bluuebunny/crossref_metadata_2025_split huggingface dataset:
KINETIC CHARACTERIZATION OF A DUAL PHOSPHATE UPTAKE SYSTEM IN THE ENDOMYCORRHIZAL FUNGUS OF ERICA HISPIDULA L.
Authors: STRAKER C. J. , MITCHELL D. T. 
Published: April 2006

SummaryMycelia of the endomycorrhizal fungus of Erica hispidula L. were grown in liquid culture media containing high (6 mM) or low (60 μM) concentrations of orthophosphate. Phosphate uptake rates were measured over the range 1 to 500 μ and were interpreted as being the consequence of a dual uptake system. The Vmax values of low P and high P status mycelia of the low‐affinity system (LA) were similar, whereas the Km of high P status mycelia was lower than that of low P status mycelia. The Km values of high P and low P status mycelia of the high‐affinity system (HA) were similar, whereas high P status mycelia showed a higher Vmax value than low P status mycelia. In low P status mycelia, the LA contribution to total uptake was 93% at 500μM and 25% at 1 μM external phosphate. The uptake systems were sensitive to pH and 2,4‐dinitrophenol. These results are compared with similar studies on saprotrophic fungi and mycorrhizal associations.
OXALIC ACID SYNTHESIS BY THE MYCORRHIZAL FUNGUS PAXILLUS INVOLUTUS (BATSCH. EX FR.) FR.
Authors: LAPEYRIE F. , CHILVERS G. A. , BHEM C. A. 
Published: April 2006

SummaryOxalic acid produced by an isolate of the mycorrhizal fungus Paxillus involutus (Batsch. ex Fr.) Fr. in still broth culture was assayed using high‐performance liquid chromatography. Production of oxalic acid per unit of mycelium was influenced by nitrogen source and concentrations of exogenous calcium and bicarbonate ions. Nitrate‐grown mycelia produced large quantities of oxalic acid; ammonium‐grown mycelia produced small quantities regardless of what other ions were present. Calcium concentrations between 10 and 50 meq 1−1 slightly enhanced oxalic acid production in the presence of nitrate; concentrations between 250 and 500 meq 1−1 depressed production. Small additions of bicarbonate ions substantially increased oxalic acids production when nitrate was present. When calcium was present, most of the oxalic acid was associated with the mycelium, probably as calcium oxalate. In the absence of calcium, most of the oxalic acid occurred free in the culture medium. It is concluded that in calcareous soils, bicarbonate and nitrate are more important than calcium in stimulating oxalate production. The significance and underlying mechanisms of oxalate production are discussed.
PRODUCTION OF FREE STEROLS BY INFECTED TUBERS OF OPHRYSLUTEA CAV.: IDENTIFICATION BY GAS CHROMATOGRAPHY‐MASS SPECTROMETRY
Authors: BARROSO J. , CHAVES NEVES H. , PAIS M. SALOMÉ S. 
Published: April 2006

SummaryErgosterol, 24–ethyl‐cholest‐7,22‐dien‐3‐β‐ol, campesterol, sitosterol and cycloartenol could be detected in the infected tubers of Ophrys lutea Cav. by capillary gas chromatography and gas chromatography–mass spectrometry of the corresponding O‐trimethylsilyl ethers and acetates. The uninfected tubers only contained demethylsterols. No free sterols could be detected in the endophyte maintained in pure culture.The possible role of sterols in the stability of the host cell membranes in mycorrhizas of O. lutea is discussed.
EFFECT OF CERTAIN HERBICIDES ON SAPROPHYTIC SURVIVAL AND BIOLOGICAL SUPPRESSION OF THE TAKE‐ALL FUNGUS
Authors: MEKWATANAKARN P. , SIVASITHAMPARAM K. 
Published: April 2006

SummarySaprophytic survival and pathogenicity of Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici Walker were evaluated in sterile and unsterile Western Australian wheat field soil treated with the herbicides glyphosate, diquat + paraquat, or trifluralin. Survival in colonized straws and subsequent pathogenicity were not affected by the herbicide treatments in sterile soil. In unsterile soil, however, survival and pathogenicity were higher in glyphosate or diquat + paraquat‐treated than in untreated or trifluralin‐treated soil. Incorporation of untreated natural soil into fumigated soil, to give concentrations of 1 and 10% natural soil in the mix, reduced disease in comparison with that in 100% sterile or 100% natural soil. Disease in fumigated soil increased progressively with increasing concentrations of glyphosate‐treated, unsterile soil. Pre‐treatment of wheat plants or soil with glyphosate before exposure of the host to the fungal pathogen or to other soil micro‐organisms showed that the increase in disease following glyphosate treatment was not related to the direct effect of the herbicide on the host.
COMPARATIVE ABILITIES OF LEAF SURFACES TO NEUTRALIZE ACIDIC RAINDROPS I. THE INFLUENCE OF CALCIUM NUTRITION AND CHARCOAL‐FILTERED AIR
Authors: HUTCHINSON T. C. , ADAMS C. M. 
Published: April 2006

