bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiofrequency power deposition utilizing thermal imaging
Authors: Cline Harvey , Mallozzi Richard , Li Zhu , McKinnon Graeme , Barber William
Published: May 2004

Wavelength effects influence radiofrequency (RF) power deposition distributions and limit magnetic resonance (MR) medical applications at very high magnetic fields. The power depositions in spherical saline gel phantoms were deduced from proton resonance shift thermal maps at both 1.5 T and 3.0 T over a range of conductivities. Phase differences before and after RF heating were measured for both a quadrature head coil and a circular surface coil. A long echo time (TE) pulse sequence with a 3D phase unwrap algorithm provided increased thermal sensitivity. The measured thermal maps agreed with a model of eddy‐current heating by circularly polarized oscillating RF fields in a conducting dielectric sphere. At 3.0 T, thermal maps were acquired with a <0.32°C temperature rise at 4 W. Proton resonance shift thermal maps provided a measure of hot spots in very‐high‐field MR imaging (MRI), in which both the phase sensitivity and signal‐to‐noise ratio (SNR) were increased. The method provides a means of studying the heat distribution generated by RF coils excited by clinical pulse sequences. Magn Reson Med 51:1129–1137, 2004. © 2004 Wiley‐Liss, Inc.
Lactate isotopomer analysis by 1H NMR spectroscopy: Consideration of long‐range nuclear spin–spin interactions
Authors: Lloyd Steven G. , Zeng Huadong , Wang PeiPei , Chatham John C.
Published: May 2004

Lactate is a key metabolite and its rates of cellular uptake and release, its production rates from glucose and glycogen, and its interconversion rate with pyruvate are important determinants of cellular energy production. If lactate precursors such as pyruvate and glucose are labeled appropriately with 13C, 1H NMR spectroscopy provides a means of quantifying lactate production from each source and allows measurement of all these rates within a single experiment. However, due to the multiplicities of the resonance lines (from nuclear spin–spin couplings) in lactate 13C isotopomers, the 1H NMR spectra were found to be more complex than expected, requiring determination of all spin–spin interactions in this anion. All such values were determined for lactate and its precursor pyruvate. The method was then applied to simultaneously measure the rates of exogenous lactate uptake and rates of release of glucose‐, glycogen‐, and pyruvate‐derived lactate in the isolated perfused rat heart. Magn Reson Med 51:1279–1282, 2004. © 2004 Wiley‐Liss, Inc.
Fast frequency mapping with balanced SSFP: Theory and application to proton‐resonance frequency shift thermometry
Authors: Scheffler Klaus
Published: May 2004

A method is presented for the rapid acquisition of frequency maps based on multiecho balanced steady‐state free precession (balanced SSFP, fast imaging with steady precession (True FISP), fast imaging employing steady‐state excitation (FIESTA), or balanced fast field echo (FFE)). This technique was applied to measure temperature changes within a gel phantom based on the temperature‐sensitive water proton‐resonance frequency. The frequency was determined as the slope of a linear fit of the phases measured at different TEs along the echo train. The signal‐to‐noise ratio (SNR) of multiecho SSFP was analyzed for different parameters, such as relaxation times and flip angle, as well as for different local field inhomogeneities. The theoretical and experimental results were compared with results from the established multiecho fast low‐angle shot (FLASH) method. Depending on the given tissue parameters, a significant increase in the accuracy of the frequency/temperature shift estimation compared to FLASH was observed. Furthermore, balanced SSFP can be used with very short TRs without generating a saturation‐related signal loss, which is essential for real‐time temperature mapping. Magn Reson Med 51:1205–1211, 2004. © 2004 Wiley‐Liss, Inc.
T2 of articular cartilage in the presence of Gd‐DTPA2−
Authors: Nieminen Miika T. , Menezes Nina M. , Williams Ashley , Burstein Deborah
Published: May 2004

T2 information and delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) are both used to characterize articular cartilage. They are currently obtained in separate studies because Gd‐DTPA2− (which is needed for dGEMRIC) affects the inherent T2 information. In this study, T2 was simulated and then measured at 8.45 T in 20 sections from two human osteochondral samples equilibrated with and without Gd‐DTPA2−. Both the simulations and data demonstrated that Gd‐DTPA2− provides a non‐negligible mechanism for relaxation, especially with higher (1 mM) equilibrating Gd‐DTPA2− concentrations, and in areas of tissue with high T2 (due to weak inherent T2 mechanisms) and high tissue Gd‐DTPA2− (due to a low glycosaminoglycan concentration). Nonetheless, T2‐weighted images of cartilage equilibrated in 1 mM Gd‐DTPA2− showed similar T2 contrast with and without Gd‐DTPA2−, demonstrating that the impact on T2 was not great enough to affect identification of T2 lesions. However, T2 maps of the same samples showed loss of conspicuity of T2 abnormalities. We back‐calculated inherent T2's (T2,bc) using a T2‐relaxivity value from a 20% protein phantom (r2 = 9.27 ± 0.09 mM−1s−1) and the Gd‐DTPA2− concentration calculated from T1,Gd. The back‐calculation restored the inherent T2 conspicuity, and a correlation between T2 and T2,bc of r = 0.934 (P < 0.0001) was found for 80 regions of interest (ROIs) in the sections. Back‐calculation of T2 is therefore a viable technique for obtaining T2 maps at high equilibrating Gd‐DTPA2− concentrations. With T2‐weighted images and/or low equilibrating Gd‐DTPA2− concentrations, it may be feasible to obtain both T2 and dGEMRIC information in the presence of Gd‐DTPA2− without such corrections. These conditions can be designed into ex vivo studies of cartilage. They appear to be applicable for clinical T2 studies, since pilot clinical data at 1.5 T from three volunteers demonstrated that calculated T2 maps are comparable before and after “double dose” Gd‐DTPA2− (as utilized in clinical dGEMRIC studies). Therefore, it may be possible to perform a comprehensive clinical examination of dGEMRIC, T2, and cartilage volume in one scanning session without T2 data correction. Magn Reson Med 51:1147–1152, 2004. © 2004 Wiley‐Liss, Inc.
Neuroprotective effects of an immunosuppressant agent on diffusion/perfusion mismatch in transient focal ischemia
Authors: Ebisu Toshihiko , Mori Yuuki , Katsuta Kiyotaka , Fujikawa Akihiko , Matsuoka Nobuya , Aoki Ichio , Umeda Masahiro , Naruse Shoji , Tanaka Chuzo
Published: May 2004

