bluuebunny/crossref_metadata_2025 huggingface dataset:
A second order discontinuous Galerkin method for advection on unstructured triangular meshes
Authors: Geijselaers H. J. M. , Huétink J.
Published: April 2003

In this paper the advection of element data which are linearly distributed inside the elements is addressed. Across element boundaries the data are assumed discontinuous. The equations are discretized by the Discontinuous Galerkin method. For stability and accuracy at large step sizes (large values of the Courant number), the method is extended to second order. Furthermore the equations are enriched with selective implicit terms. This results in an explicit and local advection scheme, which is stable and accurate for Courant numbers less than .95 on unstructured triangle meshes. Results are shown of some pure advection test problems. Copyright © 2003 John Wiley & Sons, Ltd.
A simple formulation for two‐dimensional contact problems using a moving friction cone
Authors: Wriggers P. , Haraldsson A.
Published: April 2003

In this paper a simple finite element formulation for two‐dimensional frictional contact problems undergoing large deformations is presented. It is equivalent to the standard node‐to‐segment interpolation but it leads to a less complicated matrix formulation and hence is on one hand more efficient and on the other hand easier to implement. Copyright © 2003 John Wiley & Sons, Ltd.
Munsell reflectance spectra represented in three‐dimensional Euclidean space
Authors: Romney A. Kimball , Indow Tarow
Published: April 2003

In this article we describe the results of an investigation into the extent to which the reflectance spectra of 1269 matt Munsell color chips are well represented in low dimensional Euclidean space. We find that a three dimensional Euclidean representation accounts for most of the variation in the Euclidean distances among the 1269 Munsell color spectra. We interpret the three dimensional Euclidean representation of the spectral data in terms of the Munsell color space. In addition, we analyzed a data set with a large number of natural objects and found that the spectral profiles required four basis factors for adequate representation in Euclidean space. We conclude that four basis factors are required in general but that in special cases, like the Munsell system, three basis factors are adequate for precise characterization. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 182–196, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10144
Grain positioning using metal imprint technology for single‐grain Si thin‐film transistor
Authors: Makihira Kenji , Yoshii Masahito , Asano Tanemasa
Published: April 2003

We prepared a large‐grain silicon thin film by a new solid‐phase crystallization technology called metal imprint technology, fabricated a prototype of a quasi‐single‐crystal silicon (Si) thin‐film transistor (TFT), and evaluated its performance. Metal imprint technology presses a chip array coated by metal onto amorphous silicon and promotes the nucleation in solid‐phase crystallization by the metal transferred to a small area. By using nickel (Ni) in the imprinting, we found that the incubation time could be significantly decreased, and large grains could be formed at any desired positions. The grains we obtained had a <111> orientation. An average 7‐µm grain size was obtained by annealing at 560 °C. This technology was used to fabricate TFT that positioned the channel region in a single grain. The fabricated TFT exhibited excellent performance in the field effect mobilities of 400 cm2/Vs in the n‐channel and 220 cm2/Vs in the p‐channel. We found that dispersion in mobility of TFTs could be reduced to one‐half of the dispersion of polycrystalline‐Si TFT that was crystallized in the conventional solid phase. Threshold voltages had excellent uniformity and were about one‐half of those of a conventional solid‐phase crystallized TFT. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(5): 45–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10099
Shock‐capturing with natural high‐frequency oscillations
Authors: Zhou Y. C. , Gu Yun , Wei G. W.
Published: April 2003

This paper explores the potential of a newly developed conjugate filter oscillation reduction (CFOR) scheme for shock‐capturing under the influence of natural high‐frequency oscillations. The conjugate low‐ and high‐pass filters are constructed based on the principle of the discrete singular convolution (DSC), a local spectral method. The accuracy and resolution of the DSC basic algorithm are accessed with a one‐dimensional advection equation. Two Euler systems, the advection of an isotropic vortex flow and the interaction of shock–entropy wave are utilized to demonstrate the utility of the CFOR scheme. Computational accuracy and order of approximation are examined and compared with the literature. Some of the best numerical results are obtained for the shock–entropy wave interaction. Numerical experiments indicate that the CFOR scheme is stable, conservative and reliable for the numerical simulation of hyperbolic conservation laws. Copyright © 2003 John Wiley & Sons, Ltd.
Optimization of a RF‐generated CF4/O2 gas plasma sterilization process
Authors: Lassen Klaus S. , Nordby Bolette , Grün Reinar
Published: April 2003

A sterilization process with the use of RF‐generated (13.56 MHz) CF4/O2 gas plasma was optimized in regards to power, flow rate, exposure time, and RF‐system type. The dependency of the sporicidal effect on the spore inoculum positioning in the chamber of the RF systems was also investigated. Dried Bacillus stearothermophilus ATCC 7953 endospores were used as test organisms. The treatments were evaluated on the basis of survival curves and corresponding D values. The only parameter found to affect the sterilization process was the power of the RF system. Higher power resulted in higher kill. Finally, when the samples were placed more than 3–8 cm away from a centrally placed electrode in System 2, the sporicidal effect was reduced. The results are discussed and compared to results from the present literature. The RF excitation source is evaluated to be more appropriate for sterilization processes than the MW source. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 239–244, 2003
Preliminary study of interfacial shear strength between PMMA precoated UHMWPE acetabular cup and PMMA bone cement
Authors: Park K. D. , Kim J. , Yang S. J. , Yao A. , Park J. B.
Published: April 2003

