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Small Subpopulation (small + subpopulation)
Selected AbstractsCD4 T,cell activation by myelin oligodendrocyte glycoprotein is suppressed by adult but not cord blood CD25+ T,cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2003Kajsa Wing Abstract Regulatory T,cells expressing CD25 have been shown to protect rodents from organ-specific autoimmune diseases. Similar CD25+ cells with a memory phenotype exerting suppressive function after polyclonal or allogeneic stimulation are also present in adult human blood. We demonstrate that adult human CD25+ cells regulate the response to myelin oligodendrocyte glycoprotein (MOG), as depletion of CD25+ cells increases responses of PBMC and the addition of purified CD25+ cells suppresses MOG-specific proliferation and IFN-, production of CD4+CD25, T,cells. In contrast, cord blood CD25+ cells do not inhibit responses to self antigens, and only a small subpopulation of cord CD25+ cells expresses the typical phenotype of adult regulatory T,cells (CD45RA, and GITR+) enabling suppression of polyclonal responses. We conclude that activation of self-reactive T,cells in normal healthy individuals is prevented by the presence of self-antigen-specific CD25+ regulatory T,cells and that the majority of these cells mature after birth. [source] Neuropilin-1 expression identifies a subset of regulatory T cells in human lymph nodes that is modulated by preoperative chemoradiation therapy in cervical cancerIMMUNOLOGY, Issue 1 2008Alessandra Battaglia Summary We examined the phenotype and function of CD4+ T cells expressing the semaphorin III receptor neuropilin-1 (Nrp1) in human lymph nodes and peripheral blood. In lymph nodes, Nrp1 identified a small regulatory CD4+ CD25high T-cell subpopulation (Nrp1+ Treg) that expressed higher levels of Forkhead box P3 (Foxp3) message and protein than Nrp1, Treg, and various molecular markers of activated Treg, i.e. CD45RO, human leucocyte antigen (HLA)-DR and glucocorticoid-induced tumour necrosis factor receptor (GITR). Similarly to conventional Treg, Nrp1+ Treg proliferated poorly in vitro, and exerted contact-dependent in vitro suppression of T-cell proliferation and cytokine secretion. However, Nrp1+ Treg were more efficient than Nrp1, Treg at inducing suppression. Nrp1 was also expressed on a small subpopulation of CD25int and CD25, CD4+ T cells that expressed more Foxp3, CD45RO, HLA-DR and GITR than their Nrp1, counterparts. In contrast, in peripheral blood Nrp1 identified a minor CD4+ T-cell subset that did not display the phenotypic features of Treg lacking Foxp3 expression and marginally expressing CD25. Hence, the function of Nrp1+ CD4+ T cells seemingly depends on their anatomical location. In a previous report, we proposed that Treg may curb the anti-tumour T-cell response in cervical cancer. We show here that Treg and Nrp1+ Treg levels dropped in the tumour-draining lymph nodes of patients with cervical cancer following preoperative chemoradiotherapy in a direct relationship with the reduction of tumour mass, suggesting that suppressor cell elimination facilitated the generation of T cells mediating the destruction of the neoplastic cells left behind after cytotoxic therapy. [source] Role of kainate receptor activation and desensitization on the [Ca2+]i changes in cultured rat hippocampal neuronsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2001Ana P. Silva Abstract We investigated the role of kainate (KA) receptor activation and desensitization in inducing the increase in the intracellular free Ca2+ concentration ([Ca2+]i) in individual cultured rat hippocampal neurons. The rat hippocampal neurons in the cultures were shown to express kainate receptor subunits, KA2 and GluR6/7, either by immunocytochemistry or by immunoblot analysis. The effect of LY303070, an ,-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor antagonist, on the alterations in the [Ca2+]i caused by kainate showed cell-to-cell variability. The [Ca2+]i increase caused by kainate was mostly mediated by the activation of AMPA receptors because LY303070 inhibited the response to kainate in a high percentage of neurons. The response to kainate was potentiated by concanavalin A (Con A), which inhibits kainate receptor desensitization, in 82.1% of the neurons, and this potentiation was not reversed by LY303070 in about 38% of the neurons. Also, upon stimulation of the cells with 4-methylglutamate (MGA), a selective kainate receptor agonist, in the presence of Con A, it was possible to observe [Ca2+]i changes induced by kainate receptor activation, because LY303070 did not inhibit the response in all neurons analyzed. In toxicity studies, cultured rat hippocampal neurons were exposed to the drugs for 30 min, and the cell viability was evaluated at 24 hr using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The selective activation of kainate receptors with MGA, in the presence of Con A, induced a toxic effect, which was not prevented by LY303070, revealing a contribution of a small subpopulation of neurons expressing kainate receptors that independently mediate cytotoxicity. Taken together, these