bluuebunny/crossref_metadata_2025_split huggingface dataset:
The utriculo-endolymphatic valve: its functional significance
Authors: Schuknecht Harold F. , Belal A. Aziz 
Published: July 2007

AbstractA STUDY was made of the anatomical structure and functional significance of the ultriculo-endolymphatic (UE) valve in man. The material consists of 170 human temporal bones of which 75 were chosen to show normal structure through nine decades of life, 29 with endolymphatic hydrops, 22 with developmental defects and 44 with pertinent staining characteristics of the endolymphatic fluid. The studies show that the UE valve is ideally suited to preserve the humoral and anatomical features of the pars superior (utricle and canals) from the developmental, disease, and traumatic susceptibilities of the pars inferior (cochlear duct and saccule). Its function probably is to permit the occasional egress of excessive accumulation of endolymph to be processed in the endolymphatic sac and to accomplish this while preserving the normal endolymph volume and membrane anatomy of the utricle and canals.
Population genetics of anthelmintic resistance in parasitic nematodes
Authors: GILLEARD J. S. , BEECH R. N. 
Published: July 2007

SUMMARYA key aim of anthelmintic resistance research is to identify molecular markers that could form the basis of sensitive and accurate diagnostic tests. These would provide powerful tools to study the origin and spread of anthelmintic resistance in the field and to monitor strategies aimed at preventing and managing resistance. Molecular markers could also form the basis of routine diagnostic tests for use in surveillance and clinical veterinary practice. Much of the research conducted to date has focused on the investigation of possible associations of particular candidate genes with the resistance phenotype. In the future, as full parasite genome sequences become available, there will be an opportunity to apply genome-wide approaches to identify the genetic loci that underlie anthelmintic resistance. Both the interpretation of candidate gene studies and the application of genome-wide approaches require a good understanding of the genetics and population biology of the relevant parasites as well as knowledge of how resistance mutations arise and are selected in populations. Unfortunately, much of this information is lacking for parasitic nematodes. This review deals with a number of aspects of genetics and population biology that are pertinent to these issues. We discuss the possible origins of resistance mutations and the likely effects of subsequent selection on the genetic variation at the resistance-conferring locus. We also review some of the experimental approaches that have been used to test associations between candidate genes and anthelmintic resistance phenotypes and highlight implications for future genome-wide studies.
ABC transporters and β-tubulin in macrocyclic lactone resistance: prospects for marker development
Authors: PRICHARD R. K. , ROULET A. 
Published: July 2007

SUMMARYMacrocyclic lactones (MLs) are highly lipophilic anthelmintics which are known to bind to and open ligand-gated ion channels. However, these anthelmintics, and particularly the avermectin members of the ML class of endectocides, are potent substrates for ABC transporters and these transporters may regulate drug concentration in both the host and the parasite. There is accumulating evidence that ivermectin (IVM), and to a lesser extent moxidectin (MOX), selects for certain alleles of P-glycoprotein and other ABC transporter genes, selects for constitutive overexpression of some of these gene products, and induces overexpression of some P-glycoproteins in nematodes. However, such mechanisms of ML resistance do not easily lend themselves to the identification of SNP markers for resistance because of the diversity of ABC transporters in nematodes, the apparent diversity of effects of different MLs, and because regulatory elements for ABC transporter gene expression are not well understood in nematodes. Another non ligand-gated ion channel gene which appears to be under IVM selection, at least inOnchocerca volvulusandHaemonchus contortus, is β-tubulin, and a simple genetic test for this selection has been described inO. volvulus. However, further work is required to elucidate a reliable marker associated with this gene inH. contortusor other parasitic nematodes of livestock. The possible involvement of ABC transporter genes and β-tubulin in ML resistance provides a start in developing our understanding of this phenotype and markers for its detection in field populations of parasitic nematodes. However, more work is required before these leads can provide practical SNP markers for ML resistance.
Vitamin A status in Cuban children aged 6–11 years
Authors: Macías-Matos Consuelo , Pita-Rodríguez Gisela , Monterrey-Gutiérrez Pedro , Reboso-Pérez José 
Published: July 2007

