bluuebunny/crossref_metadata_2025 huggingface dataset:
Romarchite and associated phases as common corrosion products on pewter artifacts from marine archaeological sites
Authors: Dunkle Stacie E. , Craig James R. , Lusardi Wayne R.
Published: July 2004

Corrosion products were examined from typical pewter artifacts originating from six different submerged archaeological sites, dating to between ca. A.D. 1550 and 1733, along the eastern seaboard of North America and in the Caribbean Sea. The artifacts were viewed as 270–450‐year long experiments revealing the phases and mechanisms of tin corrosion in seawater. All of the samples analyzed exhibit abhurite (Sn3O(OH)2Cl2), romarchite (SnO), and hydroromarchite (Sn3O2(OH)2) forming at the expense of the underlying artifact. Textural analysis suggests that abhurite is the first alteration product to form at the expense of the pewter; romarchite subsequently develops and then hydroromarchite. The outermost corrosion layers on several of the most corroded artifacts also exhibit cassiterite (SnO2) as a significant and apparently final phase to form during alteration. The absence of this mineral on many samples demonstrates that, while samples appeared to be stable under the conditions that were present, cassiterite had not yet had time to form. The very limited stability field for romarchite, based on data presented by Séby et al. (Geochimica et Cosmochimica Acta, 65, 3041–3053, 2001), suggests that its presence on these artifacts may be the result of a kinetic effect. The universal appearance of this mineral on corroding tin suggests that it is a required step in the oxidation of pure tin to the final most stable phase of cassiterite. The stability of romarchite and its effectiveness as an agent of passivation can provide insight into not only the formation of tin oxides but the rate of tin corrosion. This can have significant implications in the field of artifact preservation as well as more widespread industrial applications. © 2004 Wiley Periodicals, Inc.
Geoarchaeology and prehistory of the Kipsing and Tol river watersheds in the Mukogodo Hills region of Central Kenya
Authors: Pearl Frederic B. , Dickson D. Bruce
Published: July 2004

An archaeological survey and geomorphological investigation were conducted over a period of three years in the Tol and Kipsing River valleys, both located in the Mukogodo Hills‐Upper Ewaso Ng'iro Plains region of Central Kenya. Eleven alluvial‐stratigraphic sections were studied, and five late‐Quaternary alluvial stratigraphic units were identified on the basis of lithology, chronology, and soil stratigraphy. The locations of 63 archaeological sites recorded during the reconnaissance were compared with the distribution of the alluvial units. These data were used to predict where sites of different cultural periods are most likely to be found and to determine the relationship between site location and alluvial deposition. Since natural processes of deposition and erosion do not fully account for the distribution of Middle and Later Stone Age sites in the study area, the hypothesis that these differences reflect human choices, not the operation of natural processes, cannot be rejected. © 2004 Wiley Periodicals, Inc.
Late holocene behavior of Chaco and McElmo Canyon drainages (Southwest U.S.): A comparison based on archaeologic age controls
Authors: Force Eric R.
Published: July 2004

Two outwardly similar shallow‐canyon drainages of the Four Corners region of the Colorado Plateau (southwestern U.S.), McElmo Creek (SW Colorado) and Chaco Wash (NW New Mexico), expose late Holocene units which have been dated by numerous remains of the puebloan Anasazi culture (A.D. 500–1300). The stratigraphic sequences, though composed of similar sediment facies, show markedly different evolutions. The McElmo Canyon sequence consists of two units separated by an unconformity that apparently represents an arroyo that migrated 5 km upstream in 200 years, suggesting a slow “complex response” model. The dated Chaco Canyon sequence includes an arroyo channel fill seemingly cut simultaneously through a 9–14 km reach, which began filling simultaneously throughout about 100 years later. Base level control seems to have been temporarily controlled by a large eolian sand dune damming Chaco Wash, probably during a dry period. The two entrenchment chronologies do overlap, but the resemblance of either record to published regional chronostratigraphies is minimal. The differences among these regional chronologies suggest that great variety existed among fluvial sequences in prehistory, perhaps more than is seen in present‐day drainages of the region. The contrasting fluvial histories correspond to an equally marked difference in cultural responses, especially in water‐control technology. The strongest obvious similarity between the sequences is probable anthropogenic influence, which is a consequence of using cultural remains for establishing chronological control. A strong influence of climate change is less obvious but still probable if lags in the system and possible intraregional paleoclimatic differences are included in the analysis. © 2004 Wiley Periodicals, Inc.
Hypoxic regulation of Ca2+ signaling in cultured rat astrocytes
Authors: Smith I.F. , Boyle J.P. , Kang P. , Rome S. , Pearson H.A. , Peers C.
Published: July 2004

Acute hypoxia modulates various cell processes, such as cell excitability, through the regulation of ion channel activity. Given the central role of Ca2+ signaling in the physiological functioning of astrocytes, we have investigated how acute hypoxia regulates such signaling, and compared results with those evoked by bradykinin (BK), an agonist whose ability to liberate Ca2+ from intracellular stores is well documented. In Ca2+‐free perfusate, BK evoked rises of [Ca2+]i in all cells examined. Hypoxia produced smaller rises of [Ca2+]i in most cells, but always suppressed subsequent rises of [Ca2+]i induced by BK. Thapsigargin pre‐treatment of cells prevented any rise of [Ca2+]i evoked by either BK or hypoxia. Restoration of Ca2+ to the perfusate following a period of acute hypoxia always evoked capacitative Ca2+ entry. During mitochondrial inhibition (due to exposure to carbonyl cyanide p–trifluromethoxyphenyl hydrazone (FCCP) and oligomycin), rises in [Ca2+]i (observed in Ca2+‐free perfusate) evoked by hypoxia or by BK, were significantly enhanced, and hypoxia always evoked responses. Our data indicate that hypoxia triggers Ca2+ release from endoplasmic reticulum stores, efficiently buffered by mitochondria. Such liberation of Ca2+ is sufficient to trigger capacitative Ca2+ entry. These findings indicate that the local O2 level is a key determinant of astrocyte Ca2+ signaling, likely modulating Ca2+‐dependent astrocyte functions in the central nervous system. © 2004 Wiley‐Liss, Inc.
Low nuclear levels of nuclear factor‐κB are essential for KC self‐induction in astrocytes: Requirements for shuttling and phosphorylation
Authors: Zhai Qiwei , Luo Yi , Zhang Ye , Berman Michael A. , Dorf Martin E.
Published: July 2004

