Ana Ríos | Universidad Nacional de la Amazonia Peruana (original) (raw)

Papers by Ana Ríos

Research paper thumbnail of Glycine Enolates: The Large Effect of Iminium Ion Formation on α-Amino Carbon Acidity

Journal of The American Chemical Society, 2001

We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of g... more We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of glycine methyl ester by the simple ketone acetone that is the result of a 10 7 -fold larger acidity constant K CH for carbon deprotonation of the iminium ion adduct IH + (pK CH ) 14) than for deprotonation of N-protonated glycine methyl ester GH + (pK CH ) 21).

Research paper thumbnail of Glycine Enolates: The Large Effect of Iminium Ion Formation on α-Amino Carbon Acidity

Journal of The American Chemical Society, 2001

We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of g... more We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of glycine methyl ester by the simple ketone acetone that is the result of a 10 7 -fold larger acidity constant K CH for carbon deprotonation of the iminium ion adduct IH + (pK CH ) 14) than for deprotonation of N-protonated glycine methyl ester GH + (pK CH ) 21).

Research paper thumbnail of Biological Enolates: Generation and Stability of the Enolate of N-Protonated Glycine Methyl Ester in Water

Journal of The American Chemical Society, 1997

We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-pr... more We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-protonated glycine methyl ester 1 that is easily followed at 25°C and neutral pD and an estimated value of 21 for the pK a for the R-protons of this simple amino acid derivative.

Research paper thumbnail of Biological Enolates: Generation and Stability of the Enolate of N-Protonated Glycine Methyl Ester in Water

Journal of The American Chemical Society, 1997

We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-pr... more We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-protonated glycine methyl ester 1 that is easily followed at 25°C and neutral pD and an estimated value of 21 for the pK a for the R-protons of this simple amino acid derivative.

Research paper thumbnail of Formation and Stability of Organic Zwitterions in Aqueous Solution: Enolates of the Amino Acid Glycine and Its Derivatives

Journal of The American Chemical Society, 2000

... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained d... more ... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained during ... as the y-intercepts of plots (not shown) of k ex (s - 1 ) against the total buffer concentration ... s - 1 (Results) is 4-fold larger than k w = 5 × 10 - 10 s - 1 for deprotonation of acetone ...

Research paper thumbnail of Formation and Stability of Organic Zwitterions in Aqueous Solution: Enolates of the Amino Acid Glycine and Its Derivatives

Journal of The American Chemical Society, 2000

... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained d... more ... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained during ... as the y-intercepts of plots (not shown) of k ex (s - 1 ) against the total buffer concentration ... s - 1 (Results) is 4-fold larger than k w = 5 × 10 - 10 s - 1 for deprotonation of acetone ...

Research paper thumbnail of Management and outcome of children with skin and soft tissue abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus

Pediatric Infectious Disease Journal, 2004

Research paper thumbnail of Mycoplasma pneumoniae Induces Host-Dependent Pulmonary Inflammation and Airway Obstruction in Mice

Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is... more Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is a common etiologic agent of acute respiratory infection in children and adults that has been associated with wheezing in 20-40% of individuals. The current study was undertaken to elucidate the host-dependent pulmonary and immunologic response to M. pneumoniae respiratory infection by studying mice with different immunogenetic backgrounds (BALB/c mice versus C57BL/6 mice). After M. pneumoniae infection, only BALB/c mice developed significant airway obstruction (AO) compared with controls. M. pneumoniae-infected BALB/c mice manifested significantly elevated airway hyperresponsiveness (AHR) compared with C57BL/6 mice 4 and 7 d after inoculation as well as BALB/c control mice. Compared with C57BL/6 mice, BALB/c mice developed worse pulmonary inflammation, including greater peribronchial infiltrates. Infected BALB/c mice had significantly higher concentrations of tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-1beta, IL-6, IL-12, KC (functional IL-8), and macrophage inflammatory protein 1alpha in the bronchoalveolar lavage fluid compared with infected C57BL/6 mice. No differences in IL-2, IL-4, IL-5, IL-10, and granulocyte/macrophage colony-stimulating factor concentrations were found. The mice in this study exhibited host-dependent infection-related AO and AHR associated with chemokine and T-helper type (Th)1 pulmonary host response and not Th2 response after M. pneumoniae infection.

