bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation between students’ problem-solving performance and representational format
Authors: Meltzer David E.
Published: April 2005

An analysis is presented of data on students’ problem-solving performance on similar problems posed in diverse representations. Five years of classroom data on 400 students collected in a second-semester algebra-based general physics course are presented. Two very similar Newton’s third-law questions, one posed in a verbal representation and one in a diagrammatic representation using vector diagrams, were given to students at the beginning of the course. The proportion of correct responses on the verbal question was consistently higher than on the diagrammatic question, and the pattern of incorrect responses on the two questions also differed consistently. Two additional four-question quizzes were given to students during the semester; each quiz had four very similar questions posed in the four representations: verbal, diagrammatic, mathematical/symbolic, and graphical. In general, the error rates for the four representations were very similar, but there was substantial evidence that females had a slightly higher error rate on the graphical questions relative to the other representations, whereas the evidence for male students was more ambiguous. There also was evidence that females had higher error rates on circuit-diagram problems in comparison with males, although both males and females had received identical instruction .
Human Immunodeficiency Virus Type 1 Inhibits DNA Damage-Triggered Apoptosis by a Nef-Independent Mechanism
Authors: Schindler Michael , Münch Jan , Kirchhoff Frank
Published: April 2005

It is controversial whether the accessory human immunodeficiency virus type 1 (HIV-1) Nef protein inhibits or enhances apoptosis. To address this issue, we investigated the effect of Nef on programmed cell death with vectors or proviral HIV-1 constructs coexpressing Nef and green fluorescent protein from single bicistronic RNAs. This approach allows us to readily identify transfected or infected cells and to correlate cell death directly with Nef expression levels. We demonstrate that Nef does not significantly affect apoptosis in transfected or HIV-1-infected Jurkat T cells or primary human peripheral blood mononuclear cells. Unexpectedly, however, both
nef
+
and
nef
-defective HIV-1 infection blocked apoptosis in cells treated with UV light or etoposide but not cell death induced by CD95 antibody, TRAIL, Ly294002, or serum starvation. Our results show that HIV-1 infection inhibits DNA damage-induced but not death receptor-dependent cell death by a Nef-independent mechanism.
Modulation of the Cell Growth Regulator mTOR by Epstein-Barr Virus-Encoded LMP2A
Authors: Moody Cary A. , Scott Rona S. , Amirghahari Nazanin , Nathan Cherie-Ann , Young Lawrence S. , Dawson Chris W. , Sixbey John W.
Published: April 2005

Control of translation initiation is one means by which cells regulate growth and proliferation, with components of the protein-synthesizing machinery having oncogenic potential. Expression of latency protein LMP2A by the human tumor virus Epstein-Barr virus (EBV) activates phosphatidylinositol 3-kinase/Akt located upstream of an essential mediator of growth signals, mTOR (mammalian target of rapamycin). We show that mTOR is activated by expression of LMP2A in carcinoma cells, leading to wortmannin- and rapamycin-sensitive inhibition of the negative regulator of translation, eukaryotic initiation factor 4E-binding protein 1, and increased c-Myc protein translation. Intervention by this DNA tumor virus in cellular translational controls is likely to be an integral component of EBV tumorigenesis.
The Transcriptional Transactivation Function of HBx Protein Is Important for Its Augmentation Role in Hepatitis B Virus Replication
Authors: Tang Hong , Delgermaa Luvsanjav , Huang Feijun , Oishi Naoki , Liu Li , He Fang , Zhao Liansan , Murakami Seishi
Published: April 2005

The role and functional domain of hepatitis B virus (HBV) X protein (HBx) in regulating HBV transcription and replication were investigated with a transient transfection system in the human hepatoma cell line HepG2 using wild-type or HBx-minus HBV genome constructs and a series of deletion or mutation HBx expression plasmids. We show here that HBx has augmentation effects on HBV transcription and replication as a HBV mutant genome with defective X gene led to decreased levels of 3.5-kb HBV RNA and HBV replication intermediates and that these decreases can be restored by either transient ectopic expression of HBx or a stable HBx expression cell line. The C-terminal two-thirds (amino acids [aa] 51 to 154), which contain the transactivation domain, is required for this function of HBx; the N-terminal one-third (aa 1 to 50) is not required. Using the alanine scanning mutagenesis strategy, we demonstrated that the regions between aa 52 to 65 and 88 to 154 are important for the augmentation function of HBx in HBV replication. By the luciferase reporter gene analysis, we found that the transactivation and coactivation activities of HBx coincide well with its augmentation function in HBV transcription and replication. These results suggest that HBx has an important role in stimulating HBV transcription and replication and that the transcriptional transactivation function of HBx may be critical for its augmentation effect on HBV replication.
CMB ANISOTROPIES REVEAL QUANTIZED GRAVITY
Authors: HAMADA KEN-JI , YUKAWA TETSUYUKI
Published: April 2005

A novel primordial spectrum with a dynamical scale of quantum gravity origin is proposed to explain the sharp fall off of the angular power spectra at low multipoles in the COBE and WMAP observations. The spectrum is derived from quantum fluctuations of the scalar curvature in a renormalizable model of induced gravity. This model describes the very early universe by the conformal field fluctuating about an inflationary background with the expansion time constant of order of the Planck mass.
ELLIPTICITY OF LARGE SPOTS IN CMB ANISOTROPY MAPS
Authors: GURZADYAN V. G. , ADE P. A. R. , de BERNARDIS P. , BIANCO C. L. , BOCK J. J. , BOSCALERI A. , CRILL B. P. , DE TROIA G. , HIVON E. , HRISTOV V. V. , KASHIN A. L. , KULOGHLIAN H. , MASI S. , MAUSKOPF P. D. , MONTROY T. , NATOLI P. , PASCALE E. , PIACENTINI F. , POLENTA G. , YEGORIAN G.
Published: April 2005

