bluuebunny/crossref_metadata_2025_split huggingface dataset:
Architecture of the integument in lower teleostomes: Functional morphology and evolutionary implications
Authors: Gemballa Sven , Bartsch Peter 
Published: October 2002

AbstractA bony ganoid squamation is the plesiomorphic type in actinopterygians. During evolution, it was replaced by weak and more flexible elasmoid scales. We provide a comparative description of the integument of “ganoid” fishes and “nonganoid” fishes that considers all dermal components of mechanical significance (stratum compactum, morphology of ganoid scales, and their regional differences) in order to develop a functional understanding of the ganoid integument as a whole. Data were obtained for the extant “ganoid” fishes (Polypteridae and Lepisosteidae) and for closely related “lower” actinopterygians (Acipenser ruthenus, Amia calva) and “lower” sarcopterygians (Latimeria chalumnae, Neoceratodus forsteri). Body curvatures during steady undulatory locomotion, sharp turns, prey‐strikes, and fast starts in “ganoid” fishes were measured from videotapes. Extreme body curvatures as measured in anesthetized specimens are never reached during steady swimming, but are sometimes closely approached in certain situations (sharp turns, prey‐strike). During extreme body curvatures we measured high values of lateral strain on the convex and on the concave side of the body. Scale overlap changes considerably (66–127% in Lepisosteus, 42–140% in Polypterus). The ganoid squamation forms a protective coat, but at the same time it permits extreme body curvatures. This is reflected in characteristic morphological features of the ganoid scales, such as an anterior process, concave anterior margin, and peg‐and‐socket articulation. These characters are most pronounced in the anterior body region, where maximum changes in scale overlap are required. The anterior processes and anterior concave margin, together with the attached stratum compactum, guide movements in a horizontal plane during bending. Displacements of scales relative to each other are possible for scales of different scale rows, but are impeded in scales of the same scale row due to the peg‐and‐socket articulation. Furthermore, ganoid scale rows, fibers of collagen layers of the stratum compactum, and the lateral myoseptal structures follow the same oblique orientation, which is needed to achieve extreme body curvatures. There is no evidence that body curvatures are limited by the ganoid squamation in Polypterus or Lepisosteus to any larger extent than by a type of integument devoid of ganoid scales in teleostomes of similar body shape. Our results essentially contradict former functional interpretations: 1) Ganoid scales do not especially limit body curvature during steady undulatory locomotion; 2) They do not act as torsion‐resisting devices, but may be able to damp torsion together with the stratum compactum and internal body pressure. J. Morphol. 253:290–309, 2002. © 2002 Wiley‐Liss, Inc.
Pelvic and hindlimb musculature of Tyrannosaurus rex (Dinosauria: Theropoda)
Authors: Carrano Matthew T. , Hutchinson John R. 
Published: October 2002

AbstractIn this article, we develop a new reconstruction of the pelvic and hindlimb muscles of the large theropod dinosaur Tyrannosaurus rex. Our new reconstruction relies primarily on direct examination of both extant and fossil turtles, lepidosaurs, and archosaurs. These observations are placed into a phylogenetic context and data from extant taxa are used to constrain inferences concerning the soft‐tissue structures in T. rex. Using this extant phylogenetic bracket, we are able to offer well‐supported inferences concerning most of the hindlimb musculature in this taxon. We also refrain from making any inferences for certain muscles where the resulting optimizations are ambiguous. This reconstruction differs from several previous attempts and we evaluate these discrepancies. In addition to providing a new and more detailed understanding of the hindlimb morphology of T. rex—the largest known terrestrial biped—this reconstruction also helps to clarify the sequence of character‐state change along the line to extant birds. J. Morphol. 253:207–228, 2002. © 2002 Wiley‐Liss, Inc.
In the absence of rauber's sickle material, no blood islands are formed in the avian blastoderm
Authors: Callebaut Marc , Van Nueten Emmy , Bortier Hilde , Harrisson Fernand 
Published: October 2002

