bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dental homologies in lamniform sharks (Chondrichthyes: Elasmobranchii)
Authors: Shimada Kenshu 
Published: August 2002

AbstractThe dentitions of lamniform sharks are said to exhibit a unique heterodonty called the “lamnoid tooth pattern.” The presence of an inflated hollow “dental bulla” on each jaw cartilage allows the recognition of homologous teeth across most modern macrophagous lamniforms based on topographic correspondence through the “similarity test.” In most macrophagous lamniforms, three tooth rows are supported by the upper dental bulla: two rows of large anterior teeth followed by a row of small intermediate teeth. The lower tooth row occluding between the two rows of upper anterior teeth is the first lower anterior tooth row. Like the first and second lower anterior tooth rows, the third lower tooth row is supported by the dental bulla and may be called the first lower intermediate tooth row. The lower intermediate tooth row occludes between the first and second upper lateral tooth rows situated distal to the upper dental bulla, and the rest of the upper and lower tooth rows, all called lateral tooth rows, occlude alternately. Tooth symmetry cannot be used to identify their dental homology. The presence of dental bullae can be regarded as a synapomorphy of Lamniformes and this character is more definable than the “lamnoid tooth pattern.” The formation of the tooth pattern appears to be related to the evolution of dental bullae. This study constitutes the first demonstration of supraspecific tooth‐to‐tooth dental homologies in nonmammalian vertebrates. J. Morphol. 251:38–72, 2002. © 2002 Wiley‐Liss, Inc.
Towards a rational development of anti‐endotoxin agents: novel approaches to sequestration of bacterial endotoxins with small molecules
Authors: David Sunil A. 
Published: August 2002

AbstractEndotoxins, or lipopolysaccharides (LPS), present on the surface of Gram‐negative bacteria, play a key role in the pathogenesis of septic shock, a common clinical problem and a leading cause of mortality in critically ill patients, for which no specific therapeutic modalities are available at the present time. The toxic moiety of LPS is a glycolipid called ‘lipid A’, which is composed of a bisphosphorylated diglucosamine backbone bearing up to seven acyl chains in ester and amide linkages. Lipid A is structurally highly conserved in Gram‐negative bacteria, and is therefore an attractive target for developing anti‐endotoxin molecules designed to sequester, and thereby neutralize, the deleterious effects of endotoxins.  The anionic and amphipathic nature of lipid A enables the interaction of a wide variety of cationic amphiphiles with the toxin. This review describes the systematic evaluation of several structural classes of cationic amphiphiles, both peptides and non‐peptidic small molecules, in the broader context of recent efforts aimed at developing novel anti‐endotoxin strategies. The derivation of a pharmacophore for LPS recognition has led to the identification of novel, nontoxic, structurally simple small molecules, the lipopolyamines. The lipopolyamines bind and neutralize LPS inin vitroexperiments as well as in animal models of endotoxicity, and thus present novel and exciting leads for rational, structure‐based development of LPS‐sequestering agents of potential clinical value. Copyright © 2001 John Wiley & Sons, Ltd.
Contrast‐enhanced high resolution MRI for atherosclerotic carotid artery tissue characterization
Authors: Yuan Chun , Kerwin William S. , Ferguson Marina S. , Polissar Nayak , Zhang Shaoxiong , Cai Jianming , Hatsukami Thomas S. 
Published: August 2002

AbstractPurposeTo determine if a gadolinium‐based contrast agent provides additional information for characterization of human plaque tissues, particularly neovasculature. Although high‐resolution magnetic resonance imaging (MRI) has been used to identify plaque constituents in advanced atherosclerosis, some constituents, such as neovascularized tissue, defy detection.Materials and MethodsNon‐contrast‐enhanced carotid artery images from 18 patients scheduled for carotid endarterectomy and two normal volunteers were used to identify regions of fibrous tissue, necrotic core, or calcification, using established criteria. Then, the percent change in T1‐weighted images after contrast enhancement was calculated for each region.ResultsThere were statistically significant differences in mean intensity change between tissues, with the largest increase for fibrous tissue (79.5%) and the smallest for necrotic core (28.6%). Additionally, histological analysis showed that a subset of fibrous regions rich in plaque neovascularization could be identified using a threshold of 80% enhancement (sensitivity = 76%, specificity = 79%).Conclusion: The ability of contrast‐enhanced MRI to identify neovascularization and potentially improve differentiation of necrotic core from fibrous tissue further establishes MRI as a viable tool for in vivo study of atherosclerotic plaque. J. Magn. Reson. Imaging 2002;15:62–67. Published 2002 Wiley‐Liss, Inc.
Functional cardiac MR imaging with steady‐state free precession (SSFP) significantly improves endocardial border delineation without contrast agents
Authors: Thiele Holger , Nagel Eike , Paetsch Ingo , Schnackenburg Bernhard , Bornstedt Axel , Kouwenhoven Marc , Wahl Andreas , Schuler Gerhard , Fleck Eckart 
Published: August 2002