Stimulation with the chemokine KC induces an autocrine response in mouse astrocytes. A requirement for NF‐κB was established for KC self‐induction. NF‐κB inhibitors, p65 antisense oligonucleotides, or dominant‐negative IκBα inhibited this autocrine response. Mutation of a specific κB site in the KC promoter also blocked KC self‐induction. Chromatin immunoprecipitation and in vivo footprinting confirmed the direct binding of NF‐κB to the KC promoter. However, neither NF‐κB nuclear translocation, increased IκB degradation, nor upregulation of NF‐κB DNA binding activity was observed after KC stimulation. Reporter gene assays demonstrated KC‐upregulated NF‐κB transcriptional activity, and this effect was inhibited by dominant‐negative IκBα. Accumulation of NF‐κB was noted within the nucleus in the presence of nuclear export inhibitor leptomycin B, demonstrating constitutive shuttling of NF‐κB between the cytoplasm and nucleus. Blocking NF‐κB shuttling inhibited KC transcription. KC induced p65 phosphorylation, which was critical for NF‐κB activation as determined with the Gal‐4‐p65 fusion protein and mutation of p65 phosphorylation sites. In conclusion, low‐level nuclear NF‐κB is essential for KC self‐induction, and this effect is mediated by shuttling and phosphorylation of NF‐κB. The results outline a novel mechanism for NF‐κB participation in transcription regulation. © 2004 Wiley‐Liss, Inc.
Shaker‐type potassium channel subunits differentially control oligodendrocyte progenitor proliferation
Authors: Vautier François , Belachew Shibeshih , Chittajallu Ramesh , Gallo Vittorio
Published: July 2004

Oligodendrocyte precursor (OP) cells are exposed to multiple extrinsic signals that control their proliferation and differentiation. Previous cell proliferation studies and electrophysiological analysis in cultured cells and in brain slices have suggested that outward potassium channels, particularly Kv1 subunits, may have a prominent role in OP cell proliferation. In the present study, we assessed to what extent overexpression of Kv1.3, Kv1.4, Kv1.5, and Kv1.6 can affect OP cell proliferation and differentiation in culture. We observed that overexpression of Kv1.3 or Kv1.4 increased OP cell proliferation in the absence of mitogens, whereas Kv1.6 overexpression inhibited mitogen‐induced OP cell cycle progression. Interestingly, Kv1.3, Kv1.4, Kv1.5, and Kv1.6 overexpression did not interfere with the kinetics of oligodendrocyte differentiation. This study represents the first demonstration that the activity of potassium channels containing distinct Kv1 subunit proteins directly controls oligodendroglial proliferation in the presence of mitogens, as well as in growth factor‐free conditions. © 2004 Wiley‐Liss, Inc.
Astroglial‐derived lymphotoxin‐α exacerbates inflammation and demyelination, but not remyelination
Authors: Plant Sheila R. , Arnett Heather A. , Ting Jenny P‐y.
Published: July 2004

Tumor necrosis factorα (TNFα) and lymphotoxin‐α (Ltα) are upregulated in and around multiple sclerosis plaques and are proposed to play a role during chronic inflammation in demyelinating disease. Despite the perceived detrimental role of these cytokines, human clinical trials inhibiting TNFα signaling has led to worsening of symptoms in multiple sclerosis (MS) patients. Our laboratory has verified a role for TNFα in the exacerbation of demyelination but, more importantly, has demonstrated a novel role for TNFα in reparative remyelination in a cuprizone‐induced demyelination model. This may explain the worsening of symptoms experienced by MS patients. In view of the cross‐talk in TNF family signaling, the aim of this study is to understand the role of Ltα in demyelination and remyelination in hopes of improving therapeutic strategies for MS. Using the same model, we show that mice lacking Ltα exhibit a delay in demyelination that is greater than that exhibited by TNFα null mice. In this model, Ltα is expressed primarily by astroglia. The delay in demyelination is accompanied by a delay in the loss of mature GSTπ‐positive oligodendrocytes in Ltα−/− mice compared with wild‐type mice. Ltα−/− mice have decreased numbers of microglia at the site of insult during demyelination, although the number of astrocytes present is similar between strains. In contrast to TNFα the lack of Ltα did not alter the time course of remyelination, or the number of mature oligodendrocytes during the remyelination phase. Since Ltα is detrimental in inflammation and demyelination, but not necessary for remyelination and repair, inhibiting Ltα signaling may represent a promising strategy to treat MS. © 2004 Wiley‐Liss, Inc.
Murine complement C4 is not required for experimental autoimmune encephalomyelitis
Authors: Boos Laura A. , Szalai Alexander J. , Barnum Scott R.
Published: July 2004