AbstractUsing the quail‐chick chimera technique, we followed the fate of Rauber's sickle cells in older whole blastoderms (cultured for approximately 2 days): after removal of the autochthonous Rauber's sickle from an unincubated chicken blastoderm, a quail Rauber's sickle was grafted isotopically and isochronically in its place. In transverse sections through these chimeras, the grafted quail Rauber's sickle cells were seen to have transformed into a broad row or ridge of quail junctional endoblast cells extending at the inner border of the area containing blood islands. After unilateral removal of the junctional endoblast from an intermediate streak chicken blastoderm (Stage 3; Hamburger and Hamilton [1951] J Morphol 88:49–92), we observed during further in vitro culture that at the operated side, in the area previously occupied by this junctional endoblast, blood islands no longer developed. If after such a unilateral removal of the chicken junctional endoblast quail junctional endoblast was apposed in its place, then blood islands reappeared in the operated area. The intimate contact between the apposed quail junctional endoblast and the recently formed blood islands, derived from peripherally migrating mesoderm, was very obvious on sections through such chimeras. We further demonstrate that Rauber's sickle vs. junctional endoblast is indispensable for the anlage of blood islands in avian blastoderms. Indeed, in the absence of Rauber's sickle material no blood islands develop (even when mesoderm is present after ingression of the upper layer via a primitive streak) in the isolated central region of the area centralis of unincubated chicken blastoderms after culture in vitro. Also, no junctional endoblast and no sickle canal appear in these explants. By contrast, if a Rauber's sickle fragment is placed on such an isolated central blastoderm region, then blood islands develop. These blood islands start to develop from peripherally migrating mesoderm in the neighborhood of the Rauber's sickle‐derived junctional endoblast. J. Morphol. 253:132–147, 2002. © 2002 Wiley‐Liss, Inc.
Gill‐derived glands in glandulocaudine fishes (teleostei: Characidae: Glandulocaudinae)
Authors: Bushmann Paul J. , Burns John R. , Weitzman Stanley H. 
Published: October 2002

AbstractThe Glandulocaudinae is a subfamily of neotropical characid fishes from Central and South America. A unifying feature of the subfamily is the caudal gland, found almost exclusively in males. The gland consists of tissue on the base of the caudal fin covered in part by hypertrophied scales. Scale movement as the caudal fin is flexed appears to facilitate the release of chemical compounds from the glandular tissue. We describe here a different structure, found in the gill cavity of mature males in 12 of 17 glandulocaudine genera examined. Termed a gill gland, it develops as a male secondary sex character and appears morphologically suited to release chemical signals. The gland forms by the growth of tissue over and around 4–13 anterior gill filaments on the first gill arch, forming chambers with ventral openings. Within the gland chambers, gill secondary lamellae usually shorten and may disappear. When secondary lamellae persist, simple columnar epithelial cells develop between them. In the absence of secondary lamellae, the gland chambers are lined with a simple cuboidal or columnar epithelium. Gland size and the degree of gill modification vary among species. Gill glands appear absent in five glandulocaudine genera, suggesting character reversals based on current phylogenetic hypotheses and systematic classification. Gill gland morphology suggests that this structure releases chemical compounds into the gill current. The presence of gill glands only in mature males suggests a function in reproduction and/or male aggression. Together with studies of the caudal gland, this research suggests that chemical signals may play important roles in glandulocaudine reproduction. J. Morphol. 253:187–195, 2002. © 2002 Wiley‐Liss, Inc.
Comparative structural connectivity spectra analysis (CoSCoSA) models of steroids binding to the aromatase enzyme
Authors: Beger Richard D. , Wilkes Jon G. 
Published: October 2002

