bluuebunny/crossref_metadata_2025 huggingface dataset:
China's WTO accession, state enterprise reform, and spatial economic restructuring
Authors: Xiaobin Zhao Simon , Tong Christopher S. P. , Qiao Jiming
Published: August 2002

China's accession to the World Trade Organization (WTO) promises to have profound effects on the development of the nation's economy and on nationwide enterprise reorganization. This paper attempts to address the relationship between China's WTO accession and state enterprise reforms, and their impacts on the performance of China's spatial economy, including the possible rise and fall of several large national financial centres, such as Hong Kong, Beijing, Shanghai, Guangzhou and Shenzhen. It is argued that China's new international ties will enhance current enterprise reforms and promote changes in the existing pattern of enterprise organization, with enterprise mergers, acquisitions, takeover activity and the formation of large multinational corporations (MNCs) becoming dominant trends within China's industrial development. Alongside these changes, some economic sectors, such as information technology (IT) and advanced professional services are predicted to become concentrated in several national information ‘heartlands,’ each having its own well‐developed information infrastructure and other comparative advantages over traditional industrial centers. Meanwhile traditional industrial enterprises, while continuing to rely upon their pre‐assigned resource priorities, will certainly face fierce international competition in the turbulent global market. The spatial shift of production and trade undoubtedly requires that Chinese enterprises, especially those that are state‐owned, reorganize their production‐trade systems according to the global ‘rules of the game’. All of these changes, due to take effect imminently with China's WTO accession, will fundamentally restructure China's spatial economic landscape, including the creation of a new information heartland and hinterland that will in turn determine the life or death of the country's national financial centres. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of 5‐methylthioribose specifically bitritiated at the 5‐C position
Authors: Viegas Christina , Zhang Qiang , Guillerm Danielle , Guillerm Georges
Published: August 2002

An efficient and reliable method for the preparation of bitritiated‐methylthioribose from a suitably protected 5‐ketoazido‐ribose derivative has been developed. This compound is an essential component in the assay of the microbial enzyme methylthioribose kinase, which is involved in the methionine salvage pathway from methylthioadenosine. Copyright © 2001 John Wiley & Sons, Ltd.
Microscopic anatomy of the eye of the deep‐diving Antarctic Weddell seal (Leptonychotes weddellii)
Authors: Welsch Ulrich , Ramdohr Sven , Riedelsheimer Bernd , Hebel Rudolf , Eisert Regina , Plötz Joachim
Published: August 2002

The microscopic anatomy of the eye of the Weddell seal was studied with various light and electron microscopic methods with a view to correlating morphological findings with the biology of this seal which is adapted to the extremes of the Antarctic environment and to extreme diving excursions into the lightless depths of the sea. In the retina an area centralis was found but no fovea centralis. The densely packed photoreceptors consist exclusively of highly differentiated rods, which in primates detect light at low intensity but have rather poor image discrimination. The ganglion cells are relatively scarce, suggesting a high degree of convergence of the light‐sensitive cells on the ganglion cells. The pigment epithelium is almost devoid of pigment granules. The extensive tapetum lucidum is about 400–500 μm thick and is composed of about 30 layers of specialized cells. The cornea is 650 (center) to 800–900 (periphery) μm thick. Its structure and glycosaminoglycan histochemistry correspond to that of other mammals. The iridocorneal angle is unusually deep and pervaded by an elaborate trabecular meshwork, which together with a complex canal of Schlemm can be correlated with the ability to absorb large amounts of fluid. The ciliary muscle and its antagonist, the membrane of Bruch, are poorly developed, suggesting relatively poor abilities of accommodation. The combination of a well‐developed tapetum lucidum, an unpigmented pigment epithelium, well‐developed rods, and a high number of rods converging on only few ganglion cells is obviously an adaptation to an extreme light sensitivity, enabling the animals to make use of the little light available in the deep sea. J. Morphol. 248:165–174, 2001. © 2001 Wiley‐Liss, Inc.
Cardiovascular system of the blue crab Callinectes sapidus
Authors: McGaw Iain J. , Reiber Carl L.
Published: August 2002

The circulatory system of adult blue crabs, Callinectes sapidus, was mapped by either injecting barium sulfate into intact animals followed by radiography or by resin corrosion casts (Batsons Monomer). Seven arteries arise from the heart. The anterior aorta exits from the anterior dorsal surface of the heart and gives rise to the optic arteries; these arteries supply hemolymph to the supraesophageal ganglion and eyestalks. The paired anterolateral arteries also exit from the anterior dorsal surface of the heart and supply hemolymph to the gonads, hepatopancreas, stomach, antennal gland, mandibular muscles, and the hypodermis of the anterior cephalothorax. The paired hepatic arteries exit the heart anteriorly and ventrally and branch profusely within the hepatopancreas. A smaller side branch, the pyloric hepatic artery, supplies hemolymph to the pyloric stomach and midgut. The smallest artery, the posterior aorta, branches off the posterior ventral surface of the heart; it joins with the inferior abdominal artery in the region of the second abdominal segment and these arteries supply hemolymph to the hindgut and abdomen. The largest artery is the sternal artery, which exits from the ventral surface of the heart; the ventral thoracic artery branches off the sternal artery and supplies hemolymph to the chelae, the mouthparts, and to each pereiopod. The present study shows that the circulatory system is highly developed, with arteries dividing into smaller capillary‐like vessels that ramify profusely within individual organs. The return vessels, the sinuses, are discrete channels rather than random open spaces, as previously described. The present study refines and advances descriptions of the circulatory system and is discussed in relation to recent work on hemolymph flow in crustaceans. J. Morphol. 251:1–21, 2002. © 2002 Wiley‐Liss, Inc.
Embryogenesis of the glowworm Rhagophthalmus ohbai Wittmer (Insecta: Coleoptera, Rhagophthalmidae), with emphasis on the germ rudiment formation
Authors: Kobayashi Yukimasa , Suzuki Hirobumi , Ohba Nobuyoshi
Published: August 2002

