bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytoplasmic complex of p53 and eEF2
Authors: Yin Xia , Fontoura Beatriz M.A. , Morimoto Takashi , Carroll Robert B.
Published: July 2003

We have shown previously that cytoplasmic p53 is covalently linked to 5.8S rRNA. The covalent complex is associated with a small subset of polyribosomes, which includes polyribosomes translating p53 mRNA. Because 5.8S rRNA resides in or near the ribosomal P site, our findings suggested involvement of p53 in translational regulation. Ninety‐seven kiloDaltons eEF2 was found to coimmunoprecipitate in a salt‐stable complex with p53. The 97 kDa species was identified as eEF2, because it was (1) recognized by a polyclonal antiserum specific for eEF2, (2) ADP‐ribosylated by diphtheria toxin (DT), and (3) radiolabeled by γ‐32P‐azido‐GTP and UV‐irradiation. p53 and eEF2 sedimented in sucrose gradients in both polyribosomal and subribosomal fractions. Subribosomal p53 can bind eEF2 without the mediation of ribosomes, because (1) it binds subribososomal eEF2, (2) it binds phosphorylated eEF2, and (3) subribosomal p53‐bound eEF2 can be ADP‐ribosylated by DT. No effect of p53 activation was found on eEF2 expression or phosphorylation. However, the binding of eEF2 to p53 decreased when cytoplasmic p53 migrated to the nucleus. Renaturation of temperature sensitive A135V mutant p53 (ts‐p53) was found to alter the sensitivity of p53 mRNA translation, but not bulk mRNA translation, to the translocation‐specific elongation inhibitor, cycloheximide (Cx). The association of p53 with two translational components involved in ribosomal translocation, eEF2 and 5.8S rRNA, and the effect of p53 on sensitivity to the translocation inhibitor, Cx, as well as the known molecular interactions of these components in the ribosome suggest involvement of p53 in elongation. J. Cell. Physiol. 196: 475–482, 2003. © 2003 Wiley‐Liss, Inc.
Effects of collagen density on cardiac fibroblast behavior and gene expression
Authors: Loftis Melissa Joy , Sexton Dacia , Carver Wayne
Published: July 2003

Interactions between cells and the extracellular matrix (ECM) play essential roles in modulating cell behavior during development and disease. The myocardial ECM is composed predominantly of interstitial collagen type I and type III. The composition, organization, and accumulation of these collagens are altered concurrent with cardiovascular development and disease. Changes in these parameters are thought to play significant roles in myocardial function. While a number of studies have examined how changes in the ECM affect myocardial function as a whole, much less is known regarding the response at the cellular level to changes in the collagenous ECM. Experiments were carried out to determine the effects of alterations in collagen density and ECM stiffness on the behavior of isolated heart fibroblasts. In vitro bioassays were performed to measure the effects of changes in collagen concentration (0.75–1.25 mg/ml) on adhesion, migration, spreading, and gene expression by heart fibroblasts. Increased density of collagen in 3‐dimensional gels resulted in more efficient adhesion, spreading, and migration by heart fibroblasts. These experiments indicated that the density of the collagen matrix has a significant impact on fibroblast function. These studies begin to elucidate the effects of ECM density at the cellular level in the myocardium. J. Cell. Physiol. 196: 504–511, 2003. © 2003 Wiley‐Liss, Inc.
Rap1, a small GTP‐binding protein is upregulated during arrest of proliferation in human keratinocytes
Authors: D'Silva N.J. , Mitra R.S. , Zhang Z. , Kurnit D.M. , Babcock C.R. , Polverini P.J. , Carey T.E.
Published: July 2003

Rap1 is a small GTP‐binding protein (SMG) that exists in two 95% homologous isoforms, rap1A and rap1B. The functions of the rap1 proteins are not well understood. In this report we examined expression and function of rap1 in primary (HOKs) and immortalized (IHOKs) human oral keratinocytes under different growth conditions. In HOKs, rap1 increased with passage number, suggesting a role in differentiation and arrest of proliferation. Similarly, when inhibition of proliferation and differentiation were induced in HOKs by 1.2 mM CaCl2, both rap1 and involucrin increased with increasing concentrations of CaCl2. However, when similar experiments were done with IHOKs, which continue to proliferate in the presence of 1.2 mM CaCl2, the increase in involucrin expression was similar to HOKs but there was no substantial increase in rap1, suggesting that increased expression of rap1 is linked to inhibition of proliferation rather than differentiation of keratinocytes. Upon transfection of immortalized keratinocytes with rapGAP, which inactivates both isoforms of endogenous active rap1, enhanced proliferation was observed. Thus, we conclude that rap1 inhibits proliferation in keratinocytes. J. Cell. Physiol. 196: 532–540, 2003. © 2003 Wiley‐Liss, Inc.
Cell surface expression of C1qRP/CD93 is stabilized by O‐glycosylation
Authors: Park Minha , Tenner Andrea J.
Published: July 2003

