Publications (43)143.32 Total impact
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Article: Class III β-Tubulin and γ-Tubulin are Co-expressed and Form Complexes in Human Glioblastoma Cells
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ABSTRACT: We have previously shown that the neuronal-associated class III β-tubulin isotype and the centrosome-associated γ-tubulin are aberrantly expressed in astrocytic gliomas (Cell Motil Cytoskeleton 2003, 55:77-96; J Neuropathol Exp Neurol 2006, 65:455–467). Here we determined the expression, distribution and interaction of βIII-tubulin and γ-tubulin in diffuse-type astrocytic gliomas (grades II-IV) (n=17) and the human glioblastoma cell line T98G. By immunohistochemistry and immunofluorescence microscopy, βIII-tubulin and γ-tubulin were co-distributed in anaplastic astrocytomas and glioblastomas and to a lesser extent, in low-grade diffuse astrocytomas (P<0.05). In T98G glioblastoma cells βIII-tubulin was associated with microtubules whereas γ-tubulin exhibited striking diffuse cytoplasmic staining in addition to its expectant centrosome-associated pericentriolar distribution. Treatment with different anti-microtubule drugs revealed that βIII-tubulin was not associated with insoluble γ-tubulin aggregates. On the other hand, immunoprecipitation experiments unveiled that both tubulins formed complexes in soluble cytoplasmic pools, where substantial amounts of these proteins were located. We suggest that aberrant expression and interactions of βIII-tubulin and γ-tubulin may be linked to malignant changes in glial cells.Neurochemical Research 04/2012; 32(8):1387-1398. · 2.24 Impact Factor -
Article: Tubulins as therapeutic targets in cancer: from bench to bedside.
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ABSTRACT: Tubulin is the target of some of the most widely used and time-honored anticancer tubulin-binding agents (TBAs). The clinical usefulness of many TBAs has been held back as a result of tumor cell drug-resistance. The elucidation of the three-dimensional structure of αβ-tubulin dimer has provided an opportunity for rational drug design aimed at generating compounds that will target tubulin in therapeutically more efficacious ways compared to presently available drugs. An issue to be addressed is which one(s) of the tubulin species, their isotypes, or their posttranslationally modified forms, should be specifically targeted in cancer chemotherapy. This review offers a critical appraisal of current knowledge on tubulins in cancer and an update on new anti-neoplastic microtubule-targeted treatment strategies. Specifically, it examines, across disciplines, cellular/molecular, biochemical, clinical/pathological, and pharmacological aspects of β-tubulin isotypes, posttranslational modifications of tubulin dimers, γ-tubulin and microtubule nucleation, and microtubule regulatory proteins. Emphasis is placed on the overexpression of (i) the βIII isotype, which functions as a survival factor associated with dynamic instability of microtubules; (ii) γ-tubulin, a key microtubule nucleating protein; and (iii) the microtubule severing enzyme spastin, involved in cell motility and proliferation of glioblastoma cells. The role of βIII-tubulin in resistance of cancer cells to taxanes is examined. Attention is called to the novel concept that βIII-tubulin functions as a "gateway" for prosurvival signals in partnership with GTPases, such as GBP1. Appraisal is also offered on epothilones and the concept of hypersensitization to TBAs as promising therapeutic strategies in taxane resistant epithelial cancers and in high-grade gliomas.Current pharmaceutical design 02/2012; 18(19):2778-92. · 4.41 Impact Factor -
Article: Patterns of cognitive and fine motor deficits in a case of Dandy-Walker continuum.
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ABSTRACT: Cerebellar vermian hypoplasia in the context of Dandy-Walker complex is a relatively common disorder associated with a variety of cognitive and behavioral deficits in addition to impairment in motor control. Few studies, however, have examined the neuropsychological profiles of children with isolated hypoplasias of the cerebellum. Herein, we report a 6-year-old girl with Dandy-Walker continuum presenting with mild mental retardation and an inability to produce intelligible speech, despite adequate comprehension of single items and simple instructions. She was able to articulate vowels but not consonants, and fine motor function was deficient. Visual memory was intact for single items but not for multiple items, and visuospatial perception was impaired. An inability to form intelligible speech is not typically reported in cases of isolated vermian hypoplasia. The case extends our knowledge of the phenotypes associated with cerebellar hypoplasia and its relation to fine motor and articulatory control.Journal of child neurology 01/2012; 27(7):930-7. · 1.59 Impact Factor -
Article: Astrocyte senescence as a component of Alzheimer's disease.