The early embryonic development and features of the developing embryo of the glowworm Rhagophthalmus ohbai are described chiefly by light microscopy, with emphasis on the germ rudiment formation and its phylogenetic implication. The egg period is 30–34 days at about 23°C. The newly laid egg is a short ellipsoid, 1.09 by 0.78 mm in size, and the size increases to 1.15 by 0.95 mm by 17 days after oviposition. Cleavage is of the typical superficial type. The germ disk is formed by cell aggregation of the embryonic area at the anterior end of the egg. The central part of the germ disk then sinks into the yolk and the spherical germ rudiment is formed by fusion of the amnioserosal folds extended from all margins of the germ disk. The inner region of the germ rudiment soon becomes slender and develops into the short embryo, whereas the outer region facing the anterior end is extended to form the thin amnion. The embryo then rapidly elongates, the elongation being accompanied by embryo segmentation and formation of appendages. The submerged condition of the embryo persists until about 17 days after oviposition (about 1 day before embryonic revolution) and thereafter the embryo becomes superficial in position. The presence of the following embryonic characters in R. ohbai supports the molecular data placing it within the Lampyridae: 1) formation of a spherical germ rudiment near the anterior end of the egg, and 2) the submerged condition of the developing embryo persists until shortly before revolution. J. Morphol. 253:1–9, 2002. © 2002 Wiley‐Liss, Inc.
IgM expressed by leukemic CD5+ B cells binds mouse immunoglobulin light chain
Authors: Weston Kathryn M. , Tangye Stuart G. , Dunn Rosanne D. , Smith Alison , Morris Michael B. , Raison Robert L.
Published: August 2002

Mouse immunoglobulin (Ig) molecules have previously been shown to bind to the surface of CD5+ B cells from patients with B‐cell chronic lymphocytic leukemia (B‐CLL). The results indicated that surface IgM was involved in the interaction and suggested the phenomenon was an example of the polyreactive binding capacity of the surface Ig (sIg) expressed by these malignant cells. This article describes the further characterization of the interaction between human IgM and mouse Ig molecules and subunits. Mouse Ig molecules of both kappa and lambda light chain classes bound to the B‐CLL cell surface. The dissociation constant for the interaction of mouse IgG1 (K121) with the B‐CLL cell surface was 3.6 × 10−7 M. To confirm the involvement of the human IgM expressed by the B‐CLL cells in the interaction, the malignant cells were stimulated in vitro to induce secretion of human IgM. Enzyme immunoassay was used to show that secreted human IgM bound to intact mouse Ig, as occurred with the cell surface analysis. The mouse Ig epitope recognized by the purified secreted human IgM was shown by Western blot analysis to be located on the light chain of the mouse Ig molecule and to be conformationally dependent. K121 light chain was cloned and expressed in E. coli and the recombinant light chain bound to the surface of CLL B cells. The results confirm that human IgM is the reactive ligand in the interaction with mouse Ig and indicate that the interaction of polyreactive IgM with mouse IgG occurs via the light chain component of IgG. Copyright © 2001 John Wiley & Sons, Ltd.
Movement correction of the kidney in dynamic MRI scans using FFT phase difference movement detection
Authors: Giele E.L.W. , de Priester J.A. , Blom J.A. , den Boer J.A. , van Engelshoven J.M.A. , Hasman A. , Geerlings M.
Published: August 2002

To measure cortical and medullary MR renograms, regions of interest (ROIs) are placed on the kidney in images acquired using dynamic MRI. Since native kidneys move with breathing, and breath‐holding techniques are not feasible, movement correction is necessary. In this contribution we compare three correction methods, based on image matching, phase difference movement detection (PDMD), and cross‐correlation, respectively. The PDMD‐based method showed the best performance and was able to determine kidney movement in our test series in 68% of the scans with no visible deviation, and in 88% of the scans if a one‐pixel deviation is considered acceptable. J. Magn. Reson. Imaging 2001;14:741–749. © 2001 Wiley‐Liss, Inc.
Minimizing contrast agent dose during intraarterial gadolinium‐enhanced MR angiography: In vitro assessment
Authors: Hwang Ken‐Pin , Green Jordin D. , Li Debiao , Simonetti Orlando P. , Resnick Scott A. , Finn J. Paul , Duerk Jeffrey L. , Omary Reed A.
Published: August 2002

Purpose

To minimize contrast agent dosage for intra‐arterial (IA) contrast‐enhanced magnetic resonance angiography (CE‐MRA) by examining the effects of encoding order (elliptical vs. sequential) and injection duration (100% to 30% of the acquisition time).

Materials and Methods

Catheter‐based IA gadolinium (Gd) injections were performed in an arterial flow phantom. Blood flow rates, injection rates, and injection durations were systematically varied. Signal‐to‐noise (SNR) measurements were obtained in the aorta, renal artery, and common iliac artery.

Results

No significant SNR losses were observed for any of the vessels with 75% injection duration, or for the aorta and iliac artery with 50% injection duration. Excellent images of all vessels were obtained at 50% injection duration. There was no significant SNR difference between encoding schemes.

