julilili42/papers huggingface dataset:
Synthesis and Deformylation of Staphylococcus aureus δ-Toxin Are Linked to Tricarboxylic Acid Cycle Activity
2003-11-02

ABSTRACT In bacteria, translation initiates with formyl-methionine; however, the N-terminal formyl group is usually removed by peptide deformylase, an enzymatic activity requiring iron. Staphylococcus aureus δ-toxin is a 26-amino-acid polypeptide secreted predominantly with a formylated N-terminal methionine, which led us to investigate regulation of δ-toxin deformylation. We observed that during exponential and early postexponential growth, δ-toxin accumulated in the culture medium in formylated and deformylated forms. In contrast, only formylated δ-toxin accumulated after the early postexponential phase. The transition from producing both species of δ-toxin to producing only formyl-methionine-containing δ-toxin coincided with increased tricarboxylic acid (TCA) cycle activity. The TCA cycle contains several iron-requiring enzymes, which led us to hypothesize that TCA cycle induction depletes the iron in the culture medium, thereby inhibiting peptide deformylase activity. As expected, S. aureus depletes the iron in the culture medium between the postexponential and stationary phases of growth. Inhibition of δ-toxin deformylation was relieved by TCA cycle inactivation or by addition of supplemental iron to the culture medium. Of interest, peptides containing formyl-methionine are potent chemoattractants for neutrophils, suggesting that δ-toxin deformylation may have functional consequences. We found neutrophil chemotactic activity only with formylated δ-toxin. The S. aureus TCA cycle is derepressed upon depletion of rapidly catabolizable carbon sources; this coincides with the transition to producing only formylated δ-toxin and results in an increased inflammatory response. The proinflammatory response should increase host cell damage and result in the release of nutrients. Taken together, these results establish that there is an important linkage between bacterial metabolism and pathogenesis.
The cognitive representation of filmic event summaries
2003-11-05

Abstract The present study compared two types of film summaries and a complete film event portrayal of two different event sequences, measuring their perceived structure during presentation and the subsequent ability to recall them. The summaries were based on the model of behavioural perception (Newtson &amp; Engquist, 1976; Zacks &amp; Tversky, 2001) and either retained the borders (breakpoints) or the middle parts (non‐breakpoints) of each segment of the event sequence. It was found that breakpoint‐keeping summaries were perceived to be more structured and were recalled more coherently and comprehensively than non‐breakpoint‐keeping summaries. On the other hand, breakpoint‐keeping summaries were not recalled any more completely than event portrayals that had not been shortened. Also, breakpoint‐keeping summaries showed only moderate overlap in their recalled event steps. Copyright © 2003 John Wiley &amp; Sons, Ltd.
Skeletal Muscle Cells from Insulin-resistant (Non-diabetic) Individuals are Susceptible to Insulin Desensitization by Palmitate
2003-11-07

We recently demonstrated that in vivo insulin resistance is not retained in cultured skeletal muscle cells. In the present study, we tested the hypothesis that treating cultured skeletal muscle cells with fatty acids has an effect on insulin action which differs between insulin-sensitive and insulin-resistant subjects. Insulin effects were examined in myotubes from 8 normoglycemic non-obese insulin-resistant and 8 carefully matched insulin-sensitive subjects after preincubation with or without palmitate, linoleate, and 2-bromo-palmitate. Insulin-stimulated glycogen synthesis decreased by 27 +/- 5 % after palmitate treatment in myotubes from insulin-resistant, but not from insulin-sensitive subjects (1.50 +/- 0.08-fold over basal vs. 1.81 +/- 0.09-fold, p = 0.042). Despite this observation, we did not find any impairment in the PI 3-kinase/PKB/GSK-3 pathway. Furthermore, insulin action was not affected by linoleate and 2-bromo-palmitate. In conclusion, our data provide preliminary evidence that insulin resistance of skeletal muscle does not necessarily involve primary defects in insulin action, but could represent susceptibility to the desensitizing effect of fatty acids and possibly other environmental or adipose tissue-derived factors.
Impact of glafenine hydrochloride on human endothelial cells and human vascular smooth muscle cells: a substance reducing proliferation, migration and extracellular matrix synthesis
2003-11-07

