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Lovett JE, Bowen AM, Timmel CR, Jones MW, Dilworth JR, Caprotti D, Bell SG, Wong LL, Harmer J. Structural information from orientationally selective DEER spectroscopy. Phys Chem Chem Phys 2009; 11:6840-8. [DOI: 10.1039/b907010a] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Xu F, Bell SG, Rao Z, Wong LL. Structure-activity correlations in pentachlorobenzene oxidation by engineered cytochrome P450cam. Protein Eng Des Sel 2007; 20:473-80. [DOI: 10.1093/protein/gzm028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
We have a continuing interest in applying the current knowledge of cytochrome P450cam substrate recognition to engineer the enzyme for the biotransformation of unnatural substrates with the long-term aim of applications in the synthesis of fine chemicals and bioremediation of environmental contaminants. Comparisons of the structure of target substrates with that of camphor, the natural substrate, led to the design of active-site mutants with greatly enhanced activity for the oxidation of chlorinated benzenes and selectivity of (+)-alpha-pinene oxidation. The crystal structures of the F87W/Y96F/V247L mutant with 1,3,5-trichlorobenzene or (+)-alpha-pinene bound have revealed the enzyme-substrate contacts and provided insights into the activity and selectivity patterns. The structures have also provided a novel basis for further engineering of P450cam for increased activity in the oxidation of the highly inert pentachlorobenzene and hexachlorobenzene, and increased selectivity of (+)-alpha-pinene oxidation.
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Affiliation(s)
- S G Bell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
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Abstract
The protein engineering of CYP enzymes for structure-activity studies and the oxidation of unnatural substrates for biotechnological applications will be greatly facilitated by the availability of functional, whole-cell systems for substrate oxidation. We report the construction of a tricistronic plasmid that expresses the CYP101 monooxygenase from Pseudomonas putida, and its physiological electron transfer co-factor proteins putidaredoxin reductase and putidaredoxin in Escherichia coli, giving a functional in vivo catalytic system. Wild-type CYP101 expressed in this system efficiently transforms camphor to 5-exo-hydroxycamphor without further oxidation to 5-oxo-camphor until >95% of camphor has been consumed. CYP101 mutants with increased activity for the oxidation of diphenylmethane (the Y96F-I395G mutant), styrene and ethylbenzene (the Y96F-V247L mutant) have been engineered. In particular, the Y96F-V247L mutant shows coupling efficiency of approximately 60% for styrene and ethylbenzene oxidation, with substrate oxidation rates of approximately 100/min. Escherichia coli cells transformed with tricistronic plasmids expressing these mutants readily gave 100-mg quantities of 4-hydroxydiphenylmethane and 1-phenylethanol in 24-72 h. This new in vivo system can be used for preparative scale reactions for product characterization, and will greatly facilitate directed evolution of the CYP101 enzyme for enhanced activity and selectivity of substrate oxidation.
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Affiliation(s)
- S G Bell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
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Codd GA, Metcalf JS, Ward CJ, Beattie KA, Bell SG, Kaya K, Poon GK. Analysis of cyanobacterial toxins by physicochemical and biochemical methods. J AOAC Int 2001; 84:1626-35. [PMID: 11601485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Cyanobacteria (blue-green algae) produce a wide range of low molecular weight metabolites that include potent neurotoxins, hepatotoxins, and cytotoxins. The accumulation of such toxins in freshwaters, and in brackish and marine waters presents hazards to human and animal health by a range of exposure routes. A review is presented of developments in the detection and analysis of cyanobacterial toxins, other than bioassays, including application of physicochemical, immunoassays, and enzyme-based methods. Analytical requirements are considered with reference to recently derived guideline levels for the protection of health and to the availability, or otherwise, of purified, quantitative cyanobacterial toxin standards.