Followed by successful demonstration of high interfacial tensile strength in a new design of cemented all‐polyethylene acetabular cup, interfacial shear strength was investigated in this study, with the use of canine‐size prototypes of polymethylmethacrylate (PMMA) precoated UHMWPE acetabular cups. In addition to the PMMA precoated prototypes, three different types of controls were also prepared and tested: grooved UHMWPE cups, PMMA (bone cement) cups, and noncoated, plain UHMWPE cups. The interfacial shear strength of the precoated prototypes was 10.1 ± 0.69 MPa (n = 6), whereas it was 24.3 ± 0.78 MPa (n = 2) for the PMMA cup, 6.95 ± 0.21 MPa (n = 2) for the grooved UHMWPE cup, and 0.34 ± 0.47 MPa (n = 2) for the UHMWPE cup. These results indicate benefits of the PMMA precoating to stabilize the polyethylene acetabular cup securely when applied with bone cement in simulated clinical applications. Analysis of the failed PMMA precoated UHMWPE prototype cups suggested that the chemically induced bonds between precoated PMMA layer and bone cement played a key role in developing high shear strength. After the interfacial shear test of the PMMA precoated prototypes, major disruptions at the interface between treated UHMWPE and precoated PMMA layer were observed by scanning electron microscopy (SEM), which was a unique failure pattern, not found with other prototypes. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 272–279, 2003
Preparation of labeled bis‐amino acid Hydroxyethylamino sulfonamide hiv protease inhibitors
Authors: Cao Kai , Chen Shiang‐Yuan , Prakash Shimoga R.
Published: April 2003

Preparation of radiolabeled sulfonamide HIV protease inhibitors, DMP852 and DMP853 is described. The C‐14 labeling of DMP852 was accomplished by acylation of the intermediate amine with [1‐14C]‐chloroacetic anhydride followed by the treatment of the chloroacetyl derivative with methylamine. Due to the rapid loss of the methylglycine moiety during metabolism studies, a route that involved an oxidation‐reduction sequence was employed to prepare tritium labeled DMP852. Similar methodology was utilized to prepare tritium labeled DMP853. Copyright © 2003 John Wiley & Sons, Ltd.
Printed monopole array antenna for WLAN operation in the 2.4/5.2/5.8 GHz bands
Authors: Wu Tzuenn‐Yih , Fang Shyh‐Tirng , Wong Kin‐Lu
Published: April 2003

A printed monopole array antenna consisting of three equally‐spaced equilateral‐triangular monopoles suitable for 2.4/5.2/5.8‐GHz wireless local area network (WLAN) operation is presented. Among the three monopoles, the center one has a larger size, which controls the excitation of the 2.4‐GHz band, and the other two (of smaller size) are for the excitation of the 5.2/5.8‐GHz bands. Owing to the array effect, the two smaller ones provide enhanced antenna gain (>6 dBi across the operating band) for WLAN operation in the 5.2/5.8‐GHz bands. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 370–372, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10921
Congenital lobar emphysema: Evaluation and long‐term follow‐up of thirty cases at a single center
Authors: Özçelik Uğur , Göçmen Ayhan , Kiper Nural , Doğru Deniz , Dilber Embiya , Yalçın Ebru Güneş
Published: April 2003

Congenital lobar emphysema (CLE) is characterized by overdistension and air‐trapping in the affected lobe, and is one of the causes of infantile respiratory distress. In this report, we review our 27 years of experience with 30 CLE patients. Patients' medical records were evaluated with regard to age, clinical presentation, diagnostic methods, associated diseases, treatment, histopathologic findings, and final clinical and laboratory findings at the end of a long‐term period. The mean age of 30 patients (18 male) at diagnosis was 4.9 ± 6.7 months (range, 2 days–2.5 years). Tachypnea, dyspnea, cough, cyanosis, wheezing, hoarseness, and decreased breath sounds on the affected side were the main symptoms and clinical findings. On chest X‐rays, emphysema was seen in all patients; shift/herniation to the opposite lung, atelectasis, and pneumothorax were observed in 16, 5, and 2 cases, respectively. Computerized tomography of the thorax was performed in 16 cases and revealed emphysema at affected lobe/lobes in all, a shift/herniation to the opposite side in 12 cases, and atelectasis of neighbor lobe/lobes in 7 cases. All 8 patients who had perfusion scintigraphy showed reduced perfusion in the affected lobe. Narrowed and flaccid bronchi were detected in one patient by using flexible bronchoscopy. Blood gas analysis was performed in 11 patients, and hypoxia and hypercarbia were revealed in 9 and 7 of these patients, respectively. The most common affected lobe was the left upper lobe (57%), followed by the right upper lobe (30%) and right middle lobe (27%). Two lobes were involved in 4 patients. Associated abnormalities were observed in 5 patients. Twenty‐one patients underwent lobectomy; 9 were followed conservatively. Ages at diagnosis were significantly younger in surgically treated patients. Emphysema was detected in all pathological specimens, with an additional bronchial cartilage deficiency in 2 patients. In the surgically treated group, 2 patients died and 2 patients were lost to follow‐up. In the conservatively treated group, one patient was lost to follow‐up. Mean follow‐up duration of all patients was 63.2 ± 56.2 months (range, 1–209 months). At follow‐up visits, all patients were doing well. In surgically treated patients, chest X‐rays were normal (9 cases), or showed hyperlucency on the operated side (6 cases) or chronic changes in the operation area (2 cases). Hyperexpansion in the affected lobe was found to be reduced in all cases in the conservatively treated group. Pediatr Pulmonol. 2003; 35:384–391. © 2003 Wiley‐Liss, Inc.
Respiratory pressures in boys from 11–17 years old: A semilongitudinal study
Authors: Matecki Stefan , Prioux Jacques , Jaber Samir , Hayot Maurice , Prefaut Christian , Ramonatxo Michele
Published: April 2003