AbstractContrast between blood and myocardium in standard turbo gradient echo MR techniques (TFE) used routinely in clinical practice is mainly caused by unsaturated inflowing blood. Steady‐state free precession (SSFP) has excellent contrast even in the absence of inflow effects. In 45 subjects cardiac cine loops in two long axis projections were acquired using TFE and compared with SSFP. A visual score (range 0 worst – 3 best) was assigned for endocardial border delineation for six myocardial segments in two long axis views. Endocardial border delineation score for TFE was 1.3 ± 0.3 per segment and 2.4 ± 0.3 for SSFP (P < 0.0001). Signal intensity blood/signal intensity myocardium was 1.5 ± 0.4 at enddiastole and 1.4 ± 0.3 at systole for TFE and 3.5 ± 1.1 and 3.2 ± 1.3 for SSFP, respectively (P < 0.0001). SSFP increases contrast between blood and myocardium more than twofold, resulting in an improved endocardial border definition. This may reduce variability for the determination of cardiac volumes and ejection fraction. J. Magn. Reson. Imaging 2001;14:362–367. ©2001 Wiley‐Liss, Inc.
Functional assessment of pancreatic parenchyma after secretin administration using serial T2‐weighted echo‐planar magnetic resonance imaging
Authors: Masui Takayuki , Katayama Motoyuki , Kobayashi Shigeru , Ito Tatsuhiko , Kabasawa Hiroyuki , Nozaki Atsushi , Sakahara Harumi 
Published: August 2002

AbstractSignal intensity (SI) changes of pancreatic parenchyma were evaluated after intravenous administration of secretin using T2‐weighted single‐shot spin‐echo echo‐planar imaging (EPI) to assess this method as a magnetic resonance (MR) test of pancreatic exocrine function. Nine volunteers were studied with serial single‐shot EPI of the pancreas for 15 minutes after the injection of secretin or saline. The normal pattern of pancreatic SI change was demonstrated after intravenous injection of secretin, a single peak at 3–4 minutes in the head, body, and tail, followed by a gradual decrease in SI. Saline injection did not induce a significant SI change. There was no statistical difference in the peak contrast ratios (first mean, 1.21–1.25, vs. second mean, 1.18–1.22) and peak times (first mean, 3.2–3.7 minutes, vs. second mean, 3.1–3.6) in a repeat study. By evaluating the pattern of time‐response curves obtained from serial T2‐weighted EPI after secretin injection, pancreatic exocrine function may be directly assessed at the level of the head, body, and tail. J. Magn. Reson. Imaging 2001;14:450–456. © 2001 Wiley‐Liss, Inc.
Reproducibility of T2* blood volume and vascular tortuosity maps in cerebral gliomas
Authors: Jackson A. , Kassner A. , Zhu X.P. , Li K.L. 
Published: August 2002

AbstractThe development of anti‐angiogenic therapies for tumors has led to a demand for imaging‐based surrogate markers of the angiogenic process. The utility of such markers is highly dependent on their test‐retest reproducibility. This paper presents a formal assessment of the reproducibility of measurements of relative blood volume (rBV), normalized rBV (rBVnorm), and vascular tortuosity as estimated by measurement of relative recirculation (rR). The study was conducted in 11 patients with glioma who were scanned on two occasions 36–56 hours apart. The observed reliability estimates were used to calculate 95% confidence limits for detection of differences between groups and for changes in individual cases. The results show that measurement of rBV or rBVnorm in consecutive studies is statistically capable of reliably detecting changes in excess of 15% in between group studies and 25% in individual patients. Measurement of vascular tortuosity using is less reproducible but is able to confidently identify changes in excess of 30% in group studies and 35% in individuals. J. Magn. Reson. Imaging 2001;14:510–516. © 2001 Wiley‐Liss, Inc.
Improved high resolution MR imaging for surface coils using automated intensity non‐uniformity correction: Feasibility study in the orbit
Authors: Vokurka Elizabeth A. , Watson Nick A. , Watson Yvon , Thacker Neil A. , Jackson Alan 
Published: August 2002