C1qRP/CD93 is a cell surface receptor predominantly expressed on monocytes, neutrophils, endothelial cells, and early stem cell precursors. In phagocytic cells, it has been characterized as contributing to the enhancement of FcR‐ and CR1‐induced phagocytosis triggered by innate immune system defense collagens such as C1q and mannose binding lectin (MBL). Previously, we demonstrated a high level of glycosylation on C1qRP/CD93 that was predominantly O‐linked. In this study, we investigate the role of glycosylation in C1qRP/CD93 stability first by inhibiting O‐glycosylation by addition of benzyl 2‐acetamido‐2‐deoxy‐α‐D‐galactopyranoside (BAG) to the human histiocytic cell line U937, and secondly, by expression of C1qRP/CD93 in the CHO‐derived cell line ldlD which has a reversible defect in protein glycosylation. In both U937 cells and in ldlD cells transfected to express C1qRP/CD93, glycosylation deficiency caused cell surface expression levels of C1qRP/CD93 to decrease, concomitant with the detection of C1qRP/CD93 reactivity in the culture media. Metabolic labeling studies show that when glycosylation is absent, C1qRP/CD93 is synthesized and rapidly released into the culture supernatant or degraded. These studies demonstrate that O‐glycosylation is important in the stable cell surface expression of C1qRP/CD93. J. Cell. Physiol. 196: 512–522, 2003. © 2003 Wiley‐Liss, Inc.
Endothelial cell functions
Authors: Michiels Carine
Published: July 2003

Endothelial cells play a wide variety of critical roles in the control of vascular function. Indeed, since the early 1980s, the accumulating knowledge of the endothelial cell structure as well as of the functional properties of the endothelial cells shifted their role from a passive membrane or barrier to a complex tissue with complex functions adaptable to needs specific in time and location. Hence, it participates to all aspects of the vascular homeostasis but also to physiological or pathological processes like thrombosis, inflammation, or vascular wall remodeling. Some of the most important endothelial functions will be described in the following review and more specifically, their role in blood vessel formation, in coagulation and fibribolysis, in the regulation of vascular tone as well as their participation in inflammatory reactions and in tumor neoangiogenesis. J. Cell. Physiol. 196: 430–443, 2003. © 2003 Wiley‐Liss, Inc.
The non‐homologous end‐joining pathway is not involved in the radiosensitization of mammalian cells by heat shock
Authors: Dynlacht Joseph R. , Bittner M. Eric , Bethel Jody A. , Beck Brian D.
Published: July 2003

A synergistic increase in cell killing is observed when a heat‐shock is administered prior to, during, or immediately after exposure to ionizing radiation (IR). This phenomenon, known as heat‐radiosensitization, is believed to be mediated by inhibition of repair of radiation‐induced double strand breaks (DSB) when cells are exposed to temperatures above 42°C. However, the mechanism by which heat inhibits DSB repair is unclear. The bulk of radiation‐induced DSBs are repaired via the non‐homologous end‐joining pathway (NHEJ). Several reports indicate that the Ku70 and Ku80 subunits of the mammalian DNA‐dependent protein kinase (DNA‐PK), a complex involved in NHEJ, appear to be susceptible to a heat‐induced loss of DNA‐binding activity, with Ku80 representing the heat‐sensitive component. Since the heat‐induced loss and subsequent recovery of Ku–DNA binding activity correlates well with heat‐radiosensitization, a role for Ku80 and NHEJ in heat‐radiosensitization has been proposed. However, direct evidence implicating Ku80 (and NHEJ) in heat‐radiosensitization has been indeterminate. In this study, we demonstrate that equitoxic heat treatments at 42.5–45.5°C induce a similar amount of aggregation of Ku80 in human U‐1 melanoma cells. These data suggest that the time–temperature‐dependent relationship between heat lethality and Ku80 aggregation are similar. However, the aggregation/disaggregation of Ku80 and its transient or permanent inactivation is unrelated to heat‐radiosensitization. When survival curves were obtained for irradiated or irradiated and heated Ku80−/− mouse embryo fibroblasts (MEFs) and compared with survival curves obtained for wild‐type (WT) cells, we found that heat‐radiosensitization was not reduced in the Ku80−/− cells, but actually increased. Thus, our findings indicate that Ku80 is not essential for heat‐radiosensitization. Non‐involvement of Ku‐dependent or Ku‐independent NHEJ pathways in heat‐radiosensitization was confirmed by comparing clonogenic survival between DNA ligase IV‐defective and WT human cells. Our data therefore implicate homologous recombination in inhibition of repair of radiation‐induced DSBs and as a target for heat‐radiosensitization. J. Cell. Physiol. 196: 557–564, 2003. © 2003 Wiley‐Liss, Inc.
Tumor suppressor pRB functions as a co‐repressor of the CCAAT displacement protein (CDP/cut) to regulate cell cycle controlled histone H4 transcription
Authors: Gupta Sunita , Luong Mai X. , Bleuming Sylvia A. , Miele Angela , Luong Michael , Young Daniel , Knudsen Erik S. , van Wijnen Andre J. , Stein Janet L. , Stein Gary S.
Published: July 2003

