ACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2009
Preethi Ragunathan
Adhesion/invasion of pathogenic bacteria is a critical step in infection and is mediated by surface-exposed proteins termed adhesins. The crystal structure of recombinant Lmb, a laminin-binding adhesin from Streptococcus agalactiae, has been determined at 2.5,Å resolution. Based on sequence and structural homology, Lmb was placed into the cluster 9 family of the ABC (ATP-binding cassette) transport system. The structural organization of Lmb closely resembles that of ABC-type solute-binding proteins (SBPs), in which two structurally related globular domains interact with each other to form a metal-binding cavity at the interface. The bound zinc in Lmb is tetrahedrally coordinated by three histidines and a glutamate from both domains. A comparison of Lmb with other metal transporters revealed an interesting feature of the dimerization of molecules in the crystallographic asymmetric unit in all zinc-binding transporters. A closer comparison of Lmb with the zinc-binding ZnuA from Escherichia coli and Synechocystis 6803 suggested that Lmb might undergo a unique structural rearrangement upon metal binding and release. The crystal structure of Lmb provides an impetus for further investigations into the molecular basis of laminin binding by human pathogens. Being ubiquitous in all serotypes of group B streptococcus (GBS), the structure of Lmb may direct the development of an efficient vaccine. [source]

EARLY GASTRIC CANCER WITH WIDESPREAD DUODENAL INVASION WITHIN THE MUCOSA

DIGESTIVE ENDOSCOPY, Issue 3 2010
Tsutomu Namikawa
We report a rare case of early gastric cancer confined to the mucosal layer with extensive duodenal invasion, curatively removed with distal gastrectomy. An 84-year-old Japanese woman was referred to our hospital with gastric cancer. A barium meal examination and esophagogastroduodenoscopy revealed an irregular nodulated lesion measuring 6.5 x 5.5 cm in the gastric antrum and an aggregation of small nodules in the duodenal bulb. A biopsy specimen showed well-differentiated adenocarcinoma. The patient underwent distal gastrectomy with partial resection of the duodenal region containing the tumor and regional lymph node dissection, with no complication. Histological examination of the resected tissue confirmed well-differentiated adenocarcinoma limited to the mucosal layer and without lymph node metastasis. The cancer extended into the duodenum as far as 38 mm distant from the pyloric ring, and the resected margins were free of cancer cells. Gastric cancer located adjacent to the pyloric ring thus has the potential for duodenal invasion, even when tumor invasion is confined to the mucosal layer. In such cases, care should be taken during examinations to detect duodenal invasion, and the distal surgical margin must be negative given sufficient duodenal resection. [source]

WATER QUALITY IMPACTS AND INDICATORS OF METABOLIC ACTIVITY OF THE ZEBRA MUSSEL INVASION OF THE SENECA RIVER,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2004
Steven W. Effler
ABSTRACT: The conspicuous shifts in summertime values of common measures of water qualify that have persisted for 10 years (1993 to 2002) in the Seneca River, New York, as a result of the zebra mussel invasion are documented. Resolution of patterns in time and space is supported by water quality monitoring that extends back to the late 1970s. Patterns are evaluated to describe the stability of impacts and quantify metabolic activity of the invader. The water quality impacts that have persisted unabated for 10 years since the invasion are the most severe documented for a river in North America. Changes in summer median conditions since the invasion include: (1) a 16-fold decrease in chlorophyll concentration (Chi), (2) a 2.5-fold increase in Secchi disc transparency, (3) a 17-fold increase in soluble reactive phosphorus concentration, (4) a 3.7-fold increase in total ammonia concentration, (5) a greater than 25 percent decrease in dissolved oxygen (DO) concentration, and (6) a decrease in pH of 0.55 units. The strength of these signatures has been driven by anthropogenic influences that include upstream nutrient loading and morphometric modifications of the river, and the functioning of Cross Lake, through which the river flows. This hypereutrophic lake sustains dense zebra mussel populations and related water quality impacts in the river downstream of the lake outflow by acting as a source of veligers and suitable food for this bivalve. Evidence is presented that levels of metabolic activity of the zebra mussel in this river have been resource limited, manifested through increased consumption of Chl and DO with increased delivery of these constituents in the lake's outflow. [source]

HP37 PROGNOSTIC FACTORS IN OESOPHAGEAL CANCER: NUMBER OF LYMPH NODES AND EXTRACAPSULAR LYMPH NODE INVASION , AN INTERIM ANALYSIS