The immunosuppressant FK506 (tacrolimus) exerts potent neuroprotection following focal ischemia in animals; however, the separate effects of FK506 on the ischemic core and penumbra have not been reported. The ischemic penumbra is clinically defined as the difference between a large abnormal area on perfusion‐weighted imaging (PWI) and a smaller lesion on diffusion‐weighted imaging (DWI). The goal of this study was to determine the effect of FK506 on DWI/PWI match and mismatch areas in transient focal ischemia in rats. Twelve rats were subjected to 1 hr of transient middle cerebral artery (MCA) occlusion, and given an intravenous injection of a placebo (N = 6) or 1 mg/kg FK506 (N = 6) immediately before reperfusion. Magnetic resonance imaging (MRI) was performed during MCA occlusion, and 0.5, 1, and 24 hr after reperfusion. FK506 significantly protected the ischemic brain only in the mismatch cortex where the initial apparent diffusion coefficient (ADC) was normal and there was a mild reduction of cerebral blood flow (CBF). This is the first report to describe the protective effects of FK506 on ischemic penumbra, as measured by DWI/PWI mismatch. The findings provide direct evidence for the utility of DWI/PWI mismatch as a guideline for therapeutic intervention with FK506. Magn Reson Med 51:1173–1180, 2004. © 2004 Wiley‐Liss, Inc.
Acute cerebral ischemia in rats studied by Carr‐Purcell spin‐echo magnetic resonance imaging: Assessment of blood oxygenation level‐dependent and tissue effects on the transverse relaxation
Authors: Kavec Martin , Gröhn Olli H.J. , Kettunen Mikko I. , Silvennoinen M. Johanna , Garwood Michael , Kauppinen Risto A.
Published: May 2004

Acute cerebral ischemia has been shown to be associated with an enhanced transverse relaxation rate in rat brain parenchyma, chiefly due to the blood oxygenation level‐dependent (BOLD) effect. In this study, Carr‐Purcell R2 (CP R2), acquired both with short and long time intervals between centers of adiabatic π‐pulses (τCP), was used to assess the contributions of BOLD and tissue effects to the transverse relaxation in two brain ischemia models of rat at 4.7 T. R1ρ and diffusion MR images were also acquired in the same animals. During the first minutes of global ischemia, the long τCP R2 in brain parenchyma increased, whereas the short τCP R2 was unchanged. Based on the simulations, and using constraints of intravascular BOLD effect on parenchymal R2, the former observation was ascribed to be due to susceptibility changes arising in the extravascular compartment. R1ρ declined almost immediately after the onset of focal cerebral ischemia, and further declined during the evolution of ischemic damage. Interestingly, short τCP CP R2 started to decline after some 20 min of focal ischemia and declined over a time course similar to that of R1ρ, indicating that it may be an MRI marker for irreversible tissue changes in cerebral ischemia. The present results show that CP R2 MRI can reveal both tissue‐ and blood‐derived contrast changes in acute cerebral ischemia. Magn Reson Med 51:1138–1146, 2004. © 2004 Wiley‐Liss, Inc.
In vitro release of vascular endothelial growth factor from gadolinium‐doped biodegradable microspheres
Authors: Faranesh Anthony Z. , Nastley Monet T. , Perez de la Cruz Cristina , Haller Michael F. , Laquerriere Patrice , Leong Kam W. , McVeigh Elliot R.
Published: May 2004

A drug delivery vehicle was constructed that could be visualized noninvasively with MRI. The biodegradable polymer poly(DL‐lactic‐co‐glycolic acid) (PLGA) was used to fabricate microspheres containing vascular endothelial growth factor (VEGF) and the MRI contrast agent gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA). The microspheres were characterized in terms of size, drug and contrast agent encapsulation, and degradation rate. The PLGA microspheres had a mean diameter of 48 ± 18 μm. The gadolinium loading was 17 ± 3 μg/mg polymer and the VEGF loading was 163 ± 22 ng/mg polymer. Electron microscopy revealed that the Gd was dispersed throughout the microspheres and it was confirmed that the Gd loading was sufficient to visualize the microspheres under MRI. VEGF and Gd‐DTPA were released from the microspheres in vitro over a period of ∼6 weeks in three phases: a burst, followed by a slow steady‐state, then a rapid steady‐state. Biodegradable Gd‐doped microspheres can be effectively used to deliver drugs in a sustained manner, while being monitored noninvasively with MRI. Magn Reson Med 51:1265–1271, 2004. Published 2004 Wiley‐Liss, Inc.
Removal of EPI Nyquist ghost artifacts with two‐dimensional phase correction
Authors: Chen Nan‐kuei , Wyrwicz Alice M.
Published: May 2004

