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Bai WJ, Estrada MA, Gartman JA, Judd AS. Enantioselective Bioreduction of Medicinally Relevant Nitrogen-Heteroaromatic Ketones. ACS Med Chem Lett 2023; 14:846-852. [PMID: 37312862 PMCID: PMC10258907 DOI: 10.1021/acsmedchemlett.3c00114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 04/27/2023] [Indexed: 06/15/2023] Open
Abstract
We herein report an enantioselective bioreduction of ketones that bear the most frequently used nitrogen-heteroaromatics in FDA-approved drugs. Ten varieties of these nitrogen-containing heterocycles were systematically investigated. Eight categories were studied for the first time and seven types were tolerated, significantly expanding the substrate scope of plant-mediated reduction. By use of purple carrots in buffered aqueous media with a simplified reaction setup, this biocatalytic transformation was achieved within 48 h at ambient temperature, offering medicinal chemists a pragmatic and scalable tool to access a broad variety of nitrogen-heteroaryl-containing chiral alcohols. With multiple reactive sites, the structurally diverse set of chiral alcohols can be used for library compound preparation, early route-scouting activities, and synthesis of other pharmaceutical molecules, favorably accelerating medicinal chemistry campaigns.
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Zhao X, Lorent K, Escobar-Zarate D, Rajagopalan R, Loomes KM, Gillespie K, Mesaros C, Estrada MA, Blair I, Winkler JD, Spinner NB, Devoto M, Pack M. Impaired Redox and Protein Homeostasis as Risk Factors and Therapeutic Targets in Toxin-Induced Biliary Atresia. Gastroenterology 2020; 159:1068-1084.e2. [PMID: 32505743 PMCID: PMC7856536 DOI: 10.1053/j.gastro.2020.05.080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 05/08/2020] [Accepted: 05/27/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND & AIMS Extrahepatic biliary atresia (BA) is a pediatric liver disease with no approved medical therapy. Recent studies using human samples and experimental modeling suggest that glutathione redox metabolism and heterogeneity play a role in disease pathogenesis. We sought to dissect the mechanistic basis of liver redox variation and explore how other stress responses affect cholangiocyte injury in BA. METHODS We performed quantitative in situ hepatic glutathione redox mapping in zebrafish larvae carrying targeted mutations in glutathione metabolism genes and correlated these findings with sensitivity to the plant-derived BA-linked toxin biliatresone. We also determined whether genetic disruption of HSP90 protein quality control pathway genes implicated in human BA altered biliatresone toxicity in zebrafish and human cholangiocytes. An in vivo screening of a known drug library was performed to identify novel modifiers of cholangiocyte injury in the zebrafish experimental BA model, with subsequent validation. RESULTS Glutathione metabolism gene mutations caused regionally distinct changes in the redox potential of cholangiocytes that differentially sensitized them to biliatresone. Disruption of human BA-implicated HSP90 pathway genes sensitized zebrafish and human cholangiocytes to biliatresone-induced injury independent of glutathione. Phosphodiesterase-5 inhibitors and other cyclic guanosine monophosphate signaling activators worked synergistically with the glutathione precursor N-acetylcysteine in preventing biliatresone-induced injury in zebrafish and human cholangiocytes. Phosphodiesterase-5 inhibitors enhanced proteasomal degradation and required intact HSP90 chaperone. CONCLUSION Regional variation in glutathione metabolism underlies sensitivity to the biliary toxin biliatresone and may account for the reported association between BA transplant-free survival and glutathione metabolism gene expression. Human BA can be causatively linked to genetic modulation of protein quality control. Combined treatment with N-acetylcysteine and cyclic guanosine monophosphate signaling enhancers warrants further investigation as therapy for BA.
