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Biomedical subjects

A Sala

Publications and source records attributed to A Sala.

At least 19 recordsLinked to original sources
PubMed2000

Direct transactivation of the anti-apoptotic gene apolipoprotein J (clusterin) by B-MYB.

B-MYB is a ubiquitously expressed transcription factor involved in the regulation of cell survival, proliferation, and differentiation. In an attempt to isolate B-MYB-regulated genes that may explain the role of B-MYB in cellular processes, representational difference analysis was performed in neuroblastoma cell lines with different levels of B-MYB expression. One of the genes, the mRNA levels of which were enhanced in B-MYB expressing cells, was ApoJ/Clusterin(SGP-2/TRMP-2) (ApoJ/Clusterin), previously implicated in regulation of apoptosis and tumor progression. Here we show that the human ApoJ/Clusterin gene contains a Myb binding site in its 5' flanking region, which interacts with bacterially synthesized B-MYB protein and mediates B-MYB-dependent transactivation of the ApoJ/Clusterin promoter in transient transfection assays. Endogenous ApoJ/Clusterin expression is induced in mammalian cell lines following transient transfection of a B-MYB cDNA. Blockage of secreted clusterin by a monoclonal antibody results in increased apoptosis of neuroblastoma cells exposed to the chemotherapeutic drug doxorubicin. Thus, activation of ApoJ/Clusterin by B-MYB may be an important step in the regulation of apoptosis in normal and diseased cells.

Animals↗
PubMed2000

Poly(ADP-ribose) polymerase is a B-MYB coactivator.

B-MYB is implicated in cell growth control, differentiation, and cancer and belongs to the MYB family of nuclear transcription factors. Evidence exists that cellular proteins bind directly to B-MYB, and it has been hypothesized that B-MYB transcriptional activity may be modulated by specific cofactors. In an attempt to isolate proteins that interact with the B-MYB DNA-binding domain, a modular domain that has the potential to mediate protein-protein interaction, we performed pull-down experiments with a glutathione S-transferase-B-MYB protein and mammalian protein extracts. We isolated a 110-kDa protein associated endogenously with B-MYB in the nuclei of HL60 cells. Microsequence analysis and immunoprecipitation experiments determined that the bound protein was poly(ADP-ribose) polymerase (PARP). Transient transfection assays showed that PARP enhanced B-MYB transactivation and that PARP enzymatic activity is not required for B-MYB-dependent transactivation. These results suggest that PARP, as a transcriptional cofactor of a potentially oncogenic protein, may play a role in growth control and cancer.

Animals↗
PubMed2000

Monoclonal anti-CD18 antibody prevents transcellular biosynthesis of cysteinyl leukotrienes in vitro and in vivo and protects against leukotriene-dependent increase in coronary vascular resistance and myocardial stiffness.

BACKGROUND: Cysteinyl leukotrienes (cys-LT) can constrict small and large vessels and increase vascular permeability. Formation of cys-LT arising from polymorphonuclear leukocytes (PMNL) and endothelial cell cooperation (transcellular synthesis) led to the hypothesis that PMNL-endothelial cell adhesion may represent a key step toward the formation of vasoactive cys-LT. METHODS AND RESULTS: We studied the effect of pretreatment with a monoclonal antibody directed against the CD18 subunit of PMNL beta(2)-integrin on the synthesis of cys-LT in a PMNL-perfused isolated rabbit heart in vitro and in a model of permanent ligature of the left descending coronary artery in the rabbit in vivo. Challenge of PMNL-perfused rabbit hearts with formyl-met-leu-phe (0.3 micromol/L) caused synthesis of cys-LT and increase in coronary perfusion pressure that were prevented by the anti-CD18 antibody. Similar results were obtained with the use of A-23187 (0.5 micromol/L) as a challenge. Persistence of PMNL-associated myeloperoxidase activity in the perfusion buffer was observed in the presence of the anti-CD18 antibody, indicating decreased PMNL infiltration. Coronary artery ligature in vivo increased urinary excretion of leukotriene E(4), supporting the activation of the 5-lipoxygenase pathway during experimental acute myocardial infarction. Pretreatment with the anti-CD18 antibody (1 mg/kg) prevented the increase in leukotriene E(4) excretion. CONCLUSIONS: These data support the importance of adhesion in promoting cys-LT formation, originating from PMNL-endothelial cell cooperation, and contributing to myocardial stiffness and increased coronary resistance.