Odd–even echo inconsistencies result in Nyquist ghost artifacts in the reconstructed EPI images. The ghost artifacts reduce the image signal‐to‐noise ratio and make it difficult to correctly interpret the EPI data. In this article a new 2D phase mapping protocol and a postprocessing algorithm are presented for an effective Nyquist ghost artifacts removal. After an appropriate k‐space data regrouping, a 2D map accurately encoding low‐ and high‐order phase errors is derived from two phase‐encoded reference scans, which were originally proposed by Hu and Le (Magn Reson Med 36:166–171;1996) for their 1D nonlinear correction method. The measured phase map can be used in the postprocessing algorithm developed to remove ghost artifacts in subsequent EPI experiments. Experimental results from phantom, animal, and human studies suggest that the new technique is more effective than previously reported methods and has a better tolerance to signal intensity differences between reference and actual EPI scans. The proposed method may potentially be applied to repeated EPI measurements without subject movements, such as functional MRI and diffusion coefficient mapping. Magn Reson Med 51:1247–1253, 2004. © 2004 Wiley‐Liss, Inc.
Prolonged T values in newborn versus adult brain: Implications for fMRI studies of newborns
Authors: Rivkin M.J. , Wolraich D. , Als H. , McAnulty G. , Butler S. , Conneman N. , Fischer C. , Vajapeyam S. , Robertson R.L. , Mulkern R.V.
Published: May 2004

The neonatal brain possesses higher water content, lower macromolecular concentration, and reduced synaptic density than is found in the brain of a 1‐year‐old child. Changes in MRI characteristics of brain such as relaxation times accompany rapid changes in brain during early postnatal development. It was hypothesized that T values found in newborns would be significantly higher than those found in 9‐month‐old children and adults as measured at 1.5 T. Spoiled gradient echo measurements of T within the brains of newborns, 9‐month‐olds, and adults confirmed this hypothesis. The results have implications with regard to functional MRI studies in newborns since, in general, BOLD signal optimization is achieved when echo times TE are set equal to the T values of the tissue of interest. Since significantly longer T values are found in newborns, it is suggested that the TE values employed for fMRI studies of newborns should be increased to maximize BOLD signal intensity changes and improve the overall reliability of fMRI results in newborns. Magn Reson Med 51:1287–1291, 2004. © 2004 Wiley‐Liss, Inc.
A fast integral approach for drag force calculation due to oscillatory slip stokes flows
Authors: Ding Jian , Ye Wenjing
Published: May 2004

In this paper, we describe an efficient numerical method for modelling oscillatory incompressible slip Stokes flows in three dimensions. The efficiency is achieved by employing an integral approach combined with an accelerated boundary‐element‐method (BEM) solver. First the integral representations for slip flows with two different slip models are formulated. The resulting integral equations are then solved using the BEM combined with the precorrected‐FFT accelerated technique. 3D numerical codes have been developed based on the method described above. These codes are then used to calculate the drag forces on oscillating objects immersed in an unbounded slip flow. Three objects are considered, namely a sphere, a pair of plates and a comb structure. The simulated drag forces on these objects obtained from the two slip models are compared. In the sphere case, the simulated results are also compared with the analytical solutions for both the steady‐state case and the no‐slip oscillatory case and are found to be in good agreement. In addition, qualitative comparison of the simulation results with the experimental results in the plate problem is also presented in this paper. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of transfer procedures in elastoplasticity based on the error in the constitutive equations: Theory and numerical illustration
Authors: Orlando A. , Perić D.
Published: May 2004

The aim of this work is to illustrate a methodology for the assessment of adaptive strategies for the solution of associative rate‐independent plasticity problems solved by employing the incremental displacement conforming finite element method. This is the first step towards a more rational definition of transfer operators in terms of the ensuing error. The motivating idea is the observation that change of data and/or finite element mesh from one time interval to the other can be both related to a discontinuity jump of the approximate solution across the time instant tn. Thus, reliable a posteriori estimates will have to depend not only on the time step and finite element mesh size but also on the value of the jump. A new error estimate based on the error in the constitutive equations is developed which allows characterization of the discontinuity jump. Copyright © 2004 John Wiley & Sons, Ltd.
Mesh‐free radial point interpolation method for the buckling analysis of Mindlin plates subjected to in‐plane point loads
Authors: Liew K. M. , Chen X. L.
Published: May 2004

In this paper, a mesh‐free approach is employed for buckling analysis of Mindlin plates that are subjected to in‐plane point loads. The radial point interpolation method (RPIM) is used to approximate displacements based on nodes. Variational forms of the system equations are established. Two‐step solution procedures are implemented. The non‐uniform pre‐stress distribution of plate is first obtained using the RPIM based on a two‐dimensional (2D) elastic plane stress problem. This predetermined non‐uniform pre‐stress distribution is then used to compute buckling loads of plate using the RPIM based on Mindlin's plate assumption. The RPIM can easily handle any number and location of nodes in the plate domain for a desired computational accuracy without major difficulties in solving the initial stresses and buckling loads. Numerical examples considered here include circular and rectangular Mindlin plates that are subjected to in‐plane uniform and point loads with different aspect ratios and boundary conditions. The present results are validated against the available analytical and numerical solutions. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and hydrolytic degradation of a random copolymer derived from 1,4‐dioxan‐2‐one and glycolide
Authors: Bhattarai Narayan , Jiang Wen Ying , Kim Hak Yong , Lee Douck Rae , Park Soo Jin
Published: May 2004