Conclusion

Contrast agent dosage can be substantially reduced without loss of SNR by limiting injection to part of the imaging acquisition time. J. Magn. Reson. Imaging 2002;15:55–61. © 2002 Wiley‐Liss, Inc.
Single breath‐hold extended free‐breathing navigator‐gated three‐dimensional coronary MRA
Authors: Huber Michael E. , Oelhafen Markus E. , Kozerke Sebastian , Weber Oliver M. , Boesiger Peter
Published: August 2002

Purpose

To acquire the center of k‐space while extending three‐dimensional free‐breathing navigator‐gated coronary magnetic resonance (MR) angiography by an initial single breath‐hold.

Materials and Methods

This approach was successfully applied in eight healthy adult subjects. Resulting images were compared with conventionally acquired free‐breathing navigator‐gated MR angiograms.

Results

The acquisition of k‐space center during the single breath‐hold resulted in a 26% increase (P < 0.05) of signal‐to‐noise ratio. Visible length of the right coronary artery, as well as contrast‐to‐noise ratio between the blood and the myocardial muscle, were identical.

Conclusion

The breath‐hold extension was shown to be a valuable technique that may be combined with first‐pass contrast‐enhanced MR imaging. J. Magn. Reson. Imaging 2002;15:210–214. © 2002 Wiley‐Liss, Inc.
Evaluation of hepatic lesions and hepatic parenchyma using diffusion‐weighted reordered turboFLASH magnetic resonance images
Authors: Moteki Takao , Horikoshi Hiroyuki , Oya Nariyuki , Aoki Jun , Endo Keigo
Published: August 2002

Purpose

To determine whether the centric reordered snapshot fast low‐angle shot (reordered turboFLASH) magnetic resonance (MR) images with no, low, and high motion‐probing gradients (MPGs) were useful to evaluate hepatic lesions and hepatic parenchyma.

Materials and Methods

The measured diffusion coefficient (D), deviation factor (f), and apparent diffusion coefficient for flowing spin (D*) values for 92 hepatic lesions (33 hepatocellular carcinomas (HCCs), 17 metastases, 27 hemangiomas, and 15 cysts) and the nonlesion‐bearing regions of parenchyma in 74 livers (46 noncirrhotic and 28 cirrhotic) were approximately calculated from the reordered turboFLASH images (modified for diffusion sensitivities of b = 0, 50.2, and 295 seconds/mm2).

Results

These groups, listed in order of decreasing D* and f values, were cysts, noncirrhotic livers, cirrhotic livers, hemangiomas, metastases, and HCCs. The order on the basis of D values was cysts, hemangiomas, metastases, HCCs, cirrhotic livers, and noncirrhotic livers. Noncirrhotic livers showed higher D* and f values, and lower D values than HCCs and metastases (P < 0.04).

Conclusion

The D* and f values, in addition to the D value, may be useful for evaluating the nature of diffusion and flowing spins in hepatic lesions and hepatic parenchyma. J. Magn. Reson. Imaging 2002;15:564–572. © 2002 Wiley‐Liss, Inc.
Streamlined flow in the portal vein: Demonstration with MR angiography
Authors: Gallix Benoît P. , Reinhold Caroline , Dauzat Michel , Bret Patrice M.
Published: August 2002

Purpose

To demonstrate whether streamlining of the portal vein flow exists by evaluating the relative distribution of blood flowing from the superior mesenteric vein (SMV) and splenic vein (SV) into the portal venous system.

Materials and Methods

Fifteen healthy adult volunteers underwent MR angiography of the main portal vein (PV) and portal vein branches after an overnight fast. Transverse two dimension time‐of‐flight gradient echo sequences were obtained three times, in suspended expiration and inspiration, respectively, as follows: 1) No presaturation slab, 2) presaturation slab across the SMV, 3) presaturation slab across the SV. Signal intensity (SI) measurements were obtained for all acquisitions. using regions of interest traced manually within the PV and portal branches.

Results

After presaturation of the SMV and SV during expiration, the overall SI average in the PV decreased by 47% ± 8 (mean ± SD) and 17% ± 9, respectively. Right to left portal branch SI ratio and right‐anterior to left‐posterior SI ratio in the PV were 0.91 ± 0.09 and 1.02 ± 0.08 at baseline, respectively. They decreased significantly (P < 0.05) to 0.87 ± 0.09 and to 0.95 ± 0.09 after saturation of the SMV, and increased significantly to 0.95 ± 0.08 and to 1.07 ± 0.10 after saturation of the SV.

Conclusion

MR angiography with selective saturation of the SMV and SV provided reproducible assessment of the respective contributions of the SMV and SV to portal flow, and allows demonstration that streamlining of splanchnic blood occurs in the portal vein of normal subjects. J. Magn. Reson. Imaging 2002;15:603–609. © 2002 Wiley‐Liss, Inc.
Dynamic imaging of the pelvic floor using an open‐configuration magnetic resonance scanner
Authors: Law P. A. , Danin J. C. , Lamb G. M. , Regan L. , Darzi A. , Gedroyc W. M.
Published: August 2002