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Affiliation(s)
- Xiao Zhao
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristin Lorent
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Diana Escobar-Zarate
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ramakrishnan Rajagopalan
- Division of Genomic Diagnostics, Department of Pathology, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Kathleen M. Loomes
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Kevin Gillespie
- Department of System Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Clementina Mesaros
- Department of System Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ian Blair
- Department of System Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeffrey D. Winkler
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy B. Spinner
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Marcella Devoto
- Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, PA, USA.,Departments of Pediatrics and of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Translational and Precision Medicine, University La Sapienza, Rome, Italy
| | - Michael Pack
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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Wangtrakuldee P, Adeniji AO, Zang T, Duan L, Khatri B, Twenter BM, Estrada MA, Higgins TF, Winkler JD, Penning TM. A 3-(4-nitronaphthen-1-yl) amino-benzoate analog as a bifunctional AKR1C3 inhibitor and AR antagonist: Head to head comparison with other advanced AKR1C3 targeted therapeutics. J Steroid Biochem Mol Biol 2019; 192:105283. [PMID: 30641225 PMCID: PMC6625945 DOI: 10.1016/j.jsbmb.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/02/2019] [Accepted: 01/04/2019] [Indexed: 01/23/2023]
Abstract
Drugs used for the treatment of castration resistant prostate cancer (CRPC) include Abiraterone acetate (Zytiga®) and Enzalutamide (XTANDI®). However, these drugs provide clinical benefit in metastatic disease for only a brief period before drug resistance emerges. One mechanism of drug resistance involves the overexpression of type 5 17-β-hydroxysteroid dehydrogenase (aldo-keto reductase 1C3 or AKR1C3), a major enzyme responsible for the formation of intratumoral androgens that activate the androgen receptor (AR). 3-((4-Nitronaphthalen-1-yl)amino)benzoic acid 1 is a "first-in-class" AKR1C3 competitive inhibitor and AR antagonist. Compound 1 was compared in a battery of in vitro studies with structurally related N-naphthyl-aminobenzoates, and AKR1C3 targeted therapeutics e.g. GTx-560 and ASP9521, as well as with R-bicalutamide, enzalutamide and abiraterone acetate. Compound 1 was the only naphthyl derivative that was a selective AKR1C3 inhibitor and AR antagonist in direct competitive binding assays and in AR driven reporter gene assays. GTx-560 displayed weak activity as a direct AR antagonist but had high potency in the AR reporter gene assay consistent with its ability to inhibit the co-activator function of AKR1C3. By contrast ASP9521 did not act as either an AR antagonist or block AR reporter gene activity. Compound 1 was the only compound that showed comparable potency to inhibit AKR1C3 and act as a direct AR antagonist. Compound 1 blocked the formation of testosterone in LNCaP-AKR1C3 cells, and the expression of PSA driven by the AKR1C3 substrate (4-androstene-3,17-dione) and by an AR agonist, 5α-dihydrotestosterone consistent with its bifunctional role. Compound 1 blocked the nuclear translocation of the AR at similar concentrations to enzalutamide and caused disappearance of the AR from cell lysates. R-biaclutamide and enzalutamide inhibited AKR1C3 at concentrations 200x greater than compound 1, suggesting that its bifunctionality can be explained by a shared pharmacophore that can be optimized.
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Affiliation(s)
- Phumvadee Wangtrakuldee
- Department of Systems Pharmacology and Translational Therapeutics and the Center for Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Adegoke O Adeniji
- Department of Systems Pharmacology and Translational Therapeutics and the Center for Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Tianzhu Zang
- Department of Systems Pharmacology and Translational Therapeutics and the Center for Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Ling Duan
- Department of Systems Pharmacology and Translational Therapeutics and the Center for Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Buddha Khatri
- Department of Chemistry, University of Pennsylvania, 231 S. 34thStreet, Philadelphia, PA 19104-6323, USA
| | - Barry M Twenter
- Department of Chemistry, University of Pennsylvania, 231 S. 34thStreet, Philadelphia, PA 19104-6323, USA
| | - Michelle A Estrada
- Department of Chemistry, University of Pennsylvania, 231 S. 34thStreet, Philadelphia, PA 19104-6323, USA
| | - Tyler F Higgins
- Department of Chemistry, University of Pennsylvania, 231 S. 34thStreet, Philadelphia, PA 19104-6323, USA
| | - Jeffrey D Winkler
- Department of Chemistry, University of Pennsylvania, 231 S. 34thStreet, Philadelphia, PA 19104-6323, USA
| | - Trevor M Penning
- Department of Systems Pharmacology and Translational Therapeutics and the Center for Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, 1315 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA.