Novel biodegradable copolymers, poly(1,4‐dioxan‐2‐one‐co‐glycolide) [P(DON‐co‐GA)] containing a high proportion of 1,4‐dioxan‐2‐one (DON), were synthesized by copolymerizations of DON and glycolide (GA) at 120 °C for 16 h using stannous octoate as catalyst. Chemical composition and microstructural variation of the resulting copolymer were investigated by 1H‐ and 13C NMR and thermal properties by differential scanning calorimetry (DSC). From the 13C NMR spectra, it was observed that, apart from the expected preponderance of DON sequences, the minor component, GA, was indeed distributed at various points along the copolymer chain rather than incorporated as distinct blocks, which is consistent with a random sequence distribution. This view also was supported by the DSC results, which showed that most copolymers were amorphous except for one with a relatively high fraction of DON. The conclusion that it was a random structure rather than a statistical copolymer is discussed, using the theories about the mechanism of this type of polymerization in current as a reference. P(DON‐co‐GA) films were prepared by casting the copolymer solution in hexafluoroisopropanol (HFIP) with two concentrations of the polymeric solution (10 and 25 wt %). The in vitro hydrolytic degradation behaviors of these films were studied in phosphate buffer solution (pH = 7.4) at 37 °C and characterized by DSC, scanning electron microscopy, weight loss, and change in inherent viscosity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2558–2566, 2004
CF: An X‐ray database to assess effect of aerosolized tobramycin
Authors: Slattery Dubhfeasa M. , Zurakowski David , Colin Andrew A. , Cleveland Robert H.
Published: May 2004

This paper assesses the effectiveness of aerosolized tobramycin (TOBI) on cystic fibrosis (CF) lung disease, using a radiologic tool. The published tool, the age‐based severity curve (ABS), is derived from Brasfield scoring of chest X‐rays (CXR). This study evaluates both the usefulness of the ABS as an assessment tool and the effectiveness of TOBI. Thirty‐eight patients were treated with TOBI. Twenty‐four treated with dornase alfa were excluded. Fourteen patients, aged 2 months to 22 years (mean, 17 months of TOBI treatment), comprised the study group. Radiographs were obtained over a mean of 7.8 years (SD = 6.5 years; range, 9 months–18 years). Two hundred and eighty‐two CXR of TOBI patients were analyzed following the ABS protocol. Rate of decline in radiologic status of the TOBI group and ABS were compared. Also, TOBI was assessed by comparing rate of decline before and after initiation of treatment. The TOBI group's radiologic assessment was compared to its rate of decline in pulmonary function studies and published population data. Rate of decline in ABS was 0.175 Brasfield points/year vs. 0.150 points/year in the TOBI group (P < 0.001). Before treatment, the TOBI group's rate of decline was 0.169 Brasfield points/year; after treatment, it was 0.150 points/year (P = 0.02). Forced vital capacity revealed a statistically significant slowing in rate of decline on TOBI. Although not statistically significant, rate of decline in forced expiratory volume at 1 sec showed a similar trend. The degree of slowing in decline is similar to that previously reported for pulmonary function studies. Pediatr Pulmonol. 2004; 38:23–30. © 2004 Wiley‐Liss, Inc.
Inspired gas temperature in ventilated neonates
Authors: Davies Mark William , Dunster Kimble Robert , Cartwright David William
Published: May 2004

The warming and humidification of inspired gases for ventilated neonates are routine. There are no data on the temperature of the gas at the airway opening in ventilated neonates. Is the inspired gas temperature at the airway opening, as expected and set on the humidifier, around 37°C? We aimed to measure temperature at the airway opening and compare this with the circuit temperature. This was an observational study in a neonatal intensive care unit. Twenty‐five mechanically ventilated infants were studied. All had humidifiers with chamber temperature set at 36°C and the circuit temperature set at 37°C. Two temperature probes were inserted and rested at the circuit‐exit and at the airway opening, and temperatures were measured for 2 min in each infant. At this time, the circuit temperature was also noted. The mean (SD) temperature at the airway opening in infants nursed in incubators was 34.9 (1.2)°C, compared with radiant warmers where the mean (SD) was 33.1 (0.5)°C. The mean (SD) difference in temperature from the circuit temperature probe to the airway opening was greater under radiant warmers, with a mean (SD) drop of 3.9 (0.6)°C compared with a mean (SD) drop of 2.0 (1.3)°C in the incubators. In conclusion, the temperature at the circuit temperature probe does not reflect the temperature at the airway opening. Inspired gas temperatures are lower than the expected 37°C with the normal circuits and usual humidifier settings. Pediatr Pulmonol. 2004; 38:50–54. © 2004 Wiley‐Liss, Inc.
Randomized, double‐blinded trial of low‐dose dexamethasone: II. Functional residual capacity and pulmonary outcome in very low birth weight infants at risk for bronchopulmonary dysplasia
Authors: McEvoy Cindy , Bowling Susan , Williamson Kathleen , McGaw Pam , Durand Manuel
Published: May 2004