Animals↗
PubMed2000

Physical interaction between CDK9 and B-Myb results in suppression of B-Myb gene autoregulation.

B-Myb is a transcription factor belonging to the myb family, whose activity has been associated with augmented DNA synthesis and cell cycle progression. We showed recently that B-Myb autoregulates its own expression through promoter transactivation. We report in this study that CDK9, the cyclin T associated kinase, which phosphorylates and activates RNA-Polymerase II, suppresses B-Myb autoregulation through direct interaction with the carboxyl-terminus of the B-Myb protein. Down-regulation of the transactivating ability of B-Myb is independent of the kinase activity of CDK9, because a kinase deficient mutant (dn-CDK9) also represses B-myb gene autoregulation. Overexpression of CDK9 did not result in suppression of p53-dependent transactivation or inhibition of the basal activity of the promoters tested so far, demonstrating that CDK9 is a B-Myb-specific repressor. Rather, transfection of the dominant negative dn-CDK9 construct inhibited the basal activity of the reporter genes, confirming an essential role for CDK9 in gene transcription. In addition, Cyclin T1 restores B-Myb transactivating activity when co-transfected along with CDK9, suggesting that the down-regulatory effect observed on B-Myb is specifically due to CDK9 alone. Thus, our data suggest that CDK9 is involved in the negative regulation of activated transcription mediated by certain transcription factors, such as B-Myb. This may indicate the existence of a feedback loop, mediated by the different activities of CDK9, which links basal with activated transcription.

Cell Cycle Proteins↗
PubMed2000

Anti-phospholipase A2 and anti-inflammatory activity of Santolina chamaecyparissus.

The activity of the Santolina chamaecyparissus methanol extract was tested against the phospholipase A2 (PLA2)-induced mouse paw edema and in vitro inhibition of PLA2 activity. After fractionation, only the dichloromethane extract was active against the PLA2 in vitro test. In addition, it reduced the edema induced by arachidonic acid, and by 12-O-tetradecanoylphorbol-13-acetate in a multidose test. After chromatography on silicagel and gel filtration on Sephadex, and using an in vitro anti-PLA2 assay-guided process, we have isolated and identified from the dichloromethane extract the flavone nepetin and four sesquiterpenes.

Animals↗
PubMed2000

15-Lipoxygenase expression and 15(S)-hydroxyeicoisatetraenoic acid release and reincorporation in induced sputum of asthmatic subjects.

BACKGROUND: Recent evidence shows that 15(S)-hydroxy-eicoisatetraenoic acid (15[S]-HETE) can be released and rapidly reincorporated into cellular lipids. These mechanisms exert several immunoregulatory functions that may be relevant in airway inflammation. OBJECTIVE: Our purpose was to evaluate the levels of both soluble and cell-associated 15(S)-HETE and to examine 15-lipoxygenase (15-LO) messenger RNA (mRNA) expression in sputum samples obtained from 10 control and 18 asthmatic subjects. METHODS: Levels of 15(S)-HETE were measured by reverse-phase HPLC separation followed by RIA in supernatants and in cell membrane-extracted phospholipids after acid hydrolysis. 15-LO mRNA was evaluated by primed in situ hybridization (PRINS). Combined immunocytochemistry and PRINS was used to identify the phenotype of cells bearing 15-LO transcripts. RESULTS: Levels of both soluble and cell-associated 15(S)-HETE were higher in asthmatic than in control subjects (P <.0001). The percentage of cells expressing 15-LO mRNA was higher in asthmatic than in control subjects (P <.01). On double staining for specific cell-type markers and 15-LO mRNA, macrophages were the major source for 15-LO. CONCLUSION: This study shows that the induced sputum technique allows the evaluation of 15-LO activity and that soluble, cell-associated 15(S)-HETE and 15-LO levels are higher in asthmatic than in control subjects. In addition, this study indicates that, in induced sputum, airway macrophages are the major source of 15(S)-HETE in asthma.