We have measured the ellipticity of several degree scale anisotropies in the BOOMERanG maps of the Cosmic Microwave Background (CMB) at 150 GHz. The average ellipticity is around 2.6–2.7. The biases of the estimator of the ellipticity and for the noise are small in this case. Large spot elongation had been detected also for COBE-DMR and WMAP maps. If this effect is due to geodesic mixing, it would indicate a non-precisely zero curvature of the Universe which is among the discussed reasons of the WMAP low multipole anomaly.
QUANTUM PHASES IN PARTIALLY FILLED LANDAU LEVELS
Authors: GOERBIG M. O. , LEDERER P. , SMITH C. MORAIS
Published: April 2005

We compare the energies of different electron solids, such as bubble crystals with triangular and square symmetry and stripe phases, to those of correlated quantum liquids in partially filled intermediate Landau levels. Multiple transitions between these phases when varying the filling of the top-most partially filled Landau level explain the observed reentrance of the integer quantum Hall effect. The phase transitions are identified as first-order. This leads to a variety of measurable phenomena such as the phase co-existence between a Wigner crystal and a two-electron bubble phase in a Landau-level filling-factor range 4.15≲ν≲4.26, which has recently been observed in transport measurements under micro-wave irradiation.
ELECTRON-VORTEX INTERACTION IN A QUANTUM DOT
Authors: TAVERNIER M. B. , ANISIMOVAS E. , PEETERS F. M.
Published: April 2005

Small numbers N<5 of two-dimensional Coulomb-interacting electrons trapped in a parabolic potential placed in a perpendicular magnetic field are investigated. The reduced wave function of this system, which is obtained by fixing the positions of N-1 electrons, exhibits strong correlations between the electrons and the zeros. These zeros are often called vortices. An exact-diagonalization scheme is used to obtain the wave functions and the results are compared with results obtained from the recently proposed rotating electron molecule (REM) theory. We find that the vortices gather around the fixed electrons and repel each other, which is to a much lesser extend so for the REM results.
HOLE MAXIMUM DENSITY DROPLETS OF A BELL SHAPE ANTIDOT POTENTIAL IN STRONG MAGNETIC FIELDS
Authors: YANG S.-R. ERIC , HWANG N. Y. , SIM H.-S. , YI HANGMO
Published: April 2005

We study electron antidots using a Hartree-Fock approach and an electron-hole transformation that maps the electron antidot into a quantum dot with finite number of holes. We investigate hole maximum density droplets of a bell shape antidot potential in the integer quantum Hall regime with the filling factor two. Here we give the reasons for why a bell shape antidot potential can lead to spin flip transitions, which can cause the Kondo effect. We identify maximum density droplet states corresponding to the spin states of the Anderson impurity that describe the Kondo effect of the antidot.
TRIPLET BIEXCITON TRANSITION UNDER HIGH MAGNETIC FIELD IN (Cd,Mn)Te/CdTe/(Cd,Mg)Te ASYMMETRIC QUANTUM WELLS
Authors: MINO HIROFUMI , KOBAYASHI AYUMU , TAKEYAMA SHOJIRO , KARCZEWSKI GRZEGOSZ , WOJTOWICZ TOMASZ , KOSSUT JACEK
Published: April 2005

Biexciton spin states in a CdMnTe / CdTe / CdMgTe single quantum well have been investigated by means of the time-integrated and the spectrally-resolved four-wave mixing measurements in magnetic fields. Applying magnetic field in a Faraday geometry, the four-wave mixing signal showed a beat like structure at an early delay-time region with a co-circular (σ+,σ+) configuration. The spectrally-resolved four-wave mixing signals indicated an additional transition appeared at 1 meV higher energy side of the exciton resonance. These results were explained well by a magnetic field induced triplet biexciton transition.
MAGNETOOPTICAL EXPERIMENTS USING THE EXPLOSIVE DRIVEN FLUX COMPRESSION UP TO 1000T
Authors: HANSEL STEFAN , TRAN-ANH TUAN , KIRSTE ALEXANDER , PUHLMANN NIKOLAI , VON ORTENBERG MICHAEL , TATSENKO OLGA M. , PLATONOV VADIM V. , MOISEENKO ALEXANDER N. , SELEMIR VIKTOR D.
Published: April 2005

We discuss three recent magnetooptical experiments using the explosive driven flux-compression technique that have been performed in cooperation of the Berlinian with the Russian group of VNIIEF, Sarov. We present an overview on the experimental techniques touching the frontiers of physics as well as a detailed discussion of the results obtained on the semiconducting materials GaN , GaAs and HgSe . Special emphasis will be laid on the interpretation in context with theoretical predictions and analysis that go beyond the ordinary k•p-formalism but are also valid in the limit of the HOFSTADTER butterfly.
INTER-LANDAU-LEVEL TRANSITIONS AND ULTRAFAST DYNAMICS OF 2D MAGNETOEXCITONS
Authors: SHAHBAZYAN TIGRAN V. , FROMER NEIL A. , CHEMLA DANIEL S.
Published: April 2005

