bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilization of a receptor reserve for effective amplification of mitogenic signaling by an epidermal growth factor mutant deficient in receptor activation***
Authors: Nandagopal Krishnadas , Popp Diana M. , Niyogi Salil K. 
Published: August 2002

AbstractThe idea of a receptor reserve in mediating cellular function is well known but direct biochemical evidence has not been easy to obtain. This study stems from our results showing that L15 of epidermal growth factor (EGF) is important in both EGF receptor (EGFR) binding and activation, and the L15A analog of human EGF (hEGF) partially uncouples EGFR binding from EGFR activation (Nandagopal et al., [1996] Protein Engng 9:781‐788). We address the cellular mechanism of mitogenic signal amplification by EGFR tyrosine kinase in response to L15A hEGF. L15A is partially impaired in receptor dimerization, shown by chemical cross‐linking and allosteric activation of EGFR in a substrate phosphorylation assay. Immunoprecipitation experiments reveal, however, that L15A can induce EGFR autophosphorylation in intact murine keratinocytes by utilizing spare receptors, the ratio of total phosphotyrosine content per receptor being significantly lower than that elicited by wild‐type. This direct biochemical evidence, based on function, of utilization of a receptor reserve for kinase stimulation suggests that an EGF variant can activate varying receptor numbers to generate the same effective response. L15A‐activated receptors can stimulate mitogen‐activated protein kinase (MAPK) that is important for mitogenesis. The lack of linear correlation between levels of receptor dimerization, autophosphorylation, and MAPK activation suggests that signal amplification is mediated by cooperative effects. Flow cytometric analyses show that the percentages of cells which proliferate in response to 1 nM L15A and their rate of entry into S‐phase are both decreased relative to 1 nM wild‐type, indicating that MAPK activation alone is insufficient for maximal stimulation of mitogenesis. Higher concentrations of L15A reverse this effect, indicating that L15A and wild‐type differ in the number of receptors each activates to induce the threshold response, which may be attained by cooperative activation of receptor dimers/oligomers by van der Waal's weak forces of attraction. The maintenance of a receptor reserve underscores an effective strategy in cell survival. J. Cell. Biochem. 83: 326–341, 2001. © 2001 Wiley‐Liss, Inc.
Distribution of somatic H1 subtypes is non‐random on active vs. inactive chromatin II: Distribution in human adult fibroblasts
Authors: Parseghian Missag H. , Newcomb Robert L. , Hamkalo Barbara A. 
Published: August 2002

AbstractFor nearly twenty years researchers have observed changes in the histone H1 subtype content of tissues as an organism develops into an adult. To better understand the consequences of such changes, immunofractionation of chromatin using previously characterized antibodies specific for human H1 subtypes was employed in the analysis of a fibroblast cell strain derived from a 37‐year‐old individual. DNAs isolated from immunoprecipitates were probed for the existence of a variety of DNA sequences. The results presented lend further support to a previously‐proposed model (Parseghian et al. [2000] Chromosome Res 8:405‐424) in which transcription of a sequence is accompanied by the selective depletion of subtypes. The data also suggest that there is more total H1 on actively transcribed sequences in these cells as compared to fetal fibroblasts and that there is less difference in the subtype compositions of active genes vs. inactive sequences in this strain. Specifically, the consequences of these changes appear to correlate with the attenuation of the heat shock response in aging fibroblasts. In a broader context, these results could explain why there are reductions in transcription in cells from mature tissue that approach senescence. J. Cell. Biochem. 83: 643–659, 2001. © 2001 Wiley‐Liss, Inc.
Expression of AP‐2 transcription factor and of its downstream target genes c‐kit, E‐cadherin and p21 in human cutaneous melanoma
Authors: Baldi Alfonso , Santini Daniele , Battista Tullio , Dragonetti Emanuele , Ferranti Giulio , Petitti Tommasangelo , Groeger Angela M. , Angelini Anna , Rossiello Raffaele , Baldi Feliciano , Natali Pier Giorgio , Paggi Marco G. 
Published: August 2002