SummaryThe relative abilities of four species to neutralize acidic rain droplets placed on their leaf surfaces were examined. Rain droplets (50 μl) of pH 4.7, 3.8, 3.0 and 2.4 were used. Determinations of droplet pH on the leaf surfaces and on a control parafilm surface were made at intervals until the leaves dried. Neutralizing abilities of leaves of sugar beet (Beta vulgaris), radish (Raphanus sativus), sunflower (Helianthus annuus) and the arctic herb (Artemisia tilesii) were compared. The plants were grown in sand culture with calcium supplied at a range of five concentrations, from 48 to 480 ppm to alter the calcium status of the foliage. While the Ca2+ treatments strongly influenced the Ca2+ content of leaves, they did not influence the neutralizing ability of the leaves. However, sugar beet, which showed the least ability to neutralize, had the lowest foliar Ca2+ content of the species examined. At raindrop pH values of 4.7, 3.8 and 3.0, the species were all able to increase droplet pH substantially before drying. The effect appeared to be two‐phased, with a rapid initial neutralization probably due to solubilized surface particulates and evaporated leaf exudates, followed by a slower subsequent phase, probably due to droplet–cell wall exchange processes. At pH 2.4 only radish and sunflower were still able to neutralize, but this may have been due to leakage of the contents of damaged cells. In experiments comparing plants grown in filtered vs unfiltered air, and in sand vs soil in the greenhouse or outdoors, it was shown that charcoal filtering the air substantially reduced the neutralizing ability of the leaf surface. Surface wettability and the speed at which droplets dried out were important in determining the neutralizing ability of leaf surfaces.
Angiogenesis in invasive squamous cell carcinoma of the lip: tumor vascularity is not an indicator of metastatic risk
Authors: Tahan Steven R. , Stein Amy L. 
Published: April 2006

Background– Recent studies have shown that tumor growth beyond a certain size requires angiogenesis. Microvessel density has, moreover, correlated with metastatic risk in some tumors. Invasive squamous carcinoma (SCC) can develop in the epithelium of the lip and metastasize even when relatively small. This study investigates neovascularization and its relationship to metastatic risk in this tumor. Methods– All 41 primary SCCs of the lip diagnosed at our institution from 1960 to 1991 were immunostained for factor VIII. Microvessel grade (Mv) from 1+ to 4+ and the average number of vessel profiles (TMvD) in the highest density 200 × (0.785 mm2) and 400 × (0.196 mm2) microscopic fields were determined. TMvDs were compared with those of adjacent non‐tumor tissue (NTMvD). Normalized counts (TMvDns) were calculated as TMvD/NTMvD. TMvDs and TMvDnns of metastasizing (N=10) and non‐metastasizing (N = 31) tumors were compared (student t‐test). Results– In all SCCs TMvDs exceeded NTMvDs (50 vs.35 at 200 ×, P = 0. 0014, and 26 vs. 14 at 400 ×, P< 0.0001). Metastasizing and non‐metastasizing tumors did not, however, differ in Mv, TMvD, or TMvDn. Conclusions– Angiogenesis develops, but is not quantitatively related to metastatic risk, in primary invasive squamous cell carcinoma of the lip.Tahan SR, Stein AL. Angiogenesis in invasive squamous cell carcinoma of the lip: tumor vascularity is not an indicator of metastatic risk.
Prognostic evaluation of specific cutaneous infiltrates in B‐chronic lymphocytic leukemia
Authors: Kaddu Steven , Smolle Josef , Cerroni Lorenzo , Kerl Helmut 
Published: April 2006

