bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Method Developed for Brittle and Ductile Materials to Evaluate Mechanical Properties of a Lump Specimen in the Use of Indentation Test
Authors: Wei Pal Jen , Lin Jen Fin
Published: April 2007

In this study, the load-depth (P‐h) relationships matching the experimental results of the nanoindentation tests exhibited at the subregions of small and large depths are obtained, respectively. The relationships associated with these two subregions are then linked by the hyperbolic logarithm function to attain a single expression that is applied in the evaluation of the specimen’s elastic recovery ability, as shown in the unloading process. A new method is developed in the present study to evaluate both Young’s modulus and the yield strength of either a ductile or brittle material through the uses of the appropriate P‐h relationships developed in the load and unloading processes. The results of the Young’s modulus and the yield strength achieved by the present method are compared to those obtained from the conventional material tests for a lump material. The scattering of the experimental data shown in the loading and unloading processes are also interpreted by different causes.
Effects of Platelet Size and Mean Volume Fraction on Platelet Orientation and Volume Fraction Distributions in Functionally Graded Material Fabricated by a Centrifugal Solid-Particle Method
Authors: Sequeira P. D. , Watanabe Yoshimi , Eryu Hiroyuki , Yamamoto Tetsuya , Matsuura Kiyotaka
Published: April 2007

Background. A centrifugal solid-particle method has been successfully used as a means to fabricate functionally graded materials (FGMs). Various processing parameters significantly influence the formation of the graded microstructural and properties distribution in these FGMs. Method of Approach. Alloys with different Al3Ti platelet volume fractions and platelet sizes are used to study the effects of those parameters on graded distributions of the volume fraction and orientation of platelets. Al-platelet/plaster FGMs are used as a model system, and the effects of the same parameters are investigated. Results. It was found that an increase in initial volume fraction and particle size leads to steeper gradients of volume fraction and orientation distributions within the Al-Al3Ti FGMs. The results of the experimental studies are compared to those of the model material. Conclusions. It was verified that, although with some limitations, the proposed model system will be useful in the study of the formation mechanisms of the graded distributions in the FGMs.
Development and Validation of Novel FE Models for 3D Analysis of Peening of Strain-Rate Sensitive Materials
Authors: Meguid S. A. , Shagal G. , Stranart J. C.
Published: April 2007

In this paper, we provide two different symmetry cells to describe the shot-peening process. In this multiple impingement model, we study the dynamic behavior of TI-6Al-4V targets subjected to a large number of shots. Three-dimensional elastoplastic finite element analysis (FEA) of the process was conducted using these two symmetry cells for strain-rate sensitive targets and rigid shots. The basic symmetry cell is assigned a target surface area C×C, where C is one half of separation distance between adjacent shots. The second “enhanced” symmetry cell is assigned a target surface area 2C×2C thus allowing higher density of impact point locations. Average residual stresses inside the target predicted by FEA were compared with experimental measurements using the hole-drilling technique. In order to do this, a new averaged technique was developed to obtain the stress distribution inside the symmetry cell. The results reveal that both symmetry cell models could be used for shot-peening modeling. However, the use of the enhanced symmetry cell leads to a better agreement with the measured residual stresses. In addition, the enhanced symmetry cell model allowed us to overcome some of the shortcomings of the basic symmetry cell for cases involving high peening velocity and intensity.
Manufacturing Aspects Relating to the Effects of Direct Current on the Tensile Properties of Metals
Authors: Ross Carl D. , Irvin David B. , Roth John T.
Published: April 2007

For metals, deformation is commonly conducted at elevated temperatures, reducing the overall process energy and cost. However, elevating the temperature has many drawbacks, including high tool/die adhesions, environmental reactivity, etc. Therefore, this study examines using an electrical current to reduce the deformation energy and presents electricity’s effects on the tensile properties of various materials. The influences of strain rate and cold work are also investigated. The results demonstrate that, when current flows through a metallic specimen, the material’s yield strength, flow stress, and elastic modulus are decreased; strain weakening occurs; and the total energy of deformation is decreased. These changes in the engineering stress-strain behavior occurred in all of the materials tested and are much greater than can be accounted for by resistive heating. However, the effects diminish with increasing strain rate. The analysis shows that applying electricity during deformation provides a viable alternative to increasing the workpiece temperature for deformation-based manufacturing processes.
Regolith Migration and Sorting on Asteroid Itokawa
Authors: Miyamoto Hideaki , Yano Hajime , Scheeres Daniel J. , Abe Shinsuke , Barnouin-Jha Olivier , Cheng Andrew F. , Demura Hirohide , Gaskell Robert W. , Hirata Naru , Ishiguro Masateru , Michikami Tatsuhiro , Nakamura Akiko M. , Nakamura Ryosuke , Saito Jun , Sasaki Sho
Published: April 2007

High-resolution images of the surface of asteroid Itokawa from the Hayabusa mission reveal it to be covered with unconsolidated millimeter-sized and larger gravels. Locations and morphologic characteristics of this gravel indicate that Itokawa has experienced considerable vibrations, which have triggered global-scale granular processes in its dry, vacuum, microgravity environment. These processes likely include granular convection, landslide-like granular migrations, and particle sorting, resulting in the segregation of the fine gravels into areas of potential lows. Granular processes become major resurfacing processes because of Itokawa's small size, implying that they can occur on other small asteroids should those have regolith.
FT Protein Movement Contributes to Long-Distance Signaling in Floral Induction of
Arabidopsis
Authors: Corbesier Laurent , Vincent Coral , Jang Seonghoe , Fornara Fabio , Fan Qingzhi , Searle Iain , Giakountis Antonis , Farrona Sara , Gissot Lionel , Turnbull Colin , Coupland George
Published: April 2007