Adult↗
PubMed1999

Differential metabolism of exogenous and endogenous arachidonic acid in human neutrophils.

Leukotrienes can be produced by cooperative interactions between cells in which, for example, arachidonate derived from one cell is oxidized to leukotriene A(4) (LTA(4)) by another and this can then be exported for conversion to LTB(4) or cysteinyl leukotrienes (cys-LTs) by yet another. Neutrophils do not contain LTC(4) synthase but are known to cooperate with endothelial cells or platelets (which do have this enzyme) to generate cys-LTs. Stimulation of human neutrophils perfusing isolated rabbit hearts resulted in production of cys-LTs, whereas these were not seen with perfused hearts alone or isolated neutrophils. In addition, the stimulated, neutrophil-perfused hearts generated much greater amounts of total LTA(4) products, suggesting that the hearts were supplying arachidonate to the neutrophils and, in addition, that this externally derived arachidonate was preferentially used for exported LTA(4) that could be metabolized to cys-LTs by the coronary endothelium. Stable isotope-labeled arachidonate and electrospray tandem mass spectrometry were used to differentially follow metabolism of exogenous and endogenous arachidonate. Isolated, adherent neutrophils at low concentrations (to minimize transcellular metabolism between them) were shown to generate higher proportions of nonenzymatic LTA(4) products from exogenous arachidonate (deuterium-labeled) than from endogenous (unlabeled) sources. The endogenous arachidonate, on the other hand, was preferentially used for conversion to LTB(4) by the LTA(4) hydrolase. This result was not because of saturation of the LTA(4) hydrolase, because it occurred at widely differing concentrations of exogenous arachidonate. Finally, in the presence of platelets (which contain LTC(4) synthase), the LTA(4) synthesized from exogenous deuterium-labeled arachidonate was converted to cys-LTs to a greater degree than that from endogenous sources. These experiments suggest that exogenous arachidonate is preferentially converted to LTA(4) for export (not intracellular conversion) and raises the likelihood that there are different intracellular pathways for arachidonate metabolism.

Animals↗
PubMed1999

B-MYB transactivates its own promoter through SP1-binding sites.

B-MYB is an ubiquitous protein required for mammalian cell growth. In this report we show that B-MYB transactivates its own promoter through a 120 bp segment proximal to the transcription start site. The B-MYB-responsive element does not contain myb-binding sites and gel-shift analysis shows that SP1, but not B-MYB, protein contained in SAOS2 cell extracts binds to the 120 bp B-myb promoter fragment. B-MYB-dependent transactivation is cooperatively increased in the presence of SP1, but not SP3 overexpression. When the SP1 elements of the B-myb promoter are transferred in front of a heterologous promoter, an increased response to B-MYB results. In contrast, c-MYB, the prototype member of the Myb family, is not able to activate the luciferase construct containing the SP1 elements. With the use of an SP1-GAL4 fusion protein, we have determined that the cooperative activation occurs through the domain A of SP1. These observations suggest that B-MYB functions as a coactivator of SP1, and that diverse combinations of myb and SP1 sites may dictate the responsiveness of myb-target genes to the various members of the myb family.

Adenovirus E1A Proteins↗
PubMed1999

B-Myb protein in cellular proliferation, transcription control, and cancer: latest developments.

