bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of the process formation; podocytes vs. neurons
Authors: Kobayashi Naoto 
Published: August 2002

AbstractIn this review article we discuss the common mechanism for cellular process formation. Besides the podocyte, the mechanism of process formation, including cytoskeletal organization and signal transduction, etc., has been studied using neurons and glias as model systems. There has been an accumulation of data showing common cell biological features of the podocyte and the neuron: 1) Both cells possess long and short cell processes equipped with highly organized cytoskeletal systems; 2) Both show cytoskeletal segregation; microtubules (MTs) and intermediate filaments (IFs) in podocyte primary processes and in neurites, while actin filaments (AFs) are abundant in podocyte foot processes in neuronal synaptic regions; 3) In both cells, process formation is mechanically dependent on MTs, whose assembly is regulated by various microtubule‐ associated proteins (MAPs); 4) In both cells, process formation is positively regulated by PP2A, a Ser/Thr protein phosphatase; 5) In both cells, process formation is accelerated by laminin, an extracellular matrix protein. In addition, recent data from our and other laboratories have shown that podocyte processes share many features with neuronal dendrites: 1) Podocyte processes and neuronal dendrites possess MTs with mixed polarity, namely, plus‐end‐distal and minus‐end‐distal MTs coexist in these processes; 2) To establish the mixed polarity of MTs, both express CHO1/MKLP1, a kinesin‐related motor protein, and when its expression is inhibited formation of both podocyte processes and neuronal dendrites is abolished; 3) The elongation of both podocyte processes and neuronal dendrites is supported by rab8‐regulated basolateral‐type membrane transport; 4) Both podocyte processes and neuronal dendrites express synaptopodin, an actin‐associated protein, in a development‐dependent manner; interestingly, in both cells, synaptopodin is localized not in the main shaft of processes but in thin short projections from the main shaft. We propose that the podocyte process and the neuronal dendrite share many features, while the neuronal axon should be thought of as an exceptionally differentiated cellular process. Microsc. Res. Tech. 57:217–223, 2002. © 2002 Wiley‐Liss, Inc.
Role of monocyte chemoattractant protein‐1 in Propionibacterium acnes–induced pulmonary granulomatosis
Authors: Ichiyasu Hidenori , Suga Moritaka , Iyonaga Kazuhiro , Ando Masayuki 
Published: August 2002

AbstractThe inflammatory process in granulomatous disorders such as sarcoidosis is mainly the consequence of delayed hypersensitivity induced by causative antigens. Propionibacterial DNA was isolated recently by PCR from human sarcoidosis tissue. Hence, we developed a model using sensitized rabbits for T cell–mediated pulmonary granulomatosis induced by Propionibacterium acnes (P. acnes) and investigated the role of monocyte chemoattractant protein‐1 (MCP‐1) in the pathogenesis of the granuloma formation in vivo. Intravenous injection of P. acnes into sensitized rabbits induced massive pulmonary granulomas on day 3. Maximum levels of MCP‐1 in sera and bronchoalveolar lavage fluid (BALF) were detected on day 1 and preceded recruitment of monocyte/macrophages and T cells. In BALF, monocyte chemotaxis peaked 1 day after P. acnes challenge, and T cell chemotaxis peaked 3 days after P. acnes challenge. Anti‐MCP‐1 IgG inhibited monocyte chemotaxis by 80.2% and T cell chemotaxis by 35.7%. Phenotypic analysis of migrating T cells revealed that activated and memory T cells (CD26+/CD45RO+) but not naive cells were preferentially attracted to BALF. Administration of MCP‐1 antiserum in vivo inhibited the development of granulomas in both size 59.9% reduction and number 28.6% reduction, the number of infiltrating leukocytes in BALF, and the expression of adhesion molecules on leukocytes in peripheral blood and BALF. Our data indicate that MCP‐1 plays important roles in granuloma formation by attracting and activating specific types of cells in this model. Furthermore, results suggest that the rabbit model resembles human angiocentric granulomatosis and would be useful for investigating the immunopathogenesis of human pulmonary granulomatosis. Microsc. Res. Tech. 53:288–297, 2001. © 2001 Wiley‐Liss, Inc.
The reptilian oviduct: a review of structure and function and directions for future research
Authors: Girling Jane E. 
Published: August 2002