In plants, seasonal changes in day length are perceived in leaves, which initiate long-distance signaling that induces flowering at the shoot apex. The identity of the long-distance signal has yet to be determined. In
Arabidopsis
, activation of
FLOWERING LOCUS T
(
FT
) transcription in leaf vascular tissue (phloem) induces flowering. We found that
FT
messenger RNA is required only transiently in the leaf. In addition, FT fusion proteins expressed specifically in phloem cells move to the apex and move long distances between grafted plants. Finally, we provide evidence that FT does not activate an intermediate messenger in leaves. We conclude that FT protein acts as a long-distance signal that induces
Arabidopsis
flowering.
Hd3a Protein Is a Mobile Flowering Signal in Rice
Authors: Tamaki Shojiro , Matsuo Shoichi , Wong Hann Ling , Yokoi Shuji , Shimamoto Ko
Published: April 2007

Florigen, the mobile signal that moves from an induced leaf to the shoot apex and causes flowering, has eluded identification since it was first proposed 70 years ago. Understanding the nature of the mobile flowering signal would provide a key insight into the molecular mechanism of floral induction. Recent studies suggest that the
Arabidopsis FLOWERING LOCUS T
(
FT
) gene is a candidate for encoding florigen. We show that the protein encoded by
Hd3a
, a rice ortholog of
FT
, moves from the leaf to the shoot apical meristem and induces flowering in rice. These results suggest that the Hd3a protein may be the rice florigen.
Isolation of
Nocardia asiatica
from Cutaneous Ulcers of a Human Immunodeficiency Virus-Infected Patient in Italy
Authors: Iona Elisabetta , Giannoni Federico , Brunori Lara , de Gennaro Michele , Mattei Romano , Fattorini Lanfranco
Published: April 2007

A strain of
Nocardia
was isolated from cutaneous ulcers of a human immunodeficiency virus-infected patient in Italy. Comparative 16S rRNA gene sequence analysis revealed that the isolate represented a strain of
Nocardia asiatica
. Antimicrobial susceptibility testing was essential to guide the clinicians to successfully treat this infection.
Evaluation of Different Clinical Sample Types in Diagnosis of Human Enterovirus 71-Associated Hand-Foot-and-Mouth Disease
Authors: Ooi Mong How , Solomon Tom , Podin Yuwana , Mohan Anand , Akin Winnie , Yusuf Mohd Apandi , del Sel Syvia , Kontol Kamsiah Mohd , Lai Boon Fu , Clear Daniela , Chieng Chae Hee , Blake Emma , Perera David , Wong See Chang , Cardosa Jane
Published: April 2007

Human enterovirus 71 and coxsackievirus A16 are important causes of hand-foot-and-mouth disease (HFMD). Like other enteroviruses, they can be isolated from a range of sterile and nonsterile sites, but which clinical sample, or combination of samples, is the most useful for laboratory diagnosis of HFMD is not clear. We attempted virus culture for 2,916 samples from 628 of 725 children with HFMD studied over a 3 1/2-year period, which included two large outbreaks. Overall, throat swabs were the single most useful specimen, being positive for any enterovirus for 288 (49%) of 592 patients with a full set of samples. Vesicle swabs were positive for 169 (48%) of 333 patients with vesicles, the yield being greater if two or more vesicles were swabbed. The combination of throat plus vesicle swabs enabled the identification of virus for 224 (67%) of the 333 patients with vesicles; for this patient group, just 27 (8%) extra patients were diagnosed when rectal and ulcer swabs were added. Of 259 patients without vesicles, use of the combination of throat plus rectal swab identified virus for 138 (53%). For 60 patients, virus was isolated from both vesicle and rectal swabs, but for 12 (20%) of these, the isolates differed. Such discordance occurred for just 11 (10%) of 112 patients with virus isolated from vesicle and throat swabs. During large HFMD outbreaks, we suggest collecting swabs from the throat plus one other site: vesicles, if these are present (at least two should be swabbed), or the rectum if there are no vesicles. Vesicle swabs give a high diagnostic yield, with the added advantage of being from a sterile site.
A GLOBAL IN TIME EXISTENCE AND UNIQUENESS RESULT FOR A SEMILINEAR INTEGRODIFFERENTIAL PARABOLIC INVERSE PROBLEM IN SOBOLEV SPACES
Authors: COLOMBO FABRIZIO , GUIDETTI DAVIDE
Published: April 2007

We prove a global in time abstract existence and uniqueness result for a general parabolic problem of reconstruction of a convolution kernel. The result is, in particular, applicable to the theory of heat conduction for materials with memory.
FULLY DISCRETE SCHEMES FOR THE SCHRÖDINGER EQUATION: DISPERSIVE PROPERTIES
Authors: IGNAT LIVIU I.
Published: April 2007

We consider fully discrete schemes for the one-dimensional linear Schrödinger equation and analyze whether the classical dispersive properties of the continuous model are presented in these approximations. In particular, Strichartz estimates and the local smoothing of the numerical solutions are analyzed. Using a backward Euler approximation of the linear semigroup we introduce a convergent scheme for the nonlinear Schrödinger equation with nonlinearities which cannot be treated by energy methods.
ON THE GENERALIZED VON KÁRMÁN EQUATIONS AND THEIR APPROXIMATION
Authors: CIARLET PHILIPPE G. , GRATIE LILIANA , KESAVAN SRINIVASAN
Published: April 2007

