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C Ibañez

Publications and source records attributed to C Ibañez.

9 recordsLinked to original sources
PubMed2001

Thermal stabilization of the catalytic domain of botulinum neurotoxin E by phosphorylation of a single tyrosine residue.

The catalytic domain of clostridial neurotoxins is a substrate of tyrosine-specific protein kinases. The functional role of tyrosine phosphorylation and also the number and location of its (their) phosphorylation site(s) are yet elusive. We have used the recombinant catalytic domain of botulinum neurotoxin E (BoNT E) to examine these issues. Bacterially expressed and purified BoNT E catalytic domain was fully active, and was phosphorylated in vitro by the tyrosine-specific kinase Src. Tyrosine phosphorylation of the catalytic domain increased the protein thermal stability without affecting its proteolytic activity. Covalent modification of the endopeptidase promoted a disorder-to-order transition, as evidenced by the 35% increment of the alpha-helical content, which resulted in a 4 degrees C increase of its denaturation temperature. Site-directed replacement of tyrosine at position 67 completely abolished phosphate incorporation by Src. Constitutively unphosphorylated endopeptidase mutants exhibited functional properties virtually identical to those displayed by the nonphosphorylated wild-type catalytic domain. These findings indicate the presence of a single phosphorylation site in the catalytic domain of clostridial neurotoxins, and that its covalent modification primarily modulates the protein thermostability.

Botulinum Toxins↗
PubMed2001

Multivariate methods for characterization and classification of espresso coffees from different botanical varieties and types of roast by foam, taste, and mouthfeel.

Three espresso coffee (EC) samples of different botanical varieties and types of roast were prepared in standard conditions using an experimental EC prototype: Arabica coffee, Robusta Natural blend, and Robusta Torrefacto blend (a special roast by adding sugar). The ECs were characterized with regard to the physical parameters, amount of total solids, total solids on filtrate, lipids, caffeine, trigonelline, and chlorogenic acids by HPLC, and sensory descriptive analysis related to foam appearance, taste, and mouthfeel. Principal component analysis (PCA) was applied to differentiate the EC samples. Arabica and Robusta samples were separated successfully by principal component 1 (55.3% of variance) including physicochemical and sensory parameters related to foam and taste of ECs. Torrefacto and Robusta Natural EC samples were separated by principal component 2 (20.7% of total variance) including mouthfeel and other attributes of color foam. Some interesting correlations among sensory and physicochemical variables were found. A very simple discriminate function was obtained by discriminate analysis allowing the classification of each EC sample into its respective group with a success rate of 100%.

Alkaloids↗
PubMed1997

Establishment of parameters for optimal transduction efficiency and antitumor effects with purified high-titer HSV-TK retroviral vector in established solid tumors.

Suicide gene therapy using the herpes simplex thymidine kinase gene and ganciclovir is an attractive strategy for solid tumors. Early animal studies involved intratumoral injection of retroviral producer cells or unprocessed supernatant to generate an antitumor effect. Xenotransplantation of producer cells proved effective in several models, but the crude supernatants from the same cells were of insufficient titer to produce antitumor effects. We have developed new non-murine producer lines that yield replication-defective retroviral vectors encoding thymidine kinase at high titer which are then further purified and processed, resulting in pharmaceutical grade retroviral vectors with titers of up to 10(8) cfu/ml. Purified, high-titer retroviral preparations were injected directly into solid tumors in two syngeneic mouse tumor models. Significant antitumor responses and some cures were observed following systemic ganciclovir therapy. Assays using monoclonal antibodies to measure thymidine kinase protein expression at the single cell level in vitro and in vivo were developed so that therapeutic transgene expression could be quantified. Intralesional delivery resulted in transduction of over 20% of tumor cells in a protocol designed to maximize transduction on the basis of separate analyses of route, dosage, and schedule of vector administration. A consensus strategy evolved in which the combined effects of increased titer and a longer duration of retroviral vector administration interact to maximize transduction efficiency. These results indicate that purified high-titer retroviral vectors have the potential to transfer effective quantities of therapeutic genes into solid tumors in human subjects and highlight some pharmacologic factors that could be valuable in the design of clinical gene therapy protocols.

Animals↗
PubMed1995

Activated charcoal increases digoxin elimination in patients.

Digoxin continues to be an important cause of drug toxicity. On the basis of a healthy volunteer study, activated charcoal has been proposed as a treatment for digoxin chronic intoxication. In order to evaluate the effect of activated charcoal on digoxin elimination in intoxicated patients during routine practice, we reviewed all Serum Digoxin Level Requests for adult in-patients from 1991 to 1993, with digoxin levels > 2.5 ng/ml. Of a total of 39 cases, 23 had been treated with activated charcoal while 16 had not. Digoxin elimination half-life during activated charcoal therapy was 36 h (S.D. 14 h; 95% C.I. 30-42 h) while in the non-treated group it was 68 h (S.D. 19 h, 95% C.I. 57-78). Calculated total body clearance of digoxin was 55 ml/min (S.D. 17 ml/min; 95% C.I. 45-64 ml/min) for the non-treated group versus 98 ml/min (S.D. 34 ml/min; 95% C.I. 83-113 ml/min) for the group receiving charcoal, representing an 78% increase in digoxin elimination.