results indicate that cultured hippocampal neurons express not only AMPA receptors, but also kainate receptors, which can modulate the [Ca2+]i and toxicity. J. Neurosci. Res. 65:378,386, 2001. © 2001 Wiley-Liss, Inc. [source] The course and correlates of high hospital utilization in sickle cell disease: Evidence from a large, urban Medicaid managed care organization,AMERICAN JOURNAL OF HEMATOLOGY, Issue 10 2009C. Patrick Carroll Although most patients with sickle cell disease (SCD) are hospitalized infrequently and manage painful crises at home, a small subpopulation is frequently admitted to emergency departments and inpatient units. This small group accounts for the majority of health care expenses for patients with SCD. Using inpatient claims data from a large, urban Medicaid MCO for 5 consecutive years, this study sought to describe the course of high inpatient utilization (averaging four or more admissions enrolled per year for at least 1 year) in members with a diagnosis of SCD and a history of hospitalizations for vaso-occlusive crisis. High utilizers were compared with the other members with SCD on demographics, medical and psychiatric comorbidity, and use of other health care resources. Members who were high utilizers had more diagnostic mentions of sickle cell complications than low utilizers. However, the pattern of high inpatient utilization was likely to moderate over successive years, and return to the pattern after moderation was uncommon. Despite this, a small subpopulation engaged in exceptional levels of inpatient utilization over multiple years. Am. J. Hematol., 2009. © 2009 Wiley-Liss, Inc. [source] Developmental reorientation of transverse cortical microtubules to longitudinal directions: a role for actomyosin-based streaming and partial microtubule-membrane detachmentTHE PLANT JOURNAL, Issue 1 2008Frank Sainsbury Summary Transversely oriented cortical microtubules in elongating cells typically reorient themselves towards longitudinal directions at the end of cell elongation. We have investigated the reorientation mechanism along the outer epidermal wall in maturing leek (Allium porrum L.) leaves using a GFP-MBD microtubule reporter gene and fluorescence microscopy. Incubating leaf segments for 14,18 h with the anti-actin or anti-actomyosin agents, 20 ,m cytochalasin D or 20 mm 2,3-butanedione monoxime, inhibited the normal developmental reorientation of microtubules to the longitudinal direction. Observation of living cells revealed a small subpopulation of microtubules with their free ends swinging into oblique or longitudinal directions, before continuing to assemble in the new direction. Electron microscopy confirmed that longitudinal microtubules are partly detached from the plasma membrane. Incubating leaf segments with 0.2% 1°-butanol, an activator of phospholipase D, which has been implicated in plasma membrane,microtubule anchoring, promoted the reorientation, presumably by promoting microtubule detachment from the membrane. Stabilizing microtubules with 10 ,m taxol also promoted longitudinal orientation, even in the absence of cytoplasmic streaming. These results were consistent with confocal microscopy of live cells before and after drug treatments, which also revealed that the slow (days) global microtubule reorientation is superimposed over short-term (hours) regional cycling in a clockwise and an anti-clockwise direction. We propose that partial detachment of transverse microtubules from the plasma membrane in maturing cells exposes them to hydrodynamic forces of actomyosin-driven cytoplasmic streaming, which bends or shifts pivoting microtubules into longitudinal directions, and thus provides an impetus to push microtubule dynamics in the new direction. [source] Effective size of harvested ungulate populationsANIMAL CONSERVATION, Issue 5 2009B.-E. Sęther Abstract The harvest of ungulate populations is often directed against certain sex or age classes to maximize the yield in terms of biomass, number of shot animals or number of trophies. Here we examine how such directional harvest affects the effective size of the population. We parameterize an age-specific model assumed to describe the dynamics of Fennoscandian moose. Based on expressions for the demographic variance for a small subpopulation of heterozygotes Aa bearing a rare neutral allele a, we use this model to calculate how different harvest strategies influence the effective size of the population, given that the population remains stable after harvest. We show that the annual genetic drift, determined by , increases with decreasing harvest rate of calves and increasing sex bias in the harvest towards bulls 1 year or older. The effective population size per generation decreased with reduced harvest of calves and increased harvest of bulls 1 year or older. The magnitude of these effects depends on the age-specific pattern of variation in reproductive success, which influences the demographic variance. This shows that the choice of harvest strategy strongly affects the genetic dynamics of harvested ungulate populations. [source] A population analysis of VEGF transgene expression and secretionBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2008Golnaz Karoubi Abstract The induction of therapeutic angiogenesis with gene therapy approaches has received considerable interest and some limited clinical success. A major drawback to this approach is a lack of understanding of the pharmacokinetics of therapeutic protein delivery. This has become increasingly more relevant as recent studies have illustrated a defined therapeutic window for angiogenic protein secretion into the local microenvironment. For cell based gene therapies, with cells widely distributed throughout the tissue, this implies that any individual cell must attain a specific secretion rate to produce a local angiogenic response. Here we report a reproducible technique enabling the study of growth factor secretion from individual cells following transient plasmid transfection. We demonstrate significant variability in single cell vascular endothelial growth factor (VEGF) secretion with the majority of total protein secretion arising from a small subpopulation of transfected cells. We demonstrate that VEGF secretion is linearly correlated to intracellular plasmid copy number and protein secretion does not appear to reach saturation within the cell population. The selection of gene therapy approaches that optimize individual cell secretion profiles may be essential for the development of effective gene therapies. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc. [source] HETEROZYGOTE EXCESS IN SMALL POPULATIONS AND THE HETEROZYGOTE-EXCESS EFFECTIVE POPULATION SIZEEVOLUTION, Issue 9 2004Franclois Balloux Abstract It has been proposed that effective size could be estimated in small dioecious population by considering the heterozygote excess observed at neutral markers. When the number of breeders is small, allelic frequencies in males and females will slightly differ due to binomial sampling error. However, this excess of heterozygotes is not generated by dioecy but by the absence of individuals produced through selfing. Consequently, the approach can also be applied to self-incompatible monoecious species. Some inaccuracies in earlier equations expressing effective size as function of the heterozygote excess are also corrected in this paper. The approach is then extended to subdivided populations, where time of sampling becomes crucial. When adults are sampled, the effective size of the entire population can be estimated, whereas when juveniles are sampled, the average effective number of breeders per subpopulations can be estimated. The main limitation of the heterozygote excess method is that it will only perform satisfactorily for populations with a small number of reproducing individuals. While this situation is unlikely to happen frequently at the scale of the entire population, structured populations with small subpopulations are likely to be common. The estimation of the average number of breeders per subpopulations is thus expected to be applicable to many natural populations. The approach is straightforward to compute and independent of equilibrium assumptions. Applications to simulated data suggest the estimation of the number of breeders to be robust to mutation and migration rates, and to specificities of the mating system. [source] Growth of malignant oral epithelial stem cells after seeding into organotypical cultures of normal mucosaJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 2 2004Ian C. Mackenzie Background:, Oral squamous cell carcinoma (OSCC) is associated both with the local expansion of clones of malignant cells and with their further migration to regional and distant sites. The interactions that occur between normal and malignant cells during these events are not well modelled by standard culture conditions, but organotypical cultures, in which epithelial cells are grown on a matrix containing fibroblasts, provide a suitable environment for such investigations. Methods:, Cells from five cell lines, each derived from OSCC and marked by retroviral transduction with alkaline phosphatase, were incorporated as small subpopulations (0.1,5%) in uniformly differentiating organotypical cultures constructed from normal oral mucosal cells. The patterns of growth of the malignant cells within the normal epithelium were examined for 3 weeks. Results:, There was variation between the different cell lines in their rates and patterns of growth, but all cell lines produced clusters of malignant cells that had expanded within 3 weeks to replace the normal epithelium. The appearance and spacing of these clusters suggested that each was derived from a single progenitor cell. The number of malignant cells initially present within a given area of organotypical epithelium was much greater than the number of expanding cell clusters subsequently formed. Cluster-forming cells thus represented only a subpopulation of the tumour cells. Conclusions:, The organotypical model allows examination of interactions occurring between cells derived from OSCC and normal epithelia. The three-dimensional nature of organotypical cultures, together with their more normal patterns of differentiation, provides an environment that more closely mimics