In vitro studies have demonstrated that myelin and myelin‐derived proteins activate both the classical and alternative complement pathways. More recently, studies have shown that mice deficient in factor B, a protein required for activation of the alternative pathway, have attenuated experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. The relative contribution of the classical pathway to the pathogenesis of EAE has remained unexplored. To address this question, we performed EAE using mice deficient in C4 (C4−/−), a protein required for full activation of the classical pathway. We found that deletion of the C4 gene does not significantly change either the time of onset or the severity and tempo of myelin oligodendrocyte‐induced EAE compared with controls with a fully intact complement system. We observed similar levels of cellular infiltration (CD11b+ macrophages and CD3+ T cells) and demyelination in the two kinds of mice. Despite this, ribonuclease protection assays demonstrated a two‐ to fourfold increase in several pro‐inflammatory cytokines in C4−/− mice with EAE, including interleukin‐β (IL‐1β), IL‐18, tumor necrosis factor‐α (TNF‐α), IP‐10, and RANTES. These results support the conclusion that the contribution of murine complement to the pathogenesis of demyelinating disease is realized via the alternative pathway. © 2004 Wiley‐Liss, Inc.
Subjective and polysomnographic effects of milnacipran on sleep in depressed patients
Authors: Lemoine Patrick , Faivre Thierry
Published: July 2004

The effects of milnacipran (50 mg bid) on sleep patterns of eight depressed inpatients, treated for 4 weeks, were studied during the initial (days 1–3) and terminal (days 26–28) treatment periods and compared with those obtained from three sleep recordings performed just prior to the initiation of the treatment. The clinical evolution of patients was evaluated weekly using the MADRS depression scale and the Spiegel and Norris sleep scales. Clinical improvement, shown by a mean reduction of 58% in MADRS scale scores, was accompanied by an improvement of disturbed sleep parameters. From the beginning of treatment, there was an increase in the total duration of sleep and stage II sleep, a decrease in sleep latency and an increase in sleep efficiency. Total REM sleep was not modified although, since there was an increase in total sleep time, the percent REM sleep was significantly reduced. REM latency was increased early in the study, an effect classically associated with antidepressant treatment. This study suggests that milnacipran improves disturbed sleep parameters in depressed patients without any additional disturbance at the onset of treatment. Copyright © 2004 John Wiley & Sons, Ltd.
Nicotine improves antisaccade task performance without affecting prosaccades
Authors: Larrison Abigail L. , Briand Kevin A. , Sereno Anne B.
Published: July 2004

Although there is ample evidence for a cognitive‐attentional benefit of the stimulant nicotine, the source of this benefit is not as well understood. One approach is to address what aspects of performance nicotine affects at a functional systems level. It is currently debated whether the benefits produced by nicotine are the effect of enhanced higher cognitive function or reflect an overall increase in general arousal. In order to address this question, the effects of nicotine on two simple eye movement tasks were studied: the saccade (S) and antisaccade (AS) tasks. Because the S and AS tasks utilize identical sensory stimuli (peripheral targets) and require identical motor responses (eye movements) but differ significantly in their cognitive demands, the use of these two tasks should enable a parsing of nicotine effects on cognitive versus sensory‐motor processes. In this study, the S and AS tasks were performed by two experimental groups, task naïve subjects and highly practised subjects. For the first group, that of the task naïve subjects, nicotine gum administration resulted in a decrease in AS errors. For the second group, that of two experienced subjects tested repeatedly over a 3 week period, nicotine also produced a significant decrease in AS task errors, as well as resulting in a significant decrease in AS response times. Neither task naïve nor experienced subjects showed any effects of nicotine on the S task. Examining the effects of nicotine on highly controlled and constrained tasks such as the S and AS task may provide another level of insight into the mechanisms underlying the beneficial cognitive effects of nicotine. Copyright © 2004 John Wiley & Sons, Ltd.
Cytokines: abnormalities in major depression and implications for pharmacological treatment
Authors: O'Brien Sinead M. , Scott Lucinda V. , Dinan Timothy G.
Published: July 2004

The role of cytokines in depression was first considered when the cytokine interferon resulted in ‘sickness behaviour’, the symptoms of which are similar to those of major depression. The latter is associated with an increase in pro‐inflammatory cytokines such as interleukin‐1 (IL‐1), interleukin‐6 (IL‐6) and tumour necrosis factor alpha (TNF‐α). These cytokines are potent modulators of corticotropin‐releasing hormone (CRH) which produces heightened hypothalamic–pituitary–adrenal axis (HPA) activity characterized by increases in ACTH and cortisol, both of which are reported elevated in major depression. Antidepressant treatment has immunomodulatory effects with increases in the production of IL‐10, which is an anti‐inflammatory cytokine. This review based on a Medline search from 1980–2003, focuses on the evidence available of cytokine changes in acute stress, chronic stress and major depression. It examines the effects of antidepressant treatment on immune parameters in both animal models and clinical trials. We suggest that future antidepressants may target the immune system by either blocking the actions of pro‐inflammatory cytokines or increasing the production of anti‐inflammatory cytokines. Copyright © 2004 John Wiley & Sons, Ltd.
Regulation of proliferation and migration in retinoic acid treated C3H10T1/2 cells by TGF‐β isoforms
Authors: Makhijani Nalini S. , Bischoff David S. , Yamaguchi Dean T.
Published: July 2004