We hypothesized that in children, maximal respiratory pressures increase with age and more during the pubertal growth spurt. The aim of this work was to follow maximal respiratory pressures, with a semilongitudinal study, in three groups of prepubertal, peripubertal, and postpubertal children in order to specify pressure changes with age and determine the contributions of growth and puberty. A semilongitudinal study was conducted in 44 boys assigned to three overlapping age groups: from 11–13 (prepubertal stage), from 13–15 (pubertal stage), and from 15–17 years (postpubertal stage). The children underwent annual testing for maximal respiratory pressures and spirometric values. Body mass, height, lean body mass assessed from four skinfold thicknesses, and stage of development were also evaluated. Maximal respiratory pressure increased significantly with growth from 11–17 years for maximal inspiratory pressure, and from 11–15 years for maximal expiratory pressure. We observed an increase in the slope of the regression lines between age and lean body mass during the pubertal growth spurt, without an increase in the slopes of the regression lines between age and respiratory pressures. In conclusion, the relationships between age and respiratory pressures are not modified by the growth spurt, indicating that anthropometric characteristics have little role in determining respiratory pressures. Pediatr Pulmonol. 2003; 35:368–374. © 2003 Wiley‐Liss, Inc.
Synthesis and conformational characterization of peptides related to the neck domain of a fungal kinesin
Authors: Deluca Dominga , Woehlke Günther , Moroder Luis
Published: April 2003

The Y362K mutation in the neck domain of conventional kinesin from Neurospora crassa provokes a significant reduction of the rate of movement along microtubules. Since the α‐helical coiled‐coil structure of the neck region is implicated in the mechanism of the processive movement of kinesins, a series of peptides related to the heptad region 338–379 of the wild‐type and the variant fungal kinesins were synthesized as monomers and as N‐terminal disulfide dimers, crosslinked to favour self‐association into coiled‐coil structures entropically. A comparison of the dichroic properties of the peptides and the effects of trifluoroethanol and peptide concentration clearly confirmed the strong implication of the single point mutation in destabilizing the intrinsic propensity of the peptides to fold into the supercoiled conformation. That there is a correlation between the stability of the coiled‐coil and rate of movement of the kinesin is confirmed. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
The chemical synthesis and binding affinity to the EGF receptor of the EGF‐like domain of heparin‐binding EGF‐like growth factor (HB‐EGF)
Authors: Shin Song Yub , Yokoyama Tetsuo , Takenouchi Takato , Munekata Eisuke
Published: April 2003

Heparin‐binding EGF‐like growth factor (HB‐EGF), which belongs to the EGF‐family of growth factors, was isolated from the conditioned medium of macrophage‐like cells. To investigate the effect of N‐ and C‐terminal residues of the EGF‐like domain of HB‐EGF in the binding affinity to the EGF receptor on A431 cell. We synthesized HB‐EGF(44–86) corresponding to the EGF‐like domain of HB‐EGF and its N‐ or C‐terminal truncated peptides. Thermolytic digestion demonstrated three disulfide bond pairings of the EGF‐like domain in HB‐EGF is consistent with that of human‐EGF and human‐TGF‐α. HB‐EGF(44–86) showed high binding affinity to EGF‐receptor, like human‐EGF. The truncation of the C‐terminal Leu86 residue from HB‐EGF(44–86), HB‐EGF(45–86) or HB‐EGF(46–86) caused a drastic reduction in the binding affinity to the EGF receptor. These results suggest that the EGF‐like domain of HB‐EGF plays an important role in the binding to the EGF receptor, and its C‐terminal Leu86 residue is necessary for binding with the EGF‐receptor. In addition, the deletion of the two N‐terminal residues (Asp44‐Pro45) from HB‐EGF(44–86) caused a 10‐fold decrease in relative binding affinity to the EGF receptor. This indicates that the two N‐terminal residues of the EGF‐like domain of HB‐EGF are necessary for its optimal binding affinity to the EGF receptor. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Quantum chemical study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine. Part 2. Structures of catalyst‐alkoxyborane adduct with a four‐membered ring and succeeding reaction intermediates
Authors: Li Ming , Zheng Wenxu , He Rongxing , Tian Anmin
Published: April 2003

Quantum chemical ab initio computations of the structures and properties of oxazaborolidine‐alkoxyborane adduct with a BNBO four‐membered ring and succeeding reaction intermediates are carried out in the current work by means of the Hartree–Fock (HF) and the density functional methods. All the structures are optimized completely at the HF/6‐31G(d) and Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar (B3LYP)/6‐31G(d) levels. As shown in the obtained results, the oxazaborolidine‐alkoxyborane adduct with a BNBO four‐membered ring may be formed during the reduction of the carbonyl bond of the catalyst‐borane‐keto oxime ether adduct. The breakdown of the BNBO four‐membered ring results in the formation of the adduct with a BNBOCCN seven‐membered ring and an oxime bond. The reduction of the oxime bond leads to the adduct with a chiral oxime carbon. The B(2)NCN bond in the BNBOCCN seven‐membered ring of the adduct with a reduced oxime bond is weaker comparatively and thus may be more easily broken down. All the adducts have four stable structures. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 294–306, 2003
Sample size estimation for GEE method for comparing slopes in repeated measurements data
Authors: Jung Sin‐Ho , Ahn Chul
Published: April 2003

Sample size calculation is an important component at the design stage of clinical trials. Controlled clinical trials often use a repeated measurement design in which individuals are randomly assigned to treatment groups and followed‐up for measurements at intervals across a treatment period of fixed duration. In studies with repeated measurements, one of the popular primary interests is the comparison of the rates of change in a response variable between groups. Statistical models for calculating sample sizes for repeated measurement designs often fail to take into account the impact of missing data correctly. In this paper we propose to use the generalized estimating equation (GEE) method in comparing the rates of change in repeated measurements and introduce closed form formulae for sample size and power that can be calculated using a scientific calculator. Since the sample size formula is based on asymptotic theory, we investigate the performance of the estimated sample size in practical settings through simulations. Copyright © 2003 John Wiley & Sons, Ltd.
Fluoxetine depresses glutamate exocytosis in the rat cerebrocortical nerve terminals (synaptosomes) via inhibition of P/Q‐type Ca2+ channels
Authors: Wang Su‐Jane , Su Chin‐Feng , Kuo Yu‐Heng
Published: April 2003

