mutant. The chain length of the
sap
mutant can be reduced by the addition of purified BslO in the culture medium. This complementation in
trans
can be explained by an increased deposition of BslO onto the surface of
sap
mutant bacilli that extends beyond chain septa. Using fluorescence microscopy, we observed that the Sap S layer does not overlap the EA1 S layer and slowly yields to the EA1 S layer in a growth-phase-dependent manner. Although present all over bacilli, Sap S-layer patches are not observed at septa. Thus, we propose that the dynamic Sap/EA1 S-layer coverage of the envelope restricts the deposition of BslO to the SCWP at septal rings.
Delineation of the Caffeine C-8 Oxidation Pathway in Pseudomonas sp. Strain CBB1 via Characterization of a New Trimethyluric Acid Monooxygenase and Genes Involved in Trimethyluric Acid Metabolism
Authors: Mohanty Sujit Kumar , Yu Chi-Li , Das Shuvendu , Louie Tai Man , Gakhar Lokesh , Subramanian Mani
Published: May 2012

The molecular basis of the ability of bacteria to live on caffeine via the C-8 oxidation pathway is unknown. The first step of this pathway, caffeine to trimethyluric acid (TMU), has been attributed to poorly characterized caffeine oxidases and a novel quinone-dependent caffeine dehydrogenase. Here, we report the detailed characterization of the second enzyme, a novel NADH-dependent trimethyluric acid monooxygenase (TmuM), a flavoprotein that catalyzes the conversion of TMU to 1,3,7-trimethyl-5-hydroxyisourate (TM-HIU). This product spontaneously decomposes to racemic 3,6,8-trimethylallantoin (TMA). TmuM prefers trimethyluric acids and, to a lesser extent, dimethyluric acids as substrates, but it exhibits no activity on uric acid. Homology models of TmuM against uric acid oxidase HpxO (which catalyzes uric acid to 5-hydroxyisourate) reveal a much bigger and hydrophobic cavity to accommodate the larger substrates. Genes involved in the caffeine C-8 oxidation pathway are located in a 25.2-kb genomic DNA fragment of CBB1, including
cdhABC
(coding for caffeine dehydrogenase) and
tmuM
(coding for TmuM). Comparison of this gene cluster to the uric acid-metabolizing gene cluster and pathway of
Klebsiella pneumoniae
revealed two major open reading frames coding for the conversion of TM-HIU to
S
-(+)-trimethylallantoin [
S
-(+)-TMA]. The first one, designated
tmuH
, codes for a putative TM-HIU hydrolase, which catalyzes the conversion of TM-HIU to 3,6,8-trimethyl-2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (TM-OHCU). The second one, designated
tmuD
, codes for a putative TM-OHCU decarboxylase which catalyzes the conversion of TM-OHCU to
S
-(+)-TMA. Based on a combination of enzymology and gene-analysis, a new degradative pathway for caffeine has been proposed via TMU, TM-HIU, TM-OHCU to
S
-(+)-TMA.
Novel Role for RNase PH in the Degradation of Structured RNA
Authors: Jain Chaitanya
Published: May 2012

Escherichia colicontains multiple 3′ to 5′ RNases, of which two, RNase PH and polynucleotide phosphorylase (PNPase), use inorganic phosphate as a nucleophile to catalyze RNA cleavage. It is known that an absence of these two enzymes causes growth defects, but the basis for these defects has remained undefined. To further an understanding of the function of these enzymes, the degradation pattern of different cellular RNAs was analyzed. It was observed that an absence of both enzymes results in the appearance of novel mRNA degradation fragments. Such fragments were also observed in strains containing mutations in RNase R and PNPase, enzymes whose collective absence is known to cause an accumulation of structured RNA fragments. Additional experiments indicated that the growth defects of strains containing RNase R and PNPase mutations were exacerbated upon RNase PH removal. Taken together, these observations suggested that RNase PH could play a role in structured RNA degradation. Biochemical experiments with RNase PH demonstrated that this enzyme digests through RNA duplexes of moderate stability. In addition, mapping and sequence analysis of an mRNA degradation fragment that accumulates in the absence of the phosphorolytic enzymes revealed the presence of an extended stem-loop motif at the 3′ end. Overall, these results indicate that RNase PH plays a novel role in the degradation of structured RNAs and provides a potential explanation for the growth defects caused by an absence of the phosphorolytic RNases.
Identification of Ata, a Multifunctional Trimeric Autotransporter of Acinetobacter baumannii
Authors: Bentancor Leticia V. , Camacho-Peiro Ana , Bozkurt-Guzel Cagla , Pier Gerald B. , Maira-Litrán Tomás
Published: May 2012