Proliferation of mesenchymal precursors of osteogenic and chondrogenic cells and migration of these precursors to repair sites are important early steps in bone repair. Transforming growth factor‐β (TGF‐β) has been implicated in the promotion of bone repair and may have a role in these processes. Three isoforms of TGF‐β, TGF‐β1, ‐β2, and ‐β3, are expressed in fracture healing, however, their specific roles in the repair process are unknown. Differential actions of the TGF‐β isoforms on early events of bone repair were explored in the multipotent mesenchymal precursor cell line, C3H10T1/2. Cell migration was determined using a modified Boyden chamber in response to concentrations of each isoform ranging from 10−12 to 10−9 g/ml. All three isoforms demonstrated a dose‐dependent chemotactic stimulation of untreated C3H10T1/2 cells. Checkerboard assays indicated that all three isoforms also stimulated chemokinesis of the untreated cells. C3H10T1/2 cells treated with all‐trans‐retinoic acid (ATRA) and expressing relatively higher levels of osteoblastic gene markers such as alkaline phosphatase and collagen type I, lower levels of chondrocytic gene markers collagen type II and aggrecan, and unchanged levels of the adipose marker adipsin did not demonstrate significant chemokinesis or chemotaxis in response to TGF‐β1 or ‐β3 at concentrations ranging from 10−12 to 10−9 g/ml. In the ATRA‐treated cells, TGF‐β2 stimulated a significant increase in chemotaxis only at the highest concentration tested. Cell proliferation was assessed by mitochondrial dehydrogenase activity and cell counts at TGF‐β concentrations from 10−11 to 10−8 g/ml. None of the TGF‐β isoforms stimulated cell proliferation in untreated or ATRA‐treated C3H10T1/2 cells. Analysis of TGF‐β receptors (TGF‐βR1, ‐βR2, and ‐βR3) showed a 1.6‐ to 2.8‐fold decrease in mRNA expression of these receptors in ATRA‐treated cells. In conclusion: (1) while all three TGF‐β isoforms stimulate chemotaxis/chemokinesis of multipotent C3H10T1/2 cells, TGF‐β1 and ‐β3 do not stimulate chemotaxis in C3H10T1/2 cells treated with ATRA while TGF‐β2 stimulated chemotaxis only at the highest concentration tested. (2) TGF‐β isoforms do not appear to stimulate cell proliferation in C3H10T1/2 cells in either a multipotent state or after ATRA treatment when expressing higher levels of alkaline phosphatase and collagen type I gene markers. (3) Decrease in mRNA expression for TGF‐βR1, ‐βR2, and ‐βR3 upon ATRA treatment could potentially explain the lack of chemotaxis/chemokinesis in these cells expressing higher levels of alkaline phosphatase and collagen type I. © 2005 Wiley‐Liss, Inc.
Decoupling task and relationship conflict: the role of intragroup emotional processing
Authors: Yang Jixia , Mossholder Kevin W.
Published: July 2004

The present paper focuses on the role of emotion in intragroup conflict processes. We propose that how group members handle emotion affects intragroup interactions and has implications for task and relationship conflict. Three types of variables—collective emotional intelligence, intragroup relational ties, and conflict‐relevant interactional norms—constrain negative emotionality and may determine whether task conflict results in damaging relationship conflict. The moderating influence of these variables is discussed, as are compositional issues associated with measuring them. Copyright © 2004 John Wiley & Sons, Ltd.
The contexts of knowing: natural history of a globally distributed team
Authors: Baba Marietta L. , Gluesing Julia , Ratner Hilary , Wagner Kimberly H.
Published: July 2004

The focus of this paper is cognitive convergence in a globally distributed team (GDT), defined as the process by which cognitive structures of distributed team members gradually become more similar over time. To explore the convergence process, we employed a longitudinal, ethnographic research strategy that allowed us to follow a naturally occurring GDT over a 14‐month period, producing a rich case study portraying factors and processes that influence convergence. Confirming previous studies, we find that increases in shared cognition alone are not sufficient to account for performance gains on a GDT. Rather, it may be necessary not only to increase the sharing of cognition, but also to reverse a pattern of increasing divergence that can result from rejection of key knowledge domains. We also found that several factors influence the process of cognitive convergence beyond direct knowledge sharing. These include: separate but parallel or similar learning experiences in a common context; the surfacing of hidden knowledge at remote sites by third‐party mediators or knowledge brokers; and shifts in agent self‐interest that motivate collaboration and trigger the negotiation of task interdependence. Also relevant to cognitive convergence on a GDT is the geographical distribution pattern of people and resources on the ground, and the different ways in which leaders exploit the historical, cultural and linguistic dimensions of such distribution to further their own political agendas. Several propositions related to these observations are suggested. We conclude that GDTs can be effective in bringing together divergent points of view to yield new organizational capabilities, but such benefits require that leaders and members recognize early and explicitly the existence and validity of their differences. Copyright © 2004 John Wiley & Sons, Ltd.
Integrated manufacturing, empowerment, and company performance
Authors: Patterson Malcolm G. , West Michael A. , Wall Toby D.
Published: July 2004

There is controversy over whether integrated manufacturing (IM), comprising advanced manufacturing technology, just‐in‐time inventory control and total quality management, empowers or deskills shop floor work. Moreover, both IM and empowerment are promoted on the assumption that they enhance competitiveness. We examine these issues in a study of 80 manufacturing companies. The extent of use of IM was positively associated with empowerment (i.e., job enrichment and employee skill enhancement), but, with the minor exception of AMT, bore little relationship with subsequent company performance. In contrast, the extent of empowerment within companies predicted the subsequent level of company performance controlling for prior performance, with the effect on productivity mediating that on profit. Copyright © 2004 John Wiley & Sons, Ltd.
From enterprise to empowerment: the evolution of an Anglo‐American approach to strategic urban economic regeneration
Authors: Lavin Marilyn , Whysall Paul
Published: July 2004

This paper traces the development and evolution of a policy instrument designed to regenerate inner urban areas suffering the effects of long‐term economic decline.