ANZ JOURNAL OF SURGERY, Issue 2007
S. K. Thompson
Purpose Controversy exists over the 2nd edition of the TNM staging system introduced by the American Joint Committee in Cancer in 1988, and revised in 2002. Prognostic pathological factors such as the number of positive lymph nodes and any extracapsular lymph node invasion may refine this current staging system and optimize patient treatment. Methodology All patients who underwent surgical resection for oesophageal cancer were identified in a prospectively-maintained database. Patients without invasive adenocarcinoma or squamous cell cancer were excluded. Pathology slides were reviewed by a single pathologist. Survival data was calculated using Kaplan-Meier curves, and prognostic factors were examined using the log rank test. Results 235 surgical specimens met inclusion criteria, and 95 specimens have been reviewed so far. The 5-yr overall survival rate was 43% (median 31.4 months). Subdividing pN-stage into 1,2 positive nodes and >2 positive nodes showed significant differences in 5-yr survival between both groups: 41% vs. 6.0%, respectively (P = 0.0003). Similarly, including absence and presence of extracapsular lymph node invasion into our pathology review showed significant differences in 5-yr survival: 40% vs. 7.8%, respectively (P < 0.01). A negative circumferential margin, and the absence of both vascular and perineural invasion were also found to significantly improve survival rates. Conclusions The number and characteristics of metastatic invasion of lymph nodes should be included in current oesophageal cancer staging systems. Clinicians will then have more accurate prognostic information, and treatment can be better tailored to patients' needs. [source]

GRADUAL VERSUS PUNCTUATED EQUILIBRIUM EVOLUTION IN THE TURKANA BASIN MOLLUSCS: EVOLUTIONARY EVENTS OR BIOLOGICAL INVASIONS?

EVOLUTION, Issue 3 2008
Bert Van Bocxlaer
A running controversy in evolutionary thought was Eldredge and Gould's punctuated equilibrium model, which proposes long periods of morphological stasis interspersed with rapid bursts of dramatic evolutionary change. One of the earliest and most iconic pieces of research in support of punctuated equilibrium is the work of Williamson on the Plio-Pleistocene molluscs of the Turkana Basin. Williamson claimed to have found firm evidence for three episodes of rapid evolutionary change separated by long periods of stasis in a high-resolution sequence. Most of the discussions following this report centered on the topics of (eco)phenotypy versus genotypy and the possible presence of preservational and temporal artifacts. The debate proved inconclusive, leaving Williamson's reports as one of the empirical foundations of the paradigm of punctuated equilibrium. Here we conclusively show Williamson's original interpretations to be highly flawed. The supposed rapid bursts of punctuated evolutionary change represent artifacts resulting from the invasion of extrabasinal faunal elements in the Turkana palaeolakes during wet phases well known from elsewhere in Africa. [source]

SEAWEED INVASIONS: A SYNTHESIS OF ECOLOGICAL, ECONOMIC AND LEGAL IMPERATIVES

JOURNAL OF PHYCOLOGY, Issue 2 2010
Michael H. Graham
No abstract is available for this article. [source]

Susceptibility of a Northern Hardwood Forest to Exotic Earthworm Invasion

CONSERVATION BIOLOGY, Issue 4 2005
MICHAEL J. GUNDALE
Acer saccharum; Bosque Nacional Ottawa; lombrices invasoras; Sylvania Wilderness Area; uso del suelo Abstract:,Numerous exotic earthworm species are colonizing northern hardwood forests of North America, where no native earthworms exist. Upon invasion, earthworms have been shown to alter the surface soil environment and plant populations and communities. We sought to identify land-use factors in the Ottawa National Forest (ONF), Michigan (U.S.A.), that contribute to earthworm invasion in forest dominated by sugar maple (Acer saccharum Marsh.) so that the susceptibility to additional colonization could be evaluated. We sampled earthworm communities in Sylvania Wilderness Area, a unique old-growth hardwood forest, and nonwilderness sites influenced by recreational fishing, recent timber harvesting, or roads. All the nonwilderness sites contained one to five species of exotic earthworms. In contrast, only 50% of wilderness sites contained exotic earthworms, all of a single species. Nonwilderness sites also had thinner litter and duff layers, higher soil C and N content, and higher nitrogen mineralization potentials than Sylvania sites. Two central differences between Sylvania and nonwilderness sites were that all nonwilderness sites were in close contact with roads and had a history of timber harvest, whereas these factors were not present in Sylvania Wilderness Area. Using average rates of colonization, we constructed two geographic information system models to estimate the percentage of sugar maple on the ONF falling within a theoretical 100-year invasion distance of roads and of second-growth sugar maple as relative indices of susceptibility to invasion. Both models indicated high susceptibility to invasion, with 91.7% and 98.9% of sugar maple habitat falling within a theoretical 100-year invasion distance of roads or historical harvests, respectively. Resumen:,Numerosas especies de lombrices exóticas están colonizando los bosques boreales, en los que previamente no existían lombrices terrestres nativas. Por encima de la invasión, se ha demostrado que las lombrices alteran el ambiente superficial del suelo, así como a las comunidades y poblaciones de plantas. Tratamos de identificar factores de uso del suelo en el Bosque Nacional Ottawa (BNO), Michigan, E. U. A., que contribuyen a la invasión de lombrices en bosques dominados por arces (Acer saccharum Marsh.), para poder evaluar la susceptibilidad a futuras invasiones. Muestreamos comunidades de lombrices en Sylvania Wilderness Area, un bosque maduro único, y en sitios no silvestres influenciados por pesca deportiva, cosecha reciente de madera o caminos. Todas las áreas no silvestres contenían 1 - 5 especies de lombrices exóticas. En contraste, solo 50% de los sitios silvestres contenían lombrices exóticas, todas de una sola especie. Los sitios no silvestres también tenían capas de hojarasca y de mantillo más delgadas, mayor contenido de C y N del suelo y mayor potencial de mineralización del nitrógeno que los sitios en Sylvania. Dos diferencias centrales entre Sylvania y los sitios no silvestres fueron que estos estaban en contacto cercano con caminos y tenían una historia de cosecha de madera, mientras que estos factores no estuvieron presentes en Sylvania Wilderness Area. Utilizando tasas promedio de colonización, construimos dos modelos de sistemas de información geográfica para estimar el porcentaje de arces en el BNO que queda a una distancia teórica de invasión en 100 años; con caminos y arce de crecimiento secundario como índices relativos de susceptibilidad a la invasión. Ambos modelos indicaron alta susceptibilidad a la invasión, con 91.7% y 98.9% del hábitat de arce dentro de la distancia teórica de invasión en 100 años o con cosechas históricas, respectivamente. [source]