The aims of this study were to develop a noninvasive, erect, gravity‐dependent method for assessing movements of the female pelvic floor, to describe the range of movements in pelvic floor ascent and descent in asymptomatic and symptomatic women, and to quantify any differences. A total of 102 women, 28–86 years of age, 35 symptomatic and 67 asymptomatic, were included in the study. They were scanned in a sitting position in an open scanner with good vertical access using fast‐gradient echo sequences fast spoiled grass (FSPGR). Measurements of the bladder base, uterocervical junction, and anorectal junction were taken in the sagittal plane. The levator ani (LA) muscle insertion was assessed in the coronal plane with the patients at rest, during maximal strain, and during maximum contraction of the pelvic floor. Premenopausal multiparous women have a significantly lower bladder base (8/0 mm above the baseline; P value = 0.009) and uterocervical junction (15.5/3.5 mm; P value = 0.03) at rest than nulliparous women, and this becomes more apparent on straining. Parity confers a more significant effect on the position and function of the pelvic floor than menopausal status. All pelvic organs are lower at rest and on straining in women with defecation difficulties (0/–24 mm; P value = 0.001). These differences are also seen when comparing women with and without urinary incontinence. Dynamic seated magnetic resonance imaging (MRI) shows that all the pelvic organs are lower at rest and on straining in multiparous women and in those with urinary incontinence than in a group of asymptomatic nulliparous volunteers. This difference is also seen in the position of the bladder base and anorectal junction during pelvic floor contraction. These findings suggest general pelvic floor weakness in women who present with symptoms in one compartment and indicate the need for evaluation of the entire pelvic floor particularly prior to surgery. J. Magn. Reson. Imaging 2001;13:923–929. © 2001 Wiley‐Liss, Inc.
MR renography by semiautomated image analysis: Performance in renal transplant recipients
Authors: de Priester Jacobus A. , Kessels Alphons G.H. , Giele Eelco L.W , den Boer Jacques A. , Christiaans Maarten H.L. , Hasman Arie , van Engelshoven Jos M.A.
Published: August 2002

We evaluated a method of semiautomated analysis of dynamic MR image series in renal transplants. Nine patients were studied twice, with an average time interval of 7 days. MR examination consisted of a run of 256 T1‐weighted coronal scans (GE; TR/TE/flip: = 11/3.4/60°; slice thickness = 6 mm; temporal resolution = 2 seconds). Gadolinium‐DTPA (0.05 mmol/kg) was injected with an injector pump (5 ml/seconds). MR renographs of the cortex and medulla were obtained by segmentation of the renal transplant and placement of two regions of interest (ROIs) overlying the peripheral and central renal parenchyma. In the first 100 frames of the renographs, analysis of variance (ANOVA) demonstrated significant intraclass correlation coefficients with mean values for the cortex and medulla of 0.47 and 0.59, respectively. We conclude that the procedure is a robust technique that generates meaningful signal curves. J. Magn. Reson. Imaging 2001;14:134–140. © 2001 Wiley‐Liss, Inc.
Diffusion‐weighted magnetic resonance imaging detects early neuropathology following four vessel occlusion ischemia in the rat
Authors: Gregory L. J. , O'Neill M. J. , Nunn J. A. , Gray J. A. , Williams S. C. R.
Published: August 2002

Early neuropathology following a prolonged duration of four‐vessel occlusion (4 VO) ischemia in the rat was charted using magnetic resonance imaging (MRI). Animals received either 30 minutes of 4 VO (N = 6) or sham operation (N = 6) prior to in vivo assessment. Proton density and T2 and combined T2/diffusion‐weighted (T2/DW) MRI were performed at 6, 24, and 72 hours postocclusion. T2/DW imaging was the most effective sequence for delineating between injured and intact tissues, indicating neuropathology in the dorsolateral striatum at 24 hours and in the CA1/CA2 subfields of the hippocampus at 72 hours following ischemia. Apparent diffusion coefficient values were significantly reduced in the striatum (P = 0.03) and hippocampus (P = 0.005) at 24 and 72 hours, respectively. This is the first report, to our knowledge, of T2/DW imaging detecting lesions following 4 VO in accord with the known temporal evolution of ischemic brain damage. J. Magn. Reson. Imaging 2001;14:207–214. © 2001 Wiley‐Liss, Inc.
An investigation into the use of sensitivity‐encoded techniques to increase temporal resolution in dynamic contrast‐enhanced breast imaging
Authors: Larkman David J. , deSouza Nandita M. , Bydder Mark , Hajnal Joseph V.
Published: August 2002

Gadolinium‐enhanced dynamic magnetic resonance (MR) imaging is playing an increasingly important diagnostic role in patients with breast cancer. Because of the multi‐focal nature of the disease, it is mandatory to cover all of both breasts, not only in the initial scan, but also at subsequent follow‐up. This requires volume acquisitions with a temporal resolution limited to 60–80 seconds, which is insufficient to clearly discriminate malignant from benign rates of contrast uptake. In this work, we performed sensitivity‐encoded imaging using a commercially available four‐channel breast coil (MRI Devices Corporation) on a commercial 0.5‐T scanner with moderate gradient performance to give increased temporal resolution in these dynamic contrast‐enhanced scans. A two‐fold increase in temporal resolution was readily achievable with this coil. Image reconstruction was robust and image quality was assessed qualitatively to be good. We also investigated higher speed‐up factors using two directions of sensitivity‐encoded reduction and discussed some of the potential artifacts associated with such imaging. J. Magn. Reson. Imaging 2001;14:329–335. © 2001 Wiley‐Liss, Inc.
MR ventilation‐perfusion imaging of human lung using oxygen‐enhanced and arterial spin labeling techniques
Authors: Mai Vu M. , Bankier Alexander A. , Prasad Pottumarthi V. , Li Wei , Storey Pippa , Edelman Robert R. , Chen Qun
Published: August 2002

Magnetic resonance ventilation‐perfusion (V/Q) imaging has been demonstrated using oxygen and arterial spin labeling techniques. Inhaled oxygen is used as a paramagnetic contrast agent in ventilation imaging using a multiple inversion recovery (MIR) approach. Pulmonary perfusion imaging is conducted using a flow‐sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER) technique. A half Fourier single‐short turbo spin echo (HASTE) sequence is used for data acquisition in both techniques. V/Q imaging was performed in ten of the twenty volunteers, while either ventilation or perfusion was imaged in the other ten. This V/Q imaging scheme is completely noninvasive, does not involve ionized radiation, and shows promising potential for clinical use in the diagnosis of lung diseases such as pulmonary embolism. J. Magn. Reson. Imaging 2001;14:574–579. © 2001 Wiley‐Liss, Inc.
Partial Fourier imaging in multi‐dimensions: A means to save a full factor of two in time
Authors: Xu Yingbiao , Haacke E. Mark
Published: August 2002