AbstractThe AP‐2 transcription factor plays a pivotal role in regulating the expression of several genes involved in tumor growth and progression of melanoma. We determined, by Western blot, variation in the level of expression of AP‐2 and three of its downstream targets, c‐kit, E‐cadherin, and p21 in several human melanoma cell lines and, by immunohistochemistry, in a group of 99 histological samples including benign and malignat melanocytic lesions. A significant negative correlation between AP‐2 expression level and tumor thickness was found. Moreover, AP‐2 expression was positively associated with E‐cadherin and c‐kit expression. In contrast, there was a significant negative association between AP‐2 and p21 expression levels. These findings suggest that p21 is independent of AP‐2 transactivator function during the latest phases of melanoma progression. Finally, AP‐2, c‐kit, E‐cadherin, and p21 expression levels did not show to be able to distinguish between dysplastic nevi and nevi without dysplasia. We conclude that changes in the expression of these proteins are involved in the later phases of melanoma progression, and may be responsible for the transition from local invasive melanoma to metastasis. J. Cell. Biochem. 83: 364–372, 2001. © 2001 Wiley‐Liss, Inc.
Polypeptide growth factors and phorbol ester induce progressive ankylosis (Ank) gene expression in murine and human fibroblasts*
Authors: Guo Yan , Hsu Debbie K.W. , Feng Sheau‐Line Y. , Richards Christine M. , Winkles Jeffrey A. 
Published: August 2002

AbstractPolypeptide growth factors promote cellular proliferation by binding to specific plasma membrane‐anchored receptors. This interaction triggers the phosphorylation of signal transducing molecules and the transcriptional activation of numerous genes. We have used a differential display approach to identify fibroblast growth factor (FGF)‐1‐inducible genes in murine NIH 3T3 fibroblasts. Here we report that one of these genes encodes ank, a type IIIa transmembrane protein reported to function in cells as an inorganic pyrophosphate transporter. FGF‐1 induction of ank mRNA expression is first detectable at 2 h after growth factor addition and is dependent on de novo RNA and protein synthesis. Ank gene expression is also upregulated after treating quiescent fibroblasts with several other mitogenic agents (e.g., calf serum or platelet‐derived growth factor‐BB) or the tumor promoter phorbol 12‐myristate 13‐acetate. Furthermore, in comparison to parental NIH 3T3 cells, oncogene‐transformed NIH 3T3 cells constitutively express elevated levels of ank mRNA. FGF‐1 also increases ank gene expression in non‐immortalized human embryonic lung fibroblasts. Finally, the murine and human ank genes are expressed in vivo in a tissue‐specific manner, with highest levels of mRNA expression found in brain, heart, and skeletal muscle. These results indicate that ank is a growth factor‐regulated delayed‐early response gene in mammalian cells, and we propose that increased ank expression during cell cycle progression may be necessary to maintain proper intracellular pyrophosphate levels during conditions of high cellular metabolic activity. J. Cell. Biochem. 84: 27–38, 2002. © 2001 Wiley‐Liss, Inc.
Atomic charges, dipole moments, and Fukui functions using the Hirshfeld partitioning of the electron density
Authors: De Proft F. , Van Alsenoy C. , Peeters A. , Langenaeker W. , Geerlings P. 
Published: August 2002

AbstractIn the Hirshfeld partitioning of the electron density, the molecular electron density is decomposed in atomic contributions, proportional to the weight of the isolated atom density in the promolecule density, constructed by superimposing the isolated atom electron densities placed on the positions the atoms have in the molecule. A maximal conservation of the information of the isolated atoms in the atoms‐in‐molecules is thereby secured. Atomic charges, atomic dipole moments, and Fukui functions resulting from the Hirshfeld partitioning of the electron density are computed for a large series of molecules. In a representative set of organic and hypervalent molecules, they are compared with other commonly used population analysis methods. The expected bond polarities are recovered, but the charges are much smaller compared to other methods. Condensed Fukui functions for a large number of molecules, undergoing an electrophilic or a nucleophilic attack, are computed and compared with the HOMO and LUMO densities, integrated over the Hirshfeld atoms in molecules. © 2002 Wiley Periodicals, Inc. J Comput Chem 12: 1198–1209, 2002
Cyclic bi‐embeddings of Steiner triple systems on 12s + 7 points
Authors: Bennett G. K. , Grannell M. J. , Griggs T. S. 
Published: August 2002