Diameter of Involved Nerves Predicts Outcomes in Cutaneous Squamous Cell Carcinoma with Perineural Invasion: An Investigator-Blinded Retrospective Cohort Study

DERMATOLOGIC SURGERY, Issue 12 2009
AMY S. ROSS MD
BACKGROUND Perineural invasion (PNI) has been associated with poor prognosis in cutaneous squamous cell carcinoma (CSCC), but it is unclear how different degrees of nerve involvement affect prognosis. OBJECTIVE To determine whether the diameter of nerves invaded by CSCC affects outcomes of recurrence, metastasis, and disease-specific and overall survival. METHODS A retrospective cohort study was conducted of patients with CSCC with PNI. Dermatopathologists blinded to subject outcomes determined the diameter of the largest involved nerve. RESULTS Data were obtainable for 48 patients. Small-caliber nerve invasion (SCNI) of nerves less than 0.1 mm in diameter was associated with significantly lower risks of all outcomes of interest. Disease-specific death was 0% in subjects with SCNI, versus 32% in those with large-caliber nerve invasion (LCNI) (p=.003). Other factors associated with significantly worse survival were recurrent or poorly differentiated tumors or tumor diameter of 2 cm or greater or depth of 1 cm or greater. On multivariate analysis, only tumor diameter and age predicted survival. CONCLUSIONS The individual prognostic significance of factors associated with poor survival remains uncertain. Small-caliber nerve invasion may not adversely affect outcomes. Defining PNI as tumor cells within the nerve sheath and routine recording of diameter of involved nerves, tumor depth, and histologic differentiation on pathology reports will facilitate further study. [source]

Basal Cell Carcinoma Associated with Orbital Invasion: Clinical Features and Treatment Options

DERMATOLOGIC SURGERY, Issue 3 2006
SHANNA B. MEADS MD
First page of article [source]

p75NGFR Immunostaining for the Detection of Perineural Invasion by Cutaneous Squamous Cell Carcinoma

DERMATOLOGIC SURGERY, Issue 2 2006
REBECCA LEWIS KELSO MD
BACKGROUND Perineural invasion (PNI) in cutaneous squamous cell carcinoma (CSCC) may portend a poor prognosis for patients. p75NGFR (nerve growth factor receptor) is part of a membrane receptor complex that binds nerve growth factor. Its use for detecting PNI in CSCC in comparison to S-100 immunohistochemical staining has not been explored. OBJECTIVE To determine whether detection of PNI may be improved by staining with p75NGFR as compared with hematoxylin and eosin (H&E) and S-100. METHODS Thirty-four cases of CSCC were retrospectively evaluated for the presence of PNI using standard H&E as well as S-100 and p75NGFR immunohistochemical stains. Staining intensity was correlated to the presence or absence of PNI and tumor differentiation. RESULTS Results showed a positive correlation between staining intensity and the presence of PNI detected by p75NGFR (p=.04). Using p75NGFR allowed for the detection of seven cases of PNI not detected by H&E alone. Five of these cases were detected by S-100, with two cases seen by p75NGFR only. Six cases of PNI were detected using S-100 not seen on H&E, with one case also not seen using p75NGFR. CONCLUSION p75NGFR immunostaining increased detection of PNI compared with H&E. p75NGFR could serve as an alternative to S-100 in the detection of PNI, or as part of an immunostaining panel for PNI detection. [source]

Multiply Recurrent Trichilemmal Carcinoma With Perineural Invasion and Cytokeratin 17 Positivity