Fluoxetine, an antidepressant that is used clinically in the treatment of mood disorders, is a selective serotonin reuptake inhibitor. In the present study we investigated the effects of fluoxetine on 4‐aminopyridine (4AP)‐evoked glutamate release in cerebrocortical nerve terminals (synaptosomes). Fluoxetine suppressed the release of glutamate evoked by 4AP in a concentration‐dependent manner. This effect was associated with a reduction in the depolarization‐evoked increase in cytosolic free calcium levels in the absence of significant effect on the synaptosomal membrane potential. In addition, both ionomycin‐ and sucrose‐evoked glutamate releases were not affected by fluoxetine, indicating that fluoxetine‐mediated inhibition of glutamate release is not a direct effect on the exocytotic machinery. Furthermore, the inhibitory action of fluoxetine was completely abolished in synaptosomes pretreated with P/Q type Ca2+ channel blocker ω‐agatoxin IVA (ω‐AgTX IVA) or protein kinase C (PKC) stimulator 4β‐phorbol 12, 13‐dibutyrate (PDBu). These results suggest that, in cerebrocortical nerve terminals, fluoxetine inhibits glutamate release through the suppression of P/Q type Ca2+ channel activity. The presynaptic action of fluoxetine is mediated by a PKC‐sensitive signaling pathway. Synapse 48:170–177, 2003. © 2003 Wiley‐Liss, Inc.
Alterations in blood and urine parameters in two florida manatees (Trichechus manatus latirostris) from simulated conditions of release following rehabilitation
Authors: Manire Charles A. , Walsh Catherine J. , Rhinehart Howard L. , Colbert Debborah E. , Noyes David R. , Luer Carl A.
Published: April 2003

In an effort to manage the existing population of the endangered Florida manatee (Trichechus manatus latirostris), as many individuals as possible are rehabilitated from illness or injury and released back into the waters of the state of Florida. It is not uncommon, however, for manatees recaptured for health assessment following release from rehabilitation to have elevated concentrations of serum creatinine. Although such elevated levels would be indicative of kidney failure in most other mammals, problems associated with renal function have not been evident in these recaptured manatees. To determine the possible cause(s) of the serum creatinine increase, two captive Florida manatees were manipulated to simulate many of the environmental and physical changes that occur during and shortly after release. Routine chemical analyses of serum and urine, complete blood counts, serum cortisol concentrations, and lymphocyte proliferation responses were measured. Serum creatinine concentrations increased significantly in response to decreased food intake and changes in food type. The increases differed depending on the salinity of the water in which the animals were maintained. It was found that significant changes in urinary creatinine and serum creatine kinase occurred as well, but serum cortisol concentrations were elevated only during simulated transport. Lymphocyte proliferation assays indicated that immune function was potentially impaired by extreme levels of dietary restriction and by changes in salinity. These results suggest that serum creatinine elevations and subsequent effects on the immune system might be minimized by adapting manatees undergoing rehabilitation to the diet and salinity they would encounter following release. Zoo Biol 22:103–120, 2003. © 2003 Wiley‐Liss, Inc.
Gut loading to enhance the nutrient content of insects as food for reptiles: A mathematical approach
Authors: Finke Mark D.
Published: April 2003

A variety of commercially raised insects are fed to insectivorous reptiles, but information concerning appropriate diets used to feed these insects is limited. In the present study, house crickets (Acheta domesticus adults and nymphs), mealworms (Tenebrio molitor larvae), and silkworms (Bombyx mori larvae) were fed diets containing graded levels of calcium (Ca) and/or vitamin A–nutrients that are low or absent in most insects. Diets and insects were analyzed for moisture, Ca, phosphorus (P), and vitamin A. For adult crickets and cricket nymphs, body Ca and vitamin A concentrations increased in a linear fashion with increasing levels of dietary Ca or vitamin A. Ca concentrations of silkworms also increased in a linear fashion with increasing levels of dietary Ca. For mealworms, body Ca and vitamin A concentrations increased in a nonlinear fashion with increasing levels of dietary Ca or vitamin A. These regression equations, in conjunction with insect nutrient composition, allow for the calculation of the optimum nutrient concentration for gut‐loading diets. Final recommendations were based on National Research Council (NRC) requirements for rats, adjustments for the energy content of the insects, and nutrient overages as appropriate. Gut‐loading diets for crickets (adults and nymphs) should be supplemented to contain the following nutrients, respectively: Ca (51 and 32 g/kg), vitamin A (8,310 and 5,270 µg retinol/kg), vitamin D (300 and 190 µg cholecalciferol/kg), vitamin E (140 and 140 mg RRR‐α‐tocopherol/kg), thiamin (31 and 21 mg/kg), and pyridoxine (20 and 10 mg/kg). Gut‐loading diets for mealworms should be supplemented to contain the following nutrients: Ca (90 g/kg), iron (51 mg/kg), manganese (31 mg/kg), vitamin A (13,310 µg retinol/kg), vitamin D (460 µg cholecalciferol/kg), vitamin E (660 mg RRR‐α‐tocopherol/kg), thiamin (5 mg/kg), vitamin B12 (650 µg/kg), and methionine (29 g/kg). Gut‐loading diets for silkworms should be supplemented to contain the following nutrients: Ca (23 g/kg), iodine (0.7 mg/kg), vitamin D (140 µg cholecalciferol/kg), vitamin E (70 mg RRR‐α‐tocopherol/kg), and vitamin B12 (226 µg/kg). Zoo Biol 22:147–162, 2003. © 2003 Wiley‐Liss, Inc.
Effects of interactions of hepatocyte nuclear factor 4α isoforms with coactivators and corepressors are promoter‐specific
Authors: Torres-Padilla Maria Elena , Weiss Mary C
Published: April 2003