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ABSTRACT: Aging is the main risk factor for Alzheimer's disease (AD); however, the aspects of the aging process that predispose the brain to the development of AD are largely unknown. Astrocytes perform a myriad of functions in the central nervous system to maintain homeostasis and support neuronal function. In vitro, human astrocytes are highly sensitive to oxidative stress and trigger a senescence program when faced with multiple types of stress. In order to determine whether senescent astrocytes appear in vivo, brain tissue from aged individuals and patients with AD was examined for the presence of senescent astrocytes using p16(INK4a) and matrix metalloproteinase-1 (MMP-1) expression as markers of senescence. Compared with fetal tissue samples (n = 4), a significant increase in p16(INK4a)-positive astrocytes was observed in subjects aged 35 to 50 years (n = 6; P = 0.02) and 78 to 90 years (n = 11; P<10(-6)). In addition, the frontal cortex of AD patients (n = 15) harbored a significantly greater burden of p16(INK4a)-positive astrocytes compared with non-AD adult control subjects of similar ages (n = 25; P = 0.02) and fetal controls (n = 4; P<10(-7)). Consistent with the senescent nature of the p16(INK4a)-positive astrocytes, increased metalloproteinase MMP-1 correlated with p16(INK4a). In vitro, beta-amyloid 1-42 (Aβ(1-42)) triggered senescence, driving the expression of p16(INK4a) and senescence-associated beta-galactosidase. In addition, we found that senescent astrocytes produce a number of inflammatory cytokines including interleukin-6 (IL-6), which seems to be regulated by p38MAPK. We propose that an accumulation of p16(INK4a)-positive senescent astrocytes may link increased age and increased risk for sporadic AD.PLoS ONE 01/2012; 7(9):e45069. · 4.09 Impact Factor -
Article: Nuclear γ‐tubulin associates with nucleoli and interacts with tumor suppressor protein C53
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ABSTRACT: γ-Tubulin is assumed to be a typical cytosolic protein necessary for nucleation of microtubules from microtubule organizing centers. Using immunolocalization and cell fractionation techniques in combination with siRNAi and expression of FLAG-tagged constructs, we have obtained evidence that γ-tubulin is also present in nucleoli of mammalian interphase cells of diverse cellular origins. Immunoelectron microscopy has revealed γ-tubulin localization outside fibrillar centers where transcription of ribosomal DNA takes place. γ-Tubulin was associated with nucleolar remnants after nuclear envelope breakdown and could be translocated to nucleoli during mitosis. Pretreatment of cells with leptomycin B did not affect the distribution of nuclear γ-tubulin, making it unlikely that rapid active transport via nuclear pores participates in the transport of γ-tubulin into the nucleus. This finding was confirmed by heterokaryon assay and time-lapse imaging of photoconvertible protein Dendra2 tagged to γ-tubulin. Immunoprecipitation from nuclear extracts combined with mass spectrometry revealed an association of γ-tubulin with tumor suppressor protein C53 located at multiple subcellular compartments including nucleoli. The notion of an interaction between γ-tubulin and C53 was corroborated by pull-down and co-immunoprecipitation experiments. Overexpression of γ-tubulin antagonized the inhibitory effect of C53 on DNA damage G2/M checkpoint activation. The combined results indicate that aside from its known role in microtubule nucleation, γ-tubulin may also have nuclear-specific function(s). J. Cell. Physiol. 227: 367–382, 2012. © 2011 Wiley Periodicals, Inc.Journal of Cellular Physiology 10/2011; 227(1):367 - 382. · 3.87 Impact Factor -
Article: Cerebellar gliomatosis in a toddler: case report of a challenging condition and review of the literature.