AbstractA cyclic face 2‐colourable triangulation of the complete graphKnin an orientable surface exists forn ≡ 7 (mod 12). Such a triangulation corresponds to a cyclic bi‐embedding of a pair of Steiner triple systems of ordern, the triples being defined by the faces in each of the two colour classes. We investigate in the general case the production of such bi‐embeddings from solutions to Heffter's first difference problem and appropriately labelled current graphs. Forn = 19 andn = 31 we give a complete explanation for those pairs of Steiner triple systems which do not admit a cyclic bi‐embedding and we show how all non‐isomorphic solutions may be identified. Forn = 43 we describe the structures of all possible current graphs and give a more detailed analysis in the case of the Heawood graph. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 92–110, 2002; DOI 10.1002/jcd.10001
1‐rotationally resolvable 4‐cycle systems of 2Kv
Authors: Fu Hung‐Lin , Mishima Miwako 
Published: August 2002

AbstractIn this article, it is shown that there exists a 1‐rotationally resolvable 4‐cycle system of 2Kυif and only if υ ≡ 0 (mod 4). To prove that, some special sequences of integers are utilized. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 116–125, 2002; DOI 10.1002/jcd.10006
Differential localization of ErbB2 in different tissues of the rat female reproductive tract: Implications for the use of specific antibodies for ErbB2 analysis
Authors: Idris Nebila , Carraway Coralie A. Carothers , Carraway Kermit L. 
Published: August 2002

AbstractErbB2 has been implicated in numerous functions, including normal and aberrant development of a variety of tissues. Although no soluble ligand has been identified for ErbB2, we have recently shown that ASGP‐2, the transmembrane subunit of the cell surface glycoprotein Muc4 (also called sialomucin complex, SMC), can act as an intramembrane ligand for ErbB2 and modulate its activity. Muc4/SMC is abundantly expressed at the apical surface of most epithelia of the rat female reproductive tract. Since Muc4/SMC can interact with ErbB2 when they are expressed in the same cell and membrane, we investigated whether these two proteins are co‐expressed and co‐localized in tissues of the female reproductive tract. Using an anti‐ErbB2 antibody from Dako, we found moderate staining at the basolateral surface of the oviduct and also around the cell membrane of the most superficial and medial layers of the stratified epithelia of the vagina. In contrast, Neomarkers neu Ab1 antibody intensely stained the apical surface of the epithelium of the oviduct and the medial and basal layers of the stratified epithelia of the vagina, substantially overlapping the distribution of Muc4/SMC. Furthermore, Muc4/SMC and ErbB2 association in different tissues of the female reproductive tract was demonstrated by co‐immunoprecipitation analysis. Interestingly, phosphorylated ErbB2 detected by anti‐phospho‐ErbB2 is primarily present at the apical surface of the oviduct. Thus, our results show that differentially localized forms of ErbB2 are recognized by different antibodies and raise interesting questions about the nature of the different forms of ErbB2, the mechanism for differential localization, and possible functions of ErbB2 in the female reproductive tract. They also raise a cautionary note about the use of different ErbB2 antibodies for expression and localization studies. © 2001 Wiley‐Liss, Inc.
Induction of neutrophil apoptosis and secondary necrosis during endotoxin‐induced pulmonary inflammation in mice
Authors: Medan Djordje , Wang Liying , Yang Xiaodong , Dokka Sujatha , Castranova Vincent , Rojanasakul Yon 
Published: August 2002