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Affiliation(s)
- G A Codd
- University of Dundee, Department of Biological Sciences, UK
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Metcalf JS, Bell SG, Codd GA. Colorimetric immuno-protein phosphatase inhibition assay for specific detection of microcystins and nodularins of cyanobacteria. Appl Environ Microbiol 2001; 67:904-9. [PMID: 11157261 PMCID: PMC92665 DOI: 10.1128/aem.67.2.904-909.2001] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [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
A novel immunoassay was developed for specific detection of cyanobacterial cyclic peptide hepatotoxins which inhibit protein phosphatases. Immunoassay methods currently used for microcystin and nodularin detection and analysis do not provide information on the toxicity of microcystin and/or nodularin variants. Furthermore, protein phosphatase inhibition-based assays for these toxins are not specific and respond to other environmental protein phosphatase inhibitors, such as okadaic acid, calyculin A, and tautomycin. We addressed the problem of specificity in the analysis of protein phosphatase inhibitors by combining immunoassay-based detection of the toxins with a colorimetric protein phosphatase inhibition system in a single assay, designated the colorimetric immuno-protein phosphatase inhibition assay (CIPPIA). Polyclonal antibodies against microcystin-LR were used in conjunction with protein phosphatase inhibition, which enabled seven purified microcystin variants (microcystin-LR, -D-Asp3-RR, -LA, -LF, -LY, -LW, and -YR) and nodularin to be distinguished from okadaic acid, calyculin A, and tautomycin. A range of microcystin- and nodularin-containing laboratory strains and environmental samples of cyanobacteria were assayed by CIPPIA, and the results showed good correlation (R2 = 0.94, P < 0.00001) with the results of high-performance liquid chromatography with diode array detection for toxin analysis. The CIPPIA procedure combines ease of use and detection of low concentrations with toxicity assessment and specificity for analysis of microcystins and nodularins.
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Affiliation(s)
- J S Metcalf
- Department of Biological Sciences, University of Dundee, Dundee DD1 4HN, Scotland, United Kingdom
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Abstract
Hemoglobin plays an important physiologic role, one that begins early in fetal development. The focus of this article is hemoglobin physiology. Developmental erythropoiesis, developmental stages of hemoglobin, and postnatal erythropoiesis and hemoglobin production are discussed. The function of hemoglobin, its affinity for oxygen, and the clinical significance of the oxyhemoglobin dissociation curve are also explored.
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Affiliation(s)
- S G Bell
- All Children's Hospital Department 6500, St. Petersburg, FL 33701, USA
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Bell SG. Neonatal cardiovascular pharmacology. Neonatal Netw 1998; 17:7-15. [PMID: 9592496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neonates present with a variety of cardiovascular problems that require pharmacologic intervention. Pharmacologic manipulation of the ductus arteriosus and pharmacologic augmentation of cardiac output are the focus of this article. Guidelines for nursing assessment and clinical monitoring of neonates receiving cardiovascular drugs are included.
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Affiliation(s)
- S G Bell
- NICU, All Children's Hospital in St. Petersburg, FL 33701, USA
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Abstract
Cyanobacterial toxins are produced by terrestrial- fresh-, brackish- and sea-water cyanobacteria of cosmopolitan occurrence. These toxins present acute and chronic hazards to human and animal health and are responsible for isolated, sporadic animal fatalities (mammals, fish, birds) each year. Human health problems are associated with the ingestion of, and contact with cyanobacterial blooms and their toxins. Modes of action of cyanobacterial neurotoxins, hepatotoxins and skin irritants are considered. Recent indications of the accumulation of cyanobacterial toxins in fish, their effect on crop plants and their association with the deaths of human dialysis patients are discussed. These findings and events indicate an incomplete understanding of the exposure routes of these natural toxins and the need for greater awareness of their occurrence and properties among users of waterbodies which are prone to cyanobacterial bloom development.