We study the role of many-body correlations in the ultrafast dynamics of quantum well magnetoexcitons. In linear response, inter-Landau level transitions are suppressed if magnetic field is stronger than magnetoexciton binding energy. However, in nonlinear response, two-electron Auger processes remain unsuppressed even at very strong field. We show that Auger scattering plays a dominant role in the coherent exciton dynamics in strong magnetic field. We perform numerical calculations of four-wave-mixing (FWM) polarization which incorporate Auger processes nonperturbatively, and find a strong amplitude enhancement of the FWM signal accompanied with polarization oscillations at negative time delays. We identify these oscillations as quantum beats between dark two-exciton states related to each other via Auger processes.
AN EVALUATION OF ORGANISATIONAL GROUNDWORK AND LEARNING OBJECTIVES FOR NEW PRODUCT DEVELOPMENT
Authors: OWENS JONATHAN
Published: April 2005

This paper discusses New Product Development (NPD) Process and the perception required for effective NPD Learning (NPDL). A model of learning for NPD organisations is presented and the necessity to assess progression towards learning objectives at the individual, job and organisation level is shown. Three aspects of organisational groundwork are identified and discussed. These include developing the NPD process, implementing the NPD strategy and allocating resources for NPD and NPDL. Ten sets of learning objectives are identified and discussed. These are organisational analysis, barrier demolition, team working, flexible problem solving, use of advanced support tools, facilitating communication, maintaining communication, decision making, assessment of the NPD process and NPDL, and NPD risk analysis. It is proposed that adopting both an organisational needs analysis and individual needs analyses can support the development of NPD organisations. These analyses will identify the groundwork that should be undertaken by the organisation and the initial learning objectives for the individuals. The progression of NPD through the NPD process can then be assessed and implemented sufficiently.
SUMOMO: A PROTEIN SURFACE MOTIF MINING MODULE
Authors: SHRESTHA NRIPENDRA L. , KAWAGUCHI YOUHEI , OHKAWA TAKENAO
Published: April 2005

Protein surface motifs, which can be defined as commonly appearing patterns of shape and physical properties in protein molecular surfaces, can be considered "possible active sites".

We have developed a system for mining surface motifs: SUMOMO which consists of two phases: surface motif extraction and surface motif filtering. In the extraction phase, a given set of protein molecular surface data is divided into small surfaces called unit surfaces. After extracting several common unit surfaces as candidate motifs, they are repetitively merged into surface motifs. However, a large amount of surface motifs is extracted in this phase, making it difficult to distinguish whether the extracted motifs are significant to be considered active sites. Since active sites from proteins with a particular function have similar shape and physical properties, proteins can be classified based on similarity among local surfaces. Thus, in the filtering phase, local surfaces extracted from proteins of the same group are considered significant motifs, and the rest are filtered out.

The proposed method was applied to discover surface motifs from 15 proteins belonging to four function groups. Motifs corresponding to all 4 known functional sites were recognised.
Indinavir alters regulators of protein anabolism and catabolism in skeletal muscle
Authors: Hong-Brown Ly Q. , Pruznak Anne M. , Frost Robert A. , Vary Thomas C. , Lang Charles H.
Published: April 2005

The HIV protease inhibitor indinavir adversely impairs carbohydrate and lipid metabolism, whereas its influence on protein metabolism under in vivo conditions remains unknown. The present study tested the hypothesis that indinavir also decreases basal protein synthesis and impairs the anabolic response to insulin in skeletal muscle. Indinavir was infused intravenously for 4 h into conscious rats, at which time the homeostasis model assessment of insulin resistance was increased. Indinavir decreased muscle protein synthesis by 30%, and this reduction was due to impaired translational efficiency. To identify potential mechanisms responsible for regulating mRNA translation, several eukaryotic initiation factors (eIFs) were examined. Under basal fasted conditions, there was a redistribution of eIF4E from the active eIF4E·eIF4G complex to the inactive eIF4E·4E-BP1 complex, and this change was associated with a marked decrease in the phosphorylation of 4E-BP1 in muscle. Likewise, indinavir decreased constitutive phosphorylation of eIF4G and mTOR in muscle, but not S6K1 or the ribosomal protein S6. In contrast, the ability of a maximally stimulating dose of insulin to increase the phosphorylation of PKB, 4E-BP1, S6K1, or mTOR was not altered 20 min after intravenous injection. Indinavir increased mRNA expression of the ubiquitin ligase MuRF1, but the plasma concentration of 3-methylhistidine remained unaltered. These indinavir-induced changes were associated with a marked reduction in the plasma testosterone concentration but were independent of changes in plasma levels of IGF-I, corticosterone, TNF-α, or IL-6. In conclusion, indinavir acutely impairs basal protein synthesis and translation initiation in skeletal muscle but, in contrast to muscle glucose uptake, does not impair insulin-stimulated signaling of protein synthetic pathways.
Effects of Rho kinase inhibition on cerebral artery myogenic tone and reactivity
Authors: Gokina Natalia I. , Park Kristen M. , McElroy-Yaggy Keara , Osol George
Published: April 2005