The CCAAT displacement protein (CDP‐cut/CUTL1/cux) performs a key proliferation‐related function as the DNA binding subunit of the cell cycle controlled HiNF‐D complex. HiNF‐D interacts with all five classes (H1, H2A, H2B, H3, and H4) of the cell‐cycle dependent histone genes, which are transcriptionally and coordinately activated at the G1/S phase transition independent of E2F. The tumor suppressor pRB/p105 is an intrinsic component of the HiNF‐D complex. However, the molecular interactions that enable CDP and pRB to form a complex and thus convey cell growth regulatory information onto histone gene promoters must be further defined. Using transient transfections, we show that CDP represses the H4 gene promoter and that pRB functions with CDP as a co‐repressor. Direct physical interaction between CDP and pRB was observed in glutathione‐S‐transferase (GST) pull‐down assays. Furthermore, interactions between these proteins were established by yeast and mammalian two‐hybrid experiments and co‐immunoprecipitation assays. Confocal microscopy shows that subsets of each protein are co‐localized in situ. Using a series of pRB mutants, we find that the CDP/pRB interaction, similar to the E2F/pRB interaction, utilizes the A/B large pocket (LP) of pRB. Thus, several converging lines of evidence indicate that complexes between CDP and pRB repress cell cycle regulated histone gene promoters. J. Cell. Physiol. 196: 541–556, 2003. © 2003 Wiley‐Liss, Inc.
Forkhead transcription factor FoxO1 transduces insulin‐like growth factor's signal to p27Kip1 in primary skeletal muscle satellite cells
Authors: Machida Shuichi , Spangenburg Espen E. , Booth Frank W.
Published: July 2003

The insulin‐like growth factor I (IGF‐I) stimulates muscle satellite cell proliferation. Chakravarthy et al., (2000, J Biol Chem 275:35942–35952.) previously found that IGF‐I‐stimulated proliferation of primary satellite cells was associated with the activation of phosphatidylinositol 3′‐kinase (PI3K)/Akt and the downregulation of a cell‐cycle inhibitor p27Kip1. To understand mechanisms by which IGF‐I signals the downregulation of p27Kip1 in rat skeletal satellite cells, the role of Forkhead transcription factor FoxO1 in transcriptional activity of p27Kip1 was examined. When primary rat satellite cells were transfected with a p27Kip1 promoter–reporter gene construct, IGF‐I (100 ng/ml) inhibited specific p27Kip1 promoter activity. Addition of LY294002, an inhibitor of PI3K, reversed the IGF‐I‐mediated downregulation of p27Kip1 promoter activity. Co‐transfection of wild type (WT) FoxO1 into satellite cells increased p27Kip1 promoter activity in the absence of IGF‐I supplementation. Addition of IGF‐I reversed the induction of p27Kip1 promoter activity by WT FoxO1. When a mutated FoxO1 (without Thr24, Ser256, and Ser316 Akt phosphorylation sites) was used, IGF‐I was no longer able to reverse the FoxO1 induced stimulation of p27Kip1 promoter activity that had been seen when WT FoxO1 was present. When the satellite cells were treated with IGF‐I, phosphorylation of Akt‐Ser473 and FoxO1‐Ser256 was increased. In addition, when the cells were pre‐incubated with LY294002 before IGF‐I stimulation, the phosphorylation of Akt‐Ser473 and FoxO1‐Ser256 was inhibited, implying that phosphorylation of Akt and FoxO1 was downstream of IGF‐I‐induced PI3K signaling. However, IGF‐I did not induce phosphorylation of FoxO1 on residues Thr24 and Ser316. These results suggested that IGF‐I induced the phosphorylation of Ser256 and inactivated FoxO1 thereby downregulating the activation of the p27Kip1 promoter. Thus, inactivation of FoxO1 by IGF‐I plays a critical role in rat skeletal satellite cell proliferation through regulation of p27Kip1 expression. J. Cell. Physiol. 196: 523–531, 2003. © 2003 Wiley‐Liss, Inc.
Ionic basis for excitability of normal rat kidney (NRK) fibroblasts
Authors: Harks E.G.A. , Torres J.J. , Cornelisse L.N. , Ypey D.L. , Theuvenet A.P.R.
Published: July 2003

Ionic membrane conductances of normal rat kidney (NRK) fibroblasts were characterized by whole‐cell voltage‐clamp experiments on single cells and small cell clusters and their role in action potential firing in these cells and in monolayers was studied in current‐clamp experiments. Activation of an L‐type calcium conductance (GCaL) is responsible for the initiation of an action potential, a calcium‐activated chloride conductance (GCl(Ca)) determines the plateau phase of the action potential, and an inwardly rectifying potassium conductance (GKir) is important for the generation of a resting potential of approximately −70 mV and contributes to action potential depolarization and repolarization. The unique property of the excitability mechanism is that it not only includes voltage‐activated conductances (GCaL, GKir) but that the intracellular calcium dynamics is also an essential part of it (via GCl(Ca)). Excitability was found to be an intrinsic property of a fraction (∼25%) of the individual cells, and not necessarily dependent on gap junctional coupling of the cells in a monolayer. Electrical coupling of a patched cell to neighbor cells in a small cluster improved the excitability because all small clusters were excitable. Furthermore, cells coupled in a confluent monolayer produced broader action potentials. Thus, electrical coupling in NRK cells does not merely serve passive conduction of stereotyped action potentials, but also seems to play a role in shaping the action potential. J. Cell. Physiol. 196: 493–503, 2003. © 2003 Wiley‐Liss, Inc.
Pierre Janet and Félida Artificielle: Multiple personality in a nineteenth‐century guise
Authors: Brown Edward M.
Published: July 2003

In the wake of the recent epidemic of multiple personality phenomena, it is important to get a clear idea of what similar phenomena looked like in previous centuries. Pierre Janet's detailed description of his discovery, made during the 1880s, that he could cure hysteria by creating a healthy second personality offers a close look at a form of multiple personalities very different from what has recently been described. His description of the factors that influenced his discovery allow one to see his work in a historical context and to appreciate his confrontation with the paradoxes that this discovery revealed. © 2003 Wiley Periodicals, Inc.
Archival note: An inquiry into the relationshp between Alfred Binet and Cyril Burt
Authors: Faber Diana
Published: July 2003