We previously reported on a 7‐day course of dexamethasone starting at 0.5 mg/kg/day in intubated very low birth weight (VLBW) infants, 7–14 days of age, with increased dynamic pulmonary compliance and decreased bronchopulmonary dysplasia (BPD). The effect of low‐dose dexamethasone on functional residual capacity (FRC) in VLBW infants is unknown. The objective of this study was to compare the effect of two regimens of moderately early dexamethasone on FRC and passive respiratory compliance (Crs) in VLBW infants at risk for BPD. Sixty‐two intubated VLBW infants were randomized (double‐blinded) at 7–21 days of age; 29 patients (mean birth weight, 839 g) received “high” dose dexamethasone (0.5 mg/kg/day for 3 days, 0.25 mg/kg/day for 3 days, and 0.1 mg/kg/day on day 7, total dose of 2.35 mg/kg), and 33 infants (mean birth weight, 830 g) received “low‐dose” dexamethasone (0.2 mg/kg/day for 3 days and 0.1 mg/kg/day for 4 days, total dose of 1 mg/kg). FRC and Crs were measured with the nitrogen washout technique and single breath occlusion technique, before and on days 2, 5, and 7 of therapy. Clinical outcome and early neurodevelopmental follow‐up were evaluated. FRC significantly increased in the high‐dose (19.3 ml/kg at baseline to 34 ml/kg on day 7; P < 0.001) and low‐dose (18.1 ml/kg at baseline to 30.3 ml/kg on day 7; P < 0.001) dexamethasone groups when compared to baseline. There was a significant increase in Crs and a decrease in FiO2 within each group. The improvements in FRC and Crs were comparable between groups, and specific compliances (Crs/FRC) were not different. There were no significant differences in other clinical outcome parameters, including BPD and neurodevelopmental outcome. In conclusion, there are significant increases in FRC during a 7‐day course of moderately early dexamethasone in VLBW infants. The lower total dose (1 mg/kg) appears as effective as the higher total dose of dexamethasone (2.35 mg/kg) in increasing FRC. Comparable significant increases in Crs were observed in both groups of infants. Additional long‐term follow‐up is underway. Pediatr Pulmonol. 2004; 38:55–63. © 2004 Wiley‐Liss, Inc.
Dietary intake, physical activity, body mass index, and childhood asthma in the third national health and nutrition survey (NHANES III)
Authors: Romieu Isabelle , Mannino David M. , Redd Stephen C. , McGeehin Michael A.
Published: May 2004

Childhood asthma may be affected by dietary changes and increased body mass related to a sedentary lifestyle, although the mechanisms are poorly understood. To test this hypothesis, we used data from the National Health and Nutrition Survey (NHANES III) from 1988–1994, including 7,904 children. We analyzed cross‐sectional information on body mass index (BMI = weight/height2), physical activity (hr/day viewing television), dietary intake (24‐hr recall), and vitamin C intake (60 mg/day). The probability of self‐reported asthma or wheezing relating to risk factors was calculated by logistic regression. After controlling for dietary intake, physical activity, and sociodemographic variables, asthma risk was three times higher for children aged 6–16 years in the highest percentiles of BMI (>95th percentile) when compared to children in percentiles 25–49 (OR = 3.44; 95% CI, 1.49–7.96). No increase was observed in children aged 2–5 years. Low vitamin C intake was marginally related to self‐reported current wheezing in children aged 6–16 years. Our results show that increased BMI may influence asthma prevalence in children, but further investigation is needed. Pediatr Pulmonol. 2004; 38:31–42. © 2004 Wiley‐Liss, Inc.
Partial alanine scan of mast cell degranulating peptide (MCD): importance of the Histidine‐ and Arginine residues
Authors: Buku Angeliki , Mendlowitz Milton , Condie Barry A. , Price Joseph A.
Published: May 2004

The influence of the two histidine and two arginine residues of mast cell degranulating peptide (MCD) in activity and binding was studied by replacing these amino acids in the MCD sequence with L‐alanine. Their histamine releasing activity was determined on rat peritoneal mast cells. Their binding affinity to the FcεRIα binding subunit of the human mast cell receptor protein, was carried out using fluorescence polarization. The histamine assay showed that replacement of His13 by Ala occurred without loss of activity compared with the activity of MCD. Alanine substitutions for Arg7 and His8 resulted in an approximately 40‐fold increase, and for Arg16 in a 14‐fold increase in histamine‐releasing activity of MCD. The binding affinities of the analogs were tested by competitive displacement of bound fluorescent MCD peptide from the FcεRIα binding protein of the mast cell receptor by the Ala analogs using fluorescence polarization. The analogs Ala8 (for His) and Ala16 (for Arg) showed the same binding affinities as MCD, whereas analog Ala7 (for Arg) and analog Ala13 (for His) showed slightly better binding affinity than the parent compound. This study showed that the introduction of alanine residues in these positions resulted in MCD agonists of diverse potency. These findings will be useful in further MCD structure–activity studies. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
A study of a Cα, β‐didehydroalanine homo‐oligopeptide series in the solid‐state by 13C cross‐polarization magic angle spinning NMR
Authors: Henzler Wildman Katherine A. , Ramamoorthy Ayyalusamy , Wakamiya Tateaki , Yoshikawa Taichi , Crisma Marco , Toniolo Claudio , Formaggio Fernando
Published: May 2004