AbstractA method that combines NMR spectral and structural information into a constructed three‐dimensional (3D)‐connectivity matrix is developed for modeling biological binding activity of small molecules. The 3D‐connectivity matrix for a molecule is defined by associating the distances between all possible carbon‐to‐carbon connections with their assigned carbon NMR chemical shifts. In this project we selected from the total 3D‐connectivity matrix a subset, the two‐dimensional (2D) 13C‐13C COSY and a theoretical long range 2D 13C‐13C distance connectivity spectral plane. Patterns of 13C chemical shifts observed at these two relative distances for 50 steroids were used to produce a mathematical relationship for the steroids' relative binding affinity (pKi) to the aromatase enzyme. We call this technique comparative structural connectivity spectra analysis (CoSCoSA) modeling. Using combinations of the 2D COSY and 2D long‐range distance spectra as modeling parameters, we built four CoSCoSA models. One model was made from the 2D COSY spectra alone and another was developed using only the 2D long‐range distance spectra. Then the COSY and long‐distance spectra were combined in two different ways: starting with the combined principal components (PCs) from the separately calculated COSY and distance spectra or using the combined raw spectra (3D). The best CoSCoSA model was based on the combined PCs from COSY and distance spectra. This model had an r2 of 0.96 and a leave‐one‐out cross‐validation (q2) of 0.92. In general CoSCoSA modeling combines the quantum mechanical information inherent in NMR chemical shifts with internal molecular atom‐to‐atom distances to give a reliable and straightforward basis for predictive modeling. The technique has the flexibility and accuracy to outperform not only the cross‐validated variance q2 of previously published quantitative structure–activity relationships (QSAR) but also those obtained by related quantitative spectral data–activity relationships (QSDARs) lacking connectivity dimensions. Copyright © 2002 John Wiley & Sons, Ltd.
Comparison of first‐pass Gd‐DOTA and FAIRER MR perfusion imaging in a rabbit model of pulmonary embolism
Authors: Keilholz Shella D. , Mai Vu M. , Berr Stuart S. , Fujiwara Naomi , Hagspiel Klaus D. 
Published: October 2002

AbstractPurposeTo compare the sensitivity of contrast‐enhanced magnetic resonance imaging (MRI) and arterial spin labeling to perfusion deficits in the lung.Materials and MethodsA rabbit model of pulmonary embolism was imaged with both flow‐sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER) arterial spin labeling and Gd‐DOTA enhanced MRI. The signal‐to‐noise ratio (SNR) was measured in the area of the perfusion deficit and the normal lung for both techniques.ResultsThe defect was readily visible in all images. The normal lung had an average of 3.8 ± 1.2 times the SNR of the unperfused lung with the arterial spin labeling technique, and approximately 13.7 ± 3.3 times the SNR with the contrast‐enhanced technique.ConclusionGd‐DOTA enhanced MRI provides higher SNR in pulmonary perfusion imaging; however, arterial spin labeling is also adequate and may be used when repeated studies are indicated. J. Magn. Reson. Imaging 2002;16:168–171. © 2002 Wiley‐Liss, Inc.
Epstein‐Barr virus and human immunodeficiency virus serological responses and viral burdens in HIV‐infected patients treated with HAART
Authors: O'Sullivan Cathal E. , Peng RongSheng , Cole Kelly Stefano , Montelaro Ronald C. , Sturgeon Timothy , Jenson Hal B. , Ling Paul D. 
Published: October 2002

AbstractEpstein‐Barr virus (EBV) associated non‐Hodgkin lymphoma is recognized as a complication of human immunodeficiency virus (HIV) infection. Little is known regarding the influence of highly active antiretroviral therapy (HAART) on the biology of EBV in this population. To characterize the EBV‐ and HIV‐specific serological responses together with EBV DNA levels in a cohort of HIV‐infected adults treated with HAART, a study was conducted to compare EBV and HIV serologies and EBV DNA copy number (DNAemia) over a 12‐month period after the commencement of HAART. All patients were seropositive for EBV at baseline. Approximately 50% of patients had detectable EBV DNA at baseline, and 27/30 had detectable EBV DNA at some point over the follow‐up period of 1 year. Changes in EBV DNA copy number over time for any individual were unpredictable. Significant increases in the levels of Epstein‐Barr nuclear antigen (EBNA) and Epstein‐Barr early antigen (EA) antibodies were demonstrated in the 17 patients who had a good response to HAART. Of 29 patients with paired samples tested, four‐fold or greater increases in titers were detected for EA in 12/29 (41%), for EBNA in 7/29 (24%), for VCA‐IgG in 4/29 (14%); four‐fold decreases in titers were detected in 2/29 (7%) for EA and 12/29 (41%) for EBNA. A significant decline in the titer of anti‐HIV antibodies was also demonstrated. It was concluded that patients with advanced HIV infection who respond to HAART have an increase in their EBV specific antibodies and a decrease in their HIV‐specific antibodies. For the cohort overall, there was a transient increase in EBV DNA levels that had declined by 12 months. J. Med Virol. 67:320–326, 2002. © 2002 Wiley‐Liss, Inc.
Direct evidence for GB virus C/hepatitis G virus (GBV‐C/HGV) superinfection: Elimination of resident viral strain by donor strain in a patient undergoing liver transplantation
Authors: Fan Xiaofeng , Xu Yanjuan , Detre Katherine , Di Bisceglie Adrian M. 
Published: October 2002