Several recent studies have implicated the RhoA-Rho kinase pathway in arterial myogenic behavior. The goal of this study was to determine the effects of Rho kinase inhibition (Y-27632) on cerebral artery calcium and diameter responses as a function of transmural pressure. Excised segments of rat posterior cerebral arteries (100–200 μm) were cannulated and pressurized in an arteriograph at 37°C. Increasing pressure from 10 to 60 mmHg triggered an elevation of cytosolic calcium concentration ([Ca2+]i) from 113 ± 9 to 199 ± 12 nM and development of myogenic tone. Further elevation of pressure to 120 mmHg induced only a minor additional increase in [Ca2+]iand constriction. Y-27632 (0.3–10 μM) inhibited myogenic tone in a concentration-dependent manner at 60 and 120 mmHg with comparable efficacy; conversely, sensitivity was decreased at 120 vs. 60 mmHg (50% inhibitory concentration: 2.5 ± 0.3 vs. 1.4 ± 0.1 μM; P < 0.05). Dilation was accompanied by further increases in [Ca2+]iand an enhancement of Ca2+oscillatory activity. Y-27632 also effectively dilated the vessels permeabilized with α-toxin in a concentration-dependent manner. However, dilator effects of Y-27632 at low concentrations were larger at 60 vs. 100 mmHg. In summary, the results support a significant role for RhoA-Rho kinase pathway in cerebral artery mechanotransduction of pressure into sustained vasoconstriction (myogenic tone and reactivity) via mechanisms that augment smooth muscle calcium sensitivity. Potential downstream events may involve inhibition of myosin phosphatase and/or stimulation of actin polymerization, both of which are associated with increased smooth muscle force production.
Mechanical signal transduction in skeletal muscle growth and adaptation
Authors: Tidball James G.
Published: April 2005

The adaptability of skeletal muscle to changes in the mechanical environment has been well characterized at the tissue and system levels, but the mechanisms through which mechanical signals are transduced to chemical signals that influence muscle growth and metabolism remain largely unidentified. However, several findings have suggested that mechanical signal transduction in muscle may occur through signaling pathways that are shared with insulin-like growth factor (IGF)-I. The involvement of IGF-I-mediated signaling for mechanical signal transduction in muscle was originally suggested by the observations that muscle releases IGF-I on mechanical stimulation, that IGF-I is a potent agent for promoting muscle growth and affecting phenotype, and that IGF-I can function as an autocrine hormone in muscle. Accumulating evidence shows that at least two signaling pathways downstream of IGF-I binding can influence muscle growth and adaptation. Signaling via the calcineurin/nuclear factor of activated T-cell pathway has been shown to have a powerful influence on promoting the slow/type I phenotype in muscle but can also increase muscle mass. Neural stimulation of muscle can activate this pathway, although whether neural activation of the pathway can occur independent of mechanical activation or independent of IGF-I-mediated signaling remains to be explored. Signaling via the Akt/mammalian target of rapamycin pathway can also increase muscle growth, and recent findings show that activation of this pathway can occur as a response to mechanical stimulation applied directly to muscle cells, independent of signals derived from other cells. In addition, mechanical activation of mammalian target of rapamycin, Akt, and other downstream signals is apparently independent of autocrine factors, which suggests that activation of the mechanical pathway occurs independent of muscle-mediated IGF-I release.
Streptococcus sanguis-induced platelet activation involves two waves of tyrosine phosphorylation mediated by FcγRIIA and αIIbβ3
Authors: Pampolina Caroline , McNicol Archibald
Published: April 2005

The low-affinity IgG receptor, FcγRIIA, has been implicated in Streptococcus sanguis-induced platelet aggregation. Therefore, it is likely that signal transduction is at least partly mediated by FcγRIIA activation and a tyrosine kinase-dependent pathway. In this study the signal transduction mechanisms associated with platelet activation in response to the oral bacterium, S. sanguis were characterised. In the presence of IgG, S. sanguis strain 2017–78 caused the tyrosine phosphorylation of FcγRIIA 30s following stimulation, which led to the phosphorylation of Syk, LAT, and PLCγ2. These early events were dependent on Src family kinases but independent of either TxA2 or the engagement of the αIIbβ3 integrin. During the lag phase prior to platelet aggregation, FcγRIIA, Syk, LAT, and PLCγ2 were each dephosphorylated, but were re-phosphorylated as aggregation occurred. Platelet stimulation by 2017–78 also induced the tyrosine phosphorylation of PECAM-1, an ITIM-containing receptor that recruits protein tyrosine phosphatases. PECAM-1 co-precipitated with the protein tyrosine phosphatase SHP-1 in the lag phase. SHP-1 was also maximally tyrosine phosphorylated during this phase, suggesting a possible role for SHP-1 in the observed dephosphorylation events. As aggregation occurred, SHP-1 was dephosphorylated, while FcγRIIA, Syk, LAT, and PLCγ2 were rephosphorylated in an RGDS-sensitive, and therefore αIIbβ3-dependent, manner. Additionally, TxA2 release, 5-hydro-xytryptamine secretion and phosphatidic acid formation were all blocked by RGDS. Aspirin also abolished these events, but only partially inhibited αIIbβ3-mediated re-phosphorylation. Therefore, S.sanguis-bound IgG cross links FcγRIIA and initiates a signaling pathway that is down-regulated by PECAM-1-bound SHP-1. Subsequent engagement of αIIbβ3 leads to SHP-1 dephosphorylation permiting a second wave of signaling leading to TxA2 release and consequent platelet aggregation.
Epidermal growth factor modulates prostate cancer cell invasiveness regulating urokinase-type plasminogen activator activity
Authors: Angelucci Adriano , Gravina Giovanni , Biordi Leda , Millimaggi Danilo , Muzi Paola , Vicentini Carlo , Bologna Mauro , Festuccia Claudio
Published: April 2005

