bluuebunny/crossref_metadata_2025 huggingface dataset:
Helicobacter pylori Infection Negatively Influences Pregnancy Outcome in a Mouse Model
Authors: Rossi Giacomo , Romagnoli Stefano , Lauretti Laura , Pancotto Laura , Taccini Ennio , Rappuoli Rino , Del Giudice Giuseppe , Ruggiero Paolo
Published: April 2004

Background.  Helicobacter pylori infects the human stomach, causing gastritis, peptic ulcer, and gastric cancer. H. pylori infection has also been related to extra‐gastric disorders. We investigated whether H. pylori infection can influence pregnancy in a murine model.

Methods.  Female CD1 mice were infected with the H. pylori SPM326 strain before mating, and then assessed throughout pregnancy for embryo/fetus characteristics and histopathological changes of the endometrium.

Results.  Infected mice showed higher numbers of resorption and lower fetal weights than noninfected controls. These pathological phenomena were accompanied by macrophage activation, and increases both of CD4+ and CD8+ lymphocytes and of interferon‐γ and major histocompatibility complex class II expression at the endometrial level, as evaluated by immunohistochemistry.

Discussion.  During pregnancy, preferential induction of Th2‐type cytokines downregulates Th1‐type responses, allowing fetal survival. Our results suggest that H. pylori infection can induce activation of resident uterine immune cells and/or recruitment of cells at the endometrial level. It can be hypothesized that the local Th1‐type response induced by H. pylori infection could alter the systemic Th1/Th2‐type cytokine balance at sites under particular physiopathological conditions of active tissue and/or vascular formation, such as pregnancy.

Conclusions.  This is the first evidence in an animal model of the possible influence of H. pylori infection on pregnancy. Further work is required on its mechanism and its relevance for humans.
The Influence of Lactobacillus brevis on Ornithine Decarboxylase Activity and Polyamine Profiles in Helicobacter pylori‐Infected Gastric Mucosa
Authors: Linsalata Michele , Russo Francesco , Berloco Pasquale , Caruso Maria Lucia , Matteo Giovanni D.I. , Cifone Maria Grazia , Simone Claudio D.E. , Ierardi Enzo , Leo Alfredo Di
Published: April 2004

Background.  Functional probiotics may prevent Helicobacter pylori infection, and some evidence suggests that they also possess antitumor properties. Lactobacillus brevis (CD2) is a functional Lactobacillus strain with peculiar biochemical features, essentially related to the activity of arginine deiminase. This enzyme catalyzes the catabolism of arginine and affects the biosynthesis of polyamines (putrescine, spermidine, and spermine). Polyamines are polycations found in high concentrations in both normal and neoplastic cells. Our aims were: 1, to assess whether oral administration of L. brevis (CD2) affects H. pylori survival in the human gastric mucosa; 2, to evaluate the effects of L. brevis (CD2) on polyamine biosynthesis in gastric biopsies from H. pylori‐positive patients.

Materials and Methods.  For 3 weeks before endoscopy, 22 H. pylori‐positive dyspeptic patients randomly received (ratio 1 : 1) high oral doses of L. brevis (CD2) or placebo. Before and after treatment, H. pylori infection was determined by urea breath test (UBT). In gastric biopsies, ornithine decarboxylase activity and polyamine levels were, respectively, evaluated by a radiometric technique and high‐pressure liquid chromatography (HPLC).

Results.  L. brevis (CD2) treatment did not eradicate H. pylori. However, a reduction in the UBT delta values occurred, suggesting a decrease in intragastric bacterial load. Significantly, L. brevis (CD2) induced a decrease in gastric ornithine decarboxylase activity and polyamine levels.

Conclusions.  Our data support the hypothesis that L. brevis (CD2) treatment decreases H. pylori colonization, thus reducing polyamine biosynthesis. Alternatively, the arginine deiminase activity following L. brevis (CD2) administration might cause arginine deficiency, preventing polyamine generation from gastric cells.
Mechanism of Action of Low Recurrence of Gastritis Caused by Helicobacter pylori with the Type II Urease B Gene
Authors: Badruzzaman Md. , Matsui Hidetaka , Fazle Akbar Sk. Md. , Matsuura Bunzo , Onji Morikazu
Published: April 2004

Background.  Low recurrence of gastritis is seen in patients infected with Helicobacter pylori carrying the type II urease B gene, compared with H. pylori carrying types I and III. The underlying mechanism has been studied in terms of the urease activity and interleukin (IL)‐8 production capacity of different strains of H. pylori.

Materials and Methods.  Forty‐five patients infected with different strains of H. pylori (type I; 15, type II; 15 and type III; 15) were enrolled in the study. H. pylori was isolated from gastric mucosa and cultured in the presence of urea at pH 5.5 to evaluate urease activity. The capacity of different strains of H. pylori to induce IL‐8 mRNA and IL‐8 from a human gastric cancer cell line and human peripheral blood mononuclear cells was evaluated.

Results.  The urease activity of type II H. pylori[523 ± 228 µg of ammonia/dl/108 colony‐forming units (CFU)/ml] was significantly lower than that of type I (1355 ± 1369 µg of ammonia/dl/108 CFU/ml) and type III (1442 ± 2229 µg of ammonia/dl/108 CFU/ml) (p < .05). Gastric cancer cells cocultured with type II H. pylori produced lower levels of IL‐8 mRNA compared with type I and type III H. pylori. The levels of IL‐8 were also significantly lower in cultures induced by type II H. pylori compared with those induced by type I and type III H. pylori. Peripheral blood mononuclear cells also produced lower levels of IL‐8 when cocultured with type II compared with type I H. pylori.