AbstractThe viral genome of GB virus C/hepatitis G virus (GBV‐C/HGV), a single‐strand RNA virus, is subject to considerable variability and at least four genotypes have been suggested based on phylogenetic analysis. While co‐infection of GBV‐C/HGV with other infectious agents such as hepatitis C virus (HCV) has been frequently observed, there is no report whether or not co‐infection and/or superinfection occurs among different GBV‐C/HGV strains. By studying a GBV‐C/HGV positive recipient/donor pair in the context of undergoing liver transplantation, we have sequenced multiple clones derived from serum samples serially collected over four years. Detailed phylogenetic analyses have been performed with these sequences. The donor was infected with GBV‐C/HGV genotype 1 and this strain completely replaced recipient GBV‐C/HGV strain (genotype 2) after liver transplantation. The recipient's original viral strain became undetectable during follow‐up. Sequence analysis failed to identify genetic recombination between the two genotypes, at least in whole structural domain. This study, therefore, provides direct evidence for GBV‐C/HGV superinfection of one strain by another with one of them predominating probably due to replication competition. J. Med. Virol. 68:76–81, 2002. © 2002 Wiley‐Liss, Inc.
Sequence analysis of pre‐S/surface and pre‐core/core promoter genes of hepatitis B virus in chronic hepatitis C patients with occult HBV infection
Authors: Kao Jia‐Horng , Chen Pei‐Jer , Lai Ming‐Yang , Chen Ding‐Shinn 
Published: October 2002

AbstractAlthough occult hepatitis B virus (HBV) infection in individuals without detectable hepatitis B surface antigen (HBsAg) may occur and has been reported to be common in patients with chronic hepatitis C, the related molecular mechanisms remain unknown. With the polymerase chain reaction, serum HBV DNA was sought in 100 HBsAg‐negative patients with chronic hepatitis C virus (HCV)‐infection. In those with occult HBV infection, possible genomic variability of HBV was evaluated by amplification and direct sequencing of pre‐S, surface, and pre‐core/core promoter genes. In total, 10 of the 100 patients (10%) had detectable serum HBV DNA, documenting an occult HBV infection. A deletion mutant in the pre‐S gene was found in one patient and mutations of the a determinant of HBsAg were observed in 2. In addition, a novel core promoter mutant (a dinucleotide substitution: T‐to‐C at nucleotide 1,802 and T‐to‐G at nucleotide 1,803, T1802C/T1803G) was found frequently in patients with occult HBV infection as compared to sex‐ and age‐matched HBsAg‐positive patients (80 vs. 10%, P < 0.001). In conclusion, the data suggest occult HBV infection is not uncommon in chronic hepatitis C patients in Taiwan, and a novel core promoter mutant may be associated with the absence of circulating HBsAg in these patients. J. Med. Virol. 68:216–220, 2002. © 2002 Wiley‐Liss, Inc.
A note on the thermal modelling of power semiconductor devices using the network analogue
Authors: Chung Wong Chi 
Published: October 2002

AbstractThe aim of this note is to point out that the boundary condition for the network modelling of thermal problems may have been incorrectly used in some previous studies. It is shown that the accuracy of the network analogue or the equivalent finite‐difference method is on the par with the finite‐element method for very fast transient thermal simulations. Copyright © 2002 John Wiley & Sons, Ltd.
Molecular mechanisms of enhanced susceptibility to apoptosis in differentiating oligodendrocytes
Authors: Osterhout D.J. , Marin‐Husstege M. , Abano P. , Casaccia‐Bonnefil P. 
Published: October 2002

