bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kristallstrukturen und spektroskopische Eigenschaften von 2λ3‐Phospha‐1, 3‐dionaten und 1, 3‐Dionaten des Calciums ‐ ein Vergleich am Beispiel der 1, 3‐Diphenyl‐ und 1, 3‐Di(tert‐butyl)‐Derivate
Authors: Becker Gerd , Niemeyer Mark , Mundt Otto , Schwarz Wolfgang , Westerhausen Matthias , Ossberger Manfred W. , Mayer Peter , Nöth Heinrich , Zhong Zhiyuan , Dijkstra Pieter J. , Feijen Jan 
Published: December 2004

AbstractDer Wasserstoff‐Metall‐Austausch zwischen Dibenzoylphosphan und Calciumcarbid in Tetrahydrofuran (THF) ergibt nach Zusatz des Liganden 1, 3, 5‐Trimethyl‐1, 3, 5‐triazinan (TMTA) den als Kokristallisat mit Benzol isolierten zweikernigen Komplex Bis[(tmta‐N, N′, N″)calcium‐bis(dibenzoylphosphanid)] (1a). In ähnlicher Weise führt die Umsetzung von Bis(2, 2‐dimethylpropionyl)phosphan mit Bis(thf‐O)calcium‐bis[bis(trimethylsilyl)amid] in 1, 2‐Dimethoxyethan (DME) mit guten Ausbeuten zum ‐Bis(dme‐O, O′)calcium‐bis[bis(2, 2‐dimethylpropionyl)phosphanid] (1b). Über die Reaktion von Bis(thf‐O)calcium‐bis[tris(trimethylsilylmethyl)zinkat] mit dem Kohlenstoffanalogon 1, 3‐Diphenylpropan‐1, 3‐dion (Dibenzoylmethan) bzw. 2, 2, 6, 6‐Tetramethylheptan‐3, 5‐dion (Dipivaloylmethan) erhält man im gleichen Solvens das einkernige Bis(dme‐O, O′)calcium‐bis(dibenzoylmethanid) (2a) und das zweikernige (μ‐dme‐O, O′)Bis[(dme‐O, O′)calcium‐bis(dipivaloylmethanid)] (2b). Überraschenderweise setzt sich das dabei gebildete Dialkylzink mit den 1, 3‐Diketonaten 2a und 2b nicht weiter um. Schließlich kann aus dem unsymmetrischen Liganden 2‐(Methoxycarbonyl)cyclopentanon und Bis(thf‐O)calcium‐bis[bis(trimethylsilyl)amid] in Toluol der dreikernige Komplex 3 als Kokristallisat mit Tetrahydrofuran erhalten werden; der β‐Ketoester‐Ligand verbrückt als Anion ausschließlich über die Cyclopentanon‐Einheit.
Mitochondrial creatine kinase activity in patients with disturbed energy generation in muscle mitochondria
Authors: Smeitink J. , Ruitenbeek W. , Sengers R. , Wevers R. , v. Lith T. , Trijbels F. 
Published: December 2004

SummaryEleven patients with an established disturbance in muscle mitochondrial energy generation, in whom no defect in the pyruvate dehydrogenase complex or in the complexes of the respiratory chain could be detected, were investigated for a possible deficiency of mitochondrial creatine kinase (Mi‐CK) (EC 2.7.3.2). Four patients with a defect in one of the complexes of the respiratory chain were also investigated for Mi‐CK activity. In none of the investigated patients was Mi‐CK deficiency found. Surprisingly, two of the four patients with a defect in one of the respiratory chain complexes showed enhanced activity of Mi‐CK. It is concluded that Mi‐CK deficiency is not frequently found as a primary defect in patients with disturbance in mitochondrial energy generation, but more patients should be examined to allow a definite conclusion.
A family with visceral course of Niemann‐Pick disease, macular halo syndrome and low sphingomyelin degradation rate
Authors: Sperl W. , Bart G. , Vanier M. T. , Christomanou H. , Baldissera I. , Steichen‐Gersdorf E. , Paschke E. 
Published: December 2004

SummaryWe report a family with six patients suffering from a sphingomyelinase‐deficient form of Niemann‐Pick disease, all presenting with a visceral course of the disease. Retinal changes classified as macular halos in four members indicated neuronal storage and therefore an intermediate type of the disease. For further classification of the biochemical type, [choline‐methyl‐14C]sphingomyelin degradation studies were carried out in fibroblast cultures of all six members. The low degradation rates measured were similar to those usually found in the neuronopathic form (type A) of Niemann‐Pick disease. This family illustrates the broad heterogeneity within the sphingomyelinase deficiency group of the Niemann‐Pick disease. Apparently the finding of a low sphingomyelin degradation rate in fibroblast cultures does not necessarily imply a typical serious and lethal course of the disease.
Modeling flight activity and population dynamics of the pine engraver, Ips pini, in the Great Lakes region: effects of weather and predators over short time scales
Authors: Aukema Brian H. , Clayton Murray K. , Raffa Kenneth F. 
Published: December 2004