Conclusions.  These results indicate that both the lower level of urease activity and the low IL‐8‐inducing capacity of type II H. pylori might underlie the lower recurrence rate of gastritis caused by type II H. pylori.
Divine Gifts to the Secular Desert
Authors: Rowland Tracey
Published: April 2004

Being Reconciled: Ontology and Pardon, John Milbank, Routledge 2003 (0‐415‐30525‐x), pp. xiii +242, Pb £17.99, Hb £55
Theology as Critical Conversation
Authors: Brown Malcolm
Published: April 2004

Marginalization, John Atherton, SCM Press 2003 (0‐334‐02919‐8), pp. xiii + 210, Pb £14.99
CD29 integrin‐ and LIMK1/cofilin‐mediated actin reorganization regulates the migration of haematopoietic progenitor cells underneath bone marrow stromal cells
Authors: Konakahara Shu , Ohashi Kazumasa , Mizuno Kensaku , Itoh Katsuhiko , Tsuji Takashi
Published: April 2004

Migration and successive homing of haematopoietic stem/progenitor cells (HS/PCs) into haematopoietic microenvironments are critical to their proliferation and differentiation. To investigate molecular mechanisms underlying HS/PC migration, we used a human erythroleukaemia (HEL) cell line which has been characterized as a haematopoietic progenitor cell line and displays high migratory properties underneath the haematopoietic‐supportive stromal cell line, HESS‐M28. HEL cell migration is mediated by the adhesion of the CD29 integrin on HEL cells to HESS‐28 cells which leads to the localization of filamentous actin and formation of cell polarity at membrane protrusions via actin cytoskeleton reorganization. HEL cell migration is inhibited by both dominant negative forms of the Rho‐GTPase family members and a cell permeable inhibitor of LIMK1, S3 peptide. Expression of constitutively active‐ or inactive‐forms of cofilin also inhibits HEL cell migration and phosphorylated cofilin is localized to the front protrusions of HEL cells. These results suggest that cytoskeleton reorganization mediated by a Rho‐GTPase/LIMK1/cofilin pathway plays a critical role in the migration of HEL cells underneath HESS‐M28 cells.
Dissociation of raptor from mTOR is a mechanism of rapamycin‐induced inhibition of mTOR function
Authors: Oshiro Noriko , Yoshino Ken‐ichi , Hidayat Sujuti , Tokunaga Chiharu , Hara Kenta , Eguchi Satoshi , Avruch Joseph , Yonezawa Kazuyoshi
Published: April 2004

The mammalian target of rapamycin (mTOR) is a Ser/Thr protein kinase that plays a crucial role in a nutrient‐sensitive signalling pathway that regulates cell growth. TOR signalling is potently inhibited by rapamycin, through the direct binding of a FK506‐binding protein 12 (FKBP12)/rapamycin complex to the TOR FRB domain, a segment amino terminal to the kinase catalytic domain. The molecular basis for the inhibitory action of FKBP12/rapamycin remains uncertain. Raptor (regulatory associated protein of mTOR) is a recently identified mTOR binding partner that is essential for mTOR signalling in vivo, and whose binding to mTOR is critical for mTOR‐catalysed substrate phosphorylation in vitro. Here we investigated the stability of endogenous mTOR/raptor complex in response to rapamycin in vivo, and to the direct addition of a FKBP12/rapamycin complex in vitro. Rapamycin diminished the recovery of endogenous raptor with endogenous or recombinant mTOR in vivo; this inhibition required the ability of mTOR to bind the FKBP12/rapamycin complex, but was independent of mTOR kinase activity. Rapamycin, in the presence of FKBP12, inhibited the association of raptor with mTOR directly in vitro, and concomitantly reduced the mTOR‐catalysed phosphorylation of raptor‐dependent, but not raptor‐independent substrates; mTOR autophosphorylation was unaltered. These observations indicate that rapamycin inhibits mTOR function, at least in part, by inhibiting the interaction of raptor with mTOR; this action uncouples mTOR from its substrates, and inhibits mTOR signalling without altering mTOR's intrinsic catalytic activity.
Critical role for chicken Rad17 and Rad9 in the cellular response to DNA damage and stalled DNA replication
Authors: Kobayashi Masahiko , Hirano Atsushi , Kumano Tomoyasu , Xiang Shuang‐Lin , Mihara Keiko , Haseda Yasunari , Matsui Osamu , Shimizu Hiroko , Yamamoto Ken‐ichi
Published: April 2004

The Rad17‐replication factor C (Rad17‐RFC) and Rad9‐Rad1‐Hus1 complexes are thought to function in the early phase of cell‐cycle checkpoint control as sensors for genome damage and genome replication errors. However, genetic analysis of the functions of these complexes in vertebrates is complicated by the lethality of these gene disruptions in embryonic mouse cells. We disrupted the Rad17 and Rad9 loci by gene targeting in the chicken B lymphocyte line DT40. Rad17−/− and Rad9−/− DT40 cells are viable, and are highly sensitive to UV irradiation, alkylating agents, and DNA replication inhibitors, such as hydroxyurea. We further found that Rad17−/− and Rad9−/− but not ATM−/− cells are defective in S‐phase DNA damage checkpoint controls and in the cellular response to stalled DNA replication. These results indicate a critical role for chicken Rad17 and Rad9 in the cellular response to stalled DNA replication and DNA damage.
Physiological tolerance, climate change, and a northward range shift in the spittlebug, Philaenus spumarius
Authors: Karban Richard , Strauss Sharon Y.
Published: April 2004

Abstract.  1. Considerable evidence indicates that the Earth's climate has warmed over the past 20 years and most models predict that this process will continue or accelerate. Previous studies involving butterflies and other species have shown that ranges have shifted towards the poles although the mechanisms responsible for these range shifts have not been demonstrated conclusively.