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ABSTRACT: Gliomatosis confined to the cerebellum is most unusual. We report such a case in a 20-month-old male who presented with unsteadiness. Magnetic resonance imaging revealed a diffuse area of abnormal signal intensity within both cerebellar hemispheres, which did not enhance after contrast administration. The patient underwent a biopsy, which revealed a diffuse glioma infiltrating the cerebellum. Overall, the tumor cells had oligodendroglioma-like features and exhibited only focal vimentin immunoreactivity. They were negative for glial fibrillary acidic protein, synaptophysin, βIII-tubulin, and neurofilament protein. Immunofluorescence, performed on primary biopsy explants maintained in cell culture without exposure to growth factors or differentiation-promoting agents, revealed widespread nestin immunoreactivity and immunolabeling of occasional cells with antibodies to platelet-derived growth factor-α and O1/O4, markers of oligodendrocyte precursor-cells and immature oligodendrocytes, respectively. Fluorescent in situ hybridization performed on explants, touch preparations, and paraffin sections failed to reveal loss of heterozygosity for either 1p36 or 19q13. The patient was treated with temozolomide and remains stable, albeit with residual quiescent tumor, more than 3 years after surgery. This report calls attention to an unusual presentation of gliomatosis confined to the cerebellum of a toddler and addresses salient aspects of clinical and radiological differential diagnosis, as well as therapeutic challenges encountered.Journal of child neurology 09/2011; 27(4):511-20. · 1.59 Impact Factor -
Article: Microtubule-severing ATPase spastin in glioblastoma: increased expression in human glioblastoma cell lines and inverse roles in cell motility and proliferation.
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ABSTRACT: We studied the expression and distribution of the microtubule-severing enzyme spastin in 3 human glioblastoma cell lines (U87MG, U138MG, and T98G) and in clinical tissue samples representative of all grades of diffuse astrocytic gliomas (n = 45). In adult human brains, spastin was distributed predominantly in neuronsand neuropil puncta and, to a lesser extent, in glia. Compared with normal mature brain tissues, spastin expression and cellular distribution were increased in neoplastic glial phenotypes, especiallyin glioblastoma (p < 0.05 vs low-grade diffuse astrocytomas). Overlapping punctate and diffuse patterns of localization wereidentified in tumor cells in tissues and in interphase and mitotic cells ofglioblastoma cell lines. There was enrichment of spastin in the leading edges of cells in T98G glioblastoma cell cultures and in neoplastic cell populations in tumor specimens. Real-time polymerase chain reaction and immunoblotting experiments revealed greater levels of spastin messenger RNA and protein expression in theglioblastoma cell lines versus normal human astrocytes. Functional experiments indicated that spastin depletion resulted in reduced cell motility and higher cell proliferation of T98G cells. Toour knowledge, this is the first report of spastin involvement incellmotility. Collectively, our results indicate that spastinexpression in glioblastomas might be linked to tumor cell motility, migration, and invasion.Journal of Neuropathology and Experimental Neurology 09/2011; 70(9):811-26. · 4.26 Impact Factor -
Article: Targeting βIII-tubulin in glioblastoma multiforme: from cell biology and histopathology to cancer therapeutics.
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ABSTRACT: Glioblastoma multiforme (GBM) is the most common, aggressive, and chemorefractory brain tumor in human adults. Notwithstanding significant discoveries in the elucidation of pathways of molecular signaling and genetics of GBM during the past 20 years there has been no breakthrough in the pharmacological treatment of this high-grade malignancy. We, and others, have previously demonstrated increased expression of βIII-tubulin in GBM asserting a link between aberrant expression of this β-tubulin isotype and a disruption of microtubule dynamics associated either with malignant tumor development de novo, or with progression and malignant transformation of a low-grade glioma into GBM. This article reviews βIII-tubulin as a promising target in the experimental treatment of GBM and examines the potential use of epothilones, a new family of anticancer agents shown to be active in βIII-tubulin-expressing tumor cells, as well as the "double hit" therapeutic concept of tumor cell sensitization to tubulin binding agents (TBAs) by βIII-tubulin silencing. The latest progress regarding the function and potential role of βIII-tubulin in aggressive tumor behavior, cancer stem cells, tumor cell hypoxia, and resistance to taxane-related compounds, is also critically appraised.Anti-cancer agents in medicinal chemistry 06/2011; 11(8):719-28. -
Article: Human breast tumor cells express IL-10 and IL-12p40 transcripts and proteins, but do not produce IL-12p70.