Abstract The aim of this study was to examine the effects of glafenine hydrochloride (a nonsteroidal anti‐inflammatory drug) on proliferation, clonogenic activity, cell‐cycle, migration, and the extracellular matrix protein tenascin of human aortic smooth muscle cells (haSMCs) and human endothelial cells (ECs) in vitro. HaSMCs and ECs were seeded in tissue culture flasks. The cells were treated for 4 days with glafenine hydrochloride (10 μM, 50 μM, 100 μM). Half of the treated groups were incubated again with glafenine hydrochloride, the other half received medium free of glafenine hydrochloride every 4 days until day 20. The growth kinetics and clonogenic activity were assessed. Cell cycle distribution was investigated by FACS, migratory ability was evaluated, and effects on extracellular matrix synthesis were assessed by immunofluorescence. Glafenine hydrochloride inhibited the proliferation and clonogenic activity of haSMCs and ECs in a dose‐dependent manner. A block in the G2/M phase and a reduction in the G1 phase occurred. The migratory ability of haSMCs was impaired in a dose‐dependent manner and the extracellular matrix protein tenascin was reduced. As glafenine hydrochloride has the ability to fully inhibit proliferation and to partially inhibit migration in haSMCs, it could be an interesting substance for further research in the field of restenosis therapy.
Regulation of the voltage gated K+ channel Kv1.3 by the ubiquitin ligase Nedd4‐2 and the serum and glucocorticoid inducible kinase SGK1
2003-11-10

Abstract The stimulation of cell proliferation by insulin like growth factor IGF‐1 has previously been shown to depend on activation of voltage gated K + channels. The signaling involved in activation of voltage gated K + channel Kv1.3 includes the phosphatidylinositol‐3 (PI3) protein kinase, 3‐phosphoinositide dependent protein kinase PDK1 and the serum and glucocorticoid inducible kinase SGK1. However, nothing is known about mechanisms mediating the stimulation of Kv1.3 by SGK1. Most recently, SGK1 has been shown to phosphorylate and thus inactivate the ubiquitin ligase Nedd4‐2. The present study has been performed to explore whether the regulation of Kv1.3 involves Nedd4‐2. To this end Kv1.3 has been expressed in Xenopus oocytes with or without coexpression of Nedd4‐2 and/or constitutively active S422D SGK1. In oocytes expressing Kv1.3 but not in water injected oocytes, depolarization from a holding potential of −80 mV to +20 mV triggers rapidly inactivating currents typical for Kv1.3. Coexpression of Nedd4‐2 decreases, coexpression of S422D SGK1 enhances the currents significantly. The effects of either Nedd4‐2 or of SGK1 are abrogated by destruction of the respective catalytic subunits ( C938S Nedd4‐2 or K127N SGK1). Further experiments revealed that wild type SGK1 and SGK3 and to a lesser extent SGK2 are similarly effective in stimulating Kv1.3 in both, presence and absence of Nedd4‐2. It is concluded that Kv1.3 is downregulated by Nedd4‐2 and stimulates by SGK1, SGK2, and SGK3. The data thus disclose a novel mechanism of Kv1.3 channel regulation. J. Cell. Physiol. 199: 194–199, 2004© 2003 Wiley‐Liss, Inc.
Complete structure determination of the A chain of mistletoe lectin III fromViscum albumL. ssp.album
2003-11-10

Abstract The complete primary structure of the A chain of mistletoe lectin III (ML3A), a type II ribosome‐inactivating protein, was determined using proteolytic digests of ML3A, HPLC separation of the peptides, Edman degration and MALDI‐MS. Based on our results, ML3A consists of 254 amino acid residues, showing a high homology to the A chain of isolectin ML1 with only 24 amino acid residue exchanges. A striking important structural difference compared with ML1A is the lack of the single N‐glycosylation site in ML3A due to an amino acid exchange at position 112 (ML1A: N 112 GS↠ML3A: T 112 GS). The alignment of ML3A with the A chains of ML1, isoabrins, ricin D, Ricinus communis agglutinin and three lectins, identified from the Korean mistletoe Viscum album ssp. coloratum , demonstrates the rigid conservation of all amino acid residues, responsible for the RNA‐N‐glycosidase activity as reported for ricin D. In addition, the fully determined primary structure of ML3A will give further information about the biological mechanism of mistletoe lectin therapy. Copyright © 2003 European Peptide Society and John Wiley &amp; Sons, Ltd.
Serum Levels of CD137 Ligand and CD178 are Prognostic Factors for Progression of Myelodysplastic Syndrome
2003-11-10