AbstractObjective and settingA nationwide study was performed in Cuba to assess vitamin A status and the intake of vitamin-A-providing foods in children aged 6–11 years.Design and subjectsThe sample comprised 1191 schoolchildren from first to sixth grade, both sexes, from municipalities randomly selected from the five eastern provinces of Cuba in 2002 (first semester) and from the four western and four central provinces in 2003 (first semester). A food-frequency questionnaire was completed by 2038 mother-and-child pairs.ResultsMean (±standard deviation) plasma retinol concentrations were 1.77 ± 0.48 μmol l−1in the western, 2.01 ± 0.56 μmol l−1in the central and 1.40 ± 0.41 μmol l−1in the eastern region. No child had plasma retinol concentration below 0.35 μmol l−1, indicative of a high risk of clinical deficiency. Subclinical deficiency, plasma retinol concentration of 0.35–0.7 μmol l−1, was seen in <2% of subjects in all three regions and was <5% even in the two provinces with the worst vitamin A status (Guantánamo, 4.6%; Las Tunas, 3.0%). Adequate status (>1.05 μmol l−1) was present in >90% of subjects in all western and central provinces, and in one of the eastern provinces (Holguín), whereas in the four remaining eastern provinces, adequate status was present in >75%. Only nine fruits and vegetables were consumed frequently (>3 times per week) by >50% of children. Thirty-seven per cent regularly consumed a supplement containing vitamin A.ConclusionsMost Cuban children aged 6–11 years had adequate vitamin A status. Consumption of foods rich in vitamin and provitamin A, especially vegetables, was frequent but limited to a small variety of foods.
Initiation of antigen receptor endocytosis and B lymphocyte activation lie on independent biochemical pathways
Authors: SHULER RANDY L. , OWEN CHARLES S. 
Published: July 2007

SummaryPeroxidase‐conjugated anti‐surface immunoglobulin (slg) was used quantitatively to monitor endocytosis of crosslinked sIg on murine B lymphocytes. The role of biochemical second messengers in the initiation of endocytosis was assessed by employing several inhibitors. A novel peroxidase detection system was used and temperature‐dependent decreases in sIg density on immunoperoxidase‐labelled murine lymphocytes were monitored. Metabolic inhibitors as well as colchicine and cytochalasin D were utilized to confirm that the internalization of sIg could be blocked by classical inhibitors of the endocytosis process. The role of tyrosine kinase activity was established by the fact that endocytosis was significantly reduced with 100 μg/mL genistein. Experiments using EGTA or 1,2‐bis(β‐aminophenoxy)ethane‐N‐N,N′‐tetraacetic acid (BAPTA) to chelate Ca2+ indicated that Ca2+ plays little role m endocytosis. Likewise, protein kinase C (PKC) was not found to be involved in endocytosis, as activation of PKC with 50 ng/mL phorbol 12‐myristate 13‐acetate, or inhibition of the enzyme with 1 nmol/L or 5 nmol/L staurosporin, did not modulate endocytosis. Taken together, results suggested that ligand‐induced endocytosis of antigen receptors is mediated primarily through localized membrane events and is not dependent upon the classical B lymphocyte activation signals, such as the biochemical events in the inositol phosphate cascade.
Recombinant viral vaccines for enzootic bovine leucosis
Authors: DANIEL R. C. W. , GATEI M. H. , GOOD M. F. , BOYLE D. B. , LAVIN M. F. 
Published: July 2007

SummaryRecently published studies on the development and use of recombinant vaccinia virus (VV) vaccines incorporating either the complete envelope (env) gene or only a fragment of the env gene consisting of the coding sequence for the env glycoprotein 51 (gp51) and part of gp30 of the bovine leukaemia virus (BLV) are described. It has been reported that vaccination of sheep with recombinant VY vaccines containing the complete env gene appears to protect sheep against challenge infection with BLV. The evidence for this protection is based on the lack of persistence of high titres of anti‐gp51 antibodies compared with unvaccinated BLV infected controls, on the enhanced CD4 proliferative responses to specific BLV gp51 synthetic peptides in the vaccinated sheep, and on the inability to detect BLV pro‐virus by polymerase chain reaction in the vaccinated sheep after 4 months following challenge infection compared with continual detection in unvaccinated sheep over a 16 month trial period. It has been suggested that cell‐mediated immune responses may be an important aspect of protective immunity against BLV infection and it has been reported that large tracts of amino acid sequences within the env and pol genes are highly conserved in different isolates from different countries which is of importance in designing peptide derived vaccines.
Differential expression of surface antigens on activated endothelium
Authors: FAVALORO EMMANUEL J. 
Published: July 2007