Since its isolation exactly a decade ago, B-Myb has intrigued a growing number of scientists interested in understanding the mechanisms of cell proliferation. In many aspects the B-Myb story resembles that of a fashionable transcription factor involved in cell cycle control: E2F-1. Similar to E2F-1, B-Myb is a transcription factor whose expression is regulated at the G1/S border of the cell cycle. Given the ubiquitous expression of B-Myb within different cell types, its link with the cell cycle, and augmented expression in transformed cells, studies are in progress to define the potential role of B-Myb in human cancer. The purpose of this review is not to provide an extensive background to the B-Myb field but rather to describe the latest developments. A comprehensive outline of B-Myb structure and function can be found in the review by Saville and Watson (1998a, Adv. Cancer Res., 72:109-140).

Cell Cycle Proteins↗
PubMed1999

Reference database of hypervariable genetic markers of Argentina: application for molecular anthropology and forensic casework.

The population of Argentina is mostly composed of people of European ancestry. Aboriginal communities are at present very reduced in number and restricted to small geographically isolated patches. Three aboriginal communities, the Mapuche, Tehuelche and Wichi, were selected for short tandem repeat (STR) investigation. The metropolitan population of the city of Buenos Aires was analyzed, with both micro- and minisatellites. The minisatellite loci D1S7, D2S44, D4S139, D5S110, D8S358, D10S28, and D17S26 were typed on HaeIII-digested DNA obtained from unrelated individuals. D1S80 was typed by polymerase chain reaction (PCR). The autosomal STRs THO1, FABP, D6S366, CSF1PO, TPOX, F13A1, FES/FPS, vWA, MBPA/B, D16S539, D7S820, D13S317, and RENA4 and the sex chromosome STRs HPRTB, DYS385, DYS3891, DYS38911, DYS19, DYS390, DYS391, DYS392, DYS393 and YCAII were also investigated. As a by-product of our investigations, a reference database was created that is routinely used in forensic casework and paternity testing. STR allele frequency distributions are characterized by significant differences within and also between different populations. In contrast, the minisatellite bin distribution of the metropolitan population is not significantly different from other Caucasian populations.

Alleles↗
PubMed1999

Cyclooxygenase-2-dependent generation of 8-epiprostaglandin F2alpha by lipopolysaccharide-activated J774 macrophages.

OBJECTIVE: The generation of 8-epiprostaglandin F2alpha (8-epi-PGF2alpha) by arachidonic acid (AA)- and lipopolysaccharide (LPS)- stimulated J774 macrophages has been investigated. MATERIAL: Murine monocyte/macrophage J774 cell line. METHODS: Cells were incubated with AA or LPS and the amount of 8-epi-PGF2alpha, 6-ketoprostaglandin F1alpha (6-keto-PGF1alpha) and prostaglandin E2 (PGE2) released in the incubation media measured by radioimmunoassay (RIA) or, in some experiments, by enzyme immunoassay (EIA). The effect of dexamethasone (DXM), cycloheximide (CXM) and 5,5 dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanone (DFU), a cyclooxygenase-2 (COX-2) selective inhibitor, on LPS-induced generation of AA metabolites was assessed. RESULTS: AA induced a significant production of 6-ketoPGF1alpha and PGE2, whereas LPS caused a concentration- and time-dependent increase of 8-epi-PGF2alpha, 6-keto-PGF1alpha and PGE2. DXM (2 microM) as well as CXM (1 microM) significantly decreased (p<0.001; n = 4) the LPS-stimulated production of 8-epi-PGF2alpha (by 86% and 82%, respectively), 6-ketoPGF1alpha (by 78% and 74%, respectively) and PGE2 (by 83% and 78%, respectively). Immunostimulated production of AA metabolites was also inhibited by DFU (IC50 0.3+/-0.04 microM; 0.16 +/- 0.02 microM and 0.11 +/- 0.05 microM for 8-epi-PGF2alpha, 6-keto-PGF1alpha and PGE2, respectively. CONCLUSIONS: These results demonstrate the role of COX-2 in the generation of 8-epi-PGF2alpha by LPS-stimulated J774 macrophages. The relevance of these findings requires further elucidation.