Two recent archival items offer material for analysis of Alfred Binet's (1857–1911) and Cyril Burt's (1883–1971) relationship in the early twentieth century. Burt's letter to Binet's biographer Theta Wolf was an answer to her request for information about his contact with Binet. An analysis of Burt's account prompts more questions than it answers. His statements in the letter are compared with previous ones and are put into the context of the activities of the two men, but these do not enlighten us about his actual relations with Binet. The problem arises because of Burt's desciptive vagueness and lack of supporting evidence. Despite attacks against Burt's integrity made from 1976 onward, we found no conclusive evidence of false claims. The negative outcome of this analysis probably results from Burt's faulty memory, and herein lies the caveat that personal memories make unreliable material for historical accounts. © 2003 Wiley Periodicals, Inc.
Gregory Bateson on deutero‐learning and double bind: A brief conceptual history
Authors: Visser Max
Published: July 2003

The concepts of deutero‐learning and double bind have acquired an increasingly important status in various fields of social and behavioral science, particularly in psychiatry, psychotherapy, organization, and policy science. With this proliferation, however, their original meaning and significance has become increasingly muted. In this article it is argued that both concepts are important ingredients of a behavioral theory of (organizational) learning. To support this argument, the development of both concepts is traced to the work of Gregory Bateson. In Bateson's thinking, the two concepts have a firm base in dyadic behavior and interaction. © 2003 Wiley Periodicals, Inc.
Legislative warriors: American psychiatrists, psychologists, and competing claims over psychotherapy in the 1950s
Authors: Buchanan Roderick D.
Published: July 2003

American psychiatrists and psychologists have long been close colleagues and fierce rivals. There is no better illustration of this polarized relationship than the chronic tug‐of‐war over psychotherapy. Both groups laid claim to psychotherapy—whatever it was and however it was practiced. Psychiatrists attempted to monopolize psychotherapy despite its ambiguous status as an essential component of the healing arts. After the war, psychologists pressed for a share on the basis of their qualifications and competence, but struggled to overcome the limitations imposed by medical envy. This story lays bare the crucial function of tools and techniques for defining the identity and the boundaries of a science‐based profession. © 2003 Wiley Periodicals, Inc.
The modern confessional: Anglo‐American religious groups and the emergence of lay psychotherapy1
Authors: Falby Alison
Published: July 2003

This article reconceives of secularization as a gradual process of increasing interaction between the (social) scientific and spiritual realms by examining the influence of Christian ideas of group confession on lay psychotherapeutic groups in Britain, Canada, and the U.S. in the early twentieth century. This article focuses on three religious group leaders of the interwar period: Frank Buchman (1878–1961), Gerald Heard (1889–1971), and Henry Burton Sharman (1865–1953). Influenced by Natural Theology and the holiness movement, they placed sin and its redemption within the world, reconceiving it as psychological individualism and its redemption as self‐sacrifice to the group. This reconception endorsed the moral power of groups and influenced Alcoholics Anonymous and various groups within the Human Potential Movement. © 2003 Wiley Periodicals, Inc.
Factors that influence the expansion of the microenterprise sector: results from three national surveys in Zimbabwe
Authors: Daniels Lisa
Published: July 2003

Using panel data from three nationwide surveys in Zimbabwe, an error components model is estimated to explore the factors that drive the small‐enterprise sector. Among labour‐intensive industries in urban areas, entry of new enterprises appears to be driven by surplus labour. This is supported by low barriers to entry and the negative relationship between economic growth and entry rates. In contrast, entry in capital‐intensive industries is unrelated to economic growth and it is characterized by significant barriers to entry, including capital, working capital, and proprietor experience. With the exception of labour‐intensive industries in rural areas, entry in all other small‐enterprise industries is positively correlated with agricultural income. Copyright © 2003 John Wiley & Sons, Ltd.
Lending technologies, competition and consolidation in the market for microfinance in Bolivia
Authors: Navajas Sergio , Conning Jonathan , Gonzalez‐Vega Claudio
Published: July 2003

Innovations in lending technologies and market saturation have made La Paz, Bolivia one of the most rapidly changing and competitive microfinance markets in the world. Two lenders stand out: the pioneer BancoSol, which first profitably expanded the loan market with group liability loans, and the later entrant Caja Los Andes, which offered individual liability loans using costlier screening. Using a simple model of credit market competition with moral hazard and adverse selection we analyse how the terms of loan contracts were adapted to changes in competition and how borrowers' incentive to remain diligent and repay loans was affected. Hypothesized behaviour derived from the model is tested and shown to be consistent with empirical evidence from loan records and a household survey. Copyright © 2003 John Wiley & Sons, Ltd.
More on the effectiveness of public spending on health care and education: a covariance structure model
Authors: Baldacci Emanuele , Guin‐Siu Maria Teresa , Mello Luiz De
Published: July 2003

Using data for a sample of developing countries and transition economies, this paper estimates the relationship between government spending on health care and education and selected social indicators. Unlike previous studies, where social indicators are used as proxies for the unobservable health and education status of the population, this paper estimates a latent variable model. The findings suggest that public spending is an important determinant of social outcomes, particularly in the education sector. Overall, the latent variable approach yields better estimates of a social production function than the traditional approach, with higher elasticities of social indicators with respect to income and spending, therefore providing stronger evidence that increases in public spending do have a positive impact on social outcomes. Copyright © 2003 John Wiley & Sons, Ltd.
Exploring sustainable livelihoods approaches in relation to two interventions in Tanzania
Authors: Toner Anna
Published: July 2003

Whilst sustainable livelihoods ‘thinking’ is potentially valuable in advancing our understanding of the complexity and socially embedded nature of people's lives, sustainable livelihoods frameworks and principles are too eager to codify this complexity and to produce toolboxes and techniques to change the internal management of development interventions.