The fully extended peptide conformation (2.05‐helix) has been investigated for the first time in the solid‐state by 13C cross‐polarization magic angle spinning NMR. The compounds examined are members of a terminally protected, homo‐oligopeptide series (from monomer through hexamer) based on Cα, β‐didehydroalanine. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Prediction of antibiotic activity and synthesis of new pentadecapeptides based on lactoferricins
Authors: Lejon Tore , Stiberg Trine , Strøm Morten B. , Svendsen John S.
Published: May 2004

The antibacterial activity against Escherichia coli and Staphylococcus aureus has been studied for a number of modified pentadecapeptides based on lactoferricins of different origin. The peptides were classified by multivariate methods and quantitative structure–activity relationships (QSAR) were developed using theoretically derived variables for the amino acids. For the modified peptides based on bovine lactoferricin (LFB) a model was calculated and used for prediction of new peptides that were then tested for antibacterial activity in order to improve peptide activity and to check the validity of the model. Models were also calculated including lactoferricins of different origin. Theories of the mechanism of action of the peptides are briefly discussed. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Saponification of esters of chiral α‐amino acids anchored through their amine function on solid support
Authors: Cantel Sonia , Desgranges Stéphane , Martinez Jean , Fehrentz Jean‐Alain
Published: May 2004

Anchoring an α‐amino acid residue by its amine function onto a solid support is an alternative to develop chemistry on its carboxylic function. This strategy can involve the use of amino‐acid esters as precursors of the carboxylic function. A complete study on the Wang‐resin was performed to determine the non‐racemizing saponification conditions of anchored α‐amino esters. The use of LiOH, NaOH, NaOSi(Me)3, various solvents and temperatures were tested for this reaction. After saponification and cleavage from the support, samples were examined through their Marfey's derivatives by reversed phase HPLC to evaluate the percentage of racemization. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Quality of Information Flow in the Backend of a Product Development Process: a Case Study
Authors: Boersma Jaring , Loke Gabriel , Petkova Valia T. , Sander Peter C. , Brombacher Aarnout C.
Published: May 2004

The increasing need for products that are able to reliably deliver complex functionality with a high degree of innovation presents a major challenge to the modern day product creation processes. In order to be able to use information on the field behaviour of previous products in the design of new products, increasingly detailed information needs to be retrieved from the market in an increasingly shorter time. The purpose of this study is to analyse, in a typical case in the consumer electronics industry, whether the underlying business process is able to generate this information with adequate quality sufficiently quickly. Information models of the company's service centre and call centre were developed using the concepts of maturity index on reliability. The results showed that the structure of the information handling process resulted in a massive data loss (up to 60% of the data gathered by the service centres) and also in serious data quality degradation. Would this information have not been lost, it could have been used by development teams for preventive and corrective actions. Copyright © 2004 John Wiley & Sons, Ltd.
Effective Safety Management: a Case Study in the Chemical Industry
Authors: Sonnemans P. J. M. , Körvers P. M. W. , Brombacher A. C.
Published: May 2004

A major non‐trivial problem within the area of industrial safety management today is to analyse, next to the safety impact of the technical equipment, the safety impact of a ‘business process’ as currently required by regulation and safety standards.

This paper describes a case study of a pesticide company struggling with the question of how to improve the safety of their operational process further and at the same time also improve the reliability of their operational process. According to the literature ‘control of the business process’ is the keyword to improve the safety and reliability ‘performance’ of a company. A formal control model is proposed together with a classification system (using maturity levels) to analyse and qualify business processes with respect to their impact on process safety.

This method has been applied in a case study where it resulted in a model of a business process. Using the model it was possible to classify the business process control system used and to identify related improvement opportunities. The proposed method showed that, in contrast to the company's perception, it was not the production department that was responsible for most of the problems but the peripheral processes relating to the production department. The interaction between departments caused not only potential safety problems, but also caused system reliability problems. For the company it was demonstrated that the interdependency of the (different activities in the‐) operational process is an essential element preventing further improvement if not addressed properly. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐normal Populations in Quality Applications: a Revisited Perspective
Authors: Shore Haim
Published: May 2004

Much research effort has recently been focused on methods to deal with non‐normal populations. While for weak non‐normality the normal approximation is a useful choice (as in Shewhart control charts), moderate to strong skewness requires alternative approaches. In this short communication, we discuss the properties required from such approaches, and revisit two new ones. The first approach, for attributes data, assumes that the mean, the variance and the skewness measure can be calculated. These are then incorporated in a modified normal approximation, which preserves these moments. Extension of the Shewhart chart to skewed attribute distributions (e.g. the geometric distribution) is thus achieved. The other approach, for variables data, fit a member of a four‐parameter family of distributions. However, unlike similar approaches, sample estimates of at most the second degree are employed in the fitting procedure. This has been shown to result in a better representation of the underlying (unknown) distribution than methods based on four‐moment matching. Some numerical comparisons are given. Copyright © 2004 John Wiley & Sons, Ltd.
Minimum jerk motion planning for a prosthetic finger
Authors: Secco Emanuele L. , Visioli Antonio , Magenes Giovanni
Published: May 2004

In this paper we propose a method, based on both physiologic and engineering considerations, for the motion planning of a prosthetic finger. In particular, we exploit a minimum jerk approach to define the trajectory in the Cartesian space. Then, cubic splines are adopted in the joint space. The redundancy problem arising from the presence of three links is solved by assuming that there is a constant ratio between the second and the third joint motion. The value of the proportional constant is determined by minimizing the maximum jerk in the joint space. It is found that this constant value can be suboptimally but effectively set to one for all the movements. This approach guarantees a natural movement of the finger as well as reduced vibrations in the mechanical structure and increased control performances. © 2004 Wiley Periodicals, Inc.
Smoothing effects of distributed wind turbines. Part 2. Coherence among power output of distant wind turbines
Authors: Nanahara Toshiya , Asari Masahiro , Maejima Tsutomu , Sato Takamitsu , Yamaguchi Koji , Shibata Masaaki
Published: May 2004