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ABSTRACT: IL-10 transcripts were expressed in 14/15 primary breast adenocarcinomas and in 5/8 established breast tumor lines. Immunohistochemistry and immunoprecipitation from lysates and supernatants revealed that established breast tumor lines produced IL-10 protein. Immunohistochemistry revealed that IL-10 is localized to tumor cells of primary breast adenocarcinomas and to occasional infiltrating MNC. Established breast tumor cell lines expressed IL-12p40 transcripts (6/8) and protein (4/7) and IL-12p35 transcripts (6/7). Using two sandwich ELISAs, specific, respectively, for IL-12p40 and IL-12p70 proteins, we demonstrated that established breast tumor cell lines produce IL-12p40 monomer/homodimer, but not IL-12p70. Positive staining for IL-12p70 in primary breast adenocarcinomas was found only in MNC infiltrating the tumor while tumor cells were negative. IL-12p40 homodimer/monomer inhibit as antagonists IL-12 or IL-23, although they may also act as agonists and positive regulators. Also, primary breast adenocarcinomas (15/15) and established breast tumor cell lines (6/8) expressed TGF-β1 transcripts. IL-10, IL-12p40 and TGF-β1 may inhibit substantially the anti-tumor immune response.Cellular Immunology 10/2010; 266(2):143-53. · 1.97 Impact Factor -
Article: Differential expression and cellular distribution of γ‐tubulin and βIII‐tubulin in medulloblastomas and human medulloblastoma cell lines
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ABSTRACT: In previous studies, we have shown overexpression and ectopic subcellular distribution of γ-tubulin and βIII-tubulin in human glioblastomas and glioblastoma cell lines (Katsetos et al., 2006, J Neuropathol Exp Neurol 65:455–467; Katsetos et al., 2007, Neurochem Res 32:1387–1398). Here we determined the expression of γ-tubulin in surgically excised medulloblastomas (n = 20) and in the human medulloblastoma cell lines D283 Med and DAOY. In clinical tissue samples, the immunohistochemical distribution of γ-tubulin labeling was pervasive and inversely related to neuritogenesis. Overexpression of γ-tubulin was widespread in poorly differentiated, proliferating tumor cells but was significantly diminished in quiescent differentiating tumor cells undergoing neuritogenesis, highlighted by βIII-tubulin immunolabeling. By quantitative real-time PCR, γ-tubulin transcripts for TUBG1, TUBG2, and TUBB3 genes were detected in both cell lines but expression was less prominent when compared with the human glioblastoma cell lines. Immunoblotting revealed comparable amounts of γ-tubulin and βIII-tubulin in different phases of cell cycle; however, a larger amount of γ-tubulin was detected in D283 Med when compared with DAOY cells. Interphase D283 Med cells exhibited predominantly diffuse cytoplasmic γ-tubulin localization, in addition to the expected centrosome-associated distribution. Robust βIII-tubulin immunoreactivity was detected in mitotic spindles of DAOY cells. Our data indicate that overexpression of γ-tubulin may be linked to phenotypic dedifferentiation (anaplasia) and tumor progression in medulloblastomas and may potentially serve as a promising tumor marker. J. Cell. Physiol. 223: 519–529, 2010. © 2010 Wiley-Liss, Inc.Journal of Cellular Physiology 02/2010; 223(2):519 - 529. · 3.87 Impact Factor -
Article: Differential expression and cellular distribution of gamma-tubulin and betaIII-tubulin in medulloblastomas and human medulloblastoma cell lines.