Acinetobacter baumannii
has recently emerged as a highly troublesome nosocomial pathogen, especially in patients in intensive care units and in those undergoing mechanical ventilation. We have identified a surface protein adhesin of
A. baumannii
, designated the

A
cinetobacter

t
rimeric
a
utotransporter (Ata), that contains all of the typical features of trimeric autotransporters (TA), including a long signal peptide followed by an N-terminal, surface-exposed passenger domain and a C-terminal domain encoding 4 β-strands. To demonstrate that Ata encoded a TA, we created a fusion protein in which we replaced the entire passenger domain of Ata with the epitope tag V5, which can be tracked with specific monoclonal antibodies, and demonstrated that the C-terminal 101 amino acids of Ata were capable of exporting the heterologous V5 tag to the surface of
A. baumannii
in a trimeric form. We found that Ata played a role in biofilm formation and bound to various extracellular matrix/basal membrane (ECM/BM) components, including collagen types I, III, IV, and V and laminin. Moreover, Ata mediated the adhesion of whole
A. baumannii
cells to immobilized collagen type IV and played a role in the survival of
A. baumannii
in a lethal model of systemic infection in immunocompetent mice. Taken together, these results reveal that Ata is a TA of
A. baumannii
involved in virulence, including biofilm formation, binding to ECM/BM proteins, mediating the adhesion of
A. baumannii
cells to collagen type IV, and contributing to the survival of
A. baumannii
in a mouse model of lethal infection.
Adrenal trauma: medical and surgical emergency
Authors: Untereiner Olivier , Charpentier Claire , Grignon Bruno , Welfringer Pascal , Garric Jean , Mertes Paul Michel
Published: May 2012

A 35-year-old man was admitted to hospital in a state of haemorrhagic shock after a road traffic accident. A right adrenal gland injury associated with a retroperitoneal haematoma was diagnosed by CT scan. Haemostatic surgery (without adrenal gland resection) was performed instead of angioembolisation because of an associated abdominal compartment syndrome. The outcome was favourable. The objective of this case report is to illustrate the importance of the early diagnosis of adrenal gland injuries after trauma which, though uncommon and frequently overlooked or discovered fortuitously by CT scan, can be life-threatening. Angioembolisation or surgery may be necessary in cases of uncontrolled bleeding or the development of abdominal compartmental syndrome.
Pulse oximetry screening for congenital heart defects in newborn infants: an evaluation of acceptability to mothers
Authors: Powell Rachael , Pattison Helen M , Bhoyar Abhay , Furmston Alexandra T , Middleton Lee J , Daniels Jane P , Ewer Andrew K
Published: May 2012

Background

Introducing neonatal screening procedures may not be readily accepted by parents and may increase anxiety. The acceptability of pulse oximetry screening to parents has not been previously reported.

Objective

To assess maternal acceptability of pulse oximetry screening for congenital heart defects and to identify factors predictive of participation in screening.

Design and setting

A questionnaire was completed by a cross-sectional sample of mothers whose babies were recruited into the PulseOx Study which investigated the test accuracy of pulse oximetry screening.

Participants

A total of 119 mothers of babies with false-positive (FP) results, 15 with true-positive and 679 with true-negative results following screening.

Main outcome measures

Questionnaires included measures of satisfaction with screening, anxiety, depression and perceptions of test results.