2. Here it is reported that the range of the meadow spittlebug has moved northward along the California coast since 1988.

3. Survival and reproduction of this species in previous laboratory experiments were very sensitive to humidity and temperature. Small deviations from optimal conditions resulted in high mortality.

4. These laboratory results were corroborated by annual field censuses from one location since 1983 in which population densities of spittlebug nymphs were positively correlated with summer humidity and negatively correlated with temperature deviations from the published optimum. Thus it is shown that there are strong links between physiological tolerance and a geographic range shift associated with climatic change.
Queen lifespan and colony longevity in the antHarpegnathos saltator
Authors: Liebig Jürgen , Poethke Hans‐Joachim
Published: April 2004

Abstract. 1. The longevity of field colonies was investigated in the ponerine antHarpegnathos saltator(Jerdon) in which either reproductive workers (gamergates) or a single queen reproduce.

2. Data from 3 years were used to calculate the ratio between queen‐right (n = 50) and gamergate (n = 12) colonies that can be used to derive the colony mortality of gamergate colonies. Using the survival rates of queens in the laboratory, extrinsic and intrinsic mortality rates of queen‐right colonies were calculated.

3. No significant differences in the sizes of queen‐right and gamergate colonies above 14 workers was found, suggesting that mortality of established colonies is not size related.

4. The mortality of gamergate colonies is 4.17 times higher than the intrinsic mortality of queen‐right colonies.

5. In the laboratory, mean survival time of queens in colonies of more than 14 workers was 1.79 years.

6. Estimated mean survival time of queen‐right and gamergate colonies in the field varies between 0.78 and 0.43 years respectively, when no costs of conflict during the replacement of queens occur; however, when the latter costs increase colony mortality to a level similar to extrinsic mortality, the calculated longevity of queen‐right colonies would increase to 1.02 years.
Plant‐attracted ants affect arthropod community structure but not necessarily herbivory
Authors: Mody Karsten , Linsenmair K. Eduard
Published: April 2004

Abstract. 1. The effectiveness of ants as plant defenders is equivocal for plants that attract ants via extrafloral nectaries (EFNs).

2. This study focused on the myrmecophilic savannah treePseudocedrela kotschyithat attracts ants to EFNs and on the arthropod fauna associated withP. kotschyi. Herbivory and arthropod community composition were compared between trees that were dominated by one of three congeneric ant species,Camponotus acvapimensis,C. rufoglaucus, andC. sericeus, and between trees where ants were experimentally excluded and untreated control trees.

3. Short‐term ant‐exclusion experiments failed to demonstrate a consistent effect of ants on herbivory.

4. Plants dominated by different ant species differed significantly in leaf damage caused by herbivorous insects. The relative ranking of herbivory levels of the trees dominated by different ant species was persistent in three consecutive years.

5. Ants significantly reduced the abundance of different arthropod groups (Araneae, Blattodea, Coleoptera, Homoptera, non‐ant Hymenoptera). Other groups, including important herbivores, seemed not to be affected (Lepidoptera, Orthoptera, Thysanoptera, Heteroptera).

6. The study suggests that the presence of ants only benefits plants when specific ant species are attracted, and protection by these ants is not counterbalanced by their negative effect on other beneficial arthropods.
Informal carers’ experience of caring for stroke survivors
Authors: Smith Lorraine N. , Lawrence Maggie , Kerr Susan M. , Langhorne Peter , Lees Kennedy R.
Published: April 2004

Background.  Stroke is the third most common cause of death in industrialized countries and a major cause of adult disability. However, the burden of caring for stroke survivors usually rests with family members who have neither chosen nor volunteered for the role of ‘carer’.

Aims.  This paper reports on a study which aimed to describe the experience of caring for a stroke survivor at one year after stroke in Scotland.

Study design.  Semi‐structured, taped interviews were conducted with 90 carers of stroke survivors one year after stroke and the data analysed using NUD*IST. The interviews were part of a larger study, which included the administration of a range of valid and reliable multidimensional instruments to both carers and stroke survivors. The interview prompt schedule had been developed and tested in a previous study.

Findings.  Although a medical emergency, stroke was not always diagnosed or treated as such by either the public or general practitioners. Initially most carers found that they lacked the knowledge and skills to care for the stroke survivor at home and so they had to learn how to obtain the information and assistance required. Carers had to adapt to the changes that stroke effected in the stroke survivor and seek alternative ways of securing the resources they needed for managing their lives. They thought that they had not been prepared adequately for the caring role or assessed satisfactorily in terms of whether they could manage given their skill level, age and/or health status.

Conclusions.  A public health campaign to educate and inform that stroke is a medical emergency is required if stroke disability is to be minimized. The use of new technologies should be considered in facilitating carers’ learning how to care. There is a need to test alternative models of stroke follow‐up in multi‐centre studies that are holistic and place the carer‐stroke survivor at the centre of care.
The postmodern heart: war veterans’ experiences of invasive cardiac technology
Authors: Anderson Carole C.
Published: April 2004

Background.  The consequences of war and medical discourse have historical connections to pacemaker technology. Understanding these consequences is important because war veterans, medicine and cardiac technology have a shared history that continues into the present. The incidence of Australian war veterans needing cardiac pacemakers has increased many‐fold in recent years, due to advancing age. This need was recognized by the Australian Department of Veteran Affairs and a cardiac programme was established in the veteran hospital that was the setting for this study.