AbstractThe present study investigated the relationship between apoptotic and necrotic cell death and their role in pulmonary inflammatory response to endotoxin. Pulmonary administration of lipopolysaccharide (LPS) caused a rapid increase in the levels of pro‐inflammatory cytokine TNF‐α and inflammatory cell influx in the bronchoalveolar lavage (BAL) fluids. Control mice showed only resident alveolar macrophages with no apoptosis, whereas LPS‐treated mice showed clear apoptosis of BAL cells. Microscopic studies confirmed the presence of apoptotic neutrophils and macrophages ingesting apoptotic bodies. The number of apoptotic neutrophils increased concomitantly with the increase in neutrophil influx which peaked 1 day after the treatment. However, necrosis was not detected at this early time, but increased subsequently and peaked at day 3. The levels of necrosis and apoptosis were both elevated and prolonged at high LPS doses. Treatment of mice with phosphatidylserine (PS)‐containing liposome, known to inhibit macrophage phagocytosis of apoptotic cells, increased the level of apoptosis and necrosis caused by LPS, whereas control non‐PS liposome or saline treatment had no effects. We conclude that necrosis occurs secondary to apoptosis in LPS‐treated lung model and that this development is not the result of direct insult by LPS. Instead, our results and previous studies suggest that inefficient clearance of apoptotic cells by macrophages contributes, at least in part, to the levels of apoptosis and necrosis induced by LPS. Because necrosis is associated with cell damage and release of histotoxic contents, this development is likely to play a role in determining the severity and duration of lung toxicity induced by endotoxin. © 2002 Wiley‐Liss, Inc.
β‐estradiol stimulation of DNA synthesis requires different PKC isoforms in HepG2 and MCF7 cells
Authors: Marino Maria , Distefano Enza , Caporali Simona , Ceracchi Gianna , Pallottini Valentina , Trentalance Anna 
Published: August 2002

AbstractThe role exerted by protein kinase C (PKC) on estrogen‐induced DNA synthesis has been investigated in hepatic and mammary gland cells, HepG2 and MCF7. 17‐β‐estradiol stimulated DNA synthesis in HepG2 and MCF7 cells, maximal effect occurring at 10 nM. DNA synthesis stimulation was prevented by anti‐estrogen ICI 182,780 and by inhibitor of PKC, Ro 31‐8220. The rapid estradiol effects in MCF7 cells were determined by following the inositol trisphosphate (IP3) production and PKC‐α membrane translocation. After estradiol treatment the increase of IP3 production, prevented by anti‐estrogen or by phospholipase C (PLC) inhibitor (neomycin), was present in MCF7 cells. In MDA cells, devoid of estrogen receptor, no effect was observed. The PKC‐α presence on the membranes appeared unchanged in MCF7 cells. The PLC inhibitors, neomycin and U73,122, and PKC‐α down regulator, phorbol 12‐myristate 13‐acetate (PMA), were able to prevent estradiol‐induced DNA synthesis in hepatoma cells, but ineffective in mammary cells; wortmannin, an inhibitor of phosphoinositide 3‐kinases (PI3‐K), blocked DNA synthesis in both cell lines. These data show that β‐estradiol, via an estrogen receptor‐mediated mechanism, activates more signal transduction pathways, and consequently different PKC isoforms in two responsive cell lines. In both cell lines PI3‐K/PKC pathway is functional to the estrogen regulation of DNA synthesis, whereas in HepG2 cells the parallel involvement of the PLC/PKC‐α pathway is present. The reported results indicate that the DNA synthesis stimulation by β‐estradiol requires the estrogen receptor and utilises one or more activated pathways in dependence on the cell equipment. © 2001 Wiley‐Liss, Inc.
High‐level extracellular production of penicillin acylase by genetic engineering of Escherichia coli
Authors: Lin Wen‐Jer , Huang Shin‐Wei , Chou C Perry 
Published: August 2002

AbstractThe extracellular production of penicillin acylase (PAC) in genetically engineered Escherichia coli by coexpression of the brp gene encoding bacteriocin release protein (BRP) and the pac gene was demonstrated. Cell physiology was affected while PAC was released into the medium, depending on the strategy for brp expression. The performance for the production and release of PAC was optimized by taking several culture parameters, including host, inducer (mitomycin C) concentration, and induction timing for brp expression, into consideration. The effect of PAC release on inclusion body formation was also investigated. It was observed that the amount of inclusion bodies was significantly affected by brp expression. A reason for the limitation of PAC production and a strategy for resolving this problem are proposed.© 2001 Society of Chemical Industry
Use of the axial dispersion model to describe the O3 and O3 /H2O2 advanced oxidation of alachlor in water
Authors: Beltrán Fernando J , González Manuel , Acedo Benito , Rivas Javier 
Published: August 2002