SummaryEndothelial cells lining the vasculature participate in a variety of physiological processes. Following cell activation, functional changes are accompanied by changes in the surface structure (or phenotype) of these cells. Studies to date have tended to concentrate on selective changes induced with one or two surface molecules. The following study uses a different approach, having assessed potential changes to the endothelial cell surface using a large number (> 120) of previously untested monoclonal antibodies, and the cytokines TNF‐α and γ‐IFN, as well as the proteolytic enzyme thrombin. Antibody representatives from all cluster of differentiation groups CD1 through to CD54 were assessed in these studies, which used human umbilical vein endothelial cells. In line with previous observations, antibodies within CD9, CD13, CD26, CD29, CD31, CD34, CD44, CD46, CD47, CD49, CD51 and CD54 gave significant and consistent reactivity using non‐stimulated (‘quiescent’) endothelium. Using parallel cells differentially stimulated with TNF‐α, γ‐IFN or thrombin, antibodies within CD1 through to CD15, CDwl7 to CD19, CD21 to CD23, CD26, CD27, CD29, CD30, CD33 to CD35, CD37, CD38, CD40, CD43 to CD46, CD48, CD51 to CD53 failed to provide any consistent alteration to reactivity patterns compared to non‐stimulated cells. There did, however, appear to be some activation induced changes using antibodies within the other CD groups (i.e. CD16, CD20, CD24, CD25, CD28, CD31, CD32, CD36, CD39, CD41, CD42, CD47, CD49, CD50 and CD54) which ranged from minor to significant in scope and magnitude.
Human natural killer (NK) cells: Requirements for cell proliferation and expansion of phenotypically novel subpopulations
Authors: WARREN HILARY S. , KINNEAR BEVERLEY F. , SKIPSEY LOUISE J. 
Published: July 2007

SummaryPrevious studies established that the high density (resting) natural killer (NK) cell subset (R‐NK) of peripheral blood NK cells is unresponsive to interleuk:in‐2 (IL‐2) but can be induced to proliferate when cultured with γ‐irradiated malignant melanoma (MM‐170) cells or mitomycin‐C treated activated T cells in the presence of an IL‐2 conditioned medium (IL‐2‐CM). This study has examined additional requirements of this activation process. The induction of proliferation was dependent on cell to cell contact with metabolically active stimulator cells, although no evidence was obtained that stimulation was effected by soluble factors produced by the stimulator cells. Compared with IL‐2‐CM, rIL‐2 was an inefficient costimulator for the induction of NK cell proliferation, suggesting that factors in IL 2‐CM were required in addition to IL‐2, but rIL‐2 was as efficient as IL‐2‐CM in maintaining the proliferation of activated NK cells. Under optimum culture conditions, NK growth of up to 3200‐fold occurred during a proliferation cycle of 18 days. Phenotypic analysis of the culture‐generated quiescent NK cells revealed novel heterogeneity in CD 16 (FcγRIII) and CD56 (N‐CAM) expression. Some NK cells lacked expression of both CD16 and CD56 (as identified using currently available monoclonal antibodies), while other NK cells showed differential CD 16 epitope expression. Since quiescent NK cells can be obtained in large numbers and high purity, they will be a convenient source of NK cells to study the molecular processes involved in initiating NK cell proliferation.
Natural killer and natural cytotoxic cells are present at the maternal‐fetal interface during murine pregnancy
Authors: CLARKE G. R. , ROBERTS T. K. , SMART Y. C. 
Published: July 2007

SummaryNK cell activity has been detected in the early murine decidua, and hypothesized to be mediated by granulated metrial gland (GMG) cells. The possibility that natural cytotoxic (NC) cells are also present in the decidua has not been investigated. In this study mAb to NK cells (anti‐NK‐1.1) and NC cells (anti‐NC‐1.1) were used to characterize the decidual cells of days 8–14 pregnant (CBAxC57BL/6) Fl mice. Flow cytometric and immunohistological analyses showed predominantly NK‐1.1+ and NC‐1.1+ large and granular single nucleated decidual cells with abundant cytoplasm. A ‘bright’ and a ‘dim’ subset were identified for both NK‐1.1+ and NC‐1.1+ cells. The NC‐1.1dim and NK‐1.1dim cells increased in number and size as pregnancy progressed. When tested in 51Cr‐release assays, the decidual cells showed significant levels of both NK and NC activities which increased with progression of pregnancy. The NK and NC activities were partially inhibited (47 and 34%) by preincubation of the decidual cells with anti‐NC‐1.1 and complement (C), or anti‐NC‐1.1 alone. Results indicate that natural cell‐mediated cytotoxicity in the decidua is in part, at least, mediated by NK‐1.1+ and NC‐l.l+ cells, and that the NK‐1.1dim and NC‐1.1dim cells are very likely to be GMG cells. This is the first report of NC cells in the mouse uterus.
Single‐chain antibody variable region‐targeted interleukin‐2 stimulates T cell killing of human colorectal carcinoma cells
Authors: XIANG JIM , LIU ENWU , MOYANA TERENCE , QI YUMIN 
Published: July 2007