Research paper thumbnail of Respiratory syncytial virus-induced acute and chronic airway disease is independent of genetic background: An experimental murine model

Virology Journal, 2005

Background: Respiratory syncytial virus (RSV) is the leading respiratory viral pathogen in young ... more Background: Respiratory syncytial virus (RSV) is the leading respiratory viral pathogen in young children worldwide. RSV disease is associated with acute airway obstruction (AO), long-term airway hyperresponsiveness (AHR), and chronic lung inflammation. Using two different mouse strains, this study was designed to determine whether RSV disease patterns are host-dependent. C57BL/6 and BALB/c mice were inoculated with RSV and followed for 77 days. RSV loads were measured by plaque assay and polymerase chain reaction (PCR) in bronchoalveolar lavage (BAL) and whole lung samples; cytokines were measured in BAL samples. Lung inflammation was evaluated with a histopathologic score (HPS), and AO and AHR were determined by plethysmography.

Research paper thumbnail of Antimicrobial and Immunologic Activities of Clarithromycin in a Murine Model of Mycoplasma pneumoniae-Induced Pneumonia

Antimicrobial Agents and Chemotherapy, 2003

Because macrolide antibiotics are hypothesized to possess immunomodulatory activity independent o... more Because macrolide antibiotics are hypothesized to possess immunomodulatory activity independent of their antimicrobial activity, we evaluated the immunomodulatory effect of clarithromycin in a murine model of lung inflammation induced by either live or UV-killed Mycoplasma pneumoniae. BALB/c mice were intranasally inoculated once with live or UV-killed M. pneumoniae. Clarithromycin (25 mg/kg of body weight) or placebo was subcutaneously administered once daily in both groups of mice. In mice infected with live M. pneumoniae, clarithromycin treatment significantly reduced quantitative M. pneumoniae bronchoalveolar lavage (BAL) culture, pulmonary histopathologic scores (HPS), and airway resistance-obstruction (as measured by plethysmography) compared with placebo. Concentrations of tumor necrosis factor alpha, gamma interferon, interleukin-6 (IL-6), mouse KC (functional IL-8), JE/MCP-1, and MIP-1␣ in BAL fluid were also significantly decreased in mice infected with live M. pneumoniae given clarithromycin. In contrast, mice inoculated with UVkilled M. pneumoniae had no significant reduction in HPS, airway resistance-obstruction, or BAL cytokine or chemokine concentrations in response to clarithromycin administration. Clarithromycin therapy demonstrated beneficial effects (microbiologic, histologic, respiratory, and immunologic) on pneumonia in the mice infected with live M. pneumoniae; this was not observed in the mice inoculated with UV-killed M. pneumoniae.

Research paper thumbnail of Effect of clarithromycin on cytokines and chemokines in children with an acute exacerbation of recurrent wheezing: a double-blind, randomized, placebo-controlled trial

Annals of Allergy Asthma & Immunology, 2006

Clarithromycin is postulated to possess immunomodulatory properties in addition to its antimicrob... more Clarithromycin is postulated to possess immunomodulatory properties in addition to its antimicrobial activity. To evaluate the effect of clarithromycin on serum and nasopharyngeal cytokine and chemokine concentrations in children with an acute exacerbation of recurrent wheezing. Children with a history of recurrent wheezing or asthma and who presented with an acute exacerbation of wheezing were enrolled in a double-blind, randomized trial of clarithromycin vs placebo. Concentrations of tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-1beta (IL-1beta), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, granulocyte-macrophage colony-stimulating factor, RANTES, eotaxin, macrophage inflammatory protein 1alpha, macrophage inflammatory protein 1beta, and monocyte chemoattractant protein 1 were measured in serum and/or nasopharyngeal aspirates before, during, and after therapy. Mycoplasma pneumoniae and Chlamydophila pneumoniae infection were evaluated for by polymerase chain reaction and serologic testing. Nasopharyngeal concentrations of TNF-alpha, IL-1beta, and IL-10 were significantly and persistently lower in children treated with clarithromycin compared with placebo. There tended to be a greater effect of clarithromycin on nasopharyngeal cytokine concentrations in patients with evidence of M. pneumoniae or C. pneumoniae infection. No significant differences were detected in serum cytokines for children treated with clarithromycin compared with placebo. Clarithromycin therapy reduces mucosal TNF-alpha, IL-1beta, and IL-10 concentrations in children with an acute exacerbation of recurrent wheezing.