The gene encoding hepatocyte nuclear factor 4α (HNF4α) possesses two alternative promoters responsible for developmental and tissue‐specific expression of HNF4α1 and HNF4α7. The two isoforms possess different N‐termini and exhibit distinct transactivation properties. We show here for the first time that the effects mediated by HNF4α isoforms in concert with three different coregulators result in promoter‐specific responses. Transcript levels of silencing mediator for retinoid and thyroid receptors and glucocorticoid receptor interacting protein‐1 in the liver are reduced at birth, a time point when many genes are strongly activated, suggesting that the effects of coregulators on HNF4α activity in vivo could be determined by the levels of their expression as well as by the target promoter.
Discodermolide interferes with the binding of tau protein to microtubules
Authors: Kar Santwana , Florence Gordon J , Paterson Ian , Amos Linda A
Published: April 2003

We investigated whether discodermolide, a novel antimitotic agent, affects the binding to microtubules of tau protein repeat motifs. Like taxol, the new drug reduces the proportion of tau that pellets with microtubules. Despite their differing structures, discodermolide, taxol and tau repeats all bind to a site on β‐tubulin that lies within the microtubule lumen and is crucial in controlling microtubule assembly. Low concentrations of tau still bind strongly to the outer surfaces of preformed microtubules when the acidic C‐terminal regions of at least six tubulin dimers are available for interaction with each tau molecule; otherwise binding is very weak.
ArhGAP15, a novel human RacGAP protein with GTPase binding property1
Authors: Seoh Mui Leng , Ng Chong Han , Yong Jeffery , Lim Louis , Leung Thomas
Published: April 2003

We have previously described a partial cDNA sequence encoding a RhoGAP protein, GAP25 that is homologous to the recently reported ArhGAP9 and ArhGAP12. We now describe a related new member ArhGAP15 that shares a number of domain similarities, including a pleckstrin homology (PH) domain, a RhoGAP domain and a novel motif N‐terminal to the GAP domain. This novel motif was found to be responsible for nucleotide‐independent Rac1 binding. Using swop mutants of Rac/Cdc42, we have established that the binding is through the C‐terminal half of Rac1. The GAP domain of ArhGAP15 showed specificity towards Rac1 in vitro. The PH domain is required for ArhGAP15 to localize to cell periphery and over‐expression of the full‐length ArhGAP15, but not the mutant with a partial deletion of the PH domain, resulted in an increase in actin stress fibers and cell contraction. These morphological effects can be attenuated by the co‐expression of dominant negative Rac1N17. HeLa cells expressing ArhGAP15 were also resistant to phorbol myristatate acetate treatment, suggesting that ArhGAP15 is a potential regulator of Rac1.
DMBT1, a regulator of mucosal homeostasis through the linking of mucosal defense and regeneration?
Authors: Kang Weiqun , Reid Kenneth B.M
Published: April 2003

DMBT1 (deleted in malignant brain tumor 1), which encodes a large scavenger receptor cysteine rich (SRCR) B protein, has been proposed to be a tumor suppressor gene, due to the high frequency of its homozygous deletion and the lack of expression in a variety of cancers. However, studies on its physiological functions and its relationship with tumorigenesis are still at an initial stage. Two mucosal defense‐related molecules, gp‐340 and salivary agglutinin, have been identified to be alternatively spliced products of DMBT1, which suggests that DMBT1 is a pattern recognition receptor in innate immunity. Meanwhile, results from immunohistochemical staining and studies at the cellular level, began to associate DMBT1 with a proliferation to differentiation switching process in gastrointestinal epithelial cells. Together with its up‐regulation in inflammation, these findings suggest that DMBT1 might be a local regulator of homeostasis, possibly through linking mucosal inflammation to the modulation of epithelial regeneration, and whose abnormality is a frequent cause of malignancy.
Recombinant endostatin forms amyloid fibrils that bind and are cytotoxic to murine neuroblastoma cells in vitro
Authors: Kranenburg Onno , Kroon-Batenburg Loes M.J , Reijerkerk Arie , Wu Ya-Ping , Voest Emile E , Gebbink Martijn F.B.G
Published: April 2003

Endostatin is a fragment of collagen XVIII that acts as an endogenous inhibitor of tumor angiogenesis and tumor growth. Anti‐tumor effects have been described using both soluble and insoluble recombinant endostatin. However, differences in endostatin structure are likely to cause differences in bioactivity. In the present study we have investigated the structure and cellular effects of insoluble endostatin. We found that insoluble endostatin shows all the hallmarks of amyloid aggregates. Firstly, it binds Congo red and shows the characteristic apple‐green birefringe when examined under polarized light. Secondly, electron microscopy shows that endostatin forms short unbranched fibrils. Thirdly, X‐ray analysis shows the abundant presence of cross‐β sheets, the tertiary structure that underlies fibrillogenesis. None of these properties was observed when examining soluble endostatin. Soluble endostatin can be triggered to form cross‐β sheets following denaturation, indicating that endostatin is a protein fragment with an inherent propensity to form amyloid deposits. Like β‐amyloid, found in the brains of patients with Alzheimer's disease, amyloid endostatin binds to and is toxic to neuronal cells, whereas soluble endostatin has no effect on cell viability. Our results demonstrate a previously unrecognized functional difference between soluble and insoluble endostatin, only the latter acting as a cytotoxic amyloid substance.
The p110γ PI‐3 kinase is required for EphA8‐stimulated cell migration
Authors: Gu Changkyu , Park Soochul
Published: April 2003