We present an improvement to the traditional one‐dimensional partial Fourier method by extending the method to multi‐dimensions. The modified method allowed a full factor of two savings in time with much better coverage of the central k‐space information and, because of this, smaller reconstruction artifacts. The residual magnitude error was found to correlate strongly with the residual phase error. Numerical simulation also indicated that with a priori perfect phase information, the original magnitude image could be perfectly reconstructed with half of the k‐space data points in the multi‐dimensional case. Simulated, phantom, and human data sets were tested with edge differences ranging from 10% (consistent with variable Gibbs ringing) to 25% (consistent with a blurred version of the object). The method was found to be a valuable adjunct to human imaging for short TR, T1‐weighted three‐dimensional gradient‐echo imaging and magnetic resonance (MR) angiographic methods, especially when short echo times were used. J. Magn. Reson. Imaging 2001;14:628–635. © 2001 Wiley‐Liss, Inc.
Tandem mass spectrum of a farnesyl transferase inhibitor— gas‐phase rearrangements involving imidazole
Authors: Qin Xue‐Zhi
Published: August 2002

Compound 1 (1‐(3‐chlorophenyl)‐4‐[1‐(4‐cyanobenzyl)imidazolylmethyl]‐2‐piperazinone hydrochloride) is a farnesyl transferase inhibitor intended for treatment of cancer. A detailed analysis of the electrospray ionization mass spectrometry and tandem mass spectrometry data of protonated 1 shows that in the gas phase, upon collision‐induced dissociation, this ion undergoes complicated rearrangement and fragmentation. These processes include a novel two‐step rearrangement. The first step involves a gas‐phase intramolecular SN2 reaction that forms an intermediate. The second step consists of three competitive rearrangement/fragmentation pathways of the intermediate, giving rise to protonated 2, protonated methylene‐imidazole, and a distonic methylimidazole radical cation. Deuterated 1 was studied under the same experimental conditions, and the results strongly support the proposed two‐step rearrangement process. It is noted that the unique structure of 1, especially the imidazole ring of 1, plays a critical role in the rearrangement of protonated 1. Copyright © 2001 John Wiley & Sons, Ltd.
Study of gas‐phase molecular recognition using Fourier transform ion cyclotron resonance mass spectrometry (FTICR/MS)
Authors: Dearden David V. , Liang Yongjiang , Nicoll Jeremy B. , Kellersberger Katherine A.
Published: August 2002

The application of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to the quantitative study of molecular recognition in the gas phase is reviewed. Because most quantitative measurements are dependent on accurate determination of the pressure of a neutral reagent, methods for accurate pressure measurement in FTICR, including gauge calibration using a reaction with known rate constants (the traditional method), exothermic proton transfer rate measurement (often the best method when accurate neutral pressures in the trapping cell are desired), and linewidth measurement (a little‐used, but generally applicable method) are discussed. The use of rate constant measurements in molecular recognition is illustrated with examples employing natural abundance isotopic labeling to study self‐exchange and 2 : 1 ligand:metal complex formation kinetics in crown ether–alkali cation systems. Self‐exchange rates do not correlate with alkali cation/crown cavity size relationships, whereas 2 : 1 complex formation kinetics correlate strongly with size relationships. The use of exchange equilibrium constant measurements to characterize molecular recognition is illustrated by alkali cation exchanges between 18‐crown‐6 and the isomers of dicyclohexano‐18‐crown‐6. These experiments show that the alkyl‐substituted ligand binds alkali cations better than unsubstituted 18‐crown‐6 in the gas phase, in accordance with expectations based on the higher polarizability of the alkyl‐substituted ligand. Further, the metal binding thermochemistry differs for the two dicyclohexano‐18‐crown‐6 isomers, with the bowl‐shaped cis–syn‐cis isomer binding all the alkali cations more strongly than the cis–anti‐cis isomer. The measurement of entropies and enthalpies associated with one of the most subtle forms of molecular recognition, enantiomeric discrimination, is illustrated by studies of the discrimination between enantiomers of chiral amines by dimethyldiketopyridino‐18‐crown‐6. This chiral ligand binds chiral primary ammonium cations that have the opposite absolute configuration at their stereocenter more strongly than the enantiomer with the same absolute configuration. Gas‐phase studies show that this enantiomeric discrimination is enthalpic in origin, likely related to more favorable π–π stacking for the preferred enantiomer. Entropy disfavors binding of the preferred enantiomer. Copyright © 2001 John Wiley & Sons, Ltd.
Change in hepatitis A virus seroepidemiology in southern Taiwan: a large percentage of the population lack protective antibody
Authors: Wang Shih‐Min , Liu Ching‐Chuan , Huang Yi‐Shen , Yang Yao‐Jong , Lei Huan‐Yao
Published: August 2002