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Grasso M, Estrada MA, Berrios KN, Winkler JD, Marmorstein R. N-(7-Cyano-6-(4-fluoro-3-(2-(3-(trifluoromethyl)phenyl)acetamido)phenoxy)benzo[d]thiazol-2-yl)cyclopropanecarboxamide (TAK632) Promotes Inhibition of BRAF through the Induction of Inhibited Dimers. J Med Chem 2018; 61:5034-5046. [PMID: 29727562 DOI: 10.1021/acs.jmedchem.8b00499] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
BRAFV600E is the most common activating mutation in melanoma and patients treated with BRAFV600E inhibitors all develop resistance within one year. A significant resistance pathway is paradoxical activation (transactivation) involving BRAF dimers, whereby an inhibitor bound protein subunit allosterically activates the other subunit. We recently reported on dimeric BRAFV600E -selective vemurafenib inhibitors that stabilize an inactive αC-out/αC-out homodimeric conformation with improved inhibitor potency and selectivity in vitro. We set out to extend this strategy to target RAF homo- and heterodimers with the pan-RAF inhibitor TAK632 in dimeric configuration. Surprisingly, we find that monomeric TAK632 induces an active αC-in/αC-in BRAF dimer conformation, while dimeric TAK inhibitors cannot promote BRAF dimers and have significantly compromised potency in vitro. These studies uncover the intimate connection between BRAF dimerization and TAK632 mode of inhibition and highlight the importance of understanding the impact of BRAF inhibitors on kinase dimerization.
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Affiliation(s)
- Michael Grasso
- Department of Biochemistry and Biophysics and the Abramson Family Cancer Research Institute, Perelman School of Medicine , University of Pennsylvania , 421 Curie Boulevard , Philadelphia , Pennsylvania 19104 , United States.,Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Michelle A Estrada
- Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Kiara N Berrios
- Department of Biochemistry and Biophysics and the Abramson Family Cancer Research Institute, Perelman School of Medicine , University of Pennsylvania , 421 Curie Boulevard , Philadelphia , Pennsylvania 19104 , United States
| | - Jeffrey D Winkler
- Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Ronen Marmorstein
- Department of Biochemistry and Biophysics and the Abramson Family Cancer Research Institute, Perelman School of Medicine , University of Pennsylvania , 421 Curie Boulevard , Philadelphia , Pennsylvania 19104 , United States.,Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
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Estrada MA, Zhao X, Lorent K, Kriegermeier A, Nagao SA, Berritt S, Wells RG, Pack M, Winkler JD. Synthesis and Structure-Activity Relationship Study of Biliatresone, a Plant Isoflavonoid That Causes Biliary Atresia. ACS Med Chem Lett 2018; 9:61-64. [PMID: 29348813 DOI: 10.1021/acsmedchemlett.7b00479] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 12/14/2017] [Indexed: 01/27/2023] Open
Abstract
We report the first synthesis of the plant isoflavonoid biliatresone. The convergent synthesis has been applied to the synthesis of several analogs, which have facilitated the first structure-activity relationship study for this environmental toxin that, on ingestion, recapitulates the phenotype of biliary atresia.
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Affiliation(s)
- Michelle A. Estrada
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Xiao Zhao
- Department
of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Kristin Lorent
- Department
of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Alyssa Kriegermeier
- Division
of Gastroenterology, Hepatology and Nutrition, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, United States
| | - Seika A. Nagao
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Simon Berritt
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Rebecca G. Wells
- Department
of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department
of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department
of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Michael Pack
- Department
of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Cell and
Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jeffrey D. Winkler
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Grasso M, Estrada MA, Ventocilla C, Samanta M, Maksimoska J, Villanueva J, Winkler JD, Marmorstein R. Chemically Linked Vemurafenib Inhibitors Promote an Inactive BRAF V600E Conformation. ACS Chem Biol 2016; 11:2876-2888. [PMID: 27571413 PMCID: PMC5108658 DOI: 10.1021/acschembio.6b00529] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The BRAF kinase, within the mitogen activated protein kinase (MAPK) signaling pathway, harbors activating mutations in about half of melanomas and to a significant extent in many other cancers. A single valine to glutamic acid substitution at residue 600 (BRAFV600E) accounts for about 90% of these activating mutations. While BRAFV600E-selective small molecule inhibitors, such as debrafenib and vemurafenib, have shown therapeutic benefit, almost all patients develop resistance. Resistance often arises through reactivation of the MAPK pathway, typically through mutation of upstream RAS, downstream MEK, or splicing variants. RAF kinases signal as homo- and heterodimers, and another complication associated with small molecule BRAFV600E inhibition is drug-induced allosteric activation of a wild-type RAF subunit (BRAF or CRAF) of the kinase dimer, a process called "transactivation" or "paradoxical activation." Here, we used BRAFV600E and vemurafenib as a model system to develop chemically linked kinase inhibitors to lock RAF dimers in an inactive conformation that cannot undergo transactivation. This structure-based design effort resulted in the development of Vem-BisAmide-2, a compound containing two vemurafenib molecules connected by a bis amide linker. We show that Vem-BisAmide-2 has comparable inhibitory potency as vemurafenib to BRAFV600E both in vitro and in cells but promotes an inactive dimeric BRAFV600E conformation unable to undergo transactivation. The crystal structure of a BRAFV600E/Vem-BisAmide-2 complex and associated biochemical studies reveal the molecular basis for how Vem-BisAmide-2 mediates selectivity for an inactive over an active dimeric BRAFV600E conformation. These studies have implications for targeting BRAFV600E/RAF heterodimers and other kinase dimers for therapy.
