bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Matrix Metalloproteinase Production Correlates with Immune Activation and Leukocyte Migration in Leprosy Reactional Lesions
Authors: Teles Rosane M. B. , Teles Rose B. , Amadeu Thais P. , Moura Danielle F. , Mendonça-Lima Leila , Ferreira Helen , Santos Ítalo M. C. F. , Nery José A. C. , Sarno Euzenir N. , Sampaio Elizabeth P. 
Published: December 2009

ABSTRACTGelatinases A and B (matrix metalloproteinase 2 [MMP-2] and MMP-9, respectively) can induce basal membrane breakdown and leukocyte migration, but their role in leprosy skin inflammation remains unclear. In this study, we analyzed clinical specimens from leprosy patients taken from stable, untreated skin lesions and during reactional episodes (reversal reaction [RR] anderythema nodosum leprosum[ENL]). The participation of MMPs in disease was suggested by (i) increased MMP mRNA expression levels in skin biopsy specimens correlating with the expression of gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α), (ii) the detection of the MMP protein and enzymatic activity within the inflammatory infiltrate, (iii) increased MMP levels in patient sera, and (iv) thein vitroinduction of MMP-9 byMycobacterium lepraeand/or TNF-α. It was observed that IFN-γ, TNF-α, MMP-2, and MMP-9 mRNA levels were higher in tuberculoid than lepromatous lesions. In contrast, interleukin-10 and tissue inhibitor of MMP (TIMP-1) message were not differentially modulated. These data correlated with the detection of the MMP protein evidenced by immunohistochemistry and confocal microscopy. When RR and ENL lesions were analyzed, an increase in TNF-α, MMP-2, and MMP-9, but not TIMP-1, mRNA levels was observed together with stronger MMP activity (zymography/in situzymography). Moreover, followingin vitrostimulation of peripheral blood cells,M. lepraeinduced the expression of MMP-9 (mRNA and protein) in cultured cells. Overall, the present data demonstrate an enhanced MMP/TIMP-1 ratio in the inflammatory states of leprosy and point to potential mechanisms for tissue damage. These results pave the way toward the application of new therapeutic interventions for leprosy reactions.
Shiga Toxin 1-Induced Inflammatory Response in Lipopolysaccharide-Sensitized Astrocytes Is Mediated by Endogenous Tumor Necrosis Factor Alpha
Authors: Landoni Verónica I. , de Campos-Nebel Marcelo , Schierloh Pablo , Calatayud Cecilia , Fernandez Gabriela C. , Ramos M. Victoria , Rearte Bárbara , Palermo Marina S. , Isturiz Martín A. 
Published: December 2009

ABSTRACTHemolytic-uremic syndrome (HUS) is generally caused by Shiga toxin (Stx)-producingEscherichia coli. Endothelial dysfunction mediated by Stx is a central aspect in HUS development. However, inflammatory mediators such as bacterial lipopolysaccharide (LPS) and polymorphonuclear neutrophils (PMN) contribute to HUS pathophysiology by potentiating Stx effects. Acute renal failure is the main feature of HUS, but in severe cases, patients can develop neurological complications, which are usually associated with death. Although the mechanisms of neurological damage remain uncertain, alterations of the blood-brain barrier associated with brain endothelial injury is clear. Astrocytes (ASTs) are the most abundant inflammatory cells of the brain that modulate the normal function of brain endothelium and neurons. The aim of this study was to evaluate the effects of Stx type 1 (Stx1) alone or in combination with LPS in ASTs. Although Stx1 induced a weak inflammatory response, pretreatment with LPS sensitized ASTs to Stx1-mediated effects. Moreover, LPS increased the level of expression of the Stx receptor and its internalization. An early inflammatory response, characterized by the release of tumor necrosis factor alpha (TNF-α) and nitric oxide and PMN-chemoattractant activity, was induced by Stx1 in LPS-sensitized ASTs, whereas activation, evidenced by higher levels of glial fibrillary acid protein and cell death, was induced later. Furthermore, increased adhesion and PMN-mediated cytotoxicity were observed after Stx1 treatment in LPS-sensitized ASTs. These effects were dependent on NF-κB activation or AST-derived TNF-α. Our results suggest that TNF-α is a pivotal effector molecule that amplifies Stx1 effects on LPS-sensitized ASTs, contributing to brain inflammation and leading to endothelial and neuronal injury.
Klebsiella pneumoniae
Capsule Polysaccharide Impedes the Expression of β-Defensins by Airway Epithelial Cells
Authors: Moranta David , Regueiro Verónica , March Catalina , Llobet Enrique , Margareto Javier , Larrate Eider , Garmendia Junkal , Bengoechea José A. 
Published: December 2009