AbstractSeveral studies have shown that the progression of oligodendrocyte progenitors along the lineage correlates with increased susceptibility to death stimuli. The molecular basis of this phenomenon remains unclear. This study demonstrates that the protein levels of several proapoptotic molecules, including Bax, Bad (nonphosphorylated form), and certain caspase proforms, increase during oligodendrocyte development. In contrast, the steady‐state levels of antiapoptotic molecules, such as Bcl2 and BclXL, remain constant. This altered equilibrium between proapoptotic and antiapoptotic molecules correlates with increased cytochrome C in the cytosol. We conclude that, as oligodendrocytes mature, their susceptibility to apoptosis increases because of a change in the balance between protective mechanisms and proapoptotic pathways. This suggests the possible existence of a death susceptibility program, which is intrinsic to differentiating oligodendrocyte progenitors. © 2002 Wiley‐Liss, Inc.
Fractalkine and fractalkine receptors in human neurons and glial cells
Authors: Hatori Kozo , Nagai Atsushi , Heisel Rochelle , Ryu Jae K. , Kim Seung U. 
Published: October 2002

AbstractFractalkine has been identified as a novel chemokine that exhibits cell adhesion and chemoattractive properties in the central nervous system (CNS), and the fractalkine receptors, CX3CR1, are also expressed in the CNS. In the present study, the expression of fractalkine and fractalkine receptors was investigated in enriched populations of human CNS neurons, astrocytes, and microglia. In addition, the regulatory role played by protein kinase C (PKC) in fractalkine secretion in neurons was determined in A1 human hybrid neuronal cell line produced between a human cerebral neuron and a human neuroblastoma cell. Human neurons and astrocytes expressed fractalkine mRNA as determined by the revserse transcriptase‐polymerase chain reaction (RT‐PCR) analysis, while human microglia preparation did not express the fractalkine message. Human neurons and microglia expressed CX3CR1 mRNA, but astrocytes did not. These results suggest that fractalkine secreted by CNS neurons and astrocytes produce biological effects in neurons and microglia. Although phorbol ester did not change the expression of fractalkine mRNA level in A1 hybrid neurons, it did upregulate fractalkine secretion over unstimulated controls. This upregulation of fractalkine production was suppressed by the treatment with Ro32‐0432, a PKC inhibitor. These results indicate that intracellular signals transduced by PKC play an important role in the regulation of soluble fractalkine at the post‐transcriptional level in human neurons. As for the biological function of fractalkine, extracellularly applied fractalkine increased the number of bromodeoxyuridine‐labeled microglia 3‐fold over the untreated controls, indicating fractalkine induces proliferation of human microglia. These observations suggest that fractalkine released by injured neurons could induce proliferation, activation and/or migration of microglia at the injured brain sites. © 2002 Wiley‐Liss, Inc.
Cerebral postischemic reperfusion‐induced demethylation of the protein phosphatase 2A catalytic subunit
Authors: Martín de la Vega Cristina , Burda Jozef , Toledo Lobo M.V. , Salinas Matilde 
Published: October 2002

AbstractBrain reperfusion after a period of global ischemia induces changes in the phosphorylation state of a great number of proteins. Neuronal responses to ischemia and reperfusion are quite different depending on the brain region, and phosphorylation changes may be implicated in this tissue‐specific response. For this reason, we have used both biochemical and immunohistochemical methods to investigate the potential role of PP2A, the most abundant Ser/Thr phosphatase in the brain, in ischemic injury. PP2A activity as measured with phosphorylase a as substrate was slightly inhibited after 30 min ischemia followed by 30 min reperfusion, and this inhibition correlated with an increased S6K1 and ERK1/2 phosphorylation. Using a monoclonal antibody unable to recognize the methylated form of PP2Ac, we demonstrated that the catalytic subunit of PP2A (PP2Ac) was highly methylated in the brain. In addition, the postischemic reperfusion‐induced changes in PP2Ac methylation were studied in sections from cerebral cortex, hippocampus and striatum. Regional differences in PP2Ac methylation were observed within control brains, and the postischemic reperfusion caused a generalized demethylation of PP2Ac. Those regions in the control brains containing highest levels of methylated PP2Ac were the most intensively demethylated after reperfusion and corresponded to the regions most vulnerable to ischemic damage. © 2002 Wiley‐Liss, Inc.