Aim.  This paper reports on a study aimed at capturing the interest and sensitizing the practice of nurses involved in the care of war veterans and other health care consumers who have been diagnosed as requiring a cardiac pacemaker. The study sought to answer the question, ‘How does the war veteran experience his body in relation to invasive cardiac technology?’.

Method.  The research was guided by the principles of interpretive interactionism, and used unstructured interviews with eight male war veterans. The data were collected in 2000.

Findings.  Thematic and content analysis revealed five themes: emotional knowing; the medical encounter; belief in the myth of miracle; technological constraint; and the altered heart. The findings indicated that the human dimension was characterized by experiences of ambivalence, inner conflict, powerlessness and suffering.

Conclusion.  Nursing is at the interface of science and patient care, and this study contributes to nursing knowledge by focusing on a previously unresearched topic, namely embodied interactions between war veterans and invasive cardiac pacemakers. Within a highly technical area such as cardiology, nurses can still work around the technology and keep patients as their primary focus, thus promoting quality care. A humanistic rather than a technological focus locates nurses between patients and cardiac technology. In this in‐between location, nurses are not an extension of cardiac technology but a valuable source of information, education, and counselling.
Translation and validation of the Nursing Outcomes Classification labels and definitions for acute care nursing in Iceland
Authors: Gudmundsdottir Elisabet , Delaney Connie , Thoroddsen Asta , Karlsson Thorlakur
Published: April 2004

Background.  The Nursing Outcomes Classification (NOC), second edition, consists of 260 patient outcomes with definitions. This has been translated into five languages, but has not been clinically validated outside the United States of America (USA).

Aim.  The aim of this paper is to describe the translation of the labels and definitions from the NOC, second edition from English to Icelandic and validation for acute‐care nursing in Iceland.

Method.  A survey that has been designed to identify nurses’ perception of the percentage of patients’ for whom each NOC outcome is relevant in clinical nursing practice was used for clinical validation in this study. The translation procedure involved source to target language translation, parallel comparison, pilot test and field test. Validation included test–retest to measure the reliability for each of the 260 outcome variables. Data collected from 140 clinical nurses from 54 departments within 13 nursing specialties at Landspitali University‐Hospital in Iceland, in November 2001, were analysed to establish construct validity by confirmatory factor analysis. Internal consistency was calculated.

Results.  Translation was successful. Test–retest showed that 181 of the 260 NOC outcomes were significant (P < 0·05) and moderately or highly correlated (r > 0·50) (Pearson's correlation). The confirmatory factor analysis showed that 22 of the 29 NOC classes had only one factor at the loading criteria ≥0·30. Of the 260 outcomes, 244 had loading on one factor (≥0·30) within its class. Internal consistency was >0·80 (Cronbach's alpha).

Limitations.  Low response rate was a limitation. The indicators of each NOC outcome were not addressed.

Conclusion.  The Icelandic version of the NOC survey is a comprehensive tool that can be applied to nursing in acute‐care for research purposes as well as to prepare for the implementation of NOC in clinical information systems.
Involving older people in intermediate care
Authors: Andrews JoyAnn , Manthorpe Jill , Watson Roger
Published: April 2004

Background.  Intermediate care has become a crucial part of the United Kingdom government's programme for improving services for older people. Older people comprise a substantial part of the user base for these services, and it is increasingly recognized that there is a need for greater user involvement in service development for intermediate care. National initiatives undertaken in intermediate care have sought to widen and deepen the remit of such services, and in this way promote greater independence and improved quality of care for older people. In particular, the government has set out clear plans for reshaping services for older people in the National Health Service Plan and the rationale for greater involvement of older people in service development. This article considers ways in which these national and local objectives may be achieved and considers some of the implications for nursing.

Aim.  This paper aims to explore the concept of intermediate care and to identify trends and existing evidence of user involvement in care. In this way it charts a possible way forward for the development of a more ‘user sensitive’ approach.

Method.  The following databases were searched: Medline, Cochrane Library, the Social Science Citation Index and CINAHL. Key words were ‘intermediate care’, ‘older people’, ‘formal care’, ‘primary care’, ‘social services’ and ‘geriatrics’, used in combination.

Findings.  The findings from this study indicate that there is considerable scope for increased user involvement in service development for intermediate care. Such challenges may be more effectively met through greater clarity of the concept of intermediate care, and a bridging of user involvement at the practice and policy levels. Nurses are key providers of intermediate care in the community.

Conclusions.  The involvement of older people in intermediate care service development must be premised on a shared comprehension of the purpose and function of intermediate care. Nurses must be involved in shifting intermediate care from being service‐focused to patient‐centred. Effective participation eschews the application of global constructs for older people, while supporting greater participation at all levels and robust implementation processes.
Concept mapping your Web searches: a design rationale and Web‐enabled application
Authors: Lee Y.‐J.
Published: April 2004

Although it has become very common to use World Wide Web‐based information in many educational settings, there has been little research on how to better search and organize Web‐based information. This paper discusses the shortcomings of Web search engines and Web browsers as learning environments and describes an alternative Web search environment that combines a concept mapping and a data mining technique to address their drawbacks.
Designing learning objects that afford learners the experience of important variations in Chinese characters
Authors: Lam H. C. , Ki W. W. , Chung A. L. S. , Ko P. Y. , Lai A. C. Y. , Lai S. M. S. , Chou P. W. Y. , Lau E. C. C.
Published: April 2004