AbstractAscertaining the relative effects of factors such as weather and predation on population dynamics, and determining the time scales on which they operate, is important to our understanding of basic ecology and pest management. In this study, we sampled the pine engraver Ips pini (Say) (Coleoptera: Scolytidae) and its predominant predators Thanasimus dubius (F.) (Coleoptera: Cleridae) and Platysoma cylindrica (Paykull) (Coleoptera: Histeridae) in red pine plantations in Wisconsin, USA, over 2 years. We sampled both the prey and predators using flight traps baited with the synthetic aggregation pheromone of I. pini. Flight models were constructed using weather variables (temperature and precipitation), counts of bark beetles and their predators, and temporal variables to incorporate possible effects of seasonality. The number of I. pini per weekly collection period was temperature dependent and decreased with the number of predators, specifically T. dubius in 2001 and P. cylindrica in 2002. The number of predators captured each week was also weather dependent. The predators had similar seasonal phenologies, and the number of each predator species was positively correlated with the other. Including a term for the number of prey did not improve the model fits for either predator for either year. Our results suggest that exogenous weather factors strongly affect the flight activity of I. pini, but that its abundance is also affected by direct density‐dependent processes acting over weekly time scales. Adult predation during both colonization and dispersal are likely processes yielding these dynamics.
Direct demonstration of carbamoyl phosphate formation on the C‐terminal domain of carbamoyl phosphate synthetase
Authors: Kothe Michael , Purcarea Cristina , Guy Hedeel I. , Evans David R. , Powers‐Lee Susan G. 
Published: December 2004

AbstractCarbamoyl phosphate synthetase synchronizes the utilization of two ATP molecules at duplicated ATP‐grasp folds to catalyze carbamoyl phosphate formation. To define the dedicated functional role played by each of the two ATP sites, we have carried out pulse/labeling studies using the synthetases from Aquifex aeolicus and Methanococcus jannaschii, hyperthermophilic organisms that encode the two ATP‐grasp folds on separate subunits. These studies allowed us to differentially label each active site with [γ‐32P]ATP and determine the fate of the labeled γ‐phosphate in the synthetase reaction. Our results provide the first direct demonstration that enzyme‐catalyzed transfer of phosphate from ATP to carbamate occurs on the more C‐terminal of the two ATP‐grasp folds. These findings rule out one mechanism proposed for carbamoyl phosphate synthetase, where one ATP acts as a molecular switch, and provide additional support for a sequential reaction mechanism where the γ‐phosphate groups of both ATP molecules are transferred to reactants. CP synthesis by subunit C in our single turnover pulse/chase assays did not require subunit N, but subunit N was required for detectable CP synthesis in the traditional continuous assay. These findings suggest that cross‐talk between domain N and C is required for product release from subunit C.
Contribution of the intrinsic disulfide to the assembly mechanism of islet amyloid
Authors: Koo Bon W. , Miranker Andrew D. 
Published: December 2004

AbstractAmyloidogenesis from soluble protein requires conformational and oligomeric assembly steps. In systems where the precursor protein is natively unfolded, such as islet amyloid polypeptide (IAPP), forces and structural changes relevant to protein unfolding are not thought to participate in the assembly mechanism. Thus, fiber core structure elements should provide the dominant contributions to assembly kinetics. Here we show, however, that residues outside the amyloid core can influence the mechanism of IAPP fiber assembly. IAPP possesses an intramolecular disulfide bond between residues 2 and 7. This short‐range disulfide prohibits the N‐terminal region from adopting the β‐strand structure of an amyloid. We examined the role of this disulfide in fiber formation by generating a truncated construct (IAPP8–37) and a stable reduced form of the full‐length protein (IAPPCAM). The fiber structures and assembly kinetics of these variants were assessed via optical and mass spectroscopy. Our data confirm that the disulfide does not contribute to the amyloid fiber core structure. Remarkably, however, it plays a central role in the assembly mechanism. First, loss of the disulfide substantially reduces fiber formation by secondary nucleation, i.e., the ability of pre‐existing fibers to participate in the formation of new fibers. Second, the bypass of nucleation by seed addition is a two‐step process, termed activation. Loss of the disulfide eliminates this two‐step nature of seeded kinetics.
The structures of the unique sulfotransferase retinol dehydratase with product and inhibitors provide insight into enzyme mechanism and inhibition
Authors: Pakhomova Svetlana , Buck Jochen , Newcomer Marcia E. 
Published: December 2004

