PubMed Health⌕ Search

Biomedical subjects

A Viola

Publications and source records attributed to A Viola.

At least 19 recordsLinked to original sources
PubMed2001

Hepatitis C virus structural proteins reside in the endoplasmic reticulum as well as in the intermediate compartment/cis-Golgi complex region of stably transfected cells.

The intracellular localization of hepatitis C virus structural proteins was analyzed by confocal immunofluorescence microscopy, cell fractionation, and immunoelectron microscopy in stably transfected cells that do not overexpress the viral proteins. The results strongly suggest that at steady state the structural proteins reside not only in the endoplasmic reticulum but also in the intermediate compartment and cis-Golgi complex region. By analogy with other viral systems, this finding raises the possibility that the intermediate compartment and cis-Golgi complex play a role in the assembly and budding of hepatitis C virus.

Calcium-Binding Proteins↗
PubMed2001

Organization of plasma membrane functional rafts upon T cell activation.

Raft microdomains have been shown to play a key role in T cell activation. We found that in human T lymphocytes the formation of functional rafts at the plasma membrane was induced by T cell priming. In resting T cells from peripheral blood Lck and the raft glycosphingolipid GM1 resided in intracellular membranes. T cell activation induced synthesis of GM1 and effector cells showed very high levels of this lipid, which became predominantly plasma membrane associated. TCR triggering also induced targeting of the cytosolic Lck to the plasma membrane. Thus, effector cells acquire an improved signaling machinery by increasing the amount of rafts at the plasma membrane. The fact that, when compared with naive T cells, memory T cells showed higher GM1 levels suggests that raft lipid synthesis may be developmentally regulated and tune T cell responsiveness.

G(M1) Ganglioside↗
PubMed2001

[Applications of magnetic resonance spectrometry (MRS) in the study of metabolic disturbances affecting the brain in alcoholism].

The purpose of this article is to provide an overview of the current applications of magnetic resonance spectroscopy (MRS) to the investigation of cerebral metabolism in alcoholic patients. The specific metabolic changes associated with the intoxication process (tolerance, dependance), abstinence and alcohol-related diseases (alcoholic encephalopathy, cirrhosis, Gayet-Wernicke's encephalopathy, Marchiafava-Bignami syndrome) are described.

Alcohol-Induced Disorders, Nervous System↗
PubMed2001

The amplification of TCR signaling by dynamic membrane microdomains.

Modulation of T-cell receptor (TCR) signaling is essential for the regulation of T-cell responses to infectious agents. Recently, many laboratories have suggested that TCR triggering might be compartmentalized in plasma membrane microdomains called rafts. Results on the role of lipid rafts as signaling units in TCR triggering suggest that rafts might be used by T cells to fine-tune their immune responsiveness.

Animals↗
PubMed2001

High-dose idarubicin and busulphan as conditioning for autologous stem cell transplantation in acute myeloid leukemia: a feasibility study.

INTRODUCTION: Between 30 and 50% of patients with acute myeloid leukemia still relapse after autologous stem cell transplantation. We investigated the feasibility of a new conditioning regimen consisting of high dose IDA plus oral busulphan in patients undergoing autologous transplantation. MATERIALS AND METHODS: Patients (n = 13) were given three days continuous infusion IDA, followed by four days conventional dose oral busulphan as conditioning. Peripheral blood stem cells were used in all cases. Eleven patients were in CR1. Patients with t(8;21) and inv(16) as well as those with acute promyelocytic leukemia were excluded from the study. The median of CD34+ cells infused was 6.2 x 10(6)/l (2.6-16.1). RESULTS: No case of transplant-related mortality occurred. The median number of days to neutrophil (>0.5 x 10(9)/l) and platelet (>20 x 10(9)/l) recovery was 10 (7-21) and 20 (9-26), respectively. Patients needed a median of 3 platelet units (1-6) and 3 blood units (0-12), respectively. Left ventricular ejection fraction remained unmodified after ASCT. Twelve out of 13 patients (92%) had variable grade of mucositis (two grade 2, five grade 3 and five grade 4). Total parenteral nutrition was needed in nine patients (69%). After a median follow-up of 14 months from ASCT, 11 patients out of 13 (85%) are alive in continuous CR; the other two patients experienced relapse at 12 and 14 months. CONCLUSION: Our data demonstrate the feasibility of a conditioning regimen based on high-dose IDA plus Busulphan in AML. Results concerning antileukemic efficacy are promising, but need confirmation on larger series with longer follow-up.