AbstractThis study examined the effects of a recently developed automated intensity non‐uniformity correction on surface coil images using the orbit as an exemplar. Images were obtained using a standard head coil and a range of surface coils. Slices through the optic nerve head and cavernous sinus were subjected to the correction algorithm. Blind forced‐choice rankings of the subjective image quality were performed. Quantitative measurements were taken of the similarity between vitreous humor at two depths from the coil, and of the conspicuity between orbital fat and temporalis muscle intensities. The combined qualitative ranks for corrected surface coil images were higher than for the equivalent uncorrected images in all cases. Intensity non‐uniformity correction produced statistically significant improvements in orbital surface coil images, bringing their intensity uniformity in homogeneous tissue to the level of head coil images. The subjective quality of the corrected surface coil images was superior to head coil images, due to increased spatial resolution combined with improved signal to noise ratio across the image. J. Magn. Reson. Imaging 2001;14:540–546. © 2001 Wiley‐Liss, Inc.
A method for fast 3D tracking using tuned fiducial markers and a limited projection reconstruction FISP (LPR‐FISP) sequence
Authors: Flask Chris , Elgort Daniel , Wong Eddy , Shankaranarayanan Ajit , Lewin Jonathan , Wendt Michael , Duerk Jeffrey L. 
Published: August 2002

AbstractThis work demonstrates the feasibility of using wireless, tuned fiducial markers with a limited projection reconstruction–fast imaging with steady‐state free precession sequence (LPR‐FISP) to accurately obtain tracking information necessary for interactive scan plane selection in magnetic resonance imaging (MRI). The position and orientation of a rigid interventional device can be uniquely determined from the 3D coordinates of three fiducial markers mounted in a known configuration on the device. Three fiducial markers were tuned to the proton resonant frequency in a 0.2T open MR scanner and mounted to the surface of a cylindrical water phantom. An LPR‐FISP sequence was developed to suppress the water phantom signal while preserving that of the fiducial markers through a nonselective low‐tip‐angle excitation and a dephaser gradient applied prior to data acquisition. A localization algorithm was developed to accurately calculate the 3D coordinates of the fiducial markers using four LPR‐FISP projections in two orthogonal scan planes. The sequence repetition time (TR = 21 msec) and the limited projection set resulted in fast LPR‐FISP coordinate acquisition times of approximately 170 msec with an accuracy (max error) of 3 mm on a 0.2T MR system. This fast, accurate tracking method provides the fundamental technology for interactive MRI scan plane definition for rigid interventional devices without the need for stereotactic cameras or reference frames. J. Magn. Reson. Imaging 2001;14:617–627. © 2001 Wiley‐Liss, Inc.
Analysis of ethoxylated nonionic surfactants and their metabolites by liquid chromatography/atmospheric pressure ionization mass spectrometry
Authors: Petrovic M. , Barceló D. 
Published: August 2002

AbstractThe widespread use and questionable environmental acceptability of nonionic surfactants make the alkylphenol ethoxylates (APEOs) and their neutral and acidic degradation products a focus of interest in environmental analytical chemistry. The characterization and especially quantification of polyethoxylate mixtures in environmental matrices is a challenge, because of the complexity of the mixtures. A review on trace analysis of APEOs using atmospheric pressure ionization mass spectrometry, including sample preparation and liquid chromatographic separation, is presented. In this Special Feature, the performances of two ionization methods, atmospheric pressure chemical ionization and electrospray ionization, is discussed in terms of selectivity and sensitivity toward oligomeric mixtures of APEOs. Capabilities and limitations associated with the liquid chromatographic/mass spectrometric detection of APEOs, their main degradation products and their halogenated metabolites, and also specific issues related to the sample preparation, formation of fragments, adducts and cluster ions, quantification of oligomeric mixtures and signal suppression effects in complex matrices, are discussed. Conclusions and future perspectives are outlined. Copyright © 2001 John Wiley & Sons, Ltd.
Theoretical analysis of the effect of amplified luminescence on the modulation response of laser diodes
Authors: Burov L. I. , Gribkovskii V. P. , Grigelevich P. S. , Kramar M. I. , Ryabtsev G. I. , Shore K. A. , Voitikov S. V. , Kragler R. 
Published: August 2002