AbstractThe structure of retinol dehydratase (DHR) from Spodoptera frugiperda, a member of the sulfotransferase superfamily, in complexes with the inactive form of the cofactor PAP 3′‐phosphoadenosine 5′‐phosphate (PAP) and (1) the product of the reaction with retinol anhydroretinol (AR), (2) the retinoid inhibitor all‐trans‐4‐oxoretinol (OR), and (3) the potent steroid inhibitor androsterone (AND) have been determined and compared to the enzyme complex with PAP and retinol. The structures show that the geometry of the active‐site amino acids is largely preserved in the various complexes. However, the β‐ionone rings of the retinoids are oriented differently with respect to side chains that have been shown to be important for the enzymatic reaction. In addition, the DHR:PAP:AND complex reveals a novel mode for steroid binding that contrasts significantly with that for steroid binding in other sulfotransferases. The molecule is displaced and rotated ∼180° along its length so that there is no acceptor hydroxyl in close proximity to the site of sulfate transfer. This observation explains why steroids are potent inhibitors of retinol dehydratase activity, rather than substrates for sulfonation. Most of the steroid‐protein contacts are provided by the α‐helical cap that distinguishes this member of the superfamily. This observation suggests that in addition to providing a chemical environment that promotes the dehydration of a sulfonated intermediate, the cap may also serve to minimize a promiscuous sulfotransferases activity.
Identifying natural substrates for chaperonins using a sequence‐based approach
Authors: Stan George , Brooks Bernard R. , Lorimer George H. , Thirumalai D. 
Published: December 2004

AbstractThe Escherichia coli chaperonin machinery, GroEL, assists the folding of a number of proteins. We describe a sequence‐based approach to identify the natural substrate proteins (SPs) for GroEL. Our method is based on the hypothesis that natural SPs are those that contain patterns of residues similar to those found in either GroES mobile loop and/or strongly binding peptide in complex with GroEL. The method is validated by comparing the predicted results with experimentally determined natural SPs for GroEL. We have searched for such patterns in five genomes. In the E. coli genome, we identify 1422 (about one‐third) sequences that are putative natural SPs. In Saccharomyces cerevisiae, 2885 (32%) of sequences can be natural substrates for Hsp60, which is the analog of GroEL. The precise number of natural SPs is shown to be a function of the number of contacts an SP makes with the apical domain (NC) and the number of binding sites (NB) in the oligomer with which it interacts. For known SPs for GroEL, we find ∼4 < NC < 5 and 2 ≤ NB ≤ 4. A limited analysis of the predicted binding sequences shows that they do not adopt any preferred secondary structure. Our method also predicts the putative binding regions in the identified SPs. The results of our study show that a variety of SPs, associated with diverse functions, can interact with GroEL.
Hydrogen exchange and ligand binding: Ligand‐dependent and ligand‐independent protection in the Src SH3 domain
Authors: Wildes David , Marqusee Susan 
Published: December 2004

AbstractAmide hydrogen‐deuterium exchange has proven to be a powerful tool for detecting and characterizing high‐energy conformations in protein ensembles. Since interactions with ligands can modulate these high‐energy conformations, hydrogen exchange appears to be an ideal experimental probe of the physical mechanisms underlying processes like allosteric regulation. The chemical mechanism of hydrogen exchange, however, can complicate such studies. Here, we examine hydrogen exchange rates in a simple model system, the c‐Src SH3 domain interacting with a short peptide ligand. Addition of ligand slows the rates of hydrogen exchange at nearly every amide for which we can obtain data. Careful analysis, however, reveals that this slowing is due primarily to a reduction in the population of free protein in the system, and not to any specific property of the complex. We present a method to separate the contributions of free and bound protein to the exchange kinetics that has allowed us to identify the subset of amides where exchange arises directly from the complex. These results demonstrate that the slowing of hydrogen exchange induced by ligand interactions should be interpreted with caution, and more extensive experiments are required to correlate changes in hydrogen exchange with changes in structure or internal dynamics.
Immunological Analysis in Paediatric HIV Patients at Different Stages of the Disease
Authors: Lian Y. C. , Della‐Negra M. , Rutz R. , Ferriani V. , De Moraes Vasconcelos D. , Da Silva Duarte A. J. , Kirschfink M. , Grumach A. S. 
Published: December 2004