Results

Participants were predominantly satisfied with screening. The anxiety of mothers given FP results was not significantly higher than that of mothers given true-negative results (median score 32.7 vs 30.0, p=0.09). White British/Irish mothers were more likely to participate in screening, with a decline rate of 5%; other ethnic groups were more likely to decline with the largest increase in declining being for Black African mothers (21%, OR 4.6, 95% CI 3.8 to 5.5). White British mothers were also less anxious (p<0.001) and more satisfied (p<0.001) than those of other ethnicities

Conclusions

Pulse oximetry screening was acceptable to mothers and FP results were not found to increase anxiety. Factors leading to differences in participation and satisfaction across ethnic groups need to be identified so that staff can support parents appropriately.
The Physiology of the Axon Initial Segment
Authors: Bender Kevin J. , Trussell Laurence O.
Published: May 2012

The action potential generally begins in the axon initial segment (AIS), a principle confirmed by 60 years of research; however, the most recent advances have shown that a very rich biology underlies this simple observation. The AIS has a remarkably complex molecular composition, with a wide variety of ion channels and attendant mechanisms for channel localization, and may feature membrane domains each with distinct roles in excitation. Its function may be regulated in the short term through the action of neurotransmitters, in the long term through activity- and Ca2+-dependent processes. Thus, the AIS is not merely the beginning of the axon, but rather a key site in the control of neuronal excitability.
Cellular Pathways of Hereditary Spastic Paraplegia
Authors: Blackstone Craig
Published: May 2012

Human voluntary movement is controlled by the pyramidal motor system, a long CNS pathway comprising corticospinal and lower motor neurons. Hereditary spastic paraplegias (HSPs) are a large, genetically diverse group of inherited neurologic disorders characterized by a length-dependent distal axonopathy of the corticospinal tracts, resulting in lower limb spasticity and weakness. A range of studies are converging on alterations in the shaping of organelles, particularly the endoplasmic reticulum, as well as intracellular membrane trafficking and distribution as primary defects underlying the HSPs, with clear relevance for other long axonopathies affecting peripheral nerves and lower motor neurons.
Functional Consequences of Mutations in Postsynaptic Scaffolding Proteins and Relevance to Psychiatric Disorders
Authors: Ting Jonathan T. , Peça João , Feng Guoping
Published: May 2012

Functional studies on postsynaptic scaffolding proteins at excitatory synapses have revealed a plethora of important roles for synaptic structure and function. In addition, a convergence of recent in vivo functional evidence together with human genetics data strongly suggest that mutations in a variety of these postsynaptic scaffolding proteins may contribute to the etiology of diverse human psychiatric disorders such as schizophrenia, autism spectrum disorders, and obsessive-compulsive spectrum disorders. Here we review the most recent evidence for several key postsynaptic scaffolding protein families and explore how mouse genetics and human genetics have intersected to advance our knowledge concerning the contributions of these important players to complex brain function and dysfunction.
The Attention System of the Human Brain: 20 Years After
Authors: Petersen Steven E. , Posner Michael I.
Published: May 2012

Here, we update our 1990 Annual Review of Neuroscience article, “The Attention System of the Human Brain.” The framework presented in the original article has helped to integrate behavioral, systems, cellular, and molecular approaches to common problems in attention research. Our framework has been both elaborated and expanded in subsequent years. Research on orienting and executive functions has supported the addition of new networks of brain regions. Developmental studies have shown important changes in control systems between infancy and childhood. In some cases, evidence has supported the role of specific genetic variations, often in conjunction with experience, that account for some of the individual differences in the efficiency of attentional networks. The findings have led to increased understanding of aspects of pathology and to some new interventions.
Under Pressure: Cellular and Molecular Responses During Glaucoma, a Common Neurodegeneration with Axonopathy
Authors: Nickells Robert W. , Howell Gareth R. , Soto Ileana , John Simon W.M.
Published: May 2012