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ABSTRACT: In previous studies, we have shown overexpression and ectopic subcellular distribution of gamma-tubulin and betaIII-tubulin in human glioblastomas and glioblastoma cell lines (Katsetos et al., 2006, J Neuropathol Exp Neurol 65:455-467; Katsetos et al., 2007, Neurochem Res 32:1387-1398). Here we determined the expression of gamma-tubulin in surgically excised medulloblastomas (n = 20) and in the human medulloblastoma cell lines D283 Med and DAOY. In clinical tissue samples, the immunohistochemical distribution of gamma-tubulin labeling was pervasive and inversely related to neuritogenesis. Overexpression of gamma-tubulin was widespread in poorly differentiated, proliferating tumor cells but was significantly diminished in quiescent differentiating tumor cells undergoing neuritogenesis, highlighted by betaIII-tubulin immunolabeling. By quantitative real-time PCR, gamma-tubulin transcripts for TUBG1, TUBG2, and TUBB3 genes were detected in both cell lines but expression was less prominent when compared with the human glioblastoma cell lines. Immunoblotting revealed comparable amounts of gamma-tubulin and betaIII-tubulin in different phases of cell cycle; however, a larger amount of gamma-tubulin was detected in D283 Med when compared with DAOY cells. Interphase D283 Med cells exhibited predominantly diffuse cytoplasmic gamma-tubulin localization, in addition to the expected centrosome-associated distribution. Robust betaIII-tubulin immunoreactivity was detected in mitotic spindles of DAOY cells. Our data indicate that overexpression of gamma-tubulin may be linked to phenotypic dedifferentiation (anaplasia) and tumor progression in medulloblastomas and may potentially serve as a promising tumor marker.Journal of Cellular Physiology 02/2010; 223(2):519-29. · 3.87 Impact Factor -
Article: Differential expression and cellular distribution of γ‐tubulin and βIII‐tubulin in medulloblastomas and human medulloblastoma cell lines
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ABSTRACT: In previous studies, we have shown overexpression and ectopic subcellular distribution of g-tubulin and bIII-tubulin in human glioblastomas and glioblastoma cell lines (Katsetos et al., 2006, J Neuropathol Exp Neurol 65:455–467; Katsetos et al., 2007, Neurochem Res 32:1387–1398). Here we determined the expression of g-tubulin in surgically excised medulloblastomas (n ¼ 20) and in the human medulloblastoma cell lines D283 Med and DAOY. In clinical tissue samples, the immunohistochemical distribution of g-tubulin labeling was pervasive and inversely related to neuritogenesis. Overexpression of g-tubulin was widespread in poorly differentiated, proliferating tumor cells but was significantly diminished in quiescent differentiating tumor cells undergoing neuritogenesis, highlighted by bIII-tubulin immunolabeling. By quantitative real-time PCR, g-tubulin transcripts for TUBG1, TUBG2, and TUBB3 genes were detected in both cell lines but expression was less prominent when compared with the human glioblastoma cell lines. Immunoblotting revealed comparable amounts of g-tubulin and bIII-tubulin in different phases of cell cycle; however, a larger amount of g-tubulin was detected in D283 Med when compared with DAOY cells. Interphase D283 Med cells exhibited predominantly diffuse cytoplasmic g-tubulin localization, in addition to the expected centrosome-associated distribution. Robust bIII-tubulin immunoreactivity was detected in mitotic spindles of DAOY cells. Our data indicate that overexpression of g-tubulin may be linked to phenotypic dedifferentiation (anaplasia) and tumor progression in medulloblastomas and may potentially serve as a promising tumor marker.J. Cell. Physiol. 01/2010; 223:519-529. -
Article: Tubulin targets in the pathobiology and therapy of glioblastoma multiforme. II. γ‐tubulin
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ABSTRACT: Glioblastoma multiforme (GBM) is the most common and deadliest form of primary brain cancer in adults. Despite advances in molecular biology and genetics of cancer there is no currently available treatment for these tumors. Aberrant patterns of γ-tubulin expression and compartmentalization in GBM have been reported lending credence to the assertion that these changes might underlie perturbations in microtubule nucleation and mitosis associated with glioma tumorigenesis and tumor progression. This minireview focuses on the role of γ-tubulin in the pathobiology of GBM in the light of emerging concepts concerning the function of γ-tubulin and its potential role in tumorigenesis putting forward the concept that γ-tubulin might serve as a novel marker of anaplastic change in gliomas. J. Cell. Physiol. 221: 514–520, 2009. © 2009 Wiley-Liss, Inc.Journal of Cellular Physiology 11/2009; 221(3):514 - 520. · 3.87 Impact Factor -
Article: Tubulin targets in the pathobiology and therapy of glioblastoma multiforme. I. Class III beta-tubulin.