Effective teaching should focus the attention of learners to its essential aspects. It follows that instructional software can be designed in such a way that allows learners to experience the important variations in the critical aspects of the content to be learned. This paper reports on the experience of designing such special kinds of instructional learning objects for the learning of Chinese characters. The design of these learning objects takes into consideration not only what Chinese characters are all about but also how learners commonly make errors while they learn to write the characters. Out of the analysis of these learners' errors, variations in the structural features of Chinese characters were pulled out and embodied in the design of the learning objects. Learners tinkering with the learning objects can thus implicitly develop a sense of the structural features or regularity of Chinese characters, which most importantly should prepare the learners to learn more new characters in the future. The main proposal of this paper is the notion of this variation‐affording instructional software that allows learners to attend to the essential aspects of what is to be learned. Furthermore, the idea of the learning object also differs from other instructional software in its small, self‐contained and reusable nature, such that teachers can flexibly embed the learning objects into their own teaching materials.
Increasing interactivity in lectures using an electronic voting system
Authors: Draper S. W. , Brown M. I.
Published: April 2004

An overview of the experience of the opening two years of an institution‐wide project in introducing electronic voting equipment for lectures is presented. Eight different departments and a wide range of group size (up to 300) saw some use. An important aspect of this is the organizational one of addressing the whole institution, rather than a narrower disciplinary base. The mobility of the equipment, the generality of the educational analysis, and the technical support provided contributed to this. Evaluations of each use identified (formatively) the weakest spots and the most common benefits, and also (summatively) showed that learners almost always saw this as providing a net benefit to them. Various empirical indications support the theoretical view that learning benefits depend upon putting the pedagogy (not the technology) at the focus of attention in each use. Perceived benefits tended to increase as lecturers became more experienced in exploiting the approach. The most promising pedagogical approaches appear to be Interactive Engagement (launching peer discussions), and Contingent Teaching – designing sessions not as fixed scripts but to zero in on using diagnostic questions on the points that the particular audience most needs on this occasion.
13C‐, 15N‐ and 31P‐NMR studies of oxidized and reduced low molecular mass thioredoxin reductase and some mutant proteins
Authors: Eisenreich Wolfgang , Kemter Kristina , Bacher Adelbert , Mulrooney Scott B. , Williams Charles H. , Müller Franz
Published: April 2004

Thioredoxin reductase (TrxR) from Escherichia coli, the mutant proteins E159Y and C138S, and the mutant protein C138S treated with phenylmercuric acetate were reconstituted with [U‐13C17,U‐15N4]FAD and analysed, in their oxidized and reduced states, by 13C‐, 15N‐ and 31P‐NMR spectroscopy. The enzymes studied showed very similar 31P‐NMR spectra in the oxidized state, consisting of two peaks at −9.8 and −11.5 p.p.m. In the reduced state, the two peaks merge into one apparent peak (at −9.8 p.p.m.). The data are compared with published 31P‐NMR data of enzymes closely related to TrxR. 13C and 15N‐NMR chemical shifts of TrxR and the mutant proteins in the oxidized state provided information about the electronic structure of the protein‐bound cofactor and its interactions with the apoproteins. Strong hydrogen bonds exist between protein‐bound flavin and the apoproteins at C(2)O, C(4)O, N(1) and N(5). The N(10) atoms in the enzymes are slightly out of the molecular plane of the flavin. Of the ribityl carbon atoms C(10α,γ,δ) are the most affected upon binding to the apoprotein and the large downfield shift of the C(10γ) atom indicates strong hydrogen bonding with the apoprotein. The hydrogen bonding pattern observed is in excellent agreement with X‐ray data, except for the N(1) and the N(3) atoms where a reversed situation was observed. Some chemical shifts observed in C138S deviate considerably from those of the other enzymes. From this it is concluded that C138S is in the FO conformation and the others are in the FR conformation, supporting published data. In the reduced state, strong hydrogen bonding interactions are observed between C(2)O and C(4)O and the apoprotein. As revealed by the 15N chemical shifts and the N(5)H coupling constant the N(5) and the N(10) atom are highly sp3 hybridized. The calculation of the endocyclic angles for the N(5) and the N(10) atoms shows the angles to be ≈ 109°, in perfect agreement with X‐ray data showing that the flavin assumes a bent conformation along the N(10)/N(5) axis of the flavin. In contrast, the N(1) is highly sp2 hybridized and is protonated, i.e. in the neutral state. Upon reduction of the enzymes, the 13C chemical shifts of some atoms of the ribityl side chain undergo considerable changes also indicating conformational rearrangements of the side‐chain interactions with the apoproteins. The chemical shifts between native TrxR and C138S are now rather similar and differ from those of the two other mutant proteins. This strongly indicates that the former enzymes are in the FO conformation and the other two are in the FR conformation. The data are discussed briefly in the context of published NMR data obtained with a variety of flavoproteins.
MAP2 prevents protein aggregation and facilitates reactivation of unfolded enzymes
Authors: Sarkar Taradas , Mitra Gopa , Gupta Suvroma , Manna Tapas , Poddar Asim , Panda Dulal , Das Kali P. , Bhattacharyya Bhabatarak
Published: April 2004