The relationship between numerous histologic variables and survival was investigated in 54 consecutive lesions of specific skin infiltrates of B‐cell chronic lymphocytic leukemia (B‐CLL) from 27 patients (16 males and 11 females, mean age 65 years, range 42–83 years). All patients were followed for up to 204 months or until death. Histopathologically, the infiltrates showed a patchy perivascular (35%), diffuse (31.5%), nodular (31.5%) or band‐like (1.9%) pattern. In 28% of the cases, an admixture of reactive cells within the infiltrate including eosinophils, histiocytes, neutrophils and plasma cells was observed. Cytomorphologically, small B‐lymphocytes with condensed chromatin predominated in most infiltrates. However, some biopsies showed a small but significant number of medium‐ or large‐sized neoplastic cells of the B‐lymphocyte lineage with variable cytomorphological features.In a multivariate analysis, several histologic parameters within the infiltrates were found to show a significant association with long survival, namely, an infiltrate of moderate density, a nodular pattern, involvement of the lower dermis only, and presence of predominantly small B‐lymphocytes (more than 95%) with condensed chromatin. Histologic variables that independently correlated with relatively short survival included an infiltrate of severe intensity, a diffuse pattern, epidermal changes (especially acanthosis and ulceration), medium‐sized and large B‐lymphocyte (more than 5%), and reactive cells within the infiltrate (neutrophils, eosinophils, and plasma cells). Overall analysis of our results showed two histologic patterns with a significant prognostic impact (p<0.01; z=5.4). Pattern I (33 biopsies) correlated with relatively long survival (2‐year survival rate; 97%) and consisted of infiltrates showing predominantly small B‐lymphocytes (more than 95%) without reactive cells or epidermal changes. Pattern II (21 biopsies) indicated short survival (2‐year survival rate; 49%) and included all the rest of the biopsies i.e., infiltrates with medium‐ and large‐sized B‐lymphocytes (more than 5%), admixture of reactive cells, and epidermal changes. Results from our study suggest that histologic features in specific skin infiltrates of B‐chronic lymphocytic leukemia may be helpful in identifying prognostically different subgroups of patients and planning therapeutic schedules.
Spindle cell lipoma is strongly CD34 positive. An immunohistochemical study
Authors: Templeton Stephen F. , Solomon Alvin R. 
Published: April 2006

Spindle cell lipoma (SCL) is an uncommon soft tissue neoplasm that may provide diagnostic difficulty to the histopathologist. Four retrospectively identified SCLs were evaluated immunohistochemically with a broad panel of antibodies (CD34, factor XIIIa, S‐100, actin and factor VIII). All four SCLs were strongly CD34 positive (95 to 100% of cells) and focally factor XIIIa positive (average 16% of cells). Tumor cells were S‐100, actin and factor VIII negative.Dermatofibrosarcoma protuberans, neurofibroma, schwannoma and angiolipoma are CD34 positive tumors that have some similar histologic features to SCL and may be considered in the differential diagnosis. Differentiation is possible using a broad panel of immunostains and routine diagnostic criteria.
What can we learn about human immunodeficiency virus infection from a study of lymphocytic choriomeningitis virus?
Authors: Klenerman Paul , Zinkernagel Rolf M. 
Published: April 2006

SummaryThe role of cytotoxic T lymphocytes (CTL) in human immunodeficiency virus (HIV) infection remains elusive. Since the discover) 10 years ago of high levels of specific CTL in this disease, same have argued that they play an important role in virus control, minis that they drive disease progression through destruction of T helper cells, and others st ill that they play no obvious role at all. By contrast, the central role of CTL in murine lymphocytic choriomeningitis virus (LCMV) infection has been very clearly worked out through the use of in vivo depletion and adoptive transfer experiments, as well as knockout and transgenic mice. To interpret the possible roles for CTL in HIV, we have therefore made a comparison between what is known about CTL and their interaction with virus‐infected cells in these two infections. This illustrates a potential critical role for these cells in both control of HIV replication and immune‐mediated pathology, but one that is highly dependent on virus dose, distribution and dynamics.
Co‐evolution of human immunodeficiency virus and cytotoxic T‐lymphocyte responses
Authors: Goulder Philip , Price David , Nowak Martin , Rowland‐Jones Sarah , Phillips Rodney , McMichael Andrew 
Published: April 2006