DERMATOLOGIC SURGERY, Issue 8 2003
Julie E. Allee MD
Background. Trichilemmal carcinoma is an uncommon cutaneous malignancy that is thought to be the malignant counterpart of the trichilemmoma. Despite histologic features such as pronounced cytologic atypia, trichilemmal carcinoma is often described as having a rather benign clinical course. Cases of tumor recurrence after therapy are uncommon, and tumor neurotropism has never been described. objective. A case of multiply recurrent trichilemmal carcinoma with perineural invasion is described. The outer root sheath differentiation of this neoplasm is confirmed with the use of novel antibodies directed toward cytokeratins that are expressed in this area of the hair follicle. Methods. The trichilemmal carcinoma was excised using the Mohs surgical technique. Tissue obtained during the extirpation of the tumor was subjected to immunohistochemical staining for cytokeratin 15, cytokeratin 17, and c-erb-B2. Results. Tumor neurotropism was noted. The trichilemmal carcinoma demonstrated abundant cytoplasmic staining for cytokeratin 17 and c-erb-B2. Conclusions. In distinction to previous reports, this case reveals that trichilemmal carcinoma can demonstrate significant biological aggression, as reflected by tumor neurotropism and by failure to respond to multiple surgical excisions. The purported outer root sheath differentiation of this neoplasm is confirmed with the use of novel immunohistochemical staining. This immunohistochemical staining may be useful in differentiating trichilemmal carcinoma from other clear cell neoplasms. [source]

Bilateral Auricular Squamous Cell Carcinomas with Perineural Invasion

DERMATOLOGIC SURGERY, Issue 2 2001
Stacy Russell Beaty BA
Background. Bilateral squamous cell carcinoma (SCC) of the external ears is a rare phenomenon, and we are unaware of instances of bilateral perineural involvement. Objective. To describe bilateral auricular SCCs, each with perineural invasion. Methods. Case report and literature review. Results. Histopathologic examination revealed perineural invasion in both tumors. Conclusion. This appears to be an unusual presentation of bilateral auricular SCCs with perineural invasion in an elderly immunocompromised patient. [source]

Invasion of Agave species (Agavaceae) in south-east Spain: invader demographic parameters and impacts on native species

DIVERSITY AND DISTRIBUTIONS, Issue 5-6 2004
Ernesto I. Badano
ABSTRACT Several mechanisms have been proposed to explain the success of invasive species in new environments. A species may become invasive when a new site provides the potential for positive rates of population growth. This may be the case of several Agave species introduced to Spain in the 1940s. In this paper we document factors that promote large increases of populations of these species, and their effects on native plant communities in two sites of SE Spain. Results showed higher rhizome and bulbil production, and higher establishment rates by agaves in sandy soils than in clay soils. In their native habitats, agaves have low establishment rates and sandy soils are rare. This suggests that sandy soils are an opportunity which releases the clonal reproduction of Agave. The effects of agaves on the physiological performance and reproduction of native species were negative, positive or neutral, depending on the size and rooting depth of neighbours. Assemblages of native species growing within Agave stands had lower diversity than non-invaded sites. Our data show that Agave stands have positive growth rates in SE Spain, and suggest that sandy soils are a niche dimension enhancing the invasion in these new habitats. [source]

Naturalization and invasion of alien plants: concepts and definitions

DIVERSITY AND DISTRIBUTIONS, Issue 2 2000
David M. Richardson
Abstract., Much confusion exists in the English-language literature on plant invasions concerning the terms ,naturalized' and ,invasive' and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology. Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers. We propose that the term ,invasive' should be used without any inference to environmental or economic impact. Terms like ,pests' and ,weeds' are suitable labels for the 50,80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed ,transformers'. [source]

Patterns of abundance of fire ants and native ants in a native ecosystem

ECOLOGICAL ENTOMOLOGY, Issue 4 2009
KATHARINE L. STUBLE
Abstract 1.,This correlational study examines the relationship between the red imported fire ant (Solenopsis invicta) and native ants in a longleaf pine savanna. Fire ants are frequently associated with a decline in native ants throughout the invaded range, but fire ant invasion is often coupled with habitat disturbance. Invasion of fire ants into the longleaf pine savanna provides an opportunity to examine the structure of the ant community in the absence of habitat disturbance. 2.,Pitfall trapping was conducted within the longleaf pine savanna as well as across a naturally occurring soil moisture gradient, in plots that had been artificially watered. 3.,Species richness did not vary as a function of fire ant density. There was an inverse relationship between native ant density and fire ant density, but this abundance pattern does not necessarily imply a causal link between fire ant invasion and native ant decline. For individual species, fire ant densities were negatively correlated with the densities of only two native ant species, including Solenopsis carolinensis, a native species that potentially limits the invasion of fire ants. Additionally, fire ants and native ants respond differently to soil moisture, with native ants favouring drier conditions than fire ants. 4.,The possible exclusion of fire ants by some native ants, as well as differences in habitat preferences, provide alternative explanations for the frequently observed negative correlation between fire ants and native ants. [source]

Invasion impacts local species turnover in a successional system

ECOLOGY LETTERS, Issue 9 2004
Kathryn A. Yurkonis
Abstract Exotic plant invasions are often associated with declines in diversity within invaded communities. However, few studies have examined the local community dynamics underlying these impacts. Changes in species richness associated with plant invasions must occur through local changes in extinction and/or colonization rates within the community. We used long-term, permanent plot data to evaluate the impacts of the exotic vine Lonicera japonica. Over time, species richness declined with increasing L. japonica cover. L. japonica reduced local colonization rates but had no effect on extinction rates. Furthermore, we detected significant reductions in the immigration of individual species as invasion severity increased, showing that some species are more susceptible to invasion than others. These findings suggest that declines in species richness associated with L. japonica invasion resulted from effects on local colonization rates only and not through the competitive displacement of established species. [source]