Hepatitis A, the predominant reported etiologic form of viral hepatitis in Taiwan, continues to be a disease primarily of children and young adults. A seroepidemiologic study was performed to assess the seroprevalence of hepatitis A (HAV) antibodies in the southern Taiwan general population in 1998 and is compared with results of a similar study in 1992. A total of 948 subjects (477 male and 471 female) with ages ranging from 0.3 to 63 years were stratified into 14 age‐specific groups. The presence of anti‐HAV antibodies was detected using a commercially available radioimmunoassay. Fifteen percent of the subjects were positive for anti‐HAV antibodies, which is lower than that in 1992 (P < 0.001). Seroprevalences were 14.1% for males and 22.6% for females (P = 0.006). The pattern of anti‐HAV seroprevalence was distinguishable from that found in 1992; minimum seroconversion occurred at ages ranging from 1 to 30 years. Prevalence of seropositive subjects decreased markedly for the < 1, 13–15, 16–19, 20–24, 25–29, and 30–39 year age groups in comparing 1998 with 1992. The current study demonstrates a continuing decline in the prevalence of HAV among children, adolescents, and young adults. The findings can be ascribed to the improvement of socioeconomic status and modernization of environmental sanitation. As a consequence of this changing trend of endemicity and the resulting lack hepatitis A antibodies among the general population in Taiwan, the risk of sudden major outbreaks is increased because of increasing international travel and immigration, particularly during and after natural disasters. HAV vaccination will be important for the prevention and control of HAV outbreaks in the community. J. Med. Virol. 64:104–108, 2001. © 2001 Wiley‐Liss, Inc.
Dendritic cell susceptibility to hepatitis C virus genotype 1 infection
Authors: Navas Maria‐Cristina , Fuchs Anne , Schvoerer Evelyne , Bohbot Alain , Aubertin Anne‐Marie , Stoll‐Keller Françoise
Published: August 2002

In vitro infection of human monocyte‐derived dendritic cells was carried out to study their susceptibility to hepatitis C virus (HCV) infection. Immature dendritic cells and mature dendritic cells were incubated overnight at 37°C with HCV‐positive (genotype 1) serum samples; the presence of the viral genome associated with the production of its replicative intermediate was used as evidence of infection. In immature dendritic cells, HCV RNA was detectable from days 1–10 post‐infection (p.i.), and de novo synthesis of negative‐strand HCV RNA could be demonstrated by a strand‐specific rTth reverse transcription‐polymerase chain reaction at day 2. In mature dendritic cells, the positive‐strand form was detectable from days 1–5 p.i., while the negative‐strand HCV RNA appeared at days 1 and 2 p.i. Quasispecies present in the inoculum and 6 days p.i. were analyzed by sequencing hypervariable region 1 of the E2 protein. Only two of seven HVR variants present in the inoculum were found in HCV‐infected immature dendritic cells. Another two HVR variants not found in the inoculum were recovered from infected immature dendritic cells, suggesting serum minor variants selection or virus evolution during in vitro replication. Analysis by single‐strand conformation polymorphism assay of 5′ untranslated region of HCV sequences showed that the patterns obtained from the inoculum and infected immature dendritic cells and mature dendritic cells differed slightly. These findings indicate that both immature dendritic cells and mature dendritic cells are susceptible to HCV genotype 1 infection, supporting at least HCV RNA replication. This model should be a valuable tool for the study of modulation of dendritic cell functions in HCV infection. J. Med. Virol. 67:152–161, 2002. © 2002 Wiley‐Liss, Inc.
Characterization of Norwalk‐like virus associated with gastroenteritis in Indonesia*
Authors: Subekti D.S. , Tjaniadi P. , Lesmana M. , Simanjuntak C. , Komalarini S. , Digdowirogo H. , Setiawan B. , Corwin A.L. , Campbell J.R. , Porter K.R. , Oyofo B.A.
Published: August 2002

Norwalk Virus and Norwalk‐like viruses (NLVs) are reportedly responsible for 2.5–4.0% of nonbacterial acute gastroenteritis (NBAG) worldwide. To help clarify the impact of NLVs on NBAG in Indonesia, stool specimens from 102 patients, 74 with NBAG and 28 with BAG, were screened for the presence of NLVs, using a reverse transcription‐polymerase chain reaction (RT‐PCR) assay. The specimens were subtyped using prototype‐specific oligonucleotide probes and were sequenced and compared with published NLV sequences. Of the 102 specimens examined, 31 (30%) were found to be positive for NLVs. Type‐specific probe analysis of the RT‐PCR products indicated that 31 isolates hybridized to UK1 (Taunton agent) and UK3/4 (Hawaii agent/Snow Mountain agent) prototype strains. The results of this study indicate that prototype strains of NV or NLVs co‐circulate in Indonesia and contribute to the overall level of acute gastroenteritis throughout the region. J. Med. Virol. 67:253–258, 2002. © 2002 Wiley‐Liss, Inc.
Impaired sensory function in heterozygous P0 knockout mice is associated with nodal changes in sensory nerves
Authors: Samsam M. , Frei R. , Marziniak M. , Martini R. , Sommer C.
Published: August 2002

Mice heterozygously deficient in the major myelin component P0 are an established model of an inherited neuropathy and show signs of myelin degeneration in motor nerves. Unlike the case in patients, the sensory nerves are only mildly affected in the mouse mutants and do not show features indicative of myelin degeneration. Unexpectedly, by applying established behavioral tests, we found sensory deficits, as reflected by raised withdrawal thresholds to mechanical and thermal stimuli, whereas behavioral signs of a painful neuropathy were not detectable. By electron microscopy of longitudinal sections of sensory nerves, we found abnormalities in nodes of Ranvier comprising enlarged nodal gaps and poorly developed nodal Schwann cell microvilli. These alterations might be causally linked to the sensory deficits in the absence of profound myelin degeneration in the sensory nerves of the mutants. © 2002 Wiley‐Liss, Inc. © 2002 Wiley‐Liss, Inc.
Evidence for a localization of [3H]nociceptin binding sites on medullar primary afferent fibers
Authors: Le Cudennec C. , Suaudeau C. , Costentin J.
Published: August 2002