Urokinase-type plasminogen activator receptor (uPAR) and Epidermal Growth Factor Receptor (EGFR) are ubiquitous receptors involved in the control of a variety of cellular processes frequently found altered in cancer cells. The EGFR has been recently described to play a transduction role of uPAR stimuli, mediating uPA-induced proliferation in highly malignant cells that overexpress uPAR. We compared the uPA production, the presence of uPAR, AR, EGFR and Her2 with the chemotaxis and the Matrigel invasion in ten human PCa cell lines and observed that: (1) the levels of Her2, but not of EGFR, as well as the uPA secretion, cell motility and Matrigel invasion were statistically higher in AR negative than in AR positive PCa cells; (2) the uPA secretion and uPAR expression were positively related to Matri-gel invasion; (3) the EGF was able to stimulate chemotaxis and Matrigel invasion in a dose-dependent manner; (4) the EGF-induced cell migration was statistically higher in AR negative than in AR positive cells with a similar increase with respect to basal value (about 2.6 fold); (5) the Matrigel invasion was statistically higher in AR negative than in AR positive PCa cells also if the increment of Matrigel invasion after EGF treatment was statis-
tically higher in AR positive respect to AR negative cells; (6) the EGF induced uPA secretion and its membrane uptake through the increment of uPAR; and (7) these effects were blocked by EGFR/Her2 tyrosine kinase inhibitors with IC50 lower than those needed to inhibit cell proliferation and required PI3K/Akt,
MAPK and PI-PLC activities as verified by inhibition experiments. These enzymatic activities were regulated in different manners in PTEN positive and negative cells. In fact, the inhibition of PI3K blocked the EGF-induced invasiveness in PTEN positive cells but not in PTEN negative cells, in which PI3K activity was not influenced by EGFR/Her2 activation, whereas the inhibition of MAPK was able to block the invasive phenomena in both cell types. Taken together, our data suggest that the blockade of EGFR could attenuate the invasive potential of PCa cells. In addition, considering that the EGFR expression is related to higher Gleason grade of PCa and that EGFR levels are increased after anti androgenic therapy, this therapeutic approach could slow down the metastasis formation which represents the most dramatic event of PCa progression.
Effect of oral contraceptives on the anticoagulant activity of protein S in plasma
Authors: Koenen Rory , Thomassen Christella , Tans Guido , Rosing Jan , Hackeng Tilman
Published: April 2005

We determined anticoagulant parameters that depend on protein S function in plasma, i.e.the APC-independent anticoagulant activity of protein S (expressed as pSR) and APC resistance determined with thrombin generation-based tests (expressed as APCsr) as well as plasma levels of total and free protein S and prothrombin in men, women not using oral contraceptives (OC), and in women using second or third generation OC. Thrombin generation in the APC resistance assays was initiated either with factor Xa (Xa-APCsr) or tissue factor (TF-APCsr). The APC-independent anticoagulant activity of protein S was highest in men (pSR=1.69) and gradually decreased from women not using OC (pSR=1.49) via women using second generation (pSR=1.35) to women using third generation OC (pSR=1.27). The pSR correlated inversely with nAPCsr determined with the tissue factor-based APC resistance test (TF-APCsr) but not with nAPCsr determined with the factor Xa-based assay (Xa-APCsr). Multiple linear regression analysis in which sex, OC use, and protein S and prothrombin levels were included as independent variables and the pSR, TF-APCsr or Xa-APCsr as dependent variables indicated that plasma protein S levels poorly predict the pSR and the TF-APCsr, but are the main determinant of the Xa-APCsr. This indicates that OC use alters the expression of protein S activity. This phenomenon can be caused by differences in modulation of the activity of protein S by other plasma proteins that change during OC use or by OC-induced changes in the protein S molecule that impair its anticoagulant activity. Functional impairment of protein S as a result of hormonal influence may, at least in part, contribute to the thrombotic risk of OC users.
The Antioxidant Edaravone Attenuates Pressure Overload–Induced Left Ventricular Hypertrophy
Authors: Tsujimoto Ikuko , Hikoso Shungo , Yamaguchi Osamu , Kashiwase Kazunori , Nakai Atsuko , Takeda Toshihiro , Watanabe Tetsuya , Taniike Masayuki , Matsumura Yasushi , Nishida Kazuhiko , Hori Masatsugu , Kogo Mikihiko , Otsu Kinya
Published: April 2005

The free radical scavenger 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone) is used to treat patients with ischemic brain damage. We and others reported previously that in vitro and in vivo reactive oxygen species (ROS) act as second messengers to develop cardiac hypertrophy. In this study, we used an in vivo murine model of pressure overload–induced cardiac hypertrophy to examine the effects of edaravone on left ventricular hypertrophy. The animals were subjected to the transverse thoracic aorta constriction, and edaravone (10 mg/kg) was infused intraperitoneally twice daily. Seven days after the operation, we observed a significant increase in ROS production in hearts, which was eliminated by the treatment with edaravone. Pressure-overloaded hearts showed a significant increase in left ventricular weight/body weight ratio and the expression level of atrial natriuretic factor mRNA, which were attenuated by edaravone. It also reduced perivascular and intermuscular fibrosis and inhibited pressure overload–induced activation of apoptosis signal-regulating kinase 1 (ASK1) and its downstream kinases of c-Jun N-terminal protein kinase and p38 mitogen-activated protein kinase. Edaravone attenuated the hypertrophic response even when the treatment was started after the onset of cardiac hypertrophic response. These findings indicate that edaravone significantly attenuates pressure overload–induced cardiac hypertrophy mediated through its antioxidative function and subsequent inhibition of ASK1 signaling pathway.
Hydration Status in College Football Players during Consecutive Days of Twice-a-Day Preseason Practices
Authors: Godek Sandra Fowkes , Godek Joseph J. , Bartolozzi Arthur R.
Published: April 2005

Background

Football players lose 3.5 to 5 kg of body weight during preseason practices because of heavy sweating. This fluid may be difficult to replace when practices occur 2 times per day on consecutive days.