The origins of the Enterprise Zone concept are examined from radical town planning thought to government policy under Margaret Thatcher in Britain in the 1970s and 1980s, and its subsequent reappearance in American urban policy through the 1980s and 1990s, culminating in the concept of Empowerment Zones in the mid‐1990s.

Through this time, shifts occur in the nature and application of the policies and critics are heard on both sides of the Atlantic, as explained here. It is suggested the American experience benefited from its later occurrence in a more favourable economic climate. More recently there is evidence of British policy shifting closer to the evolved form of policy, as has emerged in the United States.

Copyright © 2004 John Wiley & Sons, Ltd.
A Two‐Step Interval and Modified Rosenbrock Method for Kinetic Parameter Estimation in Copolymerization Systems: A Robust and Reliable Approach
Authors: Habibi Ali , Vasheghani‐Farahani Ebrahim
Published: July 2004

Summary: The kinetics of solution free radical copolymerization of isobutyl methacrylate (i‐BMA) and lauryl methacrylate (LMA) in benzene, initiated with 2,2‐azoisobutyronitrile (AIBN) were studied at different monomer feed compositions at low conversion levels. In order to avoid the complications of copolymerization kinetics, the pseudo‐kinetic rate constant method was applied in constant and variable volume polymerization systems. A two‐step procedure based on interval analysis and the modified Rosenbrock method was used to estimate the kinetic parameters of copolymerization. In the first step, initiation, coupled propagation‐termination and transfer rate parameters were determined from steady state kinetic equations using interval analysis. Since the objective function is non‐linear, non‐convex and has multiple local optima, a robust computational technique, based on the Interval Newton/Generalized Bisection (IN/GB) algorithm, was developed to solve this set of non‐linear algebraic equations. This method was used with mathematical and computational guarantees of certainty to find the global optimum. In the second step, the system of mole balance, population balance and moment equations, which are highly stiff ordinary differential equations, were discritized and solved by the modified Rosenbrock method. The results of the first computational step were inserted as an active or equality constraint in the second step to calculate the individual elementary rate parameters of the reaction. Statistical analysis indicated that the copolymer composition is well described by the terminal unit model (TUM), but the implicit penultimate unit effect (IPUE) model of Fukuda and coworkers is more suitable for describing the rate data. In contrast to most previously studied systems, it was found that propagation and coupled rate parameters are greater than those predicted by the TUM.

Variation of number average molecular weight of the copolymer in polymerization system for various initial monomer feed compositions at different reaction times (solid lines are computed results).

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Variation of number average molecular weight of the copolymer in polymerization system for various initial monomer feed compositions at different reaction times (solid lines are computed results).
Current trends in quantitative structure activity relationships on FXa inhibitors: Evaluation and comparative analysis
Authors: Kontogiorgis Christos A. , Hadjipavlou‐Litina Dimitra
Published: July 2004

This article evaluates the quantitative structure activity relationships of FXa inhibitors, using the C‐QSAR program of Biobyte. Diaryloxypyridines, aminophenols, biaryl isoxazoline derivatives, 1,2‐dibenzamidobenzenes, 3‐amidinophenylalanine derivatives, benzoxazinones, naphthoanilides, tetrazoles, glucolic and mandelic acid derivatives were included in this survey. Clog P plays a significant role in the QSAR, especially as hydrophilicity. In the most of the cases, CMR/MR molar refractivity as well as sterimol parameters (B5 and L) are important. Electronic effects with the exception of the Hammett's constant σm, are not found to govern the biological activity. Es was found to be important indicator variables were used after the best model was found to account for the usual structural features. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 6, 687–747, 2004
Challenges and strategies: The immune responses in gene therapy
Authors: Zhou Hai‐sheng , Liu De‐pei , Liang Chih‐chuan
Published: July 2004

The host immune responses, including T lymphocytes mediated immune response and humoral immune responses are the important parts of the challenges in gene therapy. There are some potential immunostimulants in gene delivery systems, such as viral and non‐viral vectors. Viral gene products, transgene products, viral proteins derived from viral particles required by dead‐end infection, and CpG DNA in plasmid may play important roles in inducing the host immune responses when foreign genes are transferred into the targeted tissues. The immune responses should lead to many problems in gene therapy: transient expression of therapeutic gene, non‐efficient re‐administration of the same vectors, and severe side‐effects in clinical trials. Although RNAi may act as gene therapeutic agent for suppression of specific gene expression, little attention has been given to the potential non‐specific effects that might be induced. It was reported that small interfering RNAs (siRNAs) can induce the host interferon response following transfected to mammalian cells. Facing these challenges, a number of studies have been focused on taking measures to solve them, such as immunosuppression, selection of different administration routes and dose of the vectors, using the tissue‐specific promoters and modifying the vectors. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 6, 748–761, 2004
Analysis of finite dimensional approximations to a class of partial differential equations
Authors: Bao Gang , Zhou Aihui
Published: July 2004

In this paper, a unified approach for analysing finite dimensional approximations to a class of partial differential equations boundary value problems (second‐kind Fredholm differential equations) is introduced. The approach is shown to be general despite of its extremely simple form. In particular, it is expected to be useful in the convergence analysis of finite element methods for solving PDE problems. Three specific examples are presented to illustrate the broad applicability of the approach. Copyright © 2004 John Wiley & Sons, Ltd.
The tautomerism of Omeprazole in solution: a 1H and 13C NMR study
Authors: Claramunt Rosa M. , López Concepción , Alkorta Ibon , Elguero José , Yang Rong , Schulman Steve
Published: July 2004