Excess apoptosis leading to ineffective hematopoiesis is a common feature of myelodysplastic syndrome (MDS). CD178 (Fas ligand/APO-1 ligand) and CD137 ligand (CD137L), 2 molecules involved in the regulation of apoptosis, have previously been found in sera of patients with malignancies and have been hypothesized to participate in the pathogenesis of various diseases. We analyzed sera of patients with MDS and found that while time to progression of MDS correlated with the IPSS score there was no correlation of CD137L or CD178 serum levels with this score or with karyotype, bone marrow blast count or cytopenia. However, when cut-off-values for significant differentiation between cases with higher/lower levels of these molecules were determined we found that high levels of soluble CD137L (sCD137L) and low serum levels of soluble CD178 (sCD178) correlate with statistical significance to rapid progression of disease as estimated by log-rank-test. Conversely, low levels of sCD137L and high levels of sCD178 correlate significantly with prolongation of time to progression of disease. Our results indicate that serum levels of sCD137L and sCD178 represent valuable novel indicators for prognosis and disease progression and may be a useful parameter for treatment decisions in patients with MDS.
Alterations in Fas (CD 95/Apo-1) and Fas Ligand (CD178) Expression in Acute Promyelocytic Leukemia during Treatment with ATRA
2003-11-10

Over the recent years, treatment of acute promyelocytic leukemia (APL) with all-trans retinoic acid (ATRA) has become a widely accepted therapeutic regimen and is considered a model of differentiation therapy in malignant diseases. However, the role of ATRA treatment beyond that of the induction of differentiation of leukemic blasts is still far from being fully understood. Data from in vivo and in vitro studies have demonstrated that during ATRA treatment of APL there are significant changes not only in the expression of the apoptotic molecules Fas and Fas ligand, but also in the expression of other molecules involved both in the regulation of apoptosis and in interactions between host immune and leukemia cells. These effects may thus contribute, at least in part, to the beneficial effects of ATRA therapy in APL. In this report we review the current status of studies that contribute to our understanding of treatment with ATRA. We focus on ATRA-induced changes in apoptotic pathways, particularly as it relates to the Fas/Fas ligand system.
Progressive pseudorheumatoid dysplasia: A rare disease in the differential diagnosis of juvenile idiopathic arthritis
2003-11-10

Introduction: Progressive pseudorheumatoid dysplasia (PPD) is an autosomal recessive skeletal disease. The responsible gene is called WISP3 and maps to the region 6q21 on chromosome 6. At the age of 3–6 years, stiffness and pain symmetrically involve finger joints first, later followed by hips and knees. Further symptoms are movement limitation, contractures and growth retardation. These symptoms are also found in juvenile idiopathic arthritis (JIA). Here we present one patient suffering from PPD. In this interactive poster, the different steps of this demanding differential diagnosis are explored.
Normal bone density but loss of muscle and abnormal bone geometry in juvenile idiopathic arthritis
2003-11-10

Introduction: Abnormalities of bone have been described in juvenile idiopathic arthritis (JIA). The techniques used in most studies do not allow a three dimensional measurement of bone density and cannot analyze bone geometry. The aim of this study was a detailed analysis of the musculoskeletal system in JIA by determination of bone density, bone geometry and muscle cross sectional area and strength as the most important factor in bone development and maintenance.
Lasting amelioration of spatial neglect by treatment with neck muscle vibration even without concurrent training
2003-11-11

Vibration of the left posterior neck muscles is a useful, non-invasive tool supplementing the established methods of spatial neglect treatment. It does not necessarily require the patient's co-operation, which is an important advantage especially in the early phases of rehabilitation.
Gene Transfer and Expression
2003-11-14

DNA transfection has become an important technique in molecular biology. The fusion of putative gene-regulatory sequences to reporter genes and their introduction into a eukaryotic cell can be used for a detailed analysis of cisacting DNA regulatory sequences (1). DNA regulatory elements such as those responsive to CAMP (2) or to glucocorticoids and antiglucocorticoids (3) as well as to drugs and xenobiotics such as phenobarbital (4, 5) can be identified through the use of approprtate reporter-gene constructs. Cotransfection experi-ments with vectors expressing specific transcription factors can be used to iden-tify the role of these transcription factors in the expression of specific genes (6) and in addition, the developmental activation of a promoter can be examined (7). The expression of functional protein in transfected cells can be useful for studies on genetic toxicology (8) or biochemical pathways (9). By the intro-duction of mutated DNAs that produce modified protems in the transfected cell, the functional significance of protein domains (10) and individual aminoacid residues (11, 12) can be elucidated, and the transfection of cDNAs isolated from patients has already proved useful for the analysis of molecular defects that result in genetic disorders (13).
Fluorogenic Substrates as Detectors of Caspase Activity During Natural Killer Cell-Induced Apoptosis
2003-11-14