The ORL1 receptor (opioid receptor‐like 1) and its endogenous ligand, nociceptin, are involved in nociperception. We have studied, in a deafferented animal model, the modification of medullar [3H]nociceptin binding site density. A rhizotomy was carried out in rats at the cervicothoracic level, and the dorsal afferent fibers from C5 to T1 were lesioned. Seven days after surgery, animals were sacrificed, and the binding of [3H]nociceptin (2 nM) was then performed on spinal cord sections. An autoradiographic analysis revealed a significant reduction (–18%) of [3H]nociceptin binding site density in the dorsal horn ipsilateral to the deafferentation compared with the contralateral side of the lesion. In the ventral horn, no significant difference (–5%) of binding was observed in the ipsilateral side of the deafferentation compared with the contralateral side. Thus, [3H]nociceptin binding sites appear to be located mainly on either interneurons or deutoneurons of the spinal cord, because the bulk of the labeling is spared by the lesion. However, the significant reduction of labeling that occurs on the dorsal part of the ipsilateral side to the lesion indicates that [3H]nociceptin binding sites are also present on these dorsal afferent fibers. © 2002 Wiley‐Liss, Inc.
Glutamine as a pathogenic factor in hepatic encephalopathy
Authors: Albrecht Jan , Dolińska Monika
Published: August 2002

Hepatic encephalopathy (HE) results from acute or chronic liver dysfunction and is associated with hyperammonemia. Ammonium ions penetrate from blood to brain, where they form glutamine (Gln) in the reaction with glutamate catalyzed by an astroglia‐specific enzyme, glutamine synthetase (GS). Experimental data suggest that many manifestations of HE can be ascribed to increased Gln synthesis and accumulation in the brain. In HE resulting from acute liver failure (“fulminant hepatic failure”), the osmotic action of Gln appears to be in a large degree responsible for cerebral edema and edema‐associated disturbances of cerebral blood flow and ionic homeostasis. In chronic HE not accompanied by cerebral edema, Gln contributes to impairment of cerebral energy metabolism, and its increased transport from brain to the periphery accelerates the blood‐to‐brain transport of aromatic amino acids, of which tryptophen (Trp) is converted to metabolites directly implicated in HE. Most of the evidence that Gln participates in pathological events has been derived from their disappearance or amelioration in HE rats in which the cerebral Gln content was reduced by treatment with a GS inhibitor, methionine sulfoximine. J. Neurosci. Res. 65:1–5, 2001. © 2001 Wiley‐Liss, Inc.
Cysteine dioxygenase: Regional localisation of protein and mRNA in rat brain
Authors: Parsons R.B. , Waring R.H. , Williams A.C. , Ramsden D.B.
Published: August 2002

Cysteine dioxygenase (CDO) converts cysteine to cysteinesulphinic acid and is the rate‐limiting step in sulphate production. Most studies have centred upon the hepatic form of the enzyme, but several studies have investigated brain CDO using activity assays and western blotting. The aim of this study was to investigate the expression of CDO in the rat brain using a combination of immunohistochemistry and in situ hybridisation. Affinity‐purified anti‐R and anti‐H CDO antibodies were immunoprecipitated using rat brain homogenate to determine whether the antibodies could remove enzyme activity. Immunohistochemistry and in situ hybridisation were then used to determine the cellular and regional expression of both CDO protein and mRNA. Immunoprecipitation of rat brain homogenate removed up to 98% and 70% (anti‐R and anti‐H, respectively) of enzyme activity. Nonimmune sheep serum had no effect upon enzyme activity. CDO protein and mRNA was localised solely to the neurones of the brain, including the pyramidal cells of the hippocampus and the Purkinje cells of the cerebellum. Regional localisation varied, with high levels of expression in the hippocampus, the dentate gyrus, the outer cortices of the brain, and the substantia nigra. The relative expression of CDO activity and protein in these regions is most probably a result of the relative abundance of neurones in these regions. CDO expression in the brain may have several possibile functions, the most likely being the prevention of free radical production by the autoxidation of cysteine and dopamine. J. Neurosci. Res. 65:78–84, 2001. © 2001 Wiley‐Liss, Inc.
Proximal ligand effects on electronic structure and spectra of compound I of peroxidases
Authors: HARRIS DANNI L. , LOEW GILDA H.
Published: August 2002

Computational studies exploring the extent to which differences in proximal axial ligands modulate structure, spectra, and function of peroxidases have been performed. To this end, three heme models of compound I were characterized differing only in the axial ligand. The axial ligands considered were L = ImH , Im-, that are alternative protonation models for a typical peroxidase with an imidazole ligand such as horseradish peroxidase (HRP-I), and L = SCH - that is a model for an unsual peroxidase, chloroperoxidase (CPO-I). Density functional calculations (DFTs) were performed to determine the optimized geometries and electronic structure of each of these three species. Their electronic spectra were also calculated at the DFT optimized geometries, using the INDO/S/CI method. The results of these studies led to the following conclusions: (1) the presence of the nearby Asp in a typical peroxidase does indeed decrease the energy required to deprotonate the imidazole making the two forms essentially degenerate, (2) neither the state of protonation of the imidazole ligand nor the change in axial ligand from an imidazole in typical peroxidases such as HRP to a mercaptide in CPO significantly alters the characteristics of the lowest energy spin state or the electronic structure of compound I in a way that can obviously affect function, (3) both the Im-and ImH forms of the peroxidase compound I (HRP-I) lead to the same dramatic reduction in intensity relative to the ferric resting form observed experimentally. However, only in the ImH form of HRP-I does the calculated relative shift of one component of the Soret bands relative to CPO-I agree with that observed in the transient spectra of HRP-I compared to CPO-I. These results taken together strongly indicate that factors other than the nature of the proximal axial ligand are the main determinants of function.
A transient form of 2-aza-21-carbaporphyrin prearranged for fusion: DFT studies
Authors: SZTERENBERG LUDMIŁA , LATOS-GRAŻYŃSKI LECHOSŁAW
Published: August 2002