Fluorescence in situ hybridization (FISH) analysis of the interactions between honeybee larvae and Paenibacillus larvae, the causative agent of American foulbrood of honeybees (Apis mellifera)

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2008
Dominique Yue
Summary American foulbrood (AFB) is a bacterial disease of honeybee larvae caused by the spore-forming bacterium Paenibacillus larvae. Although AFB and its aetiological agent are described now for more than a century, the general and molecular pathogenesis of this notifiable disease is poorly understood. We used fluorescence in situ hybridization (FISH) performed with P. larvae -specific, 16S rRNA-targeted oligonucleotide probes to analyse the early steps in the pathogenesis of American foulbrood. The following chain of events could be demonstrated: (i) the spores germinate in the midgut lumen, (ii) the vegetative bacteria massively proliferate within the midgut before, and (iii) they start to locally breach the epithelium and invade the haemocoel. The paracellular route was shown to be the main mechanism for invasion contrasting earlier hypotheses of phagocytosis of P. larvae. Invasion coincided with the death of the host implicating that the penetration of the midgut epithelium is a critical step determining the time of death. [source]

Biology, distribution and impacts of silverleaf nightshade (Solanum elaeagnifolium Cav.),

EPPO BULLETIN, Issue 1 2007
M. Mekki
Silverleaf nightshade, Solanum elaeagnifolium, is listed as a noxious weed in its native range (Americas) and as an invasive alien plant in many countries across the world. Its local pattern of distribution in the EPPO region indicates that it is still in an establishment phase. S. elaeagnifolium invasiveness could be related to several biological traits: copious production of sexual and asexual propagules, its facility for long-distance dispersion, its ability to endure considerable drought and to dominate shallow-rooted vegetation, especially during summer dry periods, and its capacity to suppress more valuable species because it is unpalatable and toxic to cattle. Invasion of the Mediterranean semi-arid region by S. elaeagnifolium was mainly facilitated by irrigation and animal production. Low moisture stress may favour this invasive species and sheep are an important pathway for its long-distance dispersal. Once established, it is one of the most difficult weeds to eradicate because of its network of creeping horizontal and deep vertical roots. Its phenotypic plasticity enables it to adopt a rosette-like growth pattern to escape control by repeated slashing. Thus, S. elaeagnifolium monitoring in the EPPO region is vital in order to contain established populations and prevent invasion. [source]

CNS-irrelevant T-cells enter the brain, cause blood,brain barrier disruption but no glial pathology

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2007
Alina Smorodchenko
Abstract Invasion of autoreactive T-cells and alterations of the blood,brain barrier (BBB) represent early pathological manifestations of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). Non-CNS-specific T-cells are also capable of entering the CNS. However, studies investigating the spatial pattern of BBB alterations as well as the exact localization and neuropathological consequences of transferred non-CNS-specific cells have been thus far lacking. Here, we used magnetic resonance imaging and multiphoton microscopy, as well as histochemical and high-precision unbiased stereological analyses to compare T-cell transmigration, localization, persistence, relation to BBB disruption and subsequent effects on CNS tissue in a model of T-cell transfer of ovalbumin (OVA)- and proteolipid protein (PLP)-specific T-cells. BBB alterations were present in both EAE-mice and mice transferred with OVA-specific T-cells. In the latter case, BBB alterations were less pronounced, but the pattern of initial cell migration into the CNS was similar for both PLP- and OVA-specific cells [mean (SEM), 95 × 103 (7.6 × 103) and 88 × 103 (18 × 103), respectively]. Increased microglial cell density, astrogliosis and demyelination were, however, observed exclusively in the brain of EAE-mice. While mice transferred with non-neural-specific cells showed similar levels of rhodamine-dextran extravasation in susceptible brain regions, EAE-mice presented huge BBB disruption in brainstem and moderate leakage in cerebellum. This suggests that antigen specificity and not the absolute number of infiltrating cells determine the magnitude of BBB disruption and glial pathology. [source]

Invasion of a karst aquifer by hydrothermal fluids: evidence from stable isotopic compositions of cave mineralization