Natural killer (NK) cells mediate target cell lysis by two independent pathways, one involving exocytosis of preformed granules (which contain perforin and granzymes A and B), the other requiring ligation of CD95 on target cells with CD95 (APO-1/Fas) ligand on the effector cell (, , ). Both processes lead to target cell apoptosis and lysis (). Perforin and granzymes A (and B) have been implicated as main contributors to membrane and/or nuclear disintegration of target cells by the secretory pathway (), whereas granzyme B and CD95 induce early DNA fragmentation by activation of multiple cysteine proteases of the caspase cascade, including caspase-8 (FLICE) () and caspase-3 (CPP32) (). The exact mechanisms governing NK-induced death are far more complicated than delineated herein, and the in vivo relevance of their different components require further study. The roles of KIR and class I major histocompatibility complex (MHC) in the effector/target interaction are described in other chapters of this book. Caspases (Cysteine-Aspart-ases) are key effector molecules involved in programmed cell death (PCD), although some of them can also participate in other physiological processes such as activation of proinflammatory cytokines. Since the discovery of the prototype death protease Ced-3 in Caenorhabditis elegans () more than 15 mammalian and invertebrate caspases have been described ().
Identification of Differentially Expressed Genes in Young and Senescent T Cells
2003-11-14

The need to analyze changes in gene expression patterns occuring in senescent cells has stimulated the search for proper methods to identify the actual differences between young and senescent cells. In studies of aging, differential display reverse transcriptase-polymerase chain reaction (DDRT-PCR) has already been applied successfully by several groups. Altered gene expression in young and senescent fibroblast cultures (1), human mammary epithelial cells (2), and rat brain cells (3, 4) has been detected with this technique.
Human T-Cell Clones
2003-11-14

Techniques for generating human T-cell clones (TCCs) were first described nearly two decades ago (1, 2). This was a direct consequence of the discovery of T-cell growth factor and the subsequent ability to propagate T-cells over extended periods (3). Early on, numerous publications in immunology indicated an apparently unlimited growth potential of normal mammalian T lymphocyte cultures; however, even at this time, other investigators challenged this conclusion (4, 5). Nonetheless, the possibility remained that at least some TCCs represented an exception to the rule of the Hayflick Limit for growth of normal somatic cells. If this were the case, the real relevance of replicative senescence as a universal phenomenon would be highly questionable. On the other hand, if those T-cells surviving apparently indefinitely were endowed with the properties of stem cells rather than differentiated cells, this quandary would be resolved. However, as far as could be judged, the apparently immortal TCCs described in the literature seemed to possess all the attributes of normal T-cells, not stem cells. Several explanations for this apparent paradox have been proposed, the most likely of which may be that such immortal lines are in fact abnormal. Few clones were tested for karyotypic or other abnormalities. Such analyses, when performed, often revealed genetic aberrations in human as well as murine clones (6, 7). In the case of murine cells, continuous cultures often transform spontaneously in culture, but in humans this is rare or absent.
Cutting Edge: Predetermined Avidity of Human CD8 T Cells Expanded on Calibrated MHC/Anti-CD28-Coated Microspheres
2003-11-15

Abstract Cytotoxic CD8 T cells are key effectors in the immunotherapy of malignant and viral diseases. However, the lack of efficient methods for their in vitro priming and expansion has become a bottleneck to the development of vaccines and adoptive transfer strategies. Synthetic artificial APCs (aAPCs) are now emerging as an attractive tool for eliciting and expanding CTL responses. We show that, by controlling the MHC density on aAPCs, high- or low-avidity tumor-directed human CTL lines can be raised effectively in vitro if costimulation via CD28 and IL-12 is provided. Compared with low-avidity CTL lines, high-avidity CTLs need 100- to 1000-fold less peptide for activation, bind more MHC tetramers, and, as expected, are superior in recognizing tumor cell lines expressing Ag. We believe that the possibility to raise Ag-specific T cells with predetermined avidity will be crucial for the future use of aAPCs in immunotherapeutical settings.
Cyclopentenone Prostaglandins Induce Lymphocyte Apoptosis by Activating the Mitochondrial Apoptosis Pathway Independent of External Death Receptor Signaling
2003-11-15