SummaryAfter more than a decade of intensive research, the precise of human immunodeficiency virus (HIV)‐specific cytotoxic T lymphocytes (CTL) in determining the course of the infection remains open to argument. It is established that HIV‐specific CTL appear early in the infection and are temporally associated with the clearance of culturable virus from the blood; that CTL are generally detectable at very high levels throughout the asymptomatic phase and decline at the time of progression to AIDS; and that CTL‐mediated killing is sufficiently fast to prevent production of new virus by HIV‐infected cells. However, viral turnover is throughout the course of the infection, and –infected individuals progress inexorably to disease in spite of the CTL response. In order Co address the question of whether CTL play an active part in influencing the course of HIV infection, one approach has been to seek evidence for CTL‐mediated selection pressure on the virus. Several clear examples of CTL epitope‐specific mutations selected to fixation are described. We argue that CTL escape is a common event which occurs at all stages of the Infection. Detailed longitudinal studies are required to detect CTL escape and to nd the complexities contributed by factors SUC h as a polyvalent CTL response and the presence of epitope variants which antagonise the CTL response. In conclusion, there is strong evidence of a dynamic process in which CTL impose important selection constraints upon HIV fro m which the virus attempts to escape; ultimately, at the time of disease progression, the tenuous control of CTL over the virus is lost.
Host factors in the pathogenesis of HIV disease
Authors: Cohen Oren J. , Kinter Audrey , Fauci Anthony S. 
Published: April 2006

SummaryHost factors play an important role in determining rates of disease progression in human immunodeficiency virus (HIV)‐infected individuals. HIV is able lo subvert the host immune system by infecting CD4+ T cells that normally orchestrate immune responses and by inducing the secretion of proinflammatory cytokines that the virus can utilize to its own replicative advantage. The recognition that certain chemokine receptors serve as necessary co‐factors for HIV entry into its target cells as well as the fact that ligands for these receptors can modulate the efficiency of HIV infection has expanded the number and scope of host factors that may impact the pathogenesis of HIV disease. This area of investigation will no doubt yield novel therapeutic strategies for intervention in HIV disease; however, caution is warranted in light of the enormous complexity of the pleiotropic cytokine and chemokine networks and the uncertainty inherent in manipulating these systems.HIV‐infected long‐term non‐progressors represent an excellent model to study potential host factors involved in HIV disease pathogenesis. Genetic factors certainly have a major impact on the immune responses mounted by the host. In this regard, a polymorphism in the gene for the HIV co‐receptor CC chemokine receptor 5 (CCR5), which serves as a coreceptor for macrophage (M)‐tropic strains of HIV, affords a high degree of protection against HIV infection in individuals homozygous for the genetic defect and some degree of protection against disease progression in HIV‐infected heterozygotes. HIV‐specific immune responses, including cytotoxic T‐lymphocyte (dX) responses and neutralizing antibody responses, also appear to play salutary roles in protecting against disease progression.
Effector CD4+ and CD8+ T‐cell mechanisms in the control of respiratory virus infections
Authors: Doherty Peter C. , Topham David J. , Tripp Ralph A. , Cardin Rhonda D. , Brooks James W , Stevenson Philip G. 
Published: April 2006

SummaryThe rules for T‐cell‐mediated control of viruses that infect via the respiratory mucosae show both common themes and differences depending on the nature of the pathogen. Virus‐specific CD8+ cytotoxic T lymphocytes (CTLs) are the key effectors of virus clearance in mice infected with both negative strand RNA viruses (influenza and Sendai) and a DNA virus, the murine γ‐herpesvirus68 (MHV‐68). Recently completed experiments establish that these activated CD8+ T cells indeed operate primarily via contact‐dependent lysis, Perform‐mediated cytotoxicity seems to be the preferred mode, though a Fas‐based mechanism can apparently serve as an alternative mechanism. Immune CD4+ T cells functioning in the absence of the CD8+ subset cannot eliminate MHV‐68 from lung epithelial cells, are somewhat less efficient than the CD8+ CTLs at clearing the RNA viruses, and are generally ineffectual in mice that lack B lymphocytes. Though cytokine secretion by CD4+ and CD8+ T cells in the virus‐infected king may promote both T‐cell extravasation and macrophage activation, such processes are not alone sufficient to deal consistently with any d these infections. However, CD4+ T help is mandatory for an effective B‐cell response, and can operate lo promote the clonal expansion of virus‐specific CD8+ T cells in the lymph nodes and spleen. Furthermore, a concurrent CD4+ T‐cell response seems to be essential for maintaining continued CD8+ T‐cell surveillance and effector capacity through the persistent, latent phase of MHV‐68 infection in B cells. Thus, the evidence to date supports a very traditional view: CD8+ T cells function mainly as killers and the CD4+ T cells as helpers in these respiratory virus infections.
Antiviral immune responses modulate the nature of central nervous system (CNS) disease in a murine model of multiple sclerosis
Authors: Drescher Kristen M. , Pease Larry R. , Rodriguez Moses 
Published: April 2006