We consider here the "generalized von Kármán equations", which constitute a mathematical model for a nonlinearly elastic plate subjected to boundary conditions "of von Kármán type" only on a portion of its lateral face, the remaining portion being free. As already shown elsewhere, solving these equations amounts to solving a "cubic" operator equation, which generalizes an equation introduced by Berger and Fife. Two noticeable features of this equation, which are not encountered in the "classical" von Kármán equations are the lack of strict positivity of its cubic part and the lack of an associated functional. We establish here the convergence of a conforming finite element approximation to these equations. The proof relies in particular on a compactness method due to J. L. Lions and on Brouwer's fixed point theorem. This convergence proof provides in addition an existence proof for the original problem.
PRICING SECURITIES WITH EXCHANGE-IMPOSED PRICE LIMITS VIA RISK NEUTRAL VALUATION
Authors: HAREL ARIE , HARPAZ GIORA , FRANCIS JACK CLARK
Published: April 2007

Asian and European financial markets impose daily price fluctuation limits on individual securities. In the US several futures exchanges are regulated by price fluctuation limits as well. The price limits in most exchanges are set daily, and they are usually based on a percentage change from the previous day's closing price. We show that the future cash flows of a security subject to price limit regulation resemble that of a distinctive contingent claim. Assuming that the security price follows a lognormal distribution, we use the risk-neutral valuation relation (RNVR) developed by [4] to derive the security valuation, in the presence of price fluctuation limits. The characteristics of the pricing formula are examined analytically and numerically.
AN EXTENSION OF THE BRODY–HUGHSTON–MACRINA APPROACH TO MODELING OF DEFAULTABLE BONDS
Authors: RUTKOWSKI MAREK , YU NANNAN
Published: April 2007

The innovative information-based framework for credit risk modeling, proposed recently by Brody, Hughston, and Macrina, is extended to a more general and practically important setup of random interest rates. We first introduce the market model, and we derive an explicit expression for defaultable bond price. Next, the dynamics of the information process and dynamics of defaultable bond are found for both deterministic and random interest rates. Finally, the valuation and hedging of derivative securities are briefly examined. In particular, the valuation formula for a European option on a defaultable bond is established.
HEDGING VOLATILITY RISK: THE EFFECTIVENESS OF VOLATILITY OPTIONS
Authors: AN YUNBI , ASSAF ATA , YANG JUN
Published: April 2007

In this paper we focus on the performance of volatility options as hedging instruments for hedging volatility risk. We investigate (a) the relative hedging performance of volatility and European options, (b) the relative hedging performance of volatility index and straddle options, and (c) the impact of model misspecification on hedging effectiveness. Our focus is on exotic options as the options to be hedged, because they are more sensitive to volatility risk and model risk and practically more relevant when the effectiveness of different hedging strategies is examined. Using a Monte Carlo simulation, we find that volatility options are especially useful for hedging options with a severe exotic feature and there is no significant difference between the performances of volatility index and straddle options. Furthermore, our results indicate that model misspecification has an important impact on the hedging performance.
S-adenosyl methionine protects ob/ob mice from CYP2E1-mediated liver injury
Authors: Dey Aparajita , Caro Andres A. , Cederbaum Arthur I.
Published: April 2007

Pyrazole treatment to induce cytochrome P-450 2E1 (CYP2E1) was recently shown to cause liver injury in ob/ob mice but not in lean mice. The present study investigated the effects of S-adenosyl-l-methionine (SAM) on the CYP2E1-dependent liver injury in ob/ob mice. Pyrazole treatment of ob/ob mice for 2 days caused necrosis, steatosis, and elevated serum transaminase and triglyceride levels compared with saline ob/ob mice. Administration of SAM (50 mg/kg body wt ip every 12 h for 3 days) prevented the observed pathological changes as well as the increase of apoptotic hepatocytes, caspase 3 activity, and serum TNF-α levels. SAM administration inhibited CYP2E1 activity but not CYP2E1 content. The pyrazole treatment increased lipid peroxidation, 4-hydroxynonenal and 3-nitrotyrosine protein adducts, and protein carbonyls. These increases in oxidative and nitrosative stress were prevented by SAM. Treatment of ob/ob mice with pyrazole lowered the endogenous SAM levels, and these were elevated after SAM administration. Mitochondrial GSH levels were very low after pyrazole treatment of the ob/ob mice; this was associated with elevated levels of malondialdehyde and 4-hydroxynonenal and 3-nitrotyrosine protein adducts in the mitochondria. All these changes were prevented with SAM administration. SAM protected against pyrazole-induced increase in serum transaminases, necrosis, triglyceride levels, caspase-3 activity, and lipid peroxidation even when administered 1 day after pyrazole treatment. In the absence of pyrazole, SAM lowered the slightly elevated serum transaminases, triglyceride levels, caspase-3 activity, and lipid peroxidation in obese mice. In conclusion, SAM protects against and can also reverse or correct CYP2E1-induced liver damage in ob/ob mice.
Influence of age on cardiac baroreflex function during dynamic exercise in humans
Authors: Fisher James P. , Ogoh Shigehiko , Ahmed Abrar , Aro Michael R. , Gute Dean , Fadel Paul J.
Published: April 2007