AbstractA theoretical framework is established for the investigation of the effect of amplified luminescence, non‐radiative recombination, photon losses, and gain non‐linearity on the threshold current characteristics and small‐signal modulation responses of bulk and quantum‐well (QW) 1.3 and 1.55 µm InxGa1−xAsyP1−y/InP laser diodes. It is shown that the rate of recombination induced by amplified luminescence exhibits a highly non‐linear dependence on both carrier concentration and temperature. Amplified luminescence and Auger recombination increase the laser threshold and contribute strongly to the device threshold current temperature sensitivity. Amplified luminescence and Auger recombination are shown to have a significant detrimental effect on the modulation properties of long‐wavelength laser diodes. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of glutamine and GABA on [U‐13C]glutamate metabolism in cerebellar astrocytes and granule neurons
Authors: Qu Hong , Konradsen Jon R. , van Hengel Marike , Wolt Saskia , Sonnewald Ursula 
Published: August 2002

AbstractTo probe the effect of glutamine and GABA on metabolism of [U‐13C]glutamate, cerebellar astrocytes were incubated with [U‐13C]glutamate (0.5 mM) in the presence and absence of glutamine (2.5 mM) or GABA (0.2 mM). It could be shown that consumption of [U‐13C]glutamate was decreased in the presence of glutamine and release of labeled aspartate and [1,2,3‐13C]glutamate decreased as well, whereas the concentrations of these metabolites increased inside the cells. Glutamine decreased energy production from [U‐13C]glutamate presumably by substituting for glutamate as an energy substrate. No additional effect was seen in the presence of both glutamine and GABA. When cerebellar granule neurons were incubated with [U‐13C]glutamate (0.25 mM) and GABA (0.05 mM), less [U‐13C]glutamate was used for energy production than in controls. Because the barbiturate thiopental did not elicit such response (Qu et al., 2000, Neurochem Int 37:207–215) it appears that GABA also has a metabolic function in the glutamatergic cerebellar granule neurons in contrast to the astrocytes. © 2001 Wiley‐Liss, Inc.
Lectin‐induced apoptosis of mature olfactory receptor cells
Authors: Moon Young Wha , Baker Harriet 
Published: August 2002

AbstractPrevious studies showed that uptake of the lectin conjugate, wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) by olfactory receptor cells results in a thinning of the olfactory epithelium (OE) and increased turnover of globose basal cells. To ascertain the cell‐type lost as well as the time course and mechanism of the loss, the current study measured changes in the number of dendritic knobs, olfactory marker protein (OMP) expression and assessed TUNEL labeling as an indicator of apoptosis. Electron microscopic analysis of the number of dendritic knobs showed that the largest reduction occurred at 1 week after intranasal irrigation with WGA‐HRP. This data in conjunction with decreased OMP staining provided evidence for a loss of mature receptor neurons. TUNEL labeling, especially in more superficial aspects of the OE, peaked at 18 hr after WGA‐HRP application suggesting that the lectin‐conjugate produced a rapid induction of apoptotic cell death that was complete by 3 days. Measurement of tyrosine hydroxylase (TH) activity in the olfactory bulb, a sensitive measure of deafferentation, showed that innervation reached a nadir at about 1 week and that reinnervation was complete by 4 weeks. These findings demonstrate that internalization of WGA‐HRP by some receptor cells results in their death by apoptosis and a subsequent deafferentation of the olfactory bulb. © 2002 Wiley‐Liss, Inc.
Transformation of donor‐derived bone marrow precursors into host microglia during autoimmune CNS inflammation and during the retrograde response to axotomy
Authors: Flügel Alexander , Bradl Monika , Kreutzberg Georg W. , Graeber Manuel B. 
Published: August 2002