SummaryThe spectrum of disease is influenced by factors related to both the pathogen and the host, as well as the end points used in defining disease. In this article, the issue of disease resistance versus susceptibility will be examined in the framework that genetic manipulation of either the pathogen or the host immune response alters the balance from disease protection towards pathogenesis. The response of the host may trigger both a protective and a pathogenic immune response. The failure CO mount protective immune response predisposes the pathogen to persistence, which then becomes the target for immunopathology. This review will examine the factors involved both in virus‐mediated pathogenesis and in disease protection in the Theiler's model d human multiple scler manipulating the character of the virus pathogen and the specificity of the immune response, the entire spectrum of human demyelinating disease is reproduced.
On the mystique of the immunological self
Authors: Silverstein Arthur M. , Rose Noel R. 
Published: April 2006

SummarySince the time of Paul Ehrlich 100 years ago, we have known that the immunological apparatus somehow inhibits most damaging autoimmune responses while permitting a response to exogenous immunogens. With the discovery of tolerance, the concept of immunological surveillance, and especially with the discovery of HLA restriction of T‐cell recognition, the term “the immunological self” and the phrase “self‐nonself discrimination” have gained wide currency. Immunology has been called The Science of Self, and self‐nonself discrimination has been assigned as the driving force for its complex evolution. The concept of self has thus been given such mystical trappings since the time of Macfarlane Burnet that recent workers have felt free to pronounce it the central paradigm of modern immunology, and to claim to overthrow it! In this article, we challenge some of the more egregious claims about the immunological self by recalling important historical findings, by reviewing the mechanisms of Darwinian evolution, and by remembering that the general pathology of immunogenic inflammation shows that the immune response cannot discriminate between the benign and the noxious.
Toward a predictive understanding of molecular recognition
Authors: Weng Zhiping , DeLisi Charles 
Published: April 2006

Summary: T cells circulate in blood and the lymphatic system, continually engaging cells through transient non‐specific adhesion. In a normally functioning immune system, these interactions permit sufficient time for T‐cell receptors (TCRs) to sample major histocompatibility complex (MHC)‐pep‐tide complexes for the presence of foreign antigen, with detection of the latter to some extent being triggered by a longer dwell time of the receptor on the complex. Precisely how this incremental stability, which may be relatively small, leads to activation is unclear, but it appears to be related to diffusion‐mediated formation of ternary complex dimers.The formation of stable dimers can explain the high sensitivity of the response, but leaves a number of questions un addressed, including the following; i) How can high sensitivity be reconciled with high specificity, and how can a short TCR dwell time be reconciled with a comparably short time for ternary complex pair formation? ii) What is the nature of the early signals on the plasma membrane that determine alternative responses e.g. proliferation at one extreme and apoptosis at the other’ iii) What arc the cell‐surface correlates of biphasic dose response functions i.e. of responses that peak as a function of dose and then descend?This paper has two loosely coupled goals. One is to review and assess the mathematical and computational methods available for analyzing reactions with and between mobile membrane‐bound receptors. These methods range from phenomenological to mechanistic, the latter being based on the details of atomic structure. The other is to apply these methods to address biological questions, such as those raised above, part of whose answer may lie in the kinetic competition between alternative reaction paths.
Crucial function of the pre‐T‐cell receptor (TCR) in TCRP selection, TCRβ allelic exclusion and αβ versus γδ lineage commitment
Authors: von Boehmer Harald , Aifantis Iannis , Azogui Orly , Feinberg Jacqueline , Saint‐Ruf Claude , Zober Carole , Garcia Corinne , Buer Jan 
Published: April 2006

Summary: The analysis of T‐cell receptor (TCR) βselection, TCRβ allelic exclusion and TCRβ rearrangement in γδ T cells from normal and pre‐TCR‐deficient mice has shown that the pre‐TCR has a crucial role in T‐lyinpbocyte development:

The pre‐TCR is by far the most effective receptor that generates large numbers of CD4+8+ T cells with productive TCRβ rearrangements.
In the absence of the pre‐TCR, TCRβ rearrangement proceeds in developing cells irrespective of whether they already contain a productive TCRβ gene.
The pre‐TCR directs developing T cells to the αβ lineage because y5 T cells from pTα‐/‐ mice proceed much further in TCRβ rearrangement than γδ T cells from wild‐type mice. It is argued that the pre‐TCR commits developing T cells to the αβ lineage by an instructive mechanism, which has largely replaced an evolutionarily more ancient mechanism that involves stochastic αβ lineage commitment.