We investigated the influence of aging on cardiac baroreflex function during dynamic exercise in seven young (22 ± 1 yr) and eight older middle-aged (59 ± 2 yr) healthy subjects. Carotid-cardiac baroreflex function was assessed at rest and during moderate-intensity steady-state cycling performed at 50% heart rate reserve (HRR). Five-second pulses of neck pressure and neck suction from +40 to −80 Torr were applied to determine the operating point gain (GOP) and maximal gain (GMAX) of the full carotid-cardiac baroreflex function curve and examine baroreflex resetting during exercise. At rest, mean arterial pressure (MAP) and heart rate were similar between the younger and older subjects. In contrast, the resting GOP and GMAX were significantly lower in the older subjects. The increase in MAP from rest to exercise was greater in the older subjects (Δ +20 ± 2 older vs. Δ +6 ± 3 younger mmHg; P < 0.001). However, the GOP was similar in both groups during exercise because of a reduction in the younger subjects. In contrast, GMAX was unchanged from rest and therefore remained lower in older subjects (−0.19 ± 0.05 older vs. −0.42 ± 0.05 younger beats·min−1·mmHg−1; 50% HRR; P < 0.001). Furthermore, exercise resulted in an upward and rightward resetting of the cardiac baroreflex function curve in both groups. Collectively, these findings suggest that the cardiac baroreflex function curve appropriately resets during exercise in older subjects but operates at a reduced GMAX primarily because of age-related reductions in carotid-cardiac control manifest at rest.
Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station
Authors: Baevsky Roman M. , Baranov Victor M. , Funtova Irina I. , Diedrich André , Pashenko Andrey V. , Chernikova Anja G. , Drescher Jürgen , Jordan Jens , Tank Jens
Published: April 2007

Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41–50 yr, body-mass index of 22–28 kg/m2) during long-term missions (flight lengths of 162–196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight ( P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight ( P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances.
Effect of acute hyperlipidemia on autonomic and cardiovascular control in humans
Authors: Monahan Kevin D. , Dyckman Damian J. , Ray Chester A.
Published: April 2007

Blood lipids may detrimentally affect autonomic and circulatory control. We tested the hypotheses that acute elevations in free fatty acids and triglycerides (acute hyperlipidemia) impair baroreflex control of cardiac period [cardiovagal baroreflex sensitivity (BRS)] and muscle sympathetic nerve activity (MSNA: sympathetic BRS), increase MSNA at rest, and augment physiological responses to exercise. Eighteen young adults were examined in this randomized, double-blinded, and placebo-controlled study. BRS was determined using the modified Oxford technique before (pre) and 60 min (post) after initiating infusion of Intralipid (0.8 ml·m−2·min−1) and heparin (1,000 U/h) (experimental; n = 12) to induce acute hyperlipidemia, or saline (0.8 ml·m−2·min−1) and heparin (1,000 U/h) (control; n = 6). Responses to isometric handgrip to fatigue (IHG) were also determined. Blood pressure increased more ( P < 0.05) in experimental than control subjects during the infusion. MSNA at rest (14 ± 2 vs. 11 ± 1 bursts/min), cardiovagal (19.8 ± 1.8 vs. 19.1 ± 2.4 ms/mmHg pre and post, respectively) and sympathetic BRS (−5.5 ± 0.6 vs. −5.2 ± 0.4 au·beat−1·mmHg−1), and the neural and cardiovascular responses to IHG were unchanged by acute hyperlipidemia (pre vs. post) in experimental subjects. Similarly, MSNA at rest (10 ± 2 vs. 12 ± 2 bursts/min), cardiovagal (22.1 ± 4.0 vs. 21.0 ± 4.6 ms/mmHg) and sympathetic BRS (−5.8 ± 0.5 vs. −5.5 ± 0.5 au·beat−1·mmHg−1), and the neural and cardiovascular responses to IHG were unchanged by the infusion in control subjects. These data do not provide experimental support for the concept that acute hyperlipidemia impairs reflex cardiovagal or sympathetic regulation in humans.
Muscle Na+-K+-ATPase activity and isoform adaptations to intense interval exercise and training in well-trained athletes
Authors: Aughey R. J. , Murphy K. T. , Clark S. A. , Garnham A. P. , Snow R. J. , Cameron-Smith D. , Hawley J. A. , McKenna M. J.
Published: April 2007