Hypothesis

Football players are hypohydrated during twice-a-day preseason training in a hot, humid environment.

Study Design

Descriptive laboratory study

Methods

In 10 college football players, body weight was measured, and blood and urine samples were obtained before and after practices on days 2 through 8 of preseason training. Baseline samples were obtained when subjects were euhydrated. Blood samples were used to calculate plasma volume changes. Urine samples were analyzed for specific gravity, sodium, and potassium. Sweat rate was calculated. Core temperature was monitored during half- and full-padded practices.

Results

Mean wet bulb temperatures were 23.3°C during morning practices and 23.7°C during afternoon practices. Plasma volume was below baseline on day 2 and expanded by day 6. Urine specific gravity was higher than baseline for 12 of 20 measurements over the 8 days. It was 1.0175 ± 0.006 at baseline but subsequently ranged from 1.0214 ± 0.007 to 1.0321 ± 0.004. Mean daily urine sodium dropped from baseline to day 2 (194 ± 43 vs 43 ± 38 mmol × L-1), remaining lower on days 3, 4, and 6 (40 ± 39, 39 ± 39, and 68 ± 40 mmol × L-1, respectively). Urine potassium was lower on days 6 and 8 compared with baseline and day 3. Body weight was below baseline before and after both daily practices. Core temperature was higher in full pads; sweat rate and body weight loss were not different between half and full pads.

Conclusion

Body weight, plasma volume, urine specific gravity, and urine sodium indicate that football players become dehydrated by day 2 of preseason training. Urine sodium increased to near baseline by day 8; urine specific gravity was elevated.

Clinical Relevance

Football players struggle to maintain euhydration during preseason twice-a-day sessions.
Snowboarder's Talus Fracture
Authors: Valderrabano Victor , Perren Thomas , Ryf Christian , Rillmann Paavo , Hintermann Beat
Published: April 2005

Background

Fracture of the lateral process of the talus is a typical snowboarding injury. Basic data are limited, particularly with respect to treatment and outcome.

Hypothesis

As the axial-loaded dorsiflexed foot becomes externally rotated and/or everted, fracture of the lateral process of the talus occurs. Primary surgical treatment may improve the outcome of this injury, reducing the risk of secondary subtalar joint osteoarthritis.

Study Design

Cohort study; Level of evidence, 2.

Methods

We recorded details of the treatment and evaluation of 20 patients (8 female and 12 male; age at trauma, 29 years [range, 17-48 years]) who sustained a lateral process of the talus fracture while snowboarding. The injury pathomechanism was documented. The patients were treated either nonsurgically or surgically based on a fracture-type treatment algorithm. The evaluation at most recent follow-up (mean, 42 months [range, 26-53 months]) included clinical and functional examination, follow-up of sport activity, and radiological assessment (radiograph, computed tomography scan).

Results

The injury mechanism included axial impact (100%), dorsiflexion (95%), external rotation (80%), and eversion (45%). Using the American Orthopaedic Foot and Ankle Society hindfoot score, the patients obtained a mean of 93 points; the surgically treated group (n = 14) scored higher (97 points) than did the nonoperative group (n = 6; 85 points) (P <. 05). Degenerative disease of the subtalar joint was found in 3 patients (15%; operative, 1 patient; nonoperative, 2 patients). All but 4 (20%, all after nonsurgical treatment) patients reached the same sport activity level as before injury.

Conclusion

The snowboarding-related lateral process of the talus fracture represents a complex hindfoot injury. In type II fractures, primary surgical treatment has led to achieving better outcomes, reducing sequelae, and allowing patients to regain the same sports activity level as before injury.
Early Inflammatory Reaction after Rotator Cuff Repair with a Porcine Small Intestine Submucosal Implant
Authors: Malcarney Hilary L. , Bonar Fiona , Murrell George A.C.
Published: April 2005

Background

Porcine small intestine submucosal grafts have been successful in enhancing soft tissue repair, as demonstrated by animal studies. Currently, there are no reports of the use of such implants in human rotator cuff repair.

Study Design

Case series; Level of evidence, 4.

Methods

Over a 6-month period, 25 patients underwent rotator cuff repair by one surgeon using the Restore Orthobiologic Implant to augment the repaired tendon or fill a defect.

Results

Four of 25 patients experienced an overt inflammatory reaction at a mean of 13 days postoperatively. All patients underwent open irrigation and debridement of the rotator cuff and porcine small intestine submucosal implant.

Conclusion

Porcine small intestine submucosal implants should be used in rotator cuff surgery with the awareness that a non-specific inflammatory reaction can occur in the early postoperative period. This inflammatory reaction may cause breakdown of the repair. Further studies are needed to further characterize the reaction and determine which patients are susceptible.
Percutaneous versus Open Repair of the Ruptured Achilles Tendon
Authors: Čretnik Andrej , Kosanović Miloš , Smrkolj Vladimir
Published: April 2005

Background

Controversy regarding the optimal treatment of the fresh total Achilles tendon rupture remains.