Acute Disease↗
PubMed2000

Metabolic effects of photodynamically induced apoptosis in an erythroleukemic cell line. A (31)P NMR spectroscopic study of Victoria-Blue-BO-sensitized TF-1 cells.

Victoria Blue BO (VB BO) is a new and promising photosensitizer currently being evaluated for photodynamic therapy (PDT). Its photochemical processes are mediated by oxygen radicals, but do not involve singlet oxygen. We used (31)P NMR spectroscopy of VB-BO sensitized TF-1 leukemic cells to gain further insight into the biochemical mechanisms underlying PDT-induced cell death. Sham-treatment experiments were performed to evaluate the effects of this photosensitizer in the absence of light irradiation. Significant metabolic differences were detected for TF-1 cells incubated with VB BO but not exposed to light, as compared with native cells (controls). These changes include reductions in phosphocreatine, UDP-hexose and phosphodiester levels (as percentage of total phosphate) and slightly reduced intracellular pH. Complete phosphocreatine depletion, significant acidification and concomitant inorganic-phosphate accumulation were observed for TF-1 cells irradiated after incubation with VB BO. Moreover, significant changes in phospholipid metabolites, i.e., accumulation of cytidine 5'-diphosphate choline and a decrease in phosphodiester levels, were observed for PDT-treated vs. sham-treated cells. Perturbations of phospholipid metabolism may be involved in programmed cell death, and the detection of a characteristic DNA ladder pattern by gel electrophoresis confirmed the existence of apoptosis in PDT-treated TF-1 cells.

Apoptosis↗
PubMed2000

Genomic localization of the human genes TAF1A, TAF1B and TAF1C, encoding TAF(I)48, TAF(I)63 and TAF(I)110 subunits of class I general transcription initiation factor SL1.

Human SL1 is a general transcription initiation factor (GTF) essential for RNA polymerase I to start rRNA synthesis at class I promoters. It is comprised of the TATA box-binding protein (TBP) and three TBP-associated factors (TAF(I)48, TAF(I)63 and TAF(I)110). We have determined that the human genes TAF1A, TAF1B and TAF1C, encoding these three TAF(I) polypeptides, are localized at lq42, 2p25 and 16q24, respectively. All three genes are present as single copies in the human genome and map to different chromosomes, as shown by somatic cell hybrid panel and radiation hybrid panel analysis and FISH. Two of these genes, TAF1C and TAF1B, are transcribed into multiple RNAs, as determined through Northern analysis of mRNA from various human organs and cell lines. If translated into different polypeptides, this could result in production of variant isoforms of SL1 with different activation potentials.

Alleles↗
PubMed2000

[Morphologic and clinical sequelae of focal ischemic lesions].

The diseases of vessels, mainly of those in brain are one of the most serious problems of the medical practice. The encephalomalacia or cerebral infarctions are usually caused by transient or permanent obstruction of the brain arteries lumen. Beside local dysfunction of vessels the obstructions could be based on embolic events originating in the heart. Such an obstructions are resulting in global and focal cerebral ischaemias. Arterial occlusion results in cerebral ischaemia and the lack of oxygen (anoxia) which leads to reversible or irreversible injury of the nervous cells in the ischaemic region. The local cell injury or cell death causes attraction of macrophages invading into the devitalized tissue within 72-96 hours after the beginning of the ischaemia. The aim of this study was to find out the correlation between asymptomatic or symptomatic course regarding localisation of the ischaemic lesions in the cerebral tissue. Our anatomical findings were collected from 318 autopsies, and reports on postmortem examinations during the period between September-December 1998. The grossing of the brain was carried out by using of Virchow's method. Atherosclerosis, hypertension, and diabetes mellitus were found to be the main risk factors for the production of focal cerebral ischaemia. Of those patients with focal cerebral ischaemia atherosclerosis had 87.5%, 44.3% were suffering from hypertension, and 25% from diabetes mellitus. The focal ischaemia analysed in this study originated from arterial stenosis or thromboembolic obstructions. We divided the lesions into 3 groups according to their size. The most frequently apparent lesions (72%) were the small cysts (0-10 mm in diameter)-lacunae. The majority of them (90%) was found in the basal ganglia. The second group consisted of postmalatic pseudocysts (10-30 mm in diameter), and the third group was represented by encephalomalatic lesions which were larger than 30 mm. Cerebral ischaemic lesions were present in 27.8% of the studied cases. Nevertheless, more than the half (56.8%) of the affected brains (postmalatic pseudocysts, lacunae and malaciae) belongs to the group of patients who were clinically asymptomatic. The asymptomatic lesions, having negative results in the patient's history, and the clinical course were localised mainly in the basal ganglia of both sides and in the frontal part of the right (nondominant) hemisphere.