The Na+-K+-ATPase enzyme is vital in skeletal muscle function. We investigated the effects of acute high-intensity interval exercise, before and following high-intensity training (HIT), on muscle Na+-K+-ATPase maximal activity, content, and isoform mRNA expression and protein abundance. Twelve endurance-trained athletes were tested at baseline, pretrain, and after 3 wk of HIT (posttrain), which comprised seven sessions of 8 × 5-min interval cycling at 80% peak power output. Vastus lateralis muscle was biopsied at rest (baseline) and both at rest and immediately postexercise during the first (pretrain) and seventh (posttrain) training sessions. Muscle was analyzed for Na+-K+-ATPase maximal activity (3- O-MFPase), content ([3H]ouabain binding), isoform mRNA expression (RT-PCR), and protein abundance (Western blotting). All baseline-to-pretrain measures were stable. Pretrain, acute exercise decreased 3- O-MFPase activity [12.7% (SD 5.1), P < 0.05], increased α1, α2, and α3mRNA expression (1.4-, 2.8-, and 3.4-fold, respectively, P < 0.05) with unchanged β-isoform mRNA or protein abundance of any isoform. In resting muscle, HIT increased ( P < 0.05) 3- O-MFPase activity by 5.5% (SD 2.9), and α3and β3mRNA expression by 3.0- and 0.5-fold, respectively, with unchanged Na+-K+-ATPase content or isoform protein abundance. Posttrain, the acute exercise induced decline in 3- O-MFPase activity and increase in α1and α3mRNA each persisted ( P < 0.05); the postexercise 3- O-MFPase activity was also higher after HIT ( P < 0.05). Thus HIT augmented Na+-K+-ATPase maximal activity despite unchanged total content and isoform protein abundance. Elevated Na+-K+-ATPase activity postexercise may contribute to reduced fatigue after training. The Na+-K+-ATPase mRNA response to interval exercise of increased α- but not β-mRNA was largely preserved posttrain, suggesting a functional role of α mRNA upregulation.
Adaptations in the activation of human skeletal muscle induced by short-term isometric resistance training
Authors: Del Balso Christopher , Cafarelli E.
Published: April 2007

This study employed longitudinal measures of evoked spinal reflex responses (Hoffman reflex, V wave) to investigate changes in the activation of muscle and to determine if there are “linked” neural adaptations in the motor pathway following isometric resistance training. Twenty healthy, sedentary males were randomly assigned to either the trained ( n = 10) or control group ( n = 10). The training protocol consisted of 12 sessions of isometric resistance training of the plantar flexor muscles over a 4-wk period. All subjects were tested prior to and after the 4-wk period. To estimate changes in spinal excitability, soleus Hoffman (H) reflex and M wave recruitment curves were produced at rest and during submaximal contractions. Recruitment curves were analyzed using the slope method (Hslp/Mslp). Modulation of efferent neural drive was assessed through evoked V wave responses (V/Mmax) at 50, 75, and 100% maximal voluntary contraction (MVC). After 4 weeks, MVC torque increased 20.0 ± 13.9% (mean ± SD) in the trained group. The increase in MVC was accompanied by significant increases in the rate of torque development (42.5 ± 13.3%), the soleus surface electromyogram (60.7 ± 30.8%), voluntary activation (2.8 ± 0.1%), and the rate of activation (48.7 ± 24.3%). Hslp/Mslpwas not altered by training; however, V/Mmaxincreased 57.3 ± 34.2% during MVC. These results suggest that increases in MVC observed in the first few days of isometric resistance training can be accounted for by an increase in the rate of activation at the onset of muscle contraction. Augmentation of muscle activation may be due to increased volitional drive from supraspinal centers.
An Observational Study on the Effects of Nadroparin-Based and Citrate-Based Continuous Venovenous Hemofiltration on Calcium Metabolism
Authors: van der Voort Peter H.J. , Postma Sonja R. , Kingma W. Peter , Boerma E. Christiaan , de Heide Loek J.M. , Bakker Andries J.
Published: April 2007

Backgrounds: To study calcium homeostasis during citrate-based compared to nadroparin-based CVVH in critically-ill patients with acute renal failure. Methods: 11 patients were observed during citrate anticoagulation, 9 with nadroparin and 10 controls. Citrate was chosen for patients with active or at risk for bleeding. Results: The controls had, at 24 h, a median serum iCa of 1.1 mmol/l, the citrate group 0.87 mmol/l and the nadroparin group 1.1 mmol/l (citrate vs. control p = 0.001, citrate vs. nadroparin p = 0.002). At 48 h, iCa was not significantly different anymore. Ca balance was negative for the citrate group in contrast to the nadroparin group (p = 0.012). Median serum PTH was higher (30.0 pmol/l vs. 6.5 pmol/l, p = 0.003) in the citrate group. Conclusion: With a relative low target-serum-iCa (0.8–0.9 mmol/l) citrate CVVH-treated patients had a negative daily calcium balance and a temporarily lower iCa level resulting in an enhanced PTH response in comparison to nadroparin.
Vascular Endothelial Growth Factors C and D Represent Novel Prognostic Markers in Colorectal Carcinoma Using Quantitative Image Analysis
Authors: Hu W.-G. , Li J.-W. , Feng B. , Beveridge M. , Yue F. , Lu A.-G. , Ma J.-J. , Wang M.-L. , Guo Y. , Jin X.-L. , Zheng M.-H.
Published: April 2007