AbstractThe reptilian oviduct is a complex organ with a variety of functions (albumen production, eggshell production, placentation, oviposition or parturition, and sperm storage), depending on the parity mode of the species in question. These functions are under complex physiological control, the details of which are far from understood. The aims of this review are to summarise the information available concerning the structure and functions of the reptilian oviduct and to highlight areas in particular need of further research. © 2002 Wiley‐Liss, Inc.
Does one gene determine whether a C57BL/6J‐YPOS mouse will develop as a female or as an hermaphrodite?
Authors: Eicher Eva M. , Washburn Linda L. 
Published: August 2002

AbstractTwo studies were conducted to further our understanding of the inherited condition in mice known as C57BL/6J‐YPOS (B6‐YPOS) sex reversal. One study determined what proportion of B6 XYPOS mice develop as females or hermaphrodites. We found that 75% develop as females and the remainder develop as hermaphrodites regardless of whether the analysis is conducted at 14.5–16 days of embryonic development (based on gonad phenotype) or at weaning (based on the appearance of external genitalia and presence of mammary‐associated yellow pigmented hair). We also found that 75 % of the gonads in B6 XYPOS mice develop as ovaries and the remainder develop as ovotestes; none develop as a testis. We conclude that if any testicular tissue develops, sufficient testosterone is produced to cause at least some masculinization of the external genitalia. The second study tested the hypothesis that development of testicular tissue in B6 XYPOS mice is due to the presence of a POS‐derived gene, whereas B6 homozygosity of this gene guarantees ovarian development. The results did not support the POS gene theory. Therefore, we conclude it is a matter of chance that 75 % of B6 XYPOS mice develop as females and 25 % develop as hermaphrodites. J. Exp. Zool. 290:322–326, 2001. © 2001 Wiley‐Liss, Inc.
Surface glycoproteins bearing α‐GalNAc terminated chains accompany pyriform cell differentiation in lizards
Authors: Uliano Roberto , Ricchiari Loredana , Prisco Marina , Andreuccetti Piero 
Published: August 2002

AbstractThe present investigation demonstrates that in squamate reptiles, as already reported for Podarcis sicula (Andreuccetti et al., 2001), the differentiation of pyriform cells from small, stem follicle cells is characterized by the progressive appearance on the cell surface of glycoproteins bearing α‐GalNAc terminated O‐linked side chains. Using a lectin panel (WGA, GSI‐A4, GSI‐B4, PSA UEA‐I, PNA, Con‐A, DBA, LCA, BPA, SBA), we demonstrated that, during previtellogenesis, the pattern of distribution of DBA binding sites over the follicular epithelium dramatically changes. In fact, binding sites first appear in follicular epithelium at the time that small cells begin to differentiate; in such follicles, labeling is evident on the cell surfaces of small and intermediate cells. Later on, as the differentiation progresses, the binding sites also become evident on the cell surface of pyriform cells. Once differentiated, the pattern of the distribution of DBA binding sites over the follicular epithelium does not change. By contrast, during the phase of intermediate and pyriform cell regression, DBA binding sites gradually decrease, so that the monolayered follicular epithelium of vitellogenic follicles, constituted only by small cells, shows no binding sites for DBA. It is noteworthy that binding sites for DBA are present on small cells located in contact with the oocyte membrane, but not on those located under the basal lamina or among pyriform cells, and therefore not engaged in the differentiation into pyriform cells. This finding demonstrates that, in squamates, the pattern of distribution of α‐N‐GalNAc containing glycoproteins significantly changes during previtellogenesis, and that these modifications are probably related to the differentiation of small stem cells into highly specialized pyriforms. J. Exp. Zool. 290:769–776, 2001. © 2001 Wiley‐Liss, Inc.
Role for corticoids in mediating the response of Rana pipiens tadpoles to intraspecific competition
Authors: Glennemeier Karen Ann , Denver Robert John 
Published: August 2002