The tautomerism of 5(6)‐methoxy‐2‐{[(4‐methoxy‐3,5‐dimethyl‐2‐pyridinyl)methyl] sulfinyl}‐1H‐benzimidazole (omeprazole) was determined in solution, KT = 0.59 in THF at 195 K, in favor of the 6‐methoxy tautomer. The assignment of the signals was made by comparison with its two N‐methyl derivatives in acetone‐d6 and through theoretical calculations of the absolute shieldings (GIAO/DFT/6‐311++G**). Copyright © 2004 John Wiley & Sons, Ltd.
29/28, 30/28Silicon, 34/32sulfur and 80/77selenium isotope‐induced fluorine chemical shifts through two bonds
Authors: Tordeux Marc , Magnier Emmanuel , Guidotti Jérôme , Diter Patrick , Wakselman Claude
Published: July 2004

Isotope effects on fluorine chemical shifts induced by heteroatoms bonded covalently to a carbon atom bearing fluorine atoms were studied. For each compound, the isotope‐induced chemical shifts 2Δ 19F(X) through two bonds were measured for the heteroatom (X = 29/28Si, 30/28Si, 34/32S and 80/77Se). The 1Δ 19F(13/12C) values for the carbon bonded to the fluorine atoms were also recorded. Examination of the 19F NMR data showed homogeneity of the isotope‐induced chemical shifts along the rows of the periodic table and regularity down the columns (from 10 to 15 ppb per mass unit for the second row to 0.4 ppb for the fourth row). It became negligible for atoms of the fifth row. Copyright © 2004 John Wiley & Sons, Ltd.
Single‐crystal 2H NMR of deuterated 1,10‐decanedicarboxylic acid included in hydrogenated urea channels
Authors: Odin C. , Garcia P.
Published: July 2004

The intergrowth of 1,10‐decanedicarboxylic acid and urea give infinite hydrogen‐bonded chains of the guest included in the hexagonal urea host. A deuterium high‐resolution solid‐state NMR study of the selectively deuterated intergrowth compound 1,10‐decanedicarboxylic acid/hydrogenated urea at variable temperature in the range 90 ≤ T ≤ 300 K was performed on a single crystal. The analysis of the second moment as a function of temperature is shown to be compatible with the known phase transition occurring near Tc = 203 K. Moreover, the spectra indicate that the orientational disorder is strong, and is compared to an axial uniform disorder. For this purpose, the general equation for the second moment of a system with uniform two‐dimensional axial orientational disorder is given, and a method to take into account the non‐uniform excitation of the pulse sequence is proposed. Copyright © 2004 John Wiley & Sons, Ltd.
Selective estrogen receptor modulators protect hippocampal neurons from kainic acid excitotoxicity: Differences with the effect of estradiol
Authors: Ciriza Iratxe , Carrero Paloma , Azcoitia Iñigo , Lundeen Scott G. , Garcia‐Segura Luis M.
Published: July 2004

Neuroprotective effects of estradiol are well characterized in animal experimental models. However, in humans, the outcome of estrogen treatment for cognitive function and neurological diseases is very controversial. Selective estrogen receptor modulators (SERMs) may represent an alternative to estrogen for the treatment or the prevention of neurodegenerative disorders. SERMs interact with the estrogen receptors and have tissue‐specific effects distinct from those of estradiol, acting as estrogen agonists in some tissues and as antagonists in others. In this study we have assessed the effect of tamoxifen, raloxifene, lasofoxifene (CP‐336,156), bazedoxifene (TSE‐424), and 17β‐estradiol on the hippocampus of adult ovariectomized rats, after the administration of the excitotoxin kainic acid. Administration of kainic acid induced the expression of vimentin in reactive astroglia and a significant neuronal loss in the hilus. SERMs did not affect vimentin immunoreactivity in the hilus, while 17β‐estradiol significantly reduced the surface density of vimentin immunoreactive profiles. Estradiol, tamoxifen (0.4–2 mg/kg), raloxifene (0.4–2 mg/kg), and bazedoxifene (2 mg/kg) prevented neuronal loss in the hilus after the administration of kainic acid. Lasofoxifene (0.4–2 mg/kg) was not neuroprotective. These findings indicate that SERMs present different dose‐dependent neuroprotective effects. Furthermore, the mechanisms of neuroprotection by SERMs and estradiol are not identical, because SERMs do not significantly affect reactive gliosis while neuroprotection by estradiol is associated with a strong down‐regulation of reactive astroglia. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2004
Determination of reactivity ratios and kinetics of free radical copolymerization of linalool with styrene
Authors: Shukla Anjali , Srivastava A. K.
Published: July 2004

