PubMed Health⌕ Search

Biomedical subjects

F Maldonado

Publications and source records attributed to F Maldonado.

11 recordsLinked to original sources
PubMed2005

Conservation of amino acids in human rhinovirus 3C protease correlates with broad-spectrum antiviral activity of rupintrivir, a novel human rhinovirus 3C protease inhibitor.

The picornavirus 3C protease is required for the majority of proteolytic cleavages that occur during the viral life cycle. Comparisons of published amino acid sequences from 6 human rhinoviruses (HRV) and 20 human enteroviruses (HEV) show considerable variability in the 3C protease-coding region but strict conservation of the catalytic triad residues. Rupintrivir (formerly AG7088) is an irreversible inhibitor of HRV 3C protease with potent in vitro activity against all HRV serotypes (48 of 48), HEV strains (4 of 4), and untyped HRV field isolates (46 of 46) tested. To better understand the relationship between in vitro antiviral activity and 3C protease-rupintrivir binding interactions, we performed nucleotide sequence analyses on an additional 21 HRV serotypes and 11 HRV clinical isolates. Antiviral activity was also determined for 23 HRV clinical isolates and four additional HEV strains. Sequence comparison of 3C proteases (n = 58) show that 13 and 11 of the 14 amino acids that are involved in side chain interactions with rupintrivir are strictly conserved among HRV and HEV, respectively. These sequence analyses are consistent with the comparable in vitro antiviral potencies of rupintrivir against all HRV serotypes, HRV isolates, and HEV strains tested (50% effective concentration range, 3 to 183 nM; n = 125). In summary, the conservation of critical amino acid residues in 3C protease and the observation of potent, broad-spectrum antipicornavirus activity of rupintrivir highlight the advantages of 3C protease as an antiviral target.

3C Viral Proteases↗
PubMed1999

In vitro antiviral activity of AG7088, a potent inhibitor of human rhinovirus 3C protease.

AG7088 is a potent, irreversible inhibitor of human rhinovirus (HRV) 3C protease (inactivation rate constant (k(obs)/[I]) = 1,470,000 +/- 440,000 M(-1) s(-1) for HRV 14) that was discovered by protein structure-based drug design methodologies. In H1-HeLa and MRC-5 cell protection assays, AG7088 inhibited the replication of all HRV serotypes (48 of 48) tested with a mean 50% effective concentration (EC(50)) of 0.023 microM (range, 0.003 to 0.081 microM) and a mean EC(90) of 0.082 microM (range, 0.018 to 0.261 microM) as well as that of related picornaviruses including coxsackieviruses A21 and B3, enterovirus 70, and echovirus 11. No significant reductions in the antiviral activity of AG7088 were observed when assays were performed in the presence of alpha(1)-acid glycoprotein or mucin, proteins present in nasal secretions. The 50% cytotoxic concentration of AG7088 was >1,000 microM, yielding a therapeutic index of >12,346 to >333,333. In a single-cycle, time-of-addition assay, AG7088 demonstrated antiviral activity when added up to 6 h after infection. In contrast, a compound targeting viral attachment and/or uncoating was effective only when added at the initiation of virus infection. Direct inhibition of 3C proteolytic activity in infected cells treated with AG7088 was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of radiolabeled proteins, which showed a dose-dependent accumulation of viral precursor polyproteins and reduction of processed protein products. The broad spectrum of antiviral activity of AG7088, combined with its efficacy even when added late in the virus life cycle, highlights the advantages of 3C protease as a target and suggests that AG7088 will be a promising clinical candidate.

3C Viral Proteases↗
PubMed1996

In vivo calcineurin crystals formed using the baculovirus expression system.

Calcineurin is a heterodimeric phosphatase involved in the signal transduction of antigen-activated T cells. Coexpression of its two subunits, the regulatory subunit from human and the catalytic subunit from Neurospora crassa in cultured insect cells using the baculovirus expression system results in the formation of very large crystals in the cytoplasm. The crystals are formed initially in vesicles, but their subsequent growth appears to be uninhibited and continues without the need of an enclosing membrane until the host cell lyses. Although these in vivo crystals are low in population, ranging only 0-3 per cell, they are extremely large, over 10 mu m in some cases. Biochemical assays confirm their calcineurin origin, with the regulatory subunit incorporated being myristoylated, although both the myristoylated and unmyristoylated forms are expressed. The lattice structure of the in vivo crystals, with a spacing of 5.5 nm, is preserved with the regular electron microscopic (EM) specimen preparation procedure.