Drawing on research in Tanzania, this paper offers an analysis of two interventions that apply aspects of sustainable livelihoods approaches (SLA). Whilst both interventions demonstrate much good practice, both are fundamentally limited in their potential for sustainable impact. This paper demonstrates the importance of the external context within which an intervention exists and explores some of the limitations faced by development agencies in trying to ‘manage’ sustainability. Copyright © 2003 John Wiley & Sons, Ltd.
Private capital formation and public investment in Sudan: testing the substitutability and complementarity hypotheses in a growth framework
Authors: Badawi Ahmed
Published: July 2003

The paper attempts to address the issue of complementarity and substitutability of state capital to private sector investment activities in a neoclassical growth framework. It employs a co‐integrated vector autoregressive model to account for potential endogeneity and nonstationarity problems. Results suggest that both private and public capital spending have stimulated economic growth in Sudan over the period 1970–1998. The impact of private investment on real growth has been more pronounced than that of public sector investment. Public sector investment appears to have deleteriously impacted private sector physical capital expansion, implying that the impact of crowding‐out categories of public sector investment has been large enough to offset any crowding‐in effects. Such crowding out effect has weakened favourable positive effect that public sector's investment has exerted on growth by jeopardising private sector capital undertakings. Copyright © 2003 John Wiley & Sons, Ltd.
Separation of bacteria by capillary electrophoresis
Authors: Buszewski Bogusław , Szumski Michał , Kłodzińska Ewa , Dahm Hanna
Published: July 2003

Differences in the surface charges of bacteria can be exploited for their separation by capillary electrophoresis. Because of their low electrophoretic mobility, the separation is not always easy to perform, especially in the presence of the electroosmotic flow. Elimination of electroosmotic flow by capillary wall modification with γ‐(trimethoxysilyl)propyl methacrylate followed by acrylamide bonding permits separation over a distance of 8.5 cm.
Supported liquid membrane separation of amine and amino acid derivatives with chiral esters of phosphoric acids as carriers
Authors: Dżygiel Paweł , Wieczorek Piotr , Kafarski Paweł
Published: July 2003

Studies on the possible use of phosphate and phosphonate esters bearing chiral menthol or nopol moieties as carriers for the transport of amines, amino acids, and amino acid esters through supported liquid membranes (SLM) are presented. Additionally, the enantioselectivity of the SLM transport of alkyl esters of aromatic amino acids and a non‐protein amino acid was also evaluated. It could be concluded that the extent of transport strongly depends on the hydrophobicity of the amino compound. Moreover, the carrier structure also influences the transport of those compounds through SLM: chiral phosphate and phosphonate esters appear to be poor or moderate carriers for enantioselective SLM transport of amino acids and their esters. The transport efficiency and selectivity is strongly dependent on the structure of both the transported compounds and the carrier. However, no meaningful relationship exists between these structural features and transportation or enantioselectivity.
Applicability of glass fiber as a support material for generation of gaseous standard mixtures using thermal decomposition of the surface compound. Calibration of analytical equipment
Authors: Świtaj Anna , Przyk Elżbieta , Szczygelska‐Tao Jolanta , Wójcik Jan , Biernat Jan Franciszek , Namieśnik Jacek , Zygmunt Bogdan
Published: July 2003

The use of glass fiber as a support material for a surface compound serving to generate gaseous standard mixtures of ethene is described. The technique is based on the process of thermal decomposition of the surface compound in a desorber connected on‐line via a multi‐port valve to the calibrated device. The surface compound undergoes thermal decomposition at 245°C, yielding known amounts of ethene. The method enables on‐line preparation of a standard mixture immediately before the calibration step. Consequently, it can be also applied for the generation of standard mixtures containing volatile, malodorous, unstable, and toxic compounds.
Speciation of oxidation states of elements by capillary electrophoresis
Authors: Trojanowicz Marek , Poboży Ewa , Gübitz Gerald
Published: July 2003

Progress made in the last five years in the application of capillary electrophoresis methods to chemical speciation of elements is reported on the basis of over 100 literature references. The main trends observed include development of new on‐ and off‐capillary derivatization methods, application of new detection methods, and especially coupling of CE separation systems to powerful atomic spectroscopy and mass spectrometry instruments with various ionization techniques, providing either a sensitive element‐specific detection method or a third dimension for high performance separation. Besides numerous CZE and MEKC capillary electrophoresis methods only very few examples of CE speciation with capillary electrochromatography can be found. Concerning the chemical forms of elements determined, the new procedures developed are mostly focused on redox speciation of various oxidation states of elements, metal‐bound high molecular compounds, and organometallic species.
Detection of proline, arginine, and lysine using iodine‐azide reaction in TLC and HPTLC
Authors: Zakrzewski Robert , Ciesielski Witold , Kaźmierczak Dorota
Published: July 2003