AbstractCompetition is known to decrease growth and development rate in tadpoles, but the physiological basis for this phenomenon is poorly understood. We hypothesized that competition results in increased production of stress hormones and that these hormones are responsible for the suppression of growth and development. To test this hypothesis, we measured whole‐body corticosterone content in premetamorphic Leopard frog (Rana pipiens) tadpoles raised at two different population densities and three different food levels. Whole body corticosterone content was elevated in tadpoles subjected to either limited food (at low density) or high density. Within the low and intermediate food treatments, high density reduced tadpole growth and slowed development. Limited food slowed growth and development at all densities. Blocking corticoid synthesis by treating tadpoles with metyrapone (MTP) reversed the growth suppression caused by high density (tested in the intermediate food level treatment) but did not alter the effect of density on development rate. MTP treatment did not alter the depressive effect of limited resources on growth or development. Our results suggest that elevated corticoid biosynthesis mediates the negative effect of increased population density (i.e., increased intraspecific competition) on tadpole growth. J. Exp. Zool. 292:32–40, 2002. © 2002 Wiley‐Liss, Inc.
Intratumoral activation of cyclophosphamide by retroviral transfer of the cytochrome P450 2B1 in a pancreatic tumor model. Combination with the HSVtk/GCV system
Authors: Carrió Meritxell , Visa Joana , Cascante Anna , Estivill Xavier , Fillat Cristina 
Published: August 2002

AbstractBackgroundPancreatic cancer is one of the most aggressive human tumors and the development of new therapeutic approaches is particularly urgent since current therapies are not effective. The use of pro‐drug‐activating genes is a possible approach for cancer gene therapy.MethodsThe present study evaluated the efficiency of the cytochrome P4502B1 (CYP2B1) suicide gene that encodes the enzyme responsible for activating the pro‐drug cyclophosphamide (CPA), in pancreatic tumor cells invitro and in vivo. The effects on tumor growth of the combination of two suicide systems, CYP2B1/CPA and herpes simplex virus thymidine kinase gene/ganciclovir (HSVtk/GCV), were also studied.ResultsRetroviral CYP2B1 transfer followed by CPA treatment highly sensitized pancreatic tumor cells NP‐9, NP‐18, and NP‐31, and led to stabilization of tumor growth in a pancreatic tumor model. Differences in tumor volume at the end of the treatment were statistically significant when compared with animals injected with CPA alone. The combination of both suicide systems CYP2B1/CPA and HSVtk/GCV in vitro resulted in a potentiation of the killing effect. However, no potentiation was achieved in vivo, although retardation in tumor growth was evident.ConclusionsThe results show that in situ transduction of pancreatic tumor cells with the CYP2B1 gene by retroviral vectors clearly increases the sensitivity to CPA. Moreover, they suggest that in order to achieve a potentiation on cell killing when the two suicide systems HSVtk/GCV and CYP2B1/CPA are combined, co‐expression of both genes in the same tumor cell would be necessary. Copyright © 2002 John Wiley & Sons, Ltd.
A Ramsey‐type problem and the Turán numbers*
Authors: Alon N. , Erdős P. , Gunderson D. S. , Molloy M. 
Published: August 2002

AbstractFor each n and k, we examine bounds on the largest number m so that for any k‐coloring of the edges of Kn there exists a copy of Km whose edges receive at most k−1 colors. We show that for $k \ge \sqrt{n}\;+\,\Omega(n^{1/3})$, the largest value of m is asymptotically equal to the Turá number $t(n,\lfloor {n\choose 2}/k\rfloor)$, while for any constant $\epsilon > 0,\; {\rm if}\; k \le (1-\epsilon) \sqrt{n}$ then the largest m is asymptotically larger than that Turá number. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 120–129, 2002
Learning from history: Morphology's challenges in Germany ca. 1900
Authors: Nyhart Lynn K. 
Published: August 2002

AbstractA century ago, Carl Gegenbaur's program of vertebrate evolutionary morphology faced its greatest challenges. The controversy over the evolutionary origin of the vertebrate paired limbs between 1875 and 1906 illustrates the failure of the traditional methods of comparative anatomy and embryology (supported by Haeckel's biogenetic law) to choose between different phylogenetic hypotheses. The controversy over morphology's status as science intensified at the turn of the twentieth century, when the legitimacy of historical explanation itself as a mode of scientific understanding came under fire. Gegenbaur's intellectual grandson, Hermann Braus, sought to defend the legitimacy of phylogenetic reconstruction while updating it to include experimental and causal‐analytical approaches, but was unable to sustain a viable synthetic research program. The article concludes with reflections on approaches to the past used by historians and evolutionary morphologists. J. Morphol. 252:2–14, 2002. © 2002 Wiley‐Liss, Inc.
Fine structure and development of the retina of the grenadier anchovy Coilia nasus (Engraulididae, Clupeiformes)
Authors: Haacke Christoph , Heß Martin , Melzer Roland R. , Gebhart Hedwig , Smola Ulrich 
Published: August 2002