Animals↗
PubMed1994

Adhesion strength of human ligament fibroblasts.

The adhesive interactions of cells with other cells and the extracellular matrix (ECM) play a fundamental role in the organization of cells in differentiated organs, cell motility, and the healing process. The adhesion characteristics of ligament fibroblasts depend on the expression of cell surface molecules and their interaction with the ECM. Although many receptors mediating the effects of ECM components on ligament cell function remain poorly defined, it is known that fibronectin (FN) allows ligament cells to adhere through the VLA-5 receptor (alpha 5 beta 1). A direct measurement of the adhesion between anterior cruciate ligament (ACL) or medial collateral ligament (MCL) fibroblasts and fibronectin matrix proteins was achieved by using a micromanipulation technique to determine the force required to detach an ACL or MCL cell from fibronectin-coated glass. We have found that the adhesion strength is not random, but has well-defined functional relationships with the FN concentration and the seeding time (time allowed for the cell to establish attachment). The adhesion strength (i.e., force required to detach) of ACL cells shows a stronger dependence on FN concentration (1, 2, and 5 micrograms/ml) for short seeding times (15-30 min) than for long seeding times (38-75 min). For MCL cells, the effect of the seeding time on adhesion strength was apparent for all concentrations. For all the seeding times studied and FN concentrations used, MCL cells had higher adhesion strength than ACL cells. The adhesion strengths of ACL and MCL fibroblasts to FN are correlated to cell adhesion area.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Cruciate Ligament↗
PubMed1992

Force contribution of the LFA-1/ICAM-1 complex to T cell adhesion.

Little is known in quantitative terms about forces between cells generated during adhesion and recognition, or about the contribution of any one set of molecular associations to the development of these forces. To determine the forces involved in adhesion dependent on lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule 1 (ICAM-1), we have measured the junctional avidity between single cell pairs consisting of a cloned T cell that expresses LFA-1 and a fibroblast cell that expresses MHC class II molecules and ICAM-1 after transfection. Micromanipulation was used to induce conjugation of cell pairs and to determine the force required to separate the conjugate. T cell adhesion to three related fibroblast cell lines was compared: the parent line that does not express ICAM-1 or other LFA-1 counter-receptors, and two transfectants that have high and moderate levels of surface ICAM-1 expression. The force needed to separate the conjugates varied with the fibroblast ICAM-1 expression levels. The T cell adhesion to ICAM-1-expressing fibroblasts was strong, and the critical separation stresses measured for the three cell lines were 1.4 x 10(3) dyn/cm2 (1 dyn=10(-5) N) for the ICAM-1-negative fibroblast, 4.98 x 10(3) dyn/cm2 for the fibroblast with a moderate level of ICAM-1 expression, and 6.25 x 10(3) dyn/cm2 for the fibroblast line with the highest ICAM-1 expression. The dependence of adhesion strength on the LFA-1/ICAM-1 complex was confirmed by the use of blocking antibodies, which showed the contribution from the interaction of CD4/MHC class II to be negligible.

Animals↗
PubMed1991

The binding of anionic and nonionic surfactants to collagen through the hydrophobic effect.

The adsorption of nonionic surfactants on hide powder previously treated with anionic surfactants has been studied. The adsorption of nonionic surfactants takes place through hydrophobic interactions. A mechanism has been proposed for this interaction, assuming that the nonionic surfactant has been fixed by means of secondary adsorption (hydrophobic interaction) after the primary adsorption of the anionic surfactant (ionic and hydrophobic interaction) which makes it possible.

Adsorption↗
PubMed1988

Amino acid sequence of the BSC-1 cell growth inhibitor (polyergin) deduced from the nucleotide sequence of the cDNA.

The complete amino acid sequence of the BSC-1 cell growth inhibitor, including its precursor polypeptide, is reported. The sequence was deduced from the nucleotide sequence of the cDNA. The N-terminal amino acid sequence of the mature bioactive BSC-1 cell growth inhibitor is identical with the N-terminal sequences of the factors that have been called type beta 2 transforming growth factor and cartilage-inducing factor B, suggesting that these are identical. The complete amino acid sequence of the mature BSC-1 cell growth inhibitor differs from that of human type beta transforming growth factor in 32 of the 112 amino acids. Polyergin is proposed as the name for the BSC-1 cell growth inhibitor.

Amino Acid Sequence↗