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ABSTRACT: Glioblastoma multiforme (GBM) is the most common and deadliest form of primary brain cancer in adults. Despite advances in molecular biology and genetics of gliomas currently there is no effective treatment or promising molecularly targeted experimental therapeutic strategies for these tumors. In previous studies we have shown aberrant overexpression of the class III beta-tubulin isotype (betaIII-tubulin) in GBM and have proposed that this change may reflect perturbations in microtubule dynamics associated with glioma tumorigenesis, tumor progression and malignant transformation into GBM. This minireview focuses on microtubules and tubulin as emerging targets in potential therapy of GBM using a new class of betaIII-tubulin-targeted drugs in the light of recent developments concerning the function and potential role of this isotype in clinically aggressive tumor behavior, cancer stem cells, tumor hypoxia and chemoresistance to tubulin binding agents, principally taxanes.Journal of Cellular Physiology 08/2009; 221(3):505-13. · 3.87 Impact Factor -
Article: Class III beta-tubulin is constitutively coexpressed with glial fibrillary acidic protein and nestin in midgestational human fetal astrocytes: implications for phenotypic identity.
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ABSTRACT: Class III beta-tubulin isotype (betaIII-tubulin) is widely regarded as a neuronal marker in developmental neurobiology and stem cell research. To test the specificity of this marker protein, we determined its expression and distribution in primary cultures of glial fibrillary acidic protein (GFAP)-expressing astrocytes isolated from the cerebral hemispheres of 2 human fetuses at 18 to 20 weeks of gestation. Cells were maintained as monolayer cultures for 1 to 21 days without differentiation induction. By immunofluorescence microscopy, coexpression of betaIII-tubulin and GFAP was detected in cells at all time points but in spatially distinct patterns. The numbers of GFAP+ cells gradually decreased from Days 1 to 21 in vitro, whereas betaIII-tubulin immunoreactivity was present in 100% of cells at all time points. beta-III-tubulin mRNA and protein expression were demonstrated in cultured cells by reverse-transcriptase-polymerase chain reaction and immunoblotting, respectively. Glial fibrillary acidic protein+/beta-III-tubulin-positive cells coexpressed nestin and vimentin but lacked neurofilament proteins, CD133, and glutamate-aspartate transporter. Weak cytoplasmic staining was detected with antibodies against microtubule-associated protein 2 isoforms. Confocal microscopy, performed on autopsy brain samples of human fetuses at 16 to 20 gestational weeks, revealed widespread colocalization of GFAP and betaIII-tubulin in cells of the ventricular/subventricular zones and the cortical plate. Our results indicate that in the midgestational human brain, betaIII-tubulin is not neuron specific because it is constitutively expressed in GFAP+/nestin+ presumptive fetal astrocytes.Journal of Neuropathology and Experimental Neurology 05/2008; 67(4):341-54. · 4.26 Impact Factor -
Article: IL-15 treatment during acute simian immunodeficiency virus (SIV) infection increases viral set point and accelerates disease progression despite the induction of stronger SIV-specific CD8+ T cell responses.
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ABSTRACT: In this study, we examined the effect of in vivo treatment of acutely SIV-infected Mamu-A*01+ rhesus macaques with IL-15. IL-15 treatment during acute infection increased viral set point by 3 logs and accelerated the development of simian AIDS in two of six animals with one developing early minimal lesion SIV meningoencephalitis. Although IL-15 induced a 2- to 3-fold increase in SIV-specific CD8+ T cell and NK cell numbers at peak viremia and reduced lymph node (LN) SIV-infected cells, this had no impact on peak viremia and did not lower viral set point. At viral set point, however, activated SIV-specific CD8+ T cells and NK cells were reduced in the blood of IL-15-treated animals and LN SIV-infected cells were increased. Week 30 LN from IL-15-treated animals had significantly increased Gag-specific CD8+ T cell numbers, whereas total cell, lymphocyte, and CD4+ T cell numbers were reduced. IL-15 treatment significantly reduced anti-SIV Ab concentrations at week 3 and viral set point. IL-15 increased Ki-67+CD4+ T cells at week 1 of treatment and reduced blood CCR5+ and CD45RA-CD62L- CD4+ T cells. The frequency of day 7 Ki-67+CD4+ T cells strongly correlated with viral set point. These findings suggest that CD4+ T cell activation during acute infection determines subsequent viral set point and IL-15 treatment by increasing such activation elevates viral set point. Finally, IL-15-treated acutely SIV-infected primates may serve as a useful model to investigate the poorly understood mechanisms that control viral set point and disease progression in HIV infection.The Journal of Immunology 02/2008; 180(1):350-60. · 5.79 Impact Factor -
Article: Class III beta-tubulin and gamma-tubulin are co-expressed and form complexes in human glioblastoma cells.