SummaryRecombinant DNA techniques were used to clone, construct and express the bifunctional molecule FV/IL‐2. The FV/IL‐2 is a single‐chain 37kDa fusion protein expressed in Escherichia coli under control of the strong T7 bacteriophage promoter in the expression vector pT7‐7‐FV‐lL‐2. The fused gene fragment FV‐IL‐2 contains a single‐chain anti‐TAG72 FV gene fragment and the human recombinant cDNA fragment of the IL‐2 molecule. The renatured soluble form of FV/IL‐2 was purified from E. coli inclusion bodies using hydroxylapatite chromatography. The yield of this fusion protein was estimated at 2.0 mg/L. Our data showed that the FV/IL‐2 molecule retained the TAG72 antigen‐binding specificity and the IL‐2 activity as measured in the standard T cell proliferation as well as cytotoxicity assays. Therefore, it may prove to be useful in targeting the biological effect of lL‐2 to tumour cells and stimulating its immune destruction.
Plasmodium falciparum and blood monocyte induced abnormalities in human erythrocyte cation homeostasis
Authors: MOHAN K. , DUBEY M. L. , GANGULY N. K. , MAHAJAN R. C. 
Published: July 2007

SummaryThe role of Plasmodium falciparum and activated blood monocytes in bringing about erythrocyte membrane lipid peroxidation and in altering the enzyme activity associated with Ca2+ and K+ efflux was studied. An attempt was made to investigate the role of parasite and monocyte‐mediated reactive oxygen species (ROS) in inhibiting Ca2+ ‐Mg2+ ATPase and Na+‐K+ ATPase in order to find out the cause of reported high intra‐erythrocytic calcium and depleted potassium levels in parasitized erythrocytes (PRBC). The PRBC showed enhanced lipid peroxidation as indicated by increased malonyldialdehyde (MDA) formation which coincided with the maturity of the parasite. This was further enhanced following exposure of PRBC to activated blood monocytes. The Ca2+‐Mg2+ ATPase activity was decreased as the parasite matured and was further hampered significantly in mature parasite‐infected red cells exposed to activated blood monocytes. There was a good negative correlation between MDA formation and Ca2+‐efflux from red blood cells suggesting the negative influence of ROS on Ca2+‐efflux. The Na+‐K+ ATPase activity did not reveal any significant change, both during parasite maturation as well as upon exposure to ROS from activated monocytes. We therefore suggest that inhibition of Ca2+‐efflux and the resulting increased cytosolic Ca+ in PRBC might have a role in structural and functional abnormalities of red blood cell, thus enhancing the red cell loss during P. falciparum infection.
A cell‐surface opsonic receptor on leucocytes from the phylogenetically primitive vertebrate, Eptatretus stouti
Authors: RAISON ROBERT L. , COVERLEY JENNIFER , HOOK JEFFREY W. , TOWNS PETER , WESTON KATHRYN M. , RAFTOS DAVID A. 
Published: July 2007

SummaryA humoral recognition molecule that is homologous to the mammalian complement components C3, C4 and C5 has recently been identified in the Pacific hagfish, Eptatretus stouti. One function of this complement‐like protein (CLP) is to opsonize foreign material for phagocytosis by hagfish leucocytes. Here, we demonstrate that CLP's opsonic activity can be abrogated by pre‐incubating phagocytes with an anti‐hagfish leucocyte mAb (IBI). Moreover, antigen‐activated CLP can block the binding of the IBI antibody to hagfish leucocytes. Flow cytometry and immunoprecipitation indicate that IBI recognizes a 105 kDa cell‐surface, monomeric protein that is expressed exclusively on phagocytic hagfish leucocytes. It is concluded that this 105 kDa protein represents the cell surface receptor by which CLP mediates the phagocytosis of opsonized targets.
Immunosuppression by lymphokine‐activated murine killer cell line with B‐lymphoblast‐lytic activity in vitro
Authors: IKEMOTO M. , SUZUKI H. , SUGIYAMA E. , YAMASHITA N. , TUNRU I. S. , MATSUI S. , KOBAYASHI M. 
Published: July 2007