It is well established that in addition to its functional role in cell motility, cell division and intracellular transport, cytoskeletal protein tubulin also possesses significant chaperone‐like activity. In vitro studies from our laboratory showed that dimeric tubulin can prevent stress induced aggregation of substrate proteins, can resist thermal deactivation of enzymes and can also refold enzymes from their fully denatured state [Manna, T., Sarkar, T., Poddar, A., Roychowdhury, M., Das, K.P. & Bhattacharyya, B. (2001) J. Biol. Chem.276, 39742–39747]. Negative charges of the C‐termini of both subunits of tubulin are essential for this chaperone‐like property as the deletion of only β‐C‐terminus or the binding of a 14‐residue basic peptide P2 to the α‐C‐terminus completely abolishes this property [Sarkar, T., Manna, T., Bhattacharyya, S., Mahapatra, P., Poddar, A., Roy, S., Pena, J., Solana, R., Tarazona, R. & Bhattacharyya, B. (2001) Proteins Struct. Funct. Genet.44, 262–269]. Based on these results, one would expect that the microtubular proteins (MTP, tubulin with microtubular‐associated proteins, i.e. MAPs bound to the C‐terminus) should not possess any chaperone‐like activity. To our surprise we noticed excellent chaperone‐like activity of MTP. MTP prevents chemical and thermal aggregation of other proteins and can enhance the extent of refolding of fully unfolded substrate enzymes. Because MTP contains tubulin as well as several MAPs bound to the C‐termini of tubulin, we fractionated and purified microtubular associated protein 2 (MAP2) and tau using phosphocellulose chromatography. Experiments with purified proteins demonstrated that it is the MAP2 of MTP that exhibits significant chaperone‐like activity. This has been shown by the prevention of dithiothreitol‐induced aggregation of insulin, thermal aggregation of alcohol dehydrogenase and regain of enzymatic activity during refolding of unfolded substrates. Tau, which shares a homologous C‐terminal domain with MAP2, possesses no such activity.
S ‐Stereoselective piperazine‐2‐tert‐butylcarboxamide hydrolase from Pseudomonas azotoformans IAM 1603 is a novel l‐amino acid amidase
Authors: Komeda Hidenobu , Harada Hiroyuki , Washika Shingo , Sakamoto Takeshi , Ueda Makoto , Asano Yasuhisa
Published: April 2004

An amidase acting on (R,S)‐piperazine‐2‐tert‐butylcarboxamide was purified from Pseudomonas azotoformans IAM 1603 and characterized. The enzyme acted S‐stereoselectively on (R,S)‐piperazine‐2‐tert‐butylcarboxamide to yield (S)‐piperazine‐2‐carboxylic acid. N‐terminal and internal amino acid sequences of the enzyme were determined. The gene encoding the S‐stereoselective piperazine‐2‐tert‐butylcarboxamide amidase was cloned from the chromosomal DNA of the strain and sequenced. Analysis of 2.1 kb of genomic DNA revealed the presence of two ORFs, one of which (laaA) encodes the amidase. This enzyme, LaaA is composed of 310 amino acid residues (molecular mass 34 514 Da), and the deduced amino acid sequence exhibits significant similarity to hypothetical and functionally characterized proline iminopeptidases from several bacteria. The laaA gene modified in the nucleotide sequence upstream from its start codon was overexpressed in Escherichia coli. The activity of the recombinant LaaA enzyme in cell‐free extracts of E. coli was 13.1 units·mg−1 with l‐prolinamide as substrate. This enzyme was purified to electrophoretic homogeneity by ammonium sulfate fractionation and two column chromatography steps. On gel‐filtration chromatography, the enzyme appeared to be a monomer with a molecular mass of 32 kDa. It had maximal activity at 45 °C and pH 9.0, and was completely inactivated in the presence of phenylhydrazine, Zn2+, Ag+, Cd2+ or Hg2+. LaaA had hydrolyzing activity toward l‐amino acid amides such as l‐prolinamide, l‐proline‐p‐nitroanilide, l‐alaninamide and l‐methioninamide, but did not act on the peptide substrates for the proline iminopeptidases despite their sequence similarity to LaaA. The enzyme also acted S‐stereoselectively on (R,S)‐piperidine‐2‐carboxamide, (R,S)‐piperazine‐2‐carboxamide and (R,S)‐piperazine‐2‐tert‐butylcarboxamide. Based on its specificity towards l‐amino acid amides, the enzyme was named l‐amino acid amidase. E. coli transformants overexpressing the laaA gene could be used for the S‐stereoselective hydrolysis of (R,S)‐piperazine‐2‐tert‐butylcarboxamide.
Analysis of the in planta antiviral activity of elderberry ribosome‐inactivating proteins
Authors: Vandenbussche Frank , Desmyter Stijn , Ciani Marialibera , Proost Paul , Peumans Willy J. , Van Damme Els J. M.
Published: April 2004

Although the type‐2 ribosome‐inactivating proteins (SNA‐I, SNA‐V, SNLRP) from elderberry (Sambucus nigra L.) are all devoid of rRNA N‐glycosylase activity towards plant ribosomes, some of them clearly show polynucleotide–adenosine glycosylase activity towards tobacco mosaic virus RNA. This particular substrate specificity was exploited to further unravel the mechanism underlying the in planta antiviral activity of ribosome‐inactivating proteins. Transgenic tobacco (Nicotiana tabacum L. cv Samsun NN) plants expressing the elderberry ribosome‐inactivating proteins were generated and challenged with tobacco mosaic virus in order to analyze their antiviral properties. Although some transgenic plants clearly showed antiviral activity, no clear correlation was observed between in planta antiviral activity of transgenic tobacco lines expressing the different ribosome‐inactivating proteins and the in vitro polynucleotide–adenosine glycosylase activity of the respective proteins towards tobacco mosaic virus genomic RNA. However, our results suggest that the in planta antiviral activity of some ribosome‐inactivating proteins may rely on a direct mechanism on the virus. In addition, it is evident that the working mechanism proposed for pokeweed antiviral protein cannot be extrapolated to elderberry ribosome‐inactivating proteins because the expression of SNA‐V is not accompanied by induction of pathogenesis‐related proteins.
Crystal structures of HIV protease V82A and L90M mutants reveal changes in the indinavir‐binding site
Authors: Mahalingam Bhuvaneshwari , Wang Yuan‐Fang , Boross Peter I. , Tozser Jozsef , Louis John M. , Harrison Robert W. , Weber Irene T.
Published: April 2004