Glaucoma is a complex neurodegenerative disorder that is expected to affect 80 million people by the end of this decade. Retinal ganglion cells (RGCs) are the most affected cell type and progressively degenerate over the course of the disease. RGC axons exit the eye and enter the optic nerve by passing through the optic nerve head (ONH). The ONH is an important site of initial damage in glaucoma. Higher intraocular pressure (IOP) is an important risk factor for glaucoma, but the molecular links between elevated IOP and axon damage in the ONH are poorly defined. In this review and focusing primarily on the ONH, we discuss recent studies that have contributed to understanding the etiology and pathogenesis of glaucoma. We also identify areas that require further investigation and focus on mechanisms identified in other neurodegenerations that may contribute to RGC dysfunction and demise in glaucoma.
Disruption of TRPV1-mediated coupling of coronary blood flow to cardiac metabolism in diabetic mice: role of nitric oxide and BK channels
Authors: Guarini Giacinta , Ohanyan Vahagn A. , Kmetz John G. , DelloStritto Daniel J. , Thoppil Roslin J. , Thodeti Charles K. , Meszaros J. Gary , Damron Derek S. , Bratz Ian N.
Published: May 2012

We have previously shown transient receptor potential vanilloid subtype 1 (TRPV1) channel-dependent coronary function is compromised in pigs with metabolic syndrome (MetS). However, the mechanisms through which TRPV1 channels couple coronary blood flow to metabolism are not fully understood. We employed mice lacking TRPV1 [TRPV1(−/−)], db/db diabetic, and control C57BKS/J mice to determine the extent to which TRPV1 channels modulate coronary function and contribute to vascular dysfunction in diabetic cardiomyopathy. Animals were subjected to in vivo infusion of the TRPV1 agonist capsaicin to examine the hemodynamic actions of TRPV1 activation. Capsaicin (1–100 μg·kg−1·min−1) dose dependently increased coronary blood flow in control mice, which was inhibited by the TRPV1 antagonist capsazepine or the nitric oxide synthase (NOS) inhibitor N-nitro-l-arginine methyl ester (l-NAME). In addition, the capsaicin-mediated increase in blood flow was attenuated in db/db mice. TRPV1(−/−) mice exhibited no changes in coronary blood flow in response to capsaicin. Vasoreactivity studies in isolated pressurized mouse coronary microvessels revealed a capsaicin-dependent relaxation that was inhibited by the TRPV1 inhibitor SB366791 l-NAME and to the large conductance calcium-sensitive potassium channel (BK) inhibitors iberiotoxin and Penetrim A. Similar to in vivo responses, capsaicin-mediated relaxation was impaired in db/db mice compared with controls. Changes in pH (pH 7.4–6.0) relaxed coronary vessels contracted to the thromboxane mimetic U46619 in all three groups of mice; however, pH-mediated relaxation was blunted in vessels obtained from TRPV1(−/−) and db/db mice compared with controls. Western blot analysis revealed decreased myocardial TRPV1 protein expression in db/db mice compared with controls. Our data reveal TRPV1 channels mediate coupling of myocardial blood flow to cardiac metabolism via a nitric oxide-dependent, BK channel-dependent pathway that is corrupted in diabetes.
A brain leptin-renin angiotensin system interaction in the regulation of sympathetic nerve activity
Authors: Hilzendeger Aline M. , Morgan Donald A. , Brooks Leonard , Dellsperger David , Liu Xuebo , Grobe Justin L. , Rahmouni Kamal , Sigmund Curt D. , Mark Allyn L.
Published: May 2012