Purpose

To compare the results of percutaneous and open Achilles tendon repair.

Study Design

Cohort study; Level of evidence, 2.

Methods

The results of 132 consecutive patients with acute complete Achilles tendon rupture who were operated on exclusively with modified percutaneous repair under local anesthesia from 1991 to 1997 and followed up for at least 2 years were compared to the results of 105 consecutive patients who were operated on exclusively with open repair under general or spinal anesthesia in the same period.

Results

There were significantly fewer major complications in the group of percutaneous repairs in comparison with the group of open repairs (4.5% vs 12.4%; P = .03), particularly necrosis (0% vs 5.6%; P = .019), and a lower total number of complications (9.7% vs 21%; P = .013). There were slightly more reruptures (3.7% vs 2.8%; P = .680) and sural nerve disturbances (4.5% vs 2.8%; P = .487) in the group of percutaneous repairs, with no statistically significant difference. Functional assessment using the American Orthopaedic Foot and Ankle Society scale and the Holz score showed no statistically significant difference.

Conclusion

The results of the study support the choice of (modified) percutaneous suturing under local anesthesia as the method that brings comparable functional results to open repair, with a significantly lower rate of complications.
Finite element analysis of effect of electrode pitting in resistance spot welding of aluminium alloy
Authors: Chang B.H. , Zhou Y. , Lum I. , Du D.
Published: April 2005

The effect of electrode pitting on the formation of the weld nugget in resistance spot welding of an aluminium alloy was investigated using the finite element method. Pitted electrodes were simulated by assuming a pre-drilled hole of varying diameter at the centre of the electrode tip surface. The results showed that a small pitting hole would not have a detrimental influence on the nugget size. The actual contact area at the electrode/sheet interface did not change significantly when the diameter of the pitting hole was increased. However, a large pitted area at the electrode tip surface resulted in a greatly increased contact area and hence reduced current density at the sheet/sheet interface, which in turn led to the formation of an undersized weld nugget. The numerical calculation of the nugget shape and dimensions agreed well with experimental observations.
Weld-cost saving accomplished by replacing single-wire submerged arc welding with triple-wire welding
Authors: Tušek J. , Umek I. , Bajcer B.
Published: April 2005

A comparison is made of different submerged arc welding processes, that is ones using singlewire, twin-wire and triple-wire electrodes, applied to welding of two webs consisting of L sections 16x90x4100 mm in size. Experimental welding, measurement of welding parameters, calculation of the melting rate, measurement and calculation of shielding flux consumption, a visual examination of the welds made, an analysis of macro sections, and an economic calculation of the respective total cost of the welding processes using single-wire, twin-wire and triple-wire electrodes were performed in order to make a comparative analysis of the processes concerned. The experimental results obtained showed that high quality welded joints could be produced using two wires or three wires, i.e. the twin- or triple-wire electrode, in a joint contact tube in submerged arc welding. The calculation of the cost-effectiveness of welding, including personnel, materials, overheads and other costs, showed that welding with the twin-wire electrode cuts the costs by 20% and welding with the triple-wire electrode by around 30%. Submerged arc welding with a triple-wire electrode is a new welding process variant suitable for thick and long workpieces and in cases where a larger quantity of the molten filler material is required. Three wires in a joint contact tube can be arranged in a line or in the shape of a triangle optionally with long sides depending on the shape of the joint assembly and the weld shape desired. Although this procedure is highly efficient and shows numerous advantages over welding with a single-wire electrode, it has not been established in practice yet.
On-line prediction of quality and shear strength of spacer pad welds of nuclear fuel pins by applying neural network analysis of acoustic emission signals
Authors: Kalyanasundaram P. , Mukhopadhyay C.K. , Rajagopalan C. , Raj Baldev
Published: April 2005

In the present study, the development of an acoustic emission technique (AET) based methodology is reported for online prediction of quality and shear strength of spacer pad welds of nuclear fuel pins of pressurised heavy water reactors (PHWRs). The quality evaluation of spacer pad welds was made by classification of different weld categories using cluster analysis and artificial neural network (ANN) study of acoustic emission signals generated during welding. The ANN approach was also effective in arriving at the quantitative estimation of percentage correct classification between any two classes. For assessment of shear strength of individual coins of spacer pad welds by ANN, the properties of basic sigmoidal function were exploited and this could predict the strength of each coin with an accuracy of 97%. The results assume significance because instrumentation methodology is suitable for online application and complement the currently followed statistical quality control approaches for spacer pad weld assessment.
Direct resistance projection welding of copper and brass
Authors: Tušek J. , Tuma J.V. , Jenko M. , Pograjc M.
Published: April 2005

The present study discusses direct resistance projection welding of a multi-core copper cable to a discharge brass terminal. Resistance welding was carried out with a conventional machine. The upper tungsten electrode, which comes into contact with the multi-core copper cable, and the lower copper electrode, on which the brass terminal is lying during welding, are described. In the experimental research, the optimum welding parameters for direct welding (i.e.welding without an intermediate layer or a brazing filler material) of the two workpieces concerned were found. The welded joints obtained were subjected to a strength test, and metallurgical and resistance investigations. The strength test showed that the welded joint was quality welded and had higher strength than the brazed joint. With a heat resistance test during current conduction, it was found that the joint heated much less than the brazed joint. Metallographic investigations of macro-specimens and a chemical analysis at the copper/brass joining line are described.
Mechanical behaviour of overlap joints of titanium
Authors: Bergmann J.P.
Published: April 2005