Background/Aims: Vascular endothelial growth factor C (VEGF-C) and vascular endothelial growth factor D (VEGF-D) are potent lymphangiogenic and angiogenetic mediators in many kinds of tumors. However, the exact impacts of VEGF-C and VEGF-D on the prognosis of colorectal cancer (CRC) remain elusive. The aims of this study were to demonstrate the expression of VEGF-C and VEGF-D and to correlate their expression levels with clinicopathological factors and long-term survival in patients with CRC. Patients and Methods: Between January 1996 and January 1998, 69 patients with pathologically confirmed CRC who received routine follow-up at the Ruijin Hospital were included in this study. VEGF-C and VEGF-D protein expression and microvessel density of 69 surgical specimens were assessed by immunohistochemistry, with 20 samples of normal colorectal tissues as controls. All patients were followed up for 108 months or until death. The Immunohistochemical stains were quantified and analyzed by means of a Zeiss Axioplan 2 imaging analysis system. Results: The protein expression of VEGF-C and VEGF-D in tumor tissues was much higher than that in normal colorectal tissues (p < 0.01). The VEGF-C expression significantly correlated with lymph node metastasis (p = 0.011) and clinical stages of CRC (p < 0.01). The VEGF-D expression correlated with patient ages (p = 0.013), depth of tumor invasion (p = 0.013), and lymph node metastasis (p = 0.028). The expression of VEGF-C and VEGF-D was significantly correlated with the microvessel density. Both overall survival and disease-free survival at 108 months were significantly lower in the CRC patients with a high VEGF-C and/or a high VEGF-D expression, and the patients with a high expression of both VEGF-C and VEGF-D had the shortest overall survival and disease-free survival when compared with other patients. Conclusion: The VEGF-C or VEGF-D expression was significantly correlated with lymph node metastasis and long-term prognosis and could be applied as prognostic markers in CRC.
Expression of SPAM1 (PH-20) in the Murine Kidney Is Not Accompanied by Hyaluronidase Activity: Evidence for Potential Roles in Fluid and Water Reabsorption
Authors: Grigorieva Anastasia , Griffiths Genevieve S. , Zhang Hong , Laverty Gary , Shao Minghai , Taylor Leslie , Martin-DeLeon Patricia A.
Published: April 2007

Background:A role for Sperm Adhesion Molecule 1 (SPAM1) hyaluronidase in murine kidney, where Spam1 transcript levels have been reported to be higher in males, has not been clarified. Methods:Spam1 RNA and protein were studied using RT-PCR, in situhybridization, Western blotting, immunohistochemistry and hyaluronic acid substrate gel electrophoresis. Urine volume and osmolality were studied in wild-type and Spam1 null mice. Results: While RT-PCR supported a tendency of higher RNA expression in males, no sex difference for the protein was detectable in the cortex, medulla, and urine. Transcripts were predominantly localized in the proximal tubules and glomeruli, with lower levels in the medulla. Similarly, Western blotting and immunohistochemistry revealed that SPAM1 is more abundant in the cortex. Hyaluronidase activity was absent at neutral and acidic pH: suggesting non-enzymatic role(s) for SPAM1. Wild-type and Spam1 null mice given free access to water showed significantly reduced urine volumes (p < 0.01; n = 12) in the latter.Baseline urine osmolality was similar in both, leading to a significantly (p < 0.05) lower osmolar output in the nulls. After water deprivation (24 h), a significant (p < 0.01) increase in urine osmolality was seen only for wild-type mice. Conclusion: SPAM1 is implicated in fluid reabsorption and urine concentration.
Surgical Treatment for Digestive Cancer
Authors: Okuno Kiyotaka
Published: April 2007

Background: Due to the westernization of the diet in Japan, the incidence of colorectal cancer has increased 4.5 times in the last 25 years. In this review, the recent results of surgical treatment for colonic cancer and the future perspectives in Japan are described. Materials and Methods: A multi-institutional registry of large bowel cancer in Japan of 10,809 patients with colonic cancer treated from 1991 to 1994 was investigated. The data have been published in the Guidelines of the Japanese Society for Cancer of the Colon and Rectum (2005). Regarding laparoscopic surgery, 1,495 patients with colon cancer were examined in a multicenter study between April 1993 and August 2002. Results: Radical resection with a curative intent is appropriate for 83–99% of the patients with stage I–III localized colon carcinoma. Adequate lymphadenectomy, including paracolic, intermediate and principal node dissection (D3 lymphadenectomy), is of critical importance for both the accurate staging and local control of the disease. This treatment protocol has now been accepted as a ‘standard’ operation by Japanese colorectal surgeons. For patients undergoing a curative resection for colon cancer, the 5-year survival rates vary between 62 (stage III) and 91% (stage I). Adjuvant chemotherapy using 5-FU/leucovorin or oral compounds is commonly administered to patients with stage III disease. Laparoscopic surgery for colonic cancer yielded a comparable oncological outcome to that reported for conventional open surgery in the Japanese registry for all disease stages. Conclusion: Radical resection with a D3 lymphadenectomy provided satisfactory 5-year survival for patients with stage I–III colon cancer in Japan. However, the survival of patients with stage IV disease is still unsatisfactory (only a 14% 5-year survival). Any further improvements depend on both identifying such patients at an earlier stage as well as developing new and effective treatment modalities.
Current Surgical Management of Rectal Cancer
Authors: Kusunoki Masato , Inoue Yasuhiro
Published: April 2007

The management of rectal cancer has undergone significant evolution over the past decade with improvements in both surgical technique and adjuvant therapies. The progression of surgical management has been of particular interest, as surgery is the only potentially curative treatment. The major goals of surgery are to optimize oncologic outcome and maintain anorectal and genitourinary function. There are presently two approaches to rectal cancer surgery: total mesorectal excision (TME), which is the gold standard in the Western world, and lateral lymph node dissection, which was originally developed in Japan. Although the results of lateral lymph node dissection are similar to TME with prior radiotherapy, low positive lateral lymph node yields, questionable prognostic significance, and high morbidity are the main drawbacks of this procedure. Despite the current quality of these surgical procedures, locoregional treatment is limited as advanced primary rectal cancer may be associated with systemic spread of disease. Adjuvant therapy therefore plays a key role in obtaining further improvement in survival. In this article, evidence for the use and benefits of lateral lymph node dissection surgery for rectal cancer patients in Japan is reviewed, and its application in association with TME and other modalities considered.
Behavioural Measures in Frontotemporal Lobar Dementia and Other Dementias: The Utility of the Frontal Behavioural Inventory and the Neuropsychiatric Inventory in a National Cohort Study
Authors: Blair M. , Kertesz A. , Davis-Faroque N. , Hsiung G.-Y.R. , Black S.E. , Bouchard R.W. , Gauthier S. , Guzman D.A. , Hogan D.B. , Rockwood K. , Feldman H.
Published: April 2007