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Affiliation(s)
- G A Codd
- Department of Biological Sciences, University of Dundee, UK
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Bell SG. Recombinant tissue plasminogen activator. Neonatal Netw 1996; 15:13-8. [PMID: 8932068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The widespread use of indwelling intravascular catheters, such as central venous lines and umbilical vessel catheters, has resulted in an increased number of thrombotic complications and subsequently a growing need for specific thrombolytic therapy. The use of thrombolytic agents that have a high incidence of systemic fibrinolysis is of concern, however, especially in premature neonates. Tissue plasminogen activator is a locally acting thrombolytic agent that occurs naturally in the body. Tissue plasminogen activator can now be mass-produced through recombinant DNA technology. Reports of recombinant tissue plasminogen activator use in neonates are beginning to appear in the literature. This thrombolytic agent appears to be promising for the local lysis of clots within systemic coagulopathy. However, there is a need for controlled studies of thrombolytic agents in the neonatal population.
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Bell SG. Treating neonates in pain. Am J Nurs 1996; 96:59. [PMID: 8546192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- S G Bell
- All Children's Hospital, St. Petersburg, FL
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Bell SG. Assessing pain in neonates. Am J Nurs 1995; 95:15-6. [PMID: 7503154] [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: 01/25/2023]
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Bell SG. Do neonates feel pain? Am J Nurs 1995; 95:28. [PMID: 7573205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- S G Bell
- NICU, All Children's Hospital, St. Petersburg, FL, USA
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Bell SG. The national pain management guideline: implications for neonatal intensive care. Agency for Health Care Policy and Research. Neonatal Netw 1994; 13:9-17. [PMID: 8152412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A wide range of acute pain management strategies is used in various patient populations throughout the United States. A guideline, developed by an interdisciplinary panel convened by the Agency for Health Care Policy and Research, offers health care providers a "coherent yet flexible approach to pain assessment and management for use in daily practice." The goal of the guideline and application to daily practice in the NICU are described.
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Abstract
Using open-magnitude scaling, we compared the relationships between breathlessness, inspiratory esophageal pressure swing (delta Pes), and ventilation in pregnancy and postpartum. Thirteen healthy women performed progressive cycle exercise tests at 33 +/- 2 wk gestation and 12 +/- 3 wk postpartum. Pulmonary function and maximal transdiaphragmatic pressure did not change. Minute ventilation (VE) was greater in the third trimester. This increase was entirely due to the increase in tidal volume (VT; 0.74 +/- 0.18 vs. 0.54 +/- 0.18 liters at rest, P less than 0.01; 1.56 +/- 0.3 vs. 1.24 +/- 0.24 liters at 48 W, P less than 0.001). delta Pes (15.3 +/- 3.0 vs. 11.9 +/- 3.5 cmH2O at 48 W, P less than 0.01) and breathlessness (1.8 +/- 1.4 vs. 1.0 +/- 0.9 at 48 W, P less than 0.05) were greater in the third trimester. However, the relationships between VT and delta Pes and between delta Pes and breathlessness were identical in the two conditions. The VT-tidal abdominal volume (Vab) and Vab-tidal gastric pressure swing (delta Pga) relationships were similar in the two conditions. In conclusion, the relationship between delta Pes and breathlessness is the same in the third trimester and postpartum. The increased VE is responsible for the breathlessness in the third trimester. Despite progressive abdominal distension by the gravid uterus, the VT-Vab and Vab-delta Pga relationships were the same in the two conditions.
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Affiliation(s)
- S K Field
- Department of Medicine, Foothills Hospital, Calgary, Alberta, Canada
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Bell SG. Intravenous immunoglobulin therapy in neonatal sepsis. Neonatal Netw 1991; 9:9-14. [PMID: 2000082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Codd GA, Brooks WP, Priestley IM, Poon GK, Bell SG, Fawell JK. Production, detection, and quantification of cyanobacterial toxins. ACTA ACUST UNITED AC 1989. [DOI: 10.1002/tox.2540040409] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Bell SG. Vecuronium bromide as an alternative to pancuronium bromide for neuromuscular blockade in the mechanically ventilated neonate. Neonatal Netw 1989; 7:21-5. [PMID: 2565014] [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: 01/01/2023]
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Bell SG, Ellis LJ. Use of fentanyl for sedation of mechanically ventilated neonates. Neonatal Netw 1987; 6:27-31. [PMID: 3670261] [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: 01/06/2023]
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