Copolymerization of acyclic monoterpenoid, namely linalool (LIN), with styrene (STY) initiated by benzoyl peroxide (BPO) p‐acetyl benzylidene triphenyl arsonium ylide (p‐ABTAY) in xylene separately at 80°C for 180 min under inert atmosphere of nitrogen was performed. The results give a nearly alternating copolymer as evidenced from reactivity ratios (r1 = 0.016, r2 = 0.057) w.r.t. BPO; (r1 = 0.017, r2 = 0.052) w.r.t. p‐ABTAY (i.e. r1 = 0.0165 ± 0.0005 and r2 = 0.0545 ± 0.0025 per initiator set) using Kelen–Tudos method. The FT‐IR spectrum shows a band at 3026 cm−1 due to the aromatic ring of polystyrene and an alcoholic band of linalool at 3408 cm−1. 1H‐NMR spectrum shows peaks at δ 7.0–7.7 ppm of OH protons and peaks at δ 7.5–8.0 ppm due to phenyl protons of styrene. The system follows ideal kinetics i.e. Rp ∝ [LIN]1.0[STY]1.0[BPO]0.5/[p‐ABTAY]0.5. The overall energy of activation in the temperature range 75–85°C is 77.0 kJ mol−1 and 90.0 kJ mol−1, respectively. The values for Mark–Houwink constants for the functional copolymer has been evaluated as a = 0.40 and K = 1.60 × 10−4 with the help of gel permeation chromatography (GPC). Alfrey–Price, Q and e parameters for linalool have been evaluated as Q2 = 0.80; e2 = 1.25 w.r.t. BPO and Q2 = 0.90; e2 = 1.54 w.r.t. p‐ABTAY. Thermal properties of copolymers were investigated by thermogravimetric analysis (TGA) techniques. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of bi‐functional photorefractive hyperbranched polyisophthalesters
Authors: Kou Huiguang , Shi Wenfang
Published: July 2004

A series of novel bi‐functional photorefractive (PR) hyperbranched polyisophthalesters (HPIPEs) with pendant end carbazolyl and azo groups, acting as photoconductors and electro‐optic (EO) chromophores, respectively, were synthesized by modifying the HPIPE with N‐hydroxyethyl carbazole and 4‐(p‐nitrophenylazo) (N‐ethoxyl‐N‐methyl)aniline. These obtained PR polymers were then characterized by UV‐vis and IR spectrum, 1H‐NMR, elemental analysis, gel permeation chromatography (GPC) measurements and thermal analysis. As expected, due to their three‐dimension molecular structures, the lower glass transition temperatures (21–49°C) were obtained in the absence of plasticizers, which provide a necessary free volume for the EO chromophores reorientation. The acceptable thermal stability, as well as the degradation temperatures of 205–260°C, was also determined by thermogravimetric analysis (TGA). The two‐beam coupling experiments of HPIPE‐25Azo theoretically containing 25% azo end groups showed that a high gain coefficient of 59 cm−1 was obtained at the applied electric field of 80 V μm−1. Copyright © 2004 John Wiley & Sons, Ltd.
Peripheral blood monocyte count as an aid in optimizing progenitor collection in children
Authors: Strahlendorf Caron , Chan Grace
Published: July 2004

CD34 enumeration, although established as the gold standard for timing peripheral blood progenitor cell harvests, is not always available. We investigated whether the peripheral blood monocyte population could be used to assist in predicting the peak of circulating progenitors for harvesting autologous blood stem cells in children. A retrospective analysis was done on 140 harvests in 40 patients. Cross‐tabulation analysis of peripheral blood CD34 counts and monocyte counts showed a good correlation. We conclude that in the absence of CD34 results, the monocyte count gives a good indication of early marrow regeneration and helps in predicting optimal time for harvest. © 2004 Wiley‐Liss, Inc.
A new method for the extraction of specific interaction enthalpy from the enthalpy of solvation
Authors: Solomonov Boris N. , Novikov Vladimir B. , Varfolomeev Mikhail A. , Mileshko Natalia M.
Published: July 2004

A new, simple method for the extraction of specific interaction enthalpy from the enthalpy of solvation is proposed. It is based on empirical but very general relationships describing the non‐specific solvation enthalpy. The specific interaction enthalpy is calculated from the solution enthalpies in the solvent under consideration, cyclohexane and tetrachloromethane. The solution enthalpy of at least one linear alkane in the solvent must also be available. The solution enthalpies of a ‘model compound’ or homomorph are not required. This method is applicable not only for proton‐donor solutes but also for acceptor solutes such as iodine. It can be used also for solvents associated by hydrogen bonding (e.g. alcohols). The enthalpies of specific interaction for 280 solute–solvent systems were calculated. Solution enthalpy data were mainly obtained from the literature and partially measured by the authors. The results were compared with literature data on complexation enthalpy. Copyright © 2004 John Wiley & Sons, Ltd.
Electron transfer reactivity of methyl‐substituted amine NHn(CH3)3−n/NHn(CH3) (n = 0–3) self‐exchange systems: a theoretical investigation
Authors: Sun Qiao , Bu Yuxiang , Sun Lixiang , Yan Shihai , Cheng Xueli
Published: July 2004

The geometries of NHn(CH3)3−n, NHn(CH3) (n = 0–3) and their corresponding coupling complexes [NHn(CH3)3−n···NHn(CH3) (n = 0–3)] were determined using density functional theory (DFT) and ab initio methods at the 6–311+G* basis set level, and the relative stability is predicted to decrease in the order H3N···NH > CH3H2N···NH2CH > (CH3)2HN···NH(CH3) > (CH3)3N···N(CH3) for the four stable encounter complexes. The inapplicability is also discussed for the DFT methods in predicting the dissociation energy curves especially with long contact distance in which the DFT methods give abnormal behavior for the dissociation of the complexes due to the ‘inverse symmetry breaking’ problem. The contact distance dependences of the activation energy, the coupling matrix element and the electron‐transfer (ET) rate were determined with the MP2/6–311+G* or MP2/6–31G* method. The results show that ET reactions occur chiefly only over a small range of contact distances where the favorable ones are 1.9 Å < RN—N < 4.0 Å for NH3···NH, 2.5 Å < RN—N < 5.0 Å for CH3H2N··· NH2CH, 2.1 Å < RN—N < 5.0 Å for (CH3)2HN···NH(CH3) and 3.2 Å < RN—N < 6.0 Å for (CH3)3N··· N(CH3) coupling systems. The most optimum contact distances for the above four coupling systems are 2.4, 3.0, 2.7 and 3.7 Å where the corresponding maximum ET rates are 2.53 × 105 s−1(H3N···NH), 1.16 × 103 s−1(CH3H2N···NH2CH), 7.55 × 10−3 s−1 [(CH3)2HN···NH(CH3)] and 2.25 × 10−4 s−1 [(CH3)3N··· N(CH3)], respectively, and the corresponding maximum ET rate order is H3N···NH > CH3H2N··· NH2CH > (CH3)2HN···NH(CH3) > (CH3)3N···N(CH3). Increasing substituents on the active N centers may significantly change the ET rate and other kinetic parameters. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of the particle size distribution on the low shear viscosity of high‐solid‐content latexes
Authors: Do Amaral Marcelo , Van Es Steven , Asua José M.
Published: July 2004