GEOFLUIDS (ELECTRONIC), Issue 2 2001
S. H. Bottrell
Abstract Mineral deposits in the Cupp-Coutunn/Promeszutochnaya cave system (Turkmenia, central Asia) record a phase of hydrothermal activity within a pre-existing karstic groundwater conduit system. Hydrothermal fluids entered the caves through fault zones and deposited sulphate, sulphide and carbonate minerals under phreatic conditions. Locally, intense alteration of limestone wall rocks also occurred at this stage. Elsewhere in the region, similar faults contain economic quantities of galena and elemental sulphur mineralization. Comparisons between the Pb and S isotope compositions of minerals found in cave and ore deposits confirm the link between economic mineralization and hydrothermal activity at Cupp-Coutunn. The predominance of sulphate mineralization in Cupp-Coutunn implies that the fluids were more oxidized in the higher permeability zone associated with the karst aquifer. A slight increase in the ,34S of sulphate minerals and a corresponding ,34S decrease in sulphides suggest that partial isotopic equilibration occurred during oxidation. Carbonate minerals indicate that the hydrothermal fluid was enriched in 18O (,18OSMOW , + 10,) relative to meteoric groundwater and seawater. Estimated values for ,13CDIC (,13CPDB , , 13,) are consistent with compositions expected for dissolved inorganic carbon (DIC) derived from the products of thermal decomposition of organic matter and dissolution of marine carbonate. Values derived for ,13CDIC and ,18Owater indicate that the hydrothermal fluid was of basinal brine origin, generated by extensive water,rock interaction. Following the hydrothermal phase, speleothemic minerals were precipitated under vadose conditions. Speleothemic sulphates show a bimodal sulphur isotope distribution. One group has compositions similar to the hydrothermal sulphates, whilst the second group is characterized by higher ,34S values. This latter group may either record the effects of microbial sulphate reduction, or reflect the introduction of sulphate-rich groundwater generated by the dissolution of overlying evaporites. Oxygen isotope compositions show that calcite speleothems were precipitated from nonthermal groundwater of meteoric origin. Carbonate speleothems are relatively enriched in 13C compared to most cave deposits, but can be explained by normal speleothem-forming processes under thin, arid-zone soils dominated by C4 vegetation. However, the presence of sulphate speleothems, with isotopic compositions indicative of the oxidation of hydrothermal sulphide, implies that CO2 derived by reaction of limestone with sulphuric acid (,condensation corrosion') contributed to the formation of 13C-enriched speleothem deposits. [source]

Studies in Urban Ecology: the First Wave of Biological Invasion by Pistacia chinensis in Armidale, New South Wales, Australia

GEOGRAPHICAL RESEARCH, Issue 3 2000
J. M. B. Smith
Biological invasions by deliberately introduced organisms seriously compromise the integrity of ecosystems, but their early stages have seldom been documented, especially in urban contexts. Since the 1940s, the small Asian tree Pistacia chinensis has been widely planted in streets and gardens in Armidale, New South Wales, Australia, where it makes a major contribution to the autumn colours that are exploited to promote the city. Numerous wild plants are now becoming established in and near Armidale. This ongoing biological invasion may have been accelerated by the large size of the initial (planted) population, and by the presence of efficient avian seed dispersers. It is now at the stage of the first wild generation reaching reproductive maturity. While it is probably still possible to halt the invasion, various human factors appear to make this an unlikely prospect. [source]

Perineural Invasion of Sinonasal Lymphoma: A Rare Cause of Trigeminal Neuropathy

HEADACHE, Issue 2 2007
Chih-Wei Liang MD
Trigeminal neuropathy is characterized by sensory disturbance of the division of trigeminal nerve, and sometimes is associated with pain. Trigeminal neuropathy secondary to perineural invasion of sinonasal lymphoma is extremely rare. Likewise, sinonasal lymphoma is infrequently demonstrated initially with cranial neuropathy. The present case served to broaden the differential diagnosis of secondary trigeminal neuropathy and to alert clinicians to cautiously assess perineural spread of occult neoplasm in sinonasal tract and larynx or pharynx for cases with evolving trigeminal neuropathy or even other cranial nerve neuropathy in which no definite cause is identified. [source]

Heterogeneous expression of Wnt/,-catenin target genes within colorectal cancer

INTERNATIONAL JOURNAL OF CANCER, Issue 9 2007
Falk Hlubek
Abstract Invasion of common colorectal adenocarcinomas is coupled with a transient loss of epithelial differentiation of tumor cells. Previously, we have shown that dedifferentiated tumor cells at the invasive front (IF) accumulate the transcriptional activator ,-catenin in the nucleus, in contrast to cells of the tumor center. To characterize the cells of these two morphogenic tumor areas, gene expression profiling was performed. Our study demonstrates that intratumorous heterogeneity in colorectal cancer correlates with differential expression of 510 genes between the central tumor region (TC) and the IF. Many genes differentially expressed at the IF are involved in cellular invasion processes like cell motility, cell adhesion and extracellular matrix interaction. This in vivo analysis shows overexpression of known Wnt/,-catenin target genes either in the entire tumor tissue (compared to normal mucosa) or specifically at the IF. Thus, even though all tumor cells overexpress ,-catenin, the existence of at least 2 groups of Wnt/,-catenin target genes selectively activated in different tumor regions is suggested. The concomitant high expression of inflammation- and tissue repair-related genes at the IF supports the hypothesis that an inflammation-activated microenvironment may trigger selective Wnt/,-catenin target gene expression and contribute to the malignant progression of colorectal cancer. © 2007 Wiley-Liss, Inc. [source]

Diverse roles of 2-arachidonoylglycerol in invasion of prostate carcinoma cells: Location, hydrolysis and 12-lipoxygenase metabolism