Research paper thumbnail of Glycine Enolates: The Large Effect of Iminium Ion Formation on α-Amino Carbon Acidity

Journal of The American Chemical Society, 2001

We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of g... more We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of glycine methyl ester by the simple ketone acetone that is the result of a 10 7 -fold larger acidity constant K CH for carbon deprotonation of the iminium ion adduct IH + (pK CH ) 14) than for deprotonation of N-protonated glycine methyl ester GH + (pK CH ) 21).

Research paper thumbnail of Glycine Enolates: The Large Effect of Iminium Ion Formation on α-Amino Carbon Acidity

Journal of The American Chemical Society, 2001

We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of g... more We wish to report extraordinarily efficient catalysis of deprotonation of the R-amino carbon of glycine methyl ester by the simple ketone acetone that is the result of a 10 7 -fold larger acidity constant K CH for carbon deprotonation of the iminium ion adduct IH + (pK CH ) 14) than for deprotonation of N-protonated glycine methyl ester GH + (pK CH ) 21).

Research paper thumbnail of Biological Enolates: Generation and Stability of the Enolate of N-Protonated Glycine Methyl Ester in Water

Journal of The American Chemical Society, 1997

We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-pr... more We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-protonated glycine methyl ester 1 that is easily followed at 25°C and neutral pD and an estimated value of 21 for the pK a for the R-protons of this simple amino acid derivative.

Research paper thumbnail of Biological Enolates: Generation and Stability of the Enolate of N-Protonated Glycine Methyl Ester in Water

Journal of The American Chemical Society, 1997

We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-pr... more We report the formation of the amino acid ester enolate 2 by base-catalyzed deprotonation of N-protonated glycine methyl ester 1 that is easily followed at 25°C and neutral pD and an estimated value of 21 for the pK a for the R-protons of this simple amino acid derivative.

Research paper thumbnail of Formation and Stability of Organic Zwitterions in Aqueous Solution: Enolates of the Amino Acid Glycine and Its Derivatives

Journal of The American Chemical Society, 2000

... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained d... more ... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained during ... as the y-intercepts of plots (not shown) of k ex (s - 1 ) against the total buffer concentration ... s - 1 (Results) is 4-fold larger than k w = 5 × 10 - 10 s - 1 for deprotonation of acetone ...

Research paper thumbnail of Formation and Stability of Organic Zwitterions in Aqueous Solution: Enolates of the Amino Acid Glycine and Its Derivatives

Journal of The American Chemical Society, 2000

... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained d... more ... Figure 1 Representative partial 1 H NMR spectra at 500 MHz of betaine methyl ester obtained during ... as the y-intercepts of plots (not shown) of k ex (s - 1 ) against the total buffer concentration ... s - 1 (Results) is 4-fold larger than k w = 5 × 10 - 10 s - 1 for deprotonation of acetone ...

Research paper thumbnail of Management and outcome of children with skin and soft tissue abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus

Pediatric Infectious Disease Journal, 2004

Research paper thumbnail of Mycoplasma pneumoniae Induces Host-Dependent Pulmonary Inflammation and Airway Obstruction in Mice

Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is... more Respiratory tract infections result in wheezing in a subset of patients. Mycoplasma pneumoniae is a common etiologic agent of acute respiratory infection in children and adults that has been associated with wheezing in 20-40% of individuals. The current study was undertaken to elucidate the host-dependent pulmonary and immunologic response to M. pneumoniae respiratory infection by studying mice with different immunogenetic backgrounds (BALB/c mice versus C57BL/6 mice). After M. pneumoniae infection, only BALB/c mice developed significant airway obstruction (AO) compared with controls. M. pneumoniae-infected BALB/c mice manifested significantly elevated airway hyperresponsiveness (AHR) compared with C57BL/6 mice 4 and 7 d after inoculation as well as BALB/c control mice. Compared with C57BL/6 mice, BALB/c mice developed worse pulmonary inflammation, including greater peribronchial infiltrates. Infected BALB/c mice had significantly higher concentrations of tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-1beta, IL-6, IL-12, KC (functional IL-8), and macrophage inflammatory protein 1alpha in the bronchoalveolar lavage fluid compared with infected C57BL/6 mice. No differences in IL-2, IL-4, IL-5, IL-10, and granulocyte/macrophage colony-stimulating factor concentrations were found. The mice in this study exhibited host-dependent infection-related AO and AHR associated with chemokine and T-helper type (Th)1 pulmonary host response and not Th2 response after M. pneumoniae infection.