Recently there has been a marked increase in wind power generation. From a power system point of view, because a wind turbine is an intermittent generator with large output fluctuation, any increase in the number of wind turbines gives rise to concerns about the adverse effects of wind turbines on power quality. The smoothing effects of wind turbine output fluctuation are of great importance in assessing the impacts of a large number of wind turbines. With regard to impacts on power system frequency (generation–demand balance), smoothing effects on a power system‐wide scale need to be examined in greater detail, because impacts of wind turbines on power system frequency are dominated by the total power output of wind turbines interconnected to the system. This article examines smoothing effects of wind power output on a power system‐wide scale. First a summary of wind measurements, in which observations were made at 16 sites, is presented. Next, correlation coefficients of wind power output of distant wind turbines are analysed; considerable differences are observed in the correlation coefficients from day to day. Then a new indicator for assessing the smoothing effects—average coherence—is introduced to resolve difficulties of conventional indicators such as coherence. Average coherence is evaluated for the measured data; the results show that smoothing effects among wind farms distributed over some hundreds of kilometres may not be so significant for periods of more than about 100 min. Copyright © 2004 John Wiley & Sons, Ltd.
Growth of putative progenitors of type II pneumocytes in culture of human cystic fibrosis alveoli
Authors: Hollande Etienne , Cantet Sylvie , Ratovo Ginette , Daste Ghislaine , Brémont Franc¸ois , Fanjul Marjorie
Published: May 2004

Summry— Alveolar type II pneumocytes are thought to be progenitor cells capable of self‐renewal and differentiation into type I pneumocytes. Nevertheless, the existence of an alveolar stem cell has been postulated. In lungs from patients with cystic fibrosis, the alveolar epithelium is damaged with ulceration and subsequent regeneration. We characterized alveolar modifications histologically and immunohistochemically in the pulmonary tissue of a patient homozygous for the ΔF508 mutation. Alveoli were of variable size and surrounded by an inflammatory infiltrate. They were lined by a continuous layer of cuboidal cells with very weak proliferative activity. These cells resembled type II pneumocytes. They expressed thyroid transcription factor‐1, cystic fibrosis transmembrane conductance regulator, cytokeratin 7 and contained lamellar bodies. Weak expression of cytokeratin 5 considered to be a marker of progenitor cells of the bronchial and bronchiolar epithelium was detected. Explantation of this alveolar epithelium produced primary cultures and subcultures of epithelial cells that had acquired proliferative properties showing signs of dedifferentiation with a loss of lamellar bodies and a lack of expression of thyroid transcription factor‐1. Persistence of the expression of cytokeratin 7 and a strong expression of cytokeratin 5 were observed. The culture conditions were thought to have circumvented the inhibition of proliferation observed in vivo due to the inflammatory peri‐alveolar environment. They thus favored the multiplication of a population of cells co‐expressing cytokeratin 5 and certain characteristics of type II pneumocytes. The presence of these cells of intermediate phenotype is indicative of the existence of immature precursors for type II pneumocytes.
The effect of eye orientation on slowly increasing pain
Authors: Naveteur Janick , Mars Franck , Crombez Geert
Published: May 2004

The present study investigated the influence of eye orientation upon the experience of pain. Quasi continuous electrocutaneous stimuli which slowly increased in intensity were delivered to 32 healthy females volunteers. Participants were instructed to direct the eyes at locations that were ipsilateral or contralateral to the stimulated hand. Unpleasantness threshold and pain threshold were significantly higher when the eyes were oriented ipsilateral towards the stimulated hand. In a second experiment phase, the pain intensity increased until tolerance. There was no effect of eye orientation upon pain threshold and tolerance. Results of the first experimental part are in line with the counterintuitive idea that selective monitoring reduces pain distress. The lack of significant results in the second experiment phase is discussed in terms of statistical power and a change in coping induced by the expectation of high intensity pain.
Opinions of mothers on the first psychotic episode and the start of treatment of their child
Authors: de Haan L. , Welborn K. , Krikke M. , Linszen D.H.
Published: May 2004

Parents, especially mothers, have a critical role in initiating psychiatric treatment for their child with first-episode schizophrenia. Knowledge of attitudes of mothers towards the illness of their child prior to psychiatric treatment and towards the start of treatment is essential for the development of interventions for reducing duration of untreated psychosis (DUP). In the present study, mothers (n = 61) of consecutively admitted patients with recent-onset schizophrenic disorders were interviewed about: their views on the nature of the symptoms at first occurrence of psychotic symptoms in their child and views on the main reason for psychiatric treatment; their perception of problems in initiating psychiatric treatment; and suggestions they might have for getting treatment started at an earlier point in time. About 57% of the mothers did not think that their child had a psychosis at first occurrence of psychotic symptoms. Most of the mothers who immediately thought that their child suffered from a psychotic disorder supposed that this disorder was caused by use of street drugs. About one-third (32.8%) of the mothers thought that the reluctance of patients to acknowledge that they needed help was the major obstacle in initiating psychiatric treatment. More than half of the mothers perceived factors related to the delivery of professional care as problems in initiating psychiatric treatment. Given the reluctance of patients to accept treatment, these problems further complicate the initiating of treatment. Mothers emphasize that a more active approach by professional caregivers could reduce treatment delay.
Patients with schizophrenia previously stabilized on conventional depot antipsychotics experience significant clinical improvements following treatment with long-acting risperidone
Authors: Lasser Robert A. , Bossie Cynthia A. , Gharabawi Georges M. , Turner Martin
Published: May 2004