INTERNATIONAL JOURNAL OF CANCER, Issue 5 2007
Michael P. Endsley
Abstract Endogenous 2-arachidonoylglycerol (2-AG) is antiinvasive in androgen-independent prostate carcinoma (PC-3) cells. Invasion of PC-3 cells is also inhibited by exogenously added noladin ether, a non-hydrolyzable analog of 2-AG. In contrast, exogenous 2-AG has the opposite effect. Cell invasion significantly increased with high concentrations of exogenous 2-AG. In PC-3 cells, arachidonic acid (AA) and 12-hydroxyeicosatetraenoic acid (12-HETE) concentrations increased along with exogenously added 2-AG, and 12-HETE concentrations increased with exogenously added AA. Invasion of PC-3 cells also increased with exogenously added AA and 12(S)-HETE but not 12(R)-HETE. The exogenous 2-AG-induced invasion of PC-3 cells was inhibited by 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP, an inhibitor of 2-AG hydrolysis) and baicalein (a 12-LO inhibitor). Western blot and RT-PCR analyses indicated expression of 12-HETE producing lipoxygenases (LOs), platelet-type 12-LO (P-12-LO) and leukocyte-type 12-LO (L-12-LO), in PC-3 cells. These results suggest that exogenous 2-AG induced, rather inhibited, cell invasion because of its rapid hydrolysis to free AA, and further metabolism by 12-LO of AA to 12(S)-HETE, a promoter of PC cell invasion. The results also suggest that PC-3 cells and human prostate stromal (WPMY-1) cells released free AA, 2-AG, and 12-HETE. In the microenvironment of the PC cells, this may contribute to the cell invasion. The 2-AG hydrolysis and concentration of 2-AG in microenvironment are critical for PC cell's fate. Therefore, inhibitors of 2-AG hydrolysis could potentially serve as therapeutic agents for the treatment of prostate cancer. © 2007 Wiley-Liss, Inc. [source]

Disseminated cutaneous Fusarium moniliforme infections in a leukemic child

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2007
Ching-Chi Chi MD
A 5-year-old boy had a 10-month remission of acute lymphocytic leukemia (ALL) after chemotherapy. Re-induction chemotherapy was performed for relapse of ALL. Thereafter, he suffered from an episode of neutropenic fever with pneumonia. One week following control of the condition with antibiotics, a 1 × 1-cm, red, painful nodule appeared on the left thigh, which was initially suspected to be Pseudomonas infection. Parenteral ceftazidime and amikacin were administered, but persistent high fever, mild cough, and a few painful erythematous papulonodules on the face and lower extremities appeared several days later (Fig. 1). These lesions increased insidiously in diameter up to 2,5 cm with central necrosis. Hemogram showed neutropenia with a shift to the left [white blood cell (WBC) count, 2.1 × 109/L; neutrophil count, 0.21 × 109/L]. A skin biopsy showed heavy growth of hyaline branching septate hyphae in the deep dermis and subcutis, together with fat necrosis (Fig. 2). Invasion of molds into vessels and sweat glands was also seen. A culture from a lesion yielded Fusarium moniliforme, but no fungi were isolated from blood specimens. Only mild infiltrations on bilateral lower lung fields were detected by chest roentgenography. The skin lesions gradually healed and the fever subsided 2 weeks after the initiation of therapy with amphotericin B 30 mg and itraconazole 200 mg daily. Figure 1. A few painful erythematous papulonodules appeared on the face and lower extremities Figure 2. Skin biopsy showed heavy growth of hyaline branching septate hyphae in the deep dermis and subcutis along with fat necrosis (hematoxylin and eosin, ×400) Meanwhile, relapse of leukemia was detected by hemogram showing atypical leukocytosis (WBC count of 24,400 × 109/L, with blast cells representing 78%). A course of chemotherapy with cytarabine, mitoxantrone, and VP-16 was prescribed, subsequently resulting in neutropenia (WBC count, < 0.1 × 109/L; neutrophil count, 0/L) and spiking fever. Although the aforementioned antifungal therapy was continued, the centers of the originally healed lesions turned dusky red, swollen, necrotic, and ulcerative. There were more than 10 such ecthymiform lesions. After administration for 22 days, itraconazole was discontinued because of no appreciable effects. Granulocyte colony-stimulating factor (G-CSF) salvage was used, and the neutropenia gradually subsided 20 days later. In addition, the ecthymiform lesions gradually resolved. Amphotericin B was discontinued 1 week following neutrophil recovery. The patient died of Acinetobacter baumannii and Stenotrophomonas maltophilia sepsis 8 months later. [source]

FAO prevents Red Locust Invasion

AFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 6 2009
Article first published online: 30 JUL 200
No abstract is available for this article. [source]

Competitive displacement or biotic resistance?