6-Ketoprostaglandin F1 alpha↗
PubMed1999

IL-4 and IgE-anti-IgE modulation of 15(S)-hydroxyeicosatetraenoic acid release by mononuclear phagocytes.

BACKGROUND: IL-4 modulates the synthesis of IgE, the expression of CD23, and the release of 15(S)-hydroxyeicosatetraenoic (15[S]-HETE). OBJECTIVE: We evaluated the release of 15(S)-HETE by IL-4-stimulated monocytes and verified whether the observed increase in 15(S)-HETE release after passive sensitization and anti-IgE challenge of IL-4-treated monocytes was secondary to an increased CD23 expression. METHODS: Human monocytes were incubated for 24, 48, and 72 hours with IL-4 (10 ng/mL) with or without an IgE-anti-IgE stimulation. We evaluated CD23 expression by immunocytochemistry and 15(S)-HETE release by HPLC and RIA. To prove that the increase in 15(S)-HETE release was due to the effect of IL-4 on CD23, we performed experiments with an anti-CD23 blocking mAb. RESULTS: CD23 expression and 15(S)-HETE release were significantly increased by IL-4, reaching a peak after 72 hours (P <.02). After passive sensitization with human IgE and anti-IgE challenge, IL-4-stimulated monocytes released higher amounts of 15(S)-HETE than IL-4-unstimulated monocytes (P <.02). Pretreatment with the anti-human B-cell CD23 MHM6 mAb caused a dose-dependent inhibition of 15(S)-HETE release. CONCLUSIONS: This study shows that immunologic challenge of IL-4-treated, passively sensitized monocytes results in a CD23-dependent additional increase of 15(S)-HETE release, indicating the presence of a synergistic effect of IL-4 on CD23 expression and 15(S)-HETE production.

Antibodies, Anti-Idiotypic↗
PubMed1999

Pharmacokinetics of ITF 296 (Sinitrodil) a novel organic nitrate, in healthy volunteers.

ITF 296 is a new orally active nitrate acting selectively on large arterial vessels over a wide range of doses. In healthy volunteers it causes less reduction in vascular resistance and less venodilatation than classic nitrates. Its pharmacokinetic profile was evaluated after intravenous infusion and oral (solution and immediate-release tablet) administration in a randomised cross-over design on 11 healthy volunteers. The plasma levels of ITF 296 and its metabolite ITF 1124 were determined by a HPLC method. The drug is rapidly distributed (mean steady-state distribution volume 53+/-17 liters) and eliminated (half-life of about 25 minutes) both after intravenous and oral administration. The total clearance is 2. 31+/-0.46 l/min. The oral solution of ITF 296 is well absorbed (Cmax=0.057 microg/ml, tmax=30 min) but it undergoes a first-pass effect (F=25%). The tablet, developed only for Phase 1 clinical studies, is characterised by an immediate release (Cmax=0.057 microg/ml, tmax=30 min). The extent of its absolute and relative bioavailability is about 14% and 53% respectively.

Adolescent↗
PubMed1999

Successful treatment of intrathecal methotrexate overdose with folinic acid rescue: a case report.

A 7-y-old boy with acute lymphoblastic leukaemia (ALL) received 600 mg of i.v. methotrexate (MTX) over 2 h, followed by triple intrathecal therapy (TIT) with cytosine arabinoside 30 mg, methylprednisolone 10 mg and MTX 300 mg (instead of the prescribed 12 mg). Ninety minutes later the patient developed headache, loss of consciousness and generalized hypertonia. He was transferred to the Intensive Care Unit, intubated and treated with phenobarbital. Three hours after the TIT, the levogyrus form of folinic acid (equivalent to double doses of the racemic product) was started i.v. at a dose of 100 mg every 3 h for 24 h, and every 6 h in the following 24 h. Cerebrospinal fluid was examined and was found normal. The patient subsequently remained in normal neurological status. The favourable outcome in our case suggests that folinic acid rescue may be adequate to prevent sequelae in patients who undergo intrathecal MTX overdoses up to 300 mg.