AbstractThere are only few clinical studies on complement in well‐defined (or characterized) paediatric HIV patients. Aim of this study was to evaluate the complement system and immunoglobulins in HIV‐infected children and to correlate data to stage of disease. Blood samples of 127 HIV‐infected children (11–134 months; 62 male : 65 female) were collected in order to evaluate humoral immunity. The patients were classified according to CDC clinical (N‐asymptomatic; A‐mild symptoms such as common recurrent infections; B‐moderate symptoms such as Candidiasis and herpes infections, meningitis, sepsis and anaemia; C‐severe symptoms such as opportunistic infections and neoplasia) and with respect to immunological criteria (T CD4+ cell count). Analysis of complement system included the classical (CH50), alternative (APH50) pathway activities and plasma concentrations of mannan‐binding lectin (MBL), of the C4 allotypic variants C4A and C4B. (ELISA), and of the C3 split product C3d (rocket immunoeletrophoresis). Immunodiagnosis also included CD4+ and CD8+ lymphocyte count and immunoglobulin concentrations. Complement activation and consumption was observed in all patients correlating with disease activity. Activated classical and alternative pathways and elevated C3d were significantly correlated with immunologic category 3. C3d levels were also significantly correlated with immunologic category 1. Undetectable CH50 and APH50 were found in two (group C) and 10 patients (n = 2, A = 2, B = 2, C = 4), respectively. Low MBL values were found in 13/127 but without correlation to disease severity. Undetectable C4B levels were observed in three patients, favouring the diagnosis of a complete deficiency. Although not related to clinical symptomatology, a strong ongoing complement activation can be observed in all stages of HIV infection. In contrast to earlier reports MBL could not be considered as a risk factor for HIV.
Reduction of Soluble Complement Receptor 2/CD21 in Systemic Lupus Erythomatosus and Sjögren's Syndrome but not Juvenile Arthritis
Authors: Masilamani M. , Nowack R. , Witte T. , Schlesier M. , Warnatz K. , Glocker M. O. , Peter H. H. , Illges H. 
Published: December 2004

AbstractA soluble form of the complement receptor CD21 (sCD21) is shed from the lymphocyte surface. The amount of sCD21 in serum may modulate immunity as sCD21 levels are correlated with several clinical conditions. We report here the serum levels of sCD21 in juvenile arthritis (JA), systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). Using enzyme‐linked immunosorbent assay, we determined sCD21 levels in SLE, SS and JA patients. Mann–Whitney test for nonparametric two‐tail P value was performed to obtain statistical significance. Cytometrical analysis of synovial fluid leucocytes of JA patients was done on a FACSsort. While sCD21 levels in SLE and SS are reduced to levels previously found in rheumatoid arthritis (RA), JA sCD21 levels were normal. sCD21 levels did not correlate with clinical parameters and immunophenotype of synovial cells. CD4 T cells in the synovium were almost all of the CD45RO memory type and 13 of 40 patients displayed synovial expansion of γδT cells. CD21 shedding in JA differs from RA/SS/SLE. JA sCD21 levels in synovial fluid are always lower compared to blood levels of the same patients. Analysis of JA synovial T cells indicates a T‐cell driven response.
Cortisol and Dehydroepiandrosterone Affect the Response of Peripheral Blood Mononuclear Cells to Mycobacterial Antigens during Tuberculosis
Authors: Mahuad C. , Bay M. L. , Farroni M. A. , Bozza V. , Del Rey A. , Besedovsky H. , Bottasso O. A. 
Published: December 2004

AbstractThe effect of cortisol and/or dehydroepiandrosterone (DHEA) on the immune response to antigens obtained from Mycobacterium tuberculosis was studied in vitro by using peripheral blood mononuclear cells obtained from patients at various stages of lung tuberculosis (TB) and from healthy control people (HCo). The results obtained show for the first time that addition of cortisol within concentrations of physiological range can inhibit the mycobacterial antigen‐driven proliferation of cells from HCo and TB patients and the production of interferon‐γ (IFN‐γ), indicating that endogenous levels of cortisol may contribute to the decreased lymphoid cell response to mycobacterium antigens observed in TB patients. DHEA did not affect lymphoid cell proliferation, IFN‐γ production and the cortisol‐mediated inhibitory effects. Interestingly, we found that DHEA, but not cortisol, suppressed the in vitro transforming growth factor‐β production by lymphoid cells from TB patients with an advanced disease, which is indicative of a selective direct effect of this hormone.
Poor In Vitro Maturation and Pro‐Inflammatory Cytokine Response of Dendritic Cells in Children at Genetic Risk of Type 1 Diabetes
Authors: Skarsvik S. , Tiittanen M. , Lindström A. , Casas R. , Ludvigsson J. , Vaarala O. 
Published: December 2004