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Affiliation(s)
- Michael Grasso
- Department of Biochemistry and Biophysics and the Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104, USA,Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Michelle A. Estrada
- Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Christian Ventocilla
- Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Minu Samanta
- Wistar Institute, Philadelphia, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Jasna Maksimoska
- Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Jessie Villanueva
- Wistar Institute, Philadelphia, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Jeffrey D. Winkler
- Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Ronen Marmorstein
- Department of Biochemistry and Biophysics and the Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104, USA,Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, PA 19104, USA
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Silva J, Aguilar C, Ayala G, Estrada MA, Garza-Ramos U, Lara-Lemus R, Ledezma L. TLA-1: a new plasmid-mediated extended-spectrum beta-lactamase from Escherichia coli. Antimicrob Agents Chemother 2000; 44:997-1003. [PMID: 10722503 PMCID: PMC89804 DOI: 10.1128/aac.44.4.997-1003.2000] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two beta-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single beta-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 beta-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5alpha. Sequencing of the bla(TLA-1) gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A beta-lactamases: (70)SXXK, (130)SDN, and (234)KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A beta-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A beta-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 beta-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum beta-lactamase of Ambler class A.
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Affiliation(s)
- J Silva
- Departamento de Resistencia Bacteriana, Instituto Nacional de Salud Pública, Centro de Investigaciones Sobre Enfermedades Infecciosas, Cuernavaca, Morelos, México.
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Silva J, Aguilar C, Estrada MA, Echániz G, Carnalla N, Soto A, López-Antuñano FJ. Susceptibility to new beta-lactams of enterobacterial extended-spectrum beta-lactamase (ESBL) producers and penicillin-resistant Streptococcus pneumoniae in Mexico. J Chemother 1998; 10:102-7. [PMID: 9603634 DOI: 10.1179/joc.1998.10.2.102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The activities of several beta-lactam antimicrobial agents, aminoglycosides and ciprofloxacin, were determined against 62 clinical isolates of enterobacteria resistant to oxyimino cephalosporins (extended-spectrum beta-lactamase producers), collected during 1991 to 1993, and 16 penicillin-resistant invasive isolates of Streptococcus pneumoniae collected during 1994-1996. The numbers and percentages of susceptible enterobacterial strains to tested antibiotics were: imipenem 60 (97%), ciprofloxacin 57 (92%), cefepime 56 (90%), cefpirome 34 (55%), aztreonam 13 (21%), cefotaxime 7 (11%), ceftazidime 0 (0%), amikacin 11 (18%) and gentamicin 16 (26%). Despite the fact that these strains had never been exposed previously to cefepime or cefpirome, the susceptibility was 90% and 55%, respectively. No penicillin-resistant strains of S. pneumoniae were susceptible to cefotaxime, imipenem or cefepime. Only one strain was susceptible to ceftazidime and 4 (25%) were susceptible to cefpirome. Erythromycin showed the greatest activity with 12 (75%) susceptible strains.
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Affiliation(s)
- J Silva
- Instituto Nacional de Salud Pública, Centro de Investigaciones Sobre Enfermedades Infecciosas, Departamento de Genética Bacteriana, Cuernavaca, Mexico.
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Zilianti M, Segura CL, Cabello F, Benzaquen J, Romero M, Estrada MA. Studies on fetal bradycardia during birth process. I. Obstet Gynecol 1973; 42:831-9. [PMID: 4757589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Zilianti M, Segura CL, Cabello F, Benzaquen J, Caicedo CJ, Estrada MA. Studies on fetal bradycardia during birth process. II. Obstet Gynecol 1973; 42:840-3. [PMID: 4757590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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