AbstractExperiments on alachlor degradation by ozonation alone and combined with hydrogen peroxide using different surface waters have been conducted in a reactor bubble column and a kinetic model of the advanced oxidation process has been proposed. Variables studied were the nature of the surface water (four surface waters were treated), pH (3.5–9.7) and hydrogen peroxide to ozone mass ratio at the column inlet (0.1–1.85 g g−1). Data on residence time distribution, rate constants and the absorption kinetic regime were considered to prepare the kinetic model, which was also based on the axial dispersion model of non‐ideal flow. The model gives good predictions of alachlor and hydrogen peroxide conversions and the fraction of dissolved ozone (deviations were lower than ±15%) although it fails, in some cases, to yield accurate estimates of the observed experimental trends of concentrations in water at the reactor column outlet. The calculated results were close to those obtained from the more classical N well‐mixed tanks‐in‐series model (deviations with this model were lower than ±20%). It is concluded that quantitative deviations from experimental observations were likely due to the lack of rate data on ozone reactions with organic matter present in the surface waters investigated.© 2002 Society of Chemical Industry
Sonographic appearances of galactoceles
Authors: Sawhney Sukhpal , Petkovska Liljana , Ramadan Salwa , Al‐Muhtaseb Sayeed , Jain Rajeev , Sheikh Mehraj 
Published: August 2002

AbstractPurposeThe aim of this study was to investigate and summarize the sonographic appearances of galactoceles.MethodsWe retrospectively reviewed the sonograms and clinical records of 10 patients with galactoceles who had been examined over a 5‐year period to evaluate breast lumps that had occurred during lactation or the puerperium.ResultsSonograms from all patients showed well‐defined lesions with thin, echogenic walls. The internal appearances of the lesions included homogeneous contents with medium‐level echoes in 6 patients and heterogeneous contents with fluid clefts and anechoic rims in 4 patients. Focal echogenic areas with distal shadowing were seen in 2 patients. Most of the lesions showed some distal acoustic enhancement, depending on the internal contents. The diagnosis of a galactocele was established by needle aspiration in 9 patients and by excision biopsy in 1 patient. Needle aspiration alone was therapeutic in 8 patients.ConclusionsGalactoceles can have a wide range of sonographic appearances and can mimic other lesions of the breast, both benign and malignant. The clues to the diagnosis are recent childbirth and lactation and the presence of a well‐defined lesion with some distal acoustic enhancement. Needle aspiration of the lesion is both a diagnostic tool and an effective treatment in most patients with galactoceles. © 2002 John Wiley & Sons, Inc. J Clin Ultrasound 30:18–22, 2002.
Comparison of the sonographic features of acalculous and calculous submandibular sialadenitis
Authors: Ching Alex Sik‐Chung , Ahuja Anil T. , King Ann D. , Tse Gary Man‐Kit , Metreweli Constantine 
Published: August 2002

AbstractObjectiveThe purpose of this study was to compare the sonographic features of acalculous and calculous sialadenitis of the submandibular gland.MethodsA retrospective review of sonograms of the neck was performed in 25 patients with submandibular sialadenitis: 8 with acalculous and 17 with calculous disease. The submandibular glands were assessed for size, shape, border, and echogenicity; presence of dilated ducts or other intraglandular lesions; inflammatory changes in adjacent tissues; lymphadenopathy; and involvement of other salivary glands.ResultsIn the group with acalculous sialadenitis, 4 (50%) of the 8 patients had unilateral disease, and 11 (92%) of 12 glands were rounded. In all cases (100%), multiple hypoechoic lesions were diffusely distributed throughout the submandibular glands against a heterogeneous parenchymal background. The lesions ranged from 3 to 15 mm and were oval or round. Confluent lesions were noted in 2 glands (17%). There was no sonographic evidence of duct dilatation, calculi, or abnormal lymph nodes. All patients with calculous sialadenitis had unilateral disease; 9 had a main duct calculus (53%), 7 had intraglandular calculi (41%), and 1 had both (6%). In 14 (82%) of 17 glands, normal shape was maintained, and 11 (65%) of 17 had duct dilatation.ConclusionsAcalculous submandibular sialadenitis differs from the calculous form of the disease. The former has characteristic sonographic features, including a round gland with numerous hypoechoic lesions in a heterogeneous parenchymal background. Sonographic imaging in conjunction with fine‐needle aspiration is useful for detection of this disorder. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:332–338, 2001.