This study provides evidence that treatment with preclustered ephrin A5‐Fc results in a substantial increase in the stability of the p110γ PI‐3 kinase associated with EphA8, thereby enhancing PI‐3 kinase activity and cell migration on a fibronectin substrate. In contrast, co‐expression of a lipid kinase‐inactive p110γ mutant together with EphA8 inhibits ligand‐stimulated PI‐3 kinase activity and cell migration on a fibronectin substrate, suggesting that the mutant has a dominant negative effect against the endogenous p110γ PI‐3 kinase. Significantly, the tyrosine kinase activity of EphA8 is not important for either of these processes. Taken together, our results demonstrate that the stimulation of cell migration on a fibronectin substrate by the EphA8 receptor depends on the p110γ PI‐3 kinase but is independent of a tyrosine kinase activity.
The unfolding tale of PECAM‐1
Authors: Jackson Denise E
Published: April 2003

Platelet endothelial cell adhesion molecule‐1 (PECAM‐1/CD31) is a member of the immunoglobulin (Ig) superfamily that has distinctive features of an immunoreceptor based upon its genomic structure and the presence of intrinsic immunoreceptor tyrosine inhibitory motifs (ITIMs) in its ligand binding polypeptide. This has lead to its subclassification into the Ig‐ITIM superfamily. Its amino‐terminal Ig‐like domain of PECAM‐1 is necessary for its homophilic binding, which plays an important role in cell–cell interactions. Its intracellular ITIMs serve as scaffolds for recruitment of signalling molecules including protein‐tyrosine phosphatases to mediate its inhibitory co‐receptor activity. Increasing evidence has implicated PECAM‐1 in a plethora of biological phenomena, including modulation of integrin‐mediated cell adhesion, transendothelial migration, angiogenesis, apoptosis, cell migration, negative regulation of immune cell signalling, autoimmunity, macrophage phagocytosis, IgE‐mediated anaphylaxis and thrombosis. In this review, we discuss some of the new developments attributed to this molecule and its unique roles in biology.
Allosteric interactions among pyrethroid, brevetoxin, and scorpion toxin receptors on insect sodium channels raise an alternative approach for insect control
Authors: Gilles Nicolas , Gurevitz Michael , Gordon Dalia
Published: April 2003

Intensive pyrethroid use in insect control has led to resistance buildup among various pests. One alternative to battle this problem envisions the combined use of synergistically acting insecticidal compounds. Pyrethroids, scorpion α‐ and β‐toxins, and brevetoxins bind to distinct receptor sites on voltage‐gated sodium channels (NaChs) and modify their function. The binding affinity of scorpion α‐toxins to locust, but not rat‐brain NaChs, is allosterically increased by pyrethroids and by brevetoxin‐1. Brevetoxin‐1 also increases the binding of an excitatory β‐toxin to insect NaChs. These results reveal differences between insect and mammalian NaChs and may be exploited in new strategies of insect control.
The apoptosis‐associated protein BNIPL interacts with two cell proliferation‐related proteins, MIF and GFER
Authors: Shen Li , Hu Jian , Lu Hong , Wu Ming , Qin Wenxin , Wan Dafang , Li Yu-Yang , Gu Jianren
Published: April 2003

Bcl‐2/adenovirus E1B 19 kDa interacting protein 2‐like, BNIP‐2‐like (BNIPL) is a recently cloned and characterized apoptosis‐associated protein that shares 72% homology with BNIP‐2. It is highly expressed in human placenta and lung. A yeast two‐hybrid system was used to obtain two BNIPL‐interacting proteins, MIF (macrophage migration inhibitory factor) and GFER (growth factor erv1 (Saccharomyces cerevisiae)‐like). The interactions were confirmed by glutathione S‐transferase pull‐down assay in vitro and co‐immunoprecipitation assay in vivo. Colony formation assay and cell proliferation test suggest that overexpression of BNIPL could inhibit the growth of BEL‐7402 cells. These findings suggest that BNIPL may physically bind to cell proliferation‐related proteins, MIF and GFER.
The dual role of protein kinase C in the regulation of telomerase activity in human lymphocytes
Authors: Sheng Wei-Yun , Chien Ya-Li , Wang Tzu-Chien V
Published: April 2003

Protein kinase C (PKC) has been implicated to play an essential function in the upregulation of telomerase activity in activated T cells, yet its role in the regulation of telomerase activity remains largely unknown. In this work, we present evidence that PKC activity is required both for the induction of hTERT expression and for the post‐transcriptional control of telomerase enzyme activity in T lymphocytes. Of the several PKC isoforms present in lymphocytes, only the level of PKC‐ζ was greatly increased during T cell activation, implicating that PKC‐ζ may be required for the post‐transcriptional control of telomerase enzyme activity in T lymphocytes.
Biochemical characterization of the vacuolar palmitoyl acyltransferase
Authors: Veit Michael , Dietrich Lars E.P , Ungermann Christian
Published: April 2003