Adult↗
PubMed1999

Developmental regulation of Lck targeting to the CD8 coreceptor controls signaling in naive and memory T cells.

The question of whether enhanced memory T cell responses are simply due to an increased frequency of specific cells or also to an improved response at the single cell level is widely debated. In this study, we analyzed T cell receptor (TCR) transgenic memory T cells and bona fide memory T cells isolated from virally infected normal mice using the tetramer technology. We found that memory T cells are qualitatively different from naive T cells due to a developmentally regulated rearrangement of the topology of the signaling machinery. In naive cytotoxic T cells, only a few CD8 molecules are associated with Lck and the kinase is homogeneously distributed inside the cell. However, in vivo priming of naive T cells induces the targeting of Lck to the CD8 coreceptor in the cell membrane and the consequent organization of a more efficient TCR signaling machinery in effector and memory cells.

Acetyltransferases↗
PubMed1999

T lymphocyte costimulation mediated by reorganization of membrane microdomains.

Although dispensable, costimulation through CD28 facilitates activation of naïve T lymphocytes. CD28 engagement led to the redistribution and clustering of membrane and intracellular kinase-rich raft microdomains at the site of T cell receptor (TCR) engagements. Although not affecting TCR down-regulation, this process led to higher and more stable tyrosine phosphorylation of several substrates and higher consumption of Lck. These results may provide a general mechanism for amplifying receptor signaling by reorganization of membrane microdomains.

Antigen-Presenting Cells↗
PubMed1999

Distinct kinetics of cytokine production and cytolysis in effector and memory T cells after viral infection.

In the present study, naive T cells were compared with in vivo generated effector and memory T cells expressing the same TCR specific for lymphocytic choriomeningitis virus. Upon restimulation in vitro, the same minimal concentrations of the full agonist peptide p33 and also of weak and partial agonist peptides were required for proliferation of naive, effector and memory T cells, indicating no difference in threshold of activation. However, activation kinetics were distinct. While effector cytotoxic T cells exhibited immediate ex vivo lytic effector function, naive and memory T cells required 12 h and more exposure to antigen to develop lytic activity. However, both effector and memory T cells contained IFN-gamma mRNA in vivo and required less than 3 h for secretion of cytokines upon restimulation in vitro. In contrast, naive T cells did not contain IFN-gamma mRNA and required more than 12 h for cytokine secretion. Our results show that memory T cells exhibit a unique phenotype in that they produce cytokines and commit to proliferation as rapidly as effector cells, whereas they resemble naive T cells in the time requirement for development of cytolytic function.

Animals↗
PubMed1999

Complete remission in acute myeloid leukaemia with t(8;21) following treatment with G-CSF: flow cytometric analysis of in vivo and in vitro effects on cell maturation.

A 75-year-old patient diagnosed as having acute myeloid leukaemia with t(8;21) received G-CSF alone as induction therapy. Complete remission was achieved following 2 weeks of treatment. Flow cytometric analysis, performed by CD45 technique modified by the introduction of preliminary gating with LDS-751, confirmed the disappearance of blast cells along with myeloid maturation. Finally, in vitro studies demonstrated that G-CSF, as compared to other differentiation inducers, was able to induce a striking effect toward neutrophilic differentiation.

Acute Disease↗
PubMed1999

T-cell activation and the dynamic world of rafts.

Recent evidence, indicates that T-cell receptor (TCR) triggering and T-cell activation are dynamic processes that involve various aspects of T-cell organization. In addition to the interaction between the TCR molecule and its ligand, T-cell activation depends on a combination of many other events involving coreceptor molecules, actin cytoskeleton and plasma membrane lipids. Altogether, these cell structures organize the formation of a specialized junction between the T cell and the antigen-presenting cell (APC), that plays a critical role in sustaining and amplifying TCR signalling.

Animals↗
PubMed1999

Hb Rainier [beta145(HC2)Tyr-->Cys] in Italy. Characterization of the amino acid substitution and the DNA mutation.