AbstractMacrophages in the brain can have a triple source. They may originate from recently blood‐derived precursors, from the largely resident perivascular cell population (perivascular macrophages and related cells), and from intrinsic parenchymal as well as perivascular microglia. Although continuous exchange of part of the perivascular cell population with bone marrow‐derived precursors is now accepted, the turnover of adult parenchymal microglia has remained enigmatic. Using bone‐marrow chimeras carrying an unexpressed marker gene and carbon labeling of peripheral monocyte/macrophages in a combined model of facial nerve axotomy and transfer experimental autoimmune encephalitis, we demonstrate for the first time that there is an easy to induce exchange between parenchymal central nervous system (CNS) microglia and the macrophage precursor cell pool of the bone marrow. Furthermore, very low level infiltration of the CNS parenchyma by recently bone marrow‐derived microglia could be observed after simple peripheral nerve axotomy that is followed by neuronal regeneration. Thus, microglial cells can be considered wanderers between the peripheral immune system and the CNS where they may act as a “Trojan horse” in infections. The fact that recently bone marrow‐derived parenchymal microglia fully integrate into a regenerating brain nucleus' architecture encourages entirely new approaches for delivering genes into the adult CNS. J. Neurosci. Res. 66:74–82, 2001. © 2001 Wiley‐Liss, Inc.
Neurotoxicant‐induced elevation of adrenomedullin expression in hippocampus and glia cultures
Authors: Jahnke G.D. , Brunssen S. , Maier W.E. , Harry G.J. 
Published: August 2002

AbstractAdrenomedullin (AM), a vasoactive peptide first isolated from pheochromocytoma, has been reported to be present in neurons in the central nervous system and in tumors of neural and glial origin. In this study, we investigated AM expression both in the hippocampus and in glial cell cultures using a chemical‐induced model of injury. An acute intraperitoneal injection of the organometal trimethyltin (TMT) results in neurodegeneration of the hippocampal CA3–4 pyramidal cell layer. Within 4 days of injection, sparse, punctate staining for AM and lectin was evident in the CA3–4 region; by 10 days, a minimal level of CA3–4 neuronal degeneration was evident, with an increase in glial fibrillary acidic protein (GFAP)‐positive astrocytes throughout the hippocampus. Degeneration progressed in severity until 30 days post‐TMT, with distinct positive immunoreactivity for AM in the CA4 region. mRNA levels for tumor necrosis factor (TNF)‐α, interleukin (IL)‐1α, GFAP, and AM in the hippocampus were increased over control levels within 4 days following TMT. In cultured glial cells, a 6 hr exposure to TMT (10 μM) produced a morphological response of the cells and increased immunoreactivity for vimentin, GFAP, and AM. mRNA levels for TNFα, IL‐1α, GFAP, vimentin, and AM were elevated within 3–6 hr of exposure. In culture, neutralizing antibodies to IL‐1α and TNFα were effective in inhibiting the TMT‐induced elevation of AM mRNA. These data suggest an interaction between the proinflammatory cytokines and glia response in the regulation of AM in response to injury. J. Neurosci. Res. 66:464–474, 2001. Published 2001 Wiley‐Liss, Inc.
Disaggregating climatic trends by classification of circulation patterns
Authors: Huth Radan 
Published: August 2002

AbstractThe trends in occurrence frequencies of circulation types over Europe and in nine climate variables in the Czech Republic conditioned by the types are examined for period 1949–1980. The circulation types are determined by an objective procedure from daily 500 hPa heights. Both in summer and winter, anticyclonic types have become more frequent at the expense of cyclonic types. The circulation changes are shown to be unrelated to the trends in surface climate elements in summer, whereas in winter, trends in circulation explain a part of the observed warming and strengthening of southerly winds.The trends in climate elements are not uniform among circulation types. In summer, the trend pattern consisting of decreasing maximum and daily mean temperatures, daily temperature range (DTR) and sunshine duration, and increasing cloudiness and relative humidity is observed under the cyclonic types and the types with a well‐pronounced jet, but is missing under types with a blocking anticyclone over Europe. Two possible mechanisms causing this trend pattern are proposed: increasing cloudiness, and a process responsible for the reduction of sunshine without a concurrent increase of cloudiness. The latter mechanism can possibly be identified with increasing aerosol concentrations. In winter, the degree of warming is governed by changes in zonal wind. The mechanism of change in DTR seems to vary with elevation: at the lowland station (Prague‐Klementinum), the increase in DTR is related to the warming trend, and consequently with zonal wind changes, while at the mountain station (Milešovka), the increase in DTR reflects the increase in precipitating clouds.The changes in DTR are related much more to mid‐tropospheric circulation than to cloud cover in summer, whereas in winter, cloud cover plays a more important role in affecting DTR trends. Copyright © 2001 Royal Meteorological Society