Antidotes↗
PubMed1999

Interleukin-4 enhances 15-lipoxygenase activity and incorporation of 15(S)-HETE into cellular phospholipids in cultured pulmonary epithelial cells.

15(S)-Hydroxyeicosatetraenoic acid (15[S]-HETE) is a 15-lipoxygenase (15-LO) metabolite that may play an important role in different pulmonary diseases. 15-HETE is synthesized by different epithelial cells and may be subsequently incorporated into cellular phospholipids. We studied the role of interleukin-4 (IL-4) on 15-LO activity and on 15(S)-HETE incorporation into cellular phospholipids by WI-26 pulmonary epithelial cells. 15-LO activity was evaluated by measuring 15(S)-HETE production, through combined reverse-phase-high-pressure liquid chromatography (RP-HPLC) separation and specific radioimmunoassay (RIA), after incubation with arachidonic acid (AA). We also studied 15-LO messenger RNA (mRNA) expression, using primed in situ (PRINS) labeling. IL-4 (10 ng/ml) markedly increased the percentage of 15-LO mRNA-bearing cells as well as 15-LO activity after 24, 48, and 72 h, with a maximal response at 48 h. Uptake and incorporation into cellular phospholipid was studied with [3H]15(S)-HETE, which showed that IL-4 was able to increase significantly 15(S)-HETE incorporation into WI-26 cells, with a maximal effect observed at 72 h. Cellular-lipid-associated [3H]15(S)-HETE, evaluated with RP-HPLC after base-catalyzed hydrolysis, increased concomitantly with disappearance of the radiolabel from the supernatant. Class separation of cellular lipids with normal-phase HPLC (NP-HPLC) showed that IL-4 increased [3H]15(S)- HETE incorporation mainly in the phosphatidylinositol (PI) fraction. The ability of IL-4 to promote 15-LO activity and incorporation into cellular phospholipids of human lung epithelial cells may be important in airway inflammation and in modulation of the potential autocrine function of 15(S)-HETE.

Arachidonate 15-Lipoxygenase↗
PubMed1999

Ex vivo manipulation of hematopoietic stem cells for transplantation: the potential role of amifostine.

High-dose chemotherapy with autologous stem cell transplantation is an increasingly used procedure in oncohematologic diseases and represents a promising strategy in selected patients with solid tumors. In autologous stem cell transplantation, the risk of reinfusion of clonogenic tumor cells is a remarkable biologic obstacle that can be at least partly overcome by ex vivo graft purging to reduce residual tumor. Mafosfamide and 4-hydroxyperoxycyclophosphamide, active metabolites of cyclophosphamide, are the most widely used pharmacologic agents for ex vivo bone marrow purging. However, in addition to killing tumor cells, they are toxic to normal bone marrow as measured by reduced colony-forming unit granulocyte-macrophage (CFU-GM). Thus, the therapeutic index of these alkylating agents is narrow, and parameters for dose selection must include toxicity to normal bone marrow progenitor cells that can delay bone marrow engraftment and increase risk of infections, bleeding complications, hospitalization, and the need for a costly transplantation procedure. Amifostine (WR-2771, Ethyol; Alza Pharmaceuticals, Palo Alto, CA/US Bioscience, West Conshohocken, PA) selectively protects human CFU-GM progenitor cells from the cytotoxicities of active metabolites of cyclophosphamide without altering its cytotoxic effect on malignant cells. This has been demonstrated both in preclinical and clinical studies in patients with breast cancer, malignant lymphomas, and acute leukemia. Amifostine use during the ex vivo procedure significantly shortened the time to bone marrow engraftment with decreased incidence of infections and need for red blood cell transfusions.

Amifostine↗