ABSTRACT

Human β-defensins (hBDs) contribute to the protection of the respiratory tract against pathogens. It is reasonable to postulate that pathogens have developed countermeasures to resist them.
Klebsiella pneumoniae
capsule polysaccharide (CPS), but not the lipopolysaccharide O antigen, mediated resistance against hBD1 and hBD2. hBD3 was the most potent hBD against
Klebsiella
. We investigated the possibility that as a strategy for survival in the lung,
K. pneumoniae
may not activate the expression of hBDs. Infection of A549 and normal human bronchial cells with 52145-Δ
wca
K2
, a CPS mutant, increased the expression of hBD2 and hBD3. Neither the wild type nor the lipopolysaccharide O antigen mutant increased the expression of hBDs.
In vivo
, 52145-Δ
wca
K2
induced higher levels of mBD4 and mBD14, possible mouse orthologues of hBD2 and hBD3, respectively, than the wild type. 52145-Δ
wca
K2
-dependent upregulation of hBD2 occurred via NF-κB and mitogen-activated protein kinases (MAPKs) p44/42, Jun N-terminal protein kinase (JNK)-dependent pathways. The increase in hBD3 expression was dependent on the MAPK JNK. 52145-Δ
wca
K2
engaged Toll-like receptors 2 and 4 (TLR2 and TLR4) to activate hBD2, whereas hBD3 expression was dependent on NOD1.
K. pneumoniae
induced the expression of CYLD and MKP-1, which act as negative regulators for 52145-Δ
wca
K2
-induced expression of hBDs. Bacterial engagement of pattern recognition receptors induced CYLD and MKP-1, which may initiate the attenuation of proinflammatory pathways. The results of this study indicate that
K. pneumoniae
CPS not only protects the pathogen from the bactericidal action of defensins but also impedes their expression. These features of
K. pneumoniae
CPS may facilitate pathogen survival in the hostile environment of the lung.
Cigarette Smoke Exposure Impairs Pulmonary Bacterial Clearance and Alveolar Macrophage Complement-Mediated Phagocytosis of
Streptococcus pneumoniae
Authors: Phipps John C. , Aronoff David M. , Curtis Jeffrey L. , Goel Deepti , O'Brien Edmund , Mancuso Peter 
Published: December 2009

ABSTRACT

Cigarette smoke exposure increases the risk of pulmonary and invasive infections caused by
Streptococcus pneumoniae
, the most commonly isolated organism from patients with community-acquired pneumonia. Despite this association, the mechanisms by which cigarette smoke exposure diminishes host defense against
S. pneumoniae
infections are poorly understood. In this study, we compared the responses of BALB/c mice following an intratracheal challenge with
S. pneumoniae
after 5 weeks of exposure to room air or cigarette smoke in a whole-body exposure chamber
in vivo
and the effects of cigarette smoke on alveolar macrophage phagocytosis of
S. pneumoniae in vitro
. Bacterial burdens in cigarette smoke-exposed mice were increased at 24 and 48 h postinfection, and this was accompanied by a more pronounced clinical appearance of illness, hypothermia, and increased lung homogenate cytokines interleukin-1β (IL-1β), IL-6, IL-10, and tumor necrosis factor alpha (TNF-α). We also found greater numbers of neutrophils in bronchoalveolar lavage fluid recovered from cigarette smoke-exposed mice following a challenge with heat-killed
S. pneumoniae
. Interestingly, overnight culture of alveolar macrophages with 1% cigarette smoke extract, a level that did not affect alveolar macrophage viability, reduced complement-mediated phagocytosis of
S. pneumoniae
, while the ingestion of unopsonized bacteria or IgG-coated microspheres was not affected. This murine model provides robust additional support to the hypothesis that cigarette smoke exposure increases the risk of pneumococcal pneumonia and defines a novel cellular mechanism to help explain this immunosuppressive effect.
Toll-Like Receptor 4 Signaling Leads to Severe Fungal Infection Associated with Enhanced Proinflammatory Immunity and Impaired Expansion of Regulatory T Cells
Authors: Loures Flávio V. , Pina Adriana , Felonato Maíra , Araújo Eliseu F. , Leite Katia R. M. , Calich Vera L. G. 
Published: December 2009