The crystal structures of the wild‐type HIV‐1 protease (PR) and the two resistant variants, PRV82A and PRL90M, have been determined in complex with the antiviral drug, indinavir, to gain insight into the molecular basis of drug resistance. V82A and L90M correspond to an active site mutation and nonactive site mutation, respectively. The inhibition (Ki) of PRV82A and PRL90M was 3.3‐ and 0.16‐fold, respectively, relative to the value for PR. They showed only a modest decrease, of 10–15%, in their kcat/Km values relative to PR. The crystal structures were refined to resolutions of 1.25–1.4 Å to reveal critical features associated with inhibitor resistance. PRV82A showed local changes in residues 81–82 at the site of the mutation, while PRL90M showed local changes near Met90 and an additional interaction with indinavir. These structural differences concur with the kinetic data.
Cell surface adhesion of pregnancy‐associated plasma protein‐A is mediated by four clusters of basic residues located in its third and fourth CCP module
Authors: Weyer Kathrin , Overgaard Michael T. , Laursen Lisbeth S. , Nielsen Claus G. , Schmitz Alexander , Christiansen Michael , Sottrup‐Jensen Lars , Giudice Linda C. , Oxvig Claus
Published: April 2004

The metalloproteinase pregnancy‐associated plasma protein‐A (PAPP‐A) cleaves a subset of insulin‐like growth factor binding proteins (IGFBP), which inhibit the activities of insulin‐like growth factor (IGF). Through this proteolytic activity, PAPP‐A is believed to regulate IGF bioavailability in several biological systems, including the human reproductive system and the cardiovascular system. PAPP‐A adheres to mammalian cells by interactions with glycosaminoglycan (GAG), thus targeting the proteolytic activity of PAPP‐A to the cell surface. Based on site‐directed mutagenesis, we here delineate the PAPP‐A GAG‐binding site in the C‐terminal modules CCP3 and CCP4. Using heparin affinity chromatography, commonly employed in such studies, we define three clusters of arginines and lysines of CCP3, which are important for the interaction of PAPP‐A with heparin. In a model of PAPP‐A CCP3‐CCP4, basic residues of these sequence clusters form a contiguous patch located on one side of the structure. Binding to the unknown, natural cell surface receptor of PAPP‐A, assessed by flow cytometry, also depends on residues of these three basic clusters. However, single or double residue substitutions generally have a modest effect on PAPP‐A heparin binding assessed by chromatography, but cell surface adhesion was critically reduced by several of these substitutions, emphasizing the relevance of analysis by flow cytometry. The contributions of positively charged residues located in CCP4 were all minor when analyzed by heparin affinity chromatography. However, the mutation of CCP4 residues Arg1459 and Lys1460 to Ala almost abrogated cell surface adhesion. Furthermore, when acidic residues of the homologous proteinase PAPP‐A2 (Asp1547, Glu1555 and Glu1567) were introduced into the corresponding positions in the sequence of PAPP‐A, located in each of the three basic clusters of CCP3, binding to heparin was strongly impaired and cell surface binding was abrogated. This explains, at least in part, why PAPP‐A2 lacks the ability of cell surface adhesion, and further emphasizes the role of the basic clusters defined in PAPP‐A.
Effect of season of burn on shoot recovery and post‐fire flowering performance in the resprouter Stirlingia latifolia R. Br. (Proteaceae)
Authors: Bowen Barbara J. , Pate John S.
Published: April 2004

Abstract  Stirlingia latifolia R. Br. is a proteaceous undershrub that is widespread in open woodlands and heathlands of the south‐west botanical province of Western Australia where it is subject to frequent fires, both natural and the result of fuel‐reduction burns. Shoots are completely destroyed by fire but regenerate rapidly by resprouting numerous new shoots from the root crown. Flowering is strongly triggered by fire with only sparse flowering in fire‐free periods. A study was undertaken to compare regrowth and flowering in populations of S. latifolia burnt in summer or autumn with populations burnt in spring as well as in unburnt population. Post‐fire flowering was recorded in 92% of plants burnt in summer/autumn compared with 73% of plants burnt in spring and less than 3% in populations that had not been burnt for more than 2 years. Plants burnt in summer/autumn resprouted an average of 8.5 shoots from their root crown, of which 93% developed an inflorescence. In contrast, spring‐burnt plants averaged only 5.9 shoots per plant with only 64% of these bearing an inflorescence. Ability to produce flowers was found to be related to plant age, with young individuals producing fewer or no inflorescences following spring burns in comparison with the more prolific flowering of similarly aged individuals following summer/autumn burns. Summer/autumn‐burnt plants also produced significantly longer inflorescence‐bearing shoots bearing a greater numbers of flower heads than those burnt in spring. Possible explanations for these results are given in the present report.
Seasonal drought and dry‐season irrigation influence leaf‐litter nutrients and soil enzymes in a moist, lowland forest in Panama
Authors: Yavitt Joseph B. , Wright S. Joseph , Wieder R. Kelman
Published: April 2004