The application of a modified iodine‐azide procedure for the detection of proline, arginine, and lysine is described. Phenyl isothiocyanate was used to transform amino acids into phenyl thiocarbamyl derivatives (derivatization in situ). The developed plates were sprayed with a mixture of sodium azide and starch solution, adjusted to pH 5.5, and exposed to iodine vapour. Due to the catalytic effect of the CS bond, the spots appeared white on a violet‐grey background and were stable for 20 minutes. The detection limits were found to lie in the pmole range. The iodine‐azide test is compared with other procedures (iodine, UV, ninhydrin).
Old master paintings – A fruitful field of activity for analysts: Targets, methods, outlook
Authors: Zadrożna Irmina , Połeć‐Pawlak Kasia , Głuch Iwona , Ackacha Mohamed A. , Mojski Mirosław , Witowska‐Jarosz Janina , Jarosz Maciej
Published: July 2003

Natural products used by ancient artists as components of paintings on canvas and wood, on sculptures, for murals or illuminated manuscripts are presented as potential analytical targets. Analytical methods recommended so far for the identification of binders, inorganic pigments, and organic dyestuffs are reviewed with special emphasis on hyphenated techniques.
Identification of anthraquinone coloring matters in natural red dyestuffs by high performance liquid chromatography with ultraviolet and electrospray mass spectrometric detection
Authors: Ackacha Mohamed A. , Połeć‐Pawlak Kasia , Jarosz Maciej
Published: July 2003

Reversed phase liquid chromatography with diode array detection (DAD) and electrospray mass spectrometric (ESI MSD) methods were developed for the identification of anthraquinone color components of cochineal, lac dye, and madder – red natural dyestuffs. Electrospray mass spectrometry was found to be more suitable than diode array detection for such analysis because of its higher sensitivity (detection limits in the range 30–90 ng mL–1) and selectivity. The developed method permitted unequivocal identification of carminic acid and laccaic acid A as coloring matters in examined preparations of cochineal and lac dye, respectively. In madder more chemical color species were found: alizarin, purpurin, lucidin, ruberythric acid, and also aluminum and calcium alizarin lake. Among the methods recommended so far, the present one allows fast, direct, and unequivocal identification of components of very complicated natural products used in art.
Ion‐pairing high‐performance liquid chromatography‐mass spectrometry of impurities and reduction products of sulphonated azodyes
Authors: Ansorgová Dana , Holčapek Michal , Jandera Pavel
Published: July 2003

An HPLC separation method with triethylammonium acetate mobile phase additive developed for the analysis of impurities in polysulphonated azo dyes provides good separation selectivity and compatibility with electrospray ionisation (ESI) mass spectrometry. The negative‐ion ESI mass spectra containing only peaks of deprotonated molecules [M–H]– for monosulphonic acids, [M–xH]x–, and sodiated adducts [M–(x + y)H + yNa]x– for polysulphonic acids allow easy molecular mass determination of unknown impurities. Based on the knowledge of the molecular masses and of the fragment ions in the MS/MS spectra, probable structures of trace impurities in commercial dye samples are proposed. To assist in the interpretation of the mass spectra of complex polysulphonated azodyes, additional information can be obtained after chemical reduction of azodyes to aromatic amines. The structures of the non‐sulphonated reduction products can be determined by reversed‐phase HPLC/MS with positive‐ion atmospheric pressure chemical ionisation and of the sulphonated products by ion‐pairing HPLC/MS with negative‐ion ESI.
Characterization of polymer monolithic stationary phases for capillary HPLC
Authors: Moravcová Dana , Jandera Pavel , Urban Jiří , Planeta Josef
Published: July 2003

Monolithic capillary columns have been prepared in fused‐silica capillaries by radical co‐polymerization of ethylene dimethacrylate and butyl methacrylate in the presence of porogen solvent mixtures containing various concentration ratios of 1‐propanol, 1,4‐butanediol, and water with azobisisobutyronitrile as the initiator of the polymerization reaction. The through pores in organic polymer monolithic columns can be characterized by “equivalent permeability particle size”, and the mesopores with stagnant mobile phase by “equivalent dispersion particle size”. Increasing the concentration of propanol in the polymerization mixture diminishes the pore volume and size in the monolithic media and improves the column efficiency, at a cost of decreasing permeability. Organic polymer monolithic capillary columns show similar retention behaviour to packed alkyl silica columns for compounds with different polarities characterized by interaction indices, Ix, but have different methylene selectivities. Higher concentrations of propanol in the polymerization mixture increase the lipophilic character of the monolithic stationary phases. Best efficiencies and separation selectivities were found for monolithic columns prepared using 62–64% propanol in the porogen solvent mixture. To allow accurate characterization of the properties of capillary monolithic columns, the experimental data should be corrected for extra‐column contributions.
Separation of aromatic sulphonic acids by CZE in coated and non‐coated capillaries
Authors: Fischer Jan , Jandera Pavel , Česla Petr , Staněk Václav
Published: July 2003