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ABSTRACT: We have previously shown that the neuronal-associated class III beta-tubulin isotype and the centrosome-associated gamma-tubulin are aberrantly expressed in astrocytic gliomas (Cell Motil Cytoskeleton 2003, 55:77-96; J Neuropathol Exp Neurol 2006, 65:455-467). Here we determined the expression, distribution and interaction of betaIII-tubulin and gamma-tubulin in diffuse-type astrocytic gliomas (grades II-IV) (n = 17) and the human glioblastoma cell line T98G. By immunohistochemistry and immunofluorescence microscopy, betaIII-tubulin and gamma-tubulin were co-distributed in anaplastic astrocytomas and glioblastomas and to a lesser extent, in low-grade diffuse astrocytomas (P < 0.05). In T98G glioblastoma cells betaIII-tubulin was associated with microtubules whereas gamma-tubulin exhibited striking diffuse cytoplasmic staining in addition to its expectant centrosome-associated pericentriolar distribution. Treatment with different anti-microtubule drugs revealed that betaIII-tubulin was not associated with insoluble gamma-tubulin aggregates. On the other hand, immunoprecipitation experiments unveiled that both tubulins formed complexes in soluble cytoplasmic pools, where substantial amounts of these proteins were located. We suggest that aberrant expression and interactions of betaIII-tubulin and gamma-tubulin may be linked to malignant changes in glial cells.Neurochemical Research 08/2007; 32(8):1387-98. · 2.24 Impact Factor -
Article: [Neuroprotection in perinatal hypoxic-ischemic encephalopathy. Effective treatment and future perspectives].
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ABSTRACT: The aim of this paper is to review the results of recent clinical studies of some therapies that have demonstrated a neuroprotective effect in perinatal hypoxic-ischemic encephalopathy (HIE) and to present the future perspectives of other clinical and basic research investigations. THERAPIES WITH DEMONSTRATED CLINICAL EFFICACY: ALLOPURINOL: It blocks the production of free radicals following hypoxia-ischemia. In a recent study, infants with hypoplastic left heart syndrome treated with allopurinol, but not those with other congenital cardiopathies, had significantly less number of complications than controls, including death, seizures, coma or cardiac events. OPIOIDS: In another recent study, newborns with HIE treated with morphine or phentanyl, had less severe brain damage on MRI and a better neurological outcome. HYPOTHERMIA: Both local (head cooling) or systemic (whole body) hypothermia have a neuroprotective effect in selected newborns with HIE. FUTURE PERSPECTIVES: ANTIEPILEPTIC DRUGS: They have multiple mechanisms of action that can block the biochemical cascade of neuronal damage in HIE. OTHER THERAPEUTIC MODALITIES: Among them the following should be emphasized: combined neuroprotective treatments, growth factors, genetic therapies, stem cell transplant, and neuroprotective immunization. In conclusion, a better knowledge of the molecular mechanisms of HIE pathogenesis and better clinical studies of neuroprotective therapies will open new possibilities aplicable to clinical practice. These advances will undoubtedly improve the prognosis of newborns with HIE.Medicina 02/2007; 67(6 Pt 1):543-55. · 0.47 Impact Factor -
Article: Class III β-tubulin and γ-tubulin are co-expressed and form complexes in human glioblastoma cells
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ABSTRACT: We have previously shown that the neuronal-associated class III b-tubulin isotype and the centrosome-associated c-tubulin are aberrantly expressed in astrocytic gliomas (Cell Motil Cytoskeleton 2003, 55:77-96; J Neuro-pathol Exp Neurol 2006, 65:455–467). Here we determined the expression, distribution and interaction of bIII-tubulin and c-tubulin in diffuse-type astrocytic gliomas (grades II-IV) (n = 17) and the human glioblastoma cell line T98G. By immunohistochemistry and immunofluorescence microscopy, bIII-tubulin and c-tubulin were co-distributed in anaplastic astrocytomas and glioblastomas and to a lesser extent, in low-grade diffuse astrocytomas (P < 0.05). In T98G glioblastoma cells bIII-tubulin was associated with microtubules whereas c-tubulin exhibited striking diffuse cytoplasmic staining in addition to its expectant centrosome-associated pericentriolar distribution. Treatment with different anti-microtubule drugs revealed that bIII-tubulin was not associated