AbstractA study of the morphogenesis of the grenadier anchovy retina was undertaken using light and electron microscopy. Five developmental stages from prelarvae 3 days after fertilization to adult fish were studied. In addition to the general morphology of the eye and retina, special emphasis was given to the development of the photoreceptors and pigment epithelium (PE). The earliest retinae showing structural features indicative of a functioning eye are pure cone retinae composed of rows of alternating long and short cones forming a transient, tesselated pattern. At this stage there is a conventional PE containing melanin. In older stages cone rows are separated by the newly formed rods and by PE wedges filled with diffusely reflecting guanine crystallites. The findings are compared with the retinae of other engraulidids and with the development of teleost retinae in general. Moreover, the observed structural changes are discussed with respect to the photic habitat conditions of these anadromous fish that move between coastal waters, estuary, and river. J. Morphol. 248:41–55, 2001. © 2001 Wiley‐Liss, Inc.
Keratinization and lipogenesis in epidermal derivatives of the zebrafinch, taeniopygia guttata castanotis (aves, passeriformes, ploecidae) during embryonic development
Authors: Alibardi Lorenzo 
Published: August 2002

AbstractLittle is known of the lipid content of β‐keratin‐producing cells such as those of feathers, scutate scales, and beak. The sequence of epidermal layers in some apteria and in interfollicular epidermis in the zebrafinch embryo (Taeniopygia guttata castanotis) was studied. Also, the production of β‐keratin in natal down feathers and beak was ultrastructurally analyzed in embryos from 3–4 to 17–18 days postdeposition, before hatching. Two layers of periderm initially cover the embryo, but there are eventually 6–8 over the epidermis of the beak. In the beak and sheath cells of feathers, peridermal granules are numerous at 12–14 days postdeposition but they are less frequent in apteria. These granules swell and disappear during sheath or peridermal degeneration at 15–17 days postdeposition. A thin β‐keratin layer forms under the periderm among feather germs of pterylous areas but is discontinuous or disappears in apteria. In differentiating cells of barbs, barbules, and calamus cells of natal down, electron‐dense β‐keratin filaments form bundles oriented along the main axis of these cells. Cells of the pulp epidermis and collar, at the base of the follicle, contain lipids and bundles of α‐keratin filaments. Degenerating pulp cells show vacuolization and nuclear pycnosis. During β‐keratin packing, keratin bundles turn electron‐pale, perhaps due to the addition of lipids to produce the final, homogenous β‐keratin matrix. In contrast to the situation in feathers, in the cells of beak β‐keratin packets are irregularly oriented. In both feather and beak epidermal cells the Golgi apparatus and smooth endoplasmic reticulum produce vesicles containing lipid‐like material which is also found among forming β‐keratin. The contribution of lipids or lipoprotein to the initial aggregation of β‐keratin molecules is discussed. J. Morphol. 251:294–308, 2002. © 2002 Wiley‐Liss, Inc.
History and function of scale microornamentation in lacertid lizards
Authors: Arnold E.N. 
Published: August 2002

AbstractDifferences in surface structure (ober‐ hautchen) of body scales of lacertid lizards involve cell size, shape and surface profile, presence or absence of fine pitting, form of cell margins, and the occurrence of longitudinal ridges and pustular projections. Phylogenetic information indicates that the primitive pattern involved narrow strap‐shaped cells, with low posteriorly overlapping edges and relatively smooth surfaces. Deviations from this condition produce a more sculptured surface and have developed many times, although subsequent overt reversals are uncommon. Like variations in scale shape, different patterns of dorsal body microornamentation appear to confer different and conflicting performance advantages. The primitive pattern may reduce friction during locomotion and also enhances dirt shedding, especially in ground‐dwelling forms from moist habitats. However, this smooth microornamentation generates shine that may compromise cryptic coloration, especially when scales are large. Many derived features show correlation with such large scales and appear to suppress shine. They occur most frequently in forms from dry habitats or forms that climb in vegetation away from the ground, situations where dirt adhesion is less of a problem. Microornamentation differences involving other parts of the body and other squamate groups tend to corroborate this functional interpretation. Microornamentation features can develop on lineages in different orders and appear to act additively in reducing shine. In some cases different combinations may be optimal solutions in particular environments, but lineage effects, such as limited reversibility and different developmental proclivities, may also be important in their genesis. The fine pits often found on cell surfaces are unconnected with shine reduction, as they are smaller than the wavelengths of most visible light. J. Morphol. 252:145–169, 2002. © 2002 Wiley‐Liss, Inc.
Statistical analysis of atomic contacts at RNA–protein interfaces
Authors: Treger Michèle , Westhof Eric 
Published: August 2002