Research paper thumbnail of Respiratory syncytial virus-induced acute and chronic airway disease is independent of genetic background: An experimental murine model

Virology Journal, 2005

Background: Respiratory syncytial virus (RSV) is the leading respiratory viral pathogen in young ... more Background: Respiratory syncytial virus (RSV) is the leading respiratory viral pathogen in young children worldwide. RSV disease is associated with acute airway obstruction (AO), long-term airway hyperresponsiveness (AHR), and chronic lung inflammation. Using two different mouse strains, this study was designed to determine whether RSV disease patterns are host-dependent. C57BL/6 and BALB/c mice were inoculated with RSV and followed for 77 days. RSV loads were measured by plaque assay and polymerase chain reaction (PCR) in bronchoalveolar lavage (BAL) and whole lung samples; cytokines were measured in BAL samples. Lung inflammation was evaluated with a histopathologic score (HPS), and AO and AHR were determined by plethysmography.

Research paper thumbnail of Antimicrobial and Immunologic Activities of Clarithromycin in a Murine Model of Mycoplasma pneumoniae-Induced Pneumonia

Antimicrobial Agents and Chemotherapy, 2003

Because macrolide antibiotics are hypothesized to possess immunomodulatory activity independent o... more Because macrolide antibiotics are hypothesized to possess immunomodulatory activity independent of their antimicrobial activity, we evaluated the immunomodulatory effect of clarithromycin in a murine model of lung inflammation induced by either live or UV-killed Mycoplasma pneumoniae. BALB/c mice were intranasally inoculated once with live or UV-killed M. pneumoniae. Clarithromycin (25 mg/kg of body weight) or placebo was subcutaneously administered once daily in both groups of mice. In mice infected with live M. pneumoniae, clarithromycin treatment significantly reduced quantitative M. pneumoniae bronchoalveolar lavage (BAL) culture, pulmonary histopathologic scores (HPS), and airway resistance-obstruction (as measured by plethysmography) compared with placebo. Concentrations of tumor necrosis factor alpha, gamma interferon, interleukin-6 (IL-6), mouse KC (functional IL-8), JE/MCP-1, and MIP-1␣ in BAL fluid were also significantly decreased in mice infected with live M. pneumoniae given clarithromycin. In contrast, mice inoculated with UVkilled M. pneumoniae had no significant reduction in HPS, airway resistance-obstruction, or BAL cytokine or chemokine concentrations in response to clarithromycin administration. Clarithromycin therapy demonstrated beneficial effects (microbiologic, histologic, respiratory, and immunologic) on pneumonia in the mice infected with live M. pneumoniae; this was not observed in the mice inoculated with UV-killed M. pneumoniae.

Research paper thumbnail of Effect of clarithromycin on cytokines and chemokines in children with an acute exacerbation of recurrent wheezing: a double-blind, randomized, placebo-controlled trial

Annals of Allergy Asthma & Immunology, 2006

Clarithromycin is postulated to possess immunomodulatory properties in addition to its antimicrob... more Clarithromycin is postulated to possess immunomodulatory properties in addition to its antimicrobial activity. To evaluate the effect of clarithromycin on serum and nasopharyngeal cytokine and chemokine concentrations in children with an acute exacerbation of recurrent wheezing. Children with a history of recurrent wheezing or asthma and who presented with an acute exacerbation of wheezing were enrolled in a double-blind, randomized trial of clarithromycin vs placebo. Concentrations of tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-1beta (IL-1beta), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, granulocyte-macrophage colony-stimulating factor, RANTES, eotaxin, macrophage inflammatory protein 1alpha, macrophage inflammatory protein 1beta, and monocyte chemoattractant protein 1 were measured in serum and/or nasopharyngeal aspirates before, during, and after therapy. Mycoplasma pneumoniae and Chlamydophila pneumoniae infection were evaluated for by polymerase chain reaction and serologic testing. Nasopharyngeal concentrations of TNF-alpha, IL-1beta, and IL-10 were significantly and persistently lower in children treated with clarithromycin compared with placebo. There tended to be a greater effect of clarithromycin on nasopharyngeal cytokine concentrations in patients with evidence of M. pneumoniae or C. pneumoniae infection. No significant differences were detected in serum cytokines for children treated with clarithromycin compared with placebo. Clarithromycin therapy reduces mucosal TNF-alpha, IL-1beta, and IL-10 concentrations in children with an acute exacerbation of recurrent wheezing.