ABSTRACTToll-like receptors (TLRs) present in innate immune cells recognize pathogen molecular patterns and influence immunity to control the host-parasite interaction. The objective of this study was to characterize the involvement of TLR4 in the innate and adaptive immunity toParacoccidioides brasiliensis, the most important primary fungal pathogen of Latin America. We compared the responses of C3H/HeJ mice, which are naturally defective in TLR4 signaling, with those of C3H/HePas mice, which express functional receptors, afterin vitroandin vivoinfection withP. brasiliensis. Unexpectedly, we verified that TLR4-defective macrophages infectedin vitrowithP. brasiliensispresented decreased fungal loads associated with impaired synthesis of nitric oxide, interleukin-12 (IL-12), and macrophage chemotactic protein 1 (MCP-1). After intratracheal infection with 1 million yeasts, TLR4-defective mice developed reduced fungal burdens and decreased levels of pulmonary nitric oxide, proinflammatory cytokines, and antibodies. TLR4-competent mice produced elevated levels of IL-12 and tumor necrosis factor alpha (TNF-α), besides cytokines of the Th17 pattern, indicating a proinflammatory role for TLR4 signaling. The more severe infection of TLR4-normal mice resulted in increased influx of activated macrophages and T cells to the lungs and progressive control of fungal burdens but impaired expansion of regulatory T cells (Treg cells). In contrast, TLR4-defective mice were not able to clear their diminished fungal burdens totally, a defect associated with deficient activation of T-cell immunity and enhanced development of Treg cells. These divergent patterns of immunity, however, resulted in equivalent mortality rates, indicating that control of elevated fungal growth mediated by vigorous inflammatory reactions is as deleterious to the hosts as low fungal loads inefficiently controlled by limited inflammatory reactions.
Photoprotective mechanisms during leaf ontogeny: cuticular development and anthocyanin deposition in two morphs of Agave striata that differ in leaf coloration
Authors: Fondom Nicolas Y. , Castro-Nava Sergio , Huerta Alfredo J. 
Published: December 2009

Our objectives were to test whether in Agave striata Zucc., a plant with crassulacean acid metabolism (CAM plant), leaf wax development is a delayed response to sunlight exposure following cutin development, and whether energy dissipation shifts from non-photochemical quenching to photochemical quenching during leaf ontogeny. Under field conditions, photosynthesis, cuticular development, and anthocyanin deposition were studied in two morphs of A. striata that differ in leaf coloration (green vs. red). We quantified leaf anthocyanin, wax, and cutin content, and also measured chlorophyll a fluorescence and leaf surface temperature. In addition, using three leaf reflectance indices, we measured relative chlorophyll and anthocyanin content, and also xanthophyll-cycle de-epoxidation state (xanthophyll conversion). Our results revealed that the main components of cuticle (wax and cutin) in leaves of A. striata are deposited during different developmental windows, which are similar to leaves of monocots such as grasses. Exposure to sunlight was found to be the most likely candidate to affect wax and anthocyanin deposition. Chlorophyll a fluorescence data revealed that the sunlight conditions experienced by both morphs predisposed the young leaves of the green morph and old leaves of both morphs to photoinhibition. Our results also revealed that old leaves of the red morph, which contain a reduced level of chlorophyll and anthocyanin, had additional photoprotection via xanthophyll conversion. The results presented here support the photoprotective function of leaf anthocyanins and wax accumulation during leaf ontogeny, indicating that their presence may compensate for the reduced dependence of non-photochemical quenching and the xanthophyll-cycle pigment conversion.
The mycoheterotroph Arachnitis uniflora has a unique association with arbuscular mycorrhizal fungi
Authors: Domínguez Laura S. , Melville Lewis , Sérsic Alicia , Faccio Antonella , Peterson R. Larry 
Published: December 2009