Background

Conventional depot antipsychotics can provide constant pharmacologic treatment, eliminating partial compliance and reducing relapse risk. Atypical antipsychotics, have improved clinical profiles but require daily dosing, compromising their overall effectiveness. As oral risperidone provides safety and efficacy benefits over oral haloperidol, improvements may be realized by replacing conventional with atypical agents in long-acting therapy. This report examines 50-weeks of long-acting risperidone therapy in patients previously stabilized with conventional depot antipsychotics.

Methods

A multi-center, open-label study enrolled 725 patients with schizophrenia or schizoaffective disorder, judged clinically stable and maintained on stable antipsychotic doses for ≥4 weeks. Assignment by clinician judgment to receive 25–75 mg of long-acting risperidone every 2 weeks for 50 weeks followed, with performance of standard safety and efficacy assessments. Data are presented on patients receiving conventional depot antipsychotic monotherapy at study entry.

Results

In the 188 (25.9%) patients receiving conventional depot antipsychotic monotherapy at entry, mild-to-moderate mean (±S.D.) Positive and Negative Syndrome Scale (PANSS)-total scores improved significantly after receiving long-acting risperidone (64.2 ± 18.9 to 58.2 ± 20.3; P < 0.001). Clinical improvement of ≥20%, 40%, or 60% reduction in PANSS-total score, occurred in 52%, 34%, and 16% of patients, respectively. ESRS subjective ratings and objective physician ratings (Parkinsonism) decreased significantly (P < 0.001).

Conclusion

Stable patients with mild, residual symptomatology treated with conventional depot antipsychotics experienced significant improvement in psychiatric and movement disorder symptomatology following 1-year of treatment with long-acting risperidone.
RNA aptamer to thrombin binds anion‐binding exosite‐2 and alters protease inhibition by heparin‐binding serpins
Authors: Jeter Martha L , Ly Linda V , Fortenberry Yolanda M , Whinna Herbert C , White Rebekah R , Rusconi Christopher P , Sullenger Bruce A , Church Frank C
Published: May 2004

We studied the RNA aptamer Toggle‐25/thrombin interaction during inhibition by antithrombin (AT), heparin cofactor II (HCII) and protein C inhibitor (PCI). Thrombin inhibition was reduced 3‐fold by Toggle‐25 for AT and HCII, but it was slightly enhanced for PCI. In the presence of glycosaminoglycans, AT and PCI had significantly reduced thrombin inhibition with Toggle‐25, but it was only reduced 3‐fold for HCII. This suggested that the primary effect of aptamer binding was through the heparin‐binding site of thrombin, anion‐binding exosite‐2 (exosite‐2). We localized the Toggle‐25 binding site to Arg 98, Glu 169, Lys 174, Asp 175, Arg 245, and Lys 248 of exosite‐2. We conclude that a RNA aptamer to thrombin exosite‐2 might provide an effective clinical reagent to control heparin's anticoagulant action.
Simulating the effect of alcohol on the structure of a membrane
Authors: Kranenburg Marieke , Smit Berend
Published: May 2004

Adsorption of alcohol molecules or other small amphiphilic molecules in the cell membrane can induce significant changes in the structure of the membrane. To understand the molecular mechanisms underlying these structural changes, we developed a mesoscopic membrane model. Molecular simulations on this model nicely reproduce the experimental phase diagrams. We find that alcohol can induce an interdigitated structure in which the normal bilayer structure changes into a monolayer in which the alcohol molecules screen the hydrophobic tails from the water phase. We compute the effect of the chain length of the alcohol on the phase behaviour of the membrane. At low concentrations of alcohol, the membrane has domains of the interdigitated phase that are in coexistence with the normal membrane phase. We use our model to clarify some of the experimental questions related to the structure of the interdigitated phase and put forward a simple model that explains the alcohol chain length dependence of the stability of this interdigitated phase.
Voltage‐gated sodium channel expressed in cultured human smooth muscle cells: involvement of SCN9A
Authors: Jo Taisuke , Nagata Taiji , Iida Haruko , Imuta Hiroyuki , Iwasawa Kuniaki , Ma Ji , Hara Kei , Omata Masao , Nagai Ryozo , Takizawa Hajime , Nagase Takahide , Nakajima Toshiaki
Published: May 2004

Voltage‐gated Na+ channel (INa) is expressed under culture conditions in human smooth muscle cells (hSMCs) such as coronary myocytes. The aim of this study is to clarify the physiological, pharmacological and molecular characteristics of INa expressed in cultured hSMCs obtained from bronchus, main pulmonary and coronary artery. INa, was recorded in these hSMCs and inhibited by tetrodotoxin (TTX) with an IC50 value of approximately 10 nM. Reverse transcriptase/polymerase chain reaction (RT‐PCR) analysis of mRNA showed the prominent expression of transcripts for SCN9A, which was consistent with the results of real‐time quantitative RT‐PCR. These results provide novel evidence that TTX‐sensitive Na+ channel expressed in cultured hSMCs is mainly composed of Nav1.7.