AbstractType 1 diabetes (T1D) has been associated with an aberrant maturation of dendritic cells (DC). We studied the maturation of monocyte‐derived DC in children with newly diagnosed T1D and in healthy children with genetic risk for T1D. Peripheral blood monocytes from children with newly diagnosed T1D (n = 12; mean age 13.2 years), children with human leukocyte antigen (HLA)‐risk genotype of T1D (n = 7; mean age 12.7 years) and healthy children (n = 14; mean age 11.2 years) were in vitro differentiated into DC. Expression of HLA‐DR, CD80/86 and CD11c and secretion of interleukin (IL)‐12, tumor necrosis factor (TNF)‐α, IL‐6 and IL‐10 were measured using flow cytometry. Lower percentage of DC expressed CD11c and HLA‐DR, and decreased production of TNF‐α was found in children with newly diagnosed T1D and in children at genetic risk when compared to healthy children. Children with risk genotype also had decreased IL‐12 production by DC. Children with T1D and children at genetic risk of T1D appear to have similar aberrancies in the maturation of DC, which may predispose to β‐cell autoimmunity.
Interleukin‐15, as Interferon‐gamma, Induces the Killing of Leishmania infantum in Phorbol‐Myristate‐Acetate‐Activated Macrophages Increasing Interleukin‐12
Authors: D'Agostino P. , Milano S. , Arcoleo F. , Di Bella G. , La Rosa M. , Ferlazzo V. , Caruso R. , Chifari N. , Vitale G. , Mansueto S. , Cillari E. 
Published: December 2004

AbstractThe potential leishmanicidal activity of interleukin‐15 (IL‐15) was examined while priming with the cytokine phorbol‐myristate‐acetate (PMA)‐activated macrophages and infecting them with Leishmania infantum parasites. The activation of macrophage cultures with IL‐15 determined a significant anti‐leishmanial activity, comparable with that induced by interferon‐gamma (IFN‐γ). The killing of Leishmania in macrophages primed with IL‐15, as well as with IFN‐γ, was followed by an increase in the IL‐12 synthesis. The neutralization of IL‐15 or IFN‐γ, by specific monoclonal antibodies (MoAb) caused a significant reduction in leishmanicidal activity. Furthermore, in PMA‐activated macrophages, the neutralization of IL‐12 production by a specific anti‐IL‐12 MoAb reduced leishmanicidal activity induced by IL‐15 and IFN‐γ. Data indicate that IL‐15 could have a role as an activator of leishmanicidal activity, directly or indirectly, by inducing IL‐12 production.
The use of a double subgenomic Sindbis virus expression system to study mosquito gene function: effects of antisense nucleotide number and duration of viral infection on gene silencing efficiency
Authors: Tamang D. , Tseng S. M. , Huang C. Y. , Tsao I. Y. , Chou S. Z. , Higgs S. , Christensen B. M. , Chen C. C. 
Published: December 2004

AbstractRecently we established a simple, effective antisense strategy using a double subgenomic Sindbis (dsSIN) virus expression system to study gene function in mosquitoes. In this study, we further elucidate the effects of antisense nucleotide number and duration of viral infection on mosquito gene silencing efficiency by the dsSIN virus expression system. Over 15 days post virus infection, the degree of parasite melanization was progressively reduced by more than 95%, 75% and 55% in the mosquito Armigeres subalbatus transduced with 600, 147 or 36 bases antisense RNA, targeted to the highly conserved copper binding region of the Ar. subalbatus prophenoloxidase I gene (As‐pro‐POI), respectively. As the duration of viral infection increased from day 3–15, the degree of parasite melanization progressively decreased in all mosquitoes transduced with antisense RNA, irrespective of the lengths of antisense RNA. Progressive loss of parasite melanization function was found to correlate with down regulation of As‐pro‐PO expression at both the mRNA and protein activity levels, and reductions in virus titres in mosquitoes transduced with antisense RNA. A small pro‐PO RNA (c. twenty‐five nucleotides) was identified in mosquitoes transduced with antisense RNA. These data suggest that As‐pro‐POI gene expression is knocked down by degrading the As‐pro‐POI mRNA through the RNAi pathway. In conclusion, our study demonstrates that even a short antisense RNA (thirty‐six bases) can cause silencing of the As‐pro‐POI gene, and the effects of endogenous gene silencing by dsSIN expression system on mosquito gene functions can be accumulative.