AbstractForty‐five crystals of complexes between proteins and RNA molecules from the Protein Data Bank have been statistically surveyed for the number of contacts between RNA components (phosphate, ribose and the four bases) and amino acid side chains. Three groups of complexes were defined: the tRNA synthetases; the ribosomal complexes; and a third group containing a variety of complexes. The types of atomic contacts were a priori classified into ionic, neutral H‐bond, C‐H…O H‐bond, or van der Waals interaction. All the contacts were organized into a relational database which allows for statistical analysis. The main conclusions are the following: (i) in all three groups of complexes, the most preferred amino acids (Arg, Asn, Ser, Lys) and the less preferred ones (Ala, Ile, Leu, Val) are the same; Trp and Cys are rarely observed (respectively 15 and 5 amino acids in the ensemble of interfaces); (ii) of the total number of amino acids located at the interfaces 22% are hydrophobic, 40% charged (positive 32%, negative 8%), 30% polar and 8% are Gly; (iii) in ribosomal complexes, phosphate is preferred over ribose, which is preferred over the bases, but there is no significant preference in the other two groups; (iv) there is no significant prevalence of a base type at protein–RNA interfaces, but specifically Arg and Lys display a preference for phosphate over ribose and bases; Pro and Asn prefer bases over ribose and phosphate; Met, Phe and Tyr prefer ribose over phosphate and bases. Further, Ile, Pro, Ser prefer A over the others; Leu prefers C; Asp and Gly prefer G; and Asn prefers U. Considering the contact types, the following conclusions could be drawn: (i) 23% of the contacts are via potential H‐bonds (including CH…O H‐bonds and ionic interactions), 72% belong to van der Waals interactions and 5% are considered as short contacts; (ii) of all potential H‐bonds, 54% are standard, 33% are of the C‐H…O type and 13% are ionic; (iii) the Watson–Crick sites of G, O6(G) and principally N2(G) and the hydroxyl group O2′ is more often involved in H‐bonds than expected; the protein main chain is involved in 32% and the side chains in 68% of the H‐bonds; considering the neutral and ionic H‐bonds, the following couples are more frequent than expected—base A–Ser, base G–Asp/Glu, base U–Asn. The RNA CH groups interact preferentially with oxygen atoms (62% on the main chain and 19% on the side chains); (iv) the bases are involved in 38% of all H‐bonds and more than 26% of the H‐bonds have the H donor group on the RNA; (v) the atom O2′ is involved in 21% of all H‐bonds, a number greater than expected; (vi) amino acids less frequently in direct contact with RNA components interact frequently via their main chain atoms through water molecules with RNA atoms; in contrast, those frequently observed in direct contact, except Ser, use instead their side chain atoms for water bridging interactions. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of a dedicated dual phased‐array surface coil using a black‐blood FSE sequence for high resolution MRI of the carotid vessel wall
Authors: Ouhlous Mohamed , Lethimonnier Franck , Dippel Diederik W.J. , van Sambeek Marc R.H.M. , van Heerebeek Lambertus C.J. , Pattynama Peter M.T. , van der Lugt Aad 
Published: August 2002

AbstractPurposeTo investigate the ability of magnetic resonance imaging (MRI) to visualize the carotid vessel wall using a phased‐array coil and a black‐blood (BB) fast spin‐echo (FSE) sequence.Materials and MethodsThe phased‐array coil was compared with a three‐inch coil. Images from volunteers were evaluated for artifacts, wall layers, and wall signal intensity. Signal intensity and homogeneity of atherosclerosis were assessed. Lumen diameter and vessel area were measured.ResultsComparison between the phased‐array coil and the three‐inch coil showed a 100% increase in signal‐to‐noise ratio. BB‐FSE imaging resulted in good delineation between blood and vessel wall. Most volunteers had a two‐layered vessel wall with a hyperintense inner layer. MRI showed both homogeneous hyperintense and heterogeneous plaques, which consisted of a main hyperintense part with hypointense spots and/or intermediate regions. MRI lumen and area measurements were performed easily.ConclusionHigh resolution MRI of carotid atherosclerosis is feasible with a phased‐array coil and a BB‐FSE sequence. J. Magn. Reson. Imaging 2002;15:344–351. © 2002 Wiley‐Liss, Inc.