the in vivo environment in which tumours develop. The finding that only a subpopulation of tumour cells forms expanding tumour colonies suggests a range of growth potentials within a tumour population and may provide preliminary evidence for some form of stem and amplifying cell pattern. [source] The Cocaine- and Amphetamine-regulated Transcript (CART) Immunoreactivity in the Amygdala of the PigANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2010M. Równiak With 5 figures and 1 table Summary The distribution and morphology of neurons containing cocaine- and amphetamine-regulated transcript (CART) was investigated in the pig amygdala. CART- immunoreactive (CART-IR) cell bodies were rarely observed in the pig amygdala and most often they were present in the posterior (small-celled) parts of the basolateral and basomedial nuclei. In all other subdivisions only a small number of randomly scattered pericarya were present. In every region studied the CART-IR neurons formed a heterogeneous population consisting mostly of small, rounded or slightly elongated cell bodies, with a few poorly branched, smooth dendrites. In general, the morphological features of these cells clearly resembled non-pyramidal Golgi type II interneurons. Some randomly scattered CART-IR cell bodies were significantly larger and they demonstrated features of pyramidal-like Golgi type I projecting neurons. The highest densities of CART-IR fibres were evident within the central and medial nuclei. Moderate to high expression was found within the large-celled part of the basolateral nucleus and moderate to low levels in the lateral, basomedial and cortical nuclei. The routine double-labelling studies with antisera directed against CART and somatostatin (SOM), or neuropeptide Y (NPY), or cholecystokinin (CCK), or vasoactive intestinal peptide (VIP), or substance P (SP) demonstrated that, in general, these peptides do not co-exist in the CART-IR neurons. However, small subpopulations of the CART-IR fibres contained SOM, CCK, VIP or SP together. [source] Low Frequency of Chromosomal Imbalances in Anaplastic Ependymomas as Detected by Comparative Genomic HybridizationBRAIN PATHOLOGY, Issue 2 2001Stefanie Scheil We screened 26 ependymomas in 22 patients (7 WHO grade I, myxopapillary, myE; 6 WHO grade II, E; 13 WHO grade III, anaplastic, aE) using comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). 25 out of 26 tumors showed chromosomal imbalances on CGH analysis. The chromosomal region most frequently affected by losses of genomic material clustered on 13q (9/26). 6/7 myE showed a loss on 13q14-q31. Other chromosomes affected by genomic losses were 6q (5/26), 4q (5/26), 10 (5/26), and 2q (4/26). The most consistent chromosomal abnormality in ependymomas so far reported, is monosomy 22 or structural abnormality 22q, identified in approximately one third of Giemsabanded cases with abnormal karyotypes. Using FISH, loss or monosomy 22q was detected in small subpopulations of tumor cells in 36% of cases. The most frequent gains involved chromosome arms 17 (8/26), 9q (7/26), 20q (7/26), and 22q (6/26). Gains on 1q were found exclusively in pediatric ependymomas (5/10). Using FISH, MYCN proto-oncogene DNA amplifications mapped to 2p23-p24 were found in 2 spinal ependymomas of adults. On average, myE demonstrated 9.14, E 5.33, and aE 1.77 gains and/or losses on different chromosomes per tumor using CGH. Thus, and quite paradoxically, in ependymomas, a high frequency of imbalanced chromosomal regions as revealed by CGH does not indicate a high WHO grade of the tumor but is more frequent in grade I tumors. [source] Characterization within and around the Limbal Epithelial CryptACTA OPHTHALMOLOGICA, Issue 2007AM YEUNG Purpose: The Limbal Epithelial Crypt (LEC) is an anatomical structure that is found between the junction of the cornea and sclera and is in a unique position to make it an ideal structure to examine further. Previous studies have demonstrated the LEC to have properties that suggest it may be a stem cell niche. Basal cells of the LEC are significantly smaller than basal cells found in adjacent rete pegs, and morphologically they have a higher nuclear:cytoplasmic ratio. We set out to examine LEC further by exploring the surrounding LEC matrix proteins, and with known differentiation markers. Methods: Donated corneo-sclero rims were cut into eight equal sized pieces and frozen. Each piece was cut into 7,m serial sections, and was examined by microscopy for LEC structures. Identified LEC was collected on slides and stored until they were fixed in acetone and processed by standard immunofluorescence techniques for each differentiation marker. Results: Tenacin C was more positively taken up by the basement membrane of the LEC compared with the surrounding limbus. In addition, staining for desmoglein was negative against isolated small subpopulations of cells within the basal regions of the LEC. Conclusions: The LEC structure demonstrates properties that may identify this as a possible stem cell niche. Further studies are necessary to determine the significance of the LEC in its role in stem cell maintenance. [source] | |||||||||||||