Background: Distinguishing between patients with frontotemporal lobar dementia (FTLD) and other dementing illnesses remains a difficult task for many clinicians. In this study, we aimed to provide further evidence for the construct validity of the frontal behavioural inventory (FBI) and assess its utility in differentiating FTLD patients from other groups using data from the Canadian Collaborative Cohort of Related Dementias (ACCORD) study. Method: Baseline scores on the FBI and neuropsychiatric inventory (NPI) were compared among several clinical groups (n = 177). Results: The FBI discriminated a higher percentage of FTLD patients (>75% correct classification) from Alzheimer’s disease and other groups compared to the NPI (54.2%). Conclusion: This study provides good evidence for convergent validity between the FBI and NPI (r = 0.72), indicating that both measures capture similar psychopathology in this nationwide cohort.
Association of
ATP1A1
and
Dear
Single-Nucleotide Polymorphism Haplotypes With Essential Hypertension
Authors: Glorioso Nicola , Herrera Victoria L.M. , Bagamasbad Pia , Filigheddu Fabiana , Troffa Chiara , Argiolas Giuseppe , Bulla Emanuela , Decano Julius L. , Ruiz-Opazo Nelson
Published: April 2007

Essential hypertension remains a major risk factor for cardiovascular and cerebrovascular diseases. As a complex multifactorial disease, elucidation of susceptibility loci remains elusive.
ATP1A1
and
Dear
are candidate genes for 2 closely linked rat chromosome-2 blood pressure quantitative trait loci. Because corresponding human syntenic regions are on different chromosomes, investigation of
ATP1A1
(chromosome [chr]-1p21) and
Dear
(chr-4q31.3) facilitates genetic analyses of each blood pressure quantitative trait locus in human hypertension. Here we report the association of human
ATP1A1
(
P
<0.000005) and
Dear
(
P
<0.03) with hypertension in a relatively isolated, case/control hypertension cohort from northern Sardinia by single-nucleotide polymorphism haplotype analysis. Sex-specific haplotype analyses detected stronger association of both loci with hypertension in males than in females. Haplotype trend-regression analyses support
ATP1A1
and
Dear
as independent susceptibility loci and reveal haplotype-specific association with hypertension and normotension, thus delineating haplotype-specific subsets of hypertension. Although investigation in other cohorts needs to be performed to determine genetic effects in other populations, haplotype subtyping already allows systematic stratification of susceptibility and, hence, clinical heterogeneity, a prerequisite for unraveling the polygenic etiology and polygene–environment interactions in essential hypertension. As hypertension susceptibility genes, coexpression of
ATP1A1
and
Dear
in both renal tubular cells and vascular endothelium suggest a cellular pathogenic scaffold for polygenic mechanisms of hypertension, as well as the hypothesis that
ATP1A1
and/or
Dear
could contribute to the known renal and vascular endothelial dysfunction associated with essential (polygenic) hypertension.
The Troponin C G159D Mutation Blunts Myofilament Desensitization Induced by Troponin I Ser23/24 Phosphorylation
Authors: Biesiadecki Brandon J. , Kobayashi Tomoyoshi , Walker John S. , John Solaro R. , de Tombe Pieter P.
Published: April 2007

Striated muscle contraction is regulated by the binding of Ca
2+
to the N-terminal regulatory lobe of the cardiac troponin C (cTnC) subunit in the troponin complex. In the heart, β-adrenergic stimulation induces protein kinase A phosphorylation of cardiac troponin I (cTnI) at Ser23/24 to alter the interaction of cTnI with cTnC in the troponin complex and is critical to the regulation of cardiac contractility. We investigated the effect of the dilated cardiomyopathy linked cTnC Gly159 to Asp (cTnC-G159D) mutation on the development of Ca
2+
-dependent tension and ATPase rate in whole troponin-exchanged skinned rat trabeculae. Even though this mutation is located in the C-terminal lobe of cTnC, the G159D mutation was demonstrated to depress ATPase activation and filament sliding in vitro. The effects of this mutation within the cardiac myofilament are unknown. Our results demonstrate that the cTnC-G159D mutation by itself does not alter the myofilament response to Ca
2+
in the cardiac muscle lattice. However, in the presence of cTnI phosphorylated at Ser23/24, which reduced Ca
2+
sensitivity and enhanced cross-bridge cycling in controls, cTnC-G159D specifically blunted the phosphorylation induced decrease in Ca
2+
-sensitive tension development without altering cross-bridge cycling. Measurements in purified troponin confirmed that this cTnC-G159D blunting of myofilament desensitization results from altered Ca
2+
-binding to cTnC. Our results provide novel evidence that modification of the cTnC-cTnI interaction has distinct effects on troponin Ca
2+
-binding and cross-bridge kinetics to suggest a novel role for thin filament mutations in the modulation of myofilament function through β-adrenergic signaling as well as the development of cardiomyopathy.
Usefulness of Cardiovascular Investigations in Stroke Management
Authors: Douen Andre , Pageau Nicole , Medic Sejla
Published: April 2007

Background and Purpose—

There are no prospective randomized studies assessing the clinical relevance of routine cardiovascular investigations in stroke patients. The objective of this study was to evaluate the utilization, relevance, and economics of cardiovascular investigations in an ambulatory stroke clinic.