Capillary zone electrophoresis (CZE), besides ion‐pairing mode HPLC and salting‐out HPLC, is well‐suited for the analysis of aromatic sulphonic acids widely used as intermediates in the production of synthetic dyes and optical brighteners. The separation selectivity in CZE of many aromatic acids, including positional isomers, can be controlled by the type and concentration of a cyclodextrin additive. The influence of the concentration of β‐cyclodextrin in the working electrolyte on the separation of the positional isomers of naphthalene (poly‐)sulphonic acids, and their amino‐ and hydroxy derivatives, by CZE was studied, both in non‐coated fused silica capillaries and in capillaries coated with polyacrylamide. The migration time scale was calibrated using 4‐alkylbenzenesulphonic acids as the calibration standards. Limiting mobilities of the free acid anions and of their complexes with β‐cyclodextrin were calculated and the effect of the inclusion guest‐host complex formation on the CZE separation was quantitatively characterized. The migration order in coated capillaries is reversed with respect to CZE in non‐coated fused silica capillaries, the separation selectivity is different and the separation of polysulphonic acids such as naphthalene tri‐ and tetrasulphonic acids is significantly accelerated.
Regenerative Recycling of Automotive Polymer Components: Poly(propylene) Based Car Bumpers
Authors: Luda Maria Paola , Ragosta Giuseppe , Musto Pellegrino , Acierno Domenico , Di Maio Luciano , Camino Giovanni , Nepote Valeriano
Published: July 2003

There is a dramatic loss in the mechanical performances at the end of the first life application of bumpers made by a poly(propylene) matrix (PP) and an ethylene‐propylene rubber copolymer as dispersed phase. The use of specific additives during the recycling strongly enhances the mechanical properties of these items. The on purpose designed additive contained a regenerative agent and an antioxidant system. The mixing action of the recycling process re‐establishes the phase compatibility; the antioxidants inhibit oxidation, which speeds up the degradation reactions in the recycling process; eventually the regenerative agent joins short chains possessing suitable reactive groups. These three effects play a different role in restoring original material performance in dependence of the recycling process: for instance the regenerative agent may be nearly useless if chain scission is not the dominant process in the recycling operation and the interfacial adhesion between rubber and the matrix does not assure automatically a ductile mechanical behaviour under impact conditions.

SEM micrograph of the fractured surface of the used bumper recycled with additives.

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SEM micrograph of the fractured surface of the used bumper recycled with additives.
Non‐Linear Long‐Term Tensile Creep of Poly(propylene)/Cycloolefin Copolymer Blends with Fibrous Structure
Authors: Kolařík Jan , Pegoretti Alessandro , Fambri Luca , Penati Amabile
Published: July 2003

The tensile deformation of materials with Poisson's ratio smaller than 0.5 generates an additional free volume, which means that tensile creep under constant stress and temperature is a non‐iso‐free volume process. Fractional free volume rising proportionally to the creep strain accounts for a continuous shortening of retardation times. To account for this effect, “internal” time has been introduced which is related to a hypothetical pseudo iso‐free‐volume state. The shift factor along the time scale in the time‐strain superposition is not constant for an isothermal creep curve, but rises monotonically from point to point with the elapsed creep time. The reconstructed compliance dependencies obtained for various stresses approximately obey the time‐strain superposition thus forming a generalised creep curve. A routinely used empirical equation has been found suitable to describe the effects of time and stress on compliance of parent polymers and their blends. The previously proposed predictive format for the time‐dependent compliance of polymer blends has been found applicable also to poly(propylene) (PP)/cycloolefin copolymer (COC) blends with fibrous morphology. As COC shows a tendency to form fibres in a PP matrix, the mixing rule customarily used for fibre composites has been found more appropriate for injection moulded specimens than the equivalent box model for isotropic blends. The predicted compliance curve for a pseudo iso‐free‐volume state can be transformed into a “real” curve for a selected stress σ (in the interval up to the yield stress).

SEM microphotograph of the fractured surface (perpendicular to the injection direction) of the PP/COC blend 60/40.

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SEM microphotograph of the fractured surface (perpendicular to the injection direction) of the PP/COC blend 60/40.
Use of Acrylic Functionalized (Meth)acrylic Cross‐Linked Polymer Microparticles in Photopolymerized Acrylic Films
Authors: Valette Ludovic , Pascault Jean‐Pierre , Magny Benoît
Published: July 2003

The effect of reactive (meth)acrylic cross‐linked polymer microparticles (reactive CPM, also called reactive microgels) used as cross‐linking agents has been studied on the thermo‐mechanical properties of different photopolymerized thin films. The matrix was based on the copolymerization of isobornyl acrylate and ethoxy ethoxy ethyl acrylate or butyl acrylate. Various concentrations of CPM were initially blended with the monomers. These solutions were photopolymerized under UV radiation to obtain hard and transparent films. Since CPM were reactive respect to monomers, they acted as multifunctional cross‐linkers, resulting in networks after polymerization. The well distributed and highly functional CPM which connected acrylate linear chains worked as well defined chemical clusters and gave to the networks a very unique structure. By varying the reactive CPM concentration, the relationship between the number of double bonds introduced into the network by the CPM acting like cross‐linkers and the rubbery modulus of the films was determined from viscoelastic measurements. The structure of CPM, the average functionality and also crystallinity were modified to change networks properties. In addition, reactive groups have been preferentially introduced at the surface vicinity by using a new functional stabilizing agent. CPM were also compared to linear polymers with the same composition. From viscoelastic properties, it is concluded that CPM are very efficient cross‐linkers. However, very high CPM incorporation led to high extent of intramolecular reaction, reducing the cross‐linking efficiency. During thermal aging, CPM and linear copolymer seemed to rearrange leading the film structure to an equilibrium state.