Achlorophyllous plants that are dependent on an association with fungi linked to photosynthetic plants for their carbon source are known as mycoheterotrophs. Arachnitis uniflora Phil., a monotypic member of the monocotyledonous family Corsiaceae, fits this category, as it relies on a glomalean fungus belonging to Glomus Group A for carbon acquisition. Although basic structural features of root colonization have been reported for A. uniflora, the nutrient exchange interface has not been studied. This is the first study to use confocal microscopy, transmission electron microscopy, and cytochemical procedures to study the interface between a glomalean fungus and the roots of a mycoheterotrophic species. Results showed that arbuscules are never formed, and that the “vesicles in bundles” reported earlier are unlike typical glomalean vesicles, in that they form in clusters by the enlargement of hyphal branches and have a complex multilayered wall. The thick inner wall layer consists primarily of β-1,3-glucans (callose) and is surrounded by a thin outer layer of chitin. Each structure is surrounded by host cell wall material and a perifungal membrane, suggesting an involvement in nutrient exchange. The cytoplasm contains a complex of small β-1,3-glucan-containing vacuoles, lipid bodies, endobacteria, and many nuclei. These structures enlarge to occupy most of the cortical cell volume and then degrade, releasing lipids and other materials into the host cell. We suggest that these structures should not be equated with typical glomalean vesicles but are unique structures that may be involved, along with the hyphal coils, in nutrient acquisition by the host.
Effect of cold temperatures on properties of unfrozen Troll clay
Authors: Perkins Steven W. , Sjursen Morten 
Published: December 2009

Oedometer and triaxial experiments have been performed on North Sea Troll clay previously warmed to room temperature and tested at both room temperature and 0 °C to assess the effect of cold temperature on undrained strength and consolidation properties. In general, both the undrained strength and preconsolidation pressure increase as the temperature decreases. Many subsea areas of development in extreme northern or southern latitudes experience seafloor temperatures continuously around 0 °C. These results suggest that conventional laboratory testing at room temperature of samples from these areas leads to an underestimation of strength and preconsolidation pressure. Therefore, additional testing is recommended to assess the effect of a warming and cooling cycle on strength and consolidation properties, as previous work suggests that some consolidation is induced by this temperature cycle and may be responsible for the ensuing strength gain.
Wave-induced shallow slides and their features on the subaqueous Yellow River delta
Authors: Xu Guohui , Sun Yongfu , Wang Xin , Hu Guanghai , Song Yupeng 
Published: December 2009

Slope instability processes occur widely on the underwater slopes of the Yellow River delta during storms. Roughly circular depressions on the upper delta front in water depths of 4 to 8 m have been detected by acoustic surveying and their processes were observed in the laboratory. This paper analyzes the properties of geomorphic and acoustic profiles of the upper delta front and compares the engineering geologic properties of samples from the disturbed and undisturbed areas. The results indicate that the weak superficial mass could oscillate with waves and the oscillation weakened the surrounding soil under the cyclic loading. The stratum was disturbed or even destroyed with depth, the area of the slide mass enlarged gradually, and finally a collapse depression formed.
STABILITY SWITCHES IN DISCRETE FOOD-CHAIN PROBLEMS
Authors: LINDSTRÖM TORSTEN 
Published: December 2009

In an already classical paper, May [1976] pointed out that simple nonlinear models in ecology can possess complicated dynamics. A long debate concerning the possible existence of chaotic ecologies has followed the appearance of this paper. Morris [1990] stressed that several problems exist when making conclusions regarding chaotic or nonchaotic dynamics as models are fitted to ecological data. Takens' theorem [1981] should, in principle, provide tools for solving some of these problems, but in reality essential assertions are most often violated. First, limits regarding the length of the used time-series must be assumed. Second, the theorem can be applied for evaluating positive Lyapunov exponents only, and is hence not applicable for distinguishing nonchaotic dynamics from chaotic.We use a deterministic food-chain model that possesses a wide range of different dynamical patterns to demonstrate the existence of cases that are misclassified with respect to chaotic or nonchaotic motion as models are fitted to data in the various dynamical regimes. Our results are valid regardless of what finite data size is assumed. The results are best understood for high-periodic cases in the noise-free limit. If the relevant phase-space is not sufficiently well-populated with data in the vicinity of the periodic orbit, then sufficient complexity of the models are not supported by standard model selection criteria like AIC or GCV. Thus, the fitted models only in the best cases contain information concerning both the location of the periodic orbit and the eigenvalues of the Jacobians evaluated along the periodic orbit. If the space is moderately well populated with data, then the data is often described by an unstable periodic orbit of the fitted model. The attractor that was to be described by the fitted model was destabilized and is now a repeller. We call this phenomenon stability switches. It reminds about the noise-induced phenomenon reported by Rand and Wilson [1992], but we point out that the problem reported here is caused by the fitting procedure itself, not by the added noise.The repeller that has been created by the model-fitting procedure can be located in the basins of attraction of some fixed point, the infinity, or some periodic or chaotic attractors of the fitted models. The situation seems similar when periodic attractors are not well enough populated with data for describing their location and when chaotic attractors are to be described by data. Similar stability switches occur and the dynamics of models fitted to data may differ or coincide with the dynamics of the attractor that generated the data in an unpredictable manner.
Plant assemblages from SW Gondwana: further evidence for high-latitude vegetation in the Devonian of Argentina
Authors: Edwards D. , Poiré D. G. , Morel E. M. , Cingolani C. A. 
Published: December 2009