The sympathetic nervous system, leptin, and renin-angiotensin system (RAS) have been implicated in obesity-associated hypertension. There is increasing evidence for the presence of both leptin and angiotensin II receptors in several key brain cardiovascular and metabolic control regions. We tested the hypothesis that the brain RAS plays a facilitatory role in the sympathetic nerve responses to leptin. In rats, intracerebroventricular (ICV) administration of losartan (5 μg) selectively inhibited increases in renal and brown adipose tissue (BAT) sympathetic nerve activity (SNA) produced by leptin (10 μg ICV) but did not reduce the SNA responses to corticotrophin-releasing factor (CRF) or the melanocortin receptor agonist MTII. In mice with deletion of angiotensin II type-1a receptors (AT1aR−/−), increases in renal and BAT SNA induced by leptin (2 μg ICV) were impaired whereas SNA responses to MTII were preserved. Decreases in food intake and body weight with ICV leptin did not differ in AT1aR−/− vs. AT1aR+/+ mice. ICV leptin in rats increased AT1aR and angiotensin-converting enzyme (ACE) mRNA in the subfornical organ and AT1aR mRNA in the arcuate nucleus, suggesting leptin-induced upregulation of the brain RAS in specific brain regions. To evaluate the role of de novo production of brain angiotensin II in SNA responses to leptin, we treated rats with captopril (12.5 μg ICV). Captopril attenuated leptin effects on renal and BAT SNA. In conclusion, these studies provide evidence that the brain RAS selectively facilitates renal and BAT sympathetic nerve responses to leptin while sparing effects on food intake.
Molecular mechanisms of MMP9 overexpression and its role in emphysema pathogenesis of Smad3-deficient mice
Authors: Xu Bing , Chen Hui , Xu Wei , Zhang Wenming , Buckley Sue , Zheng Song Guo , Warburton David , Kolb Martin , Gauldie Jack , Shi Wei
Published: May 2012

Previous studies have found that inappropriate elevation of matrix metalloproteinase-9 (MMP9) expression and activity is coincident with early onset of emphysema in Smad3-null mice. Herein, we further investigated the role of increased MMP9 in emphysema pathogenesis and the related molecular regulatory mechanisms of elevated MMP9 in Smad3-null lung. Genetic blockade of MMP9 in Smad3-null mice significantly attenuated emphysema pathology but not hypoalveolarization during early postnatal lung development. Furthermore, Smad3 was found to be a transcription factor to positively regulate a protein deacetylase sirtuin 1 (SIRT1) by binding to an AP-1 site of SIRT1 promoter. A synergistic regulatory effect on SIRT1 expression was also detected between Smad3 and c-Jun. Consistently, Smad3 knockout lung at P28 had reduced SIRT1 expression, which in turn resulted in increased acetylation of histone H3 at the transcription factor activator protein 1 (AP-1), NF-κB, and Pea3 binding sites of MMP9 promoter and increased acetylation of NF-κB. In addition, increased Pea3 expression and nuclear accumulation was also detected in Smad3-null lungs at P28. Consistently, bindings of acetylated NF-κB and Pea3 to the MMP9 promoter were elevated in Smad3-null lung. We thus propose that deficiency of Smad3 causes downregulation of SIRT1 and increased Pea3 expression/nuclear accumulation, respectively. Decreased SIRT1 activity resulted in increased acetylation of histone H3 and NF-κB. Subsequently, increased bindings of transcription factors including NF-κB and Pea3 to MMP9 promoter significantly upregulate MMP9 transcription, contributing to emphysema pathogenesis.
α‐Well‐Posedness for Quasivariational Inequality Problems
Authors: Peng Jian Wen , Tang Jing
Published: May 2012

We introduce and study the concepts of α‐well‐posedness and L‐α‐well‐posedness for quasivariational inequality problems having a unique solution and the concepts of α‐well‐posedness in the generalized sense and L‐α‐well‐posedness in the generalized sense
for quasivariational inequality problems having more than one solution. We present some
necessary and/or sufficient conditions for the various kinds of well‐posedness to occur. Our
results generalize and strengthen previously known results for quasivariational inequality
problems.
New Pathophysiological Aspects of Growth and Prevention of Kidney Stones
Authors: Baumann J. M. , Affolter B.
Published: May 2012