Increasing demand for lightweight vehicles as well as for laser welding for automotive technologies in high rate production have pushed the automotive industry to consider the use of expensive lightweight materials with high specific mechanical properties and, as for example titanium, high corrosion resistance. Butt welds have too stringent requirements in relation to laser positioning and clamping methods, so the move to overlap joints is justified. The changes in welding design have to be requalified, in order to determine the geometries that allow the optimum exploitation of the bearing properties of a material. In this paper, the mechanical properties of overlap joints of thin sheets of titanium Grade 2 and of an α/ β alloy Ti–6Al–4V are investigated. The results presented allow a very precise classification of the two materials and should help engineers by indicating the optimum material for any given purpose. Ti–6Al–4V offers, for example, the highest strength when statically loaded, while, in contrast, the high notch sensibility results in a very poor fatigue limit when it is used for overlap joints, which is comparable to the low strength titanium Grade 2 in the same configuration.
Modelling of the GMAW system in free flight and short circuiting transfer
Authors: Terasaki H. , Simpson S.W.
Published: April 2005

An efficient model of gas metal arc welding (GMAW) systems was developed. The model accounts for the short circuiting transfer with free flight transfer, with finite droplet height included. Furthermore, we have analytically solved the energy equation of the wire, including the contact resistance between contact tip and wire as a boundary condition of the energy equation. The model predicts the time variable properties of GMAW systems from short circuiting to free flight transfer mode. Model prediction results have been compared with experimental results, and have shown good agreement.
Preferential suppression of trisomy 8 compared with normal hematopoietic cell growth by autologous lymphocytes in patients with trisomy 8 myelodysplastic syndrome
Authors: Sloand Elaine M. , Mainwaring Lori , Fuhrer Monika , Ramkissoon Shakti , Risitano Antonio M. , Keyvanafar Keyvan , Lu Jun , Basu Atanu , Barrett A. John , Young Neal S.
Published: April 2005

Clinical observations and experimental evidence link bone marrow failure in myelodysplastic syndrome (MDS) with a T cell–dominated autoimmune process. Immunosuppressive therapy is effective in improving cytopenias in selected patients. Trisomy 8 is a frequent cytogenetic abnormality in bone marrow cells in patients with MDS, and its presence has been associated anecdotally with good response to immunotherapy. We studied 34 patients with trisomy 8 in bone marrow cells, some of whom were undergoing treatment with antithymocyte globulin (ATG). All had significant CD8+ T-cell expansions of one or more T-cell receptor (TCR) Vβ subfamilies, as measured by flow cytometry; expanded subfamilies showed CDR3 skewing by spectratyping. Sorted T cells of the expanded Vβ subfamilies, but not of the remaining subfamilies, inhibited trisomy 8 cell growth in short-term hematopoietic culture. The negative effects of Vβ-expanded T cells were inhibited by major histocompatibility complex (MHC) class 1 monoclonal antibody (mAb) and Fas antagonist and required direct cell-to-cell contact. Sixty-seven percent of patients who had de novo MDS with trisomy 8 as the sole karyotypic abnormality responded to ATG with durable reversal of cytopenias and restoration of transfusion independence, with stable increase in the proportion of trisomy 8 bone marrow cells and normalization of the T-cell repertoire. An increased number of T cells with apparent specificity for trisomy 8 cells is consistent with an autoimmune pathophysiology in trisomy 8 MDS.
Siglec-9 transduces apoptotic and nonapoptotic death signals into neutrophils depending on the proinflammatory cytokine environment
Authors: von Gunten Stephan , Yousefi Shida , Seitz Michael , Jakob Stephan M. , Schaffner Thomas , Seger Reinhard , Takala Jukka , Villiger Peter M. , Simon Hans-Uwe
Published: April 2005

We report about new apoptotic and non-apoptotic death pathways in neutrophils that are initiated via the surface molecule sialic acid-binding immunoglobulin-like lectin (Siglec)-9. In normal neutrophils, Siglec-9 ligation induced apoptosis. Inflammatory neutrophils obtained from patients with acute septic shock or rheumatoid arthritis demonstrated increased Siglec-9, but normal Fas receptor-mediated cytotoxic responses when compared with normal blood neutrophils. The increased Siglec-9-mediated death was mimicked in vitro by short-term preincubation of normal neutrophils with proinflammatory cytokines, such as granulocyte/macrophage colony-stimulating factor (GM-CSF), interferon-α (IFN-α), and IFN-γ, and was demonstrated to be caspase independent. Experiments using scavengers of reactive oxygen species (ROS) or neutrophils unable to generate ROS indicated that both Siglec-9-mediated caspase-dependent and caspase-independent forms of neutrophil death depend on ROS. Interestingly, the caspase-independent form of neutrophil death was characterized by cytoplasmic vacuolization and several other nonapoptotic morphologic features, which were also seen in neutrophils present in joint fluids from rheumatoid arthritis patients. Taken together, these data suggest that apoptotic (ROS- and caspase-dependent) and nonapoptotic (ROS-dependent) death pathways are initiated in neutrophils via Siglec-9. The new insights have important implications for the pathogenesis, diagnosis, and treatment of inflammatory diseases such as sepsis and rheumatoid arthritis. (Blood. 2005;106:1423-1431)