Abstract  Climatic conditions should not hinder nutrient release from decomposing leaf‐litter (mineralization) in the humid tropics, even though many tropical forests experience drought lasting from several weeks to months. We used a dry‐season irrigation experiment to examine the effect of seasonal drought on nutrient concentrations in leaf‐fall and in decomposing leaf‐litter. In the experiment, soil in two 2.25‐ha plots of old‐growth lowland moist forest on Barro Colorado Island, Republic of Panama, was watered to maintain soil water potential at or above field capacity throughout the 4‐month dry season. Wet‐season leaf‐fall had greater concentrations of nitrogen (N, 13.5 mg g−1) and calcium (Ca, 15.6 mg g−1) and lower concentrations of sulfur (S, 2.51 mg g−1) and potassium (K, 3.03 mg g−1) than dry‐season leaf‐fall (N = 11.6 mg g−1, Ca = 13.6 mg g−1, S = 2.98 mg g−1, K = 5.70 mg g−1). Irrigation did not affect nutrient concentrations or nutrient return from forest trees to the forest floor annually (N = 18 g m−2, phosphorus (P) = 1.06 g m−2, S = 3.5 g m−2, Ca = 18.9 g m−2, magnesium = 6.5 g m−2, K = 5.7 g m−2). Nutrient mineralization rates were much greater during the wet season than the dry season, except for K, which did not vary seasonally. Nutrient residence times in forest‐floor material were longer in control plots than in irrigated plots, with values approximately equal to that for organic matter (210 in control plots vs 160 in irrigated plots). Calcium had the longest residence time. Forest‐floor material collected at the transition between seasons and incubated with or without leaching in the laboratory did not display large pulses in nutrient availability. Rather, microorganisms immobilized nutrients primarily during the wet season, unlike observations in tropical forests with longer dry seasons. Large amounts of P moved among different pools in forest‐floor material, apparently mediated by microorganisms. Arylsulfatase and phosphatase enzymes, which mineralize organically bound nutrients, had high activity throughout the dry season. Low soil moisture levels do not hinder nutrient cycling in this moist lowland forest.
Do feral house mice have an impact on invertebrate communities on sub‐Antarctic Marion Island?
Authors: Van Aarde R. J. , Ferreira S. M. , Wassenaar T. D.
Published: April 2004

Abstract  House mice (Mus domesticus L.) have been present on sub‐Antarctic Marion Island since the early 1800s. Several authors have suggested that an increase in mice density as a result of a general warming trend in the sub‐Antarctic climate from the 1960s has led to a decline in invertebrate biomass and abundance. These suggestions have been supported by the observation that the invertebrates of nearby mouse‐free Prince Edward Island are apparently larger and more numerous than on Marion. Our experiment was designed to determine whether mice have a direct effect on invertebrate abundance, biomass and community structure, or an effect on the vegetation community and thus potentially an indirect effect on invertebrates. We constructed five wire‐mesh mouse‐free exclosures in one habitat type on Marion Island and recorded both the soil macro‐invertebrate community and the vegetation inside and outside each of the exclosures before the start of the experiment in 1996 and twice thereafter (1998 and 2000). Mice had no significant effect on any of the eight prey groups' abundance or biomass, or on community structure (diversity and composition). Four of the prey groups changed significantly over time in either biomass or abundance, independent of the presence of mice. Our results, which may have been affected by generally low statistical power, suggest that factors other than mice had a larger impact on invertebrates than mice alone.
The pressure–temperature–time path of migmatites from the Sikkim Himalaya
Authors: Harris N. B. W. , Caddick M. , Kosler J. , Goswami S. , Vance D. , Tindle A. G.
Published: April 2004

A combined metamorphic and isotopic study of lit‐par‐lit migmatites exposed in the hanging wall of the Main Central Thrust (MCT) from Sikkim has provided a unique insight into the pressure–temperature–time path of the High Himalayan Crystalline Series of the eastern Himalaya. The petrology and geochemistry of one such migmatite indicates that the leucosome comprises a crystallized peraluminous granite coexisting with sillimanite and alkali feldspar. Large garnet crystals (2–3 mm across) are strongly zoned and grew initially within the kyanite stability field. The melanosome is a biotite–garnet pelitic gneiss, with fibrolitic sillimanite resulting from polymorphic inversion of kyanite. By combining garnet zoning profiles with the NaCaMnKFMASHTO pseudosection appropriate to the bulk composition of a migmatite retrieved from c. 1 km above the thrust zone, it has been established that early garnet formed at pressures of 10–12 kbar, and that subsequent decompression caused the rock to enter the melt field at c. 8 kbar and c. 750 °C, generating peritectic sillimanite and alkali feldspar by the incongruent melting of muscovite. Continuing exhumation resulted in resorption of garnet. Sm–Nd growth ages of garnet cores and rim, indicate pre‐decompression garnet growth at 23 ± 3 Ma and near‐peak temperatures during melting at 16 ± 2 Ma. This provides a decompression rate of 2 ± 1 mm yr−1 that is consistent with exhumation rates inferred from mineral cooling ages from the eastern Himalaya. Simple 1D thermal modelling confirms that exhumation at this rate would result in a near‐isothermal decompression path, a result that is supported by the phase relations in both the melanosome and leucosome components of the migmatite. Results from this study suggest that anatexis of Miocene granite protoliths from the Himalaya was a consequence of rapid decompression, probably in response to movement on the MCT and on the South Tibetan detachment to the north.