Kidney stones probably grow during crystalluria by crystal sedimentation and aggregation (AGN) on stone surfaces. This process has to occur within urinary transit time (UT) through the kidney before crystals are washed out by diuresis. To get more information, we studied by spectrophotometry the formation and AGN of Ca oxalate (Ca Ox) crystals which were directly produced in urine of 30 stone patients and 30 controls by an oxalate (Ox) titration. Some tests were also performed after removing urinary macromolecules (UMs) by ultrafiltration. To induce rapid crystallization, high Ox additions (0.5–0.8 mM) were necessary. The most important finding was retardation of crystal AGN by UM. In urine of 63% of controls but only 33% of patients, no AGN was observed during an observation of 60 minutes (P<0.05). Also growth and sedimentation rate of crystals were significantly reduced by UM. For stone metaphylaxis, especially for posttreatment residuals, avoiding dietary Ox excesses to prevent crystal formation in the kidney and increasing diuresis to wash out crystals before they aggregate are recommended.
Positive Periodic Solutions for First‐Order Neutral Functional Differential Equations with Periodic Delays
Authors: Liu Zeqing , Li Xin , Kang Shin Min , Kwun Young Chel
Published: May 2012

In this paper, two classes of first‐order neutral functional differential equations with periodic delays are considered. Some results on the existence of positive periodic solutions for the equations are obtained by using the Krasnoselskii fixed point theorem. Four examples are included to illustrate our results.
Cushing’s Syndrome due to Ectopic ACTH from Bronchial Carcinoid: A Case Report and Review
Authors: Kenchaiah Manohara , Hyer Steve
Published: May 2012

Despite advances in analytic and imaging techniques, the syndrome of ectopic adrenocorticotrophic hormone (ACTH) secretion from a tumour resulting in Cushing’s syndrome continues to pose difficult diagnostic and therapeutic challenges. Dynamic testing may be equivocal and radiology indeterminate. We report a patient presenting with Cushing’s syndrome associated with ectopic ACTH secretion from a bronchial carcinoid whose management presented diagnostic and therapeutic challenges.
Cycling Performance of Nanocrystalline LiMn2O4 Thin Films via Electrophoresis
Authors: Parvathy S. , Ranjusha R. , Sujith K. , Subramanian K. R. V. , Sivakumar N. , Nair Shantikumar V. , Balakrishnan Avinash
Published: May 2012

The present study demonstrates a novel approach by which titanium foils coated with LiMn2O4 nanocrystals can be processed into a high‐surface‐area electrode for rechargeable batteries. A detailed study has been performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes impact the cyclic and capacity behavior. These nanocrystals were synthesized by in situ sintering and exhibited a uniform size of ~55 nm. A direct deposition technique based on electrophoresis is employed to coat LiMn2O4 nanocrystals onto titanium substrates. From the analysis of the relevant electrochemical parameters, an intrinsic correlation between the cyclability and particle size has been deduced and explained in accordance with the Li intercalation/deintercalation process. Depending on the particle size incorporated on these electrodes, it is seen that in terms of capacitance fading, for nanoparticles cyclability is better than their micron‐sized counterparts. It has been shown that electrodes based on such nanocrystalline thin film system can allow significant room for improvement in the cyclic performance at the electrode/electrolyte interface.
Generalist Bee Species on Brazilian Bee-Plant Interaction Networks
Authors: Kleinert Astrid de Matos Peixoto , Giannini Tereza Cristina
Published: May 2012

Determining bee and plant interactions has an important role on understanding general biology of bee species as well as the potential pollinating relationship between them. Bee surveys have been conducted in Brazil since the end of the 1960s. Most of them applied standardized methods and had identified the plant species where the bees were collected. To analyze the most generalist bees on Brazilian surveys, we built a matrix of bee-plant interactions. We estimated the most generalist bees determining the three bee species of each surveyed locality that presented the highest number of interactions. We found 47 localities and 39 species of bees. Most of them belong to Apidae (31 species) and Halictidae (6) families and to Meliponini (14) and Xylocopini (6) tribes. However, most of the surveys presentedApis melliferaand/orTrigona spinipesas the most generalist species.Apis melliferais an exotic bee species andTrigona spinipes, a native species, is also widespread and presents broad diet breath and high number of individuals per colony.
Optimizing Cooperative Cognitive Radio Networks with Opportunistic Access
Authors: Zafar Ammar , Alouini Mohamed-Slim , Chen Yunfei , Radaydeh Redha M.
Published: May 2012

Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources.