bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular structure of amyloid fibrils: insights from solid-state NMR
Authors: Tycko Robert 
Published: June 2006

1. Introduction 22. Sources of structural information in solid-state NMR data 52.1 General remarks 52.2 Chemical shifts, linewidths, and magic-angle spinning 62.3 Dipole–dipole couplings and dipolar recoupling 82.4 Tensor correlation techniques 122.5 Solid-state NMR of aligned samples 142.6 Indirect sources of structural information 152.7 Sample preparation for solid-state NMR 153. Levels of structure in amyloid fibrils 184. Molecular structure of β-amyloid fibrils 254.1 Self-propagating, molecular-level polymorphism in Aβ1–40 fibrils 254.2 Structural model for Aβ1-40 fibrils 284.3 Staggering of β-strands in Aβ1-40 fibrils 324.4 Structure of Aβ1-42 fibrils 344.5 Structure of fibrils formed by short β-amyloid fragments 344.6 Structures of non-fibrillar aggregates 355. Molecular structure of other amyloid fibrils 365.1 Ure2p10–39 and full-length Ure2p fibrils 365.2 TTR105–115 fibrils 385.3 HET-s fibrils 385.4 Amylin fibrils 395.5 PrP fibrils 395.6 ccβ fibrils 405.7 α-synuclein fibrils 405.8 Calcitonin fibrils 416. Data relevant to various proposals regarding amyloid structure 416.1 β-helical models for amyloid fibrils 416.2 Amyloid fibrils as water-filled nanotubes 426.3 Domain swapping in amyloid fibrils 426.4 The parallel superpleated β-structure model 436.5 α-sheet structures in amyloid fibrils 437. Conclusions 448. Acknowledgments 469. References 46Solid-state nuclear magnetic resonance (NMR) measurements have made major contributions to our understanding of the molecular structures of amyloid fibrils, including fibrils formed by the β-amyloid peptide associated with Alzheimer's disease, by proteins associated with fungal prions, and by a variety of other polypeptides. Because solid-state NMR techniques can be used to determine interatomic distances (both intramolecular and intermolecular), place constraints on backbone and side-chain torsion angles, and identify tertiary and quaternary contacts, full molecular models for amyloid fibrils can be developed from solid-state NMR data, especially when supplemented by lower-resolution structural constraints from electron microscopy and other sources. In addition, solid-state NMR data can be used as experimental tests of various proposals and hypotheses regarding the mechanisms of amyloid formation, the nature of intermediate structures, and the common structural features within amyloid fibrils. This review introduces the basic experimental and conceptual principles behind solid-state NMR methods that are applicable to amyloid fibrils, reviews the information about amyloid structures that has been obtained to date with these methods, and discusses how solid-state NMR data provide insights into the molecular interactions that stabilize amyloid structures, the generic propensity of polypeptide chains to form amyloid fibrils, and a number of related issues that are of current interest in the amyloid field.
Clinical Trials in Dementia
Authors: Raya-Ampil Encarnita , Cummings Jeffrey L. 
Published: June 2006

ABSTRACTDementia, particularly Alzheimer's disease (AD), is increasing by patient population included in clinical trials. The methodology for trials of AD patients have been defined in terms of outcomes, standard measures and analytic techniques. Trial methodology is evolving with experience as new potential therapies become available. Screening criteria, instrumentation choices, duration of trials and analytic strategies may have a profound impact on the conclusions that can be derived from trials. The components of AD trials are reviewed in detail in this chapter.
Playing Games with African Lives: The G7 Debt Relief Strategy and the Politics of Indifference
Authors: Cheru Fantu 
Published: June 2006

Abstract
This chapter examines the politics of policy reform in low-income Africa, and specifically the double standard applied by the creditor countries in dealing with the debts of middle-income Latin American and low-income African countries. Whereas the Latin American debt was promptly dealt with by Western creditors because of the risk it posed to the stability of the Western banking system, equal attention was never given to the debt burden of the poorest African countries, whose debts were largely owed to multilateral financial institutions. Finally, the chapter examines the adequacy of the heavily indebted poor countries (HIPC) initiative, which was introduced in 1996 to address the problem of debt owed by low-income countries to the multilateral development banks.
Ecological Debt—The Economic Possibilities for Our Grandchildren
Authors: Simms Andrew 
Published: June 2006

AbstractThis chapter broadens the analysis of sovereign debt by incorporating ecological concerns. Centuries of consumption of the natural resources of the developing world by the developed world, resources that in many cases were acquired illegally or by force, have produced what is describes as an ecological debt of the rich countries to the poor countries. The imbalance in resource consumption helps explain the dramatic divergence in income levels between rich nations and poor nations that has occurred since the early 20th century. It is argued that there is a sustainable equilibrium in the use of the world's natural resources — clean air, fresh water, timber, and petroleum. The wealthy nations of the world have upset that equilibrium at the expense of the poor — taking more than their share of the goods while inflicting the costs of resource depletion and pollution on the poor.
Using International Finance to Further Conservation: The First 15 Years of Debt-for-Nature Swaps
Authors: Reilly William K. 
Published: June 2006

Abstract
This chapter examines debt-for-nature swaps and their potential for offsetting sovereign debt. Debt-for-nature swaps originated in the 1980s as a way of preserving natural areas in the developing world while at the same time reducing the external debt of the host country. The win-win nature of this type of transaction created many potential applications, and the US Congress and other national legislatures soon passed legislation enabling billions of dollars worth of swaps to take place. However, that potential was never realized. Legislative mandates were not funded, developing countries became suspicious of swaps as they believed they posed a threat to their sovereignty, and an improvement in debt markets reduced the attractiveness of swap economics. It is argued that although swaps are not a panacea for either debt reduction or environmental protection, they offer a concrete tool to promote both ends, and tremendous potential for swaps still exists.
Dealing with Sovereign Debt: Trends and Implications
Authors: Porzecanski Arturo C. 
Published: June 2006

AbstractThis chapter provides an overview of the reasons behind sovereign debt defaults. It discusses trends in external indebtedness (public and private) and in government indebtedness (domestic and foreign). It describes the manner in which private lenders and investors, and official bilateral and multilateral agencies, have dealt with sovereign defaults during the 1980s and 1990s. It closes with an in-depth consideration of the case of Argentina post-2001, which promises to be the most complex sovereign default case in contemporary history. It argues that private lenders and investors have been, and continue to be, able to deal promptly and effectively with instances of sovereign default, such that new, supranational bankruptcy procedures are not necessary.
Darwin and Pangenesis
Authors: Stanford P. Kyle 
Published: June 2006

AbstractThis chapter focuses on the history of our theorizing about the phenomena of generation and inheritance. It attempts to show that according to historical records, our efforts to theorize about inheritance and generation continued to be plagued by the problem of unconceived alternatives long after we came to embrace substantive evidential, metaphysical, and methodological constraints essentially continuous with those of the present day. It is argued that Darwin shows no evidence of having considered and rejected the idea that similarities between ancestors and offspring might be results of a common cause rather than links in a causal chain, and indeed shows no evidence of even having been able to understand this line of thought when it was explicitly presented to him directly by Galton. Instead the most natural conclusion to draw from the historical evidence is that Darwin simply failed to conceive of or consider the entire class of theoretical alternatives to pangenesis picked out by this idea, notwithstanding the fact that it offered an equally promising strategy for explaining what he took to be the central phenomena of inheritance and generation.
SeqVis: Visualization of compositional heterogeneity in large alignments of nucleotides
Authors: Ho Joshua W. K. , Adams Cameron E. , Lew Jie Bin , Matthews Timothy J. , Ng Chiu Chin , Shahabi-Sirjani Arash , Tan Leng Hong , Zhao Yu , Easteal Simon , Wilson Susan R , Jermiin Lars S 
Published: June 2006

Abstract
Summary: Most phylogenetic methods assume that the sequences evolved under homogeneous, stationary and reversible conditions. Compositional heterogeneity in data intended for studies of phylogeny suggests that the data did not evolve under these conditions. SeqVis, a Java application for analysis of nucleotide content, reads sequence alignments in several formats and plots the nucleotide content in a tetrahedron. Once plotted, outliers can be identified, thus allowing for decisions on the applicability of the data for phylogenetic analysis.
Availability:
Contact: lars.jermiin@usyd.edu.au
Pathways of Glucose Regulation of Monosaccharide Transport in Grape Cells
Authors: Conde Carlos , Agasse Alice , Glissant David , Tavares Rui , Gerós Hernâni , Delrot Serge 
Published: June 2006

AbstractGrape (Vitis vinifera) heterotrophic suspension-cultured cells were used as a model system to study glucose (Glc) transport and its regulation. Cells transported d-[14C]Glc according to simple Michaelis-Menten kinetics superimposed on first-order kinetics. The saturating component is a high-affinity, broad-specificity H+-dependent transport system (Km = 0.05 mm). Glc concentration in the medium tightly regulated the transcription of VvHT1 (Vitis vinifera hexose transporter 1), a monosaccharide transporter previously characterized in grape berry, as well as VvHT1 protein amount and monosaccharide transport activity. All the remaining putative monosaccharide transporters identified so far in grape were poorly expressed and responded weakly to Glc. VvHT1 transcription was strongly repressed by Glc and 2-deoxy-d-Glc, but not by 3-O-methyl-d-Glc or Glc plus mannoheptulose, indicating the involvement of a hexokinase-dependent repression. 3-O-Methyl-d-Glc, which cannot be phosphorylated, and Glc plus mannoheptulose induced a decrease of transport activity caused by the reduction of VvHT1 protein in the plasma membrane without affecting VvHT1 transcript levels. This demonstrates hexokinase-independent posttranscriptional regulation. High Glc down-regulated VvHT1 transcription and Glc uptake, whereas low Glc increased those parameters. Present data provide an example showing control of plant sugar transporters by their own substrate both at transcriptional and posttranscriptional levels. VvHT1 protein has an important role in the massive import of monosaccharides into mesocarp cells of young grape berries because it was localized in plasma membranes of the early developing fruit. Protein amount decreased abruptly throughout fruit development as sugar content increases, consistent with the regulating role of Glc on VvHT1 expression found in suspension-cultured cells.
Pathway of Sugar Transport in Germinating Wheat Seeds
Authors: Aoki Naohiro , Scofield Graham N. , Wang Xin-Ding , Offler Christina E. , Patrick John W. , Furbank Robert T. 
Published: June 2006

Abstract
Three homeologous genes encoding a sucrose (Suc) transporter (SUT) in hexaploid wheat (Triticum aestivum), TaSUT1A, 1B, and 1D, were expressed in germinating seeds, where their function is unknown. All three TaSUT1 proteins were confirmed to be capable of transporting both Suc and maltose by complementation tests with the SUSY7/ura3 yeast (Saccharomyces cerevisiae) mutant strain. The role of Suc transporters in germinating grain was examined by combining in situ hybridization, immunolocalization, fluorescent dye tracer movement, and metabolite assays. TaSUT1 transcript and SUT protein were detected in cells of the aleurone layer, scutellar epidermis, scutellar ground cells, and sieve element-companion cell complexes located in the scutellum, shoot, and root. Ester loading of the membrane-impermeable fluorescent dye carboxyfluorescein into the scutellum epidermal cells of germinating seeds showed that a symplasmic pathway connects the scutellum to the shoot and root via the phloem. However, the scutellar epidermis provides an apoplasmic barrier to solute movement from endosperm tissue. Measurements of sugars in the root, shoot, endosperm, and scutellum suggest that, following degradation of endosperm starch, the resulting hexoses are converted to Suc in the scutellum. Suc was found to be the major sugar present in the endosperm early in germination, whereas maltose and glucose predominate during the later stage. It is proposed that loading the scutellar phloem in germinating wheat seeds can proceed by symplasmic and apoplasmic pathways, the latter facilitated by SUT activity. In addition, SUTs may function to transport Suc into the scutellum from the endosperm early in germination and later transport maltose.
Analysis of theArabidopsis rsr4-1/pdx1-3Mutant Reveals the Critical Function of the PDX1 Protein Family in Metabolism, Development, and Vitamin B6 Biosynthesis
Authors: Wagner Susan , Bernhardt Anne , Leuendorf Jan Erik , Drewke Christel , Lytovchenko Anna , Mujahed Nader , Gurgui Cristian , Frommer Wolf B. , Leistner Eckhard , Fernie Alisdair R. , Hellmann Hanjo 
Published: June 2006

AbstractVitamin B6 represents a highly important group of compounds ubiquitous in all living organisms. It has been demonstrated to alleviate oxidative stress and in its phosphorylated form participates as a cofactor in &gt;100 biochemical reactions. By means of a genetic approach, we have identified a novel mutant, rsr4-1 (for reduced sugar response), with aberrant root and leaf growth that requires supplementation of vitamin B6 for normal development. Cloning of the mutated gene revealed that rsr4-1 carries a point mutation in a member of the PDX1/SOR1/SNZ (for Pyridoxine biosynthesis protein 1/Singlet oxygen resistant 1/Snooze) family that leads to reduced vitamin B6 content. Consequently, metabolism is broadly altered, mainly affecting amino acid, raffinose, and shikimate contents and trichloroacetic acid cycle constituents. Yeast two-hybrid and pull-down analyses showed that Arabidopsis thaliana PDX1 proteins can form oligomers. Interestingly, the mutant form of PDX1 has severely reduced capability to oligomerize, potentially suggesting that oligomerization is important for function. In summary, our results demonstrate the critical function of the PDX1 protein family for metabolism, whole-plant development, and vitamin B6 biosynthesis in higher plants.
JekyllEncodes a Novel Protein Involved in the Sexual Reproduction of Barley
Authors: Radchuk Volodymyr , Borisjuk Ljudmilla , Radchuk Ruslana , Steinbiss Hans-Henning , Rolletschek Hardy , Broeders Sylvia , Wobus Ulrich 
Published: June 2006

AbstractCereal seed development depends on the intimate interaction of filial and maternal tissues, ensuring nourishment of the new generation. The gene jekyll, which was identified in barley (Hordeum vulgare), is preferentially expressed in the nurse tissues. JEKYLL shares partial similarity with the scorpion Cn4 toxin and is toxic when ectopically expressed in Escherichia coli and tobacco (Nicotiana tabacum). In barley, jekyll is upregulated in cells destined for autolysis. The gene generates a gradient of expression in the nucellar projection, which mediates the maternal–filial interaction during seed filling. Downregulation of jekyll by the RNA interference technique in barley decelerates autolysis and cell differentiation within the nurse tissues. Flower development and seed filling are thereby extended, and the nucellar projection no longer functions as the main transport route for assimilates. A slowing down in the proliferation of endosperm nuclei and a severely impaired ability to accumulate starch in the endosperm leads to the formation of irregular and small-sized seeds at maturity. Overall, JEKYLL plays a decisive role in the differentiation of the nucellar projection and drives the programmed cell death necessary for its proper function. We further suggest that cell autolysis during the differentiation of the nucellar projection allows the optimal provision of basic nutrients for biosynthesis in endosperm and embryo.
Downregulation of ClpR2 Leads to Reduced Accumulation of the ClpPRS Protease Complex and Defects in Chloroplast Biogenesis inArabidopsis
Authors: Rudella Andrea , Friso Giulia , Alonso Jose M. , Ecker Joseph R. , van Wijk Klaas J. 
Published: June 2006

AbstractPlastids contain tetradecameric Clp protease core complexes, with five ClpP Ser-type proteases, four nonproteolytic ClpR, and two associated ClpS proteins. Accumulation of total ClpPRS complex decreased twofold to threefold in an Arabidopsis thaliana T-DNA insertion mutant in CLPR2 designated clpr2-1. Differential stable isotope labeling of the ClpPRS complex with iTRAQ revealed a fivefold reduction in assembled ClpR2 accumulation and twofold to fivefold reductions in the other subunits. A ClpR2:(his)6 fusion protein that incorporated into the chloroplast ClpPRS complex fully complemented clpr2-1. The reduced accumulation of the ClpPRS protease complex led to a pale-green phenotype with delayed shoot development, smaller chloroplasts, decreased thylakoid accumulation, and increased plastoglobule accumulation. Stromal ClpC1 and 2 were both recruited to the thylakoid surface in clpr2-1. The thylakoid membrane of clpr2-1 showed increased carotenoid content, partial inactivation of photosystem II, and upregulated thylakoid proteases and stromal chaperones, suggesting an imbalance in chloroplast protein homeostasis and a well-coordinated network of proteolysis and chaperone activities. Interestingly, a subpopulation of PsaF and several light-harvesting complex II proteins accumulated in the thylakoid with unprocessed chloroplast transit peptides. We conclude that ClpR2 cannot be functionally replaced by other ClpP/R homologues and that the ClpPRS complex is central to chloroplast biogenesis, thylakoid protein homeostasis, and plant development.
Two‐dose basiliximab compared with two‐dose daclizumab in renal transplantation: a clinical study
Authors: Lin Minzhuan , Ming Aimin , Zhao Ming 
Published: June 2006

Abstract:  Background:  Addition of the interleukin‐2 receptor (IL‐2R) antagonists basiliximab or daclizumab to a calcineurin inhibitor‐based regimen significantly reduces risk of acute rejection with a tolerability profile similar to a placebo. Use of a truncated two‐dose regimen of daclizumab has been reported, but till date, there has been no controlled study of two‐dose daclizumab vs. two‐dose basiliximab.Methods:  Deceased‐donor renal transplant recipients were randomized to basiliximab (20 mg on days 0 and 4) or daclizumab (50 mg on days 1 and 14) with cyclosporine, mycophenolate mofetil and corticosteroids. Flow cytometry was used to calculate the proportion of CD25+ T cells in peripheral blood.Results:  Thirty patients were randomized to basiliximab and 28 to daclizumab. There was one patient death in each group, with no other graft losses. By six months, the incidence of biopsy‐proven acute rejection was 0% with basiliximab vs. 21.4% with daclizumab (p<0.05). Three patients in the daclizumab group required OKT3 for steroid‐resistant rejection. There were no between‐group differences in the incidence of infection. The proportion of CD25+ T cells declined markedly during the first two wk in both groups, but was significantly lower in the basiliximab group during weeks six to eight.Conclusion:  Two doses of basiliximab are more effective than two 1 mg/kg doses of daclizumab in preventing acute rejection in de novo renal transplant patients receiving cyclosporine, mycophenolate mofetil and corticosteroid maintenance therapy. In patients receiving relatively low‐level immunosuppression in order to minimize toxicity, basiliximab may be preferable to a truncated daclizumab regimen.
Reactivation of hepatitis and lamivudine therapy in 11 HBsAg‐positive renal allograft recipients: a single centre experience
Authors: Murakami Reiichi , Amada Noritoshi , Sato Takaomi , Orii Takashi , Kikuchi Hiroyuki , Haga Izumi , Ohashi Yoichi , Okazaki Hajime 
Published: June 2006

Abstract:  Background:  In hepatitis B virus (HBV) surface antigen (HBsAg) (+) renal allograft recipients, the mortality associated with liver disease reaches 37–78%. An antiviral agent, lamivudine, has recently been reported to be safe and effective for preventing hepatic damage in these patients, although either resurgence of HBV‐DNA levels after discontinuation or emerging resistant HBV mutants caused by long‐term administration are still unsettled.Methods:  Between July 1976 and December 2003, 555 renal transplantations were performed in our centre. Of these, 11 patients who were HBsAg (+) at the time of transplantation (2.0%) were selected for this study. We investigated the incidence of hepatitis reactivation for three yr after transplantation and their clinical courses, including the efficacy of lamivudine therapy in seven of the 11 patients.Results:  Six episodes of hepatitis reactivation developed in five of the 11 patients (45.5%) within three yr after transplantation. Five episodes of six occurred within four months after transplantation. The patient who underwent the most severe reactivation needed intensive care including lamivudine administration and plasma exchange. Lamivudine caused no severe adverse effects and HBV‐DNA levels dropped to under measurable levels within four months after lamivudine administration in all patients. Resistant HBV mutant emerged in only one patient, who had the longest lamivudine administration of 49 months.Conclusions:  For HBsAg (+) renal allograft recipients, careful monitoring of HBV‐DNA levels and timely administration of lamivudine could prevent hepatic damage caused by reactivation of hepatitis.
Living or deceased donor kidney transplants for candidates with significant extrarenal morbidity
Authors: Kandaswamy Raja , Kasiske Bertram , Ibrahim Hassan , Matas Arthur J. 
Published: June 2006

Abstract: Background: Individuals with end‐stage renal disease (ESRD) must weigh the benefits and risks of dialysis vs. a transplant. However, if the patient has extrarenal morbidity, survival may be limited. We have recommended that, when possible, recipients have a living donor (LD) transplant. However, it could be argued that for recipients with extrarenal morbidity, the potential benefit does not justify the donor risks and that, therefore, recipients with increased risks should be denied an LD transplant.Materials and methods: We studied the outcome of LD vs. deceased donor (DD) transplants in recipients with extrarenal morbidity. For recipients with extrarenal morbidity, patient survival (p<0.01) and graft survival (p<0.01) rates were significantly better for LD (vs. DD) transplant recipients. We found no difference in death‐censored graft survival rates.Conclusion: Kidney transplant recipients with extrarenal morbidity benefit from an LD transplant. Both donor and recipient informed consent is important.