Vacuole fusion requires Sec18p‐dependent acylation of the armadillo‐repeat protein Vac8p that has been isolated with cis‐SNARE complexes. To gain more insight into the mechanism of acylation, we analyzed the palmitoylation reaction on isolated vacuoles or in vacuolar detergent extracts. Recombinant Vac8p is palmitoylated when added to vacuoles and is anchored to membranes after modification. The palmitoyl acyltransferase (PAT) extracted from vacuolar membranes is functional in detergent extracts and shows all characteristics of an enzymatic activity: It modifies exogenous Vac8p in a temperature‐, dose‐ and time‐dependent manner, and is sensitive to bromo‐palmitate, a known inhibitor of protein palmitoylation in vivo. Importantly, PAT is specific for palmitoyl‐CoA, since myristoyl‐ and stearyl‐CoA can compete with labeled Pal‐CoA only at 10‐fold higher amounts.
Differences in expression patterns between mouse connexin‐30.2 (Cx30.2) and its putative human orthologue, connexin‐31.91
Authors: Nielsen Peter A , Kumar Nalin M
Published: April 2003

A novel gap junction forming protein, mouse connexin‐30.2 (Cx30.2) contains 278 amino acid residues, and is 79% identical to human Cx31.9 (GJA11). Northern analysis showed that Cx30.2 is ubiquitously expressed, most prominently in testis. Polyclonal antibodies against Cx30.2 detected a 30 kDa protein in cells overexpressing Cx30.2, and in mouse testis. Immunofluorescence showed that Cx30.2 was expressed in vascular smooth muscle, but also in cell types where Cx31.9 was not detected. These data demonstrate that Cx30.2 is a bona fide gene, and suggest that it is the orthologue of Cx31.9, but that it may have additional roles compared with Cx31.9.
Aquaporin‐9 is expressed in a mucus‐secreting goblet cell subset in the small intestine
Authors: Okada Shinji , Misaka Takumi , Matsumoto Ichiro , Watanabe Hirohito , Abe Keiko
Published: April 2003

We analyzed the expression of aquaporins (AQPs) in the small intestine to elucidate their functions, and found that AQP9, which had not previously been detected there, is present in duodenum, jejunum, and ileum. AQP9 is expressed in colon as well, but not in stomach. Also, its expression in these intestinal sections is limited to the basolateral membranes of a goblet cell subset. Our finding that AQP9 is present specifically in goblet cells as mucus‐secreting cells suggests its involvement in the synthesis and/or secretion of a certain kind of mucus which may protect the intestinal surface and smooth the flow of intestinal contents.
Characterisation of Archaeglobus fulgidus AlkA hypoxanthine DNA glycosylase activity
Authors: Mansfield Colin , Kerins Sinéad M , McCarthy Tommie V
Published: April 2003

The AlkA protein from the archaebacterium Archaeglobus fulgidus was characterised with respect to release of hypoxanthine from DNA. The hypoxanthine glycosylase activity had optimal activity at 60°C at pH 5.0. The enzyme released hypoxanthine from substrates with a preference for dI:dG≫dI:dT>dI:dC>dI:dA. The presence of a mismatch on either side of the dIMP in the substrate reduced excision efficiency of the hypoxanthine residue at neutral pH, while a mismatch on both sides of the dIMP resulted in total loss of excision. Release of hypoxanthine from DNA required a minimum of two bases on the 5′ side and four bases on the 3′ side of the dIMP residue.
Histidine 454 plays an important role in polymerization of human glutamate dehydrogenase
Authors: Lee Eun-Young , Huh Jae-Wan , Yang Seung-Ju , Choi Soo Young , Cho Sung-Woo , Choi Hyun Jin
Published: April 2003

Although previous chemical modification studies have suggested several residues to be involved in the maintenance of the quaternary structure of glutamate dehydrogenase (GDH), there are conflicting views for the polymerization process and no clear evidence has been reported yet. In the present study, cassette mutagenesis at seven putative positions (Lys333, Lys337, Lys344, Lys346, Ser445, Gly446, and His454) was performed using a synthetic human GDH gene to examine the polymerization process. Of the mutations at the seven different sites, only the mutagenesis at His454 results in depolymerization of the hexameric GDH into active trimers as determined by HPLC gel filtration analysis and native gradient polyacrylamide gel electrophoresis. The mutagenesis at His454 has no effects on expression or stability of the protein. The K
M values for NADH and 2‐oxoglutarate were 1.5‐fold and 2.5‐fold greater, respectively, for the mutant GDH than for wild‐type GDH, indicating that substitution at position 454 had appreciable effects on the affinity of the enzyme for both NADH and 2‐oxoglutarate. The V
max values were similar for wild‐type and mutant GDH. The k
cat/K
M value of the mutant GDH was reduced up to 2.8‐fold. The decreased efficiency of the mutant, therefore, results from the increase in K
M values for NADH and 2‐oxoglutarate. The results with cassette mutagenesis and HPLC gel filtration analysis suggest that His454 is involved in the polymerization process of human GDH.
Gene expression patterns define pathways correlated with loss of differentiation in lung adenocarcinomas
Authors: Creighton Chad , Hanash Samir , Beer David
Published: April 2003

An analysis of microarray data from 86 lung adenocarcinomas reveals hundreds of genes significantly correlated with tumor cell differentiation. A bioinformatics approach of linking these genes to public information from the Locuslink and KEGG databases yields evidence for a loss of tumor cell differentiation being associated with biological processes of cell division, protein degradation, pyrimidine and purine metabolism, oxidative phosphorylation, glyoxylate and dicarboxylate metabolism, folate biosynthesis, and glutamate metabolism. The increased expression of genes involved in these processes is consistent with increased proliferation and metabolism characteristics of poorly differentiated tumors. The complete results of this analysis are available at http://dot.ped.med.umich.edu:2000/pub/diff/index.htm.
Induction of colonic epithelial cell apoptosis by p47‐dependent oxidants1
Authors: Gu Ying , Souza Rhonda F , Wu Ru Feng , Xu You Cheng , Terada Lance S
Published: April 2003

Exogenous oxidants appear capable of initiating both proliferative and death signals, but the role of endogenous oxidants in either tumorigenesis or tumor suppression is unclear. We found that expression of the NAD(P)H oxidase adapter p47
phox
was suppressed in human colon carcinoma specimens relative to adjacent normal colon. Overexpression of p47
phox
increased apoptosis in colon cancer cell lines independent of p53 and mismatch‐repair competency. p47
phox
was found to interact with the c‐Abl adapter Abl interactor‐1 (ABI‐1), and p47
phox
coprecipitated with both ABI‐1 and c‐Abl. Ectopic expression of p47
phox
in colon cancer cells increased oxidant production with phosphorylation and activation of nuclear c‐Abl and consequent apoptosis. Colonic epithelial p47
phox
may be specifically targeted to a c‐Abl‐containing complex that serves a physiologic tumor suppressing function.
Mutation of an N‐terminal acidic‐rich region of p115‐RhoGEF dissociates α13 binding and α13‐promoted plasma membrane recruitment
Authors: Bhattacharyya Raja , Wedegaertner Philip B
Published: April 2003

The Ras homology (Rho) guanine nucleotide exchange factor p115‐RhoGEF couples the α13 heterotrimeric guanine nucleotide binding protein (G protein) subunit to Rho GTPase. α13 binds to a regulator of G protein signaling (RGS) domain in p115‐RhoGEF, but the mechanism of α13 activation of p115‐RhoGEF is poorly understood. In this report, we demonstrate in cell‐based assays that the acidic‐rich N‐terminus, adjacent to the RGS domain, is required for binding to activated α13, and refine the importance of this region by showing that mutation of glutamic acids 27 and 29 in full‐length p115‐RhoGEF is sufficient to prevent interaction with activated α13. However, α13‐interacting deficient N‐terminal mutants of p115‐RhoGEF retain α13‐dependent plasma membrane recruitment. Overall, these findings demonstrate a critical role for the N‐terminal extension of p115‐RhoGEF in mediating binding to α13 and dissociate two activities of p115‐RhoGEF: binding to activated α13 and translocation to the PM in response to activated α13.
Engagement of CD99 triggers the exocytic transport of ganglioside GM1 and the reorganization of actin cytoskeleton
Authors: Yoon Sang Soon , Jung Kyung In , Choi Yoon-La , Choi Eun Young , Lee Im-Soon , Park Seong Hoe , Kim Tae Jin
Published: April 2003

We studied the role of lipid rafts and actin cytoskeleton in CD99‐mediated signaling to elucidate the mechanism of protein transport upon CD99 engagement. CD99 engagement in Jurkat cells elicited the exocytic transport of GM1 as well as several surface molecules closely related with CD99 functions. In addition, CD99 molecules were rapidly incorporated into lipid rafts and appeared to rearrange the actin cytoskeleton upon CD99 stimulation. Association of CD99 with actin cytoskeleton was inhibited by methyl‐β‐cyclodextrin, while CD99‐mediated GM1 clustering was inhibited by cytochalasin D. Therefore, we suggest that CD99 may play a role in the vesicular transport of transmembrane proteins and lipid rafts from the intracellular location to the cell surface, possibly by effecting actin cytoskeleton reorganization.
Daxx enhances Fas‐mediated apoptosis in a murine pro‐B cell line, BAF3
Authors: Muromoto Ryuta , Yamamoto Tetsuya , Yumioka Taro , Sekine Yuichi , Sugiyama Kenji , Shimoda Kazuya , Oritani Kenji , Matsuda Tadashi
Published: April 2003

Daxx has been shown to play an essential in type I interferon (IFN‐α/β)‐mediated suppression of B cell development and apoptosis. Recently, we demonstrated that Tyk2 is directly involved in IFN signaling for the induction and nuclear translocation of Daxx, which may result in growth arrest and/or apoptosis of B lymphocyte progenitors. To clarify the mechanism of Daxx‐mediated apoptosis signaling in B lymphocyte progenitors, here we introduced an efficient suicide switch in a murine pro‐B cell line, BAF3, by expressing FK506‐binding protein‐fused Fas intracellular domain (FKBP‐Fas) and Daxx. It allows us to monitor Fas/Daxx‐mediated signal by induction of Fas dimerization with the dimerizer drug AP20187. AP20187‐mediated Fas dimerization induced not only apoptosis but also Jun N‐terminal kinase (JNK) activation. However, AP20187 had no effect on cells expressing either Fas or Daxx only. Furthermore, expression of a JNK inhibitor, the JNK‐binding domain of JIP‐1, resulted in resistance to AP20187‐mediated apoptosis in cells expressing FKBP‐Fas and Daxx. These results imply that our novel suicide switch system may provide a powerful tool to delineate or identify the signaling molecules for Daxx‐mediated apoptotic machinery in B lymphocyte progenitors through JNK activation.
Phospholipid chlorohydrins cause ATP depletion and toxicity in human myeloid cells
Authors: Dever Gary , Stewart Laura-Jayne , Pitt Andrew R , Spickett Corinne M
Published: April 2003

Chlorohydrins of stearoyl‐oleoyl phosphatidylcholine (SOPC), stearoyl‐linoleoyl phosphatidylcholine, and stearoyl‐arachidonyl phosphatidylcholine were incubated with cultured myeloid cells (HL60) for 24 h, and the cellular ATP level was measured using a bioluminescent assay. The chlorohydrins caused significant depletion of cellular ATP in the range 10–100 μM. The ATP depletion by the phospholipid chlorohydrins was slightly less than that of 4‐hydroxy‐2‐nonenal, but greater than that of hexanal, trans‐2‐nonenal, and autoxidised palmitoyl‐arachidonoyl phosphatidylcholine. SOPC chlorohydrin was also found to cause loss of viability in U937 cells, and thus phospholipid chlorohydrins could contribute to the formation of a necrotic core in advanced atherosclerotic lesions.