Methods—

The outcome of cardiovascular investigations in 200 patients with stroke/transient ischemic attack diagnosed in a stroke prevention clinic was assessed. Transthoracic echocardiography (TTE) was assessed for detection of thrombus or mass, poor left ventricle function, and other structural abnormalities. ECG and Holter monitor were felt to be relevant if they showed atrial fibrillation/flutter. Investigations were deemed to be clinically pertinent if they brought about a shift treatment paradigm.

Results—

TTE and Holter were performed in >70% of cases and accounted for ≈94% of total cardiovascular cost. Relevant TTE findings were identified in 6 (4%) patients, which did not alter antithrombotic therapy. Only 2 new cases of atrial fibrillation were identified by both ECG and Holter.

Conclusions—

TTE and Holter appear to be costly low-yield procedures in this clinical setting. Prospective analyses may help to provide cost effective criteria for selection of appropriate cardiovascular studies in stroke management.
Nitric Oxide Synthase Isoforms Undertake Unique Roles During Excitotoxicity
Authors: Parathath Susana R. , Gravanis Iordanis , Tsirka Stella E.
Published: April 2007

Background and Purpose—Excitotoxicity is a component of many neurodegenerative diseases. The signaling events that lead from excitotoxic injury to neuronal death remain incompletely defined. Pharmacological approaches have shown that nitric oxide production is critical for the progression of neurodegeneration after the initiation of excitotoxicity by the glutamate analog kainate. Although nitric oxide additionally triggers blood–brain barrier (BBB) breakdown, the breakdown does not in itself inevitably lead to neuronal cell death, because neuroprotective pharmacological means can be used subsequently to prevent the neural death.

Methods—In this study, we use a genetic approach to analyze the contribution of 3 nitric oxide synthase (NOS) isoforms, neuronal NOS, endothelial NOS, and inducible NOS, to neurodegeneration and BBB breakdown in this setting.

Results—We find that neuronal NOS is critical for the progression of kainate-stimulated neurodegeneration, whereas endothelial NOS is required only for BBB breakdown. Inducible NOS is not required for either event.

Conclusions—The observation that endothelial NOS-deficient mice undergo excitotoxic neurodegeneration in the absence of BBB breakdown unlinks the two processes. These findings suggest that it may be possible to achieve full amelioration of excitotoxic-triggered neurodegeneration through developing isoform-specific inhibitors solely for neuronal NOS.
Validation of an Acute Ischemic Stroke Model
Authors: Johnston Karen C. , Wagner Douglas P. , Wang Xin-Qun , Newman George C. , Thijs Vincent , Sen Souvik , Warach Steven
Published: April 2007

Background and Purpose—

Prediction models for ischemic stroke outcome have the potential to contribute prognostic information in the clinical and/or research setting. The importance of diffusion-weighted magnetic resonance imaging (DWI) in the prediction of clinical outcome, however, is unclear. The purpose of this study was to combine acute clinical data and DWI lesion volume for ischemic stroke patients to determine whether DWI improves the prediction of clinical outcome.

Methods—

Patients (N=382) with baseline DWI data from the Glycine Antagonist In Neuroprotection and citicoline (010 and 018) trials were used to develop the prediction models by multivariable logistic regression. Data from prospectively collected patients (N=266) from the Acute Stroke Accurate Prediction Study were used to externally validate the model equations. The models predicted either full recovery or nursing home-level disability/death, as defined by the National Institutes of Health Stroke Scale, Barthel Index, or modified Rankin Scale.

Results—

The full-recovery models with DWI lesion volume had areas under the receiver operating characteristic curves (AUCs) of 0.799 to 0.821, and those without DWI lesion volume had AUCs of 0.758 to 0.798. The nursing home-level disability/death models with DWI had AUCs of 0.832 to 0.882, and those without DWI had AUCs of 0.827 to 0.867. All models had mean absolute errors ≤0.4 for calibration.

Conclusions—

All 12 models had excellent discrimination and calibration, with 8 of 12 meeting prespecified performance criteria (AUC ≥0.8, mean absolute error ≤0.4). Although DWI lesion volume significantly increased model explanatory power, the magnitude of increase was not large enough to be clinically important.
Willingness for Continued Social Commitment
Authors: Montada Leo , Kals Elisabeth , Becker Ralf
Published: April 2007

This article validates that the willingness for continued commitment (WCC) is a predictor for manifest action, situated within the theory of continued social commitment and based on a longitudinal study ( N = 204) on pollution control. The authors found that the predictive power of WCC can be increased further by taking into account volitional aspects of behavior, including means, aims, and contexts—categories derived from the rubicon Model of Action. In previous research, the authors had found that WCC to proenvironmental behavior depends mainly on a set of cognitive appraisals and emotions related to norms and responsibilities. In the present study ( N = 558), the authors show WCC to mediate most of the effects of these responsibility and norm-related predictors and to interact with situational and social context factors in predicting manifest behavior. The authors conclude by discussing theoretical and practical implications of these findings for explaining and influencing proenvironmental behavior.