A high oxygen affinity hemoglobin variant was identified in a 53-year-old male patient from Napoli (Italy), suffering from pulmonary thromboembolism and polycythemia. A detailed structural characterization of the variant hemoglobin was carried out, both at the protein and DNA levels, by a combination of DNA sequencing and allele-specific amplification techniques with mass spectrometric procedures. The amino acid substitution was found to be Tyr-->Cys, and the corresponding DNA mutation was identified as A-->G at the second position of codon 145 of the beta chain. These variations indicated the presence of Hb Rainier. Haplotype analysis of DNA polymorphisms showed that the beta-globin gene from Hb Rainier was associated with haplotype II. Moreover, structural analyses provided direct identification of an intramolecular disulphide bridge joining the newly inserted beta145Cys with beta93Cys. This is the first report of the occurrence of Hb Rainier in Italy.

Adolescent↗
PubMed1998

Genomics and transcription analysis of human TFIID.

TFIID, a multisubunit protein comprised of TBP (TATA box-binding protein) and TAF(II)s (TBP-associated factors), has a central role in transcription initiation at class II promoters. TAF(II)s role as mediators of regulatory transcription factors, such as pRb and p53, and their involvement in signal transduction pathways suggest that some may participate in the control of cell proliferation and differentiation: therefore, they could be considered potential protooncogenes or antioncogenes. With the aim of starting to analyse these potential roles, we have determined the genomic position of nine human TAF(II) genes (TAF[II]250, TAF[II]135, TAF[II]100, TAF[II]80, TAF[II]55, TAF[II]43, TAF[II]31, TAF[II]28, TAF[II]20/15) and of two previously unknown sequences related to TAF(II)250 and TAF(II)31, respectively. Except for those encoding TAF(II)250 and TAF(II)31, these genes are present in a single copy and, with the exclusion of those for TAF(II)43 and TAF(II)28 (both at 6p21), are localized in different segments of the genome. Indeed, six of them map to a chromosomal region commonly altered in specific neoplasias, which defines them as candidates for involvement in oncogenesis. Our experiments also demonstrate that TAF(II) transcripts are synthesized ubiquitously, mostly at low levels similar to those of TBP. Interestingly, the amount of the major mRNA species detected by TAF(II)20/15 cDNA is higher, which suggests that the polypeptide it encodes may also perform functions independently of TFIID. TAF(II) isoforms, indicated by additional bands on Northern blots, may play a role in modulation of TFIID function. These data will be useful for analysing variations of TAF(II) mRNA phenotype during cell proliferation, differentiation and development, both normal and pathological.

Animals↗
PubMed1998

ESR studies of a series of phthalocyanines. Mechanism of phototoxicity. Comparative quantitation of O2-. using ESR spin-trapping and cytochrome c reduction techniques.

ESR experiments with 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP) and the spin-trap 5,5-dimethyl pyrroline-N-oxide (DMPO) have been performed on a series of new phthalocyanines: the bis(tri-n-hexylsiloxy) silicon phthalocyanine ([(nhex)3SiO]2SiPc), the hexadecachloro zinc phthalocyanine (ZnPcCl16), the hexadecachloro aluminum phthalocyanine (AlPcCl16), the hexadecachloro aluminum phthalocyanine sulfate (HSO4AlPcCl16), whose photocytotoxicity has been studied against various leukemic and melanotic cell lines. Type I and Type II pathways occur simultaneously in DMF although the Type II seems to be prevalent. These results are not changed when the bis(tri-n-hexylsiloxy) silicon phthalocyanine is entrapped into liposomes. By contrast, the Type I process is favored in membrane models for all the perchlorinated phthalocyanines. This modified behavior may be accounted on a possible stacking of phthalocyanines in membranes and a preventing effect of axial ligands against aggregation in the case of the bis(tri-n-hexylsiloxy) silicon phthalocyanine. The photodynamic action of zinc perchlorinated phthalocyanine is not dependent on singlet oxygen, phototoxicity of this molecule being essentially mediated by oxygen free radicals. Quantitation of the superoxide radical was accomplished, with good agreement, by two techniques: the cytochrome c reduction and the ESR quantitation based on the double integration of the first derivative of the ESR signal. The disproportionation of the superoxide radical or degradation of the spin-trap seem to be avoided in aprotic solvents such as DMF.

Cyclic N-Oxides↗