with insoluble c-tubulin aggregates. On the other hand, immunoprecipitation experiments unveiled that both tubulins formed complexes in soluble cytoplasmic pools, where substantial amounts of these proteins were located. We suggest that aberrant expression and interactions of bIII-tubulin and c-tubulin may be linked to malignant changes in glial cells. Keywords c-Tubulin Á Class III b-tubulin Á Centrosome amplification Á Astrocytoma Á Glioma Á Glioblastoma Abbreviations ANOVA Analysis of variance Cy3 Indocarbocyanate DAPI 4¢-6-Diamidino-2-phenylindole DMEM Dulbecco's modified Eagle medium EDTA Ethylene diamine tetraacetic acid EGTA Ethylene glycol tetraacetic acid FITC Fluorescein isothiocyanate GCP c-Tubulin complex protein c-TuRC Large c-tubulin-ring complex c-TuSC c-Tubulin-small complex LI Labeling index MES 2-(N-morpholine)-ethane sulphonic acid MLI Mean labeling index MSB Microtubule-stabilizing buffer MTOC Microtubule organizing center TBST Tris-Buffered Saline Tween-20 C.D. Katsetos and E. Dráberová contributed equally to this work.Neurochem Res. 01/2007; 32:1387-1398. -
Article: Anomalous inhibitory circuits in cortical tubers of human tuberous sclerosis complex associated with refractory epilepsy: aberrant expression of parvalbumin and calbindin-D28k in dysplastic cortex.
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ABSTRACT: Damage or loss of inhibitory cortical gamma-aminobutyric acid (GABA)ergic interneurons is associated with impaired inhibitory control of neocortical pyramidal cells, leading to hyperexcitability and epileptogenesis. The calcium binding proteins parvalbumin and calbindin-D(28k) are expressed in subpopulations of GABAergic local circuit neurons in the neocortex and can serve as neuronotypic markers. Parvalbumin and calbindin-D(28k) facilitate the neuron's ability to sustain firing and provide neuroprotection. The goal of this study was to assess the hitherto unknown status of inhibitory interneurons in cortical tubers of human tuberous sclerosis complex. Surgically excised cortical tubers from three patients with tuberous sclerosis complex were evaluated immunohistochemically with antibodies to parvalbumin and calbindin-D(28k). Cortical specimens from young patients with intractable seizures, including microdysgenesis (n = 3), postischemic cortical scarring (n = 1), porencephaly (n = 1), postictal gliosis (n = 3), and low-grade neuronal or glial tumors (n = 5), were also examined for comparison. In cortical tubers, calcium binding protein immunoreactivities (calbindin-D(28k) > parvalbumin) were present in medium- or large-size dysplastic neurons, whereas giant or ballooned cells were parvalbumin or calbindin-D(28k) negative. In microdysgenesis, a nearly normal number of parvalbumin-positive neurons and a decreased number of calbindin-D(28k)-positive neurons were present. In peritumoral but more so in gliotic cortex, a coordinate decrease of parvalbumin and calbindin-D(28k) immunoreactivities was present. Our findings indicate that the expression of parvalbumin or calbindin-D(28k) by subpopulations of dysplastic neurons in cortical tubers is aberrant and denotes dysfunctional inhibitory circuits inept for excitoprotection.Journal of Child Neurology 12/2006; 21(12):1058-63. · 1.75 Impact Factor
Top co-authors
Top Journals
Institutions
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2012
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Harokopion University of Athens
Athens, Attiki, Greece
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2003–2011
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Drexel University College of Medicine
- Department of Pediatrics
Philadelphia, PA, USA
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2008
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Academy of Sciences of the Czech Republic
- Oddělení biologie cytoskeletu
Praha, Hlavni mesto Praha, Czech Republic
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1999–2003
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The Children's Hospital of Philadelphia
Philadelphia, PA, USA
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2002
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Temple University
- College of Science and Technology
Philadelphia, PA, USA
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1998
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Philadelphia University
Philadelphia, PA, USA
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