Abstract

Plant assemblages are described from the Talacasto and Punta Negra Formations, San Juan Province, the Argentine Precordillera. A detailed facies study involving trace fossil assemblages indicates that the plants were buried in shallow low- to high-energy marine environments, but not in turbidites as previously postulated. Apart from a single specimen resembling
Cooksonia
from the Lochkovian Talacasto Formation, the abundant compression fossils consist of short lengths of smooth axes, occasional defoliated lycopod stems, and very rare isolated sporangia. It is thus impossible to assign any to existing taxa with confidence nor are there sufficient distinguishing characters to erect new ones. Although the possible age of the formations in the Precordillera remains conjectural, the fossils themselves, even preserved in such fragmentary states, indicate much lower grades of organization than seen in coeval assemblages elsewhere, particularly on the Laurussian and South China palaeocontinents. Palaeocontinental reconstructions of Gondwana indicate that the localities are within 30° of the palaeo South Pole. Thus a global latitudinal gradient in vegetation is postulated for the Early Devonian with decreasing disparity and diversity at higher latitudes. An explanation for the latter is explored in terms of light regime and temperature in highly stressed environments.
Gondwanan faunal signatures from Early Palaeozoic terranes of Kazakhstan and Central Asia: evidence and tectonic implications
Authors: Popov Leonid E. , Bassett Michael G. , Zhemchuzhnikov Vyacheslav G. , Holmer Lars E. , Klishevich Inna A. 
Published: December 2009

Abstract
Two separate tectonic blocks in the southwestern segment of the Kazakhstanian orogen, the Chu–Ili terrane and the Karatau–Naryn terrane (with particular attention to Malyi Karatau), are selected to illustrate their geological history and major biogeographical signatures from the Cambrian to the early Silurian. Mid- to Late Ordovician brachiopod and trilobite faunas of Chu–Ili show increased endemicity of shallow shelf assemblages, whereas distinct links to equatorial (‘east’) peri-Gondwanan are more evident in trilobite assemblages of the outer shelf. In the Late Ordovician, strong biogeographical affinities to equatorial Gondwanan faunas became firmly established and they are also traceable into the Silurian. Early Cambrian faunas of Malyi Karatau show remarkable similarity to those of South China. From the Middle Cambrian this region evolved as an isolated carbonate seamount, but until the Early Ordovician links to South China faunas were still evident. Benthic faunas from both regions show weak links to contemporaneous faunas of Baltica and little in common with Cambrian and Ordovician faunas of the Siberian craton. This suggests their location in low southern latitudes, in relative proximity to East Gondwana, which places some constraints on plate-tectonic reconstructions in relation to the southern cluster of Kazakhstanian terranes, including Karatau–Naryn, North Tien Shan and Chu–Ili.
The ‘microcontinent’ Perunica: status and story 15 years after conception
Authors: Fatka Oldřich , Mergl Michal 
Published: December 2009

Abstract
Central Europe consists of a complex mosaic of more or less independent terranes with varying tectonometamorphic histories, usually also of different lithological compositions and protolith, and thus it is reasonable to suppose that the majority of these blocks have experienced somewhat different palaeogeographical evolution. The present terrane juxtaposition has been interpreted in general as a result of the Variscan collision of peri-Gondwanan and peri-Baltic derived terranes, with Gondwana on one side and Baltica and/or Laurentia on the other side. However, reconstruction of the pre-Variscan development and mutual palaeogeographical relationships remains a major challenge of interpretation.