Abstract 15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is a naturally occurring cyclopentenone metabolite of PGD2 that possesses both peroxisome proliferator-activated receptor γ (PPAR-γ)-dependent and PPAR-γ-independent anti-inflammatory properties. Recent studies suggest that cyclopentenone PGs may play a role in the down-regulation of inflammation-induced immune responses. In this study, we report that 15d-PGJ2 as well as synthetic PPAR-γ agonists inhibit lymphocyte proliferation. However, only 15d-PGJ2, but not the specific PPAR-γ activators, induce lymphocyte apoptosis. We found that blocking of the death receptor pathway in Fas-associated death domain−/− or caspase-8−/− Jurkat T cells has no effect on apoptosis induction by 15d-PGJ2. Conversely, overexpression of Bcl-2 or Bcl-xL completely inhibits the initiation of apoptosis, indicating that 15d-PGJ2-mediated apoptosis involves activation of the mitochondrial pathway. In line with these results, 15d-PGJ2 induces mitochondria disassemblage as demonstrated by dissipation of mitochondrial transmembrane potential (Δψm) and cytochrome c release. Both of these events are partially inhibited by the broad spectrum caspase inhibitor benzyloxycarbonil-Val-Ala-Asp-fluoromethylketone, suggesting that caspase activation may amplify the mitochondrial alterations initiated by 15d-PGJ2. We also demonstrate that 15d-PGJ2 potently stimulates reactive oxygen species production in Jurkat T cells, and Δψm loss induced by 15d-PGJ2 is prevented by the reactive oxygen species scavenger N-acetyl-l-cysteine. In conclusion, our data indicate that cyclopentenone PGs like 15d-PGJ2 may modulate immune responses even independent of PPAR-γ by activating the mitochondrial apoptosis pathway in lymphocytes in the absence of external death receptor signaling.
Freeze-Fracture Studies of Cerebral Endothelial Tight Junctions
2003-11-15

AbstractThe tracer experiments of Reese and Karnovsky (1) demonstrated that it was the endothelium that formed a permeability barrier because electron-dense tracers such as horseradish peroxidase did not pass from the vessel lumen through the interendothelial cleft. The structure responsible for the lack of permeability of tracers was the tight junction. In endothelial cells, these specialized contact zones were already known from ultrastructural studies (2), and in epithelial cells, their morphology was described in detail by Farquhar and Palade (3).KeywordsFractal DimensionTight JunctionChoroid PlexusFracture PlaneEpithelial Tight JunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Granulocyte-Macrophage Colony-Stimulating Factor-Based Melanoma Cell Vaccines Immunize Syngeneic and Allogeneic Recipients via Host Dendritic Cells
2003-11-15

Abstract Subcutaneous injection of GM-CSF-expressing cancer cells into experimental animals results in protective cancer immunity. To delineate the mode of action of such vaccines, we used trinitrophenyl, the antigenic moiety of the contact allergen trinitrochlorobenzene, as surrogate Ag. Trinitrophenyl-derivatized bone marrow-derived dendritic cells were found to elicit a contact hypersensitivity response in syngeneic, but not in allogeneic recipients, compatible with their expected mode of direct Ag presentation. When expressing GM-CSF, haptenized M3 melanoma cells were also able to induce a contact hypersensitivity response but, in contrast to bone marrow-derived dendritic cells, not only in syngeneic but also in allogeneic recipients. This argues for a critical role of host APC. To identify their nature, we introduced the β-galactosidase (βgal) gene into M3-GM cells. Their administration activated βgal-specific, Ld-restricted CTL in syngeneic BALB/c mice. Evaluation of lymph nodes draining M3-GM-βgal injection sites revealed the presence of cells presenting the respective Ld-binding βgal peptide epitope. Based on their capacity to activate βgal-specific CTL, they were identified as being CD11c+ dendritic cells. These experiments provide a rational basis for the use of GM-CSF-based melanoma cell vaccines in an allogeneic setting.