The production of high‐solid‐content, low‐viscosity latexes is an active field in both industry and academia. The viscosity of polymer dispersions has a clear dependence on the particle size distribution (PSD). An example is the rule of thumb that a bimodal PSD enables the reduction of the viscosity with respect to monomodal systems. Despite important progress in theoretical work, not much has been done to quantitatively predict the low shear viscosity of aqueous polymer dispersions as a function of the complex PSD. In this work, the capability of a low‐shear‐viscosity equation to quantitatively account for the influence of both the PSD and the physicochemical characteristics of the dispersions is experimentally assessed. An analysis, consistent with theoretical concepts, of the data with semiempirical correlations is proposed. Next, with values of the parameters of the viscosity equation obtained experimentally, the effect of a latex with a 70% solid content on the low shear viscosity is examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3936–3946, 2004
Tsp36, a tapeworm small heat‐shock protein with a duplicated α‐crystallin domain, forms dimers and tetramers with good chaperone‐like activity
Authors: Kappé Guido , Aquilina J. Andrew , Wunderink Lisa , Kamps Bram , Robinson Carol V. , Garate Teresa , Boelens Wilbert C. , de Jong Wilfried W.
Published: July 2004

Small heat shock proteins (sHSPs), which range in monomer size between 12 and 42 kDa, are characterized by a conserved C‐terminal α‐crystallin domain of 80–100 residues. They generally form large homo‐ or heteromeric complexes, and typically have in vitro chaperone‐like activity, keeping unfolding proteins in solution. A special type of sHSP, with a duplicated α‐crystallin domain, is present in parasitic flatworms (Platyhelminthes). Considering that an α‐crystallin domain is essential for the oligomerization and chaperone‐like properties of sHSPs, we characterized Tsp36 from the tapeworm Taenia saginata. Both wild‐type Tsp36 and a mutant (Tsp36C→R) in which the single cysteine has been replaced by arginine were expressed and purified. Far‐UV CD measurements of Tsp36 were in agreement with secondary structure predictions, which indicated α‐helical structure in the N‐terminal region and the expected β‐sandwich structure for the two α‐crystallin domains. Gel permeation chromatography and nano‐ESI‐MS showed that wild type Tsp36 forms dimers in a reducing environment, and tetramers in a non‐reducing environment. The tetramers are stabilized by disulfide bridges involving a large proportion of the Tsp36 monomers. Tsp36C→R exclusively occurs as dimers according to gel permeation chromatography, while the nondisulfide bonded fraction of wild type Tsp36 dissociates from tetramers into dimers under nonreducing conditions at increased temperature (43°C). The tetrameric form of Tsp36 has a greater chaperone‐like activity than the dimeric form. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Molecular modeling of the core of Aβ amyloid fibrils
Authors: Guo Jun‐tao , Wetzel Ronald , Xu Ying
Published: July 2004

Amyloid fibrils, a key pathological feature of Alzheimer's disease (AD) and other amyloidosis implicated in neurodegeneration, have a characteristic cross‐β structure. Here we present a structural model for the core of amyloid fibrils formed by the Aβ peptide using computational approaches and experimental data. Aβ(15–36) was threaded against the parallel β‐helical proteins. Our multi‐layer model was constructed using the top scoring template 1lxa, a left‐handed parallel β‐helical protein. This six‐rung helical model has in‐register repeats of the Aβ(15–36) sequence. Each rung has three β‐strands separated by two turns. The model was tested using molecular dynamics simulations in explicit water, and is in good agreement with a number of experimental observations. In addition, a model based on right‐handed helical proteins is also described. The core structural model described here might serve as the building block of the Aβ(1–40) amyloid fibril as well as some other amyloid fibrils. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Methods for electronic‐structure calculations: Overview from a reduced‐density‐matrix point of view
Authors: Ziesche P. , Tasnádi F.
Published: July 2004

The methods of quantum chemistry and solid state theory to solve the many‐body problem are reviewed. We start with the definitions of reduced density matrices, their properties (contraction sum rules, spectral resolutions, cumulant expansion, and N‐representability), and their determining equations (contracted Schrödinger equations), and we summarize recent extensions and generalizations of the traditional quantum chemical methods, of the density functional theory, and of the quasiparticle theory: from finite to extended systems (incremental method), from density‐to‐density matrix (density matrix functional theory), from weak to strong correlation (dynamical mean field theory), from homogeneous (Kimball–Overhauser approach) to inhomogeneous and finite systems. Measures of the correlation strength are discussed. The cumulant two‐body reduced density matrix proves to be a key quantity. Its spectral resolution contains geminals, possibly the solutions of an approximate effective two‐body equation, and we sketch the idea of how its contraction sum rule can be used for a variational treatment. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004