Aged↗
PubMed1993

Investigation of an outbreak of Salmonella typhi in a public school in Madrid.

A typhoid fever outbreak affecting 54 school students occurred in a Public School of Móstoles, Madrid. The date of onset was 11 June 1991 and the last detected case was 8 July 1991. Salmonella typhi was cultured from blood and/or stool samples corresponding to 54 patients and one food-handler. There were no secondary cases detected. Epidemiological investigation suggested a salad or a custard as the common source. Patients and the food-handler were treated with ampicillin/amoxicillin for up to three weeks. There were seven relapses that were also treated with the same antibiotics with success. None were found to be excreting the organisms when tested after four months. All the Salmonella typhi isolated strains were phagetype 34, biotype Xylose +, Tetrationate Reductase + and harboured a similar 22 Mdal plasmid, they were also susceptible to the antibiotics tested.

Adolescent↗
PubMed1990

Action of adenosine and characterization of adenosine receptors in human placental vasculature.

1. Adenosine induced concentration-dependent relaxations in segments of human chorionic arteries and veins precontracted with 75 mM K+, which were attenuated by 1-methyl-3-isobutylxanthine (MIX). In the same conditions, L-phenylisopropyladenosine (L-PIA), N-ethylcarboxamideadenosine (NECA) and dibutyryl-cyclic AMP (Db-cAMP) also produced concentration-dependent vasodilations. 2. The order of potency with respect to EC50 was in arteries: NECA greater than or equal to L-PIA greater than Db-cAMP greater than or equal to adenosine, and in veins: L-PIA greater than or equal to NECA greater than adenosine greater than or equal to Db-cAMP. 3. In segments precontracted with 10(-6) M PGF2 alpha, adenosine, NECA and L-PIA induced similar relaxations, which were markedly larger than those found in K+ contracted segments. 4. Db-cAMP (15 min preincubation) inhibited more potently K+ (75 mM) contractions than adenosine. 5. Adenosine reduced Ca addition-induced contractions in depolarized segments exposed to Ca-free medium, as well as 45Ca uptake elicited by 75 mM K+. 6. It is concluded that there exists a similar population of adenosine A1 and A2 receptors in chorionic vessels, which mediate adenosine relaxation. This effect appears to be mainly produced by inhibition of Ca influx, but not by a cAMP-dependent mechanism.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Role of presynaptic purinoceptors and cyclic AMP on the noradrenaline release in cat cerebral arteries.

Field electrical stimulation (ES), K+ (50 mM) or ionophore X-537A (0.01 mM) induced tritium release from cat cerebral arteries preincubated with [3H]noradrenaline (NA). Adenosine and AMP (0.5 mM) did not modify tritium release caused by ionophore X-537A, but these agents and ATP (0.5 mM) significantly reduced that elicited by ES and K+; this reduction was antagonized by 1-methyl-3-isobutylxanthine (MIX; 0.05 mM). Inosine (0.5 mM) and the agonist of purinergic A2-receptors, 5'N-ethyl-carboxamide adenosine (NECA; 0.5 mM) had no effect, but the agonist of purinergic A2-receptors L-N6-phenylisopropyl adenosine (L-PIA; 0.1 mM) diminished tritium efflux caused by ES and K+. The adenosine inhibition of ES-induced radioactivity release was not affected by indomethacin (0.05 mM). MIX (0.05 mM) increased tritium release evoked by ES and K+. Agents that increase intracellular cyclic (c)AMP levels, such as dibutyryl cAMP (0.5 mM), the phosphodiesterase inhibitor Ro 20-1724 (0.1 mM), and the activators of adenylate cyclase, forskolin (0.005 mM) and NaF (2 mM) reduced tritium secretion elicited by ES and K+. However, the intracellular increase of cyclic GMP (cGMP) caused by 8-Br-cGMP did not affect this secretion. Dipyridamole (0.05 mM) and the adenosine deaminase inhibitor erythro-9-2-hydroxy-3 nonyl adenosine (EHNA; 0.1 mM) also produced inhibition of tritium secretion elicited by ES and K+. Dipyridamole reduced both the uptake of [3H]NA and [3H]adenosine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine↗
PubMed1985

Structure of phage phi 29 connector protein assembled in vivo.

The protein p10 that forms the connector of phage phi 29, has been produced in Escherichia coli harboring a plasmid that carried the gene coding for this protein. The connector protein is assembled in a 13.4-S oligomer that has an apparent molecular weight of 460,000, suggesting that it is a dodecamer. The purified oligomers have been studied by electron microscopy of the isolated particles as well as by image-processing techniques (Fourier and rotational filtering) of artificially induced two-dimensional aggregates. The results show that the purified p10 is assembled in a circular structure with a hole in its center and 12 morphological units in the periphery. Both the morphology and the dimensions of this p10 oligomer are very similar to those of the upper neck collar extracted from phi 29 viral particles. The results strongly suggest the close relationship between the p10 oligomers assembled in E. coli and the ones produced in phi 29 infected Bacillis subtilis.

Bacillus subtilis↗