The formation mechanism of the fused porphyrin (CTPPH-NF) involves a rotation of the N(2) pyrrole ring of 2-aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH2) which is subsequently followed by formation of the C(3)–N(24) bond to yield the macrocycle with the fused pyrrole tripentacyclic ring. To approach the problem of the relative stability of the prearranged transient species theoretical investigations have been performed applying density functional theory (DFT). The molecular structures and electronic energy have been studied for idealized 2-aza-21-carbaporphyrin (CPPH2) and porphyrin (PH2) macrocycles created by a replacement of phenyl or other substituents with hydrogen or methyl groups. The following forms of 2-aza-21-carbaporphyrin and porphyrin were studied: CPH2-I, 2-NH-CPH-I and PH2-I in relation to CPH2-P, 2-NH-CPH-P and PH2-P, respectively (P indicates regular geometry (N(21) or C(21) located in the inner perimeter) and I indicates inverted geometry (N(21) or C(21) located in the outer perimeter).

A π delocalization exists through the inverted macrocycles: PH2-I, CPH2-I and 2-NH-CPH-I. The B3LYP/6-31G** optimized bond distances of I macrocycles reproduce the pattern of the P counterparts. The B3LYP/6-31G**//B3LYP/6-31G** calculated energy differences between the P and I structures are very similar for two considered 2-aza-21-carbaporphyrin tautomers: CPH 2-P → CPH 2-I, 18.50 kcal mol-1, 2- NH - CPH -P → 2- NH - CPH -I, 17.55 kcal mol-1; but essentially different for the regular porphyrin PH2-P → PH 2-I, 45.56 kcal mol-1. The methyl substitution at the 21-carbon or 5 and 20 meso positions preserved the order of stability as the calculated energy differences equal 21- CH 3- CPH 2-P → 21- CH 3- CPH 2-I, 13.39 kcal mol-1; 5,20- CH 3- CPH 2-P → 5,20- CH 3- CPH 2-I, 17.87 kcal mol-1.
The nature of the bonding between metalloporphyrins [Fe(II), Co(II), Mn(II)] and oxygen species (·O2·, H2+O·/HO·, HOO·, ·O·)
Authors: SAWYER DONALD T.
Published: August 2002

The interaction of reduced transition-metal porphyrins [e.g. PMn (II), PFe (II), PCo (II)] with oxygen species (· O 2·, H 2+ O ·/ HO ·, HOO ·, · O ·) involves radical/radical coupling to form covalent bonds. Coordinately unsaturated iron(II) porphyrins form two sigma bonds with · O 2·(-Δ G BF = 1–6 kcal mol -1) via two of the four unpaired d-electrons of the iron center. The hydroxyl radical [Formula: see text] couples with an unpaired electron of the PM (II) porphyrins to form a single covalent bond [[Formula: see text], PM III– OH ]. The bond energies (-Δ G BF ) for [Formula: see text] and [Formula: see text] are 65 ± 4 and 58 kcal mol-1, respectively. Under neutral conditions the uncharged species [( Cl 8 TPP ) Mn III– OH , ( Cl 8 TPP ) Fe III– OH , (Cl8TPP)CoIII- OH ] have bond-formation energies (-Δ G BF ) of 70 ± 4, 63, and 61 kcal mol-1, respectively. In acetonitrile solutions atomic oxygen (· O ·; derived from ozone, O 3) couples with ( Cl 8 TPP ) Mn III[ ClO 4], ( Cl 8 TPP ) Mn II, ( Cl 8 TPP ) Fe III[ ClO 4], and ( Cl 8 TPP ) Fe II to form ( Cl 8 TPP +) Mn V O (-ΔG BF = 59 ± 4 kcal mol -1), ( Cl 8 TPP ) Mn IV= O (85 kcal mol -1), ( Cl 8 TPP +·) Fe IV= O (68 kcal mol -1; model for compound I of horseradish peroxidase), and ( Cl 8 TPP ) Fe IV= O (78 kcal mol -1; model for compound II of horseradish peroxidase). The weakly bonded species [( Cl 8 TPP +) Mn V= O and ( Cl 8 TPP +·) Fe IV= O ] epoxidize olefins with near-stoichiometric efficiency; the other two species are essentially unreactive with olefins.
Palaeoenvironmental significance of the mammalian faunas of Italy since the Pliocene
Authors: Montuire Sophie , Marcolini Federica
Published: August 2002

The evolution of mammalian communities is a significant tool for reconstructing past environments and climate. In this paper, a palaeoecological and palaeoenvironmental reconstruction based on the study of the Italian mammal faunas ranging from Middle Pliocene to the Holocene is presented using the cenogram method and quantification of temperatures based on arvicolid species richness. These analyses reveal open and arid conditions during glacial periods and less open and more humid conditions during interglacials, with some differences between north and central–south Italy. Northern and Southern communities reflect similar trends in the evolution of palaeoenvironments and in the variation of the temperatures, but differences in estimated temperatures, which indicate a more temperate climate for southern Italy throughout the period, are considered here. Copyright © 2002 John Wiley & Sons, Ltd.
Green function method and its application to the resonance Raman effect
Authors: Ovander L. N. , Shadura V. A.
Published: August 2002

The advantages of the Green function method for considerations in resonant Raman scattering are shown. It is possible to avoid difficulties which arise when the frequency of incident light is in the excitonic absorption band. Copyright © 2001 John Wiley & Sons, Ltd.