SummaryThe in vitro immunosuppressive effect caused by a murine lymphokine‐activated killer cell line with B‐lymphoblast‐lytic activity was studied. The cloned cells (named BC‐1.10, phenotype Thy1.2+ LFA‐1+, TCR‐αβ−, TCR‐γδ−, FcγRII−, CD2−, CD3ε−, CD4−, CD8− and express mRNA of ζ chain) suppressed LPS‐induced Ig synthesis by B lymphoblasts previously stimulated with LPS. Phasecontrast microscopy indicated disappearance of B lymphoblasts at 24 h after the addition of BC‐1.10 cells. This suppressive effect was reduced when BC‐1.10 cells were pretreated with anti‐LFA‐1 mAb, which inhibits cytotoxicity of this clone. These data suggest that the immunosuppressive effect of BC‐1.10 is due to an elimination of B lymphoblasts, and that one of the physiological functions of lymphokine‐activated killer (LAK) cells, which are induced as a consequence of immune reactions, might be immunosuppression.
Lack of correlation between early intracellular calcium ion rises and the onset of apoptosis in thymocytes
Authors: BEAVER JOANNE P. , WARING PAUL 
Published: July 2007

SummaryApoptosis, a well‐recognized process of cell death, is usually defined by chromatin condensation, plasma membrane blebbing, reduction in cell volume, and in many cell types the cleavage of DNA into nucleosomal multiples, and finally the formation of apoptotic bodies. We have characterized the time of onset and the range of concentrations at which the toxins gliotoxin and thapsigargin induce apoptosis in thymocytes. We also looked for early changes in cytosolic calcium ion concentration ([Ca‐2+]i). Three methods were used to detect apoptosis: cellular morphology, DNA fragmentation and a flow cytometric method using ethidium bromide. Calcium fluxes were measured using both flow cytometry and bulk cell fluorimetry. Gliotoxin concentrations of 50 nmol/L to 10μmol/L induced significant numbers of cells to become apoptotic in a dose dependent manner. At these concentrations there was no observable increase in [Ca2+]i as determined by flow cytometry or in bulk cells. However, when thymocytes were treated with gliotoxin at concentrations greater than 500 μmol/L, rises in [Ca‐2+]i were apparent, but these cells died by necrosis. Thapsigargin induced low levels of apoptosis in thymocytes; the maximum effect observable after a 10 nmol/L treatment. Thapsigargin is known to inhibit the Ca2+‐ATPase in the endoplasmic reticulum thereby causing a sustained increase in [Ca2+]i in thymocytes. The rise in [Ca2+]i observed was quantitatively similar when thymocytes were treated with thapsigargin concentrations ranging between 10 and 100 nmol/L. These results led us to investigate the effect of dexamethasone on [Ca2+]i, In these experiments thymocytes showed no rises in [Ca2+]i above the control over 85 min following treatment with 10 μmol/L dexamethasone.
Production and characterization of muse thymic epithelial cell clones
Authors: GEORGIOU HARRY M. , CONSTANTINOU DORA 
Published: July 2007

SummaryFour thymic epithelial cell lines (TEC) were derived from neonatal CBA and non‐obese diabetic (NOD) mouse thymus. From these cell lines a series of clones were produced by limit dilution and these have remained in stable culture for more than 1 year. Morphological characterization indicates that most cells are stellate with numerous short or long processes and ultrastructural studies show both active and quiescent cells with junctional complexes and bundles of tonofibrils. Immunohistochemical and flow cytometric analyses show that the cells express cytokeratin and appear to label for markers characteristic of cortical epithelial cells. Most clones express Thy‐1, Pgp‐l. ICAM‐1. HSA and B220 antigen, but are negative for LFA‐1. CD2, Mel 14, Fc receptor, Mac‐1, CD4 and CD8. All clones express low to moderate levels of class I MHC but are either negative or extremely low for class II MHC antigen. Most clones secrete IL‐6 and granulocyte‐macrophage‐CSF (GM‐CSF) in vitro, but generally do not produce IL‐2. IL‐3. IL‐4 or IFN‐γ.