JOURNAL OF VEGETATION SCIENCE, Issue 2 2010
Disentangling relationships between community diversity, invasion success of tall herbs, shrubs
Abstract Questions: Are negative invasion,diversity relationships due to biotic resistance of the invaded plant community or to post-invasion displacement of less competitive species? Do invasion,diversity relationships change with habitat type or resident traits? Location/species: Lowlands and uplands of western and southern Germany, Heracleum mantegazzianum; mountain range in central Germany, Lupinus polyphyllus; and coastal dunes of northwest Germany, Rosa rugosa. Methods: We tested the significance and estimated regression slopes of invasion,diversity relationships using generalized linear (mixed effects) models relating invader cover and habitat type to species richness in different plant groups, stratified based on size, life cycle and community association. Results: We found negative, positive and neutral relationships between invader cover and species richness. There were negative linear correlations of invader cover with small plant species throughout, but no negative linear correlation with tall species. Invasion,diversity relationships tended to be more negative in early-successional habitats, such as dunes or abandoned grasslands, than in late-successional habitats. Conclusions: Invasion diversity,relationships are complex; they vary among habitat types and among different groups of resident species. Negative invasion,diversity relationships are due to asymmetric competitive displacement of inferior species and not due to biotic resistance. Small species are displaced in early-successional habitats, while there is little effect on persistence of tall species. [source]

IpgD, a protein secreted by the type III secretion machinery of Shigella flexneri, is chaperoned by IpgE and implicated in entry focus formation

MOLECULAR MICROBIOLOGY, Issue 1 2000
Kirsten Niebuhr
Invasion of epithelial cells by Shigella flexneri involves entry and intercellular dissemination. Entry of bacteria into non-phagocytic cells requires the IpaA,D proteins that are secreted by the Mxi,Spa type III secretion machinery. Type III secretion systems are found in several Gram-negative pathogens and serve to inject bacterial effector proteins directly into the cytoplasm of host cells. In this study, we have analysed the IpgD protein of S. flexneri, the gene of which is located on the virulence plasmid at the 5, end of the mxi,spa locus. We have shown that IpgD (i) is stored in the bacterial cytoplasm in association with a specific chaperone, IpgE; (ii) is secreted by the Mxi,Spa type III secretion system in amounts similar to those of the IpaA,D proteins; (iii) is associated with IpaA in the extracellular medium; and (iv) is involved in the modulation of the host cell response after contact of the bacterium with epithelial cells. This suggests that IpgD is an effector that might be injected into host cells to manipulate cellular processes during infection. [source]

Oestrogenic Steroids and Melanoma Cell Interaction with Adjacent Skin Cells Influence Invasion of Melanoma Cells In Vitro

PIGMENT CELL & MELANOMA RESEARCH, Issue 2000
SHEILA MAC NEIL
The invasion of melanoma is complex and multi-staged and involves changes in both cell/extracellular matrix (ECM) and cell/cell interactions. Female steroids and ,-MSH have also been reported to influence metastatic melanoma progression, but their mechanisms of action are unknown. Accordingly, our aim was to establish in vitro models to examine (a) the influence of sex steroids and ,-melanocyte-stimulating hormone (,-MSH) on tumour invasion and the influence of (b) ECM proteins and (c) adjacent cells on melanoma invasion. In the first model, melanoma cell invasion through fibronectin over 20 hr under serum-free conditions was used to investigate the effects of 17,-oestradiol and oestrone on the invasion of human melanoma cell lines, A375-SM and HBL. A375-SM, but not HBL cells, proved very susceptible to inhibition by female steroids. However, invasion of the HBL line was inhibited by ,-MSH. Using the second model of reconstructed human skin based on de-epidermised acellular dermis, we found that the HBL cells on their own failed to invade into the dermis (irrespective of the presence or absence of the basement membrane). However, there was a significant synergistic interaction between keratinocytes, fibroblasts and HBL cells, such that a modest invasion of HBLs into the dermis was seen within 2 weeks when other skin cells were present. In contrast, A375-SM cells showed a significant ability to invade the dermis in the absence of other cells, with less invasion when other skin cells were present. In summary, these models have provided new information on the extent to which melanoma cell invasion is sensitive to oestrogenic steroids and to ,-MSH and to interaction, not only with adjacent skin cells but also to the presence of basement membrane antigens. [source]

"Population Invasion" versus Urban Exclusion in the Tibetan Areas of Western China

POPULATION AND DEVELOPMENT REVIEW, Issue 4 2008
Andrew Martin Fischer
This article examines the confluence of local population transitions (demographic transition and urbanization) with non-local in-migration in the Tibetan areas of western China. The objective is to assess the validity of Tibetan perceptions of "population invasion" by Han Chinese and Chinese Muslims. The article argues that migration to Tibet from other regions in China has been concentrated in urban areas and has been counterbalanced by more rapid rates of natural increase in the Tibetan rural areas,among the highest rates in China. Overall, it is not clear whether there is any risk of population invasion in the Tibetan areas. However, given that non-Tibetan migration to Tibet has been concentrated in urban areas, Tibetans have probably become a minority in many of their strategic cities and towns, and non-Tibetan migrants definitely dominate urban employment. Therefore, while the Tibetan notion of population invasion may be a misperception, it reflects a legitimate concern that in-migration may be exacerbating the economic exclusion of Tibetan locals in the context of rapid urban-centered development. [source]