TEM micrograph of a photopolymerized film (30 wt.‐% of CPM‐0% ODA + 70 wt.‐% of IBOA/EEEA) after thermal aging.

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TEM micrograph of a photopolymerized film (30 wt.‐% of CPM‐0% ODA + 70 wt.‐% of IBOA/EEEA) after thermal aging.
In‐Situ Fiberized Poly(ethylene terephthalate) as a Reinforcement to Poly(propylene) Matrix
Authors: Shen Jing‐Wei , Huang Wen‐Yi , Zuo Sheng‐Wu
Published: July 2003

The reinforced poly(propylene) (PP)/poly(ethylene terephthalate) (PET) in‐situ fiberized composites were prepared by extrusion‐drawing‐injection molding. The influences of PET weight fraction (fw) on the PET fiberization, phase morphology, and mechanical properties of the composites, together with their functional mechanisms were studied by contrast to the normal‐blended materials without drawing. The results show that as the fw rises from 0 to 20%, the number of PET fibers increases, whereas their diameter and dispersity decrease till fw = 15% and then increase, and the number of remained PET particles tends to rise. These changes of PET fiberization and phase morphology with fw were attributed to the consequence of the combined actions of breakup, coalescence, and deformation of the PET dispersed phase in the PP matrix during the extrusion drawing. Correspondingly, the tensile strength (σt) and Young's modulus (E) of the in‐situ composites increase till fw = 15% and then decrease, with maximum gains of σt and E of about 20 and 70% relative to the neat PP, respectively. This σt/fw relation was ascribed to the counterbalanced result between the reinforcing effect of the dispersed phase on matrix and the interfacial flaw effect of two immiscible phases, while the E/fw relation was considered as a representation of the rigidizing effect of the fibers on the matrix being controlled by both their number and diameter.

In‐situ PET fibres (PET/PP = 85/15) in an as‐drawn filament.

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In‐situ PET fibres (PET/PP = 85/15) in an as‐drawn filament.
Some Mechanical Properties of Poly[(acrylic acid)‐co‐(itaconic acid)] Hydrogels
Authors: Rodríguez Elena , Katime Issa
Published: July 2003

Two series of hydrogels of poly[(acrylic acid)‐co‐(itaconic acid)] have been prepared by copolymerization in solution using tetrafunctional N,N′‐methylenebisacrylamide (NMBA) as cross‐linker. The resulting polymer was swollen in water at 298 K to yield homogenous transparent hydrogels. These hydrogels were characterized in terms of swelling and compression‐strain measurements. The influence of the comonomer composition and concentration of cross‐linking agent on volumetric swelling and the mechanical properties of these hydrogels were investigated. Inefficient cross‐linking is indicated by the small values of νe relative to the theoretical cross‐linking densities.

Dependence of measured affective cross‐linking density (νe) on the theoretical cross‐linking density (νt) for acrylic acid/itaconic acid hydrogels prepared at a fixed composition of AA80/AI20 wt.‐%, but at different concentrations of NMBA.

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Dependence of measured affective cross‐linking density (νe) on the theoretical cross‐linking density (νt) for acrylic acid/itaconic acid hydrogels prepared at a fixed composition of AA80/AI20 wt.‐%, but at different concentrations of NMBA.
Effect of a single dose of polychlorinated biphenyls on hepatic cell proliferation and the DNA binding activity of NF‐κB and AP‐1 in rats
Authors: Lu Zijing , Tharappel Job C. , Lee Eun Y. , Robertson Larry W. , Spear Brett T. , Glauert Howard P.
Published: July 2003

Polychlorinated biphenyls (PCBs) are environmental pollutants that, because of their persistence and biomagnification, raise concerns about the health consequences of long‐term exposure. PCB mixtures induce hepatocellular carcinomas in rodents, but the mechanism of their promoting activity is not clear. Previous studies have shown that oxidative stress occurs after PCB administration, with the induction of lipid peroxidation and oxidative DNA damage, which may contribute to their promoting activity. In this study, we examined whether the oxidative stress‐sensitive transcription factors NF‐κB or AP‐1 were activated by PCBs in the liver. Male Sprague‐Dawley rats were injected i.p. with corn oil, 2,2′,4,4′,5,5′‐hexachlorobiphenyl (PCB‐153, 30, 150, or 300 μmol/kg), 3,3′,4,4′‐tetrachlorobiphenyl (PCB‐77, 30, 150, or 300 μmol/kg), or both PCBs (each 30 or 150 μmol/kg). Rats were euthanized 2, 6, or 24 h, or 2, 6, and 10 d after the PCB injection. Electrophoretic mobility shift assays (EMSAs) were performed to determine NF‐κB and AP‐1 DNA binding activities. The highest NF‐κB DNA binding activity was observed in rats receiving higher doses of PCB‐153 (150 and 300 μmol/kg), with peak activation occurring 2 d after injection. AP‐1 activation was not detected at any timepoint. Hepatocyte proliferation, as measured by the labeling index, was increased only in groups receiving the highest dose of PCB‐153 or the combination of two PCBs (150 μmol/kg each) at day 2, and not by any other PCB treatment at any timepoint. These results show that PCB‐153, but not PCB‐77, can induce hepatocyte proliferation and hepatic NF‐κB activation after a single dose. © 2003 Wiley‐Liss, Inc.